Publications - 2021
BHLHE40 Regulates the T-Cell Effector Function Required for Tumor Microenvironment Remodeling and Immune Checkpoint-Therapy Efficacy |
| Avery J Salmon, Alexander S Shavkunov, Qi Miao, Nicholas N Jarjour, Sunita Keshari, Ekaterina Esaulova, Charmelle D Williams, Jeffrey P Ward, Anna M Highsmith, Josue E Pineda, Reshma Taneja, Ken Chen, Brian T Edelson, Matthew M Gubin |
| Cancer Immunol Res. 2022 Feb 18;canimm.0129.2021. doi: 10.1158/2326-6066.CIR-21-0129. |
| Abstract |
| Immune checkpoint therapy (ICT) using antibody blockade of PD-1 or CTLA-4 can provoke T cell-dependent antitumor activity that generates durable clinical responses in some patients. The epigenetic and transcriptional features that T cells require for efficacious ICT remain to be fully elucidated. Herein, we report that anti-PD-1 and anti-CTLA-4 ICT induce upregulation of the transcription factor BHLHE40 in tumor antigen-specific CD8+ and CD4+ T cells and that T cells require BHLHE40 for effective ICT in mice bearing immune-edited tumors. Single-cell RNA sequencing of intratumoral immune cells in BHLHE40-deficient mice revealed differential ICT-induced immune cell remodeling. The BHLHE40-dependent gene expression changes indicated dysregulated metabolism, NF-κB signaling, and IFN-γ response within certain subpopulations of CD4+ and CD8+ T cells. Intratumoral CD4+ and CD8+ T cells from BHLHE40-deficient mice exhibited higher expression of the inhibitory receptor gene Tigit and displayed alterations in expression of genes encoding chemokine/chemokine receptors and granzyme family members. Mice lacking BHLHE40 had reduced ICT-driven IFN-γ production by CD4+ and CD8+ T cells and defects in ICT-induced remodeling of macrophages from a CX3CR1+CD206+ subpopulation to an iNOS+ subpopulation that is typically observed during effective ICT. Although both anti-PD-1 and anti-CTLA-4 ICT in BHLHE40-deficient mice led to the same outcome-tumor outgrowth-several BHLHE40-dependent alterations were specific to the ICT that was used. Our results reveal a crucial role for BHLHE40 in effective ICT and suggest that BHLHE40 may be a predictive or prognostic biomarker for ICT efficacy and a potential therapeutic target. |
Alpha-Ketoglutarate dietary supplementation to improve health in humans |
| Bibek Gyanwali, Zi Xiang Lim, Janjira Soh, Clarissa Lim, Shou Ping Guan, Jorming Goh, Andrea B Maier, Brian K Kennedy |
| Trends Endocrinol Metab. 2022 Feb;33(2):136-146. doi: 10.1016/j.tem.2021.11.003. Epub 2021 Dec 21. |
| Abstract |
| Alpha-ketoglutarate (AKG) is an intermediate in the Krebs cycle involved in various metabolic and cellular pathways. As an antioxidant, AKG interferes in nitrogen and ammonia balance, and affects epigenetic and immune regulation. These pleiotropic functions of AKG suggest it may also extend human healthspan. Recent studies in worms and mice support this concept. A few studies published in the 1980s and 1990s in humans suggested the potential benefits of AKG in muscle growth, wound healing, and in promoting faster recovery after surgery. So far there are no recently published studies demonstrating the role of AKG in treating aging and age-related diseases; hence, further clinical studies are required to better understand the role of AKG in humans. This review will discuss the regulatory role of AKG in aging, as well as its potential therapeutic use in humans to treat age-related diseases. |
Calcium Channel Splice Variants and Their Effects in Brain and Cardiovascular Function |
| Sean Qing Zhang Yeow, Kelvin Wei Zhern Loh, Tuck Wah Soong |
| Adv Exp Med Biol. 2021;1349:67-86. doi: 10.1007/978-981-16-4254-8_5. |
| Abstract |
| Calcium ions serve as an important intracellular messenger in many diverse pathways, ranging from excitation coupling in muscles to neurotransmitter release in neurons. Physiologically, the concentration of free intracellular Ca2+ is up to 10,000 times less than that of the extracellular concentration, and increases of 10- to 100-fold in intracellular Ca2+ are observed during signaling events. Voltage-gated calcium channels (VGCCs) located on the plasma membrane serve as one of the main ways in which Ca2+ is able to enter the cell. Given that Ca2+ functions as a ubiquitous intracellular messenger, it is imperative that VGCCs are under tight regulation to ensure that intracellular Ca2+ concentration remains within the physiological range. In this chapter, we explore VGCCs' inherent control of Ca2+ entry as well as the effects of alternative splicing in CaV2.1 and posttranslational modifications of CaV1.2/CaV1.3 such as phosphorylation and ubiquitination. Deviation from this physiological range will result in deleterious effects known as calcium channelopathies, some of which will be explored in this chapter. |
Targeting the molecular & cellular pillars of human aging with exercise |
| Jorming Goh, Esther Wong, Janjira Soh, Andrea Britta Maier, Brian Keith Kennedy |
| FEBS J. 2021 Dec 30. doi: 10.1111/febs.16337. |
| Abstract |
| Biological aging is the main driver of age-associated chronic diseases. In 2014, the United States National Institute of Aging (NIA) sponsored a meeting between several investigators in the field of aging biology, who identified seven biological pillars of aging and a consensus review, “Geroscience: Linking Aging to Chronic Disease,” was published. The pillars of aging demonstrated the conservation of aging pathways in diverse model organisms and thus represent a useful framework with which to study human aging. In this present review, we revisit the seven pillars of aging from the perspective of exercise and discuss how regular physical exercise can modulate these pillars to stave off age-related chronic diseases and maintain functional capacity. |
Shape-Anisotropic Microembolics Generated by Microfluidic Synthesis for Transarterial Embolization Treatment |
| Yucheng Luo, Yutao Ma, Zijian Chen, Yanan Gao, Yuping Zhou, Xiaoya Liu, Xuezhe Liu, Xu Gao, Zhihua Li, Chuang Liu, Hwa Liang Leo, Hanry Yu, Qiongyu Guo |
| Adv Healthc Mater. 2022 Feb 2;e2102281. doi: 10.1002/adhm.202102281. |
| Abstract |
| Particulate embolic agents with calibrated sizes, which employ interventional procedures to achieve endovascular embolization, have recently attracted tremendous interest in therapeutic embolotherapies for a wide plethora of diseases. However, the particulate shape effect, which may play a critical role in embolization performances, has been rarely investigated. Here, polyvinyl alcohol (PVA)-based shape-anisotropic microembolics are developed using a facile droplet-based microfluidic fabrication method via heat-accelerated PVA-glutaraldehyde crosslinking reaction at a mild temperature of 38 ° C. Precise geometrical controls of the microembolics are achieved with a nearly capsule shape through regulating surfactant concentration and flow rate ratio between dispersed phase and continuous phase in the microfluidics. Two specific models are employed, i.e., in vitro decellularized rabbit liver embolization model and in vivo rabbit ear embolization model, to systematically evaluate the embolization behaviors of the nonspherical microembolics. Compared to microspheres of the same volume, the elongated microembolics demonstrated advantageous endovascular navigation capability, penetration depth and embolization stability due to their comparatively smaller radial diameter and their central cylindrical part providing larger contact area with distal vessels. Such nonspherical microembolics present a promising platform to apply shape anisotropy to achieve distinctive therapeutic effects for endovascular treatments. |
Modulated TRPC1 Expression Predicts Sensitivity of Breast Cancer to Doxorubicin and Magnetic Field Therapy: Segue Towards a Precision Medicine Approach |
| Yee Kit Tai, Karen Ka Wing Chan, Charlene Hui Hua Fong, Sharanya Ramanan, Jasmine Lye Yee Yap, Jocelyn Naixin Yin, Yun Sheng Yip, Wei Ren Tan, Angele Pei Fern Koh, Nguan Soon Tan, Ching Wan Chan, Ruby Yun Ju Huang, Jing Ze Li, Jürg Fröhlich and Alfredo Franco-Obregón |
| Frontiers in Oncology; 2022 Jan 22. DOI: 10.3389/fonc.2021.783803. |
| Abstract |
| Chemotherapy is the mainstream treatment modality for invasive breast cancer. Unfortunately, chemotherapy-associated adverse events can result in early termination of treatment. Paradoxical effects of chemotherapy are also sometimes observed, whereby prolonged exposure to high doses of chemotherapeutic agents results in malignant states resistant to chemotherapy. In this study, potential synergism between doxorubicin (DOX) and pulsed electromagnetic field (PEMF) therapy was investigated in: 1) MCF-7 and MDA-MB-231 cells in vitro; 2) MCF-7 tumors implanted onto a chicken chorioallantoic membrane (CAM) and; 3) human patient-derived and MCF-7 and MDA-MB-231 breast cancer xenografts implanted into NOD-SCID gamma (NSG) mice. In vivo, synergism was observed in patient-derived and breast cancer cell line xenograft mouse models, wherein PEMF exposure and DOX administration individually reduced tumor size and increased apoptosis and could be augmented by combined treatments. In the CAM xenograft model, DOX and PEMF exposure also synergistically reduced tumor size as well as reduced Transient Receptor Potential Canonical 1 (TRPC1) channel expression. In vitro, PEMF exposure alone impaired the survival of MCF-7 and MDA-MB-231 cells, but not that of non-malignant MCF10A breast cells; the selective vulnerability of breast cancer cells to PEMF exposure was corroborated in human tumor biopsy samples. Stable overexpression of TRPC1 enhanced the vulnerability of MCF-7 cells to both DOX and PEMF exposure and promoted proliferation, whereas TRPC1 genetic silencing reduced sensitivity to both DOX and PEMF treatments and mitigated proliferation. Chronic exposure to DOX depressed TRPC1 expression, proliferation, and responses to both PEMF exposure and DOX in a manner that was reversible upon removal of DOX. TRPC1 channel overexpression and silencing positively correlated with markers of epithelial-mesenchymal transition (EMT), including SLUG, SNAIL, VIMENTIN, and E-CADHERIN, indicating increased and decreased EMT, respectively. Finally, PEMF exposure was shown to attenuate the invasiveness of MCF-7 cells in correlation with TRPC1 expression. We thus demonstrate that the expression levels of TRPC1 consistently predicted breast cancer sensitivity to DOX and PEMF interventions and positively correlated to EMT status, providing an initial rationale for the use of PEMF-based therapies as an adjuvant to DOX chemotherapy for the treatment of breast cancers characterized by elevated TRPC1 expression levels. |
EHMT1 promotes tumor progression and maintains stemness by regulating ALDH1A1 expression in alveolar rhabdomyosarcoma |
| Alamelu Nachiyappan, Joshua Ling Jun Soon, Huey Jin Lim, Victor Km Lee, Reshma Taneja |
| J Pathol. 2021 Dec 12. DOI: 10.1002/path.5848. |
| Abstract |
| Alveolar Rhabdomyosarcoma (ARMS) is an aggressive paediatric cancer with poor prognosis. Cancer stem cells (CSC) are seeds for tumor relapse and metastasis. However, pathways that maintain stemness genes are not fully understood. Here we report that the enzyme Euchromatic Histone Lysine Methyltransferase 1 (EHMT1) is expressed in primary and relapse ARMS tumors. EHMT1 suppression impaired motility and induced differentiation in ARMS cell lines and reduced tumor progression in a mouse xenograft model in vivo. RNA-sequencing of EHMT1-depleted cells revealed downregulation of ALDH1A1 that is associated with CSCs. Consistent with this, inhibition of ALDH1A1 expression and activity mimicked EHMT1 depletion phenotypes and reduced tumorsphere formation. Mechanistically, we demonstrate that EHMT1 does not bind to the ALDH1A1 promoter but activates it by stabilizing C/EBPβ, a known regulator of ALDH1A1 expression. Our findings identify a role for EHMT1 in maintenance of stemness by regulating ALDH1A1 expression and suggest that targeting ALDH+ cells is a promising strategy in ARMS. |
Crosstalk Between Inflammatory Signaling and Methylation in Cancer |
| Dipanwita Das, Nandini Karthik, Reshma Taneja |
| Front Cell Dev Biol. 2021 Nov 24;9:756458. DOI: 10.3389/fcell.2021.756458. eCollection 2021. |
| Abstract |
| Inflammation is an intricate immune response against infection and tissue damage. While the initial immune response is important for preventing tumorigenesis, chronic inflammation is implicated in cancer pathogenesis. It has been linked to various stages of tumor development including transformation, proliferation, angiogenesis, and metastasis. Immune cells, through the production of inflammatory mediators such as cytokines, chemokines, transforming growth factors, and adhesion molecules contribute to the survival, growth, and progression of the tumor in its microenvironment. The aberrant expression and secretion of pro-inflammatory and growth factors by the tumor cells result in the recruitment of immune cells, thus creating a mutual crosstalk. The reciprocal signaling between the tumor cells and the immune cells creates and maintains a successful tumor niche. Many inflammatory factors are regulated by epigenetic mechanisms including DNA methylation and histone modifications. In particular, DNA and histone methylation are crucial forms of transcriptional regulation and aberrant methylation has been associated with deregulated gene expression in oncogenesis. Such deregulations have been reported in both solid tumors and hematological malignancies. With technological advancements to study genome-wide epigenetic landscapes, it is now possible to identify molecular mechanisms underlying altered inflammatory profiles in cancer. In this review, we discuss the role of DNA and histone methylation in regulation of inflammatory pathways in human cancers and review the merits and challenges of targeting inflammatory mediators as well as epigenetic regulators in cancer. |
Bhlhe40 function in activated B and TFH cells restrains the GC reaction and prevents lymphomagenesis |
| Rene Rauschmeier, Annika Reinhardt, Charlotte Gustafsson, Vassilis Glaros, Artem V Artemov, Josefine Dunst, Reshma Taneja, Igor Adameyko, Robert Mansson, Meinrad Busslinger, Taras Kreslavsky |
| J Exp Med. 2022 Feb 7;219(2):e20211406. DOI: 10.1084/jem.20211406. |
| Abstract |
| The generation of high-affinity antibodies against pathogens and vaccines requires the germinal center (GC) reaction, which relies on a complex interplay between specialized effector B and CD4 T lymphocytes, the GC B cells and T follicular helper (TFH) cells. Intriguingly, several positive key regulators of the GC reaction are common for both cell types. Here, we report that the transcription factor Bhlhe40 is a crucial cell-intrinsic negative regulator affecting both the B and T cell sides of the GC reaction. In activated CD4 T cells, Bhlhe40 was required to restrain proliferation, thus limiting the number of TFH cells. In B cells, Bhlhe40 executed its function in the first days after immunization by selectively restricting the generation of the earliest GC B cells but not of early memory B cells or plasmablasts. Bhlhe40-deficient mice with progressing age succumbed to a B cell lymphoma characterized by the accumulation of monoclonal GC B-like cells and polyclonal TFH cells in various tissues. |
Neurokinin receptor mechanisms in forebrain medial septum modulate nociception in the formalin model of inflammatory pain |
| Si Yun Ng, Mohammed Zacky Ariffin and Sanjay Khanna |
| Scientific Reports, volume 11, Article number: 24358 (2021). DOI: 10.1038/s41598-021-03661-6 |
| Abstract |
| The present study has explored the hypothesis that neurokinin1 receptors (NK1Rs) in medial septum (MS) modulate nociception evoked on hind paw injection of formalin. Indeed, the NK1Rs in MS are localized on cholinergic neurons which have been implicated in nociception. In anaesthetized rat, microinjection of L-733,060, an antagonist at NK1Rs, into MS antagonized the suppression of CA1 population spike (PS) evoked on peripheral injection of formalin or on intraseptal microinjection of substance P (SP), an agonist at NK1Rs. The CA1 PS reflects the synaptic excitability of pyramidal cells in the region. Furthermore, microinjection of L-733,060 into MS, but not LS, attenuated formalin-induced theta activation in both anaesthetized and awake rat, where theta reflects an oscillatory information processing by hippocampal neurons. The effects of L-733,060 on microinjection into MS were nociceptive selective as the antagonist did not block septo-hippocampal response to direct MS stimulation by the cholinergic receptor agonist, carbachol, in anaesthetized animal or on exploration in awake animal. Interestingly, microinjection of L-733,060 into both MS and LS attenuated formalin-induced nociceptive flinches. Collectively, the foregoing novel findings highlight that transmission at NK1R provide an affective valence to septo-hippocampal information processing and that peptidergic transmission in the septum modulates nociceptive behaviours. |
Interplay between Mitochondrial Metabolism and Cellular Redox State Dictates Cancer Cell Survival |
| Brittney Joy-Anne Foo, Jie Qing Eu, Jayshree L Hirpara, Shazib Pervaiz |
| Oxid Med Cell Longev. 2021 Nov 3;2021:1341604. DOI: 10.1155/2021/1341604. eCollection 2021. |
| Abstract |
| Mitochondria are the main powerhouse of the cell, generating ATP through the tricarboxylic acid cycle (TCA) and oxidative phosphorylation (OXPHOS), which drives myriad cellular processes. In addition to their role in maintaining bioenergetic homeostasis, changes in mitochondrial metabolism, permeability, and morphology are critical in cell fate decisions and determination. Notably, mitochondrial respiration coupled with the passage of electrons through the electron transport chain (ETC) set up a potential source of reactive oxygen species (ROS). While low to moderate increase in intracellular ROS serves as secondary messenger, an overwhelming increase as a result of either increased production and/or deficient antioxidant defenses is detrimental to biomolecules, cells, and tissues. Since ROS and mitochondria both regulate cell fate, attention has been drawn to their involvement in the various processes of carcinogenesis. To that end, the link between a prooxidant milieu and cell survival and proliferation as well as a switch to mitochondrial OXPHOS associated with recalcitrant cancers provide testimony for the remarkable metabolic plasticity as an important hallmark of cancers. In this review, the regulation of cell redox status by mitochondrial metabolism and its implications for cancer cell fate will be discussed followed by the significance of mitochondria-targeted therapies for cancer. |
TRAIL sensitivity of nasopharyngeal cancer cells involves redox dependent upregulation of TMTC2 and its interaction with membrane caspase-3 |
| Deepika Raman, Patricia Tay, Jayshree L Hirpara, Dan Liu, Shazib Pervaiz |
| Redox Biol. 2021 Nov 20;48:102193. DOI: 10.1016/j.redox.2021.102193. |
| Abstract |
| Aims: Preferential expression of receptors for TNF-family related apoptosis inducing ligand (TRAIL), DR4 and DR5 makes TRAIL an attractive anti-cancer therapeutic. However, the efficacy of targeting death receptors has not been extensively studied in nasopharyngeal cancer (NPC). Here we investigated TRAIL sensitivity and its underlying mechanism in NPC cell lines, and assessed the potential of TRAIL as a therapeutic option against NPC. Results: Using two established NPC cell lines, we report the expression of DR4 and DR5, which respond to TRAIL ligation by triggering efficient Type II apoptosis. Mechanistically, early activation of caspase-3 and its membrane recruitment is identified in NPC cell lines, which is associated with, hitherto unreported, interaction with transmembrane and tetratricopeptide repeat containing 2 (TMTC2) in the lipid raft domains. TMTC2 expression is induced upon exposure to TRAIL and involves intracellular increase in peroxynitrite (ONOO-) production. While ONOO- increase is downstream of caspase-8 activation, it is involved in the upregulation of TMTC2, gene knockdown of which abrogated TRAIL-induced apoptotic execution. Bioinformatics analyses also provide evidence for a strong correlation between TMTC2 and DR4 or caspase-3 as well as a significantly better disease-free survival in patients with high TMTC2 expression. Innovation and conclusion: Collectively, redox-dependent execution of NPC cells upon ligation of TRAIL receptors reintroduces the possible therapeutic use of TRAIL in NPC as well as underscores the potential of using TMTC2 as a biomarker of TRAIL sensitivity. |
Identification of a novel catalytic inhibitor of topoisomerase II alpha that engages distinct mechanisms in p53 wt or p53 -/- cells to trigger G2/M arrest and senescence |
| Soo Fern Lee, Jayshree L Hirpara, Jianhua Qu, Sanjiv K Yadav, Karishma Sachaphibulkij, Shazib Pervaiz |
| Cancer Lett. 2021 Nov 26;526:284-303. DOI: 10.1016/j.canlet.2021.11.025. |
| Abstract |
| We report a novel topoisomerase IIα inhibitor, mercaptopyridine oxide (MPO), which induces G2/M arrest and senescence with distinctly different cell cycle regulators (p21 or p14ARF) in HCT116p 53WT and HCT116 p53-/- cells, respectively. MPO treatment induced defective topoisomerase IIα-mediated decatenation process and inhibition of the enzyme's catalytic activity that stalled entry into mitosis. Topoisomerase IIα inhibition was associated with ROS-mediated activation of ATM-Chk2 kinase axis in HCT116 p53WT cells, but not in HCT116 p53-/- cells displaying early Chk1 activation. Results suggest that E2F1 stabilization might link MPO-induced p53 phospho-activation in HCT116 p53WT cells or p14ARF induction in HCT116 p53-/- cells. Also, interaction between topoisomerase IIα and Chk1 was induced in both cell lines, which could be important for decatenation checkpoint activation, even upon p53 ablation. Notably, TCGA dataset analyses revealed topoisomerase IIα upregulation across a wide array of cancers, which was associated with lower overall survival. Corroborating that increased topoisomerase IIα expression might offer susceptibility to the novel inhibitor, MPO (5 μM) induced strong inhibition in colony forming ability of pancreatic and hepatocellular cancer cell lines. These data highlight a novel topoisomerase IIα inhibitor and provide proof-of-concept for its therapeutic potential against cancers even with loss-of-function of p53. |
Changes in energy balance, body composition, metabolic profile and physical performance in a 62-day Army Ranger training in a hot-humid environment |
| Linda S.H. Gan, Priscilla W.P. Fan, Junren Zhang, Heinrich W. Nolte, Karl E. Friedl, Bradley C.Nindl, Jason K.W.Lee |
| Journal of Science and Medicine in Sport. Volume 25, Issue 1, January 2022, Pages 89-94. DOI: 10.1016/j.jsams.2021.08.005. |
| Abstract |
| Objectives To determine the physiological effects of multiple stressors including energy deficit during a 62-day Ranger course in a hot-humid environment. Design Methods Results Conclusions |
Palatable flavoured fluids without carbohydrates and electrolytes do not enhance voluntary fluid consumption in male collegiate basketball players in the heat |
| Bernadette Cherianne Taim, Haresh T. Suppiah, Jericho Wee, Marcus Lee, Jason K. W. Lee and Michael Chia |
| Nutrients 2021, 13(12), 4197. DOI: 10.3390/nu13124197 |
| Abstract |
| Using palatable fluids to enhance drinking in athletes who display insufficient compensatory hydration behaviour may mitigate the risks of hypohydration and performance deficits. However, it is unclear whether flavour can independently enhance fluid consumption. This study examined the effects of a colourless, artificially sweetened flavoured water (FW), without carbohydrates and with negligible amounts of sodium, compared to plain water (W) on fluid consumption in male collegiate basketball players in a practical game setting. Eighteen male basketball players (age 23.1 ± 1.3 years) played a 3v3 basketball small-sided game. The players were randomly assigned to consume either FW or W. Pre-game urine-specific gravity, fluid consumption, body mass, and hedonic taste perceptions were assessed. Basketball performance was analysed through notational analysis. Ratings of perceived exertion and thirst were recorded at pre-, post-game, and at each rest period. Heart rate was recorded throughout the gameplay. Despite significantly higher hedonic ratings for FW than W (6.78 ± 0.83 vs. 5.56 ± 1.33, p = 0.033, d = 1.36), there were no significant differences in fluid consumption (1083 ± 32 mL vs. 1421 ± 403 mL, p = 0.068, d = 0.92). Our result highlighted that using palatable fluids as a strategy to increase fluid consumption during high-intensity gameplay in the heat may not be effective if used without carbohydrates and electrolytes. Practitioners could consider both fluid palatability and composition in establishing a hydration plan for athletes. |
The 2021 Report of The Lancet Countdown on Health and Climate Change: Code red for a healthy future |
| Marina Romanello, Alice McGushin, Claudia Di Napoli, Paul Drummond, Nick Hughes, Louis Jamart, Harry Kennard, Pete Lampard, Baltazar Solano Rodriguez, Prof Nigel Arnell, Sonja Ayeb-Karlsson, Kristine Belesova, Wenjia Cai, Diarmid Campbell-Lendrum, Stuart Capstick, Jonathan Chambers, Lingzhi Chu, Luisa Ciampi, Carole Dalin, Niheer Dasandi, Shouro Dasgupta, Prof Michael Davies, Paula Dominguez-Salas, Prof Robert Dubrow, Prof Kristie L Ebi, Matthew Eckelman, Prof Paul Ekins, Luis E Escobar, Lucien Georgeson, Prof Delia Grace, Prof Hilary Graham, Samuel H Gunther, Stella Hartinger, Kehan He, Clare Heaviside, Jeremy Hess, Shih-Che Hsu, Prof Slava Jankin, Marcia P Jimenez, Prof Ilan Kelman, Gregor Kiesewetter, Prof Patrick L Kinney, Prof Tord Kjellstrom, Prof Dominic Kniveton, Jason K W Lee, Bruno Lemke, Prof Yang Liu, Zhao Liu, Melissa Lott, Rachel Lowe, Prof Jaime Martinez-Urtaza, Prof Mark Maslin, Lucy McAllister, Celia McMichael, Zhifu Mi, James Milner, Kelton Minor, Nahid Mohajeri, Prof Maziar Moradi-Lakeh, Prof Karyn Morrissey, Prof Simon Munzert, Kris A Murray, Tara Neville, Prof Maria Nilsson, Nick Obradovich, Maquins Odhiambo Sewe, Prof Tadj Oreszczyn, Matthias Otto, Fereidoon Owfi, Olivia Pearman, David Pencheon, Mahnaz Rabbaniha, Prof Elizabeth Robinson, Prof Joacim Rocklöv, Renee N Salas, Prof Jan C Semenza, Jodi Sherman, Liuhua Shi, Marco Springmann, Prof Meisam Tabatabaei, Jonathon Taylor, Joaquin Trinanes, Joy Shumake-Guillemot, Bryan Vu, Fabian Wagner, Prof Paul Wilkinson, Matthew Winning, Marisol Yglesias, Shihui Zhang, Prof Peng Gong, Prof Hugh Montgomery, Prof Anthony Costello, Prof Ian Hamilton |
| The Lancet, Volume 398, ISSUE 10311, P1619-1662, October 30, 2021. DOI: 10.1016/S0140-6736(21)01787-6. |
| Abstract |
| The Lancet Countdown is an international collaboration that independently monitors the health consequences of a changing climate. Publishing updated, new, and improved indicators each year, the Lancet Countdown represents the consensus of leading researchers from 43 academic institutions and UN agencies. The 44 indicators of this report expose an unabated rise in the health impacts of climate change and the current health consequences of the delayed and inconsistent response of countries around the globe—providing a clear imperative for accelerated action that puts the health of people and planet above all else. |
Hydration status and fluid replacement strategies of high-performance adolescent athletes: An application of machine learning to distinguish hydration characteristics |
| Haresh T. Suppiah, Ee Ling Ng, Jericho Wee, Bernadette Cherianne Taim, Minh Huynh, Paul B. Gastin, Michael Chia, Chee Yong Low and Jason K. W. Lee |
| Nutrients 2021, 13(11), 4073. DOI: 10.3390/nu13114073 |
| Abstract |
| There are limited data on the fluid balance characteristics and fluid replenishment behaviors of high-performance adolescent athletes. The heterogeneity of hydration status and practices of adolescent athletes warrant efficient approaches to individualizing hydration strategies. This study aimed to evaluate and characterize the hydration status and fluid balance characteristics of high-performance adolescent athletes and examine the differences in fluid consumption behaviors during training. In total, 105 high-performance adolescent athletes (male: 66, female: 39; age 14.1 ± 1.0 y) across 11 sports had their hydration status assessed on three separate occasions—upon rising and before a low and a high-intensity training session (pre-training). The results showed that 20–44% of athletes were identified as hypohydrated, with 21–44% and 15–34% of athletes commencing low- and high-intensity training in a hypohydrated state, respectively. Linear mixed model (LMM) analyses revealed that athletes who were hypohydrated consumed more fluid (F (1.183.85)) = 5.91, (p = 0.016). Additional K-means cluster analyses performed highlighted three clusters: “Heavy sweaters with sufficient compensatory hydration habits,” “Heavy sweaters with insufficient compensatory hydration habits” and “Light sweaters with sufficient compensatory hydration habits”. Our results highlight that high-performance adolescent athletes with ad libitum drinking have compensatory mechanisms to replenish fluids lost from training. The approach to distinguish athletes by hydration characteristics could assist practitioners in prioritizing future hydration intervention protocols. |
Sensory Perception of an oral rehydration solution during exercise in the heat |
| Olivia Kitson 1, Kay Rutherfurd-Markwick, Andrew Foskett, Jason Kai Wei Lee, Charles Diako, Marie Wong and Ajmol Ali |
| Nutrients 13(10):3313. DOI:10.3390/nu13103313 |
| Abstract |
| Prolonged exercise in the heat elicits a number of physiological changes as glycogen stores are low and water and electrolytes are lost through sweat. However, it is unclear whether these changes provoke an increase in liking of saltiness and, therefore, palatability of an oral rehydration solution (ORS). Twenty-seven recreationally active participants (n= 13 males; n= 14 females) completed sensory analysis of an ORS, a traditional sports drink (TS), and a flavored water placebo (PL) at rest and during 60 min (3×20-min bouts) of cycling exercise at 70% age-predicted maximum heart rate (HRmax) at 35.3±1.4◦C and 41±6% relative humidity. Before and after every 20 min of exercise, drinks were rated (using 20-mL beverage samples) based on liking of sweetness, liking of saltiness, thirst-quenching ability, and overall liking on a nine-point hedonic scale. Hydration status was assessed by changes in semi-nude body mass, saliva osmolality (SOsm), and saliva total protein concentration (SPC). After 60 min of exercise, participants lost 1.36±0.39% (mean±SD) of body mass and there were increases in SOsm and SPC. At all time points, liking of sweetness, saltiness, thirst-quenching ability, and overall liking was higher for the TS and PL compared to the ORS (p< 0.05). However, the saltiness liking and thirst-quenching ability of the ORS increased after 60 min of exercise compared to before exercise (p< 0.05). There was also a change in predictors of overall liking with pre-exercise ratings mostly determined by liking of sweetness, saltiness, and thirst-quenching ability (p< 0.001), whereas only liking of saltiness predicted overall liking post-exercise (R2 = 0.751; p< 0.001). There appears to be a hedonic shift during exercise in which the perception of saltiness becomes the most important predictor of overall liking. This finding supports the potential use of an ORS as a valuable means of hydration during the latter stages of prolonged and/or intense exercise in the heat. |
Breaking the vicious circle: Extrachromosomal circular DNA as an emerging player in tumour evolution |
| Matius Robert, Karen Crasta |
| Semin Cell Dev Biol. 2021 Nov 29;S1084-9521(21)00291-3. DOI: 10.1016/j.semcdb.2021.11.015. |
| Abstract |
| Extrachromosomal circular DNA (ecDNA) or double minutes have gained renewed interest since its discovery more than five decades ago, emerging as potent drivers of tumour evolution. This has largely been motivated by recent discovery that the tumour-exclusive ecDNA are highly prevalent in almost all cancers unlike previously thought. EcDNAs contribute to elevated oncogene expression, intratumoural heterogeneity, tumour adaptation and therapy resistance independently of canonical chromosomal alterations. Importantly, ecDNAs play a critical role in patient survival as ecDNA-based oncogene amplification adversely affects clinical outcome to a significantly greater extent than intrachromosomal amplification. Chromothripsis, a major driver of ecDNA biogenesis and gene amplification, is a mutational process characterised by chromosomal shattering and localised complex genome rearrangement. Chemotherapeutic drugs can lead to chromothriptic rearrangements and therapy resistance. In this review, we examine how ecDNAs mediate oncogene overexpression, facilitate accelerated tumour malignancy and enhance rapid adaptation independently of linear chromosomes. We delve into discoveries pertaining to mechanisms of biogenesis, distinctive features of ecDNA, gene regulation and topological interactions with active chromatin. We also discuss the critical role of chromothripsis in engendering ecDNA amplification and evolution. One envisions that insights into ecDNA biology not only hold importance for the cancer genome and tumour evolutionary dynamics, but could also inform prognostication and clinical intervention, particularly for cancers characterised by high oncogene amplification. |
Chromothripsis: A shattered chromosome in the spotlight |
| Karen Crasta |
| Semin Cell Dev Biol. 2021 Nov 25;S1084-9521(21)00303-7. DOI: 10.1016/j.semcdb.2021.11.021. |
| Abstract |
| No abstract available |
Novel Autoantibodies in Idiopathic Small Fiber Neuropathy |
| Amanda C. Y. Chan, Hiu Yi Wong, Yao Feng Chong, Poh San Lai, Hock Luen Teoh, Alison Y. Y. Ng, Jennifer H. M. Hung, Yee Cheun Chan, Kay W. P. Ng, Joy Vijayan, Jonathan J. Y. Ong, Bharatendu Chandra, Chi Hsien Tan, Nurul H. Rutt, Ti Myen Tan, Nur Hafiza Ismail, Einar Wilder-Smith, Herbert Schwarz, Hyungwon Choi, Vijay K. Sharma, Anselm Mak |
| Annals of Neurology, in press. DOI: 10.1002/ana.26268 |
| Abstract |
| Objective Small fiber neuropathy (SFN) is clinically and etiologically heterogeneous. Although autoimmunity has been postulated to be pathophysiologically important in SFN, few autoantibodies have been described. We aimed to identify autoantibodies associated with idiopathic SFN (iSFN) by a novel high-throughput protein microarray platform that captures autoantibodies expressed in the native conformational state. Methods Sera from 58 SFN patients and 20 age- and gender-matched healthy controls (HCs) were screened against >1,600 immune-related antigens. Fluorescent unit readout and postassay imaging were performed, followed by composite data normalization and protein fold change (pFC) analysis. Analysis of an independent validation cohort of 33 SFN patients against the same 20 HCs was conducted to identify reproducible proteins in both cohorts. Results Nine autoantibodies were screened with statistical significance and pFC criteria in both cohorts, with at least 50% change in serum levels. Three proteins showed consistently high fold changes in main and validation cohorts: MX1 (FC = 2.99 and 3.07, respectively, p = 0.003, q = 0.076), DBNL (FC = 2.11 and 2.16, respectively, p = 0.009, q < 0.003), and KRT8 (FC = 1.65 and 1.70, respectively, p = 0.043, q < 0.003). Further subgroup analysis into iSFN and SFN by secondary causes (secondary SFN) in the main cohort showed that MX1 is higher in iSFN compared to secondary SFN (FC = 1.61 vs 0.106, p = 0.009). Interpretation Novel autoantibodies MX1, DBNL, and KRT8 are found in iSFN. MX1 may allow diagnostic subtyping of iSFN patients. ANN NEUROL 2021 |
Dendritic cell therapy with CD137L-DC-EBV-VAX in locally recurrent or metastatic nasopharyngeal carcinoma is safe and confers clinical benefit |
| Emily Nickles, Bhushan Dharmadhikari, Li Yating, Robert J Walsh, Liang Piu Koh, Michelle Poon, Lip Kun Tan, Ling-Zhi Wang, Yvonne Ang, Yugarajah Asokumaran, Wan Qin Chong, Yiqing Huang, Kwok Seng Loh, Joshua Tay, Ross Soo, Mickey Koh, Liam Pock Ho, Marieta Chan, Madelaine Niam, Melissa Soh, Yen Hoon Luah, Chwee Ming Lim, Nivashini Kaliaperumal, Veonice B Au, Najwa Binte Said Nasir Talib, Reina Sng, John E Connolly, Boon Cher Goh, Herbert Schwarz |
| Cancer Immunol Immunother. 2021 Oct 18. DOI: 10.1007/s00262-021-03075-3. |
| Abstract |
| Introduction: Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC), and provides a target for a dendritic cell (DC) vaccine. CD137 ligand (CD137L) expressed on antigen presenting cells, costimulates CD137-expressing T cells, and reverse CD137L signaling differentiates monocytes to CD137L-DC, a type of DC, which is more potent than classical DC in stimulating T cells. Methods: In this phase I study, patients with locally recurrent or metastatic NPC were administered CD137L-DC pulsed with EBV antigens (CD137L-DC-EBV-VAX). Results: Of the 12 patients treated, 9 received full 7 vaccine doses with a mean administered cell count of 23.9 × 106 per dose. Treatment was well tolerated with only 4 cases of grade 1 related adverse events. A partial response was obtained in 1 patient, and 4 patients are still benefitting from a progression free survival (PFS) of currently 2-3 years. The mean pre-treatment neutrophil: lymphocyte ratio was 3.4 and a value of less than 3 was associated with prolonged median PFS. Progressors were characterized by a high frequency of naïve T cells but a low frequency of CD8+ effector T cells while patients with a clinical benefit (CB) had a high frequency of memory T cells. Patients with CB had lower plasma EBV DNA levels, and a reduction after vaccination. Conclusion: CD137L-DC-EBV-VAX was well tolerated. The use of CD137L-DC-EBV-VAX is demonstrated to be safe. Consistent results were obtained from all 12 patients, indicating that CD137L-DC-EBV-VAX induces an anti-EBV and anti-NPC immune response, and warranting further studies in patients post effective chemotherapy. Precis: The first clinical testing of CD137L-DC, a new type of monocyte-derived DC, finds that CD137L-DC are safe, and that they can induce an immune response against Epstein-Barr virus-associated nasopharyngeal carcinoma that leads to tumor regression or prevents tumor progression. |
No crossreactivity of anti-SARS-CoV-2 spike protein antibodies with Syncytin-1 |
| Mukul Prasad, Jia Le Lin, Yue Gu, Rashi Gupta, Paul Macary, Herbert Schwarz |
| Cell Mol Immunol. 2021 Nov;18(11):2566-2568. DOI: 10.1038/s41423-021-00773-x. |
| Abstract |
| SARS-CoV-2, as well as the measures that were taken around the world to limit its spread, has killed thousands of people and ruined industries and economies. Vigorous vaccination campaigns are being pursued in the hope of ending the pandemic. However, many people are afraid of vaccination side effects, and one of these suspected side effects is female infertility due to vaccine-induced autoreactive antibodies against Syncytin-1 [1]. The spike protein of SARS-CoV-2, which is the main target of all vaccination schemes, shares homology to Syncytin-1. Syncytin-1 enables the fusion of trophoblasts to syncytiotrophoblasts, cells that are essential for placenta formation, an early step in the establishment of a pregnancy [2, 3]. |
B7-H7 Is Inducible on T Cells to Regulate Their Immune Response and Serves as a Marker for Exhaustion |
| Khang Luu, Herbert Schwarz, and Andreas Lundqvist |
| Front Immunol. 2021; 12: 682627. DOI: 10.3389/fimmu.2021.682627 |
| Abstract |
| The discovery of immune checkpoints highlights the complexity of T cell signalling during an immune response. Upon activation, T cells express several molecules to regulate their function and to prevent overactivation. B7 homolog 7 (B7-H7) is expressed in tumours and associated with a worse prognosis. However, conflicting data regarding its function suggest that it can be both stimulatory and inhibitory. In this study we report that B7-H7 is also expressed on T cells upon cross-linking of CD3 and CD28 and that additional stimulation via CD137 further enhances the expression of B7-H7. B7-H7 is preferentially expressed on exhausted Th1 and Tc1 cells with an impaired secretion of TNF-α and IFN-γ. Blockade of B7-H7 with its natural receptor, recombinant CD28H, enhances T cell proliferation and activation. Thus, B7-H7 represents another target for immunotherapy and a biomarker to select for active effector T cells with relevance for adoptive cell transfer therapy. |
Regulatory T Cells Inhibit T Cell Activity by Downregulating CD137 Ligand via CD137 Trogocytosis |
| Khang Luu, Mugdha Vijay Patwardhan, Qun Zeng, Stina L Wickström, Andreas Lundqvist, Herbert Schwarz |
| Cells. 2021 Feb 9;10(2):353. DOI: 10.3390/cells10020353. |
| Abstract |
| CD137 is a costimulatory molecule expressed on activated T cells. CD137 ligand (CD137L) is expressed by antigen presenting cells (APC), which use the CD137-CD137L system to enhance immune responses. It was, therefore, surprising to discover CD137 expression on regulatory T cells (Treg). The function of CD137 in Treg are controversial. While some studies report that CD137 signalling converts Treg to effector T cells (Teff), other studies find that CD137-expressing Treg display a stronger inhibitory activity than CD137- Treg. Here, we describe that CD137 on Treg binds to CD137L on APC, upon which one of the two molecules is transferred via trogocytosis to the other cell, where CD137-CD137L forms a complex that is internalized and deprives APC of the immune-stimulatory CD137L. Truncated forms of CD137 that lack the cytoplasmic domain of CD137 are also able to downregulate CD137L, demonstrating that CD137 signalling is not required. Comparable data have been obtained with human and murine cells, indicating that this mechanism is evolutionarily conserved. These data describe trogocytosis of CD137 and CD137L as a new mechanism employed by Treg to control immune responses by downregulating the immunostimulatory CD137L on APC. |
Integrated Genomic Profiling and Drug Screening of Patient-Derived Cultures Identifies Individualized Copy Number-Dependent Susceptibilities Involving PI3K Pathway and 17q Genes in Neuroblastoma |
| Rachel L Y Wong, Megan R E Wong, Chik Hong Kuick, Seyed Ehsan Saffari, Meng Kang Wong, Sheng Hui Tan, Khurshid Merchant, Kenneth T E Chang, Matan Thangavelu, Giridharan Periyasamy, Zhi Xiong Chen, Prasad Iyer, Enrica E K Tan, Shui Yen Soh, N Gopalakrishna Iyer, Qiao Fan, Amos H P Loh |
| Front Oncol. 2021 Oct 14;11:709525. DOI: 10.3389/fonc.2021.709525. eCollection 2021. |
| Abstract |
| Neuroblastoma is the commonest extracranial pediatric malignancy. With few recurrent single nucleotide variations (SNVs), mutation-based precision oncology approaches have limited utility, but its frequent and heterogenous copy number variations (CNVs) could represent genomic dependencies that may be exploited for personalized therapy. Patient-derived cell culture (PDC) models can facilitate rapid testing of multiple agents to determine such individualized drug-responses. Thus, to study the relationship between individual genomic aberrations and therapeutic susceptibilities, we integrated comprehensive genomic profiling of neuroblastoma tumors with drug screening of corresponding PDCs against 418 targeted inhibitors. We quantified the strength of association between copy number and cytotoxicity, and validated significantly correlated gene-drug pairs in public data and using machine learning models. Somatic mutations were infrequent (3.1 per case), but copy number losses in 1p (31%) and 11q (38%), and gains in 17q (69%) were prevalent. Critically, in-vitro cytotoxicity significantly correlated only with CNVs, but not SNVs. Among 1278 significantly correlated gene-drug pairs, copy number of GNA13 and DNA damage response genes CBL, DNMT3A, and PPM1D were most significantly correlated with cytotoxicity; the drugs most commonly associated with these genes were PI3K/mTOR inhibitor PIK-75, and CDK inhibitors P276-00, SNS-032, AT7519, flavopiridol and dinaciclib. Predictive Markov random field models constructed from CNVs alone recapitulated the true z-score-weighted associations, with the strongest gene-drug functional interactions in subnetworks involving PI3K and JAK-STAT pathways. Together, our data defined individualized dose-dependent relationships between copy number gains of PI3K and STAT family genes particularly on 17q and susceptibility to PI3K and cell cycle agents in neuroblastoma. Integration of genomic profiling and drug screening of patient-derived models of neuroblastoma can quantitatively define copy number-dependent sensitivities to targeted inhibitors, which can guide personalized therapy for such mutationally quiet cancers. |
Plk1 in Asthma - Ready for Primetime? |
| John Kit Chung Tam, Thai Tran |
| Am J Respir Cell Mol Biol. 2021 Nov 8. DOI: 10.1165/rcmb.2021-0425ED. |
| Abstract |
| No abstract available |
Tetraspanins: Host Factors in Viral Infections |
| ChihSheng New, Zhao-Yong Lee, Kai Sen Tan, Amanda Huee-Ping Wong, De Yun Wang, Thai Tran |
| Int J Mol Sci. 2021 Oct 27;22(21):11609. DOI: 10.3390/ijms222111609. |
| Abstract |
| Tetraspanins are transmembrane glycoproteins that have been shown increasing interest as host factors in infectious diseases. In particular, they were implicated in the pathogenesis of both non-enveloped (human papillomavirus (HPV)) and enveloped (human immunodeficiency virus (HIV), Zika, influenza A virus, (IAV), and coronavirus) viruses through multiple stages of infection, from the initial cell membrane attachment to the syncytium formation and viral particle release. However, the mechanisms by which different tetraspanins mediate their effects vary. This review aimed to compare and contrast the role of tetraspanins in the life cycles of HPV, HIV, Zika, IAV, and coronavirus viruses, which cause the most significant health and economic burdens to society. In doing so, a better understanding of the relative contribution of tetraspanins in virus infection will allow for a more targeted approach in the treatment of these diseases. |
Sex-specific accelerated decay in time/activity-dependent plasticity and associative memory in an animal model of Alzheimer's disease |
| Sheeja Navakkode, Jessica Ruth Gaunt, Maria Vazquez Pavon, Vibhavari Aysha Bansal, Riya Prasad Abraham, Yee Song Chong, Toh Hean Ch'ng, Sreedharan Sajikumar |
| Aging Cell. 2021 Nov 18;e13502. DOI: 10.1111/acel.13502. |
| Abstract |
| Clinical studies have shown that female brains are more predisposed to neurodegenerative diseases such as Alzheimer's disease (AD), but the cellular and molecular mechanisms behind this disparity remain unknown. In several mouse models of AD, synaptic plasticity dysfunction is an early event and appears before significant accumulation of amyloid plaques and neuronal degeneration. However, it is unclear whether sexual dimorphism at the synaptic level contributes to the higher risk and prevalence of AD in females. Our studies on APP/PS1 (APPSwe/PS1dE9) mouse model show that AD impacts hippocampal long-term plasticity in a sex-specific manner. Long-term potentiation (LTP) induced by strong tetanic stimulation (STET), theta burst stimulation (TBS) and population spike timing-dependent plasticity (pSTDP) show a faster decay in AD females compared with age-matched AD males. In addition, behavioural tagging (BT), a model of associative memory, is specifically impaired in AD females with a faster decay in memory compared with males. Together with the plasticity and behavioural data, we also observed an upregulation of neuroinflammatory markers, along with downregulation of transcripts that regulate cellular processes associated with synaptic plasticity and memory in females. Immunohistochemistry of AD brains confirms that female APP/PS1 mice carry a higher amyloid plaque burden and have enhanced microglial activation compared with male APP/PS1 mice. Their presence in the diseased mice also suggests a link between the impairment of LTP and the upregulation of the inflammatory response. Overall, our data show that synaptic plasticity and associative memory impairments are more prominent in females and this might account for the faster progression of AD in females. |
Deciphering nanoparticle trafficking into glioblastomas uncovers an augmented antitumor effect of metronomic chemotherapy |
| Melgious Jin Yan Ang, Jeehyun Yoon, Mingzhu Zhou, Han-Lin Wei, Yi Yiing Goh, Zhenglin Li, Jia Feng, Haifang Wang, Qianqian Su, Derrick Sek Tong Ong, Xiaogang Liu |
| Adv Mater. 2021 Nov 2;e2106194. DOI: 10.1002/adma.202106194. |
| Abstract |
| Nanoparticles have been explored in glioblastomas as they can traverse the blood-brain barrier and target glioblastoma selectively. However, direct observation of nanoparticle trafficking into glioblastoma cells and their underlying intracellular fate after systemic administration remains uncharacterized. Here, based on transmission electron microscopy experiments of an intracranial glioblastoma model, we show that ligand-modified nanoparticles can traverse the blood-brain barrier, endocytose into the lysosomes of glioblastoma cells, and undergo endo-lysosomal escape upon photochemical ionization. Moreover, an optimal dose of metronomic chemotherapy using dual drug-loaded nanocarriers can induce an augmented antitumor effect directly on tumors, which was not recognized in previous studies. Metronomic chemotherapy enhances antitumor effects 3.5-fold compared with the standard chemotherapy regimen using the same accumulative dose in vivo. This study provides a conceptual framework that can be used to develop metronomic nanoparticle regimens as a safe and viable therapeutic strategy for treating glioblastomas and other advanced-stage solid tumors. This article is protected by copyright. All rights reserved. |
Metaplastic reinforcement of long-term potentiation in hippocampal area CA2 by cholinergic receptor activation |
| Amrita Benoy, Mohammad Zaki Bin Ibrahim, Thomas Behnisch, Sreedharan Sajikumar |
| J Neurosci. 2021 Sep 24;JN-RM-2885-20. DOI: 10.1523/JNEUROSCI.2885-20.2021. |
| Abstract |
| Hippocampal CA2, an inconspicuously positioned area between the well-studied CA1 and CA3 subfields, has captured research interest in recent years due to its role in social memory formation. However, the role of cholinergic inputs to the CA2 area for the regulation of synaptic plasticity remains to be fully understood. We show that cholinergic receptor activation with the non-selective cholinergic agonist, carbachol (CCh), triggers a protein synthesis-dependent and NMDAR-independent long-term synaptic depression (CCh-LTD) at entorhinal cortical (EC)-CA2 and Schaffer collateral (SC)-CA2 synapses in the hippocampus of adult male Wistar rats. The activation of muscarinic acetylcholine receptors (mAChRs) is critical for the induction of CCh-LTD with the results suggesting an involvement of M3 and M1 mAChRs in the early facilitation of CCh-LTD, while nicotinic acetylcholine receptor activation plays a role in the late maintenance of CCh-LTD at CA2 synapses. Remarkably, we find that CCh priming lowers the threshold for the subsequent induction of persistent long-term potentiation (LTP) of synaptic transmission at EC-CA2 and the plasticity-resistant SC-CA2 pathways. The effects of such a cholinergic-dependent synaptic depression on subsequent LTP at EC-CA2 and SC-CA2 synapses have not been previously explored. Collectively, the results demonstrate that CA2 synaptic learning rules are regulated in a metaplastic manner, whereby modifications triggered by prior cholinergic stimulation can dictate the outcome of future plasticity events. Moreover, the reinforcement of LTP at EC inputs to CA2 following the priming stimulus co-exists with concurrent sustained CCh-LTD at the SC-CA2 pathway and is dynamically scaled by modulation of SC-CA2 synaptic transmission.Significance Statement:The release of the neuromodulator acetylcholine is critically involved in processes of hippocampus-dependent memory formation. Cholinergic afferents originating in the medial septum and diagonal bands of Broca terminating in the hippocampal area CA2 might play an important role in the modulation of area-specific synaptic plasticity. Our findings demonstrate that cholinergic receptor activation induces a long-term depression of synaptic transmission at entorhinal cortical- and Schaffer collateral-CA2 synapses. This cholinergic activation-mediated long-term depression displays a bidirectional metaplastic switch to long-term potentiation on a future timescale. This suggests that such bidirectional synaptic modifications triggered by the dynamic modulation of tonic cholinergic receptor activation may support the formation of CA2-dependent memories given the increased hippocampal cholinergic tone during active wakefulness observed in exploratory behaviour. |
Inactive variants of death receptor p75 NTR reduce Alzheimer's neuropathology by interfering with APP internalization |
| Chenju Yi, Ket Yin Goh, Lik-Wei Wong, Ajeena Ramanujan, Kazuhiro Tanaka, Sreedharan Sajikumar, Carlos F Ibáñez |
| EMBO J. 2021 Sep 1;40(17):e109067. doi: 10.15252/embj.2021109067. |
| Abstract |
| NA |
Decompartmentalisation as a simple color manipulation of plant-based marbling meat alternatives |
| Shujian Ong, Larry Loo, Marion Pang, Russell Tan, Yao Teng, Xuanming Lou, Sze Khen Chin, Mihir Yogesh Naik, Hanry Yu |
| Biomaterials. Volume 277, October 2021, 121107. DOI: 10.1016/j.biomaterials.2021.121107 |
| Abstract |
| Recent efforts for cell-based meat cuts focus on engineering edible scaffolds, with visual cues which are key to enhancing consumer acceptance, receiving less attention Here, we employed artificial intelligence (AI)-based screening of potential plant materials and discovered that jackfruit (Artocarpus heterophyllus) has the natural structures to recapitulate marbling visuals of meat cuts. Plant tissue compositions are exploited for its differential polyphenol adsorption to produce complex marbling patterns. A one-step colour control method by varying oxidation and incubation conditions of polyphenols was developed to produce permanent meat-like colours resembling chicken, pork, and beef. The scaffold exhibits a meat-like browning behaviour when cooked and is shown to support high-density porcine myoblasts culture without masking the marbled appearance. Surveys with 78 volunteers found that marbled jackfruit scaffolds improved consumer perception of cell-based meat by ∼8%. Our approach of combining AI, tissue engineering, and sensory science unlocks the possibility of creating a range of novel cell-based meat cuts with consumer focus. |
AIM2 inflammasome mediates apoptotic and pyroptotic death in the cerebellum following chronic hypoperfusion |
| Poh L, Razak SMBA, Lim HM, Lai MKP, Chen CL, Lim LHK, Arumugam TV, Fann DY |
| Experimental Neurology, 30 Aug 2021, 346:113856. DOI: 10.1016/j.expneurol.2021.113856 |
| Abstract |
| Vascular dementia (VaD) is the second most common form of dementia and is caused by vascular pathologies resulting in chronic cerebral hypoperfusion (CCH)- induced brain injury, and ultimately cognitive impairment and memory loss. Several lines of evidence have demonstrated chronic inflammation may be involved in VaD disease progression. It is now recognized that a major contributor to cerebral and systemic chronic inflammation involves the activation of innate immune molecular complexes termed inflammasomes. Whilst previous studies on animal models of VaD have focused on the cortex, hippocampus and striatum, few studies have investigated the effect of CCH on the cerebellum. Emerging studies have found new roles of the cerebellum in cognition, based on its structural interconnectivity with other brain regions and clinical relevance in neuropsychological deficits. In the present study, we conducted our investigation on the cerebellum using a CCH mouse model of VaD following bilateral common carotid artery stenosis (BCAS). This study is the first to characterize an increased expression of inflammasome receptors, adaptor and effector proteins, markers of inflammasome activation, proinflammatory cytokines, and apoptotic and pyroptotic cell death proteins in the cerebellum following CCH. Furthermore, in AIM2 knockout mice, we observed attenuated inflammasome-mediated production of proinflammatory cytokines, apoptosis, and pyroptosis in the cerebellum following CCH. Collectively, our findings provide novel evidence that AIM2 inflammasome activation promotes apoptosis and pyroptosis in the cerebellum following chronic hypoperfusion in a mouse model of VaD. |
Modulation of Septo-Hippocampal Neural Responses in Anesthetized and Behaving Rats by Septal AMPA Receptor Mechanisms |
| Khairunisa Mohamad Ibrahim, Mohammed Zacky Ariffin, Sanjay Khanna |
| Front Neural Circuits. 2021 Jun 4;15:663633. doi: 10.3389/fncir.2021.663633. |
| Abstract |
| This study explored the effects of septal glutamatergic transmission on septal-hippocampal theta activity via intraseptal microinjection of antagonist at AMPA receptors (AMPAR). The current results showed that microinjection of AMPAR antagonist, NBQX (2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione, 20 μg/μl, 0.5 μl), evoked a decrease in the frequency of theta activity evoked by various means in anesthetized and behaving rat. Theta wave activity was induced on: (a) intraseptal microinjection of carbachol, an agonist at cholinergic receptors, (b) reticular stimulation, (c) exploration in novel open field (OF), and (d) hind paw (HP) injection of the algogen, formalin. The effect on frequency in the formalin test was observed in an early period on injection of formalin, which was novel to the animal, but not in the later more sustained phase of the formalin test. The effect of NBQX, being seen in both anesthetized and behaving animals, suggests that the modulation of theta wave frequency, including in novelty, is a function of AMPAR in MS. The effect of the antagonist on theta power was less apparent, being observed only in anesthetized animals. In addition to theta power and frequency, intraseptal NBQX also attenuated suppression of CA1 population spike (PS) induced by intraseptal carbachol, thus suggesting that septal glutamate neurotransmission is involved in the spectrum of MS-mediated network responses. Indeed, in the context of behavior, formalin injection induced an increase in the level of septal glutamate, while NBQX attenuated nociceptive behaviors. Notably, MS is involved in the modulation of formalin nociception. These findings suggest that AMPA receptors are a key modulator of septal physiological function. |
Assessment of the economic impact of heat-related labor productivity loss: a systematic review |
| Mengzhen Zhao, Jason Kai Wei Lee, Tord Kjellstrom & Wenjia Cai |
| Climatic Change. Volume 167, Article number: 22 (2021). DOI: 10.1007/s10584-021-03160-7. |
| Abstract |
| Heat stress caused by climate change and heat-related labor productivity losses have become global concerns. Estimating the economic impacts of heat stress is of great significance for employers, as well as sectoral and national policy makers who are searching for solutions to reduce productivity losses. As the value of economic impacts are sensitive to the research methodologies, we conducted a systematic review of published literature on the methodologies and results of economic impacts of heat on labor productivity. Four methods were summarized: the human capital (HC) method, the econometric method (EM), the input–output (IO) method, and the computable general equilibrium (CGE) model. Considering adaptation measures, global economic losses due to heat-related labor productivity losses are projected to range from 0.31% (0.14–0.5%, RCP2.6) to 2.6% (1.4–4%, RCP8.5) of global GDP in 2100. The published studies found that large economic losses occurred mainly in South and Southeast Asia, Sub-Saharan Africa, and Central America. Owing to different methodologies and considerations of adaptation measures, the disparities of results within the same area at a given time can be as high as 7.4-fold. We summarized the knowledge gaps in existing studies and proposed new directions to provide more targeted and reliable results for policy makers. |
Perceptions of heat-health impacts and the effects of knowledge and preventive actions by outdoor workers in Hanoi, Vietnam |
| S. Lohrey, M. Chua, C. Gros, J. Faucet, J.K.W. Lee |
| Science of The Total Environment. Volume 794, 10 November 2021, 148260. DOI: 10.1016/j.scitotenv.2021.148260. |
| Abstract |
| Extreme heat is an increasing climate threat, most pronounced in urban areas where poor populations are at particular risk. We analyzed heat impacts and vulnerabilities of 1027 outdoor workers who participated in a KAP survey in Hanoi, Vietnam in 2018, and the influence of their mitigation actions, their knowledge of heat-risks, and access to early warnings. We grouped respondents by their main income (vendors, builders, shippers, others, multiple jobs, and non-working) and analyzed their reported heat-health impacts, taking into consideration socioeconomics, knowledge of heat impacts and preventive measures, actions taken, access to air-conditioning, drinking amounts and use of weather forecasts. We applied linear and logistic regression analyses using R. Construction workers were younger and had less knowledge of heat-health impacts, but also reported fewer symptoms. Older females were more likely to report symptoms and visit a doctor. Access to air-conditioning in the bedroom depended on age and house ownership, but did not influence heat impacts as cooling was too expensive. Respondents who knew more heat exhaustion symptoms were more likely to report impacts (p < 0.01) or consult a doctor (p < 0.05). Similarly, those who checked weather updates were more likely to report heat impacts (p < 0.01) and experienced about 0.6 more symptoms (p < 0.01). Even though occupation type did not explain heat illness, builders knew considerably less (40%; p < 0.05) about heat than other groups but were twice as likely to consult a doctor than street vendors (p < 0.01). Knowledge of preventive actions and taking these actions both correlated positively with reporting of heat-health symptoms, while drinking water did not reduce these symptoms (p < 0.01). Child carers and homeowners experienced income losses in heatwaves (p < 0.01). The differences support directed actions, such as dissemination of educational materials and weather forecasts for construction workers. The Red Cross assisted all groups with cooling tents, provision of drinks and health advice. |
Changes in energy balance, body composition, metabolic profile and physical performance in a 62-day Army Ranger training in a hot-humid environment |
| Linda S.H. Gan, Priscilla W.P. Fan, Junren Zhang, Heinrich W. Nolte, Karl E. Friedl, Bradley C. Nindl, Jason K.W. Lee |
| Journal of Science and Medicine in Sport. Available online 12 August 2021. DOI: 10.1016/j.jsams.2021.08.005. |
| Abstract |
| Objectives To determine the physiological effects of multiple stressors including energy deficit during a 62-day Ranger course in a hot-humid environment. Design Prospective cohort design. Methods Food intake data were collected daily and energy expenditure at each of the three phases of the course was estimated by the doubly-labeled water method. Anthropometry, hydration status, stress and metabolic hormones, handgrip strength and lower explosive power were measured at the start and at the end of each phase. Results Seventeen male participants (age: 24.5 ± 3.2 years, height: 173.9 ± 5.1 cm, body mass: 69.3 ± 3.2 kg, BMI: 22.9 ± 0.9 kg/m2, percent body fat: 14 ± 5%) completed the study. Mean total daily energy expenditure was 4756 kcal/day and mean daily energy intake was 3882 kcal/day. An 18% energy deficit resulted in an average body mass loss of 4.6 kg, comprising mostly fat mass. Participants with higher baseline adiposity (>15% body fat) lost more fat mass and gained (rather than lost) muscle mass compared to those with lower baseline adiposity. Handgrip strength declined only at the end of Phase I, while lower body explosive power declined progressively throughout the course. Lean mass in arms and legs was correlated with initial grip strength and lower body explosive power, but only at the start of the course. Conclusions Physiologically demanding Ranger training in an equatorial environment is at least as metabolically demanding and stressful as other similar high-risk training courses, as demonstrated by the stress and metabolic endocrine responses, changes in body composition, and reduction in explosive power. Moreover, the smaller body size of Asian soldiers may confer an energetic advantage over larger sized Western counterparts. |
B7-H7 Is Inducible on T Cells to Regulate Their Immune Response and Serves as a Marker for Exhaustion |
| Khang Luu, Herbert Schwarz, Andreas Lundqvist |
| Front Immunol. 2021 Jun 1;12:682627. doi: 10.3389/fimmu.2021.682627. eCollection 2021. |
| Abstract |
| The discovery of immune checkpoints highlights the complexity of T cell signalling during an immune response. Upon activation, T cells express several molecules to regulate their function and to prevent overactivation. B7 homolog 7 (B7-H7) is expressed in tumours and associated with a worse prognosis. However, conflicting data regarding its function suggest that it can be both stimulatory and inhibitory. In this study we report that B7-H7 is also expressed on T cells upon cross-linking of CD3 and CD28 and that additional stimulation via CD137 further enhances the expression of B7-H7. B7-H7 is preferentially expressed on exhausted Th1 and Tc1 cells with an impaired secretion of TNF-α and IFN-γ. Blockade of B7-H7 with its natural receptor, recombinant CD28H, enhances T cell proliferation and activation. Thus, B7-H7 represents another target for immunotherapy and a biomarker to select for active effector T cells with relevance for adoptive cell transfer therapy. |
DUSP16 promotes cancer chemoresistance through regulation of mitochondria-mediated cell death |
| Heng Boon Low, Zhen Lim Wong, Bangyuan Wu, Li Ren Kong, Chin Wen Png, Yik-Lam Cho, Chun-Wei Li, Fengchun Xiao, Xuan Xin, Henry Yang, Jia Min Loo, Fiona Yi Xin Lee, Iain Bee Huat Tan, Ramanuj DasGupta , Han-Ming Shen, Herbert Schwarz, Nicholas R J Gascoigne, Boon Cher Goh, Xiaohong Xu, Yongliang Zhang |
| Nat Commun. 2021 Apr 16;12(1):2284. doi: 10.1038/s41467-021-22638-7. |
| Abstract |
| Drug resistance is a major obstacle to the treatment of most human tumors. In this study, we find that dual-specificity phosphatase 16 (DUSP16) regulates resistance to chemotherapy in nasopharyngeal carcinoma, colorectal cancer, gastric and breast cancer. Cancer cells expressing higher DUSP16 are intrinsically more resistant to chemotherapy-induced cell death than cells with lower DUSP16 expression. Overexpression of DUSP16 in cancer cells leads to increased resistance to cell death upon chemotherapy treatment. In contrast, knockdown of DUSP16 in cancer cells increases their sensitivity to treatment. Mechanistically, DUSP16 inhibits JNK and p38 activation, thereby reducing BAX accumulation in mitochondria to reduce apoptosis. Analysis of patient survival in head & neck cancer and breast cancer patient cohorts supports DUSP16 as a marker for sensitivity to chemotherapy and therapeutic outcome. This study therefore identifies DUSP16 as a prognostic marker for the efficacy of chemotherapy, and as a therapeutic target for overcoming chemoresistance in cancer. |
Artificial intelligence−enhanced white-light colonoscopy with attention guidance predicts colorectal cancer invasion depth |
| Xiaobei Luo, Jiahao Wang, Zelong Han, Yang Yu, Zhenyu Chen, Feiyang Huang, Yumeng Xu, Jianqun Cai, Qiang Zhang, Weiguang Qiao, Inn Chuan Ng, Robby T. Tan, Side Liu, Hanry Yu |
| Gastrointestinal Endoscopy; September 2021; 94(3): 627-638.e1. doi: 10.1016/j.gie.2021.03.936. |
| Abstract |
| Background and Aims Endoscopic submucosal dissection (ESD) and EMR are applied in treating superficial colorectal neoplasms but are contraindicated by deeply invasive colorectal cancer (CRC). The invasion depth of neoplasms can be examined by an automated artificial intelligence (AI) system to determine the applicability of ESD and EMR. Methods A deep convolutional neural network with a tumor localization branch to guide invasion depth classification was constructed on the GoogLeNet architecture. The model was trained using 7734 nonmagnified white-light colonoscopy (WLC) images supplemented by image augmentation from 657 lesions labeled with histopathologic analysis of invasion depth. An independent testing dataset consisting of 1634 WLC images from 156 lesions was used to validate the model. Results For predicting noninvasive and superficially invasive neoplasms, the model achieved an overall accuracy of 91.1% (95% confidence interval [CI], 89.6%-92.4%), with 91.2% sensitivity (95% CI, 88.8%-93.3%) and 91.0% specificity (95% CI, 89.0%-92.7%) at an optimal cutoff of .41 and the area under the receiver operating characteristic (AUROC) curve of .970 (95% CI, .962-.978). Inclusion of the advanced CRC data significantly increased the sensitivity in differentiating superficial neoplasms from deeply invasive early CRC to 65.3% (95% CI, 61.9%-68.8%) with an AUROC curve of .729 (95% CI, .699-.759), similar to experienced endoscopists (.691; 95% CI, .624-.758). Conclusions We have developed an AI-enhanced attention-guided WLC system that differentiates noninvasive or superficially submucosal invasive neoplasms from deeply invasive CRC with high accuracy, sensitivity, and specificity. |
Reproducibility and robustness of high-throughput S1500+ transcriptomics on primary rat hepatocytes for chemical-induced hepatotoxicity assessment |
| Fan Lee, Imran Shah, Yun Ting Soong, Jiangwa Xing, Inn Chuan Ng, Farah Tasnim, Hanry Yu |
| Current Research in Toxicology. 2: 282-295. doi: 10.1016/j.crtox.2021.07.003. |
| Abstract |
| Cell-based in vitro models coupled with high-throughput transcriptomics (HTTr) are increasingly utilized as alternative methods to animal-based toxicity testing. Here, using a panel of 14 chemicals with different risks of human drug-induced liver injury (DILI) and two dosing concentrations, we evaluated an HTTr platform comprised of collagen sandwich primary rat hepatocyte culture and the TempO-Seq surrogate S1500+ (ST) assay. First, the HTTr platform was found to exhibit high reproducibility between technical and biological replicates (r greater than 0.85). Connectivity mapping analysis further demonstrated a high level of inter-platform reproducibility between TempO-Seq data and Affymetrix GeneChip data from the Open TG-GATES project. Second, the TempO-Seq ST assay was shown to be a robust surrogate to the whole transcriptome (WT) assay in capturing chemical-induced changes in gene expression, as evident from correlation analysis, PCA and unsupervised hierarchical clustering. Gene set enrichment analysis (GSEA) using the Hallmark gene set collection also demonstrated consistency in enrichment scores between ST and WT assays. Lastly, unsupervised hierarchical clustering of hallmark enrichment scores broadly divided the samples into hepatotoxic, intermediate, and non-hepatotoxic groups. Xenobiotic metabolism, bile acid metabolism, apoptosis, p53 pathway, and coagulation were found to be the key hallmarks driving the clustering. Taken together, our results established the reproducibility and performance of collagen sandwich culture in combination with TempO-Seq S1500+ assay, and demonstrated the utility of GSEA using the hallmark gene set collection to identify potential hepatotoxicants for further validation. |
A chemical biology approach reveals a dependency of glioblastoma on biotin distribution |
| Jeehyun Yoon, Oleg V. Grinchuk, Srinivasaraghavan Kannan, Melgious Jin Yan Ang, Zhenglin Li, Emmy Xue Yun Tay, Ker Zhing Lok, Bernice Woon Li Lee, You Heng Chuah, Kimberly Chia, Roberto Tirado Magallanes, Chenfei Liu, Haonan Zhao, Jin Hui Hor, Jhin Jieh Lim, Touati Benoukraf, Tan Boon Toh, Edward Kai-Hua Chow, Jean-Paul Kovalik, Jianhong Ching, Shi-Yan Ng, Ming Joo Koh, Xiaogang Liu, Chandra Shekhar Verma, and Derrick Sek Tong Ong |
| Science Advances, 3 Sep 2021; 7(36). DOI: 10.1126/sciadv.abf6033 |
| Abstract |
| Glioblastoma (GBM) is a uniformly lethal disease driven by glioma stem cells (GSCs). Here, we use a chemical biology approach to unveil previously unknown GBM dependencies. By studying sulconazole (SN) with anti-GSC properties, we find that SN disrupts biotin distribution to the carboxylases and histones. Transcriptomic and metabolomic analyses of SN-treated GSCs reveal metabolic alterations that are characteristic of biotin-deficient cells, including intracellular cholesterol depletion, impairment of oxidative phosphorylation, and energetic crisis. Furthermore, SN treatment reduces histone biotinylation, histone acetylation, and expression of superenhancer-associated GSC critical genes, which are also observed when biotin distribution is genetically disrupted by holocarboxylase synthetase (HLCS) depletion. HLCS silencing impaired GSC tumorigenicity in an orthotopic xenograft brain tumor model. In GBM, high HLCS expression robustly indicates a poor prognosis. Thus, the dependency of GBM on biotin distribution suggests that the rational cotargeting of biotin-dependent metabolism and epigenetic pathways may be explored for GSC eradication. |
Long-term plasticity in the hippocampus: maintaining within and 'tagging' between synapses |
| Mohammad Zaki Bin Ibrahim, Amrita Benoy, Sreedharan Sajikumar |
| FEBS J. 2021 Jun 10. doi: 10.1111/febs.16065. Online ahead of print. |
| Abstract |
| Synapses between neurons are malleable biochemical structures, strengthening and diminishing over time dependent on the type of information they receive. This phenomenon known as synaptic plasticity underlies learning and memory, and its different forms, long-term potentiation (LTP) and long-term depression (LTD), perform varied cognitive roles in reinforcement, relearning and associating memories. Moreover, both LTP and LTD can exist in an early transient form (early-LTP/LTD) or a late persistent form (late-LTP/LTD), which are triggered by different induction protocols, and also differ in their dependence on protein synthesis and the involvement of key molecular players. Beyond homosynaptic modifications, synapses can also interact with one another. This is encapsulated in the synaptic tagging and capture hypothesis (STC), where synapses expressing early-LTP/LTD present a 'tag' that can capture the protein synthesis products generated during a temporally proximal late-LTP/LTD induction. This 'tagging' phenomenon forms the framework of synaptic interactions in various conditions and accounts for the cellular basis of the time-dependent associativity of short-lasting and long-lasting memories. All these synaptic modifications take place under controlled neuronal conditions, regulated by subcellular elements such as epigenetic regulation, proteasomal degradation and neuromodulatory signals. Here, we review current understanding of the different forms of synaptic plasticity and its regulatory mechanisms in the hippocampus, a brain region critical for memory formation. We also discuss expression of plasticity in hippocampal CA2 area, a long-overlooked narrow hippocampal subfield and the behavioural correlate of STC. Lastly, we put forth perspectives for an integrated view of memory representation in synapses. |
Inhibition of lysine methyltransferase G9a/GLP reinstates long-term synaptic plasticity and synaptic tagging/capture by facilitating protein synthesis in the hippocampal CA1 area of APP/PS1 mouse model of Alzheimer's disease |
| Javan Lee Tze Ha, Karen Ka Lam Pang, Sheila Rui Xia Ang, Mahima Sharma, Sreedharan Sajikumar |
| Transl Neurodegener. 2021 Jun 29;10(1):23.doi: 10.1186/s40035-021-00247-0. |
| Abstract |
| no astract available |
Targeting novel human transient receptor potential ankyrin 1 splice variation with splice-switching antisense oligonucleotides |
| Huang, Hua; Tay, Shermaine Huiping; Ng, Winanto; Ng, Shi Yan; Soong, Tuck Wah |
| PAIN: July 2021 - Volume 162 - Issue 7 - p 2097-2109. DOI: 10.1097/j.pain.0000000000002216 |
| Abstract |
| Activation of transient receptor potential ankyrin 1 (TRPA1) channels by both environmental irritants and endogenous inflammatory mediators leads to excitation of the nerve endings, resulting in acute sensation of pain, itch, or chronic neurogenic inflammation. As such, TRPA1 channels are actively pursued as therapeutic targets for various pathological nociception and pain disorders. We uncovered that exon 27 of human TRPA1 (hTRPA1) could be alternatively spliced into hTRPA1_27A and hTRPA1_27B splice variants. The resulting channel variants displayed reduced expression, weakened affinity to interact with WT, and suffered from complete loss of function because of disruption of the C-terminal coiled-coil domain. Using a human minigene construct, we revealed that binding of splicing factor serine/arginine-rich splicing factor 1 (SRSF1) to the exonic splicing enhancer was critical for the inclusion of intact exon 27. Knockdown of SRSF1, mutation within exonic splicing enhancer, or masking SRSF1 binding with antisense oligonucleotides promoted alternative splicing within exon 27. Finally, antisense oligonucleotides-induced alternative splicing produced transcript and protein variants that could be functionally determined as diminished endogenous TRPA1 activity in human Schwann cell-line SNF96.2 and hiPSCs-derived sensory neurons. The outcome of the work could potentially offer a novel therapeutic strategy for treating pain by targeting alternative splicing of hTRPA1. |
Modulation of septo-hippocampal neural responses in anesthetized and behaving rats by septal AMPA receptor mechanisms |
| Ibrahim KM, Ariffin MZ, Khanna S |
| Frontiers in Neural Circuits, 04 Jun 2021, 15:663633. DOI: 10.3389/fncir.2021.663633 |
| Abstract |
| This study explored the effects of septal glutamatergic transmission on septal-hippocampal theta activity via intraseptal microinjection of antagonist at AMPA receptors (AMPAR). The current results showed that microinjection of AMPAR antagonist, NBQX (2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione, 20 μg/μl, 0.5 μl), evoked a decrease in the frequency of theta activity evoked by various means in anesthetized and behaving rat. Theta wave activity was induced on: (a) intraseptal microinjection of carbachol, an agonist at cholinergic receptors, (b) reticular stimulation, (c) exploration in novel open field (OF), and (d) hind paw (HP) injection of the algogen, formalin. The effect on frequency in the formalin test was observed in an early period on injection of formalin, which was novel to the animal, but not in the later more sustained phase of the formalin test. The effect of NBQX, being seen in both anesthetized and behaving animals, suggests that the modulation of theta wave frequency, including in novelty, is a function of AMPAR in MS. The effect of the antagonist on theta power was less apparent, being observed only in anesthetized animals. In addition to theta power and frequency, intraseptal NBQX also attenuated suppression of CA1 population spike (PS) induced by intraseptal carbachol, thus suggesting that septal glutamate neurotransmission is involved in the spectrum of MS-mediated network responses. Indeed, in the context of behavior, formalin injection induced an increase in the level of septal glutamate, while NBQX attenuated nociceptive behaviors. Notably, MS is involved in the modulation of formalin nociception. These findings suggest that AMPA receptors are a key modulator of septal physiological function. |
Establishing intensifying chronic exposure to extreme heat as a slow onset event with implications for health, wellbeing, productivity, society and economy |
| Elspeth Oppermann, Tord Kjellstrom, Bruno Lemke, Matthias Otto, Jason Kai Wei Lee |
| Current Opinion in Environmental Sustainability, Volume 50, June 2021, Pages 225-235. DOI: 10.1016/j.cosust.2021.04.006. |
| Abstract |
| The Warsaw International Mechanism for Loss and Damage has identified increasing temperatures as a key slow onset event. However, it is the resulting increases in short-term heat events — heatwaves — that have so far been the primary focus of risk assessment and policy, while gradual and sustained increases in temperature have received less attention. This is a global issue but particularly important in tropical and subtropical regions already chronically exposed to extreme heat. This paper reviews recent analyses of intensifying seasonal and year-round extreme heat exposures and how this affects daily life, including worker productivity, health and wellbeing, reduced GDP and economic viability. It frames this as a slow onset event and closes with a brief indication of tools available to assess and address these risks. |
The Impact of Temperature on the Risk of COVID-19: A Multinational Study |
| Hsiao-Yu Yang and Jason Kai Wei Lee |
| Int. J. Environ. Res. Public Health 2021, 18(8), 4052. DOI: 10.3390/ijerph18084052. |
| Abstract |
| The current understanding of ambient temperature and its link to the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unclear. The objective of this study was to explore the environmental and climatic risk factors for SARS-CoV-2. For this study, we analyzed the data at the beginning of the outbreak (from 20 January to 31 March 2020) to avoid the influence of preventive or control measures. We obtained the number of cases and deaths due to SARS-CoV-2, international tourism, population age, universal health coverage, regional factors, the SARS-CoV-2 testing rate, and population density of a country. A total of 154 countries were included in this study. There were high incidence rates and mortality risks in the countries that had an average ambient temperature between 0 and 10 °C. The adjusted incidence rate for temperatures between 0 and 10 °C was 2.91 (95% CI 2.87–2.95). We randomly divided the data into a training set (80% of data) for model derivation and a test set (20% of data) for validation. Using a random forest statistical model, the model had high accuracy for predicting the high epidemic status of a country (ROC = 95.5%, 95% CI 87.9–100.0%) in the test set. Population age, temperature, and international tourism were the most important factors affecting the risk of SARS-CoV-2 in a country. An understanding the determinants of the SARS-CoV-2 outbreak can help to design better strategies for disease control. This study highlights the need to consider thermal effect in the prevention of emerging infectious diseases. |
Hydration Status, Fluid Intake, Sweat Rate, and Sweat Sodium Concentration in Recreational Tropical Native Runners |
| Juthamard Surapongchai, Vitoon Saengsirisuwan, Ian Rollo, Rebecca K. Randell, Kanpiraya Nithitsuttibuta, Patarawadee Sainiyom, Clarence Hong Wei Leow and Jason Kai Wei Lee |
| Nutrients 2021, 13(4), 1374. DOI: 10.3390/nu13041374. |
| Abstract |
| Aim: The purpose of this study was to evaluate hydration status, fluid intake, sweat rate, and sweat sodium concentration in recreational tropical native runners. Methods: A total of 102 males and 64 females participated in this study. Participants ran at their self-selected pace for 30–100 min. Age, environmental conditions, running profiles, sweat rates, and sweat sodium data were recorded. Differences in age, running duration, distance and pace, and physiological changes between sexes were analysed. A p-value cut-off of 0.05 depicted statistical significance. Results: Males had lower relative fluid intake (6 ± 6 vs. 8 ± 7 mL·kg−1·h−1, p < 0.05) and greater relative fluid balance deficit (−13 ± 8 mL·kg−1·h−1 vs. −8 ± 7 mL·kg−1·h−1, p < 0.05) than females. Males had higher whole-body sweat rates (1.3 ± 0.5 L·h−1 vs. 0.9 ± 0.3 L·h−1, p < 0.05) than females. Mean rates of sweat sodium loss (54 ± 27 vs. 39 ± 22 mmol·h−1) were higher in males than females (p < 0.05). Conclusions: The sweat profile and composition in tropical native runners are similar to reported values in the literature. The current fluid replacement guidelines pertaining to volume and electrolyte replacement are applicable to tropical native runners. |
COVID-19 and heat waves: New challenges for healthcare systems |
| Stephan Bose-O’Reilly, Hein Daanen, Katharina Deering, Nicola Gerrett, Maud Maria Theresia Elisabeth Huynen, Jason Lee, Stefan Karrasch, Franziska Matthies-Wiesler, Hanna Mertes, Julia Schoierer, Joy Shumake-Guillemot, Petervan den Hazel, Joris Adriaan Frank van Loenhout, Dennis Nowak |
| Environmental Research, Volume 198, July 2021, 111153. DOI: 10.1016/j.envres.2021.111153. |
| Abstract |
| Heat waves and Covid-19 overlap, as this pandemic continues into summer 2021. Using a narrative review, we identified overlapping risk groups and propose coping strategies. The high-risk groups for heat-related health problems as well as for high-risk COVID-19 groups overlap considerably (elderly with pre-existing health conditions). Health care facilities will again be challenged by Covid-19 during heat waves. Health care personnel are also at risk of developing heat related health problems during hot periods due to the use of personal protective equipment to shield themselves from SARS-CoV-2 and must therefore be protected from excessive heat periods. Some existing recommendations for heat health protection contradict recommendations for COVID-19 protection. This paper provides a preliminary overview of possible strategies and interventions to tackle these ambiguities. The existing recommendations for protection against heat-related illnesses need revisions to determine whether they include essential aspects of infection control and occupational safety and how they may be supplemented. |
A Web Survey to Evaluate the Thermal Stress Associated with Personal Protective Equipment among Healthcare Workers during the COVID-19 Pandemic in Italy |
| Alessandro Messeri, Michela Bonafede, Emma Pietrafesa, Iole Pinto, Francesca de’Donato, Alfonso Crisci, Jason Kai Wei Lee, Alessandro Marinaccio, Miriam Levi, Marco Morabito and on behalf of the WORKLIMATE Collaborative Group |
| Int. J. Environ. Res. Public Health 2021, 18(8), 3861. DOI: 10.3390/ijerph18083861. |
| Abstract |
| The pandemic has been afflicting the planet for over a year and from the occupational point of view, healthcare workers have recorded a substantial increase in working hours. The use of personal protective equipment (PPE), necessary to keep safe from COVID-19 increases the chances of overheating, especially during the summer seasons which, due to climate change, are becoming increasingly warm and prolonged. A web survey was carried out in Italy within the WORKLIMATE project during the summer and early autumn 2020. Analysis of variance (ANOVA) was used to evaluate differences between groups. 191 questionnaires were collected (hospital doctor 38.2%, nurses 33.5%, other healthcare professionals 28.3%). The impact of PPE on the thermal stress perception declared by the interviewees was very high on the body areas directly covered by these devices (78% of workers). Workers who used masks for more than 4 h per day perceived PPE as more uncomfortable (p < 0.001) compared to the others and reported a greater productivity loss (p < 0.001). Furthermore, the study highlighted a high perception of thermal stress among healthcare workers that worn COVID-19-PPE and this enhances the need for appropriate heat health warning systems and response measures addressed to the occupational sector. |
Thermal strain and fluid balance during a 72-km military route march in a field setting |
| Beng Hoong Poon, Suriya Prakaash, Ya Shi Teo, Priscilla Weiping Fan, Jason Kai Wei Lee |
| Singapore Med J 2021, 1–18. DOI: 10.11622/smedj.2021053. |
| Abstract |
| Introduction: A physiological profiling study was done to evaluate thermal strain as well as fluid and electrolyte balances on heat-acclimatised men performing a 72-km route march in a field setting. Methods: 38 male soldiers (age range 18–23 years) participated in the study,as part of a cohort that marched for 72 km, with loads for about 26 hours. Core temperature and heart rate sensors were used for the duration of the march. Fluid and food intake and output were monitored for the duration of the march. Blood samples were taken one day before the march (pre-march),immediately after the march before they had any opportunity to recover (Post 1) and on the 15thday after themarch to ascertain recovery (Post2) to assess fluid and electrolyte profiles. Results: Mean core temperature was within safe limits, ranging from 37.1to 38.1°C throughout the march. There was an average overall decrease in serum sodium levels, a decline in serum sodium concentration in 28 participants and three instances of hyponatraemia (serum sodium concentration< 135 mmol/L). Conclusion: Our study found low thermal strain among heat-acclimatised individuals during a 72-km route march. However, there was an average overall decrease in serum sodium levels,even when the participants were allowed to drink ad libitum. Challenges of exercise-associated hyponatraemia during prolonged activities remain to be addressed. |
The redox-senescence axis and its therapeutic targeting |
| Natalie YL Ngoi, Angeline QX Liew, Stephen J.F. Chong, Matthew S. Davids, Marie-Veronique Clement, Shazib Pervaiz |
| Redox Biology, Volume 45, September 2021, 102032. DOI: 10.1016/j.redox.2021.102032. |
| Abstract |
| Significance Cellular growth arrest, associated with ‘senescence’, helps to safeguard against the accumulation of DNA damage which is often recognized as the underlying mechanism of a wide variety of age-related pathologies including cancer. Cellular senescence has also been described as a ‘double-edged sword’. In cancer, for example, the creation of an immune-suppressive milieu by senescent tumor cells through the senescence-associated secretory phenotype contributes toward carcinogenesis and cancer progression. Recent advances The potential for cellular senescence to confer multi-faceted effects on tissue fate has led to a rejuvenated interest in its landscape and targeting. Interestingly, redox pathways have been described as both triggers and propagators of cellular senescence, leading to intricate cross-links between both pathways. Critical issues In this review, we describe the mechanisms driving cellular senescence, the interface with cellular redox metabolism as well as the role that chemotherapy-induced senescence plays in secondary carcinogenesis. Notably, the role that anti-apoptotic proteins of the Bcl-2 family play in inducing drug resistance via mechanisms that involve senescence induction. Future directions Though the therapeutic targeting of senescent cells as cancer therapy remains in its infancy, we summarize the current development of senotherapeutics, including recognized senotherapies, as well as the repurposing of drugs as senomorphic/senolytic candidates. |
A Novel Balanced Chromosomal Translocation in an Azoospermic Male: A Case Report |
| Abhik Chakraborty, Indira Palo, Souvick Roy, Shu Wen Koh, Manoor Prakash Hande, Birendranath Banerjee |
| J Reprod Infertil. Apr-Jun 2021;22(2):133-137. doi: 10.18502/jri.v22i2.5802. |
| Abstract |
| Background: Balanced translocation and azoospermia as two main reasons for recurrent pregnancy loss are known to be the leading causes of infertility across the world. Balanced translocations in azoospermic males are very rare and extensive studies need to be performed to elucidate the translocation status of the affected individuals. Case presentaion: The cytogenetic characterization of a 28 year old male and his female partner is reported in this study. The male partner was diagnosed with non-obstructive azoospermia (NOA) and the couple was unable to conceive. Cytogenetic analysis by karyotyping through Giemsa-trypsin-giemsa banding technique (GTG) showed a novel balanced translocation, 46,XY,t(19;22)(19q13.4;22q11.2), 13ps+ in the male and the female karyotype was found to be 46,XX. Multicolor fluorescence in situ hybridization (mFISH) analysis on paternal chromosomal preparations confirmed both the region and origin of balanced translocation. The status of Y chromosome microdeletion (YMD) was analyzed and no notable microdeletion was observed. Furthermore, protein-protein interaction (PPI) network analysis was performed for breakpoint regions to explore the possible functional genetic associations. Conclusion: The azoospermic condition of the male patient along with novel balanced chromosomal translocation was responsible for infertility irrespective of its YMD status. Therefore, cytogenetic screening of azoospermic patients should be performed in addition to routine semen analysis to rule out or to confirm presence of any numerical or structural anomaly in the patient. |
RENEB Inter-Laboratory comparison 2017: limits and pitfalls of ILCs |
| Eric Gregoire, Joan Francesc Barquinero, Gaetan Gruel, Mohamedamine Benadjaoud, Juan S Martinez, Christina Beinke, Adayabalam Balajee, Philip Beukes, William F Blakely, Inmaculada Dominguez, Pham Ngoc Duy, Octávia Monteiro Gil, Inci Güçlü, Kamile Guogyte, Savina Petrova Hadjidekova, Valeria Hadjidekova, Prakash Hande, Seongjae Jang, Katalin Lumniczky, Roberta Meschini, Mirta Milic, Alegria Montoro, Jayne Moquet, Mercedes Moreno, Farrah N Norton, Ursula Oestreicher, Jelena Pajic, Laure Sabatier, Sylwester Sommer, Antonella Testa, Georgia Terzoudi, Marco Valente, Perumal Venkatachalam, Anne Vral, Ruth C Wilkins, Andrzej Wojcik, Demetre Zafiropoulos, Ulrike Kulka |
| Int J Radiat Biol. 2021 May 25;1-18. doi: 10.1080/09553002.2021.1928782. Online ahead of print. |
| Abstract |
| Purpose: In case of a mass-casualty radiological event, there would be a need for networking to overcome surge limitations and to quickly obtain homogeneous results (reported aberration frequencies or estimated doses) among biodosimetry laboratories. These results must be consistent within such network. Inter-laboratory comparisons (ILCs) are widely accepted to achieve this homogeneity. At the European level, a great effort has been made to harmonize biological dosimetry laboratories, notably during the MULTIBIODOSE and RENEB projects. In order to continue the harmonization efforts, the RENEB consortium launched this intercomparison which is larger than the RENEB network, as it involves 38 laboratories from 21 countries. In this ILC all steps of the process were monitored, from blood shipment to dose estimation. This exercise also aimed to evaluate the statistical tools used to compare laboratory performance. Materials and methods: Blood samples were irradiated at three different doses, 1.8, 0.4 and 0 Gy (samples A, C and B) with 4-MV X-rays at 0.5 Gy min-1, and sent to the participant laboratories. Each laboratory was requested to blindly analyze 500 cells per sample and to report the observed frequency of dicentric chromosomes per metaphase and the corresponding estimated dose. Results: This ILC demonstrates that blood samples can be successfully distributed among laboratories worldwide to perform biological dosimetry in case of a mass casualty event. Having achieved a substantial harmonization in multiple areas among the RENEB laboratories issues were identified with the available statistical tools, which are not capable to advantageously exploit the richness of results of a large ILCs. Even though Z- and U-tests are accepted methods for biodosimetry ILCs, setting the number of analyzed metaphases to 500 and establishing a tests' common threshold for all studied doses is inappropriate for evaluating laboratory performance. Another problem highlighted by this ILC is the issue of the dose-effect curve diversity. It clearly appears that, despite the initial advantage of including the scoring specificities of each laboratory, the lack of defined criteria for assessing the robustness of each laboratory's curve is a disadvantage for the 'one curve per laboratory' model. Conclusions: Based on our study, it seems relevant to develop tools better adapted to the collection and processing of results produced by the participant laboratories. We are confident that, after an initial harmonization phase reached by the RENEB laboratories, a new step toward a better optimization of the laboratory networks in biological dosimetry and associated ILC is on the way. |
Recent Advances in Models of Immune-Mediated Drug-Induced Liver Injury |
| Farah Tasnim, Xiaozhong Huang, Christopher Zhe Wei Lee, Florent Ginhoux and Hanry Yu |
| Frontiers in Toxicology, 21 April 2021; 3: 6053892. doi: 10.3389/ftox.2021.605392. |
| Abstract |
| Hepatic inflammation is a key feature of a variety of liver diseases including drug-induced liver injury (DILI), orchestrated by the innate immune response (Kupffer cells, monocytes, neutrophils, dendritic cells) and the adaptive immune system (T cells and natural killer T cells). In contrast to acute DILI, prediction of immune-mediated DILI (im-DILI) has been more challenging due to complex disease pathogenesis, lack of reliable models and limited knowledge of underlying mechanisms. This review summarizes in vivo and in vitro systems that have been used to model im-DILI. In particular, the review focuses on state-of-the-art in vitro human-based multicellular models which have been developed to supplement the use of in vivo models due to interspecies variation and increasing ethical concerns regarding animal use. Advantages of the co-cultures in maintaining hepatocyte functions and importantly, introducing heterotypic cell-cell interactions to mimic inflammatory hepatic microenvironment are discussed. Challenges regarding cell source and incorporation of different cells with physical cell-cell contact are outlined and potential solutions are proposed. It is likely that better understanding of the interplay of immune cells in liver models will allow for the development of more accurate systems to better predict hepatotoxicity and stratification of drugs that can cause immune-mediated effects. |
Design and Fabrication of the Vertical-Flow Bioreactor for Compaction Hepatocyte Culture in Drug Testing Application |
| Liang Zhu, Zhenfeng Wang, Huanming Xia, and Hanry Yu |
| Biosensors-Basel, May 2021; 11(5): 160. doi: 10.3390/bios11050160. |
| Abstract |
| The perfusion culture of primary hepatocytes has been widely adopted to build bioreactors for various applications. As a drug testing platform, a unique vertical-flow bioreactor (VfB) array was found to create the compaction culture of hepatocytes which mimicked the mechanic microenvironment in vivo while maintaining the 3D cell morphology in a 2D culture setup and enhancing the hepatic functions for a sustained culture. Here, we report the methodology in designing and fabricating the VfB to reach ideal bioreactor requirements, optimizing the VfB as a prototype for drug testing, and to demonstrate the enhanced hepatic function so as to demonstrate the performance of the bioreactor. This device enables the modular, scalable, and manufacturable construction of a functional drug testing platform through the sustained maintenance of model cells. |
A Scalable and Sensitive Steatosis Chip with Long-Term Perfusion of in situ Differentiated HepaRG Organoids |
| Yao Teng, Zixuan Zhao, Farah Tasnim, Xiaozhong Huang, HanryYu |
| Biomaterials. Available online 1 June 2021, 120904. doi: 10.1016/j.biomaterials.2021.120904. |
| Abstract |
| Nonalcoholic fatty liver disease (NAFLD) is a significant liver disease without approved therapy, lacking human NAFLD models to aid drug development. Existing models are either under-performing or too complex to allow robust drug screening. Here we have developed a 100-well drug testing platform with improved HepaRG organoids formed with uniform size distribution, and differentiated in situ in a perfusion microfluidic device, SteatoChip, to recapitulate major NAFLD features. Compared with the pre-differentiated spheroids, the in situ differentiated HepaRG organoids with perfusion experience well-controlled chemical and mechanical microenvironment, and 3D cellular niche, to exhibit enhanced hepatic differentiation (albumin+ cells ratio: 66.2% in situ perfusion vs 46.1% pre-differentiation), enriched and uniform hepatocyte distribution in organoids, higher level of hepatocyte functions (5.2 folds in albumin secretion and 7.6 folds in urea synthesis), enhanced cell polarity and bile canaliculi structures. When induced with free fatty acid (FFA), cells exhibit significantly higher level of lipid accumulation (6.6 folds for in situ perfusion vs 4.4 folds for pre-differentiation), altered glucose regulation and reduced Akt phosphorylation in the organoids. SteatoChip detects reduction of steatosis when cells are incubated with three different anti-steatosis compounds, 78.5% by metformin hydrochloride, 71.3% by pioglitazone hydrochloride and 66.6% by obeticholic acid, versus the control FFA-free media (38% reduction). The precision microenvironment control in SteatoChip enables improved formation, differentiation, and function of HepaRG organoids to serve as a scalable and sensitive drug testing platform, to potentially accelerate the NAFLD drug development. |
Digital CRISPR-based method for the rapid detection and absolute quantification of nucleic acids |
| Xiaolin Wu, Joshua K. Tay, Chuan Keng Goh, Cheryl Chan, Yie Hou Lee, Stacy L. Springs, De Yun Wang, Kwok Seng Loh, Timothy K. Lu, Hanry Yu |
| Biomaterials. Volume 274, July 2021, 120876. doi: 10.1016/j.biomaterials.2021.120876. |
| Abstract |
| Rapid diagnostics of adventitious agents in biopharmaceutical/cell manufacturing release testing and the fight against viral infection have become critical. Quantitative real-time PCR and CRISPR-based methods rapidly detect DNA/RNA in 1 h but suffer from inter-site variability. Absolute quantification of DNA/RNA by methods such as digital PCR reduce this variability but are currently too slow for wider application. Here, we report a RApid DIgital Crispr Approach (RADICA) for absolute quantification of nucleic acids in 40-60 min. Using SARS-CoV-2 as a proof-of-concept target, RADICA allows for absolute quantification with a linear dynamic range of 0.6–2027 copies/μL (R2 value > 0.99), high accuracy and low variability, no cross-reactivity to similar targets, and high tolerance to human background DNA. RADICA's versatility is validated against other targets such as Epstein-Barr virus (EBV) from human B cells and patients' serum. RADICA can accurately detect and absolutely quantify EBV DNA with similar dynamic range of 0.5–2100 copies/μL (R2 value > 0.98) in 1 h without thermal cycling, providing a 4-fold faster alternative to digital PCR-based detection. RADICA therefore enables rapid and sensitive absolute quantification of nucleic acids which can be widely applied across clinical, research, and biomanufacturing areas. |
Isolation of Primary Rat Hepatocytes with Multiparameter Perfusion Control |
| Inn Chuan Ng, Li Zhang, Narelle Nichola Yi Ying Shen, Yun Ting Soong, Chan Way Ng, Phoebe Kang Sheing Koh, Yan Zhou, Hanry Yu |
| J Vis Exp. 2021 Apr 5;(170). doi: 10.3791/62289. |
| Abstract |
| Primary hepatocytes are widely used in basic research on liver diseases and for toxicity testing in vitro. The two-step collagenase perfusion procedure for primary hepatocyte isolation is technically challenging, especially in portal vein cannulation. The procedure is also prone to occasional contamination and variations in perfusion conditions due to difficulties in the assembly, optimization, or maintenance of the perfusion setup. Here, a detailed protocol for an improved two-step collagenase perfusion procedure with multiparameter perfusion control is presented. Primary rat hepatocytes were successfully and reliably isolated by taking the necessary technical precautions at critical steps of the procedure, and by reducing the operational difficulty and mitigating the variability of perfusion parameters through the adoption of a special intravenous catheter, standardized sterile disposable tubing, temperature control, and real-time monitoring and alarm system. The isolated primary rat hepatocytes consistently exhibit high cell viability (85%-95%), yield (2-5 x 108 cells per 200-300 g rat) and functionality (albumin, urea and CYP activity). The procedure was complemented by an integrated perfusion system, which is compact enough to be set up in the laminar flow hood to ensure aseptic operation. |
Three-Dimensional Macroporous Sponge for the Culture of Hepatocellular Carcinoma Patient-Derived Xenograft Organoids |
| Tan Boon Toh, Zheng Liu, Hanry Yu, Eliza Li Shan Fong |
| SLAS Technology, (2021), First Published March 27, 2021. doi: 10.1177/24726303211000685. |
| Abstract |
| This protocol focuses on the culture of cells harvested from hepatocellular carcinoma (HCC) patient-derived xenografts (PDXs) as organoids using a cellulosic macroporous sponge scaffold. Compared with many other epithelial cancer types, the viability of HCC cells directly derived from patients or PDX models is notoriously challenging to maintain in vitro. We previously developed a macroporous sponge scaffold uniquely designed to provide biochemical and mechanical cues that support the culture of normal hepatocytes as spheroids with maintained functionality. Leveraging our success using this sponge scaffold to maintain normal hepatocytes in vitro, we recently demonstrated that a similar sponge scaffold enables the maintenance of HCC PDX cells as organoids with preserved viability, molecular features, and heterogeneity. |
Cytoskeletal Dynamics in Epithelial-Mesenchymal Transition: Insights into Therapeutic Targets for Cancer Metastasis |
| Arpita Datta, Shuo Deng, Vennila Gopal, Kenneth Chun-Hong Yap, Clarissa Esmeralda Halim, Mun Leng Lye, Mei Shan Ong, Tuan Zea Tan, Gautam Sethi, Shing Chuan Hooi, Alan Prem Kumar, and Celestial T. Yap |
| Cancers 2021, 13(8), 1882. doi: 10.3390/cancers13081882. |
| Abstract |
| In cancer cells, a vital cellular process during metastasis is the transformation of epithelial cells towards motile mesenchymal cells called the epithelial to mesenchymal transition (EMT). The cytoskeleton is an active network of three intracellular filaments: actin cytoskeleton, microtubules, and intermediate filaments. These filaments play a central role in the structural design and cell behavior and are necessary for EMT. During EMT, epithelial cells undergo a cellular transformation as manifested by cell elongation, migration, and invasion, coordinated by actin cytoskeleton reorganization. The actin cytoskeleton is an extremely dynamic structure, controlled by a balance of assembly and disassembly of actin filaments. Actin-binding proteins regulate the process of actin polymerization and depolymerization. Microtubule reorganization also plays an important role in cell migration and polarization. Intermediate filaments are rearranged, switching to a vimentin-rich network, and this protein is used as a marker for a mesenchymal cell. Hence, targeting EMT by regulating the activities of their key components may be a potential solution to metastasis. This review summarizes the research done on the physiological functions of the cytoskeleton, its role in the EMT process, and its effect on multidrug-resistant (MDR) cancer cells—highlight some future perspectives in cancer therapy by targeting cytoskeleton. |
FEZ1 forms complexes with CRMP1 and DCC to regulate axon and dendrite development |
| Jie Yin Chua, Shi Jun Ng, Oleksandr Yagensky, Erich E Wanker and John Jia En Chua |
| eNeuro 26 March 2021, ENEURO.0193-20.2021; DOI: https://doi.org/10.1523/ENEURO.0193-20.2021 |
| Abstract |
| Elaboration of neuronal processes is an early step in neuronal development. Guidance cues must work closely with intracellular trafficking pathways to direct expanding axons and dendrites to their target neurons during the formation of neuronal networks. However, how such coordination is achieved remains incompletely understood. Here, we characterize an interaction between FEZ1, an adapter involved in synaptic protein transport, and CRMP1, a protein that functions in growth cone guidance, at neuronal growth cones. We show that similar to CRMP1 loss-of-function mutants, FEZ1 deficiency in rat hippocampal neurons causes growth cone collapse and impairs axonal development. Strikingly, FEZ1-deficient neurons also exhibited a reduction in dendritic complexity stronger than that observed in CRMP1-deficient neurons, suggesting that the former could partake in additional developmental signaling pathways. Supporting this, FEZ1 colocalizes with VAMP2 in developing hippocampal neurons and forms a separate complex with Deleted in Colorectal Cancer and Syntaxin-1, components of the Netrin-1 signaling pathway that are also involved in regulating axon and dendrite development. Significantly, developing axons and dendrites of FEZ1-deficient neurons fail to respond to Netrin-1 or Netrin-1 and Sema3A treatment, respectively. Taken together, these findings highlight the importance of FEZ1 as a common effector to integrate guidance signaling pathways with intracellular trafficking to mediate axo-dendrite development during neuronal network formation. |
Assessment of dehydration using body mass changes of elite marathoners in the tropics |
| Xiang Ren Tan, Ivan Cherh Chiet Low, Chris Byrne, Ru Wang, Jason Kai Wei Lee |
| Journal of Science and Medicine in Sport. Available online 31 January 2021. doi: 10.1016/j.jsams.2021.01.008 |
| Abstract |
| Objectives The ACSM recommends drinking to avoid loss of body mass >2% during exercise to avert compromised performance. Our study aimed to assess the level of dehydration in elite runners following a city marathon in a tropical environment. Design Prospective cohort design. Methods Twelve elite runners (6 males, 6 females; age 24–41 y) had body mass measured to the nearest 0.01 kg in their race attire immediately before and after the 2017 Standard Chartered Singapore Marathon 2017. Body mass change was corrected for respiratory water loss, gas exchange, and sweat retained in clothing, and expressed as % of pre-race mass (i.e. % dehydration). Results Data are expressed as means ± SD (range). Dry bulb temperature and humidity were 27.9 ± 0.1 °C (27.4–28.3 °C) and 79 ± 2% (73–82%). Finish time was 155 ± 10 min (143−172 min). Male runners finishing positions ranged from 2–12 out of 7627 finishers, whilst female runners placed 1–8 out of 1754 finishers. Body mass change (loss) and % dehydration for all runners were 2.5 ± 0.5 kg (1.8–3.5 kg) and 4.6 ± 0.9% (3.6–6.8%). Male runners experienced body mass loss of 2.8 ± 0.5 kg and 4.9 ± 1.2% while females experienced body mass loss of 2.1 ± 0.2 kg and 4.3 ± 0.6%. Conclusions Despite experiencing dehydration (4.6% body mass loss) two-fold higher than current fluid replacement guidelines recommend (≤2%), elite male and female runners performed successfully and without medical complication in a hot weather marathon. |
Dysfunction in nonsense-mediated decay, protein homeostasis, mitochondrial function, and brain connectivity in ALS-FUS mice with cognitive deficits |
| Wan Yun Ho, Ira Agrawal, Sheue-Houy Tyan, Emma Sanford, Wei-Tang Chang, Kenneth Lim, Jolynn Ong, Bernice Siu Yan Tan, Aung Aung Kywe Moe, Regina Yu, Peiyan Wong, Greg Tucker-Kellogg, Edward Koo, Kai-Hsiang Chuang, Shuo-Chien Ling |
| Acta Neuropathol Commun. 2021 Jan 6;9(1):9. doi: 10.1186/s40478-020-01111-4. |
| Abstract |
| Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) represent two ends of the same disease spectrum of adult-onset neurodegenerative diseases that affect the motor and cognitive functions, respectively. Multiple common genetic loci such as fused in sarcoma (FUS) have been identified to play a role in ALS and FTD etiology. Current studies indicate that FUS mutations incur gain-of-toxic functions to drive ALS pathogenesis. However, how the disease-linked mutations of FUS affect cognition remains elusive. Using a mouse model expressing an ALS-linked human FUS mutation (R514G-FUS) that mimics endogenous expression patterns, we found that FUS proteins showed an age-dependent accumulation of FUS proteins despite the downregulation of mouse FUS mRNA by the R514G-FUS protein during aging. Furthermore, these mice developed cognitive deficits accompanied by a reduction in spine density and long-term potentiation (LTP) within the hippocampus. At the physiological expression level, mutant FUS is distributed in the nucleus and cytosol without apparent FUS aggregates or nuclear envelope defects. Unbiased transcriptomic analysis revealed a deregulation of genes that cluster in pathways involved in nonsense-mediated decay, protein homeostasis, and mitochondrial functions. Furthermore, the use of in vivo functional imaging demonstrated widespread reduction in cortical volumes but enhanced functional connectivity between hippocampus, basal ganglia and neocortex in R514G-FUS mice. Hence, our findings suggest that disease-linked mutation in FUS may lead to changes in proteostasis and mitochondrial dysfunction that in turn affect brain structure and connectivity resulting in cognitive deficits. |
TDP-43 maximizes nerve conduction velocity by repressing a cryptic exon for paranodal junction assembly in Schwann cells |
| Kae-Jiun Chang, Ira Agrawal, Anna Vainshtein, Wan Yun Ho, Wendy Xin, Greg Tucker-Kellogg, Keiichiro Susuki, Elior Peles, Shuo-Chien Ling, Jonah R Chan |
| Elife. 2021 Mar 10;10:e64456. doi: 10.7554/eLife.64456. |
| Abstract |
| TDP-43 is extensively studied in neurons in physiological and pathological contexts. However, emerging evidence indicates that glial cells are also reliant on TDP-43 function. We demonstrate that deletion of TDP-43 in Schwann cells results in a dramatic delay in peripheral nerve conduction causing significant motor deficits in mice, which is directly attributed to the absence of paranodal axoglial junctions. By contrast, paranodes in the central nervous system are unaltered in oligodendrocytes lacking TDP-43. Mechanistically, TDP-43 binds directly to Neurofascin mRNA, encoding the cell adhesion molecule essential for paranode assembly and maintenance. Loss of TDP-43 triggers the retention of a previously unidentified cryptic exon, which targets Neurofascin mRNA for nonsense-mediated decay. Thus, TDP-43 is required for neurofascin expression, proper assembly and maintenance of paranodes, and rapid saltatory conduction. Our findings provide a framework and mechanism for how Schwann cell-autonomous dysfunction in nerve conduction is directly caused by TDP-43 loss-of-function. |
Regulatory T Cells Inhibit T Cell Activity by Downregulating CD137 Ligand via CD137 Trogocytosis |
| Khang Luu, Mugdha Vijay Patwardhan, Qun Zeng, Stina L Wickström, Andreas Lundqvist, Herbert Schwarz |
| Cells. 2021 Feb 9;10(2):353. doi: 10.3390/cells10020353. |
| Abstract |
| CD137 is a costimulatory molecule expressed on activated T cells. CD137 ligand (CD137L) is expressed by antigen presenting cells (APC), which use the CD137-CD137L system to enhance immune responses. It was, therefore, surprising to discover CD137 expression on regulatory T cells (Treg). The function of CD137 in Treg are controversial. While some studies report that CD137 signalling converts Treg to effector T cells (Teff), other studies find that CD137-expressing Treg display a stronger inhibitory activity than CD137- Treg. Here, we describe that CD137 on Treg binds to CD137L on APC, upon which one of the two molecules is transferred via trogocytosis to the other cell, where CD137-CD137L forms a complex that is internalized and deprives APC of the immune-stimulatory CD137L. Truncated forms of CD137 that lack the cytoplasmic domain of CD137 are also able to downregulate CD137L, demonstrating that CD137 signalling is not required. Comparable data have been obtained with human and murine cells, indicating that this mechanism is evolutionarily conserved. These data describe trogocytosis of CD137 and CD137L as a new mechanism employed by Treg to control immune responses by downregulating the immunostimulatory CD137L on APC. |
Ectopic CD137 expression by rhabdomyosarcoma provides selection advantages but allows immunotherapeutic targeting |
| Kang Yi Lee, Hiu Yi Wong, Qun Zeng, Jia Le Lin, Man Si Cheng, Chik Hong Kuick, Kenneth Tou En Chang, Amos Hong Pheng Loh, Herbert Schwarz |
| Oncoimmunology. 2021 Feb 4;10(1):1877459. doi: 10.1080/2162402X.2021.1877459. |
| Abstract |
| Rhabdomyosarcoma (RMS) is a heterogeneous soft tissue neoplasm most frequently found in children and adolescents. As the prognosis for recurrent and metastatic RMS remains poor, immunotherapies are hoped to improve quality of life and survival. CD137 is a member of tumor necrosis factor receptor family and a T cell costimulatory molecule which induces potent cellular immune responses that are able to eliminate malignant cells. Therefore, it was puzzling to find expression of CD137 on an RMS tissue microarray by multiplex staining. CD137 is not only expressed by infiltrating T cells but also by malignant RMS cells. Functional in vitro experiments demonstrate that CD137 on RMS cells is being transferred to adjacent antigen-presenting cells by trogocytosis, where it downregulates CD137 ligand, and thereby reduces T cell costimulation which results in reduced killing of RMS cells. The transfer of CD137 and the subsequent downregulation of CD137 ligand is a physiological negative feedback mechanism that is likely usurped by RMS, and may facilitate its escape from immune surveillance. In addition, CD137 signals into RMS cells and induces IL-6 and IL-8 secretion, which are linked to RMS metastasis and poor prognosis. However, the ectopic expression of CD137 on RMS cells is an Achilles' heel that may be utilized for immunotherapy. Natural killer cells expressing an anti-CD137 chimeric antigen receptor specifically kill CD137-expressing RMS cells. Our study implicates ectopic CD137 expression as a pathogenesis mechanism in RMS, and it demonstrates that CD137 may be a novel target for immunotherapy of RMS. |
Age-related changes in hippocampal-dependent synaptic plasticity and memory mediated by p75 neurotrophin receptor |
| Lik-Wei Wong, Yee Song Chong, Wei Lin, Lilian Kisiswa, Eunice Sim, Carlos F Ibáñez, Sreedharan Sajikumar |
| Aging Cell. 2021 Feb;20(2):e13305. doi: 10.1111/acel.13305. Epub 2021 Jan 15. |
| Abstract |
| The plasticity mechanisms in the nervous system that are important for learning and memory are greatly impacted during aging. Notably, hippocampal-dependent long-term plasticity and its associative plasticity, such as synaptic tagging and capture (STC), show considerable age-related decline. The p75 neurotrophin receptor (p75NTR ) is a negative regulator of structural and functional plasticity in the brain and thus represents a potential candidate to mediate age-related alterations. However, the mechanisms by which p75NTR affects synaptic plasticity of aged neuronal networks and ultimately contribute to deficits in cognitive function have not been well characterized. Here, we report that mutant mice lacking the p75NTR were resistant to age-associated changes in long-term plasticity, associative plasticity, and associative memory. Our study shows that p75NTR is responsible for age-dependent disruption of hippocampal homeostatic plasticity by modulating several signaling pathways, including BDNF, MAPK, Arc, and RhoA-ROCK2-LIMK1-cofilin. p75NTR may thus represent an important therapeutic target for limiting the age-related memory and cognitive function deficits. |
Exercise rescues mitochondrial coupling in aged skeletal muscle: a comparison of different modalities in preventing sarcopenia |
| Colin Harper, Venkatesh Gopalan, Jorming Goh |
| J Transl Med. 2021 Feb 16;19(1):71. doi: 10.1186/s12967-021-02737-1. |
| Abstract |
| Skeletal muscle aging is associated with a decline in motor function and loss of muscle mass- a condition known as sarcopenia. The underlying mechanisms that drive this pathology are associated with a failure in energy generation in skeletal muscle, either from age-related decline in mitochondrial function, or from disuse. To an extent, lifelong exercise is efficacious in preserving the energetic properties of skeletal muscle and thus may delay the onset of sarcopenia. This review discusses the cellular and molecular changes in skeletal muscle mitochondria during the aging process and how different exercise modalities work to reverse these changes. A key factor that will be described is the efficiency of mitochondrial coupling-ATP production relative to O2 uptake in myocytes and how that efficiency is a main driver for age-associated decline in skeletal muscle function. With that, we postulate the most effective exercise modality and protocol for reversing the molecular hallmarks of skeletal muscle aging and staving off sarcopenia. Two other concepts pertinent to mitochondrial efficiency in exercise-trained skeletal muscle will be integrated in this review, including- mitophagy, the removal of dysfunctional mitochondrial via autophagy, as well as the implications of muscle fiber type changes with sarcopenia on mitochondrial function. |
Slow Gait, Subjective Cognitive Decline and Motoric Cognitive RISK Syndrome: Prevalence and Associated Factors in Community Dwelling Older Adults |
| Reshma A Merchant, J Goh, Y H Chan, J Y Lim, B Vellas |
| J Nutr Health Aging. 2021;25(1):48-56. doi: 10.1007/s12603-020-1525-y. |
| Abstract |
| Background: Motoric Cognitive Risk Syndrome (MCR), slow gait speed (SG) and subjective cognitive decline (SCD) are known to be harbingers of dementia. MCR is known to be associated with a 3-fold increased risk of future dementia, while SG can precede cognitive impairment. Objective: We aim to determine the prevalence and demographics of MCR, slow gait alone (SG-A) and subjective cognitive decline alone (SCD-A) in community-dwelling older adults and association with physical, functional, cognition and psychosocial factors. Methods: A total of 509 participants were classified into four groups according to presence of SG and/or SCD. Multinomial logistic regression was used to identify the factors associated with SG-A, SCD-A and MCR. Results: The prevalence of MCR was 13.6%, SG-A 13.0% and SCD-A 35.0%. Prevalence of MCR doubled every decade in females with 27.7% of female ≥ 80 years old had MCR. Almost 4 in 10 had no SG or SCD (SG+SCD negative). MCR and SG-A groups were significantly older, had higher body mass index (BMI), lower education, lower global cognition scores especially in non-memory domains, higher prevalence of low grip strength and lower short physical performance battery scores than those with SCD-A and SG+SCD negative. In addition, the SG-A group had significantly higher prevalence of multi-morbidity and diabetes. The prevalence of pain, depression, frailty, social isolation and activity of daily living impairment were significantly higher in MCR. The global cognitive and functional scores for those with SCD-A were comparable to the SG+SCD negative group. The Malay ethnic group had the lowest prevalence of SCD but highest prevalence of SG. After adjusting for confounding factors, age, BMI, frailty status, instrumental activity of daily living, depression and pain remained significantly associated with MCR. For SG-A, age, BMI, education and number of chronic diseases remained significant. Conclusion: Both MCR and SG-A are associated with global cognitive decline especially in the non-memory domains and lower functional scores. Gait speed is a good predictor of negative outcomes and should be considered as the 'sixth' vital sign. Long term prospective studies are needed to evaluate: i) the conversion to dementia in different ethnic groups and ii) effect of targeted physical and / or dual task exercise on delaying the conversion to dementia and / or improvement in physical measures and reduction of disability. |
Loss of FEZ1, a gene deleted in Jacobsen syndrome, causes locomotion defects and early mortality by impairing motor neuron development |
| Saravanan Gunaseelan, Ziyin Wang, Venetia Kok Jing Tong, Sylvester Wong Shu Ming, Rafhanah Banu Bte Abdul Razar, Sumitra Srimasorn, Wei-Yi Ong, Kah-Leong Lim, John Jia En Chua |
| Hum Mol Genet. 2021 Jan 4;ddaa281. doi: 10.1093/hmg/ddaa281. |
| Abstract |
| FEZ1-mediated axonal transport plays important roles in central nervous system development but its involvement in the peripheral nervous system is not well-characterised. FEZ1 is deleted in Jacobsen syndrome (JS), an 11q terminal deletion developmental disorder. JS patients display impaired psychomotor skills, including gross and fine motor delay, suggesting that FEZ1 deletion may be responsible for these phenotypes, given its association with the development of motor-related circuits. Supporting this hypothesis, our data shows that FEZ1 is selectively expressed in the rat brain and spinal cord. Its levels progressively increase over the developmental course of human motor neurons derived from embryonic stem cells. Deletion of FEZ1 strongly impaired axon and dendrite development, and significantly delayed the transport of synaptic proteins into developing neurites. Concurring with these observations, Drosophila unc-76 mutants showed severe locomotion impairments, accompanied by a strong reduction of synaptic boutons at neuromuscular junctions. These abnormalities were ameliorated by pharmacological activation of UNC-51/ATG1, a FEZ1-activating kinase, with rapamycin and metformin. Collectively, the results highlight a role for FEZ1 in motor neuron development and implicate its deletion as an underlying cause of motor impairments in JS patients. |
Targeting novel human transient receptor potential ankyrin 1 splice variation with splice-switching antisense oligonucleotides |
| Huang, Hua; Tay, Shermaine Huiping; Ng, Winanto; Ng, Shi Yan; Soong, Tuck Wah |
| PAIN, in Press. doi: 10.1097/j.pain.0000000000002216 |
| Abstract |
| Activation of transient receptor potential ankyrin 1 (TRPA1) channels by both environmental irritants and endogenous inflammatory mediators leads to excitation of the nerve endings, resulting in acute sensation of pain, itch, or chronic neurogenic inflammation. As such, TRPA1 channels are actively pursued as therapeutic targets for various pathological nociception and pain disorders. We uncovered that exon 27 of human TRPA1 (hTRPA1) could be alternatively spliced into hTRPA1_27A and hTRPA1_27B splice variants. The resulting channel variants displayed reduced expression, weakened affinity to interact with WT, and suffered from complete loss of function because of disruption of the C-terminal coiled-coil domain. Using a human minigene construct, we revealed that binding of splicing factor serine/arginine-rich splicing factor 1 (SRSF1) to the exonic splicing enhancer was critical for the inclusion of intact exon 27. Knockdown of SRSF1, mutation within exonic splicing enhancer, or masking SRSF1 binding with antisense oligonucleotides promoted alternative splicing within exon 27. Finally, antisense oligonucleotides-induced alternative splicing produced transcript and protein variants that could be functionally determined as diminished endogenous TRPA1 activity in human Schwann cell-line SNF96.2 and hiPSCs-derived sensory neurons. The outcome of the work could potentially offer a novel therapeutic strategy for treating pain by targeting alternative splicing of hTRPA1. |
Pulsed electromagnetic fields synergize with graphene to enhance dental pulp stem cell-derived neurogenesis by selectively targeting TRPC1 channels |
| T T Madanagopal, Y K Tai, S H Lim, C Hh Fong, T Cao, V Rosa, A Franco-Obregón |
| Eur Cell Mater. 2021 Mar 1;41:216-232. doi: 10.22203/eCM.v041a16 |
| Abstract |
| Conventional root canal treatment replaces the infected pulp with defined materials. Alternative cell-based tissue engineering strategies aim to regenerate a fully functional pulp within the root canal. Despite recent advances in this area, however, the regeneration of an innervated pulp remains a major challenge in the field. Both graphene (2DG) and pulsed electromagnetic fields (PEMFs) independently have been shown to promote diverse cellular developmental programs. The present study showed that 2DG promoted the neurogenic induction of human dental pulp stem cells (hDPSCs) by upregulating and accelerating the expression of mature neuronal markers. Notably, 2DG induced the highest expression of transient receptor potential canonical cation channel type 1 (TRPC1) during early neurogenesis. As brief PEMF exposure promotes in vitro differentiation by activating a TRPC1-mitochondrial axis, an opportunity to combine 2DG with developmentally targeted PEMF exposure for synergistic effects was realizable. Neurogenic gene expression, neurotransmitter release, and reactive oxygen species (ROS) production were greatly enhanced by a brief (10 min) and low amplitude (2 mT) PEMF exposure timed to coincide with the highest TRPC1 expression from hDPSCs on 2DG. In contrast, hDPSCs on glass were less responsive to PEMF exposure. The capacity of PEMFs to promote neurogenesis was precluded by the administration of penicillin/streptomycin, mirroring previous studies demonstrating that aminoglycoside antibiotics block TRPC1-mediated calcium entry and verifying the contribution of TRPC1 in this form of magnetoreception. Hence, graphene created a more conducive environment for subsequent PEMF-stimulated neurogenic induction of hDPSCs through their mutual capacity to activate TRPC1with subsequent ROS production. |
Project Coolbit: Can your watch predict heat stress and thermal comfort sensation? |
| Negin Nazarian, Sijie Liu, Manon Kohler, Jason Kai Wei Lee, Clayton Miller, Winston TL Chow, Sharifah Badriyah Badriyah Alhadad, Alberto Martilli, Matias Quintana, Lindsey Sunden and Leslie Norford |
| Environmental Research Letters. |
| Abstract |
| Global climate is changing as a result of anthropogenic warming, leading to higher daily excursions of temperature in cities. Such elevated temperatures have great implications on human thermal comfort and heat stress, which should be closely monitored. Current methods for heat exposure assessments (surveys, microclimate measurements, and laboratory experiments), however, present several limitations: measurements are scattered in time and space and data gathered on outdoor thermal stress and comfort often does not include physiological and behavioral parameters. To address these shortcomings, Project Coolbit aims to introduce a human-centric approach to thermal comfort assessments. In this study, we propose and evaluate the use of wrist-mounted wearable devices to monitor environmental and physiological responses that span a wide range of spatial and temporal distributions. We introduce an integrated wearable weather station that records a) microclimate parameters (such as air temperature and humidity), b) physiological parameters (heart rate, skin temperature and humidity), and c) subjective feedback. The feasibility of this methodology to assess thermal comfort and heat stress is then evaluated using two sets of experiments: controlled-environment physiological data collection, and outdoor environmental data collection. We find that using the data obtained through the wrist-mounted wearables, core temperature can be predicted non-invasively with 95 percent of target attainment (PTA) within 0.27C. Additionally, a direct connection between the air temperature at the wrist (Ta,w) and the perceived activity level (PAV) of individuals was drawn. We observe that with increased Ta,w, the desire for physical activity is significantly reduced, reaching "Transition only" PAV level at 36C. These assessments reveal that the wearable methodology provides a comprehensive and accurate representation of human heat exposure, which can be extended in real-time to cover a large spatial distribution in a given city and quantify the impact of heat exposure on human life. |
Personal assessment of urban heat exposure: a systematic review |
| Negin Nazarian and Jason Kai Wei Lee |
| Environmental Research Letters. |
| Abstract |
| To fully address the multi-faceted challenges of urban heat, it is paramount that humans are placed at the center of the agenda. This is manifested in a recent shift in urban heat studies that aim to achieve a "Human-Centric" approach, i.e. focusing on personalized characteristics of comfort, well-being, performance, and health, as opposed to the one-size-fits-all solutions and guidelines. The proposed article is focused on systematically reviewing personalized urban heat studies and detailing the objectives posed, methodologies utilized, and limitations yet to be addressed. We further summarize current knowledge and challenges in addressing the impact of personal heat exposure on human life by discussing the literature linked with urban heat studies at the human, building, and city scales. Lastly, this systematic review reveals the need for future evaluations focused on accuracy and standardization of human-centric data collection and analytics, and more importantly, addressing critical geographic and socio-economic knowledge gaps identified in the field. |