ORCID Profile
0000-0002-3863-0994
Current Organisation
Nanyang Technological University
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Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2016
Publisher: Elsevier BV
Date: 02-2021
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-09-2019
DOI: 10.1249/MSS.0000000000002150
Abstract: Aging increases the prevalence of glucose intolerance, but exercise improves glucose homeostasis. The fibroblast growth factor 21 (FGF21)–adiponectin axis helps regulate glucose metabolism. However, the role of FGF21 in mediating glucose metabolism with aging and exercise remains unknown. This study examined whether FGF21 responses to a glucose challenge are associated with habitual exercise, aging and glucose regulation. Eighty age- and sex-matched healthy in iduals were assigned to young sedentary and active (≤36 yr, n = 20 each group) and older sedentary and active (≥45 yr, n = 20 each group) groups. Fasted and postprandial blood glucose concentration and plasma concentration of insulin, FGF21, and adiponectin were determined during an oral glucose tolerance test (OGTT). During the OGTT, glucose concentrations were 9% higher ( P = 0.008) and FGF21 concentrations were 58% higher ( P = 0.014) in the older than the younger group, independent of activity status. Active participants had 40% lower insulin concentration and 53% lower FGF21 concentration than sedentary participants, independent of age (all P 0.001). Adiponectin concentration during the OGTT did not differ by age ( P = 0.448) or activity status ( P = 0.611). Within the younger group, postprandial glucose, insulin and FGF21 concentrations during the OGTT were lower in active than in sedentary participants. In the older group, only postprandial insulin and FGF21 concentrations were lower in active participants. FGF21, but not adiponectin, response during the OGTT is higher in older than younger adults and lower in active than sedentary in iduals. Exercise-associated reduction in OGTT glucose concentrations was observed in younger but not older adults.
Publisher: MDPI AG
Date: 02-03-2022
Abstract: Lactate is a metabolite produced during anaerobic glycolysis for ATP resynthesis, which accumulates during hypoxia and muscle contraction. Tobacco smoking significantly increases blood lactate. Here we conducted a counter-balanced crossover study to examine whether this effect is associated with inhaling nicotine or burned carbon particles. Fifteen male smokers (aged 23 to 26 years) were randomized into 3 inhalation conditions: tobacco smoking, nicotine vaping, and nicotine-free vaping, conducted two days apart. An electronic thermal evaporator (e-cigarette) was used for vaping. We have observed an increased blood lactate (+62%, main effect: p 0.01) and a decreased blood glucose (−12%, main effect: p 0.05) during thermal air inhalations regardless of the content delivered. Exercise-induced lactate accumulation and shuttle run performance were similar for the 3 inhalation conditions. Tobacco smoking slightly increased the resting heart rate above the two vaping conditions (p 0.05), implicating the role of burned carbon particles on sympathetic stimulation, independent of nicotine and thermal air. The exercise response in the heart rate was similar for the 3 conditions. The results of the study suggest that acute hypoxia was induced by breathing thermal air. This may explain the reciprocal increases in lactate and decreases in glucose. The impaired lung function in oxygen delivery of tobacco smoking is unrelated to nicotine.
Publisher: Oxford University Press (OUP)
Date: 08-2005
Abstract: This study compared the effectiveness of carbohydrate-electrolyte (CHO-E) fluid replacement versus water (WAT) on hydration status, physiological and subjective responses, and exercise performance during a 3 x 60-minute loaded (14 kg) treadmill walk in 35 degrees C ambient temperature and 55% humidity. CHO-E did not affect urine loss, plasma volume change (WAT = -3.0 +/- 1.6% vs. CHO-E = -1.1 +/- 1.6%), dehydration (WAT = 0.4 +/- 0.3% vs. CHO-E = 0.4 +/- 0.3% of body mass), or core body temperature (Tc) and heart rate (HR) responses. Endurance time was greater but not significantly different with CHO-E (WAT = 134 +/- 9 vs. CHO-E = 146 +/- 9 minutes). CHO-E increased the frequency of task completion (WAT = 21% vs. CHO-E = 50%), elevated blood glucose, and reduced perceived exertion. CHO-E offers potential to enhance exercise capacity by elevating blood glucose and thereby preventing hypoglycemia, maintaining high rates of carbohydrate oxidation, and/or preventing central fatigue but provided no additional benefits with regard to hydration status and physiological function during loaded walking under heat stress.
Publisher: Elsevier BV
Date: 08-2012
Publisher: Springer Science and Business Media LLC
Date: 19-02-2020
DOI: 10.1038/S41598-020-59914-3
Abstract: Lower extremity skeletal muscle mass (LESM) in Type 2 Diabetes (T2D) has been linked to adverse clinical events, but it is not known whether it is associated with cognitive difficulties. We conducted a cross-sectional study on 1,235 people (mean age 61.4 ± 8.0 years) with T2D under primary and secondary care in Singapore. Bioelectrical impedance analyses (BIA) measures of upper extremity skeletal muscle mass (UESM), LESM and appendicular skeletal muscle index (SMI) were related to the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) measures of cognition, in multiple linear regression. In multivariable models, tertile 1 LESM (b = −2.62 (−3.92 to −1.32)) and tertile 2 LESM (b = −1.73 (−2.73 to −0.73)), referenced to tertile 3) were significantly associated with decreased RBANS total score. Significant associations of LESM with cognitive domain performances were observed for tertile 1 (b = −3.75 (−5.98 to −1.52)) and tertile 2 (b = −1.98 (−3.69 to −0.27)) with immediate memory, and for tertile 1 (b = −3.05 (−4.86 to −1.24)) and tertile 2 (b = −1.87 (−3.25 to −0.48)) with delayed memory, and for tertile 1 (b = −2.99 (−5.30 to −0.68)) with visuospatial/constructional ability. Tertile 1 SMI (b = −1.94 (−3.79 to −0.08) and tertile 2 SMI (b = −1.75 (−3.14 to −0.37)) were also associated with delayed memory. There were no associations between UESM with cognitive performance. Lower LESM may be a useful marker of possible co-occuring cognitive dysfunction.
Publisher: Elsevier BV
Date: 12-2020
Publisher: European Respiratory Society
Date: 28-09-2019
Publisher: Wiley
Date: 25-06-2010
DOI: 10.1002/BDD.714
Abstract: The objective was to develop a population pharmacokinetic‐pharmacodynamic model of caffeine's psychomotor effects in healthy, non‐habitual users of caffeine. Twenty Chinese males each received a single dose of 250 mg of caffeine orally. Plasma concentrations of caffeine were determined at various times within 24 h after dosing. The subjects' psychomotor performance was evaluated before and at various times after dosing by a test battery consisting of oculomotor assessment (saccadic velocity) as well as the computerised Swedish Performance Evaluation System. Nonlinear mixed‐effects modelling to analyse the pharmacokinetic‐pharmacodynamic relationships was performed using NONMEM. Model robustness was assessed by a nonparametric bootstrap. The results showed that caffeine caused significant improvements in psychomotor functioning. The time course of these effects was best described by pharmacokinetic harmacodynamic models involving an effect compartment. The transfer half‐lives between plasma and effect site for different domains of psychomotor functioning were in the range 24.8–49.5 min. Evaluation of the final models showed close agreement between pairs of bootstrapped and final model parameter estimates (all differences %). These results provided the first suggestive evidence that caffeine effects on psychomotor performance occur after some time delay relative to changes in plasma caffeine concentration. The models for the neurobehavioural tests provided similar transfer half‐lives between plasma and effect site. Copyright © 2010 John Wiley & Sons, Ltd.
Publisher: Springer Science and Business Media LLC
Date: 16-11-2015
Publisher: SERDI
Date: 2022
DOI: 10.14283/JFA.2022.6
Abstract: Sarcopenia is an emerging disease that adversely impacts outcomes of older adults across the spectrum of fragility fractures. Few studies have examined sarcopenia in upstream fragility fractures such as the distal radius. Understanding the state of current evidence is essential in defining a research agenda in this critical area of sentinel distal radius fractures and sarcopenia. The aim of this scoping review was to summarize existing literature on sarcopenia in distal radius fracture in older adults, and to identify research areas and gaps to guide future studies. We utilized the 5-stage framework of Arksey and O'Malley. We searched studies from 2010 to 2020 relating to «Sarcopenia» and «Distal radius fractures» in major databases. Two reviewers independently screened articles for inclusion and conducted full text reviews of shortlisted articles. We extracted data on research areas, key findings, and study limitations. Thirteen studies met the inclusion and exclusion criteria. They covered the areas of epidemiology (N=9), risk factors (N=4), basic science (N=2), outcomes (N=1), and diagnostic modalities (N=1). There were no studies on screening/case finding, prognostic scoring, intervention, or health economics. Identified limitations included the lack of clear definition and diagnostic criteria for sarcopenia, and lack of, or inappropriate, control group. Majority of studies were retrospective or cross-sectional in study design. This scoping review on sarcopenia in distal radius fractures highlighted gaps in research areas and in the rigor of studies conducted, and the need for more prospective cohort and interventional studies. Building upon current consensus criteria, we propose setting a research agenda along the timeline of sarcopenia management, from screening through to intervention and follow-up, which will inform future research in this early disease cohort of fragility fractures.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2004
Publisher: Springer Science and Business Media LLC
Date: 23-10-2014
DOI: 10.1007/S00421-013-2748-Y
Abstract: This study aimed to investigate the effects of multi-strain probiotics supplementation on gastrointestinal permeability, systemic markers of inflammation and running performance when exercising in the heat. Ten male runners were randomized to 4 weeks of daily supplementation with a probiotics capsule (45 billion CFU of Lactobacillus, Bifidobacterium and Streptococcus strains) or placebo, separated by a washout period (double-blind, cross-over trial). After each treatment, the runners exercised to fatigue at 80% of their ventilatory threshold at 35 °C and 40% humidity. To assess gastrointestinal permeability, runners ingested lactulose and rhamnose before exercise and post-exercise urine was collected to measure sugar concentrations. Venous blood s les were collected before, immediately after and 1 h after exercise, and core temperature was monitored during exercise. Probiotics supplementation significantly increased run time to fatigue (min:s 37:44 ± 2:42 versus 33:00 ± 2:27 P = 0.03, d = 0.54). Average core temperature during exercise was similar between trials (probiotic 38.1 ± 0.2 °C, placebo 38.1 ± 0.1 °C P = 0.77, d = 0.13). Serum lipopolysaccharide concentration increased post-exercise (P < 0.001), while there was a moderate to large reduction in pre-exercise (d = 0.70) and post-exercise (d = 1.24) concentration following probiotics supplementation. Plasma concentrations of IL-6, IL-10 and IL-1ra increased after exercise (P 0.05). There was a small to moderate reduction (d = 0.35) in urine lactulose:rhamnose and a small reduction (d = 0.25) in symptoms of gastrointestinal discomfort following probiotics supplementation (both P = 0.25). Four weeks of supplementation with a multi-strain probiotic increased running time to fatigue in the heat. Further studies are required to elucidate the exact mechanisms for this performance benefit.
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.APPET.2012.03.017
Abstract: Body fat fluctuation during varying competing academic demand was examined among female adolescents with high (n=24) or low (n=24) restrained eating behaviours. Body fat, perceived stress, energy intake, and exercise behaviour were measured three times with 10 weeks between consecutive sessions. High restrained eaters' body fat increased during a period when academic demands were high. Significant results were found for exercise behaviours but not for food consumption. Post hoc analyses did not reveal significant results for low restrained eaters. The results lend support to Muraven and Baumeister's limited strength model of self-regulation.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2009
Publisher: Springer Science and Business Media LLC
Date: 24-08-2022
DOI: 10.1186/S12910-022-00824-6
Abstract: Research and academic institutions use various delivery channels to deliver Research Integrity (RI) education in their communities. Yet there is no consensus on the best delivery method and the effectiveness of these channels in inculcating a positive RI culture varies across institutions. Hence, this study aimed to understand the preferences of the research community in Nanyang Technological University (NTU), Singapore. An online survey was conducted on NTU research community to understand their experience with, and preference for each RI education mode offered in NTU. The RI education modes surveyed in the general ranking question are Data Management Plan (DMP) workshops, Epigeum e-Learning, Compass e-newsletter (email), and NTU policy on Research Integrity and Responsible Conduct of Research. There were 242 responses, comprising 50% research students, 32.2% research staff and 17.8% faculty members. Non-parametric statistical techniques were used to analyse preferences across different RI education modes and within sub-groups (i.e., fields, age, native language, roles in research community). More than 92% of respondents subscribed to the importance of RI education, but with different preferences for education modes. With respect to RI education in NTU, Compass e-newsletters were ranked the lowest ( p 0.05). Most felt that they were too wordy and unengaging, making it difficult to absorb information. Similarly, Epigeum e-Learning ( p 0.05) and ‘policy’ ( p 0.05) were found to be too lengthy in presentation. The compulsory NTU RI education modes (Epigeum e-learning and ‘policy’) enjoyed higher participation rates of 70–80% compared with 32–37% for the self-regulated modes (DMP workshop and e-newsletter). This suggests that regulatory mechanisms are still necessary to promote participation in RI education, and thus, core RI education content should be made compulsory in research/academic institutions. Although Epigeum is a compulsory course, some may not have participated in the programme due to technical issues or they might have forgotten to participate in the programme within the permissible timeframe. For all four RI education modes in NTU, the lack of awareness was among the top cited reasons for not participating. Most NTU researchers perceived RI education positively although they may have reservations for some approaches. Conversely, e-Learning is favored over all the other modes except for the mode of Policy. Findings from this study are useful for improving the design of RI education strategies to be more appealing to the research community by enhancing user experience in terms of user-friendliness, relevance to specialisation, providing concise information and better presentation of materials For institutions with similar modes of RI education as NTU, these results may be relevant in improving participation rates and presentation of RI education modes, such as the use of infographics and more concise information.
Publisher: Canadian Science Publishing
Date: 08-2009
DOI: 10.1139/H09-021
Abstract: The effects of increased training (IT) load on plasma concentrations of lipopolysaccharides (LPS), proinflammatory cytokines, and anti-LPS antibodies during exercise in the heat were investigated in 18 male runners, who performed 14 days of normal training (NT) or 14 days of 20% IT load in 2 equal groups. Before (trial 1) and after (trial 2) the training intervention, all subjects ran at 70% maximum oxygen uptake on a treadmill under hot (35 °C) and humid (∼40%) conditions, until core temperature reached 39.5 °C or volitional exhaustion. Venous blood s les were drawn before, after, and 1.5 h after exercise. Plasma LPS concentration after exercise increased by 71% (trial 1, p 0.05) and 21% (trial 2) in the NT group and by 92% (trial 1, p 0.01) and 199% (trial 2, p 0.01) in the IT group. Postintervention plasma LPS concentration was 35% lower before exercise (p 0.05) and 47% lower during recovery (p 0.01) in the IT than in the NT group. Anti-LPS IgM concentration during recovery was 35% lower in the IT than in the NT group (p 0.05). Plasma interleukin (IL)-6 and tumor necrosis factor (TNF)-α concentrations after exercise (IL-6, 3−7 times, p 0.01, and TNF-α, 33%, p 0.01) and during recovery (IL-6, 2−4 times, p 0.05, and TNF-α, 30%, p 0.01) were higher than at rest within each group. These data suggest that a short-term tolerable increase in training load may protect against developing endotoxemia during exercise in the heat.
Publisher: Springer Science and Business Media LLC
Date: 25-01-2021
Publisher: Elsevier BV
Date: 07-2021
DOI: 10.1016/J.JDIACOMP.2021.107930
Abstract: We studied the association between extracellular volume status and chronic kidney disease (CKD) progression and the role of extracellular volume excess as a potential mediator in the relationship between matrix metalloproteinases (MMP)-2 and CKD progression in Type 2 diabetes mellitus (T2DM). We conducted a prospective cohort study of 1079 T2DM patients. Bioelectrical impedance analysis (BIA) was performed to assess body fluid status. After up to 8.6 years of follow-up, 471 (43.7%) patients experienced CKD progression. In the fully adjusted model, extracellular water (ECW)/ total body water (TBW)ratios 0.39-0.40 and > 0.40 were associated with 45% and 78% higher risk of CKD progression respectively. Patients with an increase in ECW/TBW ratio had 40% higher risk of CKD progression compared to those with no change or reduction of ECW/TBW ratio. Higher ECW/TBW ratio accounted for 17.4% of the relationship between MMP-2 and CKD progression in T2DM (p = 0.026). Extracellular volume excess was independently associated with CKD progression in T2DM. Higher ECW/TBW ratio mediated the positive association between MMP-2 and CKD progression. Further studies are needed to elucidate the role of extracellular volume excess in deterioration of renal function.
Publisher: Frontiers Media SA
Date: 12-2022
Publisher: Frontiers Media SA
Date: 10-07-2023
DOI: 10.3389/FPHYS.2023.1227502
Abstract: The effects of different muscle loading exercise (MLEX) modes and volume on musculoskeletal health is not well-studied in older populations. Aim: Therefore, this study aimed to compare the effects of community-based MLEX modalities and volume on musculoskeletal health in elderly people. Methods: Elderly men (n = 86) and women (n = 170), age 50–82 years old, were assigned to the sedentary (SE, n = 60), muscle strengthening exercise (MSE, n = 71), aerobic exercise (AE, n = 62) and Tai Chi exercise (TCE, n = 63) groups, based on & 2 years of exercise history. Exercise volume was compared between “Minimum” (“Min” & 60 min/week), “Low” (60–120 min/week). “Moderate” (121–239 min/week) and “High” (240–720 min/week) volumes. Results: All three modes of MLEX were associated with lower percentage of body fat (BF%) and higher percentage of lean body mass (LBM%, p = 0.003 main effect of group, and p = 0.002 main effect of volume for both BF% and LBM%), but not with higher bone mineral density (BMD, total body, lumbar spine, total hip and neck of femur), than SE. TCE had a distinct advantage in trunk flexibility ( p = 0.007 with MSE, p = 0.02 with AE, and p = 0.01 with SE), and both TCE ( p = 0.03) and AE ( p = 0.03) performed better than SE in the one-leg stand balance test. Isometric strength and throwing speed and peak power with a 2 kg power ball were higher in the MLEX than SE groups ( p = 0.01), in the ranking order of MSE, AE and TCE. However, there was no difference in handgrip strength performance between the MLEX groups, which performed better than the SE participants. Accumulating & min/week of MLEX can promote body composition health and muscle functions, but 60 min/week of MSE alone may have equal or better outcomes in these parameters. Conclusion: Community-based MLEX classes may be used to mitigate age-related chronic disease that are associated with body composition and muscular functions.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2000
Publisher: Public Library of Science (PLoS)
Date: 05-2014
Publisher: Springer Science and Business Media LLC
Date: 12-01-2013
DOI: 10.1007/S00421-013-2587-X
Abstract: This study investigated plasma lipopolysaccharides (LPS) concentration and intestinal permeability after 60-min run at 70 % maximum oxygen uptake (VO2max) in hot [33 °C, 50 % relative humidity (rH)] and cool (22 °C, 62 % rH) conditions. Fifteen volunteers gave their informed consent to participate in this study. Their venous blood s les were taken before, after, 2 and 5 h after exercise in each of the conditions. The order of the two environmental conditions in which they exercised in was randomised and counterbalanced. Plasma LPS concentration increased by an average of 54.0 % (95 % confidence interval: 30.7, 75.1 %) after exercising in the hot trial but no significant changes were observed in cool trial, where mean plasma LPS concentration was 12.0 ± 6.4 pg mL(-1) (before), 10.9 ± 5.4 pg mL(-1) (after), 10.7 ± 6.0 pg mL(-1) (2 h after) and 10.6 ± 5.7 pg mL(-1) (5 h after). Median (range) plasma claudin-3 (CLDN3) concentration was significantly higher after exercise (hot: 8.2 [1.0-13.0] ng mL(-1) and cool: 7.6 [0.6-13.4] ng mL(-1)) as compared to before exercise (hot: 6.6 [0.7-11.8] ng mL(-1) and cool: 6.7 [0.8-12.6] ng mL(-1)) (p 0.05). Changes in intestinal permeability are only affected by exercise while exercise-induced endotoxemia is affected by environmental conditions. This study, thus, highlights that an increase in intestinal permeability is not sufficient to trigger exercise-induced endotoxemia, suggesting that post-LPS translocation events may have a greater impact in its occurrence.
Publisher: Oxford University Press (OUP)
Date: 09-1997
Publisher: Springer Science and Business Media LLC
Date: 2006
DOI: 10.2165/00007256-200636010-00004
Abstract: Heat stroke is a life-threatening condition that can be fatal if not appropriately managed. Although heat stroke has been recognised as a medical condition for centuries, a universally accepted definition of heat stroke is lacking and the pathology of heat stroke is not fully understood. Information derived from autopsy reports and the clinical presentation of patients with heat stroke indicates that hyperthermia, septicaemia, central nervous system impairment and cardiovascular failure play important roles in the pathology of heat stroke. The current models of heat stroke advocate that heat stroke is triggered by hyperthermia but is driven by endotoxaemia. Endotoxaemia triggers the systemic inflammatory response, which can lead to systemic coagulation and haemorrhage, necrosis, cell death and multi-organ failure. However, the current heat stroke models cannot fully explain the discrepancies in high core temperature (Tc) as a trigger of heat stroke within and between in iduals. Research on the concept of critical Tc as a limitation to endurance exercise implies that a high Tc may function as a signal to trigger the protective mechanisms against heat stroke. Athletes undergoing a period of intense training are subjected to a variety of immune and gastrointestinal (GI) disturbances. The immune disturbances include the suppression of immune cells and their functions, suppression of cell-mediated immunity, translocation of lipopolysaccharide (LPS), suppression of anti-LPS antibodies, increased macrophage activity due to muscle tissue damage, and increased concentration of circulating inflammatory and pyrogenic cytokines. Common symptoms of exercise-induced GI disturbances include diarrhoea, vomiting, gastrointestinal bleeding, and cr s, which may increase gut-related LPS translocation. This article discusses the current evidence that supports the argument that these exercise-induced immune and GI disturbances may contribute to the development of endotoxaemia and heat stroke. When endotoxaemia can be tolerated or prevented, continuing exercise and heat exposure will elevate Tc to a higher level (>42 degrees C), where heat stroke may occur through the direct thermal effects of heat on organ tissues and cells. We also discuss the evidence suggesting that heat stroke may occur through endotoxaemia (heat sepsis), the primary pathway of heat stroke, or hyperthermia, the secondary pathway of heat stroke. The existence of these two pathways of heat stroke and the contribution of exercise-induced immune and GI disturbances in the primary pathway of heat stroke are illustrated in the dual pathway model of heat stroke. This model of heat stroke suggests that prolonged intense exercise suppresses anti-LPS mechanisms, and promotes inflammatory and pyrogenic activities in the pathway of heat stroke.
Publisher: Oxford University Press (OUP)
Date: 04-1999
Publisher: Informa UK Limited
Date: 03-2011
Publisher: American Physiological Society
Date: 2007
DOI: 10.1152/AJPREGU.00921.2005
Abstract: This study investigated the roles of endotoxemia and heat-induced tissue damage in the pathology of heat stroke. In groups of eight, male Wistar rats were treated with heat exposure only (HE), or heat exposure with turpentine (T+HE), dexamethasone (D+HE), and turpentine and dexamethasone combined (TD+HE). The rats remained sedated for 2 h after receiving the respective treatments, followed by heat exposure until the core temperature (T c ) was 42°C for 15 min control rats received turpentine (T), dexamethasone (D), and turpentine and dexamethasone (TD) without heat stress. Blood s les were collected before treatment ( baseline I), after 2 h of passive rest ( baseline II), at T c 40°C (T40), and 15 min after achieving T c 42°C (T42). No rats died in the nonheat-stressed groups. Survival rate was lowest in the TD+HE rats (37.5%), followed by the HE (62.5%), T+HE (75%), and D+HE (100%) rats ( P 0.05). The duration of survival at T42°C was shortest in the TD+HE rats (9.9 ± 6.2 min) ( P 0.01), followed by the T+HE (11.3 ± 6.1 min) and the HE (12.2 ± 4 min) ( P 0.05) rats. The increase in plasma IL-6 concentrations was highest in the T+HE (352%) and HE (178%) rats ( P 0.05). D+HE treatment suppressed the increases in plasma aspartate transaminase, alanine aminotransferase, and IL-6 and LPS concentrations during severe heat stress. Heat stroke can be triggered by endotoxemia or heat-induced tissue damage, and preexisting inflammation compromises heat tolerance, whereas blocking endotoxemia increases heat tolerance.
Publisher: IMR Press
Date: 2006
DOI: 10.2741/2021
Abstract: Heat induced complications cause an increase in a large number of proteins which play a role in erse pathways during heat shock. A detailed characterization of these proteins is essential for understanding the molecular mechanisms involved in heat stroke. In this report, the proteins present in rat liver were compared at 37 degrees C (control) and at core temperature (Tc) 42 degrees C (heat stress) by 1D PAGE and MALDI/MS/MS. Among proteins identified in the s le after heat stress are dimethyglycine dehydrogenase, transketolase, carboxylic ester hydrolase, pyruvate kinase, L-type pyruvate kinase, arginosuccinate synthetase fumarylacetoacetate hydrolase and peptidylpropyl isomerase A. These findings show that analysis of large scale proteins by MALDI/MS/MS provides a better understanding of the molecular mechanisms associated with heat shock. The resolution of proteins examined by 1D-PAGE was less than that obtained with 2D-PAGE. More specifically, 2D-PAGE allows better identification of low molecular weight proteins that can not be resolved by 1D-PAGE.
Publisher: Oxford University Press (OUP)
Date: 02-2000
Publisher: Georg Thieme Verlag KG
Date: 26-01-2011
Abstract: There are no reported cases of exercise-associated hyponatremia (EAH) in tropical Asia. This study aimed to investigate the incidence of EAH at the on-site medical tent and fluid balance in long distance foot races in a warm and humid environment. Body mass was taken before and after the races (42-km marathon 84-km ultra-marathon). Blood sodium concentration was measured for symptomatic runners admitted to the medical tent. Mean (SD) dry bulb temperature was 29.0 (0.6)°C, relative humidity 89 (2)% and wind speed 0.3 (0.5) m/s. Three out of the 8 symptomatic runners admitted to the medical tent were diagnosed with hyponatremia, with blood sodium concentrations of 134 mmol/L in a 42-km runner, and 131 and 117 mmol/L in two 84-km runners. In the 42-km race, mean % ΔBM was -1.6 (1.2)%, ranging from -5.7 to 1.4%, and 22 runners (7%) gained weight. In the 84-km race, mean % ΔBM was -2.3 (1.7)%, ranging from -8.0 to 1.4%, and 9 runners (8%) gained weight. In addition to the 3 cases of symptomatic hyponatremia observed, 8% of the 84-km runners and 7% of the 42-km runners gained weight during the race. This indicates the need to disseminate advice for the prevention and treatment of EAH for races held in the tropics.
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.PSYCHRES.2016.09.032
Abstract: Sleep disorder is a risk factor for several systemic inflammation-related diseases and there are extensive data showing that schizophrenia is associated with chronic low-grade systemic inflammation. This study investigated the associations between sleep quality and inflammatory markers in patients with schizophrenia, which has not been examined before. Sleep quality (total sleep time, sleep efficiency, sleep onset latency, total activity counts, wake after sleep onset, number of awakening, and average length of awakening) was measured using actigraphy in 199 schizophrenia inpatients. The state of inflammation was measured using blood concentration of white blood cells (WBC) and neutrophils, together with neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR). The results showed that total sleep time was negatively associated with NLR and PLR, and sleep efficiency was negatively associated with neutrophil counts and NLR. Sleep onset latency, total activity counts, wake after sleep onset, and number of awakening were positively associated with WBC and neutrophil counts. The average length of awakening was positively associated with NLR and PLR. This is the first report to suggest that improving sleep quality may modulate the state of inflammation in patients with schizophrenia.
Publisher: MDPI AG
Date: 24-10-2020
Abstract: The international community has recognized global warming as an impending catastrophe that poses significant threat to life on earth. In response, the signatories of the Paris Agreement (2015) have committed to limit the increase in global mean temperature to .5 °C from pre-industry period, which is defined as 1850–1890. Considering that the protection of human life is a central focus in the Paris Agreement, the naturally endowed properties of the human body to protect itself from environmental extremes should form the core of an integrated and multifaceted solution against global warming. Scholars believe that heat and thermoregulation played important roles in the evolution of life and continue to be a central mechanism that allows humans to explore, labor and live in extreme conditions. However, the international effort against global warming has focused primarily on protecting the environment and on the reduction of greenhouse gases by changing human behavior, industrial practices and government policies, with limited consideration given to the nature and design of the human thermoregulatory system. Global warming is projected to challenge the limits of human thermoregulation, which can be enhanced by complementing innate human thermo-plasticity with the appropriate behavioral changes and technological innovations. Therefore, the primary aim of this review is to discuss the fundamental concepts and physiology of human thermoregulation as the underlying bases for human adaptation to global warming. Potential strategies to extend human tolerance against environmental heat through behavioral adaptations and technological innovations will also be discussed. An important behavioral adaptation postulated by this review is that sleep/wake cycles would gravitate towards a sub-nocturnal pattern, especially for outdoor activities, to avoid the heat in the day. Technologically, the current concept of air conditioning the space in the room would likely steer towards the concept of targeted body surface cooling. The current review was conducted using materials that were derived from PubMed search engine and the personal library of the author. The PubMed search was conducted using combinations of keywords that are related to the theme and topics in the respective sections of the review. The final set of articles selected were considered “state of the art,” based on their contributions to the strength of scientific evidence and novelty in the domain knowledge on human thermoregulation and global warming.
Publisher: American Physiological Society
Date: 2011
Publisher: Springer Science and Business Media LLC
Date: 04-07-2016
Publisher: Springer Science and Business Media LLC
Date: 2009
Publisher: Public Library of Science (PLoS)
Date: 26-11-2019
Publisher: Oxford University Press (OUP)
Date: 05-2001
Publisher: Hindawi Limited
Date: 02-2009
DOI: 10.1111/J.1365-2710.2008.00976.X
Abstract: Caffeine has been shown to maintain or improve the performance of in iduals, but its pharmacokinetic profile for Asians has not been well characterized. In this study, a population pharmacokinetic model for describing the pharmacokinetics of caffeine in Singapore males was developed. The data were also analysed using non-compartmental models. Data gathered from 59 male volunteers, who each ingested a single caffeine capsule in two clinical trials (3 or 5 mg/kg), were analysed via non-linear mixed-effects modelling. The participants' covariates, including age, body weight, and regularity of caffeinated-beverage consumption or smoking, were analysed in a stepwise fashion to identify their potential influence on caffeine pharmacokinetics. The final pharmacostatistical model was then subjected to stochastic simulation to predict the plasma concentrations of caffeine after oral (204, 340 and 476 mg) dosing regimens (repeated dosing every 6, 8 or 12 h) over a hypothetical 3-day period. The data were best described by a one-compartmental model with first-order absorption and first-order elimination. Smoking status was an influential covariate for clearance: clearance (mL/min) = 110*SMOKE + 114, where SMOKE was 0 and 1 for the non-smoker and the smoker respectively. Interoccasion variability was smaller compared to interin idual variability in clearance, volume and absorption rate (27% vs. 33%, 10% vs. 15% and 23% vs. 51% respectively). The extrapolated elimination half-lives of caffeine in the non-smokers and the smokers were 4.3 +/- 1.5 and 3.0 +/- 0.7 h respectively. Dosing simulations indicated that dosing regimens of 340 mg (repeated every 8 h) and 476 mg (repeated every 6 h) should achieve population-averaged caffeine concentrations within the reported beneficial range (4.5-9 microg/mL) in the non-smokers and the smokers respectively over 72 h. The population pharmacokinetic model satisfactorily described the disposition and variability of caffeine in the data. Mixed-effects modelling showed that the dose of caffeine depended on cigarette smoking status.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2006
Publisher: Wiley
Date: 17-02-2020
DOI: 10.1113/EP088351
Publisher: Springer Science and Business Media LLC
Date: 17-03-2010
DOI: 10.1007/S00421-010-1405-Y
Abstract: Deep body temperature (T(c)), pacing strategy and fluid balance were investigated during a 21-km road race in a warm and humid environment. Thirty-one males (age 25.3 +/- 3.2 years maximal oxygen uptake 59.1 +/- 4.2 ml kg(-1) min(-1)) volunteered for this study. Continuous T(c) responses were obtained in 25 runners. Research stations at approximately 3-km intervals permitted accurate assessment of split times and fluid intake. Environmental conditions averaged 26.4 degrees C dry bulb temperature and 81% relative humidity. Peak T(c) was 39.8 +/- 0.5 (38.5-40.7) degrees C with 24 runners achieving T(c) > 39.0 degrees C, 17 runners > or = 39.5 degrees C, and 10 runners > or = 40.0 degrees C. In 12 runners attaining peak T(c) > or = 39.8 degrees C, running speed did not differ significantly when T(c) was below or above this threshold (208 +/- 15 cf. 205 +/- 24 m min(-1) P = 0.532). Running velocity was the main significant predictor variable of T(c) at 21 km (R(2) = 0.42, P or = 39.8 degrees C) and normothermic runners (T(c) < 39.8 degrees C) up to 11.8 km. A reverse J-shaped pacing profile characterised by a marked reduction in running speed after 6.9 km and evidence of an end-spurt in 16 runners was observed. Variables relating to fluid balance were not associated with any T(c) parameters or pacing. We conclude that hyperthermia, defined by a deep body temperature greater than 39.5 degrees C, is common in trained in iduals undertaking outdoor distance running in environmental heat, without evidence of fatigue or heat illness.
Publisher: MDPI AG
Date: 07-03-2020
Abstract: Fibroblast growth factor 21 (FGF21) and adiponectin increase the expression of genes involved in antioxidant pathways, but their roles in mediating oxidative stress and arterial stiffness with ageing and habitual exercise remain unknown. We explored the role of the FGF21–adiponectin axis in mediating oxidative stress and arterial stiffness with ageing and habitual exercise. Eighty age- and sex-matched healthy in iduals were assigned to younger sedentary or active (18–36 years old, n = 20 each) and older sedentary or active (45–80 years old, n = 20 each) groups. Arterial stiffness was measured indirectly using pulse wave velocity (PWV). Fasted plasma concentrations of FGF21, adiponectin and oxidized low-density lipoprotein (oxLDL) were measured. PWV was 0.2-fold higher and oxLDL concentration was 25.6% higher (both p 0.001) in older than younger adults, despite no difference in FGF21 concentration (p = 0.097) between age groups. PWV (p = 0.09) and oxLDL concentration (p = 0.275) did not differ between activity groups but FGF21 concentration was 9% lower in active than sedentary in iduals (p = 0.011). Adiponectin concentration did not differ by age (p = 0.642) or exercise habits (p = 0.821). In conclusion, age, but not habitual exercise, was associated with higher oxidative stress and arterial stiffness. FGF21 and adiponectin did not differ between younger and older adults, meaning that it is unlikely that they mediate oxidative stress and arterial stiffness in healthy adults.
Publisher: Wiley
Date: 07-09-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2010
Publisher: BMJ
Date: 03-2007
Publisher: Oxford University Press (OUP)
Date: 11-1998
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2019
Publisher: MDPI AG
Date: 25-10-2018
Abstract: Heat stroke (HS) is an ancient illness dating back more than 2000 years and continues to be a health threat and to cause fatality during physical exertion, especially in military personnel, fire-fighters, athletes, and outdoor laborers. The current paradigm in the pathophysiology and prevention of HS focuses predominantly on heat as the primary trigger and driver of HS, which has not changed significantly for centuries. However, pathological and clinical reports from HS victims and research evidence from animal and human studies support the notion that heat alone does not fully explain the pathophysiology of HS and that HS may also be triggered and driven by heat- and exercise-induced endotoxemia. Exposure to heat and exercise stresses independently promote the translocation of lipopolysaccharides (LPS) from gram-negative bacteria in the gut to blood in the circulatory system. Blood concentration of LPS can increase to a threshold that triggers the systemic inflammatory response, leading to the downstream ramifications of cellular and organ damage with sepsis as the end point i.e., heat sepsis. The dual pathway model (DPM) of HS proposed that HS is triggered by two independent pathways sequentially along the core temperature continuum of °C. HS is triggered by heat sepsis at Tc 42 °C and by the heat toxicity at Tc 42 °C, where the direct effects of heat alone can cause cellular and organ damage. Therefore, heat sepsis precedes heat toxicity in the pathophysiology of HS.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2006
Publisher: Elsevier BV
Date: 04-2021
Publisher: Elsevier BV
Date: 05-2007
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Chin Leong Lim.