Pub Date : 2016-03-16DOI: 10.1080/23328940.2016.1156215
K. N. Thomas, A. V. Van rij, S. Lucas, A. R. Gray, J. Cotter
ABSTRACT Exercise induces arterial flow patterns that promote functional and structural adaptations, improving functional capacity and reducing cardiovascular risk. While heat is produced by exercise, local and whole-body passive heating have recently been shown to generate favorable flow profiles and associated vascular adaptations in the upper limb. Flow responses to acute heating in the lower limbs have not yet been assessed, or directly compared to exercise, and other cardiovascular effects of lower-limb heating have not been fully characterized. Lower-limb heating by hot-water immersion (30 min at 42°C, to the waist) was compared to matched-duration treadmill running (65-75% age-predicted heart rate maximum) in 10 healthy, young adult volunteers. Superficial femoral artery shear rate assessed immediately upon completion was increased to a greater extent following immersion (mean ± SD: immersion +252 ± 137% vs. exercise +155 ± 69%, interaction: p = 0.032), while superficial femoral artery flow-mediated dilation was unchanged in either intervention. Immersion increased heart rate to a lower peak than during exercise (immersion +38 ± 3 beats·min-1 vs. exercise +87 ± 3 beats·min-1, interaction: p < 0.001), whereas only immersion reduced mean arterial pressure after exposure (−8 ± 3 mmHg, p = 0.012). Core temperature increased twice as much during immersion as exercise (+1.3 ± 0.4°C vs. +0.6 ± 0.4°C, p < 0.001). These data indicate that acute lower-limb hot-water immersion has potential to induce favorable shear stress patterns and cardiovascular responses within vessels prone to atherosclerosis. Whether repetition of lower-limb heating has long-term beneficial effects in such vasculature remains unexplored.
运动诱导动脉血流模式，促进功能和结构适应，提高功能能力，降低心血管风险。虽然热量是通过运动产生的，但最近的研究表明，局部和全身被动加热可以在上肢产生有利的血流分布和相关的血管适应性。下肢急性加热的血流反应尚未被评估，或与运动直接比较，下肢加热对心血管的其他影响尚未完全表征。将10名健康的年轻成年志愿者的下肢热水浸泡加热(42°C 30分钟，腰部)与匹配持续时间的跑步机跑步(65-75%的年龄预测心率最大值)进行比较。完成后立即评估的股浅动脉剪切率在浸泡后增加到更大程度(平均±SD:浸泡+252±137% vs运动+155±69%，相互作用:p = 0.032)，而股浅动脉血流介导的扩张在两种干预中都没有变化。浸泡将心率提高到比运动时更低的峰值(浸泡+38±3次·min-1 vs运动+87±3次·min-1，相互作用:p < 0.001)，而只有浸泡降低了暴露后的平均动脉压(- 8±3 mmHg, p = 0.012)。浸泡时的核心温度升高是运动时的两倍(+1.3±0.4°C vs +0.6±0.4°C, p < 0.001)。这些数据表明，急性下肢热水浸泡有可能在容易发生动脉粥样硬化的血管中诱导有利的剪切应力模式和心血管反应。下肢反复加热是否对此类脉管系统有长期的有益影响尚不清楚。
{"title":"Substantive hemodynamic and thermal strain upon completing lower-limb hot-water immersion; comparisons with treadmill running","authors":"K. N. Thomas, A. V. Van rij, S. Lucas, A. R. Gray, J. Cotter","doi":"10.1080/23328940.2016.1156215","DOIUrl":"https://doi.org/10.1080/23328940.2016.1156215","url":null,"abstract":"ABSTRACT Exercise induces arterial flow patterns that promote functional and structural adaptations, improving functional capacity and reducing cardiovascular risk. While heat is produced by exercise, local and whole-body passive heating have recently been shown to generate favorable flow profiles and associated vascular adaptations in the upper limb. Flow responses to acute heating in the lower limbs have not yet been assessed, or directly compared to exercise, and other cardiovascular effects of lower-limb heating have not been fully characterized. Lower-limb heating by hot-water immersion (30 min at 42°C, to the waist) was compared to matched-duration treadmill running (65-75% age-predicted heart rate maximum) in 10 healthy, young adult volunteers. Superficial femoral artery shear rate assessed immediately upon completion was increased to a greater extent following immersion (mean ± SD: immersion +252 ± 137% vs. exercise +155 ± 69%, interaction: p = 0.032), while superficial femoral artery flow-mediated dilation was unchanged in either intervention. Immersion increased heart rate to a lower peak than during exercise (immersion +38 ± 3 beats·min-1 vs. exercise +87 ± 3 beats·min-1, interaction: p < 0.001), whereas only immersion reduced mean arterial pressure after exposure (−8 ± 3 mmHg, p = 0.012). Core temperature increased twice as much during immersion as exercise (+1.3 ± 0.4°C vs. +0.6 ± 0.4°C, p < 0.001). These data indicate that acute lower-limb hot-water immersion has potential to induce favorable shear stress patterns and cardiovascular responses within vessels prone to atherosclerosis. Whether repetition of lower-limb heating has long-term beneficial effects in such vasculature remains unexplored.","PeriodicalId":22565,"journal":{"name":"Temperature: Multidisciplinary Biomedical Journal","volume":"76 1","pages":"286 - 297"},"PeriodicalIF":0.0,"publicationDate":"2016-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86471823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-03-03DOI: 10.1080/23328940.2016.1159772
M. R. Che Jusoh, S. Stannard, T. Mündel
ABSTRACT The present study determined whether 0.8g/kg bodyweight sago ingested before (Pre-Sago) or during (Dur-Sago) exercise under warm-humid conditions (30 ± 2°C, 78 ± 3 % RH; 20 km·h−1 frontal airflow) conferred a performance and/or physiological benefit compared to a control (Control) condition. Eight trained, male cyclists/triathletes (45 ± 4 y, VO2peak: 65 ± 10 ml·kg−1·min−1, peak aerobic power: 397 ± 71 W) completed 3 15-min time-trials (∼75% VO2peak) pre-loaded with 45 min of steady-state (∼55% VO2peak) cycling following > 24 h standardization of training and diet. Measures of work completed, rectal and mean skin temperatures, heart rate, expiratory gases and venous blood samples were taken. Compared to Control, Pre-Sago resulted in a smaller rise in rectal temperature (0.3 ± 0.5°C) while heart rate increased to a greater extent (6 ± 13 beats·min−1) during exercise (both P < 0.05), however, compared to Control time-trial performance remained unaffected (Pre-Sago: −0.5 ± 4.0%, P > 0.05). During exercise, plasma glucose concentrations were maintained higher for Dur-Sago than Control (P < 0.05), however substrate oxidation rates remained similar (P > 0.05). Dur-Sago also resulted in a higher plasma sodium concentration (2 ± 2 mmol·l1) and lower whole-body sweat loss (544 ± 636 g) and, therefore, reduced plasma volume contraction (all P < 0.05). Heart rate increased to a greater extent (5 ± 13 beats·min−1) during Dur-Sago, yet compared to Control time-trial performance remained unaffected (+0.9 ± 2.3%, P > 0.05). Uniquely, these results indicate that during exercise heat stress feeding sago can result in some ‘beneficial’ physiological responses, however these do not translate to changes in exercise performance when performed in a post-prandial state.
{"title":"Physiologic and performance effects of sago supplementation before and during cycling in a warm-humid environment","authors":"M. R. Che Jusoh, S. Stannard, T. Mündel","doi":"10.1080/23328940.2016.1159772","DOIUrl":"https://doi.org/10.1080/23328940.2016.1159772","url":null,"abstract":"ABSTRACT The present study determined whether 0.8g/kg bodyweight sago ingested before (Pre-Sago) or during (Dur-Sago) exercise under warm-humid conditions (30 ± 2°C, 78 ± 3 % RH; 20 km·h−1 frontal airflow) conferred a performance and/or physiological benefit compared to a control (Control) condition. Eight trained, male cyclists/triathletes (45 ± 4 y, VO2peak: 65 ± 10 ml·kg−1·min−1, peak aerobic power: 397 ± 71 W) completed 3 15-min time-trials (∼75% VO2peak) pre-loaded with 45 min of steady-state (∼55% VO2peak) cycling following > 24 h standardization of training and diet. Measures of work completed, rectal and mean skin temperatures, heart rate, expiratory gases and venous blood samples were taken. Compared to Control, Pre-Sago resulted in a smaller rise in rectal temperature (0.3 ± 0.5°C) while heart rate increased to a greater extent (6 ± 13 beats·min−1) during exercise (both P < 0.05), however, compared to Control time-trial performance remained unaffected (Pre-Sago: −0.5 ± 4.0%, P > 0.05). During exercise, plasma glucose concentrations were maintained higher for Dur-Sago than Control (P < 0.05), however substrate oxidation rates remained similar (P > 0.05). Dur-Sago also resulted in a higher plasma sodium concentration (2 ± 2 mmol·l1) and lower whole-body sweat loss (544 ± 636 g) and, therefore, reduced plasma volume contraction (all P < 0.05). Heart rate increased to a greater extent (5 ± 13 beats·min−1) during Dur-Sago, yet compared to Control time-trial performance remained unaffected (+0.9 ± 2.3%, P > 0.05). Uniquely, these results indicate that during exercise heat stress feeding sago can result in some ‘beneficial’ physiological responses, however these do not translate to changes in exercise performance when performed in a post-prandial state.","PeriodicalId":22565,"journal":{"name":"Temperature: Multidisciplinary Biomedical Journal","volume":"291 1","pages":"318 - 327"},"PeriodicalIF":0.0,"publicationDate":"2016-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79490814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-02-26DOI: 10.1080/23328940.2016.1157668
J. Deuis, I. Vetter
ABSTRACT Rodent models are frequently used to improve our understanding of the molecular mechanisms of pain and to develop novel analgesics. Robust behavioral assays that quantify nociceptive responses to different sensory modalities, such has heat, are therefore needed. Here, we describe a novel behavioral assay to quantify thermal paw withdrawal thresholds in mice, called the thermal probe test, and compared it with other methods commonly used to measure heat thresholds, namely the Hargreaves test and the dynamic and conventional hot plate tests. In the thermal probe test, a slightly rounded 2.5 mm diameter metal probe that heats on contact at a rate of 2.5°C/sec, is applied to the plantar surface of the hind paw in mice at a starting temperature of ∼37°C, and the temperature at which a withdrawal response occurs, designated as the paw withdrawal temperature, is automatically recorded. The thermal probe test is effective at quantifying thermal allodynia in carrageenan-induced inflammation (paw withdrawal temperature 3 h: contralateral, 50.3 ± 0.6°C; ipsilateral, 43.1 ± 1.0°C), burns injury (paw withdrawal temperature 3 d: contralateral, 50.8 ± 0.5°C; ipsilateral, 43.2 ± 0.6°C) and after topical capsaicin (paw withdrawal temperature: vehicle control, 49.7 ± 0.6°C; capsaicin, 44.8 ± 1.2°C), giving comparable results to the Hargreaves test. In addition, the thermal probe test can detect opioid mediated analgesia in carrageenan-induced inflammation. Therefore the thermal probe test is a novel behavioral assay effective for quantifying thermal allodynia and analgesia in mouse models of pain.
{"title":"The thermal probe test: A novel behavioral assay to quantify thermal paw withdrawal thresholds in mice","authors":"J. Deuis, I. Vetter","doi":"10.1080/23328940.2016.1157668","DOIUrl":"https://doi.org/10.1080/23328940.2016.1157668","url":null,"abstract":"ABSTRACT Rodent models are frequently used to improve our understanding of the molecular mechanisms of pain and to develop novel analgesics. Robust behavioral assays that quantify nociceptive responses to different sensory modalities, such has heat, are therefore needed. Here, we describe a novel behavioral assay to quantify thermal paw withdrawal thresholds in mice, called the thermal probe test, and compared it with other methods commonly used to measure heat thresholds, namely the Hargreaves test and the dynamic and conventional hot plate tests. In the thermal probe test, a slightly rounded 2.5 mm diameter metal probe that heats on contact at a rate of 2.5°C/sec, is applied to the plantar surface of the hind paw in mice at a starting temperature of ∼37°C, and the temperature at which a withdrawal response occurs, designated as the paw withdrawal temperature, is automatically recorded. The thermal probe test is effective at quantifying thermal allodynia in carrageenan-induced inflammation (paw withdrawal temperature 3 h: contralateral, 50.3 ± 0.6°C; ipsilateral, 43.1 ± 1.0°C), burns injury (paw withdrawal temperature 3 d: contralateral, 50.8 ± 0.5°C; ipsilateral, 43.2 ± 0.6°C) and after topical capsaicin (paw withdrawal temperature: vehicle control, 49.7 ± 0.6°C; capsaicin, 44.8 ± 1.2°C), giving comparable results to the Hargreaves test. In addition, the thermal probe test can detect opioid mediated analgesia in carrageenan-induced inflammation. Therefore the thermal probe test is a novel behavioral assay effective for quantifying thermal allodynia and analgesia in mouse models of pain.","PeriodicalId":22565,"journal":{"name":"Temperature: Multidisciplinary Biomedical Journal","volume":"16 1","pages":"199 - 207"},"PeriodicalIF":0.0,"publicationDate":"2016-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83633072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-02-26DOI: 10.1080/23328940.2016.1156801
A. Hunt, D. Billing, M. J. Patterson, Joanne N. Caldwell
ABSTRACT Military activities in hot environments pose 2 competing demands: the requirement to perform realistic training to develop operational capability with the necessity to protect armed forces personnel against heat-related illness. To ascertain whether work duration limits for protection against heat-related illness restrict military activities, this study examined the heat strain and risks of heat-related illness when conducting a military activity above the prescribed work duration limits. Thirty-seven soldiers conducted a march (10 km; ∼5.5 km h−1) carrying 41.8 ± 3.6 kg of equipment in 23.1 ± 1.8°C wet-bulb globe temperature. Body core temperature was recorded throughout and upon completion, or withdrawal, participants rated their severity of heat-related symptoms. Twenty-three soldiers completed the march in 107 ± 6.4 min (Completers); 9 were symptomatic for heat exhaustion, withdrawing after 71.6 ± 10.1 min (Symptomatic); and five were removed for body core temperature above 39.0°C (Hyperthermic) after 58.4 ± 4.5 min. Body core temperature was significantly higher in the Hyperthermic (39.03 ± 0.26°C), than Symptomatic (38.34 ± 0.44°C; P = 0.007) and Completers (37.94 ± 0.37°C; P<0.001) after 50 min. Heat-related symptom severity was significantly higher among Symptomatic (28.4 ± 11.8) compared to Completers (15.0 ± 9.8, P = 0.006) and Hyperthermic (13.0 ± 9.6, P = 0.029). The force protection provided by work duration limits may be preventing the majority of personnel from conducting activities in hot environments, thereby constraining a commander's mandate to develop an optimised military force. The dissociation between heat-related symptoms and body core temperature elevation suggests that the physiological mechanisms underpinning exhaustion during exertional heat stress should be re-examined to determine the most appropriate physiological criteria for prescribing work duration limits.
{"title":"Heat strain during military training activities: The dilemma of balancing force protection and operational capability","authors":"A. Hunt, D. Billing, M. J. Patterson, Joanne N. Caldwell","doi":"10.1080/23328940.2016.1156801","DOIUrl":"https://doi.org/10.1080/23328940.2016.1156801","url":null,"abstract":"ABSTRACT Military activities in hot environments pose 2 competing demands: the requirement to perform realistic training to develop operational capability with the necessity to protect armed forces personnel against heat-related illness. To ascertain whether work duration limits for protection against heat-related illness restrict military activities, this study examined the heat strain and risks of heat-related illness when conducting a military activity above the prescribed work duration limits. Thirty-seven soldiers conducted a march (10 km; ∼5.5 km h−1) carrying 41.8 ± 3.6 kg of equipment in 23.1 ± 1.8°C wet-bulb globe temperature. Body core temperature was recorded throughout and upon completion, or withdrawal, participants rated their severity of heat-related symptoms. Twenty-three soldiers completed the march in 107 ± 6.4 min (Completers); 9 were symptomatic for heat exhaustion, withdrawing after 71.6 ± 10.1 min (Symptomatic); and five were removed for body core temperature above 39.0°C (Hyperthermic) after 58.4 ± 4.5 min. Body core temperature was significantly higher in the Hyperthermic (39.03 ± 0.26°C), than Symptomatic (38.34 ± 0.44°C; P = 0.007) and Completers (37.94 ± 0.37°C; P<0.001) after 50 min. Heat-related symptom severity was significantly higher among Symptomatic (28.4 ± 11.8) compared to Completers (15.0 ± 9.8, P = 0.006) and Hyperthermic (13.0 ± 9.6, P = 0.029). The force protection provided by work duration limits may be preventing the majority of personnel from conducting activities in hot environments, thereby constraining a commander's mandate to develop an optimised military force. The dissociation between heat-related symptoms and body core temperature elevation suggests that the physiological mechanisms underpinning exhaustion during exertional heat stress should be re-examined to determine the most appropriate physiological criteria for prescribing work duration limits.","PeriodicalId":22565,"journal":{"name":"Temperature: Multidisciplinary Biomedical Journal","volume":"306 1","pages":"307 - 317"},"PeriodicalIF":0.0,"publicationDate":"2016-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77777895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-02-26DOI: 10.1080/23328940.2016.1157665
J. Brock, R. McAllen
ABSTRACT We review the evidence for thermoregulatory temperature sensors in the mammalian spinal cord and reach the following conclusions. 1) Spinal cord temperature contributes physiologically to temperature regulation. 2) Parallel anterolateral ascending pathways transmit signals from spinal cooling and spinal warming: they overlap with the respective axon pathways of the dorsal horn neurons that are driven by peripheral cold- and warm-sensitive afferents. 3) We hypothesize that these ‘cold’ and ‘warm’ ascending pathways transmit all extracranial thermosensory information to the brain. 4) Cutaneous cold afferents can be activated not only by cooling the skin but also by cooling sites along their axons: we consider that this is functionally insignificant in vivo. 5) By a presynaptic action on their central terminals, local spinal cooling enhances neurotransmission from incoming ‘cold’ afferent action potentials to second order neurons in the dorsal horn; this effect disappears when the spinal cord is warm. 6) Spinal warm sensitivity is due to warm-sensitive miniature vesicular transmitter release from afferent terminals in the dorsal horn: this effect is powerful enough to excite second order neurons in the ‘warm’ pathway independently of any incoming sensory traffic. 7) Distinct but related presynaptic mechanisms at cold- and warm-sensitive afferent terminals can thus account for the thermoregulatory actions of spinal cord temperature.
{"title":"Spinal cord thermosensitivity: An afferent phenomenon?","authors":"J. Brock, R. McAllen","doi":"10.1080/23328940.2016.1157665","DOIUrl":"https://doi.org/10.1080/23328940.2016.1157665","url":null,"abstract":"ABSTRACT We review the evidence for thermoregulatory temperature sensors in the mammalian spinal cord and reach the following conclusions. 1) Spinal cord temperature contributes physiologically to temperature regulation. 2) Parallel anterolateral ascending pathways transmit signals from spinal cooling and spinal warming: they overlap with the respective axon pathways of the dorsal horn neurons that are driven by peripheral cold- and warm-sensitive afferents. 3) We hypothesize that these ‘cold’ and ‘warm’ ascending pathways transmit all extracranial thermosensory information to the brain. 4) Cutaneous cold afferents can be activated not only by cooling the skin but also by cooling sites along their axons: we consider that this is functionally insignificant in vivo. 5) By a presynaptic action on their central terminals, local spinal cooling enhances neurotransmission from incoming ‘cold’ afferent action potentials to second order neurons in the dorsal horn; this effect disappears when the spinal cord is warm. 6) Spinal warm sensitivity is due to warm-sensitive miniature vesicular transmitter release from afferent terminals in the dorsal horn: this effect is powerful enough to excite second order neurons in the ‘warm’ pathway independently of any incoming sensory traffic. 7) Distinct but related presynaptic mechanisms at cold- and warm-sensitive afferent terminals can thus account for the thermoregulatory actions of spinal cord temperature.","PeriodicalId":22565,"journal":{"name":"Temperature: Multidisciplinary Biomedical Journal","volume":"506 1","pages":"232 - 239"},"PeriodicalIF":0.0,"publicationDate":"2016-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79927209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-02-26DOI: 10.1080/23328940.2016.1153360
J. Stephens, A. Schiemann, C. Roesl, Dorota M. Miller, S. Massey, N. Pollock, T. Bulger, K. Stowell
ABSTRACT Malignant hyperthermia manifests as a rapid and sustained rise in temperature in response to pharmacological triggering agents, e.g. inhalational anesthetics and the muscle relaxant suxamethonium. Other clinical signs include an increase in end-tidal CO2, increased O2 consumption, as well as tachycardia, and if untreated a malignant hyperthermia episode can result in death. The metabolic changes are caused by dysregulation of skeletal muscle Ca2+ homeostasis, resulting from a defective ryanodine receptor Ca2+ channel, which resides in the sarcoplasmic reticulum and controls the flux of Ca2+ ions from intracellular stores to the cytoplasm. Most genetic variants associated with susceptibility to malignant hyperthermia occur in the RYR1 gene encoding the ryanodine receptor type 1. While malignant hyperthermia susceptibility can be diagnosed by in vitro contracture testing of skeletal muscle biopsy tissue, it is advantageous to use DNA testing. Currently only 35 of over 400 potential variants in RYR1 have been classed as functionally causative of malignant hyperthermia and thus can be used for DNA diagnostic tests. Here we describe functional analysis of 2 RYR1 variants (c. 7042_7044delCAG, p.ΔGlu2348 and c.641C>T, p.Thr214Met) that occur in the same malignant hyperthermia susceptible family. The p.Glu2348 deletion, causes hypersensitivity to ryanodine receptor agonists using in vitro analysis of cloned human RYR1 cDNA expressed in HEK293T cells, while the Thr214Met substitution, does not appear to significantly alter sensitivity to agonist in the same system. We suggest that the c. 7042_7044delCAG, p.ΔGlu2348 RYR1 variant could be added to the list of diagnostic mutations for susceptibility to malignant hyperthermia.
{"title":"Functional analysis of RYR1 variants linked to malignant hyperthermia","authors":"J. Stephens, A. Schiemann, C. Roesl, Dorota M. Miller, S. Massey, N. Pollock, T. Bulger, K. Stowell","doi":"10.1080/23328940.2016.1153360","DOIUrl":"https://doi.org/10.1080/23328940.2016.1153360","url":null,"abstract":"ABSTRACT Malignant hyperthermia manifests as a rapid and sustained rise in temperature in response to pharmacological triggering agents, e.g. inhalational anesthetics and the muscle relaxant suxamethonium. Other clinical signs include an increase in end-tidal CO2, increased O2 consumption, as well as tachycardia, and if untreated a malignant hyperthermia episode can result in death. The metabolic changes are caused by dysregulation of skeletal muscle Ca2+ homeostasis, resulting from a defective ryanodine receptor Ca2+ channel, which resides in the sarcoplasmic reticulum and controls the flux of Ca2+ ions from intracellular stores to the cytoplasm. Most genetic variants associated with susceptibility to malignant hyperthermia occur in the RYR1 gene encoding the ryanodine receptor type 1. While malignant hyperthermia susceptibility can be diagnosed by in vitro contracture testing of skeletal muscle biopsy tissue, it is advantageous to use DNA testing. Currently only 35 of over 400 potential variants in RYR1 have been classed as functionally causative of malignant hyperthermia and thus can be used for DNA diagnostic tests. Here we describe functional analysis of 2 RYR1 variants (c. 7042_7044delCAG, p.ΔGlu2348 and c.641C>T, p.Thr214Met) that occur in the same malignant hyperthermia susceptible family. The p.Glu2348 deletion, causes hypersensitivity to ryanodine receptor agonists using in vitro analysis of cloned human RYR1 cDNA expressed in HEK293T cells, while the Thr214Met substitution, does not appear to significantly alter sensitivity to agonist in the same system. We suggest that the c. 7042_7044delCAG, p.ΔGlu2348 RYR1 variant could be added to the list of diagnostic mutations for susceptibility to malignant hyperthermia.","PeriodicalId":22565,"journal":{"name":"Temperature: Multidisciplinary Biomedical Journal","volume":"16 8 1","pages":"328 - 339"},"PeriodicalIF":0.0,"publicationDate":"2016-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82933035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-02-22DOI: 10.1080/23328940.2016.1148526
Z. Schlader, J. Temple, D. Hostler
ABSTRACT We tested the hypothesis that heat stress created by light exertion in encapsulating personal protective equipment (PPE) in a hot, humid environment increases risk propensity. Ten healthy subjects (29 ± 7 y) completed 2 trials presented in a counter-balanced manner. Subjects donned encapsulating PPE, and in one trial they wore a tube-lined shirt underneath that was perfused with 5°C water. Subjects completed 2 15 min bouts of walking exercise on a treadmill at ˜50% maximal heart rate in a 32°C, 81% RH environment. Subjects completed the Balloon Analog Risk Task (BART), an objective measure of risk-taking, before, between the 2 exercise bouts, and following the final exercise bout. Personal cooling lowered (P < 0.01) mean skin temperature by 8.0 ± 1.6°C. Intestinal temperature rose (P < 0.01) in both trials, but was lower (P < 0.01) at the end of exercise in the cooling trial (38.0 ± 0.3°C vs. 37.6 ± 0.3°C). BART derived indices of risk propensity were not affected by trial or time (trial × time interaction: P ≥ 0.33). These data indicate that 60 min of exposure to mild heat stress created by light exertion in encapsulating PPE does not affect risk-taking behavior.
{"title":"Exercise in personal protective equipment in a hot, humid environment does not affect risk propensity","authors":"Z. Schlader, J. Temple, D. Hostler","doi":"10.1080/23328940.2016.1148526","DOIUrl":"https://doi.org/10.1080/23328940.2016.1148526","url":null,"abstract":"ABSTRACT We tested the hypothesis that heat stress created by light exertion in encapsulating personal protective equipment (PPE) in a hot, humid environment increases risk propensity. Ten healthy subjects (29 ± 7 y) completed 2 trials presented in a counter-balanced manner. Subjects donned encapsulating PPE, and in one trial they wore a tube-lined shirt underneath that was perfused with 5°C water. Subjects completed 2 15 min bouts of walking exercise on a treadmill at ˜50% maximal heart rate in a 32°C, 81% RH environment. Subjects completed the Balloon Analog Risk Task (BART), an objective measure of risk-taking, before, between the 2 exercise bouts, and following the final exercise bout. Personal cooling lowered (P < 0.01) mean skin temperature by 8.0 ± 1.6°C. Intestinal temperature rose (P < 0.01) in both trials, but was lower (P < 0.01) at the end of exercise in the cooling trial (38.0 ± 0.3°C vs. 37.6 ± 0.3°C). BART derived indices of risk propensity were not affected by trial or time (trial × time interaction: P ≥ 0.33). These data indicate that 60 min of exposure to mild heat stress created by light exertion in encapsulating PPE does not affect risk-taking behavior.","PeriodicalId":22565,"journal":{"name":"Temperature: Multidisciplinary Biomedical Journal","volume":"84 1","pages":"262 - 270"},"PeriodicalIF":0.0,"publicationDate":"2016-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76963051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-10-02DOI: 10.1080/23328940.2015.1091874
Nikki Bortell, Julia A. Najera, M. Sanchez-Alavez, M. C. Marcondes
Methamphetamine (commonly known as Meth) is a highly addictive drug of abuse, which causes a potentially lethal increase in core body temperature, or hyperthermia. We have recently found that Meth-induced hyperthermia has a significant participation of the thermogenic brown adipose tissue,1 and can be prevented by a pretreatment with the antioxidant N-acetyl cysteine.1 For this publication, we labeled reactive oxygen species, such as superoxide, in vivo, by injecting C57Bl/6 mice with dihydroethidium; we then harvested and processed interscapular brown adipose tissue (for methods, see ref. 1). Reactive oxygen species were visualized in brown fat and found to be largely associated with mitochondria (Slide 1). In the slide, dihydroethidium-labeled superoxide is seen as red; the mitochondrial marker TOMM20 is seen as yellow; the cytoskeleton F-actin marker Phalloidin Alexa488 is seen as green; and the DNA marker DAPI is seen in blue. Meth depleted superoxide in brown-fat mitochondria, in correlation with the loss of TOMM20-labeled mitochondria. These changes were detectable in brown fat as early as 15 minutes after the injection of the drug, with a peak at 1 hour following injection, which is seen in Slide 1. The N-acetyl cysteine pretreatment prevented the loss of TOMM20 induced by Meth, but did not restore the Meth-depleted superoxide storages in mitochondria. Overall, this slide shows that Meth impacts the mitochondrial storages of superoxide, as well as mitochondrial integrity, in brown adipose tissue. The functional importance of these observations remains to be established and requires further studies.
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Pub Date : 2015-03-31DOI: 10.1080/23328940.2015.1017090
Andrea Fullér, C. Blatteis
It is with great sadness that we report the passing of our dear colleagues: Professor Helen Laburn and Professor Claus Jessen. We will always remember them.
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Pub Date : 2015-02-11DOI: 10.1080/23328940.2015.1009315
V. Lun
The purpose of the “Medicine in Challenging Environments” app, published in 2014 by the Mayo Clinic, is stated as “. . . to provide practical, evidence-based multi-specialty knowledge . . .” for the primary care physician to provide guidance for their patients who engage in high adventure activities and to assist high adventurers in their planning for such activities. The app editors are 3 Mayo Clinic physicians: Dr. Jan Stepanek (internist and aerospace medicine), Dr. Robert Johnson (pediatrician) and Dr. Daniela Cocco (Mayo Clinic Aerospace Medicine and Vestibular Research Laboratory researcher). The content of the application is organized in 3 main sections with multiple chapters in each section: Environments, Specific Clinical Problems and Special Considerations. This “app” is essentially a book. Navigation through the app is similar to most book-type apps. The “Home” tab leads to an introduction and hypoxia, temperature and wind/pressure calculators. The “Chapters” tab leads to all the book chapters. Each chapter is broken down into subsections. Swiping up/down scrolls a single page and swiping left and right changes pages, sections and chapters. The app is searchable by keyword. The only interactive aspects of the app are the hypoxia, temperature and wind/ pressure calculators. The content of the “Environments” section focuses on the human physiology and medical/clinical considerations as related to exposure to extremes of environmental conditions including hyper/hypo-gravity, altitude, hydration, ionizing radiation, thermal, etc.. There is also a chapter on motor sports but there is no specific chapter or content dedicated to undersea/hyperbaric medicine. The content of the “Specific Clinical Problems” focuses on medical sub-specialty specific management of travel-related medical problems and is not really related directly to the “Environments” section of the app. Each chapter has “Clinical Vignette(s)” which describes a clinical case(s) that a clinician may encounter, which enhances the practical aspect of the app. The content of the “Special Considerations” section has chapters focusing on survival strategies. For the clinician without knowledge or previous experience in guiding patients who might be facing extreme environmental conditions, this app would be a very good basic reference. The editors do attempt to make the information practical by including clinical cases (“Clinical Vignettes”). However, the challenge with any clinical reference is that it is difficult to anticipate every clinical scenario that one may face and every chapter of book could be a book in and of themselves. Moreover, clinical practice can change very quickly, so the information needs to be updated frequently. The most useful section of the app, as it relates to the title of the app, is the “Environments” section. The “Hydration” and “Thermal” chapters of this section, written by Dr. Stephen Cheung of Brock University (Canada), and Dr. Christopher Tyler of Roeh
{"title":"A new app for physicians on environmental medicine","authors":"V. Lun","doi":"10.1080/23328940.2015.1009315","DOIUrl":"https://doi.org/10.1080/23328940.2015.1009315","url":null,"abstract":"The purpose of the “Medicine in Challenging Environments” app, published in 2014 by the Mayo Clinic, is stated as “. . . to provide practical, evidence-based multi-specialty knowledge . . .” for the primary care physician to provide guidance for their patients who engage in high adventure activities and to assist high adventurers in their planning for such activities. The app editors are 3 Mayo Clinic physicians: Dr. Jan Stepanek (internist and aerospace medicine), Dr. Robert Johnson (pediatrician) and Dr. Daniela Cocco (Mayo Clinic Aerospace Medicine and Vestibular Research Laboratory researcher). The content of the application is organized in 3 main sections with multiple chapters in each section: Environments, Specific Clinical Problems and Special Considerations. This “app” is essentially a book. Navigation through the app is similar to most book-type apps. The “Home” tab leads to an introduction and hypoxia, temperature and wind/pressure calculators. The “Chapters” tab leads to all the book chapters. Each chapter is broken down into subsections. Swiping up/down scrolls a single page and swiping left and right changes pages, sections and chapters. The app is searchable by keyword. The only interactive aspects of the app are the hypoxia, temperature and wind/ pressure calculators. The content of the “Environments” section focuses on the human physiology and medical/clinical considerations as related to exposure to extremes of environmental conditions including hyper/hypo-gravity, altitude, hydration, ionizing radiation, thermal, etc.. There is also a chapter on motor sports but there is no specific chapter or content dedicated to undersea/hyperbaric medicine. The content of the “Specific Clinical Problems” focuses on medical sub-specialty specific management of travel-related medical problems and is not really related directly to the “Environments” section of the app. Each chapter has “Clinical Vignette(s)” which describes a clinical case(s) that a clinician may encounter, which enhances the practical aspect of the app. The content of the “Special Considerations” section has chapters focusing on survival strategies. For the clinician without knowledge or previous experience in guiding patients who might be facing extreme environmental conditions, this app would be a very good basic reference. The editors do attempt to make the information practical by including clinical cases (“Clinical Vignettes”). However, the challenge with any clinical reference is that it is difficult to anticipate every clinical scenario that one may face and every chapter of book could be a book in and of themselves. Moreover, clinical practice can change very quickly, so the information needs to be updated frequently. The most useful section of the app, as it relates to the title of the app, is the “Environments” section. The “Hydration” and “Thermal” chapters of this section, written by Dr. Stephen Cheung of Brock University (Canada), and Dr. Christopher Tyler of Roeh","PeriodicalId":22565,"journal":{"name":"Temperature: Multidisciplinary Biomedical Journal","volume":"2 1","pages":"53 - 53"},"PeriodicalIF":0.0,"publicationDate":"2015-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85034084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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