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Jessica J Scriven, Penelope R Whitehorn, Dave Goulson, Matthew C Tinsley
According to Bergmann's rule we expect species with larger body size to inhabit locations with a cooler climate, where they may be well adapted to conserve heat and resist starvation. This rule is generally applied to endotherms. In contrast, body size in ectothermic invertebrates has been suggested to follow the reverse ecogeographic trend: these converse Bergmann's patterns may be driven by the ecological constraints of shorter season length and lower food availability in cooler high latitude locations. Such patterns are particularly common in large insects due to their longer development times...
2016: PloS One
Takayuki Ishiwata, Arisa Oshimoto, Takehito Saito, Yasunori Kotani, Shigeki Nomoto, Yasutsugu Aihara, Hiroshi Hasegawa, Benjamin N Greenwood
We previously reported that tetrodotoxin (TTX) perfusion into the median raphe nucleus (MRN), which contains the cell bodies of serotonin (5-HT) neurons, induced a considerable body temperature reduction under normal and low ambient temperatures (23 and 5°C, respectively) in freely moving rats but showed no such effect under high ambient temperature (35°C). In the present study, we aimed to determine the mechanism(s) of body temperature reduction after TTX perfusion into the MRN by measuring tail skin temperature (an index of heat loss), heart rate (an index of heat production), and locomotor activity (Act) under normal ambient temperature (23°C)...
October 12, 2016: Neuroreport
P Cordery, N Peirce, R J Maughan, P Watson
Catecholamine reuptake inhibition improves the performance of male volunteers exercising in warm conditions, but sex differences in thermoregulation, circulating hormones, and central neurotransmission may alter this response. With local ethics committee approval, nine physically active women (mean ± SD age 21 ± 2 years; height 1.68 ± 0.08 m; body mass 64.1 ± 6.0 kg; VO2peak 51 ± 7 mL/kg/min) were recruited to examine the effect of pre-exercise administration of Bupropion (BUP; 4 × 150 mg) on prolonged exercise performance in a warm environment...
October 13, 2016: Scandinavian Journal of Medicine & Science in Sports
Jonathan B Armstrong, Eric J Ward, Daniel E Schindler, Peter J Lisi
As climate change increases maximal water temperatures, behavioural thermoregulation may be crucial for the persistence of coldwater fishes, such as salmonids. Although myriad studies have documented behavioural thermoregulation in southern populations of salmonids, few if any have explored this phenomenon in northern populations, which are less likely to have an evolutionary history of heat stress, yet are predicted to experience substantial warming. Here, we treated a rare heat wave as a natural experiment to test whether wild sockeye salmon (Oncorhynchus nerka) at the northern extent of their primary range (60° latitude) can thermoregulate in response to abnormally high thermal conditions...
2016: Conservation Physiology
Axel R Concepcion, Martin Vaeth, Larry E Wagner, Miriam Eckstein, Lee Hecht, Jun Yang, David Crottes, Maximilian Seidl, Hyosup P Shin, Carl Weidinger, Scott Cameron, Stuart E Turvey, Thomas Issekutz, Isabelle Meyts, Rodrigo S Lacruz, Mario Cuk, David I Yule, Stefan Feske
Eccrine sweat glands are essential for sweating and thermoregulation in humans. Loss-of-function mutations in the Ca2+ release-activated Ca2+ (CRAC) channel genes ORAI1 and STIM1 abolish store-operated Ca2+ entry (SOCE), and patients with these CRAC channel mutations suffer from anhidrosis and hyperthermia at high ambient temperatures. Here we have shown that CRAC channel-deficient patients and mice with ectodermal tissue-specific deletion of Orai1 (Orai1K14Cre) or Stim1 and Stim2 (Stim1/2K14Cre) failed to sweat despite normal sweat gland development...
October 10, 2016: Journal of Clinical Investigation
Sarah A Codde, Sarah G Allen, Dorian S Houser, Daniel E Crocker
Pinnipeds spend extended periods of time on shore during breeding, and some temperate species retreat to the water if exposed to high ambient temperatures. However, female northern elephant seals (Mirounga angustirostris) with pups generally avoid the water, presumably to minimize risks to pups or male harassment. Little is known about how ambient temperature affects thermoregulation of well insulated females while on shore. We used a thermographic camera to measure surface temperature (Ts) of 100 adult female elephant seals and their pups during the breeding season at Point Reyes National Seashore, yielding 782 thermograms...
October 2016: Journal of Thermal Biology
Panayiotis Pafilis, Petros Lymberakis, Kostas Sagonas, Efstratios Valakos
Environmental temperatures considerably affect the reptilian ability for thermoregulation and harsh climatic conditions may impose a highly effective body temperature regulation to lizards. Such demanding conditions are more common to extreme mainland habitats (e.g. deserts or mountains). To the contrary, islands have more benign climate conditions thanks to the thermal buffering effect of the surrounding sea. However, this favorable effect may be eliminated in small size islets where the scarcity of thermal shelters and exposure to high winds create challenging conditions...
October 2016: Journal of Thermal Biology
Zaida Ortega, Abraham Mencía, Valentín Pérez-Mellado
Temperature determines all aspects of the biology of ectotherms. Although sexual differences in thermal ecology are not the rule in lizards, some species exhibit such differences. We studied the effect of sex and reproductive condition on the thermoregulation of an introduced population of Scelarcis perspicillata during the summer in Menorca (Balearic Islands, Spain). These lizards live in the wall surfaces of a limestone quarry, where the sun is scarce because of the narrowness of the quarry walls. The population is sexually dimorphic, with larger males than females...
October 2016: Journal of Thermal Biology
John W Rowe, David L Clark, Rebecca A Mortensen, Carolyn V Commissaris, Lawrence W Wittle, John K Tucker
Color and pigmentation patterns of the integument can facilitate crypsis, thermoregulation, and social signaling. According to the "thermal melanism hypothesis", cold environmental temperature should increase the quantity of melanin that is deposited in the integument thereby facilitating radiative warming. We studied the influences of water temperature (26°C or 31°C) and substrate color (black or white) on the degree of melanization in the red-eared slider, Trachemys scripta elegans, under laboratory conditions...
October 2016: Journal of Thermal Biology
Xi-Ling Jiang, Hong-Wu Shen, Donald E Mager, Stephan Schmidt, Ai-Ming Yu
We have shown recently that concurrent harmaline, a monoamine oxidase-A inhibitor (MAOI), potentiates serotonin (5-HT) receptor agonist 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT)-induced hyperthermia. The objective of this study was to develop an integrated pharmacokinetic/pharmacodynamic (PK/PD) model to characterize and predict the thermoregulatory effects of such serotonergic drugs in mice. Physiological thermoregulation was described by a mechanism-based indirect-response model with adaptive feedback control...
September 2016: Acta Pharmaceutica Sinica. B
Christopher J Davis, Ping Taishi, Kimberly A Honn, John N Koberstein, James M Krueger
The ionotropic purine type 2X7 receptor (P2X7R) is a non-specific cation channel implicated in sleep regulation and brain cytokine release. Many endogenous rhythms co-vary with sleep including locomotor activity and core body temperature. Further, brain-hypothalamic cytokines and purines play a role in the regulation of these physiological parameters as well as sleep. We hypothesized that these parameters are also affected by the absence of the P2X7 receptor. Herein we determine spontaneous expression of body temperature and locomotor activity in WT and P2X7R knockout (KO) mice and how they are affected by sleep deprivation (SD)...
October 5, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Enrico Marchetti, Pasquale Capone, Daniela Freda
INTRODUCTION: Climate change is a global emergency that influences human health and occupational safety. Global warming characterized by an increase in temperature of the ambience and humidity affects human health directly impairing body thermoregulation with serious consequences: dehydration, fatigue, heat stroke and even death. Several studies have demonstrated negative effects of climate change on working populations in a wide variety of workplaces with particular regard to outdoor and uncooled indoor workplaces...
July 2016: Annali Dell'Istituto Superiore di Sanità
Kamiar Ghoseiri, Yong Ping Zheng, Aaron K L Leung, Mehdi Rahgozar, Gholamreza Aminian, Tat Hing Lee, Mohammad Reza Safari
The accumulation of heat inside the prosthetic socket increases skin temperature and fosters perspiration, which consequently leads to high tissue stress, friction blister, discomfort, unpleasant odor, and decreased prosthesis suspension and use. In the present study, the prototype of a temperature measurement and control (TM&C) system was designed, fabricated, and functionally evaluated in a phantom model of the transtibial prosthetic socket. The TM&C system was comprised of twelve Thermistors that were divided equally into two groups that arranged internal and external to a prosthetic silicone liner...
October 3, 2016: Assistive Technology: the Official Journal of RESNA
Danilo Antonini Alves, Daisy Machado, Adriana Melo, Rafaella Fabiana Carneiro Pereira, Patrícia Severino, Luciana Maria de Hollanda, Daniele Ribeiro Araújo, Marcelo Lancellotti
Levofloxacin is a synthetic broad-spectrum antibacterial agent for oral or intravenous administration. Chemically, levofloxacin is the levorotatory isomer (L-isomer) of racemate ofloxacin, a fluoroquinolone antibacterial agent. Quinolone derivatives rapidly and specifically inhibit the synthesis of bacterial DNA. Levofloxacin has in vitro activity against a broad range of aerobic and anaerobic Gram-positive and Gram-negative bacteria. However, formulation of combined poloxamers thermoregulated (as Pluronic® F127) and levofloxacin for use in multiresistant bacterial treatment were poorly described in the current literature...
2016: BioMed Research International
Karl J Kaiyala, Kayoko Ogimoto, Jarrell T Nelson, Kenjiro Muta, Gregory J Morton
OBJECTIVE: To investigate the role played by leptin in thermoregulation, we studied the effects of physiological leptin replacement in leptin-deficient ob/ob mice on determinants of energy balance, thermogenesis and heat retention under 3 different ambient temperatures. METHODS: The effects of housing at 14 °C, 22 °C or 30 °C on core temperature (telemetry), energy expenditure (respirometry), thermal conductance, body composition, energy intake, and locomotor activity (beam breaks) were measured in ob/ob mice implanted subcutaneously with osmotic minipumps at a dose designed to deliver a physiological replacement dose of leptin or its vehicle-control...
October 2016: Molecular Metabolism
William Ruger Porter, Jayc C Sedlmayr, Lawrence M Witmer
Extant crocodilians are a highly apomorphic archosaur clade that is ectothermic, yet often achieve large body sizes that can be subject to higher heat loads. Therefore, the anatomical and physiological roles that blood vessels play in crocodilian thermoregulation need further investigation to better understand how crocodilians establish and maintain cephalic temperatures and regulate neurosensory tissue temperatures during basking and normal activities. The cephalic vascular anatomy of extant crocodilians, particularly American alligator (Alligator mississippiensis) was investigated using a differential-contrast, dual-vascular injection technique and high resolution X-ray micro-computed tomography (μCT)...
September 28, 2016: Journal of Anatomy
Leslie Brown, Jeong-Ho Kim, Kyu Hong Cho
A hyaluronic acid capsule is a major virulence factor in the pathogenesis of Streptococcus pyogenes. It acts as an anti-phagocytic agent and adhesin to keratinocytes. The expression of the capsule is primarily regulated at the transcriptional level by the two-component regulatory system CovRS, in which CovR acts as a transcriptional repressor. The covRS genes are frequently mutated in many invasive strains, and a subset of the invasive CovRS mutants does not produce a detectable level of the capsule at 37 °C, but produces a significant amount of the capsule at sub-body temperatures...
2016: Genes
Víctor Hugo Ramírez-Delgado, Salomón Sanabria-Urbán, Martin A Serrano-Meneses, Raúl Cueva Del Castillo
Two patterns commonly emerge when animal body size is analyzed as a function of latitudinal distribution. First, body size increases with latitude, a temperature effect known as Bergmann's rule, and second, the converse to Bergmann's rule, a pattern in which body size decreases with latitude. However, other geographic patterns can emerge when the mechanisms that generate Bergmann's and the converse to Bergmann's clines operate together. Here, we use phylogenetic comparative analysis in order to control for phylogenetic inertia, and we show that bumblebees exhibit the converse to Bergmann's rule...
September 2016: Ecology and Evolution
Christopher L Riley, Christine Dao, M Alexander Kenaston, Luigina Muto, Shohei Kohno, Sara M Nowinski, Ashley D Solmonson, Matthew Pfeiffer, Michael N Sack, Zhongping Lu, Giuseppe Fiermonte, Jon E Sprague, Edward M Mills
Uncoupling protein 1 (UCP1) is the established mediator of brown adipose tissue dependent thermogenesis. In contrast, the role of UCP3, expressed in both skeletal muscle and BAT, in thermoregulatory physiology is less well understood. Here, we show that mice lacking UCP3 (UCP3KO) have impaired sympathomimetic (methamphetamine) and completely abrogated lipopolysaccharide (LPS) thermogenesis, but a normal response to norepinephrine. By comparison, UCP1 knockout (UCP1KO) mice exhibit blunted methamphetamine and fully inhibited norepinephrine thermogenesis, but an increased febrile response to LPS...
September 20, 2016: Journal of Physiology
Matthias Kröz, Marcus Reif, Danilo Pranga, Roland Zerm, Friedemann Schad, Erik Wim Baars, Matthias Girke
The concept of autonomic regulation (aR) reflects the relevance of the function of different autonomic systems for health. aR can be captured by questionnaires. We differentiate between a trait or constitutional aR questionnaire version including 12 (short-version) or 18 items, respectively, with three subscales (orthostatic-circulatory, rest/activity and digestive regulation), and an 18-item state aR questionnaire on the preceding week with four subscales (rest/activity, orthostatic-circulatory, thermo- and digestive regulation)...
September 2016: Journal of Integrative Medicine
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