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3.
Curr Sports Med Rep ; 19(4): 142-145, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32282459

RESUMEN

Exercising in hot, humid temperatures increases the risk for heat-related illnesses, ranging from mild heat edema to severe heat stroke. With increasing globalization in the world of sports, athletes are sometimes expected to compete in unforgiving conditions that expose them to these risks. In an effort to improve exercise capacity and reduce the risk of serious heat injury, many athletes are recommended to undergo heat acclimatization program prior to competing in climates with elevated average temperature. This article will look at current recommendations as well as studies on differing techniques for acclimatization and acclimation, with hopes to provide guidance for the modern-day clinician and athletes.


Asunto(s)
Aclimatación , Regulación de la Temperatura Corporal , Ejercicio Físico , Calor , Atletas , Humanos , Deportes
4.
Sci Total Environ ; 718: 137380, 2020 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-32325625

RESUMEN

Impacts of large-scale oil spills on avian species are far-reaching. While media attention often focuses on lethal impacts, sub-lethal effects and the impacts of rehabilitation receive less attention. The objective of our study was to characterize effects of moderate external oiling and subsequent rehabilitation on feather structure and thermoregulation in gulls. We captured 30 wild ring-billed gulls (Larus delawarensis) and randomly assigned each individual to an experimental group: 1) controls, 2) rehabilitated birds (externally oiled, rehabilitated by washing), or 3) oiled birds (externally oiled, not rehabilitated). We externally oiled birds with weathered MC252 Deepwater Horizon oil (water for controls) and collected feathers and thermography imagery (FLIR) approximately weekly for four weeks to investigate feather structure (quantified using a barbule clumping index) and thermoregulatory ability (characterized by internal body temperature and external surface temperature). Post-oiling feather clumping was significantly higher in oiled and rehabilitated birds compared to controls, but steadily declined over time in both groups. However, feather microstructure in rehabilitated birds was indistinguishable from controls within three weeks of washing whereas the feathers of oiled birds were still significantly clumped a month post oiling. Internal body temperatures didn't differ in any of the groups, suggesting birds maintain thermoregulatory homeostasis in spite of moderate external oiling. External temperatures for rehabilitated birds didn't differ from controls within a week of rehabilitation. Overall, rehabilitation procedures were effective and washed birds were in better condition compared to non-rehabilitated, oiled birds. This study provides evidence that the benefits of rehabilitation for moderately oiled birds likely outweigh the costs with regard to feather structure and thermoregulation. While feather preening and time were insufficient to reestablish baseline fine scale feather structure in moderately oiled birds, the significant clumping reduction over time may indicate that rehabilitation of lightly oiled birds may not be necessary and deserves further study.


Asunto(s)
Charadriiformes , Petróleo , Animales , Regulación de la Temperatura Corporal , Plumas , Contaminación por Petróleo
5.
Oecologia ; 193(1): 225-235, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32296953

RESUMEN

During hot weather, terrestrial animals often seek shaded thermal refugia. However, this can result in missed foraging opportunities, loss of body condition and impaired parental care. We investigated whether such costs could compromise breeding success in a widespread southern African bird: the Southern Yellow-Billed Hornbill Tockus leucomelas. We predicted that hornbills might be especially vulnerable to temperature-dependant reductions in parents' foraging capacity due to extreme asymmetry in sex-specific roles during breeding: females are confined within the nest cavity for most of the nesting period and the burden of provisioning falls solely on the male during this time. We followed 50 hornbill nesting attempts in the Kalahari Desert between 2012 and 2015, collecting data on provisioning rates, adult and nestling body mass, fledging success and size of fledglings. Mean daily maximum air temperatures (Tmax) during nesting attempts ranged from 33.2 to 39.1 °C. The likelihood of successful fledging fell below 50% at mean Tmax > 35.1 °C; a threshold now regularly exceeded at our study site due to recent climate warming. Additionally, offspring fledging following the hottest nesting attempts were > 50% lighter than those fledging following the coolest. Sublethal costs of keeping cool including loss of body condition, production of poor-quality offspring and breeding failure are likely to become issues of serious conservation concern as climate change progresses; even for currently widespread species. Missed-opportunity costs associated with behavioral thermoregulation and direct sublethal costs of temperature exposure should not be overlooked as a potential threat to populations, especially in environments that are already hot.


Asunto(s)
Aves , Calor , Animales , Regulación de la Temperatura Corporal , Cruzamiento , Femenino , Masculino , Comportamiento de Nidificación , Temperatura
6.
Oecologia ; 192(4): 919-928, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32166391

RESUMEN

Edible dormice (Glis glis) can remain entirely solitary but frequently share sleeping sites with conspecifics in groups of up to 16 adults and yearlings. Here, we analysed grouping behaviour of 4564 marked individuals, captured in a 13-year study in nest boxes in a deciduous forest. We aimed to clarify (i) whether social thermoregulation is the primary cause for group formation and (ii) which factors affect group size and composition. Dormice temporarily formed both mixed and single-sex groups in response to acute cold ambient temperatures, especially those individuals with small body mass. Thus, thermoregulatory huddling appears to be the driving force for group formation in this species. Huddling was avoided-except for conditions of severe cold load-in years of full mast seeding, which is associated with reproduction and high foraging activity. Almost all females remained solitary during reproduction and lactation. Hence, entire populations of dormice switched between predominantly solitary lives in reproductive years to social behaviour in non-reproductive years. Non-social behaviour pointed to costs of huddling in terms of competition for local food resources even when food is generally abundant. The impact of competition was mitigated by a sex ratio that was biased towards males, which avoids sharing of food resources with related females that have extremely high energy demands during lactation. Importantly, dormice preferentially huddled in male-biased groups with litter mates from previous years. The fraction of related individuals increased with group size. Hence, group composition partly offsets the costs of shared food resources via indirect fitness benefits.


Asunto(s)
Myoxidae , Animales , Regulación de la Temperatura Corporal , Femenino , Caballos , Masculino , Reproducción , Conducta Social
7.
Pediatrics ; 145(4)2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32193210

RESUMEN

OBJECTIVES: Reduce postoperative hypothermia by up to 50% over a 12-month period in children's hospital NICUs and identify specific clinical practices that impact success. METHODS: Literature review, expert opinion, and benchmarking were used to develop clinical practice recommendations for maintaining perioperative euthermia that included the following: established euthermia before transport to the operating room (OR), standardized practice for maintaining euthermia on transport to and from the OR, and standardized practice to prevent intraoperative heat loss. Process measures were focused on maintaining euthermia during these time points. The outcome measure was the proportion of patients with postoperative hypothermia (temperature ≤36°C within 30 minutes of a return to the NICU or at the completion of a procedure in the NICU). Balancing measures were the proportion of patients with postoperative temperature >38°C or the presence of thermal burns. Multivariable logistic regression was used to identify key practices that improved outcome. RESULTS: Postoperative hypothermia decreased by 48%, from a baseline of 20.3% (January 2011 to September 2013) to 10.5% by June 2015. Strategies associated with decreased hypothermia include >90% compliance with patient euthermia (36.1-37.9°C) at times of OR arrival (odds ratio: 0.58; 95% confidence interval [CI]: 0.43-0.79; P < .001) and OR departure (odds ratio: 0.0.73; 95% CI: 0.56-0.95; P = .017) and prewarming the OR ambient temperature to >74°F (odds ratio: 0.78; 95% CI: 0.62-0.999; P = .05). Hyperthermia increased from a baseline of 1.1% to 2.2% during the project. No thermal burns were reported. CONCLUSIONS: Reducing postoperative hypothermia is possible. Key practices include prewarming the OR and compliance with strategies to maintain euthermia at select time points throughout the perioperative period.


Asunto(s)
Hipotermia/prevención & control , Atención Perioperativa/métodos , Complicaciones Posoperatorias/prevención & control , Benchmarking , Temperatura Corporal/fisiología , Regulación de la Temperatura Corporal/fisiología , Quemaduras/epidemiología , Humanos , Hipotermia/epidemiología , Lactante , Unidades de Cuidado Intensivo Neonatal , Modelos Logísticos , Oportunidad Relativa , Quirófanos , Evaluación de Resultado en la Atención de Salud , Periodo Perioperatorio , Complicaciones Posoperatorias/epidemiología , Desarrollo de Programa , Factores de Tiempo , Transporte de Pacientes
8.
Int J Biometeorol ; 64(7): 1221-1231, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32193595

RESUMEN

Seasonal variations in day length and light intensity can affect the circadian rhythm as well as some characteristics of temperature regulation. We investigated characteristics of autonomic (ATR), behavioural (BTR) and nocturnal (NTR) temperature regulation during spring and autumn. Eleven participants underwent experiments in both seasons. To assess ATR, participants performed a 30-min bout of submaximal upright exercise on a cycle ergometer, followed by 100 min of water immersion (28 °C). Thresholds for the onset of shivering and sweating and vasomotor response were measured. BTR was assessed using a water-perfused suit, with participants regulating the water-perfused suit temperature (Twps) within a range, considered as thermally comfortable. The Twps changed in a saw-tooth manner from 10 to 50 °C; by depressing a switch, the direction of the Twps changed, and this limit defined the thermal comfort zone (TCZ) for each participant. A 24-h proximal (calf)-distal (toe) skin temperature gradient (∆Tc-t) was measured to assess NTR. Initiation of vasomotor tone, shivering and sweating was similar between trials. Width of the TCZ was 8.1 °C in spring and 8.6 °C in autumn (p = 0.1), with similar upper and lower regulated temperatures. ∆Tc-t exhibited a typical circadian rhythm with no difference between seasons. Minor changes in skin temperature and oxygen consumption (p Ë‚ 0.05) between the seasons may indicate a degree of seasonal adaptation over the course of winter and summer, which persisted in spring and autumn. Other factors, such as country, race, sex and age could however modify the outcome of the study.


Asunto(s)
Regulación de la Temperatura Corporal , Temperatura Cutánea , Humanos , Estaciones del Año , Sudoración , Temperatura
9.
PLoS Med ; 17(3): e1003040, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32134952

RESUMEN

BACKGROUND: Electrocardiographic QT interval prolongation is the most widely used risk marker for ventricular arrhythmia potential and thus an important component of drug cardiotoxicity assessments. Several antimalarial medicines are associated with QT interval prolongation. However, interpretation of electrocardiographic changes is confounded by the coincidence of peak antimalarial drug concentrations with recovery from malaria. We therefore reviewed all available data to characterise the effects of malaria disease and demographic factors on the QT interval in order to improve assessment of electrocardiographic changes in the treatment and prevention of malaria. METHODS AND FINDINGS: We conducted a systematic review and meta-analysis of individual patient data. We searched clinical bibliographic databases (last on August 21, 2017) for studies of the quinoline and structurally related antimalarials for malaria-related indications in human participants in which electrocardiograms were systematically recorded. Unpublished studies were identified by the World Health Organization (WHO) Evidence Review Group (ERG) on the Cardiotoxicity of Antimalarials. Risk of bias was assessed using the Pharmacoepidemiological Research on Outcomes of Therapeutics by a European Consortium (PROTECT) checklist for adverse drug events. Bayesian hierarchical multivariable regression with generalised additive models was used to investigate the effects of malaria and demographic factors on the pretreatment QT interval. The meta-analysis included 10,452 individuals (9,778 malaria patients, including 343 with severe disease, and 674 healthy participants) from 43 studies. 7,170 (68.6%) had fever (body temperature ≥ 37.5°C), and none developed ventricular arrhythmia after antimalarial treatment. Compared to healthy participants, patients with uncomplicated falciparum malaria had shorter QT intervals (-61.77 milliseconds; 95% credible interval [CI]: -80.71 to -42.83) and increased sensitivity of the QT interval to heart rate changes. These effects were greater in severe malaria (-110.89 milliseconds; 95% CI: -140.38 to -81.25). Body temperature was associated independently with clinically significant QT shortening of 2.80 milliseconds (95% CI: -3.17 to -2.42) per 1°C increase. Study limitations include that it was not possible to assess the effect of other factors that may affect the QT interval but are not consistently collected in malaria clinical trials. CONCLUSIONS: Adjustment for malaria and fever-recovery-related QT lengthening is necessary to avoid misattributing malaria-disease-related QT changes to antimalarial drug effects. This would improve risk assessments of antimalarial-related cardiotoxicity in clinical research and practice. Similar adjustments may be indicated for other febrile illnesses for which QT-interval-prolonging medications are important therapeutic options.


Asunto(s)
Arritmias Cardíacas/fisiopatología , Electrocardiografía , Sistema de Conducción Cardíaco/fisiopatología , Frecuencia Cardíaca , Malaria/fisiopatología , Potenciales de Acción , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Antimaláricos/efectos adversos , Arritmias Cardíacas/inducido químicamente , Arritmias Cardíacas/diagnóstico por imagen , Arritmias Cardíacas/parasitología , Regulación de la Temperatura Corporal , Cardiotoxicidad , Niño , Preescolar , Femenino , Sistema de Conducción Cardíaco/efectos de los fármacos , Sistema de Conducción Cardíaco/parasitología , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Lactante , Malaria/diagnóstico , Malaria/tratamiento farmacológico , Malaria/parasitología , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Medición de Riesgo , Factores de Riesgo , Índice de Severidad de la Enfermedad , Resultado del Tratamiento , Adulto Joven
10.
Int J Biometeorol ; 64(3): 485-499, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32016640

RESUMEN

Evaporative cooling is the critical heat dissipation mechanism for working individuals wearing thermal protective clothing in hot environments. However, until now, there is no knowledge on garment size design for evaporative cooling optimization, especially when the human body is in movements. In this study, to understand the dynamic effect of garment size on evaporative cooling, we performed experiments on a sweating thermal manikin with seven garment sizes and three walking speeds. The evaporative cooling of global and local manikin body with this wide range garment sizes was present. Results demonstrated that the effect of garment size on evaporative cooling depended on the walking speed. At lower walking speeds, the global evaporative cooling tended to decrease with greater garment size, while at higher walking speeds, the global evaporative cooling tended to increase with greater garment size. Similarly, according to effects of garment size on local evaporative cooling, body segments could be divided into three categories for evaporative cooling optimization. Further, we analyzed factors which influenced the positive effect of walking speed on the evaporative cooling. Results showed that, for most cases, the increase of evaporative cooling caused by walking showed positive linear relationship with the garment size. Further increase of walking speed led to a greater increase rate of evaporative heat loss for body segments with the small air gap. This study provides insights into clothing local characteristics of evaporative cooling with different garment sizes under dynamic conditions and may help clothing design to optimize the evaporative cooling of working individuals in hot environments.


Asunto(s)
Maniquíes , Caminata , Regulación de la Temperatura Corporal , Calor , Humanos , Ropa de Protección , Sudoración
12.
Animal ; 14(S1): s124-s132, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32024577

RESUMEN

Ruminants living in seasonal environments face a two-fold challenge during winter. The energetic cost of maintaining a high body temperature is higher at lower ambient temperatures, and this is compounded by poor availability and quality of feed. Wild ruminants acclimatize to this energetic challenge by hypothermia, that is, reduced endogenous heat production and abandoning the maintenance of a high body temperature, particularly in peripheral body parts. Further but lesser contributions to lower energy expenditure during winter are reduced foraging activity; lower heat increment of feeding; and reduced maintenance cost of size-reduced organs. Altogether, metabolic rate, estimated by the continuous measurement of heart rate, during winter is downregulated to more than half of the summer level, as is voluntary food intake, even in animals fed ad libitum. The transformation from the summer into the thrifty winter phenotype is also evident in the physiology of digestion. Microbial protein synthesis is less facilitated by diminished phosphorus secretion into the shrunk rumen during winter. In line with this result, the concentration of ammonia, the end-product of protein digestion in the rumen, peaks in rumen liquid in spring, whereas the molar proportion of acetate, an indicator of fermentation of a diet rich in fiber, peaks in winter. In contrast to reduced stimulation of growth of ruminal microbes during winter, active transport of nutrients across the intestinal epithelium is increased, resulting in more efficient exploitation of the lower amount and quality of ingested winter feed. Nevertheless, the energy balance remains negative during winter. This is compensated by using fat reserves accumulated during summer, which become a major metabolic fuel during winter.


Asunto(s)
Regulación de la Temperatura Corporal , Fibras de la Dieta/metabolismo , Ingestión de Alimentos , Metabolismo Energético , Rumiantes/fisiología , Aclimatación , Amoníaco/metabolismo , Alimentación Animal , Animales , Digestión , Fermentación , Calor , Rumen/metabolismo , Estaciones del Año , Termogénesis
13.
J Anim Sci ; 98(3)2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-32020198

RESUMEN

Feed consumption increases body temperature and may delay a return to euthermia and exacerbate intestinal injury following acute hyperthermia recovery in pigs. Therefore, the study objective was to evaluate the effects of feed removal on body temperature and intestinal morphology in pigs exposed to acute hyperthermia and then rapidly cooled. Twenty-four gilts (78.53 ± 5.46 kg) were exposed to thermoneutral (TN; n = 12 pigs; 21.21 ± 0.31 °C; 61.88 ± 6.93% RH) conditions for 6 h, or heat stress (HS; 38.51 ± 0.60 °C; 36.38 ± 3.40% RH) conditions for 3 h followed by a 3-h recovery period of rapid cooling (HSC;n = 12 pigs; TN conditions and cold water dousing). Within each recovery treatment, one-half of the pigs were provided feed ad libitum (AF; n = 6 pigs per recovery treatment) and one-half of the pigs were not provided feed (NF; n = 6 pigs per recovery treatment). Gastrointestinal (TGI), vaginal (TV), and skin (TSK) temperatures and respiration rate (RR) were recorded every 15 min. Pigs were video-recorded to assess feeding and drinking attempts. Immediately following the 6-h thermal stress period, pigs were euthanized, and intestinal samples were collected to assess morphology. During the HS period, Tv, TGI, TSK, and RR were increased (P < 0.01; 1.63, 2.05, 8.32 °C, and 88 breaths per min, respectively) in HSC vs. TN pigs, regardless of feeding treatment. Gastrointestinal temperature was greater (P = 0.03; 0.97 °C) in HSC + AF vs. HSC + NF pigs from 45 to 180 min of the recovery period. During the recovery period, feeding attempts were greater (P = 0.02; 195.38%) in AF vs. NF pigs. No drinking attempt differences were detected with any comparison (P > 0.05). A decrease (P < 0.01) in jejunum and ileum villus height (24.72% and 26.11%, respectively) and villus height-to-crypt depth ratio (24.03% and 25.29%, respectively) was observed in HSC vs. TN pigs, regardless of feeding treatment. Ileum goblet cells were reduced (P = 0.01; 37.87%) in HSC vs. TN pigs, regardless of feeding treatment. In summary, TGI decreased more rapidly following acute hyperthermia when the feed was removed, and this may have implications toward using feed removal as a strategy to promote acute hyperthermia recovery in pigs.


Asunto(s)
Alimentación Animal/efectos adversos , Regulación de la Temperatura Corporal , Ingestión de Alimentos , Fiebre/veterinaria , Porcinos/fisiología , Animales , Temperatura Corporal , Frío , Femenino , Tracto Gastrointestinal/citología , Respuesta al Choque Térmico , Calor , Mucosa Intestinal/citología , Intestinos/citología , Frecuencia Respiratoria
14.
PLoS One ; 15(2): e0229335, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32084208

RESUMEN

Acclimation resulting from low- to moderate-intensity physical exertion in the heat induces several thermoregulatory adaptations, including slower exercise-induced increases in core body temperature. However, few studies have investigated the thermoregulatory adaptations induced by high-intensity interval training (HIIT) protocols. Thus, the present study aimed to compare the adaptations in rats' thermoregulatory parameters and aerobic performance observed after two different heat acclimation regimens consisting of HIIT protocols performed in a hot environment. Twenty-three adult male Wistar rats were initially subjected to an incremental-speed exercise at 32°C until they were fatigued and then randomly assigned to one of the following three heat acclimation strategies: passive heat exposure without any exercise (untrained controls-UN; n = 7), HIIT performed at the maximal aerobic speed (HIIT100%; n = 8) and HIIT performed at a high but submaximal speed (HIIT85%; n = 8). Following the two weeks of interventions, the rats were again subjected to a fatiguing incremental exercise at 32°C, while their colonic temperature (TCOL) was recorded. The workload performed by the rats and their thermoregulatory efficiency were calculated. After the intervention period, rats subjected to both HIIT protocols attained greater workloads (HIIT100%: 313.7 ± 21.9 J vs. HIIT85%: 318.1 ± 32.6 J vs. UN: 250.8 ± 32.4 J; p < 0.01) and presented a lower ratio between the change in TCOL and the distance travelled (HIIT100%: 4.95 ± 0.42°C/km vs. HIIT85%: 4.33 ± 0.59°C/km vs. UN: 6.14 ± 1.03°C/km; p < 0.001) when compared to UN rats. The latter finding indicates better thermoregulatory efficiency in trained animals. No differences were observed between rats subjected to the two HIIT regimens. In conclusion, the two HIIT protocols induce greater thermoregulatory adaptations and performance improvements than passive heat exposure. These adaptations do not differ between the two training protocols investigated in the present study.


Asunto(s)
Adaptación Fisiológica/fisiología , Regulación de la Temperatura Corporal/fisiología , Entrenamiento de Intervalos de Alta Intensidad/métodos , Calor , Condicionamiento Físico Animal/fisiología , Esfuerzo Físico/fisiología , Animales , Masculino , Ratas , Ratas Wistar , Factores de Tiempo
15.
BMC Evol Biol ; 20(1): 28, 2020 02 13.
Artículo en Inglés | MEDLINE | ID: mdl-32054457

RESUMEN

BACKGROUND: Temperature exerts a strong influence on protein evolution: species living in thermally distinct environments often exhibit adaptive differences in protein structure and function. However, previous research on protein temperature adaptation has focused on small numbers of proteins and on proteins adapted to extreme temperatures. Consequently, less is known about the types and quantity of evolutionary change that occurs to proteins when organisms adapt to small shifts in environmental temperature. In this study, these uncertainties were addressed by developing software that enabled comparison of structural changes associated with temperature adaptation (hydrogen bonding, salt bridge formation, and amino acid use) among large numbers of proteins from warm- and cold-adapted species of marine mussels, Mytilus galloprovincialis and Mytilus trossulus, respectively. RESULTS: Small differences in habitat temperature that characterize the evolutionary history of Mytilus mussels were sufficient to cause protein structural changes consistent with temperature adaptation. Hydrogen bonds and salt bridges that increase stability and protect against heat-induced denaturation were more abundant in proteins from warm-adapted M. galloprovincialis compared with proteins from cold-adapted M. trossulus. These structural changes were related to deviations in the use of polar and charged amino acids that facilitate formation of hydrogen bonds and salt bridges within proteins, respectively. Enzymes, in particular those within antioxidant and cell death pathways, were over-represented among proteins with the most hydrogen bonds and salt bridges in warm-adapted M. galloprovincialis. Unlike extremophile proteins, temperature adaptation in Mytilus proteins did not involve substantial changes in the number of hydrophobic or large volume amino acids, nor in the content of glycine or proline. CONCLUSIONS: Small shifts in organism temperature tolerance, such as that needed to cope with climate warming, may result from structural and functional changes to a small percentage of the proteome. Proteins in which function is dependent on large conformational change, notably enzymes, may be particularly sensitive to temperature perturbation and represent foci for natural selection. Protein temperature adaptation can occur through different types and frequencies of structural change, and adaptive mechanisms used to cope with small shifts in habitat temperature appear different from mechanisms used to retain protein function at temperature extremes.


Asunto(s)
Aclimatación , Mytilus/metabolismo , Proteínas/química , Proteínas/metabolismo , Temperatura , Aclimatación/genética , Adaptación Fisiológica/fisiología , Secuencia de Aminoácidos , Animales , Regulación de la Temperatura Corporal/fisiología , Ensayos Analíticos de Alto Rendimiento/veterinaria , Calor , Enlace de Hidrógeno , Modelos Moleculares , Conformación Proteica , Procesamiento Proteico-Postraduccional/fisiología , Proteoma/química , Proteoma/metabolismo , Relación Estructura-Actividad
16.
PLoS One ; 15(1): e0227700, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31971994

RESUMEN

In vertebrates, the embryonic environment is known to affect the development and the health of individuals. In broiler chickens, the thermal-manipulation (TM) of eggs during the incubation period was shown to improve heat tolerance at slaughter age (35 days of age) in association with several modifications at the molecular, metabolic and physiological levels. However, little is known about the Japanese quail (Coturnix japonica), a closely related avian species widely used as a laboratory animal model and farmed for its meat and eggs. Here we developed and characterized a TM procedure (39.5°C and 65% relative humidity, 12 h/d, from days 0 to 13 of incubation) in quails by analyzing its short and long-term effects on zootechnical, physiological and metabolic parameters. Heat-tolerance was tested by a heat challenge (36°C for 7h) at 35 days of age. TM significantly reduced the hatching rate of the animals and increased mortality during the first four weeks of life. At hatching, TM animals were heavier than controls, but lighter at 25 days of age for both sexes. Thirty-five days after hatching, TM decreased the surface temperature of the shank in females, suggesting a modulation of the blood flow to maintain the internal temperature. TM also increased blood partial pressure and oxygen saturation percentage at 35 days of age in females, suggesting a long-term modulation of the respiration physiology. Quails physiologically responded to the heat challenge, with a modification of several hematologic and metabolic parameters, including an increase in plasma corticosterone concentration. Several physiological parameters such as beak surface temperature and blood sodium concentration revealed that TM birds responded differently to the heat challenge compared to controls. Altogether, this first comprehensive characterization of TM in Japanese quail showed durable effects that may affect the response of TM quails to heat.


Asunto(s)
Regulación de la Temperatura Corporal/fisiología , Coturnix/embriología , Animales , Antioxidantes/metabolismo , Embrión de Pollo , Pollos/crecimiento & desarrollo , Pollos/fisiología , Coturnix/crecimiento & desarrollo , Coturnix/fisiología , Desarrollo Embrionario/fisiología , Femenino , Gases/sangre , Calor , Masculino , Termotolerancia/fisiología
17.
Int J Sports Med ; 41(3): 161-167, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31902130

RESUMEN

Aerobic performance is negatively impacted by tropical climate due to impairment of thermoregulatory mechanisms. We tested the hypothesis that a torso application of a 4% menthol solution would have the same effect on a best performance 10-km run as an external use of cold water. Thirteen trained male athletes completed four outdoor 10-km runs (T=29.0±1.3°C, relative humidity 59.0±13.6%) wearing a tee-shirt soaked every 2-km either in a cold (~6°C) or warm/ambient (~28°C) solution, consisting in water or in a 4% menthol solution, (CTL, MENT-Amb, CLD and MENT-CLD). Run performances were improved from 4.8 to 6.1% in CLD (51.4±5.5 min), MENT-Amb (52.2±5.9 min) and MENT-CLD (51.4±5.1 min) conditions (vs. CTL, 55.4±8.4 min, P<0.05), without differences between these three conditions, whereas heart rate (177±13bpm), body temperature (38.7±0.6°C) and drink ingestion (356±170 g) were not modified. Thermal sensation after running was lower in MENT-CLD (vs. CTL, P<0.01) and thermal acceptability was higher in CLD and MENT-Amb (vs. CTL, P<0.05), but thermal comfort, feeling scale and rate of perceived exertion remained unchanged. The use of menthol on skin enhances aerobic performance in a tropical climate, and no differences in performance were observed between menthol and traditional percooling strategies. However, combining both menthol and traditional percooling brought no further improvements.


Asunto(s)
Rendimiento Atlético/fisiología , Regulación de la Temperatura Corporal/efectos de los fármacos , Humedad , Mentol/administración & dosificación , Carrera/fisiología , Clima Tropical , Administración Cutánea , Adulto , Ingestión de Líquidos , Marcha/fisiología , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Percepción/fisiología , Esfuerzo Físico/fisiología , Pérdida de Peso/fisiología , Adulto Joven
18.
Proc Natl Acad Sci U S A ; 117(3): 1566-1572, 2020 01 21.
Artículo en Inglés | MEDLINE | ID: mdl-31919285

RESUMEN

While surface microstructures of butterfly wings have been extensively studied for their structural coloration or optical properties within the visible spectrum, their properties in infrared wavelengths with potential ties to thermoregulation are relatively unknown. The midinfrared wavelengths of 7.5 to 14 µm are particularly important for radiative heat transfer in the ambient environment, because of the overlap with the atmospheric transmission window. For instance, a high midinfrared emissivity can facilitate surface cooling, whereas a low midinfrared emissivity can minimize heat loss to surroundings. Here we find that the midinfrared emissivity of butterfly wings from warmer climates such as Archaeoprepona demophoon (Oaxaca, Mexico) and Heliconius sara (Pichincha, Ecuador) is up to 2 times higher than that of butterfly wings from cooler climates such as Celastrina echo (Colorado) and Limenitis arthemis (Florida), using Fourier-transform infrared (FTIR) spectroscopy and infrared thermography. Our optical computations using a unit cell approach reproduce the spectroscopy data and explain how periodic microstructures play a critical role in the midinfrared. The emissivity spectrum governs the temperature of butterfly wings, and we demonstrate that C. echo wings heat up to 8 °C more than A. demophoon wings under the same sunlight in the clear sky of Irvine, CA. Furthermore, our thermal computations show that butterfly wings in their respective habitats can maintain a moderate temperature range through a balance of solar absorption and infrared emission. These findings suggest that the surface microstructures of butterfly wings potentially contribute to thermoregulation and provide an insight into butterflies' survival.


Asunto(s)
Regulación de la Temperatura Corporal/fisiología , Mariposas Diurnas/fisiología , Rayos Infrarrojos , Alas de Animales/fisiología , Animales , Colorado , Biología Computacional , Ecosistema , Ecuador , Florida , México , Modelos Biológicos , Fenómenos Ópticos , Análisis Espectral , Luz Solar , Temperatura , Alas de Animales/ultraestructura
19.
Annu Rev Entomol ; 65: 121-143, 2020 01 07.
Artículo en Inglés | MEDLINE | ID: mdl-31585504

RESUMEN

Although the insect circulatory system is involved in a multitude of vital physiological processes, it has gone grossly understudied. This review highlights this critical physiological system by detailing the structure and function of the circulatory organs, including the dorsal heart and the accessory pulsatile organs that supply hemolymph to the appendages. It also emphasizes how the circulatory system develops and ages and how, by means of reflex bleeding and functional integration with the immune system, it supports mechanisms for defense against predators and microbial invaders, respectively. Beyond that, this review details evolutionary trends and novelties associated with this system, as well as the ways in which this system also plays critical roles in thermoregulation and tracheal ventilation in high-performance fliers. Finally, this review highlights how novel discoveries could be harnessed for the control of vector-borne diseases and for translational medicine, and it details principal knowledge gaps that necessitate further investigation.


Asunto(s)
Insectos/fisiología , Envejecimiento/fisiología , Animales , Evolución Biológica , Regulación de la Temperatura Corporal , Sistema Cardiovascular , Hemolinfa/fisiología , Sistema Inmunológico , Insectos/anatomía & histología , Metamorfosis Biológica
20.
Int J Biometeorol ; 64(1): 105-113, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31485808

RESUMEN

The objectives of this study were to determine the main variables which act in the adaptive profile and the dynamic of the thermoregulatory responses of Sindi and Girolando dairy cows in tropical conditions using multivariate analyses as the auxiliary method. Thirty dairy cows were evaluated, in which the data were collected monthly during 12 months. Rectal temperature (RT) and respiratory rate (RR) were measured twice a day (morning and afternoon), along with meteorological variables (air temperature, relative humidity, and wind speed), and later the Black Globe and Humidity Index and Radiant Heat Load were calculated. Blood samples were collected for estimating the levels of triiodothyronine (T3), thyroxine (T4), hemoglobin concentration (HC), red blood cells (RBC), packet cell volume (PCV), mean corpuscular volume (MCV), white blood cells (WBC), glucose (GLU), cholesterol (CHO), triglycerides (TRI), creatinine (CRE), total protein (TP), urea (URE), albumin (ALB), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). The more active variables in the adaptive profile for Sindi cows were T4, PCV, RBC, WBC, TRI, CRE, HC, T3, and URE, while PCV, RBC, ALB, TP, RT, RR, URE, ALT, and AST variables were more active for Girolando cows. All animals were classified according to their corresponding group when considering all variables under study. The classification error percentage was > 40% in the Sindi cows when the physiological responses were considered, whereas an 80% success rate was observed in Girolando cows in the winter and summer seasons. The physiological responses of the dairy cows are similar in winter and distinct in summer in tropical conditions.


Asunto(s)
Regulación de la Temperatura Corporal , Calor , Animales , Bovinos , Femenino , Humedad , Lactancia , Estaciones del Año , Temperatura
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