body cooling
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2022 ◽  
Vol 104 ◽  
pp. 103174
Author(s):  
Nicole A. Coull ◽  
Simon G. Hodder ◽  
George Havenith

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260775
Author(s):  
Takahiro Ogawa ◽  
Sven P. Hoekstra ◽  
Yoshi-Ichiro Kamijo ◽  
Victoria L. Goosey-Tolfrey ◽  
Jeremy J. Walsh ◽  
...  

Brain-derived neurotrophic factor (BDNF) plays a key role in neuronal adaptations. While previous studies suggest that whole-body heating can elevate circulating BDNF concentration, this is not known for local heating protocols. This study investigated the acute effects of whole-body versus local passive heating on serum and plasma BDNF concentration. Using a water-perfused suit, ten recreationally active males underwent three 90 min experimental protocols: heating of the legs with upper-body cooling (LBH), whole-body heating (WBH) and a control condition (CON). Blood samples were collected before, immediately after and 1 h post-heating for the determination of serum and plasma BDNF concentration, platelet count as well as the BDNF release per platelet. Rectal temperature, cardiac output and femoral artery shear rate were assessed at regular intervals. Serum and plasma BDNF concentration were elevated after WBH (serum: 19.1±5.0 to 25.9±11.3 ng/ml, plasma: 2.74±0.9 to 4.58±2.0; p<0.044), but not LBH (serum: 19.1±4.7 to 22.3±4.8 ng/ml, plasma: 3.25±1.13 to 3.39±0.90 ng/ml; p>0.126), when compared with CON (serum: 18.6±6.4 to 16.8±3.4 ng/ml, plasma: 2.49±0.69 to 2.82±0.89 ng/ml); accompanied by an increase in platelet count (p<0.001). However, there was no change in BDNF content per platelet after either condition (p = 0.392). All physiological measures were elevated to a larger extent after WBH compared with LBH (p<0.001), while shear rate and rectal temperature were higher during LBH than CON (p<0.038). In conclusion, WBH but not LBH acutely elevates circulating BDNF concentration. While these findings further support the use of passive heating to elevate BDNF concentration, a larger increase in shear rate, sympathetic activity and/or rectal temperature than found after LBH appears needed to induce an acute BDNF response by passive heating.


2021 ◽  
Vol 15 ◽  
Author(s):  
Edward C. Harding ◽  
Wei Ba ◽  
Reesha Zahir ◽  
Xiao Yu ◽  
Raquel Yustos ◽  
...  

When mice are exposed to external warmth, nitric oxide synthase (NOS1) neurons in the median and medial preoptic (MnPO/MPO) hypothalamus induce sleep and concomitant body cooling. However, how these neurons regulate baseline sleep and body temperature is unknown. Using calcium photometry, we show that NOS1 neurons in MnPO/MPO are predominantly NREM and REM active, especially at the boundary of wake to NREM transitions, and in the later parts of REM bouts, with lower activity during wakefulness. In addition to releasing nitric oxide, NOS1 neurons in MnPO/MPO can release GABA, glutamate and peptides. We expressed tetanus-toxin light-chain in MnPO/MPO NOS1 cells to reduce vesicular release of transmitters. This induced changes in sleep structure: over 24 h, mice had less NREM sleep in their dark (active) phase, and more NREM sleep in their light (sleep) phase. REM sleep episodes in the dark phase were longer, and there were fewer REM transitions between other vigilance states. REM sleep had less theta power. Mice with synaptically blocked MnPO/MPO NOS1 neurons were also warmer than control mice at the dark-light transition (ZT0), as well as during the dark phase siesta (ZT16-20), where there is usually a body temperature dip. Also, at this siesta point of cooled body temperature, mice usually have more NREM, but mice with synaptically blocked MnPO/MPO NOS1 cells showed reduced NREM sleep at this time. Overall, MnPO/MPO NOS1 neurons promote both NREM and REM sleep and contribute to chronically lowering body temperature, particularly at transitions where the mice normally enter NREM sleep.


2021 ◽  
Vol 7 (3) ◽  
pp. 7-13
Author(s):  
R. S. Rakhmanov ◽  
E. S. Bogomolov ◽  
D. A. Narutdinov ◽  
S. A. Razgulin ◽  
M. V. Ashina

Aim. Assess the health risk of a cold environment by bioclimatic indices characterizing weather and climatic conditions in the Arctic zone of the Krasnoyarsk Territory.Materials and methods. The mean monthly daily ambient temperature, wind speed and relative air humidity were determined. The body cooling conditions integral index (BCCII) and the wind-cold index (WCI) were calculated.Results and their discussion. Using the BCCII from 4 to 6 months a year at Cape Chelyuskin, the critical risk of frostbite in exposed areas of the body determined at Dixon Island from 4 to 5 months a year; in July and August, the indicator values reached the lower border of the “moderate risk”. Using the WCI, an uncomfortable cold environment was determined, respectively, 2 months and 4 months, a very cold — 3 months and 2 months, and an extremely cold — 3 months and 2 months.Conclusion. The advantage of using BCCII rather than WCI is shown, since on its basis the criteria for safe working conditions in an open area are determined. To interpret the value of “no risk” while using WCI, it is necessary to know the period of the year, in which the weather and climatic conditions are assessed as a cold environment.


2021 ◽  
Vol 2071 (1) ◽  
pp. 012029
Author(s):  
S Alduwaish ◽  
O Alshakri ◽  
R Alamri ◽  
R Alfarieh ◽  
S Alqahtani ◽  
...  

Abstract Premature neonates are nursed in closed incubators to prevent transcutaneous water loss, dehydration, and excessive body cooling. These issues have serious risks that need to be eliminated by controlling the air’s relative humidity (RH) in the incubator. This paper aims to implement a closed-loop control system that maintains desired RH levels inside the incubator with an acceptable settling time and percentage. Designing the prototype is actuator-process-sensor based, and the implementation was in two main phases. First, building the incubator, which involved assembling the incubation space and the humidifier using a readily available ultrasonic piezoelectric transducer. Second, designing the control algorithm which is based on the ON/OFF algorithm with four levels of ON Humidification power. Finally, the results taken are the control system responses to a step input of desired values of relative humidity based on clinical guidance. Response results showed a maximum steady-state error of 2.5 and a minimum settling time of 0.8 min. The results indicate that the control system is fast and stable which meets the desired requirements. The designed control system is beneficial in reducing power usage and creating a safe humidification method for the infant.


Neuron ◽  
2021 ◽  
Vol 109 (20) ◽  
pp. 3283-3297.e11
Author(s):  
Gretel B. Kamm ◽  
Juan C. Boffi ◽  
Kristina Zuza ◽  
Sara Nencini ◽  
Joaquin Campos ◽  
...  

Author(s):  
Daryl Michael George Hurrie ◽  
Morteza Talebian nia ◽  
Kevin E. Power ◽  
Katinka Stecina ◽  
Phillip Gardiner ◽  
...  

Cold stress impairs fine and gross motor movements. Although peripheral effects of muscle cooling on performance are well understood, less is known about central mechanisms. This study characterized corticospinal and spinal excitability during surface cooling, reducing skin (Tsk) and core (Tes) temperature. Ten subjects (3 female) wore a liquid-perfused suit and were cooled (9°C perfusate, 90 min) and rewarmed (41°C perfusate, 30 min). Transcranial magnetic stimulation [eliciting motor evoked potentials (MEPs)], as well as transmastoid [eliciting cervicomedullary evoked potentials (CMEPs)] and brachial plexus [eliciting maximal compound motor action potentials (Mmax)] electrical stimulation, were applied at baseline, every 20 min during cooling, and following rewarming. Sixty minutes of cooling, reduced Tsk by 9.6°C (P<0.001) but Tes remained unchanged (P=0.92). Tes then decreased ~0.6℃ in the next 30 minutes of cooling (P<0.001). Eight subjects shivered. During rewarming, shivering was abolished, and Tsk returned to baseline while Tes did not increase. During cooling and rewarming, Mmax, MEP, and MEP/Mmax were unchanged from baseline. However, CMEP and CMEP/Mmax increased during cooling by ~85% and 79% (P<0.001) respectively, and remained elevated post-rewarming. Results suggest that spinal excitability is facilitated by reduced Tsk during cooling, and reduced Tes during warming, while corticospinal excitability remains unchanged. ClinicalTrials.gov ID NCT04253730 Novelty: • This is the first study to characterize corticospinal, and spinal excitability during whole body cooling, and rewarming in humans. • Whole body cooling did not affect corticospinal excitability. • Spinal excitability was facilitated during reductions in both skin and core temperatures.


2021 ◽  
Author(s):  
Sima Pirmoradi ◽  
Beth Ferguson ◽  
Gozde Goncu Berk ◽  
Katia Vega

2021 ◽  
Vol 38 (5) ◽  
pp. 261-268
Author(s):  
Pedro H. Nogueira ◽  
Alisson G. da Silva ◽  
Samuel A. Oliveira ◽  
Manuel Sillero-Quintana ◽  
João C. Marins

Objective: To analyze the body heat dissipation by thermography during indoor running treadmill with different airflow conditions. Materials and method: Nine male participants (23.0±2.5 years old) underwent three 45-minute moderate-intensity running sessions (60-70% reserve heart rate) on a treadmill. At each session, a different experimental condition was applied in a crossover design: without airflow (NF), and with low (LF) and high airflow (HF) generated by a fun. Thermograms were obtained with a thermal camera before exercise, during (every 10 minutes), and after exercise. Skin temperature (Tsk) was measured on regions of interest of the upper body: pectoral, brachial biceps, and upper back. A repeated measures ANOVA was used to compare Tsk over time and between conditions, considering p<0.05 as statistically significant. Results: In pectoral and brachial biceps, LF and HF conditions provided greater reductions in Tsk at all moments when compared to the NF (p<0.05). There was a higher reduction in Tsk to the HF vs LF in biceps at 30, 40, and 45 min during exercise (p<0.05). In the upper back, Tsk remained below baseline at all moments during exercise only in the HF condition (p<0.05). In NF and LF conditions, Tsk returned to baseline at 30 min during exercise (p>0.05). Conclusion: The frontal wind flow enhances body heat dissipation during moderate-intensity running in the pectoral, brachial biceps, and upper back, with a direct relationship of flow speed and Tsk reduction during exercise.


2021 ◽  
pp. 316-341
Author(s):  
Graham Mitchell

Measurement of giraffe body temperature has shown that it is ~38.5oC but it can vary by ~5oC over the course of a day. Body heat is derived from fermentation of browse, other metabolic processes and radiant heat. Heat loss mechanisms partly depend on body surface area. Despite their unusual shape the body surface area of giraffes is similar to that in other equivalent body mass mammals: a shorter trunk is offset by a longer neck and legs. Heat loss by radiation is constant, by conduction rare and minimal. Their long, slender legs and neck are an advantage for convective and evaporative heat loss from the skin: heat transfer is inversely proportional to the square root of diameter. Evaporation from the respiratory system occurs through the nasal mucosa, the surface area of which in giraffes is large. Cooling of the nasal mucosa and blood follows and cool blood drains in to the jugular vein and contributes to whole body cooling and cooling of the blood supplying the brain by heat exchange in the carotid rete. Similar heat exchange may occur across the surface of the ossicones. Behavior changes when ambient temperature exceeds skin temperature. Giraffes re-orientate their bodies to minimize radiant heat gain and seek shade. A unique arrangement of blood vessels supplying blood to skin patches allows patches to act as thermal windows through which heat can be lost an arrangement enhanced by evaporation: sweat gland density in the skin of patches is greater than it is elsewhere.


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