Selected Contribution: Ambient temperature for experiments in rats: a new method for determining the zone of thermal neutrality

2002 ◽  
Vol 92 (6) ◽  
pp. 2667-2679 ◽  
Author(s):  
Andrej A. Romanovsky ◽  
Andrei I. Ivanov ◽  
Yury P. Shimansky
Keyword(s):  
Ambient Temperature ◽  
Body Core Temperature ◽  
Body Parts ◽  
Experimental Conditions ◽  
Strong Negative Correlation ◽  
Liquid Crystal Thermography ◽  
Body Core ◽  
Definition Of ◽  
Operational Range ◽  
Rat Tail

There is a misbelief that the same animal has the same thermoneutral zone (TNZ) in different experimental setups. In reality, TNZ strongly depends on the physical environment and varies widely across setups. Current methods for determining TNZ require elaborate equipment and can be applied only to a limited set of experimental conditions. A new, broadly applicable approach that rapidly determines whether given conditions are neutral for a given animal is needed. Consistent with the definition of TNZ [the range of ambient temperature (Ta) at which body core temperature (Tc) regulation is achieved only by control of sensible heat loss], we propose three criteria of thermoneutrality: 1) the presence of high-magnitude fluctuations in skin temperature (Tsk) of body parts serving as specialized heat exchangers with the environment (e.g., rat tail), 2) the closeness of Tsk to the median of its operational range, and 3) a strong negative correlation between Tskand Tc. Thermocouple thermometry and liquid crystal thermography were performed in five rat strains at 13 Ta. Under the conditions tested (no bedding or filter tops, no group thermoregulation), the Ta range of 29.5–30.5°C satisfied all three TNZ criteria in Wistar, BDIX, Long-Evans, and Zucker lean rats; Zucker fatty rats had a slightly lower TNZ (28.0–29.0°C). Skin thermometry or thermography is a definition-based, simple, and inexpensive technique to determine whether experimental or housing conditions are neutral, subneutral, or supraneutral for a given animal.

Thermogenesis during rest and exercise in cold air

1995 ◽  
Vol 73 (8) ◽  
pp. 1149-1153 ◽  
Author(s):  
Vincent J. Paolone ◽  
Albert M. Paolone
Keyword(s):  
Body Temperature ◽  
Heat Production ◽  
Water Vapor Pressure ◽  
Body Core Temperature ◽  
Adrenergic Blockade ◽  
Nonshivering Thermogenesis ◽  
Experimental Conditions ◽  
Mean Body Temperature ◽  
Body Core ◽  
Rest And Exercise

Nine non-cold-acclimated subjects (5 female, 4 male, mean age 22.5 years) were studied to determine whether nonshivering thermogenesis contributes to cold-induced metabolic heat production during rest (50 min standing) and exercise (40 min treadmill walking) in 5 °C. Propranolol was administered orally (females, 60 mg, 1.12 mg∙kg−1; males, 80 mg, 0.96 mg∙kg−1) to block nonshivering thermogenesis. Measurements were taken at both 25 °C, 13.1 Torr (water vapor pressure; 1 Torr = 133.3 Pa) and 5 °C, 3.6 Torr, with sessions randomly assigned to be drug–neutral (DN), drug–cold (DC), placebo–neutral (PN), and placebo–cold (PC). Body core temperature was not different between any of the experimental conditions. Mean body temperature (5 °C, 32.2 ± 0.20 °C (±SEM); 25 °C, 35.3 ± 0.20 °C) and mean skin temperature (5 °C, 22.4 ± 0.70 °C; 25 °C, 31.4 ± 0.60 °C) were lower (p < 0.05) in the 5 °C than 25 °C environment (rest, exercise, drug (D), placebo (P), combined); while shivering (EMG) was higher (16.5 ± 3.9% above baseline) at 5 °C than 25 °C (15 ± 2.1% below baseline) (p < 0.05). The greater [Formula: see text] in 5 °C compared with 25 °C for the same condition is the thermoregulatory [Formula: see text]. [Formula: see text] (mL∙min−1) was lower (p < 0.05) on the D [Formula: see text] than on the P [Formula: see text] during rest and during exercise (D, 206.1 ± 63.7; P, 338.4 ± 46.7). The EMG was 21% above baseline in the DC, and 12% above baseline for PC (p > 0.05). These results suggest a nonshivering component to heat production during acute cold exposure, which can be blocked with propranolol.Key words: nonshivering thermogenesis, propranolol, β-adrenergic blockade, body temperature, exercise, shivering.

Influence of pregnancy on the febrile response to ICV administration of PGE1 in rats studied in a thermocline

1997 ◽  
Vol 82 (5) ◽  
pp. 1453-1458 ◽  
Author(s):  
Heather L. Eliason ◽  
James E. Fewell
Keyword(s):  
Ambient Temperature ◽  
Body Core Temperature ◽  
Prostaglandin E ◽  
Thermoregulatory Response ◽  
Febrile Response ◽  
Pregnant Rats ◽  
Thermoneutral Zone ◽  
Brown Adipose ◽  
Body Core ◽  
Near Term

Eliason, Heather L., and James E. Fewell. Influence of pregnancy on the febrile response to ICV administration of PGE1 in rats studied in a thermocline. J. Appl. Physiol. 82(5): 1453–1458, 1997.—Rats near term of pregnancy have an attenuated febrile response to intracerebroventricular (ICV) injection of prostaglandin E1(PGE1) when they are studied at an ambient temperature below their thermoneutral zone. Given that nonshivering thermogenesis in brown adipose tissue is impaired in rodents near term of pregnancy, it is possible that the attenuated febrile response is forced by impairment of this component of the autonomic thermoregulatory response. If this were the case, then near-term pregnant rats should develop a “normal” fever after PGE1 administration if they were studied in a thermocline where they could utilize behavioral as well as autonomic thermoregulatory effectors to increase their body core temperature (Tbc). Experiments were, therefore, carried out on 13 nonpregnant and 14 pregnant chronically instrumented rats in a thermocline (temperature gradient 10–40°C) to investigate their Tbc responses to ICV injection of PGE1. ICV injection of 0.2 μg PGE1 produced significant increases in Tbc and fever index in both nonpregnant and pregnant animals ( day 19 of gestation); the increases, however, were significantly attenuated in the pregnant compared with the nonpregnant rats. Behavioral (e.g., selected ambient temperature) and autonomic (e.g., oxygen consumption) thermoregulatory effectors were activated to increase Tbc after ICV PGE1 in both groups of animals, but the duration of activation was shortened in pregnant compared with nonpregnant rats. The abbreviated thermoregulatory effector responses and the resulting attenuated febrile response to PGE1 in the pregnant rats may have resulted from a pregnancy-related activation of an endogenous antipyretic system.

scholarly journals Evaluation of Three Formulations of Essential Oils in Broiler Chickens under Cyclic Heat Stress

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1084
Author(s):  
Jared Ruff ◽  
Guillermo Tellez ◽  
Aaron J. Forga ◽  
Roberto Señas-Cuesta ◽  
Christine N. Vuong ◽  
...  
Keyword(s):  
Heat Stress ◽  
Essential Oils ◽  
Broiler Chickens ◽  
Bone Mineralization ◽  
Body Core Temperature ◽  
Control Group ◽  
Group 4 ◽  
Body Core ◽  
Cyclic Heat ◽  
Group 2

The objective of the present research was to assess the dietary supplementation of three formulations of essential oils (EO) in chickens under heat stress (HS). Day-of-hatch Cobb 500 chicks (n = 500) were randomly distributed into four groups: 1. HS control + control diets; 2. HS + control diets supplemented with 37 ppm EO of Lippia origanoides (LO); 3. HS + control diets supplemented with 45 ppm LO + 45 ppm EO of Rosmarinus officinalis (RO) + 300 ppm red beetroot; 4. HS + 45 ppm LO + 45 ppm RO + 300 ppm natural betaine. Chickens that received the EO showed significant (p < 0.05) improvement on BW, BWG, FI, and FCR compared to control HS chickens. Average body core temperature in group 3 and group 4 was significantly (p < 0.05) reduced compared with the HS control group and group 2. Experimental groups showed a significant reduction in FITC-d at 42 days, a significant increase in SOD at both days but a significant reduction of IFN-γ and IgA compared with HS control (p < 0.05). Bone mineralization was significantly improved by EO treatments (p < 0.05). Together these data suggest that supplemental dietary EO may reduce the harmful effects of HS.

scholarly journals COVID-19 global pandemic planning: Dry heat incubation and ambient temperature fail to consistently inactivate SARS-CoV-2 on N95 respirators

2020 ◽  
pp. 153537022097781
Author(s):  
Douglas J Perkins ◽  
Robert A Nofchissey ◽  
Chunyan Ye ◽  
Nathan Donart ◽  
Alison Kell ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Personal Protective Equipment ◽  
Healthcare Personnel ◽  
Protective Equipment ◽  
Experimental Conditions ◽  
Dry Heat ◽  
Global Pandemic ◽  
Individual Site ◽  
Pandemic Planning ◽  
N95 Respirators

The ongoing pandemic of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has placed a substantial strain on the supply of personal protective equipment, particularly the availability of N95 respirators for frontline healthcare personnel. These shortages have led to the creation of protocols to disinfect and reuse potentially contaminated personal protective equipment. A simple and inexpensive decontamination procedure that does not rely on the use of consumable supplies is dry heat incubation. Although reprocessing with this method has been shown to maintain the integrity of N95 respirators after multiple decontamination procedures, information on the ability of dry heat incubation to inactivate SARS-CoV-2 is largely unreported. Here, we show that dry heat incubation does not consistently inactivate SARS-CoV-2-contaminated N95 respirators, and that variation in experimental conditions can dramatically affect viability of the virus. Furthermore, we show that SARS-CoV-2 can survive on N95 respirators that remain at room temperature for at least five days. Collectively, our findings demonstrate that dry heat incubation procedures and ambient temperature for five days are not viable methods for inactivating SARS-CoV-2 on N95 respirators for potential reuse. We recommend that decontamination procedures being considered for the reuse of N95 respirators be validated at each individual site and that validation of the process must be thoroughly conducted using a defined protocol.

The recommended Threshold Limit Values for heat exposure fail to maintain body core temperature within safe limits in older working adults

2017 ◽  
Vol 14 (9) ◽  
pp. 703-711 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Robert D. Meade ◽  
Andrew W. D'Souza ◽  
Andreas D. Flouris ◽  
Stephen G. Hardcastle ◽  
...  
Keyword(s):  
Core Temperature ◽  
Heat Exposure ◽  
Body Core Temperature ◽  
Limit Values ◽  
Threshold Limit Values ◽  
Working Adults ◽  
Threshold Limit ◽  
Body Core ◽  
Safe Limits

Desaturation of exhaled air in camels

1981 ◽  
Vol 211 (1184) ◽  
pp. 305-319 ◽  
Keyword(s):  
Drinking Water ◽  
Heat Exchange ◽  
Body Temperature ◽  
Water Vapour ◽  
Mechanical Model ◽  
Ambient Air ◽  
Body Core Temperature ◽  
Hygroscopic Properties ◽  
Exhaled Air ◽  
Body Core

We have found that camels can reduce the water loss due to evaporation from the respiratory tract in two ways: (1) by decreasing the temperature of the exhaled air and (2) by removal of water vapour from this air, resulting in the exhalation of air at less than 100% relative humidity (r. h.). Camels were kept under desert conditions and deprived of drinking water. In the daytime the exhaled air was at or near body core temperature, while in the cooler night exhaled air was at or near ambient air temperature. In the daytime the exhaled air was fully saturated, but at night its humidity might fall to approximately 75% r. h. The combination of cooling and desaturation can provide a saving of water of 60% relative to exhalation of saturated air at body temperature. The mechanism responsible for cooling of the exhaled air is a simple heat exchange between the respiratory air and the surfaces of the nasal passageways. On inhalation these surfaces are cooled by the air passing over them, and on exhalation heat from the exhaled air is given off to these cooler surfaces. The mechanism responsible for desaturation of the air appears to depend on the hygroscopic properties of the nasal surfaces when the camel is dehydrated. The surfaces give off water vapour during inhalation and take up water from the respiratory air during exhalation. We have used a simple mechanical model to demonstrate the effectiveness of this mechanism.

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