scholarly journals Revisiting the influence of individual factors on heat exchange during exercise in dry heat using direct calorimetry

2019 ◽  
Vol 104 (7) ◽  
pp. 1038-1050 ◽  
Author(s):  
Sean R. Notley ◽  
Dallon T. Lamarche ◽  
Robert D. Meade ◽  
Andreas D. Flouris ◽  
Glen P. Kenny
Keyword(s):  
Heat Exchange ◽  
Individual Factors ◽  
Direct Calorimetry ◽  
Dry Heat

scholarly journals The thermogenic effect of nesfatin-1 requires recruitment of the melanocortin system

2017 ◽  
Vol 235 (2) ◽  
pp. 111-122 ◽  
Author(s):  
Riccardo Dore ◽  
Luka Levata ◽  
Sogol Gachkar ◽  
Olaf Jöhren ◽  
Jens Mittag ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Heat Loss ◽  
Central Administration ◽  
Melanocortin System ◽  
Direct Calorimetry ◽  
Iodothyronine Deiodinase ◽  
Interscapular Brown Adipose Tissue ◽  
Peripheral Tissues ◽  
Dry Heat ◽  
Brown Adipose

Nesfatin-1 is a bioactive polypeptide expressed both in the brain and peripheral tissues and involved in the control of energy balance by reducing food intake. Central administration of nesfatin-1 significantly increases energy expenditure, as demonstrated by a higher dry heat loss; yet, the mechanisms underlying the thermogenic effect of central nesfatin-1 remain unknown. Therefore, in this study, we sought to investigate whether the increase in energy expenditure induced by nesfatin-1 is mediated by the central melanocortin pathway, which was previously reported to mediate central nesfatin-1´s effects on feeding and numerous other physiological functions. With the application of direct calorimetry, we found that intracerebroventricular nesfatin-1 (25 pmol) treatment increased dry heat loss and that this effect was fully blocked by simultaneous administration of an equimolar dose of the melanocortin 3/4 receptor antagonist, SHU9119. Interestingly, the nesfatin-1-induced increase in dry heat loss was positively correlated with body weight loss. In addition, as assessed with thermal imaging, intracerebroventricular nesfatin-1 (100 pmol) increased interscapular brown adipose tissue (iBAT) as well as tail temperature, suggesting increased heat production in the iBAT and heat dissipation over the tail surface. Finally, nesfatin-1 upregulated pro-opiomelanocortin and melanocortin 3 receptor mRNA expression in the hypothalamus, accompanied by a significant increase in iodothyronine deiodinase 2 and by a nonsignificant increase in uncoupling protein 1 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha mRNA in the iBAT. Overall, we clearly demonstrate that nesfatin-1 requires the activation of the central melanocortin system to increase iBAT thermogenesis and, in turn, overall energy expenditure.

Whole‐body Heat Exchange in Young and Middle‐Aged Men during Constant‐ and Variable‐Intensity Work of Equivalent Metabolic Demand in Dry Heat

2020 ◽  
Vol 34 (S1) ◽  
pp. 1-1
Author(s):  
Sean R. Notley ◽  
Robert D. Meade ◽  
Andrew W. D’Souza ◽  
Maura M. Rutherford ◽  
Jung-Hyun Kim ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Whole Body ◽  
Metabolic Demand ◽  
Middle Aged ◽  
Variable Intensity ◽  
Dry Heat ◽  
Body Heat

Heat exchange during upper- and lower-body exercise

1984 ◽  
Vol 57 (4) ◽  
pp. 1050-1054 ◽  
Author(s):  
M. N. Sawka ◽  
R. R. Gonzalez ◽  
L. L. Drolet ◽  
K. B. Pandolf
Keyword(s):  
Heat Exchange ◽  
Heat Loss ◽  
Dew Point ◽  
Upper Body ◽  
Evaporative Heat Loss ◽  
Lower Body ◽  
Transfer Coefficients ◽  
Cycle Exercise ◽  
Upper Body Exercise ◽  
Dry Heat

This study examined evaporative and dry heat exchange during upper- and lower-body exercise. Four male subjects performed arm-crank or cycle exercise at the same O2 uptake level (approximately 1.6 l/min) in an environment facilitating dry heat exchange [radiative and convective (R + C)] [ambient temperature (Ta) = 18 degrees C, dew-point temperature (Tdp) = 14 degrees C] and an environment facilitating evaporative heat loss (Esk) (Ta = 35 degrees C, Tdp = 14 degrees C). (R + C) was determined from the torso with a net radiometer and from the limbs with heat flow discs, whereas Esk was determined from the torso and limbs by ventilated dew-point sensors. In both environments neither esophageal temperature nor mean skin temperature were different between exercise types (P greater than 0.05). Torso (R + C) was significantly (P less than 0.05) greater during arm-crank than during cycle exercise in both environments. Torso Esk, as well as arm (R + C), and arm Esk were not different (P greater than 0.05) between exercise types in each environment. Leg (R + C) was greater (P less than 0.05) during cycle than during arm-crank exercise in the 18 degrees C environment, whereas leg Esk was greater (P less than 0.05) during cycle than during arm-crank exercise in the 35 degrees C environment. These data indicate that to compensate for greater torso sensible heat loss during upper body exercise lower body exercise elicits additional (R + C) or Esk from the legs. The avenue for this compensatory sensible and insensible heat loss depends upon the differential heat transfer coefficients which influence tissue conductivity and mass transfer.

Whole‐body heat exchange in black‐African and Caucasian men during exercise eliciting matched heat‐loss requirements in dry heat

2019 ◽  
Vol 105 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Caroline M. Muia ◽  
Sean R. Notley ◽  
Samah Saci ◽  
Andrew W. D'Souza ◽  
Glen P. Kenny
Keyword(s):  
Heat Exchange ◽  
Heat Loss ◽  
Whole Body ◽  
Black African ◽  
Dry Heat ◽  
Caucasian Men ◽  
Body Heat

A method for dynamic measurement of the resistance to dry heat exchange by footwear

1997 ◽  
Vol 28 (5-6) ◽  
pp. 383-388 ◽  
Author(s):  
Karin Bergquist ◽  
Ingvar Holmér
Keyword(s):  
Heat Exchange ◽  
Dynamic Measurement ◽  
Dry Heat

Effects of sterilization modes on the mechanical strengths of plaster of paris implants

1989 ◽  
Vol 47 ◽  
pp. 890-891
Author(s):  
K. Cowden ◽  
B. Giammara ◽  
T. Devine ◽  
J. Hanker
Keyword(s):  
Gamma Radiation ◽  
Calcium Sulfate ◽  
Significant Loss ◽  
Potassium Sulfate ◽  
Limiting Factors ◽  
Radiation Sterilization ◽  
Plaster Of Paris ◽  
Hardness Tester ◽  
Dry Heat ◽  
Calcium Sulfate Hemihydrate

Plaster of Paris (calcium sulfate hemihydrate, CaSO4. ½ H2O) has been used as a biomedical implant material since 1892. One of the primary limiting factors of these implants is their mechanical properties. These materials have low compressive and tensile strengths when compared to normal bone. These are important limiting factors where large biomechanical forces exist. Previous work has suggested that sterilization techniques could affect the implant’s strength. A study of plaster of Paris implant mechanical and physical properties to find optimum sterilization techniques therefore, could lead to a significant increase in their application and promise for future use as hard tissue prosthetic materials.USG Medical Grade Calcium Sulfate Hemihydrate Types A, A-1 and B, were sterilized by dry heat and by gamma radiation. Types A and B were additionally sterilized with and without the setting agent potassium sulfate (K2SO4). The plaster mixtures were then moistened with a minimum amount of water and formed into disks (.339 in. diameter x .053 in. deep) in polyethylene molds with a microspatula. After drying, the disks were fractured with a Stokes Hardness Tester. The compressive strengths of the disks were obtained directly from the hardness tester. Values for the maximum tensile strengths σo were then calculated: where (P = applied compression, D = disk diameter, and t = disk thickness). Plaster disks (types A and B) that contained no setting agent showed a significant loss in strength with either dry heat or gamma radiation sterilization. Those that contained potassium sulfate (K2SO4) did not show a significant loss in strength with either sterilization technique. In all comparisons (with and without K2SO4 and with either dry heat or gamma radiation sterilization) the type B plaster had higher compressive and tensile strengths than that of the type A plaster. The type A-1 plaster however, which is specially modified for accelerated setting, was comparable to that of type B with K2SO4 in both compressive and tensile strength (Table 1).

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