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Nature Communications Mar 2021The body naturally and continuously secretes sweat for thermoregulation during sedentary and routine activities at rates that can reflect underlying health conditions,...
The body naturally and continuously secretes sweat for thermoregulation during sedentary and routine activities at rates that can reflect underlying health conditions, including nerve damage, autonomic and metabolic disorders, and chronic stress. However, low secretion rates and evaporation pose challenges for collecting resting thermoregulatory sweat for non-invasive analysis of body physiology. Here we present wearable patches for continuous sweat monitoring at rest, using microfluidics to combat evaporation and enable selective monitoring of secretion rate. We integrate hydrophilic fillers for rapid sweat uptake into the sensing channel, reducing required sweat accumulation time towards real-time measurement. Along with sweat rate sensors, we integrate electrochemical sensors for pH, Cl, and levodopa monitoring. We demonstrate patch functionality for dynamic sweat analysis related to routine activities, stress events, hypoglycemia-induced sweating, and Parkinson's disease. By enabling sweat analysis compatible with sedentary, routine, and daily activities, these patches enable continuous, autonomous monitoring of body physiology at rest.
Topics: Biosensing Techniques; Body Temperature Regulation; Human Body; Humans; Hydrogen-Ion Concentration; Hypoglycemia; Levodopa; Microfluidics; Parkinson Disease; Rest; Stress, Physiological; Sweat; Sweating; Walking; Wearable Electronic Devices
PubMed: 33758197
DOI: 10.1038/s41467-021-22109-z -
Endocrinology and Metabolism Clinics of... Mar 2013During the last decades, obesity research has focused on food intake regulation, whereas energy expenditure has been mainly measured based on whole-body oxygen... (Review)
Review
During the last decades, obesity research has focused on food intake regulation, whereas energy expenditure has been mainly measured based on whole-body oxygen consumption. With the renaissance of brown adipose tissue (BAT) thermogenesis as a potential drug target in humans, more thought is put into alternative heat-producing mechanisms. Also, the interaction of peripheral and central components to regulate thermogenesis requires further studies. Certainly, several of the novel molecular genetic tools available now, compared with 40 years ago, will be helpful to gain new insights in BAT-controlled energy homeostasis and promises new approaches to pharmacologically control body weight.
Topics: Adipocytes; Adipose Tissue, Brown; Adipose Tissue, White; Animals; Body Temperature Regulation; Energy Metabolism; Humans; Thermogenesis
PubMed: 23391242
DOI: 10.1016/j.ecl.2012.11.004 -
American Journal of Physiology.... Sep 2005We measured oxygen consumption rate (Vo(2)) and body temperatures in 10 king penguins in air and water. Vo(2) was measured during rest and at submaximal and maximal...
We measured oxygen consumption rate (Vo(2)) and body temperatures in 10 king penguins in air and water. Vo(2) was measured during rest and at submaximal and maximal exercise before (fed) and after (fasted) an average fasting duration of 14.4 +/- 2.3 days (mean +/- 1 SD, range 10-19 days) in air and water. Concurrently, we measured subcutaneous temperature and temperature of the upper (heart and liver), middle (stomach) and lower (intestine) abdomen. The mean body mass (M(b)) was 13.8 +/- 1.2 kg in fed and 11.0 +/- 0.6 kg in fasted birds. After fasting, resting Vo(2) was 93% higher in water than in air (air: 86.9 +/- 8.8 ml/min; water: 167.3 +/- 36.7 ml/min, P < 0.01), while there was no difference in resting Vo(2) between air and water in fed animals (air: 117.1 +/- 20.0 ml O(2)/min; water: 114.8 +/- 32.7 ml O(2)/min, P > 0.6). In air, Vo(2) decreased with M(b), while it increased with M(b) in water. Body temperature did not change with fasting in air, whereas in water, there were complex changes in the peripheral body temperatures. These latter changes may, therefore, be indicative of a loss in body insulation and of variations in peripheral perfusion. Four animals were given a single meal after fasting and the temperature changes were partly reversed 24 h after refeeding in all body regions except the subcutaneous, indicating a rapid reversal to a prefasting state where body heat loss is minimal. The data emphasize the importance in considering nutritional status when studying king penguins and that the fasting-related physiological changes diverge in air and water.
Topics: Air; Animals; Body Temperature; Body Temperature Regulation; Body Weight; Fasting; Food; Male; Motor Activity; Oxygen Consumption; Spheniscidae; Water
PubMed: 15890795
DOI: 10.1152/ajpregu.00130.2005 -
International Journal of Hyperthermia :... 2022The cardiovascular (CV) system plays a vital role in thermoregulation because of its influence on heat transfer forced convection and conduction by changes in blood...
PURPOSE
The cardiovascular (CV) system plays a vital role in thermoregulation because of its influence on heat transfer forced convection and conduction by changes in blood distribution, blood velocity, and proximity of vessels to surrounding tissues. To fully understand the cardiovascular system's role in thermoregulation, blood distribution (influenced by cardiac output, vessel size, blood flow, and pressure) must be quantified, ideally across sex and age. Additionally, wall shear stress is quantified because it is an important metric in cardiovascular disease localization and progression. By investigating the effect of thermal conditions on wall shear stress at a healthy baseline, researchers can begin to study the confluence of thermal condition with pathology or exercise. The purpose of this study is to determine the influence of sex and age on the CV response to temperature. In this work, the effect of core body temperature on hemodynamics of the murine arterial and venous systems has been studied non-invasively, at multiple locations across age and sex.
METHODS
Male and female, adult and aged, mice ( = 20) were anesthetized and underwent MRI at 7 T. Data were acquired from four co-localized vessel pairs (the neck [carotid/jugular], torso [suprarenal and infrarenal aorta/inferior vena cava (IVC)], periphery [femoral artery/vein]) at core temperatures of 35, 36, 37, and 38 °C. Sixteen CINE, ECG-gated, phase contrast frames with one-directional velocity encoding (through plane) were acquired perpendicular to each vessel. Each frame was analyzed to quantify blood velocity and volumetric flow using a semi-automated in-house MATLAB script. Wall shear stress (WSS) was calculated using the Hagen-Poiseulle formula. A multivariable regression for WSS in the femoral artery was fitted with temperature, sex, age, body weight, and heart rate as variables.
RESULTS
Blood velocity and volumetric flow were quantified in eight vessels at four core body temperatures. Flow in the infrarenal IVC linearly increased with temperature for all groups ( = .002; adjusted means of slopes: male vs. female, 0.37 and 0.28 cm/(s × °C); adult vs. aged, 0.22 and 0.43 cm/(s × °C)). Comparing average volumetric flow response to temperature, groups differed for the suprarenal aorta (adult < aged, < .05), femoral artery (adult < aged, < .05), and femoral vein (adult male < aged male, < .001). The two-way interaction terms of temperature and body weight and temperature and sex had the largest effect on wall shear stress.
CONCLUSIONS
Age, in particular, had a significant impact on hemodynamic response as measured by volumetric flow (e.g., aged males > adult males) and WSS at peak-systole (e.g., aged males < adult males). The hemodynamic data can provide physiologically-relevant parameters, including sex and age difference, to computational fluid dynamics models and provide baseline data for the healthy murine vasculature to use as a benchmark for investigations of a variety of physiological (thermal stress) and pathophysiological conditions of the cardiovascular system.
Topics: Animals; Arteries; Body Temperature Regulation; Female; Heart Rate; Hemodynamics; Magnetic Resonance Imaging; Male; Mice; Stress, Mechanical
PubMed: 34949124
DOI: 10.1080/02656736.2021.2018510 -
Journal of the Royal Society, Interface Dec 2023Animal flight uses metabolic energy at a higher rate than any other mode of locomotion. A relatively small proportion of the metabolic energy is converted into...
Animal flight uses metabolic energy at a higher rate than any other mode of locomotion. A relatively small proportion of the metabolic energy is converted into mechanical power; the remainder is given off as heat. Effective heat dissipation is necessary to avoid hyperthermia. In this study, we measured surface temperatures in lovebirds () using infrared thermography and used heat transfer modelling to calculate heat dissipation by convection, radiation and conduction, before, during and after flight. The total non-evaporative rate of heat dissipation in flying birds was 12× higher than before flight and 19× higher than after flight. During flight, heat was largely dissipated by forced convection, via the exposed ventral wing areas, resulting in lower surface temperatures compared with birds at rest. When perched, both before and after exercise, the head and trunk were the main areas involved in dissipating heat. The surface temperature of the legs increased with flight duration and remained high on landing, suggesting that there was an increase in the flow of warmer blood to this region during and after flight. The methodology developed in this study to investigate how birds thermoregulate during flight could be used in future studies to assess the impact of climate change on the behavioural ecology of birds, particularly those species undertaking migratory flights.
Topics: Animals; Hot Temperature; Body Temperature Regulation; Birds; Temperature; Flight, Animal
PubMed: 38086401
DOI: 10.1098/rsif.2023.0442 -
International Journal of Circumpolar... Dec 2020To characterise cold sensitivity using a semi-structured interview, physical examination, thermal quantitative sensory testing (QST), and laser speckle contrast...
To characterise cold sensitivity using a semi-structured interview, physical examination, thermal quantitative sensory testing (QST), and laser speckle contrast analysis (LASCA). Eight women and four men, ages 22-74, with cold sensitivity were interviewed and examined by an occupational physician. Thermal perception thresholds were established using QST, on the pulp of the index and little finger of the most affected hand. Skin perfusion in the dorsum of the hand was measured using LASCA, at baseline, after two-minute 12°C water immersion, and during rewarming. The physical examination yielded few findings indicative of vascular or neurosensory pathology. One subject (8%) had impaired thermal perception thresholds. LASCA at baseline showed absent proximal-distal perfusion gradients in six subjects (50%), and a dyshomogeneous perfusion pattern in five (42%). Perfusion on a group level was virtually unchanged by cold stress testing (median 52.5 PU; IQR 9.0 before versus 51.3 PU; IQR 27.2 afterwards). Physical examination and thermal QST offered little aid in diagnosing cold sensitivity, which challenges the neurosensory pathophysiological hypothesis. LASCA indicated disturbances in microvascular regulation and could prove a useful tool in future studies on cold sensitivity.
Topics: Adult; Aged; Body Temperature Regulation; Cold Temperature; Female; Humans; Hypothermia, Induced; Male; Middle Aged; Pain Measurement; Reference Values; Sensory Thresholds; Skin; Vasoconstriction; Young Adult
PubMed: 32264773
DOI: 10.1080/22423982.2020.1749001 -
Philosophical Transactions of the Royal... Feb 2009Of the many visual characteristics of animals, countershading (darker pigmentation on those surfaces exposed to the most lighting) is one of the most common, and... (Review)
Review
Of the many visual characteristics of animals, countershading (darker pigmentation on those surfaces exposed to the most lighting) is one of the most common, and paradoxically one of the least well understood. Countershading has been hypothesized to reduce the detectability of prey to visually hunting predators, and while the function of a countershaded colour pattern was proposed over 100 years ago, the field has progressed slowly; convincing evidence for the protective effects of countershading has only recently emerged. Several mechanisms have been invoked for the concealing function of countershading and are discussed in this review, but the actual mechanisms by which countershading functions to reduce attacks by predators lack firm empirical testing. While there is some subjective evidence that countershaded animals match the background on which they rest, no quantitative measure of background matching has been published for countershaded animals; I now present the first such results. Most studies also fail to consider plausible alternative explanations for the colour pattern, such as protection from UV or abrasion, and thermoregulation. This paper examines the evidence to support each of these possible explanations for countershading and discusses the need for future empirical work.
Topics: Adaptation, Biological; Animals; Body Temperature Regulation; Color; Environment; Pigmentation; Ultraviolet Rays
PubMed: 19000972
DOI: 10.1098/rstb.2008.0261 -
Journal of Thermal Biology Aug 2016Thermoregulatory ability and behavior influence organismal responses to their environment. By measuring thermal preferences, researchers can better understand the...
Thermoregulatory ability and behavior influence organismal responses to their environment. By measuring thermal preferences, researchers can better understand the effects that temperature tolerances have on ecological and physiological responses to both biotic and abiotic stressors. However, because of funding limitations and confounders, measuring thermoregulation can often be difficult. Here, we provide an effective, affordable (~$50 USD per unit), easy to construct, and validated apparatus for measuring the long-term thermal preferences of animals. In tests, the apparatus spanned temperatures from 9.29 to 33.94°C, and we provide methods to further increase this range. Additionally, we provide simple methods to non-invasively measure animal and substrate temperatures and to prevent temperature preferences of the focal organisms from being confounded with temperature preferences of its prey and its humidity preferences. To validate the apparatus, we show that it was capable of detecting individual-level consistency and among individual-level variation in the preferred body temperatures of Southern toads (Anaxyrus terrestris) and Cuban tree frogs (Osteopilus septentrionalis) over three-weeks. Nearly every aspect of our design is adaptable to meet the needs of a multitude of study systems, including various terrestrial amphibious, and aquatic organisms. The apparatus and methods described here can be used to quantify behavioral thermal preferences, which can be critical for determining temperature tolerances across species and thus the resiliency of species to current and impending climate change.
Topics: Acclimatization; Animals; Anura; Behavior, Animal; Body Temperature; Body Temperature Regulation; Climate Change; Environment, Controlled; Equipment Design; Humidity; Physiology; Temperature
PubMed: 27503737
DOI: 10.1016/j.jtherbio.2016.07.016 -
PloS One 2023Otopetrin 1 (OTOP1) is a proton channel that is highly expressed in brown adipose tissue. We examined the physiology of Otop1-/- mice, which lack functional OTOP1.
OBJECTIVE
Otopetrin 1 (OTOP1) is a proton channel that is highly expressed in brown adipose tissue. We examined the physiology of Otop1-/- mice, which lack functional OTOP1.
METHODS
Mice were studied by indirect calorimetry and telemetric ambulatory body temperature monitoring. Mitochondrial function was measured as oxygen consumption and extracellular acidification.
RESULTS
Otop1-/- mice had similar body temperatures as control mice at baseline and in response to cold and hot ambient temperatures. However, in response to fasting the Otop1-/- mice exhibited an exaggerated hypothermia and hypometabolism. Similarly, in ex vivo tests of Otop1-/- brown adipose tissue mitochondrial function, there was no change in baseline oxygen consumption, but the oxygen consumption was reduced after maximal uncoupling with FCCP and increased upon stimulation with the β3-adrenergic agonist CL316243. Mast cells also express Otop1, and Otop1-/- mice had intact, possibly greater hypothermia in response to mast cell activation by the adenosine A3 receptor agonist MRS5698. No increase in insulin resistance was observed in the Otop1-/- mice.
CONCLUSIONS
Loss of OTOP1 does not change basal function of brown adipose tissue but affects stimulated responses.
Topics: Animals; Mice; Adipose Tissue, Brown; Body Temperature; Body Temperature Regulation; Fasting; Hypothermia; Mice, Knockout
PubMed: 37812612
DOI: 10.1371/journal.pone.0292610 -
PloS One 2022The western conifer seed bug (WCSB, Leptoglossus occidentalis) is a pest of many pine species and is invasive worldwide. WCSB directly and indirectly deteriorates pine...
Evaluation of thermoregulation of different pine organs in early spring and estimation of heat reward for the western conifer seed bug (Leptoglossus occidentalis) on male cones.
The western conifer seed bug (WCSB, Leptoglossus occidentalis) is a pest of many pine species and is invasive worldwide. WCSB directly and indirectly deteriorates pine nut production by sucking seeds from cones. Currently, researchers think that WCSBs search for food by a combination of cues from visible light, infrared radiation, and chemicals such as monoterpenes. Some research revealed that WCSBs prefer larger cones, and it was thought that WCSBs suck seeds from and obtain more heat on larger cones. However, in early spring, we observed that most WCSBs gathered on male cones rather than on female cones and young cones. We hypothesized that male pine cones were warmer than female cones and needles, and WCSBs sucking male cones may receive more heat. To test these hypotheses, we measured spectral reflectance with a hyperspectral sensor and temperature of pine organs with tiny thermocouples, and the data were analyzed by a heat budget model. Our results revealed that male cones were significantly warmer and more reflective than female cones and needles, which may attract WCSBs. These results supported our hypothesis that WCSBs on male cones were warmer than those on other organs. This study will help further understanding of WCSBs and the adaptive value of pine cone colors.
Topics: Animals; Body Temperature Regulation; Female; Heteroptera; Hot Temperature; Male; Pinus; Reward; Tracheophyta
PubMed: 35925894
DOI: 10.1371/journal.pone.0272565