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Body Temperature (body + temperature)
Kinds of Body Temperature Selected AbstractsDOES VIVIPARITY EVOLVE IN COLD CLIMATE REPTILES BECAUSE PREGNANT FEMALES MAINTAIN STABLE (NOT HIGH) BODY TEMPERATURES?EVOLUTION, Issue 8 2004Richard Shine Abstract Viviparity (live bearing) has evolved from egg laying (oviparity) in many lineages of lizards and snakes, apparently in response to occupancy of cold climates. Explanations for this pattern have focused on the idea that behaviorally thermoregulating (sun-basking) pregnant female reptiles can maintain higher incubation temperatures for their embryos than would be available in nests under the soil surface. This is certainly true at very high elevations, where only viviparous species occur. However, comparisons of nest and lizard temperatures at sites close to the upper elevational limit for oviparous reptiles (presumably, the selective environment where the transition from oviparity to viviparity actually occurs) suggest that reproductive mode has less effect on mean incubation temperatures than on the diel distribution of those temperatures. Nests of the oviparous scincid lizard Bassiana duperreyi showed smooth diel cycles of heating and cooling. In contrast, body temperatures of the viviparous scincid Eulamprus heatwolei rose abruptly in the morning, were high and stable during daylight hours, and fell abruptly at night. Laboratory incubation experiments mimicking these patterns showed that developmental rates of eggs and phenotypic traits of hatchling B. duperreyi were sensitive to this type of thermal variance as well as to mean temperature. Hence, diel distributions as well as mean incubation temperatures may have played an important role in the selective forces for viviparity. More generally, variances as well as mean values of abiotic factors may constitute significant selective forces on life-history evolution. [source] Metabolic Heat Production, Heat Loss and the Circadian Rhythm of Body Temperature in the RatEXPERIMENTAL PHYSIOLOGY, Issue 3 2003Roberto Refinetti Metabolic heat production (calculated from oxygen consumption), dry heat loss (measured in a calorimeter) and body temperature (measured by telemetry) were recorded simultaneously at 6 min intervals over five consecutive days in rats maintained in constant darkness. Robust circadian rhythmicity (confirmed by chi square periodogram analysis) was observed in all three variables. The rhythm of heat production was phase-advanced by about half an hour in relation to the body temperature rhythm, whereas the rhythm of heat loss was phase-delayed by about half an hour. The balance of heat production and heat loss exhibited a daily oscillation 180 deg out of phase with the oscillation in body temperature. Computations indicated that the amount of heat associated with the generation of the body temperature rhythm (1.6 kJ) corresponds to less than 1% of the total daily energy budget (172 kJ) in this species. Because of the small magnitude of the fraction of heat balance associated with the body temperature rhythm, it is likely that the daily oscillation in heat balance has a very slow effect on body temperature, thus accounting for the 180 deg phase difference between the rhythms of heat balance and body temperature. [source] Thyrotrophin-Releasing Hormone Decreases Feeding and Increases Body Temperature, Activity and Oxygen Consumption in Siberian HamstersJOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2007S. Schuhler Thyrotrophin-releasing hormone (TRH) is known to play an important role in the control of food intake and energy metabolism in addition to its actions on the pituitary-thyroid axis. We have previously shown that central administration of TRH decreases food intake in Siberian hamsters. This species is being increasingly used as a physiological rodent model in which to understand hypothalamic control of long-term changes in energy balance because it accumulates fat reserves in long summer photoperiods, and decreases food intake and body weight when exposed to short winter photoperiods. The objectives of our study in Siberian hamsters were: (i) to investigate whether peripheral administration of TRH would mimic the effects of central administration of TRH on food intake and whether these effects would differ dependent upon the ambient photoperiod; (ii) to determine whether TRH would have an effect on energy expenditure; and (iii) to investigate the potential sites of action of TRH. Both peripheral (5,50 mg/kg body weight; i.p.) and central (0.5 µg/ml; i.c.v.) administration of TRH decreased food intake, and increased locomotor activity, body temperature and oxygen consumption in the Siberian hamster, with a rapid onset and short duration of action. Systemic treatment with TRH was equally effective in suppressing feeding regardless of ambient photoperiod. The acute effects of TRH are likely to be centrally mediated and independent of its role in the control of the production of thyroid hormones. We conclude that TRH functions to promote a catabolic energetic state by co-ordinating acute central and chronic peripheral (thyroid-mediated) function. [source] Changes in Hypothalamic-Pituitary-Adrenal Function, Body Temperature, Body Weight and Food Intake with Repeated Social Stress Exposure in RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2006S. Bhatnagar Abstract These present studies aimed to compare changes in hypothalamic-pituitary-adrenal (HPA) activity and body temperature in response to acute social defeat, to repeated social stress and to novel restraint after repeated stress, as well as to assess effects on metabolic parameters by measuring body weight gain and food and water intake. We found that social defeat produced a marked increase in both adrenocorticotrophic hormone and corticosterone compared to placement in a novel cage. Similarly, body temperature was also increased during social defeat and during 30 min of recovery from defeat. We then examined the effects of 6 days of repeated social stress and observed minimal HPA responses to repeated social stress compared to control rats. These neuroendocrine responses were contrasted by robust increases in body temperature during stress and during recovery from stress during 6 days of repeated stress. However, in response to novel restraint, repeatedly stressed rats displayed facilitated body temperature responses compared to controls, similar to our previous findings with HPA activity. Food intake was increased during the light period during which defeat took place, but later intake during the dark period was not affected. Repeated stress decreased body weight gain in the dark period but food intake was increased overall during the 6 days of repeated stress in the light period. As a result, repeated stress increased cumulative food intake during the light period in the stressed rats but these relatively small increases in food intake were unable to prevent the diminished total weight gain in repeatedly stressed rats. Overall, the results demonstrate that, although acute social defeat has similar effects on temperature and HPA activity, repeated exposure to social stress has divergent effects on HPA activity compared to body temperature and that dampened weight gain produced by repeated social stress cannot be fully explained by changes in food intake. [source] Optimal Body Temperature in Transitional Extremely Low Birth Weight Infants Using Heart Rate and Temperature as IndicatorsJOURNAL OF OBSTETRIC, GYNECOLOGIC & NEONATAL NURSING, Issue 1 2010Robin B. Knobel ABSTRACT Objective: To explore body temperature in relationship to heart rate in extremely low birth weight (ELBW) infants during their first 12 hours to help identify the ideal set point for incubator control of body temperature. Design: Within subject, multiple-case design. Setting: A tertiary neonatal intensive care unit (NICU) in North Carolina. Participants: Ten infants born at fewer than 29 weeks gestation and weighing 400 to 1,000 g. Methods: Heart rate and abdominal body temperature were measured at 1-minute intervals for 12 hours. Heart rates were considered normal if they were between the 25th and 75th percentile for each infant. Results: Abdominal temperatures were low throughout the 12-hour study period (mean 35.17-36.68 °C). Seven of 10 infants had significant correlations between abdominal temperature and heart rate. Heart rates above the 75th percentile were associated with low and high abdominal temperatures; heart rates less than the 25th percentile were associated with very low abdominal temperatures. The extent to which abdominal temperature was abnormally low was related to the extent to which the heart rate trended away from normal in 6 of the 10 infants. Optimal temperature control point that maximized normal heart rate observations for each infant was between 36.8 °C and 37 °C. Conclusions: Hypothermia was associated with abnormal heart rates in transitional ELBW infants. We suggest nurses set incubator servo between 36.8 °C and 36.9 °C to optimally control body temperature for ELBW infants. [source] Research on the human thermal model with a poly-segmented handHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2008Ding Li Abstract A more integral human thermal model was built by combining the human thermal cylindrical model and the manual poly-segment thermal model. Finite element methods (FEM) was used to define the body thermal model. It was in good agreement with the experimental results. The results show: the experimental results are consistent with the calculated value, when suitable blood flux is taken into consideration. The blood flux is in a certain range when the manual temperature is stable. Blood flux is the major factor in the manual temperature field. Body temperature and intake artery temperature have little effect on the hand temperature. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(2): 94,100, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20187 [source] Symptoms and signs in culture-proven acute maxillary sinusitis in a general practice populationAPMIS, Issue 10 2009JENS GEORG HANSEN The objective of this study was to assess symptoms and signs in patients with maxillary sinusitis and a bacteriological diagnosis obtained by sinus aspiration or lavage. Designed as a prospective cohort study in general practice, the study included 174 patients, aged 18,65 years, suspected of having acute maxillary sinusitis by their general practitioner. The main outcome measures were the independent association of symptoms, signs, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) concentration and confirmed infection with the predominant bacterial pathogens Streptococcus pneumoniae and Haemophilus influenzae. The predominant organisms found in patients with acute maxillary sinusitis were S. pneumoniae and H. influenzae. Body temperature >38 °C and maxillary toothache were significantly associated with the presence of S. pneumoniae and H. influenzae. Positive bacteriological culture results were significantly associated with increasing ESR and CRP values. None of the symptoms and signs, with the exception of body temperature >38 °C and maxillary toothache, were particularly sensitive indicators of the specific aetiology in patients with acute maxillary sinusitis. Elevated ESR and CRP values were significantly associated with positive bacteriological culture results. On the other hand, absence of these symptoms and signs did not exclude the presence of acute maxillary sinusitis. [source] Kangaroo Mother Care: 25 years afterACTA PAEDIATRICA, Issue 5 2005Nathalie Charpak Abstract The components of the Kangaroo Mother Care (KMC) intervention, their rational bases, and their current uses in low-, middle-, and high-income countries are described. KMC was started in 1978 in Bogotá (Colombia) in response to overcrowding and insufficient resources in neonatal intensive care units associated with high morbidity and mortality among low-birthweight infants. The intervention consists of continuous skin-to-skin contact between the mother and the infant, exclusive breastfeeding, and early home discharge in the kangaroo position. In studies of the physiological effects of KMC, the results for most variables were within clinically acceptable ranges or the same as those for premature infants under other forms of care. Body temperature and weight gain are significantly increased, and a meta-analysis showed that the kangaroo position increases the uptake and duration of breastfeeding. Investigations of the behavioral effects of KMC show rapid quiescence. The psychosocial effects of KMC include reduced stress, enhancement of mother,infant bonding, and positive effects on the family environment and the infant's cognitive development. Conclusion: Past and current research has clarified some of the rational bases of KMC and has provided evidence for its effectiveness and safety, although more research is needed to clearly define the effectiveness of the various components of the intervention in different settings and for different therapeutic goals. [source] Thermal ecology of Zonocerus variegatus and its effects on biocontrol using pathogensAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2000Simon Blanford Summary 1 Thermal behaviour of the variegated grasshopper, Zonocerus variegatus, was investigated in the humid tropical zone of southern Benin, west Africa, in the dry seasons of 1996 and 1998. In 1998, investigations included studies of a population of grasshoppers sprayed with an oil-based formulation of the entomopathogenic fungus Metarhizium anisopliae var acridum. 2 Body temperature measurements and observations of thermal behaviour both in the field and on thermal gradients in the laboratory, suggest that Z. variegatus was not an active behavioural thermoregulator. Although it did show shade-seeking behaviour at high temperatures, no overt behavioural postures or microhabitat selection associated with heat gain and elevation of body temperatures was observed. Moreover, no alterations to thermal behaviour were found in response to infection by Metarhizium. 3 Body temperatures exhibited by Z. variegatus in the field will lengthen disease incubation of M. anisopliae var acridum compared with laboratory maintained, constant temperature conditions and may have a significant impact on pathogens with a lower thermal tolerance. 4 Habitat structure appeared to be an important factor determining the extent of body temperature elevation. The effect of habitat differences on infection and growth of M. anisopliae var acridum and other entomopathogenic fungi is discussed. [source] The birth process initiates an acute phase reaction in the fetus-newborn infantACTA PAEDIATRICA, Issue 9 2000G Marchini Our goal was to investigate whether the normal birth process stimulated an acute phase response in healthy infants with physiological changes in the circulating levels of acute phase cytokines and acute phase proteins. We also monitored body temperature, body weight and behavioural state in order to investigate if clinical signs of acute phase reaction were present. We made cross-sectional measurements of interleukin-1,, interleukin-6, C-reactive protein, serum amyloid A, procalcitonin, prealbumin, body weight, body temperature and the duration of the sleeping period during the first four postnatal days. We found an increase in interleukin-6 (p < 0.001) during the first day, followed by an increase in C-reactive protein, serum amyloid A and procalcitonin on the second postnatal day (p < 0.01). The level of prealbumin fell after birth and reached its lowest value at 3 d of age (p < 0,001). Interleukin-l p remained unchanged. The duration of the sleeping period was longer during the first day (p < 0.01). There was an increase in body temperature during the first day (p < 0.01). Maximal weight loss was during the first 2 d. Conclusions: The normal birth process and extra-uterine adaptation stimulates an acute phase reaction in the newborn infant with a release of interleukin-6 and acute phase proteins and a depression of prealbumin. This reaction, as the body's first line inflammatory defence system, probably affects the infant's behaviour, nutritional state as well as the regulation of body temperature. [source] Adenosine A3 receptors regulate heart rate, motor activity and body temperatureACTA PHYSIOLOGICA, Issue 2 2010J. N. Yang Abstract Aim:, To examine the phenotype of mice that lack the adenosine A3 receptor (A3R). Methods:, We examined the heart rate, body temperature and locomotion continuously by telemetry over several days. In addition, the effect of the adenosine analogue R- N6 -phenylisopropyl-adenosine (R-PIA) was examined. We also examined heat production and food intake. Results:, We found that the marked diurnal variation in activity, heart rate and body temperature, with markedly higher values at night than during day time, was reduced in the A3R knock-out mice. Surprisingly, the reduction in heart rate, activity and body temperature seen after injection of R-PIA in wild type mice was virtually eliminated in the A3R knock-out mice. The marked reduction in activity was associated with a decreased heat production, as expected. However, the A3R knock-out mice, surprisingly, had a higher food intake but no difference in body weight compared to wild type mice. Conclusions:, The mice lacking adenosine A3 receptors exhibit a surprisingly clear phenotype with changes in diurnal rhythm and temperature regulation. Whether these effects are due to a physiological role of A3 receptors in these processes or whether they represent a role in development remains to be elucidated. [source] Adenosine infusion attenuates soluble RAGE in endotoxin-induced inflammation in human volunteersACTA PHYSIOLOGICA, Issue 1 2009A. Soop Abstract Aim:, To evaluate possible anti-inflammatory effects of pre-treatment with adenosine in a human experimental inflammatory model. Methods:, The study design was double-blind, crossover, placebo-controlled and randomized. In the Intensive Care Unit of a university hospital, 16 healthy male volunteers were treated for 5.5 h with infusions of adenosine 40 ,g kg,1 min,1 or placebo. Thirty minutes after the start of adenosine or placebo, 2 ng kg,1E-Coli endotoxin was administered. Heart rate, body temperature, blood pressure, plasma cytokines (TNF-,, IL-6 and IL-10), soluble RAGE and resistin, exhaled nitric oxide and nitrite/nitrate in urine were determined. Results:, Endotoxin elicited the expected clinical signs of an inflammatory reaction (tachycardia, fever) and led to prominent release of the cytokines studied (P < 0.001). Resistin in plasma increased after endotoxin (P < 0.001). After placebo treatment, soluble RAGE (sRAGE) in plasma increased 5 h after the endotoxin challenge (P < 0.001) but not after adenosine. After placebo, orally exhaled NO increased with a peak at 4 h (P < 0.001), although there was no statistically significant difference between the two treatments. Nitrite/nitrate in urine (n = 11) did not differ between adenosine and placebo treatments. Conclusion:, In conclusion, adenosine infusion starting before endotoxin challenge in humans attenuated sRAGE significantly but otherwise had no clear anti-inflammatory effect. Adenosine as a potential anti-inflammatory treatment in humans needs further study, including use of higher doses. The mechanism underlying the effect of adenosines on sRAGE remains unknown. [source] Neuroanatomical basis for therapeutic applications of cannabinoid receptor 1 antagonistsDRUG DEVELOPMENT RESEARCH, Issue 8 2009Brian F. Thomas Abstract The CB1 receptor is a Class A G-protein coupled receptor that has a high density and widespread distribution within the central nervous system. Because of its neuroanatomical distribution, the endocannabinoid system can modulate a wide variety of psychological and physiological functions. For example, CB1 receptors are found in brain regions regulating motor activity, cognitive processes, pain, satiety, appetitive behaviors and reward. In correspondence with this distribution, modulation of the endocannabinoid system has been shown to produce changes in coordination, executive function, memory, mood, perception, wakefulness, nociception and appetite. Administration of cannabinoid agonists has also been therapeutically used to reduce nausea, and is also known to decrease body temperature and neuronal excitability, pointing to additional roles for endocannabinoids in these and other physiological/neurological processes. The ongoing elucidation and characterization of the neuroanatomical circuitry within which the CB1 cannabinoid receptor and endocannabinoids are localized to modulate these psychological and physiological processes continues to suggest therapeutic applications for cannabinoid antagonists and inverse agonists. Drug Dev Res 70:527,554, 2009. © 2009 Wiley-Liss, Inc. [source] Ambient temperature and risk of death from accidental drug overdose in New York City, 1990,2006ADDICTION, Issue 6 2010Amy S. B. Bohnert ABSTRACT Background Mortality increases as ambient temperature increases. Because cocaine affects core body temperature, ambient temperature may play a role in cocaine-related mortality in particular. The present study examined the association between ambient temperature and fatal overdoses over time in New York City. Methods Mortality data were obtained from the Office of the Chief Medical Examiner for 1990 to 2006, and temperature data from the National Oceanic and Atmospheric Association. We used generalized additive models to test the relationship between weekly average temperatures and counts of accidental overdose deaths in New York City, controlling for year and average length of daylight hours. Results We found a significant relation between ambient temperature and accidental overdose fatality for all models where the overdoses were due in whole or in part to cocaine (all P < 0.05), but not for non-cocaine overdoses. Risk of accidental overdose deaths increased for weeks when the average temperature was above 24°Celsius. Conclusions These results suggest a strong relation between temperature and accidental overdose mortality that is driven by cocaine-related overdoses rising at temperatures above 24°Celsius; this is a substantially lower temperature than prior estimates. To put this into perspective, approximately 7 weeks a year between 1990 and 2006 had an average weekly temperature of 24 or above in New York City. Heat-related mortality presents a considerable public health concern, and cocaine users constitute a high-risk group. [source] Foraging energetics of arctic cormorants and the evolution of diving birdsECOLOGY LETTERS, Issue 3 2001David Grémillet Efficient body insulation is assumed to have enabled birds and mammals to colonize polar aquatic ecosystems. We challenge this concept by comparing the bioenergetics of cormorants (Phalacrocorax carbo) living in temperate and arctic conditions. We show that although these birds have limited insulation, they maintain high body temperature (42.3 °C) when diving in cold water (1,10 °C). Their energy demand at these times is extremely high (up to 60 W kg,1). Free-living cormorants wintering in Greenland (water temperature ,1 °C) profoundly alter their foraging activity, thus minimizing time spent in water and the associated high thermoregulatory costs. They then meet their daily food demand within a single intense dive bout (lasting 9 min on average). Their substantial energy requirements are balanced by the highest predatory efficiency so far recorded for aquatic predators. We postulate that similar behavioural patterns allowed early diving birds (Cretaceous) to colonize cold coastal areas before they evolved efficient insulation. [source] Effects of Circadian Regulation and Rest,Activity State on Spontaneous Seizures in a Rat Model of Limbic EpilepsyEPILEPSIA, Issue 5 2000Mark Quigg Summary: Purpose: Circadian regulation via the suprachiasmatic nuclei and rest,activity state may influence expression of limbic seizures. Methods: Male rats (n = 14) were made epileptic by electrical stimulation of the hippocampus, causing limbic status epilepticus and subsequent seizures. We monitored seizures with intrahippocampal electrodes in 12,12-h light/dark (LD) cycles and in continuous dark (DD). We used radiotelemetry monitoring of activity to measure state and body temperature to determine circadian phase. Cosinor analysis and ,2 tests determined whether seizures occurred rhythmically when plotted by phase. State was defined as inactive or active in 10-min epochs based on whether activity count was below or above a cut-off value validated from video observation. Results: In LD, the peak seizure occurrence was 14:59 h after circadian temperature peak (95% confidence limit, 13:37,16:19). Phasic seizure occurrence persisted in DD for 14:05 (12:31,15:38), p < 0.0001, against uniform mean distribution. In LD, 14,787 epochs contained 1,268 seizures; seizures preferentially occurred during inactive epochs (965 observed, 878 expected in proportion to the overall distribution of inactive versus active epochs; p < 0.001). In DD, 20,664 epochs contained 1,609 seizures; seizures had no preferential occurrence by state (999 observed, 1,025 expected; p = 0.16). Conclusions: Limbic seizures occurred with an endogenous circadian rhythm. Seizures preferentially struck during inactivity during entrainment to the light,dark cycle. [source] Temperature Effects on Anti-Predator Behaviour in Rhabdophis tigrinus, a Snake with Toxic Nuchal GlandsETHOLOGY, Issue 9 2001Akira Mori Many contextual factors affect the anti-predator behaviour of animals. In ectotherms, in which most physiological activities depend on body temperature, ambient temperature is one of the most important of these factors. We examined the effects of temperature on the anti-predator behaviour of an ectotherm, the Japanese grass snake (Rhabdophis tigrinus). This species has a large repertoire of anti-predator behavioural responses. Among these responses are several anti-predator displays that appear to be unique to this species and perhaps others in a small group of closely related species possessing nuchal glands containing toxic secretions that may be derived from their toxic toad diet. Snakes were tested at room temperatures of 14, 22 and 30°C with order of temperatures balanced. A long wand modified to simulate initial contact by a predator was used as the stimulus. Snakes exhibited rather passive responses (neck flatten, body flatten, neck arch and immobile) more frequently at low temperatures, and fled more frequently at high temperatures. The dorsal facing posture, a characteristic posture directed against the stimulus, was observed more frequently at low temperatures. Threatening, assertive responses such as strike were rarely observed. These results showed that R. tigrinus shifts its anti-predator behaviour from multiple passive responses to active flight responses with increasing temperature. This snake species thus appears to rely more on its nuchal glands as a predator deterrent at low ambient temperatures. Consistent individual variation was also observed, and its adaptive and causal bases are discussed. [source] Costs of Refuge Use Affect Escape Decisions of Iberian Rock Lizards Lacerta monticolaETHOLOGY, Issue 6 2000José Martín Theoretical models of anti-predator escape behaviour suggest that prey may adjust their escape response such that the optimal flight distance is the point at which the costs of staying exceed the costs of fleeing. Anti-predatory decisions should be made based also on consequences for long-term expected fitness, such as the costs of refuge use. For example, in lizards, the maintenance of an optimal body temperature is essential to maximize physiological processes. However, if unfavourable thermal conditions of refuges can decrease the body temperature of lizards, their escape decision should be influenced by refuge conditions. Analyses of the variation in flight distances and emergence latency from a refuge for the lizard Lacerta monticola under two different predation risk levels, and their relationship with the thermal environment, supported these predictions. When risk increased, lizards had longer emergence latencies, and thus costs of refuge use increased (a greater loss of time and body temperature). In the low-risk situation, lizards that were farther from the refuge had longer flight distances, whereas thermal conditions were less important. When risk increased, lizards had longer flight distances when refuges were farther off, but also when the external heating rate and the refuge cooling rate were lower. The results suggest that, in addition to the risk of predation, expected long-term fitness costs of refuges can also affect escape decisions. [source] Therapy of circadian rhythm disorders in chronic fatigue syndrome: no symptomatic improvement with melatonin or phototherapyEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 11 2002G. Williams Abstract Background Patients with chronic fatigue syndrome (CFS) show evidence of circadian rhythm disturbances. We aimed to determine whether CFS symptoms were alleviated by melatonin and bright-light phototherapy, which have been shown to improve circadian rhythm disorders and fatigue in jet-lag and shift workers. Design Thirty patients with unexplained fatigue for > 6 months were initially assessed using placebo and then received melatonin (5 mg in the evening) and phototherapy (2500 Lux for 1 h in the morning), each for 12 weeks in random order separated by a washout period. Principal symptoms of CFS were measured by visual analogue scales, the Shortform (SF-36) Health Survey, Mental Fatigue Inventory and Hospital Anxiety and Depression Scale. We also determined the circadian rhythm of body temperature, timing of the onset of melatonin secretion, and the relationship between these. Results Neither intervention showed any significant effect on any of the principal symptoms or on general measures of physical or mental health. Compared with placebo, neither body temperature rhythm nor onset of melatonin secretion was significantly altered by either treatment, except for a slight advance of temperature phase (0·8 h; P = 0·04) with phototherapy. Conclusion Melatonin and bright-light phototherapy appear ineffective in CFS. Both treatments are being prescribed for CFS sufferers by medical and alternative practitioners. Their unregulated use should be prohibited unless, or until, clear benefits are convincingly demonstrated. [source] PRECLINICAL STUDY: Ecstasy-induced oxidative stress to adolescent rat brain mitochondria in vivo: influence of monoamine oxidase type AADDICTION BIOLOGY, Issue 2 2009Ema Alves ABSTRACT The administration of a neurotoxic dose of 3,4-methylenedioxymethamphetamine (MDMA; ,ecstasy') to the rat results in mitochondrial oxidative damage in the central nervous system, namely lipid and protein oxidation and mitochondrial DNA deletions with subsequent impairment of the correspondent protein expression. Although these toxic effects were shown to be prevented by monoamine oxidase B inhibition, the role of monoamine oxidase A (MAO-A) in MDMA-mediated mitochondrial damage remains to be evaluated. Thus, the aim of the present study was to clarify the potential interference of a specific inhibition of MAO-A by clorgyline, on the deleterious effects produced by a binge administration of a neurotoxic dose of MDMA (10 mg MDMA/kg of body weight, intraperitoneally, every 2 hours in a total of four administrations) to an adolescent rat model. The parameters evaluated were mitochondrial lipid peroxidation, protein carbonylation and expression of the respiratory chain protein subunits II of reduced nicotinamide adenine dinucleotide dehydrogenase (NDII) and I of cytochrome oxidase (COXI). Considering that hyperthermia has been shown to contribute to the neurotoxic effects of MDMA, another objective of the present study was to evaluate the body temperature changes mediated by MDMA with a MAO-A selective inhibition by clorgyline. The obtained results demonstrated that the administration of a neurotoxic binge dose of MDMA to an adolescent rat model previously treated with the specific MAO-A inhibitor, clorgyline, resulted in synergistic effects on serotonin- (5-HT) mediated behaviour and body temperature, provoking high mortality. Inhibition of MAO-A by clorgyline administration had no protective effect on MDMA-induced alterations on brain mitochondria (increased lipid peroxidation, protein carbonylation and decrease in the expression of the respiratory chain subunits NDII and COXI), although it aggravated MDMA-induced decrease in the expression of COXI. These results reinforce the notion that the concomitant use of MAO-A inhibitors and MDMA is counter indicated because of the resulting severe synergic toxicity. [source] Food-entrainable circadian oscillators in the brainEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2009M. Verwey Abstract Circadian rhythms in mammalian behaviour and physiology rely on daily oscillations in the expression of canonical clock genes. Circadian rhythms in clock gene expression are observed in the master circadian clock, the suprachiasmatic nucleus but are also observed in many other brain regions that have diverse roles, including influences on motivational and emotional state, learning, hormone release and feeding. Increasingly, important links between circadian rhythms and metabolism are being uncovered. In particular, restricted feeding (RF) schedules which limit food availability to a single meal each day lead to the induction and entrainment of circadian rhythms in food-anticipatory activities in rodents. Food-anticipatory activities include increases in core body temperature, activity and hormone release in the hours leading up to the predictable mealtime. Crucially, RF schedules and the accompanying food-anticipatory activities are also associated with shifts in the daily oscillation of clock gene expression in diverse brain areas involved in feeding, energy balance, learning and memory, and motivation. Moreover, lesions of specific brain nuclei can affect the way rats will respond to RF, but have generally failed to eliminate all food-anticipatory activities. As a consequence, it is likely that a distributed neural system underlies the generation and regulation of food-anticipatory activities under RF. Thus, in the future, we would suggest that a more comprehensive approach should be taken, one that investigates the interactions between multiple circadian oscillators in the brain and body, and starts to report on potential neural systems rather than individual and discrete brain areas. [source] Cold-seeking behavior as a thermoregulatory strategy in systemic inflammationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2006Maria C. Almeida Abstract Systemic inflammation (SI) is a leading cause of hospital death. Although fever and hypothermia are listed as symptoms in every definition of SI, how SI affects thermoregulatory behavior is unclear. SI is often modeled by systemic administration of bacterial lipopolysaccharide (LPS) to rats. When rats are not allowed to regulate their body temperature (Tb) behaviorally, LPS causes either fever or hypothermia, and the direction of the response is determined by LPS dose and ambient temperature (Ta). However, in many studies in which rats were allowed to regulate Tb behaviorally (by selecting their preferred Ta in a thermogradient apparatus), they consistently expressed warmth-seeking behavior and developed fever. We hypothesized that SI can cause not only warmth-seeking behavior but also cold-seeking behavior; we then tested this hypothesis by studying LPS-induced thermoregulatory behavior in adult Wistar rats. A multichannel thermogradient apparatus, implantable data loggers and infrared thermography were used; multiple control experiments were conducted; and the ability of the apparatus to reliably register the changes in rats' preferred Ta induced by thermal (external cooling or heating) or chemical (TRPV1 or TRPM8 agonist) stimuli was confirmed. The rats responded to a low dose of LPS (10 µg/kg i.v.) with warmth-seeking behavior and a polyphasic fever, but to a high dose (5 mg/kg i.v.) with marked cold-seeking behavior and hypothermia followed by warmth-seeking behavior and fever. This is the first well-controlled study to report SI-associated cold-seeking behavior in rats. Cold-seeking behavior is likely to be an important defense response in severe SI. [source] THE ENVIRONMENTAL AND GENETIC CONTROL OF SEASONAL POLYPHENISM IN LARVAL COLOR AND ITS ADAPTIVE SIGNIFICANCE IN A SWALLOWTAIL BUTTERFLYEVOLUTION, Issue 2 2002Wade N. Hazel Abstract Seasonal polyphenism, in which different forms of a species are produced at different times of the year, is a common form of phenotypic plasticity among insects. Here I show that the production of dark fifth-instar caterpillars of the eastern black swallowtail butterfly, Papilio polyxenes, is a seasonal polyphenism, with larvae reared on autumnal conditions being significantly darker than larvae reared on midsummer conditions. Both rearing photoperiod and temperature were found to have individual and synergistic effects on larval darkness. Genetic analysis of variation among full-sibling families reared on combinations of two different temperatures and photoperiods is consistent with the hypothesis that variation in darkness is heritable. In addition, the genetic correlation in larval darkness across midsummer and autumnal environments is not different from zero, suggesting that differential gene expression is responsible for the increase in larval darkness in the autumn. The relatively dark autumnal form was found to have a higher body temperature in sunlight than did the lighter midsummer form, and small differences in temperature were found to increase larval growth rate. These results suggest that this genetically based seasonal polyphenism in larval color has evolved in part to increase larval growth rates in the autumn. [source] COEVOLUTION OF COLOR PATTERN AND THERMOREGULATORY BEHAVIOR IN POLYMORPHIC PYGMY GRASSHOPPERS TETRIX UNDULATAEVOLUTION, Issue 2 2002Anders Forsman Abstract Ectothermic organisms, such as insects and reptiles, rely on external heat sources to control body temperature and possess physiological and behavioral traits that are temperature dependent. It has therefore been hypothesised that differences in body temperature resulting from phenotypic properties, such as color pattern, may translate into selection against thermally inferior phenotypes. We tested for costs and benefits of pale versus dark coloration by comparing the behaviors (i.e., basking duration and bouts) of pygmy grasshopper (Tetrix undulata) individuals exposed to experimental situations imposing a trade-off between temperature regulation and feeding. We used pairs consisting of two full-siblings of the same sex that represented different (genetically coded) color morphs but had shared identical conditions from the time of fertilization. Our results revealed significant differences in behavioral thermoregulation between dark and pale individuals in females, but not in males. Pale females spent more time feeding than dark females, regardless of whether feeding was associated with a risk of either hypothermia or overheating. In contrast, only minor differences in behavior (if any) were evident between individuals that belonged to the same color morph but had been painted black or gray to increase and decrease their heating rates. This suggests that the behavioral differences between individuals belonging to different color morphs are genetically determined, rather than simply reflecting a response to different heating rates. To test for effects of acclimation on behaviors, we used pairs of individuals that had been reared from hatchlings to adults under controlled conditions in either low or high temperature. The thermal regime experienced during rearing had little effect on behaviors during the experiments reported above, but significantly influenced the body temperatures selected in a laboratory thermal gradient. In females (but not in males) preferred body temperature also varied among individuals born to mothers belonging to different color morphs, suggesting that a genetic correlation exists between color pattern and temperature preferences. Collectively, these findings, at least in females, are consistent with the hypothesis of multiple-trait coevolution and suggest that the different color morphs represent alternative evolutionary strategies. [source] Increased temperature and protein oxidation lead to HSP72 mRNA and protein accumulation in the in vivo exercised rat heartEXPERIMENTAL PHYSIOLOGY, Issue 1 2009Jessica L. Staib Expression of myocardial heat shock protein 72 (HSP72), mediated by its transcription factor, heat shock factor 1 (HSF1), increases following exercise. However, the upstream stimuli governing exercise-induced HSF1 activation and subsequent Hsp72 gene expression in the whole animal remain unclear. Exercise-induced increases in body temperature may promote myocardial radical production, leading to protein oxidation. Conceivably, myocardial protein oxidation during exercise may serve as an important signal to promote nuclear HSF1 migration and activation of Hsp72 expression. Therefore, these experiments tested the hypothesis that prevention of exercise-induced increases in body temperature attenuates cardiac protein oxidation, diminishes HSF1 activation and decreases HSP72 expression in vivo. To test this hypothesis, in vivo exercise-induced changes in body temperature were manipulated by exercising male rats in either cold (4°C) or warm ambient conditions (22°C). Warm exercise increased both body temperature (+3°C) and myocardial protein oxidation, whereas these changes were attenuated by cold exercise. Interestingly, exercise in both conditions did not significantly increase myocardial nuclear localized phosphorylated HSF1. Nonetheless, warm exercise elevated left-ventricular HSP72 mRNA by ninefold and increased myocardial HSP72 protein levels by threefold compared with cold-exercised animals. Collectively, these data indicate that elevated body temperature and myocardial protein oxidation promoted exercise-induced cardiac HSP72 mRNA expression and protein accumulation following in vivo exercise. However, these results suggest that exercise-induced myocardial HSP72 protein accumulation is not a result of nuclear-localized, phosphorylated HSF1, indicating that other transcriptional or post-transcriptional regulatory mechanisms are involved in exercise-induced HSP72 expression. [source] Central control of thermogenesis in mammalsEXPERIMENTAL PHYSIOLOGY, Issue 7 2008Shaun F. Morrison Thermogenesis, the production of heat energy, is an essential component of the homeostatic repertoire to maintain body temperature in mammals and birds during the challenge of low environmental temperature and plays a key role in elevating body temperature during the febrile response to infection. The primary sources of neurally regulated metabolic heat production are mitochondrial oxidation in brown adipose tissue, increases in heart rate and shivering in skeletal muscle. Thermogenesis is regulated in each of these tissues by parallel networks in the central nervous system, which respond to feedforward afferent signals from cutaneous and core body thermoreceptors and to feedback signals from brain thermosensitive neurons to activate the appropriate sympathetic and somatic efferents. This review summarizes the research leading to a model of the feedforward reflex pathway through which environmental cold stimulates thermogenesis and discusses the influence on this thermoregulatory network of the pyrogenic mediator, prostaglandin E2, to increase body temperature. The cold thermal afferent circuit from cutaneous thermal receptors ascends via second-order thermosensory neurons in the dorsal horn of the spinal cord to activate neurons in the lateral parabrachial nucleus, which drive GABAergic interneurons in the preoptic area to inhibit warm-sensitive, inhibitory output neurons of the preoptic area. The resulting disinhibition of thermogenesis-promoting neurons in the dorsomedial hypothalamus and possibly of sympathetic and somatic premotor neurons in the rostral ventromedial medulla, including the raphe pallidus, activates excitatory inputs to spinal sympathetic and somatic motor circuits to drive thermogenesis. [source] Exposure to a hot environment can activate rostral ventrolateral medulla-projecting neurones in the hypothalamic paraventricular nucleus in conscious ratsEXPERIMENTAL PHYSIOLOGY, Issue 1 2008Joo Lee Cham A major integrative site within the brain for autonomic function is the hypothalamic paraventricular nucleus (PVN). Several studies have suggested that the PVN may be involved in the responses regulating body temperature. Hyperthermia elicits redirection of blood flow from the viscera to the periphery and involves changes in sympathetic nerve activity mediated by the central nervous system. The hypothalamic PVN includes neurones that project to the rostral ventrolateral medulla (RVLM), an important autonomic region involved in the tonic regulation of sympathetic nerve activity. This pathway could contribute to the cardiovascular changes induced by hyperthermia. The PVN has a high concentration of nitrergic neurones and it is known that nitric oxide within the brain mediates heat dissipation. Thus the aims of this study were to determine whether RVLM-projecting neurones in the PVN are activated by heat and whether those neurones are also nitrergic. The results show that, compared with control conditions, exposure of conscious rats to a hot environment of 39°C significantly increased the number of neurones containing a Fos-positive nucleus (a marker of activation) and significantly increased the number of activated RVLM-projecting neurones in the PVN. Also, although heating significantly increased the number of activated nitrergic PVN neurones, triple-labelled neurones (i.e. activated, nitrergic and RVLM projecting) in the PVN were rarely observed. The results suggest that RVLM-projecting neurones in the PVN may play a role in responses to heat exposure but these are not nitrergic. [source] Metabolic Heat Production, Heat Loss and the Circadian Rhythm of Body Temperature in the RatEXPERIMENTAL PHYSIOLOGY, Issue 3 2003Roberto Refinetti Metabolic heat production (calculated from oxygen consumption), dry heat loss (measured in a calorimeter) and body temperature (measured by telemetry) were recorded simultaneously at 6 min intervals over five consecutive days in rats maintained in constant darkness. Robust circadian rhythmicity (confirmed by chi square periodogram analysis) was observed in all three variables. The rhythm of heat production was phase-advanced by about half an hour in relation to the body temperature rhythm, whereas the rhythm of heat loss was phase-delayed by about half an hour. The balance of heat production and heat loss exhibited a daily oscillation 180 deg out of phase with the oscillation in body temperature. Computations indicated that the amount of heat associated with the generation of the body temperature rhythm (1.6 kJ) corresponds to less than 1% of the total daily energy budget (172 kJ) in this species. Because of the small magnitude of the fraction of heat balance associated with the body temperature rhythm, it is likely that the daily oscillation in heat balance has a very slow effect on body temperature, thus accounting for the 180 deg phase difference between the rhythms of heat balance and body temperature. [source] Allometric scaling of maximum metabolic rate: the influence of temperatureFUNCTIONAL ECOLOGY, Issue 4 2008C. R. White Summary 1Maximum aerobic metabolic rate, measured in terms of rate of oxygen consumption during exercise (), is well known to scale to body mass (M) with an exponent greater than the value of 0·75 predicted by models based on the geometry of systems that supply nutrients. 2Recently, the observed scaling for (,M0·872) has been hypothesized to arise because of the temperature dependence of biological processes, and because large species show a greater increase in muscle temperature when exercising than do small species. 3Based on this hypothesis, we predicted that will be positively related to ambient temperature, because heat loss is restricted at high temperatures and body temperature is likely to be elevated to a greater extent than during exercise in the cold. 4This prediction was tested using a comparative phylogenetic generalized least-squares (PGLS) approach, and 34 measurements of six species of rodent (20·5,939 g) maximally exercising at temperatures from ,16 to 30 °C. 5 is unrelated to testing temperature, but is negatively related to acclimation temperature. We conclude that prolonged cold exposure increases exercise-induced by acting as a form of aerobic training in mammals, and that elevated muscle temperatures of large species do not explain the scaling of across taxa. [source] Scaling of body temperature in mammals and birdsFUNCTIONAL ECOLOGY, Issue 1 2008Andrew Clarke Summary 1We examine variation associated with phylogeny in the scaling of body temperature in endotherms, using data from 596 species of mammal and 490 species of bird. 2Among higher groups of mammals there is statistically significant scaling of body temperature with mass in Marsupialia (positive), Ferae and Ungulata (both negative). In mammalian orders where data are available for at least 10 species, scaling is negative in three orders (Carnivora, Erinaceomorpha and Artiodactyla), positive in one (Chiroptera) and not significant in seven others. There is no relationship apparent between the scaling of body temperature and the existence of gut fermentation. As expected, monotremes exhibit the lowest body temperatures, but within marsupials diprotodonts have a mean body temperature higher than several placental groups; the traditional ranking of body temperatures in the sequence monotremes , marsupials , placentals is thus misleading. 3In birds, scaling relationships are significant only for Ciconiiformes (strongly negative) and Passeriformes (weakly positive). 4When allowance is made for phylogenetic effects, there is no significant relationship between temperature in body mass in mammals overall, but an inverse and almost significant relationship in birds. 5This study indicates a complex relationship between body mass, body temperature and metabolic rate in mammals and birds, mediated through ecology. [source] |