The temporal sequence of improved mitochondrial function on the dynamics of respiration, mobility, and cognition in aged Drosophila.

Aging is associated with mitochondrial decline and reduced adenosine triphosphate (ATP) production leading to cellular dysfunction, but this is improved by long-wavelength light absorbed by cytochrome c oxidase, increasing cytochrome c oxidase activity, ATP production and improving metabolism, sensory motor function, and cognition. Yet, the sequence of these events is unknown. We give old flies a single 90-minute 670-nm pulse and measure temporal sequences of changes in respiration, ATP, motor, and cognitive ability. Respiration increased significantly 20 minutes after light initiation and remained elevated for 4 days. Measurable ATP increased at 1 hour, peaking at 3 hours, and then declined rapidly. Respiration improved before ATP increased, which indicates an early ATP sink. Flies explore environments stereotypically, which is lost with aging but is reestablished for 7 hours after light exposure. However, again, there are improvements before there are peaks in ATP production. Improved mobility and cognitive function persist after ATP levels return to normal. Hence, elevated ATP in age may initiate independent signaling mechanisms that result in improvements in aged metabolism and function.

The effects of two different doses of ultraviolet-A light exposure on nitric oxide metabolites and cardiorespiratory outcomes.

PURPOSE: The present study investigated different doses of ultraviolet-A (UV-A) light on plasma nitric oxide metabolites and cardiorespiratory variables. METHODS: Ten healthy male participants completed three experimental conditions, 7 days apart. Participants were exposed to no light (CON); 10 J cm2 (15 min) of UV-A light (UVA10) and 20 J cm2 (30 min) of UV-A light (UVA20) in a randomized order. Plasma nitrite [NO2-] and nitrate [NO3-] concentrations, blood pressure (BP), and heart rate (HR) were recorded before, immediately after exposure and 30 min post-exposure. Whole body oxygen utilization ([Formula: see text]), resting metabolic rate (RMR) and skin temperature were recorded continuously. RESULTS: None of the measured parameters changed significantly during CON (all P > 0.05). [Formula: see text] and RMR were significantly reduced immediately after UVA10 (P < 0.05) despite no change in plasma [NO2-] (P > 0.05). Immediately after exposure to UVA20, plasma [NO2-] was higher (P = 0.014) and [Formula: see text] and RMR tended to be lower compared to baseline (P = 0.06). There were no differences in [NO2-] or [Formula: see text] at the 30 min time point in any condition. UV-A exposure did not alter systolic BP, diastolic BP or MAP (all P > 0.05). UV-A light did not alter plasma [NO3-] at any time point (all P > 0.05). CONCLUSIONS: This study demonstrates that a UV-A dose of 20 J cm2 is necessary to increase plasma [NO2-] although a smaller dose is capable of reducing [Formula: see text] and RMR at rest. Exposure to UV-A did not significantly reduce BP in this cohort of healthy adults. These data suggest that exposure to sunlight has a meaningful acute impact on metabolic function.

Living in flowing water increases resistance to ultraviolet B radiation.

Ultraviolet B radiation (UV-B) is an important environmental driver that can affect locomotor performance negatively by inducing production of reactive oxygen species (ROS). Prolonged regular exercise increases antioxidant activities, which may alleviate the negative effects of UV-B-induced ROS. Animals naturally performing exercise, such as humans performing regular exercise or fish living in flowing water, may therefore be more resilient to the negative effects of UV-B. We tested this hypothesis in a fully factorial experiment, where we exposed mosquitofish (Gambusia holbrooki) to UV-B and control (no UV-B) conditions in flowing and still water. We show that fish exposed to UV-B and kept in flowing water had increased sustained swimming performance (Ucrit), increased antioxidant defences (catalase activity and glutathione concentrations) and reduced cellular damage (lipid peroxidation and protein carbonyl concentrations) compared with fish in still water. There was no effect of UV-B or water flow on resting or maximal rates of oxygen consumption. Our results show that environmental water flow can alleviate the negative effects of UV-B-induced ROS by increasing defence mechanisms. The resultant reduction in ROS-induced damage may contribute to maintain locomotor performance. Hence, the benefits of regular exercise are 'transferred' to improve resilience to the negative impacts of UV-B. Ecologically, the mechanistic link between responses to different habitat characteristics can determine the success of animals. These dynamics have important ecological connotations when river or stream flow changes as a result of weather patterns, climate or human modifications.

Lack of Melanopsin Is Associated with Extreme Weight Loss in Mice upon Dietary Challenge.

Metabolic disorders have been established as major risk factors for ocular complications and poor vision. However, little is known about the inverse possibility that ocular disease may cause metabolic dysfunction. To test this hypothesis, we assessed the metabolic consequences of a robust dietary challenge in several mouse models suffering from retinal mutations. To this end, mice null for melanopsin (Opn4-/-), the photopigment of intrinsically photosensitive retinal ganglion cells (ipRGCs), were subjected to five weeks of a ketogenic diet. These mice lost significantly more weight than wild-type controls or mice lacking rod and cone photoreceptors (Pde6brd1/rd1). Although ipRGCs are critical for proper circadian entrainment, and circadian misalignment has been implicated in metabolic pathology, we observed no differences in entrainment between Opn4-/- and control mice. Additionally, we observed no differences in any tested metabolic parameter between these mouse strains. Further studies are required to establish the mechanism giving rise to this dramatic phenotype observed in melanopsin-null mice. We conclude that the causality between ocular disease and metabolic disorders merits further investigation due to the popularity of diets that rely on the induction of a ketogenic state. Our study is a first step toward understanding retinal pathology as a potential cause of metabolic dysfunction.

Solar radiation during rewarming from torpor in elephant shrews: supplementation or substitution of endogenous heat production?

Many small mammals bask in the sun during rewarming from heterothermy, but the implications of this behaviour for their energy balance remain little understood. Specifically, it remains unclear whether solar radiation supplements endogenous metabolic thermogenesis (i.e., rewarming occurs through the additive effects of internally-produced and external heat), or whether solar radiation reduces the energy required to rewarm by substituting (i.e, replacing) metabolic heat production. To address this question, we examined patterns of torpor and rewarming rates in eastern rock elephant shrews (Elephantulus myurus) housed in outdoor cages with access to either natural levels of solar radiation or levels that were experimentally reduced by means of shade cloth. We also tested whether acclimation to solar radiation availability was manifested via phenotypic flexibility in basal metabolic rate (BMR), non-shivering thermogenesis (NST) capacity and/or summit metabolism (Msum). Rewarming rates varied significantly among treatments, with elephant shrews experiencing natural solar radiation levels rewarming faster than conspecifics experiencing solar radiation levels equivalent to approximately 20% or 40% of natural levels. BMR differed significantly between individuals experiencing natural levels of solar radiation and conspecifics experiencing approximately 20% of natural levels, but no between-treatment difference was evident for NST capacity or Msum. The positive relationship between solar radiation availability and rewarming rate, together with the absence of acclimation in maximum non-shivering and total heat production capacities, suggests that under the conditions of this study solar radiation supplemented rather than substituted metabolic thermogenesis as a source of heat during rewarming from heterothermy.

Temperature and UV-B-insensitive performance in tadpoles of the ornate burrowing frog: an ephemeral pond specialist.

Animals may overcome the challenges of temperature instability through behavioural and physiological mechanisms in response to short- and long-term temperature changes. When ectotherms face the challenge of large diel temperature fluctuations, one strategy may be to reduce the thermal sensitivity of key traits in order to maintain performance across the range of temperatures experienced. Additional stressors may limit the ability of animals to respond to these thermally challenging environments through changes to energy partitioning or interactive effects. Ornate burrowing frog (Platyplectrum ornatum) tadpoles develop in shallow ephemeral pools that experience high diel thermal variability (>20°C) and can be exposed to high levels of UV-B radiation. Here, we investigated how development in fluctuating versus stable temperature conditions in the presence of high or low UV-B radiation influences thermal tolerance and thermal sensitivity of performance traits of P. ornatum tadpoles. Tadpoles developed in either stable (24°C) or fluctuating temperatures (18-32°C) under high or low UV-B conditions. Tadpoles were tested for upper critical thermal limits, thermal dependence of resting metabolic rate and maximum burst swimming performance. We hypothesised that developmental responses to thermal fluctuations would increase thermal tolerance and reduce thermal dependence of physiological traits, and that trade-offs in the allocation of metabolic resources towards repairing UV-B-induced damage may limit the ability to maintain performance over the full range of temperatures experienced. We found that P. ornatum tadpoles were thermally insensitive for both burst swimming performance, across the range of temperatures tested, and resting metabolic rate at high temperatures independent of developmental conditions. Maintenance of performance led to a trade-off for growth under fluctuating temperatures and UV-B exposure. Temperature treatment and UV-B exposure had an interactive effect on upper critical thermal limits possibly due to the upregulation of the cellular stress response. Thermal independence of key traits may allow P. ornatum tadpoles to maintain performance in the thermal variability inherent in their environment.

Physiological effects of bioceramic material: harvard step, resting metabolic rate and treadmill running assessments.

Previous biomolecular and animal studies have shown that a room-temperature far-infrared-rayemitting ceramic material (bioceramic) demonstrates physical-biological effects, including the normalization of psychologically induced stress-conditioned elevated heart rate in animals. In this clinical study, the Harvard step test, the resting metabolic rate (RMR) assessment and the treadmill running test were conducted to evaluate possible physiological effects of the bioceramic material in human patients. The analysis of heart rate variability (HRV) during the Harvard step test indicated that the bioceramic material significantly increased the high-frequency (HF) power spectrum. In addition, the results of RMR analysis suggest that the bioceramic material reduced oxygen consumption (VO2). Our results demonstrate that the bioceramic material has the tendency to stimulate parasympathetic responses, which may reduce resting energy expenditure and improve cardiorespiratory recovery following exercise.

Resting energy expenditure in head and neck cancer patients before and during radiotherapy.

BACKGROUND & AIMS: Weight loss is a frequently observed problem in patients with head and neck cancer (HNC) during radiotherapy. It is still to be assessed whether hypermetabolism is contributing to this problem. The aim of this study was to investigate hypermetabolism before radiotherapy, and changes in resting energy expenditure (REE) in HNC patients during radiotherapy. METHODS: REE was measured by indirect calorimetry in 71 patients with HNC before radiotherapy, after 3 and 6 weeks of radiotherapy, and 3 months after radiotherapy. The association between REE and tumour stage, CRP, and prior tumour surgery was analyzed by linear regression analyses. Forty healthy control subjects were one-to-one matched to 40 patients by gender, age and fat free mass (FFM) index to compare REE. RESULTS: Before radiotherapy, REE was not significantly different between patients and controls, neither in absolute values (1568 ± 247 vs. 1619 ± 244 kcal/d; p = 0.29), nor after weight-adjustment (22.1 ± 3.5 vs. 21.5 ± 3.3 kcal/kg, p = 0.42) or FFM-adjustment (31.5 ± 4.9 vs. 30.7 ± 4.5 kcal/kg, p = 0.38). REE was independent of tumour stage, CRP, and prior tumour surgery. REE (kcal/d) decreased during radiotherapy and thereafter by 9% from pre-radiotherapy (p < 0.01). Weight and FFM also decreased significantly over time (p < 0.001). REE adjusted for FFM decreased in the first 3 weeks of radiotherapy with 4% (B = -1.39 kcal/kg FFM, p < 0.01), increased at the end of radiotherapy and decreased again 3 months after radiotherapy (B = -1.31 kcal/kg FFM, p = 0.04). CONCLUSIONS: Head and neck cancer patients had normal REE before radiotherapy. During radiotherapy, REE decreased continuously with ongoing weight loss. However, weight loss is not the only explaining factor, since REE expressed per kg FFM showed a much more divergent course which is currently unexplained.

Short photoperiod enhances thermogenic capacity in Brandt's voles.

Environmental cues play important roles in the regulation of an animal's physiology and behavior. In the present study, we examined the effects of short photoperiod (SD) on body weight as well as on several physiological, hormonal, and biochemical measures indicative of thermogenic capacity to test our hypothesis that short photoperiod stimulates increases in thermogenesis without cold stress in Brandt's voles. SD voles showed increases in basal metabolic rate (BMR) and nonshivering thermogenesis (NST) during the 4-week photoperiod acclimation. At the end, these voles (SD) had lower body weights, higher levels of cytochrome C oxidase (COX) activity and mitochondrial uncoupling protein-1 (UCP1) contents in brown adipose tissues (BAT), and higher concentrations of serum tri-iodothyronine (T3) and thyroxine (T4) compared to LD voles. No differences were found between male and female voles in any of the above-mentioned measurements. Together, these data indicate that SD experience enhances thermogenic capacity similarly in males and females of Brandt's voles.

Nutritional consequences of radiotherapy in nasopharynx cancer patients.

Nasopharynx cancer (NPC) occurs frequently in southern China. Radiotherapy (RT) is the standard treatment for this cancer, and weight loss is commonly observed during and for a prolonged period after RT. The determinants of this phenomenon are not well known. The nutritional status of 38 NPC patients was assessed serially before and for a 6-mo period after RT. Body weight, body composition (by dual X-ray absorptiometry), basal metabolic rate (BMR, by indirect calorimetry), and calorie intake (by 3-day dietary record) were documented at pre-RT (T0), end-RT (T1), 2 mo post-end-RT (T2), and 6 mo post-end-RT (T3). The BMI at end-RT was 21.5 +- 3.7 kg/m2 (range = 13.7-27.9 kg/m2) and was significantly lower than that at pre-RT (P < 0.001). Body weight at T1-T3 was significantly lower than that at T0 (P < 0.001). Mean percentage weight loss was 10.8% at end-RT. Fifty-five percent of patients (20 of 30) had 10% weight loss by the end of RT. BMR corrected for body weight did not change significantly among the four time points, but BMRs corrected for lean body mass at T2 and T3 were significantly lower than that at T0 (P < 0.01). Patients' calorie intake generally declined from T0 to T1 (from 1,857 P < 411 kcal to 11,68 +- 549 kcal, P < 0.001) and then increased from T1 to T3. The calorie intakes at T2 and T3 were not significantly different from that at T0 but were significantly higher than that at T1. Patients were in negative energy balance before, during, and up until 6 mo after RT. The recovery in body weight lagged behind the recovery of dietary intake. Eighty-two percent of NPC patients had significant weight loss and was in negative energy balance at the end of RT, which persisted for at least 6 mo. This finding suggests that there is room for improvement in the nutritional status of patients with NPC treated with RT.

Effect of photoperiod on metabolic rate in a subtropical population of Drosophila melanogaster.

1. Descendents of a Florida, U.S.A. population of Drosophila melanogaster were reared under short (8 hr light: 16 hr dark) and long (16 hr light: 8 hr dark) photoperiods. 2. Flies reared under short photoperiods had higher rates of metabolism at 21 degrees C. 3. Because genetic background (iso-female line) affects metabolic rates, statistical control through analysis of covariance was necessary to isolate the effects of photoperiod on metabolic rates. 4. These results on a subtropical population of D. melanogaster are similar to those found on a temperate population of the same species.

[Correlation between the complex of body reactions to exposure to acute hypoxia and individual radiosensitivity in irradiation at a dose of 200 Gr]. / Sootnoshenie mezhdu kompleksom reaktsii organizma na vozdeistvie ostroi gipoksii i individual'noi radiochuvstvitel'nost'iu pri obluchenii v doze 200 Gr.

A study was made of a correlation between the response of basal metabolism to acute hypoxia and the life span of rats after irradiation resulting in the development of a cerebral form of radiation sickness. The more radiosensitive animals consumed a larger amount of oxygen, exhaled a lesser amount of carbon dioxide, and showed an increased normal expiratory exchange per minute. After the effect of acute hypoxia all the indices under study exhibited an opposite picture.

[Relation between the changes in basal metabolism in acute hypoxia and response to subsequent irradiation with 200 Gy]. / O sootnoshenii mezhdu izmeneniem osnovnogo obmena pri ostroii gipoksii i reaktsiei organizma na posleduiushchee obluchenie v doze 200 Gr.

The author considers the possibility of prediction of the outcome of radiation sickness after 200 Gy irradiation on the basis of changes in basal metabolism produced by acute hypoxia. It was shown that the animals exhibiting the increased basal metabolism after the effect of hypoxia were more radioresistant. The correlation coefficient was--0,79.

Effect of ultraviolet radiation and kinins on oxygen uptake by tissue slices and on basal metabolism in rabbits.

The experiments were carried out on 85 rabbits in 15 groups of 5-8 animals in each. The different groups received: 1) ultraviolet radiation once during 45 minutes or daily during 10 minutes for 6 weeks, 2) bradykinin intravenously 10 microgram/kg, 3) kallikrein 5 B.U./kg intramuscularly during 3 weeks. The levels of kinins and kininogen, and the activity of kallikrein and kininases were determined in the blood several times during 24 hours after radiation exposure, and at intervals of two weeks during long-term exposure to radiation. In the same time periods after exposure the basal metabolism and the uptake of oxygen by slices of the kidneys, liver, heart and skin in vitro were determined. Determinations of aerobic metabolism were carried out also after bradykinin injection and at weekly intervals during kallikrein administration. It was found that: 1) after exposure to ultraviolet radiation there was a high rise in the level of kinins and a fall of kininogen, the activity of kininogenases was raised and that of kininases was decreased, while oxygen uptake was reduced moderately; 2) exogenous bradykinin and endogenous kinins reduced oxygen uptake in vivo and in vitro.

Prediction of interindividual differences in radiosensitivity in mammals.

Prediction of individual radiosensitivity of mammals is of interest to radiobiology on the one hand and it is also important to the clinical use of radiation. The author has reported that there is a relationship between radiosensitivity in individual animals and its homeostatic activity that allows predicting individual radiosensitivity. In the present report, a phenomenon of metabolism was used to measure the homeostatic activity of an individual mouse DBA strain, 90 days old; that is, the metabolic rate was calculated from daily diet or water consumption, and body weight. Each mouse fasted completely for one day and the ratio between metabolic rates just before and just after the fast (value after fast/value before fast) was calculated to use as the index of homeostatic activity of each mouse. One week after fasting, the mice were exposed to X-rays of 500 R and the ratio of metabolic rates just before and just after exposure was calculated again. Ten days after exposure the mice were sacrificed and the spleens were fixed in Bouin's solution. After fixing, the splenic weight was measured and an endogenous spleen colony count (more than 1 mm diameter) was made, which was one response to radiation damage to the hematopoietic system. The results, summarized from several repeated experiments are given in the table below: [table: see text].