Relationship between change in core temperature and change in cortisol and TNFα during exercise

The combined thermal load created by exercise and a hot environment is associated with an exaggerated core temperature response. The elevated core temperature is believed to increase the total stress of the exercise. Increased stress during exercise has been associated with increased levels of cortisol. The association of cortisol with increased inflammatory responses following exercise in the heat is equivocal. Thus, the purpose of the current investigation was to explore the relationship between increases in rectal temperature (T_re) and TNFα and cortisol. To induce T_re changes, 8 male subjects (mean±SD, age=23.6±2 yr, VO₂max=52.8±3.7 mL/kg/min, BMI=24.2±1.9) participated in two 40 min trials of cycle ergometry at 65% of VO₂peak immersed to chest level in cool (25 °C) and warm (38.5 °C) water. T_re was monitored throughout each trial, with blood samples taken immediately pre and post of each trial. Neither cortisol nor TNFα changed significantly during exercise in the cool water; however, in the warm trial, both cortisol and TNFα significantly increased (p<0.004). Concordance correlations (R_c) between Δ cortisol and Δ TNFα indicated a strong but non-significant correlation (R_c=0.833, p=0.135). In conclusion, changes in core temperature may be impacting the relationship between exercise induced changes in cortisol and TNFα. Therefore, acute moderate-intensity exercise (40 min or less) in warm water impacts the stress and inflammatory response. Understanding this is important because exercise load may need to be adjusted in warm and hot environments to avoid the negative effects of elevated stress and inflammation response.     

Effect of short‐term underfeeding on weight of splanchnic organs in ewes

We assessed the effect of short‐term underfeeding on weight and protein mass of splanchnic tissues in adult ewes submitted to a factorial experimental design. In a pre‐experimental period, 18 ewes divided into 2 groups of 9 were fed a second cut of natural grassland hay during 4 weeks at 112 or 38% of their energy maintenance requirements. Three ewes of each group were then fed the same hay during 4 weeks at either low (group L), moderate (group M) or high intake (group H), corresponding to 38, 75 or 112% of their energy maintenance requirements, respectively, then slaughtered. Fresh weight and protein mass of splanchnic organs were measured. No carry‐over effect of the pre‐experimental level of intake on weight and protein mass was observed for any splanchnic organs. Splanchnic tissues contributed at 10.7 and 8.6% to the decrease in live weight for groups M and L, respectively. The decrease in weight of splanchnic tissues (‐15%) was mainly attributed to reticulorumen (‐23%), liver (‐21%), and at a lesser extent small intestine (‐11%). No large change in the mass ratio between mucosa and muscular‐sercsa in both dorsal and ventral sacs occurred in the rumen wall. These results are discussed together with previous published results on long‐term underfed ewes, and suggest that the decrease in energy expenditure in whole animal induced by underfeeding is mainly related to the decrease in splanchnic weight at short‐term, and to the decrease in other tissues at long‐term, splanchnic weight being stabilized.     

Chemical changes in cell envelope and poly-β-hydroxybutyrate during short term starvation of a marine bacterial isolate

Qualitative and quantitative changes were observed in lipids, poly--hydroxybutyrate (PHB), and a cell wall peptidoglycan consitutent in a marine bacterial isolate during starvation for 24 h in an energy and nutrient-free medium. While the amount and composition of the membrane fatty acids fluctuated within the first hours of starvation, the total amount of fatty acids decreased during the starvation period. Furthermore, the ratio of monounsaturated to saturated fatty acids decreased and the proportion of short chain fatty acids increased. In the very early phase of starvation the bacteria contained PHB, which had been accumulated during the growth phase, but after 3 h no PHB was detected. Cells starved for phosphorus showed a different pattern as PHB was initially accumulated and did not decrease until 5 h of starvation. Synthesis of the cell wall amino acid d-alanine was initiated during the first phase of starvation. The effects of these changes on membrane fluidity and uptake of substrates as well as the use of fatty acids and PHB as energy resources during starvation are discussed.Non-common abbreviations FID flame ionization detector - GC gas chromatography - HFBA heptafluorobutyric anhydride - MS mass spectrometry - NSS nine salt solution - PHB poly--hydroxybutyrate - PFB pentafluorobenzylbromide     

Age-related changes in the association of sleep satisfaction with sleep quality and sleep–wake pattern

Sleep and Biological Rhythms - Age-specific relationship of sleep–wake pattern with night sleep satisfaction was examined to address a question of why sleep satisfaction does not accurately...     

Persistence of synchronization of the daily rhythms of body temperature and sleep‐wake in college students

Abstract

Bedtime, risetime, and body temperature of college students exposed to a regular 24‐h life schedule were recorded for 22–25 consecutive days. Average bedtime was 1:37 am, average risetime was 8:53 am, and average temperature acrophase was 5:01 pm. There was no evidence of desynchronization of the body temperature and activity rhythms.     

Laboratory studies of the effects of short‐term isolation on aggressive behaviour in fish

A review of the literature on the effects of short‐term isolation on aggressive behaviour in a variety of fishes reveals different approaches and often conflicting results. This diversity is attributed to a number of factors, including different experimental conditions and specific differences in habitat, behavioural repertoire and social system. Some common trends are identified and the main hypotheses proposed to account for the different results are discussed. Some methodological issues as well as proximate and ultimate mechanisms are examined, and the importance of a standard experimental paradigm in comparative research emphasised.     

Do changes in feed intake or ambient temperature cause changes in cattle rumen temperature relative to core temperature?

A technique was developed to monitor and describe the relationship between core body temperature (T_c) and rumen temperature (T_rum) in cattle. This relationship was assessed in cattle subjected to varying environmental temperatures and subsequent variations in dry matter and water intake. Increasing the environmental wet bulb temperature (WBT) from ambient conditions (approximately 15 °C WBT) to mild heat stress conditions (25 °C WBT) caused an increase in both T_c and T_rum with significant decreases in feed intake and increases in water consumption. Despite increases in both T_c and T_rum, reductions in dry matter intake, and an increase in water consumption, the relationship between T_c and T_rum did not change.     

Is sleep per se a zeitgeber in humans?

It is not clear whether shifting of sleep per se, without a concomitant change in the light-dark cycle, can induce a phase shift of the human circadian pacemaker. Two 9-day protocols (crossover, counterbalanced order) were completed by 4 men and 6 women (20-34 years) after adherence to a 2330 to 0800 h sleep episode at home for 2 weeks. Following a modified baseline constant routine (CR) protocol on day 2, they remained under continuous near-darkness (< 0.2 lux, including sleep) for 6 days. Four isocaloric meals were equally distributed during scheduled wakefulness, and their timing was held constant. Subjects remained supine inbed from 2100 to 0800 h on all days; sleep was fixed from 2330 to 0800 h in the control condition and was gradually advanced 20 min per day during the sleep advance condition until a 2-h difference had been attained. On day 9, a 25 to 27 h CR protocol (approximately 0.1 lux) was carried out. Phase markers were the evening decline time of the core body temperature (CBT) rhythm and salivary melatonin onset (3 pg/ml threshhold). In the fixed sleep condition, the phase drift over 7 days ranged from +1.62 to -2.56 h (for both CBT and melatonin rhythms, which drifted in parallel). The drifts were consistently advanced in the sleep advance schedule by +0.66 +/- 0.23 (SEM) h for CBT (p = 0.02) and by 0.27 +/- 0.14 h for melatonin rhythms (p = 0.09). However, this advance was small to medium according to effect size. Sleep per se may feed back onto the circadian pacemaker, but it appears to be a weak zeitgeber in humans.     

Absorption and metabolism of short‐chain fatty acids in ruminants

Short‐chain fatty acids (SCFA), viz. acetate, propionate and butyrate are quantitatively important substrates in ruminant energy metabolism. In the reviewed literature, 16–44% of ME intake was recovered as portal appearance of SCFA. This is considerably lower than expected when related to the estimated intra‐gastric flux of SCFA. The discrepancy is caused by portal drained viscera metabolism of arterially abundant metabolites e.g., acetate and the metabolism of acetate and butyrate to acetoacetate and D‐3‐hydroxybu‐tyrate in the absorptive epithelia. Even though considerable variations between experiments on acetate and propionate appearance are found, there seems to be a great deal of evidence that the proportion of gastroin‐testinally produced acetate and propionate absorbed to the portal blood is 50–75%. The portal recovery of butyrate has been found to be between 10 and 36% dependent on intraruminal infusion rate.

It is concluded that major parts of acetate and propionate are directly absorbed to the portal vein. The true absorption rate of acetate can only be estimated by taking the portal drained viscera metabolism of arterial actetate into account. Butyrate is generally found to have a low recovery in the portal vein, but the production of D‐3‐hydroxybutyrate seems to be underestimated in major parts of the literature. It is therefore necessary to measure portal appearance as well as portal drained viscera metabolism to assess the quantitative as well as the qualitative contribution of SCFA and SCFA metabolites to whole animal metabolism.     

Short‐term fluctuations in death by cause,temperature, and income in the United States, 1930–1985

Abstract

Disclosures that this decade has had the five hottest years ever recorded globally raise concern that extreme temperatures might be associated with higher mortality. An analysis of fluctuations in annual cause‐specific deaths, seasonal temperatures, and annual income per capita in Massachusetts, Michigan, Washington, Utah, North Carolina, and Mississippi, 1930 to 1985, suggests that, on the contrary, a temperature increase throughout the year was associated with fewer deaths from all causes combined, including deaths from infectious diseases, heart diseases, cerebrovascular diseases, pneumonia, and influenza. An average temperature increase of one degree Fahrenheit was associated with a more than 2 per cent decline in deaths from pneumonia and influenza. The only category of deaths showing no significant association was death from malignant neoplasms. Compared to spring, summer, and fall temperature fluctuations, unusually cold winter temperatures had the strongest fatal effects, but only in North Carolina and Mississippi. The greatest cumulative temperature effects on mortality were found in the same two states. Controlling for annual fluctuations in income per capita did not influence the relationship between temperature and mortality. There was evidence suggesting that the level of wealth ameliorated the fatal effects of extreme temperatures. In conclusion, unusually warm weather was followed by fewer deaths; unusually cold weather, by more deaths.     

Cadmium‐induced apoptosis and phenotypic changes in mouse thymocytes

At present cadmium (Cd)induced immunotoxicity and the mechanisms involved have not been fully elucidated. The main objective of the present study is to explore the apoptogenic property of Cd in primary cultured mouse thymocytes and its effect on cell surface marker expression and phenotypic changes. Cdinduced thymocyte apoptosis was determined by TdTmediated dUTP nick end labeling (TUNEL) assay, DNA content/cell cycle analysis and DNA gel electrophoresis. The results showed that Cd was able to cause apoptosis in mouse thymocytes in a time and dosedependent manner. Moreover, different subsets of thymocytes possessed different susceptibility to the apoptotic effect of Cd, in the order of CD8⁺ > CD4^–CD8^– (double negative cells, DN) > CD4⁺CD8⁺ (double positive cells, DP) > CD4⁺. Cd treatment also altered thymocyte surface marker expression, leading to evident phenotypic changes. Such changes were characterized by a decline in DP cells and a marked decrease in CD4⁺/CD8⁺ ratio, mainly due to a significant increase in CD8⁺ subsets. These observations help to obtain a better understanding of the immunotoxic and immunomodulatory effects of Cd.     

Physiological changes in successive pregnancies and birth‐order effects

Abstract

An analysis of mortality rates documents that the well‐established female advantage in mortality continues to increase. Data from the U.S. census show that the sex differential in mortality has increased from 1.69 in 1963 to 1.82 in 1976. The age groups which show the most pronounced changes are youth (15–24), young adults (25–34), and old persons (75–84). Following Enterline (1961), we assess the major causes of death within each of these age groups in terms of their relative contributions to changing sex ratios. The major factors among young persons, apart from declining maternal mortality, are found to involve violent deaths, especially traffic accidents and suicide. Among old persons, death rates in general have declined, but advances in medical technology appear to have been more beneficial for older women than for older men, supporting the hypothesis of a biological superiority among women. However, death rates for malignant neoplasms have increased for older women as well as older men, suggesting that changing life styles may eventually have an impact on female mortality. The data suggest a need for additional research concerning the increase in violent deaths among young women and the potential increase in cancer deaths among older women.     

Association between the plasma proteome and plasma α-tocopherol concentrations in humans

Vitamin E is a lipophilic antioxidant that has been inversely associated with certain chronic diseases; however, the biological processes regulated by this vitamin have not been fully elucidated. The objective of the present study was to examine the association between the most biologically active and abundant form of vitamin E in the circulation, α-tocopherol, and the plasma proteome. Subjects were from the Toronto Nutrigenomics and Health Study and included men and women (n=1,022) who completed a general health and lifestyle questionnaire and 196-item food frequency questionnaire, and provided a fasting blood sample. Plasma α-tocopherol concentrations were measured by high-performance liquid chromatography and 54 plasma proteins were assayed by a mass spectrometry-based multiple reaction monitoring method. Analysis of covariance was used to compare mean concentrations of plasma proteins across tertiles of α-tocopherol. Plasma concentrations of apolipoprotein C-III, fibrinogen alpha, beta, and gamma chains, fibronectin and fibrinopeptide A were significantly and positively associated with plasma α-tocopherol, while intermediate levels of α-tocopherol were significantly associated with higher levels of alpha-1B-glycoprotein (all P<.0009). These findings show that circulating levels of α-tocopherol are significantly associated with specific plasma proteins and suggest novel physiological effects of vitamin E.     

Relationship between α-L-fucosidase deficiency in plasma and α-L-fucosidase activity in leukocytes

Summary After testing a population sample of 185 hospitalized Italian children for the plasma -L-fucosidase deficiency and establishing an approximate threshold value between heterozygotes and wild-type homozygotes, we analyzed by two statistical methods the distribution of the two genotypes. The results obtained by probit analysis agree with threshold and average values expected on the basis of the Hardy-Weinberg equilibrium.In addition, the level of -fucosidase in leukocytes of 12 individuals with deficiency of -fucosidase in plasma was found to be significantly lower than that of 61 controls (P<0.005). These results indicate that the mutation(s) causing a deficiency of -fucosidase in plasma is (are) also expressed in leukocytes.     

Circadian rhythm of activity and sleep‐wakefulness in elderly institutionalized persons

Abstract

The circadian rhythms of blood pressure (BP) and heart rate (HR) were documented in 30 patients for a 24‐hour period before and during the 24 hours that included unilateral surgery for senile cataract or retinal detachment. The patients were premedicated with diazepam. Anaesthesia was induced at a fixed time (09.00) in all patients with thiopentone, and muscle relaxation was with pancuronium. Maintenance was with enflurane in 15 patients and with fentanyl and droperidol in the rest. Though the intraoperative changes in haemodynamic parameters were dissimilar with the two types of maintenance agents, but both types had a similar effect on the circadian rhythms of blood pressure and heart rate. Whereas preoperatively the BP and HR circadian rhythms were nearly in phase, with their peaks in the late morning to early afternoon, the postoperative rhythms underwent a dissociation to a phase shift in the BP 24‐h pattern. The phase effect may be hypothetically attributed to direct pharmacological actions or to masking effects.