Relationship between Urine Creatinine and Urine Osmolality in Spot Samples among Men and Women in the Danish Diet Cancer and Health Cohort

Assays of urine biomarkers often use urine creatinine to account for urinary dilution, even though creatinine levels are influenced by underlying physiology and muscle catabolism. Urine osmolality—a measure of dissolved particles including ions, glucose, and urea—is thought to provide a more robust marker of urinary dilution but is seldom measured. The relationship between urine osmolality and creatinine is not well understood. We calculated correlation coefficients between urine creatinine and osmolality among 1375 members of a subcohort of the Danish Diet, Cancer, and Health Cohort, and within different subgroups. We used linear regression to relate creatinine with osmolality, and a lasso selection procedure to identify other variables that explain remaining variability in osmolality. Spearman correlation between urine creatinine and osmolality was strong overall (ρ = 0.90; 95% CI: 0.89–0.91) and in most subgroups. Linear regression showed that urine creatinine explained 60% of the variability in urine osmolality, with another 9% explained by urine thallium (Tl), cesium (Cs), and strontium (Sr). Urinary creatinine and osmolality are strongly correlated, although urine Tl, Cs, and Sr might help supplement urine creatinine for purposes of urine dilution adjustment when osmolality is not available.

The Effects of Different Exercise Intensities and Modalities on Cortisol Production in Healthy Individuals: A Review

Cortisol is a hormone that is secreted in response to physiological stress. Exercise contributes significantly to changes in circulating cortisol concentrations. With exercise, there is increased activation of the sympathetic system to stimulate the release of adrenocorticotropic hormone, which releases cortisol into the blood. Current research has predominately studied the effects that aerobic exercise and resistance training have on cortisol production. Prolonged aerobic exercise, especially at higher intensities, significantly elevates cortisol concentrations when compared to similar duration and intensities of resistance exercise. Age, gender, physical fitness level, exercise intensity, training status, and modality are all variables that influence the production of cortisol. Elevated cortisol concentrations are highly indicative of muscle catabolism, increasing the loss of lean muscle tissue. This is a significant health concern for the growing elderly population. The rate of cortisol production changes as an individual ages and has been observed to have differing responses to exercise intensities in males and females. Cortisol production is correlated with exercise intensity and duration but does not increase the same across all exercise intensities. Higher exercise intensities and duration appear to be the main contributing factors that influence the production of cortisol, increasing the potential for muscle catabolism and muscle loss.

Abstract 23: Body Fluid And Sodium Loss Leads To Aldosterone Hypersecretion And Muscle Catabolism In Hepatocellular Carcinoma Rats.

Background: The number of cancer survivors coincides with cardiovascular diseases is increasing, therefore, we are promoting the concept of “Onco-Hypertension” to clarify the mechanism linking cancer and blood pressure. In this study, we evaluated body osmolyte and water imbalance in hepatocellular cancer (HCC) model rats. Methods: Wistar rats were administered diethylnitrosamine (DEN) (1.5 μg/day, p.o.), a carcinogenic drug, for 8 weeks to establish liver cancer. Three weeks after the completion of DEN administration, we investigated blood pressure, tissue osmolyte and water content, and its association with aldosterone secretion. Results: HCC rats significantly reduced blood pressure, skin sodium, potassium, and water content. In the carcass (muscle + bone), dry weight, sodium, potassium, and water content were dramatically reduced without changing bone mass in HCC rats, suggesting that HCC causes muscle wasting to supply osmolyte and water for the dehydrated organs. These osmolytes and water loss were significantly associated with increased urinary aldosterone excretion. Supplementation of 0.25% salt water to drink improved body sodium and water loss and muscle wasting in HCC rats, which were completely suppressed by treatment with spironolactone (75 mg/kg/day, p.o.), a mineralocorticoid receptor (MR) blocker. Conclusion: These findings suggest that HCC causes body osmolyte and water loss, which leads to aldosterone hypersecretion and muscle catabolism to compensate for dehydration. A relatively small amount of salt supplement ameliorates the HCC-induced dehydration and muscle wasting via aldosterone/MR-mediated sodium and water restoration.

Athletic, muscular and hormonal evaluation in CrossFit® athletes using the “Elevation Training Mask”

Introduction: The possibility of performing intense workouts without falling into states of chronic fatigue stimulates the use of devices that improve muscular and hormonal functionality in athletes. The Elevation Training Mask (Training Mask LLC) (ETM) allows the application of hypoxia during exercise. The ETM is integrated into training routines increasing the physical stimulus to improve performance. Objective: We evaluated the impact of ETM on Workouts of the Day (WODs), muscular and hormonal behavior in Crossfit® athletes. Material and method: Prospective cohort study. During 12 weeks 20 Crossfit® athletes trained 60 minutes 3 days a week were randomly divided into 2 groups, control group (CG) (n=10) and ETM group (EG) (n=10) applying an additional progressive simulated altitude between 914 and 2743 meters. WODs (press, squat, deadlift, total CF and grace), macular markers: lactate dehydrogenase (LDH); creatine kinase (CK); myoglobin (Mb) and hormones: testosterone (T); cortisol (C), were evaluated at 2 time points of the study: day 1 (T1) and day 84 (T2). Results: All WODs and parameters LDH, CK, Mb, T and C showed no significant difference (p>0.05) in the time group interaction. In EG, a substantially lower percentage change (Δ) between T1 and T2 was observed in Mb (-16.01±25.82%), CK (6.16±26.05%) and C (-0.18±4.01%) than in CG (Mb: -094±4.39%; CK: 17.98±27.19%; C: 4.56±3.44%). The Δ T1-T2 in the WODs were similar. Conclusion: After 12 weeks of training under simulated hypoxia conditions with ETM there are no improvements in athletic performance assessed by WODs. However, the greater tendency to decrease Mb, CK and C, after using ETM, could stimulate recovery and indicate a lower muscle catabolism of the Crossfit® athlete in the long term.

Blood lipid profile changes in type 2 diabetic rats after tail suspension and reloading

Purpose The effects of the tail suspension and reloading on the protein and lipid metabolism in muscle and blood in type 2 diabetes mellitus (T2DM) are unclear. This study evaluated the hypothesis that skeletal muscle catabolism is greater in T2DM than in non-diabetes mellitus (non-DM) rats and that the activity-dependent changes in the intramuscular lipid accumulation and blood lipid profile are poorer in T2DM than in non-DM rats. Methods T2DM and non-DM rats were suspended for two weeks followed by reloading for two weeks. The muscle and blood were then examined. Results In contrast to our hypothesis, there was no marked difference between the T2DM and non-DM groups in terms of the skeletal muscle catabolism and activity-dependent changes in intramuscular lipid accumulation. However, the blood lipid profile increased in the T2DM group compared to the non-DM group. One interesting finding in this study was the decrease in non-high-density lipoprotein (non-HDL) cholesterol levels after one week of reloading followed by a significant increase in the non-HDL cholesterol levels after two weeks of reloading in the T2DM group. Conclusion These results suggest that a dramatic increase in activity after a period of inactivity may rapidly improve the blood lipid profile in T2DM rats.

Wild Bornean orangutans experience muscle catabolism during episodes of fruit scarcity

Pronounced temporal and spatial variation in the availability of food resources can produce energetic deficits in organisms. Fruit-dependent Bornean orangutans face extreme variation in fruit availability and experience negative energy and protein balance during episodes of fruit scarcity. We evaluate the possibility that orangutans of different sexes and ages catabolize muscle tissue when the availability of fruit is low. We assess variation in muscle mass by examining the relationship between urinary creatinine and specific gravity and use the residuals as a non-invasive measure of estimated lean body mass (ELBM). Despite orangutans having a suite of adaptations to buffer them from fruit scarcity and associated caloric deficits, ELBM was lower during low fruit periods in all age-sex classes. As predicted, adult male orangutans had higher ELBM than adult females and immatures. Contrary to expectation, flanged and unflanged males did not differ significantly in ELBM. These findings highlight the precarity of orangutan health in the face of rapid environmental change and add to a growing body of evidence that orangutans are characterized by unique metabolic traits shaped by their unpredictable forest environment.

Burn-induced hypermetabolism and skeletal muscle dysfunction

Critical illnesses, including sepsis, cancer cachexia and burn injury, invoke a milieu of systemic metabolic and inflammatory derangements that ultimately results in increased energy expenditure leading to fat and lean mass catabolism. Burn injuries present a unique clinical challenge given the magnitude and duration of the hypermetabolic response in comparison to other forms of critical illness, which drastically increase the risk of morbidity and mortality. Skeletal muscle metabolism is particularly altered as a consequence of burn-induced hypermetabolism as it primarily provides a main source of fuel in support of wound healing. Interestingly, muscle catabolism is sustained long after the wound has healed, indicating that additional mechanisms beyond wound healing are involved. In this review, we discuss the distinctive pathophysiological response to burn injury with a focus on skeletal muscle function and metabolism. We first examine the diverse consequences on skeletal muscle dysfunction between thermal, electrical and chemical burns. We then provide a comprehensive overview of the known mechanisms underlying skeletal muscle dysfunction that may be attributed to hypermetabolism. Lastly, we review the most promising current treatment options to mitigate muscle catabolism, and by extension improve morbidity and mortality, and end with future directions which have the potential to significantly improve patient care.

A comparison of haematological and biochemical blood indices between the Žemaitukai and Arabian horses participating in endurance competitions

The study was conducted on 30 clinically healthy Arabian horses and 28 Žemaitukai horses that competed in endurance race over the same distance (40 km). Blood samples were taken before and immediately after the exercise. The environmental conditions during the competitions varied, with a mean temperature of 22.5 °C and a mean relative humidity of 73.20%. The Žemaitukai horses showed lower haematological values and increased muscle catabolism after exercise. Arabian horses have higher aerobic capacity compared to the Žemaitukai horses which probably contributes to their superior low- to moderate-intensity exercise performance. Serum activity of muscle enzymes suggested that the muscle tissue of the Arabian horses has higher tolerance for exercise-induced muscle catabolism and lower muscle catabolism than that of muscle tissue of the Žemaitukai horses. Further studies need to be carried out to identify the diferences in muscle tissue of both breeds.