The effect of a multidisciplinary weight loss program on renal circadian rhythm in obese adolescents

Adolescent obesity is a serious health problem associated with many comorbidities. Obesity-related alterations in circadian rhythm have been described for nocturnal blood pressure and for metabolic functions. We believe renal circadian rhythm is also disrupted in obesity, though this has not yet been investigated. This study aimed to examine renal circadian rhythm in obese adolescents before and after weight loss. In 34 obese adolescents (median age 15.7 years) participating in a residential weight loss program, renal function profiles and blood samples were collected at baseline, after 7 months, and again after 12 months of therapy. The program consisted of dietary restriction, increased physical activity, and psychological support. The program led to a median weight loss of 24 kg and a reduction in blood pressure. Initially, lower diurnal free water clearance (- 1.08 (- 1.40-- 0.79) mL/min) was noticed compared with nocturnal values (0.75 (- 0.89-- 0.64) mL/min). After weight loss, normalization of this inverse rhythm was observed (day - 1.24 (- 1.44-1.05) mL/min and night - 0.98 (- 1.09-- 0.83) mL/min). A clear circadian rhythm in diuresis rate and in renal clearance of creatinine, solutes, sodium, and potassium was seen at all time points. Furthermore, we observed a significant increase in sodium clearance. Before weight loss, daytime sodium clearance was 0.72 mL/min (0.59-0.77) and nighttime clearance was 0.46 mL/min (0.41-0.51). After weight loss, daytime clearance increased to 0.99 mL/min (0.85-1.17) and nighttime clearance increased to 0.78 mL/min (0.64-0.93). Conclusion: In obese adolescents, lower diurnal free water clearance was observed compared with nocturnal values. Weight loss led to a normalization of this inverse rhythm, suggesting a recovery of the anti-diuretic hormone activity. Both before and after weight loss, clear circadian rhythm of diuresis rate and renal clearance of creatinine, solutes, sodium, and potassium was observed.What is Known:center dot Obesity-related alterations in circadian rhythm have been described for nocturnal blood pressure and for metabolic functions. We believe renal circadian rhythm is disrupted in obesity, though this has not been investigated yet.What is New:center dot In obese adolescents, an inverse circadian rhythm of free water clearance was observed, with higher nighttime free water clearance compared with daytime values. Weight loss led to a normalization of this inverse rhythm, suggesting a recovery of the anti-diuretic hormone activity.center dot Circadian rhythm in diuresis rate and in the renal clearance of creatinine, solutes, sodium, and potassium was preserved in obese adolescents and did not change after weight loss

Analysis of Saccharomyces cerevisiae Circadian Rhythms in Continuous Culture

The circadian rhythm is a roughly 24-hour cycle in the physiological processes of organisms. There have been many studies on the circadian rhythms in other model organisms, but not in Saccharomyces cerevisiae. To study the rhythm in S. cerevisiae, the levels of GAP dehydrogenase were observed. After the baseline levels were recorded, the conditions were changed to see if the circadian rhythm could be manipulated. The importance of identifying and studying the circadian oscillators in S. cerevisiae is to understand how the circadian rhythm is altered in differing conditions. The purpose of this experiment was to identify how changing the light and dark cycles affected the overall rhythms of S. cerevisiae

Circadian Rhythm in Yeast

Circadian rhythms are found in a variety of organisms and are involved in controlling activity of the organism. However, a circadian rhythm for yeast has not been discovered yet. The goal of this study is to find evidence for a circadian rhythm in yeast by looking for changes in GAPDH concentrations and peroxiredoxin levels. GAPDH and peroxiredoxin have been shown to be controlled by the circadian clock in many organisms. A continuous yeast culture is sampled every two hours over a period of about 104 hours. Each sample is processed and tested for the concentration of GAPDH using GAPDH reagent. Western blots will also be performed to determine peroxiredoxin levels

Ethnic differences and heritability of blood pressure circadian rhythm in African and European American youth and young adults

Background: The aim of this study was to investigate whether blood pressure (BP) circadian rhythm in African Americans differed from that in European Americans. We further examined the genetic and/or environmental sources of variances of the BP circadian rhythm parameters and the extent to which they depend on ethnicity or sex. Method: Quantification of BP circadian rhythm was obtained using Fourier transformation from the ambulatory BP monitoring data of 760 individuals (mean age, 17.2 +/- 3.3; 322 twin pairs and 116 singletons; 351 African Americans). Results: BP circadian rhythm showed a clear difference by ethnic group with African Americans having a lower amplitude (P = 1.5e-08), a lower percentage rhythm (P = 2.8e-11), a higher MESOR (P = 2.5e-05) and being more likely not to display circadian rhythm (P = 0.002) or not in phase (P = 0.003). Familial aggregation was identified for amplitude, percentage rhythm and acrophase with genetic factors and common environmental factors together accounting for 23 to 33% of the total variance of these BP circadian rhythm parameters. Unique environmental factors were the largest contributor explaining up to 67--77% of the total variance of these parameters. No sex or ethnicity difference in the variance components of BP circadian rhythm was observed. Conclusion: This study suggests that ethnic differences in BP circadian rhythm already exist in youth with African Americans having a dampened circadian rhythm and better BP circadian rhythm may be achieved by changes in environmental factors

Circadian rhythm and melatonin in liver carcinogenesis: updates on current findings

: Liver cancer, including hepatocellular carcinoma and cholangiocarcinoma, can be devastating if not treated early. The risk factors of liver cancer include alcoholic liver disease, non-alcoholic fatty liver disease, disruption of melatonin levels, and dysregulated circadian rhythm. The circadian rhythm is a 24-hour biological clock that regulates the physiological activities at both central and peripheral levels. Its molecular mechanism exists in every cell in mammals. Disruption of the circadian rhythm has found in liver cancers as an independent risk factor. This review summarized the most recent findings about the molecular mechanisms of circadian rhythm, the crosstalk between core clock genes and melatonin, as well as the role of circadian rhythm and melatonin played in chronic liver diseases and liver cancer. Finally, we discussed the potential clinical application of circadian rhythm and melatonin for the treatment of liver cancer and discussed future perspectives of how understanding the circadian rhythm in liver cancer progression could provide new clinical applications for liver cancer treatment and diagnosis

Effects of environmental enrichment on behavioral responses to novelty, learning, and memory, and the circadian rhythm in cortisol in growing pigs

Previously we showed that pigs reared in an enriched environment had higher baseline salivary cortisol concentrations during the light period than pigs reared under barren conditions. In the present experiment, it was investigated whether these higher baseline salivary cortisol concentrations were a real difference in cortisol concentration or merely represented a phase difference in circadian rhythm. The effects of different cortisol concentrations on the behavioral responses to novelty and learning and long-term memory in a maze test were also studied in enriched and barren housed pigs. At 9 weeks of age enriched and barren housed pigs did not differ in baseline salivary cortisol concentrations nor in circadian rhythm, but at 22 weeks of age barren housed pigs had a blunted circadian rhythm in salivary cortisol as compared to enriched housed pigs. The differences in baseline salivary cortisol concentrations between enriched- and barren-housed pigs are age-dependent, and become visible after 15 weeks of age. Enriched- and barren-housed piglets did not differ in time spent on exploration in the novel environment test. Barren-housed pigs had an impaired long-term memory in the maze test compared to enriched-housed pigs; however, no differences in learning abilities between enriched- and barren-housed pigs were found. Because blunted circadian cortisol rhythms are often recorded during states of chronic stress in pigs and rats or during depression in humans, it is suggested that the blunted circadian rhythm in cortisol in barren-housed pigs similarily may reflect decreased welfare.

Some Studies on Circadian Rhythm in the Culture of Omphalina Quelet sp. (Basidiomycota, Agaricales) A Mycobiont of an Unidentified Basidiolichen

This paper reports the discovery of circadian rhythm in Omphalina Quelet, in pure culture under laboratory conditions. The species was collected as a mycobiont from an unidentified basidiolichen

Circadian rhythm of hepatic cytosolic and nuclear estrogen receptors

The distribution of estrogen receptor between the cytosolic and nuclear compartments were evaluated in liver of male rats to determine whether a circadian rhythm exists. Cytosolic receptor reached a maximum level at 400 hours and a minimum at 2000 and 2400 hr. Nuclear receptor reached a maximum level at 800 hr and was lowest at 1600 and 2000 hr. Serum estradiol levels were also highest at 800 hr and lowest at 1600 hr. The variations in cytosolic and nuclear receptors are not reciprocal; in fact, the overall content of receptor in the liver is not constant and also displays a circadian rhythm. © 1986 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

Non-dipping nocturnal blood pressure and psychosis parameters in Parkinson disease

Conclusion: These results suggest that, among PD patients, a non-dipping circadian rhythm is associated with more severe symptoms of psychosis than is a dipping circadian rhythm. This association warrants further investigation