Background/Objectives: To determine effects of gender, age, diet, and smoking status on circadian rhythm characteristics of ascorbic acid (vitamin C). Subjects/Methods: Ascorbic acid was measured spectrophotometrically in serum collected from 162 healthy volunteers (103 males and 59 females; 7-75 years) every 6 h for 24 h (4 samples). Data were analyzed by single and population mean cosinor. Effects of gender, age, diet (vegetarian vs. omnivore), and smoking status on the rhythm-adjusted mean (MESOR) and circadian amplitude were examined by multiple analysis of variance. Results: A circadian rhythm is documented with statistical significance by population mean cosinor. In addition to effects of gender and age, the MESOR is affected by diet and smoking status. The circadian amplitude changes nonlinearly as a function of age. The circadian acrophase advances with increasing age.
Conclusion:The present observations confirm a definite circadian rhythm in ascorbic acid concentrations with significant effects of age, diet and smoking status in clinical health. Mapping the circadian rhythm of serum ascorbic acid in health can help explore its role in different pathophysiological conditions as predisease conditions may be characterized by alterations in the circadian amplitude and/or phase before there is a change in mean value.
The circadian rhythm of uric acid concentration was studied under near-normal tropical conditions in 162 healthy volunteers (103 males and 59 females; 7 to 75 year). They were mostly medical students, staff members and members of their families. They were classified into 4 age groups: A (7-20 y; N = 42), B (21-40 y; N = 60), C (41-60 y; N = 35) and D (61-75 y; N = 25). They followed a diurnal activity from about 06:00 to about 22:00 and nocturnal rest. Blood samples were collected from each subject every 6 for 24 h (4 samples). Serum uric acid was measured spectrophotometrically. Data from each subject were analyzed by cosinor rhythmometry. Effects of gender, age, diet (vegetarian vs. omnivore), and smoking status on the rhythm-adjusted mean (MESOR) and circadian amplitude were examined by multiple-analysis of variance. A marked circadian variation was found in uric acid concentration in healthy Indians of all age groups. Furthermore, both the MESOR and circadian amplitude underwent changes with advancing age. In addition to effects of gender and age, diet and smoking were also found to affect the MESOR of circulating uric acid concentration in healthy Indians residing in northern India. The present observations confirmed a definite rhythm in uric acid concentrations with significant effect of gender, age, diet, and smoking status on uric acid concentration in clinical health. Mapping the circadian rhythm of serum uric acid is needed to explore their role in different pathophysiological conditions.
The chronome of lipid peroxidation and antioxidant defense mechanisms may relate to the efficacy and management of time qualified preventive therapeutic and dietary interventions. One hundred renal stone patients, 20-60 years of age, and 50 clinically healthy volunteers, 21-45 years, were synchronized for 1 week with diurnal activity from 06:00 to 22:00 and nocturnal rest. All subjects took their usual meals three times daily (breakfast around 08:30, lunch around 13:00, and dinner around 20:30) with usual fluid intake. Drugs known to affect free radical system were not taken. Blood samples were collected at 6-h intervals for 24-h under standardized, presumably 24-h synchronized conditions. Determinations included plasma lipid peroxides, in terms of malondialdehyde (MDA) and blood superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CAT) activities. A marked circadian variation was demonstrated for each studied variable by populationmean cosinor in renal stone patients and healthy participants (p \ 0.001). By comparison to healthy subjects, parameter tests indicate that the stone formers had a higher MESOR of MDA, but a lower MESOR of SOD, GPx, GR and CAT. Furthermore, the patients also differed from the healthy controls in terms of their circadian amplitude and acrophase (tested jointly) of all variables (p \ 0.001). Mapping the broader time structure with multifrequency circadian characteristics of oxidants and anti-oxidants is needed for exploring their role as marker in the treatment and management of urolithiasis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.