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We examined the association between salivary mitochondrial DNA (mtDNA) copy number and chronic fatigue combined with depression and insomnia.
This cross-sectional study included 58 healthy adults with moderate to severe fatigue (Brief Fatigue Inventory [BFI] ≥4) for longer than 6 months. Subjects were classified as those without combined symptoms, with either depression (Beck Depression Inventory [BDI] ≥13) or insomnia (Pittsburgh Sleep Quality Index [PSQI] ≥5), or with both depression and insomnia. Salivary mtDNA copy number was measured by real-time quantitative polymerase chain reaction. The association was evaluated using a general linear model.
About 76% of participants had either depression or insomnia as additional symptoms. These subjects were predominately female, drank more alcohol, and exercised less than those without combined symptoms (P<0.05). The group with both depression and insomnia exhibited significantly higher BFI and lower mtDNA copy number than those without combined symptoms (P<0.05). After adjusting for confounding factors, significant negative associations between mtDNA copy number and usual fatigue were found in the group without combined symptoms, whereas the negative associations in the group with combined symptoms were attenuated. BDI and PSQI were not associated with mtDNA copy number.
Chronic fatigue is negatively associated with salivary mtDNA copy number. Salivary mtDNA copy number may be a biological marker of fatigue with or without combined symptoms, indicating that a separate approach is necessary.
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The results of previous studies on the association between blood mercury (Hg) and bone mineral density (BMD) are inconsistent. We therefore used a large-scale nationwide representative sample of Korean men to investigate the relationship between these two parameters.
A nationwide cross-sectional study was conducted using data from the 2008 to 2010 Korean National Health and Nutrition Examination Survey to evaluate the relationship between blood Hg and BMD and the prevalence of osteopenia or osteoporosis in 1,190 men over 50 years of age. BMD was measured by dual-energy X-ray absorptiometry. Osteopenia and osteoporosis were diagnosed for each body site according to World Health Organization T-score criteria.
After adjusting for age, body mass index, caloric energy and calcium intake, vitamin D levels, fish consumption, alcohol consumption, smoking, and exercise, quartiles of blood Hg were positively associated with femur neck T-scores in multiple linear regression analysis (β=0.06, P-value=0.03). Compared with the lowest blood Hg quartile, the odds ratios and 95% confidence intervals for diagnosis of osteopenia or osteoporosis in the second and fourth quartiles were 0.63 (0.41–0.99) and 0.57 (0.36–0.91), respectively, in the femur neck after adjusting for the same co-variables.
High blood Hg levels were associated with reduced odds of decreased femur neck BMD in Korean men. However, subgroup analysis did not show a significant protective effect of blood Hg on osteoporotic fractures. Further research is necessary to clarify the association between blood Hg and BMD.
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Testosterone levels are decreased in diabetic patients and recent studies have suggested that high-normal fasting glucose is a risk factor for cardiovascular disease. To further elucidate the relationship between plasma glucose and testosterone, we investigated the association between fasting plasma glucose (FPG) and endogenous sex hormones (serum total testosterone, sex hormone binding globulin, estradiol, and the ratio of testosterone to estradiol) in non-diabetic and pre-diabetic men.
This study included 388 men (age ≥ 40 years) who visited the health promotion center of a university hospital from May 2007 to August 2008. The subjects were divided into quartiles based on their FPG levels and correlation and multiple linear regression analyses were performed. Q1 (65 mg/dL ≤ FPG < 88 mg/dL), Q2 (88 mg/dL ≤ FPG < 94 mg/dL), Q3 (94 mg/dL ≤ FPG < 100 mg/dL) and Q4 (100 mg/dL ≤ FPG < 126 mg/dL).
FPG was independently, inversely associated with total testosterone in the non-diabetic population after adjusting for age, body mass index, smoking, and alcohol consumption (β = -0.082, P < 0.01). Among the quartiles, subjects in the high-normal FPG groups (Q2, Q3, and Q4 with FPG ≥ 88 mg/dL) had significantly decreased testosterone levels when compared with subjects in the normal FPG group (Q1 with FPG < 88 mg/dL, P < 0.005). Sex hormone binding globulin, estradiol and the ratio of testosterone to estradiol were not correlated with FPG.
Our study indicates that high-normal fasting glucose levels are associated with decreased testosterone levels in non-diabetic and pre-diabetic men.
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