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Comparison of Urine Toxic Metals Concentrations between Athletes and Sedentary Subjects
Medicine & Science in Sports & Exercise: May 2011 - Volume 43 - Issue 5 - p 706

Muñoz, Diego1; Llerena, Francisco2; Barrientos, Gema1; Palomo, Rosario3; Pinilla, Eduardo3; Olcina, Guillermo1; Maynar, Marcos1; Caballero, Maria Jesús2

Information about levels of many trace elements in biological tissues is scarce. Toxic trace elements are pervasive in the human environment and are known to accumulate in the human body over lifetime. Studies in athletes during training periods compared to non-training control subjects, indicate increased loses of minerals by sweat and urine.
PURPOSE: The aim of this study was to compare the level of toxic trace elements: lead (Pb), cadmium (Cd), beryllium (Be), tellurium (Te) and tungsten (W) in urine samples between athletes and age-matched sedentary subjects living in the same geographical area.
METHODS: twenty-one middle-distance runners (age 21.6 ± 4.3 years; Body Mass Index (BMI): 18.25 ± 1.73) and twenty-six sedentary men (age 22.65 ± 3.6 years; BMI 21.81±3.14) participated in this study. Morning midstream urine samples were collected in 30 ml polyethylene containers cleaned with 5% (v/v) HNO3 and were transported to the laboratory. The samples were acidified with 1% (v/v) HNO3 and then were vigorously shaken for 1 min prior to their storage at -20ºC. Be, Cd, Pb, Re, Te, and W were determined in urine samples using a Perkin-Elmer Elan 9000 inductively coupled plasma mass spectrometry (ICP-MS) with a quadrupole based collision/reaction cell. Creatinine concentrations were measured in all urine samples to take into account the different degree of dilution. The Mann-Whitney test was performed for statistical analysis. A p value of <0.05 was used to determine statistical significance.
RESULTS: Concentrations, expressed in µg/mg creatinine, of 5 toxic elements in urine from athletes versus sedentary subjects were as follows: Pb (0.938 ± 0.664 vs. 2.162 ± 1.444 p<0.001); Cd (0.123 ± 0.075 vs. 0.069 ± 0.041, p<0.05); Be (0.536 ± 0.244 vs. 0.066 ± 0.035, p<0.001); Te (0.244 ± 0.193 vs. 0.066 ± 0.045, p<0.001); W (0.082 ± 0.053 vs. 0.022 ± 0.006, p<0.001).
CONCLUSION: With the exception of Pb, urine toxic metal concentrations from athletes were higher than from sedentary subjects. This fact suggests that physical activity counteracts, at least in part, the cumulative effect of toxic environment by increasing the urine excretion of toxic metals in trained people.

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1,25(OH)2Vitamin D3 Stimulates Myogenic Differentiation by Inhibiting Cell Proliferation and Modulating the Expression of Promyogenic Growth Factors and Myostatin in C2C12 Skeletal Muscle Cells
Leah A. Garcia, Keisha K. King, Monica G. Ferrini, Keith C. Norris and Jorge N. Artaza     Endocrinology August 1, 2011 vol. 152 no. 8 2976-2986

Skeletal muscle wasting is an important public health problem associated with aging, chronic disease, cancer, kidney dialysis, and HIV/AIDS. 1,25-Dihydroxyvitamin D (1,25-D3), the active form of vitamin D, is widely recognized for its regulation of calcium and phosphate homeostasis in relation to bone development and maintenance and for its calcemic effects on target organs, such as intestine, kidney, and parathyroid glands. Emerging evidence has shown that vitamin D administration improves muscle performance and reduces falls in vitamin D-deficient older adults. However, little is known of the underlying mechanism or the role 1,25-D3 plays in promoting myogenic differentiation at the cellular and/or molecular level. In this study, we examined the effect of 1,25-D3 on myoblast cell proliferation, progression, and differentiation into myotubes. C2C12 myoblasts were treated with 1,25-D3 or placebo for 1, 3, 4, 7, and 10 d. Vitamin D receptor expression was analyzed by quantitative RT-PCR, Western blottings and immunofluorescence. Expression of muscle lineage, pro- and antimyogenic, and proliferation markers was assessed by immunocytochemistry, PCR arrays, quantitative RT-PCR, and Western blottings. Addition of 1,25-D3 to C2C12 myoblasts 1) increased expression and nuclear translocation of the vitamin D receptor, 2) decreased cell proliferation, 3) decreased IGF-I expression, and 4) promoted myogenic differentiation by increasing IGF-II and follistatin expression and decreasing the expression of myostatin, the only known negative regulator of muscle mass, without changing growth differentiation factor 11 expression. This study identifies key vitamin D-related molecular pathways for muscle regulation and supports the rationale for vitamin D intervention studies in select muscle disorder conditions.

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Sodium and Potassium Intake and Mortality Among US Adults
Prospective Data From the Third National Health and Nutrition Examination Survey

Quanhe Yang         Arch Intern Med. 2011;171(13):1183-1191.

Background Several epidemiologic studies suggested that higher sodium and lower potassium intakes were associated with increased risk of cardiovascular diseases (CVD). Few studies have examined joint effects of dietary sodium and potassium intake on risk of mortality.

Methods To investigate estimated usual intakes of sodium and potassium as well as their ratio in relation to risk of all-cause and CVD mortality, the Third National Health and Nutrition Examination Survey Linked Mortality File (1988-2006), a prospective cohort study of a nationally representative sample of 12 267 US adults, studied all-cause, cardiovascular, and ischemic heart (IHD) diseases mortality.

Results During a mean follow-up period of 14.8 years, we documented a total of 2270 deaths, including 825 CVD deaths and 443 IHD deaths. After multivariable adjustment, higher sodium intake was associated with increased all-cause mortality (hazard ratio [HR], 1.20; 95% confidence interval [CI], 1.03-1.41 per 1000 mg/d), whereas higher potassium intake was associated with lower mortality risk (HR, 0.80; 95% CI, 0.67-0.94 per 1000 mg/d). For sodium-potassium ratio, the adjusted HRs comparing the highest quartile with the lowest quartile were HR, 1.46 (95% CI, 1.27-1.67) for all-cause mortality; HR, 1.46 (95% CI, 1.11-1.92) for CVD mortality; and HR, 2.15 (95% CI, 1.48-3.12) for IHD mortality. These findings did not differ significantly by sex, race/ethnicity, body mass index, hypertension status, education levels, or physical activity.

Conclusion Our findings suggest that a higher sodium-potassium ratio is associated with significantly increased risk of CVD and all-cause mortality, and higher sodium intake is associated with increased total mortality in the general US population.

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Adipocytes as a new source of catecholamine production
FEBS Lett Volume 585, Issue 14, 21 July 2011, Pages 2279-2284   Peter Vargovic

Catecholamines are an important regulator of lipolysis in adipose tissue. Here we show that rat adipocytes, isolated from mesenteric adipose tissue, express genes of catecholamine biosynthetic enzymes and produce catecholamines de novo. Administration of tyrosine hydroxylase inhibitor, alpha-methyl-p-tyrosine, in vitro significantly reduced concentration of catecholamines in isolated adipocytes. We hypothesize that the sympathetic innervation of adipose tissues is not the only source of catecholamines, since adipocytes also have the capacity to produce both norepinephrine and epinephrine.

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The effects of catechin rich teas and caffeine on energy expenditure and fat oxidation: a meta-analysis
R. Hursel             Obesity Reviews       Volume 12, Issue 7, pages e573–e581, July 2011

Different outcomes of the effect of catechin-caffeine mixtures and caffeine-only supplementation on energy expenditure and fat oxidation have been reported in short-term studies. Therefore, a meta-analysis was conducted to elucidate whether catechin-caffeine mixtures and caffeine-only supplementation indeed increase thermogenesis and fat oxidation. First, English-language studies measuring daily energy expenditure and fat oxidation by means of respiration chambers after catechin-caffeine mixtures and caffeine-only supplementation were identified through PubMed. Six articles encompassing a total of 18 different conditions fitted the inclusion criteria. Second, results were aggregated using random/mixed-effects models and expressed in terms of the mean difference in 24 h energy expenditure and fat oxidation between the treatment and placebo conditions. Finally, the influence of moderators such as BMI and dosage on the results was examined as well. The catechin-caffeine mixtures and caffeine-only supplementation increased energy expenditure significantly over 24 h (428.0 kJ (4.7%); P < 0.001 and 429.1 kJ (4.8%); P < 0.001, respectively). However, 24 h fat oxidation was only increased by catechin-caffeine mixtures (12.2 g (16.0%); P < 0.02 and 9.5 g (12.4%); P = 0.11, respectively). A dose-response effect on 24 h energy expenditure and fat oxidation occurred with a mean increase of 0.53 kJ mg−1 (P < 0.01) and 0.02 g mg−1 (P < 0.05) for catechin-caffeine mixtures and 0.44 kJ mg−1 (P < 0.001) and 0.01 g mg−1 (P < 0.05) for caffeine-only. In conclusion, catechin-caffeine mixtures or a caffeine-only supplementation stimulates daily energy expenditure dose-dependently by 0.4–0.5 kJ mg−1 administered. Compared with placebo, daily fat-oxidation was only significantly increased after catechin-caffeine mixtures ingestion.

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Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss?
K. A. Varady         Obesity Reviews Volume 12, Issue 7, pages e593–e601, July 2011

Dietary restriction is an effective strategy for weight loss in obese individuals. The most common form of dietary restriction implemented is daily calorie restriction (CR), which involves reducing energy by 15–60% of usual caloric intake every day. Another form of dietary restriction employed is intermittent CR, which involves 24 h of ad libitum food consumption alternated with 24 h of complete or partial food restriction. Although both diets are effective for weight loss, it remains unknown whether one of these interventions produces superior changes in body weight and body composition when compared to the other. Accordingly, this review examines the effects of daily CR versus intermittent CR on weight loss, fat mass loss and lean mass retention in overweight and obese adults.

Results reveal similar weight loss and fat mass loss with 3 to 12 weeks’ intermittent CR (4–8%, 11–16%, respectively) and daily CR (5–8%, 10–20%, respectively).

In contrast, less fat free mass was lost in response to intermittent CR versus daily CR. These findings suggest that these diets are equally as effective in decreasing body weight and fat mass, although intermittent CR may be more effective for the retention of lean mass.

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