Biomedical and environmental sciences : BES最新文献

Female Sprague-Dawley rats weighing 60-80 g were given different dosages of soy isoflavones and/or lindane for four weeks. Soy isoflavones was added in feed and lindane was given by oral gavage. We found that soy isoflavones could reduce the level of lindane in rat's serum and brain, but might cause the uterus hyperplasia. Lindane could inhibit the effect of soy isoflavones on uterus and significantly decrease the level of estradiol and testosterone in serum. This study indicated that soy isoflavones could reduce the level of lindane in rat's body. Lindane could reduce the level of hormones and decreased the effect of soy isoflavones on rat's uterus.

Objective: To assess the prevalence of malnutrition among children and adolescents in Xizang (Tibet).

Methods: We analyzed data from the Chinese National Survey on Students' Constitution and Health for the years 1995, 2000, 2005, and 2010 pertaining to Tibetan children and adolescents in lase (Lhasa), aged 7-18 years old. Numbers of survey subjects for these years were: 2393, 2754, 2397, and 2643, respectively.

Results: Our results indicated that the rate of occurrence of stunting in Tibet has evidenced a gradual decline: for boys, from 26.8% in 2000 to 9.3% in 2010; and for girls, from 25.8% in 2000 to 10.8% in 2010. In general, the wasting rate for both boys and girls in Tibet has gradually decreased over time: for boys, from 17.7% in 1995 to 4.6% in 2005; and for girls from 12.5% in 1995 to 2.3% in 2005. The stunting rates of boys aged 7-13 years old and of girls aged 7-11 years old were 67.5% and 53.1%, respectively, while these rates for boys aged 14-18 years old and girls aged 12-18 years old were 32.5% and 46.9%, respectively.

Conclusion: Stunting and wasting rates of Tibetan children and adolescents indicate a gradual declining trend over time. The stunting rates of both boys and girls during early puberty were significantly higher than those during late puberty.

Objective: The goal of this study was to analyze protein requirements in healthy adults through a meta-analysis of nitrogen balance studies.

Methods: A comprehensive search for nitrogen balance studies of healthy adults published up to October 2012 was performed, each study were reviewed, and data were abstracted. The studies were first evaluated for heterogeneity. The average protein requirements were analyzed by using the individual data of each included studies. Study site climate, age, sex, and dietary protein source were compared.

Results: Data for 348 subjects were gathered from 28 nitrogen balance studies. The natural logarithm of requirement for 348 individuals had a normal distribution with a mean of 4.66. The estimated average requirement was the exponentiation of the mean of the log requirement, 105.64 mg N/kg•d. No significant differences between adult age, source of dietary protein were observed. But there was significant difference between sex and the climate of the study site (P<0.05).

Conclusion: The estimated average requirement and recommended nutrient intake of the healthy adult population was 105.64 mg N/kg•d (0.66 g high quality protein/kg•d) and 132.05 mg N/kg•d (0.83 g high quality protein/kg•d), respectively.

Melamine in combination with cyanuric acid has been considered to be more toxic than either melamine or cyanuric acid alone. The objective of this study was designed to evaluate the combined genotoxicity and cytotoxicity of melamine (M) and cyanuric acid (C) at three mass ratios (1:1, 1:2, 2:1). MC (1:1), MC (1:2), and MC (2:1) were evaluated for their potential genotoxic risk, at gene level by Ames test, and at chromosomal level by micronucleus test. In order to evaluate cytotoxicity in HEK-293 cells, the MTT assay was included. Western blot was also employed to investigate the renal injury molecule-1 (Kim-1) expression in HEK-293 cells exposed to MC. Neither genotoxicity at gene level nor at chromosomal level was observed for MC (1:1), MC (1:2), and MC (2:1). Based on MTT assay, three ratios of MC at 82.5 and 165 µg/mL slightly inhibited viability of HEK-293 cells (P<0.05). MC (1:1) at 41.25 and 82.50 µg/mL could elevate the Kim-1 expression in HEK-293 cells.

This study aimed to investigate bacterial community in an urban drinking water distribution system (DWDS) during an occurrence of colored water. Variation in the bacterial community diversity and structure was observed among the different waters, with the predominance of Proteobacteria. While Verrucomicrobia was also a major phylum group in colored water. Limnobacter was the major genus group in colored water, but Undibacterium predominated in normal tap water. The coexistence of Limnobacter as well as Sediminibacterium and Aquabacterium might contribute to the formation of colored water.

Objective: To study the relationship between resting heart rate and blood lipid level.

Methods: A total of 9 415 subjects aged ⋝ 40 years were included in the present study. Their resting heart rate was monitored and their serum levels of triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) were measured to define dyslipidemia according to the 2007 Chinese Guidelines on Prevention and Treatment of Dyslipidemia in Adults.

Results: The subjects were divided into group A with their resting heart rate <70 beats/min, group B with their resting heart rate =70-79 beats/min, group C with their resting heart rate =80-89 beats/min, and group D with their resting heart rate ⋝ 90 beats/min. High TG, TC, and LDL-C were presented across the resting heart rate (Ptrend <0.01). Multiple logistic regression analysis revealed that the risk of high TG and TC was higher in subjects with their resting heart rate ⋝ 90 beats/min than in those with their resting heart rate <70 beats/min (OR=1.42; 95% CI: 1.16-1.74 and OR=1.33; 95% CI: 1.09-1.64, respectively).

Conclusion: Elevated resting heart rate is associated with high TG and TC in middle-aged and elderly Chinese subjects.

A total of 1116 middle-aged and elderly men and 1442 postmenopausal women were recruited in this study. Whether bisphenol A exposure was associated with circulating sex hormone concentrations was studied. Univariate analysis revealed that the urinary bisphenol A concentration was negatively correlated with the serum levels of luteinizing hormone (β=-0.061, P<0.0001) and follicle-stimulating hormone (β=-0.086, P<0.0001) in men, and with the serum levels of follicle-stimulating hormone (β=-0.037, P=0.018) and sex hormone-binding globulin (β=-0.043, P=0.006) in women. However, no significant association was observed between the serum levels of urinary bisphenol A and circulating sex hormone after adjustment for the potential confounders.

Objective: To study the relation between serum calcium level and elevated BaPWV in Chinese subjects.

Methods: The relation between serum calcium level and elevated BaPWV was studied in 9 615 subjects. The mean value of left and right BaPWV was analyzed. BaPWV was defined as high when it was ⋝1752.5 cm/s (the upper quartile) either side.

Results: The BaPWV and its elevated percentage progressively increased across the quartiles of the serum calcium level (P<0.05). The prevalence of elevated BaPWV was significantly higher in subjects of the second, third and highest quartiles than in those of the lowest quartile (26.9%, 28.4%, and 33.2% vs 23.7%, P=0.0116, P=0.0004, and P<0.0001). Logistic regression analysis revealed that the risk of elevated BaPWV was 1.32- fold higher in subjects of the highest quartile than in those of the lowest quartile (OR=1.32, 95% CI: 1.08-1.60).

Conclusion: The elevated serum calcium level is related to an elevated BaPWV and a higher risk of arterial stiffness, independent of conventional risk factors, in middle-aged and elderly Chinese subjects.