Effects of mental arithmetic stress on blood cell counts and the immune system

Evaluation of long-term dermal exposure to soil contaminated with spent engine oil in male Wistar rats: An experimental approach

Continuous occupational exposure to spent engine oil (SEO) poses physiological risks to humans, especially to automobile mechanics. This study investigated the physiological effects of SEO-contaminated soil in a male Wistar rat model. Animals were dermally exposed to soil contaminated with SEO for 120 consecutive days and compared with rats exposed to uncontaminated soil (negative control). Heavy metal (lead (Pb), nickel (Ni), zinc, and cadmium (Cd)) accumulations, hematology, biochemical (aspartate aminotransferase (AST), alanine aminotransferase, alkaline phosphatase (ALP), urea, and creatinine) parameters, sperm morphology, and histopathology (liver, kidney, lungs, brain, skin, and testis) were evaluated as end points. Results revealed that the heavy metals in SEO-contaminated soil are far greater than the World Health Organisation permissible limits, with significant (p < 0.05) increases of Pb and Ni present in the brain, and Pb and Cd in the serum compared with the uncontaminated soil for the negative control. Only significant (p < 0.05) values were observed in the lymphocytes, activities of AST and ALP, and sperm abnormalities of the exposed rats compared with those used for the negative control. Histopathological changes were not evident in the brain but lesions were observed in the liver, kidney, lungs, skin, and testis of the exposed rats. Results herein suggest that the constituents of SEO may elicit harmful physiological changes to humans who are directly exposed to them.

Factors associated with primary transmission of multidrug-resistant tuberculosis compared with healthy controls in Henan Province, China

Background

It is estimated that there are about 74,000 primary multidrug-resistant tuberculosis (MDR-TB) patients per year according to the prevalence of MDR-TB of 5.7% among new TB patients in China. Thus, the risks of primary transmission of MDR-TB require further attention. This study aimed to identify the factors associated with primary transmission of MDR-TB in Henan province, where the number of new TB patients is ranked second highest in China.

Methods

A 1:1 matched case–control study was conducted in Henan, China. Cases were primary MDR-TB patients who were individually matched with a healthy control without TB from the same neighborhood. The study was conducted from July 2013 to June 2014. Both case and control were matched by age (±5 years) and sex. Conditional logistic regression was used to compute adjusted odds ratios (AORs) with corresponding 95% confidence intervals (CIs) for risk factors associated with primary MDR-TB.

Results

For the study, 146 pairs of participants were recruited. The final multivariable logistic regression model disclosed that after adjusting for age and sex, primary MDR-TB cases were more likely to be single (AOR, 5.4; 95% CI, 1.4–20.7), earn an annual income of ≤ 12,000 yuan (RMB) (AOR, 9.9; 95% CI, 2.0–48.1), experience more life pressure/stress (AOR, 10.8; 95% CI, 2.8–41.5), not be medically insured (AOR, 50.1; 95% CI, 8.2–306.8), and suffer from diabetes, cardiovascular disease or other respiratory diseases, or cancer (AOR, 57.1; 95% CI, 8.6–424.2).

Conclusions

In order to control primary transmission of MDR-TB in China, we recommend that improving the social support, living standards and medical security of the lower social class become a priority.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-015-0045-1) contains supplementary material, which is available to authorized users.

Changes of immunoregulatory cells associated with psychological stress and humor

For 8 medical students influences of psychological stress or humor on T-cell subset percentages and natural killer cell activity were investigated by measuring these parameters before and after an examination and before and after watching a comedy video. Although T-cell subsets were not significantly affected by either stimulus and natural killer cell activity was not affected by the examination, the latter was significantly decreased after watching the comedy video.