Chronic oxidative-stress, chronic inflammation, and persistent aberrant DNA-methylation occurred in the liver of (48)Ti-exposed mice. Hence, exposure to (48)Ti ions in space may pose health risks.

IntroductionThere have been few studies which have compared the quality of life between medical students and adult health care workers.Aims(1) To compare health related quality of life (HRQoL) between medical students and adult health care workers and (2) to identify factors associated with quality of life of medical students.MethodsA cross sectional survey of medical students at Chiang Mai University and health care workers at Chiang Mai University Hospital in 2013.ResultsCompared with the population of adult health care workers, medical students had a higher physical HRQoL but similar mental HRQoL. This is potentially mediated by the presence of depression, as the prevalence of depressive symptoms was similar in both groups. Higher academic achievement and absence of underlying biomedical conditions were associated with higher HRQoL in medical students.ConclusionThe psychological burden for medical students in Thailand could be at similar levels to that of their adult health care counterparts.

Burkholderia pseudomallei, the causative agent of the potentially fatal tropical disease melioidosis, is known to be highly resistant to oxidative stress although the mechanism of this resistance remains to be fully elucidated. Previous studies have shown that an OxyR is involved in the regulation of oxidative stress via the katG and dpsA genes encoding KatG and DpsA and that the alternative sigma factor, RpoS, plays a critical role in resistance to oxidative stress by regulating katG and katE genes. Here it is shown that RpoS is essential for expression of the oxidative stress regulator OxyR, since a mutant strain lacking RpoS failed to induce oxyR expression both during normal growth and under conditions of oxidative stress. It is further demonstrated that the RpoS acts as a positive transcriptional regulator of oxyR and dpsA expression, while OxyR acts as a negative transcriptional regulator of the katG-dpsA operon via OxyR repressor under normal growth conditions, and as a positive transcriptional regulator via OxyR under conditions of oxidative stress. Therefore both RpoS and OxyR are required to promote expression of both the katG-dpsA operon and dpsA gene.

Although the lung is one of the target organs at risk for cancer induction from exposure to heavy ions found in space, information is insufficient on cellular/molecular responses linked to increased cancer risk. Knowledge of such events may aid in the development of new preventive measures. Furthermore, although it is known that germinal cells are sensitive to X- or γ-rays, there is little information on the effects of heavy ions on germinal cells. Our goal was to investigate in vivo effects of 1 GeV/n 48Ti ions (one of the important heavy ions found in the space environment) on somatic (lung) and germinal (testis) tissues collected at various times after a whole body irradiation of CBA/CaJ mice (0, 0.1, 0.25, or 0.5 Gy, delivered at 1 cGy/min). We hypothesized that 48Ti-ion-exposure induced damage in both tissues. Lung tissue was collected from each mouse from each treatment group at 1 week, 1 month, and 6 months postirradiation. For the testis, we collected samples at 6 months postirradiation. Hence, only late-occurring effects of 48Ti ions in the testis were studied. There were five mice per treatment group at each harvest time. We investigated inflammatory responses after exposure to 48Ti ions by measuring the levels of activated nuclear factor kappa B and selected pro-inflammatory cytokines in both tissues of the same mouse. These measurements were coupled with the quantitation of the levels of global 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Our data clearly showed the induction of chronic inflammation in both tissues of exposed mice. A dose-dependent reduction in global 5hmC was found in the lung at all time-points and in testes collected at 6 months postirradiation. In contrast, significant increases in global 5mC were found only in lung and testes collected at 6 months postirradiation from mice exposed to 0.5 Gy of 1 GeV/n 48Ti ions. Overall, our data showed that 48Ti ions may create health risks in both lung and testicular tissues.