Comprehensive study of health effects of plasma technology occupational environment: Exposure to high frequency and intensity noise and toxic gases

OBJECTIVES

To evaluate on animal models the health effects of the combined or separate exposure to main chemical and physical hazards of plasma-based material processing technology environment.

MATERIALS AND METHODS

Male Wistar rats were exposed to actual levels of hazardous factors in plasma technology occupational environment: i.e., ozone and nitrogen oxides (O₃ and NO_x) in respective concentrations of 0.5 mg/m³ and 1.0 mg/m³ and high-frequency (1000-1600 Hz) of 112 dB intensity noise for 3 h/day, 5 days/week for 12 weeks, with a recovery period of 1 month.

RESULTS

Exposure to noise or its combination with chemical factors (ozone, nitrogen oxides) causes non-specific CNS changes testifying for significant excitation dominance, especially in the case of joint exposure. Histological examination of rats' brain in experimental revealed a pronounced increase in blood filling of small vessels on the tenth day of the experiment, with subsequent intensification of vascular alterations and eventually to cerebral edema. The exposure to noise significantly reduced total thymus, bone marrow and spleen cell numbers and these was also more pronounced under the joint impact of noise and toxic gases. Thymus, but not bone marrow or spleen, mitotic activity was as well reduced under the same modes of exposure. Cytological investigation of film preparations of subcutaneous connective tissue revealed that joint exposure led to microcirculatory disorders, increased number of dark mast cells and reduced degranulation processes indicative of increased autoregulatory processes effective at microvasculature level.

CONCLUSIONS

High-frequency and intensity noise is main stressor factor that has negative impact on CNS and immune system, morphology and functioning of hematopoietic organs (spleen, bone marrow, thymus) and connective tissue. Its negative impact is significantly potentiated by concurrent exposure to ozone and nitrogen oxide, while exposure only to these toxic gases has no significant effect on the above targets.

Progress toward measles elimination in the Russian Federation, 2003-2009

Successful implementation of the Russian Federation's national measles elimination program has been ensured by high vaccine coverage (>95%) of the target population (with 2 doses of measles-containing vaccine), case-based laboratory investigation of measles, and active surveillance of measles cases among patients with rashes and/or fever. As a result, the incidence of measles has decreased to <1 case per 1,000,000 population (2007-2009); no circulation of D6 genotype, which was endemic in the Russian Federation, has been observed since the second half of 2007; and the proportion of imported measles cases of different genotypes increased to 19.8% in 2007 from 1% in 2003. To confirm successful elimination of indigenous measles, a documentation system was initiated in the Russian Federation.

[Reorganization of elements of the cytoskeletal and vacuolar systems in tumor cells in the early stage of developing multiple drug resistance]

The multidrug resistance (MDR) is one of the main reasons for chemotherapeutic failures in cancer patients. The overexpression of MDR gene product (Pgp) leads to the appearance of resistant tumor cells. We investigated alterations of cell structures in cells with a low level MDR and Pgp expression. The Syrian hamster embryo fibroblasts transformed by the Raus sarcoma virus were used in our experiments. Resistant sublines were isolated by propagation of the cells in colchicine supplemented medium. We have found that the first steps of MDR are accompanied by significant alterations of cytoskeleton elements and vacuolar system, e.g. changes in actin stress-fibres organization, microtubule distribution, the Golgi complex structure, vesicular transport. We suppose that the above cell structural alterations are not accidental. Perhaps, they are also essential for evolution of multidrug resistant mechanisms.