Tehran University Medical Journal

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Background: Fumes generated during electric welding are one of air pollutants of working place in industrial companies, which can cause some clinical signs and diseases in worker, including mucosal irritation, changing of semen quality and cancer. Chronic exposure of workers with these fumes can cause reduce sperm motility and forward penetration and decrease in normal sperm count. Although a lot of researches were done in this field up to now, there is little information about histopathological effects of these fumes on germinal epithelium. The aim of this study was to identify structural changes of germinal epithelium in Rat as an experimental model after exposure to fumes of electric welding in exposure chamber.
Material and Methods: A total number of 60 Sprague Dawley Rats were chosen and divided into experimental (40) and control (20) groups. Each of groups was subdivided into 2, 4, 6 and 8-week subgroups. The number of Rat in each subgroup of experimental and control group was 10 and 5 respectively. Animals were housed in standard situation. After adaptation experimental group were exposed to fumes of electric welding (AMA 2000 electrode, 100 Ampere, 0.1 cm/s speed of electrode welding) for 2 hour/day and 5 day/week. The rate of air turn over in exposure chamber was fixed to 12-15/hour. The amount of O3, CO, CO2, NO + NO2 and particulate matter were measured by Galtec detectors and Cellulose acetate filter respectively. According to time table animals were killed and specimens from testis were taken and fixed in formaline buffer solution and processed routinely. Sections with 5-7 micrometer in thickness were stained by H-E, PAS, PNA and Alcian blue pH=2.5. The thickness of germinal epithelium was measured and data were analyzed by Kruskall Wallis test.
Results: The results of this study showed a few quantitative and qualitative changes in germinal epithelium. Vasodilatation of vessels in tunica albuginea and interstitial tissue, decreasing of eosinophilia in myoid cells, increase in size of spermatogonia especially dark type, disorganization of association between sertoli and spermatogenic cell lineage and spermatogenic arrests in spermatocyte I period. There were significant difference between experimental and control group for thickness of germinal epithelium (p<0.001).
Conclusion: It seems that although some adaptation response was appeared in experimental group, a lot of structural changes also appeared in germinal epithelium. The amount and severity of these changes were dependent to 3 factors include the amount of fumes, the variety of it and the duration of exposure.

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Background: Some pregnant women are exposed to occupational noise, a risk factor for the development of the auditory system. The auditory system is one of the areas in embryonic development in which noise might induce aberrant development. Noise can change the gene expression pattern of an embryo and thereby modify the physiology of the auditory system. Therefore, noise can change the molecular structure of the developing ear. One of the critical molecules involved in development of auditory system is glycoconjugate. The aim of this study was to investigate the molecular changes of the developing spiral ganglion after exposure to industrial levels of noise.

Methods: A total of 42 pregnant mice were divided into control and experimental groups. Each group was further divided into three subgroups. The three experimental subgroups were exposed to daily noise with an intensity of 100 db for 2.5 hours until sacrifice (for the first group to be sacrificed) or day seven of postnatal life (for the other two groups). The mice offspring were sacrificed at the first, seventh and 14^th days of postnatal life. The inner ears were prepared histologically. The specimens were stained with the lectins wheat germ antigen (WGA), peanut agglutinin (PNA), Dolichos biflorus agglutinin (DBA) and BSAI-B4.

Results: The results indicated that, although there were no histological changes at the light-microscopic level in the ear development, statistical analysis showed that there was a significant decrease in the uptake of the BSA1-B4 lectin by neurons of spiral ganglion in 14th day of postnatal life in the experimental group compared to  that of the control group (p<0.05).

Conclusions: After noise exposure, in spite of normal neuronal structure, these cells were modified at the molecular level, especially in glycoconjugate expression, influencing the normal physiology of neurons and causing auditory disorders.