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    Beneficial effects of melatonin on reperfusion injury in rat sciatic nerve
    (Blackwell Munksgaard, 2004) Sayan, H.; Ozacmak, V.H.; Özen, O.A.; Coskun, O.; Arslan, S.O.; Sezen, S.C.; Aktaş, R.G.
    Studies have shown that ischemia-reperfusion (I/R) produces free radicals leading to lipid peroxidation and to damage of the nervous tissue. Melatonin, a main secretory product of the pineal gland, has free radical scavenging and antioxidant properties and has been shown to diminish I/R injury in many tissues. There are a limited number of studies related to the effects of melatonin on I/R injury in the peripheral nervous system. Therefore, in the present study, the protective effect of melatonin was investigated in rats subjected to 2 hr of sciatic nerve ischemia followed by 3 hr of reperfusion. Following reperfusion, nerve tissue samples were collected for quantitative assesment of malondialdehyde (MDA), an oxidative stress marker, and superoxide dismutase (SOD), a principal antioxidant enzyme. Samples were further evaluated at electron microscopic level to examine the neuropathological changes. I/R elevated the concentration of MDA significantly while there was a reduction at SOD levels. Melatonin treatment reversed the I/R-induced increase and decrease in MDA and SOD levels, respectively. Furthermore, melatonin salvaged the nerve fibers from ischemic degeneration. Histopathologic findings in the samples of melatonin-treated animals indicated less edema and less damage to the myelin sheaths and axons than those observed in the control samples. Our results suggest that administration of melatonin protects the sciatic nerve from I/R injury, which may be attributed to its antioxidant property.
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    The mast cells in semen: Their effects on sperm motility
    (Taylor & Francis Inc, 2003) Cıncık, M.; Sezen, S.C.
    This study was conducted to evaluate any possible association between mast cells and sperm concentration, morphology, and motility. The study comprised 400 patients who had applied for semen analysis. To evaluate mast cells, 6 smear slides were prepared for each subject and stained with 1% toluidin blue-pyronine (pH 4). The slides revealing any mast cells were labeled as mast (+). Concentration and motility was evaluated through a Makler chamber. Kruger's strict criteria were used in morphometric analysis. The mean age of 86 mast (+) cases (21% of total patients) was 31+/-6.7; progressive sperm motility rate was 33+/-21.2. The mean concentration was 32+/-30.2x10 6 /mL, and normal sperm percentage was 11.8+/-6.5. Progressive sperm motility rate in the mast (-) cases were 53+/-25. The mean age of mast cell (+) patients was higher than that of mast cell (-) patients ( t =3.57, p <.001), while they had lower sperm concentration ( p >.05) and lower normal morphologic sperm rate ( t =2.26, p <.024), compared to mast cell (-) patients. The relation between mast cell (+) and mast cell (-) cases and sperm progressive motility was statistically significant ( t =6.44, p <.001). It was concluded that sperm parameters were negatively affected by mast cells.
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    Oocyte membrane maturation and oocyte-sperm relationship: Transmission electron microscopy study
    (Taylor & Francis Inc, 2003) Sezen, S.C.; Cincik, M.
    The success of in vitro maturation (IVM) depends greatly on the acquisition of immature oocytes. Immature oocytes in prophase I (PI) and metaphase I (MI), aspirated after controlled ovarian hyperstimulation, were incapable of fertilization, leading to a lower fertilization rate. Therefore, they must be evaluated on a fine structure level for their in vitro maturation (IVM) processes and their relationship with sperm. Oocyte membrane maturation and oocyte-sperm relationship were studied using transmission electron microscopy. A total of 55 human oocytes obtained from 20 patients at various times and 83 oocytes obtained from the dissected ovarians of female Wistar rats were used for transmission electron microscopy (TEM) evaluation. Despite being in either prophase I and metaphase I or in metaphase II, the oocytes were not fertilized after 48 h of incubation. At the various stages of maturation between PI and MII, the number and the size of microvilluses on the oocyte membrane increased as MII approached and decreased after full maturation. Oocyte activation was related to oocyte membrane maturation and has an effect on the oocyte sperm penetration.