Effect of the herbicide 4-CPA on human erythrocyte antioxidant enzymes in vitro.

To investigate the possible role of oxygen free radicals and oxidant stress in the toxic effects of phenoxyherbicides, we studied the in vitro effect of 4-chlorophenoxyacetic acid (4-CPA) on various human erythrocyte antioxidant enzymes, namely glucose-6-phosphate dehydrogenase, catalase, selenium-dependent glutathione peroxidase, glutathione reductase and Cu/Zn-superoxide dismutase. 4-CPA added in a dose of 1 ppm to human erythrocytes for 1 h caused a significant reduction in glucose-6-phosphate dehydrogenase (P <0.001) and catalase (P <0.001) activities, but did not significantly affect the activities of other enzymes. Such selective inactivation of specific erythrocyte antioxidant enzymes may play a role in the toxic effects of phenoxyherbicides.

Structural changes in placental barrier of smoking mother. A quantitative and ultrastructural study.

Human placental villi from all three trimesters of pregnancy, in 90 non-smoking pregnants and 244 cigarette smoking pregnants, were investigated. In smokers, the numbers of syncytial knots and cytotrophoblastic cells increased, depending on the cigarettes per day, syncytial buds and vasculo-syncytial membranes decreased as the pregnancy proceeded. The mean birth weight and placental weight in smokers were decreased, depending on the cigarettes per day at the third trimester. The ultrastructure of placental villi from smokers were compared with that on non-smokers. The villi from smokers had abnormalities of the microvilli, focal syncytial necrosis, decreased syncytial pinocytotic activity, degenerated cytoplasmic organelles. Using a morphometric method, the basement membranes were measured throughout pregnancy. The mean thickness of the basement membranes of trophoblastic layer and fetal capillary were found to not only increase with the maternal smoking during pregnancy but also attain the maximum in the heavy smokers by the third trimester of pregnancy. There was increased collagen in the villous stroma and shrinkage endothelial changes in fetal capillaries, in smokers the deleterious effect of the cigarette smoking on the placental barrier was heavy damage. As a result of impairment of placental barrier, the transports between mother and fetus were hampered.

Immunohistochemistry of matrix metalloproteinases (MMP), their substrates, and their inhibitors (TIMP) during trophoblast invasion in the human placenta.

The invasion of extravillous trophoblast cells into the maternal endometrium is one of the key events in human placentation. The ability of these cells to infiltrate the uterine wall and to anchor the placenta to it as well as their ability to infiltrate and to adjust utero-placental vessels to pregnancy depends, among other things, on their ability to secrete enzymes that degrade the extracellular matrix. Most of the latter enzymes belong to the family of matrix metalloproteinases. Their activity is regulated by the tissue inhibitors of matrix metalloproteinases. We have studied the distribution patterns of matrix metalloproteinases-1, -2, -3, and -9 and their inhibitors TIMP-1 and TIMP-2 as compared to the distribution of their substrates along the invasive pathway of extravillous trophoblast of 1st, 2nd, and 3rd trimester placentas by means of light microscopy on paraffin and cryostat sections as well as at the ultrastructural level (only 3rd trimester placenta). The comparison of different methods proved to be necessary, since the immunohistochemical distribution patterns of these soluble enzymes are considerably influenced by the pretreatment of tissues. All three methods revealed immunoreactivities of both, proteinases and their inhibitors, not only intracellularly in the extravillous trophoblast but also extracellularly in its surrounding matrix, the distribution patterns depending on the stage of pregnancy and on the degree of differentiation of trophoblast cells along their invasive pathway. Within the extracellular matrix, immunolocalization of matrix metalloproteinases as well as their inhibitors showed a specific relation to certain extracellular matrix molecules.

The role of antioxidants in the prevention of t-butyl hydroperoxide-induced chemiluminescence.

An experimental system which assesses the antioxidant potential of ascorbic acid, glutathione, uric acid, and taurine was developed. The system comprised hemoglobin, luminol, t-butyl hydroperoxide, and different concentrations of antioxidants in TRIS-HCl buffer (pH 7.4). Control assays were performed by excluding antioxidants. Chemiluminescence was detected using a liquid scintillation counter in single photon mode. All antioxidants, when applied in the appropriate concentrations, decreased the maximum chemiluminescence values. The minimum concentrations which decreased the chemiluminescence values were defined for each of the antioxidants.

Menstrual effluent induces epithelial-mesenchymal transitions in mesothelial cells.

BACKGROUND: Menstrual effluent affects mesothelial cell (MC) morphology. We evaluated whether these changes were consistent with epithelial-mesenchymal transitions (EMT). METHODS: Monolayer cultures of MC were incubated overnight in conditioned media, prepared from cells isolated form menstrual effluent, with or without kinase and ATP inhibitors. Changes in cell morphology were monitored using time-lapse video microscopy and immunohistochemistry. Effects on the expression of EMT-associated molecules were evaluated using real-time RT-PCR and/or Western blot analysis. RESULTS: Incubation in conditioned media disrupted cell-cell contacts, and increased MC motility. The changes were reversible. During the changes the distribution of cytokeratins, fibrillar actin and alpha-tubulin changed. Sodium azide, an inhibitor of ATP production, and Genistein, a general tyrosine kinase inhibitor, antagonized these effects. Wortmannin, a phosphatidylinositol 3-kinase inhibitor, and SU6656, an Src tyrosine kinase inhibitor, only partially antagonized the effect. The expression of Snail and vimentin was markedly up-regulated, whereas the expression of E-cadherin was decreased and cytokeratins were altered. CONCLUSIONS: In MC, menstrual effluent initiates a reversible, energy-dependent transition process from an epithelial to a mesenchymal phenotype. Involvement of the (Src) tyrosine kinase signalling pathway and the changes in the expression of cytokeratins, Snail, vimentin and E-cadherin demonstrate that the morphological changes are EMT.