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Biomedical subjects

O Genbacev

Publications and source records attributed to O Genbacev.

At least 55 records · Page 3Linked to original sources
PubMed1979

[Importance of determining gonadotropin levels in the serum in secondary amenorrhea].

On the basis of the results of the analysis of FSH, LH, and prolactin values in the serum of patients with secondary ammenorrhea, four groups of patients were formed: group 1 with low values of both gonadotropin hormones, group 2 with low FSH and high LH values, group 3 with high FSH and high LH values, and group 4 with the basdal gonadotropin values within normal. The use of functional tests proved helpful in the differentiation of the causes of amenorrhea. The use of the LH-RH test is of particular significance in the differentiation of the degree of changes in patients from group 1 and 4. To determine adequate therapy, the determination of estrogen in patients from group 1 and 3 is imperative. A successful treatment of secondary amenorrhea depends on its duration and a timely detection of its causes.

Amenorrhea↗
PubMed1977

Effect of prostaglandin PGE2alpha on the synthesis of placental proteins and human placental lactogen (HPL).

The biosynthesis of placental proteins and placental lactogen (HPL) was studied in vitro in 10-12 week, 16-18 week and term human placenta in the presence and absence of PGF2alpha. The highest 14C-leucine incorporation was detected in 10 to 12 weeks old placentas of PGF2alpha to the incubation medium depressed the rate of incorporation of 14C-leucine into placental proteins in a dose dependent manner. Placentas most sensitive to this action of PGF2alpha were those obtained at 18 weeks of gestation followed by placentas at term. In vivo application of PGF2alpha for therapeutic induction of abortions resulted in the marked inhibition of placental protein synthesis in vitro.

Abortion, Induced↗
PubMed1975

Pituitary cell activities in gonadectomized rats treated with estrogen.

The incorporation of 14C-leucine into LTH and STH, the uptake of 3H-estradiol into the pituitary and the appearance of the LTH and LH cells were studied in male and female rats gonadectomized at the age of 30 days and chronically treated with estradiol (E). The biosynthesis of LTH in the pituitary of ovariectomized rats was decreased 15 and 60 days after the operation to the level of intact males. This decrease is followed by the reduction of the number of immunochemically stained LTH producing cells. Chronical administration of estradiol stimulated the LTH synthesis and maximal incorporation of 14C-leucine was obtained in ovariectomized rats. Maximal relative increase of labeled LTH was noticed in the pituitaries of intact male rats treated with E. STH synthesis is inhibited by treatment with E and maximal decrease was obtained in intact males. The luteinizing LH cells were still hypertrophic in the pituitaries of gonadectomized E treated rats, but the number of castration cells was reduced. On the basis of these results we can conclude that the castration of 30-day-old rats of both sexes does not alter the sex difference in the reaction of LTH and STH cells to estradiol.

Animals↗
PubMedDate not supplied

Coincubation--an experimental approach to the study of decidual-trophoblast interaction.

Coincubation of trophoblast and decidual tissue explants was used for the study of placental-endometrial interaction in early pregnancy. To this end two types of experiments were performed: coincubation with (type A) and without (type B) direct tissue contact. The rate of incorporation of [14C]leucine into cytosol proteins in both tissues was employed for the estimation of total protein synthesis. Prolactin production in vitro was used as a specific marker of the decidual and hCG of the trophoblast cell function. The results show that the type A coincubation experiments produced a strong inhibition of cytosol protein synthesis in both tissues. PRL production by the decidual tissue and hCG production by the trophoblast tissue was reduced. In the type B coincubation experiments protein synthesis and prolactin production by the decidual tissue remained within the control range. In the trophoblast tissue explants protein synthesis and hCG production were depressed. The degree of inhibition was, however, lower than that in type-A experiments. Based on these results it was concluded that the in vitro model of coincubation of trophoblast and decidual tissue explants is suitable for the study of the role of tissue interactions in vitro.

Chorionic Gonadotropin↗
PubMedDate not supplied

Villous culture of first trimester human placenta--model to study extravillous trophoblast (EVT) differentiation.

During implantation and subsequent placentation the human extravillous trophoblast (EVT) cells invade the endometrium and maternal vasculature within the uterus. The origin of the EVT and signals triggering its differentiation, migration and invasion are poorly understood. First and second trimester human chorionic villi explants were used as a source of EVT and a variety of substrates which resemble extracellular matrix (ECM) in vivo have been tested to induce EVT differentiation and migration. The obtained results demonstrate that villous explants from both 5-7 and 8-10 weeks of gestation give rise to EVT cells in vitro if maintained on the surface of Matrigel or decidual extract supplemented collagen gel. Fetal calf serum (FCS) supplemented media was essential for EVT differentiation and villous trophoblast viability. Immunostaining of both EVT cells and cells from the cytotrophoblastic column with monoclonal antibody Ki67 (cell proliferation marker) indicate that EVT cells differentiate in vitro by proliferation from the tip of anchoring villi. These mononucleated, round-shaped, migrating cells are HLA-A,B,C class I antigen (W6/32) antibody and low molecular weight cytokeratin positive, and do not immunostain with PAI-1 (plasminogen activator inhibitor) and HPL antibodies. Differentiation of EVT was restricted to first trimester villous tissue; explants from second trimester placentae did not give rise to EVT. Tissue viability as monitored by glucose utilization, lactate, progesterone and hCG production rates correlated with EVT differentiation. The production rates for hCG demonstrated significant variation among individual placentae and was maintained constant for 10 days consistently only in explants cultured on decidual extract supplemented collagen matrix. The described villous tissue culture system may be, therefore, a unique in vitro model to study proliferation and differentiation of EVT from cytotrophoblastic columns, the regulation of EVT proliferation and differentiation, the role of ECM in the induction of the migration and the interaction of extravillous and villous trophoblast at the level of the cytotrophoblastic column.

Cell Differentiation↗
PubMedDate not supplied

Maternal smoking inhibits early human cytotrophoblast differentiation.

Differentiation of the specialized epithelial cells of the placenta, termed cytotrophoblasts, is a particularly important aspect of placental development during the first trimester of pregnancy. During this process cytotrophoblast stem cells either fuse to form the syncytium or aggregate to form cell columns that adhere to, then invade the uterus. We found that chorionic villi from early gestation placentas of mothers who smoke showed a marked reduction in cell columns, a defect that could not be corrected by placing them in culture. We used two different in vitro models to determine if nicotine plays a role in the etiology of this defect. Exposing early gestation chorionic villi from nonsmoking women to nicotine inhibited subsequent cell column formation in vitro. Nicotine also inhibited normal first trimester cytotrophoblast invasion, apparently by reducing the ability of treated cells to synthesize and activate the 92 kDa type IV collagenase, an important mediator of invasion in vitro. These results suggest that maternal cigarette smoking inhibits the trophoblast differentiation pathway that leads to column formation and uterine invasion. This effect, which is due at least in part to the effects of nicotine, may contribute to the growth retardation observed in fetuses of mothers who smoke during pregnancy.

Adolescent↗
PubMedDate not supplied

In vitro differentiation and ultrastructure of human extravillous trophoblast (EVT) cells.

Tissue explants of anchoring villi from the first trimester placentae cultured on extracellular matrix (Matrigel) give rise to EVT cells in vitro. This study was designed to address two issues important for further application of the described in vitro model: first, were the observed EVT cells derived by cell proliferation in vitro and second, what is the degree of homology between the in vivo and the in vitro differentiated EVT cells. The cultures (tissue and matrix) were prepared for light and electron microscopic (EM) examinations. Semi-thin sections from Spurr epoxy resin-embedded tissue were used to 'pop-off' the selected area for EM examination. Cell proliferation in vitro was assessed immunohistochemically using proliferative cell nuclear antigen (PCNA) antibodies. Since positive hPL immunostaining has been consistently demonstrated in the invasive subpopulation of EVT cells from placental bed in situ, hPL staining was used as a marker of EVT cell differentiation in vitro. It has been demonstrated that PCNA antibodies immunostained nuclei of cytotrophoblast cells from cell column at the base of the anchoring villi, indicating that these cells expressed proliferative activity in vitro. Cytotrophoblast proliferation resulted in the formation of the flattened zone of cell outgrowths at the tip of anchoring villi. Cells from the distal layer of the cell column detached gradually and migrated into the surrounding matrix. These cells appeared as individual, round-shaped EVT cells with smooth surface cell membrane. Their cytoplasm was rich in glycogen and contained large lipid droplets and flattened cisternae of the RER. Positive PCNA immunostaining, along with the presence of mitotic figures, indicated that EVT cells in vitro retained the ability for cell proliferation. As a result of cell proliferation and migration, the number of EVT cells increased during the culture period of 4 days. EVT cell glycogen content and lipid stores decreased progressively as they migrated into the matrix. Individual EVT cells, as well as EVT cell clusters, became surrounded by the clear zone of digested matrix. Some cells started to express strong positive staining with hPL antibodies as soon as they had migrated outside the villous explant. By day 4 of culture, a small percentage of EVT cells (about 5-10%) ceased to migrate, firmly attached to the substratum and appeared as irregular shaped cells with filopodia-like projections. Their cytoplasm contained dilated cisternae of RER, a small number of glycogen granules and bundles of actin-like filaments located in the cytoplasm inside the plasma membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Differentiation↗
PubMedDate not supplied

Concordant in situ and in vitro data show that maternal cigarette smoking negatively regulates placental cytotrophoblast passage through the cell cycle.

Maternal cigarette smoking is associated with fetal growth restriction and other pregnancy complications. To investigate possible mechanisms involving the placenta, we studied the morphology of first trimester chorionic villi from mothers who smoked. In mothers who smoked > 20 cigarettes/day, floating villi showed focal defects including an absence of cytotrophoblast stem cells and an abnormal thinning of the syncytium. Anchoring villi displayed a striking increase in the number of cytotrophoblast columns that failed to reach the uterus or degenerated in the intervillous space. Many samples showed a significant reduction in the number of anchoring villi. Also, the number of Ki67-positive cytotrophoblasts was dramatically decreased, indicating that fewer cells were in S phase of the mitotic cycle. Together, these results suggested premature depletion of the cytotrophoblast stem cell population. To test this hypothesis, we exposed anchoring villi from nonsmokers to nicotine in vitro and analyzed the effects on cytotrophoblast passage through the cell cycle. Nicotine (0.23 to 6.0 microM) negatively affected the expression of a number of cell cycle regulators/markers and BrdU incorporation, without discernable effects on apoptosis. These results link abnormal placental development secondary to maternal cigarette smoking to a substantial decrease in the mitotic potential of cytotrophoblasts.

Adult↗
PubMedDate not supplied

Post-implantation differentiation and proliferation of cytotrophoblast cells: in vitro models--a review.

Cytotrophoblast cells, specialized placental cells, proliferate early in pregnancy and then differentiate into tumour-like cells that invade the uterus and its vasculature. We have established in vitro models of three-dimensional cultures for anchoring villi and cell islands on extracellular matrix in order to study regulation of cytotrophoblast cell differentiation and proliferation. It has been demonstrated that cytotrophoblast cells from cell islands and cell columns share the same characteristics and that their differentiation is triggered by interaction with the extracellular matrix. The fact that during much of the first trimester maternal blood flow to the placenta is at a minimum, suggests that oxygen tension might regulate cytotrophoblast proliferation and differentiation. Hypoxia, comparable to that encountered by early gestation cytotrophoblast cells in the intervillous space, stimulated the cells to enter the cell cycle and inhibited their differentiation along the invasive pathway. Thus, oxygen gradient and cell-matrix interactions at the maternal-fetal interface play an important role in the regulation of cytotrophoblast proliferation and differentiation.

Cell Culture Techniques↗
PubMedDate not supplied

Endocrine profile of 45 patients with Sertoli cell only syndrome.

The basal serum levels of FSH, LH, prolactin and testosterone were determined in 45 patients with Sertoli cell only syndrome and were compared with the same in patients with Klinefelter's syndrome, oligozoospermic men and normal, fertile men. The serum FSH and LH levels in patients with Sertoli cell only syndrome were significantly higher than in normal males. The elevation of gonadotropins in patients with this syndrome was not so high, and the testosterone not lowered, as those in patients with Klinefelter's syndrome. The finding that the basal serum LH levels were elevated and serum testosterone levels were in normal range, demonstrated that there was compensated dysfunction of the Leydig cells in patients with Sertoli cell only syndrome.

Adult↗
PubMedDate not supplied

Sperm morphology and motility in different age populations.

A prospective study of 77 semen specimens was conducted by routine examination of patients reporting to our laboratory for sterility problems. Abnormal spermatozoa were found mostly in patients over 40 years of age. The most frequent head abnormality was angulation of head (found in 94% of patients) and the most frequent tail abnormality was bent jail (found in 90% of patients). Immature spermatozoa were noted mostly in patients over 40 years of age. Motile sperm concentration was higher in patients up to 26 years of age. However, there was a remarkable heterogeneity of routine andrological parameters within the examined groups.

Adult↗
PubMedDate not supplied

[Determination of the concentration of sex hormone-binding globulin in the clinical evaluation of women with secondary amenorrhea].

The serum SHGB (sex-hormone-binding globulin) concentration was measured in patients with secondary amenorrhea in order to determine its role in the regulation of androgen and estrogen metabolism in the course of the normal and irregular menstrual cycle. SHBG concentration was lower than in the control group in 52% of amenorrheic patients, but this difference was not statistically significant due to great individual variations. If the patients were divided in 2 groups according to Prolactin (PRL) concentration, significant decrease in SHGB concentration was observed in the group with elevated PRL concentrations. Correlation of SHBG with estrogen (E2), testosterone (T), progesterone (PRG) and PRL was tested and results show the weak correlation (r = 0.4) between SHGB and T and more significant correlation between SHGB and E2 in the group with basal E2 concentration below 100 pmol/1. SHGB test should be included in the evaluation of alterations of androgen and estrogen metabolism.

Adult↗