PubMed Health⌕ Search

Biomedical subjects

V A Lebedev

Publications and source records attributed to V A Lebedev.

At least 19 recordsLinked to original sources
PubMed2004

[Prolactin-binding activity of bovine granulosa cells on luteinization and exposure to somatotropin in vitro].

The influence of luteinization and bovine somatotropin (ST, 5-50 ng/ml) during cultivation of bovine granulosa cells on their ability to bind [125I]-labeled bovine prolactin (PRL) was studied. On the second day of cultivation in serumfree medium, granulosa cells from immature antral follicles underwent spontaneous luteinization, in both the absence and presence of ST. The level of [125I]-PRL specific binding to cells increased after two days of cultivation, with a negative correlation being revealed between estradiol production by the cells and their PRL-binding activity. At the same time, the addition of ST to the culture medium had no effect on the level of [125I]-PRL specific binding to native and luteinizing granulosa cells. The findings suggest a stimulatory influence of the luteal differentiation process on the PRL-binding activity of bovine granulosa cells, this influence is independent of the action of ST.

Animals↗
PubMed2001

Characterization of somatotropin- and prolactin-binding sites on bovine granulosa cells using homologous hormones.

Specific binding of bovine somatotropin (BST) and bovine prolactin (BPRL) to cow granulosa cells from antrum-containing follicles of different diameter was studied. Scatchard analysis of the data revealed a single type of low affinity BST-binding sites on the granulosa cells with dissociation constants similar to those for the BPRL-binding sites. The number of BST-binding sites on the cells decreased with increasing follicle diameter from 3-5 to 6-10 mm. However, the binding capacity to BPRL decreased only in the case of cells from follicles 11-20 mm in diameter. The findings are discussed in relation to the "homologous binding" phenomenon.

Animals↗
PubMed2000

[Reciprocal modulation of regulatory action of prolactin and somatotropin on DNA synthesis in granulosa cells of cows].

A comparative analysis of the individual and joint influence of bovine prolactin (BPRL) and bovine somatotropin (BST) on DNA synthesis in cultured bovine granulosa cells from follicles of 3-5 mm in diameter was conducted, and a possibility for regulation of BPRL binding to receptors on the cells by BST was examined. Despite a unidirectional growth-promoting action of BPRL and BST on granulosa cells, their joint mitogenic effect on the cells was not additive at low concentrations of BPRL. The addition of BST to the culture medium did not alter the biphasic character of dependence of DNA synthesis in the cells on BPRL concentration, but increased the maximum effective concentration of the latter. When culturing granulosa cells with BST, the absence of its influence on the level of BPRL specific binding to the cells was shown. This fact suggests that BST modulating action on the mitogenic effect of BPRL is not a result of a change in the number of free receptors for PRL on granulosa cells. The results obtained are discussed in relation to the notion of similarity of receptor functional properties and intracellular signal ways for PRL and ST.

Animals↗
PubMed2000

[Neurochemical organization of the brain reinforcing systems].

Modern concepts of neurophysiological mechanisms of the brain reinforcing systems are reviewed from A.A. Ukhtomsky's concept of dominanta. The brain mesocorticolimbic system was shown to play a key role in functioning of the brain reinforcing systems. Morphological and neurochemical organisation of this system determining the emotional sphere, was studied. The dopamine system was found to be the main neurochemical tool of the mesocorticolimbic system. Other transmitters, neuromodulators, and hormones play a regulatory role in the latter. The data obtained corroborate the authors' concept of fluctuating emotional gradient.

Animals↗
PubMed1998

Prolactin in follicular fluid and intracellular store calcium in follicular cells are related to morphological signs of ovarian follicle atresia in cows: work in progress.

It is known that prolactin (PRL) is the third pituitary hormone serving gonadotropic function in mammals. However, its role in the regulation of ovarian folliculogenesis and, in particular, its relationship to follicular atresia as well as the mechanism of its influence on follicular cells are poorly understood. We investigated PRL levels in follicular fluids (FFs) and intracellular store calcium ([Ca2+]is) in cell walls of bovine ovarian follicles with diameters of 10 to 20 mm and their relationship to follicular atresia. Ovarian follicles were categorized on the basis of macroscopic criteria and of microscopic examination of granulosa cell (GC) smears. Prolactin concentrations in FFs were measured by RIA and levels of [Ca2+]is in follicular cells were determined by using the fluorophore chlortetracycline. Compared to atretic follicles, morphologically normal follicles were characterized by higher concentrations of PRL in FFs (P < 0.001) and lower contents of [Ca2+]is in follicular cells (P < 0.01). Furthermore, follicles containing no more than 20% of pycnotic GCs had higher levels of PRL in their fluids than those containing over 40% of pycnotic GCs (P < 0.05). Finally, the direct effect of PRL on [Ca2+]is content in follicular cells was studied in vitro. Compared to control, PRL decreased (P < 0.001) the levels of [Ca2+]is in the cells after 24 h culture of follicular walls from morphologically normal follicles in TCM 199 supplemented by 10% fetal calf serum. Our findings suggest that the decline of PRL concentrations in FFs and the rise of [Ca2+]is contents in follicular cells are related to atresia of large bovine follicles and that there appears to be a relationship between the two biochemical parameters.

Animals↗
PubMed1997

[Changes in the content of prolactin and somatotropin and the level of their binding with cells in the growing antral follicles of cows].

The hormone concentrations in the follicular fluid rise along with an increase in follicular diameter whereas the level of their binding to cells declines. The findings suggest that two basic parameters characterizing the degree of prolactin and somatotropin actions on granulosa cells develop in different directions in the course of antral follicle maturation.

Animals↗
PubMed1995

[Multiple primary malignant neoplasms and survival of patients with stage-I lung cancer].

The study group included 2161 patients operated on in 1968-1990. Tumors stage I were morphologically confirmed in 910 cases (T1S-3, T1-375 and T2-532). 827 patients survived 5 years (90.9%); 551 patients-10 years (60.3%). Primary multiple neoplasms (PMN) of different localization were detected in 96 (10.6%) patients with stage I tumors. Thirteen patients (13.5%) died of progression of a second tumor; 17 (17%)-of other causes. Average 5-year survival was 65%, 10 years-53%. These indices in 96 patients with PMNs were 73 and 53%, respectively. Relative risk of PMN in lung cancer was found to be in direct correlation with survival time and to depend, to a large degree, on tumor extension. When PMNs are detected early and treated radically, new primary tumors emergence does not significantly in lung cancer stage I. Preliminary results showed chemotherapy (neoadjuvant one included) to lower the risk of PMN in lung cancer stage I. The most plausible causes of enhanced survival of patients with PMNs are discussed.

Female↗
PubMed1994

[Lactogenic receptors on cow granulosa cells].

Bovine prolactin (BPRL) binding to cow granulosa cells depending on the antral follicular diameter has been studied. The data obtained point to the existence of one type of low affinity PRL-binding sites on granulosa cells. No reliable differences in the parameters of BPRL interaction with lactogenic receptors in the dynamics of folliculogenesis have been found. The recombinant bovine growth hormone and BPRL competitive binding while interacting with lactogenic receptors has been shown that suggests action of these hormones at over the same binding sites on cow granulosa cells.

Animals↗
PubMed1991

[Heterogeneous forms of prolactin in the blood and colostrum of ruminants].

The monomer form of prolactin prevailed in the blood of cows and she-goats in the physiological conditions associated with an intensive prolactin secretion. The dimer's content increased at the final stage of lactation and in pregnancy. High level of prolactin was found in the colostrum, a form of the prolactin with the milk mass over 100000 having been identified in the soluble fraction of milk. This particular form seems to appear directly in the mammal gland by means of binding of the monomer with an unknown protein.

Animals↗
PubMed1991

[Echographic and morphological parallels in the evaluation of the condition of the uterine scar].

Examinations of 86 women included echography, examination of the lower segment of the uterus during surgery, control manual examination of the postpartum uterus, and histologic examination of the tissues collected from the so-called cicatrix site. The authors claim that the criteria of the myometrial adequacy are the V-shaped lower segment of the uterus, at least 3-4 mm thick, continuous anterior contour of the uterus, the presence of a homogenous echostructure or a structure with small sites of elevated echogenicity. A balloon-shaped lower segment of the uterus and its thinness (less than 3 mm), no continuity in the uterine contour, predominance of elevated echogenicity incorporations in the echostructure of the cicatrix site indicate the inadequacy of the myometrium at the site of the transverse cicatrix in the lower segment of the uterus. The findings evidence that echography is a highly informative method for the diagnosis of the uterine cicatrix status and that echographic examinations should be widely used to choose the delivery mode for pregnant women with a history of abdominal delivery.

Adult↗
PubMed1991

[Clinical significance of factors affecting the course of pregnancy and the status of newborn infants born to women with uterine scar].

Clinical, ultrasonic (fetoscopy, placentography, Doppler metry of uteroplacental and fetoplacental blood flow), and radioimmunological methods (measurement of follicle-stimulating and luteinizing hormones, estradiol, estriol, progesterone) were used to examine 98 pregnant with a cicatrix onto the uterus. The early neonatal period was studied thoroughly in some newborns. The acid-base balance, umbilical vascular blood gases, arterial blood oxygen saturation, heart rate, blood pressure, and body temperature were measured. Having no clear-cut negative action on the uteroplacental and fetoplacental blood flow, an inadequate cicatrix was found to be a risk factor for fetal hypotrophy. Due to lower adaptative possibilities, the newborns to mothers having a cicatrix onto the uterus should constitute a risk group for complications in the neonatal period. It is concluded that repeated elective cesarean section performed in the period close to delivery is one of the factors that lower perinatal mortality and morbidity of babies born to mothers with a cicatrix on the uterus.

Adult↗
PubMed1991

[Current diagnostic methods and therapeutic principles in various forms of puerperal endometritis].

A total of 55 puerperants+ with endometritis followed by spontaneous labours (26 females) and cesarean operation (29 females) were studied. A comprehensive study involved echography, hysteroscopy, bacteriological analysis of the uterine content, and histological examination of mucosal curettage of the corpus uteri. Three types of the clinical course of endometritis were identified: 1) in the presence of placental tissue residues; 2) with necrosis of delayed decidual tissue and lochia- or hematometra; and 3) a "pure" type of endometritis without abnormal tissues in the uterus. Uterine curettage was performed in the first type of endometritis, vacuum aspiration of its content was carried out in Type 2. The patients from Group 3 who had the most severe inflammatory process of the uterus underwent its cavity washing with large volumes of cold antiseptic solutions, took detoxifying, ++rheo-vasoactive and protein agents, received immunomodulating and uterotonic therapy. The algorithm developed for management of puerperants+ with postpartum endometritis substantially enhanced the efficiency of therapy and prevented severe septic events in time.

Adult↗
PubMed1991

[Endoscopic semeiotics of malignant lymphoma of the stomach].

The authors analyse 7 cases from their own experience and literature data. Among the characteristic signs of malignant gastric lymphoma is multicentric growth of the neoplastic nodes which may be partly covered with the mucosa. An important sign is the presence of multiple ulcerations or erosions which may occur both on the surface of the tumor and on the mucosa of parts of the stomach which are still not affected. A polypiform, cushion-like thickening of the folds is often seen against the background of the infiltrated mucosa. The color of the mucosa is bright and rich, ranging from crimson the bluish. In growth of malignant lymphoma into the stomach from affected abdominal lymph nodes endoscopy reveals a characteristic inward depression of the wall in the zone of involvement and extension of the neoplastic tissue on the mucosa.

Adult↗