PubMed Health⌕ Search

Biomedical subjects

L Nebel

Publications and source records attributed to L Nebel.

At least 55 records · Page 3Linked to original sources
PubMed1983

Activity of natural killer cells in normal pregnancy and edema-proteinuria-hypertension gestosis.

Natural killer cytotoxicity of peripheral blood lymphocytes in normal pregnancy and edema-proteinuria-hypertension (EPH) gestosis was investigated and compared to natural killer cytotoxicity in lymphocytes of normal nonpregnant control donors. These lymphocytes were also compared for their ability to respond to interferon treatment in vitro. Natural killer activity was found to be only slightly decreased in normal pregnant women but was found to be increased in patients with EPH gestosis. Interferon treatment of peripheral lymphocytes caused strong enhancement of natural killer activity in lymphocytes of normal pregnant women but resulted in only weak activities in lymphocytes from patients with EPH gestosis. We consequently concluded that pre-natural killer lymphocyte subpopulations from patients with EPH gestosis have already been activated by a presently still unknown stimulator.

Adult↗
PubMed1983

Influence of catecholamines on cochlear action potentials.

Catecholamines were injected intra-arterially in guinea pigs using a rheological model described elsewhere. With this method, apart from the ear, only a relatively restricted area was perfused with catecholamines, and the amount eventually entering the general circulation was insufficient to change the normal BP. The induced vasoconstriction of the labyrinthine vessels affected the cochlear blood flow and caused an increase of 11.34 dB in the mean action potential threshold. When the rate of catecholamine infusion was increased, associating vasoconstriction of the cochlear vessels with increased BP, deterioration of the action potential threshold was limited to only 2 dB. However, decrease in the normal BP under the same experimental conditions raised the threshold by 21.67 dB.

Animals↗
PubMed1983

Transplacental kanamycin ototoxicity in the guinea pig.

The effect of kanamycin on the cochlear sensory epithelium of albino guinea pig fetuses was studied histologically following the administration of 200 or 400 mg/kg body weight kanamycin sulfate to the pregnant mothers for 8 consecutive days at different stages of gestation. Surface view analysis of Corti's organ revealed slight damage following treatment in the middle trimester of gestation and marked damage due to treatment in the last trimester. The pattern of hair cell loss induced during and after the functional differentiation of the cochlea resembled the pattern of ototoxic lesions in the adult ear. The assumed mechanisms for induction of teratogenesis by kanamycin in the fetal organ of Corti are discussed.

Animals↗
PubMed1983

Fresh and cryopreserved fetal bones replacing massive bone loss in rats.

Cartilaginous fetal bones from rat preserved by deep freezing procedures were compared to comparable fresh bones with regard to the following parameters: chemical composition, water and uronic acid contents; cell viability measured by the rate of proteoglycan synthesis; mineralization-ossification status by calcium binding; matrix integrity by the release of uronic acid containing substances; and biological activity as transplants inducing the formation of bone. The transplanted material was chemically analyzed and checked for its rate of proteoglycan synthesis. The quality of the formed bone was similar whether isogeneic or allogeneic, fresh or cryopreserved bone was employed as transplant material. Evidently those various fetal bones may be of clinical value whenever the need for replacement of massive bone loss arises. Although the viability and the cartilaginous nature of the graft are critical, the isogeneity and freshness are of a quantitative advantage only. These biochemical observations were confirmed by roentgenological and histological evaluations of the grafts. An optimal cryopreserving procedure and tests for examining bone candidates for successful grafting are described.

Animals↗
PubMed1983

Concanavalin A agglutinability and immunoadherent properties of rat blastocyst.

Preimplantation rat blastocysts were examined in vitro for concanavalin A agglutinability and antigenic properties on the 5th day of development after flushing and after 24 h in culture, following regional differentiation. Differences were found between the two trophoblastic cell populations with regard to cell membrane receptors to concanavalin A. Immunoadherence hemagglutination tests show that the early trophoblast possesses antigenic properties, which are similarly present in the mural and polar cells of the early preimplantation blastocyst. With later differentiation in vitro, differences can be found between the two trophoblastic cell populations with regard to detectable surface antigens.

Agglutination Tests↗
PubMed1983

Immunoregulatory mechanisms in pregnancy. II. Further characterization of suppressor lymphocytes induced by alpha-fetoprotein in lymphoid cell cultures.

Nonspecific suppressor cell (SPC) activity has been induced in vitro by preculturing splenocytes from normal mice in the presence of mouse amniotic fluid (MAF) and alpha-fetoprotein for 5 days or more. In adoptive transfer experiments in vivo, these AFP-precultured SPC were shown to reduce the humoral response of mice to sheep red blood cells and the cell-mediated cytotoxic response to allogeneic tumor cells. In mixing experiments in vitro, using freshly explanted splenocytes, the AFP-precultured splenocytes abrogated the generation of specific cytotoxic T-lymphocytes in primary mixed lymphocyte-tumor cell cultures. Supernatants of such precultured cells had at best only a marginal effect. These suppressor cells were found to be nylon-wool nonadherent and their effect could be almost completely abolished by treatment with anti-Thy-1, 2 serum plus complement. SPC precursors were found to be sensitive to cyclophosphamide (in vivo) and to hydrocortisone (in vivo and in vitro). At the same time, they are resistant to different doses of radiation.

Animals↗
PubMed1982

Comparison of cornual transfer via laparotomy with utero-cervical transfer of cultured preimplantation rat embryos.

Most work on embryo transfer has used the cornual route via laparotomy for implantation. This method is time-consuming and costly in operating materials. Cervical transfer seems to offer a simpler route and the promise of time and cost saving. Technical difficulties, however, have prevented this method from becoming widely used. It was thought that mastery of this technique is essential to allow large-scale experiments in order to determine the optimal time for reimplantation, the optimal stage whether 8 cells, morulae, or blastocysts, and to compare culture media. All of these will have significant clinical applications. In this work Vickery's method of cervical transfer in mice was modified to include direct vision of the cervix and dilatation before implantation. With this modification equivalent results were found on cervical or cornual transfer, but a higher failure rate on cervical transfer. The results and implications are discussed.

Animals↗
PubMed1982

Immunoregulatory mechanisms in pregnancy. 1. Evidence for the alpha-fetoprotein-induced generation of suppressor cells in vitro.

The generation of active suppressor cells has been induced in vitro by preculturing of splenocytes from normal mice in the presence of mouse amniotic fluid (MAF) and alpha-fetoprotein (AFP). By using freshly explanted splenocytes, addition of such precultured lymphocytes abrogated the generation of specific cytotoxic lymphocytes (CTL) in primary mixed lymphocyte cultures. Effective suppression can be induced only when the precultured cells are added within the first 48 hr of culture. These suppressor cells are nylon-wool nonadherent and their effect could be almost abolished by treatment with anti-Thy-1,2 serum plus complement. The precursors of the suppressor cells are sensitive to hydrocortisone and resistant to low doses of radiation. The induction of suppressor cells by AFP may be one of the mechanisms resulting in deviant immune response during pregnancy and in the newborn.

Animals↗
PubMed1982

Observations on some immune properties of preimplantation rat blastocysts.

Rat blastocysts after 3, 24 or 72 hours in culture, were exposed to antiserum against rat embryo and mouse placenta in the presence of complement. The concomitant exposure damaged the trophoblastic cells and the inner cell mass. Differences were not observed in the nature and strength of the damage between blastocysts with or without zona pellucida. When the cultured blastocysts were exposed first to antisera and only later to complement, the damage seemed to be selective. In the 3 and 24 hour cultured blastocysts, only the trophoblastic cells were destroyed but not the inner cell mass. In the 72 hour cultures, the damage was inflicted to all cells including the inner cell mass, exposed after spreading of trophoblastic cells. The anti-rat embryo serum and the anti-mouse placenta serum had similar effects in low dilutions. In high dilution, the anti-rat embryo serum was more potent. Isolated inner cell masses were cultured up to 72 hours but did not attach to the dish nor spread. Nevertheless, the cells survived, proliferated and differentiated into an outer layer of seemingly endodermal cells.

Animals↗
PubMed1981

The male factor in fertilization of rat eggs in vitro.

Both epididymal and ejaculated spermatozoa give usable rates of fertilization of superovulated oocytes in vitro. The epididymal sperm gave higher rates, but ejaculated sperm were preferred because intra-donor variation was lower than inter-donor variation. A selected population of 14 male donors had normally distributed fertilizing capacity with a mean and standard deviation of 77 +/- 14% (2,823 eggs). Successive ejaculates usually gave similar rates of fertilization. An attempt was made to eliminate dead and agglutinated cells from the ejaculated sperm by filtration through a column of glass beads. Despite the expected marked improvement in the average motility, the eluted spermatozoa were incapable of fertilizing. We concluded that the preferred source of spermatozoa for fertilization in vitro is ejaculated sperm. In the rat, motility and cell morphology are not adequate criteria for fertilizing capacity of treated spermatozoa.

Animals↗
PubMed1981

Renal damage following transplantations of heterologous placental tissue.

Immunological interrelations between placenta and kidney have become a matter of interest with regard to the pathogenesis of preeclampsia. Kidney morphology of Lewis rats was studied following repeated transplantations of heterologous or syngeneic placental tissue. In most of the heterologous placenta-recipient animals, diffuse severe glomerular lesions were found, similar to those seen in women with preeclampsia. In the strongly responding recipients, endothelial cell swelling, narrowing of capillary lumina and proliferation of mesangial matrix were observed. Patchy areas of fluorescence associated with dense IgG deposition, as well as fibrin deposits demonstrated in the affected glomeruli, were correlated with histologic changes. The use of syngeneic placenta as a transplant did not cause histological or immunohistological changes. These findings support the view that differences in histocompatibility antigens between mother and fetus may be involved in the pathogenesis of the nephropathy in preeclampsia.

Animals↗
PubMed1981

Effect of the carbon dioxide laser on the oviducts of rabbits.

Oviducts of 35 mature, white New Zealand rabbits were injured by a laser beam, using various powers from 25 to 40 W, and by a series of pulses of 1/10, 1/20 or 1/100 s duration. The contralateral oviducts served as controls and were injured at similar areas by a scalpel. The injured areas of both tubes were histologically examined at different periods from the time of injury. Enzyme histochemical studies were also carried out. The site of the laser injury was bloodless. There was a delay in the healing process of the laser side. Vessels were sealed at the area where the spot of the laser hits the vessels, but beyond that point a regular thermal damage was noted with thrombus formation such as seen in regular diathermia or scalpel injuries. Enzymatic activity of the epithelium in the vicinity of the laser-injured areas was intact. The thermal damage due to laser injury found in this study is still significant and would necessitate the use of the laser by microtechniques so as to limit the damage of oviduct tissues.

Animals↗
PubMed1979

Cellular hyperreactivity to placenta in toxemia of pregnancy.

It is generally assumed that maternal immune response may be involved in some pathological conditions of pregnancy, such as toxemia. The activity of cell-mediated immunity to placenta was studied in women with gestosis. The leucocyte inhibition technique was employed to test reactivity of peripheral blood leucocytes from postpartum women. The results indicated that leucocyte migration was significantly inhibited in the presence of placental microsomal fraction when blood from toxemic women was used. Thus, about 87% out of 30 studied cases of toxemia showed positive results. At the same time, in only 22% of women with uncomplicated pregnancy was such a positive leucocyte migration inhibition test found. There was no correlation between the severity of the toxemic symptoms and the extent of inhibition. In further experiments the leucocyte migration inhibition test with the microsomal fraction antigens from cadaver kidneys was performed; only 1 out of 6 patients showed positive leucocyte migration inhibition. These findings may suggest that the normal status of the mother is altered towards cellular hyperreactivity to placental antigens in toxemic pregnancy.

Female↗
PubMed1979

Fetal bone grafts do not elicit allograft rejection because of protecting anti-Ia alloantibodies. Implications to the immune survival of fetuses in allogeneic mothers.

In a previous study we showed that allografts of BN fetal bone, unlike allografts of adult bone, are not rejected by allogeneic recipients of the Lewis strain in spite of the existence of major histocompatibility complex (MHC) incompatibility between donors and hosts. In the present study, we analyzed the relationships existing between the host and fetal tissue that determine graft survival. We found that (1) the fetal BN graft, unlike adult grafts, induces in Lewis recipients a vigorous humoral response consisting mainly in the production of IgG antibody that seems to be directed against antigens of Ia-like specificities. (2) The BN rats are genetically defective in their capacity to respond to determinants and thus are not capable of producing anti-Ia antibodies; in accordance, Lewis fetal bone grafts are rejected by the BN recipients. (3) Chondrocytes isolated from fetal mouse bones do express Ia antigenic determinants. We suggest that the survival of an allogeneic fetal graft in an immunologically intact recipient depends on an active and selective immune response directed against the Ia components associated with the MHC on the embryonic and fetal cells. On the basis of these notions, we propose that the capacity of Ia determinants expressed on cells of the embryo, to elicit anti-Ia and IgG alloantibodies in the pregnant mother, determines the capacity of the embryo to escape rejection by the histoincompatible mother.

Animals↗