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Biomedical subjects

L Nebel

Publications and source records attributed to L Nebel.

At least 73 records · Page 4Linked to original sources
PubMed1979

Differences in concanavalin A-FITC binding to rat spermatozoa during epididymal maturation and capacitation.

Rat spermatozoa from the caput epididymis and cauda epididymis, but not from the testis, demonstrated a crescent of greenish fluorescence on the convex surface of the sperm head, as observed by fluorescence microscopy after staining with concanavalin A-fluorescein isothiocyanate. The percentage of spermatozoa displaying this fluorescent zone decreased during incubation under capacitating conditions, both in vivo and in vitro, suggesting that a glycoprotein zone that is capable of binding concanavalin A was removed or altered during the capacitation period.

Animals↗
PubMed1979

Osteogenesis by periosteal transplant. Experimental study of spinal fusion in rats.

Autogenous transplantation of periosteum was performed in 60 rats. Periosteum was transferred from the femur to the spinal column in the region of thoracic vertebra 8 to lumbar vertebra 2. Follow-up included histological examination and microradiography. New bone formation occurred late and the bones were of a heterotopic nature; a solid arthrodesis was not achieved. Free periosteal grafts do not exhibit the relatively predictable behavior of periosteal flaps. Greater understanding at the biomolecular level may be required before free periosteal grafts can be introduced into routine clinical practice.

Animals↗
PubMed1978

Changes in concanavalin A agglutinability during development of the inner cell mass and trophoblast of mouse blastocysts in vitro.

Mouse blastocyst cultures were analysed for Concanavalin A (Con A) agglutinability by microhaemadsorption methods and for Con A binding capacity with Rhodamine-Con A stain. The inner cell mass, which was not agglutinable in the early culture stages, became agglutinable when it started to develop. The trophoblast, which was initially agglutinable, lost this property as the cells matured. There was no apparent correlation between changes in agglutinability and capacity to bind Rhodamine-Con A. The pattern of change in Con A agglutinability which characterized development of the inner cell mass and trophoblast is consistent with an interpretation that agglutinability was related to the migratory activities of these cells. The loss of agglutinability associated with trophoblast maturation may have been due to alterations in Con A receptor accessibility.

Agglutination↗
PubMed1978

Hyaluronidase release from guinea pig spermatozoa as affected by reproductive tract secretions and metabolic inhibitors.

Cauda epididymal sperm of mature guinea pigs were incubated (37 degrees, 5% CO2 in air). 10% of the total enzyme activity was released into the medium in 4 hr, 30% in 24 hr. Addition of lysolecithin resulted in rapid release of hyaluronidase. Vitamin C (0.54 mM), sodium fluoride (0.02 M), and cholesterol increased the rate of release whereas citrate (20 mM) diminished it. No effect upon hyaluronidase release was noted upon addition of KCN (10(-2)M), progesterone (250 microgram/ml), testosterone (500 microgram/ml), spermine (1.15 mg/ml), inositol (5.6 mM), or chloroquine phosphate (0.54 mM).

Animals↗
PubMed1977

Autograft suture in peripheral nerves.

Fresh collagen fibers prepared from rabbit tendons or aponeurosis were inserted in either median or sciatic nerves of the same animal. The tissue reactions induced by the autologous fibers were compared histologically with those caused by similarly inserted silk, catgut and homograft sutures in contralateral nerves. Sham operations, passing empty needles, were performed on control nerves. The treated nerves were removed on the 5th to the 30th postoperative day, and histological sections were prepared. The insertion of the different sutures in peripheral nerves resulted in tissue reactions of varying types and degrees, depending on the material used. Catgut and silk thread induced extensive degenerative and inflammatory reactions which persisted for more than 4 weeks. Homograft sutures underwent rapid organization with a minor degree of degeneration and inflammation, which persisted for only a short time. Autograft fibers resulted in minimal myelin degeneration and mild inflammatory processes for 5-10 days, which was only slightly different from the regular course of healing seen in sham-operated control nerves. These intial observations suggest that sutures of autograft fibers may prove advantageous in nerv repair.

Animals↗
PubMed1977

Studies of sperm antigenicity. 6. In vivo and in vitro cellular reactivity in guinea pigs sensitized with fractions of guinea pig spermatozoa.

Normal guinea pig spermatozoa cells were homogenized by a French pressure cell. Three soluble and three insoluble fractions were obtained by ultrascentrifugation and (emulsified in CFA) were used for guinea pig sensitization. The following were observed: 1) all fractions were immunogenic except one; 2) in vivo and in vitro delayed hypersensitivity was elicited in animals immunized with these fractions; 3) two distinctive histopathologic lesions were observed in the testes of sensitized animals: lesions of orchitis type developed in animals injected with some fractions. Other fractions induced lesions of aspermatogenic type. These results correlated well with delayed hypersensitivity results obtained by in vivo and in vitro tests. Although some other spermatozoal fractions did not cause severe changes in the testes. The lack of sperm accumulation in the epididymis was obvious.

Animals↗
PubMed1977

In vitro anti-kidney effect of lymphocytes in experimental immunization to placental antigens.

The lymph node and spleen lymphocytes of placenta-sensitized guinea pigs were tested for their ability to destroy kidney monolayer. It was shown by microcytotoxicity assay that these sensitized lymphoid cells killed target monolayer at different effector/target cell ratios. About 35% of kidney cells were destroyed when sensitized lymph node cells were added at a ratio of 500: 1, and 50% at a ratio of 1000:1. Immunized spleen cells produced approximately the same results. No significant cytotoxicity was measured when placenta-sensitized lymphocytes were added to nonrelated mouse skin fibroblasts. In order to exclude the possibility of participation of species-specific antigens in this experimental model, placenta-sensitized lymphocytes were added to L-cell monolayer in the presence of kidney antigens or mouse normal serum (a carrier of species-specific determinants). An extensive cytotoxic effect was observed in the presence of kidney antigens, while addition of mouse normal serum did not induce significant target cell lysis. The cross-reactivity of the cytotoxic ability of placenta-sensitized lymphocytes may indicate that cell-mediated immunity can be involved in the pathogenesis of nephropathy in toxaemic pregnancies, accompanying sensitization by placental antigens.

Animals↗
PubMed1977

The effect of Imuran on implantation and early embryonic development in rats.

Pregnant rats were injected daily with 2, 4, and 20 mg/kg of Imuran from the first day of gestation until sacrificed on Days 6-12. Gravid uteri, as well as maternal organs, were removed and examined histologically. According to the histologic findings, the treatment with the high dose of 20 mg/kg/day Imuran induced injuries to the blastocyst. Starting from Day 8, the trophoblastic layer lost its continuity and maternal blood invaded into the blastocystic cavity resulting in destruction of embryonic tissues. This degeneration progressed until evident resorption on Day 12. Smaller doses, such as 2 or 4 mg/kg of Imuran, did not result in early trophoblastic damage. The effect seemed to be the result of the antimetabolic effect of Imuran acting on the proliferating trophoblast through the maternal blood.

Animals↗
PubMed1976

Studies on sperm antigenicity, 5. In vivo and in vitro cellular reactivity in guinea pigs sensitized with fractions of human spermatozoa.

In vitro delayed type hypersensitivity was demonstrated with peritoneal exudate cells from guinea pigs immunized with different preparations of human and guinea pig seminal components emulsified with complete Freund's adjuvant-H37Ra. The seminal components were intact human spermatozoa (HuSp); intact guinea pig spermatozoa (GPSp); human seminal plasma (HuSePlFr); and fractions of human spermatozoa obtained by centrifugation of the homogenate at 5,000 X g (5S30 and 5p30), at 20,000 X g (20S30 and 20p30), and at 144,000 X g (144p120). Cellular sensitivity was demonstrated in vivo by skin testing and in vitro by the macrophage inhibition technique. Peritoneal exudate cells from guinea pigs sensitized with fractions 5p30 and 20p30 elicited a delayed hypersensitivity reaction which could be detected only with intact human spermatozoa. Other human spermatozoal fractions (5S30, 20S30, and 144p120) were weak immunogens. Sensitization of guinea pigs with fractions of human spermatozoa, in addition to causing delayed hypersensitivity reactions, elicited low titers of spermatoxic antibodies. Antibodies to human spermatozoal fractions 5S30, 5p30, 20S30, and 20p30 cross-reacted with intact human spermatozoa and intact guinea pig spermatozoa. It is postulated that the existence of "spermatozoa-specific" coating antigen(s) derived from other components of the reproductive tract might be responsible for human spermatozoal antigenicity.

Animals↗
PubMed1975

Studies on sperm antigenicity. IV. Lymphocyte cytotoxicity in cell-mediated response to homologous spermatozoa.

In the presence of specific antigen, lymph node cells from Rockefeller strain guinea pigs with delayed hypersensitivity to homologous spermatozoal antigen produced progressive destruction of L929 cell monolayers. This effect was measured by counting surviving target cells removed from Leighton tubes by trypsin treatment as well as by standard cell counts in microplates. The cytotoxic effect was immunologically specific since neither sperm-sensitized lymphocytes in presence of unspecific antigen nor normal lymph node cells with guinea pig sperm, induced target cell destruction. The effect required an antigen concentration equal to, or greater than, 70 micrograms protein/ml. A ratio of 100:1 of sensitized lymphoid cells to target cell was found to be optimal. L-cell lysis could be demonstrated at day 14 and reached its peak on day 21 after immunization. A high level of correlation between lymphocyte cytotoxicity and macrophage migration inhibition was found. The role of lymphocyte cytotoxicity in cell-mediated immunity to spermatozoa is discussed as one of the possible mechanisms leading to destructive changes in the testes.

Animals↗
PubMed1975

Studies on sperm antigenicity. 2. In vivo and in vitro cellular reactivity in guinea pigs sensitized to homologous and heterologous spermatozoal autoantigens.

In vitro delayed type hypersensitivity was demonstrated with peritoneal exudate cells from guinea pigs of the Rockefeller and Hartley strains, immunized with different preparations of the guinea pig male reproductive tract (RMT) emulsified in complete Freund's adjuvant-H37Ra. The RMT preparations were purified guinea pig spermatozoal autoantigens S, P, and T; whole guinea pig spermatozoa, and extract from epididymal tissue. The cellular sensitivity in vivo was demonstrated by injecting the proper antigen into the skin of the tested animals and in vitro by the macrophage inhibition technique. Peritoneal exudate cells from guinea pigs sensitized with whole guinea pig spermatozoa cells were inhibited in vitro by the specific antigen, epididymal extract, and autoantigen-T. Autoantigen-S was found to be a weak immunogen. However, the migration of peritoneal exudate cells from guinea pigs sensitized with large amounts of antigen-S was inhibited by whole spermatozoa in vitro. This cross-reactivity revealed the possibility that the immunogenicity of purified autoantigen-S might be connected to its molecular size. According to the immunizing dose of the antigens, testicular lesions of either the aspermatogenic or orchitis type were found in the testes of sensitized guinea pigs. Lesions in the testes of the guinea pigs were not detectable by cross-immunization with heterologous human or rat spermatozoa, although some degree of in vitro cross-reactivity was detected by skin test studies.

Animals↗