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Biomedical subjects

A Meyer

Publications and source records attributed to A Meyer.

At least 343 records · Page 19Linked to original sources
PubMed1988

Studies on the 240-kDa Con A-binding glycoprotein of rat cerebellum, a putative marker of synaptic junctions.

A Con A-binding glycoprotein of Mr 240,000 was isolated from the remaining residue of rat cerebella after sequential extraction with buffers supplemented with or without neutral detergents. It was further purified by affinity chromatography on Con A-Sepharose in the presence of sodium dodecyl sulfate and preparative gel electrophoresis. This glycoprotein partially resists Triton X-100 extraction and is soluble in N-lauryl sarcosinate. The 240-kDa glycoprotein was not detected in kidney, liver, heart, forebrain and was specifically seen in cerebellar homogenate. The isolated glycoprotein appears to be similar, not necessarily identical with the GPA--a synaptic junction 240-kDa Con A-binding glycoprotein isolated from cerebellum earlier (Groswald and Kelly, J. Neurochem., 42 (1984) 534-546). Monospecific antibodies obtained against the purified 240-kDa protein were used for developmental study in normal and hypothyroid rats. There was observed an increase in the amount of 240-kDa glycoprotein, dependent on the age of the rat and this rise was in correlation with the synapse formation in rat cerebellum. The amount of 240-kDa glycoprotein is considerably reduced in hypothyroid rats.

Aging↗
PubMed1988

Histiocytic differentiation in benign and malignant bone tumors.

In this study fresh frozen tissue samples of benign osseous tumors (five non-osteogenic fibromas, one fibrous dysplasia, one chondromyxoidfibroma), tumors of uncertain biological behaviour (eight cases of histiocytosis X, two giant-cell tumors), and of malignant intraosseous tumors (two malignant fibrous histiocytomas, two malignant histiocytosis, four osteosarcomas, one chondrosarcoma and two Ewing sarcomas) were studied with a panel of monoclonal antibodies reactive with monocyte/macrophages and various types of dendritic cells. In addition, tumors were further defined with a broad spectrum of antibodies against filamentous proteins and lymphocyte differentiation antigens. The specimens were stained with a triple-layer immunoalkaline phosphatase protocol. Tumors stained with these antibodies could be roughly divided into two groups. The first group comprised tumors with one predominant cell population reactive with one particular monoclonal antibody. In this group, cases of histiocytosis X were found to be consistently labelled with CD-1 antibodies. The giant-cell tumors showed a very homogeneous staining with certain monocyte/macrophage antibodies (Ki-M8). Nevertheless, even in these tumors, heterogeneity was demonstrated by the occurrence of cells with monocytic differentiation in histiocytosis X and conversely by the occurrence of cells with differentiation antigens of the dendritic cell system in giant-cell tumors. An exception has to be made for the two cases of malignant histiocytosis examined. These tumors were selectively labelled with antibodies against monocyte/macrophages (Ki-M8, IOM-1). The second group comprised tumors showing a high degree of heterogeneity demonstrated by the varying amounts of tumor cells reacting with the applied markers of the monocyte/macrophage and dendritic cell systems. In most cases it was difficult to ascribe labelled cells to the tumor cell population as opposed to an "innocent bystander" inflammatory cell population. This distinction was especially difficult in malignant fibrous histiocytomas underlining the current concept that these tumors are of primitive mesenchymal rather than true histiocytic origin.

Adolescent↗
PubMed1988

Production of growth factors related to fibroblast growth factor and platelet-derived growth factor by human embryonal carcinoma cells.

Previous studies have demonstrated that mouse embryonal carcinoma (EC) cells produce at least two growth factors: one related to platelet-derived growth factor (PDGF) and another related to basic fibroblast growth factor (FGFb). Since human EC cell lines are being used with increased frequency, the current study examined whether human EC cells produce growth factors, in particular those produced by mouse EC cells. In this study, it was determined that the human EC cell line NT2/D1 produces a heat-labile heparin-binding growth factor that behaves like FGF in a bioassay. Three additional criteria suggest that this factor is closely related or identical to FGFb. The factor from NT2/D1 EC cells, bovine FGFb and FGFb produced by the human hepatoma cell line SK-HEP-1 elute from heparin at similar salt concentrations. The factor produced by NT2/D1 EC cells exhibits a thermal stability curve that is nearly identical to those for bovine FGFb and FGFb from SK-HEP-1 cells. Lastly, NT2/D1 and SK-HEP-1 cells express transcripts of the same size that hybridize with a cDNA probe for human FGFb. In the course of these studies it was determined that NT2/D1 EC cells also express several transcripts that hybridize with a cDNA probe for the human PDGF A-chain. Thus, our findings suggest that the pattern of growth factor production by human and mouse EC cells is evolutionarily conserved.

Biological Assay↗
PubMed1988

Isolation and immunohistochemical localization of a chondroitin sulfate proteoglycan from adult rat brain.

A chondroitin sulfate proteoglycan called PGM1 has been isolated from the particulate fraction of adult rat forebrain. Delipidation of the material, solubilization of proteoglycans in guanidinium chloride, precipitation at low ionic strength, and final extraction at pH 5.0 were used for its isolation. Proteoglycans were subjected to further purification by diethylaminoethyl-cellulose chromatography. Individual components were separated by gel filtration. PGM1 appeared to be a high-molecular-weight chondroitin sulfate proteoglycan, capable of strong interaction with hyaluronic acid. It was finally isolated by gel filtration on Ultrogel AcA 22 in the presence of 4 M guanidinium chloride. Monospecific antibodies obtained in rabbits against the purified molecule did not cross-react with other brain proteoglycans. Immunocytochemical techniques revealed an almost unique association of this compound with axons, particularly those known to contain neurofilaments. However, not all these axons and all parts of these axons contained PGM1. This component was not detectable in liver, intestine, spleen, kidney, lung, heart, skin, hair, lens, and muscle, a finding suggesting a specificity for the nervous tissue. This component is expressed in neural cell cultures. Despite the preservation of the neuronal specificity, it seems to lose its specific axonal localization in vitro.

Animals↗
PubMed1988

Bioactive glass-ceramics in middle ear surgery. An 8-year review.

An 8-year follow-up of Ceravital middle ear prostheses showed there was extremely good tolerance in the middle ear space. Incompatibility phenomena were not observed, and inflammatory reactions were neither caused nor supported by the implants. The tympanoplasties were always performed without interposition of cartilage between the tympanic membrane or the tympanic membrane graft and the disk-shaped portion of the implant, and extrusions were never observed. Long-lasting inflammatory processes appeared to destroy implants the same way they destroy ossicles. Transient inflammatory periods (such as episodes of purulent otitis media, which occurred soon after the prostheses were implanted) did not lead to any remarkable changes of the surface of the implant. In healthy middle ears, the hearing results were stable.

Biocompatible Materials↗
PubMed1988

Wound coverage with cultured autologous keratinocytes: use after burn wound excision, including biopsy followup.

Cultured autologous keratinocytes (CAK) have been used in eight patients as part of their definitive treatment for burn wound closure. The CAK grafts were placed on surgically excised wounds rather than mature granulation tissue. This technique guaranteed that permanent skin coverage derived from cultured cells, and not residual epidermal cells from surviving dermis. Graft take was variable, ranging from zero in the case of one of the children to 85%. Long-term assessment noted adequate permanent coverage, confirmed by biopsy. Electron micrographs demonstrated no well formed anchoring fibrils, which may account for the graft fragility which has been reported as much as 1 year postgraft. Advantages of using CAK are that an acceptable permanent wound closure can be achieved without depending on donor site availability. An almost unlimited quantity of skin is available because the original biopsy can be expanded manyfold in the laboratory.

Adult↗
PubMed1987

[Antibodies against HIV-2 (LAV-II) in Africa and West Germany].

Antibodies against HIV-2 were tested by indirect immunofluorescence in over 2000 sera from Africa and the Federal Republic of Germany. The specificity of the test for HIV-2 was established by absorption of the sera with HIV-1 infected cells. Antibodies against HIV-2 were found in sera from two of 51 Africans who are living in the FRG. In addition, antibodies against HIV-2 were occasionally found in two of 1396 sera from Central Africa and two of 322 from West Africa. Cross-reacting antibodies were found in four of 189 high risk patients from the FRG who had HIV-1 infection, these antibodies no longer being present after absorption. It would therefore seem that HIV-2 infections are still rare among German risk groups.

Absorption↗
PubMed1987

[Facilitating cervix dilatation of the non-pregnant uterus by intracervical administration of gels containing prostaglandin and calcium chloride].

In a prospective, randomised study, 50 non-pregnant patients were treated intracervically with 3 ml 5% tylose, 50 micrograms sulprostone, 100 micrograms sulprostone gel, 3 ml 2.5 mM or 9.0 mM calcium chloride gel in order to soften the cervix 12-14 hours before diagnostic curettage. The gel was not used in a further 20 patients. To objectively demonstrate the priming effect, the force required for dilatation of the cervical canal was measured in Newtons, using a mechanical tonometer both before gel application and before the operation. In comparison with the administration of tylose only, the intracervical application of either sulprostone gel or calcium chloride gel led to a significant improvement in cervical dilatability. Tylose alone had a slight but measurable effect on the cervix. An increase in sulprostone from 50 micrograms to 100 micrograms or calcium molarity from 2.5 mM to 9.0 mM brought no further improvement in the dilatory effect. Dilatation-induced cervical lesions could be avoided by preoperative cervical ripening. After application of sulprostone, 3 out of 20 patients experienced doses-dependent uterine cramps, while all patients treated with calcium chloride gel were free of side effects. The intracervical administration of sulprostone and calcium chloride gel allowed gentle dilatation of the non-pregnant cervix, thus lowering the risk of uterine lesions. Under clinical aspects, cervical priming facilitates diagnostic and therapeutic procedures, which, in exceptional cases, can be performed without anaesthesia.

Administration, Intravaginal↗
PubMed1987

Nature and immunochemical characteristics of a Ca2+/calmodulin kinase activity endowed in a highly insoluble protein purified from adult rat brain.

Using sequential extraction procedure of proteins from adult rat forebrain, a protein of Mr 52,000, insoluble in neutral detergents, capable of binding calmodulin in the presence of Ca2+, was isolated. Antibodies to this antigen had the capacity to inhibit the Ca2+/calmodulin-dependent kinase activity associated with this protein. This protein (52K) (in many respects identical to the major protein of postsynaptic densities) shares by itself the Ca2+/calmodulin-dependent kinase activity, thus differing from soluble Ca2+/calmodulin-dependent kinases isolated by others. Despite its insolubility in most detergents, the 52K protein is not particularly rich in hydrophobic amino acids. Its richness in cysteine and proline residues suggests that the active conformation of the enzyme is sustained by numerous disulfide bridges.

Amino Acids↗
PubMed1987

Isolation and immunochemical study of a soluble cerebellar lectin delineating its structure and function.

A procedure of sequential extractions of cerebellar tissue was set up, which allowed specific solubilization of endogenous lectins by mannose. Two cerebellar soluble lectins, CSL1 (Mr = 33,000) and CSL2 (Mr = 31,500), were isolated. They appeared to consist of structurally and immunologically related polypeptides chains. By immunoaffinity, another minor component (Mr = 45,000) was isolated. Immunological studies suggested that the minor component is the precursor of the two other, i.e., CSL1 and CSL2, subunits. CSL1 (mainly lysosomal) possesses an additional peptide compared with CSL2 (mainly cytoplasmic and extracellular), which seems to be implicated in the signal for secretion and release.

Aging↗
PubMed1987

[Compatibility of glass-carbon implants in the middle ear--animal experiment studies].

28 tympanoplastic procedures with destruction and reconstruction of the ossicular chain were performed in rabbits. Vitreous carbon implants were used as prosthetic material. The animals were followed up from 14 days to one year. In 23 cases extensive inflammation of the middle ear mucosa was observed macroscopically. The histological findings were formation of an increasing fibrous capsule with duration of time, permanent foreign body reaction at the surface of the implants and missing formation of new bone or contact with bone respectively. Thus vitreous carbon seems to be a less promising material in middle ear surgery.

Animals↗