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Biomedical subjects

M Bayer

Publications and source records attributed to M Bayer.

At least 19 recordsLinked to original sources
PubMed1992

Assembly of hepatitis delta virus particles.

Hepatitis delta virus (HDV) is a subviral satellite of hepatitis B virus (HBV). Since the RNA genome of HDV can replicate in cultured cells in the absence of HBV, it has been suggested that the only helper function of HBV is to supply HBV coat proteins in the assembly process of HDV particles. To examine the factors involved in such virion assembly, we transiently cotransfected cells with various hepadnavirus constructs and cDNAs of HDV and analyzed the particles released into the medium. We report that the HDV genomic RNA and the delta antigen can be packaged by coat proteins of either HBV or the related hepadnavirus woodchuck hepatitis virus (WHV). Among the three co-carboxy-terminal coat proteins of WHV, the smallest form was sufficient to package the HDV genome; even in the absence of HDV RNA, the delta antigen could be packaged by this WHV coat protein. Also, of the two co-amino-terminal forms of the delta antigen, only the larger form was essential for packaging.

Antigens, Viral↗
PubMed1992

Attenuation of postischemic microvascular disturbances in striated muscle by hyperosmolar saline dextran.

The underlying mechanisms of the beneficial therapeutic effects of small-volume resuscitation with hyperosmolar solutions for treatment of hypovolemic shock are still poorly understood. Using the dorsal skinfold chamber model and intravital fluorescence microscopy, we investigated the effects of hyperosmolar saline dextran on ischemia-reperfusion injury in striated skin muscle of awake normovolemic golden hamsters. Test solutions (4 ml/kg body wt i.v.) were administered 2 min before reperfusion after 4 h of pressure-induced ischemia. In animals receiving 0.9% saline (control), we observed a drastic enhancement of leukocyte rolling along and sticking to the endothelium of postcapillary venules 0.5 h after reperfusion. Postischemic leukocyte rolling and sticking were significantly reduced when animals were treated with 7.2% saline alone (HSS), 10% Dextran 60 in 0.9% saline (HDS), or 10% Dextran 60 in 7.2% saline (HHS). In control animals, capillary perfusion was reduced to approximately 60% of preischemic values 0.5 h after reperfusion. Concomitantly, leakage of the macromolecule fluorescein isothiocyanate-dextran (5 mg in 0.1 ml saline i.v., M(r) 150,000) into the perivascular space increased from 0% before ischemia to approximately 12% at 0.5 h reperfusion. In contrast, when animals were treated with HSS, HDS, or HHS before reperfusion, capillary perfusion decreased to a significantly minor extent of approximately 15%, and macromolecular leakage was slightly increased to approximately 5%. Our results suggest that hyperosmolar saline dextran effectively attenuates postischemic microvascular disturbances elicited by ischemia-reperfusion, presumably through reduction of postischemic leukocyte-endothelium interaction and capillary swelling.

Animals↗
PubMed1991

[Surgical treatment of sequelae of injuries of the thoracolumbar spine].

The authors describe surgical techniques used in 48 patients with sequelae of injuries of the thoracolumbar spine and the achieved results. Twenty-one patients were treated by an anterior operation, 14 by posterior operation and 13 a combination of both. The anterior operation involved 1) simple stabilization by autografts or 2) release, correction of the kyphosis and fusion and 3) elimination of the affected body of the vertebra and replacement by a massive allograft. If reliable stability was not achieved, instrumentation was added. In posterior operation they always stabilized the spine by instrumentation and added fusion. In the remaining patients they combined the posterior and anterior operation. The anterior operations were, if necessary, supplemented by decompression, when using the posterior approach they decompressed by the posterolateral route. As to complications which called for re-operation, instrumentation failed once and twice a pseudoarthrosis was repaired. Pain disappeared or receded substantially in 86%. Of 30 patients with a partial nervous lesion 14 (47%) improved, in two slight deterioration occurred.

Adolescent↗
PubMed1991

[Sequelae of injuries of the thoracolumbar spine and indications for surgery].

Inadequate treatment of a fresh injury of the thoracolumbar spine of failure or surgical treatment may lead to substantial restriction of the physical activity of the patient. This is due to posttraumatic kyphosis, possibly its progression, instability, painfulness and a persisting or progressing neurological finding. Forty-eight patients with unstable fracture of the thoracolumbar spine were, except one operated patient, treated originally by conservative methods, 15 of them were moreover subjected to isolated laminectomy. In 30 patients a partial nervous lesion was involved. The majority of patients in the group subjected to laminectomy had a more severe kyphotic deformity which more frequently was progressive. The authors indicated surgery in 18 patients (37%) on account of pain, in 14 (29%) on account of instability, in 12 (25%) on account of progressing kyphosis and in 4 (8%) on account of an increasing nervous deficit. They included 26 patients with persisting partial nervous affections in the group with instability and progressing kyphosis, as anterior compression of the dural sac was revealed and they indicated release of nervous structures as part of the surgical operation. In the remaining partial neurological lesions with a patient spinal canal decompression was not indicated.

Adolescent↗
PubMed1989

Development of an enzyme immunoassay for the serodiagnostic of tuberculosis and mycobacterioses.

An enzyme-linked immunosorbent assay (ELISA) test has been developed for the serodiagnosis of mycobacterioses. The test is based on an interspecific antigen, antigen 60 (A60). This antigen belongs to the group of thermostable macromolecular antigens and is the principal constituent of tuberculin RT 23. A60 is composed of proteins, polysaccharides and lipids in a ratio that varies with the growth cycle of the mycobacterium. The test detects antibodies against mycobacteria and is most effective in cases of active infections. We found that the best way to cope with the day-to-day variations in the results obtained was to transform the absorbance values into arbitrary IgG units. The variations observed with IgM antisera were, however, too great to allow more than a qualitative test. Healthy individuals are negative in the IgG and IgM tests and tuberculous patients are usually positive in the IgG test. The presence of IgM antibodies was only rarely observed. For IgG antibodies, the best discriminative power at a 1:100 dilution of the analyzed sera seemed to lie at 125 sero-units. It was found that some sera originating from clinically documented tuberculous cases responded in a poor way in this test.

Animals↗
PubMed1988

Homologous and crossreacting immune response of the jird and cotton rat against microfilariae of Dipetalonema viteae and Litomosoides carinii (Nematoda: Filarioidea).

Consecutive injections of microfilariae of L. carinii and D. viteae were carried out in the homologous or heterologous sequence into the corresponding natural or into the experimental hosts. Microfilariae of D. viteae are imunogenic in Sigmodon specifically and crossreacting as well. However, in the natural host, Meriones, they are doubtlessly tolerogenic. The sojourn and level of microfilaraemia are prolonged resp. higher when living D. viteae-Mf are injected s.c. followed by an i.v. injection. However, freeze-killed microfilariae of D. viteae are immunogenic in Meriones. Obviously the two filarial worms living in small mammals realize the balance with their natural hosts in quite a different manner. Which one of the two possibilities, or if one of them at all, reflects the relationship in human pathogenic filariae remains open.

Animals↗
PubMed1988

[A ventral mantle technic with dorsolateral mediastinal saturation in the radiotherapy of Hodgkin's disease].

Between 1975 and 1981 69 patients suffering from Hodgkin's disease stage I to III were treated by radiotherapy exclusively. In contrast to the standard modalities the mantle was treated only through a ventral portal with dorsolateral boost to the posterior mediastinum. The geometrical treatment arrangement and the modalities of dose application yielded favourable dose distributions and single doses within the target volume. The analysis of failures showed no in field-failure, six marginal recurrences, and 17 distant failures, which are not related to the technique of irradiation. The described technique of mantle irradiation seems to be equivalent to the standard technique with regard to tumor control and side effects.

Cobalt Radioisotopes↗
PubMed1978

The immunopharmacologic and anti-inflammatory properties of RMI 9563 with special reference to its effect on the complement system.

The immunopharmacology of RMI 9563 - bis[3-(diethylamino)propyl]fluoranthene-3,9-dicarboxylate dihydrochloride--has been described. The compound, when given parenterally, inhibited several cell-mediated immune responses (EAE, tuberculin skin reaction, adjuvant arthritis) in rats, enhanced IgM and IgG antibody-producing cells in mice, and displayed anti-inflammatory activity in several models (carrageenan paw edema, adjuvant arthritis, direct passive Arthus reaction--a model of inflammation that is immunologically induced and complement-dependent). RMI 9563 suppressed the activation of complement in vitro by the selective inhibition of C1 esterase.

Animals↗
PubMed1976

Synthesis of new cyclic nucleotides and their differential stimulatory effects on thyroid function in mice.

Various 8-substituted cAMP analogues were converted into the corresponding N6,O2'-dibutyryl, N6-monobutyryl, or O2'-monobutyryl derivatives and the parent compounds as well as the new derivatives were tested for TSH-like stimulation of the thyroid function in mice in vivo by means of the McKenzie bioassay. It was found that a pronounced stimulatory effect on the thyroid secretion can be produced by certain cyclic nucleotides. The most potent compounds, 8H2N-cAMP, 8MeS-cAMP, and 8N3-cAMP at 15-30 mg/kg iv, showed an activity approximately one order of magnitude higher than that of cAMP and comparable to the action of 0.6-1.0 mU of TSH per mouse iv. Radioimmunological determination of thyroxine levels in the serum confirmed these results. Serum T4 levels in mice injected, for instance, with 8MeS-cAMP (30 mg/kg) rose from 4.85 +/- 0.25 to 6.32 +/- 0.41 mug/100 ml in 1 h, the net increase in T4 being comparable to that produced by TSH (1 mU/mouse) under identical experimental conditions. Introduction of one or two butyryl groups (in the N6 and/or O2' position) significantly increased or decreased the biological activity, dependent on the parent compound, but no direct correlation between biological activity and degree of butyrylation was apparent. The effect of these compounds on the thyroid seems to be specific for cyclic nucleotides because 8MeS-5'AMP which resembles 8MeS-cAMP but lacks the cyclic phosphate structure is inactive in the McKenzie bioassay and in the T4 radioimmunoassay.

Animals↗