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Biomedical subjects

U Müller

Publications and source records attributed to U Müller.

At least 577 records · Page 32Linked to original sources
PubMed1979

Evidence for a gonad-specific receptor for H-Y antigen: binding of exogenous H-Y antigen to gonadal cells is independent of beta 2-microglobulin.

This report addresses the question whether two different types of binding exist for the reaction of H-Y antigen with the cell surface. Anti-H-Y antiserum in the presence of complement was cytotoxic only for gonadal cells expressing their own H-Y antigen, but not to ovarian cells loaded with H-Y antigen. H-Y antigen was co-redistributed with beta 2--microglobulin on newborn testicular cells, but some residual H-Y activity was found on similarly treated testis cells from 15 day old rats. After beta 2--microglobulin redistribution, testis cells maintained their binding capacity for exogenous H-Y antigen prepared from epididymal fluid or Daudi cell culture supernatants. This result suggests that exogenous H-Y antigen is bound via a gonad-specific receptor which is independent of beta 2--microglobulin and that this type of binding for H-Y antigen is different from the beta 2--m-associated expression of H-Y antigen on the cell surface.

Animals↗
PubMed1979

Comparison of skin tests and RAST for the diagnosis of bee sting allergy.

Skin tests and estimation of specific IgE-antibodies by the RAST are evaluated as diagnostic procedures in bee sting hypersensitivity with the followiny extracts. (2) With bee venom results of skin tests and RAST correspond in 82%, with bee wholebody extracts in 68%. (3) Both with skin tests and the RAST with bee venom a good discrimination between patients with bee sting hypersensitivity and non-allergic controls is observed. Skin tests with bee venom are somewhat more sensitive than bee venom-RAST. (4) With the careful skin test procedure chosen, no adverse reactions were observed.

Allergens↗
PubMed1979

Immunotherapy in bee sting hypersensitivity. Bee venom versus wholebody extract.

Fifty-six patients with serologically confirmed bee sting hypersensitivity were treated for 1-3 years with either bee venom (BV) (31 patients) or wholebody extract (WBE) (25 per cent of re-exposed patients on BV-therapy showed a diminished reaction and 75% no reaction. Thirty-three per cent of re-exposed patients on WBE-therapy developed an unchanged or worse reaction, 42% a diminished reaction and 25% no reaction at all. An initial rise in BV-specific IgE was observed in BV-treated patients, whereas IgE levels after 1 year of treatment lay significantly below pretreatment values in both treatment groups. BV-specific IgG increased markedly in patients on BV-therapy and decreased slightly in those on WBE-therapy. The initial IgE increase induced by BV-therapy was insignificant in patients with high pretreatment levels of specific IgG-antibodies. Similarly, re-exposed patients with high BV-specific IgG showed no IgE increase, whereas a substantial rise in specific IgE was observed in those with low IgG. On the basis of clinical and serological results immunotherapy with BV is considered to be clearly superior to immunotherpy with WBE.

Adult↗
PubMed1979

Cross-reactivity to mammalian anti-H-Y antiserum in teleostean fish.

Anti-H-Y antiserum, raised in highly inbred rats, is absorbed by gonadal cells of various species of fish. This cross-reactivity proved to be restricted to the male sex in the cyprinodont species Lebistes and Xiphophorus, known to have the XX/XY mechanism of sex determination. In members of the more primitive fish orders Isospondyli and Ostariophysi, cross-reactivity was shown to occur as well, but the amount of antiserum absorbed was very similar in both sexes. An antigen cross-reacting with mammalian anti-H-Y antiserum is assumed to exist in fish similar to that found in higher vertebrates. If this is true, this antigen may have been shared originally by both sexes. However, during evolution, its expression has become restricted to the heterogametic sex.

Animals↗
PubMed1978

Studies on H-Y antigen in different cell fractions of the testis during pubescence: immature germ cells are H-Y antigen negative.

Various cell types of the rat testis during pubescence, including germ, Sertoli, and Leydig cells, were partially enriched. The fractions were tested for the presence, binding, and secretion of H-Y antigen. The main results are: Immature germ cells are H-Y antigen-negative until the late diploid stages, and late primary spermatocytes or spermatids become positive; the somatic cells of the gonad are positive at all ages examined (18 days old to adulthood). Secretion of H-Y antigen is restricted to the Sertoli cell fraction. Binding of externally supplied antigen takes place on Leydig cells; the Sertoli cell surface will be saturated because of active secretion; there is no binding to germ cells. Thus, immature germ cells seem to be the only H-Y antigen-negative cells of the male organism, and the Sertoli cells seem to be the only ones to secrete H-Y antigen.

Age Factors↗
PubMed1978

Appearance of hCG-receptor after conversion of newborn ovarian cells into testicular structures by H-Y antigen in vitro.

In a previous report (Zenzes et al., 1978b) it was shown that dissociated ovarian cells of newborn rats in vitro, if exposed to H-Y antigen, reorganize into testicular structures. The current study was designed to see whether this morphological conversion also results in a functional conversion. The LH/hCG receptor was used as a parameter characteristic for the newborn testis, but not for the newborn ovary. In the converted ovary, the LH/hCG receptor becomes detectable a few hours after onset of the culture and remains continuously present afterward. The appearance of this receptor may be due to a hormone-like action of H-Y antigen.

Animals↗
PubMed1978

The testis as a secretory organ for H-Y antigen.

After cultivation of dissociated rat testicular tissues, H-Y antigen is detectable in the medium; this is not the case if nongonadal male tissues are incubated. Release of H-Y antigen by testis cells is inhibited by the addition of cycloheximide. All tissues still type H-Y positive after culture. It is assumed that the testis actively secretes H-Y antigen. This assumption is supported by the finding that the amount of H-Y antigen in the epididymal fluid increases with the age of the animals.

Animals↗
PubMed1978

Rapidly adhering cells in two cases of anencephaly.

We report the successful use of a new method described by Gosden and Brock (1977) in two cases of anencephaly; according to this method 'rapidly adhering cells' are identified as neural cells of a specific morphology. Although the original method described adherence of cells during the first 20 h, we were able to identify a considerable number of such cells after a delay of three days due to mailing of the amniotic fluid.

Adult↗
PubMed1978

Binding studies of H-Y antigen in rat tissues: indications for a gonad-specific receptor.

The binding capacity for H-Y antigen was studied in various rat tissues of both sexes. In nongonadal tissues (liver, kidney, brain, epidermis) binding could not be demonstrated. In contrast, the gonads are able to bind exogenously supplied H-Y antigen. In the ovary, the binding capacity remains unchanged in newborn and adult animals, while in the testis, this capacity decreases with age. A receptor like that of a proteohormone is assumed to exist in the gonads but not in other tissues. In nongonadal tissues, H-Y antigen apparently is present only if the cell itself synthesizes the antigen. The H-Y antigen receptor of the gonads is not sex-specific. Thus, the primary sex differentiation depends on whether H-Y antigen is synthesized in the organism.

Animals↗
PubMed1978

Higher order structure of simian virus 40 chromatin.

Simian virus 40 nucleoprotein complexes undergo an ionic strength-dependent structural transition. At moderate ionic strength they contain histone H1 as well as the nucleosomal histones and have a compact conformation with globular subunits 190 angstroms in diameter. At high ionic strength histone H1 is released, and the structure unfolds into chains with an average of 24 nucleosomes. The extended viral chromatin converts to the compact form by the addition of histone H1. Transcriptionally active simian virus 40 chromatin undergoes the same structural transitions. The higher order structure of viral chromatin may be analogous to the compact state of cellular chromatin fibers observed at physiological ionic strength.

Chromatin↗
PubMed1978

The structure of SV 40 chromatin.

Simian virus 40 (SV40) nucleoprotein complexes were studied with the electron microscope. Depending on the isolation procedure, SV40 chromatin has two different conformations: complexes isolated in the presence of 0.15 M NaCl appeared as very compact globular structures, while those isolated in the presence of 0.6 M NaCl had the typical 'beads-on-a-string' appearance of the primary nucleofilament. Concomitant with this structural change was a variation in the histone pattern and sedimentation behaviour of the complexes: with NaCl at 0.15 mol 1(-1) the isolated complexes contained both the nucleosomal histones and histone H1, and sedimented in sucrose gradients at 70S. Increasing the ionic strength to 0.6 M NaCl resulted in the removal of histone H1 from the complexes and in a decrease of the sedimentation coefficient to 40S. DNA relaxing enzyme is associated with the SV40 nucleoprotein complexes. The numbers of superhelical turns in DNA from compact and open types of complexes were found to be the same. Therefore the transition from the condensed to the open structure of viral chromatin does not require a change in the topological winding number of its DNA.

Centrifugation, Density Gradient↗