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J Schaller

Publications and source records attributed to J Schaller.

At least 73 records · Page 4Linked to original sources
PubMed1994

Influence of the epididymis on integrins and matrix proteins of human spermatozoa.

Spermatozoa alter their antigenity and develop the ability of binding to zona pellucida and to vitellus during the epididymal transit. The involvement of spermatozoal adhesion molecules (AM), especially beta 1-integrins in this binding process between the gametes is very likely. Therefore, the influence of epididymis on the binding capacity of AM was indirectly investigated by comparison of AM on ejaculated and on testicular human spermatozoa and spermatogenic cells, respectively. The AM-expression was detected on ejaculated spermatozoa by flow cytometry (EPICS PROFILE II, Coulter Corp., Krefeld, Germany) and on spermatogenic cells by immunohistology using monoclonal antibodies against. beta 1-integrins and matrix proteins. The alpha-chains 3, 5, 6 of the beta 1-integrins and fibronectin were found on ejaculated spermatozoa as well as on spermatogenic cells except spermatogonia. The alpha-4-chain and laminin could only be detected after the epididymal transit of spermatozoa, whereas, the beta-chain of beta 1-integrins was missing on the ejaculated spermatozoa. These findings suggest that AM are predominantly expressed on spermatogenic cells before the epididymal transit but an epididymis-mediated modulation of AM, i.e. masking, demasking or activating of cryptodeterminants is possible. On this way dysfunction of epididymis could be followed by an impairment of AM-mediated binding capacity of spermatozoa.

Antigens, CD↗
PubMed1993

Biochemical and functional characterization of histone H1-like proteins in procyclic Trypanosoma brucei brucei.

Four variants and/or posttranslational modifications of histone H1-like proteins of Trypanosoma brucei brucei procyclic culture forms were extracted with 0.25 N HCl from isolated nuclei and analyzed by two-dimensional gel electrophoresis. The amino acid composition of these proteins, their ability to space nucleosomes regularly and to induce salt-dependent condensation of the chromatin indicated their histone H1 nature. On the other hand, the histone H1-like proteins clearly differed from their higher-eukaryote counterparts by their weak interaction with DNA under low-salt conditions. As a consequence, intact nucleosome filaments were prepared according to a new preparation protocol especially adapted to the unstable chromatin of T. b. brucei. Our results indicate that the biochemical properties of the histone H1-like proteins contribute to the structural and functional differences between the chromatin of procyclic T. b. brucei and that of higher eukaryotes.

Amino Acids↗
PubMed1993

Semliki Forest virus core protein fragmentation: its possible role in nucleocapsid disassembly.

Semliki Forest virus (SFV) envelope proteins function as proton pores under mildly acidic conditions and translocate protons across the viral membrane [Schlegel, A., Omar, A., Jentsch, P., Morell, A. and Kemp, F. C. (1991) Biosci. Rep. 11, 243-255]. As a consequence, during uptake of SFV by cells via receptor-mediated endocytosis the nucleocapsid is supposed to be exposed to protons. In this paper the effects of mildly acidic pH on SFV nucleocapsids were examined. A partial proteolytic fragmentation of core proteins was observed when nucleocapsids were exposed to mildly acidic pH. A similar proteolytic event was detected when intact SFV virions were exposed to identical conditions. Protease protection assays with exogenous bromelain provided evidence that the capsid protein degradation was due to an endogenous proteolytic activity and not to a proteolytic contamination. Detergent solubilization of virus particles containing degraded nucleocapsids followed by sucrose gradient centrifugation led to a separation of capsid protein fragments and remaining nucleocapsids. These data are discussed in terms of a putative biological significance, namely that the core protein fragmentation may play a role in nucleocapsid disassembly.

Aedes↗
PubMed1993

Granulocyte activation in bullous diseases: release of granular proteins in bullous pemphigoid and pemphigus vulgaris.

BACKGROUND: Eosinophil and polymorphonuclear granulocytes may be involved in the formation of blisters in bullous dermatoses, particularly bullous pemphigoid. OBJECTIVE: Our purpose was to evaluate the role of granulocyte activation in the pathogenesis of pemphigus vulgaris and bullous pemphigoid. METHODS: Levels of eosinophil cationic protein (ECP) and neutrophil-derived myeloperoxidase (MPO) in blister fluid and serum and levels of serum IgE were determined in patients with bullous pemphigoid (n = 12), those with pemphigus vulgaris (n = 9) and healthy volunteers (n = 12). RESULTS: In blister fluid and serum of patients with bullous pemphigoid, significantly elevated concentrations of ECP, MPO and IgE were detected as compared with controls. In contrast, ECP, MPO, and IgE levels in blister fluid and serum of patients with pemphigus vulgaris did not significantly differ from controls. Moreover, the MPO/ECP ratio in serum of patients with bullous pemphigoid was significantly decreased as compared with controls, whereas the MPO/ECP ratio in pemphigus vulgaris did not differ from controls, indicating a preferential activation of eosinophils in bullous pemphigoid only. In patients with bullous pemphigoid, serum levels of ECP and MPO significantly decreased during immunosuppressive therapy to levels similar to those of controls. CONCLUSION: Activated granulocytes, releasing their granular contents such as ECP and MPO, may be of importance for blister formation in bullous pemphigoid and may be useful for monitoring disease activity.

Aged↗
PubMed1993

Evidence of beta 1 integrins and fibronectin on spermatogenic cells in human testis.

Interactions between human spermatozoa and oocytes are an essential event in the process of fertilization. Cell-cell and cell-matrix interactions in somatic cells are mediated by adhesion molecules such as beta 1 integrins (very late antigens; VLA). Therefore, we investigated the expression of beta 1 integrins and the matrix proteins collagen IV, fibronectin and laminin in human testis by immunohistology. Monoclonal antibodies against the beta chain of beta 1 integrins reacted with the basement membrane of the tubuli seminiferi, spermatocytes, spermatids and testicular spermatozoa. The alpha 3, -5 and -6 chains of beta 1 integrins showed the same pattern, whereas, the alpha 1, -2 and -4 chains could not be detected on spermatogenic cells. These VLA subunits were localized on endothelial cells, leukocytes and basement membranes. Matrix proteins such as laminin, collagen IV and fibronectin were detectable as components of basement membranes in human testis. Germinal cells except spermatogonia expressed fibronectin only. These results demonstrate that beta 1 integrins and matrix proteins in human testis are normally expressed on somatic tissue and that germinal cells, especially spermatocytes, spermatids and spermatozoa show positive reactions with antibodies against the VLA-3, -5 and -6 complexes and fibronectin. These findings suggest a production of beta 1 integrins and fibronectin during the spermatogenesis and a role of these proteins in adhesive mechanisms of spermatozoa similar to somatic cell-cell or cell-matrix interactions.

Adult↗
PubMed1993

Beta 1-integrins of spermatozoa: a flow cytophotometric analysis.

The expression of adhesion molecules on human ejaculated spermatozoa was investigated by means of flow cytophotometry using monoclonal antibodies against eight different adhesion molecules. Spermatozoa from infertility patients who exhibited normal semen parameters showed specific fluorescence after incubation with antibodies against very late antigens VLA alpha 4, VLA alpha 5, VLA alpha 6, and corresponding matrix proteins laminin and fibronectin. Semen samples from men with teratozoospermia or oligoasthenoteratozoospermia were characterized by reduced expression of adhesion molecules. Normal and pathological semen samples differed mostly in the expression of VLA alpha 5. After artificial induction of the acrosome reaction by a cold shock method and incubation with 2 mM Ca2+, a changed pattern of adhesion molecules on the sperm surface was found for VLA alpha 6 as the most prominent molecule. After treatment of spermatozoa with 0.1% Triton X-100, the number of cells with adhesion molecules increased significantly. This result suggests that adhesion molecules are an integral part of sperm structure.

Acrosome↗
PubMed1993

Semen samples with teratozoospermia show a lower percentage of spermatozoa with detectable adhesion molecules (AM).

Adhesion molecules (AM) are cell surface proteins which interact with ligands and mediate cell-cell bindings. Possibly, the AM are involved in the spermatozoal adhesion to oocytes. Human spermatozoa showed several adhesion molecules on their surface: the alpha chains of the beta 1-integrins VLA alpha 4 (CDw 49d), VLA alpha 5 (CDw 49e) and VLA alpha 6 (CDw 49f), the beta-chain of beta 2-integrins (CD 18) and the matrix proteins laminin and fibronectin. Semen samples with severe teratozoospermia were characterized by a significantly lower percentage (P < 0.01) of spermatozoa with VLA alpha 4, VLA alpha 5 and laminin. VLA alpha 5 (the alpha-chain of the fibronectin receptor) showed the most significant difference between the "normal" and teratozoospermic semen sample groups. This phenomenon could contribute to the explanation of a lower fertilizing capacity of teratozoospermic semen samples.

Cell Adhesion Molecules↗
PubMed1992

Amino acid sequence of human plasma galactoglycoprotein: identity with the extracellular region of CD43 (sialophorin).

The amino acid sequence of galactoglycoprotein purified from human plasma was elucidated to 75% completeness by using chemical degradation of peptides and glycopeptides derived from digests of the protein with seven specific proteases. This sequence represents a polypeptide chain of approximately 220 amino acid residues including a high content of serine, threonine, alanine, and proline with one N-linked and multiple O-linked glycans. Comparison of peptide sequences from the native galactoglycoprotein and the deglycosylated derivative demonstrated the locations of 25 sites of O-glycosylation and three serine sites that are not glycosylated. The homogeneous N terminus was established as serine. C-terminal analysis revealed multiple C-terminal residues, suggesting that galactoglycoprotein molecules are of varying lengths. A search of a protein data base revealed that the galactoglycoprotein polypeptide is identical to the N-terminal (extracellular) polypeptide region of the blood-cell surface molecule CD43 (sialophorin, leukosialin). Further support of the relatedness of these molecules was obtained by immunoprecipitation of 125I-labeled galactoglycoprotein by monoclonal anti-CD43 antibodies. The composition and properties of the molecules together with the known structure of the gene encoding CD43 suggest that galactoprotein is derived by proteolytic cleavage from transmembrane "hexasaccharide CD43," known to be expressed on neutrophils, activated T lymphocytes, and platelets.

Amino Acid Sequence↗
PubMed1992

Sequence differences between histones of procyclic Trypanosoma brucei brucei and higher eukaryotes.

Four histones, a, b, c, d from procyclic Trypanosoma brucei brucei, which show similarities with the amino acid composition of the core histones H3, H2A, H2B and H4, were isolated and cleaved with Endoproteinase Glu-C. The fragments were separated by FPLC reversed phase chromatography and a subset of the fragments (a5, a9, b6, c8, d3, d9, d11) was subjected to sequence analysis. A 54-71% identity was found in the sequences of the fragment c8 and the C-terminal half of H2B and of three fragments of protein d covering the N-terminal half as well as the C-terminal region of H4. The amino acid sequence of the fragment a9 showed a 57 and 54% identity with H3 sequences of Saccharomyces cerevisiae and Xenopus laevis. Neither the a5 nor the b6 sequence could be aligned with histone sequences of other eukaryotes. The significant differences of 21-48% between the T.b. brucei histone sequences and those of calf thymus histones, which are more pronounced than the differences of Tetrahymena pyriformis and the higher eukaryote, resulted partially from replacements of amino acids with different properties and indicate specific patterns of histone-histone and/or histone-DNA contact sites in the nucleosome of T.b. brucei. These differences, together with the lack of a functional histone H1, may be sufficient to explain the lack of a salt-dependent formation of the nucleosome filament into the 30 nm fibre, which reflects alternative methods of organizing and processing the genetic information in the nucleus of the protozoan parasite and which may be of chemotherapeutic significance.

Amino Acid Sequence↗
PubMed1992

Complete amino acid sequence of ovine miniplasminogen.

The complete amino acid sequence of ovine miniplasminogen (M(r) 37,662, 343 residues) was determined with the aid of fragments obtained by cleavage with 2-(2-nitrophenylsulfenyl)-3-methyl-3'-bromoindolenine and clostripain. The fragments were aligned with overlapping sequences and sequence comparison with miniplasminogens of other species. Sequence comparison with other species (human, bovine, porcine, equine and canine) gave an overall identity of 63% and a similarity of 83%. The dendrogram of the alignment indicates that ovine miniplasminogen has the closest relationship with the bovine (87% identity) and the most distant with the equine (77% identity) species. The close relationship is indicative for the presence of the same structural and functional domains as in the other species. Sequence comparison of different miniplasminogens showed that positions 49 (Arg), 83 (Arg) and 161 (Ser) in the light chain of the plasmin molecule may play a role in the interaction between plasminogen and streptokinase.

Amino Acid Sequence↗
PubMed1992

[Onset of disseminated Bloch-Sulzberger incontinentia pigmenti].

The case report of a 2-week-old girl suffering from incontinentia pigmenti (Bloch-Sulzberger Syndrome) with disseminated urticarial erythemas, papules and vesicles at the onset is presented. Histological examination showed eosinophilic spongiosis. The peripheral blood eosinophilia and the development of typical lesions led to the diagnosis of incontinentia pigmenti. Eosinophilic spongiosis and peripheral blood eosinophilia are important symptoms in the diagnosis of atypical incontinentia pigmenti.

Biopsy↗
PubMed1991

Identification of the disulphide bonds in human platelet glycocalicin.

The glycoprotein Ib/IX complex on platelets is responsible for the first stage of haemostasis as an essential component in the primary adhesion of platelets to damaged vessel walls. Glycocalicin is the extracellular part of platelet glycoprotein Ib alpha and contains the von Willebrand factor and thrombin binding sites. Disulphide bonds are implicated in the von Willebrand binding site and studies with peptides point towards a region of glycocalicin with four cysteines as containing the binding sites for both von Willebrand factor and thrombin. The position and linkage of these two disulphide bonds are now determined to be 209-248 and 211-264 and the relevance of this double-loop structure for glycoprotein Ib/IX function is discussed.

Amino Acid Sequence↗
PubMed1991

Primary structure of a new actin-binding protein from human seminal plasma.

Secretory actin-binding protein (SABP), a glycoprotein from human seminal plasma, was isolated according to Akiyama and Kimura [Akiyama, K. & Kimura, H. (1990) Biochim. Biophys. Acta 1040, 206-210]. The complete amino acid sequence of SABP was determined with the aid of fragments generated by trypsin, Staphylococcus aureus V8 protease and pepsin. The single polypeptide chain of SABP contains 118 amino acids with a calculated Mr of 13,506 and pyroglutamic acid as the N-terminal residue. A single N-glycosidic carbohydrate moiety is located at Asn77. The carbohydrate composition shows an unusually high amount of fucose. The arrangement of the two disulfide bonds is Cys37-Cys63 and Cys61-Cys95. Sequence comparison revealed a high degree of similarity with a 14-kDa submandibular gland protein from mouse (45% identity and 64% similarity). SABP is identical with a prolactin-inducible protein and a protein termed gross cystic disease fluid protein 15 (sequences translated from cDNA clones), both from human breast tissues. Although SABP was also detected in saliva, in extracts of the submandibular gland and seminal vesicles, little is known of its function.

Actins↗
PubMed1991

Identification of the disulfide bonds of human complement C1s.

C1s, one of the three subcomponents of C1, the first component of the complement system, is a complex serine protease. To determine the disulfide-bonding pattern, fragments of C1s were generated by cleavage with pepsin, thermolysin, or subtilisin. Disulfide bonds have been identified by several methods, for example, direct observation of the phenylthiohydantoin derivative of cystine during Edman degradation of isolated peptides and placement in the known cDNA sequence. All of the 26 half-cystines are linked in disulfide bonds occurring at positions 50-68, 120-132, 128-141, 143-156, 160-187, 219-236, 279-326, 306-339, 344-388, 371-406, 410-534, 580-603, and 613-644. All of the disulfide bonds of the earlier described substructures of C1s, the EGF-homologous part, the two SCR units, and the two domains typical for C1s and C1r are localized within these domains.

Amino Acid Sequence↗
PubMed1991

Biochemical properties of histone-like proteins of procyclic Trypanosoma brucei brucei.

Four histone-like proteins a, b, c, d were extracted with 0.2 M H2SO4 from soluble nuclear chromatin of Trypanosoma brucei brucei procyclic culture forms and purified by FPLC reversed phase chromatography. The amino acid composition of these proteins and their electrophoretic mobilities in three different gel systems strongly indicated their core histone nature. Similarities were found between a, b, c and d with the core histones H3, H2A, H2B and H4 of higher eukaryotes, respectively. On the other hand, these proteins also showed differences as compared to higher eukaryotes; proteins a and d clearly differed from their counterparts H3 and H4 on the basis of their hydrophobic properties. The results indicate the occurrence of core histone variants in T.b. brucei which may influence DNA-histone and histone-histone interactions as well as the chromatin compaction in the nucleus of this protozoan parasite.

Amino Acids↗