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J Schaller

Publications and source records attributed to J Schaller.

At least 19 recordsLinked to original sources
PubMed1995

Partial amino acid sequence and functional aspects of histone H1 proteins in Trypanosoma brucei brucei.

Trypanosoma brucei brucei, a protozoan parasite of wild and domestic animals in Africa, is related to the pathogenic agent of human sleeping sickness. Four H1 histone proteins were isolated from nuclei of procyclic culture forms and cleaved with proteases. Amino acid sequence analysis of purified fragments indicated the presence of variants which displayed sequence identities as compared to the C-terminal domain of human H1. Substitutions of amino acids and posttranslational modifications of the histones in T b brucei H1 may influence protein conformation and histone-histone as well as histone-DNA interactions in the chromatin of the parasite. Digestion of soluble chromatin with immobilized trypsin at low and high ionic strengths indicated an internal localization of H1 in the condensed chromatin. The influence of histone H1 of T b brucei on the compaction pattern of the chromatin was investigated by dissociation and reconstitution experiments. Electron microscopy revealed that trypanosome H1 was able to induce condensation of the chromatin of the parasite and of rat liver into dense tangles. After dephosphorylation of H1, 30 nm fibers were induced in rat liver chromatin, while the resulting fibers were distinctly thinner in T b brucei. It can be concluded that the absence of 30 nm fibers in T b brucei chromatin cannot be explained by the divergent variants and posttranslational phosphorylations of H1 only but rather by the influence of both, the divergent core histones, previously described, and H1 properties.

Amino Acid Sequence↗
PubMed1994

Coagulation factor XII Locarno: the functional defect is caused by the amino acid substitution Arg 353-->Pro leading to loss of a kallikrein cleavage site.

The dysfunctional coagulation factor XII (FXII) Locarno was purified from 2 L of the proposita's plasma. Studies to identify the molecular defect responsible for the lack of amidolytic and proteolytic activity of this FXII variant were performed. Amino acid sequence analysis of peptides obtained from FXII Locarno on activation with either trypsin or plasma kallikrein and dextran sulfate showed an amino acid substitution of Arg 353 by Pro. Thereby, the kallikrein cleavage site at Arg 353-Val 354 is lost. Although trypsin-activated FXII Locarno was fully cleaved at Arg 334-Asn 335 and at Arg 343-Leu 344, neither amidolytic nor proteolytic activity was generated. We conclude that proteolytic cleavage at Arg 343 in the absence of cleavage at Arg 353 is not sufficient to expose the enzymatic active site in FXII Locarno.

Amino Acid Sequence↗
PubMed1994

Enhanced cytotoxicity of amyloid beta-peptide by a complement dependent mechanism.

Amyloid beta-peptide (A beta) has been shown to activate the classical complement pathway in vitro. Here, we demonstrate that this interaction is fully capable of killing cells and damaging cellular processes in mixed hippocampal cultures from embryonic day 18 rat fetuses. Lactic acid dehydrogenase (LDH) release and morphologic changes were used to evaluate toxicity.

Amyloid beta-Protein Precursor↗
PubMed1994

The human 4F2 antigen: evidence for cryptic and noncryptic epitopes and for a role of 4F2 in human T lymphocyte activation.

T lymphocyte activation can be triggered through multiple distinct, but functionally related, pathways. Murine monoclonal antibodies (mAbs) have been used to characterize the surface components of several of these pathways, as well as structures whose function is not yet known. One such cell surface structure is the heterodimeric 4F2 antigen, which is expressed on activated and proliferating cells. Two new mAbs that recognize the heavy chain of the 4F2 antigen have been produced in our laboratory. One antibody, UM7F8, is comitogenic with soluble anti-CD2 and immobilized (but not soluble) anti-CD3 mAbs. The second antibody, termed UM2G12, appears to recognize a cryptic epitope on the 4F2 heavy chain and is not comitogenic for T cells. In view of the functional effects seen with UM7F8, and the highly regulated expression of the 4F2 antigen, it seems likely that 4F2 has a specific role in T cell development and activation.

Antibodies, Monoclonal↗
PubMed1994

[Value of the patient's own test substances in epicutaneous testing].

Patch testing with commercially available test kits of known allergens often leads to detection of the responsible allergen. In many cases, however, the responsible allergen cannot be found unless the patient's "own" products or chemicals are tested. An analysis of 2460 patch tests with patch test kits proposed by the DKG (German Contact Allergy Group) and a positive history of a patient's own substance showed positive results in 208 patients with 289 products. In 44% (129 out of 289) the responsible allergen could only be found by testing the patient's own substances, in 56% (160 out of 289) the same allergen as was responsible for the positive result with patients' endogenous substances was positive in one of the commercially available test kits. The substances that tested positive were medical products/adhesives (45%), cosmetics (39.4%), rubber materials (4.1%), leather materials (0.7%) and others (10%). Subsequent testing of the different components of the patients' own substances that tested positive was carried out in 45 cases and resulted in the detection of new allergens, such as tris-(2-hydroxyethyl)isocyanurate triacrylate. In 27 patients the endogenous substances had tested positive in the course of testing for occupational dermatitis, and in 10 of these positive testing of a patient's own product resulted in notification of an occupational dermatitis. These results show, that patch testing with the patients own products if very important for the finding of the responsible or even new allergens.

Adult↗
PubMed1994

[Detection of an unusual varicella zoster virus infection in an immunosuppressed patient with polymerase chain reaction].

We report a case of a 76-year-old patient who developed an atypical form of varicella zoster virus (VZV) reinfection. In addition to histological and serological confirmation of diagnosis, direct demonstration of VZV-DNA was possible by means of the nested polymerase chain reaction. Although VZV infection is usually diagnosed by clinical examination, the nested PCR is a sensitive and specific diagnostic procedure that can be useful especially in atypical cases.

Acyclovir↗
PubMed1994

Purification of toxic peptides and the amino acid sequence of CSTX-1 from the multicomponent venom of Cupiennius salei (Araneae:Ctenidae).

The venom of the wandering spider Cupiennius salei was analysed biochemically by gel filtration, cation exchange chromatography, RP-HPLC, IEF, SDS-PAGE and TLC-electrophoresis. The native venom contains high levels of Na+, K+, Ca2+, histamine and taurine. It shows considerable activity of hyaluronidase, but not proteolytic activity. Thirteen peptides (CSTX-1 to CSTX-13) with an apparent mol. wt between 2.6 and 12.5 kDa causing differently strong toxic, effects were purified. Toxicity data of the crude venom (insects and mouse) are given and compared with the toxicity of CSTX-1, which causes most of the crude venom's toxicity. CSTX-1 has a mol. wt of 8352.6 and its amino acid sequence of 74 amino acids is given.

Amino Acid Sequence↗
PubMed1994

Identity of human extra parotid glycoprotein (EP-GP) with secretory actin binding protein (SABP) and its biological properties.

In this paper the identity of the salivary protein EP-GP (extra-parotid glycoprotein) is reported, also apparent in other human secretions. Immunochemical and biochemical analysis demonstrated that EP-GP is similar to the secretory actin-binding protein (SABP), also known as gross cystic disease fluid protein-15 (GCDFP-15) and prolactin-inducible protein (PIP). The molecular mass and charge microheterogeneity of EP-GP, also observed for SABP, was shown to be predominantly caused by the carbohydrate moiety. In addition, evidence was given that EP-GP is not related to the lipocalin Von Ebner's gland protein (human; VEGh). The biological significance of EP-GP and its homologues is not clear. EP-GP bound to actin and fibrinogen as described for SABP and GCDFP-15. However, the affinity for these proteins does not appear to have any direct physiological role in the mucosal secretions. On the other hand, EP-GP binds to several bacteria. By electron microscopy the ultrastructural localization is demonstrated of EP-GP to the cell wall of both Streptococcus salivarius HB and its cell appendage-lacking mutant Streptococcus salivarius HB-C12. Concerning this finding we hypothesize on the possible functional aspects of this enigmatic protein EP-GP.

Amino Acid Sequence↗
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

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↗
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↗