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Biomedical subjects

J Stadler

Publications and source records attributed to J Stadler.

At least 127 records · Page 7Linked to original sources
PubMed1982

Organization of highly repetitive satellite DNA of two Cucurbitaceae species (Cucumis melo and Cucumis sativus).

The prominent satellites of the Cucurbitaceae Cucumis melo (melon) and Cucumis sativus (cucumber) have been characterized, in actinomycin/CsCl gradients where the satellite sequences can be separated from ribosomal, organelle, and main band DNA the location of the satellites is different indicating a different GC content. The purified satellite of C. melo is cut by HindIII into a repeat unit of 380 bp; AluI digestion gives rise to two bands (about 80 and 220 bp in size). The HindIII repeat unit if cloned into pBR325 exhibits new recognition sites for HpaII leaving two bands with 150 and 80 bp suggesting methylation of the C/CGG cutting site in the uncloned material. The restriction pattern indicates an internal sequence repeat within the 380 bp HindIII fragment. The C. sativus satellite is cut by AluI to a repeat unit of 180 bp showing no other recognition site for the restriction enzymes tested so far. About 10% sequence homology has been determined between the C. melo and C. sativus satellites by cross hybridization studies. A high methylation degree of cytosines has been measured for both satellites and the ribosomal DNA of C. sativus (about 30%). No transcription products of the C. melo satellite were found during seedling development.

Base Composition↗
PubMed1982

Monoclonal antibodies against contact sites A of Dictyostelium discoideum: detection of modifications of the glycoprotein in tunicamycin-treated cells.

Tunicamycin acts on cell aggregation in Dictyostelium discoideum by changing cell movement and by inhibiting the EDTA-stable type of intercellular adhesion. Tunicamycin-treated cells show unco-ordinated pseudopodial activity such that pseudopods are simultaneously extended from all parts of the cell surface, and the cells are unable to move in straight paths. Concurrent with the inhibition of formation of EDTA-stable contacts, N-glycosylation of a glycoprotein specific for aggregation-competent cells is inhibited. This glycoprotein, previously called contact site A, has an apparent mol. wt. of 80 kilodaltons (kd). In membranes of tunicamycin-treated cells, two components are detected that react with certain monoclonal antibodies against contact sites A: one component of 66 kd, the other of 53 kd apparent mol. wt. Another group of monoclonal antibodies reacts only with the 80-kd glycoprotein and the 66-kd component. These results are in accord with the assumption that the glycoprotein carries two carbohydrate chains, and that the antibodies differ in their requirement for glycosylation of the antigen. Despite the coincidence between blockage of EDTA-stable cell adhesion and inhibited glycosylation of contact sites A, direct involvement of the carbohydrate moieties of this glycoprotein in intercellular adhesion seems questionable. EDTA-stable cell adhesion has not been blocked by Fab fragments from antibodies that specifically react with the glycosylated protein.

Journal Article↗
PubMed1982

Improved purification and N-terminal amino acid sequence determination of the contact site A glycoprotein of Dictyostelium discoideum.

On aggregating cells of Dictyostelium discoideum a specific glycoprotein is expressed which is absent from growth phase cells of this organism. The glycoprotein has been related to cell surface antigens, called contact sites A, that are defined by their reaction with aggregation blocking antibody fragments. In the present paper an improved purification scheme for the glycoprotein is described and its N-terminal sequence is given. The purification has been monitored by use of a monoclonal antibody. The contact site A glycoprotein has the properties of an integral membrane protein.

Amino Acid Sequence↗
PubMed1982

Tight attachment of fatty acids to proteins associated with milk lipid globule membrane.

The proteinaceous coat associated with the cytoplasmic side of milk lipid globule membranes (MLGM) was prepared from bovine and caprine milk by removal of membrane material with non-ionic detergent. These coat preparations, which were enriched in two major proteins, a glycoprotein of polypeptide M, 67 000 (butyrophilin) and a non-glycosylated protein of polypeptide Mr 155 000 (xanthine oxidase), contained small amounts of fatty acids which could not be removed by exhaustive extractions with organic solvents. Both butyrophilin and xanthine oxidase of bovine MLGM were excised and eluted from SDS-polyacrylamide gels and were shown to contain 1 to 2 moles of bound fatty acids per mole of protein. Palmitic, stearic and oleic acids were the predominant protein-bound fatty acids, but no specificity for binding of individual fatty acids was observed. The fatty acids were not rendered soluble in organic solvents when the protein preparations were incubated with phospholipases A or C or with trypsin. Treatment with 0.25 M NaOH at 100 degrees C for 1 h or with 1 M hydroxylamine at 4 degrees C for 16 h, however, released virtually all of the fatty acids associated with these proteins. Similar results were obtained with two major proteins, bands 3 and 4.1, or rat erythrocyte plasma membrane. By contrast, skeletal muscle actin and serum albumin had no bound fatty acids that could be released by alkali treatment. These results show that fatty acids are bound to a number of membrane-associated proteins, both glycosylated and unglycosylated, via linkages that resist purification of the proteins on SDS-polyacrylamide gel electrophoresis and are suggestive of covalent attachment of fatty acids to these proteins. The possible involvement of this acylation in processes characterized by local changes of membrane shape and plasticity is discussed.

Animals↗
PubMed1981

Absence of sugars in electrophoretically purified cytochrome b5 demonstrated by combined gas chromatography-mass spectrometry.

The problem of determining small but significant amounts of carbohydrates, in purified proteins, has been studied using the membrane protein, cytochrome b5. A newly developed method that involves direct gas chromatography-mass spectrometry of sugars obtained by hydrolysis of proteins purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) allows the identification and determination of small amounts of carbohydrates (e.g., 20 micrograms of glycoprotein containing a minimum of 0.1% monosaccharide), even in the presence of relatively high amounts of impurities. Application of this method to cytochrome b5 fragments obtained by tryptic digestion from rat liver microsomes and purified by combined gel filtration and ion exchange chromatography, followed by SDS PAGE, has consistently yielded values below 0.07 mol of the individual sugars and aminosugars per mole cytochrome b5. It is concluded that cytochrome b5, at least its trypsin-released major amino-terminal fragment, is not constitutively glycosylated.

Animals↗
PubMed1981

Antibodies to high molecular weight polypeptides of desmosomes: specific localization of a class of junctional proteins in cells and tissue.

Desmosome-enriched fractions were isolated from bovine muzzle epidermis either as desmosome-tonofilament complexes using a procedure involving treatment at pH9 or in the form of desmosomal residue fractions using a modification of the citric acid buffer (pH 2.3) method of Skerrow and Matoltsy [1]. Major polypeptides of high molecular weights (mol. wt.) were separated by gel electrophoresis, individual polypeptide bands were excised, and protein was eluted and used for immunization. Guinea pig antibodies raised against two prominent polypeptides of high mol. wt. (250,000 and 215,000) showed, on nitrocellulose paper blots of desmosome-tonofilament polypeptides separated by gel electrophoresis, extensive cross-reaction between a group or large polypeptides characteristic of desmosome-containing fractions, most notably polypeptides of 250 K, 215 K, 200 k, 175 K, and 164 K. These antibodies allowed, when used in immunofluorescence microscopy, the specific localization of desmosomal junctions (i) in sections through epithelia-containing tissue (e.g., epidermis, mucosae of tongue and esophagus, cornea, mammary gland, small intestine, liver, thymus, urothelium of bladder) and myocardium; (ii) on dissociated cells from these tissues; (iii) on various epithelial cells grown in culture; an (iv) in tumor-like proliferations of cultured epithelial cells injected into nude mice. Individual desmosomes could be visualized and resolved at the light microscopic level. No reaction was found in cells devoid of desmosomes and on other classes of intercellular junctions. Electron microscopic localization using immunoperoxidase techniques indicated that these proteins are located in, or close to, the desmosomal plague structure. It is proposed to use such antibodies against desmosomal proteins as markers specific to this so far only morphologically define class of junctions. Use of these markers will (i) improve identification and classification of intercellular junctions; (ii) facilitate determinations of the specific patterns of distributions of desmosomes and desmosomal protein in various cells and tissue; (iii) allow studies of formation and disintegration of desmosomes, and of the biosynthesis and possible recycling of their constituents; and (iv) provide tissue group-specific markers valuable in histology and diagnosis, especially for identification of epithelial and carcinoma cells.

Animals↗
PubMed1981

Zinc deficiency during intravenous hyperalimentation.

Two cases of patients developing symptoms and signs of zinc deficiency while on total parenteral nutrition are presented. Supporting causes for the appearance of early low serum zinc levels are discussed. These cases serve to further stress the need of adding trace elements to solutions given to patients on long-term total parenteral nutrition.

Adult↗
PubMed1980

Cell fusion-impaired variants of a mouse lymphocytic cell line obtained by single-step selection for polyethylene glycol resistance.

This report describes an effective method for single-step isolation of cell line variants with reduced intercellular plasma membrane fusion ability. Variants, derived from a subline of L5178Y, were obtained by selection for growth in the presence of a toxic level of PEG 6000. These variants occurred after EMS treatment and spontaneously. Further testing revealed a pleiotropic phenotype, fusion impairment and polyethylene glycol resistance, which has been designated PgfR. Variant sublines, in serial subculture for more than 165 days on nonselective medium, retain a stable PgfR phenotype. PgfR variants have an approximate 7-fold reduction in intercellular fusion competence.

Animals↗
PubMed1980

Spontaneous bacterial clearance in experimental urinary tract infections in mice: cellular aspects of the process.

The morphological aspects of Proteus mirabilis clearance from the urinary tract of experimentally infected mice were investigated. For this purpose, two groups of mice were compared: a group infected with the bacterium and a group that had just recovered from the infection. Differences between the two groups were found in extent of bladder and kidney inflammation, depth of infiltration into the bladder wall, and in the increment of bladder volume. There was no clear-cut difference between the two groups in number of lymphocytes and monocytes, but the number of granulocytes was significantly lower in the bladder and kidneys of the recently healed animals. Likewise, the plasma cells were fewer in healed animals than in infected ones, the difference being statistically significant for bladders and on the verge of significance for kidneys.

Animals↗
PubMed1980

Thymidine kinase: an inexpensive index of liver regeneration in a large animal model.

Most studies of liver regeneration have been restricted to small animals because of the cost of assessment of DNA synthesis by the standard method of thymidine incorporation in vivo. This paper presents the use of thymidine kinase as an inexpensive measure of regeneration in large animals. The use of the large model is advantageous because of the availability of serial blood and tissue samples from the same animal. Initially, the responses in thymidine kinase and thymidine incorporation over a period of 96 hr were shown to correspond well in rats subjected to 68% and 34% hepatectomy. Any delays could be attributed to different times of operation. A reproducible technique for 50% partial hepatectomy in the pig was developed, and the animals were studied by daily open liver biopsy for 7 days. The responses in thymidine kinase activity and mitotic indices showed tha peak regeneration occurred at 3-4 days. Levels of aspartate amino transferase were elevated sevenfold after partial hepatectomy but returned to normal within 96 hr. The levels of alkaline phosphatase and bilirubin were unaltered, confirming that the biliary drainage had not been compromised. This study offers the pig as another suitable model for the study of liver regeneration and thymidine kinase activity as a suitable index.

Animals↗
PubMed1979

[Clinical considerations on posttraumatic osteitis].

Posttraumatic bone infection very often signifies a life threatening complication. However, it must no longer be accepted that amputation of the afflicted limb be the logical treatment of such a complication. A surgeon who offers the advantages of operative treatment of a fracture to his patient must also be able to control its complications. Osteitis can be treated with a good chance of success. In our clinic 29 bone infections were treated, 13 of them healing without substantial restrictions, 7 with distinct discomfort and 4 with arthrodesis, i.e. 83% healed. However, the treatment may require months and may necessitate further operative interventions. The transfer of such a patient from an acute care hospital to a high altitude clinic offers -- besides the medical and psychological advantage of a continuous long-term treatment plan -- the climatic conditions of sun and high altitude air which apparently act very favorably on the healing process of chronic infections. Of course, the possibility of competent surgical interventions must exist. Thus, with proper therapy the disastrous chain of errors beginning mainly with poor initial care through insufficient treatment can be broken.

Adolescent↗