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H Diringer

Publications and source records attributed to H Diringer.

At least 19 recordsLinked to original sources
PubMed1992

Hidden amyloidoses.

The pathogenesis as well as the genetic disposition to develop clinical symptoms in transmissible spongiform encephalopathies (e.g. Creutzfeldt-Jakob disease, scrapie, bovine spongiform encephalopathy) relate these diseases to classical noninfectious amyloidoses (familial amyloidotic polyneuropathy as an example) and to Alzheimer's disease. This is not obvious to the nonexpert at first glance. This communication tries to elucidate this association, to reveal which immunochemical techniques have contributed their share.

Alzheimer Disease↗
PubMed1991

Neuronal autophagy in experimental scrapie.

In this study we report the formation of giant autophagic vacuoles (AV) in neurons in experimental scrapie in hamsters. Autophagy is an important step in the cellular turnover of proteins and organelles. It is known to occur in neurons under physiological as under pathological conditions. Giant AV, however, are seen very rarely only in pathological states. In our model AV are much more numerous after intracerebral (i.c.) transmission of the scrapie agent than after the transmission via the intraperitoneal route which points to a correlation between the intensity of the process and the period of incubation. As the appearance of the AV in our model is correlated chronologically with that of scrapie-associated fibrils, at least after i.c. transmission, the process may be related to a disturbance of cellular protein metabolism and, thus, to the processing of prion protein.

Animals↗
PubMed1991

Virus-induced amyloidosis in scrapie involves a change in covalent linkages in the preamyloid.

Preparations of the preamyloid and the amyloid protein from normal and scrapie hamster brains show different solubilization behaviours towards Triton X-114 extraction. The normal isoform is completely extractable from microsomal membranes by the detergent, whereas the pathological one is not. Both forms can be isolated using preparative SDS electrophoresis as the final step in order to remove all non-covalently associated materials. After removal of the SDS these purified proteins retain their solubility differences against Triton X-114. This demonstrates that at least one distinct modification of the preamyloid protein--which has to be covalent in nature--must have occurred to account for the strong aggregation tendency of the pathological isoform.

Amyloid↗
PubMed1991

Chemoprophylaxis of scrapie in mice.

Three applications of the polyanion pentosanpolysulphate about 2 months before infection of mice with scrapie completely protected animals infected with up to 100 LD50, and considerably prolonged the lifespan of those infected with 100 to 10,000 LD50. The clinical diagnosis was confirmed by immunoblot analysis for the protein of scrapie-associated fibrils.

Animals↗
PubMed1991

Virus-induced amyloidoses.

After a short introduction into the general concept of amyloidoses and the genetic disposition involved in these diseases, the genetic disposition for unconventional virus diseases (or transmissible spongiform encephalopathies) and the disease specific amyloid are described. Experimental studies on the pathogenesis and the infectious agent suggest that scrapie and related diseases are virus-induced amyloidoses of the brain.

Alzheimer Disease↗
PubMed1990

A quantitative assay for tyrosine sulfation and tyrosine phosphorylation in peptides.

A method was developed to measure sulfation and phosphorylation of tyrosine in proteins after alkaline hydrolysis, ion-exchange chromatography, reaction with [3H]dinitrofluorobenzene and subsequent thin-layer chromatography. The method allows the detection of 10-20 pmol of modified tyrosine and was applied to determine the content of tyrosine-phosphate and -sulfate in fibrinogens, thyroglobulin, alpha-casein, cytochrome c and glyceraldehyde dehydrogenase.

Chemical Phenomena↗
PubMed1989

Inhibition of human immunodeficiency virus type 1 RNase H by sulfated polyanions.

The reverse transcriptase (RT) activity of human immunodeficiency virus type 1 and other retroviruses is closely associated with a hybrid-degrading RNase H activity which is essential for retroviral replication. We have analyzed the effect of sulfated polysaccharides on human immunodeficiency virus type 1 recombinant RT and RNase H activities in vitro. Heparin, dextran sulfates, and xylan polysulfate were found to be much more potent inhibitors of RNase H than of RT and exhibit 50% infective doses of 0.04 to 0.1 micrograms/ml (corresponding to 0.1 to 25 nM) which is up to 5,000-fold more efficient than that for RT. Inhibitors of RNase H activity are attractive as antiviral drugs.

Anions↗
PubMed1987

Mouse polyclonal and monoclonal antibody to scrapie-associated fibril proteins.

Antibody response in mice to scrapie-associated fibril proteins (protease-resistant proteins [PrPs]) was generated to different epitopes depending on the source of antigen. Mice responded differently to PrPs isolated from scrapie-infected animals of homologous (mouse) versus heterologous (hamster) species. An enzyme-linked immunosorbent assay established to monitor this antibody response in mice immunized with PrPs was unable to detect such a response in scrapie-infected mice. A monoclonal antibody (MAb), 263K 3F4, derived from a mouse immunized with hamster 263K PrPs reacted with hamster but not mouse PrPs. MAb 263K 3F4 also recognized normal host protein of 33 to 35 kilodaltons in brain tissue from hamsters and humans but not from bovine, mouse, rat, sheep, or rabbit brains. This is the first demonstration of epitope differences on this host protein in different species. The defining of various epitopes on PrP through the use of MAbs will lead to a better understanding of the relationship of PrPs to their host precursor protein and to the infectious scrapie agent.

Animals↗
PubMed1986

Immunological comparison of scrapie-associated fibrils isolated from animals infected with four different scrapie strains.

Scrapie-associated fibrils (SAFs) are abnormal filamentous structures that are uniquely associated with unconventional slow virus diseases. The antigenic relationships of SAFs from animals infected with four biologically distinct scrapie strains were investigated by using antisera raised to purified SAF proteins. Rabbit antisera were raised to SAFs isolated from mice infected with the ME7 scrapie strain and to SAFs isolated from hamsters infected with the 263K scrapie strain. A strong antigenic relationship was shown among SAF proteins (PrPs) isolated from all scrapie-infected animals (ME7, 139A, and 87V in mice and 263K in hamsters), and this relationship was demonstrable regardless of which antiserum was used. SAF proteins were antigenically distinct from those of paired helical filaments or amyloid isolated from patients with Alzheimer disease. Distinct Western blot profiles were demonstrated for SAFs isolated from animals infected with each scrapie strain. Differences seen among SAFs were independent, at least in part, of host species or genotype, implying that certain specific structural and molecular properties of SAFs are mediated by the strain of scrapie agent.

Alzheimer Disease↗
PubMed1978

Metabolism of myoinositol in avian and mammalian cells infected with naked and enveloped DNA and RNA viruses.

The uptake of 3H-inositol into the pool of free inositol and its incorporation into the lipid phosphatidylinositol have been studied in various avian and mammalian cells infected by different viruses. In all the virus-cell systems investigated, virus infection results in a drastically reduced amount of free 3H-inositol about 3 to 5 h post-infection, demonstrable in the infected cells as compared to the mock-infected controls. In contrast, the incorporation of 3H-inositol into lipid can be enhanced, reduced, or not influenced at all, depending on the virus-cell system under observation.

Adenoviruses, Human↗
PubMed1977

Different pools of free myoinositol in chick-embryo cells as indicated by infection with Newcastle-disease virus.

Infection of chicken fibroblasts with Newcastle-disease virus indicates that cellular inositol is compartmented in at least two pools. Only the smaller pool is directly connected with the biosynthesis of phosphatidylinositol. Entrance of exogenous inositol into this pool is inhibited by phlorizin but not by the virus. Three hours after infection Newcastle-disease virus blocks the entrance of inositol from the small pool into one (or more) subsequent larger pool(s). About five hours after infection the virus enhances the catabolism of phosphatidylinositol in chicken cells and about seven hours after infection the permeability of the plasma membrane increases.

Animals↗
PubMed1977

Quantitative determination of myoinositol, inositol 1-phosphate, inositol cyclic 1 : 2-phosphate and glycerylphosphoinositol in normal and Rous-sarcoma-virus-transformed quail fibroblasts under different growth conditions.

Myoinositol and its phosphorylated derivatives have been quantitatively determined in normal and Rous-sarcoma-virus-transformed quail cells under various growth conditions using [2-(3)H]myoinositol at isotope equilibrium conditions. The following amounts were determined (nmol/mumol phospholipid, as a unit of cell mass): exponentially growing normal and tumor cells contained 25--40 nmol free inositol, 0.40--0.45 nmol myoinositol 1-phosphate, 0.30--0.50 nmol glycerylphosphoinositol, and 0.03--0.04 nmol myoinositol cyclic 1 : 2-phosphate. At high cell populations in the absence of serum, conditions which result in cessation of growth by normal but not by tumor cells, changed levels were found for glycerylphosphoinositol and free inositol. In tumor cells the levels of these two compounds increased to 0.64 nmol and 64 nmol, respectively. In normal cells glycerylphosphoinositol increased to 0.95 nmol and free inositol showed highly elevated levels of 144 nmol. At short pulses the specific activities of inositol 1-phosphate and inositol cyclic 1 : 2-phosphate were found to be higher than that of phosphatidylinositol. This was not the case for glycerylphosphoinositol.

Animals↗
PubMed1977

Isolation and separation of inositol 1-phosphate, cyclic inositol 1,2-phosphate, and glycerylphosphoinositol from tissue culture cells labeled with [3H]inositol.

Water-soluble phosphorylated inositol derivatives have been separated from each other and from inositol by ion exchange and by thin-layer chromatography. The method, in combination with radioactive labeling, is sensitive enough to be applied to single tissue culture dishes corresponding to 10(6) - 10(7) cells. With this technique glycerylphosphoinositol, inositol 1-phosphate, cyclic inositol 1,2-phosphate, and at least three other inositol labeled compounds can be detected in human, monkey, hamster, mouse, and Japanese quail fibroblasts. During a 24-h incubation with [3H]inositol the extent of labeling of these compounds differed according to the cell type.

Animals↗