Search PubMed⌕ Search

Biomedical subjects

H Diringer

Publications and source records attributed to H Diringer.

At least 55 records · Page 3Linked to original sources
PubMed1988

Replication of the scrapie agent in hamsters infected intracerebrally confirms the pathogenesis of an amyloid-inducing virosis.

Following intracerebral infection of hamsters with scrapie agent replication started with or without a very short lag phase. Infectivity titres increased exponentially within 35 to 40 days post-infection to a maximum level of 3 x 10(9) LD50 per brain and then remained constant until death. Minimal detectable amounts of scrapie-associated fibrils (SAF) appeared at 42 days and reached high levels 56 days after inoculation. The first clinical symptoms were diagnosed at about 65 days and animals died after 85 to 95 days. These data confirm earlier results in which peripheral infection first revealed agent replication, then SAF formation and finally clinical disease. Unconventional virus diseases, therefore, can best be described as virus-induced, organ-specific amyloidoses.

Amyloidosis↗
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

Pathogenesis of scrapie: study of the temporal development of clinical symptoms, of infectivity titres and scrapie-associated fibrils in brains of hamsters infected intraperitoneally.

After an intraperitoneal infection of hamsters with scrapie agent, early low and constant titres of about 100 LD50/brain between days 10 to 50 were followed by a dramatic increase to maximum levels of 3 X 10(9) LD50/brain within about 15 days. The plateau of maximum infectivity remained unchanged from day 70 to the time of the first and final signs of disease at 95 and 123 days post-infection, respectively. Scrapie-associated fibrils (SAF) as measured by immunoblotting of SAF protein could not be detected before 79 days post-infection even when a total brain was used for analysis. Subsequently, the concentration of SAF increased gradually by about 100,000-fold until the time of clinical disease. The kinetics suggest a virus-induced amyloidosis of the brain as the cause of disease.

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↗
PubMed1985

The protein component of scrapie-associated fibrils is a glycosylated low molecular weight protein.

Scrapie-associated fibril protein (SAF-protein) extracted from infectious scrapie-associated fibrils (SAF) isolated from scrapie hamster brains is not infectious. SAF-protein is composed of various mol. wt. species of glycoproteins differing in carbohydrate content rather than amino acid composition. The N-linked carbohydrate chains represent approximately 40-60% of the mol. wt. of SAF-protein. The deglycosylated SAF-protein has a surprisingly low mol. wt. of approximately 7 kd, representing approximately 55 amino acid residues. This size and chemical analyses indicate that SAF-protein is an amyloid-type of protein. The simplest explanation for the available data is that SAF-polypeptide is very likely not to be part of the scrapie agent but that it is, like other amyloid proteins, derived from host-encoded proteins and not infectious. It is suggested that the infectivity of fractions rich in SAF is due to co-purification of scrapie virus and SAF caused by the high carbohydrate content of SAF-protein.

Amino Acid Sequence↗
PubMed1985

Scrapie: concept of a virus-induced amyloidosis of the brain.

After an intraperitoneal infection disease-specific incorporation of [3H]leucine into protein and [3H]uridine into RNA in the brain precede clinical scrapie in hamsters. Onset of both incorporations are the earliest measurable events in the disease. Infectivity and subsequent clinical symptoms appear only after this biochemical activity has ceased. The disease-specific [3H]protein co-purifies with scrapie-associated fibrils (SAF) and infectivity during differential centrifugation and buffer extraction. SDS-PAGE shows that the [3H]protein is not SAF protein but a protein with an apparently higher mol. wt. The [3H]RNA is metabolically stable and separates from SAF and the main portion of infectivity in the last step of the purification. The appearance of SAF-protein is a late event and correlates with severe clinical symptoms. SAF seems to be derived from a brain protein turning over slowly. Our data are consistent with early pre-clinical virus replication. In this case treatment aimed at suppressing virus replication in the clinical phase of the human Creutzfeldt-Jakob disease is unlikely to produce any beneficial effect.

Amyloidosis↗
PubMed1985

Characterization of antisera against scrapie-associated fibrils (SAF) from affected hamster and cross-reactivity with SAF from scrapie-affected mice and from patients with Creutzfeldt-Jakob disease.

Antisera raised in rabbits and also for the first time in mice against scrapie-associated fibril (SAF) protein from hamster brain have been quantified by a modified ELISA technique (NC-ELISA) and used for a detailed analysis of SAF proteins obtained from hamster, mouse, and from patients who died of Creutzfeldt-Jakob disease. The antisera predominantly detected five bands in a Western blot analysis with apparent molecular weights of about 26000 (26K), 24K, 20K, 18K and 16K. By gel electrophoresis these antigens seem to be identical in mouse, hamster and man. The amount of material in the various bands, however, varies according to host or agent. In control materials from healthy brain SAF protein was found to be absent even when this material was used in a 50-fold excess compared to diseased brain.

Animals↗
PubMed1985

Isolation and characterization of a 14500 molecular weight protein from brains and tissue cultures persistently infected with borna disease virus.

A protein with an apparent molecular weight of 14500 (14.5K) was extractable from homogenates of Borna disease virus-infected brains and tissue cultures using high concentrations of detergent and salt and by differential centrifugation procedures. The protein, present in an aggregated form, was remarkably resistant to proteinase K. Specific antibodies prepared in the homologous system (rat) recognized the 14.5K protein from various sources (infected brain of rat, mouse or chicken, and tissue cultures), but did not neutralize infectivity nor stain Borna disease virus-specific antigens from in vitro or in vivo preparations. Post-infection immune sera from different animal species did not detect the protein. This 14.5K protein was infection-specific but not disease-specific, and is inferred to be part of an internal virion component.

Animals↗
PubMed1985

Biochemical differences among scrapie-associated fibrils support the biological diversity of scrapie agents.

Scrapie-associated fibrils (SAF) were isolated and purified from animals infected with three different scrapie agents: ME7 and 139A in mice, and 263K in hamsters. Mouse ME7 and 139A SAF differed from hamster 263K SAF in morphology, sedimentation rate and protein composition. SAF from the three scrapie agents were distinguishable from each other by their sensitivity to proteinase K digestion. SAF copurified with infectivity in both the hamster and mouse systems. SAF appear to be a unique class of structures which are related but specific for each individual scrapie agent. These properties may correlate with the biological and pathological differences seen among these agents.

Animals↗
PubMed1985

Absence of autoantibodies against neurofilament proteins in the sera of scrapie infected mice.

Autoantibodies against neurofilament proteins were not detected in any of the sera from the following scrapie infected mice: 19 mice infected with scrapie agent 139A in pre-clinical stage, 32 histologically confirmed scrapie mice and other 12 clinical scrapie mice infected with various strains. The test sera were assayed against acetone-fixed central neuron cultures from fetal mice by indirect immunofluorescence and immunoperoxidase techniques. The negative result suggests that autoantibodies against neurofilament proteins do not play a role in the pathogenesis of scrapie.

Animals↗
PubMed1984

A rapid and efficient method to enrich SAF-protein from scrapie brains of hamsters.

Scrapie hamster brains contain at least 5-10 micrograms of scrapie-associated fibrils (SAF) per brain as estimated by the amount of its major constituent, a protein of about 26 000 daltons (SAF-protein). It can be extracted efficiently by a 10% solution of sarkosyl and can be enriched by differential centrifugation and buffer extraction. Scrapie infectivity, SAF, and SAF-protein copurify.

Animals↗
PubMed1984

The reticuloendothelial system in scrapie pathogenesis.

A single injection of 1 mg dextran sulphate 500 per mouse considerably prolonged incubation times and produced survivors, even when given 3 days after intravenous or intraperitoneal scrapie infection. Since this compound could be detected in mononuclear phagocytes of spleen and lymph nodes for up to 7 months, it is suggested that it impairs a particular step in the infectious process in these cells of the lymphoreticular system. Blockage of the reticuloendothelial system by trypan blue and silica did not alter the pathogenesis.

Animals↗
PubMed1984

Dextran sulphate 500 delays and prevents mouse scrapie by impairment of agent replication in spleen.

Treatment of scrapie-infected mice with dextran sulphate (DS) 500 resulted in considerably reduced spleen titres over a long period of time. Subsequently, the central nervous system disease was delayed or even prevented during the 350-day period of observation. Both effects increased after multiple injections of the compound. The potency of DS 500 to protect against scrapie was greatest when treatment and infection were carried out simultaneously. Under these conditions the lethality of 500 to 1000 LD50 was reduced to almost zero. Treatment as early as 10 weeks before infection still prolonged the incubation periods. Of several other polyions tested, dextran sulphate 5 and pentosan polysulphate also impaired scrapie pathogenesis.

Animals↗