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Biomedical subjects

C Bate

Publications and source records attributed to C Bate.

8 recordsLinked to original sources
PubMed2003

Evaluation of quinacrine treatment for prion diseases.

Based on in vitro observations in scrapie-infected neuroblastoma cells, quinacrine has recently been proposed as a treatment for Creutzfeldt-Jakob disease (CJD), including a new variant CJD which is linked to contamination of food by the bovine spongiform encephalopathy (BSE) agent. The present study investigated possible mechanisms of action of quinacrine on prions. The ability of quinacrine to interact with and to reduce the protease resistance of PrP peptide aggregates and PrPres of human and animal origin were analyzed, together with its ability to inhibit the in vitro conversion of the normal prion protein (PrPc) to the abnormal form (PrPres). Furthermore, the efficiencies of quinacrine and chlorpromazine, another tricyclic compound, were examined in different in vitro models and in an experimental murine model of BSE. Quinacrine efficiently hampered de novo generation of fibrillogenic prion protein and PrPres accumulation in ScN2a cells. However, it was unable to affect the protease resistance of preexisting PrP fibrils and PrPres from brain homogenates, and a "curing" effect was obtained in ScGT1 cells only after lengthy treatment. In vivo, no detectable effect was observed in the animal model used, consistent with other recent studies and preliminary observations in humans. Despite its ability to cross the blood-brain barrier, the use of quinacrine for the treatment of CJD is questionable, at least as a monotherapy. The multistep experimental approach employed here could be used to test new therapeutic regimes before their use in human trials.

Animals↗
PubMed2002

Neuroinflammation in Alzheimer's disease and prion disease.

Alzheimer's disease (AD) and prion disease are characterized neuropathologically by extracellular deposits of Abeta and PrP amyloid fibrils, respectively. In both disorders, these cerebral amyloid deposits are co-localized with a broad variety of inflammation-related proteins (complement factors, acute-phase protein, pro-inflammatory cytokines) and clusters of activated microglia. The present data suggest that the cerebral Abeta and PrP deposits are closely associated with a locally induced, non-immune-mediated chronic inflammatory response. Epidemiological studies indicate that polymorphisms of certain cytokines and acute-phase proteins, which are associated with Abeta plaques, are genetic risk factors for AD. Transgenic mice studies have established the role of amyloid associated acute-phase proteins in Alzheimer amyloid formation. In contrast to AD, there is a lack of evidence that cytokines and acute-phase proteins can influence disease progression in prion disease. Clinicopathological and neuroradiological studies have shown that activation of microglia is a relatively early pathogenetic event that precedes the process of neuropil destruction in AD patients. It has also been found that the onset of microglial activation coincided in mouse models of prion disease with the earliest changes in neuronal morphology, many weeks before neuronal loss and subsequent clinical signs of disease. In the present work, we review the similarities and differences between the involvement of inflammatory mechanisms in AD and prion disease. We also discuss the concept that the demonstration of a chronic inflammatory-like process relatively early in the pathological cascade of both diseases suggests potential therapeutic strategies to prevent or to retard these chronic neurodegenerative disorders.

Acute-Phase Proteins↗
PubMed2001

Killing of prion-damaged neurones by microglia.

The loss of neurones that occurs in the transmissible spongiform encephalopathies, or prion diseases, can be reproduced in vitro by incubating neuronal cultures with either peptides derived from the prion protein or with partially purified prion preparations. In the present studies, the extent of neuronal loss on exposure to these prions or prion peptides was increased by the addition of microglia, a process that was dependent upon the number of microglia added, the concentration of prions/peptides present and the degree of fibrillarity of the prion peptides. Microglia also killed scrapie-infected neuroblastoma cells expressing infectious PrP(SC). Microglia secreted low amounts of interleukin (IL)-6 when incubated with peptides alone but up to 10 times as much IL-6 when incubated with peptide-treated neurones, suggesting that microglia recognise peptide-induced changes in neurones.

Animals↗
PubMed1995

Strain variation in tumor necrosis factor induction by parasites from children with acute falciparum malaria.

A small proportion of individuals infected with Plasmodium falciparum develop cerebral malaria. Why it affects some infected individuals but not others is poorly understood. Since tumor necrosis factor (TNF) has been implicated strongly in the pathogenesis of cerebral malaria, here we have compared different parasite isolates for their ability to induce TNF production by human mononuclear cells in vitro. Wild isolates were collected from 34 Gambian children with cerebral malaria and 66 children with uncomplicated malaria fever. Cerebral malaria isolates tended to stimulate more TNF production than mild malaria isolates, but there was considerable overlap between the two groups, and the present data provide only limited support for the hypothesis that cerebral malaria is caused by strains of P. falciparum inducing high levels of TNF. However, it is notable that the amounts of TNF induced by different wild isolates from a single locality differed by over 100-fold. The biological significance of this polymorphism deserves further scrutiny in view of the central role that TNF is believed to play in host defense and in the clinical symptomatology of human malaria.

Acute Disease↗
PubMed1975

Immunogenetic factors in thalassemia and hepatitis B infection. A multicentre study.

Geographical variations in the prevalence of hepatitis B infection were found in association with an increased opportunity of exposure to this virus in patients with homozygous beta-thalassemia in Cyprus, Greece, Sardinia and the United Kingdom. No association was found between the Gm phenotype of the individuals investigated and susceptibility to hepatitis B virus using HBsAg as a marker, or the ability to make antibody to it. Variation in the distribution of Gm haplotypes does not appear to be a feasible explanation for variation in anti-HBs and HBsAg frequencies in a series of highly transfused populations.

Adolescent↗