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James W Ironside

Publications and source records attributed to James W Ironside.

At least 19 recordsLinked to original sources
PubMed2006

Variant Creutzfeldt-Jakob disease: prion protein genotype analysis of positive appendix tissue samples from a retrospective prevalence study.

OBJECTIVE: To perform prion protein gene (PRNP) codon 129 analysis in DNA extracted from appendix tissue samples that had tested positive for disease associated prion protein. DESIGN: Reanalysis of positive cases identified in a retrospective anonymised unlinked prevalence study of variant Creutzfeldt-Jakob disease (vCJD) in the United Kingdom. STUDY SAMPLES: Three positive appendix tissue samples out of 12,674 samples of appendix and tonsil tested for disease associated prion protein. The patients from whom these samples were obtained were aged 20-29 years at the time of surgery, which took place in 1996-9. SETTING: Pathology departments in two tertiary centres in England and Scotland. RESULTS: Adequate DNA was available for analysis in two of the three specimens, both of which were homozygous for valine at codon 129 in the PRNP. CONCLUSIONS: This is the first indication that the valine homozygous subgroup at codon 129 in the PRNP is susceptible to vCJD infection. All tested clinical cases of vCJD have so far occurred in the methionine homozygous subgroup, and a single case of probable iatrogenic vCJD infection has been identified in one patient who was a methionine/valine heterozygote at this genetic locus. People infected with vCJD with a valine homozygous codon 129 PRNP genotype may have a prolonged incubation period, during which horizontal spread of the infection could occur either from blood donations or from contaminated surgical instruments used on these individuals during the asymptomatic phase of the illness.

Adolescent↗
PubMed2006

vCJD prion acquires altered virulence through trans-species infection.

Variant Creutzfeldt-Jakob disease (vCJD) appears to be caused by infection with the bovine spongiform encephalopathy (BSE) agent. To date, all patients with vCJD are homozygous for methionine at codon 129 of the PrP gene. To investigate the relationship between polymorphism at codon 129 and susceptibility to BSE or vCJD prions, we performed splenic follicular dendritic cell assay with humanized knock-in mice through peripheral infection. All humanized knock-in mice showed little or no susceptibility to BSE prions. Only the subset of humanized knock-in mice with codon 129 Met/Met genotype showed weak susceptibility by Western blotting. Surprisingly, we succeeded in the transmission of vCJD prions to humanized knock-in mice not only with codon 129 Met/Met but also with codon 129 Met/Val. Humanized knock-in mice with codon 129 Val/Val were not susceptible. The results suggest that human heterozygotes at codon 129 are also at risk for secondary infection with vCJD.

Animals↗
PubMed2006

Application of an immunocapillary electrophoresis assay to the detection of abnormal prion protein in brain, spleen and blood specimens from patients with variant Creutzfeldt-Jakob disease.

Sensitive and specific detection of abnormal prion protein in blood could provide a diagnostic test or screening assay for animal and human prion diseases. Here, the application of an immunocapillary electrophoresis (ICE) method developed for sheep scrapie to brain, spleen and blood from patients with Creutzfeldt-Jakob disease (CJD) is described. The assay involves organic-solvent extraction, a competitive immunoassay using fluorescently labelled synthetic prion protein peptides and polyclonal antibodies specific for those sequences, and analysis by capillary electrophoresis using laser-induced fluorescence detection. The test was evaluated by using clinical blood specimens from patients with variant (n=5) or sporadic (n=4) CJD and patients initially suspected of having CJD who were given an alternative diagnosis (n=6). In this context, the ICE assay was specific, but incompletely sensitive (55%). The method was unable to detect abnormal prion protein in variant CJD brain or spleen reference materials due to its loss during the extraction process.

Brain↗
PubMed2006

Detection of type 1 prion protein in variant Creutzfeldt-Jakob disease.

Molecular typing of the abnormal form of the prion protein (PrP(Sc)) has come to be regarded as a powerful tool in the investigation of the prion diseases. All evidence thus far presented indicates a single PrP(Sc) molecular type in variant Creutzfeldt-Jakob disease (termed type 2B), presumably resulting from infection with a single strain of the agent (bovine spongiform encephalopathy). Here we show for the first time that the PrP(Sc) that accumulates in the brain in variant Creutzfeldt-Jakob disease also contains a minority type 1 component. This minority type 1 PrP(Sc) was found in all 21 cases of variant Creutzfeldt-Jakob disease tested, irrespective of brain region examined, and was also present in the variant Creutzfeldt-Jakob disease tonsil. The quantitative balance between PrP(Sc) types was maintained when variant Creutzfeldt-Jakob disease was transmitted to wild-type mice and was also found in bovine spongiform encephalopathy cattle brain, indicating that the agent rather than the host specifies their relative representation. These results indicate that PrP(Sc) molecular typing is based on quantitative rather than qualitative phenomena and point to a complex relationship between prion protein biochemistry, disease phenotype and agent strain.

Amino Acid Sequence↗
PubMed2006

Detection and localization of PrPSc in the skeletal muscle of patients with variant, iatrogenic, and sporadic forms of Creutzfeldt-Jakob disease.

Variant Creutzfeldt-Jakob disease (vCJD) differs from other human prion diseases in that the pathogenic prion protein PrP(Sc) can be detected to a greater extent at extraneuronal sites throughout the body, principally within lymphoid tissues. However, a recent study using a high-sensitivity Western blotting technique revealed low levels of PrP(Sc) in skeletal muscle from a quarter of Swiss patients with sporadic CJD (sCJD). This posed the question of whether PrP(Sc) in muscle could also be detected in vCJD, sCJD, and iatrogenic (iCJD) patients from other populations. Therefore, we have used the same high-sensitivity Western blotting technique, in combination with paraffin-embedded tissue blotting, to screen for PrP(Sc) in muscle tissue specimens taken at autopsy from 49 CJD patients in the United Kingdom. These techniques identified muscle PrP(Sc) in 8 of 17 vCJD, 7 of 26 sCJD, and 2 of 5 iCJD patients. Paraffin-embedded tissue blotting analysis showed PrP(Sc) in skeletal muscle in localized anatomical structures that had the morphological and immunohistochemical characteristics of nerve fibers. The detection of PrP(Sc) in muscle tissue from all forms of CJD indicates the possible presence of infectivity in these tissues, suggesting important implications for assessing the potential risk of iatrogenic spread via contaminated surgical instruments.

Animals↗
PubMed2005

Correlative studies support lipid peroxidation is linked to PrP(res) propagation as an early primary pathogenic event in prion disease.

To assess whether heightened oxidative stress plays an early and primary pathogenic role in transmissible spongiform encephalopathies (TSE), we undertook detailed correlative studies using a mouse-adapted model of human disease. The spatio-temporal evolution of the abnormal, protease-resistant isoform of the prion protein (PrP(res)) and neuropathological changes were correlated with the occurrence and type of oxidative stress. Heightened oxidative stress was demonstrated, but restricted to elevated levels of free aldehydic breakdown products of lipid peroxidation, affecting all brain regions to varying extents. The increase in lipid peroxidation was highest over the mid-incubation period, with the onset showing close temporal and general topographical concordance with the first detection of PrP(res) with both pre-empting the typical neuropathological changes of spongiform change, gliosis and neuronal loss. Further, prion propagation over the disease course was assessed using murine bioassay. This revealed that the initial rapid increase in infectivity titres was contemporaneous with the abrupt onset and maximisation of lipid peroxidation. The present results are an important extension to previous studies, showing that heightened oxidative stress in the form of lipid peroxidation is likely to constitute an early primary pathogenic event in TSE, associated temporally with the integral disease processes of prion propagation and PrP(res) formation, and consistent with causal links between these events and subsequent typical neuropathological changes.

Analysis of Variance↗
PubMed2005

Redox metals and oxidative abnormalities in human prion diseases.

Prion diseases are characterized by the accumulation of diffuse and aggregated plaques of protease-resistant prion protein (PrP) in the brains of affected individuals and animals. Whereas prion diseases in animals appear to be almost exclusively transmitted by infection, human prion diseases most often occur sporadically and, to a lesser extent, by inheritance or infection. In the sporadic cases (sporadic Creutzfeld-Jakob disease, sCJD), PrP-containing plaques are infrequent, whereas in transmitted (variant CJD) and inherited (Gerstmann-Straussler-Scheinker Syndrome) cases, plaques are a usual feature. In the current study, representative cases from each of the classes of human prion disease were analyzed for the presence of markers of oxidative damage that have been found in other neurodegenerative diseases. Interestingly, we found that the pattern of deposition of PrP, amyloid-beta, and redox active metals was distinct for the various prion diseases. Whereas 8-hydroxyguanosine has been shown to be increased in sCJD, and inducible NOS is increased in scrapie-infected mice, well-studied markers of oxidative damage that accumulate in the lesions of other neurodegenerative diseases (such as Alzheimer's disease, progressive supranuclear palsy, and Parkinson's disease), such as heme oxygenase-1 and lipid peroxidation, were not found around PrP deposits or in vulnerable neurons. These findings suggest an important distinction in prion-related oxidative stress, indicating that different neurodegenerative pathways are involved in different prion diseases.

Adult↗
PubMed2005

Anti-hu paraneoplastic syndrome presenting as bilateral sixth cranial nerve palsies.

A 62-year-old woman presented with diplopia caused by bilateral sixth cranial nerve palsies. Two weeks later, she had bulbar weakness and ataxia. Brain magnetic resonance imaging showed non-specific abnormalities and spinal fluid was acellular but contained an elevated protein and oligoclonal bands. A paraneoplastic screen showed anti-Hu antibodies. Her clinical condition improved with immunoglobulin and systemic corticosteroid treatment. Breast cancer was diagnosed 21 months later by mammography but there were no metastases detected. Four and half years after the onset of her diplopia, she died of diffuse metastatic breast cancer. This is the first reported case of anti-Hu paraneoplastic brain stem encephalitis presenting with sixth cranial nerve palsies.

Abducens Nerve Diseases↗
PubMed2005

Type 1 and type 2 human PrPSc have different aggregation sizes in methionine homozygotes with sporadic, iatrogenic and variant Creutzfeldt-Jakob disease.

In Creutzfeldt-Jakob disease (CJD), the type (type 1 or 2) of abnormal isoform of the prion protein (PrP(Sc)) in the brain and the genotype at codon 129 of the PrP gene are major determinants of clinicopathological phenotype. Little is known about the difference in biochemical properties between the two types of PrP(Sc), except for the different proteinase K cleavage sites. To investigate the size of aggregates formed by PrP(Sc) types 1 and 2, brain homogenates from various cases of CJD with the same genotype (homozygous for methionine at codon 129) were passed through filters with a mean pore size of 72+/-4 nm. Type 2 PrP(Sc) was efficiently removed from the filtrates by the filters, in contrast to type 1. Even type 2 PrP(Sc) from a patient without amyloid plaques was removed more efficiently than type 1 from patients with amyloid plaques. These results indicate that type 2 PrP(Sc) has a larger aggregation size than type 1, irrespective of the existence of amyloid plaques.

Blotting, Western↗
PubMed2005

Risks of transmission of variant Creutzfeldt-Jakob disease by blood transfusion.

Variant Creutzfeldt-Jakob disease (vCJD) was first identified in 1996 in the UK, and results from human exposure to the bovine spongiform encephalopathy (BSE) agent. vCJD has subsequently been identified in 10 additional countries, and numbers continue to increase in the UK. Unlike other human prion diseases, infectivity and the disease-associated form of the prion protein are readily detected in lymphoid tissues in vCJD. In experimental BSE infection in a sheep model, infectivity has been transmitted by blood transfusion from asymptomatic infected animals to normal recipient animals, indicating that infectivity is present in blood during the incubation period. Recently, two cases of apparent iatrogenic vCJD infection by blood transfusion from asymptomatic donors who subsequently died from vCJD have been reported from the UK. The first case resulted in clinical illness identical to other cases of vCJD, while the second case was an asymptomatic infection detected at autopsy. Sensitive means of detection of disease-associated prion protein in the blood are required in order to be employed for screening purposes, both individually at the time of blood donation, and to help ascertain future numbers of vCJD cases in the UK and beyond.

Animals↗
PubMed2004

Prion protein heterogeneity in sporadic but not variant Creutzfeldt-Jakob disease: UK cases 1991-2002.

Human prion diseases can occur as an idiopathic disorder (sporadic Creutzfeldt-Jakob disease) or can be acquired, as is the case for variant Creutzfeldt-Jakob disease. These disorders are characterized by the accumulation of a protease-resistant form of the host-encoded prion protein termed PrP(Sc) in the brains of affected individuals. PrP(Sc) has been proposed to be the principal, if not sole, component of the infectious agent, with its accumulation in the central nervous system the primary event leading to neurodegeneration. A major question remains as to whether self-propagating structural differences in PrP(Sc) might account for the clinicopathological diversity evident in Creutzfeldt-Jakob disease and whether different prion protein types underlie the existence of different strains of causative agent. Here, we describe the results of a large-scale biochemical study of PrP(Sc) from autopsy-proved cases of variant Creutzfeldt-Jakob disease (n = 59) and compare these with cases of sporadic Creutzfeldt-Jakob disease (n = 170) in the United Kingdom over the period 1991 to 2002. The results show PrP(Sc) in variant Creutzfeldt-Jakob disease to be remarkably stereotyped. In contrast, considerable heterogeneity in PrP(Sc) exists both between and within cases of sporadic Creutzfeldt-Jakob disease.

Adolescent↗
PubMed2004

Prevalence of lymphoreticular prion protein accumulation in UK tissue samples.

This study aims to provide an estimate of the number of individuals in the UK who may be incubating variant Creutzfeldt-Jakob disease and at risk of causing iatrogenic spread of the disease. Lymphoreticular accumulation of prion protein is a consistent feature of variant Creutzfeldt-Jakob at autopsy and has also been demonstrated in the pre-clinical phase. Immunohistochemical accumulation of prion protein in the lymphoreticular system remains the only technique that has been shown to predict neurological disease reliably in animal prion disorders. In this study, immunohistochemistry was used to demonstrate the presence of prion protein, with monoclonal antibodies KG9 and 3F4, in surgically removed tonsillectomy and appendicectomy specimens. The samples were collected from histopathology departments across the UK and anonymised prior to testing. Samples were tested from 16 703 patients (14 964 appendectomies, 1739 tonsillectomies), approximately 60% of whom were from the age group 20-29 years at operation. Twenty-five per cent of the samples were excluded from the final analyses because they contained inadequate amounts of lymphoid tissue. Three appendicectomy samples showed lymphoreticular accumulation of prion protein, giving an estimated prevalence of 3/12 674 or 237 per million (95% CI 49-692 per million). The pattern of lymphoreticular accumulation in two of these samples was dissimilar from that seen in known cases of variant Creutzfeldt-Jakob disease. Although it is uncertain whether immunohistochemical accumulation of prion protein in the lymphoreticular system is specific for variant Creutzfeldt-Jakob disease, it has not been described in any other disease, including other forms of human prion disease or a range of inflammatory and infective conditions. These findings reinforce the importance of measures taken by the UK Department of Health to reduce the risk of spread of variant Creutzfeldt-Jakob via blood products and surgical instruments, and of the urgency to proceed with large-scale screening of fresh tonsil specimens for the presence of prion protein.

Adolescent↗
PubMed2004

BSE and vCJD cause disturbance to uric acid levels.

Bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (vCJD) are two new members of the family of neurodegenerative conditions termed prion diseases. Oxidative damage has been shown to occur in prion diseases and is potentially responsible for the rapid neurodegeneration that is central to the pathogenesis of these diseases. An important nonenzymatic antioxidant in the brain is uric acid. Analysis of uric acid in the brain and cerebrospinal fluid (CSF) of cases of BSE and CJD showed a specific reduction in CSF levels for both BSE and variant CJD, but not sporadic CJD. Further studies based on cell culture experiments suggested that uric acid in the brain was produced by microglia. Uric acid was also shown to inhibit neurotoxicity of a prion protein peptide, production of the abnormal prion protein isoform (PrP(Sc)) by infected cells, and polymerization of recombinant prion protein. These findings suggest that changes in uric acid may aid differential diagnosis of vCJD. Uric acid could be used to inhibit cell death or PrP(Sc) formation in prion disease.

Animals↗
PubMed2004

Complement activation in human prion disease.

The central event in the neuropathological process of prion diseases (PrD) is the accumulation of abnormal prion protein accompanied by severe neuronal loss. Despite the infectious nature of these diseases, no prominent immune response has been detected yet. However, recent studies have shown that complement, a component of the innate immune system, is involved in the early pathogenesis of experimental prion infection. Here we demonstrate, in the diseased human brains, the presence of active compounds of the complement system, like C1q and C3b, in extracellular disease-associated prion protein deposits and the membrane attack complex in neurons. The neuronal localization of the membrane attack complex correlates well with the severity of disease-specific pathology and TUNEL labeling of neurons, irrespective of genotype or molecular phenotype of human prion diseases.

Adolescent↗
PubMed2004

Peripheral tissue involvement in sporadic, iatrogenic, and variant Creutzfeldt-Jakob disease: an immunohistochemical, quantitative, and biochemical study.

Human prion diseases are rare fatal neurodegenerative conditions that occur as acquired, familial, or idiopathic disorders. A key event in their pathogenesis is the accumulation of an altered form of the prion protein, termed PrP(Sc), in the central nervous system. A novel acquired human prion disease, variant Creutzfeldt-Jakob disease, is thought to result from oral exposure to the bovine spongiform encephalopathy agent. This disease differs from other human prion diseases in its neurological, neuropathological, and biochemical phenotype. We have used immunohistochemistry and Western blot techniques to analyze the tissue distribution and biochemical properties of PrP(Sc) in peripheral tissues in a unique series of nine cases of variant Creutzfeldt-Jakob disease. We have compared this with the distribution and biochemical forms found in all of the major subtypes of sporadic Creutzfeldt-Jakob disease and in a case of iatrogenic Creutzfeldt-Jakob disease associated with growth hormone therapy. The results show that involvement of the lymphoreticular system is a defining feature of variant Creutzfeldt-Jakob disease, but that the biochemical isoform of PrP(Sc) found is influenced by the cell type in which it accumulates.

Blotting, Western↗
PubMed2004

Prion protein accumulation and neuroprotection in hypoxic brain damage.

The function of the normal conformational isoform of prion protein, PrP(C), remains unclear although lines of research have suggested a role in the cellular response to oxidative stress. Here we investigate the expression of PrP(C) in hypoxic brain tissues to examine whether PrP(C) is in part regulated by neuronal stress. Cases of adult cerebral ischemia and perinatal hypoxic-ischemic injury in humans were compared with control tissues. PrP(C) immunoreactivity accumulates within neuronal processes in the penumbra of hypoxic damage in adult brain, and within neuronal soma in cases of perinatal hypoxic-ischemic injury, and in situ hybridization analysis suggests an up-regulation of PrP mRNA during hypoxia. Rodents also showed an accumulation of PrP(C) in neuronal soma within the penumbra of ischemic lesions. Furthermore, the infarct size in PrP-null mice was significantly greater than in the wild type, supporting the proposed role for PrP(C) in the neuroprotective adaptive cellular response to hypoxic injury.

Adult↗
PubMed2004

Expression of excitatory amino acid transporter-1 (EAAT-1) in brain macrophages and microglia of patients with prion diseases.

The mechanisms of neuronal apoptosis in prion diseases are unclear. Experimental studies suggest that it may result from 2 associated mechanisms: glutamate-mediated excitotoxicity and oxidative stress. Recent studies showed that activated macrophages/microglia (AMM) express excitatory amino acid transporters (EAATs) in HIV infection, suggesting that they may play a neuroprotective role by clearing extra-cellular glutamate and producing anti-oxidant glutathione. In order to test this hypothesis in prion diseases, samples from cerebral cortex, striatum, thalamus, and cerebellum from 14 patients with Creutzfeldt-Jakob disease (8 sporadic, 2 familial, 2 iatrogenic, and 2 variant), and 4 with fatal familial insomnia (3 homozygous Met/Met at codon 129 of the PRNP gene, 1 heterozygous Met/Val), and 3 controls were immunostained for EAAT-1, GFAP, HLA-DR, CD68, IL-1, caspase 3, and PrP. In prion diseases, EAAT-1 immunopositivity was found in affected areas. Only AMM, interstitial, perivascular, perineuronal (sometimes around apoptotic neurons), or close to reactive astrocytes, expressed EAAT-1. Astrocyte EAAT-1 expression was scarcely detectable in controls and was not detected in prion disease cases. The proportion of AMM expressing EAAT-1 did not correlate with the severity of neuronal apoptosis, spongiosis, astrocytosis, microgliosis, or PrP deposition, but only with disease duration. Occasional EAAT-1 expressing AMM were found in patients with short survival, whereas diffuse EAAT-1 expression by AMM was observed in cases with long survival (24 to 33 months) that most often were heterozygous for Met/Val at codon 129 of the PRNP gene. Our findings suggest that AMM may develop a partial neuroprotective function in long-lasting prion diseases, although it does not seem to efficiently prevent neurological and neuropathological deterioration. Whether this neuroprotective function of microglia is the cause or the effect of longer survival needs to be clarified.

Adult↗