Characterization of Sporadic Creutzfeldt-Jakob Disease and History of Neurosurgery to Identify Potential Iatrogenic Cases

We previously reported a phenotype of Creutzfeldt-Jakob disease (CJD), CJD-MMiK, that could help identify iatrogenic CJD. To find cases mimicking CJD-MMiK, we investigated clinical features and pathology of 1,155 patients with diagnosed sporadic CJD or unclassified CJD with and without history of neurosurgery. Patients with history of neurosurgery more frequently had an absence of periodic sharp-wave complexes on electroencephalogram than patients without a history of neurosurgery. Among 27 patients with history of neurosurgery, 5 had no periodic sharp-wave complexes on electroencephalogram. We confirmed 1 case of CJD-MMiK and suspected another. Both had methionine homozygosity at codon 129 of the prion protein gene and hyperintensity lesions in the thalamus on magnetic resonance images of the brain, which might be a clinical marker of CJD-MMiK. A subgroup with a history of neurosurgery and clinical features mimicking dura mater graft-associated CJD might have been infected during neurosurgery and had symptoms develop after many years.

How an Infection of Sheep Revealed Prion Mechanisms in Alzheimer's Disease and Other Neurodegenerative Disorders

Although it is not yet universally accepted that all neurodegenerative diseases (NDs) are prion disorders, there is little disagreement that Alzheimer's disease (AD), Parkinson's disease, frontotemporal dementia (FTD), and other NDs are a consequence of protein misfolding, aggregation, and spread. This widely accepted perspective arose from the prion hypothesis, which resulted from investigations on scrapie, a common transmissible disease of sheep and goats. The prion hypothesis argued that the causative infectious agent of scrapie was a novel proteinaceous pathogen devoid of functional nucleic acids and distinct from viruses, viroids, and bacteria. At the time, it seemed impossible that an infectious agent like the one causing scrapie could replicate and exist as diverse microbiological strains without nucleic acids. However, aggregates of a misfolded host-encoded protein, designated the prion protein (PrP), were shown to be the cause of scrapie as well as Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker syndrome (GSS), which are similar NDs in humans. This review discusses historical research on diseases caused by PrP misfolding, emphasizing principles of pathogenesis that were later found to be core features of other NDs. For example, the discovery that familial prion diseases can be caused by mutations in PrP was important for understanding prion replication and disease susceptibility not only for rare PrP diseases but also for far more common NDs involving other proteins. We compare diseases caused by misfolding and aggregation of APP-derived Aβ peptides, tau, and α-synuclein with PrP prion disorders and argue for the classification of NDs caused by misfolding of these proteins as prion diseases. Deciphering the molecular pathogenesis of NDs as prion-mediated has provided new approaches for finding therapies for these intractable, invariably fatal disorders and has revolutionized the field.

Epitope mapping of the protease resistant products of RT-QuIC does not allow the discrimination of sCJD subtypes

Sporadic Creutzfeldt-Jakob disease (sCJD) is a transmissible, rapidly progressive and fatal neurodegenerative disease. The transmissible agent linked to sCJD is composed of the misfolded form of the host-encoded prion protein. The combination of histopathological and biochemical analyses has allowed the identification and sub-classification of six sCJD subtypes. This classification depends on the polymorphic variability of codon 129 of the prion protein gene and the PrPres isotype, and appears to be associated with neuropathological and clinical features. Currently, sCJD subtyping is only fully achievable post mortem. However, a rapid and non-invasive method for discriminating sCJD subtypes in vita would be invaluable for the clinical management of affected individuals, and for the selection of participants for clinical trials. The CSF analysis by Real Time Quaking Induced Conversion (RT-QuIC) reaction is the most sensitive and specific ante mortem sCJD diagnostic test available to date, and it is used by a number of laboratories internationally. RT-QuIC takes advantage of the natural replication mechanisms of prions by template-induced misfolding, employing recombinant prion protein as reaction substrate. We asked whether epitope mapping, of the RT-QuIC reaction products obtained from seeding RT-QuIC with brain and CSF samples from each of the six molecular subtypes of sCJD could be employed to distinguish them and therefore achieve in vita sCJD molecular subtyping. We found that it is possible to distinguish the RT-QuIC products generated by sCJD biological samples from the ones generated by spontaneous conversion in the negative controls, but that different sCJD subtypes generate very similar, if not identical RT-QuIC reaction products. We concluded that whilst RT-QuIC has demonstrable diagnostic value it has limited prognostic value at this point in time.

Transmission of amyloid-β protein pathology from cadaveric pituitary growth hormone

We previously reported1 the presence of amyloid-β protein (Aβ) deposits in individuals with Creutzfeldt-Jakob disease (CJD) who had been treated during childhood with human cadaveric pituitary-derived growth hormone (c-hGH) contaminated with prions. The marked deposition of parenchymal and vascular Aβ in these relatively young individuals with treatment-induced (iatrogenic) CJD (iCJD), in contrast to other prion-disease patients and population controls, allied with the ability of Alzheimer's disease brain homogenates to seed Aβ deposition in laboratory animals, led us to argue that the implicated c-hGH batches might have been contaminated with Aβ seeds as well as with prions. However, this was necessarily an association, and not an experimental, study in humans and causality could not be concluded. Given the public health importance of our hypothesis, we proceeded to identify and biochemically analyse archived vials of c-hGH. Here we show that certain c-hGH batches to which patients with iCJD and Aβ pathology were exposed have substantial levels of Aβ40, Aβ42 and tau proteins, and that this material can seed the formation of Aβ plaques and cerebral Aβ-amyloid angiopathy in intracerebrally inoculated mice expressing a mutant, humanized amyloid precursor protein. These results confirm the presence of Aβ seeds in archived c-hGH vials and are consistent with the hypothesized iatrogenic human transmission of Aβ pathology. This experimental confirmation has implications for both the prevention and the treatment of Alzheimer's disease, and should prompt a review of the risk of iatrogenic transmission of Aβ seeds by medical and surgical procedures long recognized to pose a risk of accidental prion transmission2,3.

Nonopportunistic infection leading to rapidly progressive dementia in a patient with HIV/AIDS: A case report

RATIONALE

Cognitive dysfunction is a common presenting symptom in patients with HIV/AIDS. It is usually directly associated with HIV infection or due to opportunistic infection. Rapidly progressive dementia, however, is rarely observed in acute HIV infection or during immune reconstitution. Recently, a case of Creutzfeld-Jakob disease (CJD) has been reported in a patient with chronic HIV infection. The incidence of CJD is not known to be increased among immunocompromised patients.

PATIENT CONCERNS

We here report the case of a 59-year-old male patient with a recent diagnosis of HIV/AIDS and Pneumocystis jiroveci pneumonia presenting with secondary behavioral changes and disorientation. Over the course of several weeks, progressive dementia developed characterized by apraxia, gait ataxia, and mutism.

DIAGNOSES

After the exclusion of common HIV-associated neurologic conditions, the clinical course as well as findings on electroencephalogram (EEG), magnetic resonance imaging (MRI), and a positive 14-3-3 assay converged into a probable diagnosis of CJD. The diagnosis was later confirmed histopathologically.

OUTCOMES

Palliative care was provided, and the patient passed away within 2 months of symptom onset.

LESSONS

HIV/AIDS is an important stratifying condition during the work-up of many clinical syndromes including encephalopathy but may prematurely exclude important differential diagnoses. Non-opportunistic etiologies have to be considered as part of a secondary workup as this case of concomitant AIDS and CJD demonstrates. Rapidly progressive dementia should be distinguished from delirium as early as possible in order to be able to choose the correct diagnostic pathway. Despite the common occurrence of neurologic syndromes in the setting of immunodeficiency, an analytical diagnostic approach is advisable to minimize diagnostic bias.

Infectious and Sporadic Prion Diseases

Prion diseases are progressive fatal encephalopathies characterized by a neurodegenerative pathology, the tissue deposition of abnormally folded prion protein and, in general, potential transmissibility. Creutzfeldt-Jakob disease (CJD) is the commonest human prion disease and occurs in three principal forms: sporadic (idiopathic), acquired (infectious), and inherited (genetic). This chapter concerns the sporadic and acquired forms. Sporadic CJD occurs worldwide and affects mainly the middle aged and elderly. There are recognized genetic risk factors-most importantly the PRNP-129 polymorphism. The acquired forms of CJD consist of iatrogenic CJD (accidental transmission of CJD via medical or surgical procedures) and variant CJD (vJCD) (which originated as a zoonosis via bovine spongiform encephalopathy (BSE)-contamination of human food). The main causes of iatrogenic CJD are cadaveric-derived human growth hormone treatment and dura mater surgical grafts. The PRNP-129 polymorphism has important effects on iatrogenic infection, including overall susceptibility and incubation period. vCJD, resulting from dietary exposure to BSE, has affected mostly the United Kingdom, followed by France. All tested cases were originally PRNP-129MM, although two MV cases have been identified recently (one possible; one definite). vCJD has been secondarily transmitted via blood transfusion and a blood product. There is continuing concern over secondary transmission since there is evidence-from lymphoreticular tissue studies-of extensive subclinical infection in the UK general population, although a further recent study has caused uncertainty over the significance of the previous studies. While definitive diagnosis of CJD is pathological, recent developments in protein amplification and detection have led to significantly better clinical diagnosis.

A case cluster of variant Creutzfeldt-Jakob disease linked to the Kingdom of Saudi Arabia

As of mid-2016, 231 cases of variant Creutzfeldt-Jakob disease-the human form of a prion disease of cattle, bovine spongiform encephalopathy-have been reported from 12 countries. With few exceptions, the affected individuals had histories of extended residence in the UK or other Western European countries during the period (1980-96) of maximum global risk for human exposure to bovine spongiform encephalopathy. However, the possibility remains that other geographic foci of human infection exist, identification of which may help to foreshadow the future of the epidemic. We report results of a quantitative analysis of country-specific relative risks of infection for three individuals diagnosed with variant Creutzfeldt-Jakob disease in the USA and Canada. All were born and raised in Saudi Arabia, but had histories of residence and travel in other countries. To calculate country-specific relative probabilities of infection, we aligned each patient's life history with published estimates of probability distributions of incubation period and age at infection parameters from a UK cohort of 171 variant Creutzfeldt-Jakob disease cases. The distributions were then partitioned into probability density fractions according to time intervals of the patient's residence and travel history, and the density fractions were combined by country. This calculation was performed for incubation period alone, age at infection alone, and jointly for incubation and age at infection. Country-specific fractions were normalized either to the total density between the individual's dates of birth and symptom onset ('lifetime'), or to that between 1980 and 1996, for a total of six combinations of parameter and interval. The country-specific relative probability of infection for Saudi Arabia clearly ranked highest under each of the six combinations of parameter × interval for Patients 1 and 2, with values ranging from 0.572 to 0.998, respectively, for Patient 2 (age at infection × lifetime) and Patient 1 (joint incubation and age at infection × 1980-96). For Patient 3, relative probabilities for Saudi Arabia were not as distinct from those for other countries using the lifetime interval: 0.394, 0.360 and 0.378, respectively, for incubation period, age at infection and jointly for incubation and age at infection. However, for this patient Saudi Arabia clearly ranked highest within the 1980-96 period: 0.859, 0.871 and 0.865, respectively, for incubation period, age at infection and jointly for incubation and age at infection. These findings support the hypothesis that human infection with bovine spongiform encephalopathy occurred in Saudi Arabia.

[Human prion diseases in the Czech Republic]

Human prion diseases are a group of very rare diseases with a unique pathogenesis and, due to an inauspicious prognosis and unavailability of therapy, with fatal consequences. The etiopathogenetic background is the presence of pathologically misfolded prion protein, highly resistant to denaturation, the aggregation and presence of which in the brain tissue causes irreversible neuronal damage. The most frequent prion disease in humans is Creutzfeldt-Jakob disease (CJD) which occurs in sporadic, hereditary/familial, or acquired/infectious/iatrogenic forms. A new form of CJD, variant CJD, is considered to be linked to dietary exposure to beef products from cattle infected with bovine spongiform encephalopathy (BSE) and to infection via blood transfusion. The clinical picture of these diseases is characterized by a rapidly progressing dementia, cerebellar and extrapyramidal symptoms, and rather specific MRI, EEG, and CSF findings. Clinically, the diagnosis is described as possible or probable prion disease and needs to be confirmed by neuropathological or immunological investigation of the brain tissue. Epidemiological data from the Czech Republic spanning the last decade are presented.

Distinct origins of dura mater graft-associated Creutzfeldt-Jakob disease: past and future problems

Dura mater graft-associated Creutzfeldt-Jakob disease (dCJD) can be divided into two subgroups that exhibit distinct clinical and neuropathological features, with the majority represented by a non-plaque-type of dCJD (np-dCJD) and the minority by a plaque-type of dCJD (p-dCJD). The two distinct phenotypes of dCJD had been considered to be unrelated to the genotype (methionine, M or valine, V) at polymorphic codon 129 of the PRNP gene or type (type 1 or type 2) of abnormal isoform of prion protein (PrPSc) in the brain, while these are major determinants of clinicopathological phenotypes of sporadic CJD (sCJD). The reason for the existence of two distinct subgroups in dCJD had remained elusive. Recent progress in research of the pathogenesis of dCJD has revealed that two distinct subgroups of dCJD are caused by infection with different PrPSc strains from sCJD, i.e., np-dCJD caused by infection with sCJD-MM1/MV1, and p-dCJD caused by infection with sCJD-VV2 or -MV2. These studies have also revealed previously unrecognized problems as follows: (i) the numbers of p-dCJD patients may increase in the future, (ii) the potential risks of secondary infection from dCJD, particularly from p-dCJD, may be considerable, and (iii) the effectiveness of the current PrPSc decontamination procedures against the PrPSc from p-dCJD is uncertain. To prevent secondary infection from p-dCJD, the establishment of effective decontamination procedures is an urgent issue. In this review, we summarize the past and future problems surrounding dCJD.

Advances in screening test development for transmissible spongiform encephalopathies

The blood of patients with transmissible spongiform encephalopathy or prion disease can no longer be considered free of infectivity. There have been two recent reports of highly probable transfusion-associated iatrogenic variant Creutzfeldt-Jakob disease infections, and there is supporting experimental evidence of scrapie transmission by the transfusion of blood from sheep with naturally occurring disease. In the absence of a preclinical diagnostic test for transmissible spongiform encephalopathy, the main precautionary measures undertaken by blood agencies employ donor exclusion criteria, ensuring that the number of any further iatrogenic cases will be small. The development of a sensitive, specific and reliable diagnostic test is urgently needed for early identification of infected individuals in order to ensure the safety of blood supplies. During the past 5 years, significant progress has been made in improving the sensitivity and specificity of tests using brain and lymphoreticular tissues to identify Creutzfeldt-Jakob disease-infected individuals. However, the quest for a blood test is still in its infancy and requires extensive further research.

Consumption of bovine spongiform encephalopathy (BSE) contaminated beef and the risk of variant Creutzfeldt-Jakob disease

To date, the variant Creutzfeldt-Jakob disease (vCJD) risk assessments that have been performed have primarily focused on predicting future vCJD cases in the United Kingdom, which underwent a bovine spongiform encephalopathy (BSE) epidemic between 1980 and 1996. Surveillance of potential BSE cases was also used to assess vCJD risk, especially in other BSE-prevalent EU countries. However, little is known about the vCJD risk for uninfected individuals who accidentally consume BSE-contaminated meat products in or imported from a country with prevalent BSE. In this article, taking into account the biological mechanism of abnormal prion PrP(res) aggregation in the brain, the probability of exposure, and the expected amount of ingested infectivity, we establish a stochastic mean exponential growth model of lifetime exposure through dietary intake. Given the findings that BSE agents behave similarly in humans and macaques, we obtained parameter estimates from experimental macaque data. We then estimated the accumulation of abnormal prions to assess lifetime risk of developing clinical signs of vCJD. Based on the observed number of vCJD cases and the estimated number of exposed individuals during the BSE epidemic period from 1980 to 1996 in the United Kingdom, an exposure threshold hypothesis is proposed. Given the age-specific risk of infection, the hypothesis explains the observations very well from an extreme-value distribution fitting of the estimated BSE infectivity exposure. The current BSE statistics in the United Kingdom are provided as an example.

A case of Creutzfeldt-Jakob disease following cataract surgery: sporadic versus iatrogenic cause

Creutzfeldt-Jakob Disease (CJD) is a fatal neurologic disorder caused by an infectious agent called a human prion protein. CJD can be classified as sporadic CJD, familial CJD, variant CJD, and iatrogenic CJD. We report a 64-year-old man diagnosed with CJD three months after cataract surgery. Although sporadic CJD is the most common type, the patient's cataract surgery elicited the possibility of an iatrogenic transmission. It is important to consider whether visual symptoms are a manifestation of sporadic CJD, rather than cataract surgery resulting in iatrogenic CJD. Preceding cataract surgeries have been reported with CJD, but there is no proven causality. This case highlights consideration of sporadic versus iatrogenic cause when seen in association with cataract surgery.

[Mutant D178N prion protein converts spontaneously in RT-QuIC assay]

OBJECTIVE

To study the conversion of mutant D178N prion protein in RT-QuIC assay.

METHODS

The D178N mutant prion PRNP was generated by the method of single site mutation. The mutant PRNP gene was inserted into plasmids of pET24. The full and N-truncated recombinant human prion proteins were expressed and purified. The fibril formations of these proteins were real-time monitored by the method of RT-QuIC. The ability to resist proteinase K (PK) of these fibrils was analyzed.

RESULTS

We succeed to construct human PrP-D178N plamids. The N-truncated human prion protein with D178N (PrP90-231-D178N) can convert spontaneously in RT-QuIC, while full length of human prion D178N protein (PrP23-231-D178N) fails to convert spontaneously. The spontaneously generated fibril has been domenstrated it is partily PK-resistant.

CONCLUSION

The N-terminal of prion protein (23-90) plays an important role for the D178N mutant protein spontaneously conversion, which provide the clues for study the pathogenesis of genetic CJD.

All clinically-relevant blood components transmit prion disease following a single blood transfusion: a sheep model of vCJD

Variant CJD (vCJD) is an incurable, infectious human disease, likely arising from the consumption of BSE-contaminated meat products. Whilst the epidemic appears to be waning, there is much concern that vCJD infection may be perpetuated in humans by the transfusion of contaminated blood products. Since 2004, several cases of transfusion-associated vCJD transmission have been reported and linked to blood collected from pre-clinically affected donors. Using an animal model in which the disease manifested resembles that of humans affected with vCJD, we examined which blood components used in human medicine are likely to pose the greatest risk of transmitting vCJD via transfusion. We collected two full units of blood from BSE-infected donor animals during the pre-clinical phase of infection. Using methods employed by transfusion services we prepared red cell concentrates, plasma and platelets units (including leucoreduced equivalents). Following transfusion, we showed that all components contain sufficient levels of infectivity to cause disease following only a single transfusion and also that leucoreduction did not prevent disease transmission. These data suggest that all blood components are vectors for prion disease transmission, and highlight the importance of multiple control measures to minimise the risk of human to human transmission of vCJD by blood transfusion.

Possible editing of Alu transcripts in blood cells of sporadic Creutzfeldt-Jakob disease (sCJD)

Editing of RNA molecules gained major interest when coding mRNA was analyzed. A small, noncoding, Alu DNA element transcript that may act as regulatory RNA in cells was examined in this study. Alu DNA element transcription was determined in buffy coat from healthy humans and human sporadic Creutzfeldt-Jakob disease (sCJD) cases. In addition, non-sCJD controls, mostly dementia cases and Alzheimer's disease (AD) cases, were included. The Alu cDNA sequences were aligned to genomic Alu DNA elements by database search. A comparison of best aligned Alu DNA sequences with our RNA/cDNA clones revealed editing by deamination by ADAR (adenosine deaminase acting on RNA) and APOBEC (apolipoprotein B editing complex). Nucleotide exchanges like a G instead of an A or a T instead of a C in our cDNA sequences versus genomic Alu DNA pointed to recent mutations. To confirm this, our Alu cDNA sequences were aligned not only to genomic human Alu DNA but also to the respective genomic DNA of the chimpanzee and rhesus. Enhanced ADAR correlated with A-G exchanges in dementia, AD, and sCJD was noted when compared to healthy controls as well as APOBEC-related C-T exchanges. The APOBEC-related mutations were higher in healthy controls than in cases suffering from neurodegeneration, with the exception of the dementia group with the prion protein gene (PRNP) MV genotype. Hence, this study may be considered the first real-time analysis of Alu DNA element transcripts with regard to editing of the respective Alu transcripts in human blood cells.

Expert elicitation for the judgment of prion disease risk uncertainties

There is a high level of uncertainty surrounding the potential for iatrogenic prion transmission through transplantation, medical instrument reuse, blood transfusion, and blood product use due to a lack of evidence-based research on this important risk issue. A group of specialists was enlisted to evaluate some of the knowledge gaps in this area using the "Classical Model," a structured elicitation procedure for weighting and pooling expert judgment. The elicitation exercise was undertaken in March 2009 with 11 transmissible spongiform encephalopathy (TSE) experts who were first calibrated using a series of seed questions for which the answers are known; they were then asked to answer a number of target questions that are important for risk assessment purposes, but for which there remains high uncertainty at this time. The target questions focused on variant Creutzfeldt-Jakob disease (vCJD) prevalence, incubation times for vCJD, genetic susceptibility to prion disease, blood infectivity, prion reduction of blood and blood products, surgical instrument risks, and interspecies transmission of TSEs. The experts were also asked to perform pairwise risk rankings for 12 different potential routes of infection. Dura mater transplantation was seen as having the highest risk, while dental tissue grafts were viewed as presenting the lowest risk of iatrogenic transmission. The structured elicitation procedure provides a rational, auditable, and repeatable basis for obtaining useful information on prion disease risk issues, for which data are sparse.

Prions: a mystery unravelled?

Prions result in fatal degeneration of the central nervous system (CNS) in the form of diseases known as transmissible spongiform encephalopathies (TSEs). The discovery in 1996 of a new variant of Creutzfeldt-Jakob disease (a human TSE) and experimental confirmation that it is caused by the prion strain responsible for bovine spongiform encephalopathy (BSE) has greatly spurred research in this field. The mechanism underlying prion propagation is now reasonably clear. Prions multiply, in fact, by stimulating their hosts to produce proteins that are initially normal, but acquire an abnormal, prion-like conformation during the coiling stage. A fuller understanding of this mechanism could lead to the employment of molecules capable of making prion proteins revert to the normal conformation in the treatment of both TSEs and other serious CNS disorders.

Molecular pathology of human prion diseases

Prion diseases are fatal neurodegenerative conditions in humans and animals. In this review, we summarize the molecular background of phenotypic variability, relation of prion protein (PrP) to other proteins associated with neurodegenerative diseases, and pathogenesis of neuronal vulnerability. PrP exists in different forms that may be present in both diseased and non-diseased brain, however, abundant disease-associated PrP together with tissue pathology characterizes prion diseases and associates with transmissibility. Prion diseases have different etiological background with distinct pathogenesis and phenotype. Mutations of the prion protein gene are associated with genetic forms. The codon 129 polymorphism in combination with the Western blot pattern of PrP after proteinase K digestion serves as a basis for molecular subtyping of sporadic Creutzfeldt-Jakob disease. Tissue damage may result from several parallel, interacting or subsequent pathways that involve cellular systems associated with synapses, protein processing, oxidative stress, autophagy, and apoptosis.

[Human spongiform encephalopathies in the Netherlands]

Cases of Creutzfeldt Jakob disease (CJD) have been centrally registered in the Netherlands since 1997. Each year about 35 cases are reported. All patients with a possible, probable or definite diagnosis are registered in a European database. Recently, patients with a transfusion-transmitted form of CJD have been diagnosed in the United Kingdom. Such cases have not yet occurred in the Netherlands. It is important to continue to detect and centrally register patients with CJD.

Diffusion weighted imaging in heroin-associated spongiform leukoencephalopathy

BACKGROUND

Heroin-associated spongiform leukoencephalopathy (HASL) is a rare complication of heroin abuse. We report a case that highlights the increased sensitivity of diffusion weighted imaging (DWI) compared with T2-weighted imaging in the acute setting of HASL.

METHODS

Single case report.

RESULTS

A 36-year-old male with a history of heroin abuse (snorting) presented with a 3-day history of lethargy. MRI brain revealed restricted diffusion involving the globus pallidum and cerebral cortex bilaterally that was not seen on fluid-attenuated inversion recovery (FLAIR) images. The patient was diagnosed with acute HASL. Repeated MRI FLAIR at 3 months confirmed the development of atrophy and T2 hyperintensity in the subcortical white matter, consistent with leukoencephalopathy. Neurological exam at 3-month follow-up was nonfocal.

CONCLUSIONS

Restricted diffusion, which likely corresponds to electron microscopic findings of fluid entrapment between the myelin lamellae, may be detectable earlier than changes on FLAIR. Clinicians should be aware of the neuroimaging findings of HASL and the increased sensitivity of MRI DWI over T2-weighted images in detecting HASL acutely.

BSE case associated with prion protein gene mutation

Bovine spongiform encephalopathy (BSE) is a transmissible spongiform encephalopathy (TSE) of cattle and was first detected in 1986 in the United Kingdom. It is the most likely cause of variant Creutzfeldt-Jakob disease (CJD) in humans. The origin of BSE remains an enigma. Here we report an H-type BSE case associated with the novel mutation E211K within the prion protein gene (Prnp). Sequence analysis revealed that the animal with H-type BSE was heterozygous at Prnp nucleotides 631 through 633. An identical pathogenic mutation at the homologous codon position (E200K) in the human Prnp has been described as the most common cause of genetic CJD. This finding represents the first report of a confirmed case of BSE with a potential pathogenic mutation within the bovine Prnp gene. A recent epidemiological study revealed that the K211 allele was not detected in 6062 cattle from commercial beef processing plants and 42 cattle breeds, indicating an extremely low prevalence of the E211K variant (less than 1 in 2000) in cattle.

Bovine spongiform encephalopathy (BSE or Mad Cow Disease), a transmissible spongiform encephalopathy (TSE) or prion disease of cattle, was first discovered in the United Kingdom in 1986. BSE is most likely the cause of a human prion disease known as variant Creutzfeldt Jakob Disease (vCJD). In this study, we identified a novel mutation in the bovine prion protein gene (Prnp), called E211K, of a confirmed BSE positive cow from Alabama, United States of America. This mutation is identical to the E200K pathogenic mutation found in humans with a genetic form of CJD. This finding represents the first report of a confirmed case of BSE with a potential pathogenic mutation within the bovine Prnp gene. We hypothesize that the bovine Prnp E211K mutation most likely has caused BSE in “the approximately 10-year-old cow” carrying the E221K mutation.

[Scrapie of sheep and Creutzfeldt-Jakob disease in Iceland]

OBJECTIVE

Scrapie of sheep and Creutzfeldt-Jakob disease (CJD) are both classified as prion diseases. The infectious agents of both diseases are closely related. The objectives of the study was to explore, whether sheep scrapie could be transmitted to humans and cause CJD.

MATERIAL AND METHODS

The occurrence of CJD was studied in a period of 40 years, 1960 to 2000. The first part of the study, which was started in 1980, was retrospective. Hospital records from the Department of Neurology of the National Hospital from the years 1960-1980 were scrutinised and paraffin blocks from the collection of the Department of Pathology from cases with the diagnosis CJD and some suspect cases were obtained and analysed. The latter part of the study was prospective, which gave the possibility to study codon 129 of PRNP gene and characterise the strain of the infectious agent. Information on the epidemiology of scrapie in Iceland and of the diet of Icelanders was collected.

RESULTS

Four cases of CJD were detected in the 40 years studied, which corresponds to an incidence of 0.44 per million inhabitants, which is less than half the average incidence in 18 other European countries in the years 1997-2004.

CONCLUSION

The low incidence of CJD in Iceland does not indicate that sheep scrapie can be transmitted to humans and cause CJD. If this were the case, we would have expected an higher incidence of CJD and possibly atypical cases, as the Icelandic population has been exposed to scrapie for 130 years.

Ten-year mortality from Creutzfeldt-Jakob disease in Cyprus

We report the mortality from sporadic Creutzfeldt-Jakob disease in Cyprus for a 10-year surveillance period (1995-2004). In that time, 5 cases were identified out of a population of 749,000, giving an incidence of 0.7 cases per million population per year. Our sporadic incidence matches that expected according to global epidemiological surveillance. No cases of variant Creutzfeldt-Jakob disease were found but 1 familial case was diagnosed.

Infective dementias

A wide range of infectious diseases can result in dementia, although the identity and nature of these diseases has changed over time. Two of the most significant current groups in terms of scientific complexity are HIV/AIDS and prion diseases. In these disorders, dementia occurs either as a consequence of targeting the brain and selectively damaging neurones, or by an indirect effect of neuroinflammation. In prion diseases, both direct neurotoxicity and neuroinflammation may act to result in neuronal damage. In HIV encephalitis, the progression of the dementia is slower, perhaps reflecting indirect damage that appears to result from neuroinflammation as a main cause of neuronal death. An ever-increasing range of model systems is now available to study the neuronal damage in infectious dementias, ranging from cell culture systems to animal models, some of which, particularly in the case of prion diseases, are very well characterised and amenable to controlled manipulation in terms of both host and agent parameters. As valuable as these experimental models are, they do not allow a direct approach to an understanding of dementia, the complexities of which cannot readily be studied in vitro or in animal models, but they do allow studies of interventions and therapeutic strategies. This review summarises the current state of knowledge regarding the major infective dementias.

The clinical neurology and epidemiology of Creutzfeldt-Jakob disease, with special reference to iatrogenic cases

The clinical characteristics of Creutzfeldt-Jakob disease (CJD) in a newly analysed group of 223 cases transmitted to primates at the NIH are compared to a recent large series of neuropathologically verified cases in France, and the limited conclusions from worldwide epidemiological studies are briefly summarized. Discussion then focuses on iatrogenic CJD, with special attention to the interplay of clinical, laboratory and epidemiological features of the current outbreak of CJD in hypopituitary dwarfs treated with growth hormone extracted from pools of human pituitary glands.

[Clinical characteristics and laboratory findings in prion diseases]

Acutely progressing dementia, generalized myoclonus, and periodic synchronous discharge (PSD) on EEG are thought to be characteristic features of Creutzfeldt-Jakob disease (CJD). However, recent surveillance studies in European countries and Japan have revealed several uncommon variants that run relatively long clinical course, demonstrate atypical myoclonus, and show no PSD. Brain specific proteins such as 14-3-3 protein, tau protein, and neuron specific enolase (NSE) are detected in the CSF of CJD patients. Clinical features and laboratory findings of sporadic CJD are related well to the combination of polymorphism at codon 129 of prion protein gene(PRNP) (Methionine/Methionine, Methionine/Valine, and Valine/Valine) and type of pathogenic prion protein (type 1 and type 2). Those of genetic prion disease depend on pathogenic mutation in PRNP. Positive rates of PSD and 14-3-3 protein in the CSF differ among subtypes of sporadic CJD and genetic prion diseases. Diffusion-weighted MRI is very useful for an early clinical diagnosis of CJD and some subtypes show their own characteristic findings.

[Acquired Creutzfeldt-Jakob disease (CJD)--Kuru, iatrogenic CJD, variant CJD]

Human prion diseases can be classified as sporadic, hereditary or acquired. The acquired forms are known to be caused by the transmission to human from human or animal, via medical appliances, oral intake or parenteral solutions. Usually, peripheral infection such as oral(Kuru) or parenteral (human pituitary hormones) transmission causes cerebellar degenerative form, and central nervous system infection such as neurosurgical treatment, dura mater grafts or corneal grafts transmission causes clinical features similar to sporadic form of Creutzfeldt-Jakob disease (CJD). The variant CJD (vCJD) is considered to be transmitted bovine spongiform encephalopathy(BSE) to human through dietary exposure. The early clinical features of vCJD are dominated by psychiatric symptoms, and minor number of patients have neurological symptoms from the onset. After about 6 months, there are frank neurological signs, including ataxia, cognitive impairment and involuntary movements.

[Research progress in slow virus infections in Japan and the diagnostic points]

There have been many progresses of researches on slow virus infections including sub-acute sclerosing panencephalitis (SSPE), progressive multifocal leukoencephalopathy (PML) and prion diseases. In Japan, many researches were conducted in relation with the research group on prion disease and slow virus infection sponsored by the Ministry of Health, Welfare and Labor. Particularly in prion disease, the nation-wide surveillance has shown many important epidemiological and clinical results. However the elucidation of pathomechanisms and development of effective treatments of prion disease, SSPE and PML are far from contentment and we the mankind need further efforts to overcome these diseases.

[Prevention of prion disease transmission]

Prion infections lead to fatal diseases of the CNS, including Creutzfeldt-Jakob disease (CJD) in humans, bovine spongiform encephalopathy(BSE) in cows. Iatrogenic CJD which have been transmitted through dura-matter transplantation, administration of pituitary tissue extracts, corneal transplantation, or neurosurgical procedures. There are not thought to be infectious agents in blood of sporadic CJD patients. However three recipients of blood donated by individuals who subsequently developed variant CJD in United Kingdam. We introduce the guideline for CJD infection through medical procedure made in 2003 and arouse attention to risk of blood in variant CJD patients.

Clinical features and diagnosis of dura mater graft-associated Creutzfeldt-Jakob disease

BACKGROUND

A subset of patients with dura mater graft-associated Creutzfeldt-Jakob disease (dCJD) demonstrates atypical clinical features and plaque formation in the brain (plaque type).

OBJECTIVE

To elucidate the frequency and clinical features of plaque type dCJD in comparison with the non-plaque type.

METHODS

We analyzed clinicopathologic findings of 66 patients who had been registered as having dCJD by the Creutzfeldt-Jakob Disease Surveillance Committee, Japan, between April 1999 and February 2006.

RESULTS

1) Analysis of pathologically confirmed dCJD patients (n = 23) demonstrated plaque type dCJD in 11 patients (48%). In contrast to the non-plaque type with classic CJD features, the plaque type commonly presented with ataxic gait as an initial manifestation, relatively slow progression of neurologic symptoms, and no or late occurrence of periodic sharp-wave complexes (PSWCs) on EEG. MRI, especially diffusion-weighted images, and CSF 14-3-3 protein and neuron specific enolase (NSE) showed high diagnostic sensitivities for plaque as well as non-plaque types. 2) Analysis of clinically diagnosed dCJD patients (n = 34) demonstrated that 7 patients (21%) had atypical clinical features without PSWCs, probably corresponding to plaque type dCJD.

CONCLUSION

The frequency of the plaque type in dura mater graft-associated Creutzfeldt-Jakob disease is apparently higher than previously recognized. For the clinical diagnosis of the plaque type dura mater graft-associated Creutzfeldt-Jakob disease, MRI and CSF markers would be useful, in addition to the core features, i.e., onset with ataxic gait disturbance, relatively slow progression, and no or late occurrence of periodic sharp-wave complexes on EEG.

Insights into prion strains and neurotoxicity

Transmissible spongiform encephalopathies (TSEs) are neurodegenerative diseases that are caused by prions and affect humans and many animal species. It is now widely accepted that the infectious agent that causes TSEs is PrP(Sc), an aggregated moiety of the host-derived membrane glycolipoprotein PrP(C). Although PrP(C) is encoded by the host genome, prions themselves encipher many phenotypic TSE variants, known as prion strains. Prion strains are TSE isolates that, after inoculation into distinct hosts, cause disease with consistent characteristics, such as incubation period, distinct patterns of PrP(Sc) distribution and spongiosis and relative severity of the spongiform changes in the brain. The existence of such strains poses a fascinating challenge to prion research.

Selection of spiking materials for studies on the clearance of agents of transmissible spongiform encephalopathy during plasma fractionation

Manufacturers of plasma derivatives are encouraged to perform product-specific investigational studies on the ability of their processes to remove prion agents. Such studies are invariably performed using spiking materials derived from infected brain tissue. However, there is little guidance available on which preparations are suitable and no consensus on the acceptability of resultant data. Further research is required to resolve this question.

Dental treatment and risk of variant CJD--a case control study

OBJECTIVE

Knowledge of risk factors for variant CJD (vCJD) remains limited, but transmission of prion proteins via re-useable medical devices, including dental instruments, or enhanced susceptibility following trauma to the oral cavity is a concern. This study aimed to identify whether previous dental treatment is a risk factor for development of vCJD.

DESIGN

Case control study.

METHODS

Risk factor questionnaires completed by interview with relatives of 130 vCJD patients and with relatives of 66 community and 53 hospital controls were examined by a dental surgeon. Responses regarding dental treatments were analysed.

RESULTS

We did not find a statistically significant excess of risk of vCJD associated with dental treatments with the exception of extractions in an unmatched analysis of vCJD cases with community controls (p = 0.02). However, this result may be explained by multiple testing.

CONCLUSIONS

This is the first published study to date to examine potential links between vCJD and dental treatment. There was no convincing evidence found of an increased risk of variant CJD associated with reported dental treatment. However, the power of the study is restricted by the number of vCJD cases to date and does not preclude the possibility that some cases have resulted from secondary transmission via dental procedures. Due to the limitations of the data available, more detailed analyses of dental records are required to fully exclude the possibility of transmission via dental treatment.

Cells infected with scrapie and Creutzfeldt-Jakob disease agents produce intracellular 25-nm virus-like particles

We had repeatedly found approximately 25-nm-diameter virus-like particles in highly infectious brain fractions with little prion protein (PrP), and therefore we searched for similar virus-like particles in situ in infected cell lines with high titers. Neuroblastoma cells infected with the 22L strain of scrapie as well as hypothalamic GT cells infected with the FU Creutzfeldt-Jakob disease agent, but not parallel mock controls, displayed dense 25-nm virus-like particles in orthogonal arrays. These particles had no relation to abnormal PrP amyloid in situ, nor were they labeled by PrP antibodies that faithfully recognized rough endoplasmic reticulum membranes and amyloid fibrils, the predicted sites of normal and pathological intracellular PrP. Additionally, phorbol ester stimulated the production of abnormal PrP gel bands by >5-fold in infected N2a + 22L cells, yet this did not increase either the number of virus-like arrays or the infectious titer of these cells. Thus, the 25-nm infection-associated particles could not be prions. Synaptic differentiation and neurodegeneration, as well as retroviruses that populate the rough endoplasmic reticulum of neuroblastoma cells, were not required for particle production. The 25-nm particle arrays in cultured cells strongly resembled those first described in 1968 in synaptic regions of scrapie-infected brain and subsequently identified in many natural and experimental TSEs. The high infectivity of comparable, isolated virus-like particles that show no intrinsic PrP by antibody labeling, combined with their loss of infectivity when nucleic acid-protein complexes are disrupted, make it likely that these 25-nm particles are the causal TSE virions that induce late-stage PrP brain pathology.

[Identification of beta-aggregate sites in protein chain]

Studying amyloid diseases (amyloidoses) has been especially actual and has attracted the attention of researchers all over the world in connection with the appearance of epidemic prion diseases such as Bovine Spongiform Encephalopathie in cattle and Creutzfeldt-Jakob in human. Amyloidoses are caused by transition of a "healthy" protein molecule or peptide from a native conformation to a very stable pathologic form: molecules in a pathologic conformation aggregate, that results in the amyloid fibrils which can grow infinitely. Investigation of molecular mechanisms of these diseases and the ability to find protein regions responsible for the appearance of the given diseases is a fundamental problem. Theoretical and experimental studies of amyloid fibril formation are considered in this review.

[A possible influence of nutrient factors in the mechanism development of the neurodegenerative diseases--alzheimerrs disease and sprongiform encelphalopathy with people]

The article presents a review of the literature data, as well as the author's experimental observations concerning the role of nutrient components in the development of neurodegenerative diseases of amyloidal nature. In particular, the role of antioxidants in the prevention of the accumulation of oxidized proteins blocking the chaperone system is discussed. A separate section is devoted to the formation of the large amorphous aggregates on the association of caseins with the precursors of amyloidal structures (amyloidal beta peptidel-42 and recombinant prions). A possible role of nutrient factors in the development of the neurodegenerative diseases is discussed.

[Sleep disorders in prion diseases]

Prion diseases are a group of encephalopathies with neurodegenerative changes caused by an altered protein named prion whose characteristic datum is transmissibility. In most cases they occur in a sporadic form although a group of them are familial associated with mutations in the gene of the prion protein. Genetic polymorphism seems to determine the different family variants. One of the most enigmatic and unusual is Fatal Familial Insomnia (FFI), a hereditary disorder characterised by loss of physiological sleep with oneiric stupor, autonomic and motor hyperactivity, and motor anomalies. The polysomnography of this entity reflects an inability to produce the physiological pattern of NREM and REM sleep, as well as hormonal and vegetative circadian fluctuations; the transition from wakefulness to sleep is markedly altered with the early disappearance sleep spindles. The hypothesis of the origin of these disorders is thalamic neuronal loss, especially in the anterior and dorsomedial nuclei, described in the neuropathology of these patients; besides PET reveals hypofunction of thalamic nuclei, centres responsible for controlling wakefulness-sleep. In Creutzfeldt-Jakob disease the wake-sleep disorders are not considered characteristic; nonetheless, frequent alterations have been found in the electroencephalographic registers of sleep. Besides thalamic neurodegeneration, there could be common etiopathogenic mechanisms in prion diseases in relation to the biological function of the prion protein.