Iatrogenic Creutzfeldt-Jakob disease at the millennium

Alzheimer-type neuropathology in a 28 year old patient with iatrogenic Creutzfeldt-Jakob disease after dural grafting

We report the case of a 28 year old man who had received a cadaverous dura mater graft after a traumatic open skull fracture with tearing of the dura at the age of 5 years. A clinical suspicion of Creutzfeldt-Jakob disease (CJD) was confirmed by a brain biopsy 5 months prior to death and by autopsy, thus warranting the diagnosis of iatrogenic CJD (iCJD) according to WHO criteria. Immunohistochemistry showed widespread cortical depositions of disease associated prion protein (PrP(sc)) in a synaptic pattern, and western blot analysis identified PrP(sc) of type 2A according to Parchi et al. Surprisingly, we found Alzheimer-type senile plaques and cerebral amyloid angiopathy in widespread areas of the brain. Plaque-type and vascular amyloid was immunohistochemically identified as deposits of beta-A4 peptide. CERAD criteria for diagnosis of definite Alzheimer's disease (AD) were met in the absence of neurofibrillar tangles or alpha-synuclein immunoreactive inclusions. There was no family history of AD, CJD, or any other neurological disease, and genetic analysis showed no disease specific mutations of the prion protein, presenilin 1 and 2, or amyloid precursor protein genes. This case represents (a) the iCJD case with the longest incubation time after dural grafting reported so far, (b) the youngest documented patient with concomitant CJD and Alzheimer-type neuropathology to date, (c) the first description of Alzheimer-type changes in iCJD, and (d) the second case of iCJD in Austria. Despite the young patient age, the Alzheimer-type changes may be an incidental finding, possibly related to the childhood trauma.

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.

Variant Creutzfeldt-Jakob disease: risk of transmission by blood transfusion and blood therapies

In the last decade, a new variant of the human prion disease Creutzfeldt-Jakob disease (now known as variant CJD or vCJD) was identified and causally linked to dietary exposure to bovine spongiform encephalopathy (BSE) during the 1980s and early 1990s. Preliminary studies in animal models suggest that prions can be transmitted by blood. Based on two recent reports of iatrogenic vCJD transmission by blood transfusion in humans, a Department of Health-sponsored risk assessment warned that recipients of plasma therapies are now at risk of contracting vCJD from potentially infected donors. It is believed that all the population may be susceptible to vCJD infection, although clinical cases have so far occurred only in methionine homozygotes at codon 129 in the human prion protein gene. A non-invasive blood-based diagnostic assay is urgently needed. Because the incubation period may be upwards of 40 years and there is no reliable screening test, it is currently unknown how many people may be in an asymptomatic phase of vCJD infection in the UK. However, there remains a distinct possibility that some infected patients may never develop clinical symptoms but will remain asymptomatic carriers who can potentially transmit the disease to other individuals. Therefore, screening of infectious individuals will be a critical component for individuals who rely on blood transfusions and/or blood therapies. In the absence of screening tests or effective therapies to treat this disease, a formidable worldwide public health challenge lies ahead to prevent new infections, accurately assess infection rates and treat infected patients.

Rapid method for the sensitive detection of protein contamination on surgical instruments

Hospital sterile service departments (SSDs) currently rely on simple visual confirmation of cleanliness as an assessment of the efficacy of cleaning surgical instruments. The inherent inability to monitor low levels of infectious or proteinaceous contamination on surgical instruments creates the possibility that highly dangerous and robust biological agents may remain infectious and undetected even after standard cleaning and sterilization procedures have been employed. This paper describes the development of a novel microscopy technique, episcopic differential interference contrast microscope, combined with the fluorescent reagent, SYPRO Ruby, to rapidly detect brain tissue protein to below 400 pg/mm(2) on an instrument surface. This technique has displayed a minimum level of detection observed by 50% of volunteers of 85 pg/mm(2) (95% confidence intervals 67-112 pg/mm(2)). Quantitative assessment of instruments supplied from various SSDs enabled the establishment of a 'contamination index' of both proteinaceous and non-proteinaceous deposits on the surface. This new methodology for the assessment of surface contamination is generally applicable and should facilitate future quantitative surveys of instrument contamination in hospitals and other healthcare environments.

Autologous tissues for dural grafting in children: a report of 56 cases

BACKGROUND

Diverse materials have been used for dural closure, including grafts of cadaveric origin. Some 168 cases of Creutzfeldt-Jakob disease have been reported following the implant of human dura mater. A few publications have addressed the use of dural grafts in children, but none has analyzed the feasibility of autologous tissues for this purpose.

AIM

Since 1994, the authors have utilized autologous tissues for dural grafting in children undergoing neurosurgical procedures, aimed at studying the feasibility of its use in this age group.

MATERIAL AND METHODS

We studied 56 children submitted to neurosurgical procedures who underwent an implant of a patch of autologous tissue for dural closure. Epidemiological, clinical, and neuroimaging data were processed using statistical methods.

RESULTS

The study group was composed of 29 boys and 27 girls, with ages ranging from 1 month to 17 years (mean 7.6 years). The procedures corresponded to lesions at the posterior cranial fossa (n = 41), supratentorial cranial compartment (n = 12), and spine (n = 3). Seventy-five percent of the children had no complication. Four patients had adverse effects unrelated to dural grafting, while ten children had complications that might be associated with it. The most frequent complication was pseudomeningocele (n = 6), followed by infection (n = 3) and CSF leak (n = 1). Although hydrocephalus seemed to have an influence on the occurrence of complications, their incidence in patients without hydrocephalus did not differ statistically.

CONCLUSIONS

Autologous grafts of fascia or pericranium can be safely used for dural reconstruction in children. Given the reported complications associated with the use of foreign materials for duraplasty, the authors recommend the use of autologous tissues for dural repair, reserving other types of dural grafts for cases in which its usage is unavoidable.

PrPTSE distribution in a primate model of variant, sporadic, and iatrogenic Creutzfeldt-Jakob disease

Human prion diseases, such as Creutzfeldt-Jakob disease (CJD), are neurodegenerative and fatal. Sporadic CJD (sCJD) can be transmitted between humans through medical procedures involving highly infected organs, such as the central nervous system. However, in variant CJD (vCJD), which is due to human contamination with the bovine spongiform encephalopathy (BSE) agent, lymphoreticular tissue also harbors the transmissible spongiform encephalopathy-associated prion protein (PrP(TSE)), which poses a particularly acute risk for iatrogenic transmission. Two blood transfusion-related cases are already documented. In addition, the recent observation of PrP(TSE) in spleen and muscle in sCJD raised the possibility that peripheral PrP(TSE) is not limited to vCJD cases. We aimed to clarify the peripheral pathogenesis of human TSEs by using a nonhuman primate model which mimics human diseases. A highly sensitive enzyme-linked immunosorbent assay was adapted to the detection of extraneural PrP(TSE). We show that affected organs can be divided into two groups. The first is peripheral organs accumulating large amounts of PrP(TSE), which represent a high risk of iatrogenic transmission. This category comprises only lymphoreticular organs in the vCJD/BSE model. The second is organs with small amounts of PrP(TSE) associated with nervous structures. These are the muscles, adrenal glands, and enteric nervous system in the sporadic, iatrogenic, and variant CJD models. In contrast to the first set of organs, this low level of tissue contamination is not strain restricted and seems to be linked to secondary centrifugal spread of the agent through nerves. It might represent a risk for iatrogenic transmission, formerly underestimated despite previous reports of low rates of transmission from peripheral organs of humans to nonhuman primates (5, 10). This study provides an additional experimental basis for the classification of human organs into different risk categories and a rational re-evaluation of current risk management measures.

Phenotypic variability in human prion diseases

Human prion diseases are rare neurodegenerative disorders that can occur as sporadic, familial or acquired disorders. Within each of these categories there is a wide range of phenotypic variation that is not encountered in other neurodegenerative disorders. The identification of the prion protein and its key role in the pathogenesis of this diverse group of diseases has allowed a fuller understanding of factors that influence disease phenotype. In particular, the naturally occurring polymorphism at codon 129 in the prion protein gene has a major influence on the disease phenotype in sporadic, familial and acquired prion diseases, although the underlying mechanisms remain unclear. Recent technical advances have improved our ability to study the isoforms of the abnormal prion protein in the brain and in other tissues. This has lead to the concept of molecular strain typing, in which different isoforms of the prion protein are proposed to correspond to individual strains of the transmissible agent, each with specific biological properties. In sporadic Creutzfeldt-Jakob disease there are at least six major combinations of codon 129 genotype and prion protein isotype, which appear to relate to distinctive clinical subgroups of this disease. However, these relationships are proving to be more complex than first considered, particularly in cases with more than a single prion protein isotype in the brain. Further work is required to clarify these relationships and to explain the mechanism of neuropathological targeting of specific brain regions, which accounts for the diversity of clinical features within human prion diseases.

Surface Plasmon Resonance Analysis for the Screening of Anti-prion Compounds

The interaction of anti-prion compounds and amyloid binding dyes with a carboxy-terminal domain of prion protein (PrP121-231) was examined using surface plasmon resonance (SPR) and compared with inhibition activities of abnormal PrP formation in scrapie-infected cells. Most examined compounds had affinities for PrP121-231: antimalarials had low affinities, whereas Congo red, phthalocyanine and thioflavin S had high affinities. The SPR binding response correlated with the inhibition activity of abnormal PrP formation. Several drugs were screened using SPR to verify the findings: propranolol was identified as a new anti-prion compound. This fact indicates that drug screenings by this assay are useful.

Managing the risk of transmission of variant Creutzfeldt Jakob disease by blood products

Whereas plasma-derived clotting factor concentrates now have a very good safety record for not being infectious for lipid enveloped viruses, concern has arisen about the possibility that prion diseases might be transmitted by blood products. There is epidemiological evidence that classical sporadic Creutzfeld Jakob disease (CJD) is not transmitted by blood transfusion. There is now good evidence that the abnormal prion associated with variant CJD can be transmitted by transfusion of fresh blood components and infect recipients. To reduce the risk of the pathological prion in the UK infecting recipients of clotting factor concentrates, these are now only manufactured from imported plasma collected from countries where there has not been bovine spongiform encephalopathy (BSE) in cattle and the risk of variant CJD in the population is, therefore, considered negligible. The safety of these concentrates is also enhanced because prion protein is, to an appreciable extent, excluded by the manufacturing process from the final product. To help reduce the chance of prion transmission by fresh blood products, donations are leucodepleted, there is increasing use of imported fresh frozen plasma (especially for treating children) and potential donors, who have been recipients of blood since 1980 (the beginning of the BSE epidemic in cattle) are deferred.

Inactivation of prions by acidic sodium dodecyl sulfate

Prompted by the discovery that prions become protease-sensitive after exposure to branched polyamine dendrimers in acetic acid (AcOH) (S. Supattapone, H. Wille, L. Uyechi, J. Safar, P. Tremblay, F. C. Szoka, F. E. Cohen, S. B. Prusiner, and M. R. Scott, J. Virol. 75:3453-3461, 2001), we investigated the inactivation of prions by sodium dodecyl sulfate (SDS) in weak acid. As judged by sensitivity to proteolytic digestion, the disease-causing prion protein (PrPSc) was denatured at room temperature by SDS at pH values of < or =4.5 or > or =10. Exposure of Sc237 prions in Syrian hamster brain homogenates to 1% SDS and 0.5% AcOH at room temperature resulted in a reduction of prion titer by a factor of ca. 10(7); however, all of the bioassay hamsters eventually developed prion disease. When various concentrations of SDS and AcOH were tested, the duration and temperature of exposure acted synergistically to inactivate both hamster Sc237 prions and human sporadic Creutzfeldt-Jakob disease (sCJD) prions. The inactivation of prions in brain homogenates and those bound to stainless steel wires was evaluated by using bioassays in transgenic mice. sCJD prions were more than 100,000 times more resistant to inactivation than Sc237 prions, demonstrating that inactivation procedures validated on rodent prions cannot be extrapolated to inactivation of human prions. Some procedures that significantly reduced prion titers in brain homogenates had a limited effect on prions bound to the surface of stainless steel wires. Using acidic SDS combined with autoclaving for 15 min, human sCJD prions bound to stainless steel wires were eliminated. Our findings form the basis for a noncorrosive system that is suitable for inactivating prions on surgical instruments, as well as on other medical and dental equipment.

Creutzfeldt-Jakob disease acquired via a dural graft: failure of therapy with quinacrine and chlorpromazine

BACKGROUND

Accidental transmission of Creutzfeldt-Jakob disease (CJD) has been reported after neurosurgical interventions, use of intracerebral electrodes, corneal transplants, and after the administration of human-derived hormones. Acquired CJD has also been documented after dural grafting with tissues of human cadaver origin. At present, quinacrine and chlorpromazine are being investigated for the treatment of sporadic CJD, with the hope of offering an effective treatment of an otherwise fatal disease. Our objective was to report a case of iatrogenic CJD occurring 18 years after the implant of a dural graft of human origin and to inform on the results of the treatment with quinacrine and chlorpromazine.

CASE DESCRIPTION

In 1984, a 46-year-old woman was given a Lyodura graft for decompression of Chiari I malformation and syringomyelia. The patient was diagnosed with CJD in 2002. In view of the scarce options for treatment of CJD and after reviewing the current literature, the patient was treated with quinacrine and chlorpromazine. She showed no clinical improvement and died 6 months after hospital admission. The iatrogenic origin of the disease in this patient is supported by the clinical features, laboratory data, and findings from the brain necropsy.

CONCLUSIONS

Patients who have received a dural graft of cadaveric origin may be at risk for developing CJD after very prolonged incubation periods. Treatment with quinacrine and chlorpromazine for acquired CJD was ineffective in our patient. A clinical trial on the use of antiprion agents is warranted.

Prion diseases

Prion diseases are degenerative disorders of the nervous system caused by transmissible particles that contain a pathogenic isoform of the prion protein, a normal constituent of cell membranes. The most common human prion disease is Creutzfeldt-Jakob disease (CJD). Most cases are sporadic with unknown mode of transmission, 10-15% of cases are inherited, and a small number have been transmitted by medical procedures. The spread of human prion diseases through consumption of infected material has been implicated historically in kuru and recently in variant CJD. Animal prion diseases (scrapie of sheep, transmissible mink encephalopathy, chronic wasting disease of cervids, and bovine spongiform encephalopathy) all seem to be laterally transmitted by contact with infected animals or by consumption of infected feed. The different modes of transmission of different prion diseases, the unpredictable species barriers, the variable distribution of infectivity in tissues, and strain variations found in some diseases all make risk assessment and predictions of future events difficult.

Prions: Who Should Worry about Them?

Prion diseases, also called transmissible spongiform encephalopathies (TSEs), are a family of neurodegenerative disorders affecting both humans and animals. They are caused by the accumulation of an abnormal form of a protein known as prion that results in neuronal death and a characteristic spongiform appearance of the brain tissue. Human prion diseases can be sporadic, acquired or hereditary. Acquired prion diseases have been linked to entering contaminated food into the human food chain, failure to completely disinfect or sterilize contaminated surgical instruments, patients receiving tissues and organs from infected donors, recipients of blood and other biological contaminated products, and potentially to cross infection in dental procedures. At present, there is unfortunately no efficient therapy that can be administered to clinically infected patients with prion diseases. Moreover, there are no simple diagnostic tests that can be used to show the agent of transmissible spongiform encephalopathy during the preclinical phase of the disease. Therefore, to prevent the spread of this emerging infectious agent it is necessary to implement several health control strategies and maintain surveillance for subclinical infections.

Elimination of transmissible spongiform encephalopathy infectivity and decontamination of surgical instruments by using radio-frequency gas-plasma treatment

It has now been established that transmissible spongiform encephalopathy (TSE) infectivity, which is highly resistant to conventional methods of deactivation, can be transmitted iatrogenically by contaminated stainless steel. It is important that new methods are evaluated for effective removal of protein residues from surgical instruments. Here, radio-frequency (RF) gas-plasma treatment was investigated as a method of removing both the protein debris and TSE infectivity. Stainless-steel spheres contaminated with the 263K strain of scrapie and a variety of used surgical instruments, which had been cleaned by a hospital sterile-services department, were examined both before and after treatment by RF gas plasma, using scanning electron microscopy and energy-dispersive X-ray spectroscopic analysis. Transmission of scrapie from the contaminated spheres was examined in hamsters by the peripheral route of infection. RF gas-plasma treatment effectively removed residual organic residues on reprocessed surgical instruments and gross contamination both from orthopaedic blades and from the experimentally contaminated spheres. In vivo testing showed that RF gas-plasma treatment of scrapie-infected spheres eliminated transmission of infectivity. The infectivity of the TSE agent adsorbed on metal spheres could be removed effectively by gas-plasma cleaning with argon/oxygen mixtures. This treatment can effectively remove 'stubborn' residual contamination on surgical instruments.

Transmissible spongiform encephalopathies: Assessment of exposure risk in the histological working environment using GC-MS detection of fatty acids as marker for central nervous tissues

To elucidate the risk of occupational exposure to the agent of transmissible spongiform encephalopathies (TSE) in the histological working environment, we assessed the principal suitability of three analytical methods for the detection of tissues of the central nervous system (CNT). We tested a neuron-specific enolase (NSE) Western blot, a glial fibrillary acidic protein (GFAP) ELISA and the GC-MS detection of some CNT typical fatty acids (FAs): omega9-tetracosenic acid, omega7-tetracosenic acid, lignoceric acid, and cerebronic acid. Histological sample processing (formalin fixation, dehydration, paraffin embedding) affected both of the immunochemical approaches considerably. The NSE Western blot produced negative results without exception. The results for the GFAP ELISA were better but still far too insensitive. Thus, both methods were judged to be unsuitable in their present form without major analytical adjustment. GC-MS sensitivity remained unaffected by the formalin fixation process. Sensitivity was reduced in the course of the final dehydration step using xylene in the histological sample processing. However, this reduction was found to be rather moderate (range 42-59%) when compared to the immunochemical methods. Overall, we judged GC-MS to be a promising analytical approach for the assessment of a potential TSE exposure risk via airborne CNT particles in the histological working environment. All the FAs we tested showed very low but detectable baseline contents. Thus, cut-off values must be used in the present GC-MS approach. The most suitable FA turned out to be omega9-tetracosenic acid due to the greatest difference between its content in histological CNT samples and the respective cut-off value (689:1). Preliminary results by GC-MS monitoring of CNT via omega9-tetracosenic acid (and other FAs) on filters of routinely used vacuum cleaners and on filters after air sampling indicate that the airborne CNT/TSE exposure risk in the histological laboratory is minor if existing at all. However, further in depth studies will have to validate our preliminary findings and assess these results in the light of possible future data on human oral and/or pulmonary TSE susceptibility.

Abnormal prion protein in the retina of the most commonly occurring subtype of sporadic Creutzfeldt-Jakob disease

BACKGROUND

Involvement of the eye has been reported in patients with variant Creutzfeldt-Jakob disease (vCJD), but there is disagreement on whether retinal involvement occurs in sporadic Creutzfeldt-Jakob disease (sCJD).

METHODS

Western blotting, paraffin embedded tissue blotting, and immunohistochemistry were used to test whether the abnormal form of the prion protein (PrPSc) accumulates to detectable levels in the eye in a case of the most common subtype of sCJD (MM1).

RESULTS

Low levels of PrPSc were detectable in the retina, localised to the plexiform layers of the central retina. PrPSc was not detectable in other ocular tissues.

CONCLUSIONS

The abnormal form of the prion protein is present in the retina in the most common sCJD subtype (MM1), albeit at levels lower than those found previously in vCJD and in sCJD of the VV2 subtype.

Blood infectivity, processing and screening tests in transmissible spongiform encephalopathy

Surprising advances have been made in the areas of blood infectivity, infectivity removal and, especially, blood screening tests for transmissible spongiform encephalopathy (TSE) in the past few years. In fact, if anyone as recently as last year had suggested that a screening test for preclinical human infection might be available before the end of 2005, the statement would have been met with smiling disbelief. Nevertheless, it can be confidently predicted that the diagnostic misfolded 'prion' protein (PrP(TSE)) will soon be reliably detectable in blood during the symptomatic phase of disease, and it is highly probable that it will also be detectable in blood from at least a proportion of infected individuals during the preclinical phase of disease.

Molecular neurology of prion disease

Prions are infectious pathogens principally composed of abnormal forms of a protein encoded in the host genome. They cause lethal neurodegenerative conditions including CJD, GSS, and kuru in humans and scrapie and bovine spongiform encephalopathy in domestic animals. Remarkably, distinct strains of prions occur despite absence of an agent-specific genome: misfolded proteins themselves may encode strain diversity--with wide implications in biology. The arrival of variant CJD, and the experimental confirmation that it is caused by infection with BSE-like prions, has focussed research on early diagnosis and treatment. Recent advances lead to considerable optimism that effective human therapies may now be developed. While several drugs have been tried in small numbers of patients, there is no clear evidence of efficacy of any agent and controlled clinical trials are urgently needed. Importantly, there is increasing recognition that fundamental processes involved in prion propagation--seeded aggregation of misfolded host proteins--are of far wider significance, not least in understanding the commoner neurodegenerative diseases that pose such a major and increasing challenge for healthcare in an ageing population.

High incidence of scrapie induced by repeated injections of subinfectious prion doses

To clarify the mechanisms leading to the development of Creutzfeldt-Jakob disease in some recipients of pituitary-derived human growth hormone (hGH), we investigated the effects of repeated injections of low prion doses in mice. The injections were performed, as in hGH-treated children, by a peripheral route at short intervals and for an extended period. Twelve groups of 24 mice were intraperitoneally inoculated one, two, or five times per week for 200 days with 2 x 10(-5) to 2 x 10(-8) dilutions of brain homogenate containing the mouse-adapted C506M3 scrapie strain. Sixteen control mice were injected once a week for 200 days with a 2 x 10(-4) dilution of normal brain homogenate. Of mice injected in a single challenge with a scrapie inoculum of a 2 x 10(-4), 2 x 10(-5), or 2 x 10(-6) dilution, 2/10, 1/10, and 0/10 animals developed scrapie, respectively. Control mice remained healthy. One hundred thirty-five of 135 mice injected with repeated prion doses of a 2 x 10(-5) or 2 x 10(-6) dilution succumbed to scrapie. Of mice injected with repeated scrapie doses of a 2 x 10(-7) or 2 x 10(-8) dilution, 52/59 and 38/67 animals died of scrapie, respectively. A high incidence of scrapie was observed in mice receiving repeated doses at low infectivity, whereas there was no disease in mice that were injected once with the same doses. Repeated injections of low prion doses thus constitute a risk for development of prion disease even if the same total dose inoculated in a single challenge does not induce the disease.

Propionibacterium infection associated with bovine pericardium dural allograft

Propionibacteria are known to play a part in postneurosurgical infections, primarily those involving ventricular shunts. Nevertheless, little is known about the association between dural allografts and propionibacterium infections. Two patients underwent craniotomy for supratentorial meningiomas and each received a dural allograft. Both patients subsequently presented with delayed epidural fluid collections several weeks after surgery. Propionibacterium species was cultured in samples from both patients. The allografts were removed and the patients were treated with appropriate antibiotic agents; one patient underwent an interval craniectomy. Both patients demonstrated neuroimaging and clinical improvement after surgery and antiobiotic therapy. These cases demonstrate the association of propionibacterium infections with dural allografts. Furthermore, in patients with latent and indolent infections, Propionibacterium spp. should be suspected and treated appropriately.

Consensus statement on the bio-safety of urinary-derived gonadotrophins with respect to Creutzfeldt–Jakob disease

Human transmissible spongiform encephalopathies (TSE) encompass a group of rare neurodegenerative diseases. In April 2004, a group of international experts and regulators met in Buenos Aires, Argentina, to review the safety and to reach consensus on the use of urinary-derived gonadotrophins with respect to TSE. Iatrogenic transmission of Creutzfeldt-Jakob Disease (CJD) from pituitary-derived gonadotrophins has been reported, no infectivity in urine has been demonstrated, and no definite cases of transmission via urine have been reported. It is currently not possible to monitor donor urine or finished product for the presence of prions. Therefore the assessment of risk has to be based on the likelihood of infection in urine, the source of the urine, and the capacity of the manufacturing process to remove any adventitious infection. Urine for the production of medicinal products should be obtained from sources that minimize the possible presence of materials derived from subjects suffering from human TSE. As no strong evidence for TSE infectivity in urine exists, it can be concluded that the risk of disease-generating prions and TSE infectivity being present in donor urine is low. Current evidence indicates that, with respect to the risk of TSE infection, urinary-derived gonadotrophins appear to be safe.

The public health impact of prion diseases

Several prion disease-related human health risks from an exogenous source can be identified in the United States, including the iatrogenic transmission of Creutzfeldt-Jakob disease (CJD), the possible occurrence of variant CJD (vCJD), and potential zoonotic transmission of chronic wasting disease (CWD). Although cross-species transmission of prion diseases seems to be limited by an apparent "species barrier," the occurrence of bovine spongiform encephalopathy (BSE) and its transmission to humans indicate that animal prion diseases can pose a significant public health risk. Recent reports of secondary person-to-person spread of vCJD via blood products and detection of vCJD transmission in a patient heterozygous at codon 129 further illustrate the potential public health impacts of BSE.

[Hospital practice and prion risks]

Procedures applicable in France for the prevention of prion diseases were first implemented in 1995, resulting from the threat of an epidemic extension of Creutzfeldt-Jakob Disease (CJD) following contamination resulting from the use of extracted growth hormone. It was found later that the bovine disease could infect humans via foodstuffs, and the human variant of the disease (v-CJD) transmissible through lymphoid formations was described in 1996. This led to generalizing precautions to a larger number of medical interventions, taking into account the risk for a population more broadly exposed to contamination. The principles for managing these new risks are described, as well for the use of medical devices or in patient as pathology laboratories.

The population distribution of the Met allele at the PRNP129 polymorphism (a high risk factor for Creutzfeldt-Jakob disease) in various regions of France and in West Europe

The present study has been conducted to ascertain the level of allelic variation at codon 129 of the prion protein gene in France. Six French populations have been studied (Paris, Lille, Rennes, Chambéry, Grasse and Perpignan), totalling 1374 normal subjects. Mean heterozygosity in France is 46.5%, and the mean Met 129 allele (a high risk susceptibility factor for Creutzfeldt-Jakob disease) is 0.674. There is a genetic heterogeneity (chi(2)=38.44, p<0.001) between the six populations compared, and Met allele frequencies are inversely correlated with latitude (r=-0.93, p<0.01). Such an inverse correlation with latitude (r=-0.78, p=0.01) is also found when Met allele frequencies in France are compared to those already published in five other European countries and in Turkey. We hypothesise that high Met 129 frequencies populations may be at higher risk for Creutzfeldt-Jakob disease.

Improved infection control in the prevention of variant Creutzfeldt-Jakob disease in Australia: costs and benefits

OBJECTIVE

To evaluate the costs and benefits of infection control strategies to prevent the transmission of variant Creutzfeldt-Jakob disease (vCJD) in ophthalmic surgery in Australia.

METHODS

The reduction in the risk of iatrogenic transmission of vCJD from feasible infection control strategies was calculated using decision analytic models. A static model calculated the direct secondary transmission for surgical eye procedures, and a simple dynamic model estimated the change in the risk of a subsequent sustained epidemic over the longer term. The expected number of vCJD infections, their cost of care and years of life lost and the estimated cost of strategies included the direct costs of infection control measures were calculated taking a health system perspective.

RESULTS

The dynamic model (Markov process) predicted that from a hypothetical pool of as many as 100 primary vCJD cases there would be less than five iatrogenic infections in the next 30 years. If there are fewer than five primary cases the model predicted no secondary cases of vCJD. The costs of providing care for a vCJD case is estimated to be about $50,000, subject to considerable uncertainty. The minimum cost for using a partial infection control strategy to prevent an iatrogenic infection is likely to be in the order of several millions of dollars.

CONCLUSIONS

Substantial public health investment would need to be made in order to reduce a low risk of iatrogenic transmission of vCJD. Given the likely number of cases of iatrogenic infection, and the order of magnitude of the costs of caring for cases of vCJD, it may be difficult to justify the high cost of risk reduction strategies.

Tissue classification for the epidemiological assessment of surgical transmission of sporadic Creutzfeldt-Jakob disease. A proposal on hypothetical risk levels

Background

Epidemiological studies on the potential role of surgery in Creutzfeldt-Jakob Disease transmission have disclosed associations with history of specific surgical interventions or reported negative results.

Methods

Within the context of a case-control study designed to address surgical risk of sporadic Creutzfeldt-Jakob Disease in Nordic European countries (EUROSURGYCJD Project), a strategy was adopted to categorise reported surgical procedures in terms of potential risk of Creutzfeldt-Jakob Disease acquisition. We took into account elements of biological plausibility, either clinically or experimentally demonstrated, such as tissue infectivity, PrP expression content or successful route of infection.

Results

We propose a classification of exposed tissues and anatomic structures, drawn up on the basis of their specific putative role as entry site for prion transmission through contact with surgical instruments that are not fully decontaminated.

Conclusions

This classification can serve as a reference, both in our study and in further epidemiological research, for categorisation of surgical procedures in terms of risk level of Creutzfeldt-Jakob Disease acquisition.

Dementia associated with infectious diseases

At the turn of the last century, infectious diseases represented an important cause of health morbidity and behavioral changes. Neurosyphilis, for example, was relatively common at the time and often led to the development of cognitive impairment and dementia. With the advent of effective antibiotic treatment, the association between infectious diseases and dementia became increasingly less frequent, although a resurgence of interest in this area has taken place during the past 15 years with the emergence of acquired immunodeficiency syndrome (AIDS) and variant Creutzfeldt-Jakob disease (vCJD). This paper reviews the most frequent infectious causes of dementia, including prion diseases, as well as infections caused by herpes virus, human immunodeficiency virus (HIV), toxoplasmosis, cryptococcus, cytomegalovirus, syphilis, borrelia and cysticercosis.

Collagen matrix (DuraGen) in dural repair: analysis of a new modified technique

STUDY DESIGN

Retrospective review of 110 patients undergoing spinal dural repair and regeneration using an onlay, suture-free, 3-dimensional-collagen matrix graft (DuraGen) over an 8-year period (1995-2003).

OBJECTIVES

Technique appraisal of collagen matrix to repair spinal dura following incidental durotomy, spinal tumor surgery, and trauma.

SUMMARY OF BACKGROUND DATA

Traditional methods of spinal dural repair following incidental durotomy involve tedious attempts at primary watertight suture with a 5% to 10% failure rate. Dural injury occurs after trauma, or dural excision may be required after tumor resection. Collagen matrix is a newer development in collagen sponge.

METHODS

The clinical and demographic data included diagnosis, type and site of surgery, infection risk, size of defect, use of lumbar drains, closed suction subfascial drains, and adverse events. The primary endpoints of graft failure were cerebrospinal fluid leak and pseudomeningocele formation. Neurosurgical wound infection rates were determined.

RESULTS

Collagen matrix was used (n = 110) in the following conditions: degenerative (69), pseudomeningocele formation repair (4), tumors (14), trauma (13), and congenital (5). There were 15 cervical (10 anterior), 21 thoracic (3 anterior), and 71 lumbar (all posterior) surgeries. Fibrin glue was used in 7.3%, subfascial drains in 82%, and lumbar drainage in 2.7%. Overall, cerebrospinal fluid leaks occurred in 2.7%. The 2 pseudomeningocele formations (3.2%) resolved at 3 months. There were 2 wound infections. In the subgroup with incidental durotomy (n = 69), failure of cerebrospinal fluid containment occurred in 4.3% [1 cerebrospinal fluid leak (1.4%), 2 pseudomeningocele formations (2.9%)].

CONCLUSIONS

Collagen matrix was successful in cerebrospinal fluid containment in > 95% of patients requiring dural repair following anterior and posterior spinal surgery. Subfascial drains were safe. Routine lumbar drains are not required but are recommended for repair of established pseudomeningocele formations.

Therapeutic approaches in treating Creutzfeldt-Jakob disease - what does the future hold?

Creutzfeldt-Jakob disease (CJD) is one of the human prion disorders. It has a rapid disease course and is invariably fatal. Currently, no therapy is available. The causative agent is thought to be the prion protein, which acquires a pathological isoform through a conformational change and is hardly degradable. Experimental research has identified several substances, which were able to modestly inhibit the formation and propagation of pathological prion configurations. However, these substances were only effective when administered around the time of inoculation with the pathological prion. This review discusses the possibilities and limitations encountered in the development of pharmacotherapeutics for CJD.

Creutzfeldt-Jakob Disease and Cadaveric Dura Mater Grafts in Japan: An Updated Analysis of Incubation Time

The incubation time for 76 patients with cadaveric dura mater-transmitted Creutzfeldt-Jakob disease reported in Japan by November 2001 was analyzed to clarify its distributional feature and the risk factors which affect the earlier onset of the disease. Cluster analysis indicated that cases could be divided into 3 clusters with respect to the incubation time, i.e., short (1.4-6.2 years), medium (7.0-11.9 years) and long (12.9-17.6 years). The incubation time in females was significantly shorter than those in males. Patients who were transplanted dura mater for facial spasms had a significantly shorter incubation time than those who received transplantation for other diseases including meningioma, aneurysm, or acoustic schwannoma. These results suggest that some host factors may have an influence on the incubation time of the disease.

Decontamination of surgical instruments from prion proteins: in vitro studies on the detachment, destabilization and degradation of PrPSc bound to steel surfaces

Effective reprocessing of surgical instruments ensuring elimination of inadvertent contamination with infectious agents causing transmissible spongiform encephalopathies (TSEs) is essential for the prevention of iatrogenic transmission of Creutzfeldt-Jakob disease (CJD) or its new variant (vCJD) from asymptomatic carriers. In a search for effective yet instrument-friendly and routinely applicable reprocessing procedures, we used an in vitro carrier assay to assess the decontamination activity exerted by different reagents on pathological prion protein (PrP(Sc)), the biochemical marker for TSE infectivity, attached to steel surfaces. In this assay, steel wires were contaminated with 263K scrapie brain homogenate and reprocessed for decontamination by exposure to several different test reagents. Residual contamination with PrP(Sc) and its protease-resistant core PrP27-30, still present after reprocessing on the wire surface or in the cleaning solution, was monitored by sensitive Western blot detection without or after proteinase K digestion. Using this approach, various reagents and processing conditions were screened for both their efficacy of decontamination and their active principles, such as detachment, destabilization or degradation of surface-bound prion protein. This revealed that, under appropriate conditions, relatively mild reagents such as 0.2 % SDS/0.3 % NaOH (pH 12.8), a commercially available alkaline cleaner (pH 11.9-12.2), a disinfectant containing 0.2 % peracetic acid and low concentrations of NaOH (pH 8.9) or 5 % SDS (pH 7.1) exert potent decontaminating activities on PrP(Sc)/PrP27-30 attached to steel surfaces. For in vivo validation, wires reprocessed in these reagents have been implanted into reporter animals in ongoing experiments.

Proceedings of a consensus conference: the screening of blood donors for variant CJD

Since the identification, in 1996, of the first case of variant Creutzfeldt-Jakob disease (vCJD) in humans various approaches have been implemented and/or proposed to prevent this disease from being transfusion transmitted. In addition, a variety of possible laboratory-based approaches have been developed and will continue to be developed for the vCJD screening of blood donors. Various issues related to the implementation of such vCJD testing is likely to assume greater importance as diagnostic tests for vCJD becomes available for the potential screening of blood donors. The purpose of this Consensus Conference was to bring together international experts in an effort to determine which principles should guide the introduction of such testing. These experts provided the scientific and biological background of bovine spongiform encephalopathy (BSE) and vCJD, an understanding of their current epidemiology, as well as the ethical and legal issues that would impact on the implementation of a screening test for preventing the transfusion transmission of vCJD. This contentious issue is of potential considerable importance to transfusion medicine personnel worldwide, as well as to future recipients of allogeneic blood components.

Diagnosing prion diseases: needs, challenges and hopes

Prion diseases are among the most intriguing infectious diseases and are associated with unconventional proteinaceous infectious agents known as prions. Prions seem to lack nucleic acid and propagate by transmission of protein misfolding. The nature of prions and their unique mode of transmission present challenges for early diagnosis of prion diseases. In this article, state-of-the-art prion diagnostic techniques, together with the new strategies that are being used to develop sensitive, early and non-invasive diagnoses for these diseases are reviewed.

Variant Creutzfeldt-Jakob disease: risk of transmission by blood and blood products

Variant Creutzfeldt-Jakob disease (CJD) is a novel acquired human prion disease apparently resulting from exposure to the bovine spongiform encephalopathy (BSE) agent. Variant CJD differs from other human prion diseases in that the disease-associated form of the prion protein and infectivity are readily detectable in lymphoid tissues throughout the body. Lymphoid tissues and lymphocytes are implicated in the peripheral pathogenesis of prion diseases (where infectivity may be detected during the preclinical phase of the illness), giving rise to concerns that blood and blood products may also contain infectious particles, representing a possible source of iatrogenic spread of variant CJD. This concern has been reinforced following the experimental transmission of BSE in a sheep model by transfusion of blood and buffy coat from animals in the preclinical phase of the illness, and the recent identification of a UK case of variant CJD in a patient who had received packed red blood cells that had been donated by an individual who subsequently died from variant CJD. Studies in animal models suggest that most prion infectivity in blood may be cell-associated, with lower levels in the plasma, and there is evidence to suggest that any infectivity present may be reduced during the process of plasma fractionation. However, the possibility that plasma or blood products could transmit the disease cannot be excluded. Further studies are required to develop more sensitive means to detect disease-associated prion protein in blood; such techniques could be employed for screening purposes to reduce exposure to contaminated products and to assist with risk management in potentially exposed individuals.

Prion diseases: Update on mad cow disease, variant creutzfeldt-jakob disease, and the transmissible spongiform encephalopathies

Transmissible spongiform encephalopathies (TSEs) are a group of progressive, fatal neurodegenerative disorders that share a common spongiform histopathology. TSEs may be transmitted in a sporadic, familial, iatrogenic, or zoonotic fashion. The putative infectious agent of TSE, the prion, represents a novel paradigm of infectious disease with disease transmission in the absence of nucleic acid. Several small but spectacular epidemics of TSEs in man have prompted widespread public health and food safety concerns. Although TSEs affect a comparatively small number of individuals, prion research has revealed fascinating insights of direct relevance to common illnesses. This paper reviews recent advances that have shed new light on the nature of prions and TSEs.

Treatment of transmissible spongiform encephalopathy by intraventricular drug infusion in animal models

The therapeutic efficacy of direct drug infusion into the brain, the target organ of transmissible spongiform encephalopathies, was assessed in transgenic mice intracerebrally infected with 263K scrapie agent. Pentosan polysulfate (PPS) gave the most dramatic prolongation of the incubation period, and amphotericin B had intermediate effects, but antimalarial drugs such as quinacrine gave no significant prolongation. Treatment with the highest dose of PPS at an early or late stage of the infection prolonged the incubation time by 2.4 or 1.7 times that of the control mice, respectively. PPS infusion decreased not only abnormal prion protein deposition but also neurodegenerative changes and infectivity. These alterations were observed within the brain hemisphere fitted with an intraventricular infusion cannula but not within the contralateral hemisphere, even at the terminal disease stage long after the infusion had ended. Therapeutic effects of PPS were also demonstrated in mice infected with either RML agent or Fukuoka-1 agent. However, at doses higher than that providing the maximal effects, intraventricular PPS infusion caused adverse effects such as hematoma formation in the experimental animals. These findings indicate that intraventricular PPS infusion might be useful for the treatment of transmissible spongiform encephalopathies in humans, providing that the therapeutic dosage is carefully evaluated.

Young onset dementia

Young onset dementia is a challenging clinical problem with potentially devastating medical and social consequences. The differential diagnosis is wide, and includes a number of rare sporadic and hereditary diseases. However, accurate diagnosis is often possible, and all patients should be thoroughly investigated to identify treatable processes. This review presents an approach to the diagnosis, investigation, and management of patients with young onset dementia, with particular reference to common and treatable causes.

Long-term mortality in the United States cohort of pituitary-derived growth hormone recipients

OBJECTIVE

Patients who received pituitary-derived growth hormone (GH) are at excess risk of mortality from Creutzfeldt-Jakob disease. We investigated whether they were at increased risk of death from other conditions, particularly preventable conditions.

STUDY DESIGN

A cohort (N=6107) from known US pituitary-derived GH recipients (treated 1963-1985) was studied. Deaths were identified by reports from physicians and parents and the National Death Index. Rates were compared with the expected rates for the US population standardized for race, age, and sex.

RESULTS

There were 433 deaths versus 114 expected (relative risk [RR], 3.8; 95% confidence interval [CI], 3.4-4.2; P<.0001) from 1963 through 1996. Risk was increased in subjects with GH deficiency caused by any tumor (RR, 10.4; 95% CI, 9.1-12.0; P<.0001). Surprisingly, subjects with hypoglycemia treated within the first 6 months of life were at extremely high risk (RR, 18.3; 95% CI, 9.2-32.8; P<.0001), as were all subjects with adrenal insufficiency (RR, 7.1; 95% CI, 6.2-8.2; P<.0001). A quarter of all deaths were sudden and unexpected. Of the 26 cases of Creutzfeldt-Jakob disease, four cases have died since 2000.

CONCLUSIONS

The death rate in pituitary-derived GH recipients was almost four times the expected rate. Replacing pituitary-derived GH with recombinant GH has eliminated only the risk of Creutzfeldt-Jakob disease. Hypoglycemia and adrenal insufficiency accounted for far more mortality than Creutzfeldt-Jakob disease. The large number of potentially preventable deaths in patients with adrenal insufficiency and hypoglycemia underscores the importance of early intervention when infection occurs in patients with adrenal insufficiency, and aggressive treatment of panhypopituitarism.

Lyodura use and the risk of iatrogenic Creutzfeldt-Jakob disease in Australia

Although infectiousness is a feature of Creutzfeldt-Jakob disease (CJD), only a small proportion of cases are linked to transmission through healthcare provision. As of January 2003, over 120 cases of CJD associated with use of human cadaveric dura mater had been recognised worldwide; almost all were associated with the commercial product Lyodura. Most cases (97) have occurred in Japan, giving an overall risk estimate of around 1 per 2268 patients treated with Lyodura (0.04%) in that country. In Australia, five cases of CJD have so far been linked to Lyodura, but, given the protracted tails of previous epidemics of transmissible spongiform encephalopathies, further cases are possible. Results of surveys of Lyodura use in Australia are incomplete, but information from the manufacturer suggests that 2208-2478 sheets of Lyodura may have been used here. This use translates to a relatively high incidence of Lyodura-associated CJD, with current overall rates appearing around five times higher than those reported in Japan; reasons for this difference are unclear.

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.

Quinoline derivatives are therapeutic candidates for transmissible spongiform encephalopathies

We previously reported that quinacrine inhibited the formation of an abnormal prion protein (PrPres), a key molecule in the pathogenesis of transmissible spongiform encephalopathy, or prion disease, in scrapie-infected neuroblastoma cells. To elucidate the structural aspects of its inhibiting action, various chemicals with a quinoline ring were screened in the present study. Assays of the scrapie-infected neuroblastoma cells revealed that chemicals with a side chain containing a quinuclidine ring at the 4 position of a quinoline ring (represented by quinine) inhibited the PrPres formation at a 50% inhibitory dose ranging from 10(-1) to 10(1) micro M. On the other hand, chemicals with a side chain at the 2 position of a quinoline ring (represented by 2,2'-biquinoline) more effectively inhibited the PrPres formation at a 50% inhibitory dose ranging from 10(-3) to 10(-1) micro M. A metabolic labeling study revealed that the action of quinine or biquinoline was not due to any alteration in the biosynthesis or turnover of normal prion protein, whereas surface plasmon resonance analysis showed a strong binding affinity of biquinoline with a recombinant prion protein. In vivo studies revealed that 4-week intraventricular infusion of quinine or biquinoline was effective in prolonging the incubation period in experimental mouse models of intracerebral infection. The findings suggest that quinoline derivatives with a nitrogen-containing side chain have the potential of both inhibiting PrPres formation in vitro and prolonging the incubation period of infected animals. These chemicals are new candidates for therapeutic drugs for use in the treatment of transmissible spongiform encephalopathies.

Possible transmission of variant Creutzfeldt-Jakob disease by blood transfusion

BACKGROUND

Variant Creutzfeldt-Jakob disease (vCJD) is a novel human prion disease caused by infection with the agent of bovine spongiform encephalopathy (BSE). Epidemiological evidence does not suggest that sporadic CJD is transmitted from person to person via blood transfusion, but this evidence may not apply to vCJD. We aimed to identify whether vCJD is transmissible through blood transfusion.

METHODS

The national CJD surveillance unit reported all cases of probable or definite vCJD to the UK blood services, which searched for donation records at blood centres and hospitals. Information on named recipients and donors was provided to the surveillance unit to establish if any matches existed between recipients or donors and the database of cases of vCJD. Recipients were also flagged at the UK Office of National Statistics to establish date and cause of death.

FINDINGS

48 individuals were identified as having received a labile blood component from a total of 15 donors who later became vCJD cases and appeared on the surveillance unit's register. One of these recipients was identified as developing symptoms of vCJD 6.5 years after receiving a transfusion of red cells donated by an individual 3.5 years before the donor developed symptoms of vCJD.

INTERPRETATION

Our findings raise the possibility that this infection was transfusion transmitted. Infection in the recipient could have been due to past dietary exposure to the BSE agent. However, the age of the patient was well beyond that of most vCJD cases, and the chance of observing a case of vCJD in a recipient in the absence of transfusion transmitted infection is about 1 in 15000 to 1 in 30000.