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Paul Brown

Publications and source records attributed to Paul Brown.

At least 37 records · Page 2Linked to original sources

Working with transmissible spongiform encephalopathy agents.

The family of illnesses called transmissible spongiform encephalopathies (TSEs), or "prion" diseases, is composed of a small number of human and animal neurodegenerative diseases caused by unique pathogenic agents that are still not fully defined. They are best considered as "protein-misfolding diseases" (together with Alzheimer's disease, Parkinson's disease, and a few other rare examples) resulting from the conversion of a normal body protein into a misfolded amyloid multimer. The pathogenic agents display a unique resistance to conventional disinfection methods and an extraordinary environmental durability, which has led the US Department of Agriculture to designate the causative agent of bovine spongiform encephalopathy as a bioterrorism security threat. In this review, precautions and regulations concerning the handling of TSE agents are discussed in relation to personnel and environmental biosafety.

Animals↗

Removal of exogenous (spiked) and endogenous prion infectivity from red cells with a new prototype of leukoreduction filter.

BACKGROUND: Two recent probable cases of transmission of a variant of human Creutzfeldt-Jakob disease (vCJD) through blood transfusion suggest that the disease can be transmitted through transfusion of blood components from presymptomatic blood donors. In the absence of a preclinical screening test, removal of the infectious agent by processing is the only means by which risk to recipients of blood from donors with inapparent vCJD infections can be eliminated. STUDY DESIGN AND METHODS: In the endogenous infectivity study, a pool of 500 mL of whole blood was collected into CP2D anticoagulant from 263K-strain scrapie-infected hamsters, processed into 300 mL of red cells (RBCs), and then passed through a prion removal filter. Pre- and postfiltration samples were tested for PrP(sc) by Western blot and for infectivity by inoculation of healthy hamsters. In the exogenous (spiking) infectivity study, 30 mL of 10 percent (wt/vol) scrapie-infected brain homogenates was added to 270 mL of human RBCs and then filtered. Levels of PrP(sc) and infectivity were determined by Western blot and bioassay. RESULTS: In the endogenous infectivity study, the prefiltered RBCs transmitted disease to 6 of 43 animals, whereas the postfiltered RBCs did not transmit disease to any of 35 animals, and a barely visible prefiltration PrP(sc) Western blot signal was reduced below the level of detection in the postfiltration sample. In the exogenous (spike) study, infectivity was reduced by 3.7 log LD50 per mL, from 9.2 to 5.5 log LD50 per mL. CONCLUSION: The new filter was effective in removing both infectivity and PrP(sc) from RBCs. The use of this type of filter should reduce the risk of vCJD transmission through blood transfusion.

Animals↗

Infectivity studies of both ash and air emissions from simulated incineration of scrapie-contaminated tissues.

We investigated the effectiveness of 15 min exposures to 600 and 1000 degrees C in continuous flow normal and starved-air incineration-like conditions to inactivate samples of pooled brain macerates from hamsters infected with the 263K strain of hamster-adapted scrapie with an infectivity titer in excess of 10(9) mean lethal doses (LD50) per g. Bioassays of the ash, outflow tubing residues, and vented emissions from heating 1 g of tissue samples yielded a total of two transmissions among 21 inoculated animals from the ash of a single specimen burned in normal air at 600 degrees C. No other ash, residue, or emission from samples heated at either 600 or 1000 degrees C, under either normal or starved-air conditions, transmitted disease. We conclude that at temperatures approaching 1000 degrees C under the air conditions and combustion times used in these experiments, contaminated tissues can be completely inactivated, with no release of infectivity into the environment from emissions. The extent to which this result can be realized in actual incinerators and other combustion devices will depend on equipment design and operating conditions during the heating process.

Air Pollutants↗

Autophagy is a part of ultrastructural synaptic pathology in Creutzfeldt-Jakob disease: a brain biopsy study.

Ultrastructural correlates of synaptic and dendritic spines loss have never been studied in detail in human transmissible spongiform encephalopathies (TSEs)-Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker (GSS) disease and fatal familial insomnia (FFI). In this paper, we describe synaptic alterations as found in brain biopsies from Creutzfeldt-Jakob disease and fatal familial insomnia patients. Our material consisted of brain biopsies obtained by open surgery from one FFI case, one case of variant Creutzfeldt-Jakob disease (vCJD), seven cases of sporadic Creutzfeldt-Jakob disease (sCJD) and one case of iatrogenic (human growth hormone) Creutzfeldt-Jakob disease (iCJD). For electron microscopy, approximately 2mm(3) samples were immersion fixed in 2.5% glutaraldehyde for less than 24h, embedded in Epon and routinely processed. Grids were examined and photographed in a transmission electron microscope. The synaptic alterations were found constantly; in practically every brain biopsy they were frequent. The accumulation of different subcellular organelles (neuroaxonal dystrophy), dark synapses and branching cisterns were the most frequent findings while concentric arrays of membranes were only rarely found. Autophagic vacuoles are formed in many synapses in all categories of human transmissible encephalopathies. We conclude that synaptic autophagy contributes to overall synaptic loss in brains affected in prion diseases.

Adult↗

Neuronal cell death in transmissible spongiform encephalopathies (prion diseases) revisited: from apoptosis to autophagy.

Neuronal autophagy, like apoptosis, is one of the mechanisms of the programmed cell death (PCD). In this review, we summarize the presence of autophagic vacuoles in experimentally induced scrapie, Creutzfeldt-Jakob disease and Gerstmann-Sträussler-Scheinker (GSS) syndrome. Initially, a part of the neuronal cytoplasm was sequestrated by concentric arrays of double membranes; the enclosed cytoplasm appeared relatively normal except that its density was often increased. Next, electron density of the central area dramatically increased. The membranes then proliferated within the cytoplasm in a labyrinth-like manner and the area sequestrated by these membranes enlarged into a more complex structure consisting of vacuoles, electron-dense areas and areas of normally-looking cytoplasm connected by convoluted membranes. Of note, autophagic vacuoles form not only in neuronal perikarya but also in neurites and synapses. Finally, a large area of the cytoplasm was transformed into a collection of autophagic vacuoles of different sizes. On a basis of ultrastructural studies, we suggest that autophagy plays a major role in transmissible spongiform encephalopathies (TSEs) and may even participate in a formation of spongiform change.

Animals↗

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.

Adrenal Insufficiency↗

Erythropoietin protects the kidney against the injury and dysfunction caused by ischemia-reperfusion.

Erythropoietin (EPO) is upregulated by hypoxia and causes proliferation and differentiation of erythroid progenitors in the bone marrow through inhibition of apoptosis. EPO receptors are expressed in many tissues, including the kidney. Here it is shown that a single systemic administration of EPO either preischemia or just before reperfusion prevents ischemia-reperfusion injury in the rat kidney. Specifically, EPO (300 U/kg) reduced glomerular dysfunction and tubular injury (biochemical and histologic assessment) and prevented caspase-3, -8, and -9 activation in vivo and reduced apoptotic cell death. In human (HK-2) proximal tubule epithelial cells, EPO attenuated cell death in response to oxidative stress and serum starvation. EPO reduced DNA fragmentation and prevented caspase-3 activation, with upregulation of Bcl-X(L) and XIAP. The antiapoptotic effects of EPO were dependent on JAK2 signaling and the phosphorylation of Akt by phosphatidylinositol 3-kinase. These findings may have major implications in the treatment of acute renal tubular damage.

Animals↗

The modern landscape of transfusion-related iatrogenic Creutzfeldt-Jakob disease and blood screening tests.

The idea that blood in naturally occurring transmissible spongiform encephalopathies is not infectious has imploded in the face of recent transmissions from the blood of naturally occurring scrapie in sheep and of variant Creutzfeldt-Jakob disease in humans. Although donor exclusion criteria ensure that the number of any further iatrogenic cases will be small, the risk of future blood-borne disease transmissions could be entirely eliminated by a diagnostic preclinical screening test. A variety of methodological approaches to blood testing are under development, with different levels of success, but no method has yet achieved the critical goal of discriminating transmissible spongiform encephalopathy-infected from healthy uninfected humans.

Blood Donors↗

Effect of protease treatment on plasma infectivity in variant Creutzfeldt-Jakob disease mice.

BACKGROUND: The emergence of variant Creutzfeldt-Jakob disease (vCJD) and of a probable transmission of the disease through blood transfusion from a presymptomatic case has underlined the need for a reliable, sensitive, and specific screening test. This study was initiated to explain why attempts to identify protease-resistant prion protein (PrPres) following treatment with proteinase K (PK) in blood or blood components have so far failed. STUDY DESIGN AND METHODS: RIII mice were inoculated intracerebrally (i.c.) with vCJD agent. As soon as some mice became ill, blood from all mice was collected, pooled, and separated into components. Aliquots of plasma were treated with either 100 and 500 microg per mL PK or left untreated. Samples were analyzed for total protein and for PrPres by Western blot with 6H4 antibodies. Infectivity in PK-treated and untreated samples was bioassayed by i.c. inoculation into healthy mice. RESULTS: Estimated infectivity in untreated control plasma was 20.6 IU per mL. Treatment of plasma with 100 or 500 microg per mL PK resulted in estimated infectivity levels of 8.4 and 5.2 IU per mL, respectively. Coomassie staining revealed substantial changes in the protein profile after PK treatment, with massive degradation of proteins at 500 microg per mL PK. No PrPres was detected in plasma samples by Western blotting. CONCLUSION: Infectivity in plasma of vCJD-infected mice showed a trend toward reduction following enzymatic treatment with increasing doses of PK, possibly because of activity against proteolysis-sensitive isoforms of abnormal prion protein. It is concluded that the use of PK in protocols for the detection of PrPres may decrease the sensitivity of blood-based assays.

Animals↗

Variation in specialist fees: evidence from New Zealand insurance claims.

OBJECTIVES: To examine the parity between specialties in reimbursements for surgical procedures in a private, fee-for-service setting and to ascertain whether differences exist after accounting for factors suggested by a Resource-Based Relative Value Scale (RBRVS). METHODS: A routinely updated database covering several private insurers (n = 8294 procedures from 1997 to 2002) was used to examine differences in overall and hourly reimbursement. Multiple regression analysis was used to control for factors that might be responsible for differences in payment (location, year, sex of patient and the associated anaesthetist fee). The resulting regression residuals were compared between specialties. RESULTS: Large differences between specialties in reimbursements were found in the overall amount paid. For most specialties, these differences were explained by factors such as time for procedure, location, complexity of procedure and sex of patients. However, hourly reimbursements for ophthalmologists were substantially higher (more than 50% above general surgery overall and 72% higher on an hourly basis). Some other smaller differences in overall and hourly reimbursement were also found. CONCLUSIONS: These results indicate that specialist fees vary significantly but many of the differences are explainable by factors incorporated into the RBRVS. However, significant variation remains for some specialties, most notably ophthalmology. Explanations for the results are discussed, including the possibility that political factors may influence the setting of specialist fees. This raises questions concerning the fairness of reimbursements and resulting solidarity within the medical profession.

Fee-for-Service Plans↗

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.

Animals↗

Fate of myelinated fibres in the optic nerves in experimental Creutzfeldt-Jakob disease in rodents: an ultrastructural study.

We report the ultrastructural appearances of myelinated fibres of the optic nerves from mice infected with the Fujisaki strain of Gerstmann-Sträussler-Scheinker (GSS) disease and from Echigo-1 strain of Creutzfeldt-Jakob disease (CJD). Optic nerves from CJD- and GSS-infected rodents showed severe pathological changes. Theses changes were qualitatively indistinguishable from each other but were more robust in the Fujisaki GSS model than in the hamsters inoculated with Echigo-1. The most characteristic finding was the distension with the attenuation of the myelin sheath forming a vacuole while shrunken axon was attached to the innermost layer of the myelin. With high power electron microscopy, we could observe the splitting of the myelin lamellae at the major dense or intraperiod lines to form complex openings that extended to line the vacuole. This finding suggests that myelin lamellae participate in the formation of vacuoles.

Animals↗

Kuru: a half-opened window onto the landscape of neurodegenerative diseases.

Kuru, the first human neurodegenerative disease classified as a transmissible spongiform encephalopathy (TSE), prion disease or, in the past, as a slow unconventional virus disease, was first reported to Western medicine in 1957 by Gajdusek and Zigas. A complete bibliography of kuru through 1975 has been published by Alpers et al. The solution of the kuru riddle opened a novel field of biomedical sciences and initiated more than a quarter of century of research that has already resulted in two Nobel prizes (to D. Carleton Gajdusek in 1976 and to Stanley B. Prusiner in 1997) and was linked to a third (to Kurt Wüthrich who determined the structure of the prion protein). Kuru research has impacted the concepts of nucleation-polymerization "protein cancers", and "conformational disorders". This paper is dedicated to Dr. Carleton Gajdusek on the occasion of his 80th birthday. "Kuru" in the Fore (Fig. 1) language means to shiver from fever or cold. The Fore used the noun of the kuru-verb to describe the always fatal disease which decimated their children and adult women but rarely men. It has been and still is restricted to natives of the Fore linguistic group at Papua New Guinea's Eastern Highlands and those neighboring linguistic groups which exchange women with Fore people (Auiana, Awa, Usurufa, Kanite, Keiagana, late, Kamano, Kimi; Fig. 2). Neighboring groups into which kuru-affected people did not settle through marriage or adoption, such as the Anga (Kukukuku), and remote lagaria, Kamano and Auiana people, were not affected. It seems that Kuru first appeared at or shortly after the turn of XX century in Uwami village of Keiagana people and spread to the Awande in the North Fore where the Uwami had social contacts. Within 20 years it had spread further into the Kasokana (in 1922 according to Lindebaum) and Miarasa villages of North Fore, and a decade later had reached the South Fore at the Wanikanto and Kamira villages. Kuru became endemic in all villages that it entered and became hyperendemic in the South Fore region. All native informants stressed the relatively recent origin of kuru. Interestingly enough, when kuru first appeared, it was considered poetically by Fore as similar to "the swaying of casuarinas tree" and kuru was labeled cassowary disease to stress the similarity between cassowary quills and "waving casuarinas fronds". Gajdusek first learned about kuru from Dr. Roy Scragg, director of Public Health in Port Mosby, who had already read a report sent by Dr. Vin Zigas to Dr. John Gunter in 1956. In March 1957, Gajdusek joined Zigas, who at that time was a medical patrol officer in Kainantu, Eastern Highland District of the Territory of Papua New Guinea.

Adult↗

The effect of nitric oxide on glucose metabolism.

Nitric oxide (NO) is an important bioactive signaling molecule that mediates a variety of normal physiological functions, which, if altered, could contribute to the genesis of many pathological conditions, including diabetes. In this study, we examined the possible diabetogenicity of NO by noting differences in the cellular binding of insulin in dogs treated with the NO donor, S-nitrosoglutathione (GSNO) compared to captopril-treated controls. GSNO administration resulted in an abnormality in glucose metabolism which was attributed to decreased binding of insulin to its receptor on the cell membrane of mononuclear leucocytes, 11.60 +/- 0.60% in GSNO-treated dogs compared with 18.10 +/- 1.90% in captopril-treated control (p < 0.05). The decreased insulin binding was attributed to decreased insulin receptor sites per cell, 21.43 +/- 2.51 x 10(4) in GSNO-treated dogs compared with 26.60 +/- 1.57 x 10(4) in captopril-treated controls (p < 0.05). Average affinity analysis of the binding data demonstrated that this decrease in insulin binding was also due to a decrease in average affinity of the receptor on mononuclear leucocytes for insulin. This was evident by a decrease in empty and filled site affinities in GSNO-treated dogs compared with that of captopril-treated dogs (p < 0.05). It appears that GSNO is exerting its effect by decreasing the number of insulin receptor sites and/or decreasing the average receptor affinity. These results provide evidence for a novel role of NO as a modulator of insulin binding and the involvement of NO in the aetiology of diabetes mellitus.

Animals↗

Astrocytes in transmissible spongiform encephalopathies (prion diseases).

Astrocytosis is one of the hallmarks of neuropathology of transmissible spongiform encephalopathies (TSEs) or prion diseases. In this review, we summarize data on astrocytic reaction, including naturally occurring or experimentally induced TSEs. A particular form of astrocytic reaction is known as gliocytosis and it is typical for experimental scrapie in mouse or in hamsters. Also, astrocytes participate in the formation of amyloid plaques. An interesting interaction between astrocytes and oligodendrocytes is discussed in detail as well as a particular form of astrocytic reaction in panencephalopathic form of TSEs.

Animals↗