Proteomic characterization of the effects of clofibrate on protein expression in rat liver.

Clofibrate is a peroxisome proliferator known to induce liver tumours in rats. A proteomics study was conducted to provide new insights into the molecular mechanisms of clofibrate-induced non-genotoxic hepatocarcinogenesis. Rats were treated with 250 mg/kg day clofibrate orally and sacrificed after 7 days. Proteins extracted from the liver were analysed by 2-DE using DIGE technology. The protein identification performed by MS showed that clofibrate induced up-regulation of 77 proteins and down-regulation of 27 proteins. The highest expression ratios corresponded to proteins involved in a series of biochemical pathways such as lipid metabolism, fatty acid metabolism, amino acid metabolism, protein metabolism, citric acid cycle, xenobiotic detoxification and oxidative stress. Proteins implicated in cell proliferation and apoptosis, such as prohibitin, 10-formyl tetrahydrofolate dehydrogenase, senescence marker protein-30, pyridoxine 5'-phosphate oxidase and vimentin, were also identified as being regulated. These results provide leads for further investigations into the molecular mechanisms of liver tumours induced by clofibrate. In addition, MS results showed that a series of regulated proteins were detected as several spots corresponding to different pI and/or M(r). Differential effects on those variants could result from specific PTM and could be a specific molecular signature of the clofibrate-induced protein expression modulation in rat liver.

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.

Novel methods for disinfection of prion-contaminated medical devices.

BACKGROUND: The unique resistance of prions to classic methods of decontamination, and evidence that prion diseases can be transmitted iatrogenically by medical devices pose a serious infection control challenge to health-care facilities. In view of the widespread tissue distribution of the variant Creutzfeldt-Jakob disease agent in human beings, new practicable decontamination procedures are urgently needed. METHODS: We adapted an in-vivo method using stainless steel wires contaminated with prions to the hamster-adapted scrapie strain 263K. A new in-vitro protocol of surface contamination compatible with subsequent biochemical detection of PrP(res) (protease-resistant form of the prion protein) from the treated surface was developed to explore the mechanisms of action of methods of decontamination under test. These models were used to investigate the effectiveness of innovative physical and chemical methods of prion inactivation. FINDINGS: Standard chemical decontamination methods (NaOH 1N, NaOCl 20000 ppm) and autoclaving in water at 134 degrees C reduced infectivity by >5.6 log10 lethal doses; autoclaving without immersion was somewhat less effective (4-4.5 log reduction). Three milder treatments, including a phenolic disinfectant, an alkaline cleaner, and the combination of an enzymatic cleaner and vaporised hydrogen peroxide (VHP) were also effective. VHP alone, which can be compatible with electronic components, achieved an approximately 4.5 log reduction in infectivity (equivalent to autoclaving without water immersion). INTERPRETATION: New decontamination procedures are proposed to ensure the safety of medical and surgical instruments as well as surfaces that cannot withstand the currently recommended prion inactivation procedures.