人类朊毒体病的诊治及预防

传染性和家族性人类中枢神经系统以慢性海绵状退行性变为特征的疾患,如克-雅病（CJD）、杰茨曼-斯脱司勒-史茵克综合征（GSS）、致死性家族性失眠症（FFI）及库鲁病的病原过去曾认为均为慢病毒感染所致,现已认识到其病原体为朊毒体类,并且将此类疾患统称为传播性神经退行变性疾患或称朊毒体病。     

Lower specific infectivity of protease-resistant prion protein generated in cell-free reactions

Prions are unconventional infectious agents that cause transmissible spongiform encephalopathy (TSE) diseases, or prion diseases. The biochemical nature of the prion infectious agent remains unclear. Previously, using a protein misfolding cyclic amplification (PMCA) reaction, infectivity and disease-associated protease-resistant prion protein (PrPres) were both generated under cell-free conditions, which supported a nonviral hypothesis for the agent. However, these studies lacked comparative quantitation of both infectivity titers and PrPres, which is important both for biological comparison with in vivo-derived infectivity and for excluding contamination to explain the results. Here during four to eight rounds of PMCA, end-point dilution titrations detected a >320-fold increase in infectivity versus that in controls. These results provide strong support for the hypothesis that the agent of prion infectivity is not a virus. PMCA-generated samples caused the same clinical disease and neuropathology with the same rapid incubation period as the input brain-derived scrapie samples, providing no evidence for generation of a new strain in PMCA. However, the ratio of the infectivity titer to the amount of PrPres (specific infectivity) was much lower in PMCA versus brain-derived samples, suggesting the possibility that a substantial portion of PrPres generated in PMCA might be noninfectious.     

朊毒体感染的现状及研究进展

朊毒体病 (priondisease)是一类人和动物的慢性中枢神经系统退行性疾病 ,其中人类朊毒体病包括库鲁病 ,克雅病(CJD) ,杰茨曼 -斯脱司勒 -史茵克综合征 (GSS) ,致死性家族性失眠症 (FFI) ,新变异型CJD(nvCJD) ;动物的朊毒体病包括牛海绵状脑病 (BSE或疯牛病 )、羊瘙痒症等。现已证实 ,这类神经系统变性疾病的病因是一种由蛋白质组成而缺乏核酸的传染因子。其发现者美国的Prusiner教授将之命名为Prion。Prion的中文称谓曾有多种译名 ,现较为接受的是“朊粒”和“朊毒体”。1　朊毒体的特点及致病机制朊毒体是一种分子质量很小的、有…     

Antiretrovirals to prevent HIV infection: Pre-and postexposure prophylaxis

More than 3 million people are now receiving antiretroviral therapy (ART) worldwide. Currently, the indications for ART depend primarily on CD4 count, blood viral burden, and clinical signs and symptoms suggesting advanced HIV disease. However, interest is increasing in ART’s preventive potential. Postexposure prophylaxis following both occupational and nonoccupational exposure to HIV is the standard-of-care in many settings. Observational and ecologic studies suggest that ART administered to HIV-infected people reduces transmission within serodiscordant couples. Pre-exposure prophylaxis to prevent HIV infection is a potentially safe and intermittent intervention for very high-risk people, and clinical trials to evaluate this preventive strategy are underway. The prevention benefits of ART may begin to affect the decision of when to start therapy and add a much-needed strategy to current HIV prevention efforts.     

Pathogen inactivation methods to prevent transfusion-transmissible arboviruses: A systematic review and meta-analysis

Objective

Arboviruses are emerging as a relevant threat to transfusion safety. Pathogen inactivation methods (PIMs) may reduce the risk of transmission through transfusion, as long as they meet minimum standards for effectiveness. This study aims to assess the log reduction of viral load achieved with different PIMs, according to the blood product they are used on and the arbovirus targeted.

Methods

Systematic literature review and meta-analysis. Searches were conducted in MEDLINE and Embase. The study protocol was registered in PROSPERO CRD42022312061. We selected records reporting the log reduction of viral load achieved with the main PIMs (amotosalen + UVA light [INTERCEPT], riboflavin + UV light [Mirasol], methylene blue + visible light/UVC light [THERAFLEX], solvent detergent, amustaline [INTERCEPT] and PEN110 [Inactine]), applied to any blood product (plasma, platelets, red blood cells or whole blood) and for any arbovirus. The log reduction of viral loads was assessed by obtaining the mean log reduction factor (LRF). We compared and classified the LRF of different techniques using statistical methods.

Results

We included 59 publications reporting LRF results in 17 arboviruses. For 13 arboviruses, including Chikungunya virus, Dengue virus, West Nile virus and Zika virus, at least one of the methods achieves adequate or optimal log reduction of viral load−mean LRF ≥4. The LRF achieved with riboflavin + UV light is inferior to the rest of the techniques, both overall and specifically for plasma, platelets preserved in platelet additive solution (PAS)/plasma, and red blood cells/whole blood. The LRF achieved using Mirasol is also lower for inactivating Chikungunya virus, Dengue virus and Zika virus. For West Nile virus, we found no significant differences. In plasma, the method that achieves the highest LRF is solvent/detergent; in platelets, THERAFLEX and INTERCEPT; and in red blood cells/whole blood, PEN110 (Inactine).

Conclusion

Not all PIMs achieve the same LRF, nor is this equivalent between the different arboviruses or blood products. Overall, the LRFs achieved using riboflavin + UV light (Mirasol) are inferior to those achieved with the rest of the PIMs. Regarding the others, LRFs vary by arbovirus and blood product. In light of the threat of different arboviruses, blood establishments should have already validated PIMs and be logistically prepared to implement these techniques quickly.     

Crystal structure of human prion protein bound to a therapeutic antibody

Prion infection is characterized by the conversion of host cellular prion protein (PrP^C) into disease-related conformers (PrP^Sc) and can be arrested in vivo by passive immunization with anti-PrP monoclonal antibodies. Here, we show that the ability of an antibody to cure prion-infected cells correlates with its binding affinity for PrP^C rather than PrP^Sc. We have visualized this interaction at the molecular level by determining the crystal structure of human PrP bound to the Fab fragment of monoclonal antibody ICSM 18, which has the highest affinity for PrP^C and the highest therapeutic potency in vitro and in vivo. In this crystal structure, human PrP is observed in its native PrP^C conformation. Interactions between neighboring PrP molecules in the crystal structure are mediated by close homotypic contacts between residues at position 129 that lead to the formation of a 4-strand intermolecular β-sheet. The importance of this residue in mediating protein–protein contact could explain the genetic susceptibility and prion strain selection determined by polymorphic residue 129 in human prion disease, one of the strongest common susceptibility polymorphisms known in any human disease.     

Novel processes for inactivation of leukocytes to prevent transfusion-associated graft-versus-host disease

Transfusion-associated graft-versus-host disease (TA-GVHD) is a serious complication of blood component transfusion therapy. Currently, cellular blood components for patients recognized at risk for TA-GVHD are irradiated prior to transfusion in order to prevent this complication. Considerable progress has been made in elucidating the pathophysiology of this highly morbid complication, but questions as to which patients are at risk and what is the most robust technology to prevent TA-GVHD remain. As new technologies for inactivating or modulating leukocyte function are introduced, the question of how to evaluate these technologies becomes relevant. Over the past two decades, a number of research groups have explored technology to inactivate infectious pathogens and leukocytes contaminating cellular blood components. Few clinicians have an in-depth understanding of the methods or the criteria for selection of how to approach new technologies for leukocyte inactivation with potential to replace current methods. This mini review focuses on the salient aspects of current and evolving technology for prevention of TA-GVHD.     

Oral rapamycin to prevent human coronary stent restenosis: a pilot study

Background

Recent human trials with rapamycin-eluting stents have shown very low restenosis rates. However, the high costs of these devices preclude their use in routine angioplasty, especially when considering multiple stenting. We evaluated whether orally administered rapamycin inhibits in-stent neointimal growth in patients with unstable angina.

Methods

We enrolled 15 patients successfully treated with the implantation of a single stent in a single de novo lesion in native coronary arteries. Correct stent expansion and apposition were corroborated with intravascular ultrasound scanning in all patients. Patients received aspirin, clopidogrel, and atorvastatin for 6 months. Rapamycin was administered in a loading dose of 5 mg, followed by 2 mg/day for 4 weeks.

Results

The reference diameter was 3.4 ± 0.4 mm, lesion length was 11.2 ± 2 mm, lesion type B1 was 36%, and lesion type B2 was 64%. After the procedure, in-stent minimal lumen diameter and diameter stenosis (DS) were 3.3 ± 0.4 mm and 0.3% ± 7.5%, respectively. At 10 days, plasma levels of rapamycin were 7.95 ± 2.6 ng/mL. At 6 months, angiographic determinations demonstrated an in-stent minimal lumen diameter of 2 ± 1 mm, an in-stent DS of 41.3% ± 28.0%, and an in-stent late loss of 1.4 ± 1.1 mm. Binary restenosis (>50% DS) was present in 6 of 15 patients (40%). Target lesion revascularization (coronary artery bypass grafting) was performed in 2 of 15 patients (13.3%). There were no serious adverse events during the 6-month period of follow-up, but 1 patient had severe heartburn caused by esophagitis, and another patient had herpes zoster at the end of the protocol.

Conclusions

Oral rapamycin was well tolerated, but did not suppress in-stent neointimal growth in this small group of patients.     

Consumption of red and processed meat and esophageal cancer risk:Meta-analysis

To summarize the evidence about the association between red and processed meat intake and the risk of esophageal cancer,we systematically searched the PubMed and EMBASE databases up to May 2012,with a restriction to English publications,and the references of the retrieved articles.We combined the studyspecific relative risks(RRs) and 95%CI,comparing the highest with the lowest categories of consumption by using a random-effects model.A total of 4 cohort studies and 23 case-control studies were included in the meta-analysis.The combined RRs(95%CI) of the cohort studies comparing the highest and lowest categories were 1.26(1.00-1.59) for red meat and 1.25(0.83-1.86) for processed meat.For the case-control studies,the combined RRs(95%CI) comparing the highest and lowest categories were 1.44(1.16-1.80)for red meat and 1.36(1.07-1.74) for processed meat.Findings from this meta-analysis suggest that a higher consumption of red meat was associated with a greater risk of esophageal cancer.     

Hepatitis B virus infection and pregnancy: a practical approach

Hepatitis B virus (HBV) infection is a global problem and the world has 350 million carriers of chronic hepatitis B. Over 50 % of these have acquired their infection vertically from their mothers (mother-to-child transmission [MTCT]). Majority (>90 %) of vertically-acquired infection results into chronic infection, due to induction of an immune-tolerant state. Hence, management of chronic HBV during pregnancy and strategies to prevent MTCT would go a long way in global control of HBV infection and the morbidity and mortality associated with it. However, chronic HBV infection in pregnancy presents a unique challenge, because of existence of a complex relationship between the physiological changes of pregnancy and the pathophysiological response of body to HBV. This relationship may lead to a varied presentation of the patient to the doctor depending on the period of her pregnancy and stage of her liver disease. Each of these modes of presentation raises issues that need to be addressed for successful maternal and fetal outcome, including prevention of MTCT of HBV. This review will try to give a practical approach in addressing these issues.     

Detection of Plasmodium falciparum infection in human patients: a comparison of the DNA probe method to microscopic diagnosis

We have previously reported the isolation and testing of a DNA probe specific for the detection of Plasmodium falciparum. Field studies to compare the sensitivity and specificity of the DNA probe with that of light microscopy have been performed. In 2 studies in Thailand, 1,397 patients were tested. Microscope slides were prepared in a standard fashion and examined by clinical technicians and expert microscopists. The DNA probe method compares favorably in sensitivity with routine microscopy, detecting parasite densities as low as 40 parasites/microliters blood in the first study and, after modifications, 20-25 parasites/microliters blood in the second. Modifications included the elimination of salt from the lysis buffer, increasing the pH of the lysis buffer, and use of nylon based hybridization membranes instead of nitrocellulose. The DNA probe method offers the advantage of a standardized procedure that can be used in a batchwise fashion on a large number of samples.     

Helicobacter pylori upregulates prion protein expression in gastric mucosa： A possible link to prion disease

AIM: Pathological prion protein (PrPSC) is responsible for the development of transmissible spongiform encephalopathies (TSE). While PrPc enters the organism via the oral route, less data is available to know about its uptake and the role of gastrointestinal inflammation on the expression of prion precursor PrPc, which is constitutively expressed in the gastric mucosa. METHODS: We studied PrPc expression in the gastric mucosa of 10 Helicobacter pylori-positive patients before and after successful H pylori eradication compared to non-infected controls using RT-PCR and Western blotting. The effect of central mediators of gastric inflammation, i.e., gastrin, prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) on PrPc expression was analyzed in gastric cell lines. RESULTS: PrPc expression was increased in H pylori-infection compared with non-infected controls and decreased to normal after successful eradication. Gastrin, PGE2, and IL-1β dose-dependently upregulated PrPc in gastric cells, while TNF-α had no effect. CONCLUSION: H pylori infection leads to the upregula-tion of gastric PrPc expression. This can be linked to H pylori induced hypergastrinemia and increased mucosal PGE2 and IL-1β synthesis. H pylori creates a milieu for enhanced propagation of prions in the gastrointestinal tract.     

Using maximal sterile barriers to prevent central venous catheter-related infection: a systematic evidence-based review

BACKGROUND: Catheter-related infections cause increased morbidity, mortality, and health care costs. Infection control experts advocate using maximal sterile barriers to reduce the incidence of these infections. Low compliance rates suggest that clinicians are not convinced or are not aware that available data support adopting this more cumbersome, time-consuming, and relatively more expensive technique. Accordingly, we conducted a systematic, evidence-based review of the medical literature to determine the value of maximal sterile barriers. DATA SOURCES: We used multiple computerized databases, reference lists of identified articles, and queries of prominent investigators. STUDY SELECTION: We selected studies comparing infectious outcomes using maximal sterile barriers versus using less stringent sterile barrier techniques during central venous catheter insertion. DATA SYNTHESIS: We found only 3 primary research studies. Although each study suggests maximal sterile barriers may reduce infectious complications, the evidence supporting this conclusion is incomplete. The only randomized controlled trial limited enrollment to ambulatory oncology patients. These 3 studies differed notably in their patient populations, research designs, and health care settings. CONCLUSION: The medical literature suggests maximal sterile barriers are advantageous in at least one setting and may be useful in others. While we believe the available evidence does support the use of maximal sterile barriers during routine insertion of central venous catheters, prospective studies and economic analyses would better clarify its value.     

Stroke in Italy: a disease to prevent

Stroke, a disease determining an increasing socioeconomic burden in aging populations, represents the second cause of mortality worldwide and the third cause of mortality in western countries. In our study, crude annual incidence rate of stroke was 293/ 100,000. Several conditions and life-style factors have been identified as risk factors for stroke. Their recognition is important to prevent stroke. Atherothrombosis contributes a large proportion of cases; however, conventional stroke risk factors do not fully account for the risk of stroke, and often stroke victims with documented atherosclerosis may not show any conventional risk factor. A major goal is to promote prevention of stroke through identification and clarification of new risk factors and pathogenic mechanisms. Moreover, early stroke prevention requires a comprehensive multidisciplinary strategy to educate and promote adherence to preventive protocols.