Infectious agent transmission

Associated with the administration of blood or blood products is the risk of aeeidental transmission of infectious agents. Transmission of hepatitis, as well as AIDS, has generated prominent attention in this regard, but several bacterial and parasitic diseases may also be transmitted via infected blood products (Table 9.2). 

The inescapable variability of the source material and potential threat to safety due to unrecognized infectious agents [transmission ofAIDS by blood products and the undefined potential for either human or bovine source materials to spread Creutzfeld-Jakob disease (CJD)/ transmissible or bovine spongiform encephalopathy (TSE, BSE)]... 

The most resistant of all infectious agents to chemical inactivation are the prions, which cause transmissible degenerative encephalopathies. 

Prion diseases resulting in encephalopathy can be transmitted between individuals within species (more rarely between species) [26-28], A conformational variant of the normal cellular protein PrPs (PrPc) (protease-sensitive or cellular) is believed to catalyze [29] or nucleate [30-33] conversion to the pathological form, PrPR (protease-resistant). This highly unusual nongenetic mode of transmission of an infectious agent has been strongly debated [29]. The observation of multiple examples of nucleated catalysis of aberrant polymerization of protein subunits has... 

In addition to enhancing erythropoiesis, EPO treatment also improves tolerance to exercise, as well as a patient s sense of well-being. Furthermore, reducing/eliminating the necessity for blood transfusions also reduces/eliminates the associated risk of accidental transmission of blood-borne infectious agents, as well as the risk of precipitating adverse transfusion reactions in recipients. The therapeutic spotlight upon EPO has now shifted to additional (non-renal) applications (Table 10.8). 

Isolation Separation of infected persons or animals from others to prevent or limit direct or indirect transmissions of the infectious agent. 

To meet the infectivity requirement in the definition of a prion, the abnormal form of the protein must be transmissible to other cells and organisms of the same species. In yeast and filamentous fungi, infectious agents such as viruses and plasmids are naturally transmitted by cytoplasmic mixing during mating or heterokaryon formation (Wickner, 2001). 

Table 9.2. Some of the infectious agents that have been transmitted via administration of infected blood or blood products. Transmission of viruses, particularly hepatitis A and B virus and HIV, are most common...

The abnormal deposits found in the brains of CJD victims consist of an abnormal isoform of PrP. Prion protein is normally found in cells. Detailed structural studies show that normal cellular PrP (PrP ) is a soluble protein whose conformation is rich in a-helices with very little P-sheet. The PrP protein extracted from the brains of CJD victims (i.e., PrP ) is identical in primary amino acid sequence to the normal PrP (PrP ). However, PrP has a much greater content of P-sheet conformation with little a-helical structure. Thus PrP is neurotoxic because of its three-dimensional structure. When the prion protein is predominantly in an a-helical conformation it is nontoxic when the prion protein is predominantly in a P-sheet conformation, it kills neurons. The prion protein is thus made neurotoxic not by its amino acid composition but by its conformation. This concept is both fascinating and terrifying. Prion diseases are transmissible thus prions are infectious agents. However, prions are not like bacteria or viruses, or other infectious microbes—they are simply protein molecules. Prions are not microbes with cell membranes and nucleic acids they are not living things. Indeed, prions are not even infectious molecules, they are infectious molecular shapes. 

A. General description Prolastin is prepared from pooled human plasma of normal donors it has a molecular weight of 52kDa. To reduce the potential risk of transmission of infectious agents, Prolastin has been heat-treated in solution at 60 + 0.5°C for not less than 10 hours. However, no procedure has been found to be totally effective in removing viral infectivity from plasma fractionation products. 

Warnings Should be administered in facilities equipped and staffed with adequate laboratory and supportive medical resources Immunosuppressive activity may vary from lot to lot Potential for the transmission of infectious agents Treatment should be discontinued if the following occur Symptoms of anaphylaxis Thrombocytopenia Leukopenia... 

Safety from transmission of infectious agents must be ensured. 

Prions (small proteinaceous infectious particles) are a unique class of infectious agent causing spongiform encephalopathies such as bovine spongiform encephalopathy (BSE) in cattle and Creutzfeldt-Jakob disease (CJD) in humans. There is considerable concern about the transmission of these agents from infected animals or patients. Risk of infec-tivity is highest in brain, spinal cord and eye tissues. There are still many unknown factors regarding de-... 

Transmission of blood-borne viruses is always a concern when blood and blood-derived products are used. The infection of a large number of hemophiliac patients with hepatitis viruses and HIV during the 1980s prompted the development of virucidal methods to inactivate infectious agents. All currently available plasma-derived factor concentrates come from screened donors and undergo viral... 

Center for Disease Control (CDC) in Atlanta, and all but a few of these were in the USA or Haiti. The Republican-controlled US Senate and the White House of Ronald Reagan were reluctant to recognise a condition that affected gays and Haitians The small number of European cases, most of whom had spent some time in Africa, seemed to imply an African origin for the infectious agent, with onwards transmission via Haiti to the USA. 

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