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Potential Detrimental Effects (potential + detrimental_effects)
Selected AbstractsWear mechanisms in metal-on-metal bearings: The importance of tribochemical reaction layersJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2010Markus A. Wimmer Abstract Metal-on-metal (MoM) bearings are at the forefront in hip resurfacing arthroplasty. Because of their good wear characteristics and design flexibility, MoM bearings are gaining wider acceptance with market share reaching nearly 10% worldwide. However, concerns remain regarding potential detrimental effects of metal particulates and ion release. Growing evidence is emerging that the local cell response is related to the amount of debris generated by these bearing couples. Thus, an urgent clinical need exists to delineate the mechanisms of debris generation to further reduce wear and its adverse effects. In this study, we investigated the microstructural and chemical composition of the tribochemical reaction layers forming at the contacting surfaces of metallic bearings during sliding motion. Using X-ray photoelectron spectroscopy and transmission electron microscopy with coupled energy dispersive X-ray and electron energy loss spectroscopy, we found that the tribolayers are nanocrystalline in structure, and that they incorporate organic material stemming from the synovial fluid. This process, which has been termed "mechanical mixing," changes the bearing surface of the uppermost 50 to 200 nm from pure metallic to an organic composite material. It hinders direct metal contact (thus preventing adhesion) and limits wear. This novel finding of a mechanically mixed zone of nanocrystalline metal and organic constituents provides the basis for understanding particle release and may help in identifying new strategies to reduce MoM wear. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:436,443, 2010 [source] Review article: endoscopic antireflux procedures , an unfulfilled promise?ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2008F. PACE Summary Background, Most published reviews concerning the endoscopic treatment of gastro-oesophageal reflux disease date back to 2005. Aim, To provide an updated review that includes all papers published up to 2007. Methods, A Medline search from January 2005 to June 2007 was performed regarding endoscopic procedures aiming at treating gastro-oesophageal reflux disease. In addition, we retrieved the abstracts presented at Digestive Disease Week during the last 3 years. We included in the review both ,mechanistic' studies , that is, papers exploring the potential mechanism of action of the procedure/device , and studies trying to assess its clinical efficacy. Results, During the last 3 years, the number of published papers has declined, and some devices are not available any more. The alleged mechanism(s) of action of the various devices or procedures is (are) still not completely elucidated; however, some concerns have arisen as far as durability and potential detrimental effects. Moreover, all the aspects of endoscopic therapy, except for its safety, are either insufficiently explored or not investigated at all, or assessed only in particularly selected patient subgroups. Conclusions, None of the proposed antireflux therapies has fulfilled the criteria of efficacy, safety, cost, durability and, possibly, of reversibility. There is at present no definite indication for endoscopic therapy of gastro-oesophageal reflux disease. We suggest a list of recommendations to be followed when a new endoscopic therapeutic procedure is to be assessed for use in clinical practice. [source] Successful Lung Transplantation in an HIV- and HBV-Positive Patient with Cystic FibrosisAMERICAN JOURNAL OF TRANSPLANTATION, Issue 9 2009A. Bertani Prior to the advent of highly active antiretroviral therapy (HAART), HIV-infected patients were usually not considered as transplant candidates because of the poor prognosis of their underlying disease and concerns regarding the potential detrimental effects of immunosuppression on viral load and immune status. However, with the significant HAART-associated improvements in morbidity and mortality, good short-term outcomes after liver and kidney transplantation for patients with HIV infection have been reported. Nevertheless, HIV infection is currently considered a contraindication to lung transplantation in most transplant centers worldwide. The results of a double lung transplant performed in an HIV and HBV co-infected patient with cystic fibrosis (CF) and end-stage respiratory failure (ESRF) are presented after a 2-year follow-up. Approval of and recommendations for the management of this patient were obtained from the Italian National Center for Transplantation as an extension of the ongoing Italian protocol for liver and kidney transplantation in HIV-infected individuals. The operation was successful and the patient recovered rapidly after surgery. A cautious infectious and immunosuppressive management allowed so far the avoidance of major infectious complications and rejection. To the best of our knowledge, this is the first report of lung transplantation in an HIV and HBV co-infected patient. [source] Parasite resistance and genetic variation in the endangered Gila topminnowANIMAL CONSERVATION, Issue 2 2001Philip W. Hedrick In recent years, it has become apparent that introduced or novel pathogens or parasites may have a significant negative impact on endangered species. Here we examine experimentally the effect of an exotic fluke from guppies on the endangered Gila topminnow. Populations from different sources showed variable responses (although statistically non-significant) to the fluke and, in particular, the most homozygous population had high fluke infections and high subsequent mortality. Homozygotes for a MHC (major histocompatibility complex) gene had lower (although statistically non-significant) survival when infected with flukes than did heterozygotes. An inbred line from one of the populations had statistically significant lower survival and higher fluke infection than did a simultaneous outbred control. Overall, Gila topminnows appear quite susceptible to infection by the non-native fluke compared to other related species. In addition, it was shown that Gila topminnows can be infected by casual contact with infected guppies. This is another example of the potential detrimental effects of a parasite on an endangered species, a threat that may constitute a particular problem for species with low genetic variation, either in general, for important MHC genes, or for populations with a past history of inbreeding. [source] Optimal fed-batch cultivation when mass transfer becomes limitingBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2007John Villadsen Abstract In the design of an aerobic fed-batch process to produce, for example, a pharmaceutical protein, the volumetric production rate will eventually become limited by mass transfer when the biomass concentration exceeds a certain upper limit x*. It appears to be common practice to switch from exponential feed of substrate to a constant feed rate when x* is reached. This is done to avoid oxygen starvation with a potential risk of undesired stress responses. But with a constant feed rate the carbon source (glucose) concentration may decrease to a low level with a resulting loss of viability and an undesired production of endotoxins. It is shown that an exponential feeding strategy may be continued, but with a smaller exponent than the one used before oxygen limitation occurs. This will diminish the potential detrimental effects on the culture due to low glucose concentration, and the total time to reach a given final biomass concentration will be reduced. Biotechnol. Bioeng. 2007;98: 706,710. © 2007 Wiley Periodicals, Inc. [source] |