Journal of internal medicine
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Hyaluronan is a polysaccharide found in all tissues and body fluids of vertebrates as well as in some bacteria. It is a linear polymer of exceptional molecular weight, especially abundant in loose connective tissue. Hyaluronan is synthesized in the cellular plasma membrane. ⋯ In animals and man, the half-life of hyaluronan in tissues ranges from less than 1 to several days. It is catabolized by receptor-mediated endocytosis and lysosomal degradation either locally or after transport by lymph to lymph nodes which degrade much of it. The remainder enters the general circulation and is removed from blood, with a half-life of 2-5 min, mainly by the endothelial cells of the liver sinuoids.
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Microcirculation represents the smallest functional unit of the cardiovascular system, where the interaction between blood and tissue creates the environment necessary for cell function. Analysis of physiology and pathophysiology of this system gives a unique perspective to the disease process, and provides the link between clinical and molecular medicine. The present status and future directions of this medical and scientific frontier were assessed and projected by experts in the field at a meeting in Italy in 1995, and the conclusions are presented in this article.
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The objective was to review the current status of meta-analysis, the process of combining the results of similar investigations, which was described in 1976. It has evolved rapidly, and thousands have already been published. Meta-analysis may be performed in a narrative form or in the preferred statistical format, which is more rigorous and demanding. ⋯ Examples are given from my own field--hepatology--and from my own research experience. Although meta-analysis is simple in concept, it is complex in execution. If performed with insufficient insight or attention to detail, it may give ambiguous or erroneous results.
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Hypertriglyceridaemia, as defined by fasting triglyceride levels of greater than 2.8 mmol l-1, is a prevalent dyslipoproteinaemia in our population. The underlying pathophysiological mechanisms that result in elevations of plasma triglycerides are heterogeneous and, in most cases, incompletely understood. However, in a subset of patients presenting with this lipid disorder, the biochemical and genetic defects that lead to hypertriglyceridaemia have been well characterized. ⋯ Together, these two proteins initiate the hydrolysis of triglycerides present in chylomicrons and very low density lipoproteins. In the past decade our understanding of the underlying molecular defects that lead to familial chylomicronaemia has been greatly enhanced by the identification of mutations in the genes for LPL and apoC-II. Characterization of these defects has provided new insights into the structure and function of apoC-II and LPL and established the important role that these two proteins play in normal triglyceride metabolism.