The rate of hospital readmission per patient-year of follow-up is as high as 0.46 after implantation of a modern cardioverter/defibrillator. Rehospitalization time in such patients is significantly longer in the patient cohort >60 years. The majority of readmissions is caused by multiple appropriate shock treatments. Further studies are needed to systematically investigate strategies for the prevention of rehospitalization in modern ICD therapy.
Platelet-activating factor (PAF) is rapidly degraded in vivo by the action of a specific acetylhydrolase. Measuring the PAF-acetylhydrolase activity in serum from 12 healthy volunteers a maximum velocity of 67.2 ± 11.8 nmol/min × ml and a Km value of 15.8 ± 2.9 μmol/l were ascertained. More than 90% of the activity was found to be associated with lipoproteins. It was detected in isolated VLDL, LDL, Lp(a) as well as HDL2 but not in HDL3. The PAF-acetylhydrolase activities associated with the various lipoproteins were shown to behave like a unique enzyme with distinct kinetic properties. Because VLDL and LDL were found to take up about 5 and 2.5 times more PAF with respect to their mass than HDL, it is concluded that lipoproteins affect the PAF-acetylhydrolase activity at the level of substrate presentation. As a consequence of the distinct kinetic properties, the lipoprotein-associated PAF-acetylhydrolase activities do not contribute proportionately to the degradation of PAF in serum. The latter is shown to depend primarily on the amount of PAF-acetylhydrolase bound to the apoprotein B-containing lipoproteins.
The degradation of platelet-activating factor (PAF) and lipid concentrations were measured in sera from 20 patients with insulin-dependent diabetes mellitus and from 20 age- and sex-matched healthy volunteers. The PAF-degrading capacity as well as triglycerides and total and very low density and low-density lipoprotein cholesterol were found to be significantly increased in the patients group, whereas the difference observed in high-density lipoprotein cholesterol was statistically nonsignificant. There were also a series of close relationships between the degradation of PAF and some lipid variables in the control group. These results confirm the parallel changes of lipoproteins and PAF-degrading capacity described previously in serum from atherosclerotic patients and extend it to patients suffering from diabetes mellitus.
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