The time of onset of ischemic stroke was determined for 1,167 of 1,273 patients during the collection of data by four academic hospital centers between June 30, 1983, and June 30, 1986. More strokes occurred in awake patients from 10:00 AM to noon than during any other 2-hour interval. The incidence of stroke onset declined steadily during the remainder of the day and early evening. The onset of stroke is least likely to occur in the late evening, before midnight.

SUMMARY Because creatine kinase (CK) appears in cardiac lymph after myocardial infarction, this study was undertaken to determine whether lymph inactivates CK in vitro and whether interruption of cardiac lymph flow influences estimation of infarct size based on plasma CK changes in conscious dogs. After the effects of incubation of canine myocardial CK in native, deproteinized, or sulfhydrylfortified lymph and dialysates had been characterized; effects of interruption of cardiac lymph flow on plasma CK time-activity curves after coronary occlusion were assessed in 13 conscious dogs, seven of which had exteriorized occlusive snares around cardiac lymphatics as well as the left anterior descending coronary artery. Native and deproteinized lymph as well as lymph dialysate markedly inactivated CK in vitro with associated nonenzymatically mediated proteolysis detectable on SDS gels. CK released into blood after coronary occlusion compared to myocardial CK depletion was 50% less in dogs with lymphatic occlusion (P< 0.01) although CK loss in the centers of infarcts (73% and 69%) and overall CK depletion (18% and 20%) were similar in the two groups. Based on comparison of observed to projected plasma CK values prior to lymphatic occlusion, significantly less CK appeared in blood when coronary occlusion was followed by lymphatic occlusion (P < 0.01), although the rate of disappearance of CK from the systemic circulation was not altered. Thus, lymph inactivates CK in vitro, and plasma CK time-activity curves after coronary occlusion are influenced considerably by interruption of cardiac lymph flow, a factor that should be incorporated to refine enzymatic estimates of infarct size.SINCE the amount of creatine kinase (CK) (EC 2.7.3.2) depleted from the heart in experimental animals with infarction correlates with independent criteria of necrosis, 12 a mathematical model has been developed to estimate CK depletion from analysis of plasma CK timeactivity curves.3 Parameters in the model formulated initially include the proportion of CK depleted from the heart that appears in the circulation, CK distribution space, and the rate of CK disappearance from the circulation. Since CK, as well as other enzymes, appears in lymph after myocardial infarction, 4 " 6 development of physiologically rather than empirically based models describing CK time-activity curves requires characterization of CK transport and potential inactivation in lymph. Cardiac lymph flow is low, approximately 1-3 ml/100 g per hr in anesthetized animals.7 ' 8 Thus, CK released into lymph may be exposed to it for prolonged intervals. Accordingly, if lymph not only transports but also influences CK activity, plasma CK time-activity curves following coronary occlusion might be affected markedly.The present study was undertaken to characterize effects of canine cardiac lymph on canine myocardial CK in vitro and the effects of marked perturbation of cardiac lymph flow in vivo on plasma CK time-activity curves after infarction. Methods ReagentsBovine serum albumin, fra...

No abstract

No abstract

No abstract