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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Seven calves underwent thoracotomy to study the response of 41 physiologic variables over a 14 day post-operative period for comparison to a recent series of left ventricular bypass pump implants. The experimental protocols were identical to the pump implant protocols except that the sham operated animals did not receive antiplatelet or anticoagulant drugs and the pumps were not implanted. Of the 41 variables studied, 13 changed significantly during the post-operative period. Heart rate, hematocrit, whole blood hemoglobin, and fibrinogen concentration decreased, while fibrinogen survival, stroke volume, cardiac output, arterial blood pH, pCO2 and pO2, plasma sodium concentration, and urinary excretion rates of sodium and potassium increased from the first or second to the fourteenth post-operative day. Heart rate and hematocrit also decreased in the recent series of 18 animals in which left ventricular bypass pumps were implanted. The decrease in heart rate is toward the unoperated control value as the calves recover from the operative stress. The decrease in hematocrit is probably the result of daily removal of blood for the physiologic studies because there was no evidence of hemorrhage or red blood cell destruction.
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PMID:Forty-one variables following thoracotomy in calves. 72 17

A whole-body positron-emission transaxial tomograph (PETT III) was used to image the cross-sectional distribution of 13NH3 and 11CO-hemoglobin in the human brain and heart. Carotid and intravenous bolus injections of 13NH3 in the rhesus monkey had shown that 13NH3 is efficiently extracted by the brain and clears from it slowly (half-time, 40-50 min for carotid injections and 60-70 min for intravenous injections). The intravenous tomographic images in humans showed an excellent relationship between 13NH3 uptakes in the cortex, subcortical white matter, cerebellum, and brain stem and normal blood perfusion or flow in these structures. Cerebral lesions with high (metastasis) and low (stroke) blood flows showed correspondingly high and low uptakes of 13NH3. Large- and small-vascular structures of the brain were also clearly seen in 11CO-hemoglobin tomographic images. Normal myocardium and the ventricular chambers were well defined, and a transmural anterior myocardial infarct was clearly shown. The effective combination of positron transaxial tomography and compounds labeled with positron-emitters provides a safe new method for quantitatively imaging hemodynamic and physiologic functions of selected organs with good tomographic image quality.
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PMID:Tomographic images of blood pool and perfusion in brain and heart. 81 45

Sixty children age 5 to 16 years with normal or nearly normal hearts performed submaximal and maximal supine bicycle exercise. Submaximal cardiac output was linearly correlated with work load (r = 0.80). After 2 minutes' exercise cardiac output was over 90 per cent of the value for 6 minutes' exercise. Maximal cardiac index was 10.1 +/- 1.8 for boys and 8.6 +/- 1.8 L. per minute per square meter for girls. Stroke volume was highest during the recovery period after maximal exercise. Pulmonary artery PO2 fell to 24 mm. Hg, oxygen saturation to 33 per cent, and pH to 7.21. During maximal exercise mean pulmonary artery pressure was 24 +/- 5 mm. Hg and mean brachial artery pressure was 113 +/- 8. There were no major differences between children aged 5 to 9 years of age and those 10 to 16 years, except for higher hemoglobin values in postpubertal children.
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PMID:Hemodynamics of supine bicycle exercise in "normal" children. 85 Oct 61

The problem of early differentiation of "traumatic tap" from subarachnoid hemorrhage (SAH) was studied in the rabbit by determining the changes in percentage of hemolysis and in lactate concentrations in CSF within the first twenty-four hours following induced SAH. The 0.3 to 7% hemolysis which occurred was relatively independent both of the time following SAH and of the number of red blood cells (rbc) in the cerebrospinal fluid (CSF). There was, on the other hand, a significant and time-dependent increase in CSF lactate concentration early after SAH, suggesting the potential clinical value of the detection of increased lactate with a relatively normal lactate/pyruvate ratio in hemorrhagic CSF. Until this can be evaluated in human subjects, however, determination of the rbc counts or total hemoglobin concentrations in serially collected samples of CSF remains the best clinical method.
Stroke
PMID:Differentiation of early subarachnoid hemorrhage from traumatic lumbar puncture. 90 62

The results of hemoglobin determination in the CSF by the method of fluorescence microscopy in 195 patients speaks in favor of relative diagnostical importance of hemoglobin in the supra fall-out CSF for establishing the character of the stroke. The following circumstances testify to this fact: 1) in an artificial admixture of blood in the CSF in some cases there may be hemolysis of "passing" erythrocytes; 2) in a genuine admixture of blood, tests of hemoglobin in the centrifugate of the CSF may be negative since in some cases the transition of hemoglobin into bilirubin in the subarachmoid space occurs more rapidly than the hemolysis of erythrocytes. Thus, the hemoglobin does not accumulate in the liquid in quantities, sufficient enough to be measured by the existing methods; 3) in a large amount of artificial blood admixture, even without a hemolysis of "passing" erythrocytes the hemoglobin tests in the centrifugate of the CSF may be positive at the expense of hemoglobin of the blood plasma.
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PMID:[Diagnostic value of determining hemoglobin in cerebrospinal fluid in acute cerebral circulatory disorders]. 91 51

Records of 11 postmenopausal parkinsonism patients were evaluated in comparison with those of 11 postmenopausal depression patients. None had a history of encephalitis, stroke, drug-induced or toxic extrapyramidal disorders, or active bleeding within six months before admission. There was no significant differences between the two groups with regard to time interval from menopause to onset of symptoms, height, weight, or age at first admission. Both groups showed normal height, hemoglobin, hematocrit, and erythrocyte counts. Parkinsonism patients were underweight and had a shorter interval from menopause to onset of symptoms (12.4 +/- 1.9 vs. 16.8 +/- 2.5 yr.). These findings are compatible with the hypothesis that in parkinsonism, hereditary predisposition to positive body iron balance may be associated with alteration of the blood-brain barrier in parkinsonism.
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PMID:Postmenopausal Parkinsonism: brain iron overload? 93 Jul 48

To study central circulation at different levels of hemoglobin (Hb) concentration, five subjects performed submaximal and maximal exercise in three different situations: 1) control, 2) after venesection of 800 ml of whole blood, and 3) after reinfusion of the red blood cells about 30-35 days after venesection. Maximal oxygen uptake (VO2 max) decreased from 4.27 l-min-1) at control to 4.03 l-min-1 after venesection (P less than 0.05) and increased to 4.61 l-min-1 after reinfusion (P less than 0.05). Maximal values on cardiac output (Q), heart rate (HR), and stroke volume (SV) were the same in the three situations. Thus, there was no compensatory increase in Qmax due to the lowered arterial oxygen content (Cao2) after venesection. An increase of the Cao2 (Hb concentration) and a lowering of the Cvo2 contributed equally to the increased VO2 max after reinfusion. At a given submaximal VO2, HR and blood lactates were increased at lowered Hb concentration and decreased at increased Hb concentration over control levels. Correlation coefficient for the change in Q in relation to the acute change in Hb concentration at a given submaximal VO2 was -0.49 (P less than 0.05).
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PMID:Central circulation during exercise after venesection and reinfusion of red blood cells. 93 52

Acute isovolemic anemia was produced in anesthetized chickens by serial exchanges of 6% dextran 70 equal to 1% of body weight to quantitate cardiovascular and metabolic parameters. When hematocrit (Hct) and hemoglobin (Hb) levels were reduced by 50% (from 33.3 to 16.3 vol %, and from 10.3 to 5.4 g/100 g, respectively, P less than 0.001), tissue oxygen delivery was maintained by increases in cardiac output (CO), stroke volume (SV), oxygen extraction, and reduced total peripheral resistance (TPR). Heart rate, right atrial pressure, and oxygen consumption (Vo2) were unchanged. Further reductions in Hct and Hb (to 10.8 vol % and 3.7 g/100 g, respectively), were accompanied by cardiovascular failure, as evidenced by falling CO, SV, tissue oxygen delivery, and Vo2. Relative apparent viscosity determinations on the exchanged blood-dextran mixtures indicated that large viscosity changes occurred with the first exchange whereas subsequent exchanges had small incremental viscosity changes. These data indicate that in acutely anemic chickens, oxygen transport capacity was maintained by increased cardiac output and decreased peripheral resistance, unless the severity of the anemia resulted in cardiovascular failure.
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PMID:Acute isovolemic anemia in anesthetized chickens. 99 89

The oxy form of sickle hemoglobin precipitates rapidly during mechanical shaking. The rate of precipitation depends on shaking conditions such as stroke amplitude, frequency, angle between the vial axis and the shaking motion, volume and viscosity of hemoglobin solution and temperature. The rate increases linearly with either stroke (S) or frequency (n) above a certain value (S = 5 mm or n = 10Hz). The rate constant was maximum when the angle 0 between the vial axis and the shaking direction was 30 degrees. The rate of precipitation of sickle oxyhemoglobin was faster at high temperatures and always about 10 times greater than that of normal hemoglobin. The activation energies of precipitation of hemoglobin S and A are 20.3 and 21.3 kcal/mol, respectively. The thermogram of hemoglobin was measured by a differential scanning calorimeter. The denaturation temperatures determined from the peak of denaturation curves were 83.5 degrees C for oxyhemoglobin S and 85 degrees C for oxyhemoglobin A. The precipitated hemoglobin after mechanical shaking did not show any denaturation peak indicating that the protein molecules are irreversibly denatured by shaking.
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PMID:Denaturation of oxyhemoglobulin S by mechanical shaking. 99 91

Review of the epidemiology of atherothrombotic brain infarction (ABI) based largely on 18 years of prospective data from the Framingham cohort reveals that stroke is a potent force in morbidity and mortality, that hypertension is its dominant precursor, that it can be predicted and suggests that only a preventive approach can substantially reduce stroke morbidity. Data from Framingham on the relative frequency of the major types of stroke found in the community reveal that 57 percent are due to ABI and only 17 percent to intracranial hemorrhage--two-thirds of which is subarachnoid. Lacunar infarcts are common accounting for 13 percent of ABI's in men and 23 percent in women. Despite the sizeable geographic, seasonal and secular trends in stroke mortality, few environmental determinants of stroke have been uncovered. However, established hallmarks of the candidate for an atherothrombotic stroke include: hypertension (systolic or diastolic), glucose intolerance, high normal hemoglobin, the cigarette habit (men only), abnormal lipids (under age 60) and cardiac impairments. Many unresolved issues remain. Nevertheless, it is possible to identify a tenth of the general population from which half the strokes will emerge. This provides a rational basis for establishing a program of prevention.
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PMID:An evaluation of the epidemiology of atherothrombotic brain infarction. 104 23


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