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Biomedical subjects

E F Bernstein

Publications and source records attributed to E F Bernstein.

At least 145 records · Page 8Linked to original sources
PubMed1977

The pulse-reappearance time: an index of over-all blood flow impairment in the ischemic extremity.

A simple test is described to evaluate limb blood supply. The technique utilizes the delayed reappearance of the volume pulse after transient arterial occlusion. As monitored from the toe by a mercury-in rubber gauge, pulse reappearance (PRT) was instantaneous (less than one second) and the 50 percent of control amplitude reappearance time (PRT/2) was 3.4 +/- 0.8 seconds in 22 control subjects. A significant delay of the PRT and especially of PRT/2 was found in 60 patients with angiographically documented ischemic disease of the lower extremities. The delay was correlated closely with the severity of the disease: the mean PRT/2 for single level arterial disease (aortoiliac, femoropopliteal, posterior tibial, or anterior tibial artery obstruction) was approximately 25 seconds, and the mean PRT/2 associated with multilevel occlusion was 71 seconds. Since the technique is very simple, it may be used as a quick screening and follow-up procedure to detect the presence and over-all severity of peripheral arterial occlusive disease.

Arterial Occlusive Diseases↗
PubMed1977

Structural correlates of platelet functional damage by physical forces.

Human platelets, which were selectively damaged either in a device designed to impose surface injury or one in which damage is primarily limited to shear forces in the fluid bulk, were examined with the electron microscope in an effort to correlate functional and ultrastructural evidence of injury. Surface injury results in more severe inhibition of platelet adhesion and aggregation, as well as PF-3 and PF-4 activity. These functional effects are accompanied by profound and widespread ultrastructural changes, including membrane defects, enlargement of the open cannicular system, alterations in dense bodies and alpha granules, and the development of globular shapes. Very little serotonin is lost, but there is an increase in the number of abnormal dense bodies. In contrast, the shear injured cells demonstrate few functional defects, despite a lesser but still substantial number of structural changes, at forces up to 10(5) dynes/cm2. At higher shears, both functional and structural evidence of severe injury is present, along with apparently normal platelet aggregation.

Blood Platelets↗
PubMed1976

Prolonged pulseless perfusion in unanesthetized calves.

Nonpulsatile left ventricular (LV) bypass was achieved in nine alert, active calves for periods of up to two weeks using a centrifugal blood pump. Data were compared to prebypass control values and to results obtained from seven calves that underwent nonthoracotomy, retrograde LV cannulation, and pulsatile bypass for up to 35 days. Nonpulsatile flow produced an increase in heart rate of 20% (P less than .05) and an increase in aortic pressure of 10% (P less than .05). Cardiac output and systemic vascular resistance were similar in both groups for three days; thereafter, vascular resistance decreased as cardiac output progressively increased. Serum renin, lactate, and pyruvate values remained normal; creatinine clearances were not significantly different than control values, and there were no significant changes in body weight. These data indicate no untoward effects as a result of prolonged pulseless perfusion.

Anesthesia↗
PubMed1976

Growth rates of small abdominal aortic aneurysms.

A policy of utilizing B-mode ultrasound scan measurements of abdominal aortic aneurysms to help determine operability in poor-risk patients with small asymptomatic aneurysms has been pursued for the past 6 years. Indications for surgery in such patients have included enlargement to 6 cm. in any transverse diameter, the development of symptoms, or evidence of leak or rupture. In addition, patients treated nonoperatively have been followed by serial B-mode echo scans, permitting the accumulation of aneurysm growth rate data. Such data indicate that small aneurysms grow an average of 0.4 cm. per year, but that dramatic increases in aneurysm size may occur unexpectedly in asymptomatic patients. These data appear to have value in both individual decision making and as a baseline for weighting the various risk factors in the poor-risk patient with a small asymptomatic abdominal aortic aneurysm.

Aged↗
PubMed1976

The effects of pulseless perfusion on the distribution of renal cortical blood flow and on renin release.

The effects of pulseless perfusion on the distribution of renal blood flow and on release of renin were studied in anesthetized dogs. The distribution of renal blood flow to four cortical layers was determined with the radioactive microsphere technique during pulsatile control conditions and after one and 2 hours of pulseless perfusion, without significant changes in mean arterial pressure and mean total renal blood flow. Simultaneously, renal vein blood samples were analyzed for renin (radioimmunoassay technique). During pulseless perfusion there was a consistent and progressive redistribution of blood flow toward deeper cortical layers with the outer cortical layer falling from 36.9 to 25.3% p less than 0.001) and the juxtamedullary cortex increasing from 14.5 to 25.4% (p less than 0.001) after 2 hours. In addition, there was a progressive increase in renal venous concentration of renin, which was 20.91 +/- 6.6 ng. per millimeter per hour after 2 hours of pulseless flow compared to 5.06 +/- 1.16 ng. per millimeter per hour during control conditions (p less than 0.05). These changes in cortical blood flow and in release of renin were not observed in sham-operated controls. The results indicate that pulseless flow alone produced both a significant increase in renal production of renin and a significant redistribution of renal cortical blood flow, due to the greater vasoconstriction in the outer cortex when compared to the juxtamedullary cortex.

Animals↗
PubMed1975

Platelet function in calves: a study of adhesion, aggregation, release, clotting factor activity and life span.

Normal calf platelets were found to significantly differ human platelets in a number of important respects. The average calf platelet count is more than twice the average human value. Calf platelets demonstrated no adhesion to glass, in a test in which over 50% of human platelets adhered. Responsiveness to several aggregating, agents, including ADP, thrombin and collagen, was markedly diminished in the calf platelet, requiring much higher concentrations of the stimulating agent to produce comparable responses. In addition, calf platelet clot-promoting activity was far less effective than with human platelets following stimulation with Celite or Russell's viper venom, although the total platelet factor 3 content exceeded that found in human paltelets, following complete disruption. In addition, the calf platelet has a significantly shorter life span and higher turnover rate than the human. These species differences in normal platelet function must be considered in evaluating the results of experiments with artificial organs in the calf model.

Animals↗