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Biomedical subjects

J R O'Brien

Publications and source records attributed to J R O'Brien.

At least 109 records · Page 6Linked to original sources
PubMed1975

Heparin neutralizing activity test in the diagnosis of acute myocardial infarction.

We have previously shown in patients after recovery from a myocardial infarct (post-MI) that the heparin neutralizing activity (HNA) in the plasma is raised and that this activity may come from platelet factor 4 derived from activated platelets. This report concerns 89 patients admitted with acute chest pain; in 54, with evidence of acute infarction, the level of HNA is much higher than in a post-MI group or controls. Over the ensuing weeks the HNA decreases to the post-MI level. In 34 patients the evidence subsequently collected excluded a diagnosis of infarction; in these there were almost always normal amounts of HNA and little overlap with the results from the patients with infarcts. This easy test is therefore likely to prove clinically useful. Its significance is discussed. The platelet count and platelet volume are both abnormal in patients with acute infarction and also in the chest pain group so these tests do not help to discriminate.

Acute Disease↗
PubMed1974

Anti-thormbin III and heparin clotting times in thrombosis and atherosclerosis.

A survey of the literature shows that when whole blood clots thrombin is formed and there is a decrease in anti-thrombin III (Anti-Th. III) and an increase in heparin neutralizing activity (HNA) which is probably identical to platelet factor 4 derived from platelets. Many studies of atherosclerosis and of arterial and venous thrombosis using various tests thought to measure Anti-Th. III and HNA report a decrease in Anti-Th. III or an increase in HNA or both. We have measured both in patients with atherosclerosis and survivors of myocardial infarction. The HNA was increased and the serum anti-thrombic activity was decreased relative to controls and there was an inverse correlation between the two measurements. All this evidence suggests that some kind of mild chronic intravascular coagulation may occur in atherosclerosis. These changes could be related to the cause or the result of atherosclerosis.

Antithrombin III↗