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Biomedical subjects

J R O'Brien

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

At least 19 recordsLinked to original sources
PubMed1979

Changes in the heparin neutralising activity of platelet poor plasma after immunisation.

Acute myocardial disease, which may be associated with abnormal platelet activity, has been reported after routine immunisation. Thirty-two army apprentices undergoing immunisation were studied for changes in the heparin neutralising activity (HNA) of platelet poor plasma. HNA increased after immunisation. This increase in HNA may represent an increase in platelet activation but may also relate to changes in acute phase proteins. These changes were not observed in elderly subjects undergoing immunisation with influenza vaccine.

Adolescent↗
PubMed1978

The effect of ICI 55,897 and clofibrate on platelet function and other tests abnormal in atherosclerosis.

There is considerable evidence that the quantity or quality of plasma lipids influences platelet function tests, and clofibrate reduces high plasma lipids and alters some platelet tests. Clofibrate was accordingly given to patients with vascular disease who were at risk of thrombosis. The heparin thrombin clotting time (HTCT), initially short and thus possibly reflecting increased activation, was regularly returned to normal after about a month's delay. The fibrinogen was also normalized but the initially abnormal anti-thrombic activity became more abnormal. ICI 55,897, an analogue of clofibrate, also normalized the HTCT and the fibrinogen and had no adverse effect on the anti-thrombin levels. This compound has no effect on plasma lipids. If it can be shown that the correction of abnormal tests conveys clinical benefit these findings suggest that ICI 55,897 might clinically be more beneficial than clofibrate. However, direct comparison of clofibrate and ICI 55,897 suggests that clofibrate is more effective in normalizing the HTCT. The mechanism underlying these drug-induced changes are unknown but they cannot be directly related to lipid changes.

Aged↗
PubMed1976

Effect of a diet of polyunsaturated fats on some platelet-function tests.

The fat in the normal diet of 19 apparently well men was partly replaced by linoleic acid. This produced striking changes in many platelet-function tests, suggesting decreased platelet activation. Twenty controls maintaining their normal diet showed no change. It is concluded that normal people have a degree of platelet activation which can be decreased. This may be relevant to the benefits attributed to a diet containing polyunsaturated fats.

Adult↗
PubMed1976

Acute platelet changes after large meals of saturated and unsaturated fats.

Large amounts of saturated fats (S.F.) or unsaturated fats (U.S.F.) were given to healthy volunteers at a single meal. The heparin thrombin clotting-time, which may measure platelet factor 4 released from platelets into the plasma, was shortened after S.F. and prolonged after U.S.F. The antithrombin clotting activity decreased after S.F. and increased after U.S.F. The platelet-count decreased and the platelet volume increased after both S.F. and U.S.F.

Adult↗