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Biomedical subjects

L Imandt

Publications and source records attributed to L Imandt.

8 recordsLinked to original sources
PubMed1987

Tissue plasminogen activator activity and inhibition in acute myocardial infarction and angiographically normal coronary arteries.

Parameters of blood coagulation, blood platelet reactivity and fibrinolysis were analyzed in 18 patients with acute myocardial infarction (AMI) and angiographically normal coronary arteries. This study group was compared with a patient control group of 18 AMI patients with 1-vessel obstructive coronary artery disease. Patients were matched for sex, age and AMI date. A healthy control group consisted of 18 sex- and age-matched volunteers. Blood coagulation measurements and platelet reactivity were similar in the 3 groups, except for fibrinogen, which was significantly higher in the patient control group. Plasma activity of tissue plasminogen activator (tPA) was detectable in only 2 patients in the study group, 9 in the patient control group (p less than 0.02) and 12 in the healthy control group (p less than 0.0001). Median plasma tPA inhibitory activity was higher in the study group (10.3 IU/ml) and the patient control group (8.1 IU/ml) than in the healthy control group (2.7 IU/ml, p less than 0.0001 and p less than 0.03). Thus, reduced activity and enhanced inhibition of plasma tPA may be important factors in the origin of coronary thrombosis, especially in the absence of coronary artery disease.

Adult↗
PubMed1981

Lithium inhibits adenylate cyclase of human platelets.

The ADP-induced aggregation of human platelets is markedly increased after preincubation with lithium chloride, whereas lithium has the opposite effect on rabbit platelets. Since this phenomenon might be related to cAMP metabolism, the influence of lithium on total cAMP content and adenylate cyclase activity was investigated. Lithium does not significantly change the total cAMP content of human platelets neither during incubation nor during ADP-induced aggregation. Basal adenylate cyclase activity, however, was slightly inhibited by lithium in human platelets. The inhibition of adenylate cyclase by ADP appeared to be enhanced by lithium. Prostacyclin induced stimulation of adenylate cyclase is counteracted by this ion. In rabbit platelets the prostacyclin stimulated adenylate cyclase activity is not affected by lithium. These data suggest that a correlation exists between the influence of lithium on the aggregation of human and rabbit platelets and the sensitivity of their adenylate cyclase for this ion.

Adenylyl Cyclase Inhibitors↗
PubMed1981

Lithium stimulates thromboxane B2 formation in human platelets.

The aggregation of human platelets is enhanced after preincubations with lithium salts. Previously it was shown that lithium inhibits adenylate cyclase activity in human platelets. Enhancement of aggregation and inhibition of adenylate cyclase by lithium was not observed in rabbit platelets. In this paper it is shown that in human platelets lithium enhances considerably the synthesis of thromboxane B2, whereas the synthesis of PGE2 and PGF2 alpha was enhanced to a lesser extent. In rabbit platelets lithium had no effect on prostaglandin synthesis. It is concluded that lithium specifically stimulates the synthesis of thromboxanes in human platelets, probably due to the previously reported inhibition of adenylate cyclase activity, resulting in an increased aggregability.

Adenosine Diphosphate↗
PubMed1980

Observations on ADP aggregation of lithium chloride incubated platelets in a variety of mammalian species.

In citrated platelet-rich plasma of eight mammalian species lithium produces species-dependent effects on ADP aggregation ranging from stimulation to inhibition. Raising the extracellular calcium concentration enhanced aggregation of both lithium-stimulated and lithium-inhibited platelets, indicating that the extracellular calcium concentration has no direct relation to the effect of lithium on platelet function. Lithium did not induce changes in total intracellular platelet calcium and magnesium contents. Aggregation of platelets with ionophore A23187 showed the same species-specific lithium effects as aggregation induced by ADP. The data suggest that lithium does not exert its effect on platelets through interference with intra- or extracellular calcium concentrations.

Adenosine Diphosphate↗