Gerhard Johnson, M.D.

VA Medical Center

Dr. Johnson focuses on platelet biology and related coagulation problems. Current studies include: [a] elucidation of thromboxane receptor biology, using the characteristic canine signaling defect as a model to provide evidence that control involves thromboxane receptor phosphorylation; [b] evaluation of the role of platelet serotonin uptake and release in pathogenesis of dexfenfluramine cardiopulmonary toxicity; [c] clinical studies of prophylactic therapy for deep vein thrombosis in high risk orthopedic surgery patients.

Selected Publications

Burroughs SF, Johnson GJ. Beta-lactam antibiotic-induced platelet dysfunction: Evidence for irreversible inhibition of platelet activation in vitro and in vivo after prolonged exposure to penicillin. Blood 1990; 75:1473-1480.

Johnson GJ, Leis LA, Francis GS. Adenosine potentiates the inhibitory effects of calcium antagonists on human platelet aggregation induced by thromboxane A2 or U46619. Thromb Res 1990; 59:139-148.

Johnson GJ, Leis LA, King RA. Thromboxane responsiveness of dog platelets is inherited as an autosomal recessive trait. Thromb Haemost 1991; 65:578-580.

Johnson GJ. Platelets, penicillins, and purpura: What does it all mean? J Lab Clin Med 1993; 121:531-533.

Burroughs SF,Johnson GJ. Beta-lactam antibiotics inhibit agonist-stimulated platelet calcium influx. Thromb Haemost 1993; 69:503-508.

Johnson GJ, Leis LA, Dunlop PC. Thromboxane-insensitive dog platelets have impaired activation of phospholipase C due to receptor-linked G protein dysfunction. J Clin Invest 1993; 92:2469-2479.

Johnson GJ, Leis LA, Dunlop PC. Specificity of G alpha q and G alpha 11 gene expression in platelets and erythrocytes. Expressions of cellular differentiation and species differences. Biochem J 1996; 318:1023-1031.

Dunlop PC, Leis LA, Johnson GJ. Epinephrine correction of impaired platelet thromboxane receptor signaling. Am J Physiol Cell Physiol 2000; 279:C1760-1771.

Johnson GJ, Leis LA, Dunlop PC, Weir EK. The effect of the anorectic agent, d-fenfluramine, and its primary metabolite, d-norfenfluramine, on intact human platelet serotonin uptake and efflux. J Thromb Haemost 2003; 1:2663-8.