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Biomedical subjects

D Karpman

Publications and source records attributed to D Karpman.

22 records · Page 2Linked to original sources
PubMed1997

von Willebrand factor mediates increased platelet retention in recurrent thrombotic thrombocytopenic purpura.

The plasma cryoprecipitate of two brothers with recurrent thrombotic thrombocytopenic purpura (TTP) was previously found to mediate increased platelet retention and contain ultra-large von Willebrand factor (vWF) multimers during remissions. We conducted this study to examine if vWF is involved in the increased platelet retention in TTP. Platelet retention decreased when the patients' plasma was incubated with a monoclonal antibody directed to the vWF epitope which interacts with the platelet receptor glycoprotein Ib or when incubated with a Fab-fragment directed to the platelet receptor glycoprotein IIb/IIIa. Replacement of patient vWF with an equivalent concentration of a factor VIII/vWF concentrate containing no ultra-large vWF multimers was accompanied by a normalization of platelet retention. These results indicate that vWF is involved in the increased platelet retention. Analysis of polymorphic markers in the vWF gene demonstrated that a recessive mutation in this gene is unlikely.

Adolescent↗
PubMed1996

Increased platelet retention in familial recurrent thrombotic thrombocytopenic purpura.

We studied two brothers with recurrent thrombotic thrombocytopenic purpura (TTP). Platelet retention, measured with a modified Adeplat S glass-bead test, was found to be increased during acute episodes of TTP and during remissions. Values of platelet retention ranged between 57 to 95% (normal range 16 to 34%). The continually elevated values enabled us to investigate which fraction of the patients' blood was responsible for the increased platelet retention and to evaluate the effect of different treatments on this parameter. We found that the patients' plasma increased the retention of normal platelets and of platelets taken from a patient with von Willebrand's disease type III. This activity was located in the cryoprecipitate fraction of plasma. Unusually large von Willebrand factor (vWF) multimers were demonstrated in both children during remission and decreased during relapse. Both fresh frozen plasma (FFP) and a commercial factor VIII/vWF concentrate reduced platelet retention when tested during remission. Treatment of both siblings with FFP or factor VIII/vWF concentrate was beneficial during recurrences. We conclude that the elevated platelet retention is due to a factor in the cryoprecipitate of the childrens' plasma, and that both FFP and factor VIII/vWF concentrate are effective in decreasing platelet retention.

Adult↗
PubMed1995

Cytokines in childhood hemolytic uremic syndrome and thrombotic thrombocytopenic purpura.

Serum and urine cytokines were analyzed in children with hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). Interleukin-6 (IL-6) was elevated in the serum of 33 of 35 children with HUS (94%) and in 2 of 2 children with recurrent TTP. Serum IL-6 was higher in children with HUS who developed anuria, extrarenal manifestations during the acute phase of illness and/or chronic renal sequelae. Tumor necrosis factor-alpha (TNF-alpha) was detected in the serum of 7 patients with HUS (20%) and 1 patient with TTP. IL-6 and TNF-alpha were elevated in the urine of 4 of 4 children with HUS and 2 of 2 children with TTP. Urinary levels were higher than serum levels, suggesting local production of cytokines in the urinary tract. Sequential serum and urine samples showed that IL-6 levels varied with disease activity. IL-6 and TNF-alpha were not detected in the serum (n = 25) and urine (n = 15) of healthy children. We conclude that IL-6 in urine may be used to monitor disease activity in HUS and TTP.

Adolescent↗