ALBERT

Beschreibung: Platelet-associated C3 (PA-C3) was measured with a quantitative immunofluorescence assay. With this assay, PA-C3 levels were determined for 78 normal volunteers, 30 patients with immune thrombocytopenic purpura (ITP), and 20 patients with nonimmune thrombocytopenias. Platelet-associated IgG (PA-IgG) levels were also measured with our standard quantitative immunofluorescence assay. All patients with nonimmune thrombocytopenias and ITP in remission had normal PA-C3 levels. Twenty-four patients with active ITP were classified into 3 groups: 9 (38%) with increased PA-IgG and normal PA-C3 levels, 10 (42%) with elevated PA-C3 and PA-IgG levels, and 5 (20%) with increased PA-C3 values only. A direct correlation was found between PA-C3 and PA-IgG levels. PA-IgG levels were higher in the group of patients with elevated PA-C3 levels than in those with normal values. Platelet survival studied showed reduced survival times of 1.5--2.5 days for the 5 patients with elevated PA-C3 levels only. Elevated PA-C3 levels returned to normal in 7 ITP patients whose platelet counts increased in response to corticosteroid therapy or to splenectomy. Therefore, PA-C3 and PA-IgG assays can be used to identify patients with ITP, to follow their response to therapy, and to classify them into immunologic subgroups similar to red cell classification by Coombs'testing in immune hemolytic anemia.

Beschreibung: Moderate doses of ethanol were shown to induce a significant rise in prostacyclin (PGI2) concentration in cultures of endothelial cells derived from umbilical veins. Administration of 32 g of ethanol to six volunteers elevated plasma levels of PGI2 in parallel with those of blood alcohol. Although not specific for ethanol, this alcohol induced the largest change in PGI2. Withdrawal of the stimulant alcohol caused prompt reduction of the elevated prostacyclin to baseline values. The activity of ethanol appears to be due to a direct stimulation of cyclooxygenase. The release of [14C]arachidonic acid from prelabeled endothelial cells was decreased by ethanol. PGE2 production was also enhanced by exposure of endothelial cells to ethanol. The physiologic significance of these alcohol-induced changes in PGI2 levels remains to be established.

Beschreibung: Platelet-associated C3 (PA-C3) was measured with a quantitative immunofluorescence assay. With this assay, PA-C3 levels were determined for 78 normal volunteers, 30 patients with immune thrombocytopenic purpura (ITP), and 20 patients with nonimmune thrombocytopenias. Platelet-associated IgG (PA-IgG) levels were also measured with our standard quantitative immunofluorescence assay. All patients with nonimmune thrombocytopenias and ITP in remission had normal PA-C3 levels. Twenty-four patients with active ITP were classified into 3 groups: 9 (38%) with increased PA-IgG and normal PA-C3 levels, 10 (42%) with elevated PA-C3 and PA-IgG levels, and 5 (20%) with increased PA-C3 values only. A direct correlation was found between PA-C3 and PA-IgG levels. PA-IgG levels were higher in the group of patients with elevated PA-C3 levels than in those with normal values. Platelet survival studied showed reduced survival times of 1.5--2.5 days for the 5 patients with elevated PA-C3 levels only. Elevated PA-C3 levels returned to normal in 7 ITP patients whose platelet counts increased in response to corticosteroid therapy or to splenectomy. Therefore, PA-C3 and PA-IgG assays can be used to identify patients with ITP, to follow their response to therapy, and to classify them into immunologic subgroups similar to red cell classification by Coombs'testing in immune hemolytic anemia.

Beschreibung: The effect of fish oil administration on platelet function was studied in eight normal individuals, four men and four women, who received fish oil equivalent to 6 g eicosapentaenoic acid per day for a period of 25 days. Platelet aggregation, platelet adhesion, phospholipid and fatty acid distribution were measured at periodic intervals before, during, and after the period of fish oil administration. Platelet aggregation induced by arachidonic acid, adenosine diphosphate, and collagen showed a moderate increase in ED 50 in response to the administration of fish oil. Conversely, platelet adhesion to fibrinogen and collagen I, which was studied at low shear rates in a laminar flow chamber, showed a striking 60% to 65% decrease after fish oil supplementation of the diet. The change in adhesiveness could be correlated with the pseudopodia formed in response to agonistic stimulation. Scanning electron microscopic examination of adherent platelets showed an overall reduction of pseudopodia that appeared short and stubby on fish oil administration. The profile of the fatty acids extracted from plasma confirmed compliance of the volunteers with their dietary supplements. Analysis of phospholipids showed changes in sphingomyelin, lysophosphatidylcholine, and phosphatidylcholine between pseudopodia and platelet cell bodies. Fish oil administration did not affect their overall distribution except for a moderate decrease in phosphatidylethanolamine in platelet pseudopodia. Changes were also recognized in the total fatty acids extracted from platelets, affecting primarily arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. There were no changes in platelet adhesiveness in a group of five normal individuals who received a vegetable oil supplement of equal dose and duration as that of the fish oil. We conclude from these studies that fish oil, at least when administered over a limited period of time, is an effective inhibitor of platelet adhesiveness.

Beschreibung: Moderate doses of ethanol were shown to induce a significant rise in prostacyclin (PGI2) concentration in cultures of endothelial cells derived from umbilical veins. Administration of 32 g of ethanol to six volunteers elevated plasma levels of PGI2 in parallel with those of blood alcohol. Although not specific for ethanol, this alcohol induced the largest change in PGI2. Withdrawal of the stimulant alcohol caused prompt reduction of the elevated prostacyclin to baseline values. The activity of ethanol appears to be due to a direct stimulation of cyclooxygenase. The release of [14C]arachidonic acid from prelabeled endothelial cells was decreased by ethanol. PGE2 production was also enhanced by exposure of endothelial cells to ethanol. The physiologic significance of these alcohol-induced changes in PGI2 levels remains to be established.

Beschreibung: A quantitative immunofluorescence platelet-associated immunoglobulins (PA-IgG) assay was used to detect alloimmunity to platelets in 8/12 multitransfused patients and to perform platelet crossmatching in the 8 alloimmunized patients. The correct separation of multitransfused patients into alloimmune and nonalloimmune groups was substantiated with chromium-51-labeled platelet survival studies. For 5 alloimmunized patients, compatible and incompatible donor platelets were demonstrated by PA-IgG crossmatching and were confirmed by platelet survival studies. With the other 3 alloimmunized patients, only studies with 5 of these incompatible donor platelets showed markedly reduced survival times on 4 occasions. PA-Igg compatible donor platelets survived 3.5- 8.7 days, while PA-IgG incompatible platelets showed survival times of 0.1–2.4 days. Overall, PA-IgG testing correctly indicated survival results on 15/17 occasions (88%), whereas platelet aggregation, serotonin release, and lymphocytotoxicity testing showed correct predictions for only 41%-59% of the survival studies. PA-IgG testing predicted which times, thus indication patients with platelet-specific alloantibodies. the PA-IgG assay provides a sensitive method to detect platelet alloantibodies and to perform platelet crossmatching, which can complement HLA typing in the selection of donor platelets for alloimmunized patients.

Beschreibung: A quantitative immunofluorescence platelet-associated immunoglobulins (PA-IgG) assay was used to detect alloimmunity to platelets in 8/12 multitransfused patients and to perform platelet crossmatching in the 8 alloimmunized patients. The correct separation of multitransfused patients into alloimmune and nonalloimmune groups was substantiated with chromium-51-labeled platelet survival studies. For 5 alloimmunized patients, compatible and incompatible donor platelets were demonstrated by PA-IgG crossmatching and were confirmed by platelet survival studies. With the other 3 alloimmunized patients, only studies with 5 of these incompatible donor platelets showed markedly reduced survival times on 4 occasions. PA-Igg compatible donor platelets survived 3.5- 8.7 days, while PA-IgG incompatible platelets showed survival times of 0.1–2.4 days. Overall, PA-IgG testing correctly indicated survival results on 15/17 occasions (88%), whereas platelet aggregation, serotonin release, and lymphocytotoxicity testing showed correct predictions for only 41%-59% of the survival studies. PA-IgG testing predicted which times, thus indication patients with platelet-specific alloantibodies. the PA-IgG assay provides a sensitive method to detect platelet alloantibodies and to perform platelet crossmatching, which can complement HLA typing in the selection of donor platelets for alloimmunized patients.

Beschreibung: The effect of fish oil administration on platelet function was studied in eight normal individuals, four men and four women, who received fish oil equivalent to 6 g eicosapentaenoic acid per day for a period of 25 days. Platelet aggregation, platelet adhesion, phospholipid and fatty acid distribution were measured at periodic intervals before, during, and after the period of fish oil administration. Platelet aggregation induced by arachidonic acid, adenosine diphosphate, and collagen showed a moderate increase in ED 50 in response to the administration of fish oil. Conversely, platelet adhesion to fibrinogen and collagen I, which was studied at low shear rates in a laminar flow chamber, showed a striking 60% to 65% decrease after fish oil supplementation of the diet. The change in adhesiveness could be correlated with the pseudopodia formed in response to agonistic stimulation. Scanning electron microscopic examination of adherent platelets showed an overall reduction of pseudopodia that appeared short and stubby on fish oil administration. The profile of the fatty acids extracted from plasma confirmed compliance of the volunteers with their dietary supplements. Analysis of phospholipids showed changes in sphingomyelin, lysophosphatidylcholine, and phosphatidylcholine between pseudopodia and platelet cell bodies. Fish oil administration did not affect their overall distribution except for a moderate decrease in phosphatidylethanolamine in platelet pseudopodia. Changes were also recognized in the total fatty acids extracted from platelets, affecting primarily arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. There were no changes in platelet adhesiveness in a group of five normal individuals who received a vegetable oil supplement of equal dose and duration as that of the fish oil. We conclude from these studies that fish oil, at least when administered over a limited period of time, is an effective inhibitor of platelet adhesiveness.