Multimeric analysis in diagnosis of vWD variants in Indians.

von Willebrand disease is a common inherited bleeding disorder and the problem is undefined in developing countries due to limitation of its diagnostic facilities. The aim of the study was to diagnose vWD in patients with history of muco - cutaneous bleeding and characterization into its variants by multimeric analysis. 224 patients presenting with history of muco - cutaneous bleeding were selected. In all patients, platelet count, BT, PT, APTT, PF3 availability, clot solubility and factor VIII assay were done. Diagnosis of vWD was confirmed by RIPA, vWF: Ag, and vWF: RCo and its sub-characterization was done by multimeric analysis. 64 patients were diagnosed to have vWD. Of these, 21.9% were of type 1 vWD, 43.7% type 2 vWD, 1.6% acquired vWD and 32.8% type 3 vWD. By multimeric analysis, 2 patients had supranormal HMW multimers and two patients had normal distribution of vWF multimers were diagnosed as type 2M 'Vicenza'; and type 2M vWD respectively. It is concluded, that vWD is not an uncommon condition amongst Indian population.

Platelet-derived microparticles stimulate proliferation of granulocyte-macrophage progenitor cells from umbilical cord blood / 中国实验血液学杂志

This study was aimed to investigate the effect of platelet-derived microparticles (PMP) on stimulating the proliferation of granulocyte-macrophage progenitors (CFU-GM) from umbilical cord blood. Different concentrations of thrombin were adopted to activate the platelets for releasing PMP. Flow cytometry was adopted to evaluate the efficiencies of different concentrations of thrombin to produce PMP. Umbilical cord blood mononuclear cells (MNC) were obtained from healthy donors and the MNC were isolated by Ficoll density gradient centrifugation. MNC were cultured in 2.7% methylcellulose containing different concentration of PMP and colonies were counted under an inverted microscope after 7 days. The result showed that the release rate of PMP activated by 2.0, 1.5, 1.0 and 0.5 U/ml thrombin were 28.7%, 47.7%, 50.1% and 43.9% respectively. The PMP enhanced colony formation in dose-dependent manner. The number of colonies per 2 x 10(5) MNCs in groups of PMP at different concentrations (10, 50 and 100 microg/ml) were 119.8 +/- 32.2,142.8 +/- 45.2 and 180.8 +/- 85.1 respectively. The number of colonies in the groups of PMP at 100 microg/ml and 50 microg/ml were statistically significant when compared with control group (103.0 +/- 24.8) (P < 0.05). The number of colonies per 2 x 10(5) MNC in the group of PMP (10 microg/ml) was 119.8 +/- 32.2 which was higher than that in control group, but there was no statistical significance between two groups. It is concluded that platelet activated with 1.0 U/ml thrombin can get the best release efficiency of PMP and PMP can enhance the proliferation of granulocyte-macrophage progenitor cells of umbilical cord blood.

Sangrado en ataxia telangiectasia. Un aspecto de la enfermedad previamente no estudiado / Bleeding in ataxia telangiectasia. An aspect of this illness wich has not been previosly studied

En un paciente con ataxia-telangiectasia se demostró la presencia de una condición hemorrágica debida a alteraciones vasculares, defectos plaquetarios funcionales múltiples y deficiencia leve de factor IX. En la revisión de 128 pacientes con ataxia-telangiectasia se encontró que 7 habían sufrido hemorragias en ausencia de alguna enfermedad subyacente capaz de provocarlas. La presencia de trastornos semejantes a los descritos en el paciente, en síndrome de Ehlers-Danlos, en osteogénesis imperfecta y en telangiectasia hemorrágica hereditaria (condiciones que tiene en común con ataxia-telangiectasia, la existencia de alteraciones vasculares), permiten plantear la existencia de alguna forma de interrelación entre el desarrollo de vasos y la síntesis de algunos factores de la coagulación y la formación de plaquetas

PF3 activity in normal subjects and beta-thalassemia trait.

Platelet factor 3 (PF3) is a platelet membrane component that plays an important role in the activation of the coagulation mechanism. Whenever platelet activation occurred, PF3 is released and participates in thrombin formation. Erythrocyte membrane fraction has also some PF3 like activity, and in abnormal erythrocyte membrane disorders, eg thalassemia, some of the membrane fraction accelerates platelet activation by increasing the PF3 activity. Formerly it was difficult to measure the PF3 activity in plasma. Recently a sensitive chromogenic test to determine the PF3 activity, which could detect the changes in PF3 activity with time, was introduced. This study was done to observe the effect of abnormal erythrocyte on platelet activation. The results obtained using the chromogenic method are the following: whole blood taken from normal subjects showed OD 0.11 +/- 0.06 at 0 minutes after blood collection and then increased significantly (p < 0.01) to 0.21 +/- 0.10 after 90 minutes, while the platelet count did not differ significantly (p > 0.05). Those results showed that there were some platelet activation after 90 minutes as seen by the increased PF3 activity, with no significant change in platelet counts. In beta-thalassemic trait subjects the PF3 activity in whole blood at 0 minutes did not differ significantly compared to the normal subjects, but after 90 minutes it was significantly higher (p < 0.01), OD 0.52 +/- 0.35. However the PF3 in platelet rich plasma at 90 minutes did not increase. The platelet count after 90 minutes was significantly decreased (p < 0.01) This result suggest that the increase in PF3 activity was caused by the role of the abnormal erythrocytes.

Development of a new method for detection of platelet factor 3 like activity.

We asked the question, "Can thalassemic erythrocytes play some role in alteration of the hemostatic system?", because clinical examination of thalassemic patients shows symptoms and signs related to alterations in hemostatic and circulatory systems, and thalassemic erythrocytes are different from normal erythrocytes. We obtained one of the answers to the question: The erythrocytes of postsplenectomized patients of beta-thalassemia/HbE disease could stimulate their own platelets to aggregate spontaneously. To know the role of erythrocytes in platelet aggregation, we wanted to examine the effect of thalassemic erythrocytes on the coagulation system by focusing of PF3-like activity of erythrocytes, because PF3-like activity of the ghosts of erythrocytes had been reported. For the study, we tried to develop a technique that was accurate and sensitive enough to detect PF3-like activity of blood. The system we developed was the following: 1) We activated the intrinsic coagulation pathway of commercial standard plasma by ellagic acid. 2) CaCl2, a fixed amount of PF 3 and synthetic thrombin inhibitor MD 805 were added to the reaction mixture. 3) At a fixed time, thrombin activity in the mixture was measured by using S-2238 as a substrate. At full activation of the contact system by ellagic acid, the amount of thrombin formed in a certain time depended on the amount of PF3-like substances such as cephalin, freeze-thawed platelets or ghosts of erythrocytes added to the test system, indicating that PF3-like activity of those substances can be measured by the activity of thrombin generated in a fixed time.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of PF3 availability in whole blood from volunteers and beta-thalassemia/HbE patients: a promising method for prediction of thrombotic tendency.

The platelet factor 3 (PF 3) plays a very important role in activation of coagulation factors and is regarded to be available during activation of platelets. However, membrane fraction of erythrocytes is also shown to have PF 3-like activity, suggesting that the abnormal erythrocytes may accelerate the activation of platelet by forming thrombin on their abnormal membrane or by way of other factors of the abnormal erythrocytes, and may increase the availability of PF 3 in whole blood (WB). To examine this hypothesis, we developed a method for determination of PF 3 activity, because the method now available for the PF3 determination could not detect changes in PF 3 activity with time. The principles of our method were as follows: 1) The reaction system was adjusted so that the amount of thrombin generated in a fixed reaction time correlates with the amount of PF 3. 2) To avoid inhibition of thrombin activity by antithrombin III, a synthetic thrombin inhibitor, MD 805, was added to the system and the activity of thrombin generated was measured by synthetic thrombin substrate S-2238 using A405 as an indicator of the availability of PF3. The results obtained by the method were the following: WB taken from volunteers showed A405 of 0.12 +/- 0.02 at 30 minutes after blood collection and then the A405 increased to 0.27 +/- 0.03 at 90 minutes. However, one volunteer showed the value of 0.59 at 90 minutes, though the value at 30 minutes was 0.16. The platelet number in his WB did not change during the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemostatic profile in neonatal septicemia.

Hemostatic profile was studied in 25 full term non-asphyxiated neonates with blood culture-proven septicemia. Observations were compared with that of 25 healthy, non-asphyxiated, full term, birth weight and age-matched controls. Detailed coagulation tests & platelet studies were done in each of the 50 neonates by standard techniques. Hemostatic defects occurred in 96% of the septicemic neonates and none in the control group irrespective of the occurrence of clinical bleeding. The coagulation tests were deranged in 805 and platelet function tests in 92% of patients. These tests were significantly deranged in septicemic neonates as compared to control group.

Effect of variable doses of aspirin on platelet functions.

Serial platelet functions were studied after various single doses of aspirin (75 mg, 150 mg, 300 mg, and 600 mg) in 20 males. Clotting time and platelet counts remained unchanged. Significant deaggregation of platelets occurred only with 600 mg of aspirin. This persisted on day '3'. Platelet factor-3 release time was prolonged till day '3' with only 150 mg and 600 mg doses of aspirin. In view of these findings it appears that 600 mg aspirin given every 4th day is more suited for significant antiplatelet effect.

Platelet functions in children with rheumatic activity

A battery of investigations including platelet count, bleeding time, platelet aggregation, platelet adhesiveness, clot retraction, saolin-cephalin on platelet poor and platelet rich plasmas, and platelet factor 3 availability were performed on 65 children, 40 cases out of them with rheumatic activity and without heart failure, 14 cases with activity and heart failure 11 cases with quiescent rheumatic heart. The same procedures were done on 12 healthy children of matched age and sex as controls. Changes of platelet aggregation, platelet adhesiveness, clot retraction, kaalin-cephalin time in platelet rich and platelet poor plasmas, and platelet factor 3 availability were found in the first two groups. And changes in clot retraction and platelet factor 3 availability were more in children with heart failure. In the quiescent cases all were normal except platelet adhesiveness which remained enhanced. The results were discussed and a conclusion of adding drugs that decrease the adhesiveness of platelets as Diphyridamol was raised up

Functional platelet defects and their laboratory evaluation.

Primary diseases of platelet function include Glanzmann's thrombasthenia, hereditary platelet release abnormalities (storage pool disease and release defect), Bernard-Soulier giant platelet syndrome, and platelet factor 3 defects. Qualitative defects of platelets are associated with many diseases, notably of the liver and kidney, and with the use of many drugs, particularly aspirin.