Platelet Functions in Cardiopulmonary Bypass Surgery

Background

Haemorrhage after Cardio Pulmonary Bypass (CPB) Surgery is a well recognised complication that leads to significant morbidity and mortality. The incidence varies between 5-25% depending upon the clinical situation. Several factors are implicated as causative but none have been precisely proved.

Methods

Our study was an attempt to evaluate the haemostatic defect with particular reference to platelet function abnormalities during cardio pulmonary bypass surgery, in order to reduce the morbidity and mortality associated with post CPB haemorrhage. Flow cytometric evaluation of different platelet glycoproteins like GPIb/IX, GPIIb/IIIa and GMP-140 was done.

Results

The marker expression showed deregulation during surgery which returned to base after bypass was terminated. In contrast, the cases with bleeding showed significant variation. P-Selectin (GMP 140) expression decreased progressively till 3^rd post-operative day showing lack of activation of platelets in cases of severe bleeding.

Conclusion

Longer duration of CPB initiates plasmin generation through heparin, which raises the PAI-1-tPA complex and thereby down regulating the functions of platelets. This suggests a link between duration of CPB, bleeding, platelet dysfunction and fibrinolysis. Hence serial estimations of the levels of GMP-140 and tPA can predict severe bleeding.Key Words: CardioPulmonary Bypass, Platelet dysfunction, flowcytometry, platelet glycoproteins, haemorrhage     

Organochlorine pesticide residues in human milk in the United Kingdom 1997 - 8

1 The concentrations of a range of organochlorine pesticide residues have been determined in 168 samples of human milk collected between January 1997 and May 1998 in the UK. 2 Of the 18 residues sought, only p,p'-DTT, p,p'-DDE, dieldrin, HCB, beta-HCH and gamma-HCH were detected. 3 The continuing trend of a reduction in the concentrations of these pesticide residues in human milk samples and in the percentage of human milk samples containing residues was seen. 4 Correlations between the concentrations of p,p'-DDE, dieldrin, HCB, beta-HCH and gamma-HCH and age were seen. 5 When compared to studies carried out in Europe over a similar time period, residues in this present study were shown to occur at similar or lower concentrations.     

Pneumocystis carinii pneumonia studied by gallium-67 scanning

The validity and reliability of gallium-67 (Ga-67) scanning for diagnosis and follow-up of Pneumocystis carinii pneumonia (PCP) were assessed in 34 patients thought to have pulmonary complications of acquired immunodeficiency syndrome (AIDS). Overall sensitivity was 94% and specificity 74%. Among patients with normal or equivocal chest radiographs at the time of admission, sensitivity was 86% and specificity 85%. The authors consider Ga-67 scanning a valid and reliable adjunct in the diagnosis of PCP in AIDS patients with respiratory symptoms when the chest radiograph is normal or equivocal.     

葛根素对高血压患者血浆内皮素和一氧化氮的影响

目的：检测正常人与高血压病（ＥＨ）患者血浆内皮素、一气体氮的变化及葛根素对其的干预效应。方法：ＥＨ对照组口服苯磺酸氨氯地平５ｍｇ／ｄ,或合和盐酸苯那普利１０ｍｇ／ｄ,每日一次,１５ｄ为一疗程。ＥＨ伍用治疗组同时合用５％ＧＮＳ２５０ｍｌ＋葛根素注射液４００ｍｇ静滴,两组治疗前后检测血浆ＥＴ、ＮＯ水平变化。结果：ＥＨ各组血浆ＥＴ较正常人组均显著增高（Ｐ〈０．０１）,血浆ＮＯ水平及ＮＯ／ＥＴ比值除轻度Ｅ     

Molecular basis of altered red blood cell membrane properties in Southeast Asian ovalocytosis: role of the mutant band 3 protein in band 3 oligomerization and retention by the membrane skeleton

Southeast Asian ovalocytosis (SAO) is an asymptomatic trait characterized by rigid, poorly deformable red cells that resist invasion by several strains of malaria parasites. The underlying molecular genetic defect involves simple heterozygous state for a mutant band 3 protein, which contains a deletion of amino acids 400 through 408, linked with a Lys 56-to-Glu substitution (band 3-Memphis polymorphism). To elucidate the contribution of the mutant SAO band 3 protein to increased SAO red blood cell (RBC) rigidity, we examined the participation of the mutant SAO band 3 protein in increased band 3 attachment to the skeleton and band 3 oligomerization. We found first that SAO RBC skeletons retained more band 3 than normal cells and that this increased retention preferentially involved the mutant SAO band 3 protein. Second, SAO RBCs contained a higher percentage of band 3 oligomer-ankyrin complexes than normal cells, and these oligomers were preferentially enriched by the mutant SAO protein. At the ultrastructural level, the increased oligomer formation of SAO RBCs was reflected by stacking of band 3-containing intramembrane particles (IMP) into longitudinal strands. The IMP stacking was not reversed by treating SAO RBCs in alkaline pH (pH 11), which is known to weaken ankyrin-band 3 interactions, or by removing the cytoplasmic domain of band 3 from SAO membranes with trypsin. Finally, we found that band 3 protein in intact SAO RBCs exhibited a markedly decreased rotational mobility, presumably reflecting the increased oligomerization and the membrane skeletal association of the SAO band 3 protein. We propose that the mutant SAO band 3 has an increased propensity to form oligomers, which appear as longitudinal strands of IMP and exhibit increased association with membrane skeleton. This band 3 oligomerization underlies the increase in membrane rigidity by precluding membrane skeletal extension, which is necessary for membrane deformation.