Effect of platelet-activating factor (PAF) on human platelets

The effect of pure synthetic PAF (1-0-alkyl-2-acetyl-sn-glycero-3- phosphorylcholine) was studied in human platelets. PAF (0.2--2.0 micrograms/ml) produced a dose-dependent aggregation in human platelet- rich plasma (PRP) or platelet suspension obtained by gel-filtration (GFP). In addition, PAF (0.8 microgram/ml) induced secretion of 14C- serotonin (45% +/- 10%; mean +/- SD, n = 9) and platelet factor 4 (PF4) (12.89 +/- 3.81 micrograms/10(9) platelets; n = 9) in PRP. Similar results were obtained in GFP. Aggregation and release of 14C-serotonin and PF4 were inhibited by the metabolic inhibitors 2-deoxyglucose (16.7 mM) and antimycin-A (8.3 micrograms/ml), by the membrane-active drugs mepacrine (10 microM) and chlorpromazine (0.025 mM), by PGI2 (5.34 nM), which elevates intracellular c-AMP, by indomethacin (10 microM) or aspirin (100 microM). The ADP scavengers, creatine phosphate and creatine phosphokinase (CP/CPK), inhibited the second wave of aggregation but not secretion. These data suggest that the major effect of PAF on human platelets is mediated through the cyclo-oxygenase pathway and not through a third pathway.     

Red cell compatibility testing in baboon xenotransplantation

BACKGROUND: Although baboon ABO group and human anti-baboon heteroagglutinin (HA) titers have been considered in the selection of baboon donors for clinical hepatic xenotransplantation, the biologic role of these antibodies is not yet known. However, because of the potential importance of ABO hemagglutinins, a method for baboon ABO group determination is described, as are the titers of HA observed in both baboons and normal human donors. STUDY DESIGN AND METHODS: The ABO group of 62 baboons was determined by modified reverse typing. Baboon sera were heated and absorbed with human group O red cells. Reverse typing was then performed by standard techniques. HA titers at room temperature (RT) and in the antiglobulin test (AGT) were assessed in 10 baboons by using human red cells and in 33 normal donors by using baboon red cells. RESULTS: Ten (16%) baboons were group A, 29 (47%) were group B, 23 (37%) were group AB, and none were group O. In tests using human group O red cells, HA titers in 10 baboons ranged from 1 to 32 at RT and from negative to 64 in the AGT. All 33 normal human sera contained anti-baboon HA. Under a hemagglutination scoring system, group A persons had the lowest HA scores (17 +/− 15 at RT, 31 +/− 19 in the AGT), and group B persons had the highest HA scores (67 +/− 4 at RT, 85 +/− 9 in the AGT). CONCLUSION: Baboon ABO group can be easily determined by modified reverse serum typing. Both baboons and humans possess HAs of variable titer. Among humans, titers appear to be highest in group B individuals and lowest in group A. Additional studies are needed to determine the clinical significance of these antibodies.     

Antiplatelet agents for the prevention of pre-eclampsia

Pre-eclampsia (P-EC) remains a significant problem in modern obstetrics occurring in 2 to 4% of women. The disease is still responsible for 60,000 maternal deaths worldwide annually. An increased understanding of the underlying pathophysiology has resulted in a more scientific approach to prophylaxis and prevention, yet the underlying disease mechanisms are not fully understood. The role of combining good prediction with prevention has yet to be established but has the potential to target health resources far more efficiently. Good prediction may also impact on tailoring antenatal care appropriately, with prophylactic measures for high-risk women becoming the highly preferred management option. Antiplatelet agents reduce the incidence and complications of P-EC and should be considered prophylactically in those at high risk of the disease.     

The association of Triatoma maculata (Ericsson 1848) with the gecko Thecadactylus rapicauda (Houttuyn 1782) (Reptilia: Squamata: Gekkonidae): a strategy of domiciliation of the Chagas disease peridomestic vector in Venezuela?

Objective

To investigate the bioecological relationship between Chagas disease peridomestic vectors and reptiles as source of feeding.

Methods

In a three-story building, triatomines were captured by direct search and electric vacuum cleaner search in and outside the building. Then, age structure of the captured Triatoma maculata (T. maculata) were identified and recorded. Reptiles living in sympatric with the triatomines were also searched.

Results

T. maculata were found living sympatric with geckos (Thecadactylus rapicauda) and they bit residents of the apartment building in study. A total of 1 448 individuals of T. maculata were captured within three days, of which 74.2% (1 074 eggs) were eggs, 21.5% were nymphs at different stages, and 4.3% were adults.

Conclusions

The association of T. maculata and T. rapicauda is an effective strategy of colonizing dwellings located in the vicinity of the habitat where both species are present; and therefore, could have implications of high importance in the intradomiciliary transmission of Chagas disease.     

How placental growth factor detection might improve diagnosis and management of pre-eclampsia

Pre-eclampsia complicates around 5% of pregnancies and hypertensive disorders of pregnancy are responsible for over 60,000 maternal deaths worldwide annually. Identifying women with pre-eclampsia is a major goal of antenatal care in order to target increased surveillance, allow stabilizing therapies to be implemented and to enable timely delivery. Current risk assessment is based on clinical history, imperfect assessment of clinical signs (e.g., hypertension and proteinuria) and nonspecific biochemical markers, all of which are subject to considerable error. This is further confounded by underlying maternal disease such as chronic hypertension or renal pathology. Angiogenic factors reflect the underlying pathophysiology of pre-eclampsia and there is emerging evidence that they can now be used for more accurate risk assessment. The most promising of these factors include placental growth factor and soluble fms-like tyrosine kinase-1. Used at point of care, these can accurately discriminate true disease in suspected cases and subsequent need for delivery.