Correlates of STI testing among vocational school students in the Netherlands

Background  

Adolescents are at risk for acquiring sexually transmitted infections (STIs). However, test rates among adolescents in the Netherlands are low and effective interventions that encourage STI testing are scarce. Adolescents who attend vocational schools are particularly at risk for STI. The purpose of this study is to inform the development of motivational health promotion messages by identifying the psychosocial correlates of STI testing intention among adolescents with sexual experience attending vocational schools.     

Phorbol esters sensitize platelets to activation by physiological agonists

Phorbol esters such as phorbol 12, 13-dibutyrate (PdBu; 40 to 200 nmol/L) or 12-O-tetradecanoyl phorbol 13-acetate (20 to 80 nmol/L) added to aspirinized platelet-rich plasma (PRP) 5 to 15 seconds prior to various platelet stimuli (epinephrine, ADP, prostaglandin endoperoxide analog U44069, collagen, PAF, or vasopressin) potentiate the rate and extent of aggregation and ATP secretion induced by those agonists. Platelet aggregation, but not secretion, is potentiated at low concentrations of agonists; platelet secretion is potentiated at higher concentrations of the platelet stimuli. Potentiation of platelet responses was also observed when the preincubation time with PdBu was extended to 12 minutes and also occurred in washed platelets. The potentiating effect of phorbol esters is not mediated by formation of arachidonate metabolites or by released ADP. The sensitizing effect of PdBu on platelet aggregation induced by epinephrine is unique, since in contrast to the other platelet stimuli it is also found at maximal concentrations of epinephrine and does not diminish with prolonged preincubation of platelets with PdBu. Activation of protein kinase C ranges from 20% to 80% over control after 1 to 10 minutes of platelet pretreatment with PdBu but dramatically increases after subsequent addition of a stimulus such as vasopressin. In contrast, agonist- induced myosin light chain phosphorylation is reduced after platelet pretreatment with PdBu. The results indicate that protein kinase C activation enhances platelet aggregation and dense granule secretion triggered by physiologic stimuli, although it desensitizes agonist- induced myosin light chain phosphorylation.     

Assessment of sperm chromatin condensation and ploidy status using flow cytometry correlates to fertilization,embryo quality and pregnancy following in vitro fertilization

Purpose  

Sperm flow cytometry (SFC) was used to evaluate the association of sperm chromatin condensation and ploidy with fertilization, embryo development, pregnancy and abortion rates following IVF.     

Preparation of factor IX deficient human plasma by immunoaffinity chromatography using a monoclonal antibody

A murine hybridoma clone is described that grows continuously in culture and produces a monoclonal antibody we have called Royal Free Monoclonal Antibody to factor IX No. 1 (RFF-IX/1). This has high affinity for a coagulation site on factor IX. RFF-IX/1 immobilised on sepharose can be used to deplete factor IX from normal human plasma. This immunoaffinity depleted plasma is indistinguishable from severe Christmas disease plasma and can be used as the substrate in a one stage coagulation assay for factor IX. The affinity column has high capacity and can be regenerated so that large scale production from normal plasma of factor IX deficient plasma as a diagnostic reagent is now feasible.     

Severe perinatal thrombosis in double and triple heterozygous offspring of a family segregating two independent protein S mutations and a protein C mutation

Molecular genetic and phenotypic analyses were performed in a highly unusual case of combined protein S and protein C deficiency manifesting in a family in which a child had died perinatally from renal vein thrombosis. Antenatal diagnosis in a second pregnancy was initially performed by indirect restriction fragment length polymorphism (RFLP) tracking using a neutral dimorphism within the PROS gene and served to exclude severe protein S deficiency. Am umbilical vein blood sample at 22 weeks gestation showed isolated protein C deficiency. This pregnancy proceeded to a full-term delivery without thrombotic complications. Molecular genetic analysis of the PROC and PROS gene segregating in the family then yielded one PROC gene lesion in the father and two PROS gene lesions, one in each parent. These lesions were shown to segregate with the respective deficiency states through the family pedigree. Analysis of DNA from paraffin-embedded liver tissue taken from the deceased child showed the presence of both PROS mutations, as well as the PROC mutation. Genotypic analysis of the second child showed a PROC mutation, but neither PROS mutation consistent with its possession of normal protein S levels and a low/borderline protein C level. Antenatal diagnosis was then performed in a third pregnancy by direct mutation detection. However, although the fetus carried only the paternal PROS and PROC gene lesions, the child developed renal thrombosis in utero. It may be that a further genetic lesion at a third locus still remains to be defined. Alternatively, the intrauterine development of thrombosis in this infant could have been caused, at least in part by a transplacental thrombotic stimulus arising in the protein S-deficient maternal circulation. This analysis may, therefore, serve as a warning against extrapolating too readily from genotype to phenotype in families with a complex thrombotic disorder.