A new method for determination of plasma homocystine by isotope dilution and electrospray tandem mass spectrometry.

A new analytical determination method of homocystine in human plasma has been developed. The method utilises liquid chromatography coupled to ionspray tandem mass spectrometry. Quantitative analysis was achieved using as an internal standard homocystine-d8. Mass spectrometer operated in the multiple reaction mode: homocystine and homocystine-d8 were detected through the transition from the precursor to the product ion (from m/z 269.3 to 90.0, and m/z 277.3 to 94.0, respectively). The method is extremely sensitive, with limit of detection in the range of 6 fmol/L. The interassay and intraassay coefficients of variation for homocystine were 6.22% and 3.4%, respectively. The accuracy for the added homocystine ranged from 85% to 110%. High specificity of tandem mass spectrometry coupled with a fast chromatographic process is suitable for a rapid and reliable assay of homocystine.

The COX-2 G/C -765 polymorphism may modulate the occurrence of cerebrovascular ischemia.

In the atherosclerotic plaque, cyclooxygenase-2 (COX-2) catalyzes prostaglandin E formation, which acts as a pro-atherogenic factor. A polymorphism, G/C -765, within the COX-2 promoter region modulates gene expression and the risk of cerebrovascular disease. We have evaluated the relation between COX-2 G/C -765 genotypes and the occurrence of cerebrovascular ischemia. We evaluated the COX-2 G/C -765 polymorphism in 110 consecutive patients with a documented history of acute ischemic cerebrovascular disease, in 110 age-matched and sex-matched subjects without such history, and in a general population (n = 324) from the same ethnical background. The frequency of the COX-2 -765C allele in patients [0.21; 95% confidence interval (CI), 0.16-0.26] was similar to those found in controls (0.28; 95% CI, 0.22-0.34) and in the general population (0.26; 95% CI, 0.23-0.29). Carriers of the CC genotype differed between patients (0.02; 95% CI, 0.00-0.05) and controls [0.10 (95% CI, 0.04-0.16), P = 0.019; odds ratio, 0.17 (95% CI, 0.04-0.79)] or the general population [0.08 (95% CI, 0.05-0.11), P = 0.023; odds ratio, 0.22 (95% CI, 0.05-0.95)]. In a multiple logistic regression analysis adjusted for confounding variables, smoking status (P < 0.001), atrial fibrillation (P = 0.004) and COX-2 G/C-765 polymorphism (P = 0.016) independently contributed to cerebrovascular ischemia, with CC carriers exhibiting a lower risk (odds ratio, 0.07; 95% CI, 0.01-0.61). Our data show an association between the COX-2 G/C-765 gene polymorphism and cerebrovascular ischemia, suggesting that the COX-2 gene is a susceptibility locus for the risk of cerebrovascular ischemic disease.

Protein Z levels and unexplained fetal losses.

We evaluated protein Z plasma levels in a group of women with fetal losses (n = 124) and compared them with those in a group of women (n = 60) with uneventful pregnancies. We found that protein Z deficiency is not associated with otherwise unexplained fetal losses.