The first ambulatory screening on thromboembolism: a multicentre, cross-sectional, observational study on risk factors for venous thromboembolism.

OBJECTIVES: To assess the prevalence of risk factors for venous thromboembolism (VTE) and the prevalence of recent (<1 year) VTE [including superficial vein thrombosis (SVT), deep vein thrombosis (DVT) and pulmonary embolism (PE)] amongst patients attending general practitioner (GP) surgeries. DESIGN: Multicentre, cross-sectional, observational study. SETTING: A total of 1536 GP surgeries. PARTICIPANTS: A total of 15 180 adult, co-operative subjects, who had consulted their GP for a health disorder and signed the informed consent form. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Prevalence of known VTE risk factors graded according to importance and prevalence of recent (<1 year) VTE events (including SVT), based on interviews. RESULTS: About 1:5 patients had at least one strong risk factor and about 1:20 had at least two risk factors, with no difference between sexes. The prevalence of strong risk factors increased with age. Most were related to medical conditions: history of SVT and/or DVT/PE, heart failure and malignancy. About 3:4 women and 2:3 men had at least one moderate to weak risk factor; nearly 1:2 women and 1:3 men had at least two moderate to weak risk factors. The most common were: history of VTE, smoking, history of miscarriage, estrogen therapy, obesity, and varicose veins. Overall, 80% women and 67% men had at least one risk factor, and 50% women and 35% men had at least two risk factors. The prevalence of recent (<1 year) VTE was 3.4% in women and 2.4% in men, and increased with age. The majority of cases were SVT in both sexes (2.5% in women and 1.5% in men). CONCLUSIONS: The prevalence of risk factors for VTE amongst patients attending GP surgeries is high. GPs should bear this in mind during their daily practice.

Association of a polymorphism in the Apo AI gene promoter with hyperalphalipoproteinemia.

The distribution of a polymorphism due to an Adenine to Guanine transition in the ApoAI gene has been studied in 136 women and 108 men, through amplification of the promoter region of the gene and allele-specific oligonucleotide hybridization. The allelic frequencies for the A allele were 0.10, 0.14 and 0.27 in women and 0.08, 0.17 and 0.14 in men for the lowest decile, intermediate group and the highest decile of HDL-cholesterol levels, respectively. Statistical analysis showed that the A allele was associated with high HDL-cholesterol levels in women, but not in men.

Free radicals promote modifications in plasma high-density lipoprotein: nuclear magnetic resonance analysis.

The behavior of high-density lipoprotein (HDL) after free-radical-mediated oxidation was studied by incubating plasma HDL with chemical oxidizing systems (Cu++) in conditions similar to those used for low-density lipoprotein (LDL) chemical oxidation. Nuclear magnetic resonance (NMR) spectroscopy (1H and 31P) was used to evaluate the degree of oxidation and to characterize the oxidized products. The almost complete loss of polyunsaturated systems together with an appreciable decrease in choline peak demonstrates large-scale HDL-lipid degradation. The appearance of epoxide systems on fatty chains and the identification of oxidized cholesterol derivatives as cholesterol 5 alpha,6 alpha-epoxide, 5 beta,6 beta-epoxide, 7-keto, and 25-hydroxy confirm this picture. Phospholipid analysis indicates an alteration of the phospholipid profile in lyso-phosphatidylcholine (Lyso-PC) production and the disappearance of phosphatidylethanolamine (PE). This study shows that HDL is extensively degraded although there are no large variations in the classical oxidative monitors, lipid hydroperoxide (LPO) and thiobarbituric acid reactive substance (TBARS). Our results suggest that HDL is significantly modified when submitted to an oxidative process.

Determination of Lp(a) and APO(a) in an Italian population.

Plasma lipoprotein(a) [Lp(a)] levels were determined in an Italian population subdivided according to age and sex. The distribution of plasma Lp(a) levels was highly skewed, with 75% of the subjects having less than 10 mg/dl. No significant differences were found in the plasma Lp(a) levels of the two age groups, but women had significantly higher levels than men. There was no significant correlation between Lp(a) levels and the other lipid and lipoprotein parameters studied, with the exception of a weak correlation between Lp(a) levels and both total cholesterol and low density lipoprotein-cholesterol in younger women. Apoprotein(a) phenotyping was performed in about one-third of the population; an inverse relationship between the molecular weight of the different isoforms and plasma concentrations of Lp(a) was observed.

Human apolipoprotein A-I gene promoter polymorphism: association with hyperalphalipoproteinemia.

An apolipoprotein A-I gene promoter polymorphism, due to an adenine (A) to guanine (G) transition 78 base pairs upstream from the transcription initiation site, was studied by amplification of the corresponding region of the apoA-I gene, DNA sequencing, and allele-specific oligonucleotide hybridization. The frequency of the polymorphism was studied on female and male individuals classified into three groups according to the high density lipoprotein (HDL) cholesterol concentration. The allelic frequencies for the A polymorphism were 0.10, 0.14, 0.27 in women and 0.08, 0.17, 0.14 in men in the lowest, in the intermediate (between 10th and 90th percentile), and the highest decile of HDL cholesterol levels, respectively. Statistical analysis showed a significant difference of allelic frequencies between the highest and the lowest deciles (P less than 0.006) and between the highest and the intermediate deciles of HDL cholesterol in women (P less than 0.04) but not in men. As the sequences surrounding the polymorphism are known to be involved in transcription modulation, it is possible that the A-G transition polymorphism may have an influence on apoA-I synthesis and, in consequence, on the HDL cholesterol levels in women.

NMR analysis of low-density lipoprotein oxidatively-modified in vitro.

Human plasma low density lipoprotein has been oxidized at different stages in vitro and analysed by 1H, 13C, and 31P NMR spectroscopy and by biochemical methods. Information was obtained on: a) structure mobilities of lipids and on lipid-protein interactions; b) conjugated and oxo-dienes; c) polyunsaturated/monounsaturated fatty acid chains; d) lysophosphatidylcholine production. The results show that the NMR approach is particularly useful for the assessment of structural modification in oxidized LDL.