Phosphorylation of factor Va and factor VIIIa by activated platelets

Platelet activation leads to the incorporation of 32[PO4(2-)] into bovine coagulation factor Va and recombinant human factor VIII. In the presence of the soluble fraction from thrombin-activated platelets and (gamma-32P) adenosine triphosphate, radioactivity is incorporated exclusively into the M(r) = 94,000 heavy chain (H94) of factor Va and into the M(r) = 210,000 to 90,000 heavy chains as well into the M(r) = 80,000 light chain of factor VIII. Proteolysis of the purified phosphorylated M(r) = 94,000 factor Va heavy chain by activated protein C (APC) gave products of M(r) = 70,000, 24,000, and 20,000. Only the intermediate M(r) = 24,000 fragment contained radioactivity. Because the difference between the M(r) = 24,000 and M(r) = 20,000 fragments is located on the COOH-terminal end of the bovine heavy chain, phosphorylation of H94 must occur within the M(r) = 4,000 peptide derived from the carboxyl-terminal end of H94 (residues 663 through 713). Exposure of the radioactive factor VIII molecule to thrombin ultimately resulted in a nonradioactive light chain and an M(r) = 24,000 radioactive fragment that corresponds to the carboxyl-terminal segment of the A1 domain of factor VIII. Based on the known sequence of human factor VIII, phosphorylation of factor VIII by the platelet kinase probably occurs within the acidic regions 337 through 372 and 1649 through 1689 of the procofactor. These acidic regions are highly homologous to sequences known to be phosphorylated by casein kinase II. Results obtained using purified casein kinase II gave a maximum observed stoichiometry of 0.6 mol of 32[PO4(2-)]/mol of factor Va heavy chain and 0.35 mol of 32[PO4(2-)]/mol of factor VIII. Phosphoamino acid analysis of phosphorylated factor Va by casein kinase II or by the platelet kinase showed only the presence of phosphoserine while phosphoamino acid analysis of phosphorylated factor VIII by casein kinase II showed the presence of phosphothreonine as well as small amounts of phosphoserine. The platelet kinase responsible for the phosphorylation of the two cofactors was found to be inhibited by several synthetic protein kinase inhibitors. Finally, partially phosphorylated factor Va was found to be more sensitive to APC inactivation than its native counterpart. Our findings suggest that phosphorylation of factors Va and VIIIa by a platelet casein kinase II- like kinase may downregulate the activity of the two cofactors.     

Family history of diabetes and risk of atherosclerotic cardiovascular disease in Korean men and women

The importance of family history of type 2 diabetes (FHD) as a risk factor for atherosclerotic cardiovascular disease (ASCVD) remains controversial. A report of diabetes in parents and siblings was used to establish FHD in a cohort of 1,005,230 Koreans aged 30-95 years insured by the National Health Insurance Corporation who had a biennial medical evaluation during 1992-1995. ASCVD morbidity and mortality from 1993 to 2005 were examined in relation to FHD and other ASCVD risk factors. The risk of ischemic heart disease (IHD) increased significantly (19%) in men with FHD but not in women. A strong interaction was observed between FHD and personal history of diabetes for the occurrence of ASCVD; men with both diabetes and FHD were at significantly increased risk of developing IHD, cerebrovascular disease and ASCVD with hazard ratios (HR) of 2.28, 2.07, and 2.12, respectively, compared to those who had neither FHD nor type 2 diabetes. Corresponding risks were 2.64, 2.03, and 2.10 in women, respectively. This study demonstrates that risk of ASCVD is increased among those with diabetes and a family history of diabetes; suggesting that genetic factors associated with occurrence of familial diabetes may increase risk of ASCVD beyond the risk among people without FHD.     

Sugar-sweetened soft drinks, diet soft drinks, and serum uric acid level: the Third National Health and Nutrition Examination Survey

OBJECTIVE: Sugar-sweetened soft drinks contain large amounts of fructose, which may significantly increase serum uric acid levels and the risk of gout. Our objective was to evaluate the relationship between sugar-sweetened soft drink intake, diet soft drink intake, and serum uric acid levels in a nationally representative sample of men and women. METHODS: Using data from 14,761 participants age>or=20 years from the Third National Health and Nutrition Examination Survey (1988-1994), we examined the relationship between soft drink consumption and serum uric acid levels using linear regression. Additionally, we examined the relationship between soft drink consumption and hyperuricemia (serum uric acid level>7.0 mg/dl for men and >5.7 mg/dl for women) using logistic regression. Intake was assessed by a food-frequency questionnaire. RESULTS: Serum uric acid levels increased with increasing sugar-sweetened soft drink intake. After adjusting for covariates, serum uric acid levels associated with sugar-sweetened soft drink consumption categories (<0.5, 0.5-0.9, 1-3.9, and >or=4 servings/day) were greater than those associated with no intake by 0.08, 0.15, 0.33, and 0.42 mg/dl, respectively (95% confidence interval 0.11, 0.73; P<0.001 for trend). The multivariate odds ratios for hyperuricemia according to the corresponding sweetened soft drink consumption levels were 1.01, 1.34, 1.51, and 1.82, respectively (P=0.003 for trend). Diet soft drink consumption was not associated with serum uric acid levels or hyperuricemia (multivariate P>0.13 for trend). CONCLUSION: These findings from a nationally representative sample of US adults suggest that sugar-sweetened soft drink consumption is associated with serum uric acid levels and frequency of hyperuricemia, but diet soft drink consumption is not.