Platelet coagulation factor Va: the major secretory platelet phosphoprotein

Platelet-derived coagulation factor Va is the primary secreted substrate for a thrombin-stimulation-dependent platelet kinase. Human platelet factor Va, consisting of a molecular weight (M(r)) 105,000 heavy chain and an M(r) 74,000 light chain, incorporates phosphate in at least two sites on the light chain. Phosphorylated factor Va represents 50% of the secreted protein-associated phosphate. This modification occurs exclusively at serine residues and is inhibited by H-7 and staurosporine, which suggests a protein kinase C (PKC)-mediated event. Purified plasma factor V and Va are phosphorylated in the light chain region by rat brain PKC. The activity of platelet factor Va in prothrombinase on platelets is not altered when phosphorylation is inhibited by staurosporine. Plasma-derived factor Va in the presence of thrombin stimulated platelets is phosphorylated on both the heavy chain and the light chain. Plasma factor V and factor Va heavy chain phosphorylation occurs without light chain phosphorylation in the presence of added 32P gamma-ATP and non-stimulated or collagen- stimulated platelets or casein kinase II. This differential phosphorylation of factor Va heavy and light chain shows two independent platelet kinase activities that act on factor Va. The heavy chain factor V/Va kinase activity is similar to casein kinase II, which we have demonstrated previously to act on factor Va and accelerate activated protein C inactivation of the cofactor. Our data show platelet-dependent phosphorylation of platelet and plasma factor V and Va resulting in significant covalent modifications of the cofactor. These modifications may play a role in directing the extracellular distribution of factor V and factor Va.     

Synthesis of coagulation factor V by cultured aortic endothelium

Bovine aortic endothelium has been examined with respect to the synthesis of coagulation factor V. After cultured cells reached confluency, samples of supernatant culture media and solubilized cells were analyzed for factor V in a two-stage bioassay and in a double- antibody radioimmunoassay. In addition, preconfluent cells were pulsed for 4 days with 35S-methionine in methionine-free media. After the 4- day pulse, supernatant media were chromatographed on a factor V monoclonal antibody-Sepharose resin to isolate 35S-labeled factor V. The isolated material and 125I-factor V standards were analyzed by electrophoresis and autoradiography. The bioassay indicated an increase, with time, of unactivated factor V in the culture supernatant, whereas solubilized cells were negative for factor V. The radioimmunoassay indicated an increase, with time, of factor V antigen in the culture supernatants, and the solubilized cells yielded a constant level of antigen per cell. Autoradiograms of electrophoretograms of immunoadsorbed 35S-culture supernatant with 125I- factor V/Va standards revealed labeled proteins with electrophoretic mobilities compatible with 125I-factor V/Va standards. The data obtained from three different sources-bioassay, radioimmunoassay, and 35S-methionine incorporation-all indicate that factor V is synthesized by cultured bovine aortic endothelium.     

Indications for dual-chamber cardioverter defibrillators at implant and at 1 year follow-up: a retrospective analysis in the single-chamber defibrillator era.

AIM: This retrospective four-centre study assessed the current indications for dual-chamber implantable cardioverter defibrillators (ICDs) at implant and during a medium-term follow-up period in a group of patients treated by single-chamber ICD in the pre dual-chamber ICD era. METHODS AND RESULTS: The study population consisted of 153 consecutive patients (127 males, mean age 58 +/- 6 years) treated by single-chamber ICD for ventricular tachycardia and/or ventricular fibrillation. Definite indications for having a dual-chamber ICD included the presence of sinus node dysfunction and of second- or third-degree atrioventricular (AV) block, while possible indications were represented by paroxysmal atrial fibrillation or flutter and first-degree AV block. At implant, dual-chamber ICD would appear definitely indicated in 10.5% of cases, and possibly indicated in an additional 17.5% of cases. During 12 +/- 10 months follow-up, such percentages remained stable (11 and 19.5%, respectively). Inappropriate ICD intervention was documented in five of 13 patients (38%), with episodes of paroxysmal atrial fibrillation or flutter. CONCLUSION: In this non-selected study population, a dual-chamber ICD would have potentially benefited approximately 30% of the patients. During medium-term follow-up, there was no progression towards increasing dual-chamber ICD indications. The 15% cumulative incidence of paroxysmal atrial tachyarrhythmias justifies the activation of dedicated detection algorithms.     

Fatty acid synthase is required for the proliferation of human oral squamous carcinoma cells

Fatty acid synthase (FAS) is the enzyme responsible for the endogenous synthesis of saturated long-chain fatty acids from the precursors acetyl-CoA and malonyl-CoA. A growing body of evidence indicates that FAS is over expressed in several human cancers, such as prostate, breast, bladder, liver, lung, melanoma and oral squamous cell carcinoma (SCC). In the present study we used human oral SCC cell lines (SCC-4, -9, -15 and -25) as a model to investigate the role of FAS in the pathogenesis of oral cancer. RT-PCR and western blot experiments demonstrated that FAS is differentially expressed by the four oral SCC cell lines, with the highest production in SCC-9 followed by SCC-25. FAS expression in SCC-4 and -15 was similarly lower than the other cell lines. Proliferation curves and immunocytochemistry for PCNA and Ki-67 demonstrated that SCC-25 has the highest proliferative potential. In addition, the specific inhibitor of FAS activity cerulenin was able to significantly reduce the proliferation of oral SCC cells. Expression of androgen receptor was low in SCC-4, -9 and -15 and undetectable in SCC-25, whereas EGFR and c-erb-B2 were expressed in high amounts by the four cell lines. Immunocytochemical reactions showed that SCC-25 expresses higher levels of EGF compared to the other three cell lines. Finally, oral SCC cells exposed to nanomolar concentrations of exogenous EGF presented a reduction in the FAS protein levels concomitant with a decrease in their proliferation rates. Taken together, our results indicate that FAS is expressed in an apparently androgen-independent fashion in oral SCC cells and it is necessary for their proliferation.     

Prevalence of widespread pain and associations with work status: a population study

Background  

This population study based on a representative sample from a Swedish county investigates the prevalence, duration, and determinants of widespread pain (WSP) in the population using two constructs and estimates how WSP affects work status. In addition, this study investigates the prevalence of widespread pain and its relationship to pain intensity, gender, age, income, work status, citizenship, civil status, urban residence, and health care seeking.     

Verapamil-sensitive Ca2+ channel regulation of Th1-type proliferation of splenic lymphocytes induced by Walker 256 tumor development in rats

Recently, we demonstrated that verapamil, an L-type Ca2+ channel blocker, inhibits the activation of splenic lymphocytes during Walker 256 ascitic tumor development in adult rats. In the present study we have analyzed the changes in spleen size, splenic lymphocyte proliferation, white pulp organization and relative size as well as food intake, and levels of blood haemoglobin in Walker 256 tumor bearing rats. These rats displayed a spleen enlargement associated with a significant increase in white pulp area and TCD8+ lymphocyte proliferation. Levels of interferon-gamma, but not of interleukin-10, were elevated in tumor bearing rats, indicating a Th1-type immune response. These manifestations were accompanied by reduced food intake and anaemia. Treatment of tumor bearing rats with verapamil avoided spleen enlargement and increased expression of cytokines, as well as the splenic TCD8+ lymphocyte proliferation. In addition, verapamil treatment promoted an exacerbation of the anorexia and anaemia caused by Walker tumor development. No such effect was observed in control rats treated with verapamil. Taken together, these findings suggest that verapamil inhibits the immune response to cancer, resulting in an increase of the systemic effects induced by Walker 256 tumor.     

Trends in practice characteristics: analyses of 19 periodic surveys (1987-1992) of Fellows of the American Academy of Pediatrics

OBJECTIVE: To examine 6 years of practice characteristics data of Fellows of the American Academy of Pediatrics (AAP), focusing on sex differences for specialty area, primary activity, practice setting, and practice location. METHODS: We analyzed data from 19 Periodic Surveys that were fielded between 1987 and 1992. The Periodic Survey is used to survey AAP members regularly about current issues in pediatric practice. There are no duplicate respondents in these analyses of the first 19 Periodic Surveys. We collapsed the 19 surveys into the years in which they were fielded, and analyzed sex differences for each of the 6 years. In addition, we ran logistic regressions on several questions, including all 16 868 respondents, to examine how the characteristics of the specialty have been affected by the increase in the number of female pediatricians, controlling for survey year, age of respondents, and specialty area practiced. RESULTS: The proportion of nonresident AAP members who are female has grown throughout the 6 years; in 1987, 26.9% were female, and in 1992, 36.4% were female. For 5 of the 6 years there were sex differences in specialty area, usually concerning pediatric subspecialties. Substantial sex differences occurred in primary activity, in which each year women were more likely than men to be salaried. Men were more often in group practices, whereas women were generally more likely to practice in hospitals or clinics. Logistic regression demonstrated that there are sex differences in practice characteristics across time, but there is also a substantial change in practice characteristics accountable to survey year, eg, a pediatrician of either sex was 75% more likely to be salaried in 1992 than in 1987. CONCLUSIONS: Throughout the 6-year period, AAP members became increasingly more likely to practice general pediatrics, to be salaried, and to be younger-all effects independent of sex, all effects stronger for females. Rapid transformations in the health care system will likely reduce current sex differences in practice characteristics of the future.