Stat1-Dependent, p53-Independent Expression of p21(waf1) Modulates Oxysterol-Induced Apoptosis

7-Ketocholesterol (7kchol) is prominent in atherosclerotic lesions where apoptosis occurs. Using mouse fibroblasts lacking p53, p21(waf1), or Stat1, we found that optimal 7kchol-induced apoptosis requires p21(waf1) and Stat1 but not p53. Findings were analogous in a human cell system. Apoptosis was restored in Stat1-null human cells when wild-type Stat1 was restored. Phosphorylation of Stat1 on Ser(727) but not Tyr(701) was essential for optimum apoptosis. A neutralizing antibody against beta interferon (IFN-β) blunted Ser(727) phosphorylation and apoptosis after 7kchol treatment; cells deficient in an IFN-β receptor subunit exhibited blunted apoptosis. IFN-β alone did not induce apoptosis; thus, 7kchol-induced release of IFN-β was necessary but not sufficient for optimal apoptosis. In Stat1-null cells, expression of p21(waf1) was much less than in wild-type cells; introducing transient expression of p21(waf1) restored apoptosis. Stat1 and p21(waf1) were essential for downstream apoptotic events, including cytochrome c release from mitochondria and activation of caspases 9 and 3. Our data reveal key elements of the cellular pathway through which an important oxysterol induces apoptosis. Identification of the essential signaling events that may pertain in vivo could suggest targets for therapeutic intervention

Gender Differences in Physicians' Financial Ties to Industry: A Study of National Disclosure Data.

Academic literature extensively documents gender disparities in the medical profession with regard to salary, promotion, and government funded research. However, gender differences in the value of financial ties to industry have not been adequately studied despite industry's increasing contribution to income and research funding to physicians in the U.S.We analyzed publicly reported financial relationships among 747,603 physicians and 432 pharmaceutical, device and biomaterials companies. Demographic and payment information were analyzed using hierarchical regression models to determine if statistically significant gender differences exist in physician-industry interactions regarding financial ties, controlling for key covariates. In 2011, 432 biomedical companies made an excess of $17,991,000 in payments to 220,908 physicians. Of these physicians, 75.1$3,598.63, p<0.001) per person than men. Additionally, female physicians received significantly lower amounts for meals (-$41.80, p<0.001), education (-$1,893.14, p<0.001), speaker fees (-$2,898.44, p<0.001), and sponsored research (-$15,049.62, p=0.05). For total dollars, an interaction between gender and institutional reputation was statistically significant, implying that the differences between women and men differed based on industry's preference for an institution, with larger differences at higher reputation institutions.Female physicians receive significantly lower compensation for similarly described activities than their male counterparts after controlling for key covariates. As regulations lead to increased transparency regarding these relationships, efforts to standardize compensation should be considered to promote equitable opportunities for all physicians

Smooth muscle cell surface tissue factor pathway activation by oxidized low-density lipoprotein requires cellular lipid peroxidation

Abstract Tissue factor, which is expressed in vascular lesions, increases thrombin production, blood coagulation, and smooth muscle cell proliferation. We demonstrate that oxidized low-density lipoprotein (LDL) induces surface tissue factor pathway activity (ie, activity of the tissue factor:factor VIIa complex) on human and rat smooth muscle cells. Tissue factor messenger RNA (mRNA) was induced by oxidized LDL or native LDL; however, native LDL did not markedly increase tissue factor activity. We hypothesized that oxidized LDL mediated the activation of the tissue factor pathway via an oxidant-dependent mechanism, because antioxidants blocked the enhanced tissue factor pathway activity by oxidized LDL, but not the increased mRNA or protein induction. We separated total lipid extracts of oxidized LDL using high-performance liquid chromatography (HPLC). This yielded 2 major peaks that induced tissue factor activity. Of the known oxysterols contained in the first peak, 7α- or 7β-hydroxy or 7-ketocholesterol had no effect on tissue factor pathway activity; however, 7β-hydroperoxycholesterol increased tissue factor pathway activity without induction of tissue factor mRNA. Tertiary butyl hydroperoxide also increased tissue factor pathway activity, suggesting that lipid hydroperoxides, some of which exist in atherosclerotic lesions, activate the tissue factor pathway. We speculate that thrombin production could be elevated via a mechanism involving peroxidation of cellular lipids, contributing to arterial thrombosis after plaque rupture. Our data suggest a mechanism by which antioxidants may offer a clinical benefit in acute coronary syndrome and restenosis