Citations

In cultured endothelial cells, the antioxidant, l -ascorbic acid (vitamin C), increases nitric oxide synthase (NOS) enzyme activity via chemical stabilization of tetrahydrobiopterin. Our objective was to determine the effect of vitamin C on NOS function and tetrahydrobiopterin metabolism in vivo. Twenty-six to twenty-eight weeks of diet supplementation with vitamin C (1%/kg chow) significantly increased circulating levels of vitamin C in wild-type (C57BL/6J) and apolipoprotein E (apoE)–deficient mice. Measurements of NOS enzymatic activity in aortas of apoE-deficient mice indicated a significant increase in total NOS activity. However, this increase was mainly due to high activity of inducible NOS, whereas eNOS activity was reduced. Significantly higher tetrahydrobiopterin levels were detected in aortas of apoE-deficient mice. Long-term treatment with vitamin C restored endothelial NOS activity in aortas of apoE-deficient mice, but did not affect activity of inducible NOS. In addition, 7,8-dihydrobiopterin levels, an oxidized form of tetrahydrobiopterin, were decreased and vascular endothelial function of aortas was significantly improved in apoE-deficient mice. Interestingly, vitamin C also increased tetrahydrobiopterin and NOS activity in aortas of C57BL/6J mice. In contrast, long-term treatment with vitamin E (2000 U/kg chow) did not affect vascular NOS activity or metabolism of tetrahydrobiopterin. In vivo, beneficial effect of vitamin C on vascular endothelial function appears to be mediated in part by protection of tetrahydrobiopterin and restoration of eNOS enzymatic activity.

Activation of CD4+ T cells is governed by interplay between stimulatory and inhibitory receptors; predominance of stimulatory signals favors autoimmune reactions. In patients with rheumatoid arthritis, expression of the critical costimulatory molecule, CD28, is frequently lost. Instead, CD4+CD28null T cells express killer immunoglobulin-like receptors (KIRs) with a preferential expression of the stimulatory receptor, CD158j. The frequency of CD4+CD28null T cells in rheumatoid arthritis (RA) correlates with the risk for more severe disease. Moreover, the KIR2DS2 gene, which encodes for CD158j, is a genetic risk factor for rheumatoid vasculitis. CD158j signals through the adaptor molecule, KARAP/DAP12, to positively regulate cytotoxic activity in NK cells. However, the majority of CD4+CD28null T cell clones lacked the expression of KARAP/DAP12. Despite the absence of KARAP/DAP12, CD158j was functional and augmented interferon-γ production after T cell receptor stimulation. Cross-linking of CD158j resulted in selective phosphorylation of c-Jun NH2-terminal protein kinase (JNK) and its upstream kinase, MKK4 that led to the expression of ATF-2 and c-Jun, all in the absence of extracellular signal–regulated kinase (ERK)1/2 phosphorylation. Mutation of the lysine residue within the transmembrane domain of CD158j abolished JNK activation, suggesting that an alternate adaptor molecule was being used. CD4+CD28null T cells expressed DAP10 and inhibition of phosphatidylinositol 3-kinase, which acts downstream of DAP10, inhibited JNK activation; however, no interaction of DAP10 with CD158j could be detected. Our data suggest that CD158j in T cells functions as a costimulatory molecule through the JNK pathway independent of KARAP/DAP12 and DAP10. Costimulation by CD158j may contribute to the autoreactivity of CD4+CD28null T cells in RA.

Persistent spectral nonphotochemical hole-burning (NPHB) spectroscopy has recently been applied to dye molecules in cells. The sensitivity of NPHB to the nanoenvironment of the probe is well established. It has been shown that NPHB applied to bulk suspensions of cultured human cells can distinguish between normal and cancer cells. Thus, NPHB has potential as a diagnostic cancer tool. For this reason, the methodology is referred to as hole-burning imaging, by analogy with MRI. The optical dephasing time ( T 2 ) of the dye in hole-burning image replaces the proton T 1 relaxation time in MRI. In addition to the T 2 mode of operation, there are four other modes including measurement of the spectral hole growth kinetics (HGK). Reported here is that the selectivity and sensitivity of NPHB operating in the HGK mode allow for distinction between normal and carcinoma cells at the single-cell level. The ovarian cell lines are ovarian surface epithelial cells with temperature-sensitive large T antigens (analogously normal) and ovarian surface epithelial carcinoma (OV167) cells. The mitochondrial specific dye used was rhodamine 800 (Molecular Probes). This carbocationic dye is highly specific for the outer and inner membranes of mitochondria. In line with the results for bulk suspensions of the two cell lines, the hole-burning efficiency for OV167 cells was found to be significantly higher than that for normal cells. Theoretical analysis of the HGK data leads to the conclusion that the degree of structural heterogeneity for the probe–host configurations in OV167 cells is lower than in the normal cells. Possible reasons for this are given.

Endothelial dysfunction is a systemic disorder and a key variable in the pathogenesis of atherosclerosis and its complications. Current evidence suggests that endothelial status is not determined solely by the individual risk factor burden but rather, may be regarded as an integrated index of all atherogenic and atheroprotective factors present in an individual, including known as well as yet-unknown variables and genetic predisposition. Endothelial dysfunction reflects a vascular phenotype prone to atherogenesis and may therefore serve as a marker of the inherent atherosclerotic risk in an individual. In line with this hypothesis, dysfunction of either the coronary or peripheral vascular endothelium was shown to constitute an independent predictor of cardiovascular events, providing valuable prognostic information additional to that derived from conventional risk factor assessment. Interventions like risk factor modification and treatment with various drugs, including statins and angiotensin-converting enzyme inhibitors, may improve endothelial function and thereby, potentially prognosis. Hence, given its reversibility and granted the availability of a diagnostic tool to identify patients at risk and to control the efficacy of therapy in clinical practice, endothelial dysfunction may be an attractive primary target in the effort to optimize individualized therapeutic strategies to reduce cardiovascular morbidity and mortality.

Objective— This study was undertaken to examine the association between bicuspid aortic valve (BAV) and aortic dilatation in the community. The association between BAV and aortic dilatation has been reported predominantly in retrospective studies in patients mostly with valvular dysfunction or selected surgical patients from tertiary referral centers. An independent association of BAV and aortic dilatation in a community-based study has not been demonstrated. Methods and Results— In a geographically defined population of Olmsted County, Minnesota, residents with BAV (n=44, age 35±13 years) without hemodynamically significant obstruction or regurgitation and matched controls with normal tricuspid aortic valves were identified by transthoracic echocardiography. The two groups were compared with respect to measurements of the aorta. The BAV and control groups differed with respect to size of the aortic anulus (23.2±2.4 versus 21.6±2.4 mm; P =0.002), aortic sinus (33.5±4.6 versus 30.3±4.1 mm; P =0.0001), and proximal ascending aorta (33.3±6.5 versus 27.9±3.6 mm; P =0.0001). There was no difference in the size of the aortic arch (24.2±3.6 versus 25.3±3.4 mm; P =0.16). These differences were maintained when the groups were stratified by sex and blood pressure. The relationship between bicuspid aortic valve and aortic dilatation was maintained when adjusting for factors related to fluid mechanics and hemodynamics such as systolic blood pressure, diastolic blood pressure, left ventricular ejection time, and peak aortic valve velocity. Conclusions— In a community-based study, BAV is associated with an alteration of aortic dimensions even in the absence of hemodynamically significant aortic valve stenosis or regurgitation.

Purpose: Between February 1993 and September 1995, 739 patients with metastatic breast cancer were entered on an Intergroup trial (E1193) comparing doxorubicin (60 mg/m2), paclitaxel (175 mg/m2/24 h), and the combination of doxorubicin and paclitaxel (AT, 50 mg/m2 and 150 mg/m2/24 h, plus granulocyte colony-stimulating factor 5 mg/kg) as first-line therapy. Patients receiving single-agent doxorubicin or paclitaxel were crossed over to the other agent at time of progression. Patients and Methods: Patients were well balanced for on-study characteristics. Results: Responses (complete response and partial response) were seen in 36% of doxorubicin, 34% of paclitaxel, and 47% of AT patients (P = .84 for doxorubicin v paclitaxel, P = .007 for v AT, P = .004 for paclitaxel v AT). Median time to treatment failure (TTF) is 5.8, 6.0, and 8.0 months for doxorubicin, paclitaxel, and AT, respectively (P = .68 for doxorubicin v paclitaxel, P = .003 for doxorubicin v AT, P = .009 for paclitaxel v AT). Median survivals are 18.9 months for patients taking doxorubicin, 22.2 months for patients taking paclitaxel, and 22.0 months for patients taking AT (P = not significant). Responses were seen in 20% of patients crossing from doxorubicin → paclitaxel and 22% of patients crossing from paclitaxel → doxorubicin (P = not significant). Changes in global quality-of-life measurements from on-study to week 16 were similar in all three groups. Conclusion: (1) doxorubicin and paclitaxel, in the doses used here, have equivalent activity; (2) the combination of AT results in superior overall response rates and time to TTF; and (3) despite these results, combination therapy with AT did not improve either survival or quality of life compared to sequential single-agent therapy.