Publications

For both primary and secondary prevention of coronary heart disease (CHD), it is prudent to use strategies that are of proven benefit and that do not harm patients. In all women, these strategies include lifestyle approaches such as smoking avoidance, proper nutrition, and regular exercise. Lipid-lowering and blood pressure control with pharmacotherapy are indicated in women who do not meet target lipid or blood pressure levels with lifestyle interventions. For women with CHD, aspirin, beta-blockers, and angiotensin-converting enzyme inhibitors should be considered. Widespread under-use of established preventive therapies has been documented in women. These interventions should be emphasized in clinical practice. For secondary prevention of CHD in women, the American Heart Association (AHA) recommends against initiating hormone replacement therapy (HRT) based on studies that have shown no benefit and early harm. For patients with CHD already on HRT, the decision to continue or stop HRT should be based on established noncoronary benefits and risks and patient preference. There are insufficient data to suggest that HRT should be initiated for the sole purpose of primary prevention of CHD. Because the new AHA guidelines recommend placing significant weight on the noncardiac benefits and risks of HRT, it is important to become familiar with these noncardiac effects. It is also important to understand the evidence supporting the AHA's decision to recommend placing relatively less weight on the cardiac effects of HRT.

Previous studies in chondrogenic RCJ3.1C5.18 (C5.18) cells showed that growth of these cells at high extracellular Ca(2+) concentrations ([Ca(2+)](o)) reduced the expression of markers of early chondrocyte differentiation. These studies addressed whether raising [Ca(2+)](o) accelerates C5.18 cell differentiation and whether Ca(2+) receptors (CaRs) are involved in coupling changes in [Ca(2+)](o) to cellular responses. We found that high [Ca(2+)](o) increased expression of osteopontin (OP), osteonectin, and osteocalcin, all markers of terminal differentiation, in C5.18 cells and increased the production of matrix mineral. Overexpression of wild-type CaR cDNA in C5.18 cells suppressed proteoglycan synthesis and aggrecan RNA, two early differentiation markers, and increased OP expression. The sensitivity of these parameters to changes in [Ca(2+)](o) was significantly increased, as indicated by left-shifted dose-responses. In contrast, stable expression of a signaling-defective CaR mutant (Phe707Trp CaR) in C5.18 cells, presumably through dominant-negative inhibition of endogenous CaRs, blocked the suppression of aggrecan RNA levels and proteoglycan accumulation and the enhancement of OP expression by high [Ca(2+)](o). These data support a role for CaRs in mediating high [Ca(2+)](o)-induced differentiation of C5.18 cells.

Vascular endothelial growth factor (VEGF) promotes vascular permeability (VP) and neovascularization, and is required for development. We find that VEGF-stimulated Src activity in chick embryo blood vessels induces the coupling of focal adhesion kinase (FAK) to integrin alpha(v)beta5, a critical event in VEGF-mediated signaling and biological responsiveness. In contrast, FAK is constitutively associated with beta1 and beta3 integrins in the presence or absence of growth factors. In cultured endothelial cells, VEGF, but not basic fibroblast growth factor, promotes the Src-mediated phosphorylation of FAK on tyrosine 861, which contributes to the formation of a FAK/alpha(v)beta5 signaling complex. Moreover, formation of this FAK/alpha(v)beta5 complex is significantly reduced in pp60c-src-deficient mice. Supporting these results, mice deficient in either pp60c-src or integrin beta5, but not integrin beta3, have a reduced VP response to VEGF. This FAK/alpha(v)beta5 complex was also detected in epidermal growth factor-stimulated epithelial cells, suggesting a function for this complex outside the endothelium. Our findings indicate that Src can coordinate specific growth factor and extracellular matrix inputs by recruiting integrin alpha(v)beta5 into a FAK-containing signaling complex during growth factor-mediated biological responses.

PURPOSE

To investigate in vitro if P-glycoprotein (P-gp) transport can differentiate between antibiotic drugs exhibiting increased active renal clearance (CL(r)) in cystic fibrosis (CF) patients (i.e., dicloxacillin, trimethoprim) and drugs that do not exhibit this phenomenon (i.e.. cefsulodin, sulfamethoxazole).

METHODS

Transport studies were carried out in MDCK (wild type) and MDR1-MDCK (P-gp overexpressing) cells that were grown to confluence on Transwell inserts. [14C]-mannitol transport and transepithelial electrical resistance (TEER) were measured to validate the integrity of the cells. Drug concentrations were analyzed using HPLC.

RESULTS

Dicloxacillin and trimethoprim are substrates of P-gp (B-->A/A-->B ratios in MDR1-MDCK cells are 32 and 50, respectively). P-gp inhibitors (i.e., GG918, cyclosporine, ketoconazole, vinblastine) decreased the B-->A transport of dicloxacillin and trimethoprim and increased the A-->B transport of trimethoprim while non-P-gp inhibitors (e.g., PAH) had no effect. In contrast, cefsulodin and sulfamethoxazole are not substrates of P-gp (B-->sA/A-->B values in MDCK and MDR1-MDCK cells are -1).

CONCLUSIONS

Our in vitro studies suggest that P-glycoprotein may play a role in increasing renal clearance of drug substrates in CF patients. Dicloxacillin and trimethoprim. which are both substrates of P-gp, show increased active renal clearance in CF patients while cefsulodin and sulfamethoxazole, which are not P-gp substrates, do not show increased active renal clearance in CF patients.

BACKGROUND

Cardiac transplantation is associated with oxidant stress, which may contribute to the development of accelerated coronary arteriosclerosis. We postulated that treatment with antioxidant vitamins C and E would retard the progression of transplant-associated arteriosclerosis.

METHODS

In a double-blind prospective study, 40 patients (0-2 years after cardiac transplantation) were randomly assigned vitamin C 500 mg plus vitamin E 400 IU, each twice daily (n=19), or placebo (n=21) for 1 year. The primary endpoint was the change in average intimal index (plaque area divided by vessel area) measured by intravascular ultrasonography (IVUS). Coronary endothelium-dependent vasoreactivity was assessed with intracoronary acetylcholine infusions. IVUS, coronary vasoreactivity, and vitamin C and E plasma concentrations were assessed at baseline and at 1 year follow-up. All patients received pravastatin. Analyses were by intention to treat.

FINDINGS

Vitamin C and E concentrations increased in the vitamin group (vitamin C 43 [SD 21] to 103 [43] mmol/L; vitamin E 24 [14] to 65 [27] mmol/L) but did not change in the placebo group (vitamin C 45 [15] vs 43 [16] mmol/L; vitamin E 27 [14] vs 27 [9] mmol/L; p<0.0001 for difference between groups). During 1 year of treatment, the intimal index increased in the placebo group by 8% (SE 2) but did not change significantly in the treatment group (0.8% [1]; p=0.008). Coronary endothelial function remained stable in both groups.

INTERPRETATION

Supplementation with antioxidant vitamins C and E retards the early progression of transplant-associated coronary arteriosclerosis.