Publications

Tidal volume reduction during mechanical ventilation reduces mortality in patients with acute lung injury and the acute respiratory distress syndrome. To determine the mechanisms underlying the protective effect of low tidal volume ventilation, we studied the time course and reversibility of ventilator-induced changes in permeability and distal air space edema fluid clearance in a rat model of ventilator-induced lung injury. Anesthetized rats were ventilated with a high tidal volume (30 ml/kg) or with a high tidal volume followed by ventilation with a low tidal volume of 6 ml/kg. Endothelial and epithelial protein permeability were significantly increased after high tidal volume ventilation but returned to baseline levels when tidal volume was reduced. The basal distal air space fluid clearance (AFC) rate decreased by 43% (P < 0.05) after 1 h of high tidal volume but returned to the preventilation rate 2 h after tidal volume was reduced. Not all of the effects of high tidal volume ventilation were reversible. The cAMP-dependent AFC rate after 1 h of 30 ml/kg ventilation was significantly reduced and was not restored when tidal volume was reduced. High tidal volume ventilation also increased lung inducible nitric oxide synthase (NOS2) expression and air space total nitrite at 3 h. Inhibition of NOS2 activity preserved cAMP-dependent AFC. Because air space edema fluid inactivates surfactant and reduces ventilated lung volume, the reduction of cAMP-dependent AFC by reactive nitrogen species may be an important mechanism of clinical ventilator-associated lung injury.

Brain natriuretic peptide (BNP) gene expression is a well documented marker of hypertrophy in the cardiac myocyte. Triiodothyronine (T(3)), the bioactive form of thyroid hormone, triggers a unique form of hypertrophy in cardiac myocytes that accompanies the selective activation or suppression of specific gene targets. In this study, we show that the BNP gene is a target of T(3) action. BNP secretion was increased 6-fold, BNP mRNA levels 3-fold, and BNP promoter activity 3-5-fold following T(3) treatment. This was accompanied by an increase in myocyte size, sarcomeric organization, and protein synthesis. Of note, several of the responses to T(3) synergized with those to the conventional hypertrophic agonist endothelin. The response to the liganded thyroid hormone receptor (TR) was mediated by an unusual thyroid hormone response element located between -1000 and -987 relative to the transcription start site. Both TR homodimers and TR.retinoid X receptor heterodimers associated with this element in an electrophoretic mobility shift assay. Protein fragments harboring the LXXLL motifs of the coactivators GRIP1 and SRC1 or TRAP220 interacted predominantly with the TR.retinoid X receptor heterodimeric pair in a ligand-dependent fashion. Both TR homodimers and heterodimers in the unliganded state selectively associated with glutathione S-transferase-nuclear receptor corepressor fragments harboring one of three receptor interaction domains containing the sequence (I/L)XX(I/V)I. These interactions were dissociated following the addition of T(3). Collectively, these findings identify the BNP gene as a potential model for the investigation of TR-dependent gene regulation in the heart.

BACKGROUND

Moderate alcohol intake has been associated with lower cardiovascular mortality. However, data evaluating the relationship between C-reactive protein (CRP), a predictor of cardiovascular risk, and alcohol consumption are sparse.

METHODS AND RESULTS

The relationship between alcohol consumption and CRP was evaluated in a cross-sectional survey and over time among 1732 men and 1101 women participating in the Pravastatin Inflammation/CRP Evaluation Study. CRP levels were lower in those with moderate alcohol intake versus light or occasional intake: in 5 categories of alcohol intake (no alcohol or <1 drink monthly, 1 to 3 drinks monthly, 1 to 4 drinks weekly, 5 to 7 drinks weekly, and > or =2 drinks daily), median CRP levels were 2.60 mg/L (interquartile range (IQR), 1.20 to 5.30 mg/L), 2.20 mg/L (IQR, 1.00 to 4.40 mg/L), 1.70 mg/L (IQR, 0.80 to 3.80 mg/L), 1.60 mg/L (IQR, 0.80 to 3.30 mg/L), and 1.80 mg/L (IQR, 0.80 to 2.90 mg/L), respectively. This relationship was present among men, women not taking hormone replacement therapy, nonsmokers, and those individuals with and without a history of cardiovascular disease (all P<0.001). In multivariate analysis, the relationship between alcohol consumption and CRP remained significant after controlling for multiple traditional cardiovascular risk factors. Alcohol consumption did not significantly affect the change in CRP or lipid levels associated with statin use.

CONCLUSION

Moderate alcohol consumption was associated with lower CRP concentrations than no or occasional alcohol intake, an effect that was independent of alcohol-related effects on lipids. Alcohol may attenuate cardiovascular mortality in part through an anti-inflammatory mechanism.