Chronic exposure to carbon monoxide and nicotine: endothelin ET(A) receptor antagonism attenuates carbon monoxide-induced myocardial hypertrophy in rat.

The aims of the present study were to determine the effects of endothelin ET(A) receptor antagonism on carbon monoxide (CO)-induced cardiac hypertrophy and endothelin-1 (ET-1) expression and to compare myocardial effects of chronic nicotine with CO exposure. Female Sprague-Dawley rats (n = 84) were randomized to three groups exposed 20 h/day to CO (200 ppm), nicotine (500 microg/m3), or air for 14 consecutive days. In each exposure group, animals were randomized to ET(A) receptor antagonist LU 135252 in drinking water (0.5 mg/ml) or placebo. Myocardial ET-1 and atrial natriuretic peptide (ANP) expression was measured by competitive RT-PCR and plasma ET-1 by immunoassay. Carboxyhemoglobin was 22.1 +/- 0.3% in CO-exposed animals and 2.8 +/- 0.3% in controls. Plasma nicotine was 57 +/- 7 ng/ml and plasma cotinine was 590 +/- 23 ng/ml in nicotine-exposed animals and below detection levels in controls. CO exposure induced a 21% increase in right ventricular hypertrophy (p < 0.01), a 7% increase in left ventricular hypertrophy (p < 0.01), a 25% increase in right ventricular ET-1 expression (p < 0.05), and an eightfold increase in ANP expression (p = 0.08). ET(A) receptor antagonism reduced right ventricular hypertrophy by 60% (p < 0.05) with no significant effect on left ventricular hypertrophy or myocardial ET-1 expression. Chronic nicotine exposure did not significantly affect cardiac weights or ANP and ET-1 expression. We conclude that ET(A) receptor antagonism reduces right ventricular hypertrophy induced by chronic CO exposure, whereas CO-induced myocardial ET-1 expression remains unchanged.     

Low-dose preoperative radiation postpones recurrences in operable rectal cancer. Results of a randomized multicenter trial in western Norway

A randomized, multicenter clinical trial was conducted in Western Norway to study the effectiveness of preoperative radiation therapy in operable rectal cancer, given at a dosage of 3150 cGy in 18 fractions, 2 to 3 weeks before radical surgery. Three hundred nine patients were entered into the trial between May 1976 and December 1985. After radiation no tumor was seen in 4.5% of the patients. There was no increased morbidity or mortality at surgery. The 5-year survival for evaluable patients was 57.5% in the control group and 56.7% in the radiotherapy group. For patients operated on for cure the 5-year survival was 60.9% and 64.2% in the control group and radiotherapy group, respectively. Radiation significantly delayed both local and distant recurrences in patients in the radiation group who had curative resection from 13.3 months in controls to 27.1 months. The local recurrence rate in the corresponding groups was 21.1% and 13.7%, respectively. We conclude that higher preoperative radiation doses should be used in new trials as a higher dosage may transform the observed positive effects into a survival benefit.