Endogenous testosterone and the prospective association with carotid atherosclerosis in men: the Tromsø study.

The role of testosterone in the development of cardiovascular disease is controversial. Recent observational studies, however, suggest a protective role of normal endogenous testosterone levels in the development of atherosclerosis. In a cohort from the Tromsø study, 1,101 men had both hormone-levels measured and the right carotid artery examined by ultrasound in 1994 and 2001. We studied the prospective association between sex hormone-levels and progression of carotid intima-media thickness (IMT) and plaque area from 1994 to 2001. We also performed a cross-sectional study of 2,290 men from the population in 2001. The data were analysed by univariate correlations, analyses of covariance and multiple linear regression analyses. In the cross-sectional study, we found an inverse association between testosterone levels and total carotid plaque area (P < 0.05), after adjusting for age, systolic blood pressure, smoking and use of lipid-lowering drugs. We found no prospective associations between sex hormone-levels and change in plaque area or IMT from 1994 to 2001. The lack of prospective associations in our study may be due to increased use of anti-hypertensive and lipid-lowering drugs from 1994 baseline to follow-up.

The 118 A > G polymorphism in the human mu-opioid receptor gene may increase morphine requirements in patients with pain caused by malignant disease.

BACKGROUND: Dispositions for genes encoding opioid receptors may explain some variability in morphine efficacy. Experimental studies show that morphine and morphine-6-glucuronide are less effective in individuals carrying variant alleles caused by the 118 A > G polymorphism in the mu-opioid receptor gene (OPRM1). The purpose of the study was to investigate whether this and other genetic polymorphisms in OPRM1 influence the efficacy of morphine in cancer pain patients. METHODS: We screened 207 cancer pain patients on oral morphine treatment for four frequent OPRM1 gene polymorphisms. The polymorphisms were the -172 G > T polymorphism in the 5'untranslated region of exon 1, the 118 A > G polymorphism in exon 1, and the IVS2 + 31 G > A and IVS2 + 691 G > C polymorphisms, both in intron 2. Ninety-nine patients with adequately controlled pain were included in an analysis comparing morphine doses and serum concentrations of morphine and morphine metabolites in the different genotypes for the OPRM1 polymorphisms. RESULTS: No differences related to the -172 G > T, the IVS2 + 31 G > A and the IVS2 + 691 G > C polymorphisms were observed. Patients homozygous for the variant G allele of the 118 A > G polymorphism (n = 4) needed more morphine to achieve pain control, compared to heterozygous (n = 17) and homozygous wild-type (n = 78) individuals. This difference was not explained by other factors such as duration of morphine treatment, performance status, time since diagnosis, time until death, or adverse symptoms. CONCLUSION: Patients homozygous for the 118 G allele of the mu-opioid receptor need higher morphine doses to achieve pain control. Thus, genetic variation at the gene encoding the mu-opioid receptor contributes to variability in patients' responses to morphine.