Cytochrome P450 1A1 (CYP1A1) T6325C polymorphism might modulate essential hypertension-associated stroke risk

Stroke is a serious complication associated with hypertension. Because cytochrome P450 1A1 (CYP1A1) is involved in the production of arachidonic acid-derived vasoactive substances, we hypothesized that CYP1A1 functional polymorphisms (linked to changes in enzyme activity) might be related to pathological conditions associated with essential hypertension. We genotyped 32 patients with hypertension for three CYP1A1 polymorphisms, and individuals with or without history of previous stroke were compared. These results were also compared with a control population sample of 152. The distributions of T6235C (m1) CYP1A1 genotypes in patients with (TT: 44.4%;

TC/CC

55.6%; n = 9) and without stroke (TT: 82.6%;

TC/CC

17.4%; n = 23) indicate that the C allele is associated with stroke (OR = 5.94; 95% C = 1.46 - 24.23). No association was found between the polymorphism studied and essential hypertension. Our results suggest a relationship between CYP1A1 activity and incidence of stroke in patients with essential hypertension, but no conclusion can be drawn regarding an association with essential hypertension.

[Assessment of glomerular filtration rate in a hospital population. Comparison of two methods]

OBJECTIVES

This study was undertaken to assess the value of Cockroft-Gault Formula (FCG) in the patients of an Internal Medicine ward.

METHODS

FCG was compared with creatinine clearance (DC) adjusted for corporal area. Serum creatinine was measured after 24 h urine collection and 8 h fast. By the subtraction of FCG from DC, the variable difference (DIF) was calculated. FCG was calculated using total body weight (PT) and lean body weight (PS). All patients were included unless they had renal failure.

RESULTS

Renal function was calculated in 92 patients, 33 women and 59 men. Mean age was 60.8 +/- 17.9 (13-87). Mean FCG (64.7 +/- 27.4) and mean DC (68.4 +/- 32.6) were not significantly different and a correlation between them was found (r = 0.68; p < 0.001). Using PS to estimate FCG the correlation coefficient was increased to 0.75 (p < 0.001). DC and FCG using PT or PS correlated inversely with age (r = 0.59; r = 0.53; r = 0.66, respectively; p < 00.1). In a cluster analysis model we could find that for extremes of renal function FCG overestimated (DIF = -10.4 +/- 13.3) or underestimated (DIF = 29.8 +/- 29.7) DC. The main influence for the difference between the two methods was body weight (r = -0.69; p < 0.001). The distribution by diagnosis led to two classes of patients for whom DIF was significantly different (p < 0.02), and body weight was the main factor.

CONCLUSION

Cockroft-Gault formula, although correlating with creatinine clearance, over or underestimates creatinine clearance for extremes of renal function. Age and body weight were the main factors for the differences found between the two methods.

[Nitric oxide-dependent endogenous and exogenous vasodilators. The mechanism of action of nitrates]

The concept of endothelium-dependent vasodilation was developed after the discovery in 1980 of the endothelium-derived relaxing factor (EDRF) by Furchtgott and Zawadzki. In 1987 Furchgott and Ignarro identified the EDRF with nitric oxide. In the same year Moncada and coworkers demonstrated that the liberation of nitric oxide by endothelial cells was responsible by the biologic activity of EDRF. Nitric oxide is the endogenous mediator responsible by the endothelium-dependent vasodilation and can be considered the endogenous nitrovasodilator. But nitric oxide has a more complex spectrum of action, because it participates in the regulation of platelet activity and preservation of the normal structure of the vessel wall. Nitric oxide is also the terminal product of the biotransformation of therapeutic nitrates responsible by guanylate cyclase activation. Nitrates can be classified as endothelium non dependent vasodilators because some of them release spontaneously nitric oxide from their metabolites, and others are biotransformed to nitric oxide in vascular smooth muscle cells.

[Arterial hypertension in the elderly and renal function]

STUDY OBJECTIVE

to evaluate the effects of antihypertensive treatment on renal function, in an elderly population of 29 patients with arterial hypertension.

DESIGN

retrospective study of the first six months follow-up.

SETTING

outpatients clinic of arterial hypertension in the elderly at a central hospital.

PATIENTS AND METHODS

twenty nine elderly (> or = 65 years old) patients with a mean age of 71.8 +/- 5.6 years, with arterial hypertension (> or = 160/95 mmHg) submitted to antihypertensive treatment. Fourteen males and fifteen females. The systolic, diastolic and mean blood pressure was determined with a DINAMAP 1846, previously and at the first, third and sixth month of antihypertensive treatment (diuretic, calcium antagonists and angiotensin converting enzyme inhibitors). The serum creatinine was evaluated in the beginning of treatment and six months later. Means (+/- standard deviation) were compared with Student's t-test (statistically significant findings < 0.05).

MEASUREMENTS AND RESULTS

the initial mean arterial pressure was 127.0 +/- 17 mmHg; with the antihypertensive treatment, was 119.1 +/- 16 mmHg in the first month, 114.4 +/- 12 mmHg in the third and 117.6 +/- 12 mmHg in the sixth month. The serum creatinine was 1.26 +/- 0.75 mg/dl in the beginning of the study and the final result was 1.30 +/- 0.74 mg/dl (p-NS).

CONCLUSIONS

the antihypertensive treatment was effective in reducing the blood pressure, without a significant increase in serum creatinine.

[Clinical significance of hypercholesterolemia in the elderly]

Hypercholesterolemia is known as a cardiovascular risk factor for the non elderly man. But it still remains the controversy about the significance of dislipidemia on the aged. The authors discuss the problem and suggest a therapeutic approach following the European Consensus Conference Guidelines.