Flow-mediated dilatation of the brachial artery and left ventricular geometry in hypertensive patients

OBJECTIVES

In arterial hypertension, the spectrum of geometric patterns in the left ventricle may parallel the structural alterations detected in the carotid arteries and in subcutaneous small arteries. It has been also reported that hypertensive left ventricular hypertrophy (LVH) may be associated with endothelial dysfunction, as evaluated by the response of coronary or forearm vasculature to acetylcholine infusion. The aim of this study was to evaluate the flow-mediated vasodilatation (FMD) of the brachial artery, non-invasive estimate of endothelium-dependent vasodilatation according to left ventricular geometric adaptations in hypertensive patients.

METHODS AND RESULTS

In 16 normotensive (nine males, seven females, aged 40-68 years) and in 78 hypertensive subjects (50 males, 28 females, aged 42-67 years), we performed an echocardiographic study for the measurement of left ventricular mass index (LVMI) and relative wall thickness (RWT); we measured to a high resolution the brachial artery diameter at rest, during reactive hyperaemia (5 min of brachial artery occlusion) and after sublingual glyceril trinitrate (GTN); brachial artery flow velocity was measured by pulsed Doppler. Twenty-six hypertensive patients had a normal LVMI (LVMI < 51 g/ m2.7) and geometry (RWT < 0.44), five had concentric remodelling (RWT > or = 0.44), and concentric and eccentric LVH were observed in 19 and 28 patients, respectively. FMD was reduced in hypertensive patients as compared with normotensive subjects (P< 0.01). No correlation was found between FMD and LVMI (r= -0.078) or RWT (r = 0.049); in addition, no difference in FMD was found among the left ventricular geometric patterns in hypertensive patients.

CONCLUSIONS

In hypertensives, the presence of endothelial dysfunction is not associated with the LVH or with different left ventricular geometric patterns, suggesting that different and independent mechanisms may be responsible for the presence of LVH and of endothelial dysfunction.

Changes in midwall systolic performance and cardiac hypertrophy reduction in hypertensive patients

OBJECTIVE

To investigate changes in left ventricular (LV) performance, as evaluated by measurement of midwall LV fractional shortening (FS), after reduction of cardiac hypertrophy.

DESIGN AND METHODS

Echocardiographic evaluation of LV anatomy and function was performed by M-mode echocardiography at baseline, after long-term antihypertensive therapy, and after treatment withdrawal in 68 asymptomatic hypertensive patients (50 males, 18 females, age range 22-62 years). Patients were divided according to the presence of LV hypertrophy (LVH) at baseline (LV mass index, LVMI, > or = 51 g/m(2.7)).

RESULTS

At baseline patients with concentric (relative wall thickness > 0.44) LV hypertrophy (n = 38) or remodelling (n = 7) had reduced midwall shortening with respect to patients with normal LV geometry (n = 4) or eccentric LVH (n = 19); no differences were observed for endocardial FS. After long-term treatment (average 15 months), in 11 patients LV mass remained within normal limits, in 45 patients LVH reduction was obtained, while in 12 patients LV mass remained persistently elevated. Midwall FS was significantly increased in patients with reduction of LVH both during treatment and after withdrawal of treatment, while it remained significantly lower in patients with persistently elevated LV mass. Changes in midwall fractional shortening were independently associated with modifications in relative wall thickness (P < 0.00001), with changes in end-diastolic dimensions (P < 0.0001) and those of LVMI (P< 0.02) as shown by multivariate analysis.

CONCLUSION

LV midwall systolic performance significantly improved after reduction of LVH, even in the presence of high blood pressure values. Modifications in relative wall thickness are more independently associated with changes, in LV diastolic dimensions and mass, to midwall improvement

Enhanced vascular reactivity in the sympathectomized rat: studies in vivo and in small isolated resistance arteries

OBJECTIVE

In the conscious rat, sympathectomy (6-hydroxydopamine pretreatment, 100 mg/kg intraperitoneally, twice in the previous 5-6 days) induces, among various homeostatic modifications, the frequent occurrence of sudden and wide oscillations of blood pressure. Since one of the mechanisms underlying this, as yet unexplained, phenomenon may be an enhanced vascular reactivity, we tested the hypothesis that sympathectomized rats exhibit such a hyper-reactivity. We examined the response to a variety of vasoactive agents both in vivo (chronically instrumented conscious animals) and in vitro (small isolated resistance arteries).

DESIGN AND METHODS

Wistar-Kyoto sympathectomized rats (6-hydroxydopamine pretreatment, n = 19) and control rats (vehicle pretreatment, n = 23) were studied. In conscious animals, concentration-blood pressure response curves to intra-venous bolus injections of vasopressin, phenylephrine and angiotensin II were obtained. In isolated vessels, concentration-wall tension response curves were obtained for norepinephrine, phenylephrine, vasopressin, serotonin and potassium. Vasodilator responses to acetylcholine (with or without L-NAME), bradykinin and sodium nitroprusside were also evaluated after precontraction with norepinephrine (mesenteric arteries) or vasopressin (cerebral arteries).

RESULTS

In sympathectomized rats in vivo the pressor responses to vasopressin, phenylephrine and angiotensin II were significantly larger than in control rats, the difference amounting to 46.5, 40.2 and 57.1%, respectively (all P < 0.05). In vitro, the vascular reactivity of isolated cerebral arteries was similar in sympathectomized and control rats. In contrast, the mesenteric arteries showed significantly increased contractions in sympathectomized compared to control rats in response to norepinephrine, phenylephrine and vasopressin but not to serotonin and potassium, whereas the vasodilator responses to acetylcholine and sodium nitroprusside (but not to bradykinin and acetylcholine+L-NAME) were reduced.

CONCLUSIONS

In conclusion, we showed that sympathectomy produces complex alterations of vascular reactivity both in vivo and in isolated vessels, which shift the balance of the sensitivity of the vessel between vasoconstrictor and vasodilating agents towards an increased constriction. These results are unlikely to simply reflect denervation supersensitivity; their underlying receptor, post-receptor and/or contractile mechanisms are yet to be identified.

Time course of apoptosis in small resistance arteries of spontaneously hypertensive rats

OBJECTIVE

The time course of programmed cell death (apoptosis) in the vasculature of spontaneously hypertensive rats (SHRs) is still unclear. Moreover, no data are presently available about the possible inter-relationships between apoptosis and vascular remodelling. The aim of this study was to investigate the mesenteric small resistance arteries and large arteries (aortas) of SHRs and normotensive Wistar-Kyoto (WKY) rats at different ages, before and after the development of overt hypertension.

METHODS

Twenty-four SHRs (4, 8 or 12 weeks old) and 24 age-matched WKY rats were included in the study. Blood pressure was measured non-invasively. Rats were killed by decapitation and segments of aortas and small mesenteric arteries were dissected free from the surrounding tissue. Mesenteric arteries were mounted on a micromyograph and structural characteristics were measured (media thickness, media:lumen ratio, etc.). Apoptotic cells in the tunica media of large and small vessels were then stained using modified TdT-mediated dUTP Nick-End Labeling (TUNEL).

RESULTS

At 4 weeks of age no difference in the blood pressure and percentage of apoptosis in mesenteric arteries between SHRs and WKY rats was detected; however, the media:lumen ratio of mesenteric small resistance arteries was significantly greater in SHRs. At 8 and 12 weeks of age systolic blood pressure, media:lumen ratio and apoptosis rate in mesenteric small arteries was significantly higher in SHRs. The rate of apoptosis in the aortas was similar in the two strains at all three ages.

CONCLUSIONS

An increased prevalence of apoptosis was observed in mesenteric small arteries of 8- and 12-week-old SHRs. It is possible that apoptosis may exert a role in small resistance artery remodelling during the development and establishment of hypertension.

Cellular hypertrophy in subcutaneous small arteries of patients with renovascular hypertension

Structural alterations of small arteries in patients with essential hypertension are characterized by inward eutrophic remodeling. However, small arteries in patients with secondary hypertension, as well as in experimental models of hypertension with high circulating renin, are characterized by inward hypertrophic remodeling, which is characterized by smooth muscle cell hypertrophy in animal models. The aim of our study was to determine whether remodeling of subcutaneous small arteries in patients with secondary forms of hypertension is associated with smooth muscle cell hypertrophy and/or alterations in the elastic modulus of the vessel wall. Fifteen patients with renovascular hypertension, 9 with primary aldosteronism, and 13 with essential hypertension and 9 normotensive subjects were included in the study. A biopsy of subcutaneous fat was taken from all subjects. Small arteries were dissected, and morphology was determined on a micromyograph. Unbiased estimates of cell volume and number were made in fixed material. From the resting tension-internal circumference relation of the small arteries, the incremental elastic modulus was calculated and plotted as a function of wall stress. Blood pressure was greater in patients with essential hypertension, renovascular hypertension, or primary aldosteronism than in normotensive subjects, but no significant difference was observed among the 3 groups of hypertensive patients. The media/lumen ratio, the medial cross-sectional area, and the smooth muscle cell volume were significantly greater in patients with renovascular hypertension than in normotensive subjects and patients with essential hypertension. No difference in cell number or in the elastic properties was observed among the 4 groups of subjects. In conclusion, our data demonstrate for the first time that a pronounced activation of the renin-angiotensin-aldosterone system is associated with vascular smooth muscle cell hypertrophy in human hypertension in a manner similar to that found in animal models.

Genes involved in melanoma: an overview of INK4a and other loci

Melanoma is the most aggressive of the skin cancers and its prognosis is often poor. The only known environmental risk factor for this tumour is ultraviolet light exposure. This fact together with the existence of melanoma-prone families has prompted investigation of genetic risk factors that may be involved in melanoma development. Inactivation of the INK4a/p16 gene is known to play a role in familial cases. Data on genes or loci involved in sporadic melanoma are less definitive and require more detailed research. In addition to the INK4a locus, other genes involved in melanoma development are discussed here, in particular those genes that participate in the same functional pathway, such as CDK4 and Rb, and p53, which is regulated by the alternative product of INK4a. Evidence showing the possible location of melanoma susceptibility genes on chromosomes 1p, 6, 10q and 11q is analysed along with data showing N-ras, betacatenin, c-myc and MC1R involvement. Melanoma is a well-characterized disease in terms of its progression stages; therefore obtaining precise genetic information is crucial in the development of a stepwise model of melanoma pathogenesis.

High-dose, not low-dose insulin increases the vasoconstrictor effect of norepinephrine in spontaneously hypertensive rats: effects of antihypertensive treatment

The effect of insulin on the vasoconstriction induced by norepinephrine is presently controversial. Therefore, the aims of our study were: (1) to evaluate the effect of low- and high-dose insulin on the concentration-response curve to norepinephrine in small resistance arteries of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) before and after the development of hypertension, and (2) to evaluate the effects of antihypertensive treatment on vascular response to insulin and norepinephrine. Fifty-six rats were included in the study. Six SHR were treated with enalapril and 6 with candesartan cilexetil from the 4th to the 12th week of age, while 10 WKY and 14 SHR were kept untreated. Two additional groups of 10 untreated SHR and 10 WKY were killed at 4 weeks of age, in a prehypertensive phase. Mesenteric small arteries were dissected and mounted on a micromyograph. A dose-response curve to norepinephrine was performed at cumulative concentrations in the presence or absence of low- and high-dose insulin. We found that only high-dose insulin increased the vascular response to norepinephrine in 12-week-old SHR, but not in 4-week-old SHR or in age-matched WKY. The increased responsiveness to norepinephrine disappeared after preincubation of the vessels with a selective inhibitor of endothelin-1 type A receptors. After antihypertensive treatment with enalapril or candesartan cilexetil, the potentiation of the vasoconstrictor response to norepinephrine was abolished. In conclusion, insulin at high, nonphysiological doses seems to induce an increase in the reactivity to norepinephrine in mesenteric small arteries of SHR, possibly mediated by a local production of endothelin-1. Antihypertensive treatment with an ACE inhibitor or an angiotensin II receptor blocker may normalize this altered response. This mechanism may be relevant in the development of hypertension in SHR.

Functional reassessment of P16 variants using a transfection-based assay

CDKN2A appears to be the major melanoma susceptibility gene, and is also mutated/deleted in sporadic tumours of various types including melanoma. Thus far most approaches to assessing the functionality of mutations in this gene have used in vitro methods such as CDK4 binding and kinase inhibition assays, with sometimes disparate conclusions about functional significance of some variants between studies. We have used a melanoma cell line (MM96L) with no functional p16, as the basis for a "semi-in vivo" transfection-based assay for exogenous p16 functionality based on the growth parameters of the cells and the behaviour of variant proteins after transfection of different CDKN2A cDNAs. Colony counts performed on these transfectants revealed that all but the wild type, + 24 bp ad A148T variants have a diminished ability to inhibit cell growth. All other variants detected either constitutionally in familial melanoma patients (I49T, R87P, G101W and V126D) or somatically in melanomas (N71S, and P81L), appeared functionally impaired in this assay. This diminution of function was independent of CDK4 and CDK6 binding ability. Furthermore, the predominant localization of these variants within the cell was different from that of wt p16. This mislocalization may provide an explanation for their lack of function, or alternatively, it may also be an indicator that the cells are processing unstable, misfolded p16 proteins. This novel assay for assessment of functionality of p16 variants may better reflect the role of some of these mutations in vivo, and as such is a useful adjunct to other in vitro assays.

A cyclin D-Cdk4 activity required for G2 phase cell cycle progression is inhibited in ultraviolet radiation-induced G2 phase delay

Cyclin D-Cdk4 complexes have a demonstrated role in G1 phase, regulating the function of the retinoblastoma susceptibility gene product (Rb). Previously, we have shown that following treatment with low doses of UV radiation, cell lines that express wild-type p16 and Cdk4 responded with a G2 phase cell cycle delay. The UV-responsive lines contained elevated levels of p16 post-treatment, and the accumulation of p16 correlated with the G2 delay. Here we report that in UV-irradiated HeLa and A2058 cells, p16 bound Cdk4 and Cdk6 complexes with increased avidity and inhibited a cyclin D3-Cdk4 complex normally activated in late S/early G2 phase. Activation of this complex was correlated with the caffeine-induced release from the UV-induced G2 delay and a decrease in the level of p16 bound to Cdk4. Finally, overexpression of a dominant-negative mutant of Cdk4 blocked cells in G2 phase. These data indicate that the cyclin D3-Cdk4 activity is necessary for cell cycle progression through G2 phase into mitosis and that the increased binding of p16 blocks this activity and G2 phase progression after UV exposure.

Structural association between the carotid artery and the left ventricle in a general population in Northern Italy: the Vobarno study

OBJECTIVE

To evaluate the interrelationships between structural alterations in the carotid arteries and left ventricular geometric patterns in a middle-aged general population.

DESIGN AND METHODS

We studied 223 untreated subjects (106 females, 117 males; aged 48-64 years) living in a small town in Northern Italy (Vobarno, Brescia), using a cross-sectional design. The left ventricular mass index was assessed by echocardiography, while the intima-media thickness and the occurrence of plaque were evaluated by ultrasound. Blood pressure was determined by clinic measurements and by 24 h noninvasive ambulatory blood pressure monitoring.

RESULTS

According to the presence of left ventricular hypertrophy (left ventricular mass index > 50 g/m2.7 in males and > 47 g/m2.7 in females) or concentric left ventricular remodelling (normal left ventricular mass index and relative wall thickness > 0.42), the subjects were divided into four groups: 124 subjects with normal left ventricular geometry, 73 subjects with left ventricular hypertrophy (55 with eccentric and 18 with concentric hypertrophy) and 26 subjects with concentric remodelling. The common carotid intima-media thickness and cross-sectional area were significantly greater in the subjects with concentric left ventricular hypertrophy (analysis of variance, P< 0.05) than in those with normal left ventricular geometry. A significantly higher number of plaques was observed in subjects with concentric and eccentric left ventricular hypertrophy.

CONCLUSIONS

In a general population of unselected middle-aged subjects, the presence of concentric left ventricular hypertrophy was associated with an increase in intima-media thickness and with the presence of plaque in the carotid arteries, possibly contributing to the worse prognosis observed in this group of patients.

Effects of candesartan cilexetil and enalapril on structural alterations and endothelial function in small resistance arteries of spontaneously hypertensive rats

It was previously observed that a significant regression of structural alterations and endothelial dysfunction in mesenteric small arteries of spontaneously hypertensive rats (SHRs) may be obtained after therapy with angiotensin-converting enzyme (ACE) inhibitors. It is not clear whether angiotensin II-type 1 receptor blockers may share this properties. We evaluated the effects of the ACE inhibitor enalapril and of the angiotensin II-receptor blocker candesartan cilexetil on structural alterations of mesenteric small resistance arteries, on cardiac mass, and on endothelial function in SHRs. Seventy-three rats were included in the study. Sixteen SHRs were treated with enalapril and 21 with candesartan cilexetil, whereas 18 Wistar-Kyoto (WKY) and 18 SHRs were untreated. Enalapril and candesartan cilexetil were administered in the drinking water from weeks 4 to 12 of age. Blood pressure was measured noninvasively every week. The rats were killed at the end of the treatment period, after 3 or 4 days of therapeutic washout. Heart weight/body weight ratio (HW/BW) was measured. Mesenteric arterioles were dissected and mounted on a micromyograph (Mulvany's technique). Then the media-to-lumen ratio (M/L) was evaluated. In addition, endothelium-dependent and endothelium-independent relaxation was evaluated by dose-response curves to acetylcholine (in the presence or absence of a bradykinin-receptor blocker and of indomethacin) and sodium nitroprusside. Systolic blood pressure was significantly reduced by both drugs, compared with untreated SHRs, although the hypotensive effect was greater with enalapril than with candesartan cilexetil. A significant reduction of M/L of mesenteric small arteries and of HW/BW was observed in SHRs treated with candesartan cilexetil or enalapril. A significant improvement of endothelial function, as evaluated by a dose-response to acetylcholine, was observed. The acetylcholine-induced vasodilatation was similar after addition to the organ bath of a selective blocker of bradykinin receptors, thus suggesting a minor role (if any) of the increased local availability of bradykinin, as a consequence of inhibition of ACE, in the improvement of endothelial function observed after enalapril treatment. In addition to a satisfactory antihypertensive effect observed with both drugs, candesartan cilexetil and enalapril were proven to be equally effective in reducing structural alterations in mesenteric small resistance arteries, in normalizing cardiac mass, and in improving endothelial function. The inhibition of bradykinin breakdown does not seem to be involved in the improvement of endothelial dysfunction observed with ACE inhibitors.

Effects of hypotensive and non-hypotensive doses of manidipine on structure, responses to endothelin-1 and ICAM-1 production in mesenteric small resistance arteries of spontaneously hypertensive rats

OBJECTIVE

We have evaluated the effects of a new calcium channel blocker, manidipine, given at both high, hypotensive and low, non-hypotensive doses, on vascular morphology, response to endothelin-1 and ICAM-1 production in mesenteric small resistance arteries of spontaneously hypertensive rats (SHR).

METHODS

Ten SHR were treated with manidipine 3 mg/kg per day (high dose) and 10 with manidipine 0.3 mg/kg/per day (low dose). The drug was administered by gavage from the 4th to 12th weeks of age. Eighteen Wistar-Kyoto (WKY) rats and 18 SHR were kept untreated as controls. Rats were killed at 13 weeks. Mesenteric small arteries were dissected and mounted on a micromyograph for determination of indexes of vascular structure (media thickness, wall thickness, media/lumen ratio).

RESULTS

Systolic blood pressure was significantly reduced by the high dose of the drug, while no effect was observed with low-dose manidipine. A reduction in the media/lumen ratio was observed only in SHR treated with high-dose manidipine. The response to endothelin-1 in untreated SHR was significantly lower in comparison with WKY; a significant reduction was observed in SHR treated with high-dose manidipine. ICAM-1 vascular concentrations were higher in untreated SHR than in WKY controls. Both high- and low-dose manidipine reduced ICAM-1 concentrations toward normalization.

CONCLUSIONS

Manidipine at high, hypotensive, but not at low, non-hypotensive doses has been proven to reduce structural alterations in mesenteric small resistance arteries, and to normalize vascular responses to endothelin-1. In addition, manidipine, at both low and high doses, may reduce ICAM-1 vascular production, thus suggesting a possible anti-atherogenic effect.

Chamber-specific alterations of norepinephrine uptake sites in cardiac hypertrophy

The present study investigated local differences of sympathetic activation and sympathetic neuroeffector defects in nonhypertrophied right and hypertrophied left ventricles in a rat model with renin-induced pressure overload [TG(mREN2)27]. As judged from the depletion of myocardial norepinephrine stores, sympathetic activation was more pronounced in the left than in the right ventricles. In addition, norepinephrine uptake1 carrier sites were reduced in left but unchanged in right ventricles. Gene expression of the carrier was unchanged in stellate ganglia. An increase of Gialpha expression and a heterologous adenylyl cyclase desensitization occurred only in the left but not in the right ventricles, whereas a reduction of beta-adrenergic receptors was observed in both chambers. We concluded that general sympathetic activation can lead to beta-adrenoceptor downregulation but that pressure overload further increases sympathetic activation involving norepinephrine uptake mechanisms in the left ventricles, resulting in heterologous beta-adrenergic desensitization.

Power spectral analysis of the heart rate in hypertensive patients with and without left ventricular hypertrophy: the effect of a left ventricular mass reduction

OBJECTIVE

The aim of this study was to evaluate the spectral analysis of the heart rate in normotensive subjects and in hypertensive patients with and without left ventricular hypertrophy (LVH), under basal conditions and after a reduction in left ventricular mass.

SUBJECTS AND METHODS

In 12 normotensive subjects and 22 hypertensive patients (14 with and eight without LVH), we performed 24 h electrocardiogram Holter monitoring, ambulatory blood pressure monitoring and an echocardiographic study. Sequences of 512 R-R intervals, during daytime, afternoon and night-time periods, were taken for an evaluation of spectral analysis (Box-Jenkins method). We then calculated the absolute and percentage power spectral density of the peak centred at 0.10 Hz (low-frequency peak) and at 0.25 Hz (high-frequency peak).

RESULTS

At baseline, a daytime to night-time decrease in the low-frequency peak was detected in normotensives (P < 0.01) and in hypertensives without LVH (P < 0.01), while no change was observed in hypertensives with LVH. The power spectral density low-frequency peak during the daytime and night-time was significantly greater in hypertensives with LVH than in those without LVH (P < 0.001) and in normotensive subjects (P < 0.001). Fourteen of these patients with LVH were given effective long-term antihypertensive treatment and were studied again 20 days after the treatment had been withdrawn, when blood pressure had increased to pretreatment values. In eight patients showing a reduction in LVH, we found a significant decrease in the power spectral density low-frequency peak and an increase in the high-frequency peak during daytime and night-time in respect to basal conditions, and circadian variations in the spectral indices of heart rate variability were restored. In contrast, in six patients without reversal of LVH, the power spectral density low-frequency peak did not change in respect to basal conditions and remained significantly higher in comparison with the patients with LVH regression.

CONCLUSION

A reduction in LVH may be associated with restoration of daytime to night-time cardiac autonomic control, as evaluated by a power spectral analysis of the heart rate.

Relations between cardiac and vascular structure in patients with primary and secondary hypertension

BACKGROUND

Data on cardiac and vascular structure in secondary hypertension are generally scarce, and no data on the interrelations between cardiac mass and structural characteristics of the vessel wall, both in large and in small resistance arteries, are presently available.

OBJECTIVES

The aim of this study was to investigate the relation between structural changes in subcutaneous small arteries, left ventricular mass and wall thickness of the common carotid artery in patients with primary and secondary hypertension.

METHODS

Seventy-four subjects were included in the study: 11 patients with pheochromocytoma, 14 with primary aldosteronism (PA), 19 with renovascular hypertension (RVH), 18 with essential hypertension (EH) and 12 normotensive (NT) control subjects. All subjects were submitted to a biopsy of subcutaneous fat. Morphologic characteristics of subcutaneous small resistance arteries (relaxed diameter <300 microm) were directly evaluated using a micromyographic technique. All subjects were submitted to calculation of left ventricular mass index (LVMI) and common carotid artery intima-media thickness (CCIMT), using ultrasound technique.

RESULTS

The correlation coefficients between the media to lumen ratio in subcutaneous small arteries (M/L) and LVMI or between M/L and CCIMT were closer in RVH than in pheochromocytoma, EH or NT; in PA the correlation coefficients were slightly less close than those in RVH. An excess prevalence of carotid plaques in RVH was observed.

CONCLUSIONS

A close relation between small resistance artery morphology and cardiac or carotid artery structure may be observed in those hypertensive patients in whom the renin-angiotensin-aldosterone system is activated. In constrast, in NT, EH and pheochromocytoma no significant correlation between M/L and LVMI or CCIMT was observed.

PM and D1S80 loci gene frequencies in the Zaragoza population of northern Spain

LDLR, GYPA, HBGG, D7S8, GC (PM loci) and D1S80 are widely used in forensic casework analyses and population data are required to estimate the frequency of a DNA profile. This paper presents the results of a survey aimed at investigating the allele and genotype frequency distribution of these loci in an important Spanish population (Zaragoza, North Spain). Statistical analysis to determine whether allele frequencies were in Hardy-Weinberg equilibrium was carried out as well as to obtain some parameters of medicolegal interest. There was no evidence of association between the alleles of the loci. The Zaragoza sample does not differ substantially from other Caucasian populations.

Effects of losartan and enalapril on small artery structure in hypertensive rats

We evaluated the effects on cardiovascular structure of the angiotensin-converting enzyme (ACE) inhibitor enalapril and of the angiotensin II receptor blocker losartan, administered either at hypotensive or nonhypotensive dosage in spontaneously hypertensive rats (SHR). SHR were treated from ages 4 to 12 weeks with low-dose (1 mg x kg(-1) x d(-1)) enalapril, low-dose (0.5 mg x kg(-1) x d(-1)) losartan, high-dose (25 mg x kg(-1) x d(-1)) enalapril, or high-dose (15 mg x kg(-1) x d(-1)) losartan. Untreated WKY and SHR were also studied. Rats were killed at 13 weeks of age, and the heart was weighed. Mesenteric small arteries were dissected and mounted on a micromyograph for determination of media thickness and lumen diameter. In fixed arteries, cell volume, number of cells per segment length, and number of cell layers were measured using the unbiased "disector" method. Systolic blood pressure was significantly reduced by the high doses of both drugs, but the hypotensive effect was greater with enalapril than with losartan (P<0.05). In the high-dose enalapril and losartan groups, there were similar reductions in relative left ventricular mass, media/lumen ratio, and number of cell layers of resistance arteries; however, there were no differences in the cell volume or number of cells per segment length of resistance arteries. Low-dose enalapril did not affect systolic blood pressure or any of the structural parameters. The results show that the hypotensive effects of both losartan and enalapril were associated with outward remodeling of resistance arteries at the cellular level. The effect of losartan on resistance artery structure was equal to that of enalapril, despite the smaller hypotensive effect.

Endothelial dysfunction in hypertension is independent from the etiology and from vascular structure

The aim of our study was to evaluate the relationships between endothelial function, small resistance artery structure, and blood pressure in patients with primary or secondary hypertension. Sixty subjects were included in the study: 9 patients with pheochromocytoma, 10 with primary aldosteronism, 17 with renovascular hypertension, and 13 with essential hypertension with 11 normotensive subjects who served as controls. Clinic and 24-hour ambulatory blood pressure (ABPM) were evaluated. All subjects were submitted to a biopsy of subcutaneous fat. Small resistance arteries were dissected and mounted on a micromyograph and the media/lumen ratio was calculated. A dose-response curve to acetylcholine was performed at cumulative concentrations from 10(-9) to 10(-5) mol/L. The vasodilator response to acetylcholine was similarly impaired in the four groups of hypertensive patients (ANOVA P<.05 versus normotensive controls), without any significant difference among them. In subcutaneous small arteries of patients with either primary aldosteronism or renovascular hypertension, a marked increase in media:lumen ratio was observed, while in patients with pheochromocytoma, the extent of vascular structural alterations was similar to that observed in essential hypertension. No significant correlation between media-lumen ratio or clinic blood pressure and maximum acetylcholine-induced vasodilatation was observed. On the contrary, a significant, albeit not very close, correlation between ABPM values and maximum acetylcholine-induced vasodilatation was observed (r=34, P<.05 with 24-hour systolic blood pressure, r=0.36, P<.05 with 24-hour diastolic blood pressure). In conclusion, endothelial dysfunction seems to be independent from the degree of vascular structural alterations and from the etiology of hypertension, and it is probably more linked to the hemodynamic load.

Alpha-adducin gene polymorphism and cardiovascular phenotypes in a general population

BACKGROUND

Previous studies have shown that molecular variants of the cytoskeletal protein adducin may be involved in regulation of blood pressure both in genetic rat hypertension and in human essential hypertension.

OBJECTIVE

To investigate the relationship of genetic polymorphism of alpha-adducin with blood pressure, cardiovascular structure, and some biochemical indexes of cardiovascular risk in a sample of general population.

DESIGN AND METHODS

A sample of 246 subjects (124 men and 122 women, aged 57.7+/-3.7 years) was randomly chosen from a middle-aged population. Twenty-four-hour ambulatory blood pressure, as well as left ventricular mass (by echocardiographic methods) and carotid wall thickness (by B-mode ultrasound methods) were measured. DNA was extracted from peripheral blood samples; the Gly460Trp diallelic variant of human alpha-adducin was genotyped by polymerase chain reaction amplification and then allele-specific oligo hybridization.

RESULTS

A trend toward higher 24 h ambulatory blood pressure values in subjects not treated with antihypertensive drugs was observed among carriers of Trp460 allele, although the differences did not attain statistical significance (at closest, P = 0.066 for a dominant effect of Trp460 on systolic blood pressure). When blood pressure was considered a dichotomous variable, allowing the inclusion of treated hypertensives), a higher prevalence of Trp460 allele among hypertensives was observed (0.188 versus 0.106 among normotensives, P= 0.02). There was no evidence of association either of left ventricular mass or of common carotid wall thickness with Gly460Trp polymorphism.

CONCLUSIONS

In this sample of a general population, the relationship of a genetic polymorphism of alpha-adducin with blood pressure values was rather weak. However, a population-based case-control analysis indicated that there was an association between Trp460 allele and hypertension, with a relative risk for subjects carrying at least one Trp460 allele of approximately 1.6. Further investigation of larger and different population samples in order to assess the role of adducin gene polymorphism as a marker of genetic predisposition to the development of hypertension is warranted.

The vasoconstriction induced by endothelin-1 is mediated only by ET(A) receptors in mesenteric small resistance arteries of spontaneously hypertensive rats and Wistar Kyoto rats

OBJECTIVE

To evaluate the functional responses of mesenteric small resistance arteries of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rat controls to endothelin-1 (ET-1), in the presence and absence of an ET(A) receptor antagonist drug as well as to an ET(B) receptor agonist.

METHODS

Twenty rats aged 12 weeks were studied. They were 10 SHR and 10 WKY rats. Mesenteric small resistance arteries (relaxed diameter 100-180 microm) were dissected and mounted on a micromyograph (Mulvany's technique). A dose-response curve for response to ET-1 was plotted for cumulative concentrations (from 10(-11) to 10(-8) mol/l) in the presence and absence of 10(-6) mol/l FR 139317 (a selective antagonist of ET(A) receptors). In addition, the effects of 10(-7) mol/l N-succinyl-[Glu9, Ala11,15]-endothelin 1 fragment 8-21 (IRL 1620, a selective agonist of ET(B) receptors) were evaluated.

RESULTS

The response of ET-1 was greater in WKY rats than it was in SHR. Almost all the vasoconstrictor effect of ET-1 could be prevented by addition of FR 139317, whereas the agonist of ET(B) receptors had no effect (no change in active force).

CONCLUSIONS

The contractile effects of ET-1 on mesenteric small resistance arteries of SHR and WKY rats are mediated mostly by ET(A) receptors, whereas ET(B) receptors play a minor role, if any. It is possible, however, that a vasoconstrictor effect of ET(B) receptors on the smooth muscle could be masked by the concomitant stimulation of endothelial ET(B) vasodilator receptors.

Discrimination between migraine patients and normal subjects based on steady state visual evoked potentials: discriminant analysis and artificial neural network classifiers

Fifty-one migraine patients and 19 control subjects were examined by steady state visual evoked potentials (SSVEPs) procedure. The aim of this study was to develop a discriminant analysis and an artificial neural network (NN) classifier in order to discriminate between migraneurs during attack-free periods and normal subjects. Discriminant analysis correctly classified 72.5% of migraine patients with a false positive rate of 36.8%. The NN method had a sensitivity of 100% with a false positive rate of 15%. The results of this study confirm SSVEP pattern as a marker of migraine and demonstrate that NNs could be a useful method in the statistical analysis of topographic EEG data.