Pietro Delva

Endothelial progenitor cells in patients with essential hypertension.

Objective(s) The eventual role of blood pressure on the endothelial progenitor cell (EPC) has rarely been evaluated and data collected so far relate to patients with co-existing coronary heart disease. Methods We have studied the number and functional activity of EPC as well as the number of EPC endothelial colony-forming units (CFU) in a carefully selected group of 36 patients with essential hypertension and 24 normotensive control subjects. Results In patients with essential hypertension, the EPC number was not statistically different from that found in control subjects (mean ± SD, essential hypertension 58 ± 29, controls 53 ± 20; EPC/high power field). CFU per well were not statistically different in patients with essential hypertension compared with normotensive controls (mean ± SD, patients with essential hypertension 2.4 ± 2.6, normotensive controls 3 ± 3.3 CFU/well). In essential hypertension patients, the EPC number was inversely correlated with both total (R = 0.635, P < 0.0001) and low-density lipoprotein (LDL)-cholesterol (R = 0.486, P < 0.05). Neither the EPC number nor the EPC CFU were correlated with age, systolic blood pressure, diastolic blood pressure, body mass index, lipoprotein(a), high-sensitivity C-reactive protein or homocysteine. Conclusions The present study shows that essential hypertension is not characterized by the altered number or functional activity of EPC. Plasma total and LDL-cholesterol are independent predictors of reduced numbers of circulating EPC in essential hypertension patients. The absence of any correlation between the characteristics of EPC and several markers predictive of cardiovascular damage merits further investigation.

Effects of six months of vitamin D supplementation in patients with heart failure: A randomized double-blind controlled trial

BACKGROUND AND AIM Low plasma vitamin D levels have been associated with heart failure (HF). This research attempts to explain the role of vitamin D supplementation on myocardial function in elderly patients with HF. METHODS AND RESULTS Twenty-three chronic HF patients were randomized in a small parallel group, double-blind, placebo-controlled trial. All patients, with a mean age of 74 years and vitamin D levels <30 ng/mL, received 800,000 IU (4000 IU/daily) of cholecalciferol or placebo for 6 months. The outcomes measured at baseline and after 6 months were ejection fraction (EF) and other echocardiography parameters, carboxyterminal propeptide of procollagen type I (PIP), natriuretic peptides, lipid profile, renin, parathyroid hormone, blood pressure, and body mass index (BMI). In 13 patients under active treatment for 6 months, mean plasma 25-hydroxy vitamin D concentrations (15.51 vs. -1.40 ng/mL, p < 0.001) and plasma calcium (from 9.3 to 9.6 mmol/L, p < 0.05) increased significantly. However, other biomarkers of bone metabolism did not differ between the treatment and placebo groups. EF increased significantly in the intervention group (6.71 vs. -4.3%; p < 0.001), and the serum concentration of PIP increased only in the placebo group after 6 months (1140.98 vs. -145 mcg/L; p < 0.05). Systolic blood pressure was lower after 6 months of cholecalciferol treatment (from 129.6 to 122.7 mm Hg, p < 0.05). No significant variations were observed for other parameters. CONCLUSIONS Six months of vitamin D supplementation significantly improves EF in elderly patients with HF and vitamin D deficiency.

Intralymphocyte free magnesium in patients with primary aldosteronism: aldosterone and lymphocyte magnesium homeostasis.

It is known that hyperaldosteronism has been associated with magnesium deficiency, yet there are no data on the intracellular concentration of ionized magnesium ([Mg(2+)(i)]) in subjects with primary aldosteronism (PA). We measured intralymphocyte free magnesium ([Mg(2+)(i)]) and intralymphocyte free calcium ([Ca(2+)(i)]) in 16 patients with PA and 26 normotensive control subjects (NCs). [Mg(2+)(i)] and [Ca(2+)(i)] were also measured in blood lymphocytes incubated in vitro with aldosterone, according to a fluorimetric method. In subjects with PA, [Mg(2+)(i)] was significantly lower than that in NCs (mean+/-SD; PA 203+/-56 micromol/L, NCs 291+/-43 micromol/L, 95% confidence interval 57 to 119, P=0.001). In the patients, [Ca(2+)(i)] did not prove to be statistically different from that of NCs (mean+/-SD; PA 47.2+/-10.6 nmol/L, NCs 53.2+/-11 nmol/L). The lymphocytes exposed to the action of aldosterone showed a significant reduction in [Mg(2+)(i)] (n=15, NCs 271+/-28 micromol/L, aldosterone treatment 188+/-39 micromol/L, P=0.001, 95% confidence interval 57 to 108). The dose-effect curve of aldosterone on [Mg(2+)(i)] showed an EC(50) value of approximately 0.5 to 1 nmol/L aldosterone. The reduction in [Mg(2+)(i)] mediated by aldosterone is antagonized by the receptor inhibitor of aldosterone; it is inhibited by inhibitors of protein synthesis and is not measurable when the lymphocytes are incubated in an Na(+)-free medium. The data are consistent with the hypothesis that aldosterone affects the cellular homeostasis of magnesium, probably through modification of the activity of the Na(+)-Mg(2+) antiporter.

Erythrocyte Na(+)-H+ exchange activity in essential hypertensive and obese patients: role of excess body weight.

Introduction: Several authors have described increased Na + — H + exchanger activity in essential hypertension, and an increase in activity of this transport system has also been postulated in situations of hyperinsulinism, such as obesity and essential hypertension Methods: We measured Na + — H + exchanger activity in a group of 37 subjects with essential hypertension (18 obese, 19 non-obese), in a group of nine normotensive obese subjects and in a control group of 16 healthy volunteers. Plasma insulin and glucose values during an oral glucose tolerance test were evaluated, together with other variables such as plasma aldosterone, plasma renin activity and plasma potassium Results: Na+—H+ exchanger system activity did not appear to be abnormally raised in the hypertensive subjects, but was significantly increased in the normotensive obese group. Upon dividing the hypertensive subjects into two subgroups on the basis of body mass index, it was noted that, whereas the non-obese hypertensives showed Na+—H + exchanger activity patterns similar to those in controls, the obese hypertensive subjects exhibited increased activity of the transport system. Na+—H + activity correlates with body mass index and shows a significant inverse correlation with plasma potassium. No correlations were found between Na + — H + exchanger activity and the sum of plasma insulin values during the oral glucose tolerance test Conclusion: Na + — H + exchanger overactivity appears to be characteristic in overweight subjects, but would not appear to be a specific feature of essential hypertension. The increased Na + — H + exchanger activity observed in obese subjects may be postulated to be related to the hypermineralocorticoidism characteristic of this condition

Effects of magnesium supplements on blood pressure, endothelial function and metabolic parameters in healthy young men with a family history of metabolic syndrome

BACKGROUND AND AIMS Magnesium plays an important role in the modulation of vascular tone and endothelial function and can regulate glucose and lipid metabolism. Patients with hypertension, metabolic syndrome (MetS) and diabetes mellitus (T2DM) have low body magnesium content; indeed, magnesium supplementation has been shown to have a positive effect on blood pressure (BP) and gluco-metabolic parameters. The aim of our study was to evaluate the effect of magnesium supplements on hemodynamic and metabolic parameters in healthy men with a positive family history of MetS or T2DM. METHODS AND RESULTS In a randomized, double-blind, placebo-controlled 8-week crossover trial with a 4 week wash-out period, oral supplements of 8.1 mmol of magnesium-pidolate or placebo were administered twice a day to 14 healthy normomagnesemic participants, aged 23-33 years. The primary endpoint was office BP, measured with a semiautomatic oscillometric device. Secondary endpoints included characteristics of the MetS, namely endothelial function, arterial stiffness and inflammation. Plasma and urinary magnesium were measured in all participants while free intracellular magnesium was measured only in a subsample. There was no significant difference in either systolic and diastolic BP in participants post-magnesium supplementation and post-placebo treatment when compared to baseline BP measurements. Further, the metabolic, inflammatory and hemodynamic parameters did not vary significantly during the study. CONCLUSIONS Our study showed no beneficial effect of magnesium supplements on BP, vascular function and glycolipid profile in young men with a family history of MetS/T2DM (trial registration at clinicaltrial.gov ID: NCT01181830; 12th of Aug 2010).

High plasma levels of a ouabain‐like factor in normal pregnancy and in pre‐eclampsia*

Abstract. Recent reports have described high levels of one or more substances which cross‐react with digoxin antibodies in the serum of women with pre‐eclampsia. We measured plasma ouabain‐like activity and intra‐erythrocyte sodium and potassium concentrations, in addition to performing routine hypertensive laboratory tests, in 13 normotensive non‐pregnant subjects, 15 normotensive pregnant women and 16 pre‐eclamptic women (gestational age:33–36 weeks). Plasma ouabain‐like activity, measured as plasma‐induced variations in ouabain binding to human erythrocytes, proved significantly higher in both groups of pregnant subjects as compared to normotensive non‐pregnant women, and a significant difference was also found between pre‐eclamptic and normotensive pregnant women, the former exhibiting higher plasma ouabain‐like activity. No differences in intracellúlar sodium and potassium levels were detected among the three groups studied. Though there is reason to believe that the high plasma levels found both in normal and hypertensive pregnancy may depend on placental production, we are not in a position to define with any degree of certainty what the mechanism or mechanisms are that regulate ouabain‐like factor production.

Collagen I and III mRNA gene expression and cell growth potential of skin fibroblasts in patients with essential hypertension

Objectives Despite the claimed disregulation of extracellular matrix synthesis and the increased proliferation rate of different cell types in experimental models of hypertension, very few data are available on collagen synthesis and the proliferation rate of fibroblasts in essential hypertensive patients. Design We measured collagen I, collagen III, histone H3 mRNA gene expression, collagen protein concentration and thymidine incorporation in fibroblasts from 17 essential hypertensive patients (EH) and 13 healthy normotensive control subjects (NC). Methods A Northern blot analysis was performed on fibroblasts in culture obtained from skin biopsies. Collagen protein concentration and DNA synthesis were measured by means of incorporation of tritiated proline and tritiated thymidine, respectively. Results In cultivated fibroblasts from hypertensives, the expression of collagen III mRNA after addition of fetal calf serum was significantly increased in comparison with that of normotensive-derived cells. After addition of fetal calf serum, collagen protein was statistically increased in cultures from EH patients as compared to NC. In hypertensives, the expression of histone H3 mRNA as well as tritiated thymidine incorporation were both increased as compared to normotensives. Conclusions Our data suggest that cultivated fibroblasts from essential hypertensive patients are characterized by an increased expression of type III collagen mRNA and collagen protein synthesis in response to fetal serum, as compared to normotensive-derived cells. Cells from hypertensives are characterized by an increased rate of proliferation after addition of fetal serum, as ascertained by increased thymidine incorporation and increased histone H3 mRNA gene expression, as compared to normotensive-derived cells. This phenotype could be genetically determined and may have an important role in the pathogenesis of essential hypertension.

Erythrocyte Na+-H+ exchanger kinetics and Na+-Li+ countertransport activity in essential hypertensive patients

The authors measured Na+–H+ exchanger kinetics together with Na+–Li+ countertransport Vmax in the erythrocytes of 21 subjects with essential hypertension and 16 normotensive control subjects. Na+–H+ exchanger Vmax appeared to be increased in patients with essential hypertension, while the Na+–H+ exchanger affinity for intracellular proton sites (K50%) proved to be unchanged and the index of cooperativity among intracellular proton binding sites as measured by Hills coefficient (Hills n) decreased as compared with normotensive control subjects. Na+–Li+ countertransport Vmax appeared to be higher in patients with essential hypertension than in control subjects. The authors were unable to find any correlations between Na+–H+ exchanger kinetic parameters and metabolic variables such as parameters of insulin resistance and plasma lipids. On the basis of the data obtained, erythrocyte Na+–H+ exchanger activity was found to be abnormal in two kinetic variables in essential hypertensive patients and showed no simple linear correlations with the main variables of glucose metabolism, plasma lipids, renin or aldosterone.

Intralymphocyte Free Magnesium in a Group of Subjects With Essential Hypertension

Despite the importance of magnesium in essential hypertension, few data are available on the ionized intracellular concentration of this ion. We therefore studied intralymphocyte free intracellular magnesium (Mgi) in 32 untreated essential hypertensive subjects and 27 normotensive control subjects by means of a fluorimetric technique based on the use of the new magnesium-sensitive dye furaptra. We also measured intralymphocyte ionized calcium (Cai) with fura 2. No statistically significant differences were found in Mgi in hypertensive compared with normotensive subjects (essential hypertensive, 0.291 +/- 0.053 mmol/L; normotensive, 0.293 +/- 0.043 [mean +/- SD]). A statistically significant inverse correlation was established between Mgi and plasma triglycerides in essential hypertensive subjects (r = -.521, P = .002). The hypertensive group was arbitrarily divided into two subgroups according to plasma triglyceride levels (> 2 [n = 10] or < 2 mmol/L [n = 22]), and Mgi proved to be significantly lower in the subgroup with high plasma triglyceride levels compared with either the subgroup with normal triglycerides (P = .009; 95% confidence interval, 0.013-0.088) or the normotensive control group as a whole (P = .03; 95% confidence interval, 0.003-0.069) (high-triglyceride hypertensive subgroup, Mgi = 0.256 +/- 0.045 mmol/L; normal-triglyceride hypertensive subgroup, Mgi = 0.307 +/- 0.049). No statistically significant differences were found in Cai in hypertensive compared with normotensive subjects (hypertensive, 53 +/- 12 nmol/L; normotensive, 54 +/- 14). We did not find statistically significant correlations between Cai and plasma triglycerides, nor did we find any differences in Cai between the subgroup of hypertensive subjects with high plasma triglyceride levels and either the subgroup of hypertensive subjects with normal triglycerides or the normotensive control group as a whole. The discrepancies between our results in lymphocytes and data relating to either erythrocytes or platelets emphasize the need for caution before the results are extrapolated from one tissue to the other. The decreased Mgi levels in the subgroup of high-triglyceride hypertensive subjects may suggest a role for magnesium in plurimetabolic syndrome.

Anti-angiogenic effects of two cystine-knot miniproteins from tomato fruit

BACKGROUND AND PURPOSE Cystine‐knot miniproteins are characterized by a similar molecular structure. Some cystine‐knot miniproteins display therapeutically useful biological activities, as antithrombotic agents or tumour growth inhibitors. A critical event in the progression of tumours is the formation of new blood vessels. The aim of this work was to test two tomato cystine‐knot miniproteins for their effects on endothelial cell proliferation and angiogenesis in vitro.