Circulating endothelin-1 levels increase during euglycemic hyperinsulinemic clamp in lean NIDDM men.

OBJECTIVE: To evaluate whether or not insulin stimulates endothelin (ET)-1 secretion in vivo. RESEARCH DESIGN AND METHODS: Plasma ET-1 levels were evaluated in 16 lean normotensive men with non-insulin-dependent diabetes mellitus (NIDDM) (mean age 50.3 +/- 4.1 years) during either a 2-h euglycemic hyperinsulinemic clamp (40 mU insulin.m-2.min-1) or placebo infusion (50 ml isotonic saline) according to a single-blind randomized crossover protocol. RESULTS: Circulating ET-1 levels increased during the euglycemic hyperinsulinemic clamp (from 0.88 +/- 0.38 pg/ml at time 0 to 1.66 +/- 0.22 pg/ml and 1.89 +/- 0.99 pg/ml at 60 and 120 min, respectively [P < 0.05 vs. time 0]) and returned to baseline levels after the discontinuation of insulin infusion (0.71 +/- 0.22 pg/ml after a 30-min period of recovery [NS]). Compared with placebo, the euglycemic hyperinsulinemic clamp induced a significant increase in plasma ET-1 levels at 60 min (P < 0.0001) and 120 min (P < 0.0001). Changes in basal insulin levels and corresponding changes in circulating ET-1 levels after a 2-h euglycemic hyperinsulinemic clamp were significantly correlated (r = 0.771, P < 0.0001). A possible unfavorable effect of ET-1 on the tissue sensitivity to insulin-stimulated glucose uptake was suggested by the presence of a negative correlation between total glucose uptake and baseline ET-1 levels (r = -0.498, P < 0.05). CONCLUSIONS: Our findings indicate that circulating ET-1 levels significantly increase during euglycemic hyperinsulinemic clamp in men with NIDDM. The negative correlation between total glucose uptake and circulating ET-1 levels suggests that the peptide might exert negative effects on the insulin sensitivity of target tissues. The consequent increase in insulin secretion as well as the insulin-related ET-1 release from endothelial cells could favor the development of diabetes-related vascular lesions.

Enhanced blood pressure response to cyclooxygenase inhibition in salt-sensitive human essential hypertension.

To evaluate the influence of salt sensitivity on the blood pressure response to oral indomethacin treatment, we studied 35 hospitalized essential hypertensive patients (24 men and 11 women, aged from 40 to 55 years). During a normal NaCl intake (120 mmol Na+ per day), patients were assigned to receive in a randomized double-blind fashion either 200 mg indomethacin (25 patients) or placebo (10 patients) for 5 days. Two weeks after the interruption of indomethacin treatment, during which the normal NaCl intake was continued, salt sensitivity was assessed by giving each patient a high (220 mmol Na+ per day for 10 days) and then a low (20 mmol Na+ per day for 10 days) NaCl diet. Blood pressure changes were evaluated, and the measurement taken at the end of the 2 weeks under normal sodium intake was considered baseline blood pressure. Patients were classified as salt sensitive when a diastolic blood pressure change of 10 mm Hg or more occurred after both low and high periods of sodium intake. In salt-resistant patients treated with indomethacin (n = 12, nine men and three women, mean age 50.5 +/- 3.7 years), neither blood pressure (systolic blood pressure from 150.8 +/- 11.2 to 154.6 +/- 9.3 mm Hg, NS; diastolic blood pressure from 99.3 +/- 2.1 to 101.1 +/- 4.4 mm Hg, NS) nor the urinary Na+ excretion (from 108.1 +/- 20.9 to 97.9 +/- 9.1 mmol/24 hr, NS) was significantly affected by the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of systolic time intervals in asymptomatic patients with primary hyperlipoproteinemia.

Previous studies have focused on the usefulness of systolic time intervals to assess changes of myocardial function. In a recent report, hyperlipoproteinemia (HLP) was shown to induce early signs of vascular disease in asymptomatic subjects. By means systolic time intervals (STI) we studied left ventricular functions in normal subjects and asymptomatic patients with HLP, who showed normal response to exercise on a bicycle ergometer. The results showed mean values of STI for the population in the normal range, according to standards accepted in North American reports. Different values of STI were found when we compared the data of controls with the STI of HLP patients with higher values of PEPI and PEP/LVET and lower values of LVETI in HLP patients. These results suggest that hyperlipoproteinemia affects STI in asymptomatic patients, probably as a sign of early impairment of left myocardial function.

Plasma insulin levels do not change during atrial natriuretic factor infusion in human essential hypertensives.

In order to evaluate the effects of atrial natriuretic factor (ANF) infusion on plasma insulin (IRI) in hypertension, 32 essential hypertensives (aged 40 to 62 years) were studied. After 1 week of pharmacologic washout under normal sodium intake (120 mEq of Na+/day), patients were randomly assigned to receive either ANF (0.04 micrograms/kg/min) or its vehicle (50 mL of isotonic saline) over a 60-min period in supine position. Plasma IRI and glucose were measured at -60, 0, 20, 40, 60, 120, 180, and 240 min (infusion time: from 0 to 60 min). Plasma levels of IRI and glucose did not change significantly during ANF infusion. On the contrary, after ANF discontinuation plasma IRI rose from levels of 13.5 +/- 6.4 microU/mL at 60 min to values of 20.1 +/- 11.3 microU/mL at 240 min (P less than .0001 v time 0). Plasma glucose showed a similar behavior, increasing from values of 100.4 +/- 5.0 mg/dL at 60 min to values of 120.0 +/- 5.1 mg/dL at 240 min (P less than .02 v time 0). Our findings suggest that ANF did not influence insulin release in hypertensives. The increase of plasma glucose and IRI observed after ANF discontinuation could be due to the relapse of sympathetic activity, suppressed during ANF infusion.

Erythrocyte Na-K-Cl cotransport activity in low renin essential hypertensive patients. A 23Na nuclear magnetic resonance study.

The Na-K-Cl cotransport activity in red blood cells from essential hypertensive men with low (n = 8, mean age 42 +/- 4 years) or normal renin activity (n = 4, mean age 43 +/- 3 years), and in normotensive men with normal renin activity (n = 7, mean age 38 +/- 4 years) has been evaluated by means of a recently developed 23Na nuclear magnetic resonance (NMR) method. Sodium efflux was determined by relating the resonating frequency of the NMR signal from extracellular sodium to sodium concentration in the presence of the shift reagent Dy(PPP)2(7-). The maximum Na+ efflux driven by cotransport (Vmax) was measured in Na(+)-loaded erythrocytes in the presence of ouabain to block the Na-K-Cl pump activity. A significant difference (P < 0.05) was found in Vmax values of low renin patients (0.70 mmol/h/L cells, range 0.40 to 0.90 mmol/h/L cells) as compared with normotensive controls (0.39 +/- 0.08 mmol/h/L cells) and normal renin hypertensives (mean 0.49 +/- 0.04 mmol/h/L cells). In conclusion, this study showed an increased activity of the Na-K-Cl cotransport in red blood cells from low renin hypertensive men as compared with normal renin hypertensives and normotensives.

Left ventricular function after coronary artery bypass. Non-invasive study by systolic time intervals.

Left ventricular function was evaluated with serial recording of STI intervals in 78 patients with stable angina on effort undergoing coronary and left ventricular cineangiography. On the basis of these data the patients were divided into four groups: OV) nor or mild coronary disease (n. 11); 1V) 70% stenosed vessel; 2V) two significantly affected vessels (n. 32); 3V) three significantly affected vessels (n. 18). Thirty-six patients (9 with one stenosis, 17 with 2, 10 with 3) underwent coronary artery bypass. Thirty-one 8 with one, 15 with 2, 8 with 3) refused the treatment in spite of the same clinical situation and were medically treated. Recordings were performed before medical and surgical treatment and after 6 and 12 months. Initial average values of the patients of 2V and 3V groups showed a shorter LVETI, longer PEPI and higher PEP/LVET ratio than those of 1V and 0V groups. Subjects of 2V group and abnormal left ventricular wall motion showed longer PEPI and higher PEP/LVET than patients of 2V without abnormal wall motion. On first evaluation no differences were observed between surgical and medical groups. The latter did not show any difference after 6 and 12 months. Surgical patients of 2V and 3V showed a longer LVETI, shorter PEPI and a lower PEP/LVET than the medical group. In the surgical group PEPI and PEP/LVET were significantly decreased after surgery while LVETI was prolonged. Our results suggest an improvement of left ventricular performance by coronary artery bypass in patients with coronary artery disease.

[The efficacy and tolerance of orally administered kallikrein in patients with essential arterial hypertension]. / Efficacia e tollerabilità della somministrazione orale di callicreina in pazienti affetti da ipertensione arteriosa essenziale.

Since the reduced kallikrein excretion demonstrated in essential hypertension suggested the possibility of an impairment in the renal kallikrein-kinin system, we decided to evaluate the efficacy and safety of oral kallikrein administration (glandular kallikrein derived from porcine pancreas) in 30 essential hypertensive subjects (21 males, 9 females, age range 34-62 years). Twenty subjects took 150 IU kallikrein t.i.d. for eight days; during this period their sodium intake remained normal (120 mEq Na+/die). Ten subjects took placebo. After the trial period, urinary kallikrein in the active group increased from 0.9 +/- 0.4 U/24 h (normal value greater than 1.2 U/24 h) to 1.6 +/- 1 U/24 h (p less than 0.05); systolic and diastolic blood pressure decreased respectively from 154.6 +/- 13.8 mmHg to 140.3 +/- 12.5 mmHg (p less than 0.01) and from 92.5 +/- 1.5 mmHg to 86 +/- 3.9 mmHg (p less than 0.025); urinary sodium and potassium excretion increased respectively from 96.7 +/- 17 mEq/24 h to 119.1 +/- 32.3 mEq/24 h (p less than 0.05) and from 36.7 +/- 11 mEq/24 h to 43.5 +/- 12.8 mEq/24 h (p less than 0.05). One patient in the kallikrein group suffered a transient episode of gastric pain. No modifications of the parameters evaluated were observed in the placebo group. We conclude that kallikrein has a mild hypotensive effect in hypertensive subjects and is generally well-tolerated. Its antihypertensive effect is probably due to the sodiuretic action of the substance.

[Sodium-modulating hormones and the pressor response to sodium chloride in essential arterial hypertension]. / Ormoni sodiomodulanti e risposta pressoria al cloruro di sodio nell'ipertensione arteriosa essenziale.

Some predictive markers for NaCl sensitivity, related to the red blood cell membrane or to circulating proteins, have already been described in human essential hypertension. The present study was planned to investigate whether or not some hormones produced by the kidney or acting at the kidney level could be used as new markers for NaCl sensitivity. The study was conducted in 28 not previously treated outpatients affected by uncomplicated mild to moderate essential hypertension. After 15 days on a normal NaCl diet, plasma renin activity (PRA), plasma atrial natriuretic peptide (ANP), and the urinary excretion of active kallikrein were evaluated. The sensitivity of blood pressure to changes in NaCl intake was then assessed in all patients, according to a randomized double blind cross-over design. Each patient was assigned to a high (240 mmol of NaCl/day for 15 days) or low (40 mmol of NaCl/day for 15 days) NaCl intake. During the assessment of NaCl sensitivity, the double blindness was achieved by the use of capsules containing either NaCl or placebo. Fifteen patients (11 males and 4 females) resulted as NaCl-sensitive, while 13 patients (8 males and 5 females) were classified as NaCl-resistant. Our results indicate that PRA levels were significantly lower in the NaCl-sensitive group than in the NaCl-resistant one (0.108 +/- 0.05 ng/L/s vs 0.247 +/- 0.16 ng/L/s, p < 0.007), in the presence of raised levels of plasma ANP in NaCl-sensitive hypertensives (18.08 +/- 4.61 fmol/mL vs 12.45 +/- 3.77 fmol/mL, p < 0.006).(ABSTRACT TRUNCATED AT 250 WORDS)

[Primary hyperaldosteronism caused by monolateral adrenal hyperplasia]. / Iperaldosteronismo primario da iperplasia surrenalica monolaterale.

We have reported two patients with unilateral adrenal hyperplasia as a rare cause of primary aldosteronism, and discussed the literature on this subject. When diagnosed by NMR-CT imaging and selective sampling from adrenal veins, the treatment of this disorder appears to be surgical. Whether its pathogenesis is related to the more common varieties of primary aldosteronism is open to speculation according to metabolic findings.

[Oral administration of extracted kallikrein to patients with essential arterial hypertension]. / Somministrazione orale di callicreina estrattiva in pazienti affetti da ipertensione arteriosa essenziale.

Reduced kallikrein excretion has been demonstrated in essential hypertension, suggesting an impairment of the renal kallikrein-kinin system. Therefore, we evaluated the efficacy and safety of oral kallikrein administration (glandular kallikrein derived form porcine pancreas) in 20 essential hypertensives (14 males and 6 females) aged between 34 and 62 years. Kallikrein was administered (150 U.I. three times daily) over a period of eight days, under normal sodium intake (120 mEq of Na+/day). After the kallikrein administration period, urinary kallikrein resulted increased (from 0.9 +/- 0.4 U/24h, normal value greater than 1.2 U/24h, to 1.6 +/- 1 U/24h; p less than 0.05). Blood pressure decreased (systolic: from 154.6 +/- 13.8 mmHg to 140.3 +/- 12.5 mmHg; p less than 0.01--diastolic: from 92.5 +/- 1.5 mmHg to 86 +/- 3.9 mmHg; p less than 0.025), while urinary excretion of sodium (from 96.7 +/- 16 mEq/24h to 119.1 +/- 32.2 mEq/24h; p less than 0.05) and potassium (from 36.7 +/- 11 mEq/24h to 43.5 +/- 12.8 mEq/24h; p less than 0.05) increased after kallikrein administration. We observed only a transient episode of gastric pain. In conclusion, kallikrein administration has a mild hypotensive effect in hypertensive patients, and is generally well tolerated. The antihypertensive action is probably due to the natriuretic effect of kallikrein.

Varietal and pre-fermentative volatiles during ripening of Vitis vinifera cv Nebbiolo berries from three growing areas.

Flavour analysis of grape is a key step in quality evaluation. The Stir Bar Sorptive Extraction technique (SBSE, 'Twister'®) was used to assess varietal and pre-fermentative volatile accumulation in 'Nebbiolo' berries, from véraison to harvest. Grapes were collected in three vineyards, representing different 'crus' in the cultivation areas of Barolo, Barbaresco and Roero (North-West Italy). Volatile constituents of grapes were identified and quantified by GC-MS. We demonstrate the influence exerted by the growing location on volatile concentration and profile, as well as on the timing of volatile accumulation. The accumulation of certain classes of compounds, considered favourable for defining berry quality, followed common patterns, and was negatively correlated to that of compounds with herbaceous and grassy notes, such as the C6 compounds. PCA analysis shows that the concentrations of varietal and pre-fermentative volatiles were more effective in separating growing areas than dates of harvest. Grapes from the Barbaresco area, showing higher values of the concentration ratio between favourable and unfavourable compounds throughout ripening, could be statistically separated from grapes from the other areas.

Development of an enzyme immunoassay for the detection of hepatitis B surface antigen employing monoclonal antibodies.

The use of monoclonal antibodies in the development of a third generation microtitration plate enzyme immunoassay for the detection of hepatitis B virus (HBV) is described. These antibodies were tested either alone or in combination with polyclonal antibodies raised in rabbit. Horseradish peroxidase was employed in the conjugates and 3,3',5,5'-tetramethylbenzidine was used as the enzyme substrate. Effect of type and concentration of antibodies used in the coating solution and in preparing conjugates as well as reaction time are discussed. The designed test employs a 100-microliters sample, with an overall incubation time of 3.5 hr. Serum or plasma (EDTA or citrate as anticoagulant) can be used. The sensitivity limit of the test was 0.4 ng/ml for subtype ad and 0.5 ng/ml for subtype ay. When used as screening test, 99.6% specificity was obtained; predictive value was 97.5% for a positive result and 99.8% for a negative result. According to the performance of the test, it seems to be suitable for diagnosis in routine laboratory and screening in blood banks.

Urinary kallikrein and salt sensitivity in essential hypertensive males.

A strong influence of urinary kallikrein excretion on the salt sensitivity of blood pressure has been recently suggested in normotensive patients. To evaluate the relationship between kallikrein and salt sensitivity in essential hypertension, active kallikrein excretion, plasma renin activity, atrial natriuretic peptide and aldosterone levels were evaluated in 37 male hypertensives (mean age 43.3 +/- 4.7 years) after two weeks on a normal NaCl diet (120 mmol NaCl per day). After kallikrein determination, salt sensitivity was assessed in a randomized cross-over double-blind fashion by evaluating the blood pressure response to a high (240 mmol NaCl per day for two weeks) and a low (40 mmol NaCl per day for 2 weeks) NaCl intake. Blood pressure changes were evaluated considering as baseline blood pressure the measurement taken at the end of the 2 weeks under normal NaCl intake. Patients were classified as salt sensitive when a diastolic blood pressure change of 10 mm Hg or more occurred after both periods of low and high NaCl intake. At the end of the assessment of salt sensitivity, 19 hypertensive patients (mean age 43.0 +/- 4.6 years) were resistant. The urinary excretion of active kallikrein was significantly lower (P < 0.0001) in salt sensitive (0.51 +/- 0.36 U/24 hr) than in salt resistant patients (1.28 +/- 0.48 U/24 hr). Also, plasma atrial natriuretic peptide levels were higher in salt sensitive than in salt resistant hypertensives (P < 0.02), and a significant correlation between urinary kallikrein and plasma atrial natriuretic peptide was demonstrated in salt sensitive hypertensives (r = -0.691, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Active kallikrein response to changes in sodium-chloride intake in essential hypertensive patients.

To evaluate the behavior of active kallikrein excretion in salt-sensitive and salt-resistant hypertensive patients during changes in sodium-chloride (NaCl) intake, 61 male, nonobese, nondiabetic outpatients affected by uncomplicated essential hypertension were given a diet that contained 140 mmol NaCl per day for 2 wk. Patients then received either a low- (20 mmol NaCl/day) or a high- (320 mmol NaCl/day) sodium diet for 2 wk, according to a randomized, double-blind, cross-over protocol. Hypertensive patients were classified as salt sensitive when their diastolic blood pressure rose by at least 10 mm Hg after the high-sodium diet, and decreased by at least 10 mm Hg after the low-sodium diet, considering as baseline blood pressure values those that were taken at the end of the 140 mmol NaCl/day intake period. The remaining patients were classified as salt resistant or, when diastolic blood pressure increased by 10 mm Hg or more after low-sodium intake, as counter-regulating. Twenty-three patients were therefore classified as salt sensitive, 28 as salt resistant, and 10 as counter-regulating. The baseline active kallikrein excretion was significantly lower (P < 0.0001) in salt-sensitive (0.62 +/- 0.31 U/24 h) patients than in salt-resistant (1.39 +/- 0.44 U/24 h) and counter-regulating patients (1.27 +/- 0.38 U/24 h). Surprisingly, the kallikrein response to changes in sodium intake was similar in all subgroups, although enzyme excretion was always at the lowest level in salt-sensitive hypertensive patients. This latter group also showed the highest plasma atrial natriuretic peptide levels (28.2 +/- 8.5 fmol/mL, P < 0.0001 versus salt-resistant and counter-regulating patients), and the greatest peptide increment with sodium load (P < 0.0001 versus salt-resistant and counter-regulating patients). Counter-regulating patients showed the steepest increase in plasma renin activity (from 0.24 +/- 0.18 to 0.83 +/- 0.21 ng/L per s, P < 0.001) and decrease of plasma atrial natriuretic peptide (from 26.1 +/- 6.3 to 6.8 +/- 3.1 fmol/mL, P < 0.001) when switched from a high to a low-sodium intake. In conclusion, salt-sensitive hypertensive patients excrete less active kallikrein than do salt-resistant and counter-regulating patients, but maintain a normal enzyme response to changes in dietary sodium intake. The exaggerated response of atrial natriuretic peptide to high-sodium intake that was observed in the same patients could be compensating for an impaired renal capability to excrete a sodium load.