A. Antonello

Cyclosporin‐induced endothelial dysfunction and hypertension: are nitric oxide system abnormality and oxidative stress involved?

Abstract Hypertension is a major side effect of cyclosporin (CsA). While the mechanism(s) responsible are unclear, CsA‐induced endothelial dysfunction and CsA‐induced hypertension have been attributed to the CsA effect on the endothelial‐derived factors controlling vasomotor tone. Endothelial nitric oxide (NO) is crucial in the maintenance of a state of basal vasodilation, and recent studies have suggested an NO‐mediated counterregulatory mechanism protective from CsA‐induced vasoconstriction. Our study evaluates endothelial nitric oxide synthase (ecNOS) gene status (PCR analysis) and plasma levels of NO metabolites (ELISA) in kidney and heart transplant patients under chronic CsA treatment with CsA‐induced hypertension. Since CsA increases superoxide production, which metabolises NO, plasma hydroperoxides from cholesterol esters and from triglycerides and peroxynitrite were also evaluated (HPLC) as an index of the presence of superoxides and of “oxidative stress”. Quantification of monocyte ecNOS mRNA and NO metabolites plasma levels from patients and controls (C) demonstrated NO system upregulation in patients notwithstanding the hypertension. The mean ecNOS to β‐actin ratio was 1.80 ± 0.85 in patients vs 0.40 ± 0.09 in C (P < 0.04). NO metabolites were 34.03 ± 14.32 μM in patients vs 11.53 ± 5.64 μM in C (P < 0.001). Hydroperoxides from cholesterol esters and from triglycerides were also increased in patients, 3.4 ± 1.4 vs 1.3 ± 0.6 integrated area units (i. a. u.), P < 0.007 and 10.6 ± 6.4 vs 1.3 ± 0.8 i.a.u., P < 0.008, respectively, as well as the peroxynitrite plasma level, 0.32 ± 0.11 μM/l vs undetectable in C. This study confirms a CsA‐induced NO system upregulation in transplanted patients. However, the NO‐mediated counterregulatory system to CsA‐induced vasoconstriction, present in normals, could be canceled in patients by CsA‐induced superoxide (O2−) and free radical production which, by increasing NO metabolism, could contribute to CsA‐induced vasoconstriction and hypertension and predispose to atherosclerosis.

Increased urinary NO2−/NO3− and cyclic guanosine monophosphate levels in patients with bartter's syndrome: Relationship to vascular reactivity

Nitric oxide (NO) is a potent endogenous vasodilator and plays a pivotal role in the control of vascular tone by the formation of cyclic guanosine monophosphate (GMP). Patients affected by Bartters syndrome have lower than normal vascular reactivity with normohypotension and decreased peripheral resistances in spite of biochemical and hormonal abnormalities typical of hypertension, and it is possible that increased production of NO may be involved in maintaining this reduced vascular response and vasodilatation. We have examined this possibility by studying NO2-/NO3- and cyclic GMP urinary excretions to assess NO production in vivo in seven patients affected by Bartters syndrome compared with seven healthy controls. A group of five patients with hypokalemia other than Bartter syndrome (pseudo-Bartters) was also included in the study to evaluate the effect of hypokalemia on NO production. NO2-/NO3- urinary excretion (0.45 +/- 0.14 v 0.25 +/- 0.04 micromol/micromol urinary creatinine [controls], P < 0.005, v 0.28 +/- 0.05 [pseudo-Bartters], P < 0.01) and cyclic GMP urinary excretion (0.057 +/- 0.028 v 0.022 +/- 0.01 micromol/micromol of urinary creatinine [controls], P < 0.009, v 0.024 +/- 0.004 [pseudo-Bartters], P < 0.02) were increased in patients with Bartters syndrome in comparison with controls and pseudo-Bartters, and a linear correlation between these two parameters was also present (P < 0.001). We conclude that in Bartters syndrome the increased NO2-/NO3- and cyclic GMP urinary excretions point to an increased NO synthesis, which could account for the reduced vascular response of the disease, therefore adding its role in determining the vascular hyporeactivity of Bartters syndrome.

OXIDATIVE STRESS AND TGFBETA IN KIDNEY-TRANSPLANTED PATIENTS WITH CYCLOSPORIN-INDUCED HYPERTENSION. EFFECT OF CARVEDILOL AND NIFEDIPINE

Cyclosporin is a powerful stimulator of oxidative stress signaling, leading to TGFbeta production, NO degradation, endothelial dysfunction, hypertension and post-transplant nephropathy. Carvedilol, alpha1-beta-blocker with strong antioxidant activity, may interfere with this chain of events. Therefore, we measured monocyte ecNOS, TGFbeta and heme oxygenase-1 (HO-1) mRNA level and plasma nitrite/nitrate, 3-nitrotyrosine, an estimate of peroxynitrite, and total plasma antioxidant power in kidney-transplanted patients with post-transplant hypertension, before and after treatment with carvedilol, 25 - 50 mg o.d. orally for 4 months (n = 15). The dihydropyridine calcium channel blocker nifedipine (n = 10) was used as comparator antihypertensive drug. Blood pressure fell to a similar extent with both drugs. Carvedilol increased plasma antioxidant power and HO-1 mRNA and reduced 3-nitrotyrosine and TGFbeta mRNA levels, while the same was not observed with nifedipine. Monocyte ec NOS mRNA levels and plasma nitrite/nitrate were higher in the patients than in a normotensive healthy control group and were unaffected by either treatment. In conclusion, carvedilol reduces the oxidative stress and corrects the altered cellular signaling mediated by oxidative stress in CsA-induced post-transplant hypertension. Therefore, it may prevent long-term complications, such as endothelial dysfunction, fibrogenesis and post-transplant nephropathy by decreasing NO degradation and production of TGFbeta, a key fibrogenic cytokine, and by activating HO-1 production.

Carotid artery lesions in patients with nondiabetic chronic renal failure

Atherosclerotic complications are the leading cause of death in chronic renal failure (CRF) patients. Therefore, we wished to investigate the prevalence of carotid artery lesions (CALs) in these subjects. Two groups were evaluated by high-resolution echo Doppler: group 1 included 103 patients (68 males and 35 females) affected by nonnephrotic CRF and group 2 included 100 control subjects (60 males and 40 females). The prevalence of hypertension was 84% in both groups. The exclusion criteria included diabetes mellitus and symptoms of cerebrovascular disease. In the two groups we evaluated clinical history, physical examination, total cholesterol, triglycerides, fibrinogen, blood cell counts, blood urea nitrogen, creatinine, 24-hour proteinuria, and urine analysis. In group 1 patients the following lipid profile parameters were also evaluated: low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, lipoprotein(a), ApoAI, ApoAII, and ApoB. Group 1 had higher triglycerides and fibrinogen than group 2. A lower body mass index was found in group 1 than in group 2. The prevalence of CALs was significantly higher in the CRF patients than in the control subjects (62% v 47%; P = 0.04). The difference between the two groups was more striking among normotensive patients (62% v 19%; P = 0.03). All CRF patients affected by peripheral arterial disease and 86% of those having coronary artery disease had associated CALs. In CRF patients the severity of CALs was positively correlated to age, white blood cell count, triglycerides, and fibrinogen. Nondiabetic CRF patients have a higher prevalence of carotid artery lesions than control subjects. Several factors besides hypertension, including lipids, blood coagulation, and leukocytes, could contribute to the accelerated atherosclerosis of CRF patients.

Intracellular calcium signalling and vascular reactivity in Bartter's syndrome

We investigated patients affected by Bartters syndrome in the attempt to localize the intracellular defect mediating the reduced intracellular Ca2+ mobilization that may be responsible for the decreased vascular reactivity characteristic of Bartters syndrome. Using the formylmethionyl-leucyl-phenylalanine (fMLP) receptor system, which causes, intracellular calcium release, we investigated fMLP-stimulated intracellular inositol 1,4,5-trisphosphate (IP3) production as well as the number and affinity of fMLP receptors in neutrophils from Bartters syndrome patients and healthy controls. Scatchard plot analysis of radioactive fMLP binding to neutrophils indicated that there were no differences in either cell receptor number and affinity for ligand between healthy controls (n = 5) and patients with Bartters syndrome (n = 5): 6,151 +/- 1,431 vs. 7,112 +/- 2,566 receptors/cell; K(D): 0.446 +/- 0.14 vs. 0.454 +/- 0.09 pM of fMLP. 5- and 10-second fMLP-stimulated intracellular IP3 production was instead reduced in patients affected by Bartters syndrome: 2.479 +/- 1.07 vs. 4.073 +/- 1.04 nmol/10(7) cells at 5 s (n = 8; p < 0.01); 1.673 +/- 0.741 vs. 3.766 +/- 1.348 nmol/10(7) cells at 10 s (n = 8; p < 0.005). The results of this study indicate that the anomaly of intracellular calcium mobilization in patients with Bartters syndrome arises from a defect at the postreceptor level. The anomalous calcium signalling that takes place in Bartters syndrome may provide a mechanism for the hyporesponsiveness to pressor stimuli characteristic of these patients.

A procedure for the determination of a renin inhibitor in human plasma

Abstract An improved method for the determination of a phospholipid, which inhibits renin and is present in human plasma, is described. The phospholipid is extracted from plasma, added to a reconstituted renin-angiotensinogen system free from endogenous phospholipase(s) and then activated by the addition of an excess of exogenous phospholipase A. Angiotensin I produced in an assay medium containing renin-angiotensinogen and phospholipase A is compared with angiotensin I developed in an assay medium containing renin-angiotensinogen-phospholipid and phospholipase A. The inhibition of renin activity is expressed as percentage reduction in the production rate of angiotensin I, evaluated by radioimmunoassay of angiotensin I.

Giovan Battista Morgagni, a Pioneer of Clinical Nephrology

In the 18th century, Giovanni Battista Morgagni was the first to propose that specific signs and symptoms are linked to particular anatomical changes at autopsy and that these changes were the cause of the disease. This paper describes the report by Morgagni wherein he linked the anatomic findings at autopsy, specifically atrophied kidneys, with the signs and symptoms of a disease now known as uremia. From these findings, Morgagni felt that he had identified the factors responsible for the disease as well as its clinical course.

Effect on blood pressure of intravenous administration of a phospholipid renin preinhibitor and its active form in renal hypertensive rats

SummaryIt has been evaluated the effect of acute intravenous administration of a phospholipid renin preinhibitor and its active form (lysophospholipid) in rats rendered hypertensive by unilateral renal ischemia, by continuous infusion of homologous renin and in normal control rats.Both the substances have no effect on blood pressure in normal rats.In rats rendered hypertensive by unilateral renal ischemia or by continuous infusion of homologous renin, injection of inactive phospholipid does not lower blood pressure, while the same quantity of active lysophospholipid brings about a significant reduction. This observation suggest either the absence of circulating specific phospholipase(s), or their non activation of the preinhibitor.

Urinary angiotensinogen loss in chronic proteinuric glomerulonephritis.

Urinary angiotensinogen loss, transferrinuria and transferrin clearance, gamma G globulinuria and gamma G clearance, and the selectivity of proteinuria have been evaluated in 10 patients affected by proteinuric renal diseases. Urinary angiotensinogen concentration appeared to be very small in all cases (0.80±0.63 s.d. ng/ml). The absence of correlation between the urinary loss of angiotensinogen and the loss and the clearance of transferrin, side by side with the significant correlation between angiotensinogenuria and urinary loss and clearance of gamma G globulin, and the selectivity of proteinuria support the hypothesis that human angiotensinogen behaves like a high molecular weight protein.

Water and its effects when drunk cold - The physician's view (1576-1751)

Starting with Baldassare Pisanelli’s book Trattato della natura de’ cibi et del bere, published in Venice in 1586, the controversies that have kept physicians busy over the centuries regarding the relative importance of water in human health are traced. These controversies were of considerable importance as the Latin word for water ‘aqua’ is derived from the phrase ‘a qua vinimus’ (from whence we come). However, until the studies of Nicolas Lemery, one of the most important pharmacologists of the 18th century, the controversies were debated using more theoretical, philosophical arguments. Lemery’s studies shifted the debates from those based on philosophical arguments to more physiologically and scientifically based arguments.