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Biomedical subjects

A Semplicini

Publications and source records attributed to A Semplicini.

At least 19 recordsLinked to original sources
PubMed2006

Effect of doxazosin on oxidative stress related proteins in essential hypertensive patients.

The role of oxidative stress in the pathophysiology of hypertension has stimulated the investigation of strategies to reduce oxidative stress via antioxidant defenses. Using a molecular biology approach, we report, in essential hypertensive patients, the effect of doxazosin treatment on the mononuclear cell gene and protein expression of two major elements in the oxidative stress and vascular remodeling-related pathways: p22(phox) and PAI-1. Ten essential hypertensive patients were treated with Doxazosin (4 mg/day) for two weeks (EH + D) and compared with ten untreated hypertensive patients (EH) and ten normotensive subjects (C). In EH p22(phox) and PAI-1 mRNA and protein level was increased compared with C. In EH + D, doxazosin reduced p22(phox) and PAI-1 gene and protein expression, which was similar to that of C. These results demonstrate for doxazosin an inhibitory effect on oxidative stress related proteins at gene and protein level, which confirms at molecular level a powerful antioxidant potential for this agent that could translate, in the long term, into a powerful antiatherosclerotic effect.

Adult↗
PubMed2005

Comparison between nifedipine and carvedilol in the treatment of de novo arterial hypertension after liver transplantation: preliminary results of a controlled clinical trial.

There is no controlled clinical trial on the treatment of de novo arterial hypertension after liver transplantation (LT) a common complication using calcineurin inhibitors (CNI) for immunosuppressive therapy. The aim of this study was to compare the efficacy and safety of nifedipine, a calcium channel blocker, and carvedilol, an alpha1- and beta-blocker. The study included 50 patients who developed arterial hypertension after LT. The data on the first 30 patients who have completed 12-month follow-up are reported herein. Eighteen patients received nifedipine, and 12 patients received carvedilol. Patients were evaluated monthly at the outpatient clinic for 1 year. If patients developed severe adverse effects to nifedipine, they were switched to carvedilol and vice versa (therapy failure). The two groups were similar for clinical features, indications for LT, immunosuppressive therapy, and baseline blood pressures. A failure of treatment was observed in 9 of 18 patients treated with nifedipine (50.0%) and one of 12 patients treated with carvedilol (8%, P < .025). Nifedipine was effective in 4 of 18 patients, carvedilol, in 4 of 12 patients (22.21% vs 33.3%, P = NS). Two of the nine nonresponders to nifedipine responded to carvedilol. The efficacy of monotherapy was observed in 11 of 40 randomized patients (27.5%). Carvedilol monotherapy is as effective as nifedipine but far better tolerated.

Blood Pressure↗
PubMed2003

Effect of epoetin on HO-1 mRNA level and plasma antioxidants in hemodialysis patients.

OBJECTIVE: Patients with renal failure and undergoing hemo- (HD) or peritoneal dialysis are under oxidative stress which is thought to contribute to the long-term complications noted in this patient population. One effect of HD-induced oxidative stress is via red blood cell (RBC) membrane lipid peroxidation leading to RBC destruction and anemia. Interaction of this oxidative stress with epoetin (EPO) treatment to increase RBC number and Hb concentration remains unexplored. PATIENTS AND METHODS: This preliminary study used RT-PCR as well as colorimetric based assay approaches to evaluate the effect of EPO-alpha treatment on markers of oxidative stress in hemodialysis patients. Eighteen patients (12 males, 6 females, age range 45 - 68), were treated with EPO-alpha (Eprex) 50 UI/kg thrice weekly over an 8-month study period. Monocytes were isolated at baseline, then monthly thereafter, monocyte heme-oxygenase-1 (HO-1) and plasma Hb and antioxidant power (AOP) were determined. RESULTS AND CONCLUSIONS: Treatment with EPO increased Hb (9.4 +/- 0.7 g/dl to 10.9 +/- 0.5, mean +/- SD p < 0.001). In addition, both monocyte HO-1 mRNA (0.34 +/- 0.08 vs. 0.59 +/- 0.02 d.u. p < 0.001) and plasma AOP (1,379.8 +/- 175 micromol/l to 1,624 +/- 170, p < 0.04) increased. While AOP changes showed no correlation with other indices, increases in HO-1 and Hb were positively correlated using 2 different measures: delta Hb (peak Hb - baseline Hb) vs. delta HO-1 (peak HO-1 mRNA - baseline HO-1 mRNA) as well as delta Hb(5 months-baseline) vs. delta HO-1 (5 months - baseline) mRNA (r = 0.81, p < 0.001 and r = 0.76, p < 0.001; respectively). In conclusion, the increases upon EPO treatment of both HO-1 gene expression and plasma AOP as well as the significant correlation between delta Hb and delta HO-1 mRNA suggest that EPO treatment reduces oxidative stress via a combination of effects. These could potentially include effects on oxidative stress directly as well as effects on the levels and types of antioxidants present in plasma.

Adult↗
PubMed2002

Increased red cell sodium-lithium countertransport and lymphocyte cytosolic calcium are separate phenotypes in patients with essential hypertension.

Increased red blood cell sodium-lithium countertransport (SLC) activity and elevated intracellular calcium have been observed in hypertensive patients. The association of these ion transport abnormalities with each other and with another phenotype, insulin resistance, has been suggested. We investigated whether elevated SLC activity and increased lymphocyte cytosolic calcium (Ca(cyt)) occur in the same individuals and whether either is associated with hyperinsulinaemia. We measured SLC activity, lymphocyte Ca(cyt)and fasting insulin levels in hypertensive patients and normal subjects. Consistent with prior studies, SLC activity was significantly and positively correlated with fasting insulin levels (r = 0.45, P < 0.01). However, SLC activity and lymphocyte Ca(cyt) were significantly but inversely correlated (r = -0.42, P < 0.01) and lymphocyte Ca(cyt) was also inversely correlated with fasting insulin (r = -0.55, P < 0.001). When the study participants were instead separated into two groups based on fasting insulin levels, those above the median (15 microU/ml) had significantly higher SLC activity and significantly lower Ca(cyt). When separated by lymphocyte Ca(cyt) levels (above or below 120 nM) those patients with low lymphocyte Ca(cyt) had significantly higher SLC activity and significantly higher insulin levels. Multiple linear regression showed that fasting insulin was significantly predictive of SLC activity (P = 0.05) and Ca(cyt) (P < 0.01). Thus, elevated SLC activity and increased lymphocyte Ca(cyt) are separate and distinct ion transport phenotypes in hypertensive patients, linked through a relationship to hyperinsulinaemia that is direct with SLC activity and inverse with lymphocyte Ca(cyt).

Adult↗
PubMed2002

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.

Adrenergic beta-Antagonists↗
PubMed2001

Analysis of Gq protein alpha subunit mRNA expression in human monocytes: relevance of the purification step.

BACKGROUND: Galphaq is a member of the Gq family of G proteins, which by stimulating the phospholipase Cbeta (PLCbeta)-IP(3)-Ca(++) mediated intracellular signaling systems controls some of the most fundamental cardiovascular cellular processes. The study of Galphaq is complicated by the presence of a pseudogene in human DNA, with signficant homology to the mRNA encoding the alpha subunit of Gq protein. The presence of this pseudogene will cause problems when the analysis of the Galphaq gene expression is based solely on RT-PCR. In this study, we report a simple method for avoiding unwanted amplification of the Galphaq pseudogene and the use of human monocytes as a readily available source for examining Galphaq. METHODS: RT-PCR was carried out on RNA extracted from peripheral blood monocytes of 10 normal subjects using specific primers for Galphaq. RESULTS: When several subjects' Galphaq was examined, the authentic Galphaq mRNA amplification product levels, as a ratio to unpurified pseudogene containing amplification products, declined by up to approximately 70%. CONCLUSION: Given the importance of Gq protein in cardiovascular signal transduction, it is fundamental to provide a reliable assessment of G alpha q gene expression. In addition to accurately assessing Galphaq levels, the use of circulating human monocytes as a useful source of Galphaq for investigating mechanisms involved in the regulation of vascular tone is shown.

Base Sequence↗
PubMed2001

G protein beta3 subunit gene 825T allele is associated with increased left ventricular mass in young subjects with mild hypertension.

BACKGROUND: A nucleotide substitution (C-->T) at position 825 of the gene GNB3 encoding the beta3 subunit of heterotrimeric G proteins is associated with alternative splicing and enhanced signal transduction. There is accumulating evidence from different populations that the 825T allele is associated with increased prevalence of hypertension, obesity, and left ventricular hypertrophy. However, it is unclear to what extent the 825T allele has a direct influence on left ventricular structure, independently of the effects of pressure and body mass index. Therefore we explored whether the GNB3 825T allele is associated with increased left ventricular mass index in a selected and homogeneous group of young, never treated, mild hypertensives. PROCEDURES: Young subjects (n = 207, aged 18 to 45 years) were genotyped at the GNB3 825 locus. In each patient, 24-h ambulatory blood pressure (BP) measurement and two-dimensional guided M-mode echocardiography combined with Doppler sonography were performed. RESULTS: The genotype distribution among patients was in Hardy-Weinberg equilibrium. Patients carrying the 825T allele had an increased left ventricular mass index (95.1 +/- 1.5 v 89.7 +/- 1.5 g/m2; P = .01) in comparison to those with CC genotype. The association between left ventricular mass index and 825T allele was independent of gender, age, BP, heart rate, alcohol intake, and physical activity. CONCLUSIONS: In young patients with mild hypertension without heart disease the 825T allele is associated with an increased left ventricular mass index. These hypothesis-generating data suggest that GNB3 825T allele may be considered as one genetic marker predisposing to an increase in left ventricular mass in hypertensives, and justifies larger studies.

Adult↗
PubMed2001

Abnormalities of Gq-mediated cell signaling in Bartter and Gitelman syndromes.

BACKGROUND: The constitutive endothelial isoform of nitric oxide synthase (ecNOS) and nitric oxide (NO) production are increased in patients with Bartter syndrome (BS) and Gitelman (GS) syndrome and may reduce vascular tone. Moreover, these patients present an abnormal cell signaling [reduced stimulated intracellular calcium ([Ca(2+)](i)) and inositol-1,4,5,triphosphate ([IP(3)](i)) in neutrophils], suggesting the presence of a generalized reduction of protein kinase C (PKC) and cell reactivity. Since PKC regulates ecNOS gene expression, we evaluated the signal transduction system involving Gq protein, PKC, and ecNOS in circulating nucleated cells from patients with BS/GS. METHODS: Nucleated blood cells from 2 BS and 7 GS and from 10 controls (C) were used. PKC activity was evaluated in neutrophils by radioenzymatic assay; PKC alpha concentration was evaluated in monocytes by Western blot analysis. ecNOS and G alpha q mRNA production was evaluated in monocytes by reverse transcription-polymerase chain reaction (RT-PCR) analysis using specific primers and quantitated by PCR-based semiquantitative analysis of ecNOS and G alpha q mRNA expression. RESULTS: Cytosol and membrane basal PKC activity were similar in neutrophils from BS/GS and C (70 +/- 3 vs. 80 +/- 2; 37 +/- 3 vs. 46 +/- 2 pmol/min/mg protein, respectively), while fMLP-stimulated membrane PKC activity increased to a lower extent in BS/GS (from 43 +/- 2 to 53 +/- 3 vs. 38 +/- 2 to 66 +/- 3 pmol/min/mg protein, P < 0.05 for the difference). Membrane PKC alpha expression was similar in basal conditions (8.5 +/- 1.5 vs. 12.4 +/- 4.0 densitometric units), but increased after fMLP was reduced in BS/GS (4.5 +/- 1.4 vs. 9.5 +/- 2.1, P < 0.01). In BS/GS, PKC stimulation with PMA dose dependently reduced ecNOS gene expression (from 0.80 +/- 0.05 to 0.78 +/- 0.03 densitometric units; PMA 50 nmol/L, P = NS; to 0.55 +/- 0.07, PMA 100 nmol/L, P < 0.001) to an undetectable expression (PMA 200 nmol/L). Qualitatively similar effects were seen in monocytes from control subjects. Incubation of monocytes from patients and controls with the PKC inhibitor GF109203X increased ecNOS mRNA, with no difference between patients and controls. G alpha q mRNA was reduced in BS/GS versus controls (0.87 +/- 0.013 vs. 0.98 +/- 0.005 densitometric units, P < 0.0004). CONCLUSION: An abnormal G alpha q expression blunts cell signaling and PKC production in BS/GS. A reduced PKC up-regulated NO system may contribute to the vascular hyporeactivity of BS/GS.

Adult↗
PubMed2001

Chronic renal failure, end-stage renal disease, and peritoneal dialysis in Gitelman's syndrome.

The chronic state of hypovolemia, hypotension, and hypokalemia found in Bartter's syndrome has been shown to lead to a chronic nephropathy, which then can progress toward end-stage renal disease and dialysis. This progression, however, has never been reported for Gitelman's syndrome, a variant of Bartter's syndrome that shows a milder clinical picture. This report is the first to document this progression (ie, the development of end-stage renal disease in Gitelman's syndrome) as well as the first report of the use of peritoneal dialysis in either Bartter's syndrome or Gitelman's syndrome. The clinical course highlights the importance of and the need for careful control of hemodynamic status in these patients to slow the progression of renal injury. The hemodynamic alterations that characterize Bartter's syndrome and Gitelman's syndrome patients suggest that for patients requiring renal replacement therapy, peritoneal dialysis is a more appropriate treatment because of its less severe impact on these parameters.

Adult↗
PubMed2001

Adrenomedullin stimulates DNA synthesis of rat adrenal zona glomerulosa cells through activation of the mitogen-activated protein kinase-dependent cascade.

BACKGROUND: Adrenal zona glomerulosa cells are provided with adrenomedullin receptors. Adrenomedullin has recently been found to enhance proliferation of cultured rat vascular smooth muscle cells and zona glomerulosa cells. OBJECTIVE: To investigate whether adrenomedullin affects rat zona glomerulosa proliferative activity through the tyrosine kinase and extracellular signal regulated kinases (ERKs) pathways. METHODS: Dispersed rat zona glomerulosa cells were cultured in vitro for 24 h and then exposed to adrenomedullin (10(-7) mol/l), alone or in the presence of tyrphostin-23 (10(-5) mol/l) or PD-98059 (10(-4) mol/l), for 24 or 48 h. To assess the rate of DNA synthesis, 5-bromo-2'-deoxyuridine (BrdU, 20 mg/ml) was also added to the medium and BrdU-positive cells were detected by immunocytochemistry. The expression of ERKs and the effect of adrenomedullin on ERKs phosphorylation and activity were assayed in dispersed zona glomerulosa cells. RESULTS: Adrenomedullin significantly increased the percentage of BrdU-positive (phase-S) zona glomerulosa cells; this effect was blocked by either the tyrosine kinase inhibitor, tyrphostin-23, or the mitogen-activated protein kinase kinase (MEK-1) inhibitor, PD-98059. Both zona glomerulosa and zona fasciculata/reticularis express ERK-1 (44 kDa) and ERK-2 (42 kDa) isoforms. However, adrenomedullin phosphorylated ERK-1 and ERK-2 only in the zona glomerulosa; this effect was blunted by the MEK-1 inhibitor, PD98059, and by the calcitonin gene-related peptide type 1 (CGRP-1) receptor antagonist, CGRP8-37, but not by the adrenomedullin C-terminal fragment, ADM22-52. CONCLUSION: Adrenomedullin stimulates the growth of rat zona glomerulosa cells through activation of CGRP-1 receptor, linked to the tyrosine kinase-MEK-1-ERKs signalling pathway. These results confirm the complex role played by this peptide in the regulation of zona glomerulosa cell physiology.

Adrenomedullin↗
PubMed2001

Hypertension and cerebrovascular diseases: a specific role of vascular protection for the prevention of dementia.

Despite the use of antihypertensive drugs, mortality (but not morbidity) from cerebrovascular diseases has been reduced significantly. As a consequence, an increasing number of patients suffer from recurring strokes and from the debilitating consequences of cerebrovascular diseases and develop progressive cognitive impairment. Its pathological substrates are regional alteration of cerebral perfusion, lacunae, white matter lesions, progressive cortical atrophy, even in the asymptomatic patient and in the absence of extracranial carotid artery stenosis. Lacunar infarction and white matter lesions are particularly frequent in the hypertensive diabetic patient. Lacunae and white matter lesions sometimes coexist and may favour the development of dementia in the hypertensive patient, through focal ischaemia, perivascular oedema, disruption of the blood-brain barrier, cerebral diaschisis and cortical deafferentation. Treatment with calcium channel blockers, angiotensin converting enzyme inhibitors and diuretics smooth the patchy hypoperfusion despite the fall in pressure. However, the time course and the extent of this effect vary according to the drug administered. In particular, only a calcium channel blocker increased perfusion of both cortical and subcortical areas, while diuretic treatment increased perfusion only after prolonged treatment, and this effect was limited to the cortical areas. Such differences may explain the discrepant results on risk reduction for dementia observed in large intervention trials.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Effect of insulin and angiotensin II on cell calcium in human skin fibroblasts.

We have recently shown that insulin attenuates angiotensin II-induced intracellular Ca(2+) mobilization in human skin fibroblasts from normotensive subjects. This study was designed to investigate the effects of angiotensin II and the interactions between insulin and angiotensin II on intracellular Ca(2+) mobilization in skin fibroblasts from patients with essential hypertension. Fibroblasts were obtained from 9 normotensives and 18 hypertensives. Spectrofluorophotometric free Ca(2+) measurement was performed in monolayers of 24-hour serum-deprived cells. Resting intracellular Ca(2+) level and angiotensin II-stimulated intracellular Ca(2+) peak were higher in fibroblasts from hypertensives compared with those from normotensives. The effect of acute insulin exposure was evaluated in fibroblasts from hypertensives subdivided on the basis of insulin sensitivity. In insulin-sensitive hypertensives, insulin significantly blunted the effects of angiotensin II on intracellular Ca(2+) response, whereas in insulin-resistant patients, insulin did not modify intracellular Ca(2+) response to angiotensin II. Pertussis toxin, a G(ialpha)-inhibitor, reduced angiotensin II-stimulated Ca(2+) peak in insulin-sensitive but not in insulin-resistant hypertensives. In conclusion, the effects of angiotensin II on intracellular Ca(2+) mobilization are more pronounced in fibroblasts from hypertensives compared with those from normotensives, and the inhibitory effect of insulin is blunted in insulin-resistant hypertensives by a G(ialpha) pertussis toxin-sensitive abnormality.

Adult↗
PubMed2001

Hyperglycemia acutely increases monocyte extracellular signal-regulated kinase activity in vivo in humans.

Glycemic spikes may negatively affect the long-term prognosis of patients with diabetes. Extracellular signal-regulated kinases (ERKs) are intracellular mediators of cell proliferation, and they can be activated in response to high glucose levels. However, the modifications of their activity in response to hyperglycemia have been poorly investigated, in vivo, in humans. Thus, we sought to determine in circulating monocytes: 1) the role of hyperglycemia in ERKs activity and phosphorylation, and 2) whether hyperglycemia affects mitogen-activated protein kinase kinase (MEK) activity and mitogen-activated protein phosphatase-1 (MKP-1) expression. These goals were performed in five normal subjects. Baseline monocyte ERKs activity was 60 +/- 5 pmol/min.mg protein; when exogenous hyperglycemia was induced, both monocyte ERKs activity (81 +/- 11 pmol/min.mg protein; P < 0.05) and phosphorylation significantly increased (P < 0.01). MEK activity was significantly increased by hyperglycemia (1251 +/- 136 vs. 2000 +/- 42 cpm; P = 0.0017), whereas no changes were observed in MKP-1 expression. We conclude that hyperglycemia acutely stimulates ERKs activity and phosphorylation in human monocytes by the MEK pathway in vivo. These findings may be relevant in understanding the negative role of acute hyperglycemia on monocyte pathophysiology.

Adult↗
PubMed2000

Idiopathic hypercalciuria: O2(-)NO relationship and altered bone metabolism.

The pathogenesis of idiopathic hypercalciuria (IH) has not been elucidated yet, but a correlation between IH and altered bone metabolism has been proposed. Since nitric oxide (NO) regulates osteoclasts' bone resorption, a possible role for NO can be suggested. In this study we evaluated iNOS gene expression by reverse transcription of mRNA from monocytes, followed by polymerase chain reaction in patients with IH subdivided into fasting (FH) and absorptive (AH) hypercalciuria. Since superoxide (O2-), which metabolizes NO, is overproduced by osteoclasts during bone resorption, peroxynitrite plasma level was evaluated as index of O2-. Vertebral BMD in IH as a whole group was lower vs controls (C) (Z score=-1.78+/-0.2 vs 0.51+/-0.25, p<0.001), but only FH patients showed a reduced bone density (2.13+/-0.18 vs 0.51+/-0.25, p<0.0001). PTH and calcitriol were not different. FH showed an increase in b-ALP vs AH and C (41.1+/-2.6 vs 30.1+/-3.9 vs 26.6+/-3.6 U/l p<0.02), and higher uHP, either on NCD (17.7+/-1.6 vs 11.4+/-1.3 mg/g uCr, p<0.04) or after LCD (26.7+/-2.5 vs 16.7+/-1.9, p<0.01). Cells from FH patients, but not from both AH patients and C, expressed iNOS. Peroxynitrite plasma level was elevated in FH (0.30+/-0.07) pmol/l while not detectable in AH and C. This study confirms an altered bone metabolism only in FH which shows an abnormal NO system. The increased iNOS gene expression in FH, in fact, points toward an altered NO system's activity downstream the generation of NO. A possible interaction of NO with O2-, which breaks down NO, and the role of this interaction in the pathophysiology of IH is discussed.

Adult↗
PubMed2000

Role of insulin-like growth factor-I in primary osteoporosis: a correlative study.

Osteoporosis is characterized by impairment of bone mass and deterioration of bone microscopic structure, resulting in increased bone fragility and susceptibility to fracture. Recent reports have indicated that reduced plasma levels of IGF-I are associated with osteoporosis in both males and females. Moreover, there is accumulating clinical evidence that treatment with GH or IGF-I has beneficial effects on bone mass and bone remodeling in men with idiopathic osteoporosis, in the elderly and in hypopituitary patients. As correlative studies on IGF-I, IGF-BP3 and bone mass in the elderly are lacking, we studied the relationships between serum IGF-I, IGF-BP3, bone mineral density (BMD), body mass index (BMI), calciotropic hormones and age in 102 premenopausal and postmenopausal women. Our study indicates that the reduction of the anabolic processes mediated by IGF-I may account for the slow and progressive loss of bone mass that take place after the age of 40-50 years. In addition, nutritional caloric or proteic deficit may add to the effects of GH, age and other factors in decreasing IGF-I synthesis and therefore further contribute to the development of primary osteoporosis.

Adult↗
PubMed2000

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

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 beta-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 microM in patients vs 11.53 +/- 5.64 microM 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 microM/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.

Adult↗
PubMed2000

Dietary manipulation of delta-6-desaturase modifies phospholipid arachidonic acid levels and the urinary excretion of calcium and oxalate in the rat: insight in calcium lithogenesis.

An anomalous n-6 polyunsaturated fatty acid composition in plasma and erythrocyte membrane phospholipids, namely increased levels of arachidonic acid (AA), has been reported in calcium nephrolithiasis and has been proposed to play an important role in its pathogenesis. To confirm this, in rats we modified phospholipid AA levels by dietary manipulation of the delta-6-desaturase, the rate-limiting enzyme of the fatty acid biosynthetic pathway, and evaluated the effect on cellular and renal functions predisposing to lithogenesis. Increased AA levels led to conditions at risk for nephrolithiasis: higher oxalate flux and lower sodium cotransport in erythrocytes and a rise in urinary prostaglandin E2, calcium, sodium, and oxalate levels; reduced AA levels reversed these changes. In vitro, in human erythrocytes the incorporation of exogenous AA into membranes increased band 3 protein phosphorylation directly activating the Ser/Thr protein kinase CK1 and induced a parallel raise in band 3-mediated oxalate transport. These findings demonstrate the pivotal role of phospholipid AA in modulating erythrocyte and renal transport of calcium and oxalate.

Animals↗