Integrated central blood pressure-aortic stiffness risk score for cardiovascular risk stratification in chronic kidney disease.

BACKGROUND AND AIMS: The aim of this study was to develop an integrated central blood pressure-aortic stiffness (ICPS) risk score to predict cardiovascular events. METHODS: It was a retrospective cohort study. A total of 100 chronic kidney disease (CKD) patients on conservative therapy were included. Pulse wave velocity (PWV), central systolic blood pressure (cSBP), and central pulse pressure (cPP) were measured. A score was assigned to tertiles of PWV (0-2), cPP (0-2), and cSBP (0 to the first and second and 1 to the third tertile) based on each parameter's ability to individually predict cardiovascular outcome. The sum of these scores and three ICPS risk categories as predictors were studied. Finally, we compared discrimination of the ICPS risk categories with PWV, cSBP, and cPP. RESULTS: Adjusted for age and sex, patients in high and very high ICPS risk categories had increased cardiovascular risk (HR: 3.52, 95% CI: 1.65-7.49; HR: 7.56, 95% CI: 3.20-17.85, respectively). High and very high ICPS risk categories remained independent predictors in a model adjusted for multiple CV risk factors (HR: 4.58, 95% CI: 1.65-7.49; HR: 8.56, 95% CI: 3.09-23.76, respectively). ICPS risk categories (Harrell's C: 0.723, 95% CI: 0.652-0.795) showed better discrimination than PWV (Harrell's C: 0.659, 95% CI: 0.586-0.732, p = 0.028) and cSBP (Harrell's C: 0.660, 95% CI: 0.584-0.735, p = 0.008) and there has been a tendency of significance in case of cPP (Harrell's C: 0.691, 95% CI: 0.621-0.761, p = 0.170). CONCLUSION: The ICPS score may clinically importantly improve the identification of CKD patients with elevated cardiovascular risk.

The significance of micro- and macrovascular biomarkers on cardiovascular outcome in chronic kidney disease: a prospective cohort study.

Measures of small and large artery dysfunction have not been investigated in a single cohort for the prediction of cardiovascular (CV) events in patients with nondialysed (ND) chronic kidney disease (CKD). This prospective cohort study aimed to determine whether central pulse wave velocity (cPWV), central pulse pressure (CPP) or microvascular post-occlusive reactive hyperaemia area (PORHHA) independently predict CV events and mortality in CKD-ND. A total of 94 stage 1-5 CKD-ND (65.3±13.1 years; estimated glomerular filtration rate 35.3 (22.8-49.4) ml min(-1) per 1.73 m(2)) patients were followed-up for a median of 52 (36-65) months and had baseline cPWV and CPP measured by applanation tonometry and PORHHA by laser Doppler flowmetry. Multiple failure time Cox regression models were used to determine the predictive role of vascular parameters on CV mortality and events. Based on multiple linear regressions, baseline age, diabetes, CV disease, and systolic blood pressure (SBP) were independently related to cPWV (R(2)=0.3), SBP and PORHHA to CPP (R(2)=0.45), whereas CPP was the only parameter independently related to PORHHA (R(2)=0.16, all P<0.05). During follow-up, 41 CV events occurred (14 CV deaths). In univariate analyses, cPWV (1.07 (1.02-1.13) per m s(-1)), CPP (1.04 (1.01-1.07) per mm Hg) and lnPORHHA (0.70 (0.58-0.85) per ln(PU × s)) were all related to the outcome. Baseline diabetes (HR 3.07 (1.65-5.68)), lnFGF23 (fibroblast growth factor-23; 1.86 (1.13-3.06) per RU ml(-1)) and CPP (1.04 (1.01-1.07) per mm Hg) were independent predictors of CV events. The impaired pulsatile component of large arteries (CPP) independently of other vascular markers (cPWV, PORHHA) predicted CV outcomes in CKD-ND. CPP may integrate the information provided by cPWV and PORHHA.

Laser-Doppler examination of corona phlebectatica paraplantaris.

AIM: Corona phlebectatica paraplantaris (CPP) is a typical sign of chronic venous insufficiency (CVI). The aim of our study was to obtain information about the basic microcirculation and microvascular reactivity in CPP. METHODS: Microcirculation of the skin was investigated on the surface of CPPs and as a control in a nearby vessel-free skin region of the foot. The resting flow was recorded in a supine position, then different provocation tests were performed such as local heating (44 ˚C, 2 min), postocclusive reactive hyperemia (PORH, 220 mmHg, 3 min) and venoarterial response (VAR). RESULTS: There were significant differences between the circulation of CPPs and control skin: resting flux and amplitude values were higher in CPPs. Spectral analysis showed higher endothelial, sympathetic, myogenic, breathing and heart activities in CPPs. At the beginning of the PORH test, compression of the leg increased the flow in CPPs. Other PORH parameters, the response to local heating and VAR were not different in the two areas studied. CONCLUSION: High resting flux values and large amplitudes in CPPs suggest more the presence of open AV shunts in the ankle region than the role of calibre differences. Pathological responses to different provocation tests can be a consequence of the CVI.

Alteration of serum semicarbazide-sensitive amine oxidase activity in chronic renal failure.

Despite recent intensive investigations, physiological and pathological role of semicarbazide-sensitive amine oxidase (SSAO) is far from clear. In this study, serum SSAO activity was determined, radiochemically, in various groups of uremic patients: haemodialysed (HD), peritoneally dialysed (PD) and those receiving conservative treatment but still not dialysed (ND), as well as in controls. Reduced enzyme activity was found in HD uremic patients before and after dialysis treatment, compared to controls (5260 +/- 862 and 6011 +/- 958 pmol/h/ml vs. 8601 +/- 283 pmol/h/ml, p < 0.01 and p < 0.05, respectively). The activity was slightly lower in PD, and normal in ND patients. In HD patients SSAO activity was also determined by an assay based on the formation of hydrogen peroxide, and was found to be elevated compared to controls (2384 +/- 323 pmol/h/ml vs. 1437 +/- 72 pmol/h/ml, p < 0.05). The elevated serum SSAO activity measured through the detection of the enzyme-generated hydrogen peroxide in HD patients might indicate its contribution to the accelerated atherosclerotic disease observed in uremia.

Endogenous bacteria-triggered inducible nitric oxide synthase activation protects the ovariectomized rat stomach.

Under experimental circumstances, ovariectomy attenuates gastric mucosal injury where nitric oxide (NO)-mediated pathways are involved. In this study, we have examined the changes in constitutive (cNOS) and inducible NO synthase (iNOS) enzyme activities (assessed by the citrulline assay), and the role of endogenous bacteria in ovariectomy-provoked mucosal defence. Gastric lesions were induced by indomethacin (50 mg/kg, s.c.) over a 4 h period in sham-operated and ovariectomized female Wistar rats. Groups of animals received the wide-spectrum antibiotic ampicillin (800 mg/kg/day, p.o., for 3 days), and others were injected with bacterial endotoxin (E. coli, 3 mg/kg, i.v., 5 h before autopsy). We found that ovariectomy increased iNOS and decreased cNOS activity (resulting an elevated total gastric NOS level), and protected the stomach, effects reversed by ampicillin treatment. In ovary-intact rats, administration of bacterial endotoxin enhanced gastric iNOS activity and reduced lesion-formation. These results suggest that ovariectomy improves gastric mucosal defence perhaps by endogenous bacteria-triggered induction of iNOS.

Attenuation of Helicobacter pylori endotoxin-provoked rat intestinal inflammation by selective inhibition of the inducible nitric oxide synthase.

We studied the actions of purified Helicobacter pylori endotoxin (3 mg kg(-1), i.v.) on rat intestinal vascular permeability (assessed by the radiolabelled human serum albumin leakage technique) and on nitric oxide synthase induction (assessed by the citrulline assay) 4 h later. We found increased albumin leakage and expression of the inducible nitric oxide synthase in jejunum and colon, effects reversed by a selective inducible nitric oxide synthase inhibitor N-(8-(aminomethyl)benzyl)-acetamidine (1400W; 0.2-1 mg kg(-1), s.c., concurrently with endotoxin). Thus, H. pylori endotoxin seems to be capable of provoking an inflammatory response in the rat intestinal tissue. Systemic liberation of H. pylori endotoxin might possibly attenuate jejunal and colonic mucosal barrier function, a process mediated by the expression of the inducible nitric oxide synthase.

Estrogen-mediated up-regulation of the Ca-dependent constitutive nitric oxide synthase in the rat aorta and heart.

The role of endogenous estrogens has been studied in the regulation of the Ca-dependent constitutive nitric oxide synthase (cNOS) enzyme activity in aortic and cardiac tissues of the rat. The activity of cNOS enzyme was measured by the citrulline assay in the abdominal aorta and in the left ventricle of the heart obtained from male, sham-operated female and ovariectomized female Wistar rats. Estrogen replacement therapy (17-beta-estradiol, 20-100 microg/kg/day, s.c.) has been performed in ovariectomized rats over two weeks. We found that cNOS activity was higher in the aorta and heart of female rats compared to males. Ovariectomy decreased cNOS activity in both tissues to that level what could be observed in males. Estrogen supplementation caused a dose-dependent elevation of cNOS enzyme activity in cardiac and aortic tissues, where the higher dose (100 microg) completely restored cNOS enzyme activity to the levels found in females. We concluded that endogenous estrogens up-regulate the activity of the cNOS isoenzymes in the rat aorta and heart.

Interactions of pro-inflammatory and vasoactive mediators with nitric oxide in the regulation of rat vascular permeability during laparotomy.

Inhibition of constitutive nitric oxide (NO) synthases by administration of N(G)-nitro-L-arginine methyl ester (L-NAME) during abdominal laparotomy provokes extensive vascular leakage in the rat gastrointestinal tract, assessed by the extravasation of [125I]human serum albumin. In the present study, the role of vasoactive or neutrophil-derived pro-inflammatory mediators in this process has been investigated. Administration of the thromboxane synthase inhibitor, 1-benzyl-imidazole (BZI, 25-50 mg kg(-1), s.c.), the platelet-activating factor (PAF) receptor antagonist, 3-[4-(2-chlorophenyl)-9-methyl-6H-thienol-[3,2-f][1,2,4]-triazolo- [4, 3-a][1,4]-diazepine-2-yl]-1-(4-morpholynil)-1-propionate (WEB 2086; 0.5-1 mg kg(-1), s.c.), the 5-lipoxygenase synthase inhibitor, N-(4-benzyloxybenzyl)-acetohydroxamic acid (BW A137C; 4-20 mg kg(-1), s.c.) or the vasopressin pressor receptor antagonist ([Mca(1), Tyr(Me)(2),Arg(8)]vasopressin/Manning peptide; 0.01-0.2 microg kg(-1), s.c.) dose-dependently reduced the intestinal plasma leakage provoked by L-NAME (5 mg kg(-1), s.c.), following a 5-cm abdominal laparotomy in anaesthetised rats. These findings suggest that constitutive NO synthase effectively counteracts the damaging actions on microvascular integrity of mediators, including thromboxanes, PAF, leukotrienes and vasopressin, released during surgical intervention.

Raloxifene, an oestrogen-receptor modulator, prevents decreased constitutive nitric oxide and vasoconstriction in ovariectomized rats.

Administration of graded doses of [Arg(8)]vasopressin (0.06-0.18 microg kg(-1), i.v.) induced a dose-dependent increase in arterial blood pressure in the catecholamine-depleted (phentolamine; 10 mg kg(-1), i.p.) intact and ovariectomized female rat, with the elevation of blood pressure more marked following ovariectomy. In addition, ovariectomy caused the down-regulation of aortic Ca(2+)-dependent constitutive nitric oxide synthase (assessed by the citrulline assay). The down-regulation of the Ca(2+)-dependent constitutive nitric oxide synthase and augmentation of vasopressin-induced blood pressure responses were prevented by the therapy (1 month, p.o.) with the selective oestrogen receptor modulator, raloxifene (0.3-1.0 mg kg(-1) day(-1)), or with 17beta-oestradiol (0.3 mg kg(-1) day(-1)) in ovariectomized rats. Thus, oestrogen deficiency down-regulates vascular constitutive nitric oxide synthase, which appears to be involved in the increased sensitivity of the vasculature to vasopressin, since both effects can be reversed by the exogenous administration of the natural oestrogen 17beta-oestradiol or the selective oestrogen-receptor modulator raloxifene.