Microalbuminuria and oxidative stress in essential hypertension

Microalbuminuria as a potential biomarker for Parkinson's disease severity: A hypothesis

Parkinson's disease (PD) is the second most common neurodegenerative condition characterized by motor and non-motor symptoms causing a great burden in patients' quality of life. PD has been associated with various metabolic factors such as diabetes, hypertension, and more recently chronic kidney disease where proteinuria has been associated with an increased risk. The presence of small amounts of albumin in urine, microalbuminuria, is a common biomarker for endothelial damage and a predictive factor for not only cardiovascular but also neurological dysfunction. Multiple studies have assessed potential biomarkers for PD progression with great heterogeneity, we hypothesize the use of microalbuminuria as a potential marker that correlates with PD severity and might represent a feasible and simple method of evaluating PD patients in clinical practice. Evidence supporting the present hypothesis comes from oxidative stress, insulin resistance, and endothelial dysfunction. Oxidative stress is a key element in PD pathogenesis; studies have shown lower antioxidant capacity as PD progresses. On the other side, insulin signaling plays an important role in neuronal growth and survival, with its resistance being associated with PD. Microalbuminuria has been associated with both processes; increased levels of oxidative stress markers and decreased insulin sensitivity, hence its screening in PD might reflect these common pathological mechanisms. Moreover, the low vitamin D levels observed in PD patients, which are correlated with endothelial dysfunction and disease severity, might contribute to microalbuminuria induction. More evidence on this vascular approach comes from white matter lesions (WML), observed in brain imaging, which have been significantly associated with motor and non-motor function in PD patients and are independently associated with microalbuminuria. In this manner, an oxidant and insulin resistant environment, along with low vitamin D levels in PD patients, which are associated with microalbuminuria, might contribute altogether to WML. As the latter are correlated with motor and non-motor function, microalbuminuria might thus give insight on PD status. Prospective cohort studies with an adequate sample size, follow-up, and a thorough battery of clinical tests for PD are needed to confirm this hypothesis.

Oxidative Stress and the Kidney in the Space Environment

In space, the special conditions of hypogravity and exposure to cosmic radiation have substantial differences compared to terrestrial circumstances, and a multidimensional impact on the human body and human organ functions. Cosmic radiation provokes cellular and gene damage, and the generation of reactive oxygen species (ROS), leading to a dysregulation in the oxidants–antioxidants balance, and to the inflammatory response. Other practical factors contributing to these dysregulations in space environment include increased bone resorption, impaired anabolic response, and even difficulties in detecting oxidative stress in blood and urine samples. Enhanced oxidative stress affects mitochondrial and endothelial functions, contributes to reduced natriuresis and the development of hypertension, and may play an additive role in the formation of kidney stones. Finally, the composition of urine protein excretion is significantly altered, depicting possible tubular dysfunction.

Genomic and metabolomic profile associated to microalbuminuria

To identify factors related with the risk to develop microalbuminuria using combined genomic and metabolomic values from a general population study. One thousand five hundred and two subjects, Caucasian, more than 18 years, representative of the general population, were included. Blood pressure measurement and albumin/creatinine ratio were measured in a urine sample. Using SNPlex, 1251 SNPs potentially associated to urinary albumin excretion (UAE) were analyzed. Serum metabolomic profile was assessed by 1H NMR spectra using a Brucker Advance DRX 600 spectrometer. From the total population, 1217 (mean age 54 ± 19, 50.6% men, ACR>30 mg/g in 81 subjects) with high genotyping call rate were analysed. A characteristic metabolomic profile, which included products from mitochondrial and extra mitochondrial metabolism as well as branched amino acids and their derivative signals, were observed in microalbuminuric as compare to normoalbuminuric subjects. The comparison of the metabolomic profile between subjects with different UAE status for each of the genotypes associated to microalbuminuria revealed two SNPs, the rs10492025_TT of RPH3A gene and the rs4359_CC of ACE gene, with minimal or no statistically significant differences. Subjects with and without microalbuminuria, who shared the same genotype and metabolomic profile, differed in age. Microalbuminurics with the CC genotype of the rs4359 polymorphism and with the TT genotype of the rs10492025 polymorphism were seven years older and seventeen years younger, respectively as compared to the whole microalbuminuric subjects. With the same metabolomic environment, characteristic of subjects with microalbuminuria, the TT genotype of the rs10492025 polymorphism seems to increase and the CC genotype of the rs4359 polymorphism seems to reduce risk to develop microalbuminuria.

Association of serum carotenoid levels with urinary albumin excretion in a general Japanese population: the Yakumo study

Background

Albuminuria is a risk factor for not only nephropathy progression but also cardiovascular disease. Oxidative stress may have a role in the positive association between albuminuria and cardiovascular disease.

Methods

This cross-sectional study investigated the associations of serum levels of carotenoids, which are dietary antioxidants, with albuminuria among 501 Japanese adults (198 men, mean age ± SD: 66.4 ± 10.0 years; 303 women, mean age ± SD: 65.4 ± 9.8 years) who attended a health examination. Serum levels of carotenoids were determined by high-performance liquid chromatography. Logistic regression analysis was used to estimate odds ratios (ORs) with 95% CIs for albuminuria after adjustment for age, body mass index, smoking habits, drinking habits, hypertension, diabetes mellitus, and dyslipidemia.

Results

Prevalence of albuminuria was 15.4% among men and 18.1% among women. Among women with albuminuria, geometric mean serum levels of canthaxanthin, lycopene, β-carotene, total carotenes, and provitamin A were significantly lower than those of normoalbuminuric women. Adjusted ORs for albuminuria among women in the highest tertiles of serum β-carotene (OR, 0.45; 95% CI, 0.20–0.98) and provitamin A (OR, 0.45; 95% CI, 0.20–0.97) were significantly lower as compared with those for women in the lowest tertile. There were no associations between serum carotenoids and albuminuria in men.

Conclusions

An increased level of serum provitamin A, especially serum β-carotene, was independently associated with lower risk of albuminuria among Japanese women.

Pharmacologic management of chronic reno-cardiac syndrome

Chronic kidney disease (CKD) significantly increases cardiovascular morbidity and mortality. CKD remains an under-represented population in cardiovascular clinical trials, and cardiovascular disease is an under-treated entity in CKD. Traditional cardiovascular risk factors in conjunction with uremia-related complications often progress to myocardial dysfunction. Such uremic cardiomyopathy leads to over-activation of neurohormonal pathways with detrimental effects. Management of the reno-cardiac syndrome (RCS) requires the targeting of these multiple facets. In this article we discuss the relevant pathophysiology of RCS, and present the clinical data related to its management.

The effect of antihypertensive drugs on chronic kidney disease: a comprehensive review

Data from randomized clinical trials and epidemiological evidence identify systemic hypertension as the second most common modifiable risk factor for chronic kidney disease (CKD) progression after diabetes mellitus. CKD may progress silently over the years and early diagnosis and control of hypertension is of major importance in delaying renal function decline. Recent guidelines for the treatment of hypertension suggest the use of a variety of antihypertensive drugs in order to achieve the desired blood pressure levels. Renin-angiotensin system inhibitors have been undoubtedly studied the most and are suggested by guidelines and experts as first choice in patients with hypertension and renal injury, particularly in those with diabetes, as they have repeatedly shown to significantly reduce proteinuria. Other classes of antihypertensive drugs have been studied to a lesser extent and they have their own unique properties and effects. However, it is now common knowledge that adequate blood pressure control is the most important factor for the preservation of renal function, so every drug that effectively lowers hypertension is believed to be renoprotective. The present article will review the latest data on the role and properties of each class of antihypertensive drugs on CKD.

The association of oxidative stress with hypertensive retinopathy

This study was designed to answer the following questions: (i) Do levels of serum gamma-glutamyl transferase (GGT), a marker of oxidative stress, change in hypertensive retinopathy (HR)? (ii) Is there any relation between degree of HR and GGT levels? This study included 80 hypertensive patients with HR. Group 1 comprised 40 patients with grade I HR, and group 2 comprised 40 patients with grade II HR. We selected 40 healthy subjects for the control group. Level of GGT in group 2 was significantly higher than in group 1 (P = 0.005) and control group (P = 0.001); it was also higher in group 1 than in control group (P = 0.025). Our study suggests that oxidative stress, mechanisms known to be involved in vascular lesions, may promote the development of HR.

Urinary albumin excretion during angiotensin II receptor blockade: comparison of combination treatment with a diuretic or a calcium-channel blocker

BACKGROUND

We aimed to test the hypothesis that the angiotensin II receptor blocker (ARB)/diuretic combination decreases the urinary albumin/creatinine ratio (UACR) to a greater extent than treatment with the ARB/calcium-channel blocker (CCB) combination through a mechanism related to a greater reduction of sleep blood pressure (BP).

METHODS

We conducted a prospective, randomized, open-label, blinded end-point trial in hypertensive patients. Patients received olmesartan monotherapy for 12 weeks, followed by an additional use of hydrochlorothiazide (HCTZ) (n = 104) or azelnidipine (n = 103) for 24 weeks after randomization. The measurements of central and ambulatory BP, and laboratory tests were performed at baseline and the end of the study.

RESULTS

The adjusted percent reduction in UACR in the olmesartan/HCTZ group was significantly greater than that in the olmesartan/azelnidipine group (-43.2 vs. -24.0%, P = 0.0014), although the olmesartan/azelnidipine group showed greater decreases in central systolic BP (SBP; P = 0.04), oxidative stress (urinary 8-isoprostane; P = 0.02), inflammation (high-sensitivity C-reactive protein; P = 0.04), and insulin resistance (the homeostasis model assessment insulin resistance index (HOMA(IR)); P < 0.001) than the olmesartan/HCTZ group. In multivariate regression analyses, the significant determinants of change in UACR in the olmesartan/HCTZ group were changes in sleep SBP (P < 0.001), central SBP (P = 0.01), estimated glomerular filtration rate (eGFR) (P = 0.02), and HOMA(IR) (P = 0.03), and those in the olmesartan/azelnidipine group were changes in central SBP (P = 0.001) and urinary 8-isoprostane (P = 0.02).

CONCLUSIONS

These data showed that the ARB/diuretic combination decreased UACR significantly more than the ARB/CCB combination, and this decrease in UACR was associated with a greater magnitude reduction in sleep SBP.

Polymorphisms of antioxidant enzymes, blood pressure and risk of hypertension

OBJECTIVE

To assess the association of single-nucleotide polymorphisms (SNPs) in genes codifying for antioxidant enzymes to blood pressure (BP) values and risk of hypertension.

METHODS

Population-based study including 1388 participants (704 women) older than 18 years in which 300 were untreated hypertensive patients. In 335 untreated hypertensive patients referred to one hypertension clinic, the study was replicated. Thirty-five SNP throughout 13 genes were analyzed using SNPlex. In a subgroup of hypertensive patients, the amount of 8-oxo-deoxyguanosine and GPX activity levels was measured in mononuclear cells.

RESULTS

In the general population, genotypes with the G allele of the c.172G>A polymorphism in the SOD3 gene and those with the T allele of the c.-20C>T polymorphism in the CAT gene were associated with significant lower values of BP. Likewise, these genotypes were associated with less risk for hypertension after adjusting for confounder variables. Haplotypes in both genes increased the strength of associations. In the hypertensive patients, the same alleles of the two polymorphisms were associated with lower BP values too. In addition, two others, the CT-TT genotypes of the c.891C>T polymorphism in the GPX1 gene and the CT-CC genotypes of the c.-793T>C polymorphism of the TXN gene were also significantly associated to lower BP values. Furthermore, the CC genotype of the c.891C>T polymorphism in the GPX1 gene was associated with higher values of 8-oxo-dG and GPX activity levels as compared to those for the CT-TT genotype.

CONCLUSIONS

The results of the present study support the influence of antioxidant enzyme genes in BP values and hypertension risk.

Reduction in basal nitric oxide activity causes albuminuria

OBJECTIVE

The barrier function of the glomerular filter has been studied for decades. Albuminuria reflects a malfunction of this barrier, and in animals dysfunctional endothelial nitric-oxide (NO) synthase results in albuminuria. We aimed to analyze the importance of NO for the glomerular barrier function in humans.

RESEARCH DESIGN AND METHODS

To assess the effect of endothelial dysfunction on albuminuria, we measured the urine albumin-to-creatinine ratio (UACR) both before and after the blockade of NO synthases (NOSs) with systemic infusion of N(G)-monomethyl-L-arginine (L-NMMA) in two distinct study populations. In population A, 62 hypertensive patients with type 2 diabetes and, in population B, 22 patients with hypercholesterolemia but without hypertension or type 2 diabetes were examined. All subjects had normal renal function.

RESULTS

There was a significant increase in the UACR in response to NOS inhibition with L-NMMA in hypertensive patients with type 2 diabetes (study population A) and in patients with hypercholesterolemia (study population B). Linear regression analyses revealed that the change in mean arterial presssure in response to L-NMMA was not related to the increase in the UACR in response to L-NMMA in either population, even after adjusting for filtration fraction.

CONCLUSIONS

NOS inhibition provokes albuminuria that is unrelated to changes in blood pressure. It is noteworthy that this finding was evident in patient groups prone to endothelial dysfunction and albuminuria. Thus, acute deterioration of endothelial function by reducing NO activity causes an increase in albuminuria.

Gestational diabetes mellitus alone in the absence of subsequent diabetes is associated with microalbuminuria: results from the Kidney Early Evaluation Program (KEEP)

OBJECTIVE

Women with gestational diabetes mellitus (GDM) maintain a higher risk for recurrent GDM and overt diabetes. Overt diabetes is a risk factor for development of chronic kidney disease (CKD), but GDM alone, without subsequent development of overt diabetes, may also pose a risk for CKD.

RESEARCH DESIGN AND METHODS

This cross-sectional analysis included Kidney Early Evaluation Program (KEEP) participants from 2000 to 2009. Patient characteristics and kidney function among three categories (GDM alone, overt diabetes, and no history of diabetes) were compared. The prevalence of microalbuminuria, macroalbuminuria, and CKD stages 1-2 and 3-5 was assessed using logistic regression.

RESULTS

Of 37,716 KEEP female participants, 571 (1.5%) had GDM alone and 12,100 (32.1%) had overt diabetes. Women with GDM had a higher rate of microalbuminuria but not macroalbuminuria than their nondiabetic peers (10.0 vs. 7.7%) that was substantially lower than the 13.6% prevalence in diabetic women. In multivariate analysis, women with GDM alone, compared with nondiabetic women, demonstrated increased odds of CKD stages 1-2 (multivariate odds ratio 1.54 [95% CI 1.16-2.05]) similar to the odds for women with overt diabetes (1.68 [1.55-1.82]). In stratified analyses, age, race, BMI, and hypertension modified the odds for CKD stages 1-2 but not CKD stages 3-5 among women with GDM.

CONCLUSIONS

Women with GDM alone have a higher prevalence of microalbuminuria than women without any history of diabetes, translating to higher rates of CKD stages 1-2. These results suggest that GDM, even in the absence of subsequent overt diabetes, may increase the risk for future cardiovascular and kidney disease.

Differential effects of carvedilol and metoprolol on renal function in patients with heart failure

BACKGROUND

The aim of the present study was to verify the effects of beta-blockers on renal function in patients with heart failure (HF).

METHODS AND RESULTS

A total of 40 patients with HF (New York Heart Association class, II-III) were enrolled, who had beta-blocker therapy initiated with carvedilol (n=23) or metoprolol (n=17). The changes in renal and cardiac function were retrospectively analyzed over 16 weeks. The study population was divided into 2 groups according to the median baseline (65.9 ml/min) of estimated glomerular filtration rate (eGFR) calculated by the Modification of Diet in Renal Disease formula. eGFR significantly decreased in the higher eGFR group (P=0.04), but did not in the lower eGFR group. Left ventricular ejection fraction significantly increased in both groups with lower eGFR (P=0.01) and higher eGFR (P<0.01). There was an interaction between plasma norepinephrine concentration and eGFR in terms of beta-blocker treatment (P=0.02, ANOVA). eGFR significantly decreased in patients who received metoprolol (from 75.7+/-33.5 to 59.5+/-20.0 mlxmin(-1).1.73 m(-2), P<0.01), but did not change in those who received carvedilol (from 67.1+/-27.7 mlxmin(-1).1.73 m(-2) to 65.6+/-23.2 mlxmin(-1).1.73 m(-2)).

CONCLUSIONS

Beta-blockers preserved renal function in HF patients with lower baseline eGFR, but not in those with higher baseline eGFR. Carvedilol may be preferable to metoprolol to prevent the development of chronic kidney disease during beta-blocker therapy for HF.

Urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG), a reliable oxidative stress marker in hypertension

The potential use of oxidative stress products as disease markers and progression is an important aspect of biomedical research. In the present study, the quantification of urine 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) concentration has been used to express the oxidation status of hypertensive subjects. 8-oxo-dG has been simultaneously isolated and assayed in nuclear (nDNA) and mitochondrial DNA (mtDNA). In addition, oxidative stress of mononuclear cells has been estimated by means of GSH and GSSG levels and GSSG/GSH ratio in hypertensive subjects before and after antihypertensive treatment. It is shown that oxidative stress decreases significantly in hypertensive patients after treatment the effect being accompanied by reduction of their blood pressure. A significant correlation is observed comparing the yield of urine 8-oxo-dG and that isolated from mitochondria DNA. Moreover, urinary excretion of 8-oxo-dG also correlates with the GSSG/GSH ratio of cells.

CONCLUSION

urine 8-oxo-dG assay is a good marker for monitoring oxidative stress changes in hypertensives.

The kidney, hypertension, and remaining challenges

There is an epidemic of chronic kidney disease in the Western world, with hypertension being the second most common cause. Blood pressure control rates, while improving, are still below 50% for the United States population. The following three challenges remain for the treatment of hypertension and associated prevention of end-stage kidney disease. First, a better understanding by the general medical community of how and in whom to use renin angiotensin aldosterone system blockers is needed. Second, the appropriate initiation of fixed-dose combination therapy to achieve blood-pressure goals needs to be clarified. Finally, the subgroup of patients with kidney disease needs more aggressive blood pressure lowering.

Determinants of platelet activation in hypertensives with microalbuminuria

Microalbuminuria is a predictor of adverse outcome in hypertension.We evaluated in vivo platelet activation, by urinary 11-dehydrothromboxane (TX)B2 and plasma P-selectin, in hypertensives with or without microalbuminuria, and its possible association with oxidative stress, by urinary 8-iso-prostaglandin (PG)F2alpha and endothelial dysfunction. Sixty essential hypertensive patients, with (n=30) or without (n=30) microalbuminuria, and 30 controls were studied. Endothelial function was assessed by nitric oxide products, intercellular adhesion molecule (ICAM)-1, and asymmetric dimethylarginine (ADMA) levels. Urinary 11-dehydro-TXB2 excretion was higher in microalbuminuric (median 805 pg/mg creatinine) compared to nonmicroalbuminuric patients or controls (414 and 291 pg/mg, respectively; P<0.0001). Plasma P-selectinwas significantly higher in patients with microalbuminuria (median 136 ng/ml) as compared to those without microalbuminuria or controls (85 and 65 ng/ml; P<0.0001). Urinary 8-iso-PGF2alpha excretion was also enhanced in microalbuminuric (median 279 pg/mg creatinine) compared to nonmicroalbuminuric patients or controls (157 and 146 pg/mg, respectively; P<0.0001). A significant impairment in endothelial function was found in microalbuminuric patients, with decreased nitric oxide and increased ICAM-1 and ADMA levels. Multivariate regression analysis showed that urinary 8-iso-PGF2alpha excretion (beta=0.49; P<0.0001) and microalbuminuria (beta=0.36; P<0.001) were independently related to 11-dehydro-TXB2 in hypertensives. Vitamin E supplementation (900 mg daily for 1 month) in 10 hypertensives with microalbuminuria was associated with normalization in median 11-dehydro-TXB2 and 8-iso-PGF2alpha. We conclude that lipid peroxidation is a major determinant of persistent platelet activation in hypertensive patients with microalbuminuria.

White blood cells telomere length is shorter in males with type 2 diabetes and microalbuminuria

OBJECTIVE

To examine differences in telomere (terminal restriction fragment [TRF]) length and pulse wave velocity (PWV)--an index of arterial stiffness--in patients with type 2 diabetes with and without microalbuminuria (MA).

RESEARCH DESIGN AND METHODS

A total of 84 men with type 2 diabetes, 40 with MA and 44 without MA (aged 63.5 +/- 9.0 vs. 61.2 +/- 9.8 years), were studied. TRF length was determined in white blood cells. MA was defined as albumin excretion rate (AER) in the range of 30-300 mg/24 h in at least two of three 24-h urine collections. PWV was assessed using applanation tonometry. Markers of oxidative stress were also measured.

RESULTS

TRF length was shorter in patients with MA than in those without MA (6.64 +/- 0.74 vs. 7.23 +/- 1.01 kb, respectively, P = 0.004). PWV was significantly higher in the patients with MA. Multivariate linear regression analysis in the total sample demonstrated an independent association between TRF length and age (P = 0.02), MA status (P = 0.04) or AER (P = 0.002), and plasma nitrotyrosine levels (P = 0.02). AER was associated significantly with PWV (P < 0.01).

CONCLUSIONS

Subjects with type 2 diabetes and MA have shorter TRF length and increased arterial stiffness than those without MA. Additionally, TRF length is associated with age, AER, and nitrosative stress. As shorter TRF length indicates older biological age, the increased arterial stiffness in patients with type 2 diabetes who have MA may be due to the more pronounced "aging " of these subjects.

Should β-Blockers Be Used to Control Hypertension in People With Chronic Kidney Disease?

Activation of the sympathetic nervous system is common in patients with chronic kidney disease, plays an important role in the genesis of hypertension, the rate of decrease of renal function, and is associated with the increased cardiovascular morbidity and mortality seen in these patients. beta-blockers are potent antihypertensive agents but differ in their hemodynamic effects on renal function. The cardioselective beta-blockers such as atenolol and metoprolol are known to retard the progression of renal diseases, but to a lesser degree compared with blockers of the renin-angiotensin-aldosterone system. However, the newer vasodilating beta-blockers such as carvedilol and nebivolol have different effects on renal hemodynamics and function primarily because of its greater adjunctive alpha1-blocking activity. Carvedilol decreases renal vascular resistance and prevents reductions in the glomerular filtration rate and renal blood flow in patients with hypertension with or without impaired kidney function. In addition, carvedilol may retard progression of albuminuria, and provide cardiorenal protection in chronic kidney disease patients with hypertension, congestive heart failure, and at high risk for sudden cardiac death.

Antioxidant activity of carvedilol in cardiovascular disease

Oxidative and inflammatory stresses are cardinal in the pathogenesis of hypertension and atherosclerosis. Oxidative stress also leads to the induction of inflammation through the activation of proinflammatory transcription factors. Understanding the mechanisms leading to oxidative stress and the means of suppressing it are important in controlling complications related to atherogenesis, since oxidative and inflammatory stress are important in the pathogenesis of atherosclerosis. The failure of chemical antioxidants [which scavenge reactive oxygen species (ROS)], such as vitamins E and C, has led to further exploration of the ROS-suppressive effects of drugs used in the treatment of cardiovascular disease. Carvedilol has been shown to possess both ROS-scavenging and ROS-suppressive effects, and its use is associated with a reduction in oxidative stress. Furthermore, anti-inflammatory effects of carvedilol have now been described. Although further clinical investigations are required, these properties may contribute to the improvement in clinical outcomes observed with carvedilol.

Beta blockers in the management of chronic kidney disease

The sympathetic nervous system modulates renal function through its receptors namely beta1 (cardiac output and renin release), alpha1 (systemic and renovascular constriction), and beta2 renovascular dilation. Sympathetic overactivity is commonly seen in chronic kidney disease (CKD) and is an important contributor to increasing the risk of cardiovascular events as well as increasing renal disease progression. Recent evaluations of drug use in people with CKD shows a remarkably low percentage of patients receiving beta-blockers, especially in more advanced stage CKD when cardiovascular risk is higher. This is in large part due to tolerability of these agents. Moreover, water-soluble beta-blockers such as atenolol and metoprolol are dialyzable and require supplementation to avoid exacerbation of arrhythmias following dialysis. Newer vasodilating beta-blockers have better tolerability and different effects on renal hemodynamics as well as metabolic variables. These effects are related to the relative alpha1-blocking effect of agents such as carvedilol and labetolol, with carvedilol having relatively greater alpha-blocking effects. Few studies evaluate beta-blockers on cardiovascular risk in CKD patients. Studies with carvedilol demonstrate attenuated increases in albuminuria as well as reduction in cardiovascular events in CKD patients with hypertension. This paper reviews the animal and clinical trial data that evaluate beta-blockers in CKD highlighting the vasodilating beta-blockers. It is apparent that greater use of this drug class for blood pressure control would further enhance reduction of risk of heart failure, the most common cause of death in the first year of starting dialysis.

Impact of the components of metabolic syndrome on oxidative stress and enzymatic antioxidant activity in essential hypertension

The objective of the present study was to analyze the impact of metabolic syndrome (MS) and its individual components on oxidative stress (OX) and on the activity of antioxidant enzymes of patients with essential hypertension. One hundred and eighty-seven hypertensives, 127 (61.9%) of them having criteria for MS according to the International Diabetes Federation criteria and 30 healthy normotensive subjects were included. OX status was assessed by measuring glutathione oxidized/glutathione reduced and reactive oxygen species-induced byproducts of lipid peroxidation, malondialdehyde, and DNA damage, 8-oxo-dG genomic and mitochondrial. Antioxidant enzymatic activity of Cu/Zn extracellular-superoxide dismutase (SOD) and catalase (CAT) was measured in plasma and glutathione peroxidase 1 in hemolysed erythrocytes. In mononuclear cells, total-SOD activity, CAT and glutathione peroxidase 1, were assessed as well. The OX state in both blood and peripheral mononuclear cells observed in hypertensives were not enhanced by the addition of components of the so-called MS. Likewise, the reduction in the activity of antioxidant enzymes, both extracellular and cytoplasmic, was not affected by the presence of additional components of the MS. Neither the number of components nor the individual addition of each of them, low high-density lipoprotein, triglycerides, abdominal obesity or fasting glucose, further impact in the OX abnormalities observed in those with only hypertension in absence of other components. In conclusion, the present data indicates that contribution of MS components to the OX burden generated by high blood pressure is minimal.

Cellular oxidative processes in relation to renal disease

This article summarizes the biochemical processes that produce reactive oxygen species (ROS) and other mediators that account for 'oxidative stress'. Formation of ROS in signal transduction cascades is illustrated from studies of kidney cell systems. The pathophysiological implications for the nephrologist are then reviewed.

Reduced renal ClC-5 Cl− channel expression in spontaneously hypertensive rats with microalbuminuria

Mutations in a renal-specific Cl(-) channel, ClC-5, result in low-molecular-weight proteinuria. Herein we studied ClC-5 expression in the kidneys of spontaneously hypertensive rats (SHR) to identify possible causes of their increased urinary excretion of albumin. The amount of ClC-5 protein was significantly reduced in 3-month-old SHR as compared with normotensive Wistar/Kyoto (WKY) rats. The ClC-5 protein level was partially restored by short term administration of perindopril, an inhibitor of angiotensin-converting enzyme. Corresponding to the increase in ClC-5 expression, the albuminuria in SHR improved to the control level. These results implicate the ClC-5 Cl(-) channel reduction in the development of albuminuria in the early stage of essential hypertension.