Angiotensin II receptor blockade reduces salt sensitivity of blood pressure through restoration of renal nitric oxide synthesis in patients with diabetic nephropathy

INTRODUCTION

We have previously demonstrated the increased salt sensitivity of blood pressure (BP) in diabetic patients with early nephropathy. Here, we examined the effects of an angiotensin II receptor blocker (ARB) on salt sensitivity and renal oxidative stress or nitric oxide (NO) in those patients.

PATIENTS AND METHODS

Type 2 diabetic patients with (n = 6) and without (n = 6) microalbuminuria were studied on a high-salt diet for one week and on a salt-restricted diet for one week. The study was repeated in the patients with microalbuminuria during treatment with an ARB, valsartan (80 mg/day). Salt sensitivity was assessed from the BP/sodium excretion curve. Urinary excretion rates of NOx, 8-hydroxy-2-deoxyguanosine as a marker of oxidative stress, and plasma tetrahydrobiopterin as a cofactor for NO synthase were measured.

RESULTS

Compared with diabetic patients without microalbuminuria, patients with microalbuminuria showed greater salt sensitivity and lower urinary excretion of NOx. In the patients with microalbuminuria, treatment with valsartan reduced salt sensitivity in association with increased NOx excretion, reduced 8-hydroxy-2,-deoxyguanosine excretion, and increased plasma tetrahydrobiopterin levels.

CONCLUSIONS

These data support the hypothesis that ARBs reduce the salt sensitivity of BP by decreasing renal oxidative stress and restoring NO activity in diabetic patients with microalbuminuria.

Urinary angiotensinogen reflects the activity of intrarenal renin-angiotensin system in patients with IgA nephropathy

BACKGROUND

A potential contribution of local activation of the renin-angiotensin system (RAS) to the pathogenesis of renal injury has been indicated by evidence for blood pressure-independent renoprotective effects of angiotensin II (AngII) receptor blockers (ARBs). The present study was performed to test the hypothesis that urinary angiotensinogen provides a specific index of intrarenal RAS status in patients with immunoglobulin A (IgA) nephropathy.

METHODS

This paper is a survey of urine specimens from three groups: healthy volunteers, patients with IgA nephropathy and patients with minor glomerular abnormality (MGA). Patients with hypertension, diabetes, reduced glomerular filtration rate and/or who were under any medication were excluded from this study. Urinary angiotensinogen levels were measured by a sandwich enzyme-linked immunosorbent assay system.

RESULTS

Urinary angiotensinogen levels were not different between healthy volunteers and patients with MGA. However, urinary angiotensinogen levels, renal tissue angiotensinogen expression and AngII immunoreactivity were significantly higher in patients with IgA nephropathy than in patients with MGA. Baseline urinary angiotensinogen levels were positively correlated with renal angiotensinogen gene expression and AngII immunoreactivity but not with plasma renin activity or the urinary protein excretion rate. In patients with IgA nephropathy, treatment with an ARB, valsartan (40 mg/day), significantly increased renal plasma flow and decreased filtration fraction, which were associated with reductions in urinary angiotensinogen levels.

CONCLUSION

These data indicate that urinary angiotensinogen is a powerful tool for determining intrarenal RAS status and associated renal derangement in patients with IgA nephropathy.

Cerebral microvascular disease predicts renal failure in type 2 diabetes

Abnormalities in small renal vessels may increase the risk of developing impaired renal function, but methods to assess these vessels are extremely limited. We hypothesized that the presence of small vessel disease in the brain, which manifests as silent cerebral infarction (SCI), may predict the progression of kidney disease in patients with type 2 diabetes. We recruited 608 patients with type 2 diabetes without apparent cerebrovascular or cardiovascular disease or overt nephropathy and followed them for a mean of 7.5 years. At baseline, 177 of 608 patients had SCI, diagnosed by cerebral magnetic resonance imaging. The risk for the primary outcome of ESRD or death was significantly higher for patients with SCI than for patients without SCI [hazard ratio, 2.44; 95% confidence interval (CI) 1.36 to 4.38]. The risk for the secondary renal end point of any dialysis or doubling of the serum creatinine concentration was also significantly higher for patients with SCI (hazard ratio, 4.79; 95% CI 2.72 to 8.46). The estimated GFR declined more in patients with SCI than in those without SCI; however, the presence of SCI did not increase the risk for progression of albuminuria. In conclusion, independent of microalbuminuria, cerebral microvascular disease predicted renal morbidity among patients with type 2 diabetes.

Prevalence of metabolic syndrome in the general Japanese population in 2000

To determine the prevalence of metabolic syndrome in the Japanese general population, we analyzed data from a nationwide survey conducted in 2000. According to the Japanese new diagnostic criteria for metabolic syndrome in 2005, we analyzed 3,264 people aged from 20 to 79 (men, 1,917; women, 1,347) from the total participants. The incidence of metabolic syndrome was 7.8%. Men had a higher incidence (12.1%) than women (1.7%). Most of the women satisfying the criteria were 50 years old or over, while the incidence in men started to rise from their 30s. When we applied the criteria of Adult Treatment Panel III, the incidence was about 3-fold higher. In this population visceral obesity was associated with metabolic abnormalities, such as higher LDL-cholesterol, triglyceride, glucose, and blood pressure and lower HDL-cholesterol. Thus we determined the incidence of metabolic syndrome and each metabolic abnormality in the Japanese general population in 2000 and found an association of visceral obesity with metabolic abnormalities. Intervention to reduce the incidence of metabolic syndrome in Japan is necessary to reduce the risk of cardiovascular disease.

Risk Factors for Hypoxemia After Surgery for Acute Type A Aortic Dissection

PURPOSE

Postoperative hypoxemia is a frequent complication of surgery for acute type A aortic dissection. We tried to determine the factors associated with postoperative hypoxemia.

METHODS

Between 1997 and 2003, 114 patients underwent surgery for acute type A aortic dissection. Multivariate logistic regression analysis was done to identify the independent predictors of postoperative hypoxemia, defined by an arterial partial oxygen/inspired oxygen fraction (PaO(2)/FiO(2)) ratio of 200 or lower.

RESULTS

The overall in-hospital mortality was 6.1% (7 of 114 patients), being 5.2% in the hypoxemia group and 6.9% in the non-hypoxemia group. The ventilation time and intensive care unit stay were significantly longer in the hypoxemia group than in the non-hypoxemia group (P = 0.0044, P = 0.038, respectively). Logistic regression identified the following variables as predictors for postoperative hypoxemia: body mass index > or = 25 (odds ratio [OR], 5.6; 95% confidence interval [CI], 2.1-15.01; P < 0.001), preoperative PaO(2)/FiO(2) ratio < or = 300 (OR, 2.6; 95% CI, 1.09-6.13; P = 0.031), and the volume of transfused blood (OR, 1.08; 95% CI, 1.01-1.18; P = 0.037).

CONCLUSIONS

Initiating early treatment for hypoxemia and reducing the volume of blood transfused intraoperatively may improve the postoperative clinical course of obese patients with preoperative hypoxemia.

Polymorphisms in Four Genes Related to Triglyceride and HDL-cholesterol Levels in the General Japanese Population in 2000

We studied the association of six common polymorphisms of four genes related to lipid metabolism with serum lipid levels. We selected single-nucleotide polymorphisms (SNPs) in the genes for cholesteryl ester transfer protein (CETP), lipoprotein lipase (LPL), hepatic lipase (LIPC), and apolipoprotein CIII (APOC3), and studied 2267 individuals randomly selected from the participants of Serum Lipid Survey 2000. There was a significant association of CETP polymorphism (D442G, Int14 +1 G --> A, and TaqIB), LPL polymorphism (S447X), and LIPC polymorphism (-514 --> CT) with HDL-cholesterol levels. We also found a significant association of LPL polymorphism (S447X) and APOC3 polymorphism (SstI) with triglyceride levels. This is the largest database showing the association of common genetic variants in lipid metabolism with serum lipid levels in the general Japanese population. Further study is necessary to elucidate the role of these gene polymorphisms in cardiovascular events.

Effects of daily alcohol intake on the blood pressure differ depending on an individual's sensitivity to alcohol: oriental flushing as a sign to stop drinking for health reasons

OBJECTIVE

To determine whether flushing of the facial skin in response to alcohol consumption (alcohol flushing) is a warning sign of hypertension. We also sought the relationship between alcohol flushing and other risk factors that may contribute to the development of hypertension.

METHODS

We first investigated the relationship of the aldehyde dehydrogenase 2 (ALDH2) genotype to alcohol flushing for 53 normal volunteers. We evaluated the relationships among hypertension, alcohol consumption, and facial flushing for 1011 middle-aged Japanese men (aged 40-68 years; mean 51.6 +/- 5.5 years), on the basis of their responses to questionnaires and health records.

RESULTS

The first examination of 53 normal volunteers showed that there were differences in the degree of alcohol flushing between the ALDH2 genotypes (P < 0.01). Hypertension was observed in 27.4% of the study population (277 of 1011), and was correlated positively to alcohol consumption (P < 0.01). The prevalence of hypertension differed significantly among these four groups: there was a 22.4% prevalence (70 of 312) among subjects with no flushing, a 33.8% prevalence (113 of 334) among those with slight flushing, a 27% prevalence (84 of 311) among those with visible flushing, and an 18.5% prevalence (10 of 54) among subjects who were almost completely intolerant to alcohol (P < 0.05). In particular, heavy drinkers who consumed > or = 1.5 Go (a traditional Japanese unit equivalent to 27 g ethanol) a day had a high prevalence of hypertension with slight and visible skin flushing [42% (63 of 150) and 40.7% (24 of 59), respectively]. That a family history of hypertension, greater age, heavy alcohol consumption, obesity, and symptoms of intoxication including flushing were correlated significantly to the prevalence of hypertension for all groups was demonstrated by multiple logistic regression analysis (P < 0.05).

CONCLUSIONS

A repeated heavy alcohol intake could increase the risk of hypertension for Japanese subjects who exhibit skin flushing in response to alcohol consumption. Chronic alcohol intake by subjects with alcohol flushing might bring about a significant increase in blood acetaldehyde levels and cause an additional rise in the blood pressure.