Multifactorial determination of hypertensive nephroangiosclerosis

Treatment of hypertension in chronic kidney disease patients under specialized care: one-center cross-sectional analyses

AIM

The study analyzed hypertension management and control rates among non-dialysis, non-transplanted hypertensive chronic kidney disease (CKD) patients under specialized care in Gdansk nephrology center in 1996-2011.

PATIENTS AND METHODS

It was a retrospective, cross-sectional study analyzing data from medical records of 190, 490, 1799 and 1696 subjects with CKD, who received outpatient care in 1996, 2001, 2006 and 2011, and were included in four independent surveys, respectively.

RESULTS

The average number of antihypertensive drugs per patient increased significantly (p < 0.01) as follows 1.74 ± 0.9 (1996), 2.08 ± 1.01 (2011), 2.5 ± 1.19 (2006) and 2.65 ± 1.18 (2011). The percentage of patients receiving diuretics, beta-blockers and drugs inhibiting renin-angiotensin-aldosterone increased significantly in subsequent years, while a frequency of therapy with calcium channel blockers decreased (p < 0.001). 16%, 30%, 42% and 54% of subjects had causal BP values < 140/90 mmHg (p < 0.001). When specific thresholds for CKD patients according to JNC recommendations were used, the control rate was worse but also showed significant improvement in the second, third and final surveys, i.e. 9%, 12%, 14% and 24% (p < 0.001). The subgroup analysis revealed that a better control rate was observed in following groups: < 65 years old; I-II stage of CKD; primary glomerulonephritis; without cardiovascular complications or diabetes.

CONCLUSION

The study may show an improvement in the effectiveness of antihypertensive treatment in CKD patients under specialized care in Gdansk Nephrology Centre in 1996-2011.

Increased susceptibility to kidney injury by transfer of genomic segment from SHR onto Dahl S genetic background

The Dahl salt-sensitive (S) rat is a widely studied model of salt-sensitive hypertension and develops proteinuria, glomerulosclerosis, and renal interstitial fibrosis. An earlier genetic analysis using a population derived from the S and spontaneously hypertensive rat (SHR) identified eight genomic regions linked to renal injury in the S rat and one protective locus on chromosome 11. The "protective" locus in the S rat was replaced with the SHR genomic segment conferring "susceptibility" to kidney injury. The progression of kidney injury in the S.SHR(11) congenic strain was characterized in the present study. Groups of S and S.SHR(11) rats were followed for 12 wk on either a low-salt (0.3% NaCl) or high-salt (2% NaCl) diet. By week 12 (low-salt), S.SHR(11) demonstrated a significant decline in kidney function compared with the S. Blood pressure was significantly elevated in both strains on high salt. Despite similar blood pressure, the S.SHR(11) exhibited a more significant decline in kidney function compared with the S. The decline in S.SHR(11) kidney function was associated with more severe kidney injury including tubular loss, immune cell infiltration, and tubulointerstitial fibrosis compared with the S. Most prominently, the S.SHR(11) exhibited a high degree of medullary fibrosis and a significant increase in renal vascular medial hypertrophy. In summary, genetic modification of the S rat generated a model of accelerated renal disease that may provide a better system to study progression to renal failure as well as lead to the identification of genetic variants involved in kidney injury.

Chronic kidney disease in postmenopausal women

Menopause is derived from the Greek words men (month) and pauses (cessation) and means permanent cessation of menstruation after the loss of ovarian activity. Chronic kidney disease (CKD) has recently been associated with cardiovascular events in several studies. CKD patients have a heavy burden of traditional cardiovascular risk factors in addition to a range of nontraditional risk factors such as inflammation and abnormal metabolism of calcium and phosphate. In this review, the association of CKD and cardiovascular disease (CVD), as well as of osteoporosis in postmenopausal women is discussed. CKD mineral and bone disorder, characterized by disturbances of calcium/phosphate/parathyroid hormone, bone abnormalities and vascular and soft tissue calcification, is highly prevalent in CKD and is a strong, independent predictor of bone fracture, CVD and death. Estrogen has been shown to: (a) decrease the expression of angiotensin type 1 receptors in vasculature and kidneys; (b) reduce the expression and activity of angiotensin-converting enzyme, and (c) cause the release of angiotensinogen substrate from the liver. However, the degree of activation or suppression of the renin-angiotensin-aldosterone system by estrogen has not been clearly established. Clinical data on the effects of estrogen therapy on bone mineral densities are extremely limited in the ESRD population. CVD is the most common cause of death in postmenopausal women with CKD and many contributing factors have been explored. Future research for prevention of CVD in postmenopausal women with CKD would focus on the biology of vascular calcification as well as bone loss.

Dissection of a genetic locus influencing renal function in the rat and its concordance with kidney disease loci on human chromosome 1q21

Previously, we conducted a genome scan on a population derived from the Dahl salt-sensitive hypertensive (S) and the spontaneously hypertensive rat (SHR) using urinary albumin excretion (UAE) as our primary measure of renal function. We identified 10 quantitative trait loci (QTL) linked to several renal and/or cardiovascular traits. In particular, linkage and subsequent congenic strain analysis demonstrated that the loci on chromosome 2 had a large and significant effect on UAE compared with the S rat. The present work sought to characterize the chromosome 2 congenic strain [S.SHR] by conducting a time-course analysis (week 4-20), including evaluating additional renal parameters, histology, electron microscopy, and gene expression/ pathway analysis. Throughout the time course the congenic strain consistently maintained a threefold reduction in UAE compared with S rats and was supported by the histological findings of significantly reduced glomerular, tubular and interstitial changes. Gene expression/pathway analysis performed at week 4, 12, and 20 revealed that pathways involved in cellular assembly and organization, cellular movement, and immune response were controlled differently between the S and congenic. When all the data are considered, the chromosome 2 congenic appears to attenuate renal damage primarily through an altered fibrotic response. Recombinant progeny testing was employed to reduce the QTL to approximately 1.5 cM containing several interesting candidate genes. The concordance of this rat QTL with renal disease loci on human chromosome 1q21 demonstrate that elucidating the causative gene and mechanism of the rat QTL may be of particular importance for understanding kidney disease in humans.

Contrast Medium Administration in the Elderly Patient: Is Advancing Age an Independent Risk Factor for Contrast Nephropathy after Angiographic Procedures?

Contrast medium-induced nephropathy (CMIN) is the third leading cause of hospital-acquired acute renal dysfunction. Even if the number of patients over 75 years of age undergoing diagnostic and/or interventional procedures and requiring administration of contrast medium (CM) is growing constantly, at present there is no definitive consensus regarding the role of advancing age and related morphologic or functional renal changes as an independent risk factor for CMIN. The authors review the evidence from recent medical literature on the definition, pathophysiology, and clinical presentation of CMIN as well as therapeutic approaches to its prophylaxis. Attention is focused on advancing age as a preexisting physiologic condition that is, per se, able to predispose the patient to CM-induced renal impairment, assuming that every elderly patient is potentially at risk for CMIN.

Smoking as a risk factor for renal injury in essential hypertension

BACKGROUND

Smoking is an important player in the pathogenesis of hypertensive nephropathy. To shed more light on this issue, we performed a case-control cross-sectional study and stratification analyses to evaluate the influence of smoking on surrogate markers of kidney injury and oxidative stress in patients supposed to have hypertensive nephropathy. The dependence of kidney lesions on the 'extent' of smoking was determined as well.

METHODS

82 patients with essential hypertension and micro- or macro-albuminuria were recruited. The control group consisted of 41 sex- and age-matched healthy individuals. Urine albumin creatinine ratio and plasma von Willebrand factor activity were analysed as markers of endothelial injury. N-acetyl-beta-D-glucosaminidase, transforming growth factor-beta1 and 15-isoprostane F2t urine excretions were regarded as markers of tubular dysfunction, renal fibrosis and oxidative stress, respectively. Patients' smoking habits were recorded and categorized on the basis of a self-administered questionnaire.

RESULTS

In multivariate regression analysis, the independent associations between smoking and urine albumin (p < 0.05; beta = 0.27), von Willebrand factor activity (p < 0.05; beta = 0.29) and urine isoprostanes (p < 0.05; beta = 0.28) were found. When the smokers were stratified according to the number of cigarettes smoked per day and the time from which they started smoking, 'heavy smokers' and 'long-term smokers' presented with higher albumin excretion and higher von Willebrand factor activity than 'light smokers' and 'short-term smokers', respectively. The passive smokers had numerically higher albumin excretion and von Willebrand factor activity than nonsmokers.

CONCLUSION

The study showed that smoking induces oxidative stress. Smoking was also found to be a strong predictor for the extent of endothelial injury in patients with hypertensive kidney injury. Subjects who smoke heavily and for a long time, as well as passive smokers, seem to be particularly exposed to endothelial damage.

[Sequelae of hypertenson: kidney disease]

Nephropathy is one of the frequent sequelae of hypertension. Arterial hypertension causes both arterial and capillary changes in the kidneys as well as development of interstitial fibrosis. Systemic or intraglomerular pressure increase leads to albuminuria and proteinuria, which in turn contributes to further damage of the kidneys. Impairment of the kidneys due to hypertension can ultimately result in terminal renal insufficiency necessitating dialysis. Metabolic factors such as hyperlipidemia, hyperuricemia, hyperhomocysteinemia, and insulin resistance can aggravate renal lesions. Effective lowering of blood pressure in conjunction with management of the metabolic risk factors is decisive for prevention of chronic kidney disease, which in turn must be considered a factor involved in exacerbation of the hypertension.