Impaired autoregulation of the glomerular filtration rate in patients with nondiabetic nephropathies

Impaired autoregulation of the glomerular filtration rate in patients with nondiabetic nephropathies.BackgroundThe ability of the kidney to maintain constancy of the glomerular filtration rate (GFR) over a wide range of renal perfusion pressures is termed autoregulation. Defective autoregulation of GFR has been demonstrated in diabetic nephropathy. Whether this is also the case in patients with nondiabetic nephropathies is not known.MethodsWe investigated the effect of acute lowering of blood pressure (BP) on GFR in 16 (8 males and 8 females) albuminuric subjects suffering from different nondiabetic nephropathies and in 14 (7 males and 7 females) controls matched with respect to sex, age, BP, and baseline GFR. The subjects received in random order an intravenous injection of either clonidine (150 to 225 μg) or saline (0.154 mmol/liter) within two weeks. We measured GFR ([51Cr]-EDTA), albuminuria (enzyme-linked immunosorbent assay; ELISA), and BP (Takeda TM-2420).ResultsClonidine induced similar reductions in mean arterial BP 17 (2) versus 19 (2) mm Hg [mean (SE)] in patients with nephropathy and in controls, respectively. GFR diminished in average from 89 (6) to 82 (5) ml/min/1.73 m2 (P < 0.05), and albuminuria declined from a geometric mean of 1218 (antilog SE 1.3) μg/min to 925 (1.3) in the patients with nondiabetic nephropathies (P < 0.05), whereas these variables remained unchanged in the control group. The mean difference between changes in GFR (95% confidence interval) between the nondiabetic macroalbuminuric and control subjects was 6.1 (-0.03 to 12.21) ml/min/1.73 m2 (P = 0.051).ConclusionOur study suggests that albuminuric patients with nondiabetic nephropathies frequently suffer from impaired autoregulation of GFR

Long-term enzyme replacement therapy is associated with reduced proteinuria and preserved proximal tubular function in women with Fabry disease

Background Fabry disease is an X-linked lysosomal storage disorder caused by mutations in the GLA gene. Deficiency of α-galactosidase A (α-Gal A) causes intracellular accumulations of globotriaosylceramide (GL-3) and related glycosphingolipids in all organs, including the kidney, often leading to end-stage renal failure. In women with Fabry disease, accumulation of GL-3 in the glomerular podocytes and other renal cells induces progressive, proteinuric nephropathy, but not as severe as in men. Enzyme replacement therapy (ERT) with recombinant α-Gal A reduces cellular GL-3 deposits in podocytes and tubular epithelial cells. We have previously shown that α-Gal A is delivered to these cells by different pathways involving different receptors. This study investigated the long-term changes in albuminuria, estimated glomerular filtration rate (eGFR) and urinary markers of both glomerular and tubular dysfunction in women with Fabry disease treated with ERT. Methods A retrospective, single centre, cohort study evaluated the long-term association between ERT, albuminuria and eGFR in 13 women with Fabry disease and mild renal involvement. In particular, we analysed the changes in the proteinuric profile, including the glomerular marker IgG, the tubular markers α1-microglobulin and retinol-binding protein (RBP), and the shared tubular and glomerular markers albumin and transferrin. Results ERT was associated with a significant reduction in albuminuria and a relatively stable eGFR. The decrease in albuminuria was paralleled by a decrease in both glomerular and tubular urine protein markers. Conclusions The data indicate that long-term ERT is associated with a reduction in albuminuria and glomerular and tubular urinary protein markers in women with Fabry disease and mild renal manifestation

Vascular function in adults with cyanotic congenital heart disease

Background Patients with cyanotic congenital heart disease (CCHD) may have a low burden of atherosclerosis. Endothelial dysfunction is an early stage of atherosclerosis and endothelial function is previously studied in smaller CCHD groups with different techniques and variable results. We aimed to examine endothelial function and carotid atherosclerosis in a larger group of CCHD patients. Methods This multicentre study assessed endothelial function in adults with CCHD and controls by measuring the dilatory response of the brachial artery to post-ischemic hyperaemia (endothelium-dependent flow-mediated-vasodilatation (FMD)), and to nitroglycerin (endothelium-independent nitroglycerin-induced dilatation (NID)). Flow was measured at baseline and after ischaemia (reactive hyperaemia). Carotid-intima-media-thickness (CIMT), prevalence of carotid plaque and plaque thickness (cPT-max) were evaluated ultrasonographically. Lipoproteins, inflammatory and vascular markers, including sphingosine-1-phosphate (S1P) were measured. Results Forty-five patients with CCHD (median age 50 years) and 45 matched controls (median age 52 years) were included. The patients presented with lower reactive hyperaemia (409 ± 114% vs. 611 ± 248%, p < 0.0001), however preserved FMD response compared to controls (106.5 ± 8.3% vs. 106.4 ± 6.1%, p = 0.95). In contrast, NID was lower in the patients (110.5 ± 6.1% vs. 115.1 ± 7.4%, p = 0.053). There was no difference in CIMT, carotid plaque or cPT-max. The patients presented with lower high-density-lipoprotein cholesterol, and higher level of inflammatory markers and S1P. Conclusion Adults with CCHD had preserved FMD in the brachial artery, but impaired NID response and lower reactive hyperaemia than controls. The preserved FMD and the comparable prevalence of carotid atherosclerosis indicate that CCHD patients have the same risk of atherosclerosis as controls

Circulating Glucagon 1-61 Regulates Blood Glucose by Increasing Insulin Secretion and Hepatic Glucose Production

Glucagon is secreted from pancreatic a cells, and hypersecretion (hyperglucagonemia) contributes to diabetic hyperglycemia. Molecular heterogeneity in hyperglucagonemia is poorly investigated. By screening human plasma using high-resolution-proteomics, we identified several glucagon variants, among which proglucagon 1-61 (PG 1-61) appears to be the most abundant form. PG 1-61 is secreted in subjects with obesity, both before and after gastric bypass surgery, with protein and fat as the main drivers for secretion before surgery, but glucose after. Studies in hepatocytes and in b cells demonstrated that PG 1-61 dose-dependently increases levels of cAMP, through the glucagon receptor, and increases insulin secretion and protein levels of enzymes regulating glycogenolysis and gluconeogenesis. In rats, PG 1-61 increases blood glucose and plasma insulin and decreases plasma levels of amino acids in vivo. We conclude that glucagon variants, such as PG 1-61, may contribute to glucose regulation by stimulating hepatic glucose production and insulin secretion

Thyroid Function and Body Weight: A Community-Based Longitudinal Study

OBJECTIVE: Body weight and overt thyroid dysfunction are associated. Cross-sectional population-based studies have repeatedly found that thyroid hormone levels, even within the normal reference range, might be associated with body weight. However, for longitudinal data, the association is less clear. Thus, we tested the association between serum thyrotropin (TSH) and body weight in a community-based sample of adult persons followed for 11 years. METHODS: A random sample of 4,649 persons aged 18-65 years from a general population participated in the DanThyr study in 1997-8. We included 2,102 individuals who participated at 11-year follow-up, without current or former treatment for thyroid disease and with measurements of TSH and weight at both examinations. Multiple linear regression models were used, stratified by sex and adjusted for age, smoking status, and leisure time physical activity. RESULTS: Baseline TSH concentration was not associated with change in weight (women, P = 0.17; men, P = 0.72), and baseline body mass index (BMI) was not associated with change in TSH (women, P = 0.21; men, P = 0.85). Change in serum TSH and change in weight were significantly associated in both sexes. Weight increased by 0.3 kg (95% confidence interval [CI] 0.1, 0.4, P = 0.005) in women and 0.8 kg (95% CI 0.1, 1.4, P = 0.02) in men for every one unit TSH (mU/L) increase. CONCLUSIONS: TSH levels were not a determinant of future weight changes, and BMI was not a determinant for TSH changes, but an association between weight change and TSH change was present

The Role of Vascular Lesions in Diabetes Across a Spectrum of Clinical Kidney Disease

Introduction: The clinical-histologic correlation in diabetic nephropathy is not completely known. Methods: We analyzed nephrectomy specimens from 90 patients with diabetes and diverse degrees of proteinuria and glomerular filtration rate (GFR). Results: Thirty-six (40%) subjects had normoalbuminuria, 33 (37%) microalbuminuria, and 21 (23%) non-nephrotic proteinuria. Mean estimated GFR (eGFR) was 65±23 (40% 10% to 20% of the sample. Moderate hyalinosis and arteriolar sclerosis were observed in 80% to 100% of cases with normoalbuminuria, microalbuminuria, proteinuria, as well as in class I, II, or III. Conclusions: Weak correspondence between analytical parameters and kidney histology was found. Thus, disease may progress undetected from the early clinical stages of the disease. Finally, vascular damage was a very common finding, which highlights the role of ischemic intrarenal disease in diabetes

Plasma neutrophil gelatinase associated lipocalin (NGAL) is associated with kidney function in uraemic patients before and after kidney transplantation

<p>Abstract</p> <p>Background</p> <p>Neutrophil gelatinase associated lipocalin (NGAL) is a biomarker of kidney injury. We examined plasma levels of NGAL in a cohort of 57 kidney allograft recipients (Tx group, 39 ± 13 years), a uraemic group of 40 patients remaining on the waiting list (47 ± 11 years) and a control group of 14 healthy subjects matched for age, sex and body mass index (BMI). The kidney graft recipients were studied at baseline before transplantation and 3 and 12 months after transplantation and the uraemic group at baseline and after 12 months.</p> <p>Methods</p> <p>NGAL was measured using a validated in-house Time-Resolved Immuno-flourometric assay (TRIFMA). Repeated measurements differed by < 10% and mean values were used for statistical analyses. Spearman rank order correlation analysis and the Kruskal-Wallis non-parametric test were used to evaluate the association of NGAL concentrations with clinical parameters.</p> <p>Results</p> <p>Plasma NGAL levels before transplantation in the Tx and uraemic groups were significantly higher than in the healthy controls (1,251 μg/L, 1,478 μg/L vs. 163 μg/L, p < 0.0001). In the Tx group NGAL concentrations were associated with serum creatinine (R = 0.51, p < 0.0001), duration of end-stage renal failure (R = 0.41, p = 0.002) and leukocyte count (R = 0.29, p < 0.026). At 3 and 12 months plasma NGAL concentrations declined to 223 μg/L and 243 μg/L, respectively and were associated with homocysteine (R = 0.39, p = 0.0051 and R = 0.47, p = 0.0007).</p> <p>Conclusions</p> <p>Plasma NGAL is a novel marker of kidney function, which correlates to duration of end-stage renal failure (ESRD) and serum creatinine in uraemic patients awaiting kidney transplantation. Plasma NGAL is associated with homocysteine in transplanted patients. The prognostic value of these findings requires further studies.</p