Influence of genetic polymorphisms of the renin-angiotensin system on IgA nephropathy.

BACKGROUND: We evaluated the impact of the three major genetic polymorphisms of the renin-angiotensin system [angiotensinogen (AGT) gene M235T, angiotensin-converting enzyme (ACE) gene-I/D and angiotensin II-type 1 receptor (AT1R) gene A1166C polymorphisms] as risk factors in IgA nephropathy. METHODS: The clinical course of 107 patients with biopsy proven IgA nephropathy followed up for 6.6 +/- 5.8 years was examined. The genetic polymorphisms were determined by PCR amplification. RESULTS: The allele frequencies of the polymorphisms studied were similar in patients and control subjects. AGT-M235T genotype was associated with the presence of nephrotic syndrome (p < 0.05), correlated to the number of antihypertensive drugs agents taken (p < 0.01) and influenced the rate of deterioration of renal function (p < 0.05). Combined analysis of AGT-M235T and ACE-I/D polymorphisms detected an interaction on affecting progression (p < 0.05). ACE-inhibition had a more pronounced effect in certain AGT-M235T and ACE-I/D genotypes (p < 0.05) and their combined analysis showed a synergistic effect (p < 0.01). No association between AT(1)R-A1166C polymorphism and any of the parameters studied was observed. CONCLUSIONS: Our results suggest that angiotensinogen-M235T polymorphism is an important marker of progression in IgA nephropathy in Caucasian patients, especially when analyzed in combination with ACE-I/D polymorphism.

Tolerability and efficacy of multidose epoetin beta (Reco-Pen) for subcutaneous administration in patients with anemia due to renal failure.

AIMS: To assess the tolerability, safety and efficacy of the epoetin beta multidose cartridge formulation, self-administered subcutaneously via a pen device (Reco-Pen), in adult patients with renal anemia. METHODS: Patients receiving maintenance epoetin therapy were switched to the subcutaneous (SC) multidose formulation of epoetin beta (NeoRecormon). The frequency of adverse events, local tolerability, and changes in blood pressure and laboratory variables were recorded. Hematologic parameters, transfusion requirements and epoetin beta dosage were also assessed. RESULTS: A total of 406 patients were entered in the intention-to-treat analysis. Mean treatment duration was 82.3 days. Fifty patients (12.3%) withdrew from the study; 14 (3.4%) discontinued because of adverse events. Treatment was well tolerated, with adverse events considered probably related to treatment in only 5 cases, and 1 case of local intolerability. There were no clinically significant changes in blood pressure or laboratory variables, and no changes in hematologic parameters or transfusion requirements. Unexpectedly, the epoetin beta dose was reduced by almost one-third in patients previously maintained on SC epoetin. CONCLUSION: SC administration of this multidose epoetin beta formulation with the Reco-Pen device was well tolerated and effective. It is possible that the improved capacity to individualize dose may have contributed to the considerable reduction in SC epoetin beta dosage requirement.

Smoking as a risk factor for end-stage renal failure in men with primary renal disease.

BACKGROUND: It is not known whether smoking increases the risk of end-stage renal failure (ESRF) in patients with primary renal disease. METHODS: We performed a retrospective multicenter case-control study including 582 patients from nine centers in Germany, Italy and Austria. The diseases investigated were IgA glomerulonephritis (IgA-GN) as a model of inflammatory renal disease and autosomal dominant polycystic kidney disease (ADPKD) as a model of non-inflammatory renal disease. Cases were patients who had progressed to ESRF and controls were patients who were not in ESRF, that is, whose serum-creatinine failed to progress to >3 mg/dl during the observation period and who did not require renal replacement therapy. Matching for renal disease (IgA-GN, ADPKD), gender, age at renal death and region of residence resulted in 102 individually matched pairs (IgA-GN N = 54, ADPKD N = 48). Multiple conditional logistic regression was used to estimate adjusted odds ratios for independent tobacco effects. RESULTS: In men (matched pairs: IgA-GN N = 44, ADPKD N = 28), a significant dose-dependent increase of the risk to progress to ESRF was found (non-adjusted). The baseline risk was defined as <5 pack-years (PY): (i) 5 to 15 PY, odds ratio 3.5 (95% CI 1.3 to 9.6), P = 0.017; (ii) >15 PY = 5.8 (2.0 to 17), P = 0.001. Systolic blood pressure, ACE inhibitor treatment and age at diagnosis emerged as potential confounders. After adjustment, the risk for ESRF in men with >5 PY was highly increased for patients without ACE inhibitor treatment [10.1 (2.3 to 45), P = 0.002] but not with ACE inhibitor treatment [1.4 (0.3 to 7.1), P = 0.65]. CONCLUSION: Smoking increases the risk of ESRF in men with inflammatory and non-inflammatory renal disease.

Alterations of polymorphonuclear leukocyte glycogen metabolism and glucose uptake in dialysis patients.

Human polymorphonuclear leukocytes (PMNs) are activated during extracorporeal circulation. An indicator of PMN activation may be the glycogen-degrading enzyme phosphorylase. It is unknown whether dialysis therapy may influence PMN carbohydrate metabolism. Therefore, PMNs were isolated from healthy control subjects, patients undergoing continuous ambulatory peritoneal dialysis (CAPD), and patients undergoing regular hemodialysis therapy (RDT) before, during, and at the end of hemodialysis (HD) treatment using dialyzers made of polysulfone or polymethylmethacrylate (PMMA). Nifedipine (NIF) was continuously infused during HD with PMMA in 5 patients at a dose of 18 micrograms/kg body weight per hour. Glycogen, activity of glycogen synthetase and phosphorylase (active and inactive forms of both enzymes), and glucose uptake with and without stimulation with the chemotactic peptide FMLP were determined in these PMNs. During HD with PMMA, there was a significant increase of PMN phosphorylase "a" activity 15 and 30 minutes after the start of HD. HD with polysulfone did not stimulate the active "a" form of the glycogen-degrading enzyme in PMNs. HD with PMMA significantly inhibited the active I-form of glycogen synthetase, whereas polysulfone activated glycogen synthetase I. NIF inhibited phosphorylase "a" activation during HD with PMMA. PMN glycogen content and glucose uptake were improved during HD with polysulfone, but not with PMMA. PMN glycogen content, activity of glycogen synthetase, and glucose uptake were significantly lower also in CAPD patients compared with healthy controls. These data show that HD with PMMA activates PMN glycogenolysis. This effect can be inhibited by calcium channel blockers. PMN glycogen content of RDT and CAPD patients is significantly lower compared with healthy controls due to inhibition of glycogen synthesis. Elimination of dialyzable factor(s) improves, but does not restore, PMN glycogen synthesis and glucose uptake.

[Kaposi's sarcoma after kidney transplantation]. / Kaposi-Sarkom nach Nierentransplantation.

A Kaposi's sarcoma of the skin with nodular and follicular lesions but no visceral involvement developed in a 44-year-old man nine months after transplantation of an haplo-identical kidney (a relative as donor). He was on an immunosuppressive regimen of daily 10 mg methylprednisolone and 2.5 mg/kg cyclosporin A. No HIV antibodies were demonstrated. After reduction of the dosage to 4 mg methylprednisolone and 1 mg/kg cyclosporin A no further growth of the skin lesions was observed, while transplant function was maintained. The lesions regressed after radiation of two areas in the right lower leg with 48 Gy. Ten months later the sarcoma again progressed and required further radiotherapy, which arrested growth, while there was no change in transplant function.

Effect of phosphate depletion on gluconeogenesis in isolated rat hepatocytes.

In isolated hepatocytes of rats with advanced phosphate depletion (serum Pi in controls: 8.79 +/- 0.16 mg/dl; Pi depletion: 2.79 +/- 0.18 mg/dl), diminished gluconeogenesis is observed [controls: 247 +/- 21 nmol X (mg protein)-1 X (30 min)-1; Pi depletion: 174 +/- 15]. In vitro stimulation with glucagon (28 nmol/l) caused a significant rise of glucose production, fall in lactate production, and increase in cAMP content in controls, but did not change glucose or lactate production in Pi depletion despite significant stimulation of cAMP content. This defect was not corrected by pretreating Pi-depleted animals with somatostatin. Impaired basal and glucagon-stimulated glucose production by hepatocytes of Pi-depleted animals was not reversed by incubation in a medium with high Pi content. Insulin (17 nmol/l) did not influence glucose or lactate production in hepatocytes of control or Pi-depleted animals. Epinephrine (10(-6) M) caused a significant stimulation of glucose production in control animals which was inhibited both by phenoxybenzamine (10(-4) M) and propranolol (10(-3) M). Epinephrine-mediated increase of glucose production with pyruvate (10 mM) as substrate was reduced but still demonstrable in hepatocytes of phosphate-depleted animals in parallel with a significant rise of hepatocellular cAMP concentration. Various concentrations of bovine PTH1-34 failed to affect cAMP concentration, glucose or lactate production in Pi-depleted animals and glucose or lactate production in controls. Impaired basal and stimulated (glucagon and epinephrine) glucose production despite adequate cellular cAMP generation points to steps distal to adenylate cyclase as the cause of disturbed hepatic gluconeogenesis in phosphate depletion.

Cardiac function in experimental uremia.

In acutely uremic animals, the contractile force of the heart is consistently increased; such an increase can be dissociated from changes of afterload or catecholaminergic drive. It is associated with diminished sarcolemmal Na,K-ATPase activity in the heart which, in turn, may be related to increased levels of endogenous digitalis-like substances (endigens) that have been postulated to represent a natriuretic factor. In patients with chronic uremia, myocardial contractility is usually normal, but occasionally there may be heart failure unrelated to pre-existing hypertension, coronary heart disease, anemia, fluid overload, or other recognizable factors. So far, the experimental basis for this clinical observation is uncertain. Possible causes for the clinical syndrome include an excess of parathyroid hormone or cardiodepressor substances. There is experimental evidence of impaired cardiac response to beta adrenergic agonists, e.g., decreased isoproterenol-dependent calcium uptake, diminished inotropic and chronotropic responses. In acutely uremic rats, cardiac cyclic AMP levels are high but can be reversed by beta blockers. Heart calcium content is variable and heart weight is constantly increased in acutely uremic rats, despite decreased skeletal muscle mass. The change in heart weight is not related to anemia, to an excess of parathyroid hormone, or to sympathetic activity; its cause remains unknown. Experimental studies to date have shown a variety of abnormalities, but do not provide a uniform concept of the mechanisms or an explanation for the cardiac dysfunction so often observed in patients with uremia.

Glycogen metabolism in phosphorus-depleted rats.

Glycogen content as well as the enzymes of glycogenolysis and glycogen synthesis were examined in myocardium, skeletal muscle, liver and kidneys of rats with dietary phosphorus deprivation. Myocardial glycogen content was decreased and this was accompanied by activation of the enzymes of glycogenolysis and inhibition of the enzymes of glycogen synthesis. Beta blockade (nadolol) abolished the effect of phosphorus depletion (PD) on myocardial glycogen metabolism, documenting that the effect of PD is mediated, at least in part, by increased sympathetic activity. Furthermore, administration of insulin caused a marked increase of glycogen content in the heart of both control and phosphorus-depleted (PD) animals. There was no change of glycogen content or the activities of enzymes of glycogen metabolism in skeletal muscle or kidney, but a decrease of glycogen content of the liver was observed in PD animals.