Gert Mayer

Adverse effect of low-dose prophylactic human recombinant leukocyte interferon-alpha treatment in renal transplant recipients: cytomegalovirus infection prophylaxis leading to an increased incidence of irreversible rejections

Since infections with Herpetoviridae after kidney transplantation still remain a major clinical problem, we conducted a double-blind, placebo-controlled trial using low-dose recombinant interferon-alpha-2C (rIFNa2C) prophylaxis in 50 renal graft recipients im-munosupressed with cyclosporine and methylpredniso-lone. Ten patients were excluded from further analysis because of graft loss due to surgical complications, side effects of rIFNa2C, and because of lack of compliance. There was a significant difference in graft loss due to irreversible rejections between the verum and the placebo group (6 vs. 0; P< 0.05), whereas no difference was observed with regard to the occurrence of viral infections. We conclude, that low-dose rIFNa2C prophylaxis is harmful in renal allograft recipients treated with cyclosporine in view of the high incidence of irreversible transplant rejections without beneficial effects on the occurrence of viral infections.

Regular physical exercise improves endothelial function in heart transplant recipients

Background:u2002Impaired endothelial function is detectable in heart transplant (HTX) recipients and regarded as risk factor for coronary artery disease. We have studied whether endothelial function can be improved in HTX patients participating in a regular physical training program as demonstrated in patients with chronic heart failure, hypertension and coronary artery disease.

Angiotensin-converting enzyme and angiotensin II receptor 1 polymorphism in coronary disease and malignant ventricular arrhythmias

OBJECTIVESnIt has been reported that patients carrying the angiotensin-converting enzyme (ACE) deletion DD genotype with the angiotensin II type 1 (AT1) C allele are at increased risk for myocardial infarction. The frequency distribution of the ACE and AT1 receptor gene polymorphism and their possible relation regarding malignant ventricular arrhythmias in patients with coronary artery disease (CAD) and left ventricular dysfunction was determined.nnnMETHODSnThe ACE I/D and AT1 A/C polymorphisms (using polymerase chain reaction) in 100 Caucasian patients suffering from CAD with a history of malignant ventricular arrhythmias treated with an implantable cardioverter defibrillator (ICD group) was compared to 127 age-matched Caucasian patients with CAD and no history of malignant ventricular arrhythmias (control group). All patients had reduced left ventricular ejection fraction of < 40% and were comparable regarding sex distribution, body mass index, ACE-inhibitor treatment, lipid status and duration of CAD.nnnRESULTSnThe prevalence of DD/CC in the ICD group was significantly higher (19% versus 10%, p < 0.0001). The risk for malignant ventricular arrhythmias was associated with the combination of ACE D and AT1 C alleles (odds-ratio: 2.4, 95% confidence interval 1.41 to 3.94, p < 0.001). The distribution of ACE and AT1 genotypes was not different between the two group.nnnCONCLUSIONSnPatients with coronary artery disease and left ventricular dysfunction carrying ACE D and AT1 C alleles are at increased risk for development of malignant ventricular arrhythmias. Because of available pharmacological inhibitors, these results may have clinical implications for the prevention of sudden cardiac death.

Glomerular permselectivity in proteinuric patients after kidney transplantation.

To characterize the defect in glomerular permselectivity responsible for proteinuria after renal transplantation, we studied 10 patients with moderate proteinuria (median 0.37 g/d, range 0.20-0.79), 16 patients with the nephrotic syndrome (6.73 g/d, 3.9-14.6), 8 living related donor transplant recipients without any history of rejection (median proteinuria 0.26 g/d, 0.06-0.58), and 12 healthy volunteers. The fractional clearance of neutral dextrans > 54 A was significantly higher in nephrotic patients, demonstrating a defect in glomerular size selectivity. Using a log-normal model of glomerular pore size distribution, r*(5%) and r*(1%), indices for the presence of large pores, were increased in the nephrotic patients. The fractional clearance of negatively charged dextran sulfate was significantly higher in all patient groups, indicating a loss of glomerular charge selectivity. Biopsy findings showed more prominent glomerular lesions in the nephrotic group compared with the moderately proteinuric group. We conclude that mild proteinuria late after renal transplantation is associated with a defect in glomerular charge selectivity. The development of nephrotic range proteinuria is associated also with a defect of glomerular size selectivity, which correlates with prominent glomerular pathology.

Effects of dichloroacetate on exercise performance in healthy volunteers

Dichloroacetate (DCA), a stimulator of the pyruvate dehydrogenase complex, decreases lactate levels and peripheral resistance and increases cardiac output. This study was performed to examine the effects of DCA on exercise performance in humans. Eight healthy male volunteers (age 20–28 years) were tested by bicycle spiro-ergometry using a microprocessor-controlled gas analysis system after infusion of DCA (50 mg/kg body weight) or saline. Prior infusion of DCA significantly reduced the increase of lactate levels during exercise when compared with infusion of saline (1.40±0.21 vs 2.10±0.09 mmol·l−1 at 50% of the expected maximal working capacity, P<0.05; 8.53±0.45 vs 9.92±0.59 mmol·l−1 at maximal working capacity, P<0.05). Oxygen uptake increased significantly after DCA when compared with saline from 7.5±0.4 vs 7.4±0.5 to 27.2±1.5 vs 23.7±1.7 (P<0.05) at anaerobic threshold and to 35.6±1.7 vs 30.5±1.0 ml · kg−1 min−1 (P<0.05) at maximal exercise capacity. Following DCA infusion the workload at which the anaerobic threshold was reached was significantly higher (160±7 vs 120±5 W, P<0.05) and the maximal working capacity was significantly increased (230±9 vs 209±8 W, P<0.05). In summary, DCA reduced the increase of lactate levels during exercise and increased oxygen uptake at the anaerobic threshold and at maximal working capacity, which was significantly increased. These results warrant further studies on a potential therapeutic application of DCA in patients with reduced exercise capacity.

The long-term effect of simultaneous heart and kidney transplantation on native renal function.

Background. It is unclear whether patients with heart failure and renal insufficiency should receive a simultaneous heart and kidney transplant or whether a single heart transplantation is sufficient to restore native renal function. Methods. We analyzed the renal plasma flow and glomerular filtration of the native and transplant kidneys in eight patients long term after simultaneous heart and kidney transplantation using a dynamic MAG3 radioisotope scan and serum creatinine determinations. All subjects had been hemodialysis dependent before transplantation. Seven patients suffered from an intrinsic renal disease that were diabetic nephropathy in three cases, small fibrotic kidneys of undetermined origin in two cases, one lupus nephritis, and cyclosporine nephrotoxicity in one patient who had a previous heart transplant. In one patient renal insufficiency was considered to be solely due to renal hypoperfusion because no intrinsic renal disease could be detected. Results. All patients were on cyclosporine-based triple immunosuppression, transplanted for 4 to 10 years, exhibited cardiac ejection fractions of more than 50% and had normal serum creatinine values. Radioisotopic scan showed no function of the native kidneys in all seven patients with intrinsic renal disease but exhibited normal function of the native kidneys as well as the renal transplant in the patient without intrinsic kidney disease before transplantation. Conclusions. These data suggest that a simultaneous heart and kidney transplantation is necessary in patients with cardiomyopathy and renal insufficiency due to primary kidney disease, but not in those with hemodynamically mediated renal failure, even if an immunosuppressive regimen with calcineurin inhibitors is used.

Multiple‐dose pharmacokinetics of cefpirome in long‐term hemodialysis with high‐flux membranes

Cefpirome is a cephalosporin eliminated primarily by kidneys that requires dosage reduction in patients with renal failure. The pharmacokinetic parameters were studied in 10 patients with end‐stage renal disease who were receiving hemodialysis. Repeated intravenous administration of 2 gm cefpirome three times a week resulted in trough levels of 12.2 ± 5.4 μg/ml and peak serum concentrations of 99.6 ± 82.1 μg/ml. After 312 hours of hemodialysis with polysulfone high‐flux membranes, 62.3% ± 23.3% of cefpirome was removed. The interdialytic half‐life was 9.35 ± 0.99 hours, and the intradialytic half‐life was 2.02 ± 0.7 hours.

Hemodynamic Effects of Partial Correction of Chronic Anemia by Recombinant Human Erythropoietin in Patients on Dialysis

Eighteen patients on chronic hemodialysis with renal anemia were treated with recombinant human erythropoietin (r-HuEPO). Hemodynamic parameters in the resting state were determined before and after successful treatment. Posttreatment cardiac index was decreased (3.3 v 2.8 L/min/m2), whereas diastolic blood pressure (72 v 79 mm Hg) and calculated peripheral resistance (2,230 v 2,860 dyne.cm.s-5) were increased significantly when compared with the pretreatment period. We conclude from our study that the increase of blood pressure as seen in patients on dialysis, who are effectively treated with r-HuEPO, is due to an increase in peripheral resistance. This increase overrules the decrease of cardiac index and might well be a result of peripheral vasoconstriction due to improved oxygen availability.

Biocompatibility of high-flux membranes.

Standard dialysis with cuprophane membranes is known to stimulate the immune system. As a result of activation of macrophages various interleukins and tumor necrosis factor (TNF) are secreted, presenting further evidence of the poor biocompatibility of cuprophane. We investigated the immunogenic properties of three modern high-flux membranes. Seven patients were studied during hemodiafiltration sessions using either a polysulfone (F60, Fresenius), a polymethylmetacrylate (BK 2.1, Toray) or a cellulose triacetate (FB-210 U, Nipro) dialyzer in a hemodiafiltration procedure. Serial measurements were made during each treatment of interleukin-1β (II-1β), TNF, soluble IL-2 receptor (sII-2r), soluble CD4 (sCD4), soluble CD8 (sCD8), interferon gamma (IFNg) and neopterin. In contrast to the known increase of IL-1β, IL-2r and TNF with cuprophane membranes, none of the modern high-flux dialyzers stimulated the production of these factors. Significant decreases of neopterin and sCD4 were observed. IFNg and sCD8 did not change significantly. Our results suggest that the modern high-flux dialyzers are non-immunogenic, and thus provide further evidence of the superior biocompatibility of synthetic or semisynthetic membranes over the conventional cuprophane.