R. Fedor

New perspectives in the renin-angiotensin-aldosterone system (RAAS) IV: circulating ACE2 as a biomarker of systolic dysfunction in human hypertension and heart failure.

Background Growing evidence exists for soluble Angiotensin Converting Enzyme-2 (sACE2) as a biomarker in definitive heart failure (HF), but there is little information about changes in sACE2 activity in hypertension with imminent heart failure and in reverse remodeling. Methods, Findings Patients with systolic HF (NYHAII-IV, enrolled for cardiac resynchronisation therapy, CRT, n = 100) were compared to hypertensive patients (n = 239) and to a healthy cohort (n = 45) with preserved ejection fraction (EF>50%) in a single center prospective clinical study. The status of the heart failure patients were checked before and after CRT. Biochemical (ACE and sACE2 activity, ACE concentration) and echocardiographic parameters (EF, left ventricular end-diastolic (EDD) and end-systolic diameter (ESD) and dP/dt) were measured. sACE2 activity negatively correlated with EF and positively with ESD and EDD in all patients populations, while it was independent in the healthy cohort. sACE2 activity was already increased in the hypertensive group, where signs for imminent heart failure (slightly decreased EF and barely increased NT-proBNP levels) were detected. sACE2 activities further increased in patients with definitive heart failure (EF<50%), while sACE2 activities decreased with the improvement of the heart failure after CRT (reverse remodeling). Serum angiotensin converting enzyme (ACE) concentrations were lower in the diseased populations, but did not show a strong correlation with the echocardiographic parameters. Conclusions Soluble ACE2 activity appears to be biomarker in heart failure, and in hypertension, where heart failure may be imminent. Our data suggest that sACE2 is involved in the pathomechanism of hypertension and HF.

Arterial stiffness in chronic renal failure and after renal transplantation.

Arterial stiffness is an independent cardiovascular risk factor, along with aging, hypertension, and cardiovascular disease. The augmentation index (AIx) and pulse wave velocity (PWV) are early markers of atherosclerotic vascular changes. Arteriography was used to determine systolic and diastolic blood pressure, pulse pressure (PP), AIx, and PWV in 82 male and 64 female renal transplant recipients (mean [SD] age, 45.3 [11.2] years). Cardiovascular risk was assessed using echocardiography and ultrasonography of the carotid arteries. The left ventricular wall thickness, ejection fraction, and stenosis of the carotid arteries were also measured. Fasting serum creatinine, cystatin C, homocysteine, C-reactive protein, immunoreactive parathyroid hormone, lipid, and calcium-phosphorus concentrations were determined. The serum cystatin concentration was 2.1 (0.2) mg/L, and the homocysteine concentration, 15.2 (2.6) micromol/L. After transplantation, body mass index, fat mass, and visceral fat area increased significantly (P < .01). The AIx was increased (AIx > or =10%) in 20% of men and 37% of women, PWV was increased (>10 m/s) in 43% of men and 34% of women, and PP was pathologically high (>12 m/s) in 10% of men and 12% of women. The PWV was significantly related to age (r = 0.52) and ventricular wall thickness (r = 0.46). Pulse pressure, BMI, and systolic and diastolic blood pressure correlated positively but modestly with PWV. There was a significant relationship between AIx80 and systolic (r = 0.42) and diastolic (r = 0.39) blood pressure and PP (r = 0.33). The ejection fraction correlated negatively with PWV and AIx. There was a strong association between carotid artery stenosis, PWV, and AIx80. All patients with PWV greater than 10 m/s demonstrated carotid artery stenosis. In conclusion, arteriography is an objective, noninvasive, and convenient method for early diagnosis and follow-up of atherosclerosis.

Intensity correlation-based calibration of FRET.

Dual-laser flow cytometric resonance energy transfer (FCET) is a statistically efficient and accurate way of determining proximity relationships for molecules of cells even under living conditions. In the framework of this algorithm, absolute fluorescence resonance energy transfer (FRET) efficiency is determined by the simultaneous measurement of donor-quenching and sensitized emission. A crucial point is the determination of the scaling factor α responsible for balancing the different sensitivities of the donor and acceptor signal channels. The determination of α is not simple, requiring preparation of special samples that are generally different from a double-labeled FRET sample, or by the use of sophisticated statistical estimation (least-squares) procedures. We present an alternative, free-from-spectral-constants approach for the determination of α and the absolute FRET efficiency, by an extension of the presented framework of the FCET algorithm with an analysis of the second moments (variances and covariances) of the detected intensity distributions. A quadratic equation for α is formulated with the intensity fluctuations, which is proved sufficiently robust to give accurate α-values on a cell-by-cell basis in a wide system of conditions using the same double-labeled sample from which the FRET efficiency itself is determined. This seemingly new approach is illustrated by FRET measurements between epitopes of the MHCI receptor on the cell surface of two cell lines, FT and LS174T. The figures show that whereas the common way of α determination fails at large dye-per-protein labeling ratios of mAbs, this presented-as-new approach has sufficient ability to give accurate results. Although introduced in a flow cytometer, the new approach can also be straightforwardly used with fluorescence microscopes.

Insertion/deletion polymorphism of the angiotensin-converting enzyme predicts left ventricular hypertrophy after renal transplantation.

BACKGROUND Kidney transplant recipients show a higher risk for cardiovascular complications, such as left ventricular hypertrophy and heart failure, leading to the premature death in many cases. METHODS We investigated the contribution of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism to the development of left ventricular hypertrophy (LVH), an indicator of heart disease progression among kidney transplant recipients. RESULTS We observed a significant correlation between graft function and left ventricular mass index. The occurrence of LVH or severe LVH was significantly greater among patients with at least one D-allele (ID or DD). CONCLUSION The use of ACE inhibitors or angiotensin receptor blockers seemed to be advantageous for patients with the ID and especially, the DD genotype.

Single-laser polarization FRET (polFRET) on the cell surface

A new method for the simultaneous detection of rotational mobility and proximity of cell surface receptors is presented based on cell-by-cell basis measurement of polarized fluorescence intensity components of the donor and acceptor of a FRET system. In addition to the FRET efficiency and the donor and acceptor concentrations, the method makes also possible the determination of the rotational characteristics and the associated fraction of the donors (FRET-fraction). The method is illustrated with flow cytometric and rFLIM measurements on donor-acceptor systems comprising fluorescently labeled whole antibodies and their Fab fragments against epitopes of the MHCI and MHCII cell surface receptors on human lymphoblast cells. Fluorescence anisotropy of donor and acceptor and FRET efficiency were measured for samples of different acceptor-to-donor concentration ratios. Acceptor anisotropy proved to be more sensitive than the donor anisotropy for sensing FRET. After determining the rotational constants of the donor-conjugated antibodies by measurements of FRET in the steady state, and by rFLIM as a reference, the associated fractions of the MHCI and MHCII molecules in their clusters were determined. Besides the flow cytometer and the wide-field rFLIM used in this study, the method can be applied also in other devices capable of dual-anisotropy detection.

Insertion/Deletion Polymorphism of Angiotensin-Converting Enzyme as a Risk Factor for Chronic Allograft Nephropathy

Angiotensin-converting enzyme (ACE) inhibitor therapy is widely used to treat chronic allograft nephropathy (CAN), which suggests a possible role of the renin-angiotensin system in the pathologic mechanism of the disease. The objective of this study was to investigate the possible link between CAN and ACE. The ACE insertion/deletion polymorphism and the amount and activity of ACE were determined in cadaver kidney recipients with CAN (n = 38) or normal renal function (n = 34). The DD genotype was observed significantly more frequently in the CAN group compared with the group with normal renal function. Moreover, the DD genotype was associated with a higher serum ACE concentration and greater serum ACE activity, compared with II genotype homozygotes. The insertion/deletion polymorphism of ACE affects ACE expression and activity in serum, and, therefore, may have an important role in the pathogenesis of CAN. These findings suggest that determination of the ACE genotype may be useful in identifying patients at high risk. In particular, the DD genotype may be considered an indication for ACE inhibitor therapy.

Noninvasive Perioperative Monitoring of Arterial Function in Patients With Kidney Transplantation

Development of atherosclerosis is accelerated in kidney transplant recipients. Impaired metabolic pathways have a complex effect on the arterial wall, which can be measured by noninvasive techniques. Few data are available on the change of stiffness parameters in the postoperative course, so in this study we analyzed the stiffness parameters of kidney transplant recipients during the perioperative period. Seventeen successful primary kidney transplant patients with uneventful postoperative period (7 woman, 10 men; 46.16 ± 12.19 years) were involved in our short-term prospective longitudinal study. We analyzed the correlation between noninvasively assessed stiffness parameters (pulse wave velocity [PWV], augmentation index [AIx], pulse pressure [PP], systolic area index, diastolic area index, diastolic reflection area), ankle-brachial index (ABI), and laboratory parameters (creatinine, glomerular filtration rate, urea, haemoglobin, C-reactive protein). Stiffness parameters were measured with a Tensiomed Arteriograph. These parameters were assessed before the transplantation, and 24 hours, and 1 and 2 weeks after surgery under standard conditions. We found that creatinine (P = .0008) and C-reactive protein (P = .006) serum levels decreased, and glomerular filtration rate increased significantly (P = .0005). We revealed that PWV (P = .0075) and AIx (P = .013) improved significantly. There was no significant change in ABI, PP, and the other monitored parameters. Along with the available data in the literature, our findings suggest that kidney transplantation has a positive effect on the arterial function.

A Single-center Experience of Allograft Nephrectomies Following Kidney Transplantation

INTRODUCTION Approximately 10% of renal allografts fail during the first year after kidney transplantation (KT) and 3%-5% thereafter yearly. The indication and timing of allograft nephrectomy (AN) is still uncertain in some cases. The aim of this study was to reveal the ratio, etiology, and complications of AN at our center. MATERIAL AND METHODS This is a retrospective study of all patients who underwent KT at our center between January 1, 2004 and December 31, 2014. We analysed the frequency, indications, timing, and complications of ANs. Also early and late ANs were compared. RESULTS From 417 renal transplantations 49 ANs were performed (11.7%). The most frequent indications were chronic allograft nephropathy (25; 51%), arterial blood supply complications, like arterial thrombosis and stenosis (7; 15%), treatment-resistant acute rejection (3; 6%), and nonreparable ureter complications (3; 6%). The average time of AN since KT was 28 months. ANs were performed as an urgent setting in 16 (33%) cases, whereas it was elective in 33 cases (67%). The AN was executed within 30 days (early) in 11 (22%) cases, and thereafter (late) in 38 (78%) cases. The main indication for early AN was renal artery thrombosis (4; 37%) and chronic allograft nephropathy (25; 66%) for late AN. Surgical complications occurred in 10 cases (20; 4%). The most common was hematoma. CONCLUSION The majority of the ANs were elective and late (more than 30 days; average time, 47 months). Leading indication was chronic allograft nephrectomy. Early ANs were urgent and life-saving in all cases.

Eredményeink a teljes jogú Eurotransplant-tagság óta. A Debreceni Vesetranszplantációs Központ tapasztalatai

Absztrakt Bevezetes: A Debreceni Egyetemen 1991-ben vegeztek el az első veseatultetest. Hazank 2013-ban csatlakozott az Eurotransplanthoz. Celkitűzes: A szerzők elemeztek a tapasztalatokat. Modszer: 2008. januar 1. es 2013. augusztus 31. kozott (A csoport = 163) es 2013. szeptember 1. es 2015. oktober 22. kozott vegzett cadavervese-atultetesek (B csoport = 90) adatait elemeztek. Eredmenyek: Az elődonorok aranya 3,5%-rol 9,1%-ra nőtt. 2013 ota a recipiensek 25%-a 60 evesnel idősebb, a >30 kg/m2 testtomegindex aranya 31%-ra, a diabetesesek aranya ketszeresere emelkedett. Az ureteroneocystostomia mellett bevezetesre kerult a veg az oldalhoz ureteroureteralis anastomosis. Indukcios kezeles mellett az akut rejectios epizod jelentősen csokkent (34%-rol 8%-ra). A technikai szovődmenyek aranya nem valtozott. A bakterialis fertőzesek aranya csokkent (41%-rol 33%-ra). Az 1, 3 es 5 eves veseallograft-tulelesek 86,6%, 85% es 82,7%, valamint 88%, 84% es 84% voltak a ket csoportban. Kovetkeztetesek: Az extended criteri...

Dual-laser homo-FRET on the cell surface

Inhomogeneous broadening and red-edge effects have been detected on a highly mobile system of fluorescently conjugated mAbs targeted to cell surface receptors. By exploiting site-selective spectroscopy and the characteristic loss of homo-FRET on increasing excitation and decreasing emission wavelengths, contributions of physical rotation and homo-FRET to the depolarization of fluorescence anisotropy have been separated. Absolute homo-FRET efficiency has been determined by ratioing two anisotropies: a homo-FRET-sensitive one, which is excited at the absorption main band and detected at the long wavelength region of emission, and a homo-FRET-insensitive one, which is excited at the long wavelength region of absorption and detected at the short wavelength region of emission. Because the anisotropies are simultaneously detected in a unified detection scheme of a dual T-format arrangement, the method is applicable for the real-time tracking of dynamical changes of physical rotations and proximities. The utility of the method is demonstrated in the context of the MHCII molecule and the heavy and light chains of the MHCI molecule, a system of three receptors with well-characterized close mutual proximities. Although the method is presented for a flow cytometer, it can also be realized in a fluorescence microscope capable for dual-laser excitation and dual-anisotropy detection.