Sylvie Dusilova Sulkova

Advanced Glycation End Products in Clinical Nephrology

As a result of oxidative and carbonyl stress, advanced glycation end products (AGEs) are involved in the pathogenesis of severe and frequent diseases and their fatal vascular/cardiovascular complications, i.e. diabetes mellitus and its complications (nephropathy, angiopathy, neuropathy and retinopathy, renal failure and uremic and dialysis-associated complications), atherosclerosis and dialysis-related amyloidosis, neurodegenerative diseases, and rheumatoid arthritis. They are formed via non-enzymatic glycation which is specifically enhanced through the presence of oxidative and carbonyl stress, and their ability to form glycoxidation products in peptide and protein structures finally modulating or inducing biological reactivity. Food can be another source of AGEs; however, high serum AGEs in hemodialysis patients might reflect nutritional status better. Several methods of renal replacement therapy have been studied in connection with the AGE removal, but unfortunately the possibilities are still unsatisfactory even if high flux dialysis, hemofiltration, or hemodiafiltration give better results than conventional low flux dialysis. AGEs are currently being studied in the patients on peritoneal dialysis as their precursors can be formed in the dialysis fluid. AGEs can cause damage to the peritoneum and so a loss of ultrafiltration capacity. Many compounds give promising results in AGE inhibition (inhibition of formation of AGEs, inhibition of their action or degradation of AGEs), are tested for these properties, and eventually undergo clinical studies (e.g. aminoguanidine, OPB-9195, pyridoxamine, antioxidants, N-phenacylthiazolium bromide, antihypertensive drugs, angiotensin-converting enzyme inhibitors and angiotensin II receptor-1 antagonists).

Age-related extracellular to total body water volume ratio (Ecv/TBW)--can it be used for "dry weight" determination in dialysis patients? Application of multifrequency bioimpedance measurement.

The article suggests a novel method for quantitative determination of optimal dry weight in dialysis patient based on their extracellular volume (ECV) to total body water (TBW) ratio and its relation to age. Values of ECV and TBW are evaluated by means of whole body multifrequency bioimpedometry. In an effort to find a suitable marker of hydration status in an individual from bioimpedance data, significant correlation has been found between ECV/TBW ratio and age in health. Assuming that all excess fluid in dialysis patients is stored exclusively in ECV and that distribution of their TBW at the state of optimal dry weight corresponds to that of a healthy person of the same age, the pre-dialysis ECV/TBW could be used for quantitative determination of optimal dry weight and/or of the ultrafiltration to reach this weight. Practical bioimpedance measurement of ECV/TBW in a group of dialysis patients both pre- and post-dialysis confirmed both above assumptions, i.e. nearly exclusively extracellular origin of ultrafiltration as well as normalisation of the ECV/TBW ratio towards the end of dialysis. Supporting evidence of increasing ECV/TBW value with age was also found in literature. Although the suggested method needs detailed analysis of possible disturbing factors (ethnic “specificity” of the reference ECV/TBW vs. age characteristics in health, possible difference in “biological” and “physical” age of dialysis patient and others), the article is published at this early stage to enable wider testing of the proposed novel method by different investigators.

Relationship of Pregnancy-Associated Plasma Protein-A to Renal Function and Dialysis Modalities

Background: The aim of the study was to determine pregnancy-associated plasma protein-A (PAPP-A), which was recently described as a new marker of cardiovascular events, in patients with chronic renal insufficiency/failure and to find out its relationship to renal function and to prominent markers of oxidative stress (advanced oxidation protein products – AOPP) and inflammation (C-reactive protein – CRP). Methods: The studied group consisted of 36 chronic hemodialysis patients (HD), 10 patients treated with continuous ambulatory peritoneal dialysis (CAPD) and 38 patients with chronic renal insufficiency (CHRI) not yet dialyzed. PAPP-A was measured by Time Resolved Amplified Cryptate Emission technology. Determination of AOPP is based on a spectrophotometric method. Results: PAPP-A levels are statistically significantly elevated in the both groups of dialyzed patients in comparison with healthy subjects (27.0 ± 16.5 mIU/l in HD and 14.07 ± 6.73 mIU/l in CAPD vs. 8.22 ± 2.7 mIU/l in the control group, p < 0.0001 and p < 0.001, respectively, p < 0.05 HD vs. CAPD). The mean serum PAPP-A levels in the CHRI patients not yet dialyzed were not significantly higher in comparison with the control group (9.72 ±4.44 vs. 8.22 ± 2.7 mIU/l, n.s.). In the CHRI not dialyzed patients, we found a significant positive correlation between serum creatinine and PAPP-A levels (r = 0.68, p < 0.05). In comparison with controls, AOPP and CRP levels were significantly higher in HD patients [AOPP 155.0 ± 37.9 µmol/l, p < 0.0001 vs. controls, CRP 10.0 (4.6– 26.9) mg/l (median, interquartile range), p < 0.0001 vs. controls], CAPD patients [AOPP 118.5 ± 25.8 µmol/l, p < 0.0001 vs. controls, CRP 7.7 (2.0–18.8) mg/l, p < 0.01 vs. controls] and AOPP levels in chronic renal failure patients not yet dialyzed (98.5 ± 43.24 µmol/l, p < 0.01 vs. controls). The correlations between PAPP-A and AOPP (r = 0.49, p < 0.05) and PAPP-A and CRP (r = 0.48, p < 0.05) serum concentration were statistically significant in HD patients. In CAPD patients, neither a correlation between PAPP-A and AOPP nor a correlation between PAPP-A and CRP were found. Conclusion: We can conclude that serum PAPP-A levels sensitively reflect the changes in renal function, depend on dialysis modality, and may represent a novel marker associated with inflammation and oxidative stress in chronic renal failure patients.

Comparison of different techniques of hemodialysis vascular access flow evaluation.

Measurement of vascular access flow (QVA) has been suggested as a method of choice for vascular access quality (VAQ) monitoring. Besides traditional duplex Doppler, a number of bedside methods based mostly on the Krivitski principle of QVA evaluation from recirculation at reversed needles (RX), have been developed. This work compares ultrasonic dilution (UD), taken as a reference, HD01, Transonic Systems; duplex Doppler (DD); thermodilution (TD), BTM, Fresenius; optodilutional RX measurement (ORX), Critline III, R-mode, HemaMetrics; direct optodilutional QVA evaluation from jumpwise changes in ultrafiltration rate at both normal and reversed needles connection (OABF), Critline III, ABF-mode; and direct transcutaneous optodilutional QVA evaluation (TQA), Critline III TQA. Firstly, reproducibility of each method was assessed by duplicate measurement at unchanged conditions. This was followed by paired measurement with each method performed at controlled change in relevant measurement condition (two different extracorporeal blood flows in UD and TD, changed sensor position in TQA). Finally paired measurements by each method and the reference method performed at identical conditions were evaluated to assess accuracy of each method. The simple Krivitski formula QVA= QB(1–RX)/RX was used wherever manual QVA calculation was needed. Very high reproducibility was seen in UD, both for measurement at the same extra corporeal blood flow (QB) (correlation coefficient of duplicate measurement r= 0.9702, n= 58) and for measurement at two different QB (r= 0.9735, n= 24), justifying its current status of a reference method in QVA evaluation. Slightly lower reproducibility of TD measurement at the same QB (r= 0.9197, n= 40) and at two different QB (r= 0.8508, n= 168) can be easily overcome by duplicate measurement with averaging. High correlation of TD vs. UD (r= 0.9543, n= 54) makes TD a viable clinical alternative in QVA evaluation. Consistently different QVA obtained at two different QB should prompt closer investigation of anatomical conditions of the access. Use of the simple Krivitski formula in TD (which measures total recirculation, i.e. sum of access recirculation and cardiopulmonary recirculation) brings about underestimation of QVA, which progressively increases from QVA of about 600 mL/min up. Good correlation, although with significant scatter (r= 0.8691, n= 27) was found between the DD-and UD-based QVA. By far the worst reproducibility at the same QB from among the investigated methods was found in ORX (0.6430, n= 23). Also the correlation of ORX vs. UD was lower than in other methods (r= 0.702, n=33) and general overestimation of QVA by about 25% was noted. Correlation of OABF vs. UD (r= 0.6957, n= 26) was slightly better than that of ORX and it gave less overestimated values. The TQA method showed very high reproducibility (r= 0.9712, n= 85), however only for unchanged sensor position. Correlation of QVA measured at two different sensor positions was much worse (r= 0.7255, n= 22). Correspondence of TQA vs. UD was satisfactory (r= 0.8077, n= 36). Skilled and experienced operators are a must with this method.

DENOSUMAB ASSOCIATED WITH BONE DENSITY INCREASE AND CLINICAL IMPROVEMENT IN A LONG-TERM HEMODIALYSIS PATIENT. CASE REPORT AND REVIEW OF THE LITERATURE

Denosumab is a human monoclonal antibody representing a novel therapy of osteoporosis. Contrary to always other antiosteoporotic drugs, it is not contraindicated in advanced chronic kidney disease, as its pharmacokinetic does not differ from patients with normal kidney function. However, published case reports in chronic kidney disease (CKD) patients stopped the therapy after single dose because of hypocalcemia. We present a case of successful treatment of osteoporosis in a young hemodialysis patient with repeated denosumab doses.

Advanced glycation end products in hemodialyzed patients with diabetes mellitus correlate with leptin and leptin/body fat ratio.

Advanced glycation end products (AGEs) and other carbonyl and oxidative stress compounds are supposed to play a critical role in the pathogenesis of several diseases and their complications, i.e., diabetes mellitus, diabetic retinopathy, atherosclerosis, and chronic renal failure. In the present investigation, we were interested in the relationship of AGEs in plasma to other prominent factors in the patients on chronic hemodialysis treatment—27 patients with diabetes mellitus, 35 patients without diabetes mellitus. AGE-group reactivity was estimated using a spectrofluorometric method (excitation 350 nm, emission 430 nm) and is expressed in arbitrary units (AU). We found significantly higher AGEs levels in diabetics than in non-diabetics on regular hemodialysis treatment both before (2.7 ± 0.7 × 104 AU vs. 2.2 ± 0.6 × 104 AU, p<0.001) and after the dialysis session (2.3 ± 0.5 × 104 AU vs. 1.8 ± 0.7 × 104 AU, p<0.005). AGEs were significantly reduced during hemodialysis in both groups of patients—by 15.4 % in the diabetic go (p<0.001) and by 17.3% in non-diabetics (p<0.005). In the patients with diabetes mellitus, AGEs did not correlate with parameters of the glucose metabolism correction (blood glucose, HbA1c). We observed a significant correlation between AGEs and leptin (r = 0.48, p < 0.05) as well as the leptin/body fat ratio (r = 0.56, p < 0.05) only in hemodialyzed patients with diabetes mellitus. These findings suggest more detailed studies to identify the molecular links between carbonyl stress, i.e., advanced glycation end products, and leptin metabolism, sign of microinflammation and hypertension.

Skin wounds associated with calciphylaxis in end-stage renal disease patients on dialysis

Calciphylaxis is a rare complication of chronic renal failure mostly with poor prognosis. Painful lesions on various skin surface areas are the most prominent feature of this serious disease. Subsequent infection of necrotic skin tissue is associated with the risk of sepsis. Pathophysiology is unclear, but several risk factors are known. The most important risk factor is impaired calcium-phosphate metabolism. Our paper describes two cases of different forms of calciphylaxis in patients with chronic renal failure. In the first case, pamidronate and cinacalcet were used for treatment. In the second described case, calciphylaxis was associated with secondary hyperparathyroidism and immediate subtotal parathyroidectomy was performed. Both patients were successfully treated, using systemic approach as well as dedicated local care for healing of skin wounds.

Evaluation of Skin Microcirculation during Hemodialysis

Background. Cardiovascular mortality in hemodialysis (HD) patients remains high despite improvements in HD technique such as dialysis adequacy, dialysis fluid purity, and membrane biocompatibility. Optimal fluid balance to maintain optimal hemodynamic stability during hemodialysis (HD) procedure is essential. At the present time, hemodynamic stability is conventionally assessed as stability of macrocirculation, especially as maintenance of systemic blood pressure with no attention paid to peripheral perfusion. Peripheral ischemic vascular disease represents a serious problem with high mortality and morbidity. We estimated skin microcirculation changes during HD using new device, Laser Doppler Line Scanner (Moor Instruments, Devon, UK). Aims. The aims were to introduce the novel method of detection of skin perfusion changes during hemodialysis and to evaluate possible relationship of these to ultrafiltration as well as to selected biochemical characteristics. Methods. In 36 hemodynamically stable patients, we performed paired measurements of skin blood flow in both hands before and during HD with registering the time of dialysis and the total ultrafiltration achieved. Results. We found a significant decrease in a majority of the evaluated areas. However, the skin blood flow change was not homogenous as it decreased more on the fingers. Conclusion. To our knowledge, this is the first study when the microcirculatory changes during hemodialysis are demonstrated and evaluated in large skin surface area, and showing not only a decrease in a majority of areas but also the heterogeneity of the changes.

Temperature and Thermal Balance Monitoring and Control in Dialysis

Temperature and thermal balance have been studied in an effort to explain better tolerance of ultrafiltration during isolated ultrafiltration and other convective techniques as compared to conventional hemodialysis. The large number of published studies has led to the conclusion that negative thermal balance of the extracorporeal circuit ameliorates hemodynamic stability by increased vasoreactivity and increased peripheral resistance. On the other hand, measurement of dialysis efficiency (urea removal) did not unequivocally confirm the theoretically predicted decrease in efficiency of “cool” dialysis. Another suggested application of temperature and thermal balance for assessing bioincompatibility is currently hampered by the ability of existing technology to evaluate thermal parameters of the extracorporeal circuit only. Publications on impact of negative thermal balance of the extracorporeal circuit on ultrafiltration‐induced changes in blood volume give contradictory results. Further studies are needed for elucidation of the impact of thermal balance on overall biological response to dialysis.

Changes of Serum Calcium, Magnesium and Parathyroid Hormone Induced by Hemodialysis with Citrate-Enriched Dialysis Solution

Background/Aims: In recent years, one of technical attempts to improve biocompatibility and tolerability of the hemodialysis procedure is the substitution of acetate in dialysis solution with citrate. The aim of our study was to compare two dialysis solutions: traditional bicarbonate dialysis solution containing acetate (3 mmol/L) (solution A); and (solution C) commercially produced citrate-enriched bicarbonate dialysis solution (0.8 mmol/L citrate). Methods: Patients from a single hemodialysis center (N=126) were included in the study. Both conventional low-flux hemodialysis and on-line hemodiafiltration procedures were studied. Both dialysis solutions contained identical calcium (1.5 mmol/L) and magnesium (0.5 mmol/L) concentrations. Results: Parathyroid hormone (iPTH) concentration decreased during procedures with solution A by 64%. On the contrary, when solution C was used, iPTH concentration increased insignificantly by 4%. For solution A, serum calcium and magnesium increased during procedures in patients with predialysis concentrations lower than 2.33 and 0.76 mmol/L, respectively. In procedures with dialysis solution C these concentrations were significantly lower: 2.19 mmol/L for Ca and 0.68 mmol/L for Mg. Conclusion: Our study clearly shows that the substitution of part of acetate with citrate in dialysis solution significantly influences changes of serum calcium, magnesium and parathyroid hormone concentrations during hemodialysis and hemodiafiltration procedures.