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Books: 234	Journals: 18	Articles: 21295

Abstract

Y. Fujimoto, M. Matsushima, K. Tsuzuki, M. Okada, M. Shibata, Y. Yanase, K. Usui and M. Nagashima

¹Department of Pediatrics and ²Pediatric Cardiology, Chukyo Hospital, Nagoya, and ³Aichi Children?s Health and Medical Center, Obu, Japan
Aims: Nephropathy has long been recognized as a potential complication of cyanotic congenital heart disease (CCHD). There have been few large-scale studies or clinical reports on renal impairment in patients with CCHD; similarly, very few studies have examined the drug treatment of nephropathy in CCHD. We examined the clinical characteristics and effectiveness of enalapril, an angiotensin-converting enzyme inhibitor (ACE-I), in patients with CCHD complicated with significant proteinuria. Materials and methods: The clinical records of 37 patients with CCHD were evaluated; all were older than 10 years of age (median 19, range from 10 to 27) and had regular check-ups, including urinalysis. The treatment criteria for enalapril administration included significant proteinuria (urinary excretion > 1.0 g/24 h), stable cardiac condition and blood pressure within the normal range. Results: Eleven patients (29.7%) had persistent proteinuria, 6 patients met the enalapril treatment criteria and 5 patients were treated for more than 12 months. Enalapril apparently reduced the urinary protein excretion in 4 of the 5 patients (80%). No consistent improvement of renal function, as evidenced in the glomerular filtration rate (GFR), renal plasma flow (RPF) or filtration fraction (FF) was found in these patients, but neither were any significant adverse effects noted. Conclusion: The incidence of nephropathy among patients with CCHD was about 30%, which was consistent with previous studies. It is worth considering the use of ACE-I when nephropathy accompanies CCHD.

Abstract

L. Calò¹, B. Giacon², P.A. Davis³, E. Pagnin¹, A. Piccin¹, P. Riegler², W. Huber², A. Antonello⁴ and A. Semplicini¹

¹Department of Clinical and Experimental Medicine, Clinica Medica ⁴ and ²Nephrology, University of Padua, ³Department of Internal Medicine, University of California, Davis, USA, and ⁴Division of Nephrology Bolzano Hospital, Italy
Cyclosporin is a powerful stimulator of oxidative stress signaling, leading to TGFb production, NO degradation, endothelial dysfunction, hypertension and post-transplant nephropathy. Carvedilol, a1-b-blocker with strong antioxidant activity, may interfere with this chain of events. Therefore, we measured monocyte ecNOS, TGFb and heme oxygenase-1 (HO-1) mRNA level and plasma nitrite/nitrate, 3-nitrotyrosine, an estimate of peroxynitrite, and total plasma antioxidant power in kidney-transplanted patients with post-transplant hypertension, before and after treatment with carvedilol, 25 – 50 mg o.d. orally for 4 months (n = 15). The dihydropyridine calcium channel blocker nifedipine (n = 10) was used as comparator antihypertensive drug. Blood pressure fell to a similar extent with both drugs. Carvedilol increased plasma antioxidant power and HO-1 mRNA and reduced 3-nitrotyrosine and TGFb mRNA levels, while the same was not observed with nifedipine. Monocyte ec NOS mRNA levels and plasma nitrite/nitrate were higher in the patients than in a normotensive healthy control group and were unaffected by either treatment. In conclusion, carvedilol reduces the oxidative stress and corrects the altered cellular signaling mediated by oxidative stress in CsA-induced post-transplant hypertension. Therefore, it may prevent long-term complications, such as endothelial dysfunction, fibrogenesis and post-transplant nephropathy by decreasing NO degradation and production of TGFb, a key fibrogenic cytokine, and by activating HO-1 production.

Abstract

M. Cohnen¹, M. Brause², P. May¹, G. Hetzel², A. Saleh¹, B. Grabensee² and U. Mödder¹

¹Institute of Diagnostic Radiology, and ²Department of Nephrology, Düsseldorf, Germany MR urography in renal transplantation
Aim: The diagnostic work-up of renal transplants with impaired function due to urological problems can be difficult. This study was performed to assess sensitivity and specificity of non-invasive contrast-enhanced MR urography (MRU). Methods and materials: Thirty-five patients with renal transplants (25 – 71 years, mean: 53.4 years) with sonographically diagnosed hydronephrosis or perirenal fluid collections were assessed by MR urography. MR examinations were carried out at a 1.5 T clinical scanner (Vision, Siemens, Erlangen, Germany) with a 512 matrix contrast-enhanced fat-suppressed T1-weighted FLASH 3D sequence in breath-hold technique. MIP reconstructions were used to produce MR urography. MRU diagnoses were compared to operative results. Results: In all patients, images with sufficient contrast in the renal collecting system were obtained. Hydronephrosis was confirmed in 20 patients, 8 patients showed a different pathology while 7 had normal findings. Compared to operative results, sensitivity of MRU was 100% with a specificity of 78%, respectively. One ureteral stone was misdiagnosed as a stricture, and 2 suspected ureteral stenoses could not be found upon operation. Conclusions: Contrast-enhanced MR urography is a highly sensitive and specific non-invasive method to evaluate patients suspected of having typical post-transplant urological complications. It may replace invasive procedures such as antegrade pyelography in the pre-operative work-up.

Abstract

M.K. Shah

Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital/Harvard Medical School, Boston, MA, USA
Aims: Simultaneous bilateral quadriceps tendon rupture occurs in patients with renal disease. It has been hypothesized that the length of renal disease and the length of dialysis may correlate with the development of tendon ruptures. This study aims to characterize the factors involved in patients with renal disease and simultaneous bilateral quadriceps tendon rupture. Methods: All reported cases of simultaneous bilateral quadriceps tendon rupture were identified using MEDLINE. Each case was reviewed for information regarding this injury. Results: Of the 65 cases reviewed, 24 cases involved patients with renal disease. Males were more often affected than females, almost a 2 : 1 ratio. The mean age of injury was 36 years. Most patients (63%) had signs of secondary hyperparathyroidism. The average length of renal disease was 13 years while the average length on dialysis was 6.5 years. Age, gender, mechanism of injury, time before diagnosis, location of rupture, method of repair, presence of hyperparathyroidism, length of renal disease or length on dialysis were not related to functional outcome. However, length on dialysis was related to mechanism of injury. Conclusions: Most patients with renal disease and simultaneous bilateral quadriceps tendon rupture have good functional recovery. Duration of dialysis is related to spontaneous tendon rupture and should be considered a complication of chronic renal failure.

Abstract

K.S. Brimble, Ch.G. Rabbat, D.J. Treleaven and A.J. Ingram

Department of Medicine, McMaster University, Hamilton, Ontario, Canada
Aim: The purpose of this study was to evaluate the clinical utility of Doppler ultrasound (US) prior to native forearm arteriovenous fistula (AVF) creation. Materials and methods: US mapping was carried out pre-operatively to evaluate the major veins and arteries in the appropriate arm. One hundred and 6 patients were identified retrospectively over 2 years with complete clinical and US data. A failed fistula was defined as an inability to provide blood flow to meet adequacy targets by 6 months (urea reduction ratio ³ 65%). Results: Twenty-nine patients (27.4%) had successful forearm AVFs. The mean minimum forearm cephalic vein diameter (CVD) was 2.51 ± 0.14 and 2.23 ± 0.06 mm in successful and failed fistulae, respectively (p = 0.04). This result was primarily due to differences observed in women. A receiver operator curve analysis showed that a cutpoint of 2.6 mm for minimum forearm CVD had the greatest predictive value with a likelihood ratio of 3.94 (95% CI: 1.97 – 7.84) for fistula failure. Multivariate logistic regression analysis determined that male gender and minimum forearm CVD were the only significant predictors for fistula success with odds ratios of 3.90 (95% CI: 1.30 – 11.68) and 2.31 (95% CI: 1.00 – 5.43), respectively. The study is limited by the possibility that US results in patients may have lead to an alternative type of access being attempted. Conclusions: US mapping prior to forearm AVF creation is of modest benefit. Only male gender and minimum forearm CVD were predictive of AVF success.

Abstract

A. Webb, M. Abdalla, P.N. Harden and G.I. Russell

St. Lukes Hospital, Bradford, UK The Tesio catheter system for hemodialysis access
Background: The Tesio catheter system has been proposed to be a reliable source of vascular access for the dialysis patient with low rates of infection and other complications. Whether such catheters provide reliable short- and long-term access remains undetermined. Methods: This study prospectively examined all Tesio lines inserted over a 2-year period in patients with end-stage failure with careful recording of all catheter complications and reasons for catheter loss. Results: 100 catheters were inserted in 82 patients giving a total experience of 13,749 catheter days; 74 catheters were inserted into the jugular veins, the remainder into the femoral veins; 82 insertions were covered with antibiotics. At the end of the study, 29 catheters remained in situ. Of the remaining 71 catheters, 27 catheters were removed because of fashioning of definitive access. Nine catheters were lost due to infection and 10 were lost due to non-function; 19 patients died with a functioning catheter. Episodes of non-function were the major complications, although catheter patency was restored in 90% of cases utilizing urokinase and warfarin. Overall 80% of femoral and 16% of jugular catheters required anticoagulation. Conclusions: Tesio catheters inserted into the jugular or femoral veins can provide excellent access whilst awaiting definitive dialysis access. They are well-tolerated with a low complication rate compared to standard temporary central venous catheters. Non-function remains a significant problem, especially in femoral catheters, which should be anti-coagulated following insertion. Because of our results we suggest that these catheters be used as part of the co-ordinated approach to the management of vascular access in end-stage renal failure patients without definitive access.

Abstract

D. Guo, B.L. Jaber, S. Lee, M.C. Perianayagam, A.J. King, B.J.G. Pereira and V.S. Balakrishnan

Division of Nephrology, Department of Medicine, New England Medical Center Hospitals, Boston, MA, USA
Background: Polymorphonuclear cell (PMN) dysfunction and the increased use of parenteral iron may be important contributory factors to bacterial infections among patients with end-stage renal disease (ESRD) on maintenance hemodialysis (HD). We compared the in vitro impact of a commonly used parenteral iron preparation, iron dextran, on PMN function and viability between a group of HD patients with normal iron indices and healthy subjects. Methods: Eleven patients with ESRD on HD and 10 healthy subjects were studied. PMN harvested from heparinized blood were incubated with iron dextran (0 – 20 mM) in culture medium (RPMI) for 24 hours at 37 °C with 5% CO2 following which function and viability were assessed by flow cytometry using appropriate fluorescent labels. Results: Unstimulated, S. aureus and N-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated hydrogen peroxide (H2O2) production was significantly higher in PMN unexposed to iron dextran from HD patients compared to those from healthy subjects. Iron dextran had no impact on unstimulated PMN H2O2 production in either group. In the healthy group, the only significant change occurred with 4-b-phorbol 12-b-myristate 13-a-acetate (PMA) stimulation, where cells exposed to 0.2 and 2.0 mM iron dextran produced less H2O2 relative to PMN unexposed to iron dextran (p < 0.05). In the HD group, all concentrations of iron dextran significantly attenuated H2O2 production stimulated by S. aureus, fMLP and PMA compared to PMN unexposed to iron dextran. Although PMN phagocytosis decreased with exposure to increasing concentration of iron dextran in both healthy subjects and HD patients, these changes did not achieve statistical significance. No significant changes in PMN viability or apoptosis were seen in either group after exposure to iron dextran. Conclusions: These results indicate that iron dextran, a standard parenteral iron preparation, attenuates PMN function in HD patients with normal iron indices at clinically relevant concentrations. Further studies are required to evaluate and compare the impact of newer preparations of parenteral iron, such as iron sucrose and ferric gluconate, on PMN function.

Abstract

M. Espinosa, A. Martin-Malo, M.A. Alvarez de Lara, R. Gonzalez, M. Rodriguez and P. Aljama

¹Servicios de Nefrologia and ²Immunologia, Hospital Universitario Reina Sofia, Cordoba, Spain Acute hepatitis C in HD patients
Aims: Chronic liver disease develops in the majority of non-uremic patients with hepatitis C virus (HCV) infection. The aim of this study was to analyze the evolution towards chronic hepatopathy in 19 cases of acute hepatitis C observed in hemodialysis patients from 1990 to 2001. Methods: A prospective follow-up study on HCV infection was conducted in 3 HD units from April 1990 to June 2001 to study clinical outcomes after acute hepatitis C. A total of 781 patients were tested monthly for alanine aminotransferase and anti-HCV in serum. In this period, 19 patients suffered from acute hepatitis C. Evolution to chronic liver disease in the follow-up was evaluated by means of biochemical (increased ALT) and virological criteria (HCV-RNA+). The transmission mechanism, the apparition of anti-HCV, clinical manifestations and mortality were also investigated. Results: In 15 (78.9%) of the 19 patients, the viremia remained positive (chronic viremia) and 11 patients (57.8%) evolved to chronic liver disease (chronic viremia and high transaminase levels) with a median follow-up of 3 years (range 1 – 6). Five of them who underwent liver biopsies had histologic signs of chronic active hepatitis. One of them (5.2%) evolved to liver cirrhosis in the follow-up. In 4 out of 19 patients (21%) the HCV infection resolved. Although 7 (36.8%) of them died in the follow-up, acute hepatitis C infection was not a short-term independent risk factor of death. Conclusions: Three years after acute hepatitis C, 87.5% of the hemodialysis patients remained HCV-RNA positive and 56.2% evolved to chronic liver disease. It is important to stress that HCV infection spontaneously cleared in 4 out of 19 patients (21%).

Abstract

N. Verma, S. Arunabh, T.M. Brady and C. Charytan

¹Department of Internal Medicine & Nephrology, The New York Hospital Medical Center of Queens, Flushing, NY, and ²Department of Endocrinology, Winthrop-University Hospital, Mineola, NY, USA
Renal involvement in infectious mononucleosis (IM) is infrequent. In most cases it is self-limited and is rarely associated with loss of renal function. The purpose of this case report is to document a case of acute interstitial nephritis (AIN) leading to acute renal failure (ARF) in a patient with Epstein-Barr virus (EBV) infection and to review literature of EBV infection and its renal manifestation. The patient was managed with hemodialysis and steroids and made an uneventful recovery. Renal involvement in IM may be more common than generally appreciated and may occasionally lead to ARF. Therapy with corticosteroids may have role in the management of IM-induced ARF and may shorten the duration of renal failure.

Abstract

S.M. Sprague and L.T. Ho

Department of Medicine, Evanston Northwestern Healthcare, Northwestern University Medical School, Evanston, Illinois, USA
Control of hyperphosphatemia and the administration of vitamin D are the primary treatment modalities for the prevention and management of secondary hyperparathyroidism. Vitamin D therapy for secondary hyperparathyroidism has been limited by the development of hypercalcemia and/or hyperphosphatemia due to increased intestinal absorption of these minerals. Recently, selective vitamin D analogs specifically designed to suppress parathyroid hormone (PTH) without causing hypercalcemia or hyperphosphatemia have shown promise for the treatment of secondary hyperparathyroidism in uremia. This case report describes the successful use of doxercalciferol to treat severe secondary hyperparathyroidism in an adult male patient undergoing chronic peritoneal dialysis, with a follow-up period of 9 months. During this period, the patient?s hyperparathyroidism was rapidly and easily controlled. Treatment was complicated by a single incident of over suppression of PTH, with concomitant hypercalcemia. This quickly resolved upon temporary discontinuation of doxercalciferol therapy, after which therapy was resumed without further incident.

Abstract

N. Sano, K. Kitazawa, D. Totsuka,K. Kobayashi, H. Honda, Y. Makino,T. Shibata and T. Sugisaki

Department of Nephrology, Showa University, Shinagawa-ku, Tokyo
A 47-year-old Japanese woman with both Takayasu’s arteritis (TA) and systemic lupus erythematosus (SLE) presented with unequal pulses in the upper extremities, diarrhea and proteinuria. In 1986, when she was 38 years old, angiography revealed stenosis of the left subclavian artery. In 1994, SLE was diagnosed on the basis of clinical and laboratory findings, including renal dysfunction, hematologic and immunologic abnormalities, a high titer of antinuclear antibody and a positive lupus band test on the skin. Renal biopsy showed lupus nephritis and glomerular lesions with a bubble-like appearance of the glomerular capillary wall with TA. Lupus nephritis coexisting with glomerulonephropathy associated with TA has rarely been reported.

Abstract

G. Wong, S.A. Jayawardene and N. Velasco

Abstract

T. Okada, T. Nakao, H. Matsumoto, Y. Nagaoka, H. Iwasawa, K. Nanri and T. Yamazaki

Abstract

V. Wirta¹, P. Saransaari⁴, O. Wirta², V. Rantalaiho², S.S. Oja³, A. Pasternack², T. Koivula¹ and T. Lehtimäki¹

¹Laboratory of Atherosclerosis Genetics, Department of Clinical Chemistry, Centre for Laboratory Medicine, ²Department of Internal Medicine, ³Department of Clinical Physiology, Tampere University Hospital, and ⁴Medical School, University of Tampere, Finland
Background: Methylenetetrahydrofolate reductase (MTHFR) gene polymorphism may cause hyperhomocysteinemia, which affects the vascular endothelium and may induce occlusive vascular disease (OVD). Hypertension thickens small-sized arterial walls and attenuates intramural blood flow. Such OVD can be studied in retinal angiograms as a decrease in the arterio-venous ratio (AVR). Diabetes, by altering microvascular structure and function, in many ways modifies this AVR. Objective: To assess whether MTHFR gene polymorphism (C677T) by causing hyperhomocysteinemia affects the retinal AVR in type 2 diabetic and non-diabetic subjects. Methods: Eighty-four recently diagnosed (< 1 year) type 2 diabetic and 115 non-diabetic subjects were included in the study. Retinal fluoresceine angiograms were recorded and the mean AVR was calculated by measuring transverse vessel diameters at 6 locations. The mean AVR was used as a marker of OVD. The MTHFR VV, VA and AA genotypes were determined by PCR and plasma homocysteine by high-pressure liquid chromatography. Results: In the diabetic subjects with the VV, VA and AA genotypes, the plasma homocysteine levels were 16.5 ± 7, 12.5 ± 4.6 and 11.3 ± 4.9 mM, respectively (p = 0.008, ANCOVA). The corresponding values in controls were 14.6 ± 3.8, 13.7 ± 5.7 and 11.6 ± 4.4 (p = 0.08). Correspondingly, in the diabetic subjects, the AVR values were 0.71 ± 0.07, 0.75 ± 0.07 and 0.73 ± 0.1 (p = NS, ANOVA) and in the control subjects they were 0.8 ± 0.14, 0.81 ± 0.12 and 0.76 ± 0.09 (p = NS, ANOVA). Multiple linear regression analysis (best model c2 = 18.2, R2 = 0.10, p < 0.001) showed that AVR was related to diastolic blood pressure (t = –3.7, p < 0.001) and GFR (t = –2.2, p = 0.03). There was no relation between the AVR and plasma homocysteine levels. Conclusion: In the present study of recently diagnosed type 2 diabetic and non-diabetic subjects, MTHFR gene polymorphism (C677T mutation) slightly affected the plasma homocysteine level but did not alter the arterio-venous ratio.

Abstract

M. Andrassy¹,³, A. Bierhaus¹,³, M. Hong¹,³, J. Sis², S. Schiekofer¹,³, P.M. Humpert¹,³, J. Chen¹,³, M. Haap³, W. Renn³, E. Schleicher³, H.-U. Häring³, K. Andrassy² and P.P. Nawroth¹,³

¹Department of Medicine IV, University of Tübingen, ²Department of Nephrology, and ³Department of Medicine I, University of Heidelberg, Germany
The aim of this study was to determine the effect of rh-EPO on the redox-sensitive transcription factor (NF-kB) in vivo and in vitro. Ten patients (7 female, 3 male), mean age 69.2 ± 11 years, with end-stage renal failure and anemia prior to initiation of regular hemodialysis were enrolled and divided into 2 groups (group A “good responder”, 7 patients and group B “poor responder”, 3 patients) in accordance to the response to rh-EPO therapy. Nuclear binding activity of NF-kB was determined in ex vivo isolated mononuclear cells before, 4 and 8 weeks after onset of regular hemodialysis and rh-EPO therapy by electrophoretic mobility shift assays (EMSA). In group A, a reduction of NF-kB binding activity from 100% to 56 ± 6% was observed within the first four weeks of rh-EPO treatment, while mean hemoglobin rose from 8.2 ± 0.4 g/dl to 11.1 ± 0.2 g/dl. However, this effect was abrogated after another 4 weeks of treatment when NF-kB signal increased back to 85.2 ± 10.6% despite consistent mean hemoglobin level of 11.3 ± 0.4 g/dl. Group B demonstrated a slight increase of NF-kB signal from 100% to 129 ± 18.5%, while mean hemoglobin only moderately rose from 7.6 ± 0.3 g/dl to 8.3 ± 0.1 g/dl within the first 4 weeks, and it further rose to 180 ± 45% after 8 weeks of treatment, while mean hemoglobin (9.5 ± 0.1 g/dl) remained low. The NF-kB binding activity differed significantly when comparing both groups (p = 0.007). Binding activity of Oct-1, serving as control, did not change notably in either group (p = 0.34). In vitro studies showed that rh-EPO did not directly affect NF-kB binding activity in THP-1 cells. However, coincubation of THP-1 cells with erythrocytes led to a reduction of NF-kB binding activity only in THP-1 cells with a hemoglobin level adjusted to 11 g/dl compared to 8 g/dl in the presence of rh-EPO. In vivo and in vitro data implicate a complex interaction between rh-EPO, stimulated RBC and the redox-sensitive transcription factor NF-kB in mononuclear cells.

Abstract

T.A. Ikizler, J.D. Morrow, L.J. Roberts, J.A. Evanson, B. Becker, R.M. Hakim, Y. Shyr, J. Himmelfarb

¹Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA, ²Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA, ³Department of Medicine, Division of Nephrology, University of Wisconsin Medical School, Madison, Wisconsin, USA, ⁴Department of Preventative Medicine, Division of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee, USA, and ⁵Department of Medicine, Division of Nephrology, Maine Medical Center, Portland, Maine, USA
Aims: Cardiovascular mortality has been reported to be 10- to 20-fold higher in chronic dialysis patients than in the age-matched general population. It has been suggested that increased oxidant stress and resulting vascular wall injury due to uremia and the hemodialysis procedure may be one of the mechanisms predisposing to these cardiovascular complications. Further, hemodialysis membrane bioincompatibility can contribute to increased oxidative stress and prevalence of inflammation. Materials: We studied 18 chronic hemodialysis (CHD) patients (age 62.8 ± 14.7 years, 39% male, 61% African-American, 44% insulin-dependent diabetic, 61% smokers, 61% with documented coronary artery disease) during hemodialysis with 2 membranes with different flux and complement activating properties. Methods: We have measured free and phospholipid-bound F2-isoprostane (F2-IsoP) levels, a sensitive marker of oxidative stress, in CHD patients and compared them to levels in healthy subjects. We have also examined the acute effects of the hemodialysis procedure using both biocompatible and bioincompatible membranes on F2-IsoP levels. Results: The results indicated that, compared to controls, both free (96.2 ± 48.8 pg/ml versus 37.6 ± 17.2 pg/ml) and bound F2-IsoP (220.4 ± 154.8 pg/ml versus 146.8 ± 58.4 pg/ml) levels were significantly higher (p < 0.05 for both). There was a statistically significant decrease in free F2-IsoP concentrations at 15 and 30 minutes of HD, which rebounded to baseline levels at the completion of the procedure. There were no significant differences in F2-IsoP concentrations between the 2 study dialyzers at any time point. Age, smoking status, diabetes mellitus and presence of cardiovascular disease were also not correlated with F2-IsoP levels in this patient population. There was a significant association between predialysis F2-IsoP and C-reactive protein concentrations. Conclusion: Using a sensitive and specific assay for the measurement of F2-IsoP, we demonstrated that CHD patients are under increased oxidative stress. During a single hemodialysis treatment, the hemodialysis membrane appears to have no discernable effect on oxidative stress status. Measurement of F2-isoprostanes may be a useful biomarker of oxidative stress status as well as in developing new therapeutic strategies to ameliorate inflammatory and oxidative injury in this patient population.

Abstract

G. Stoya, A. Klemm, E. Baumann, H. Vogelsang, U. Ott, W. Linss and G. Stein

¹Department of Internal Medicine IV, ²Institute of Anatomy I, and ³Institute of Immunology, Friedrich Schiller University, Jena, Germany
Aim: It is suggested that the red blood cells (RBCs) of uremic patients have increased oxidative damage. The activities of different antioxidant enzymes and the levels of several antioxidants or lipid peroxidation products in RBCs are usually determined to estimate the oxidative stress in uremia. The autofluorescence of RBCs as measured by flow cytometry is caused by the formation of conjugated Schiff base compounds from aldehydes derived from lipid peroxidation and amino groups of phospholipids or cell proteins, and has been proposed as a marker of oxidative stress. The aim of this study was to evaluate if this method is suitable for estimation of oxidative stress in the RBCs of patients with different degrees of renal insufficiency. Patients and methods: To determine the oxidative damage in RBCs in uremia, the autofluorescence of RBCs was measured by flow cytometry in the following 3 groups of patients: group A: 16 patients with chronic renal failure (CRF); group B: 16 hemodialysis (HD) patients; group C: 16 patients with a well-functioning renal allograft. Twenty-four healthy volunteers served as controls. The basal value of RBC autofluorescence and the autofluorescence of RBCs after oxidative damage by treatment with 0.1 mM hydrogen peroxide (H2O2)/0.7 mM sodium azide were determined. Results: In basal RBC autofluorescence values, no differences were found between the 3 groups and the controls. However, there was a significant correlation between the increase of serum creatinine and RBC autofluorescence in the group of patients with CRF (r = 0.521; p = 0.038). After H2O2 treatment, the RBC autofluorescence rose markedly in all individuals. This increase in RBC autofluorescence was significantly higher in the patients with CRF (p = 0.003) and in the HD patients (p = 0.001) compared to the controls. In contrast, there was no difference in RBC autofluorescence between the patients with renal allograft and the controls after H2O2 treatment. Conclusions: In conclusion, flow cytometry is a useful tool for determining oxidative damage in RBCs. The RBCs of uremic patients are more susceptible to oxidative damage induced by H2O2, likely caused by diminished antioxidant defense in the RBC membrane. Successful renal transplantation leads to a normal autofluorescence response in the RBCs after H2O2 treatment.

Abstract

K. Dewitte¹, A. Dhondt², N. Lameire², D. Stöckl¹ and L.M. Thienpont¹

¹Laboratory for Analytical Chemistry, Faculty of Pharmaceutical Sciences, Ghent University, and ²Renal Division, University Hospital, Ghent, Belgium
Aim of the study: Based on data in the literature, it remains unclear whether the ionized fraction of serum total magnesium (Mg) is lower in chronic hemodialysis (HD) patients compared to healthy subjects. Patients and methods: The ionized fraction of serum total Mg was investigated in 49 HD patients, pre- and post-dialysis, and compared to 30 healthy controls. The quality of the analytical performance of the Mg measurements has been emphasized by applying a reference method and/or rigorous internal quality control (IQC). In addition, the ionized fraction of serum total calcium (Ca) was measured in both populations, because the results for Mg should be related to those of Ca. Results: In HD patients, the ionized fraction of serum total Mg was on average 65% (pre-dialysis 64.2% and post-dialysis 66.2%). In healthy controls, the ionized fraction was 64.9%. When the analytical variability was taken into account, no significant differences (p > 0.05) were observed between pre- and post-dialysis samples and controls. For Ca, an ionized fraction of 55.3% was found in HD patients, which was not significantly different from the fraction obtained in the control group (55.7%). Conclusion: The present study demonstrates that, compared to healthy controls, the ionized fraction of serum total Mg is not different in hemodialysis patients.

Abstract

J.A. Vassalotti, A. Falk, E.D. Cohl, J. Uribarri and V. Teodorescu

¹Division of Nephrology, Mount Sinai Medical Center, New York, USA ²Division of Radiology, Mount Sinai Medical Center, New York, USA and ³Division of Surgery, Mount Sinai Medical Center, New York, USA
Aims: The arteriovenous fistula (AVF) is the preferred hemodialysis access. Subset analyses of both the HEMO and DOPPS studies have shown that obese hemodialysis patients have a lower prevalence of functioning AVF. Doppler ultrasound may increase the prevalence of functioning AVF in obese subjects. Patients and methods: The effect of pre-operative vein mapping employed between 10/01/98 and 12/08/00 on the prevalence of functioning AVF in a single university hemodialysis program was studied. Pre-operative ultrasound was performed to study venous and arterial systems on both arms. Results: There were 50 obese patients, defined as body mass index (BMI) ³ 27 kg/m2, and 130 patients with a lower BMI. The groups were similar in mean age and diabetes prevalence. The obese group had statistically significantly more females 34/50 versus 61/130 with p = 0.01. There was no statistically significant difference between the vein mapping parameters studied in the two BMI groups, including mean mid-forearm cephalic vein diameter, distal radial artery peak systolic velocity and subclavian vein patency. No obese patient required venography. There was no significant difference between the number of functioning AVF in both groups (22/50 obese, 48/130 lower BMI, p = 0.24). Conclusions: Pre-operative vein mapping is associated with a similar prevalence of functioning AVF in obese and lower BMI patients. Pre-operative ultrasound screening is a useful tool to promote AVF placement in obese patients.

Abstract

N. Kimata, K. Nitta, T. Akiba,K. Tominaga, K. Suzuki, Y. Watanabe, T. Haga, A. Kawashima, N. Miwa, E. Nishida, T. Aoki and H. Nihei

¹Department of Medicine and ²Division of Blood Purification, Kidney Center, Tokyo Women’s Medical University, Tokyo, and ³Dialysis Center, Takeda General Hospital, Fukushima, Japan
Objective: Intraluminal thrombosis of the catheter was thought to be a major cause of catheter dysfunction. We evaluated if thrombi appear in the luminal side or outside of the catheters placed in the femoral vein in 21 hemodialysis patients. Methods: 23 double-lumen catheter (25 cm long and 4 mm diameter polyurethane) strippings were consecutively performed. Mean catheter dwell time was 17.9 ± 11.2 days (2 – 45 days). The femoral vein was observed with ultrasound echography, and thrombo-venous ratio (thrombus diameter/vein diameter) was calculated. X-rays were also taken to clearly visualize the thrombi followed by contrast medium injection through the catheter. Results: Tube-shaped thrombi were echographically detected in 22 of 23 catheters (95.7%) when the catheter was stripped. Ten catheters (43.5%) were stripped due to the reduced blood flow, and tube-shaped thrombi were observed in the femoral vein, whereas no thrombus was found in the intraluminal side of the catheter. In 7 of 23 patients (30.4%) with leg edema on the same side of the catheter, the thrombo-venous ratio was 78.9 ± 7.4%, which was higher than that in the patients without leg edema (52.1 ± 11.1%). Conclusion: The tube-shaped thrombi, formed around the double-lumen catheter, may cause catheter dysfunction and reduced venous return of the lower legs. The catheter should be removed as soon as thrombosis is diagnosed, especially when accompanied by leg edema.

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