Prognostic value of Balkan endemic nephropathy and gender on upper tract urothelial carcinoma outcomes after radical nephroureterectomy: A cohort study.

BACKGROUND: To identify the prognostic impact of residence in a BEN-endemic area and gender on upper tract urothelial carcinoma (UTUC) outcomes in Serbian patients treated with radical nephroureterectomy (RNU). METHODS: The study included 334 consecutive patients with UTUC. Patients with permanent residence in Balkan endemic nephropathy (BEN) or non-endemic areas from their birth to the end of follow-up were included in the analysis. Cox regression analyses were used to address recurrence-free (RFS) and cancer-specific survival (CSS) estimates. RESULTS: Female patients were more likely to have preoperative pyuria (P = 0.01), tumor multifocality was significantly associated with the female gender (P = 0.003). Gender was not associated with pathologic stage and grade, lymph node metastasis, lymphovascular invasion, adjuvant chemotherapy, bladder cancer history, tumor size, distribution of tumor location, preoperative anemia and demographic characteristics. A total of 107 cases recurred, with a median time to bladder recurrence of 24.5 months. History of bladder tumor (HR, 1.98; P = 0.005), tumor multifocality (HR, 3.80; P < 0.001) and residence in a BEN-endemic area (HR, 1.81; P = 0.01) were independently associated with bladder cancer recurrence. The 5-year bladder cancer RFS for the patients from areas of BEN was 77.8 % and for the patients from non-BEN areas was 64.7 %. The 5-year CSS for the men was 66.2% when compared to 66.6% for the women (P = 0.55). CONCLUSIONS: Residence in a BEN-endemic area represents an independent predictor of bladder cancer recurrence in patients who underwent RNU. Gender cannot be used to predict outcomes in a single-centre series of consecutive patients who were treated with RNU for UTUC.

Association of SOD2 (rs4880) and GPX1 (rs1050450) Gene Polymorphisms with Risk of Balkan Endemic Nephropathy and its Related Tumors.

Background: Experimental data show that superoxide dismutase 2 (SOD2) is involved in ochratoxin (OTA)-induced nephrotoxicity, whereas clinical data indicate the role of SOD2 rs4880 or glutathione peroxidase 1 (GPX1) rs1050450 polymorphisms in end-stage renal disease and urothelial carcinoma risk, known to be the major complications of Balkan endemic nephropathy (BEN). Therefore, we hypothesized that SOD2 and GPX1 gene polymorphisms would influence the risk of BEN and its associated tumors. Materials and Methods: The study was conducted in 207 BEN patients and 86 controls from endemic areas. Results: Individuals with both copies of variant SOD2 allele, known for lower mitochondrial antioxidant protection, are at a significantly higher BEN risk (OR = 2.6, p = 0.021). No association was observed between GPX1 gene polymorphism and BEN risk. Combining SOD2 and GPX1 genotypes did not alter the risk of BEN development. Regarding the risk of urothelial tumors in BEN patients, none of the polymorphisms studied was significantly associated with the risk of these tumors. Conclusions: Polymorphism in SOD2 rs4880 gene affects the risk of BEN development. Hence, SOD2 genotyping could, together with a panel of other enzymes, be used as a biomarker of susceptibility in BEN areas.

Increased Glomerular Filtration Rate in Early Stage of Balkan Endemic Nephropathy.

Background: A previous study indicated that Balkan endemic nephropathy (BEN) patients in the early stage of the disease had significantly higher creatinine clearance (Ccr) than healthy persons. The aim of the study was to assess whether tubular creatinine secretion affects Ccr in early stages of BEN and to check the applicability of serum creatinine-based glomerular filtration rate (GFR) equations in these patients. Methods: The study involved 21 BEN patients with estimated GFR (eGFR) above 60 mL/min/1.73 m2, excluding any conditions that could affect GFR or tubular creatinine secretion, and 15 healthy controls. In all participants Ccr with and without cimetidine and iohexol clearance (mGFR) were measured and eGFR calculated using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease Study (MDRD) equations. Glomerular hyperfiltration cutoff (GFR-HF) was calculated. Results: There was no significant difference between the groups in Ccr before and after cimetidine or for eGFR, but mGFR was significantly higher in BEN patients than in controls (122.02 ± 28.03 mL/min/1.73 m2 vs. 101.15 ± 27.32 mL/min/1.73 m2; p = 0.032). Cimetidine administration reduced Ccr by 10% in both groups. The ratio of Ccr to mGFR was significantly above one in seven BEN patients and five controls and their mGFR values were similar. Seven other patients and eight controls had this ratio equal to one, while values below one were recorded for seven more patients and two controls. mGFR of all these 14 patients was significantly higher than that of healthy controls (129.88 ± 27.52 mL/min/1.73 m2 vs. 107.43 ± 19.51 mL/min/1.73 m2; p = 0.009). Mean GFR-HF was significantly higher than mGFR in controls, but these two values were similar in BEN patients. eGFR underestimated mGFR in both BEN patients and controls. Conclusion: The ratio of Ccr to mGFR and mGFR to GFR-HF indicated that elevated mGFR in early stages of BEN could be explained by increased glomerular filtration, but tubular creatinine secretion augmented Ccr in a smaller proportion of patients, who did not differ from healthy subjects.

Balkan endemic nephropathy: an update on its aetiology.

Balkan endemic nephropathy (BEN) is a unique, chronic renal disease frequently associated with upper urothelial cancer (UUC). It only affects residents of specific farming villages located along tributaries of the Danube River in Bosnia-Herzegovina, Croatia, Macedonia, Serbia, Bulgaria, and Romania where it is estimated that ~100,000 individuals are at risk of BEN, while ~25,000 have the disease. This review summarises current findings on the aetiology of BEN. Over the last 50 years, several hypotheses on the cause of BEN have been formulated, including mycotoxins, heavy metals, viruses, and trace-element insufficiencies. However, recent molecular epidemiological studies provide a strong case that chronic dietary exposure to aristolochic acid (AA) a principal component of Aristolochia clematitis which grows as a weed in the wheat fields of the endemic regions is the cause of BEN and associated UUC. One of the still enigmatic features of BEN that need to be resolved is why the prevalence of BEN is only 3-7 %. This suggests that individual genetic susceptibilities to AA exist in humans. In fact dietary ingestion of AA along with individual genetic susceptibility provides a scenario that plausibly can explain all the peculiarities of BEN such as geographical distribution and high risk of urothelial cancer. For the countries harbouring BEN implementing public health measures to avoid AA exposure is of the utmost importance because this seems to be the best way to eradicate this once mysterious disease to which the residents of BEN villages have been completely and utterly at mercy for so long.

Biomarkers of oxidative damage and antioxidant enzyme activities in pre-dialysis Balkan endemic nephropathy patients.

AIM: To obtain more insight into molecular mechanisms underlying oxidative stress in Balkan endemic nephropathy (BEN), biomarkers of oxidative stress and antioxidant enzyme activities were studied in 38 pre-dialysis BEN patients, 21 healthy BEN family members and 36 healthy subjects from non-endemic areas. METHODS: Protein thiol groups (P-SH), antioxidant enzyme activities [superoxide dismutase (SOD) and glutathione peroxidase (GPX)], were determined in plasma spectrophotometrically, while malondialdehyde adducts (MDA) by enzyme immunoassay. RESULTS: BEN patients had significantly lower plasma GPX activity in comparison with values for both control groups (p = 0.016), gradually decreasing with kidney function impairment estimated by glomerular filtration rate (r = 0.53, p = 0.002). GPX activity was inversely correlated with serum urea (r = -0.627, p < 0.001), creatinine (r = -0.53, p < 0.05), urinary excretion of protein and α1-microglobulin (r = -0.44, p = 0.012; r = -0.50, p < 0.007). Significant upregulation of SOD activity was observed in healthy BEN family members (p < 0.05). While the concentration of MDA adducts was similar in all three groups, BEN patients and healthy BEN family members exhibited increased protein damage, based on fewer P-SH groups in comparison with subjects from non-BEN areas (p = 0.085; p = 0.014, respectively). CONCLUSIONS: Based on our results on increased oxidative protein damage in both pre-dialysis BEN patients and healthy BEN family members, it can be speculated that individuals from BEN areas, in general, are chronically exposed to some prooxidant environmental compounds. Moreover, decrease in plasma GPX activity, as a consequence of impaired kidney function, could further affect oxidative status in BEN patients.

Prevalence and risk factors of vascular calcification in pre-dialysis patients with Balkan endemic nephropathy.

Introduction: Vascular calcifications (VC) are common in patients with chronic kidney disease and present one of manifestations of mineral and bone disorders in these patients. Objective: The aim of this pilot study was to examine the prevalence and risk factors of VC in pre-dialysis patients with Balkan endemic nephropathy (BEN) and other kidney diseases. Methods: The study involved 32 pre-dialysis patients, 15 with BEN and 17 with other kidney diseases. All the patients underwent an interview, objective examination, routine laboratory analyses and measurement of serum concentration of intact parathyroid hormone (iPTH), 25-hydroxyvitamin D3 [25(OH)D3] and osteopontin. VCs in iliac, femoral, radial, and digital arteries were evaluated and Adragao VC score was calculated. The samples of radial artery were collected during the first creation of an arteriovenous fistula, and expression of osteocalcin, bone morphogenic protein-2 osteopontin, and matrix Gla-protein in arterial wall were examined. Results: Patients with BEN were significantly older (71.1 ± 6.1 vs. 54.7 ± 11.1 years), but they had significantly lower systolic and mean blood pressure (95.7 ± 13.2 mmHg vs. 104.3 ± 7.4 mmHg) and lower serum concentration of phosphorus (1.32 ± 0.36 mmol/l vs. 1.65 ± 0.35 mmol/l) and cholesterol (4.3 ± 1.1 mmol/l vs. 5.2 ± 0.8 mmol/l) than patients with other kidney diseases. Mean VC score was significantly lower in patients with BEN than in those with other kidney diseases (2.8 ± 1.7 vs. 4.6 ± 1.8; p = 0.009), but expression of four examined proteins in arterial wall differed insignificantly between the two groups. VC score correlated significantly with serum concentrations of cholesterol, triglycerides (positively), and iPTH (negatively). Conclusion: Pre-dialysis BEN patients had a significantly lower mean score of VC than patients with other kidney diseases.

Chronic dietary exposure to aristolochic acid and kidney function in native farmers from a Croatian endemic area and Bosnian immigrants.

BACKGROUND AND OBJECTIVES: Improvements in agricultural practices in Croatia have reduced exposure to consumption of aristolochic acid-contaminated flour and development of endemic (Balkan) nephropathy. Therefore, it was hypothesized that Bosnian immigrants who settled in an endemic area in Croatia 15-30 years ago would be at lower risk of developing endemic nephropathy because of reduced exposure to aristolochic acid. To test this hypothesis, past and present exposure to aristolochic acid, proximal tubule damage as a hallmark of endemic nephropathy, and prevalence of CKD in Bosnian immigrants were analyzed. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this cross-sectional observational study from 2005 to 2010, 2161 farmers were divided into groups: indigenous inhabitants from endemic nephropathy and nonendemic nephropathy villages and Bosnian immigrants; α-1 microglobulin-to-creatinine ratio >31.5 mg/g and eGFR<60 ml/min per 1.73 m(2) were considered to be abnormal. RESULTS: CKD and proximal tubule damage prevalence was significantly lower in Bosnian immigrants than inhabitants of endemic nephropathy villages (6.9% versus 16.6%; P<0.001; 1.3% versus 7.3%; P=0.003, respectively); 20 years ago, Bosnian immigrants observed fewer Aristolochia clematitis in cultivated fields (41.9% versus 67.8%) and fewer seeds among wheat seeds (6.1% versus 35.6%) and ate more purchased than homemade bread compared with Croatian farmers from endemic nephropathy villages (38.5% versus 14.8%, P<0.001). Both Croatian farmers and Bosnian immigrants observe significantly fewer Aristolochia plants growing in their fields compared with 15-30 years ago. Prior aristolochic acid exposure was associated with proximal tubule damage (odds ratio, 1.64; 95% confidence interval, 1.04 to 2.58; P=0.02), whereas present exposure was not (odds ratio, 1.31; 95% confidence interval, 0.75 to 2.30; P=0.33). Furthermore, immigrant status was an independent negative predictor of proximal tubule damage (odds ratio, 0.40; 95% confidence interval, 0.19 to 0.86; P=0.02). CONCLUSIONS: Bosnian immigrants and autochthonous Croats residing in endemic areas are exposed significantly less to ingestion of aristolochic acid than in the past. The prevalence of endemic nephropathy and its associated urothelial cancers is predicted to decrease over time.

Familial versus environmental factors in Balkan endemic nephropathy in Mehedinti county, Romania, by means of albuminuria and tubular biomarkers: preliminary study.

INTRODUCTION AND AIMS: Balkan endemic nephropathy (BEN), a regional tubulointerstitial kidney disease encountered in South-Eastern Europe, with still undefined etiology and inexorable evolution towards end stage renal disease, raises the question of the relative contribution of family and environmental factors in its etiology. In order to evaluate the intervention of these factors, markers of tubular injury have been assessed, this lesion being considered an early renal involvement in BEN. METHODS: The paper studies relatives of BEN patients currently included in dialysis programmes (for involvement of the family factor) and their neighbors (for involvement of environmental factors) and analyzes them with regard to tubular injury by means of tubular biomarkers (N-acetyl-beta-d-glucosaminidase-NAG and alpha-1-microglobulin), and albuminuria. At the same time, glomerular filtration rate (GFR) (CKD-EPI) was measured. It is considered that, in order to acquire the disease, one should have lived for 20 years in the BEN area. The relatives have been classified according to this criterion. RESULTS: More evident tubular injury was found in the neighbors of BEN patients living for more than 20 years in the endemic area, which argues in favor of environmental factors. Higher levels of urinary alpha-1-microglobulin and albumin in relatives of BEN patients who had been living for more than 20 years in the area than in relatives with a residence under 20 years, plead for the same hypothesis. GFR was lower in persons who had been living for more than 20 years in the BEN area (neighbors and relatives). CONCLUSIONS: Environmental factors could be more important in BEN than family factors.

Surprising good antioxidant status in patients with Balkan Endemic Nephropathy on hemodialysis undergoing vitamin C therapy. A pilot study.

AIMS: End Stage Renal Disease (ESRD) represents a microinflammatory state accompanied by oxidative stress and an imbalance between pro- and antioxidants. Vitamin C is a highly effective antioxidant, acting to lessen oxidative stress. The aim of our study was to assess the Antioxidant Capacity of Water soluble substances (ACW) and the Antioxidant Capacity of Liposoluble substances (ACL) in patients with Balkan Endemic Nephropathy (BEN) on hemodialysis undergoing Vitamin C therapy as compared to healthy controls. METHODS: Twenty-one patients with BEN on hemodialysis (HD), mean age: 63.33 +/- 5.42 years, 6 M and 15 F, were enrolled into the study. All patients received 10 vials of Vitamin C 750 mg/5 ml every 2 months. Eleven apparently healthy subjects, mean age: 63.73 +/- 5.21 years, 6 M and 5 F, served as controls. The photochemiluminescence assay was used to measure the antioxidant activity of plasma samples. The results are presented in equivalent concentration units of Vitamin C for water soluble antioxidants and in equivalent concentration units of Trolox (synthetic Vitamin E) for lipid soluble antioxidants. Both concentrations are expressed in micromols/L. Statistical analysis (non-parametric Wilcoxon test) was performed using NCSS. RESULTS: Mean duration since BEN diagnosis was: 8.24 +/- 3.5 years. Mean duration since HD initiation was: 4.92 +/- 3.4 years. Smoking status was negative in all patients. Hypertension was present in 15 patients (71.42%), cardiovascular disease in 10 (47.61%), HCV infection in 13 (61.9%), 1 patient had HBV + HCV infection, 1 had renal tuberculosis, 1 had upper urinary tract cancer, 1 genital cancer, and I autoimmune thyroid disease. The Antioxidant Capacity of Water soluble substances (ACW) in patients with BEN was 477.6 +/- 177.63 micromols/L, significantly higher as compared to controls: 198.05 +/- 196.63 micromols/L; p = 0.01, whereas the Antioxidant Capacity of Liposoluble substances (ACL) in patients with BEN was 33.9 +/- 22.99 micromols/L, non-significantly different as compared to controls: 27.38 +/- 4.21 micromols/L; p = 0.22. CONCLUSIONS: We conclude that Vitamin C therapy in patients with BEN on HD significantly increases the Antioxidant Capacity of Water soluble substances (ACW) as compared to controls and could be used to counter oxidative stress in patients with ESRD.

The assessment of arterial stiffness in endemic (Balkan) nephropathy patients undergoing haemodialysis.

Cardiovascular (CV) complications are the most important cause of morbidity and mortality in patients with advanced chronic kidney disease (CKD). Arterial stiffness (AS) has been recognized as a strong and independent predictor for CV events in CKD. Our aim was to assess indices of AS in a group of Endemic (Balkan) Nephropathy (EN) patients undergoing haemodialysis (HD). Hypertenison was not considered an importnat feauture in earlier stages of the disease, and therefore we presumed that those patients would have lower AS. Interestingly, we found AS to be even higher in this group of EN patients. This result should be confirmed in a larger cohort of EN patients.

Incidence and predictive factors of Balkan endemic nephropathy: a longitudinal study.

Balkan endemic nephropathy (BEN) is a chronic kidney disease that progresses slowly. There are no known clinical markers to identify an early disease development. We evaluated the relationship between parental history of BEN and clinical markers as predictors of new occurrences of BEN. A 5-year prospective study in the offsprings of BEN and control patients was conducted in Vratza, Bulgaria, between 2003 and 2009 using markers in years one and three to predict new cases of BEN in the year five. We defined incident cases of BEN based on parental history, reduced kidney size and reduced kidney function, distinguishing probable and definite BEN, both combined as total incidence. The data were analyzed by Cox regression models using age as time scale and controlling for gender. We estimated hazard ratios and their 95% confidence intervals. The incidence of BEN was 17.4%. Paternal history was strongly associated with all three incidence groups (hazards ratio: 27-68, P <0.05). A reduction of kidney size of 1 mm resulted in a 5% increased hazard. However, taking parental history of BEN into account, these associations lost their significance. No kidney function measures were associated with new onset of BEN. A parental history of BEN is more important than clinical markers predicting the incidence of BEN. Without this information, kidney length forecasts probable BEN and the total incidence, while none of any clinical markers was related to definite BEN.

Urinary protein patterns in patients with Balkan endemic nephropathy.

PURPOSE: Urinary excretion of beta2-microglobulin (beta2-MG), albumin, immunoglobulin G (IgG) and protein was examined in patients with Balkan endemic nephropathy (BEN), glomerulonephritis (GN) and healthy controls. METHODS: The proteins were measured in morning urine samples from 74 patients with BEN, 50 healthy persons and 22 patients with GN. RESULTS: In BEN patients, median values for albumin, beta2-MG and protein were above upper normal limits, but median IgG was inside normal range. All patients with GN had microalbuminuria (MAU) and half of them had increased urinary beta2-MG, which was also found in eleven patients with increased urinary IgG. In BEN patients, there were significant negative correlations between eGFR and all measured urinary proteins, the composition of which changed during the course of BEN. In patients with eGFR > 60 ml/min/1.73 m(2) isolated beta2-MG was the most frequent finding (10/12 patients), but MAU was present in 4/12 patients. In BEN patients with eGFR between 30 and 59 ml/min/1.73 m(2), beta2-MG appeared as often as the combination of beta2-MG and albumin and isolated MAU. Out of 49 BEN patients with eGFR > 30 ml/min/1.73 m(2) 15 had increased urinary IgG either alone (1) or together with beta2-MG (3) or albumin (3) or beta2-MG and albumin (8). In BEN patients with GFR < 30 ml/min/1.73 m(2) only 1/25 had isolated beta2-MG but increased urinary IgG with increased beta2-MG, and albumin was the most frequent. CONCLUSION: Although low-molecular weight proteinuria was the most frequent urinary finding in BEN patients, MAU was frequently detected in advanced stages of BEN but also in some patients with eGFR > 60 ml/min/1.73 m(2). IgG was increasingly found as eGFR decreased.

Epidemiological data regarding Balkan endemic nephropathy in relationship with the Pliocene coal etiological hypothesis.

Balkan Endemic nephropathy (BEN) is a tubulointerstitial disease of unknown etiology signaled in a limited geographical area. In the neighbourhood of endemic villages are coal deposits from the Pliocene, that contain toxic substances that by mobilizing groundwater can leach in water sources used by the inhabitants. In the present paper the possible impact of the coal from Pliocene on people that worked many years in mines in the endemic County Mehedinti, Romania, and who lived in this area are analysed. The risk of toxicity of coal was theoretically increased in miners because they consumed frequently water from mine springs that came from coal layers, while at home water from wells could have been contaminated by toxic substances from coal. It has been found that only 5 of the 96 patients with BEN were under dialysis program in 2008. Also out of 34 former miners only 3 had GFR < 60 ml/min/1.73 sqm, and only one with creatinine of 3 mg/dl had GFR < 30 ml/min/1.73 sqm. The mean GFR in the 34 miners was: 94.13 +/- 26.58 ml/min/1.73 sqm. We analysed GFR and proteinuria in persons from the endemic zone from 2 types of villages: some with mining activity presently (Husnicioara) others where presently there are no mining activities (Hinova, Bistrita, Livezile). We also analysed comparatively 2 non-endemic localities near the endemic focus: Drobeta Turnu Severin (without mining activity) and Motru with mining activity where different coal deposits are (non-Pliocene). Data were provided from the family doctors databases. The GFR was lower in the inhabitants from the endemic villages Bistrita and Hinova than in the investigated inhabitants from the non-endemic town Drobeta Turnu Severin (p = 0.008 and p = 0.0004 respectively). Inhabitants from the endemic village Husnicioara (Pliocene coal mine still functioning) had a higher GFR than inhabitants from Drobeta Turnu Severin and higher than inhabitants from the endemic village Livezile (mine closed 10 years ago): p = 0.0055 and p = 0.001 respectively, but a lower than the investigated inhabitants from the non-endemic town Motru (where a non-Pliocene coal mine is functioning): p < 0.001. Proteinuria was present in 8.03% of the inhabitants from the endemic village Bistrita and in 7.4% of the inhabitants from the endemic village Hinova. In the non-endemic town Drobeta Turnu Severin, proteinuria was present in 7.08% of the investigated inhabitants. Proteinuria was present in 0.78% of the investigated inhabitants of the non-endemic town Motru (where a non-Pliocene coal mine is functioning) and 2.5% of the inhabitants of the endemic village Husnicioara (Pliocene coal mine still functioning). Our paper does not show any relationship between exposure to Pliocene coal and the etiology of BEN.

[Structural and functional characteristics of urinary tract in offspring of Balkan endemic nephropathy patients].

INTRODUCTION: Balkan endemic nephropathy (BEN) is a familial chronic progressive tubulointerstitial disease of unknown aetiology that occurs with high prevalence in endemic rural environments of Serbia, Bosnia and Herzegovina, Croatia, Bulgaria and Romania. It has been documented only in adults. OBJECTIVE: The aim of this study was to examine clinical markers of BEN in children and adolescent offspring of BEN patients. METHODS: Prospective clinical trial involved two groups of children and adolescents: I consisted of 30 offspring of BEN patients and II of 29 offspring of non-BEN dialysis patients, both of them living in the same South Morava region of Serbia. All of them were healthy at the time of the investigation, not receiving any drugs. The study included personal and family history, physical examination, comprehensive laboratory analyses and renal ultrasound. Blood pressure (BP) was determined by using casual BP and 24 h ABPM in subjects older than 5 years. Urinary proteins were investigated by analysing microalbumin, alfa 1 microglobulin, beta 2 microglobulin and SDS-PAGE electrophoresis. GFR was measured by estimated creatinine clearance and by serum Cystatin C concentrations. RESULTS: There were no statistically significant differences in age, gender, history of urinary tract infections or functional voiding disorders between these two groups. All of the studied subjects had normal BP and GFR. Renal ultrasound was abnormal only in BEN offspring (6.66%) as well as increased urine concentrations of microalbumin (3.3%), alpha 1 microglobulin (10%) and beta 2 microglobulin (13.3%) while low molecular protein (<66,000 D) was prevalent in BEN compared with non-BEN offspring (21.43% vs. 3.7%). CONCLUSION: Renal abnormalities in offspring of BEN patients may be an early marker of BEN.This has to be confirmed in long term follow-up of a greater number of BEN paediatric offspring.

Fifty years of Balkan endemic nephropathy: challenges of study using epidemiological method.

Balkan endemic nephropathy (BEN) is a chronic tubulointerstitial disease associated with urothelial cancer, which affects people living in the alluvial plains along the tributaries of the Danube River. Challenges of studying BEN using the epidemiological method are multiple. The natural history from exposure to occurrence of the disease may take many years. The early stages of BEN are not easily detectable clinically, as the disease is asymptomatic until a significant decline in function occurs, and even then symptoms are usually non-specific. The natural history of BEN is complex, possibly with multiple risk factors operating both at the stage of initiation of renal damage and in its progression. In BEN, genetic susceptibility is due to multiple genes of small effects, gene-gene interactions, and gene-environment interactions of complex nature that are difficult to assess with current study designs. BEN is now kidney disease of the old people, and many risk factors for disease such as smoking, alcohol consumption, obesity, and diabetes could contribute to the kidney damage. Evidence is presented that environmental rather than genetic factors play a decisive role in the etiopathogenesis of BEN. Aristolochic acid, described as a culprit of BEN in 1959, is confirmed in 2007 by the molecular biology methods. Mycotoxins and polycyclic aromatic hydrocarbons, leached from lignites and found in the vicinity of endemic settlements, deserve further investigation. Despite advances in understanding the epidemiology of BEN, more research is needed on the patterns of BEN over time and between places, and on identifying the contributions of modifiable risk factors in initiating and hastening progression of BEN in order to improve the scope for preventing BEN. Primary prevention is still at the beginning. Knowledge accumulated in the fifty years of BEN research and new data about prevention and treatment of chronic kidney disease reveal several effective methods in secondary and tertiary prevention of BEN. Genetic epidemiology could establish the relative size of the genetic effect in relation to other sources of variation in disease risk (i.e., environmental effects such as intrauterine environment, physical and chemical effects, as well as behavioral and social aspects). Public health authorities in the several countries having aristolochic acid nephropathy should take immediate measures for reducing dietary exposure of residents to Aristolochia.

Visual assessment of endemic nephropathy markers relationship.

The aim of this paper was to assess relationship between possible endemic nephropathy (EN) markers visually by the CoPlot methodology, and to illustrate this promising data analysis approach. From 912 screened persons in 3 Croatian endemic villages, 25 persons were diagnosed as confirmed EN patients, 371 as non-EN, and the remainder were classified as suspected of having EN, or at risk. Data on 25 confirmed EN patients were matched with appropriate non-EN examinees. All records with missing data were excluded, resulting in 35 subjects with complete data on the 13 key EN variables for CoPlot mapping. CoPlot solution met the accepted goodness of fit measure thresholds. Result showed relationship between EN markers, identifying some nearly duplicated variables, and possible outliers needing some subsequent analysis.

[One-year follow-up of renal function in endemic nephropathy families].

INTRODUCTION: Endemic nephropathy is familial, chronic tubulointerstitial disease with an insidious onset and asymptomatic, slow progressive course. OBJECTIVE: The present study was undertaken with the aim to find out whether new persons with renal disorders can be detected among members of endemic families in the village of Sopic (Kolubara River region, Serbia). METHODS: The study involved 44 members of five endemic families without history of renal disorders. Objective survey and laboratory analyzes that enabled determination of kidney functions (creatinine clearance, proteinuria, urine specific gravity and osmolality, fractional sodium excretion (FENa), the rate of tubular phosphate reabsorption (TRP), urine N-acetil-D-glycosaminidase and intestinal alkaline phosphatase) were done in all examined persons three times during the 6-month intervals. RESULTS: At the first examination, hypertension was detected in 23 (52%) person, decreased creatinine clearance in two and proteinuria in 10 persons included in the study. In addition, proteinuria and tubular disorders were detected in 6, hypertension, proteinuria and/or tubular disorders in 9 persons. The analysis of the results obtained by three check-ups undertaken during one year showed that proteinuria and tubular disorders appeared intermittently in half of the examined endemic family members. All persons with detected renal disorders required further examination in order to establish accurate diagnosis of renal disease. CONCLUSION: Three check-ups performed at six-month intervals in the members of five endemic families detected various renal disorders including renal hypofunction. Regular systematic check-ups of endemic families could enable early detection of the disease and early initiation of measures for slowing down chronic renal disease progression.

[Results of kidney function measurement and blood pressure in population from endemic region of Vitina].

INTRODUCTION: The analysis of frequency of kidney diseases, causes of terminal renal failure in patients subjected to repeated dialysis in major dialysis centers in the region of Kosovo and Metohija as well as mortality rate in these patients showed a stable number of patients with kidney diseases, evidencing that the populations of Vitina and Gnjilane were the most commonly affected These towns are designated as regions with the highest incidence of Balkan endemic nephropathy. The present analysis was aimed at: (1) establishing the incidence rate of hypertension and renal function impairment by using clinical and laboratory analyses in individuals from Vitina and neighboring villages, and (2) investigating the correlation between creatinine clearance, age and arterial blood pressure in the studied group. MATERIAL AND METHODS: The analysis included 510 individuals (excluding diabetics) over the one-month period during 2004 (201 males with their age ranging from 18 to 90 years). Blood pressure measurements were performed in all the individuals, while renal function was determined by glomerular filtration rate (GFR), as calculated according to Cockcroft-Gault formula. RESULTS: Creatinine clearance was lower than 100 ml/min in 237 (46.5%) individuals, out of whom 62 (12%) had GFR below 60 ml/min. Among the remaining 273 (53.5%) individuals with GFR above 100 ml/min, 68 individuals had GFR above 140 ml/min. The distribution of patients depending on their systolic blood pressure values revealed that systolic blood pressure was lower in 44 subjects and higher in 302 subjects (59%). The correlation test revealed significant association between the studied parameters. The positive correlation between patients' age and kidney function means the higher the age of subjects the lower creatinine clearance value (r = --0.622, p < 0.001). The negative correlation of the systolic blood pressure value and kidney function was found, meaning that higher the systolic blood pressure is accompanied by lower creatinine clearance (r = --0.204, p < 0.001). Moreover, patients' age was significantly correlated with the systolic blood pressure level (r = 0.511, p < 0.001), as well as with the diastolic blood pressure level (r = 0.299, p < 0.001). The former means that higher values of both systolic and the diastolic pressures were found in older subjects. No correlation was found between the diastolic blood pressure level and kidney function (the results are not presented). Conclusion The results obtained in the study confirm significant incidence of renal function impairment measured according to creatinine clearance values in patients from the endemic nephropathy region. Reduced kidney function is found in both elderly individuals and those with high systolic blood pressure. In order to establish the correlation with the incidence and presence of BEN or other kidney diseases additional population screening is necessary.

Diagnostic criteria for Balkan endemic nephropathy: proposal by an international panel.

Balkan endemic nephropathy (BEN) is a familial chronic tubulointerstitial disease with insidious onset and slow progression to terminal renal failure. Diagnostic criteria for BEN have been described more than 40 years ago. Research groups on BEN use one of at least three described lists of criteria. Comparison of studies using such criteria is difficult, and a recent meeting of investigators (Zagreb, October 2006) has suggested that unified criteria have to be elaborated. In this paper, an International Panel of BEN Investigators agreed on criteria appropriate to epidemiologic studies and clinical investigations of BEN. A screening procedure of BEN in endemic settlements is proposed.