To find out whether ochratoxin A (OTA), citrinin (CIT), aristolochic acids (AA) are etiologic agents of Balkan endemic nephropathy (BEN) or Chinese herbal nephrotoxicity, and associated urinary tract tumor (UTT), we have compared (i) in human kidney cell culture, the DNA adduct formation and persistence of OTA/CIT and AA adducts (ii) analyzed DNA adduct in several tumors from human kidney suspected to be exposed to either OTA and CIT, or AAs (iii) analyzed OTA, CIT, and AA in food. In kidney cell cultures, formation of specific OTA-DNA adduct and AA-DNA adduct were detected in the same range (around 10 adducts/10(9) nucleotides) and were time- and dose-dependent. After 2 days all disappeared. DNA adduct related to OTA and CIT are found in human kidney tissues from Balkans, France, and Belgium whereas no DNA adducts related to AA could be found in any tumors of BEN patients from Croatia, Bulgaria, or Serbia. No DNA adduct was found in kidney biopsy or necropsy of the French women suspected to be exposed to AA. OTA and CIT are more frequently found in rural area. AA was never detected. All these plead for implication of mycotoxins, especially OTA, in BEN and UTT.

Currently used diagnostic criteria in different endemic (Balkan) nephropathy (EN) centers involve different combinations of parameters, various cut-off values and many of them are not in agreement with proposed international guidelines. Leaders of EN centers began to address these problems at scientific meetings, and this paper is the outgrowth of those discussions. The main aim is to provide recommendations for clinical work on current knowledge and expertise. This document is developed for use by general physicians, nephrologists, urologist, public health experts and epidemiologist, and it is hoped that it will be adopted by responsible institutions in countries harboring EN. National medical providers should cover costs of screening and diagnostic procedures and treatment of EN patients with or without upper urothelial cancers.

Aetiology remains the main unanswered problem in Balkan endemic nephropathy (BEN) despite investigations into the roles of genetic factors, environmental agents and immune mechanisms. Evidence has accumulated that BEN is an environmentally-induced disease. Weathering of low-rank coals near to the villages where BEN is endemic produces water-soluble polycyclic aromatic hydrocarbons and aromatic amines, similar to metabolic products of acetaminophen that cause analgesic nephropathy. Many of these compounds are known to be carcinogenic and could also cause urothelial cancer. Genetic studies have supported genetic predisposition to BEN. The candidate genes have been localized to a region between 3q25 and 3q26, the 3q BEN marker being detected in both BEN patients and in some healthy relatives with initial morphological changes peculiar to BEN. Three bands with increased frequencies of spontaneous and induced aberrations contain oncogenes. The frequent association of BEN and urinary tract tumours (UTT) can be explained by the chromosomal hypothesis of oncogenesis. The results of molecular biological investigations will allow the identification of genetic markers of BEN, permitting early detection of BEN-predisposing mutations and identification of susceptible individuals who may be at risk of exposure to the environmental agents. An increased incidence of tumours of renal pelvis and ureter in patients with BEN and in population from endemic settlements has been observed. Familial clustering of the UTT was also reported. The frequency of urinary bladder tumours in BEN-endemic settlements is also increased compared with the non-endemic villages and cities. The geographic correlation between BEN and UTT supports the speculation that these diseases share a common aetiology.

Balkan endemic nephropathy (BEN) is a familial chronic tubulointerstitial disease with insidious onset and slow progression leading to terminal renal failure. The results of molecular biological investigations propose that BEN is a multifactorial disease with genetic predisposition to environmental risk agents. Exome sequencing of 22 000 genes with Illumina Nextera Exome Enrichment Kit was performed on 22 DNA samples (11 Bulgarian patients and 11 Serbian patients). Software analysis was performed via NextGene, Provean, and PolyPhen. The frequency of all annotated genetic variants with deleterious/damaging effect was compared with those of European populations. Then we focused on nonannotated variants (with no data available about them and not found in healthy Bulgarian controls). There is no statistically significant difference between annotated variants in BEN patients and European populations. From nonannotated variants with more than 40% frequency in both patients' groups, we nominated 3 genes with possible deleterious/damaging variants—CELA1, HSPG2, and KCNK5. Mutant genes (CELA1, HSPG2, and KCNK5) in BEN patients encode proteins involved in basement membrane/extracellular matrix and vascular tone, tightly connected to process of angiogenesis. We suggest that an abnormal process of angiogenesis plays a key role in the molecular pathogenesis of BEN.

The aim of this study was to determine the long-term functional outcome of kidneys in children with urolithiasis treated by means of extracorporeal shock wave lithotripsy (ESWL). The effectiveness and safety of this method in the management of pediatric urinary stone disease was also studied. This prospective study enrolled 84 children, 33 boys (age: 9.1 +/- 3.8 yrs) and 51 girls (age: 9.6 +/- 3.9 yrs), with urolithiasis who were treated using a second-generation "Siemens" Lithostar lithotriptor, in the period between 1988 and 1998. Dynamic kidney scintigraphy using (99 m)Tc-DTPA was done prior to, immediately following ESWL treatment, three months later, and again after an observation period of 12 - 67 months (38 +/- 13 months). Immediate fragmentation rate was 90 %, while the calculus clearance rate was 61 %. Glomerular filtration rate (GFR), measured by clearance of (99 m)Tc-DTPA, immediately after an ESWL treatment of 107 +/- 6 ml/min was significantly lower compared to the pretreatment value of 118 +/- 7 ml/min, but returned three months later to 121 +/- 6 ml/min, and to 131 +/- 10 ml/min at the end of the observation period. A separate analysis was performed on three groups of patients treated by ESWL: with acute calculous disease, chronic calculous disease, and chronic calculous with partial stasis. ESWL treatment in children with acute obstruction was associated with an immediate increase in GFR; however, in chronic calculous disease a decrease in GFR was found. A return of GFR to the pretreatment level was observed at the three-month control in these patients. In patients with acute stone obstruction, at 3 and 12 - 67 months after ESWL treatment, GFR of the treated kidney was found to be significantly increased compared to the pretreatment level. In contrast, in children with chronic calculous disease this increase was modest. This study has demonstrated ESWL to be an effective treatment option for urinary calculi management, which can be safely performed in a pediatric population without long-term effects on the growing kidneys.