Molecular characterization of cystinuria in south-eastern European countries.

Cystinuria is an autosomal recessive disorder caused by defective transport of cystine and dibasic amino acids in the proximal renal tubules and small intestine. So far, more than 128 mutations in SLC3A1 gene, and 93 in SLC7A9 gene have been described as a cause of cystinuria. We present a molecular characterization of the cystinuria in 47 unrelated south-east European families. The molecular methodology included direct sequencing, single strand conformational polymorphism, and restriction fragment length polymorphism. A total of 93 (94.9 %) out of 98 unrelated cystinuric chromosomes have been characterized. Mutations in SLC3A1 gene account for 64.3 % and in SLC7A9 gene for 30.6 % of the cystinuric chromosomes. Ten different mutations in SLC3A1 gene were found, and two of them were novel (C242R and L573X), while in SLC7A9 gene seven mutations were found, of which three were novel (G73R, V375I and c.1048_1051delACTC). The most common mutations in this study were T216M (24.5 %), M467T (16.3 %) and R365L (11.2 %) in SLC3A1 and G105R (21.4 %) in SLC7A9 gene. A population specificity of cystinuria mutations was observed; T216M mutation was the only mutation present among Gypsies, G105R was the most common mutation among Albanians and Macedonians, and R365L among Serbs. The results of this study allowed introduction of rapid, simple and cost-effective genetic diagnosis of cystinuria that enables an early preventive care of affected patients and a prenatal diagnosis in affected families.

Oxidative stress in children with kidney disease.

The aim of this work was to study the dynamics of oxidative stress in the blood and urine of children with kidney diseases: glomerulonephritis (GN), pyelonephritis (PN), renal failure (RF), and lower urinary tract infections (LUTI). The concentration of conjugated dienes is increased in blood: GN 4 times and RF up to 2 times; and extremely increased in urine: GN 12 times and RF 4 times. The concentration of thiobarbituric acid reactive substances in urine shows a similar trend: GN 7 times, PN 2 times, RF 1.5 times, and LUTI almost 3 times. Urine chemiluminescence is also increased: GN 5 times, PN and LUTI 3 times, and RF 6 times. Kidney disease leads to 2.5-fold inhibition of antioxidant catalase activity in blood and 10-fold in urine. Total antioxidant activity of urine is induced in all groups: GN 18 times, PN 2 times, RF 1.5 times, and almost 4 times in the LUTI group. Experimental data confirm that products of lipid peroxidation, intensity of chemiluminescence, and total and enzyme antioxidant capacity in combination with clinical parameters are a proper test for the dynamics of oxidative stress and markers of intoxication in children with inflammatory and immunological active parenchymal kidney disorders. These data could be helpful for the optimization of complex and effective antioxidant therapy of children with kidney disease.

Hypertension in children with chronic renal failure.

Systemic hypertension (HTN) is one of the major problems associated with chronic renal failure (CRF). HTN is a symptom and complication of CRF. The prevalence of HTN varies with the cause of CRF. The incidence of HTN increased up to 90% with progressive deterioration of the glomerular filtration rate (GFR). HTN is the major risk factor for decline in renal function and progression of CRF. It is the most important risk factor for cardiovascular diseases and morbidity and mortality in patients with CRF and end-stage renal disease (ESRD) on dialysis. The target blood pressure for hypertensive children with CRF should be under the 95th percentile for sex and age. The therapeutic approach in CRF is directed at reducing volume expansion and sodium retention, and decreasing peripheral vascular resistance. Diuretics are first-line therapy for HTN in patients with CRF with sodium and water retention. ACE inhibitors are the first-class drugs because of their renoprotective effect in preventing deterioration of kidney function. Calcium channel blockers are excellent first-line antihypertensive drugs. Recently angiotensin II receptor blockers and ACE inhibitors have been efficiently used together for the treatment of HTN and to prevent further decline in renal function.

PKHD1 protein encoded by the gene for autosomal recessive polycystic kidney disease associates with basal bodies and primary cilia in renal epithelial cells.

Mutations of the polycystic kidney and hepatic disease 1 (PKHD1) gene have been shown to cause autosomal recessive polycystic kidney disease (ARPKD), but the cellular functions of the gene product (PKHD1) remain uncharacterized. To illuminate its properties, the spatial and temporal expression patterns of PKHD1 were determined in mouse, rat, and human tissues by using polyclonal Abs and mAbs recognizing various specific regions of the gene product. During embryogenesis, PKHD1 is widely expressed in epithelial derivatives, including neural tubules, gut, pulmonary bronchi, and hepatic cells. In the kidneys of the pck rats, the rat model of which is genetically homologous to human ARPKD, the level of PKHD1 was significantly reduced but not completely absent. In cultured renal cells, the PKHD1 gene product colocalized with polycystin-2, the gene product of autosomal dominant polycystic disease type 2, at the basal bodies of primary cilia. Immunoreactive PKHD1 localized predominantly at the apical domain of polarized epithelial cells, suggesting it may be involved in the tubulogenesis and/or maintenance of duct-lumen architecture. Reduced PKHD1 levels in pck rat kidneys and its colocalization with polycystins may underlie the pathogenic basis for cystogenesis in polycystic kidney diseases.

Recombinant human growth hormone therapy in autosomal recessive polycystic kidney disease.

Patients with autosomal recessive polycystic kidney disease (ARPKD) may have growth retardation that is disproportionate to the degree of renal dysfunction. We treated growth-retarded ARPKD patients with recombinant growth hormone (rhGH) and document the response to therapy and effect of rhGH on the rate of progression of renal failure. The diagnosis of ARPKD and congenital hepatic fibrosis was made on the basis of clinical findings and by abdominal ultrasound examinations. Seventeen patients (6 girls/11 boys) aged 0.3-18.3 years were studied. Diagnosis was made prenatally in 6, after birth in 3, and in 8 between 0.33 and 10 years. Follow-up was 2 months to 14.3 years (median 6.9 years). Growth, growth velocity, weight, and bone age were measured before and after treatment with rhGH. Insulin-like growth factor-1 and IGF binding protein 3 were measured prior to rhGH therapy. Five children (1 girl/4 boys) with height Z-scores < or =1.2 (5/17) aged 4.5-11.9 years received rhGH therapy. Duration of rhGH therapy was 0.3-5.4 years. All responded to rhGH (Z-score before -2.8 vs. -1.26 after treatment, P=0.03). An increase in height Z-score was noted 0.5-1.5 years after starting rhGH therapy. There were no side effects from rhGH therapy. The initial Z-score in the untreated group was -0.35 and the final score was -0.64. Initial glomerular filtration rate (GFR) in the treated group was 77 versus 104 ml/min per 1.73 m(2) in the non-treated group. GFR in 3 of 6 growth-retarded patients (<5th percentile) was 38, 65, and 30 ml/min per 1.73 m(2). GFR in 2 of 11 non-growth-retarded patients was 30 and 26 ml/min per 1.73 m(2). The change from initial GFR and final GFR in treated patients was 77 versus 76 ml/min per 1.73 m(2), and non-treated patients 104 versus 89 ml/min per 1.73 m(2) ( P>0.05). Growth failure in ARPKD may be attributable to factors other than chronic renal insufficiency alone. Use of rhGH therapy in ARPKD is safe, effective, and has the potential to improve the physical and psychological well-being of these children.