János Mátyus

Dent Disease with mutations in OCRL1.

Dent disease is an X-linked renal proximal tubulopathy associated with mutations in the chloride channel gene CLCN5. Lowe syndrome, a multisystem disease characterized by renal tubulopathy, congenital cataracts, and mental retardation, is associated with mutations in the gene OCRL1, which encodes a phosphatidylinositol 4,5-bisphosphate (PIP(2)) 5-phosphatase. Genetic heterogeneity has been suspected in Dent disease, but no other gene for Dent disease has been reported. We studied male probands in 13 families, all of whom met strict criteria for Dent disease but lacked mutations in CLCN5. Linkage analysis in the one large family localized the gene to a candidate region at Xq25-Xq27.1. Sequencing of candidate genes revealed a mutation in the OCRL1 gene. Of the 13 families studied, OCRL1 mutations were found in 5. PIP(2) 5-phosphatase activity was markedly reduced in skin fibroblasts cultured from the probands of these five families, and protein expression, measured by western blotting, was reduced or absent. Slit-lamp examinations performed in childhood or adulthood for all five probands showed normal results. Unlike patients with typical Lowe syndrome, none of these patients had metabolic acidosis. Three of the five probands had mild mental retardation, whereas two had no developmental delay or behavioral disturbance. These findings demonstrate that mutations in OCRL1 can occur with the isolated renal phenotype of Dent disease in patients lacking the cataracts, renal tubular acidosis, and neurological abnormalities that are characteristic of Lowe syndrome. This observation confirms genetic heterogeneity in Dent disease and demonstrates more-extensive phenotypic heterogeneity in Lowe syndrome than was previously appreciated. It establishes that the diagnostic criteria for disorders resulting from mutations in the Lowe syndrome gene OCRL1 need to be revised.

The Serum Paraoxonase Activity in Patients with Chronic Renal Failure and Hyperlipidemia

Human serum paraoxonase is physically associated with an apolipoprotein (Apo-A1) and clusterin-containing high-density lipoprotein (HDL) and prevents low-density lipoprotein from lipid peroxidation. The aim of our study was to determine whether paraoxonase activity or phenotype is altered in patients with chronic renal failure and in hyperlipidemic subjects without renal insufficiency and to compare the values with those of healthy controls. We investigated the serum paraoxonase activity and polymorphism in 119 hemodialyzed uremic patients, 107 patients with primary hyperlipoproteinemia, and in 110 healthy control subjects. The serum paraoxonase activity was significantly decreased both in hyperlipidemic (p < 0.01) and uremic patients (p < 0.001) as compared with controls. On comparison, the serum paraoxonase activity was significantly lower (p < 0.001) in uremic than in hyperlipoproteinemic patients. The HDL and Apo-A1 levels were as follows: uremic < hyperlipidemic < control. To assess whether the observed reduction in paraoxonase activity was due to HDL and Apo-A1 level decreases, we standardized the enzyme activity for HDL and Apo-A1 concentrations. We found that the standardized paraoxonase activity (paraoxonase/HDL ratio) was also lower in the uremic patients (103.3 ± 69.5) as compared with hyperlipidemic patients (137.64 ± 81.0) and controls (194.45 ± 94.45). The standardized values for Apo-A1 showed a similar tendency: paraoxonase/Apo-A1 ratio in uremic patients 89.64 ± 47.8, in hyperlipidemic patients 128.12 ± 69.83, and in controls 161.40 ± 47.35. The phenotypic distribution of paraoxonase (AA, AB, BB) did not change significantly in the patient groups. These results suggest that HDL concentration and phenotypic distribution of paraoxonase may not be the only determining factors, but that other as yet undetermined factors could be involved in the enzyme activity changes.

Serum paraoxonase activity changes in uremic and kidney-transplanted patients

Serum paraoxonase (PON) is a high-density lipoprotein (HDL)-associated hydrolase, which inhibits low-density lipoprotein oxidation. Uremic and kidney-transplanted patients have an increased risk of atherosclerosis, to which an increased lipoprotein oxidation may contribute. The aim of our study was to determine whether the PON activity or phenotype is altered in uremic and kidney-transplanted patients, and to compare the values with those of healthy controls. 117 uremic patients on long-term hemodialysis treatment, 115 renal-transplanted patients, and 110 healthy controls were involved in the study. The PON activity was significantly reduced in the uremic patients compared to controls (PON 101.36±30.12 vs. control 188.05±58.96 U/ml; p < 0.001), while in kidney-transplanted patients the values were almost identical to those of controls (PON 161.5±35.39 U/ml). The different immunosuppressive drug combinations did not influence PON activity. To assess whether the altered PON activity was due to a decrease HDL level, we standardized the enzyme activity for the HDL concentration (PON/HDL ratio). We found that the standardized enzyme activity was lower in the uremic (102.7±54.8) and kidney-transplanted patients (144.5±32.7) when compared to controls (194.5±94.5; p < 0.001). The phenotypic distribution of PON in uremic, renal transplant and control patients are as follows: AA 66.67, 56.48 and 66.67%; AB 31.62, 33.3 and 26.67%; BB 1.71, 10.19 and 6.67%. We conclude that the decreased PON/HDL and PON/apoA-1 ratios may lead to a reduction in the antioxidant capacity of HDL, which might contribute to the accelerated development of atherosclerosis in uremic and kidney-transplanted patients.

Study of cross-sectional and longitudinal distribution of some major and minor elements in the hair samples of haemodialysed patients with micro-PIXE

The concentration of Zn, K, Ca, Fe and Cl was determined in the hair samples of haemodialysed patients and healthy controls. Cross-sectional and longitudinal measurements were performed using the micro-PIXE method. The concentration changes of the above mentioned elements along the length of the hair and their cross-sectional distribution were studied. The effect of the washing procedure on the concentration of these elements has also been determined. The ability of the PIXE method was examined using Human Hair certified reference material (NCS DC 73347), and the results show that this method can be used to determine the concentration of the selected elements in the hair samples. We compared the results of the PIXE method with the results obtained from microwave digested reference material with the ICP-OES method. The concentration ranges of Ca, Fe and Zn were similar in the patients and controls while the concentration ranges of Cl and K were different (controls: Ca, 135-1598; Cl, 394-2382; Fe, 6-51; K, 54-1055; Zn, 102-183 µg g –1 ; versus patients: Ca, 298-559; Cl, 2476-7821; Fe, 15-58; K, 327-2031; Zn, 96-163 µg g –1 ). The washing procedure highly affected the concentration of K and Cl (unwashed: K, 1164±846; Cl, 6107±1714 µg g –1 ; versus washed: K, 497±552; Cl, 3470±1446 µg g –1 ). There were no differences between controls and patients in the cross-sectional distribution of the selected elements; the distribution of Cl was homogeneous, the Ca was concentrated in the outer layer of the hair while the distribution of K was nearly homogeneous with a slight increase at the outer layer.

Relationship between Serum Nickel and Homocysteine Concentration in Hemodialysis Patients

Severe hyperhomocysteinemia (HHC) is associated with atherosclerosis. In hemodialysis (HD) patients, one of the main causes of death is cardiovascular disease. In animals, trace elements such as cobalt, copper, iron, and nickel ameliorated vitamin B12 deficiency-induced HHC. However, correlations between plasma total homocysteine (tHcy) and trace elements in HD patients have not been investigated. Therefore, tHcy, folate, vitamin B12, trace elements (cobalt, copper, iron, and nickel), and some laboratory parameters such as serum total protein, albumin, transferrin, ferritin, C-reactive protein (CRP), and interleukin-6 concentrations were determined in 122 hemodialysis patients. When patients were divided into groups according to their tHcy, we found no significant differences in concentrations of cobalt, copper, and total protein, while nickel was higher, and folate, vitamin B12, and iron were lower in patients with lower than higher tHcy. In univariate regression analysis, tHcy negatively correlated with concentrations of folate (r = −0.302, p < 0.006), vitamin B12 (r = −0.347, p < 0.0001), nickel (r = −0.289, p < 0.006), and CRP (r = −0.230, p < 0.02) and positively with serum albumin (r = 0.316, p < 0.0004) and hemoglobin (r = 0.329, p < 0.0001) values. No relationship between tHcy and serum concentrations of cobalt, copper, iron, or other laboratory parameters was found in HD patients. The effect of cobalt and nickel on homocysteine production was assessed in human peripheral mononuclear cells (PBMCs). Nickel but not cobalt at concentrations found in HD patients significantly inhibited homocysteine, cysteine, and S-adenosylhomocysteine production in human PBMCs. These results suggest that nickel might also be involved in the regulation of the methionine–folate cycle in humans, as was demonstrated in animal experiments.

[Advances in the prevention, diagnosis and therapy of vascular diseases].

Atherosclerosis is a systemic disease affecting the coronary, carotid, intracerebral, renal and peripherial arteries. The early morphological and functional impairments could be detected in the second or third decades of life and their progression depend on the number and severity of risk factors and individual susceptility. Although the vascular risk factors (smoking, overweight, age, unhealthy diet, lack of physical exercise, hypertension, diabetes mellitus, chronic kidney disease and dyslipidemia) are the same and common in the different vascular diseases, the present clinical routine artificially classifies the diagnosis and therapy of different vascular diseases into different subfields of medicine with the negative impact of possible polypragmasia. Recently, worldwide health surveys (e.g. REACH registry) have proven the usefulness of a holistic approach in the diagnosis and therapy of multiorgan-affected vascular patients. This review summarizes the multidisciplinary advances and future perspective of vascular diseases.

New trends in the laboratory diagnostics of proteinuria and albuminuria

According to current clinical trials, albumin excretion is an early indicator of cardiovascular damage. While proteinuria is considered as a marker of kidney function, albuminuria indicates cardiovascular risk first of all. Sensitivity of the previous laboratory tests does not meet the clinical requirements, and the error of urine collection makes the results misleading. For that reason recent guidelines suggest to calculate albumin/creatinine (ACR) and protein/creatinine (PCR) measured from the first morning urine. For the clinical diagnosis of albuminuria the sensitive immunoturbidimetric assays are suggested. Albumin dipsticks are not recommended for the measurement of albuminuria. Wide-range urinary protein reagents are also available with high sensitivity, while serum reagents are not applicable (Biuret). The traceability of calibrator to a reference material is a critical requirement. Proteinuria and albuminuria of a patient should be monitored in the same laboratory, using a fixed method and cut-off value. Albumin/creatinine value should be reported together with gender-dependent reference range.Ujabb klinikai vizsgalatok szerint az albuminuria a cardiovascularis betegsegek korai markere. Mig a proteinuria elsősorban a vesefunkcio-romlas, az albuminuria a cardiovascularis riziko parametere. A regebbi laboratoriumi tesztek erzekenysege nem megfelelő, es a 24 oras vizeletgyűjtes pontatlansaga is sok bizonytalansagot okoz. Ezert a mai nemzetkozi iranyelvek 24 oras gyűjtes helyett a reggeli első vizeletből az albumin/kreatinin (ACR) es protein/kreatinin (PCR) meghatarozasat javasoljak. Klinikai laboratoriumok szamara javasolhatok az ujabb, nagy erzekenysegű immunkemiai vizeletalbumin-reagensek. Az albuminspecifi kus tesztcsikok az albuminuria fokanak meghatarozasara nem eleg erzekenyek. A vizeletfeherje-meghatarozashoz szinten leteznek nagy erzekenysegű, szeles meresi tartomanyu reagensek, igy erre nem alkalmazhatok a szerumfeherje-reagensek (peldaul Biuret). A modszervalasztas sarkalatos pontja, hogy a kalibrator nemzetkozi referensanyagra visszavezethető legyen. Mindezekből kovetkezik, hogy egy beteg ACR- vagy PCR-erteke az adott modszert es dontesi hatarerteket alkalmazo ugyanazon laboratoriumban kovethető jol. A laboratoriumi leleten az albumin/kreatinin referenciatartomanyat nemenkent kell megadni. Kulcsszavak: albuminuria, ACR, proteinuria, cardiovascularis betegseg, kreatinin New trends in the laboratory diagnostics of proteinuria and albuminuria According to current clinical trials, albumin excretion is an early indicator of cardiovascular damage. While proteinuria is considered as a marker of kidney function, albuminuria indicates cardiovascular risk fi rst of all. Sensitivity of the previous laboratory tests does not meet the clinical requirements, and the error of urine collection makes the results misleading. For that reason recent guidelines suggest to calculate albumin/creatinine (ACR) and protein/creatinine (PCR) measured from the fi rst morning urine. For the clinical diagnosis of albuminuria the sensitive immunoturbidimetric assays are suggested. Albumin dipsticks are not recommended for the measurement of albuminuria. Wide-range urinary protein reagents are also available with high sensitivity, while serum reagents are not applicable (Biuret). The traceability of calibrator to a reference material is a critical requirement. Proteinuria and albuminuria of a patient should be monitored in the same laboratory, using a fi xed method and cut-off value. Albumin/creatinine value should be reported together with gender-dependent reference range.

The epidemic of chronic kidney disease requires the estimation of glomerular filtration rate

Nowadays chronic kidney disease has become a major public health problem due to the great increase in atherogenic nephropathies. In the absence of classic renal symptoms, chronic kidney disease is mostly diagnosed when renal failure is already advanced, although it can be revealed by laboratory tests in the earlier stages. When diagnosis is late, the progression to end-stage renal failure is unavoidable and renal replacement therapy is needed. Even early-moderate renal failure significantly increases the risks for atherosclerosis, thereby leading to the deaths of patients from cardiovascular disease before initiation of dialysis. Therefore screening for asymptomatic chronic kidney disease is urgently needed. Estimated glomerular filtration rate has the greatest importance in the screening and in the timely intervention to slow down the progression of renal failure and cardiovascular disease. In 2005, the Hungarian Society of Nephrologists and the Hungarian Society of Laboratory Medicine suggested the automatic estimation and reporting of glomerular filtration rate, each time serum creatinine measurements were made. This practice is used more frequently by laboratories in Hungary. This article aims to help facilitate the utilization and evaluation of estimated glomerular filtration rate.

Relapsing polychondritis with p-ANCA associated vasculitis: Which triggers the other?

Relapsing polychondritis (RP) is a rare autoimmune disease with chronic inflammatory/destructive lesions of the cartilaginous tissues. In one third of the cases it is associated with other autoimmune disorders, mostly with anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV). We report three cases of RP with p-ANCA positive AAV. In the first patient RP developed 1.5 years after the onset of AAV. In the others the signs of RP were present before the onset of severe crescent glomerulonephritis. Patients responded well on steroid and cyclophosphamide. In dialysis dependent cases plasmapheresis was also used successfully. During the 2 and 1.5 years of follow up, they were symptom-free, and had stable glomerular filtration rate. The first patient died after four years of follow-up due to the complications of sudden unset pancytopenia, which raises the possibility of associated hemophagocytic syndrome. In the setting of RP or AAV physicians should always be aware of the possibility of sudden or insidious appearance of the other disease.

Identification of sulfhemoglobinemia after surgical polypectomy

Sulfhemoglobinemia (SHb) is an uncommon cause of cyanosis that is predominantly drug-induced in adults. We report an unusual case of sodium sulfate-induced sulfhemoglobinemia in a 61-year-old woman after surgical polypectomy. Fractional hemoglobin derivates were assayed by spectrophotometry and high-performance liquid chromatography. The SHb ratio was 8.6% in the first sample and 3.77% a month later measured by spectrophotometry. In the blood hemolysate, a new peak was identified as SHb with high-performance liquid chromatography (HPLC). HPLC showed the presence of 9.37% SHb in the first sample and 4.88% a month later. After removing the suspected toxic agent the cyanosis decreased significantly. The findings underline the importance of routine SHb detection in cyanosis of unknown origin especially in emergency cases.