Biomedical subjects

K Nemecek

Publications and source records attributed to K Nemecek.

5 recordsLinked to original sources

PubMed1999

Trace elements in end-stage renal disease. 1. Methodological aspects and the influence of water treatment and dialysis equipment.

For human beings trace elements are essential nutrients with a gamut of functions. They are for instance indispensable components of many enzymes, so they have some regulatory functions and they may affect immune reactions and free radical generation. Altered blood levels of different trace elements have been described in patients with advanced renal failure and especially in those treated by different kinds of renal replacement therapy. Altered renal function may result in impaired renal excretion of trace elements and their accumulation or depletion in the body. The dialysate concentrate and water used for preparing the dialysate may be an important source of the accumulation or depletion of trace elements in dialyzed patients. The gain or loss of trace elements during dialysis depends on the gradient between the ultrafiltrable fraction of a particular element in serum and its concentration in the dialysis fluid, and also on the type and permeability of the dialysis membrane. There are some methodological problems concerning the handling and storing of blood samples and measurement techniques leading to the rather inconsistent results of different studies concerning trace elements in renal disease. Geographical variations and environmental contamination of soil and water and different dietary habits may significantly influence trace elements in these patients. The abnormalities of trace elements are primarily the result of uremia, and they may be further modified and sometimes greatly exacerbated by the dialysis procedure.

Artifacts↗

PubMed1999

Trace elements in end-stage renal disease. 2. Clinical implication of trace elements.

For human beings trace elements are essential nutrients with a gamut of functions. They are for instance indispensable components of many enzymes, so they have some regulatory functions and they may affect immune reactions and free radical generation. Abnormalities of trace elements are primarily the result of uremia, and they may be further modified and sometimes greatly exacerbated by the dialysis procedure. The role of trace elements in hemodialysis (HD) patients has not yet been fully characterized. To prevent some complications in chronic HD patients, it is very important to regulate the levels of trace elements by adequate water treatment. Reverse osmosis is able to prevent the accumulation of the majority of trace elements in the patients. Zinc supplementation may be recommended for patients with proven zinc deficiency, but for all chronic renal failure patients it is questionable. Selenium deficiency is to be suspected in dialyzed patients and selenium supplementation may be beneficial (increasing glutathione peroxidase activity, cardioprotective effect, immunostimulatory properties) for chronic renal failure patients. Supplementation with a trace element may be indicated when its depletion was unequivocally documented and when there is evidence of the positive effects of this element on the quality of life of the dialyzed patients.

Chemistry Techniques, Analytical↗

PubMed1998

ICRF-187 (dexrazoxan) protects from adriamycin-induced nephrotic syndrome in rats.

BACKGROUND: Reactive oxygen species produced during metabolism of adriamycin are purported to play an important role in the pathogenesis of experimental adriamycin nephropathy in rats. ICRF-187 (dexrazoxan, Cardioxan), an iron chelator, has been shown to inhibit adriamycin-induced formation of hydroxyl radical and to decrease adriamycin cardiotoxicity in oncological patients. The aim of our study was to assess the putative protective role of ICRF-187 in adriamycin nephropathy by evaluating the possible participation of free radicals in its pathogenesis. METHODS: We examined five experimental groups. Group A, received a single dose of adriamycin (5 mg/kg bw i.v.), group CA was given a single dose of ICRF-187 (100 mg/kg bw i.v.) before adriamycin administration, group CCA received a single dose of ICRF-187 (100 mg/kg bw i.v.) before adriamycin administration followed by three weekly intraperitoneal injections (100 mg/kg bw) ICRF-187. Group CC received one dose of ICRF-187 (100 mg/kg bw i.v.) followed by three weekly intraperitoneal injections of ICRF-187, and group N served as control receiving saline. Common biochemical parameters, malondialdehyde (MDA) and antioxidant enzymes (glutathione peroxidase--GPx and superoxide dismutase--SOD) in blood and kidney homogenates were measure and histology of the kidney was studied after the rats were sacrificed. RESULTS: Full-blown nephrotic syndrome developed after 3 weeks only in A rats. Nephrotic syndrome was completely prevented in all ICRF-187 treated rats (CA, CCA). Proteinuria was significantly increased in A rats (108.2 + 48.4 mg/l of glomerular filtrate) compared with CA (12.4 + 6.8 mg/l, P < 0.0001) and with N (6.1 + 3.5 mg/l, P < 0.0001). Total MDA in erythrocytes was significantly increased only in A rats (1.7 + 0.3 micromol/l) and was completely normalized by ICRF-187 in CA (1.1 + 0.2 micromol/l, P < 0.001). Total TBARS and MDA in kidney homogenates were significantly elevated in groups with repeated administration of ICRF-187 (CC and CCA rats) compared to N, CA, A groups. Activity of GPx and SOD in kidney homogenate and in erythrocytes was not significantly increased by ICRF-187 in adriamycin treated rats. Histologic changes in A rats resembled minimal change nephropathy with fusion of foot processes and hyaline casts in tubules. There was only minimal mesangial proliferation and perivascular mast cell infiltrates in all groups of ICRF-187-treated rats. CONCLUSIONS: We conclude that ICRF-187, probably by chelation iron, completely protected rats from adriamycin-induced nephrotic syndrome. It supports the role of iron-mediated reactive oxygen species in the development of this type of glomerular injury. However, repeated administration of ICRF-187 alone is able to increase parameters of oxidative stress in the kidney.

Animals↗

PubMed1998

Retinol and alpha-tocopherol in hemodialysis patients.

The biological effects of reactive oxygen species and other radicals controlled by antioxidant mechanisms are modified by various enzymes and other substrates. Antioxidant substrates are divided into those with lipophilic and hydrophilic groups. Retinol and tocopherol are the main representations of lipophilic antioxidants. The aim of the present study was to describe the changes of retinol and alpha-tocopherol which occurred in hemodialysis (HD) patients in respect to the influence of antioxidant systems. The experimental group consisted of 14 patients on regular HD treatment. The control group consisted of 14 healthy blood donors. HPLC was used to measure retinol and alpha-tocopherol in serum. We found that the retinol concentration was significantly higher in HD patients compared to controls (2.35 +/- 0.95 versus 0.90 +/- 0.23 mg/L, p < 0.0001). The concentration of alpha-tocopherol in serum was not different in both study groups (7.32 +/- 3.01 versus. 8.94 +/- 3.57 mg/L). A review of the MEDLINE database since 1985 found a few references concerning these important antioxidant vitamins in HD patients and these contained contrasting results. It has been suggested that some of the complications related to HD including cardiovascular complications, anemia and atherosclerosis may be due to ineffective antioxidant systems and/or to increased free oxygen radical production. The question about supplementation of antioxidants in HD patients is open although there are some positive data regarding the use of moderate and safe selenium supplementation in HD patients. HD patients treated by erythropoietin had increased plasma concentration of retinol and normal level of alpha-tocopherol compared to healthy group. However, this positive finding did not affect lipid peroxidation, which is increased in HD patients and leads to some complications during HD treatment.

Adult↗

PubMed1990

[Kidney involvement in cryoglobulinemia].

The authors provide the reported data on renal impairment in mixed cryoglobulinemia (CGE) and 3 own CGE case reports. Renal impairment by the type of rapid-progressing nephritis with episodes of acute renal failure was the major sign in the clinical picture of those cases.

Adult↗