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Biomedical subjects

I Cepelak

Publications and source records attributed to I Cepelak.

At least 19 recordsLinked to original sources
PubMed2001

Magnesium concentration in plasma, leukocytes and urine of children with intermittent asthma.

BACKGROUND: Magnesium (Mg) is involved in numerous physiological functions, including protein folding, intracellular signalling and enzyme catalysis. It acts as a smooth muscle relaxant. We decided to test changes of total Mg concentration in plasma, leukocytes and urine of 16 healthy children and 26 patients with intermittent asthma aged 3 to 14 years. METHODS: Samples were taken on the first day of broncho-obstruction and five days after the acute attack. During this period, patients were under salbutamol therapy. RESULTS: Plasma Mg concentration in patients increased by about 40% (first day 0.58+/-0.05 mmol Mg/l and five days later 0.64+/-0.04 mmol Mg/l) compared with healthy children (0.42+/-0.04 mmol Mg/l). Leukocyte Mg concentrations showed significant changes. On the first day of broncho-obstruction, Mg in leukocytes significantly decreased by about 60% (1.16+/-0.31 mmol Mg/g protein) compared to healthy children (3.04+/-0.68 mmol Mg/g protein). Five days later, Mg values significantly increased (3.28+/-1.09 mmol Mg/g protein) and almost reached the values of the healthy group. Mg concentration in urine statistically decreased by about 30% (0.55+/-0.06 mmol Mg/mmol creatinine) on the first day of broncho-obstruction compared to healthy children (0.75+/-0.05 mmol Mg/mmol creatinine). Five days after the acute attack, Mg concentration in patients' urine (0.73+/-0.07 mmol Mg/mmol creatinine) was close to values of healthy children. CONCLUSION: The results obtained indicate that the intracellular measurement of Mg concentration is relevant for estimation of magnesium concentration in the human organism. Hence, determination of Mg concentration in leukocytes may be used in evaluation of asthmatic pathology.

Adolescent↗
PubMed2000

Studies of ochratoxin A-induced inhibition of phenylalanine hydroxylase and its reversal by phenylalanine.

Ochratoxin A (OTA) is a nephrotoxic, hepatotoxic, and teratogenic mycotoxin produced by storage molds on a variety of foodstuffs. Its chemical structure is composed of an isocumarin part linked to l-phenylalanine. Inhibition of phenylalanine hydroxylase and other enzymes that use phenylalanine as substrate is based on this structural homology. We have examined the effects of low doses of ochratoxin A on the activity of phenylalanine hydroxylase in kidney and in liver of experimental animals. Daily administration of ochratoxin A (50 microg/kg body wt, for 10 and 35 days, respectively) caused a significant reduction in the phenylalanine hydroxylase activity. Inhibition was more pronounced in liver than in kidney, although actual ochratoxin A concentration was higher in the kidney tissue. We observed an apparent increase in the affinity of phenylalanine hydroxylase for substrate following OTA administration to animals. However, simple competitive inhibition was observed for both tissues in vitro (K(i liver) = 0.0119 +/- 0.002 mM and K(i kidney) = 0.13 +/- 0.026 mM). Simultaneous application of ochratoxin A with phenylalanine could reduce inhibition of phenylalanine hydroxylase, in particular in liver. Enzyme activity was almost completely preserved after 35 days of combined treatment. The results obtained suggest that daily administration of ochratoxin A in low doses produced an inhibitory effect that could be diminished by competitive action of l-phenylalanine.

Animals↗
PubMed1999

External quality assessment in clinical chemistry: review of the situation in Croatia with particular reference to equipment.

The effect of the use of new flame photometers (Ciba Corning 480, Chiron, Salzburg, Austria) and multichannel analyzers (BM Hitachi 904 or BM Hitachi 911, both Boehringer GmbH, Mannheim, Germany) on analytical quality was assessed in a number of medical biochemical laboratories (n=58) at health centers and general hospitals that provide primary health care services for the respective catchment areas. The laboratories were supplied during 1996 and 1997 with new equipment, as part of the First Croatian Health Project, Primary Health Care Subproject, carried out by the Croatian Ministry of Health and Croatian Institute of Health Insurance. We evaluated analytical performance of these laboratories for 19 analytes, according to the results reported in the Croatian External Quality Assessment Program for medical biochemical laboratories, performed four times per year. Changes of percentages of particular methods used by the participating laboratories were observed for inorganic phosphate, total bilirubin, urea and creatinine. Such changes were even more pronounced for enzymes, where changes in the measurement procedure such as incubation temperature and buffers were observed in the methods used. Evaluation of method performance revealed that after the introduction of new equipment interlaboratory variation decreased, so that an increasing proportion of laboratories included in the Project produced results within the target limits.

Chemistry, Clinical↗
PubMed1998

Valproate and carbamazepine comedication changes hepatic enzyme activities in sera of epileptic children.

Previous observation that valproic acid (VPA) and carbamazepine (CBZ) caused hepatic damage prompted us to investigate the effects of VPA or CBZ monotherapy and VPA + CBZ comedication on the number of hepatic enzyme activities in sera of epileptic children. This study compares alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) activities in sera of children treated with VPA (n=42), or CBZ (n=36) taken as a monotherapy, with VPA + CBZ combined therapy (n=36). The effect of VPA alone is greater on the activity of AST than on other enzymes, while CBZ therapy changes primarily the activities of GGT. The mean catalytic activity of AST was significantly elevated in groups on VPA, CBZ and VPA + CBZ treatment (2.02-, 1.49- and 1.45-fold increase, respectively) as compared to the control values. Changes in the ALT activity followed different patterns. The maximal increase was observed in the CBZ group with a smaller increase in the group on VPA + CBZ polytherapy, whereas only 15% of patients receiving VPA showed an average 1.38-fold increase of the mean enzyme activity. Increase in the catalytic activity of GGT probably reflects the induction produced by the CBZ treatment, either alone or in combination. Children on CBZ monotherapy showed an increase of mean catalytic activity of about twofold in 56% of patients. Children on VPA + CBZ comedication showed a similar behaviour, while VPA alone produced a moderate (1.44-fold) increase in 23% of children. However, concentrations of VPA and CBZ in sera of patients receiving monotherapy were within the expected therapeutic limits, whereas subtherapeutic levels of VPA were found in 30% of children on VPA + CBZ comedication. We propose that individual dosage adjustment in VPA + CBZ polytherapy should be combined with monitoring of relevant enzyme activities in serum.

Adolescent↗
PubMed1996

Influence of ochratoxin A treatment on the activity of membrane bound enzymes in rat brain regions.

Ochratoxin A is a mycotoxin produced by Aspergillus ochraceus and is a natural contaminant of mouldy food. We examined the neuroactive potential of ochratoxin A by measuring the changes in the activities of several membrane bound, cytoplasmic and lysosomal enzymes in the brain of adult female rats, following subchronic application of ochratoxin A. The activities of both soluble and membrane bound fractions of ecto-5'nucleotidase, ecto-Ca2+/Mg2+ATPase, alanine aminopeptidase, gamma-glutamyl transferase, as well as activities of lactate dehydrogenase and of N-acetyl-beta-D-glucosaminidase were followed. Biochemical effects were examined in cerebral cortex, cerebellum and hippocampus. The results obtained showed physiologically significant alterations in the activity of enzymes tested. The changes were found to be time-dependent and regionally selective. Compared to controls, statistically significant increases in gamma-glutamyl transferase were observed in all three brain regions, while in the case of alanine aminopeptidase activities differed with regard to region, the highest increase being observed in hippocampus. Ecto-Ca2+/Mg2+ATPase and ecto-5'nucleotidase showed distinct changes lasting for 20 days of treatment, while increase in the activities of N-acetyl-beta-D-glucosaminidase and lactate dehydrogenase were visible only at the beginning of the treatment. By the end of the trial the activities of almost all enzymes returned back to normal values.

Animals↗
PubMed1995

Effect of sodium valproate on renal cell brush-border enzymes in rats.

The effect of sodium valproate (200 mg/kg body weight) on renal cells was investigated during a 10-day trial, by determining the catalytic activities of alanine aminopeptidase, gamma-glutamyltransferase and alkaline phosphatase in the membrane cell brush-border of the renal proximal tubules. Four days after the administration of sodium valproate, a significant increase was observed in the volume of urine (9.2 +/- 4.2 ml/18-h volume; control group, 3.06 +/- 1.8 ml/18-h volume), and in the catalytic activities of gamma-glutamyltransferase (2.69 times that measured in the control group) and alkaline phosphatase (3.02 times that measured in the control group) in urine. After prolonged treatment the urine became alkaline (pH = 10.5 on day 10), thereby excluding alanine aminopeptidase as a useful indicator of renal cell changes following the administration of sodium valproate. The activities of alkaline phosphatase and gamma-glutamyltransferase in isolated vesicles of renal brush-border membrane cells were significantly increased (p < 0.05) and decreased, respectively. On the basis of the results obtained, we believe that the determination of the catalytic activities of gamma-glutamyltransferase and alkaline phosphatase in urine might prove useful for the follow-up of the renal cell state during therapy with sodium valproate.

Alkaline Phosphatase↗
PubMed1995

Ochratoxin A impairs activity of the membrane bound enzymes in rat pancreas.

Ochratoxin A is a mycotoxin produced by Aspergillus ochraceus and is a natural contaminant of moldly food. Ochratoxin A has a number of toxic effects, some of which may be related to the changes in the cell membrane. We measured the activities of 5 pancreatic, membrane bound enzymes in female Fisher rats that were given low oral doses of ochratoxin A (120 micrograms/kg body weight per day) during 20-35 days. The amount of toxin corresponds to 1.5 mg/kg in the feed, daily. These doses are in the range of natural contamination found in feed. The enzymes studied were alanine aminopeptidase, alkaline phosphatase, ecto-Ca2+/Mg(2+)-ATPase, gamma-glutamyl transferase and ecto-5'-nucleotidase. Treatment lasting 20 days caused a strong decrease in the activity of alanine aminopeptidase, Ca2+/Mg(2+)-ATPase and alkaline phosphatase to 0.76 +/- 0.04, 0.53 +/- 0.03 and 0.30 +/- 0.02 of the control values, respectively (p < 0.05). No significant changes in the activity of gamma-glutamyl transferase and 5'-nucleotidase were observed. However, activity of alanine aminopeptidase returned to normal values after 35 days of treatment, suggesting an adaptation of the organism, or a substitution of a released enzyme. Activities of alkaline phosphatase and Ca2+/Mg(2+)-ATPase remained significantly reduced to 0.42 +/- 0.03 and 0.52 +/- 0.04, respectively (p < 0.01). We conclude that treatment of rats with low doses of ochratoxin A resulted in reduction of the activities of the membrane bound enzymes, most probably by inducing their release, as a result of the impairment of the functional integrity of cell membranes.

5'-Nucleotidase↗
PubMed1992

Arginase, a new marker of mammary carcinoma.

Activities of arginase, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase were determined in sera obtained in a group of healthy women, women with verified carcinoma of the breast, benign mastopathy, a group of patients with carcinoma of various organs and a group of patients with acute viral hepatitis. Preoperative values of serum arginase activity in patients with breast carcinoma were up to 4-fold those found in healthy women. Sensitivity of the test was 86%. After the surgery, the activity decreased abruptly during the first week and normalised within 15-30 days. In benign diseases of the breast, the activity of arginase was normal. Serum arginase activity is raised in both benign and malignant liver diseases, however, the quotients alanine aminotransferase/arginase, aspartate aminotransferase/arginase and alkaline phosphatase/arginase differ significantly. Thus, use of alanine aminotransferase/arginase quotient implies a high degree of confidence in differentiating between increased arginase activity in mammary carcinoma (alanine aminotransferase/arginase = 0.572 +/- 0.278) and high arginase activity in hepatitis (alanine aminotransferase/arginase = 12.226 +/- 1.822).

Adult↗
PubMed1991

Effect of ochratoxin A on brush border enzymes of rat kidney.

Ochratoxin A was given orally at 60 microgram/kg body weight in neutral olive oil to Fischer rats for 30 days, at which time they were killed. Clinical state, weights of animals and of their organs and urea and creatinine concentrations were not affected during the exposure period. Significant increases in the activity of enzymes in urine were found: 60% increase in alanine aminopeptidase, 45% increase in gamma-glutamyl-transferase and 90% increase in alkaline phosphatase. These changes indicate early pathological changes in the kidney. Relatively small amounts of the toxin thus affect kidney membrane cells.

Alkaline Phosphatase↗
PubMed1990

Multiple forms of gamma-glutamyltransferase and lipoproteins.

The gamma-glutamyltransferase isoenzyme patterns originating from human serum and homogenates of liver, kidney, pancreas and intestine in the presence and in absence of isolated lipoproteins has been studied. On the basis of these results one can conclude that the distribution of a variety of gamma-glutamyltransferase activities obtained by the electrophoresis of blood serum is not a consequence of an existence of a large number of true isoenzymes, but of increased concentrations of lipoproteins which bind to the enzyme thus causing the appearance of gamma-glutamyltransferase in the region of the appropriate lipoproteins.

Humans↗
PubMed1989

Changes of activities of some transferases, alkaline phosphatase and cholinesterase in the blood of women using oral contraceptives and in vitro influence of these agents on tissular enzyme levels in rat liver.

Aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, and alkaline phosphatase activities in the blood serum of women taking the oral contraceptive preparation Microgynon through extended periods were raised; the activity of cholinesterase was simultaneously reduced. In rats liver homogenates ethynylestradiol, one of the active components of Microgynon, acted as an inducer of gamma-glutamyltransferase and alkaline phosphatase while leaving aspartate aminotransferase and alanine aminotransferase unaffected, but reduced the level of cholinesterase. Norgestrel, the other active component of the preparation, suppressed the biosynthesis of gamma-glutamyltransferase and alkaline phosphatase while leaving aspartate aminotransferase, alanine aminotransferase and cholinesterase levels unaffected. A mixture of ethynylestradiol plus norgestrel in the mass proportion occurring in Microgynon produced the same effects upon gamma-glutamyltransferase and alkaline phosphatase as ethynylestradiol alone. Estradiol, the parent hormone of ethynylestradiol, lacked the inducing capability of the latter while ethynylpropargyl chloride induced gamma-glutamyltransferase and alkaline phosphatase so it was concluded the inducing effect of ethynylestradiol must be ascribed to the ethynyl radical. Progesterone, the parent of norgestrel, shared the latter's suppressive activity for gamma-glutamyltransferase and alkaline phosphatase biosynthesis, and behaved like its derivative towards the other enzymes.

Adult↗
PubMed1986

Effects of neuroleptic phenothiazines on the activities of aminotransferases and gamma-glutamyltransferase in serum and liver.

Serum alanine aminotransferase, aspartate aminotransferase and gamma-glutamyltransferase activities were monitored in psychiatric patients receiving normal doses of phenothiazine neuroleptics over a 30-day period. The first two enzymes showed slight initial increases and a subsequent return to normal, while the third showed a slight increase. In rats, dosage levels exceeding those used in human therapy produced much larger increases in the catalytic concentrations of all three enzymes in serum (1.4, 0.7 and 0.5 above the control value, respectively), and somewhat smaller increases in the liver homogenates of these animals.

Animals↗
PubMed1982

Immunoregulatory activity of cell-free peritoneal washings of mice with Ehrlich ascitic carcinoma.

Cell-free peritoneal washings (PW) were collected from mice with Ehrlich ascitic carcinoma at various time intervals after tumor transplantation and tested on the immunosuppressive activity in vitro. Two assays were used: (1) stimulation of human peripheral blood lymphocytes by phytohemagglutinin (PHA) and (2) inhibition of human leukocyte migration with PPD. Fluids collected in the early phase of tumor growth (up to day 6) were ineffective, or weakly suppressive, and those collected in advanced and terminal stages of carcinoma development, were suppressive in both tests applied. Control cell-free peritoneal washings obtained from normal mice without the tumor exerted suppressive activity when adjusted to the same protein concentration as the PW from mice with Ehrlich carcinoma. This suggests that host's cells in tumor-bearing animals, rather than tumor cells themselves, may be responsible for the production of inhibitory substance(s). Cell-free peritoneal washings were also tested on their ability to influence the growth of Ehrlich carcinoma cells in vitro, as measured by 3H-thymidine incorporation. Samples collected from mice with advanced tumors stimulated the growth of tumor cells.

Animals↗
PubMed1981

Effect of sodium tetrathionate on the activities of some enzymes in kidney and urine.

The activities of lactate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase, beta-galactosidase, N-acetyl-beta-D-glucosaminidase, leucine aminopeptidase, gamma-glutamyltransferase and alkaline phosphatase in renal tissue and urine of rats treated with sodium tetrathionate were determined. A decrease of enzyme activities in renal tissue and an increase in urine were observed. The largest decrease in the glutamate dehydrogenase of renal tissue amounted to 0.7 times the control value, and was correlated with an appropriate increase in the urine. Increases in urinary enzyme activity were especially marked for beta-galactosidase and N-acetyl-beta-D-glucosaminidase (3 and 6 times the control values, respectively). The increase in enzyme activities was not accompanied by a corresponding change in the urinary protein. Characterization of urinary lactate dehydrogenase and N-acetyl-beta-D-glucosaminidase isoenzymes also indicates the renal origin of these enzymes. The abnormally high enzyme activities of the urine correlated with the nature and degree of renal damage shown by electron microscopy.

Acetylglucosaminidase↗