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Biomedical subjects

E Marklová

Publications and source records attributed to E Marklová.

At least 19 recordsLinked to original sources

Genetic variants of transferrin in the diagnosis of protein hypoglycosylation.

Human transferrin (Tf) shows genetic polymorphisms, which may interfere in the screening of congenital disorders of glycosylation (CDG). Isoelectric focusing followed by direct immunofixation was used for Tf analysis in controls and several groups of patients. Equivocal results in one case have been recognized as a rare Tf CD variant. A higher incidence of some genetic variants has been reported in connection with certain diseases; of the seven Tf phenotypes detected in our set of samples, an apparently higher frequency of Tf C1C2 variant found in some groups of patients was not significant.

Adolescent↗

Genetic aspects of diabetes mellitus.

Practically all types of diabetes mellitus (DM) result from complex interactions of genetic and environmental factors. Multifactorial and polygenic Type 1 DM is strongly influenced by genes controlling the immune system, mainly HLA-DQ and DR. In addition to this, many other predisposition loci, interacting with each other, have some influence on susceptibility to DM. Heterogeneous Type 2 DM, accounting for about 85% of all diabetic patients, is supposed to be induced by multiple genes defects involved in insulin action and/or insulin secretion. Other genetically influenced traits like obesity and hyperlipidemia are strongly associated with the Type 2. The group called Other specific types of DM include monogenic forms MODY 1-5 and many various subtypes of the disease, where the specific gene mutations have been identified. Both genetic and intrauterine environmental influences are likely to contribute to the abnormalities defined as Gestational DM.

Diabetes Complications↗

[Clinical picture of homocystinuria with cystathionine beta-synthase deficiency in 19 Czech and Slovak patients].

BACKGROUND: Homocystinuria due to cystathionine beta-synthase deficiency is an autosomal recessive disorder of methionine metabolism. It manifests with vascular, central nervous system and connective tissue disturbances, and phenotypically resembles Marfan's syndrome. We analysed the clinical course of homocystinuria in Czech and Slovak patients. METHODS AND RESULTS: The group of homocystinuric patients consisted of 19 individuals (12 males and 7 females) aged 5-32 years (average age 18 years), who were diagnosed between 1980 and 1999. The overall incidence of homocystinuria in the Czech and Slovak Republics was 1:287,000. The proportion of pyridoxine-responsive patients was 47%. The average follow-up period was 10 years (range 1 month to 19 years). The prevalence of the individual signs in the group was as follows: lens dislocation--95% of patients, progressive myopia--79%, marfanoid habitus--74%, kyfoscoliosis--68%, osteoporosis--63%, psychomotor retardation--58%, other neurologic symptomatology--58% and tromboembolism--21%. The average delay between the first sign of the disease and the time when the diagnosis was made was 4 years (range 1 to 14 years). At the time of diagnosis the average levels of metabolites in plasma were as follows: total homocysteine 348 mumol/l (range 211-536), free homocystine 70 mumol/l (range 0-203) and methionine 359 mumol/l (range 75-937). CONCLUSIONS: Both the clinical course of homocystinuria due to the cystathionine beta-synthase deficiency and its incidence in the Czech and Slovak Republics are similar to those in other populations. Since homocystinuria is a treatable disease, it should be included in the differential diagnosis of Marfan's syndrome, tromboembolism and severe psychomotor retardation.

Adolescent↗

Screening for defects in tryptophan metabolism.

We introduced a two-step procedure for the detection of defects in metabolism of tryptophan: (1) HPTLC (described previously) is suitable when starting the investigation, (2) two HPLC methods with isocratic elution and spectrophotometric detection are used at the next step, when pathological findings are to be confirmed and the individual metabolites quantified. The first method enables the assessment of tryptophan, 5-hydroxyindolylacetic acid, indolylacetic acid, indolylacryloylglycine, indolylacrylic acid and its possible precursors, namely indolyllactic and indolylpropionic acids. The second procedure is intended for the monitoring of anthranilic, 3-hydroxyanthranilic, kynurenic and xanthurenic acids, kynurenine, 3-hydroxykynurenine and indoxyl-sulfate. The same pre-treated sample is used for all methods.

Amino Acid Metabolism, Inborn Errors↗

Metabolism of tryptophan in the liver: interference with decarboxylation of other aromatic amino acids.

Decarboxylation of aromatic amino acid in mammalian tissues is catalyzed by aromatic amino acid decarboxylase (EC. 4.1.1.28, AAD). The enzyme differs in its affinity to individual aromatic amino acids, the best substrates being 3,4-dihydroxyphenylalanine (dopa) and 5-hydroxytroptophan. Surprisingly, AAD is abundant in the liver, where the substrates with rather low affinity to AAD as tryptophan, phenylalanine, and tyrosine are offered to decarboxylation. In the present paper, the possibility of interference of tryptophan with decarboxylation of phenylalanine, tyrosine as well as dopa in the liver was investigated. The AAD activity was measured radiometrically with 1-14C-labeled aromatic amino acid substrates using the rat liver enzyme. The influence of tryptophan on decarboxylation of tyrosine was formally competitive with Ki = 9.2 x 10(-3) M, while the inhibition of decarboxylation of phenylalanine by tryptophan was non-competitive with Ki at 2.75 x 10(-2) M. The effect of tryptophan on decarboxylation of dopa was small and it could not be expressed in terms of inhibition kinetics and inhibition constant. At physiological concentrations of aromatic amino acids in plasma, tryptophan does not seem to have remarkable effects on decarboxylation of phenylalanine, tyrosine, and dopa in the liver.

Amino Acids↗

Where does indolylacrylic acid come from?

In addition to the main catabolic routes of tryptophan (Trp), there exist minor and less thoroughly investigated pathways; one of these leads to indolylacrylic acid (IAcrA). IAcrA is a plant growth hormone, whereas its biological role in animals is still obscure, as is the way and site where it is formed in the organism. A two-stage production is likely: Intestinal microorganisms catabolize Trp to indole derivatives which are then absorbed and converted to IAcrA and its glycine conjugate, indolylacryloylglycine (IAcrGly). Our finding of IAcrGly in the urine of proven germ-free piglets points to the possibility that Trp can be converted to IAcrA without the intervention of intestinal microorganisms. Seasonal and age variations, influence of light and connection with photodermatoses have been reported. Besides other pathological conditions the differences in IAcrGly excretion relative to normal controls were especially pronounced in some myopathies, namely in boys with Duchenne muscular dystrophy.

Aging↗

Screening for organic acid disorders.

The detection of organic acidurias is a part of our screening programme for inherited metabolic diseases. Adapted procedure is differentiated and involves several steps: 1) thin-layer chromatography (TLC) in the case of an abnormal finding followed by 2) gas chromatography (GC). The next step of the investigation, using 3) gas chromatography mass-spectrometry (GS-MS) is reserved for more complicated and dubious analyses. In acutely sick patients and in the case of discrepancies between TLC results on the one hand, and clinical symptoms, supported by other laboratory findings on the other, the GC or GC-MS-analysis is performed immediately. Some examples of metabolic disorders, identified by this procedure, are presented.

Acids↗

High-performance liquid chromatographic profiling of indolylacryloylglycine and its possible precursors in body fluids.

Indolylacryloylglycine (IAcrGly) is one of the physiological components of urine, although its source and its role in the human organism have not yet been unambiguously established. Changes in the IAcrGly excretion level have been found under some physiological (age dependence, seasonal variations) and pathological (photodermatoses, muscle dystrophy, liver cirrhosis) conditions. The proposed method for IAcrGly, indolylacrylic acid and its possible precursors, namely indolyllactic and indolylpropionic acids, involves deproteinization and extraction of urine on a Sep Pak C18 cartridge. HPLC analysis was carried out using a DataApex liquid chromatograph, equipped with an LCD 2082 UV detector, signals being acquired with a CSW workstation. The chromatographic column was Spherisorb ODS, 5 microns (125 x 4 mm I.D.), the mobile phase for isocratic elution was ethanol-1% acetic acid (27:73) and the flow-rate was 0.7 ml/min. The lower response limit is about 1 mumol/l for all metabolites at 280 nm.

Chromatography, High Pressure Liquid↗

Screening for biotinidase deficiency in some skin diseases.

Biotinidase deficiency is an inherited, autosomal recessive disorder involving gluconeogenesis, synthesis of fatty acids and catabolism of branched chain amino acids. As the cutaneous manifestations have been described to be a prominent part of the clinical picture, we tested a group of children and adults with various skin lesions. The blood-spot screening test was repeatedly (new disc and new card) positive in some patients suffering from psoriasis and atopic eczema. The quantitative assay does not confirm the decrease of serum biotinidase activity. Some alternative explanations of these results are put forward.

Adolescent↗

Urinary excretion of indolylacryloylglycine, indolylacetic acid and 5-hydroxyindolylacetic acid in burn patients.

Indolylacryloylglycine (IAcrGly) is a regular constituent of human urine. Changes in its excretion have been observed, among other conditions, in some skin diseases. Skin lesions in burns are dealt with in the present paper. IAcrGly excretion has been followed during several weeks of hospital treatment and compared with that of two other tryptophan metabolites, namely indolylacetic acid (IAA) and 5-hydroxyindolylacetic acid (5-HIAA). The average excretion of IAcrGly was significantly lower especially between day 3 and 15 post injury. Some alternative explanations of these results are put forward.

Adolescent↗

Urinary excretion of some metabolites of tryptophan in malignant diseases.

The urinary excretion of four tryptophan metabolites, namely indolylacryloylglycine, indolylacetic, 5-hydroxyindolylacetic and 3-hydroxyanthranilic acids, was studied in two control groups, in children suffering from acute leukemia, hepatic and brain tumours and in adults with bladder cancer. Compared with controls, a significantly lower excretion of IAcrGly was observed in all patient groups with the exception of that with hepatic tumours. Hematological malignancies were further accompanied by low excretion of indolylacetic acid, and bladder cancers by a lower 5-hydroxyindolylacetic acid level. We found no correlation of the metabolites tested in individuals of any patient group. In controls, however, indolylacryloylglycine and indolylacetic acid did correlate.

Adolescent↗