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V Kozich

Publications and source records attributed to V Kozich.

At least 19 recordsLinked to original sources
PubMed2002

Methionine-loading test: evaluation of adverse effects and safety in an epidemiological study.

BACKGROUND: Methionine loading test is commonly used to detect hyperhomocysteinemia in patients with arteriosclerosis and other conditions. As administration of methionine causes endothelial dysfunction in laboratory examinations, we explored whether loading with this compound leads to clinically relevant adverse effects, especially in vasculature. METHODS AND RESULTS: When studying genetic factors in arteriosclerosis we recorded acute complications during a standard methionine loading test (with a dose of 100 mg/kg bw) and assessed a 30-day mortality in a group of 296 patients with coronary artery or peripheral arterial disease and in 591 controls. Acute complications were observed in 33% of the women and 16.5% of the men. For each sex, the patients and controls exhibited the same proportion of complications. The most common symptom, dizziness, was attributable to methionine loading. In addition, isolated sleepiness, nausea, polyuria and decreased or increased blood pressure were observed in part of the subjects. None of the 887 individuals died within the 30-day period following the test. CONCLUSION: Our study suggests that although standard loading with L-methionine frequently causes transitory complications impairing perception and vigilance, the test does not have serious adverse effects on vasculature and may be considered a safe procedure.

Arteriosclerosis↗
PubMed2001

[Metabolic complications and neurologic manifestations of vitamin B12 deficiency in children of vegetarian mothers].

BACKGROUND: Serious hematological, metabolic and neurological complications owing to the nutritional deficiency of vitamin B12 may occur in infants of mothers on a strict vegetarian diet. METHODS AND RESULTS: The mother of the first child was a strict vegetarian. She had an elevated urinary methylmalonic acid level and a low concentration of serum vitamin B12. Her 13-month-old daughter was exclusively breast-fed until the age of 9 month and then she was fed only vegetables. Physical examination revealed psychomotoric retardation, apathy, muscular hypotonia, abnormal movements and failure to thrive. Laboratory analysis showed a megaloblastic anaemia, a low level of vitamin B12 and methylmalonic aciduria. MRI of the brain revealed diffuse frontotemporoparietal atrophy and retardation of myelination. After treatment with vitamin B12 supplements, abnormal movements disappeared and development improved, but a mild generalised hypotonia continued. A cranial MRI 9 months after treatment still showed signs of retardation of myelination. The second patient, an 8 month-old male, son of a strict vegetarian mother too, was referred for investigation of psychomotoric retardation, hypotonia, dyskinesia, failure to thrive and microcephaly. He was breast-fed and from 6 month of age he had also received fruit juices. Laboratory analysis revealed megaloblastic anaemia, high methylmalonic aciduria and homocystinuria. The patient's and his mother's serum level of vitamin B12 were low. After treatment with vitamin B12 supplements, biochemical and metabolic markers of disease were normal but there continued a generalised hypotonia, microcephaly and language delay. CONCLUSION: Our observations emphasize the health complications of nutritional cobalamine deficiency and a requirement of clinical, biochemical and metabolic monitoring in infants within strict vegetarian families.

Anemia, Megaloblastic↗
PubMed2001

Association of the Glu298Asp polymorphism in the endothelial nitric oxide synthase gene with essential hypertension resistant to conventional therapy.

Endothelial nitric oxide synthase (eNOS) produces nitric oxide (NO) which, after diffusing into vascular smooth muscle cells, activates guanylate cyclase leading to vasodilatation. A polymorphism (894G to T) in exon 7 of the eNOS gene causes the conversion of Glu to Asp in position 298. The recently described crystal structure of the heme domain of eNOS protein shows that Glu298 is fully solvent accessible and distant from regions integral to enzyme function. Searching for phenotypic expression of eNOS gene variants, we genotyped a group of patients with essential hypertension (H, n = 119) for the Glu298Asp polymorphism and compared them with age- and sex-matched healthy normals (N, n = 85). To specify phenotypic expression further, the hypertensive patients were subdivided into one group that responded well to regular antihypertensive therapy (CH, n = 45) and one group that was resistant to the therapy (RH, n = 74). Patients with BP higher than 140/90 mmHg when on adequate lifestyle modification and triple-combination therapy (including diuretics) were considered resistant. In RH and H groups, a significantly higher frequency of T alleles (P = 0.022 and P = 0.046, respectively) was found compared to normotonics (N). In well-controlled hypertonics, the same tendency was found, but did not reach statistical significance. The Glu298Asp polymorphism may contribute to the complex pathogenesis of essential hypertension and may be a factor in the resistance of these patients to conventional antihypertensive therapy. The presence of this allele may thus be predictive of the patients' therapeutic response.

Adrenergic beta-Antagonists↗
PubMed2001

Impaired heme binding and aggregation of mutant cystathionine beta-synthase subunits in homocystinuria.

During the past 20 years, cystathionine beta-synthase (CBS) deficiency has been detected in the former Czechoslovakia with a calculated frequency of 1:349,000. The clinical manifestation was typical of homocystinuria, and about half of the 21 patients were not responsive to pyridoxine. Twelve distinct mutations were detected in 30 independent homocystinuric alleles. One half of the alleles carried either the c.833 T-->C or the IVS11-2A-->C mutation; the remaining alleles contained private mutations. The abundance of five mutant mRNAs with premature stop codons was analyzed by PCR-RFLP. Two mRNAs, c.828_931ins104 (IVS7+1G-->A) and c.1226 G-->A, were severely reduced in the cytoplasm as a result of nonsense-mediated decay. In contrast, the other three mRNAs-c.19_20insC, c.28_29delG, and c.210_235del26 (IVS1-1G-->C)-were stable. Native western blot analysis of 14 mutant fibroblast lines showed a paucity of CBS antigen, which was detectable only in aggregates. Five mutations-A114V (c.341C-->T), A155T (c.463G-->A), E176K (c.526G-->A), I278T (c.833T-->C), and W409_G453del (IVS11-2A-->C)-were expressed in Escherichia coli. All five mutant proteins formed substantially more aggregates than did the wild-type CBS, and no aggregates contained heme. These data suggest that abnormal folding, impaired heme binding, and aggregation of mutant CBS polypeptides may be common pathogenic mechanisms in CBS deficiency.

Adolescent↗
PubMed2001

Cystathionine beta-synthase deficiency in Central Europe: discrepancy between biochemical and molecular genetic screening for homocystinuric alleles.

Recent reports suggested that homocystinuria due to cystathionine beta-synthase (CBS) deficiency is a more common inborn error of metabolism than originally thought. In this study we compared the prevalence of homocystinuric alleles ascertained by two different approaches. First, the incidence of homocystinuria estimated by selective biochemical screening in the Czech and Slovak Republics was 1:349,000 (95% CI 1:208,000-1:641,000). The two most common pathogenic mutant alleles found subsequently in these patients, IVS11-2A>C and c.833T>C, had a calculated population prevalence of 0.00042 (95% CI 0.00031-0.00055) and 0.00018 (95% CI 0.00013-0.00023), respectively. Second, to examine the possible negative detection bias of mildly affected patients we determined the prevalence of these two pathogenic mutations in a sample of 1284 unselected newborns. Indeed, the observed prevalence of the c.833T>C allele (0.00195, 95% CI 0.00063-0.00454) was 11x higher than in the previous group suggesting that many homozygotes for the c.833T>C had not been diagnosed by selective biochemical screening. The IVS11-2A>C allele was not detected among 2,568 newborn CBS alleles. The estimated incidence of homocystinuria of 1:83,000, calculated in a combined model, suggests that selective biochemical screening may ascertain only approximately 25% of all homocystinuric patients. In conclusion, homocystinuria in Central Europe may be sufficiently common to consider sensitive newborn screening programs for this disease.

Alleles↗
PubMed2001

Haplotyping of wild type and I278T alleles of the human cystathionine beta-synthase gene based on a cluster of novel SNPs in IVS12.

Homocystinuria is most frequently due to deficiency of cystathionine beta-synthase (CBS). We identified IVS12 as a polymorphism hot spot of the human CBS gene and report five novel single nucleotide polymorphisms (SNPs): g.13514G>A, g.13617A>G, g.13715C>T, g.13800G>A, and g.13904C>T. Analyzing 50 control DNA samples of unaffected and unrelated subjects of German origin the observed frequencies of heterozygosity were 0.02, 0.36, 0.18, 0.36, and 0.36, respectively. These polymorphic markers were combined into four distinct IVS12-haplotypes A1, A2, B1, and B2, revealing frequencies of 0.75, 0.01, 0.15, and 0.09, respectively, with an observed overall frequency of heterozygosity at 0.38. This haplotype system and the SNP c.699 were employed in the analysis of ten alleles affected by the most prevalent CBS mutation, c.833T>C (exon 8; I278T). We found that the I278T alleles segregate with at least two distinct haplotypes characterized by upstream and downstream polymorphic sites instead of sharing a common ancestral haplotype. This was a remarkable finding even in patients with very similar ethnic background. The novel haplotype system may facilitate future studies on the evolution of the CBS gene and might be suited for genotyping of families affected by homocystinuria.

Alleles↗
PubMed2001

Folate supplementation prevents plasma homocysteine increase after fenofibrate therapy.

BACKGROUND: Homocysteine is associated with an increased risk of atherosclerosis. The administration of fibrates has been reported to significantly increase plasma homocysteine levels, a potentially adverse effect of fibrates. We investigated the hypothesis that concomitant treatment with fenofibrate and folic acid leads to a smaller increase in plasma total homocysteine levels than treatment with fenofibrate alone. METHODS: A randomized, open-label study compared the effect of micronized fenofibrate (200 mg daily) alone versus fenofibrate plus folic acid (10 mg every other day) on plasma homocysteine levels. Twenty-two patients with mixed hyperlipidemia participated. The 9-wk treatment period was preceded by a 4-wk wash-out period without hypolipidemic drugs. RESULTS: In patients treated with fenofibrate only, plasma homocysteine levels increased by 6.85 +/- 5.23 micromol/L (from 12.27 +/- 3.15 to 19.13 +/- 7.20 micromol/L); in patients treated with fenofibrate and folic acid, plasma homocysteine levels increased by 2.01 +/- 2.88 micromol/L (from 10.14 +/- 2.32 to 12.15 +/- 3.08 micromol/L). The difference in the homocysteine increase between the two groups was statistically significant at P = 0.014. CONCLUSIONS: Folic acid supplementation in patients treated with fenofibrate significantly reduced the increase in plasma homocysteine levels. More studies are needed to clarify whether amelioration of this side effect increases the clinical benefit of fibrates.

Arteriosclerosis↗
PubMed2001

Measurement of homocysteine and other aminothiols in plasma: advantages of using tris(2-carboxyethyl)phosphine as reductant compared with tri-n-butylphosphine.

BACKGROUND: Aminothiols have been implicated in the pathogenesis of arteriosclerosis, and reliable methods are needed to determine their concentrations in body fluids. We present a comparison of two analytical methods and focus on the reduction of low-molecular weight and protein-mixed disulfides of homocysteine, cysteine, cysteinyl-glycine, and glutathione. METHODS: The plasma total aminothiol profile was determined by HPLC with fluorescence detection after derivatization with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate. Disulfides and protein-bound aminothiols were reduced by either tri-n-butylphosphine (the TBP method) or tris(2-carboxyethyl)phosphine (the TCEP method); the effects of temperature, time of reduction, and concentration of reductants were evaluated. RESULTS: The intraassay imprecision (CV) was <3% for all aminothiols using both methods. The interassay CVs for total cysteine (tCys), total cysteinyl-glycine (tCys-Gly), and total homocysteine (tHcy) were <4% and <8% for the TCEP and TBP methods, respectively, whereas for total glutathione (tGSH) the interassay CV was >12% for both methods. Deming regression and Bland-Altman difference plots showed positive biases for total aminothiol concentrations determined by the TCEP method relative to the TBP method. The mean proportional biases were 65%, 27%, 6%, and 60% for tCys, tCys-Gly, tHcy, and tGSH, respectively. The calculated concentrations of total aminothiols by the TCEP method were less influenced by changes in temperature and concentration of reducing agent or by calibrator matrix. CONCLUSIONS: The agreement between the TCEP and TBP methods was considerably lower for the determination of tCys, tCys-Gly, and tGSH than for tHcy. For total-aminothiol determination, the TCEP method yields better reproducibility and is more robust than the TBP method.

Chromatography, High Pressure Liquid↗
PubMed2000

[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↗
PubMed1999

[Diagnostic significance of mild hyperhomocysteinemia in a population of children with parents or grandparents who have peripheral or coronary artery disease].

BACKGROUND: A rise of the homocysteine plasma level--mild hyperhomocysteinaemia--is considered an independent risk factor for the development of vascular damage. It is due to hereditary deficiency of 5,10-methylene-tetrahydrofolate reductase with accentuation of vitamin deficiency (folic acid, vitamin B6 and B12). In previous studies the authors confirmed this fact in the population of patients with aortocoronary or peripheral arterial bypasses. The assumed autosomal recessive transmission of this deficiency should make it possible to detect carriers of this metabolic deviation already in childhood. By selective screening of the child population at risk it would thus be possible to detect affected subjects in time and prevent the development of vascular disease by preventive folate administration. METHODS AND RESULTS: In a group of 38 children and grandchildren from risk families where at least one of the parents or grandparents was operated on account of vascular obliterating disease the total homocysteine plasma level was examined by the chromatographic method. An increase of total homocystein (8.7 +/- 2.7 mumol/l) was found as compared with children from the non-risk population (5.4 +/- 1.8 mumol/l), (p < 0.001). The total homocysteine values however were dependent on the child's age and were more marked in children above 12 years of age. In the parental population mild hyperhomocysteinaemia was present in 38% of those with aortocoronary bypasses and in 43% of those with peripheral arterial bypasses. CONCLUSIONS: The authors found significantly elevated total homocysteine levels in the child population from risk families with obliterating vascular disease. The total homocysteine level depends on the child's age and is more markedly expressed in children above 12 years of age.

Adolescent↗
PubMed1999

Cystathionine beta-synthase mutations in homocystinuria.

The major cause of homocystinuria is mutation of the gene encoding the enzyme cystathionine beta-synthase (CBS). Deficiency of CBS activity results in elevated levels of homocysteine as well as methionine in plasma and urine and decreased levels of cystathionine and cysteine. Ninety-two different disease-associated mutations have been identified in the CBS gene in 310 examined homocystinuric alleles in more than a dozen laboratories around the world. Most of these mutations are missense, and the vast majority of these are private mutations. The two most frequently encountered of these mutations are the pyridoxine-responsive I278T and the pyridoxine-nonresponsive G307S. Mutations due to deaminations of methylcytosines represent 53% of all point substitutions in the coding region of the CBS gene.

CpG Islands↗
PubMed1999

Four novel mutations in the cystathionine beta-synthase gene: effect of a second linked mutation on the severity of the homocystinuric phenotype.

Homocystinuria due to cystathionine beta-synthase (CBS) deficiency is frequently caused by missense mutations. In this article, we report four novel missense mutations in the CBS gene: 172C-->T (R58W) linked in cis with A114V; 376A-->G (M126V); 904G-->A (E302K); and 1006C-->T (R336C). The CBS activity of the corresponding mutant enzymes expressed in Escherichia coli was greatly diminished, confirming the pathogenicity of these mutations. Western analysis showed that the R58W+A114V and M126V mutant enzymes were unstable in E. coli, while the E302K subunits were partially degraded to shorter products. Using site-directed mutagenesis we found that CBS containing either the R58W or A114V as the only mutations demonstrated 18% and 46% of normal activity, respectively. Both mutant forms of CBS were stable in E. coli. When these two mutations were expressed in cis, the resultant mutant protein exhibited activity 1.3% that of a control. All these in vitro results were in good agreement with the clinical manifestation in these patients. The Italian patient 2241, an A114V+R58W/M126V compound heterozygote, exhibited severe pyridoxine nonresponsive homocystinuria, while another Italian patient 2242, with an A114V/E302K genotype, responded to pyridoxine treatment and had a much milder phenotype. The third patient 3064, an English compound heterozygote for two severe mutations R336C and G307S, was B6 nonresponsive. This report of a ninth homocystinuric allele carrying two mutations in cis raises the possibility that double mutant alleles may be underestimated in homocystinuric patients. In this context, a search for additional mutations in cis may sometimes be necessary to establish a good genotype-phenotype relationship.

Alleles↗
PubMed1999

Identification of a mutation cluster in mevalonate kinase deficiency, including a new mutation in a patient of Mennonite ancestry.

Mevalonate kinase (MKase) deficiency (MKD) is a rare autosomal recessive disorder in the pathway of cholesterol and nonsterol isoprenoid biosynthesis. Thus far, two disease-causing missense alleles have been identified, N301T and A334T. We report four additional mutations associated with MKD: L264F, T243I, L265P, and I268T, the last found in a patient of Mennonite ancestry. Electrophoretic analysis of bacterially expressed wild-type and mutant MKase indicated that I268T and T243I mutants produced normal or somewhat reduced amounts of MKase protein; conversely, L264F and L265P mutations resulted in considerably decreased, or absent, MKase protein. Immunoblot analysis of MKase from all patients suggested that the MKase polypeptide was grossly intact and produced in amounts comparable to control levels. Three mutations resulted in significantly diminished MKase enzyme activity (<2%), whereas the I268T allele yielded approximately 20% residual enzyme activity. Our results should allow more-accurate identification of carriers and indicate a mutation "cluster" within amino acids 240-270 of the mature MKase polypeptide.

Alleles↗
PubMed1999

Statistical approaches for evaluation of genetic risk factor of peripheral arterial occlusive disease.

In the paper we show results of medical study from statistical point of view. The medical study was aimed to study genetic risk factors of peripheral arterial occlusive diseases in Czech population. Two genes, CBS and MTHFR were examined, as various genotypes of these genes are thought to have impact on amino thiols, who participate in variety of reactions in vasculature. Statistical part of the study was responsible for analysis and interpretation of collected data.

Adult↗
PubMed1998

The human cystathionine beta-synthase (CBS) gene: complete sequence, alternative splicing, and polymorphisms.

Cystathionine beta-synthase [CBS; l-serine hydro-lyase (adding homocysteine), EC 4.2.1.22] catalyzes the first committed step of transsulfuration and is the enzyme deficient in classical homocystinuria. In this report, we describe the molecular cloning and the complete nucleotide sequence of the human CBS gene. We report a total of 28,046 nucleotides of sequence, which, in addition to the CBS gene, contains approximately 5 kb of the 5' flanking region. The human CBS gene contains 23 exons ranging from 42 to 209 bp. The 5' UTR is formed by 1 of 5 alternatively used exons and 1 invariably present exon, while the 3' UTR is encoded by exons 16 and 17. We also describe the identification of two alternatively used promoter regions that are GC rich (approximately 80%) and contain numerous putative binding sites for Sp1, Ap1, Ap2, and c-myb, but lack the classical TATA box. The CBS locus contains an unusually high number of Alu repeats, which may predispose this gene to deleterious rearrangements. Additionally, we report on a number of DNA sequence repeats that are polymorphic in North American and European Caucasians.

Alternative Splicing↗
PubMed1998

[Fetal pathology in Fabry's disease and mucopolysaccharidosis type I].

Fetal Fabry disease (defect of alfa galactosidase) and mucopolysaccharidosis I (defect of alfa iduronidase, family with IH phenotype) were diagnosed by biochemistry in two risk gravidities subsequently interrupted according to mother's demand. Fetus with Fabry disease (gestation age 19 weeks) had rudimentary storage in kidney and myenteric plexuses cells, cardiocytes were normal. Biopsy of chorionic villi showed a bit more conspicuous storage in single trophoblastic elements. Much more striking storage was observed in MPS I (gestational age 14-15 weeks) especially in liver (hepatocytes and sinus cells), spleen (sinus endothelial cells and pulp macrophages) and fibroblasts of skin and placenta. Skin peripheral nerves and cerebral cortical gangliocytes did not show any lysosomal storage. Different manifestation of storage in fetal age may reflex the speed of lysosomal storage development in both lysosomal enzymopathies.

Fabry Disease↗