The porphyrias are group of mostly inherited disorders in which a specific spectrum of accumulate... more The porphyrias are group of mostly inherited disorders in which a specific spectrum of accumulated and excreted porphyrins and heme precursors are associated with characteristic clinical features. There are eight enzymes involved in the heme synthesis and defects in seven of them cause porphyria. Four of them are described as acute hepatic porphyrias, which share possible precipitation of acute attacks with symptoms engaging the nervous system. Acute intermittent porphyria (AIP), caused by partial deficiency of the porphobilinogen deaminase (PBGD), is the most frequent among hepatic porphyrias. Clinical expression is highly variable and ~ 90 % of AIP heterozygotes remain asymptomatic throughout life. During systematic genetic analysis of the AIP patients diagnosed in the Czech and Slovak Republics, we found a special case of AIP. In a 15-year-old boy with abdominal and subsequent neurological symptomatology, we identified de novo mutation 966insA within the PBGD gene leading to a st...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Mutations in several genes such as parkin can be detected in up to 20% of patients with early-ons... more Mutations in several genes such as parkin can be detected in up to 20% of patients with early-onset Parkinson's disease (EOPD). The aim of our study was to determine the frequency of parkin alterations and phenotypic characteristics in Czech EOPD patients. A total of 45 EOPD individuals (age at onset <45 years) were phenotyped and screened for parkin mutations. In total, 19 patients (42.2%) were carriers of previously described heterozygous genetic alterations. Parkin mutations (Ex2del, R402C) were identified in two (4.4%) cases, non-pathogenic variant A82E plus polymorphism D394N occurred in one (2.2%) patient and parkin polymorphisms (3x S167N, 1x R334C, 7x V380L, 4x D394N) were found in 15 (34.9%) individuals. Furthermore, the G2019S mutation in the LRRK2 gene was found in one (2.2%) subject. The clinical characteristics of our patients correspond to previous descriptions of EOPD phenotype. This is the first report on EOPD-associated genetic alterations among Czech patient...
Nitrite (NO2−) recycling to nitric oxide (NO) is catalysed by a number of enzymes and induces a p... more Nitrite (NO2−) recycling to nitric oxide (NO) is catalysed by a number of enzymes and induces a protective vasodilation effect under hypoxia/ischaemia. In the present work, we tested the in vitro ability of the three NOS (nitric oxide synthase) isoforms to release NO from nitrite under anoxia using electrochemical detection, chemiluminescence and absorption spectroscopy. The release of free NO from anoxic nitrite solutions at 15 μM was specific to the endothelial NOS isoform (eNOS) and did not occur with the neuronal (nNOS) or inducible (iNOS) isoforms. Unlike xanthine oxidase, the eNOS reductase domain did not recycle nitrite to NO, and wild-type eNOS did not reduce nitrate. Our data suggest that structural and, by inference, dynamic differences between nNOS and eNOS in the distal haem side account for eNOS being the only isoform capable of converting nitrite into NO at pH 7.6. In human dermal microvascular endothelial cells under careful control of oxygen tension, the rates of NO ...
Biochemical and Biophysical Research Communications, 2006
In this work, we demonstrate that endothelial nitric oxide synthase is capable of anoxic reductio... more In this work, we demonstrate that endothelial nitric oxide synthase is capable of anoxic reduction of nitrite anions to nitric oxide at physiological pH by absorption and EPR spectroscopy and electrochemical measurements. The nitrite reduction is achieved at the oxygenase domain of the protein and proceeds even in the absence of the tetrahydrobiopterin cofactor. The nitrite pathway increases by sixfold the NO production with respect to the regular arginine pathway under hypoxia, which is largely blocked. Therefore, basal levels of NO release could be sustained by anoxic nitrite reduction. The reaction suggests a new pathway for fast NO delivery under hypoxia, precisely when the vasodilating properties of nitric oxide are most needed.
Aim: Estimating polymorphic allele frequencies of the NADPH–CYP450 oxidoreductase (POR) gene in a... more Aim: Estimating polymorphic allele frequencies of the NADPH–CYP450 oxidoreductase (POR) gene in a Czech Slavic population. Methods: The POR gene was analyzed in 322 individuals from a control cohort by sequencing and high resolution melting analysis. Results: We identified seven unreported SNP genetic variations, including two SNPs in the 5′ flanking region (g.4965C>T and g.4994G>T), one intronic variant (c.1899-20C>T), one synonymous SNP (p.20Ala=) and three nonsynonymous SNPs (p.Thr29Ser, p.Pro384Leu and p.Thr529Met). The p.Pro384Leu variant exhibited reduced enzymatic activities compared with wild-type. Conclusion: New POR variant identification indicates the number of uncommon variants might be specific for each subpopulation being investigated, particularly germane to the singular role that POR plays in providing reducing equivalents to all CYP450s in the endoplasmic reticulum. Original submitted 15 September 2014; Revision submitted 17 November 2014
Erythropoietic protoporphyria (EPP), a chronic erythropoietic porphyria, is characterized by exce... more Erythropoietic protoporphyria (EPP), a chronic erythropoietic porphyria, is characterized by excess accumulation of protoporphyrin, particularly in erythroid cells. EPP inheritance is complex, almost always associated with two molecular defects. In most EPP patients, clinical expression requires coinheritance of a private ferrochelatase (FECH) mutation trans- to a hypomorphic FECH*IVS3-48C allele. This leads to a decrease of FECH activity below the critical threshold. This is characterized by cutaneous photosensitivity in early childhood such as itching, burning, swelling and redness in sun-exposed areas. Hepatic failure occurs in some patients (about 1-10 % of EPP patients), which may necessitate liver transplantation. We investigated a Czech family with two patients with manifested EPP in four generations. We found a novel mutation, c.84G >A, in the FECH gene in four individuals including proband and his mother (G84A transition in exon 2; p.W28*). Both clinically manifested pro...
Porphyrias are uncommon inherited diseases of haem biosynthesis for which the diagnosis and treat... more Porphyrias are uncommon inherited diseases of haem biosynthesis for which the diagnosis and treatment varies in individual countries. Despite the existence of guidelines recommended by porphyria experts concerning the diagnosis and management of the acute porphyrias, and of specialist centres in most European countries, many clinicians still do not apply these guidelines. The European Porphyia Initiative (EPI) network was formed in 2001 in order to compare experience among countries to attempt to develop a common approach to the management of the porphyrias, particularly concerning recommendation of safe and unsafe drugs, and to facilitate international collaborative clinical and biological research. The main achievements of EPI during this period have been: * Drafting and agreeing to consensus protocols for the diagnosis and management of acute hepatic porphyrias. * Creation of a multilingual website, particularly focusing on guidelines for common prescribing problems in acute porp...
Table 1: Features of PiZZ patients who do or do not receive alpha1antitrypsin augmentation therap... more Table 1: Features of PiZZ patients who do or do not receive alpha1antitrypsin augmentation therapy. PiZZ, nonaugmented n = 143 PiZZ, augmented n = 221 Multivariate p value Characteristics Age (years) 49.4 ± 15.3 57.3 ± 10.4 Women (%) 52.4 42.1 BMI (kg/m 2) 24.3 ± 3.7 25.0 ± 4.7 Diabetes mellitus (%) 5.6 5.8 AATD-related features AAT serum level (mg/dL) 29.0 ± 17.2 104.9 ± 47.8 <0.0001 CAT score (points) 14 ± 8 18 ± 6 <0.0001 Long-term oxygen therapy (%) 7.7 34.4 <0.0001 Liver status LSM(kPa)
Rett syndrome (RTT) is an X-linked disorder caused by mutations in the methyl-CpG-binding protein... more Rett syndrome (RTT) is an X-linked disorder caused by mutations in the methyl-CpG-binding protein 2 gene (MECP2). The incidence is 1:10,000-1:15,000 females worldwide. To date, the mutational spectrum of MECP2 in the Ukrainian population is not known. Here we present first Ukrainian girl with classic clinical signs of RTT, in whom mutation of MECP2 gene was detected. Total genomic DNA was extracted from a dry blood spot using the QIAamp DNA Mini Kit (Qiagen) according to the manufacturer's protocol. Genomic DNA was used to amplify coding sequence and exon/intron borders of MECP2 gene. Products were examined by restriction analysis and automatic direct sequencing. The sequencing analysis of our patient revealed a small deletion of 4 bases AAAG at position 856-859 in exon 4 of MECP2 gene (856-859del4). This mutation leads to a frameshift (K286fs) and a premature stop codon. The creation of premature stop codon results in synthesis of truncated MeCP2 protein. Localization of the mu...
Two series of imidazole-containing amino acids (1a-e and 2a-c), all larger homologues and analogu... more Two series of imidazole-containing amino acids (1a-e and 2a-c), all larger homologues and analogues of L-histidine, were prepared. Since imidazole and phenyl substituted imidazoles have been reported to be inhibitors of NOS and the mode of action of these compounds as heme ligands is a potential mechanism of inhibitory action, we designed imidazole-containing amino acids as combined inhibitors at both the amino acid as well as heme binding sites. To study the influence of the distance between the amino acid moiety and the imidazole moiety on inhibitory potency, the number of carbons between these two functional groups was varied from two to six. The structure-activity relationships of this class of inhibitors can be correlated with the distance between the heme and the amino acid binding sites of the enzyme. Two of the compounds (1b and 1d) with three and five methylenes between the imidazole and amino acid functional groups, respectively, were found to be potent and selective inhibitors for nNOS and iNOS over eNOS. When phenyl was substituted on the nitrogen of the imidazole, both the potency and isoform selectivity diminished.
The porphyrias are group of mostly inherited disorders in which a specific spectrum of accumulate... more The porphyrias are group of mostly inherited disorders in which a specific spectrum of accumulated and excreted porphyrins and heme precursors are associated with characteristic clinical features. There are eight enzymes involved in the heme synthesis and defects in seven of them cause porphyria. Four of them are described as acute hepatic porphyrias, which share possible precipitation of acute attacks with symptoms engaging the nervous system. Acute intermittent porphyria (AIP), caused by partial deficiency of the porphobilinogen deaminase (PBGD), is the most frequent among hepatic porphyrias. Clinical expression is highly variable and ~ 90 % of AIP heterozygotes remain asymptomatic throughout life. During systematic genetic analysis of the AIP patients diagnosed in the Czech and Slovak Republics, we found a special case of AIP. In a 15-year-old boy with abdominal and subsequent neurological symptomatology, we identified de novo mutation 966insA within the PBGD gene leading to a st...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Mutations in several genes such as parkin can be detected in up to 20% of patients with early-ons... more Mutations in several genes such as parkin can be detected in up to 20% of patients with early-onset Parkinson's disease (EOPD). The aim of our study was to determine the frequency of parkin alterations and phenotypic characteristics in Czech EOPD patients. A total of 45 EOPD individuals (age at onset <45 years) were phenotyped and screened for parkin mutations. In total, 19 patients (42.2%) were carriers of previously described heterozygous genetic alterations. Parkin mutations (Ex2del, R402C) were identified in two (4.4%) cases, non-pathogenic variant A82E plus polymorphism D394N occurred in one (2.2%) patient and parkin polymorphisms (3x S167N, 1x R334C, 7x V380L, 4x D394N) were found in 15 (34.9%) individuals. Furthermore, the G2019S mutation in the LRRK2 gene was found in one (2.2%) subject. The clinical characteristics of our patients correspond to previous descriptions of EOPD phenotype. This is the first report on EOPD-associated genetic alterations among Czech patient...
Nitrite (NO2−) recycling to nitric oxide (NO) is catalysed by a number of enzymes and induces a p... more Nitrite (NO2−) recycling to nitric oxide (NO) is catalysed by a number of enzymes and induces a protective vasodilation effect under hypoxia/ischaemia. In the present work, we tested the in vitro ability of the three NOS (nitric oxide synthase) isoforms to release NO from nitrite under anoxia using electrochemical detection, chemiluminescence and absorption spectroscopy. The release of free NO from anoxic nitrite solutions at 15 μM was specific to the endothelial NOS isoform (eNOS) and did not occur with the neuronal (nNOS) or inducible (iNOS) isoforms. Unlike xanthine oxidase, the eNOS reductase domain did not recycle nitrite to NO, and wild-type eNOS did not reduce nitrate. Our data suggest that structural and, by inference, dynamic differences between nNOS and eNOS in the distal haem side account for eNOS being the only isoform capable of converting nitrite into NO at pH 7.6. In human dermal microvascular endothelial cells under careful control of oxygen tension, the rates of NO ...
Biochemical and Biophysical Research Communications, 2006
In this work, we demonstrate that endothelial nitric oxide synthase is capable of anoxic reductio... more In this work, we demonstrate that endothelial nitric oxide synthase is capable of anoxic reduction of nitrite anions to nitric oxide at physiological pH by absorption and EPR spectroscopy and electrochemical measurements. The nitrite reduction is achieved at the oxygenase domain of the protein and proceeds even in the absence of the tetrahydrobiopterin cofactor. The nitrite pathway increases by sixfold the NO production with respect to the regular arginine pathway under hypoxia, which is largely blocked. Therefore, basal levels of NO release could be sustained by anoxic nitrite reduction. The reaction suggests a new pathway for fast NO delivery under hypoxia, precisely when the vasodilating properties of nitric oxide are most needed.
Aim: Estimating polymorphic allele frequencies of the NADPH–CYP450 oxidoreductase (POR) gene in a... more Aim: Estimating polymorphic allele frequencies of the NADPH–CYP450 oxidoreductase (POR) gene in a Czech Slavic population. Methods: The POR gene was analyzed in 322 individuals from a control cohort by sequencing and high resolution melting analysis. Results: We identified seven unreported SNP genetic variations, including two SNPs in the 5′ flanking region (g.4965C>T and g.4994G>T), one intronic variant (c.1899-20C>T), one synonymous SNP (p.20Ala=) and three nonsynonymous SNPs (p.Thr29Ser, p.Pro384Leu and p.Thr529Met). The p.Pro384Leu variant exhibited reduced enzymatic activities compared with wild-type. Conclusion: New POR variant identification indicates the number of uncommon variants might be specific for each subpopulation being investigated, particularly germane to the singular role that POR plays in providing reducing equivalents to all CYP450s in the endoplasmic reticulum. Original submitted 15 September 2014; Revision submitted 17 November 2014
Erythropoietic protoporphyria (EPP), a chronic erythropoietic porphyria, is characterized by exce... more Erythropoietic protoporphyria (EPP), a chronic erythropoietic porphyria, is characterized by excess accumulation of protoporphyrin, particularly in erythroid cells. EPP inheritance is complex, almost always associated with two molecular defects. In most EPP patients, clinical expression requires coinheritance of a private ferrochelatase (FECH) mutation trans- to a hypomorphic FECH*IVS3-48C allele. This leads to a decrease of FECH activity below the critical threshold. This is characterized by cutaneous photosensitivity in early childhood such as itching, burning, swelling and redness in sun-exposed areas. Hepatic failure occurs in some patients (about 1-10 % of EPP patients), which may necessitate liver transplantation. We investigated a Czech family with two patients with manifested EPP in four generations. We found a novel mutation, c.84G >A, in the FECH gene in four individuals including proband and his mother (G84A transition in exon 2; p.W28*). Both clinically manifested pro...
Porphyrias are uncommon inherited diseases of haem biosynthesis for which the diagnosis and treat... more Porphyrias are uncommon inherited diseases of haem biosynthesis for which the diagnosis and treatment varies in individual countries. Despite the existence of guidelines recommended by porphyria experts concerning the diagnosis and management of the acute porphyrias, and of specialist centres in most European countries, many clinicians still do not apply these guidelines. The European Porphyia Initiative (EPI) network was formed in 2001 in order to compare experience among countries to attempt to develop a common approach to the management of the porphyrias, particularly concerning recommendation of safe and unsafe drugs, and to facilitate international collaborative clinical and biological research. The main achievements of EPI during this period have been: * Drafting and agreeing to consensus protocols for the diagnosis and management of acute hepatic porphyrias. * Creation of a multilingual website, particularly focusing on guidelines for common prescribing problems in acute porp...
Table 1: Features of PiZZ patients who do or do not receive alpha1antitrypsin augmentation therap... more Table 1: Features of PiZZ patients who do or do not receive alpha1antitrypsin augmentation therapy. PiZZ, nonaugmented n = 143 PiZZ, augmented n = 221 Multivariate p value Characteristics Age (years) 49.4 ± 15.3 57.3 ± 10.4 Women (%) 52.4 42.1 BMI (kg/m 2) 24.3 ± 3.7 25.0 ± 4.7 Diabetes mellitus (%) 5.6 5.8 AATD-related features AAT serum level (mg/dL) 29.0 ± 17.2 104.9 ± 47.8 <0.0001 CAT score (points) 14 ± 8 18 ± 6 <0.0001 Long-term oxygen therapy (%) 7.7 34.4 <0.0001 Liver status LSM(kPa)
Rett syndrome (RTT) is an X-linked disorder caused by mutations in the methyl-CpG-binding protein... more Rett syndrome (RTT) is an X-linked disorder caused by mutations in the methyl-CpG-binding protein 2 gene (MECP2). The incidence is 1:10,000-1:15,000 females worldwide. To date, the mutational spectrum of MECP2 in the Ukrainian population is not known. Here we present first Ukrainian girl with classic clinical signs of RTT, in whom mutation of MECP2 gene was detected. Total genomic DNA was extracted from a dry blood spot using the QIAamp DNA Mini Kit (Qiagen) according to the manufacturer's protocol. Genomic DNA was used to amplify coding sequence and exon/intron borders of MECP2 gene. Products were examined by restriction analysis and automatic direct sequencing. The sequencing analysis of our patient revealed a small deletion of 4 bases AAAG at position 856-859 in exon 4 of MECP2 gene (856-859del4). This mutation leads to a frameshift (K286fs) and a premature stop codon. The creation of premature stop codon results in synthesis of truncated MeCP2 protein. Localization of the mu...
Two series of imidazole-containing amino acids (1a-e and 2a-c), all larger homologues and analogu... more Two series of imidazole-containing amino acids (1a-e and 2a-c), all larger homologues and analogues of L-histidine, were prepared. Since imidazole and phenyl substituted imidazoles have been reported to be inhibitors of NOS and the mode of action of these compounds as heme ligands is a potential mechanism of inhibitory action, we designed imidazole-containing amino acids as combined inhibitors at both the amino acid as well as heme binding sites. To study the influence of the distance between the amino acid moiety and the imidazole moiety on inhibitory potency, the number of carbons between these two functional groups was varied from two to six. The structure-activity relationships of this class of inhibitors can be correlated with the distance between the heme and the amino acid binding sites of the enzyme. Two of the compounds (1b and 1d) with three and five methylenes between the imidazole and amino acid functional groups, respectively, were found to be potent and selective inhibitors for nNOS and iNOS over eNOS. When phenyl was substituted on the nitrogen of the imidazole, both the potency and isoform selectivity diminished.
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