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Biomedical subjects

M Hrebícek

Publications and source records attributed to M Hrebícek.

18 recordsLinked to original sources
PubMed2005

Prosaposin deficiency -- a rarely diagnosed, rapidly progressing, neonatal neurovisceral lipid storage disease. Report of a further patient.

An infant presented with multifocal myoclonus and cyanotic hypoxemia immediately after birth, and severe feeding problems, a protein-losing enteropathy, massive ascites and grand-mal epilepsy marked his rapid downhill course, with death at 17 weeks. At 2 weeks, brain MRI revealed grey matter heterotopias in the parieto-occipital regions suggestive of a cortical morphogenetic disorder. In cultured skin fibroblasts, lipid storage and reduced activities of ceramidase, galactosylceramide beta-galactosidase and glucosylceramide beta-glucosidase were evident. Autopsy disclosed generalised lysosomal lipid storage with macrophages and adrenal cortex prominently affected. The pattern of stored lipids in cultured fibroblasts and in dewaxed spleen tissue blocks was compatible with a diagnosis of prosaposin (pSap) deficiency (pSap-d). Neuropathologically, there was a pronounced generalised neurolysosomal storage combined with a severe depletion of cortical neurons and extreme paucity of myelin and oligodendroglia. This pathology, in particular the massive neuronal loss, differed from that in other neurolipidoses and could be explained by the reduced hydrolysis of multiple sphingolipids and the loss of pSap's neurotrophic function. The absence of immunostainable saposins on tissue sections and the presence of a homozygous c.1 A > T mutation in the prosaposin gene confirmed the diagnosis. PSap-d may be an underdiagnosed condition in infants with severe neurological and dystrophic signs starting immediately after birth.

Brain↗
PubMed2001

A novel mutation in the coding region of the prosaposin gene leads to a complete deficiency of prosaposin and saposins, and is associated with a complex sphingolipidosis dominated by lactosylceramide accumulation.

A fatal infantile storage disorder with hepatosplenomegaly and severe neurological disease is described. Sphingolipids, including monohexosylceramides (mainly glucosylceramide), dihexosylceramides (mainly lactosylceramide), globotriaosyl ceramide, sulphatides, ceramides and globotetraosyl ceramide, were stored in the tissues. In general, cholesterol and sphingomyelin levels were unaltered. The storage process was generalized and affected a number of cell types, with histiocytes, which infiltrated a number of visceral organs and the brain, especially involved. The ultrastructure of the storage lysosomes was membranous with oligolamellar, mainly vesicular, profiles. Infrequently, there were Gaucher-like lysosomes in histiocytes. The neuropathology was severe and featured neuronal storage and loss with a massive depopulation of cortical neurons and pronounced fibrillary astrocytosis. There was a paucity of myelin and stainable axons in the white matter with signs of active demyelination. Immunohistochemical investigations indicated that saposins A, B, C and D were all deficient. The patient was homozygous for a 1 bp deletion (c.803delG) within the SAP-B domain of the prosaposin gene which leads to a frameshift and premature stop codon. In the heterozygous parents, mutant cDNA was detected by amplification refractory mutation analysis in the nuclear, but not the cytoplasmic, fraction of fibroblast RNA, indicating that the mutant mRNA was rapidly degraded. The storage process in the proband resembled that of a published case from an unrelated family. Saposins were also deficient in this case, leading to its reclassification as prosaposin deficiency, and her mother was found to be a carrier for the same c.803delG mutation. Both of the investigated families came from the same district of eastern Slovakia.

Antigens, CD↗
PubMed2001

Eight novel ABCD1 gene mutations and three polymorphisms in patients with X-linked adrenoleukodystrophy: The first polymorphism causing an amino acid exchange.

X-ALD is a neurological disorder associated with inherited defects in the ABCD1 (ALD) gene located on Xq28 and with impaired peroxisomal very long-chain fatty acid beta-oxidation. We examined the ABCD1 gene in probands from 11 unrelated X-ALD Czech and Slovak families by the direct sequencing of cDNA or genomic PCR products. In 10 families there were 10 different mutations, eight of which were novel. The spectrum of mutations consists of six point mutations, three microdeletions (1bp, 2bp, 4 bp), and one large deletion (229bp). In the 11th family we detected two novel single-base pair substitutions in exon 1 (c.38 A>C and c.649 A>G), both causing amino acid exchanges (N13T and K217E). Expression studies revealed that only K217E is a deleterious mutation, because a plasmid encoding ALDP with K217E was ineffective in the restoration of defective beta-oxidation in X-ALD fibroblasts. The N13T amino acid exchange, on the other hand, did not affect ALDP function. Thus, N13T represents the first polymorphism causing an amino acid exchange in the ABCD1 gene. As this polymorphism was observed neither in 100 control alleles nor in 300 X-ALD patients who have been sequenced so far world-wide, it seems to be very rare or unique. Two additional novel polymorphisms were found by the sequencing of the ABCD1 gene from our patients: c.-59 C/T in the 5'untranslated region and c.2019 C/T (F673F) in exon 10. The frequencies of these two polymorphisms, were 11/150 and 2/150 control alleles, respectively.

5' Untranslated Regions↗
PubMed2001

Inhibition of substrate synthesis as a strategy for glycolipid lysosomal storage disease therapy.

The glycosphingolipid (GSL) lysosomal storage diseases are caused by mutations in the genes encoding the glycohydrolases that catabolize GSLs within lysosomes. In these diseases the substrate for the defective enzyme accumulates in the lysosome and the stored GSL leads to cellular dysfunction and disease. The diseases frequently have a progressive neurodegenerative course. The therapeutic options for treating these diseases are relatively limited, and for the majority there are no effective therapies. The problem is further compounded by difficulties in delivering therapeutic agents to the brain. Most research effort to date has focused on strategies for augmenting enzyme levels to compensate for the underlying defect. These include bone marrow transplantation (BMT), enzyme replacement and gene therapy. An alternative strategy that we have been exploring is substrate deprivation. This approach aims to balance the rate of GSL synthesis with the impaired rate of GSL breakdown. The imino sugar N-butyldeoxynojirimycin (NB-DNJ) inhibits the first step in GSL biosynthesis and has been used to evaluate this approach. Studies in an asymptomatic mouse model of Tay-Sachs disease have shown that substrate deprivation prevents GSL storage in the CNS. In a severe neurodegenerative mouse model of Sandhoff disease, substrate deprivation delayed the onset of symptoms and disease progression and significantly increased life expectancy. Combining NB-DNJ and BMT was found to be synergistic in the Sandhoff mouse model. A clinical trial in type I Gaucher disease has been undertaken and has shown beneficial effects. Efficacy was demonstrated on the basis of significant decreases in liver and spleen volumes, gradual but significant improvement in haematological parameters and disease activity markers, together with diminished GSL biosynthesis and storage as determined by independent biochemical assays. Further trials in type I Gaucher disease are in progress; studies are planned in patients with GSL storage in the CNS.

Animals↗
PubMed2001

Cells of porcine epidermis and corneal epithelium are not recognized by human natural anti-alpha-galactoside IgG.

Human natural antibodies against Galalphal,3Gal-R are mainly responsible for hyperacute rejection of xenografts transplanted to the human host. In addition to the anti-alpha-Gal activity, human serum also contains anti-beta-Gal IgG fractions. Employing biotinylated IgG subfractions with anti-alpha- and anti-beta-Gal activity purified from human natural IgG, we have studied expression of reactive epitopes in porcine and human skin, porcine cultured keratinocytes and porcine and human cornea, porcine liver and human lacrimal gland, tear fluid and capillaries. No reactivity of porcine and human epidermis as well as anterior corneal epithelium was observed for human anti-alpha-Gal IgG. Serving as positive control, porcine capillaries gave the expected signal with the anti-alpha-Gal antibody. The anti-beta-Gal subfraction recognized cell nuclei in the epidermis of both these species. The pig liver cells interacted with antibodies against alpha- and beta-galactosides like cells of the human lacrimal gland. alpha-galactoside-reactive glycoproteins were also detected in the human tear fluid. The carbohydrate specificity of the reaction was ascertained by using melibiose as competitive sugar for alpha-galactoside-mediated binding. These results reveal the presentation of Galalpha1,3Gal in epithelial cells of human lacrimal gland, its biosynthetic origin being unclear. With respect to a potential clinical perspective, the given results facilitate consideration of the use of porcine epidermal cells in engineering of non-permanent wound covers to improve treatment.

Animals↗
PubMed2000

Novel oral treatment of Gaucher's disease with N-butyldeoxynojirimycin (OGT 918) to decrease substrate biosynthesis.

BACKGROUND: Current treatment for Gaucher's disease involves administration of intravenous glucocerebrosidase to degrade glucocerebroside stored in lysosomes. Lowering the rate of biosynthesis of glucocerebroside should decrease accumulation of this substrate. We investigated the safety and efficacy of OGT 918 (N-butyldeoxynojirimycin), an inhibitor of glucosyltransferase, as a novel oral treatment for non-neuronopathic Gaucher's disease. METHODS: We recruited, into a 1-year open-label study, 28 adults (seven with previous splenectomies) from four national Gaucher's referral clinics, who were unable or unwilling to receive enzyme treatment. We measured liver and spleen volume by computed tomography or magnetic resonance imaging at baseline and at months 6 and 12, and biochemical and haematological variables monthly, including chitotriosidase activity (a sensitive marker of Gaucher's disease activity). Patients were started on 100 mg oral OGT 918 three times daily. FINDINGS: Baseline liver volumes were 1.1-2.7 times normal and spleen volumes 5.1-24.8 times normal. At 12 months, mean liver and spleen volumes were significantly lowered by 12% (95% CI 7.8-16.4) and 19% (14.3-23.7), respectively (each p<0.001). Haematological variables improved slightly. Mean organ volume and blood counts improved continually between 6 months and 12 months of treatment. Mean chitotriosidase concentrations fell by 16.4% over 12 months (p<.0001). Six patients withdrew because of gastrointestinal complaints (two), personal reasons (two), or severe pre-existing disease (two). The most frequent adverse effect was diarrhoea, which occurred in 79% of patients shortly after the start of treatment. INTERPRETATION: Decrease of substrate formation by OGT 918 improves key clinical features of non-neuronopathic Gaucher's disease. The strategy justifies further trials in this and other glycosphingolipid storage disorders.

1-Deoxynojirimycin↗
PubMed2000

[Prenatal diagnosis in families with cytochrome C oxidase disorder].

OBJECTIVE: Cytochrome c oxidase (COX) deficiency presents with severe impairment of brain, muscle or heart. Prenatal diagnosis in affected families is difficult because the disease may be caused by mutations in nuclear or mtDNA. This study shows the results of prenatal diagnosis in two families where the first child died because of a generalised COX defect. In both cases the low activity of COX was accompanied by a low content of the enzyme. SUBJECTS: In the first family the amniocentesis was performed during the second pregnancy and cultured amniocytes showed a marked decrease of COX activity and ATP production. Based on decision of the parents the pregnancy was terminated. Analysis of the foetal tissues confirmed a generalised COX defect. In the second family the nuclear origin of the COX defect was found using transmitochondrial cybrids derived from COX-deficient fibroblasts of the affected child. In the successive pregnancy with dizygotic twins a combined amniocentesis and chorionic villi biopsy has been performed. Prenatal diagnosis was based in both foetuses on three independent approaches. COX activity, the ATP production and protein content of COX complex was measured in cultivated foetal cells. The results of all investigations excluded a putative COX defect and both children are healthy at the age of 2 and half years. CONCLUSION: Prenatal diagnosis of COX disorders is available in families with the generalised form of the disease based on a nuclear origin of COX deficiency. Three independent approaches to characterise COX at a functional, enzymatic and protein level may be used.

Cytochrome-c Oxidase Deficiency↗
PubMed1997

[Mucolipidosis II (I cell disease). First case report in the Czech Republic and prenatal diagnosis in a family].

The authors describe the first case of mucolipidosis II in the Czech Republic. The cause of this autosomal recessive hereditary disease is deficient synthesis of mannoso-6-phosphate ligand on precursors of lysosomal enzymes which normally make their transport into the lysosomal system possible. The diagnosis was proved by the presence of typical lysosomal cumulation in bioptic specimens and extremely elevated activity of lysosomal enzymes in the patient's serum caused by their non-regulated secretion and subsequent intracellular depletion. During the second pregnancy in the family prenatal diagnosis was made. A normal range of lysosomal enzyme activities in the supernatant of the amniotic fluid and in cultivated chorionic villi along with normal results of ultrastructural examination of the chorionic villus indicated the development of an intact foetus.

Czech Republic↗
PubMed1997

[Enzyme therapy in children with severe forms of Gaucher's disease].

The enzyme therapy with Ceredase in patients with Gaucher's disease is at present probably the most expensive treatment in the whole world. One-year treatment of an adult patient with Gaucher's disease costs more than 7 million crowns. Indications for treatment in individual patients as well as financial provisions are so far problematic in the Czech Republic. From a total of 28 patients of varying age with Gaucher's disease diagnosed by the authors Ceredase was administered to two boys with a severe course of the disease. Within one year of treatment the health status of both children improved, growth became normal, the spleen diminished in size by 20-35%, haematological manifestations of hypersplenism are receding, there was a 32-46% decline of the activity of serum chitotriosidase and biochemical parameters of the disease improved.

Child↗
PubMed1997

Follow-up study of subunit c of mitochondrial ATP synthase (SCMAS) in Batten disease and in unrelated lysosomal disorders.

Immunohistochemical and biochemical studies of subunit c of mitochondrial ATP synthase (SCMAS) storage were carried out in neuronal ceroid lipofuscinosis (NCL) and in a series of unrelated inherited and acquired lysosomal disorders. In the NCL group, represented by the late infantile, early juvenile and juvenile types, SCMAS storage was generalized neurovisceral, with considerable difference in the visceral storage pattern between the types. In late infantile NCL the SCMAS storage was intensive and corresponded to the generalized, autofluorescent, uniformly curvilinear material, irrespective of the cell type affected. In both early juvenile and juvenile NCLs the SCMAS storage was strong and almost uniform in brain neurons, but did not correlate entirely with the visceral autofluorescent storage pool, being undetectable in autofluorescent storage deposits in a constant set of tissues. In the adult (Kufs) type, the brain neurons were stained with various intensity. In infantile NCL, SCMAS storage was restricted to some of the persisting neurons. In a series of inherited lysosomal enzymopathies and acquired lysosomal disorders, excessive SCMAS accumulation was found only in secondary neuronal lipopigments. It occurred as an early and more uniform phenomenon in mucopolysaccharidosis types I, II, IIIA and in polysulphatase deficiency, or as a delayed varied phenomenon in protracted variants of mucolipidosis I, Niemann-Pick types A and C, and GM2 and GM1 gangliosidoses. Neuronal ageing led to an irregular increase in immunodetectable SCMAS epitope in some neuronal lipofuscin granules. There was no evidence of significant SCMAS lysosomal accumulation in non-neural cells in the whole group, regardless of whether lipofuscin or ceroid accumulation occurred or not. The neuronal SCMAS storage is thus nosologically a common unspecific phenomenon, which is especially amplified in NCL. The specificity of the NCL storage process is shown by the fact that even lysosomes of non-neuronal cells in NCL accumulate SCMAS.

Adolescent↗
PubMed1996

A case of type I Gaucher disease with cardiopulmonary amyloidosis and chitotriosidase deficiency.

Severe cardiopulmonary amyloidosis developed several months after a total splenectomy in a patient with type 1 Gaucher disease and led within a year to his death at 48 years of age. The autopsy findings were dominated by extensive pulmonary and cardiac amyloid infiltration. No Gaucher cells were found in the lungs. Aside from a glucocerebrosidase deficiency the patient was also deficient in chitotriosidase, an enzyme whose activity is usually greatly increased in the serum of Gaucher patients. Analysis of mutations in the glucocerebrosidase gene revealed heterozygosity for N370S and D409H mutations. The normal amount of glucocerebrosidase was found in the spleen by Western blotting. We suggest that amyloidosis should be considered in the differential diagnosis of severe cardiopulmonary disease in Gaucher patients.

Amyloid↗
PubMed1996

Comparison of the 5' end of the rat and mouse cystathionine beta-synthase genes.

We have isolated and characterized a genomic fragment encompassing the first six exons and 2.6 kbp 5' flanking sequence of the rat cystathionine beta-synthase (CBS) gene. A previously unknown exon approximately 3 kbp upstream of exon 1 was identified. The transcription start site was mapped to approximately 3 kbp upstream from the translation start codon and contains a consensus cap signal. The putative promoter region contains three GC boxes, in both orientations, and no TATA box. We have also compared a 1171-bp-long DNA sequence of the 5' end of the rat CBS gene with the homologous mouse region of 1125 bp. We found two homologous Sp1 sites in the mouse gene and an overall sequence conservation of 70% with 88-89% similarity in the 80-bp regions surrounding the intron 0 splice sites.

Animals↗
PubMed1993

[Metabolic study in a child with Leigh's syndrome and deficient activity in complex I of the respiratory chain].

Leigh's syndrome--subacute necrotizing encephalomyopathy--is a serious disease of child age manifested by severe psychomotor retardation, a varied neurological symptomatology, a typically symmetrical neuropathological affection of the central nervous system in the area of the basal ganglia and a metabolic disorder affecting the energy system of cells. The authors describe the clinical course of the disease and the results of metabolic and neuropathological investigations in an infant with Leigh's syndrome and severe lactate acidosis based on deficiency of complex I activity of the respiratory chain.

Female↗
PubMedDate not supplied

Analysis of the beta-glucocerebrosidase gene in Czech and Slovak Gaucher patients: mutation profile and description of six novel mutant alleles.

The aim of this study was to characterize the spectrum of 13-glucocerebrosidase gene mutations in Czech and Slovak Gaucher patients and to study genotype/phenotype associations. We have analyzed fifty-eight chromosomes from twenty-six type I, two type 2, and one type 3 13-glucocerebrosidase deficient subjects by direct sequencing of PCR products. Fifty-eight mutant alleles were identified. Seventy-eight percent of mutant alleles carried common mutations (N370S 28/58, L444P 11/58, recNciI 5/58, and IVS2(+1)A 1/58), the remaining twenty-two percent carried rare and private mutations (1263del55, l326insT, S196P, rec(g4889-6506), 2O3delC, G202E, F216Y, R257X, R12OW, R359Q, S1O7L, L444P + V460V, and D409H + T369M). Six of these alleles have not been previously described (rec(g4889-6506), 1326insT, SI96P. G202E, D409H + T369M, and L444P + V460V). The most common genotypes were N370S/L444P (8/29). N370S/recNciI (5/29), and N370S/N370S (2/29). The spectrum of the mutations is characteristic for a Caucasian (non-Jewish) population, with N370S, L444P and recNciI being the most prevalent mutations. The absence of the mutation 84insG that is frequently associated with severe bone disease may have contributed to the low incidence of severe bone disease in Czech and Slovak Gaucher subjects.

Adolescent↗