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Biomedical subjects

O Hurko

Publications and source records attributed to O Hurko.

At least 55 records · Page 3Linked to original sources
PubMed1989

Directly repeated sequences associated with pathogenic mitochondrial DNA deletions.

We determined the nucleotide sequences of junctional regions associated with large deletions of mitochondrial DNA found in four unrelated individuals with a phenotype of chronic progressive external ophthalmoplegia. In each patient, the deletion breakpoint occurred within a directly repeated sequence of 13-18 base pairs, present in different regions of the normal mitochondrial genome-separated by 4.5-7.7 kilobases. In two patients, the deletions were identical. When all four repeated sequences are compared, a consensus sequence of 11 nucleotides emerges, similar to putative recombination signals, suggesting the involvement of a recombinational event. Partially deleted and normal mitochondrial DNAs were found in all tissues examined, but in very different proportions, indicating that these mutations originated before the primary cell layers diverged.

Base Sequence↗
PubMed1989

Compression syndromes due to hypertrophic nerve roots in hereditary motor sensory neuropathy type I.

Three patients with hereditary motor sensory neuropathy type I developed neurologic deficits attributable to hypertrophic nerve roots. Compression of the cervical spinal cord by enlarged nerve roots occurred in our index patient. Multilevel decompressive laminectomies relieved the myelopathy. An unrelated patient who had syncope precipitated by neck rotation had hypertrophied nerve roots that eroded into the transverse foramina in juxtaposition to the vertebral arteries. In a 3rd patient, compression of hypertrophied nerve roots within the thecal sac and neural foramina was associated with spinal claudication and radiculopathy, respectively.

Adult↗
PubMed1989

Dystrophin analysis in clonal myoblasts derived from a Duchenne muscular dystrophy carrier.

Clonal myogenic cell cultures were established from a potential heterozygote for a mutant Duchenne muscular dystrophy (DMD) gene who was also heterozygous for isozymes of the X-linked enzyme glucose-6-phosphate dehydrogenase. Previous tissue culture studies of this muscle donor demonstrated equal proliferative capacity of myoblasts that had lyonized either the paternal or maternal X-chromosome, indicating that mutation of the DMD gene does not affect growth of myoblasts. If this muscle donor were a gonadal mosaic, this conclusion would be incorrect. In the present study, only those myogenic colonies expressing the glucose-6-phosphate dehydrogenase-A isozyme were found to express dystrophin, indicating that this woman was indeed a heterozygote for DMD. By documenting dystrophin deficiency in a specific population of myogenic cells from this woman, we verify our previous conclusion regarding the normal proliferative capacity of DMD myoblasts. Somatic cell testing of dystrophin expression may offer an alternative to established genetic carrier tests for those women in whom deletions of the DMD are not detectable, whose pedigree structure does not permit linkage analysis, or in whom standard phenotypic analyses are ambiguous.

Blotting, Western↗
PubMed1988

Oral carnitine therapy in children with cystinosis and renal Fanconi syndrome.

11 children with either cystinosis or Lowe's syndrome had a reduced content of plasma and muscle carnitine due to renal Fanconi syndrome. After treatment with oral L-carnitine, 100 mg/kg per d divided every 6 h, plasma carnitine concentrations became normal in all subjects within 2 d. Initial plasma free fatty acid concentrations, inversely related to free carnitine concentrations, were reduced after 7-20 mo of carnitine therapy. Muscle lipid accumulation, which varied directly with duration of carnitine deficiency (r = 0.73), improved significantly in three of seven rebiopsied patients after carnitine therapy. One Lowe's syndrome patient achieved a normal muscle carnitine level after therapy. Muscle carnitine levels remained low in all cystinosis patients, even though cystinotic muscle cells in culture took up L-[3H]carnitine normally. The half-life of plasma carnitine for cystinotic children given a single oral dose approximated 6.3 h; 14% of ingested L-carnitine was excreted within 24 h. Studies in a uremic patient with cystinosis showed that her plasma carnitine was in equilibrium with some larger compartment and may have been maintained by release of carnitine from the muscle during dialysis. Because oral L-carnitine corrects plasma carnitine deficiency, lowers plasma free fatty acid concentrations, and reverses muscle lipid accumulation in some patients, its use as therapy in renal Fanconi syndrome should be considered. However, its efficacy in restoring muscle carnitine to normal, and the optimal dosage regimen, have yet to be determined.

Administration, Oral↗
PubMed1987

Cystine storage in cultured myotubes from patients with nephropathic cystinosis.

Sorted muscle cells, cultured from a patient with nephropathic cystinosis, stored 100 times normal amounts of cystine. Subcellular fractionation and density-gradient centrifugation confirmed that the cystine was located in a lysosomal compartment. 2. Myoblasts from cystinotic patients in culture underwent fusion to myotubes in a normal fashion. 3. The free thiol cysteamine effectively depleted cystinotic-muscle cells of cystine. 4. Cultured myoblast and myotubes offered a unique system for investigating the effects of lysosomal storage on differentiated cell functions.

Cells, Cultured↗
PubMed1987

Cervicomedullary compression in young patients with achondroplasia: value of comprehensive neurologic and respiratory evaluation.

We studied prospectively 26 young patients with achondroplasia to test two hypotheses: that respiratory problems may be the result of occult spinal cord compression, and that achondroplastic patients with cord compression might have occult respiratory abnormalities. Respiratory abnormalities were present in 85%, the majority caused by a primary problem of the pulmonary system, such as small thoracic cage or obstructed airway. Three patients had hypoxemia, recurrent cyanotic spells, and episodes of respiratory distress explainable only by cervicomedullary cord compression; in each patient, respiratory problems were alleviated by decompressive surgery. Another six patients with cervicomedullary compression had, in addition, at least one primary pulmonary cause of respiratory problems. After decompressive surgery the respiratory problems improved in three and were unchanged in three. Reconstructed sagittal CT images proved the most sensitive technique for detecting craniocervical stenosis as a cause of cervicomedullary cord compression, although some degree of stenosis was present in nearly all of the patients.

Achondroplasia↗
PubMed1987

Comparison of Duchenne and normal myoblasts from a heterozygote.

To test the hypothesis that the Duchenne muscular dystrophy gene limits the proliferation of myoblasts, we studied myoblasts from a woman who was a carrier of the Duchenne gene and also heterozygous for glucose-6-phosphate dehydrogenase (G6PD), an X-linked enzyme. G6PD-A and G6PD-B cells did not differ in proliferative capacity, implying no difference in proliferative capacity of cells bearing the Duchenne gene or the normal allele.

Cell Separation↗
PubMed1986

Transfection of human skeletal muscle cells with SV40 large T antigen gene coupled to a metallothionein promoter.

We have undertaken to increase the proliferative capacity of cultured human skeletal myocytes by transfection with a plasmid construct that contains the immortalizing and transforming large T antigen gene of simian virus 40 (SV40) under the control of a zinc-sensitive metallothionein promoter. This construct was chosen to permit rapid growth of transformants in zinc-containing medium, which induces high levels of T antigen expression, and muscle-specific differentiation after withdrawal of exogenous zinc, which reduces levels of T antigen. When grown in 100 microM Zn2+, transformed myocytes expressed the large T antigen, divided rapidly, and acquired an apparently unlimited proliferative capacity. Transfer of these cells to a zinc-poor medium resulted in decreased T antigen immunofluorescence, growth rate, and saturation density as well as a return to a physiological spindle morphology. Despite transformation, these cells expressed differentiation markers characteristic of myoblasts: the B isoform of creatine kinase, and surface antigens 5.1H11, D5, and Thy 1 in the presence or absence of Zn2+. When grown to high density in a serum-poor medium, these cells differentiated further into typical multinucleated myotubes that expressed the M isoform of creatine kinase and increased levels of surface antigen 5.1H11, creatine kinase, and nicotinic acetylcholine receptors, but no detectable Thy 1 antigen. The specific activity of these differentiation markers was higher when the cells were grown in the absence of added zinc. These results indicate that transformation of human skeletal myocytes with a regulatable SV40 large T antigen gene allows an increase of the proliferative capacity of these cells with preservation of their capacity to differentiate in a physiological manner.

Antigens, Polyomavirus Transforming↗
PubMed1986

Novel antigens at the neuromuscular junction.

Three novel components of neuromuscular junctions have been identified by use of monoclonal antibodies (McAb) against glycoproteins obtained from a mouse neuroblastoma X human dorsal root ganglion cell hybrid line. Antigen distribution was assessed by fluorescent immunohistochemistry on frozen sections of human intercostal muscle counterstained with labeled alpha-bungarotoxin to identify neuromuscular junctions. Antigen SOS 6 stained exclusively in the neuromuscular junction, whereas antigens SOS 5 and SOS 13 were highly enriched in the junction but also stained extrasynaptic regions. These antigens can be distinguished from previously described components of the neuromuscular junction by their molecular weights, insensitivity to collagenase treatment, and solubility in 0.1% Triton X-100. Indirect evidence suggests that these species-specific antigens are located in the postsynaptic muscle membrane, but location in the junctional basal lamina or subsarcolemmal region cannot be excluded.

Acetylcholinesterase↗
PubMed1984

Immunocytochemical analysis of fibre type differentiation in developing skeletal muscle.

Two monoclonal antibodies (McAbs) reactive with 'fast' and 'slow' adult myosin heavy chains have been produced and used in the analysis of human and rat muscle fibre type development. Expression of adult 'slow' myosin heavy chain was detected in human foetal muscle fibres as early as 14 weeks of gestation and in 1 day newborn rat muscle fibres. The standard histochemical stains used to show muscle fibre type do not distinguish fast from slow fibres at this early stage of development. These McAbs should therefore be of value in identifying factors involved in the differentiation of myotubes into fast and slow muscle fibres.

Adult↗
PubMed1983

Human fetal muscle-specific antigen is restricted to regenerating myofibers in diseased adult muscle.

A monoclonal antibody, 5.1H11, directed against human fetal muscle and myogenic cells in tissue culture, was used for immunofluorescence analysis of frozen sections of muscle biopsies from 24 patients with different diseases of muscle. The staining pattern was highly specific; detectable levels of the 5.1H11 antigen were restricted to regenerating myofibers as assessed by comparison with serial sections stained with hematoxylineosin. There was no appreciable staining of intrafusal, normal adult extra fusal, denervated, degenerating, or necrotic muscle fibers. Thus, the 5.1H11 antibody allows unambiguous identification of regenerating myofibers in biopsy specimens.

Adolescent↗