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Biomedical subjects

E Bonilla

Publications and source records attributed to E Bonilla.

At least 145 records · Page 8Linked to original sources
PubMed1991

Progressive depletion of fast alpha-actinin-positive muscle fibers in Duchenne muscular dystrophy.

In normal human muscle, a monoclonal antibody against alpha-actinin recognizes an isoform that is only expressed in a population of fast fibers histochemically identified as type IIb or fast-twitch glycolytic. Immunohistochemical studies of muscle biopsies from patients with Duchenne muscular dystrophy (DMD) showed that the number of alpha-actinin-positive type IIb fibers was essentially normal in preclinical patients. Symptomatic patients between the ages of 3 and 5 years showed depletion of these fibers, which were not seen in patients older than 5 years. ATPase histochemistry showed that a few type IIb fibers were present in muscle from symptomatic DMD patients but lacked the fast isoform of alpha-actinin. The data suggest that type IIb fibers are affected early in DMD.

Actinin↗
PubMed1991

Differential diagnosis of fatal and benign cytochrome c oxidase-deficient myopathies of infancy: an immunohistochemical approach.

To differentiate the 2 major myopathies of infancy due to cytochrome c oxidase (COX) deficiency, we studied muscle biopsies from 4 patients with fatal myopathy and 4 with benign myopathy using biochemical, histochemical, and immunohistochemical techniques. Immunohistochemistry with antibodies directed against individual subunits of COX differentiated the 2 phenotypes: the fatal infantile myopathy was characterized by absence of the nuclear DNA (nDNA)-encoded subunit VIIa,b of COX, while in the benign myopathy both VIIa,b and the mitochondrial DNA (mtDNA)-encoded subunit II were absent. Early differential diagnosis between fatal and benign COX-deficient myopathies is of critical importance for prognosis and management of these infants, because the benign form is initially life-threatening but ultimately reversible.

Biopsy↗
PubMed1991

Biochemical and molecular analysis of cytochrome c oxidase deficiency in Leigh's syndrome.

We studied three patients with Leigh's syndrome (LS) and cytochrome c oxidase (COX) deficiency. Biochemical studies in brain, muscle, heart, liver, kidney, and fibroblasts disclosed a generalized COX deficiency. Kinetic studies of COX activity in brain mitochondria showed a low Vmax and a normal Km for reduced cytochrome c. Immunologic studies showed decrease of all COX subunits studied, without a specific defect of any one of them. Southern blot analysis excluded large deletions of mitochondrial DNA (mtDNA) but revealed a generalized increase in mtDNA quantity. Although Northern blot analysis showed no alteration in the 12 COX subunit mRNAs studied, two of three patients showed a decreased steady state rate of COX transcription in brain. COX deficiency in LS thus appears to be related to a decreased amount of otherwise normal COX holoenzyme.

Biochemistry↗
PubMed1991

Dystrophin deficiency in young girls with sporadic myopathy and normal karyotype.

We studied dystrophin in three young girls with a sporadic myopathy of early onset, manifested by mild to severe limb weakness, calf hypertrophy, high serum creatine kinase, normal karyotype, and morphologic features in muscle consistent with muscular dystrophy. DNA analysis did not reveal a deletion of the dystrophin gene. Immunohistochemical studies of dystrophin in muscle biopsies showed a mosaic of fibers with and without dystrophin, and immunoblot analysis showed partial dystrophin deficiency in all three patients, more severe in the patient with the highest proportion of dystrophin-deficient fibers. These observations suggest that the patients are Duchenne muscular dystrophy carriers. The data also support the concept that uneven lyonization in muscle is responsible for the clinical myopathy in these patients. We suggest that any girl with sporadic proximal limb weakness should be evaluated as a possible Duchenne carrier by dystrophin studies.

Child↗
PubMed1991

Mitochondrial encephalomyopathies: biochemical approach.

Thanks to recent advances in the molecular genetics of mitochondrial encephalomyopathies, we can now begin to correlate genetic lesions with biochemical defects. In the fatal infantile myopathy due to cytochrome c oxidase (COX) deficiency, an autosomal recessive condition, immunocytochemical studies have shown an isolated defect of subunit VIIa, which is 1 of the only 2 tissue-specific subunits of human COX. In muscle biopsies from patients with Kearns-Sayre syndrome, a multisystem disorder characterized by deletions of the mitochondrial DNA (mtDNA), the activities of all mitochondrial enzymes containing mtDNA-encoded subunits are decreased. The results of Northern analysis, in situ hybridization, and immunocytochemistry in muscle, and of mitochondrial protein synthesis in cultured fibroblasts suggest that partially deleted mtDNAs are transcribed but not translated, probably due to lack of indispensable tRNAs.

Brain Diseases↗
PubMed1991

mtDNA depletion with variable tissue expression: a novel genetic abnormality in mitochondrial diseases.

We studied two related infants with a fatal mitochondrial disease, affecting muscle in one and liver in the other. Quantitative analysis revealed a severe depletion of mtDNA in affected tissues. This genetic abnormality was also observed in muscle of an unrelated infant with myopathy and in muscle and kidney of a fourth child with myopathy and nephropathy. Biochemistry, immunohistochemistry, and in situ hybridization showed that the depletion of mtDNA in muscle fibers was correlated with a respiratory chain defect and with lack of mitochondrially translated proteins. Although the differential tissue involvement in these infants suggests mtDNA heteroplasmy, sequence analysis of mtDNA replication origins did not reveal any abnormality that could account for the low copy number.

Blotting, Southern↗
PubMed1990

Immunocytochemical study of dystrophin at the myotendinous junction.

Dystrophin is the protein whose deficiency results in Duchenne muscular dystrophy. The protein has homologies with a number of cytoskeletal proteins, is localized at the muscle sarcolemma and it may provide stability to the muscle plasma membrane. Using immunocytochemical techniques, we have studied dystrophin localization at the myotendinous junction, a region of membrane complexity that requires more stability because it is subjected to great mechanical stress during the transmission of contractile force to the tendon. The results showed subsarcolemmal deposits of dystrophin at the junctional folds of the myotendon as well as membrane-associated dystrophin at extrajunctional sarcolemma. The findings suggest that dystrophin may be one of the components linking terminal actin filaments to the subplasmalemmal surface of the junctional folds of the myotendon.

Animals↗
PubMed1990

Involvement of respiratory muscles in cytoplasmic body myopathy--a pathology study.

A muscle biopsy and autopsy study of a child who died at 14 months of respiratory failure is described. A diagnosis of infantile cytoplasmic body myopathy was made due to the high percentage of cytoplasmic bodies (CBs), particularly in respiratory muscles. No pathological abnormalities were found in the central nervous system, peripheral nerves or visceral organs. Immunohistochemical studies suggested that the central core of CBs was stained for fibrillary actin, being surrounded by a positive signal for desmin. A differential diagnosis as to other conditions involving proliferation of CBs is discussed.

Autopsy↗
PubMed1990

Cytochrome c oxidase deficiency.

Cytochrome c oxidase (COX) is a complex enzyme composed of 13 subunits, three of which are encoded by the mitochondrial DNA (mtDNA). The other 10 subunits are encoded by the nuclear DNA, synthesized in the cytoplasm, and transported into the mitochondria. The complexity of the enzyme and its dual genetic control explain the heterogeneity of clinical phenotypes associated with COX deficiency. There are two major syndromes, one characterized by muscle involvement (fatal infantile or benign infantile myopathy), the other dominated by brain disease (Leigh syndrome, myoclonic epilepsy with ragged red fibers, Menkes' disease). Partial defects of COX have been shown in muscle of patients with progressive external ophthalmoplegia, either alone (ocular myopathy) or as part of Kearns-Sayre syndrome. Biochemical studies have documented either muscle-specific or generalized defects of COX; COX deficiency is reversible in the benign infantile myopathy. Immunologically detectable protein may be normal (benign myopathy) or variably decreased (fatal myopathy, Leigh syndrome). The subunit pattern of COX is normal by immunoblot in patients with fatal myopathy and Leigh syndrome; a disproportionate decrease of subunit II was seen in a patient with myoclonic epilepsy with ragged red fibers. Availability of the three mtDNA genes and of complementary DNA probes for eight of the 10 nuclear DNA-encoded subunits makes it possible to investigate the different diseases at the molecular level. Large deletions of mtDNA have been found in patients with ocular myopathy and Kearns-Sayre syndrome: the deleted mtDNA appear to be transcribed but not translated, thus explaining the partial COX deficiency.

Brain Diseases↗
PubMed1990

Widespread tissue distribution of mitochondrial DNA deletions in Kearns-Sayre syndrome.

We performed Southern analysis of mitochondrial DNA (mtDNA) in 6 tissues from a patient with Kearns-Sayre syndrome and found a single deletion of 4.9 kb in all tissues. The percentage of deleted mtDNAs varied widely between tissues, from only 4% in smooth muscle to approximately 50% in skeletal muscle. Samples of DNA obtained from 3 different skeletal muscles and from separate areas of individual tissues showed little variation in percentage of deleted mtDNA. Biochemical analysis showed no clear correlation between mitochondrial enzyme activity and deleted mtDNAs.

Blotting, Southern↗
PubMed1990

Partial dystrophin deficiency in monozygous twin carriers of the Duchenne gene discordant for clinical myopathy.

We studied monozygous twin women, age 63. One, asymptomatic, had a serum creatine kinase (CK) level of 191 units (normal, 1 to 50); her son died of typical Duchenne muscular dystrophy (DMD) at age 18. Her twin sister had symptomatic limb weakness from about age 40. Her serum CK was 495 units. EMG and muscle biopsy were compatible with myopathy. In the asymptomatic twin, the peripheral blood lymphocyte karyotype was 46,XX. In the affected twin, 18% of cells were 45,X, and the others 46,XX, without X/autosome translocation. DNA analysis did not reveal a deletion at the DMD locus. Immunologic studies of dystrophin showed a partial deficiency of the protein that was more severe in the symptomatic twin. The clinical discordance and the different severity of dystrophin deficiency may have resulted from the effects of lyonization.

Creatine Kinase↗
PubMed1990

[Dystrophin in the differentiation between Duchenne and Becker muscular dystrophies: an immunohistochemical study compared with clinical stage, serum enzymes and muscle biopsy].

Study of 55 cases of progressive muscular dystrophies (34 Duchenne, 12 Duchenne with residual dystrophin and 9 Becker patients) comparing age, age at the initial symptoms, duration of symptoms, levels of serum enzymes, degree of disability measured by the Vignos and Archibald scale, and the type and amount of dystrophin found in the muscle biopsies by immunofluorescence. Statistical analysis showed a tendency of the symptoms and progression of disease to be related with the low quantity of dystrophin in the biopsies. There was no difference in the parameter analysed between the Duchenne patients with and without residual dystrophin, as well as the Duchenne with residual dystrophin and Becker patients. There was an inverse relation with the amount of dystrophin and the endomysial connective tissue and fatty infiltration, and a direct relation with hypertrophic fibers and atrophic angulated fibers in the NADH-tetrazolium reductase. In the comments a discussion is made about the difficulties in differentiate Duchenne and Becker dystrophies, the cases with residual dystrophin and the importance of the correct diagnosis.

Adolescent↗
PubMed1990

Mitochondrial encephalomyopathies.

The mitochondrial diseases present with great heterogeneity. They are often multisystemic and vary considerably in age at onset, distribution of weakness, severity, and course. Only nonthyroidal hypermetabolism has a distinctive clinical presentation. Therefore, attempts at classification have generated some controversy. This article discusses the general classification that takes into account genetic and biochemical features, which has resulted from the fast pace of biochemical and molecular genetic investigations.

Brain↗
PubMed1989

Dystrophin in electric organ of Torpedo californica homologous to that in human muscle.

We have found that dystrophin is highly concentrated at neuromuscular junctions and innervated membranes of the electric organ of Torpedo californica. In acetylcholine receptor-rich Torpedo membrane preparations dystrophin represents approximately 0.4% of total protein and can be extracted from these membranes by alkaline treatment in the absence of detergent, indicating that it is a peripheral membrane protein. Polyclonal antibodies raised against electrophoretically isolated Torpedo dystrophin cross-react with dystrophin in human muscle and unequivocally discriminate between normal and Duchenne muscular dystrophy patient's muscle. These results indicate that dystrophin is phylogenetically a highly conserved protein and that the relatively abundant dystrophin in electric organ would facilitate further investigations of its structure and function.

Animals↗