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Biomedical subjects

E Bonilla

Publications and source records attributed to E Bonilla.

At least 199 records · Page 11Linked to original sources
PubMed1985

Mitochondrial myopathies.

Mitochondrial myopathies are clinically heterogeneous disorders that can affect multiple systems besides skeletal muscle (mitochondrial encephalomyopathies or cytopathies) and are usually defined by morphological abnormalities of muscle mitochondria. There are a few distinctive syndromes, such as the Kearns-Sayre syndrome; myoclonus epilepsy with ragged-red fibers; and mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes. Biochemically, mitochondrial myopathies can be divided into defects of substrate utilization, oxidation-phosphorylation coupling, and the respiratory chain. Because mitochondria have their own DNA and their own translation and transcription apparatuses, mitochondrial myopathies can be due to defects of either a nuclear or mitochondrial genome and can be transmitted by mendelian or maternal inheritance.

Carnitine↗
PubMed1985

Ultrastructural localization of anionic phospholipids in skeletal muscle plasma membrane.

Polymyxin B was used as a probe to label anionic phospholipids in skeletal muscle plasma membrane. This antibiotic produces muscle surface membrane lesions that can be identified in both thin sections and freeze-fracture replicas. The membrane perturbations assumed a patchy distribution with a preferential localization at the level of the I band and A-I bands junction. Intramembraneous particles were also observed within the lesions. We consider the possibility that microdomains of anionic phospholipids in muscle plasma membrane may function in the binding of Ca++.

Animals↗
PubMed1985

Fatal infantile cytochrome c oxidase deficiency: decrease of immunologically detectable enzyme in muscle.

A 2-month-old boy had progressive generalized weakness, hypotonia, and respiratory insufficiency requiring assisted ventilation. At age 3 1/2 months, he started having seizures and recurrent pulmonary infections; he died at age 7 months. Serum lactate was chronically elevated, but there was no aminoaciduria. Histochemical and ultrastructural studies of muscle biopsies at ages 2 and 3 months showed excessive mitochondria, lipid, and glycogen; a third biopsy at 6 months showed marked increase in perimysial fibrous and fat tissue. Cytochrome c oxidase activity was 7% of normal in the first biopsy and undetectable in the others. Cytochrome spectra of mitochondria isolated from postmortem muscle showed complete lack of cytochrome aa3. Antibodies were obtained against cytochrome c oxidase purified from normal human heart. Immunotitration and enzyme-linked immunosorbent assay (ELISA) showed decreased immunologically reactive enzyme protein in the patient's muscle, but SDS-PAGE electrophoresis of immunoprecipitates of muscle mitochondrial extracts showed the presence of all cytochrome c oxidase subunits. These data suggest that decreased synthesis of one or more subunits may result in markedly decreased concentration of electrophoretically normal complex IV in skeletal muscle.

Cytochrome-c Oxidase Deficiency↗
PubMed1984

(3H) spiroperidol binding decreases in brains of rats infected with Venezuelan equine encephalomyelitis virus.

After i.p. inoculation with the Guajira strain of Venezuelan equine encephalomyelitis virus a significant decrease in the density of (3H) spiroperidol binding sites in the striatum, midbrain and frontal cortex was observed. No changes in the affinity of the receptors could be demonstrated. This finding is compatible with neuronal degeneration caused by the viral infection.

Animals↗
PubMed1984

Copper distribution in the normal human brain.

Copper concentration was determined in samples from 38 areas of 7 normal human brains. The grey matter contained higher concentrations of copper than the white matter. Identical areas of the grey and white matter of the cerebral cortex showed significant differences between individuals. In the caudate nucleus the highest concentrations of copper were found in the tail followed by the body and the head, respectively. A negative linear regression between age and brain copper levels was demonstrated.

Adolescent↗
PubMed1984

Chronic manganese intake induces changes in the motor activity of rats.

Two groups of adult male Sprague-Dawley rats were treated with manganese added to the drinking water in concentrations of 0.1 and 5.0 mg Mn2+/ml. Age-matched controls received distilled demineralized water. Spontaneous motor activity, measured in 60-min weekly sessions during 8 months, showed a significant increase during the 1st month. Further exposure did not affect the motor activity to 6 months. But, on months 7 and 8 a significant reduction was observed compared with controls. Both hyper- and hypoactivity were not dose-dependent as the results obtained in both groups of manganese-exposed rats were similar. These findings should make health authorities aware of the potential involvement of low doses of manganese in the development of early behavioral problems long before the irreversible neurologic damage is established.

Animals↗
PubMed1984

Distribution of freeze-fracture particle sizes in Duchenne muscle plasma membrane.

We studied the distribution of freeze-fracture intramembranous particle (IMP) sizes in Duchenne muscle biopsies and controls. We found that the previously reported decrease in muscle plasma membrane particle density in Duchenne includes a variety of different IMPs, but does not preferentially involve IMPs of any one size.

Cell Membrane↗
PubMed1984

Immunocytochemical localization of the mammalian voltage-dependent sodium channel using polyclonal antibodies against the purified protein.

Antibodies were raised in rabbits against the purified voltage-dependent sodium channel from rat skeletal muscle sarcolemma. The resultant antiserum reacted with the purified channel in a solid-phase radioimmunoassay and precipitated the sodium channel from a crude mixture of solubilized membrane proteins. Crude membrane proteins separated according to size under nondenaturing conditions by chromatography on Sepharose CL-6B contained a single peak of immunoreactivity that coincided with the native channel. On immunoblots of sarcolemmal membrane proteins, the antiserum reacted predominantly with a diffuse high molecular weight band that was comparable in migratory characteristics to the large glycoprotein subunit of the purified channel. Using immunocytochemical techniques, binding of this polyclonal antiserum was localized to the surface membrane of rat skeletal muscle. This staining was specifically blocked by pre-incubation of the antiserum with the purified channel protein. The antiserum also stained the surface membrane of rat cardiac muscle and the nodes of Ranvier in rat peripheral nerve. Species cross-reactivity was seen with mouse, human, and guinea pig skeletal muscle while chicken, rabbit, and frog muscle was not stained. The antiserum also reacted with the surface membranes of fetal rat muscle in tissue culture. These results indicate that sodium channels in adult mammalian skeletal muscle, cardiac muscle, and peripheral nerve and in fetal muscle in culture all share common antigenic determinants. The antiserum should prove useful for topographical studies of sodium channel distribution in these tissues.

Animals↗
PubMed1983

Freeze-fracture analysis of plasma membrane cholesterol in Duchenne muscle.

We estimated cholesterol in Duchenne muscle plasma membrane using the sterol-specific ligand digitonin. In measuring the extent of digitonin-cholesterol complex formation with freeze-fracture electron microscopy, we found a significantly greater proportion of surface area taken up by complexes in Duchenne muscle (60% +/- 9%) than in controls (36% +/- 4%). This finding suggests that a population of Duchenne muscle fibers has a higher concentration of cholesterol in the plasma membrane. Membrane cholesterol is known to affect membrane deformability and the activity of membrane-bound enzymes and transport proteins; thus a difference in membrane cholesterol might account for structural and functional abnormalities in Duchenne plasma membrane.

Cell Membrane↗
PubMed1983

Ultrastructural study of the muscle cell surface.

In human muscle fibers and using tannic acid-glutaraldehyde fixation and freeze-fracture deepetch rotary replication, trabecular structures connecting the basal lamina to the outer leaflet of the muscle plasma membrane were observed. The trabeculae were noted at all levels of the sarcomere in regions away from the myotendinous junction. It is suggested that trabecular structures connecting the basal lamina to the plasma membrane may be a universal feature of the muscle cell surface.

Adult↗
PubMed1983

Freeze-fracture study of muscle plasma membrane in obligate carriers of Duchenne muscular dystrophy.

Diminution of intramembranous particles and increase in the number of caveolae have been reported in freeze-fractured muscle plasma membrane of patients with Duchenne muscular dystrophy. We searched for similar alterations in a population of muscle plasma membranes from obligate carriers of Duchenne muscular dystrophy. There were no significant changes in muscle plasma membrane morphology in carriers and normal controls.

Adult↗
PubMed1983

Muscle plasma membrane abnormalities in infants with Duchenne muscular dystrophy.

Muscle biopsies from one preclinical case, one early case, four symptomatic cases of Duchenne muscular dystrophy, and six controls were investigated for the presence of delta lesions by phase optics and conventional electronmicroscopy. By phase microscopy the frequency of delta lesions was 4.9% in the preclinical and early cases and 4.0% in the four symptomatic cases. The incidence of delta lesions in the controls was 0.4%. Electronmicroscopic studies of delta lesions revealed similar findings in the preclinical, early, and symptomatic cases. The common denominator of the delta lesions was disruption of the muscle plasma membrane. Plasma membrane lesions occur early in Duchenne muscular dystrophy.

Cell Membrane↗
PubMed1982

Effect of Venezuelan equine encephalomyelitis virus infection on brain choline acetyltransferase and acetylcholinesterase activities.

Mice and rats infected with the Venezuelan equine encephalomyelitis virus showed a significant decrease in the choline acetyltransferase activity of caudate nucleus, hypothalamus, midbrain, hippocampus and frontal cortex. Acetylcholinesterase activity was not affected in any of the same brain regions analyzed. In surviving rats no alterations were observed in the activities of choline acetyltransferase, tyrosine hydroxylase, and glutamate decarboxylase 3 months after the infection.

Acetylcholinesterase↗
PubMed1982

Freeze-fracture characterization of 'young' and 'old' human erythrocytes.

While 'young' and 'old' erythrocytes separated by density show differences in various biochemical properties, the membrane ultrastructure as demonstrated by freeze-fracture remains unchanged. This implies that although superficial membrane components may be affected by aging, and whole segments of membrane may be lost, the structural relationship between integral protein and lipid in the remaining membrane is not altered.

Erythrocyte Aging↗
PubMed1982

The regional distribution of manganese in the normal human brain.

The concentration of manganese per gram dry tissue weight was determined in samples from 39 areas of 8 normal human brains. Manganese was shown to be unevenly distributed with the largest concentrations in the pineal gland and the olfactory bulb. The gray matter yielded a higher content of manganese than the white matter. Significant differences between individuals were found for identical areas of the gray and white matter of the cerebral cortex. Higher levels of manganese were demonstrated in the tail of the caudate nucleus than in the body and the head of the same structure. No significant correlation was shown between the amount of manganese in brain and age.

Adolescent↗