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Biomedical subjects

A Miranda

Publications and source records attributed to A Miranda.

At least 109 records · Page 6Linked to original sources
PubMed1984

Phosphoglycerate kinase deficiency myopathy: biochemical and immunological studies of the mutant enzyme.

A new phosphoglycerate kinase variant (PGK New Jersey) has been purified from muscle and cultured fibroblasts of a patient with recurrent myoglobinuria. The mutant enzyme had higher than normal affinity for adenosine triphosphate (ATP) and 3-phosphoglycerate, and a shift of the pH optimum towards the acidic side. Antibodies raised against PGK purified from normal muscle were used to evaluate the presence of immunologically cross-reacting enzyme protein in tissues from the patient. Immunodiffusion and an antibody consumption test showed the presence of reduced amounts of cross-reacting material in the patient's muscle. Several PGK variants have been characterized in asymptomatic individuals or in patients with hemolytic anemia. The biochemical features of PGK New Jersey, the only known variant associated with recurrent myoglobinuria, distinguish this mutant enzyme from others.

Adolescent↗
PubMed1984

[Squaric acid dibutyl ester in the treatment of severe alopecia areata].

The results of the treatment with topical applications of squaric acid dibutylester in seven cases of severe alopecia areata are reported. In adult patients this form of therapy is very effective to achieve a total hair regrowth, but its use should be strictly limited to the most serious cases, recalcitrant to other therapeutical methods.

Adjuvants, Immunologic↗
PubMed1978

McArdle disease: the mystery of reappearing phosphorylase activity in muscle culture--a fetal isoenzyme.

To understand the apparently paradoxical appearance of phosphorylase in muscle cultured from patients with McArdle disease, the enzyme in muscle culture was studied immunologically and electrophoretically. Antibody against normal human muscle phosphorylase completely inhibited the enzyme of adult muscle, but it had no effect on phosphorylase activity of muscle cultures from normal individuals or patients with McArdle disease. Also, amounts of antibody that would completely inhibit phosphorylase in mature muscle left about 30% of the activity in muscle obtained from human fetus at four months' gestation. Acrylamide-disc and slab-gel electrophoresis showed a single band of phorphorylase activity in adult muscle and two bands in fetal muscle. This suggested that at four months' gestation, both fetal and mature forms are present but that only the mature isoenzyme is inhibited by the antibody. The enzyme from cultured muscle gave only a single band, with the electrophoretic mobility of the fetal isoenzyme. These data suggest that phosphorylase activity in muscle cultured from patients with McArdle disease is due to a fetal isoenzyme whose genetic control is different from that of the mature enzyme.

Antibody Formation↗
PubMed1977

A new juvenile hexosaminidase deficiency disease presenting as cerebellar ataxia. Clinical and biochemical studies.

A boy with mild hand tremor since age 2 1/2 was found at 4 to have cherry-red spots and mild trucal ataxia without seizures or dementia. Biochemically, he had striking hexosaminidase deficiency (serum: 4.6 percent of normal, 88.9 percent heat-labile; leukocyte: 2.2 percent of normal, 84.6 percent heat-labile; fibroblast 12.8 percent normal, 93.1 percent heat-labile). The residual hexosaminidase activity migrated electrophoretically in two bands. The major band comigrated with hexosaminidase A, the minor with hexosaminidase S. Hexosaminidase B was totally absent. The parents had partially reduced hexosaminidase with a decreased heat-stabile fraction. This disorder may result from a new mutation closely related to that causing Sandhoff-Jatzkewitz disease.

Cerebellar Ataxia↗
PubMed1976

Antibodies to acetylcholine receptors in rabbits: immunochemical and electrophysiological studies.

Acetylcholine receptors (AChR), purified from electric eel and Torpedo by affinity chromatography using a synthetic quaternary ammonium ligand, bound 10 nmole alpha-bungarotoxin (alpha-BuTx) per mg of protein and demonstrated a common subunit. Rabbits, immunized with either eel or Torpedo/AChR, developed flaccid paralysis barely altered by anticholinesterases and died 48 hours after the first sign of paralysis. In paralyzed animals, repetitive stimulation at low rates induced a 50% to 90% decrement of evoked potentials, temporarily reversed by edrophonium. Extracellular and introcellular MEPP amplitudes were 40% to 50% of controls. Serum and isolated IgG formed single immunoprecipitin lines against the antigens. AChR-antibody complexes did not bind alpha-BuTx, whereas alpha-BuTx-AChR complexes bound antibody if the antibody was specific for that AChR. Torpedo and eel AChR showed partial idenity with both antisera. Rat diaphragms and eel electroplax incubated with antisera to Torpedo and eel AChR showed a 50%-60% reduction in carbamylcholine depolarization. These studies demonstrate differences between eel and Torpedo AChR induce a block in neuromuscular transmission in rabbits with features of myasthenia gravis.

Acetylcholine↗
PubMed1976

Adenyl cyclase abnormality in Duchenne muscular dystrophy: muscle cells in culture.

Cultured muscle cells from patients with Duchenne muscular dystrophy differed from cells of normal individuals and of patients with other muscle diseases. In Duchenne cells, basal activity of adenyl cyclase of myotubes was higher and was not stimulated significantly by epinephrine or isoproterenol, as it was in fused control cells, and the response to fluoride was less. The genetic defect in this disease may be an abnormality of the sruface membrane of muscle.

Adenylyl Cyclases↗
PubMed1975

Electron-microscopic, cytochemical and biochemical studies of acetylcholinesterase and butyrylcholinesterase activity in muscle of dystrophic mice.

We have studied extrajunctional muscle of control and dystrophic mice by electron microscopic-cytochemistry and radiometric assay. We have found both a soluble and particulate AChE activity, which is similar proportionally in control and dystrophic muscle. The particulate AChE activity is probably due to the enzyme localized in the sarcotubular system. These sites are more numerous in muscle adjacent to the motor end-plant than in distally located extrajunctional muscle, and are increased markedly in the dystrophic mouse. Myoblasts and small muscle fibers in the dystrophic mouse also have AChE activity in the reticulum similar to fetal muscle. The soluble AChE activity identified radiometrically may represent those sites exhibiting random cytochemical end-product, such as some muscle nuclei, satellite cells, myogenic mononuclear cells in the connective tissue, and degenerating axonal boutons no longer associated with junctional folds of muscle. Enzyme activity is present in degenerating fibers, but it is randomly dispersed in the sarcoplasm rather than membrane-bound. AChE activity has not been found in debris of completely necrotic muscle. BuChE activity is higher and the number of BuChE-active sites in the sarcotubular system adjacent to the motor end-plates is greater in dystrophic muscle than in control muscle.

Acetylcholinesterase↗