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Biomedical subjects

M Mora

Publications and source records attributed to M Mora.

At least 127 records · Page 7Linked to original sources
PubMed1987

Association of reovirus proteins with the structural matrix of infected cells.

The interaction of reovirus with the cytoskeleton was investigated. The soluble components of infected cells were extracted with the nonionic detergent NP-40 in a physiological buffer, and a cytoskeletal extract was prepared from the detergent-insoluble fraction. We observed a selective association of viral-specified products with the cytoskeleton that was temporally controlled. Viral dsRNA appeared first on the framework but after several hours was found also in the soluble phase, encapsidated in mature virions. The initial viral translation products were associated exclusively with the soluble fraction, but concomitant with the appearance of dsRNA, viral proteins microNS and sigma 3 were detected on the cytoskeleton. Several hours later, all viral proteins were detected on the framework. Viral polypeptide microNS exhibited unique spatial distribution patterns that correlated with viral assembly: Before dsRNA replication, it appeared as diffusely distributed protein; a few hours later, it was detected in punctate foci interconnected by tiny filaments; several hours later, it appeared as an extensive fiber network that traversed the foci. The other viral proteins were detected only within viral foci. MicroNS remained bound to the matrix fraction after treatment with DNase, Mg2+, and high salt, treatments that released other viral proteins. This distribution pattern was virus-directed because passage of virus at high multiplicity of infection induced mutations that prevented assembly of the microNS-coated filament organization. A small fraction of the viral-specified products that included polypeptide microNS, but not viral dsRNA, was coprecipitated from cytoskeletal extracts with proteins of mol wt approximately 55K by monoclonal antibodies that recognized tubulin and vimentin. Disruption of this interaction by long exposure to colchicine did not prevent association of viral proteins or RNA with the matrix, indicating that viral products were not transported through these interactions. The results indicate that reovirus morphogenesis includes temporal and spatial controls not described previously.

Animals↗
PubMed1987

Chicken liver purine nucleoside phosphorylase activity dependency of the redox state of sulfhydryl groups.

1. Double reciprocal plots (1/v vs 1/S) for nucleoside substrates of chicken liver purine nucleoside phosphorylase were non linear at high inosine or deoxyinosine concentrations (greater than 0.1 mM). The appearance of downward curvatures may be correlated with the oxidation of sulfhydryl groups of the enzyme. 2. 5,5'-Dithiobis-(2-nitrobenzoic acid) reacts with four sulfhydryl groups in the native enzyme, but upon denaturation with sodium dodecylsulfate six sulfhydryl groups react with this reagent. 3. Inosine, ribose-1-phosphate, hypoxanthine and orthophosphate partially protect sulfhydryl groups from the reaction with Ellman's reagent. 4. Inhibition of purine nucleoside phosphorylase by p-chloromercuribenzoate and 5,5'-dithiobis-(2-nitrobenzoic acid) follows a second order reaction kinetics.

Animals↗
PubMed1987

Synaptic vesicle abnormality in familial infantile myasthenia.

In familial infantile myasthenia (FIM) the miniature end-plate potential (MEPP) amplitude is normal in rested muscle, but stimulation in vitro at 10 Hz decreases it abnormally, and neuromuscular transmission fails in a few minutes. In search of a morphologic correlate of the transmission failure, we analyzed the densities and diameters of synaptic vesicles in deep and superficial regions of nerve terminals in external intercostal muscles of three FIM patients and three nonweak controls before and after 10-Hz stimulation for 10 minutes. The densities of superficial or deep synaptic vesicles before or after stimulation in FIM were not significantly different from the corresponding control values. The diameters of superficial and deep synaptic vesicles before stimulation were significantly smaller in the three FIM patients than in the three controls. Stimulation in the FIM patients reduced the MEPP amplitude by 51 to 75%, but increased the vesicle diameter in two patients and did not change the vesicle diameter in one patient. Stimulation in the controls reduced the MEPP amplitude by only 16 to 34%, decreased the vesicle diameter in two, and did not change the vesicle diameter in one. Stimulation after treatment with 1 mg/dl hemicholinium markedly reduced the MEPP amplitude in the controls, had no further effect on the transmission defect in FIM, and had no consistent effect on vesicle diameter in FIM or controls. We conclude that synaptic vesicles are abnormally small in rested muscle in FIM, but vesicle size cannot be reliably correlated with the MEPP amplitude in FIM or controls.

Adult↗
PubMed1986

Multimodal therapy for locally advanced breast cancer.

Thirty-one women with stage III breast cancer were prospectively treated with two cycles of cyclophosphamide (Cytoxan), doxorubicin hydrochloride (Adriamycin), fluorouracil, and tamoxifen citrate followed by a simple mastectomy with level I axillary dissection. Postoperatively, four additional cycles of the combination chemotherapy alternating with three cycles of 1500 rad (15 Gy) to the chest wall and lymphatics were given. Seventy-seven percent of patients had a greater than 50% reduction in tumor size after the initial chemotherapy. No tumor size progressed during therapy, and a single patient remained inoperable. Pathologic findings revealed nine patients with only microscopic residual tumor. Nuclear vacuolization was present in 42.8% of tumor cells after chemotherapy vs 14.2% of cells before chemotherapy. The mean follow-up for the groups is 24.3 months. To date, nine patients have had recurrence with only one isolated local recurrence. This therapy is effective in reducing primary tumor size and allows a limited mastectomy to be done with minimal morbidity.

Adult↗
PubMed1986

[Purification and properties of purine nucleoside phosphorylases from bird liver].

Chicken and pigeon liver PNPases differ in their isoelectric points (5.40 and 5.15), in their molecular weights (125,000 +/- 5,000; 78,000 +/- 5,000, determined on Sephadex G-200) and in their subunit molecular weight (62,000 +/- 10%; 75,000 +/- 10%, determined by sodium dodecil sulfate-polyacrylamide gel electrophoresis). The related molecular weights show a dimeric structure for the chicken liver enzyme and a monomeric structure for the pigeon liver enzyme. Activation energies are similar but differ in delta H values. Both PNPases are irreversibly inactivated by p-chloromercuribenzoate and 5,5'-dithiobis-(2-nitrobenzoic acid) when incubated with these reagents; inactivation can be reverted totally or partially by dithiothreitol and 2-mercaptoethanol.

Animals↗
PubMed1985

Phosphorolytic and ribosyl transfer mechanisms of purified chicken liver purine nucleoside phosphorylase.

Purified chicken liver purine nucleoside phosphorylase shows two ionizable groups at the active site whose pKa were near pH 6.9 and 8; the molecular weight (67,000-89,000) depends on the protein concentration. Initial velocity studies and product inhibition patterns were consistent with a random mechanism, which is rapid equilibrium in the phosphorolytic reaction with a dead-end complex, but not in the synthetic reaction. Free inorganic orthophosphate purine nucleoside phosphorylase (Sephadex G-100) catalyzes a pentosyl transfer reaction from inosine to guanine according to a random Bi, Bi mechanism.

Animals↗
PubMed1984

Systemic carnitine deficiency: clinical, biochemical, and morphological cure with L-carnitine.

A 20-year-old woman had systemic carnitine deficiency. Biochemical studies of cultured fibroblasts, skeletal muscle mitochondria, and fluids showed no evidence of other disease that might deplete tissue carnitine stores. Carnitine supplementation produced a dramatic improvement in her clinical condition: she gained weight and strength and recovered brain function, which had deteriorated slightly after repeated episodes of encephalopathy. Lipid droplets disappeared from skeletal muscle and plasma, and muscle carnitine content rose from low to normal values. On treatment, she excreted less carnitine than controls. This form of systemic carnitine deficiency may be due to defective carnitine biosynthesis.

Acids↗
PubMed1983

Congenital myopathy due to phosphorylase deficiency.

A 4-year-old boy had delayed psychomotor development, proximal weakness, increased serum CK, and myopathic EMG. Muscle biopsy was normal, but histochemical stain for phosphorylase showed no reaction. The enzyme defect was confirmed biochemically and in studies of anaerobic glycolysis in vitro. Glycogen concentration was twice normal. Atypical presentations of myophosphorylase deficiency have included progressive weakness of late onset and fatal infantile myopathy. This patient represents another example of clinical heterogeneity.

Child, Preschool↗
PubMed1981

Systemic carnitine deficiency with peripheral nerve involvement morphological and biochemical study.

The patient, a 31-year-old woman, suffered from a weakness of the proximal muscles which subsequently worsened involving the spinal and neck muscles. During the hospitalization, the patient displayed a "burning feet" syndrome. Lab tests showed a moderate increase in CPK, Aldolase, SGPT, SGOT, lactic and pyruvic acids. Needle EMG was interpreted as "myopathic" but a marked reduction of sensitive action potentials was also detected. Muscle biopsy showed neutral lipid accumulation in muscle fibers, many small angular fibers, probably denervated ones were also evident. A liver biopsy showed fatty accumulation in hepatocytes. Free carnitine was extremely reduced in muscle and liver and just below normal level in plasma while there was a tenfold elevation of long-chain carnitine esters in plasma too. The mechanism by which carnitine deficiency can cause both neural and muscular alterations and in particular the role of carnitine in glucose metabolism is discussed.

Adult↗
PubMed1980

"Carnitine deficient" myopathy and cardiomyopathy with fatal outcome.

A 13-year-old boy with a mild limb girdle muscular weakness had a massive rhabdomyolysis and cardiac arrest after general anesthesia. A congestive cardiomyopathy then developed. Muscle biopsy revealed an unspecific "myopathic" degeneration of muscle fibers and a slight accumulation of lipid droplets. Carnitine content was markedly reduced in muscle and moderately in plasma. Both prednisone and carnitine therapies were unable to improve the heart insufficiency, and the patient died 1 year after the acute episode of rhabdomyolysis.

Adolescent↗