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Biomedical subjects

M Miranda

Publications and source records attributed to M Miranda.

At least 163 records · Page 9Linked to original sources
PubMed1983

Harding-passey mouse-melanoma tyrosinase inactivation by reaction products and activation by L-epinephrine.

1. Harding-Passey mouse-melanoma tyrosinase (EC 1.14.18.1) is inhibited during L-3,4-dihydroxyphenylalanine oxidation by reaction products. L-3,4-dihydroxyphenyl 3-[14C]alanine oxidation products bind to the enzyme, as demonstrated by gel electrophoresis and radioactivity measurements. 2. The enzyme interacts with indoles and oxidizes dopamine and norepinephrine. 3. L-epinephrine activates tyrosinase at non hormonal concentrations and bovine serum albumin protects the enzyme from auto-inhibition. 4. The inhibition of the Harding-Passey mouse-melanoma tyrosinase, during substrate oxidation, is very similar to that of mushroom enzyme.

Animals↗
PubMed1982

Developmental aspects of hexose metabolism in Bufo bufo.

Due to the close correlation between glucose mobilization and utilization within animal tissues, in this paper, the stages of appearance of phosphorylase, glucose-6-phosphatase and hexokinase as well as the levels of some intermediates of glucose metabolism have been investigated during Bufo bufo development. Phosphorylase first appears at stage 13 and is dominant in the neural part of the embryo, but, after this stage, increases relatively more in the nonneural one. Hexokinase appears at stage 17 and glucose-6-phosphatase soon after. Phosphorylase appearance at stage 13 is correlated with an increase of lactate content in the embryo; this may indicate a metabolization of hexoses. On this basis, the subsequent appearance of hexokinase and glucose-6-phosphatase activities also seems coherent with hexose mobilization and utilization within embryo. No direct causative factor for the changes observed was evident.

Animals↗
PubMed1982

A study on melanogenesis and catecholamine biosynthesis during Bufo bufo development.

Tyrosinase and L-DOPA decarboxylase activities have been investigated during Bufo bufo development since catecholamines and melanin are formed from common substrates in homologous cells. Catecholamines first appear at stage 13 (neural plate), but tyrosinase, at a very low level, and L-DOPA decarboxylase are present throughout all of prior development. Hence, L-DOPA decarboxylase activity is not likely to be correlated with the control of catecholamine synthesis, although at stage 17 it is mainly localized in the nonneural part of the embryo. The distribution of young melanosomes and L-DOPA decarboxylase suggest a separation between melanogenesis and catecholamine synthesis.

Animals↗
PubMed1982

In situ immunofluorescent visualization of chromosomal transcripts in polytene chromosomes.

The induction and distribution of chromosomal transcripts in the polytene chromosomes of D. melanogaster and D. hydei has been investigated by indirect immunofluorescence using an antiserum directed against DNA/RNA hybrids. The fluorescence was intense and occurred in most of the chromosomal subdivisions when the chromosomes were exposed to denaturing conditions and then allowed to reanneal. The extent of hybrid formation depended both on the extent of DNA denaturation and on the maintenance of RNA integrity. Fluorescence was absent from chromosomes treated with pancreatic RNase before denaturation. The velocity of the chromosomal DNA/RNA hybridization reaction and the effects of the initiation inhibitor of RNA synthesis, DRB, suggest that in order to hybridize the RNA has to be located in its transcriptional compartment. Even though overall patterns of fluorescence seem to be similar during a developmental stage, variations were observed, particularly some correlated with puff induction after ecdysone stimulation.

Animals↗
PubMed1981

Manometric characteristics of the extrahepatic biliary tract in dogs.

Pressure measurements of the whole extrahepatic biliary tract were performed in dogs using constant perfusion techniques. Studies were done during general anesthesia and in conscious trained dogs. Gallbladder intraluminal fasting pressure was significantly lower than common bile duct pressure. No motor activity was demonstrated in the common bile duct. At the cysticocholedochal junction a static high-pressure zone was observed, probably due to mechanical factors. At the level of the choledochoduodenal junction, a high-pressure zone with a sphincter behavior was demonstrated, with a resting pressure of 38 cm H2O above intraduodenal pressure and with rhythmic contractions with a mean amplitude of 88 cm H2O above duodenal pressure. Duodenal motility was completely different from sphincter dynamics. No differences in pressure values were seen during general anesthesia or in conscious state.

Animals↗
PubMed1981

Some properties of Bufo bufo tyrosinase during development.

Tyrosinase expression during Bufo bufo development has been investigated. Until stage 19, only 1 electrophoretic band is detectable, but at a later stage (25) 3 bands appear. The Km for L-3,4-dihydroxyphenylalanine (L-dopa) was also determined.

Animals↗
PubMed1981

Perimeter and location of the muscular gastroesophageal junction or 'cardia' in control subjects and in patients with reflux esophagitis or achalasia.

The location and perimeter of the true muscular gastroesophageal junction or cardia were determined during operation in 6 patients with achalasia, in 20 control subjects, and in 40 patients with reflux esophagitis. These two latter groups were submitted to highly selective vagotomy, owing to duodenal ulcer in the control subjects and as part of the surgical technique in reflux esophagitis patients. The careful dissection and isolation of the distal 5-6 cm of the esophagus and esophagogastric junction permitted us to measure the location and perimeter very precisely. There was a very close correlation between the distance incisors-beginning of gastroesophageal sphincter measured preoperatively and the distance incisors-cardia measured during surgery. The cardia could be clearly identified by external inspection corresponding to the limit between the longitudinal muscle layer of the esophagus and the serosal surface of the stomach. The perimeter of the cardia in the patients with reflux esophagitis was significantly larger than the perimeter of the control subjects (p less than 0.001). Intraoperative manometry demonstrated that the external limit of the cardia corresponded to the beginning of the gastroesophageal sphincter. Patients with achalasia had significantly smaller perimeter than controls or reflux esophagitis patients (p less than 0.001).

Adult↗
PubMed1981

[Treatment of juvenile rheumatoid arthritis (author's transl)].

A revision of the treatment of the juvenile chronic arthritis (JCA) is made, Salicylates, still in use, require control of the salicylate level in order to obtain a higher efficiency and to prevent toxicity. New drugs appeared in the last years (by-products of propionic acid, tolmetin acid, fenclofenic...), are useful as an alternative for salicylates and with very little toxicity. Steroid therapy has to be reserved for serious systemic illness only, and slow acting drugs as antimalarials, gold and pencillamine, were only used in those cases with severe persistant activity and in cases of corticosteroid dependents. Use of the immunosuppressive therapy, is justified only in exceptional cases. Immunostimulants (transfer factor, Levamisol) are still in experimental phase. Presentation of the last five years' experience of the Pediatric Department is given. It concerns 25 cases of JCA, 5 systemic forms, 9 polyarticular and 11 forms of pauci-articular. Therapy is based on the predominant use of aspirin and on steroid therapy for the system forms. The efficiency of the treatment is not easy to evaluate regarding consideration of the unpredictable evaluation of the illness.

Adjuvants, Immunologic↗
PubMed1980

Abnormal atrioventricular nodal response patterns in patients with long-term Chagas' disease.

Thirty-two volunteers with positive serologic tests for Chagas' disease were submitted to electrophysiologic studies. No one had documented tachyarrhythmias, heart failure, PR interval shorter than 0.12 or longer than 0.20 msec, pre-excitation or cardiac enlargement. The atrioventricular (AV) nodal function study under programmed atrial stimulation revealed abnormal AV nodal function in nine (28.1 percent) with long-term Chagas' disease. Due to the high incidence of the longitudinal dissociation in this disease, and based on previously reported histopathologic findings that demonstrate the involvement of the right side of the AV node and His bundle, this study suggests that the abnormal AV nodal responses may be secondary to the organic alterations produced by Chagas' disease.

Adult↗
PubMed1979

Inhibition of tyrosinase by indole compounds and reaction products. Protection by albumin.

Tyrosinase activity decreases as the reaction proceeds and is inhibited by L-3,4-dihydroxyphenylalanine oxidation products. Indole and tryptophan inhibit tyrosinase reaction and bovine albumin protects against end-product(s) inhibition or inactivation. Since the same tyrosinase reaction products are indole compounds and some authors reported the binding of indole derivatives with albumin, it is here suggested that indole intermediates of melanin synthesis inhibit or inactivate tyrosinase.

Basidiomycota↗
PubMed1979

Identification of Candida lusitaniae as an opportunistic yeast in humans.

Four yeast strains, causally associated with infection in a patient with acute myelogenous leukemia, were identified by standard methods currently used in yeast taxonomy as representatives of Candida lusitania van Uden et do Carmo-Sousa. Because this species has not been recognized previously as an opportunistic yeast in humans, molecular taxonomic methods were applied to confirm its identity. The nuclear deoxyribonucleic acid (DNA) base composition of two clinical isolates was shown to be 45.1 mol% guanine plus cytosine as compared to 44.7 mol% guanine plus cytosine for the type strain of this species. DNA/DNA reassociation experiments revealed more than 95% complementarity between the DNAs from the clinical isolates and that of the type strain of C. lusitaniae, thus confirming their classification by conventional taxonomy. A key is provided to differentiate C. lusitaniae from two phenotypically similar Candida species.

Blood↗