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Biomedical subjects

M Miranda

Publications and source records attributed to M Miranda.

At least 109 records · Page 6Linked to original sources
PubMed1995

The Educational Commission for Foreign Medical Graduates: global efforts in graduate medical education.

In addition to its certification programme, which assesses the readiness of foreign medical graduates to enter graduate medical education programmes in the USA, the Educational Commission for Foreign Medical Graduates (ECFMG) is involved in a number of other programmes in international medical education. These include: (1) continuing to provide sponsorship for exchange visitors in graduate medical education programmes in the USA; (2) the development of a clinical skills assessment that is currently being introduced in pilot projects in the USA and abroad and will eventually become a component of the ECFMG certification process; (3) funding and administration of two fellowship programmes that provide foreign scholars (clinicians and basic scientists) with the opportunity to spend up to one year in a US medical school; (4) collaboration with the World Health Organization on the upcoming revised edition of the World Directory of Medical Schools; and (5) co-sponsorship, with the World Health Organization, of a consultation on quality medical education oriented towards attaining a global consensus on the definition and the elements of quality in medical education and on the most appropriate ways to evaluate quality.

Education, Medical, Graduate↗
PubMed1995

Molecular cloning of the plasma membrane H(+)-ATPase from Kluyveromyces lactis: a single nucleotide substitution in the gene confers ethidium bromide resistance and deficiency in K+ uptake.

A Kluyveromyces lactis strain resistant to ethidium bromide and deficient in potassium uptake was isolated. Studies on the proton-pumping activity of the mutant strain showed that a decreased H(+)-ATPase specific activity was responsible for the observed phenotypes. The putative K. lactis PMA1 gene encoding the plasma membrane H(+)-ATPase was cloned by its ability to relieve the potassium transport defect of this mutant and by reversing its resistance to ethidium bromide. Its deduced amino acid sequence predicts a protein 899 residues long that is structurally colinear in its full length to H(+)-ATPases cloned from different yeasts, except for the presence of a variable N-terminal domain. By PCR-mediated amplification, we identified a transition from G to A that rendered the substitution of the fully conserved methionine at position 699 by isoleucine. We attribute to this amino acid change the low capacity of the mutant H(+)-ATPase to pump out protons.

Amino Acid Sequence↗
PubMed1995

[Apomorphine test: evaluation of dopaminergic response in patients with Parkinson disease].

Apomorphine is a potent dopaminergic agonist that quickly and predictably reverts parkinsonian symptomatology. In 32 patients (18 male) aged 45 to 83 years old (22 with idiopathic parkinsonism and 10 with parkinsonism of other causes), the dopaminergic response to apomorphine after domperidone administration was assessed using the digital skill test and Webster scale. Twenty patients with idiopathic parkinsonism and 1 with parkinsonism of other causes had a positive response to apomorphine. In 44% apomorphine had adverse effects. All patients with idiopathic parkinsonism and the only patient with parkinsonism of other causes with a positive apomorphine test had a good response to levodopa therapy. It is concluded that apomorphine test has a 95% positive predictive value for idiopathic parkinsonism and is a useful diagnostic tool.

Aged↗
PubMed1995

[Wilson's disease: a review apropos of a clinical experience in 16 patients].

Wilson's Disease is an inherited disorder of copper metabolism. We report 16 patients (6 males) with the disease; 6 had hepatic involvement exclusively, 4 had neurological involvement, 3 had a neurological and hepatic involvement and 3 were asymptomatic. The age onset was 9 years for hepatic and 17 years for neurologic involvement. The mean delay in diagnosis was 14 months. Chronic hepatitis, cirrhosis and fulminant hepatic failure were the clinical forms of liver disease. Patients with neurologic disorders had behavioral disturbances and extrapyramidal manifestations such as dystonia and parkinsonism. Patients had a good response to penicillamine, except 3 that died of liver complications, in whom the treatment was delayed or discontinued. We conclude that this metabolic disease must be suspected in pubertal children and in adults of less than 30 years old with liver disease of unknown origin or behavioral alterations associated to an extrapyramidal syndrome.

Adolescent↗
PubMed1994

[Influences of hyperinsulinemia in the lipid profile of hypertensive patients].

BACKGROUND: Hypertension and dyslipemia are associated with a greater frequency than that randomly expected. The increase in insulinic resistance hyperinsulinemia is one of the factors implicated in the pathogenesis of this association. In the present study the lipid profile of hypertensive patients is analyzed according to the degree of insulinemia. METHODS: The lipid profile (total cholesterol, fraction linked to low density lipoproteins cLDL, high density cHDL, triglycerides and plasma apolipoproteins A1 and B were determined in 87 patients with essential high blood pressure. Moreover an oral overdose of 75 g of glucose was administered with determinations of glycemia, insulinemia and C peptide at the time of glucose administration, 60 and 120 minutes. RESULTS: Upon separation of the hypertense patients into two groups according to the insulinemia achieved following an oral overload of glucose, those hypertensives with a greater degree of insulinemia showed a significant increase in triglycerides (p < 0.05) and also a significant decrease in cHDL (p < 0.001). The hypertensive patients with lower insulinemia showed a significant increase in total cholesterol (p < 0.05) and fraction linked to LDL although the latter was not significant. CONCLUSIONS: Two different lipid profiles may be observed in hypertensive patients: one linked to hyperinsulinemia and characterized by an increase in triglycerides and a decrease in cHDL and another with no relation with hyperinsulinemia which is manifested by an increase in total cholesterol and cholesterol transported by the LDL.

Adult↗
PubMed1994

Carrier detection and microsatellite analysis of Duchenne and Becker muscular dystrophy in Spanish families.

Duchenne and Becker muscular dystrophy (D/BMD) are usually problematical when trying to determine the carrier status of at-risk women, which usually has to be based on haplotype or dosage analysis on Southern blots. Using multiplex polymerase chain reaction (PCR) analysis, we have detected deletions in 20 out of 44 D/BMD families with living affected members (45.5 per cent), more often in sporadic cases of DMD (14/22 with detectable deletion) than in familial ones (4/15), the majority (15/20) occurring in the distal region of the D/BMD gene. Four highly informative short tandem repeat polymorphisms (STRPs), which lie within the distal deletion hot spot of the D/BMD gene, can show loss of heterozygosity in carrier females, providing direct evidence of their carrier status. These STRPs greatly improve informativity, with a combined heterozygosity of 100 per cent and with the majority of families informative for three of the four STRPs. In 14/15 (93 per cent) of the families with distal deletions, the STRPs provided direct information on carrier status, and in some cases, they provide valuable information on recombination breakpoints and non-paternity.

Adolescent↗
PubMed1994

Prenatal diagnosis of Werdnig-Hoffmann disease: DNA analysis of a mummified umbilical cord using closely linked microsatellite markers.

We present a case of prenatal diagnosis of Werdnig-Hoffmann disease, the most severe type of spinal muscular atrophy (SMA). DNA obtained from a mummified umbilical cord of a decreased affected brother of the index case was analysed with four closely linked microsatellite markers [EF1/2a and EF13/14 (D5S125), MAP1B, and JK53CA (D5S112)], flanking the SMA gene, on chromosome 5q11.2-13.3. The fetus was diagnosed as homozygous for the deleterious SMA gene.

Adult↗
PubMed1994

Developmental aspects of detoxifying enzymes in fish (Salmo iridaeus).

The activities of superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, glutathione transferase and glyoxalase I have been studied during the embryologic development of rainbow trout (Salmo iridaeus) and in several other trout tissues to investigate the protective development metabolism. A gradual increase of superoxide dismutase, catalase, glutathione reductase, glyoxalase I and glutathione transferase activities was noted throughout embryo development. In all trout tissues investigated glutathione peroxidase was found to be extremely low compared to catalase activity. The highest activity of superoxide dismutase, glyoxalase I and glutathione reductase was found in liver followed by kidney. No change in the number of GST subunits was noted with the transition from the embryonic to the adult stages of life according to the SDS/PAGE and HPLC analyses performed on the GSH-affinity purified fractions.

Animals↗
PubMed1994

[Evolution of the concept of heath center in the context of the new National Health Service Act and the development of health administration at the local level].

The authors consider the recently passed about the Portuguese health system reform, namely bills Laws 48/90 and 10/93 (the Bases for Health Law and the National Health Service Act) and they existing some contradictions between the two Laws. In this paper the authors try to adopt point out legislation, mainly the Bases for Health Law from August 24, 1990, as a standard for the conceptualization of a model. One of the proposals in this law, the Health Area, is examined according to the functional contents expressed therein. The authors then probe the concept further, suggesting a local health administration function, at in a Health Area and aimed based a population of about 30,000 inhabitants (from 10 to 50 thousand) and headed by a local Health Administration. The duties and the functional and organizational structure of this body are defined; suggestions for its composition are also advanced. Considering the organizational structure, the authors suggest some services to be supervised by the Local Health Administration: a Public Health Service, a Secretariat and Accounting Service, a Social Service and other. The new concept of Health Center, as the primary care providing unit, is introduced, as is the idea of a Family Medicine Unit, whose functions, definition and scope are proposed.

Catchment Area, Health↗
PubMed1994

Cyto-genotoxic species leakage within human melanoma melanosomes. Molecular-morphological correlations.

This work studies the phenotype changes, relating to pigment expression, of a human melanoma cell line. The phenotypic instabilities and proliferation rates are correlated with the production and release in the cell culture medium of active oxygen species and melanin synthesis intermediates. The proliferation rates versus L-tyrosine concentration in the culture media are investigated: a decrease is found when high L-tyrosine is added to the medium. This would be consistent with the release of cytotoxic and/or genotoxic species by melanoma cells. The morphology of melanoma melanosomes is coherent with the leakage of cytotoxic and genotoxic species produced during melanin synthesis.

Cell Division↗
PubMed1993

Purification and characterization of the major glutathione transferase from adult toad (Bufo bufo) liver.

Five forms of glutathione transferase (GST) were resolved from the cytosol of adult common toad (Bufo bufo) liver by GSH-affinity chromatography followed by isoelectric focusing. The major enzyme (GST-7.64; 55% of total activity bound to the column) has a pI value of 7.64, is composed of two subunits each with a molecular mass of 23 kDa, and has the N-terminal amino acid residue blocked. GST-7.64 has also been characterized with respect to amino acid composition, substrate specificity, inhibition characteristics, c.d. spectra and immunological reactivity. The N-terminal sequence of some peptides obtained after tryptic digestion has also been determined. All together the results obtained suggest that the major toad liver GST is distinct from any known GST, including microbial, plant and mammalian GSTs.

Amino Acid Sequence↗
PubMed1993

Analysis of gene expression in mouse preimplantation embryos demonstrates that the primary role of enhancers is to relieve repression of promoters.

Enhancers are generally viewed simply as extensions of promoters, lacking a function of their own. However, previous studies of mouse preimplantation embryos revealed that 1-cell embryos can utilize enhancer-responsive promoters efficiently without an enhancer, whereas 2-cell embryos require an enhancer to achieve the same levels of expression. This suggested that enhancers relieved a repression in 2-cell embryos that is absent in 1-cell embryos. Results presented here demonstrate first that the ability of 1-cell embryos to dispense with enhancers does not result from the absence of specific activation proteins. Under conditions where GAL4-VP16 activated a GAL4-dependent promoter in both embryos, GAL4-VP16 activated a GAL4-dependent enhancer only in 2-cell embryos. Moreover, the role of an enhancer is not to compensate for either changes in promoter requirements, or for reduced levels of promoter-specific transcription factors. Linker-scanning mutations in a natural promoter revealed that both embryos utilized the same promoter elements, and comparison of different promoters revealed that these embryos have equivalent transcriptional capacities. In addition, titration experiments revealed less Sp1 activity in 1-cell embryos where enhancers are dispensable than in 2-cell embryos where enhancers are required. Therefore, we propose that the primary function of enhancers, first evident with formation of a mouse 2-cell embryo, is to prevent repression of weak promoters, probably by altering chromatin structure. Consistent with this hypothesis is the fact that butyrate, an agent that alters chromatin structure, stimulated promoters in 2-cell embryos, but not in 1-cell embryos.

Animals↗
PubMed1993

Transcription enhancer factor-1 (TEF-1) DNA binding sites can specifically enhance gene expression at the beginning of mouse development.

In an effort to identify transcriptional elements that are recognized at different stages of early mouse development, polyomavirus (PyV) enhancer mutations were selected for their ability to support PyV transcription and replication in various mouse undifferentiated embryonal carcinoma (EC) and embryonic stem (ES) cell lines. Several of these enhancer mutations were then isolated, sequenced and tested for their ability to stimulate the PyV early gene promoter in plasmid DNA that was either transfected into EC, ES and fibroblast cell lines, or injected into the nuclei of mouse 1-cell and 2-cell embryos. EC, ES and fibroblast cell lines showed clear preferences for different enhancer configurations, and cleavage-stage embryos (2- to 8-cell stage) strongly preferred the same enhancer configuration favored by ES cells. This 'embryo responsive' (ER) enhancer configuration was characterized by a tandem duplication of the region containing a single point mutation that created a DNA binding site for Transcription Enhancer Factor-1 (TEF-1). ER enhancers stimulated the PyV promoter up to 350-fold in embryos, and were up to 74-fold more active than the wild-type PyV enhancer. Most of the activity from PyER enhancers could be duplicated in 2-cell embryos by synthesizing only the tandemly repeated sequence. Comparison of these synthetic enhancers with ER enhancers confirmed that TEF-1 DNA binding sites were highly preferred in ES cells and cleavage-stage embryos, and suggested that ER enhancer activity resulted primarily from cooperative interaction between either two closely spaced TEF-1 DNA binding sites or two TEF-1 DNA binding sites separated by a third, as yet unidentified, transcription factor binding site. These results provide a prototype of a mammalian embryo responsive enhancer, and suggest that TEF-1 plays an important role in activation of gene expression at the beginning of mammalian development.

Animals↗
PubMed1993

Requirements for promoter activity in mouse oocytes and embryos distinguish paternal pronuclei from maternal and zygotic nuclei.

Fertilization of mouse eggs produces a 1-cell embryo containing both a paternal and maternal pronucleus. These two nuclei combine during the first mitosis to form the zygotic nuclei of 2-cell embryos. This transition is accompanied by the onset of transcription and the decline of maternal mRNA-dependent gene expression. To determine how changes in nuclear composition affect gene expression, plasmid DNA containing a promoter and an enhancer that function throughout a broad host range was injected into nuclei of oocytes and embryos. The requirements for promoter activity in paternal pronuclei of 1-cell embryos were distinct from those in maternal or zygotic nuclei: (1) Paternal pronuclei permitted high levels of promoter activity relative to maternal or zygotic nuclei. (2) Butyrate, an agent that alters chromatin structure, stimulated promoter activity in maternal or zygotic nuclei, but not in paternal pronuclei. (3) The embryo-responsive polyomavirus F101 enhancer also stimulated promoter activity, but only after formation of a 2-cell embryo. Either butyrate or the F101 enhancer stimulated promoter activity in zygotic nuclei to the level observed in paternal pronuclei. Stimulation also was observed with 2-cell embryos containing nuclei of only maternal or paternal origin, but their transcriptional capacity was more limited. These and other results support the hypothesis that the need for enhancers in 2-cell embryos results from repression by chromatin structure, and the role of enhancers is to relieve this repression.

Animals↗
PubMed1993

Developmental aspects of Bufo bufo embryo glutathione transferases.

The expression of glutathione transferase isoenzymes has been studied during the development of Bufo bufo embryo. By analysing the GSH-affinity purified materials in terms of substrate specificities, SDS-PAGE pattern, HPLC elution profile, we conclude that, up to stage 22, no significant changes in the expression of glutathione transferases isoenzymes occurred during Bufo bufo embryo development. At stage 25 the distribution of glutathione transferases was found to be slightly different from those of all other foregoing stages. A marked decrease of embryonic glutathione transferases subunits with a parallel appearance of new structurally and immunologically different subunits was noted in toad liver and kidney. Toad ovary continued to express embryonic glutathione transferase subunits.

Animals↗
PubMed1993

Specific increase of L-dopa levels in plasma upon infusion of tyrosinase containing liposomes.

1. The present paper reports the effects of liposome-entrapped tyrosinase (EC 1.14.18.1. L-Tyrosine, L-3,4-dihydroxyphenylalanine: oxygen oxidoreductase) infusion on the catecholamine contents of rat plasma. The actions of liposomes and free tyrosinase have also been investigated. 2. From the experiments, evidence has been obtained that liposome-entrapped tyrosinase is able to affect specifically L-3,4-dihydroxyphenylalanine (L-DOPA) levels which increase dramatically. 3. The possible use of liposome-entrapped tyrosinase to raise L-DOPA levels in catecholamine related disorders is discussed. 4. Liposomes without tyrosinase provoke no significant changes of catecholamine or L-DOPA levels while free tyrosinase does induce a change but in a less constant fashion than the liposome-entrapped enzyme.

Animals↗