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Biomedical subjects

M C Pereira

Publications and source records attributed to M C Pereira.

At least 19 recordsLinked to original sources
PubMed1999

Mapping the gene causing hereditary primary hyperparathyroidism in a Portuguese kindred to chromosome 1q22-q31.

A Portuguese kindred with autosomal dominant isolated primary hyperparathyroidism (HPT) that was associated with parathyroid adenomas and carcinomas was investigated with the aim of determining the chromosomal location of this gene, designated HPTPort. Leukocyte DNA from 9 affected and 16 unaffected members and 7 parathyroid tumors from 4 patients was used in comparative genomic hybridization (CGH), tumor loss of heterozygosity (LOH), and family linkage studies. The CGH studies revealed abnormalities of chromosomes 1 and 13, and the results of LOH studies were consistent with the involvements of tumor suppressor genes from these regions. Family segregation studies mapped HPTPort to chromosome 1q22-q31 by establishing linkage with eight loci (D1S254, D1S222, D1S202, D1S238, D1S428, D1S2877, D1S422, and D1S412) (peak two-point LOD scores = 3. 46-5.14 at 0% recombination), and defined the location of HPT Port to a 21 cM region flanked centromerically by D1S215 and telomerically by D1S306. Thus, HPTPort has been mapped to chromosome 1q22-q31, and a characterization of this gene will help to elucidate further the mechanisms that are involved in the development of parathyroid tumors.

Adenoma↗
PubMed1998

Evaluation of nickel toxicity on liver, spleen, and kidney of mice after administration of high-dose metal ion.

The toxic effects caused by nickel (Ni) per si were explored by performing in vivo studies on mice following subcutaneous administration of a metallic solution of nickel at 1, 2, 3, and 4 weeks to evaluate the side effects of this metal ion when released from stainless steel implants. Other groups were similarly injected with HBSS and used as controls. Accumulation of Ni ions on liver, spleen, and kidney was assessed by an electrochemical method, adsorptive stripping voltammetry (AdSV) using microelectrodes, and atomic absorption spectrometry (AAS). Alterations of those organs induced by Ni ions were studied, showing that several histological changes had been induced. Chemical analysis and histological features indicate that Ni is partially accumulated in the study organs.

Animals↗
PubMed1998

Adsorptive stripping measurements of iron accumulation in mice kidney using microelectrodes and histological features.

The toxic effects caused by iron in kidney was performed on experimental studies with mice following administration of a metallic solution of this species to simulate the iron corrosion products of a metallic implant. To quantify the total levels of iron present in this organ, an electrochemical method was chosen based on the application of square wave voltammetry using adsorptive collection of iron-catechol on a mercury film microelectrode (MFM). The optimal working conditions to produce a very stable and reproducible iron peak in the digested kidney samples were found to be pH = 7.2 provided by 8.0 mmol/L PIPES buffer, catechol concentration of 3.0 x 10(-4) mol/L, deposition potential -1.80 V and deposition time 20 s. These results were compared with those obtained by atomic absorption spectrometry (AAS) indicating a good performance of the electrochemical method used. The analytical results show an increase of iron concentration with treatment time, which indicates that this metal ion is partially accumulated in the kidney. This accumulation induces with time some morphological alterations as evidenced by the histological analysis.

Animals↗
PubMed1998

[Cutaneous reconstruction at the leg and foot level. Experience in 277 clinical cases].

The authors present their clinical experience of leg and foot reconstruction with 227 clinical cases. Based on these cases the authors analyse the use of 18 musculocutaneous, 53 axial, 72 septocutaneous and 84 free flaps, totalling 29 different kinds of flaps performed. Although no definitive conclusions can be drawn about which are the best flaps for foot and leg reconstruction, the preferential options are pointed out.

Adolescent↗
PubMed1997

Heart muscle cells share common neutral glycosphingolipids with Trypanosoma cruzi.

Neutral glycosphingolipids were isolated from mouse heart muscle cells and their structures were analyzed. The molecular compositions of these glycosphingolipids were examined using column chromatography, HPTLC, GC-MS and fast atom bombardment-mass spectrometry (FAB-MS). Monohexosylceramides are a mixture of glucosyl- and galactosylceramides in a ratio of 1:1, sphingosine as the long chain base and as fatty acyl groups mainly C16, C18 saturated and C22 and C24 hydroxy fatty acids. Dihexosylceramide, identified as lactosylceramide contains C18 sphingosine and C18, C20 and C22 were the major fatty acids. No evidence for the occurrence of hydroxylated fatty acids in this glycolipid could be obtained from the GC-MS data. Our results clearly demonstrated that Trypanosoma cruzi and heart muscle cells have similar glycosphingolipid structures. In addition, heart muscle cells neutral glycosphingolipids have been shown to be immunoreactive. Antibodies reactive with each of the immunogenic glycolipids from heart cells or T. cruzi epimastigotes were present in the sera of human patients with Chagas disease as detected by ELISA. These cross-reactive antigens could be involved in the Chagasic autoimmunity.

Animals↗
PubMed1997

Therapy of post-renal transplantation hyperlipidaemia: comparative study with simvastatin and fish oil.

BACKGROUND: Recipients of renal transplantation (RT) exhibit disturbances of serum lipids and apoproteins that may contribute to their cardiovascular morbidity and mortality. In our renal transplant department the hypercholesterolaemia prevalence at the first and fifth year of RT is 70.0% and 81.2%, respectively. Lipid-lowering therapy has been utilized in many Transplant Units. The aim of our study was to evaluate post-RT hyperlipidaemia control with simvastatin or fish oil. METHODS: Forty-three RT patients (26 men and 17 women) with persistent hypercholesterolaemia and stable graft function which were resistant to a lipid-lowering diet (American Heart Association Step Two) were randomized into two groups and treated for 3 months with simvastatin (S) (10mg/day; n = 25) and fish oil (F) (6 g/day; n = 18). Total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), lipoprotein a (Lp(a)), apolipoprotein A1 (Apo A1), and apolipoprotein B (Apo B) were monitored and at the study baseline they were similar between the two groups. RESULTS: No side effects were detected after 3 months of therapy. In group S, the concentrations of TC (271 +/- 46 mg% vs 228 +/- 49 mg%; P < 0.001), TG (180 +/- 78 vs 134 +/- 45; P < 0.01), LDL-C (177 +/- 40 vs 144 +/- 43; P < 0.01) and Apo B (96 +/- 18 vs 82 +/- 16; P < 0.001) were significantly reduced, and Apo A1 concentration had increased (135 +/- 24 vs 149 +/- 30; P < 0.01). In group F, the concentrations of TC (266 +/- 25 vs 240 +/- 31; P < 0.001), TG (203 +/- 105 vs 156 +/- 72; P = 0.02) and HDL-C (63 +/- 15 vs 53 +/- 12; P < 0.01) were significantly reduced. CONCLUSIONS: We concluded that low-dose simvastatin and fish oil are both effective and safe in correcting post-RT hyperlipidaemia. Further prospective studies with larger follow-up are needed to clarify whether this therapy has an impact on cardiovascular morbidity and mortality in RT patients.

Adult↗
PubMed1994

Calcitonin-producing insulinoma: clinical, immunocytochemical and cytogenetical study.

The case of a patient with a large goitre associated with hypercalcitoninaemia and fasting hypoglycaemia is reported. Pentagastrin (PG) test was negative. Repeated measurements of fasting glycaemia, insulin and C peptide established the diagnosis of insulinoma. After localization by endoscopic ultrasonography, a distal pancreatectomy was performed and a small insulinoma was recovered. Glycaemia and calcitonin (CT) became normal. The tumour cells displayed a strong immunoreactivity for insulin and CT. Cytogenetical evaluation of the tumour revealed a translocation t(1;9) (p13;p22).

Aged↗
PubMed1993

Heart muscle cells acutely infected with Trypanosoma cruzi: characterization of electrophysiology and neurotransmitter responses.

Primary cell cultures of mouse ventricular myocardium were infected with Trypanosoma cruzi, to study the consequences of T. cruzi-muscle cell interaction on the rate of spontaneous contractions, on the responses to norepinephrine, and on action potential parameters. Single cells or small cell groups of infected cultures were subjected to pharmacological and electrophysiological experiments. In concentrations ranging from 1 nM to 100 microM, norepinephrine exerted positive or negative chronotropic effects mediated by alpha-adrenergic receptors. A significant number of infected cells (25%) did not respond to the agonist. Two days after infection the cultures exhibited a higher frequency of spontaneous contractions (20%), paralleled by an increase in firing rate and a decrease in the action potential duration without significant changes in maximum diastolic potential and action potential amplitude. A decrease in alpha-adrenergic receptor-mediated positive chronotropic response to norepinephrine was also observed in 2-day infected cells. Cells made to phagocyte ferritin particles showed an increase in the rate of spontaneous contractions, but no changes in the positive chronotropic responses to norepinephrine. In conclusion, these observations show that during acute infection with T. cruzi, there are alterations in automaticity and in the chronotropic responses to norepinephrine, whose mechanisms are related to the process of parasite endocytosis by the cardiac cells.

Animals↗
PubMed1993

Myofibrillar breakdown and cytoskeletal alterations in heart muscle cells during invasion by Trypanosoma cruzi: immunological and ultrastructural study.

The cytoskeletal organization of normal and Trypanosoma cruzi-infected mouse embryo heart muscle cells (HMC) in primary culture was investigated using immunofluorescence and transmission electron microscopy. Fluorescent probes revealed that in the early stages of infection, up to 24 h, the HMC cytoskeleton appeared to accommodate the intracellular parasites perinuclearly, with only a few cells displaying a slight disturbance in the distribution of filaments. However, as the infection progressed (48 to 72 h), microtubules and desmin filaments were disrupted. Breakdown of myofibrils occurred in regions where the parasites were present, followed by formation of actin polygons. Using Triton X-100 treated whole cell mount, we obtained a striking preservation of the three-dimensional architecture of the cytoskeleton. Combining electron spectroscopic imaging (ESI) with contrast tuning, we detected a highly interconnected cytoskeletal network in normal cells, and a loose network in infected cells. Bundles of filaments running under and over the parasites were also observed. Our results demonstrate that T. cruzi infection induces myofibrillar breakdown and destruction of several cytoskeleton filaments in heart muscle cells.

Animals↗
PubMed1992

A kindred with multiple endocrine neoplasia type 2A associated with pruritic skin lesions.

BACKGROUND: A kindred affected by multiple endocrine neoplasia type 2A (MEN 2A), associated with symmetric, bilateral, scapular pruritic skin lesions (PSL), is reported. METHODS: There were 21 members, including the propositus, in four generations. Screening of 10 family members showed a palpable thyroid tumor in 1 and positive results for a pentagastrin test in 7 others. Two of these patients had surgically confirmed pheochromocytoma. Two others had a biochemical diagnosis of pheochromocytoma but did not have surgery. RESULTS: Medullary thyroid carcinoma was confirmed in five patients and nodular C-cell hyperplasia in another. In five affected adults, PSL were observed in the interscapular region, crossing the midline in some. These lesions were characterized by hyperkeratosis and hyperpigmentation. In all the patients, the pruritus had been present long before the clinical or biochemical diagnosis. Skin biopsies were performed in two of these patients. No amyloid deposits were found (Congo red stain and electron microscopic examination were used). Two children (14 and 6 years old) in the fourth generation complained of scapular pruritus, although skin lesions were not apparent. CONCLUSIONS: Localized PSL must be sought when screening for MEN 2A.

Adolescent↗
PubMed1992

Glycolipid and protein profiles of normal and Trypanosoma cruzi infected heart muscle cells.

Using Triton X-114, glycolipids and proteins were extracted from heart muscle cells (HMC) infected with Trypanosoma cruzi clone Dm28c and from uninfected HMC, and analysed by SDS-PAGE and high-performance thin-layer chromatography (HPTLC). Two major differences were observed: (a) two proteins with a molecular mass of 92 kDa and 69 kDa were present in the uninfected cells but absent from the infected cells and (b) a 70-90 kDa protein band was detected only in parasitized cells. These differences would seem to constitute alterations taking place during the process of cell recognition and/or parasite interiorization. No differences were observed in the respective glycolipid compositions, of control and infected cells analysed by HPTLC. A glycolipid with the same mobility as the neutral glycolipid isolated from epimastigotes of T. cruzi was detected in the uninfected cells. This finding may lend support to the previously described hypothesis that molecular mimicry is implicated in the cardioneuropathology of Chagas' disease.

Animals↗
PubMed1991

Ventilation and perfusion display in a single image.

A new method of ventilation and perfusion display onto a single image is presented. From the data on regions of interest of the lungs, three-dimensional histograms are created, containing as parameters X and Y for the position of the pixels, Z for the perfusion and colour for local ventilation. The perfusion value is supplied by sets of curves having Z proportional to the local perfusion count rate. Ventilation modulates colour. Four perspective views of the histogram are simultaneously displayed to allow visualization of the entire organ. Information about the normal ranges for both ventilation and perfusion is also provided in the histograms.

Adult↗
PubMed1991

A field evaluation of anthelmintics for control of cyathostomes of horses in Brazil.

The anthelmintic efficacy of ivermectin (IVM), piperazine citrate (PPZ) and fenbendazole (FBZ) alone, and combinations of FBZ with varying dosages of PPZ, was evaluated for the control of strongyles of Mangalarga equids. In all cases of positive strongly egg counts per gram of faeces (EPG) before and after treatment, pure populations of cyathostome larvae with eight gut cells were consistently observed in faecal cultures. The faecal egg count reductions (FECR) were evaluated between Day 7 and Day 56 post-treatment. Significant differences (P less than or equal to 0.05) were found between Day 7 and Day 49 when comparing the mean EPG values of IVM with those of the other anthelmintics. PPZ alone and the combination of FBZ (7.5 mg kg-1) and PPZ (55 mg base kg-1) did not show significant differences during the trial; both groups exhibiting an FECR of greater than 90% between Day 7 and Day 30. Horses treated with the combinations of FBZ (7.5 mg kg-1) and PPZ at either 40 or 25 mg base kg-1, and with FBZ alone at either 7.5 or 15 mg kg-1, showed an FECR of less than 90% 2 weeks after treatment. The emergence of a degree of resistance of strongyles to FBZ and PPZ in a segment of the cyathostomes in this population is suggested.

Animals↗
PubMed1987

Is idiopathic hyperprolactinemia a transitional stage toward prolactinoma?

The basal prolactin (PRL) levels on five different days, the PRL responses to thyrotropin-releasing hormone and to domperidone, and the thyroid-stimulating hormone (TSH) responses to domperidone were studied in 75 regularly menstruating women and 44 patients with moderate hyperprolactinemia. It was found that, for the entire sample, the responses to each of the stimuli could be described by a continuous function of the basal PRL levels. The present work provides evidence for the following conclusions: 1) The PRL responses to thyrotropin-releasing hormone and to domperidone merely bring additional diagnostic information relative to basal PRL levels in the occasional patients with macroprolactinemia; 2) there is a continuous spectrum of lactotroph activities in women, ranging from normal secretors through an intermediate group of hypersecretors (with progressively increased serum PRL levels and decreased responsiveness to stimuli) to full-blown prolactinomas; and 3) idiopathic hyperprolactinemia is a heterogeneous entity that includes the above intermediate group of patients, women with macroprolactinemia, and patients with undiagnosed prolactinomas.

Adult↗
PubMed1986

Immunological control of immunotherapy in asthma.

Immunotherapy of allergic diseases first called desensitization or hyposensitization is based on the introduction by parenteral administration or perhaps also by mouth of the allergens which has been considered to be responsible by the clinical symptoms. Immunotherapy partially corrects the imbalance of immune response decreasing IgE response and increasing the production of IgG1 and IgG4 antibodies either by direct effect or by an effect on specific T helpers and T suppressors subsets.

Asthma↗