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Biomedical subjects

A Guimarães

Publications and source records attributed to A Guimarães.

At least 37 records · Page 2Linked to original sources
PubMed1998

Noval mutation (Y184C) in exon 4 of the beta-sarcoglycan gene identified in a Portuguese patient. Mutations in brief no. 177. Online.

We report a novel beta-sarcoglycan gene mutation identified in a 21-year-old Portuguese male with a progressive myopathy of intermediate severity, who had been misdiagnosed as Becker Muscular Dystrophy (BMD) based on clinical observations and muscle immunocytochemical anaylsis with dystrophin antibodies only. Since no detectable deletions or duplications were found in the dystrophin gene, we screened for mutations in the sarcoglycan genes by PCR-SSCP. The patient's sample showed a band of increased mobility in exon 4 of the beta-sarcoglycan gene which, upon sequencing, was found to represent a homozygous A-->G transversion at nucleotide 551, resulting in a tyrosine to cysteine substitution at position 184 (Y184C). Carrier status was ascertained in both parents and a sister. These aberrant conformers were not detected in 85 unrelated control individuals screened by PCR-SSCP analysis. All seven beta-sarcoglycan mutations reported to date are associated with a severe phenotype and occur in exons 3 and 4, which correspond to the immediate extracellular domain of the protein. This region contains five conserved cysteine residues. In our patient, the presence of an extra cysteine residue could interefere with intra- and/or inter-molecular disulphide bond formation. The intermediate phenotype could perhaps result from the assembly of both normal and abnormal complexes, depending on the formation of the disulphide bonds.

Adult↗
PubMed1997

L-2-Hydroxyglutaric aciduria: clinical, biochemical and magnetic resonance imaging in six Portuguese pediatric patients.

We present clinical, biochemical and cranial magnetic resonance imaging data of six pediatric patients with L-2-hydroxyglutaric aciduria. All the children have the same ethic origin and lived in the northern area of Portugal. Our findings reinforce the described phenotype of this rare metabolic disease with mental deficiency, severe cerebellar dysfunction, mild extrapyramidal and pyramidal symptoms, progressive macrocephaly and seizures. Magnetic resonance imaging revealed subcortical leukoencephalopathy, cerebellar atrophy and signal changes in the putamina and dentate nuclei. These were similar to those of the previous reports in all patients. The urinary excretion of L-2-hydroxyglutaric acid was variably increased in all patients. The other persistent biochemical abnormality was hyperlysinemia. We have found a strong correlation between the severity of the clinical manifestations and the extension of the lesions in the neuroimaging studies. There was no correlation between the clinical findings and the amount of urinary excretion of L-2-hydroxyglutaric acid. We report the second case in the literature of a cerebral thalamic tumor in L-2-hydroxyglutaric aciduria; neuropathological examination of the surgical biopsy demonstrated a diffuse fibrillary astrocytoma.

Adolescent↗
PubMed1997

Transfontanelle ultrasonography in infants: comparative study with cranial computed tomography.

The findings of transfontanelle ultrasonography, undertaken in 36 infants with clinical evidence of central nervous system (CNS) disorders, were compared with the findings of cranial computed tomography (CT). Considering the CT scan findings as gold standard, cranial ultrasonography had a sensitivity of 82 per cent and a specificity of 75 per cent in identifying cerebral pathology. The positive predictive value was 92 per cent and negative predictive value was 45 per cent.

Brain Diseases↗
PubMed1994

Distinct T cell populations distinguish chronic myeloid leukaemia cells from lymphocytes in the same individual: a model for separating GVHD from GVL reactions.

Donor lymphocyte responses to minor histocompatibility antigen (mHA) differences are involved in allo-responses between HLA matched pairs causing GVHD and graft-versus-leukaemia (GVL). Since some mHA are tissue-restricted, GVHD and GVL responses may be separable. We studied donor lymphocyte responses to patients with CML in a series of 10 HLA-matched sibling and 10 unrelated donor-recipient pairs comparing proliferation to recipient PHA blasts and CML cells and attempting to selectively deplete responses to PHA blasts in vitro. Responses in counts per min (c.p.m) to CML cells and PHA blasts were, respectively, 2809 +/- 2205 (SD) and 7376 +/- 1877 in related and 12,107 +/- 7191 and 26,136 +/- 22,479 in unrelated pairs. Autologous responses to PHA blasts were significantly lower (mean 779 +/- 735) (p < 0.001). Results correlated with clinical outcome: higher responses to recipient cells correlated with transplant-related death (p = 0.02 for CML and p = 0.06 for PHA blasts). Higher responses to CML correlated with GVHD grade > or = II (p = 0.025). Donor lymphocytes exposed to recipient PHA blasts for 5 days and treated with a ricin-conjugated anti-CD25 antibody retained over 75% of their response to CML but < 10% to PHA blasts. Similarly, depletion of response to CML but not to PHA blasts occurred when CML was the primary challenge. These results indicate that distinct populations of donor T cells respond to recipient leukaemic and non-leukaemic cells, and provide the basis for a clinically applicable technique to selectively deplete donor GVHD reacting cells while conserving GVL.

Graft vs Host Disease↗
PubMed1993

The galea frontalis myofascial flap in anterior fossa CSF leaks.

We report the clinical use of galea frontalis myofascial flaps in the treatment of anterior fossa cerebrospinal fluid leaks after trauma. This flap provides an adequately sized and vascularised barrier between the cranial and nasal cavities through which the cells of the inflammatory response reach the target area. This technique was used in 9 cases with complete success; in 5 out of 9 patients, repair of an anterior cranial base bone defect was also performed with split calvarial bone grafts, harvested from the frontal craniotomy bone. In all patients, neither recurrence of the CSF leakage nor postoperative meningitis or its recurrence were observed.

Adult↗
PubMed1990

Molecular and morphological changes in the cat lateral geniculate nucleus and visual cortex induced by visual deprivation are revealed by monoclonal antibodies Cat-304 and Cat-301.

Monoclonal antibody Cat-301 recognizes a surface-associated proteoglycan on subsets of neurons in the mammalian CNS (Hockfield and McKay, 1983). The expression of Cat-301 immunoreactivity on Y cells in the cat LGN is sharply reduced by early visual deprivation (Sur et al., 1988). We employed an immunosuppression strategy (Hockfield, 1987) to further study alterations in the expression of experience-dependent molecules. Newborn BALB/c mice were injected with LGN from dark-reared cats to induce a suppression of the immune response to antigens expressed in visually deprived animals. These mice were then immunized with LGN from normal cats to elicit an immune response to antigens with an expression dependent on normal early visual experience. This strategy permitted the generation of monoclonal antibody Cat-304, which recognizes a surface-associated antigen on neuronal cell bodies and proximal dendrites, and which appears histologically identical to Cat-301. Further analyses show that Cat-304 and Cat-301 recognize different epitopes on the same 680-kDa chondroitin sulfate proteoglycan. We examined the effects of early visual deprivation on Cat-304 immunoreactivity in the LGN and visual cortex of cats. In LGN from normal cats, Cat-304 labels neurons in layers A, A1, and C, in interlaminar zones, and in the medial interlaminar nucleus. In LGN from dark-reared cats, the number of antibody-positive neurons is markedly reduced, and the cross-sectional area of the remaining positive neurons is smaller than normal. In cortical area 17 of normally reared cats, Cat 304-positive neurons are densely distributed in 2 bands, in layers IV and V/VI. Labeled neurons are also present in layers II and III. In area 17 of dark-reared cats, the number of antibody-positive neurons is reduced. The reduction in the number of labeled neurons is most pronounced in layers II/III and V/VI. Antibody-positive neurons are smaller in all cortical layers of dark-reared cats. The changes in the expression of Cat-301 immunoreactivity in dark-reared visual cortex and LGN are identical to those of Cat-304. The laminar differences in the effect of dark rearing on Cat-301 and Cat-304 expression in the visual cortex provides support for the suggestion that layer IV of cortical area 17 may be less susceptible to prolongation of plasticity by dark rearing than layers II/III and V/VI. Further, the biochemical and histological studies reported provide evidence that early visual experience regulates protein expression in the cat LGN and visual cortex.

Animals↗
PubMed1988

Giant axonal disease: report of three cases and review of the literature.

We describe three cases of Giant Axonal Neuropathy (GAN) with clinical signs of central nervous system involvement and an abnormal CT in one case. Two of these cases are sibs, pointing to an autosomal recessive inheritance as two other families previously reported. The review of the literature shows that most cases have central nervous system and cranial nerves involvement suggesting a generalized disorder in keeping an inborn error of organization of intermediate filaments. According to this, we think that Giant Axonal Disease (GAD) is a better designation to this condition.

Adolescent↗
PubMed1987

The value of CT-scanning in supratentorial haemangioblastomas.

The authors describe a case of supratentorial haemangioblastoma, presenting with epileptic fits, without association with polycythemia, or Von Hippel-Lindau syndrome, which, if present, would have given a clinical clue as to the nature of the lesion.

Brain Neoplasms↗
PubMed1986

The peripheral neuropathy in Machado-Joseph disease.

Peripheral nerve biopsies were taken from 11 patients with Machado-Joseph disease (MJD), a heredo-degenerative disease within the group of autosomal dominant ataxias. On the basis of the clinical symptoms, 2 patients were found to suffer from type I, 4 from type II and 5 from type III. All cases shared the same pathological features, which consisted of a reduction in density of myelinated and unmyelinated fibres and an increase in endoneurial collagen. It was also observed that some Schwann cells were not related to axons, whilst others showed numerous budding processes. The intensity of the changes varied considerably: it was mild in type I and II and severe in type III. Peripheral nerve changes in MJD are compared with those previously described in other forms of heredo-ataxias. It is concluded that involvement of peripheral nerves is a significant feature in this group of diseases and that peripheral nerve biopsy could be useful in the identification of the subtypes of MJD.

Adult↗
PubMed1986

Four cases of late onset metachromatic leucodystrophy in a family: clinical, biochemical and neuropathological studies.

Four cases of familial metachromatic leucodystrophy are described: the age of onset ranged from 15 to 21 years. Mental deterioration was the earliest clinical sign to be noted and all progressed to severe dementia. The arylsulphatase activity in peripheral leucocytes of the patients was very low, 5 to 15 nmol/h/mg protein, moderately reduced in the heterozygote, 40 nmol/h/mg protein, compared with control values of 60-160 nmol/h/mg protein. Sural nerve biopsies in two cases showed perivascular macrophages filled with metachromatic material and electron microscopy showed typical inclusions in Schwann cell cytoplasm. Necropsy in one of the cases revealed severe demyelination mainly in the cerebral hemispheres with metachromatic material in macrophages and neurons.

Adolescent↗
PubMed1982

The pathology of Machado-Joseph disease. Report of a possible homozygous case.

The clinical and pathological findings in a boy suffering from Machado-Joseph disease are described. The patient was the son of two affected parents and signs first appeared at the age of 8 years. A younger brother also became affected at the age of 7. The patient presented all the characteristic features of the disease which consist of progressive cerebellar ataxia, pyramidal signs, progressive external ophthalmoplegia with variable degrees of extrapyramidal and peripheral signs. He died at the age of 15, after an unusually short duration of the disease. Pathological examination showed degeneration and mild gliosis of the substantia nigra, dentate, pontine and cranial nerve nuclei, anterior horns and Clarke's columns. Additional findings, not previously described were the involvement of sensory ganglia, intermediolateral columns and gracile and cuneate nuclei. It is suggested that the present case is homozygous for the gene of Machado-Joseph disease. The pattern of distribution of the pathological lesions and the sparing of some anatomical structures confirm our view that Machado-Joseph disease should be considered a distinct clinico-pathological entity within the group of the autosomal dominant ataxias.

Adolescent↗
PubMed1982

A three-year follow-up study of infection with Trypanosoma cruzi and electrocardiographic abnormalities in a rural community in northeast Brazil.

The relationship between parasitemia, seroreactivity to Trypanosoma cruzi, and electrocardiographic abnormalities was studied in 115 individuals from a rural community in northeast Brazil where Chagas' disease is endemic. Vector control measures were introduced, and after 3 years 106 of the original participants were located and re-examined. Serum antibodies to T. cruzi were measured by complement fixation and indirect fluorescent antibody tests and parasitemia by xenodiagnosis and blood cultures. On both examinations more seropositive children than seropositive adults showed parasitemia, and parasitemia was more likely to persist over the 3-year period in younger individuals. Electrocardiographic (ECG) abnormalities were seen more frequently in seropositive individuals without parasitemia. However, ECG abnormalities, as expected, were more prevalent in older individuals and therefore no specific inverse relationship between ECG findings and parasitemia could be shown. The decreased prevalence of infection noted in younger individuals following the introduction of vector control measures indicates that this approach limited transmission.

Adolescent↗
PubMed1979

[Effects of parotidectomy on the blood sugar level and hepatic glycogen (author's transl].

This work was carried out in order to investigate the influence of parotid glands on the metabolism of carbohydrates in the rat. The animals were selected by age (10, 20, 30 and 40 days-old) and distributed in 3 experimental groups as follows: Group I -- Parotidectomized animals; Group II -- Sham-parotidectomized animals; and Group III -- Control animals. The animals from all the groups were sacrificed 20 days after the beginning of the experiment. From the discussion of the results it was observed that the parotidectomized animals at 20, 30 and 40 days have presented significantly larger glycaemic means than control animals. These control animals, by the other hand, have also presented significantly larger glycaemic means than sham-parotidectomized animals. Concerning the 10 days-old animals, the statistical analysis have not showed any significance among the three groups. The results obtained from hepatic glycogen dosages, in the same animals, have showed a coherence, because the animals that have presented larger glycaemic levels, have also presented less hepatic glycogen content; contrarily, the animals that have presented a less glycaemic levels, have also presented a larger amount of hepatic glycogen.

Age Factors↗