PubMed Health⌕ Search

Biomedical subjects

M Fraga

Publications and source records attributed to M Fraga.

46 records · Page 3Linked to original sources
PubMed1991

[Alagille's syndrome: a family case and its association with hepatocellular carcinoma].

Two cases of Alagille syndrome are reported, father and son. This, a 6-year-old boy, presented with neonatal cholestasis but thereafter evolved with progressively decreasing jaundice and persisting pruritus. A liver biopsy confirmed the absence of intrahepatic bile ducts with preservation of hepatic architecture and no fibrosis. The patient had a characteristic phenotype: short stature, triangular face, deep eyes with hypertelorism, partial embryotoxon and data of peripheral pulmonary artery stenosis. His father died 43-year-old by a hepatocarcinoma. His liver biopsy showed also absence of intrahepatic bile ducts. In addition to the association Alagille's syndrome hepatocarcinoma (previously reported in six cases, three into the same family), it should be stressed in this case the long survival and the fact he had many children: the case with Alagille's syndrome, five children in good health, and one who died shortly after birth.

Abnormalities, Multiple↗
PubMed1991

Immunohistochemical demonstration of neuronal and astrocytic markers and oncofoetal antigens in retinoblastomas.

General opinion is that retinoblastomas, though not everyone agrees with that view. Some authors suggest that retinoblastomas are derived from a primitive retinal cell able to differentiate into both neuronal and glial cell lines. The aim of the present work was to study immunohistochemically the expression of neuronal and astrocytic markers in retinoblastomas and at the same time the presence of the oncofoetal antigens carcinoembryonic antigen (CEA) and alpha Foeto Protein (AFP), since patients with retinoblastomas often show high oncofoetal antigen in serum levels. For this purpose we employed the streptavidin-biotin immunoperoxidase technique in 13 cases of retinoblastoma to evaluate the presence and distribution of neuron-specific enolase (NSE), neurofilament protein (NF), glial fibrillary acidic protein (GFAP), S-100 protein, CEA and AFP. All 13 tumours studied stained for NSE. Seven of them showed GFAP- and S-100 positive perivascular glial cells as well as cells distributed randomly in the tumour that were interpreted as non tumour cells. All 13 retinoblastomas lacked detectable NF, CEA, and AFP. These results support the idea that retinoblastomas are neuronal tumours, although retinal glial cells may become incorporated in the tumour and proliferate in response to the tumour.

Antigens, Neoplasm↗
PubMed1989

An analysis of the relationship between the cellular distribution and the rate of turnover for the separate classes of unoccupied, noncovalently occupied, and covalently occupied insulin receptor.

To further investigate insulin's role in regulating the turnover of insulin receptor during down-regulation in 3T3-L1 adipocytes, the relationship between the cellular distribution and turnover of unoccupied, noncovalently occupied, and covalently occupied receptor was examined. At steady-state 12% of the unoccupied receptors and 46% of covalently occupied receptors are intracellular. The apparent first-order rate constant (Kapp) for turnover of the total pool of covalently occupied receptors (0.16 h-1) is 3.8-fold higher than that for unoccupied receptors (0.042 h-1). When unlabeled insulin is added, identical values for both Kapp (0.10 h-1) and distribution (26% internal) are measured for noncovalently and covalently occupied receptors. The rate constant (Kdeg), describing the relative sensitivity of internalized receptor to degradation, is identical (0.36-0.41 h-1) for unoccupied, noncovalently occupied, and permanently occupied pools of internal receptor. Mechanisms for down-regulation postulating: (a) an occupancy-dependent alteration in the conformation of internal receptor increasing receptor sensitivity to internal proteases, (b) a preferential sorting of internal occupied receptor to degradative pathways, or (c) induction of intracellular proteases by insulin, would all reflect a substantial change in Kdeg for occupied receptor and thus are unlikely mechanisms by which insulin increases the rate of receptor turnover. The turnover of insulin receptor in 3T3-L1 adipocytes is regulated primarily by its intracellular concentration and not by the state of occupancy of internalized receptor.

Adipose Tissue↗
PubMed1989

Calcitonin gene-related peptide (CGRP) immunoreactivity in the neuroendocrine Merkel cells and nerve fibres of pig and human skin.

The presence of calcitonin gene-related peptide (CGRP) in the skin of pig snout and human fingertip was investigated using immunohistochemical techniques. CGRP immunoreactivity was found in Merkel cells and nerve fibres of both species. In pig snout skin, Merkel cells containing CGRP were seen forming clusters at the tips of rete ridge epidermis and in the external root sheath of sinus hair follicles (vibrissae). Human Merkel cells immunostained for CGRP were found isolated or forming small groups in the basal layer of glandular epidermal ridges. In all cases, immunoreactivity was more intense on the side of the Merkel cell facing the associated nerve terminal (which was never positive for CGRP). This part of the Merkel cell has the greatest density of dense-cored granules, suggesting that CGRP must be stored in these granules. Nerve bundles containing CGRP-immunoreactive fibres were found at dermal and hypodermal level, and blood vessels were often surrounded by CGRP nerve fibres. In pig snout skin some nerve fibres containing CGRP penetrated the epidermis and terminated as free endings, and in the human fingertip a small number of CGRP-immunoreactive nerve fibres were seen in Meissner's corpuscles.

Animals↗
PubMed1983

Changes in purine nucleoside phosphorylase activity during thymosin-induced human null cell differentiation.

Purine nucleoside phosphorylase (PNP) is a purine salvage pathway enzyme which we have found to be 8-10 times more active (per cell) in human peripheral blood null lymphocytes than in T lymphocytes. To test the hypothesis that null cells are, in part, pre-T lymphocytes we have defined an in vitro system for null cell differentiation into T cells and examined PNP activity during this differentiation process. We found that about 10% of human null cells could be driven to differentiate into T cells using thymosin fraction 5 (TF5) an extract of bovine thymus glands. The response to TF5 was dose related to up to 250 micrograms/ml with a maximum response occurring by 42-46 hr incubation. Exposure to TF5 was necessary for more than 4 hr but no more than 8 hr in order to obtain a maximum response. Both OKT4 and OKT8 positive cells were present in the newly differentiated T cell population but OKT8 positive cells appeared to predominate (OKT4/OKT8 = 0.698 +/- 0.30, mean +/- 1 SD). The differentiation process did not involve DNA synthesis but was inhibited at 4 degrees C. In the newly differentiated T cells PNP activity per cell was 8- to 10-fold lower (36 +/- 23 nm/hr/106 cells) than in null cells (311 +/- 136), and was at a level similar to mature T cells (56 +/- 7). Thus, human peripheral blood null cells can be induced to differentiate into T lymphocytes which can be characterized by both surface markers and biochemical parameters. Future studies will look at the function of TF5-induced T cells and the regulation of PNP activity during the differentiation process.

Adult↗
PubMedDate not supplied

Presentation of T-cell-rich B-cell lymphoma mimicking acute hepatitis.

Liver involvement in non-Hodgkin's lymphoma is relatively frequent, being found in approximately half of the post-mortem studies. However, the clinical presentation of lymphoma mimicking primary liver disease is uncommon. A case of non-Hodgkin's lymphoma (the recently described T-cell-rich B-cell lymphoma variant) is presented, where the initial and predominant manifestations were of hepatic origin, resembling non-neoplastic acute liver disease.

Adult↗
PubMedDate not supplied

Prolonged survival after liver transplantation for Hodgkin's disease-induced fulminant liver failure.

A 30-year-old male with a past history of nodular lymphocyte predominance Hodgkin's disease in apparent complete remission for two years received a liver transplantation because of fulminant liver failure. Histopathological examination of the explanted liver showed massive infiltration by Hodgkin's disease. In spite of a nodal recurrence of Hodgkin's disease, the patient is alive and in excellent general condition six years after liver transplantation.

Adult↗