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Biomedical subjects

A Mauro

Publications and source records attributed to A Mauro.

At least 55 records · Page 3Linked to original sources
PubMed1985

The distribution of laminin in human brain tumors: an immunohistochemical study.

The immunohistochemical distribution of laminin in 70 cases of primary and secondary brain tumors has been studied. The sections were fixed in Carnoy, embedded in paraffin, and treated with collagenase before applying the specific immune serum. In normal neural tissue and in gliomas, the distribution of laminin overlaps with that of basement membrane, as is known from observations on ultrastructure in the literature. The overlapping was observed also in neurinomas, papillomas of the choroid plexus, ependymomas, and meningiomas. Problems arise in the interpretation of the results in the other oncotypes. In hemangiopericytomas and hemangioblastomas, laminin demonstrates a basement membrane around the vessels only; it is absent around stromal cells. In desmoplastic medulloblastomas, laminin forms a network among the tumor cells. In primary lymphomas, concentric rings of laminin are evidenced around some vessels. In discussing the results, the ultrastructural distribution of basement membranes is taken into account.

Basement Membrane↗
PubMed1984

[Leptomeningeal carcinomatous metastases].

The metastatic involvement of leptomeninges is an uncommon complication of systemic cancer, but there are evidences that its incidence is increasing, particularly for breast cancer. The two commonest primary sites are the breast and the lung and adenocarcinoma is the most frequent histologic type of carcinoma to metastasize to the leptomeninges. Clinical diagnosis is suggested by the simultaneous occurrence of symptoms and signs in more than one areas of CNS. Examination of cerebrospinal fluid is the most helpful diagnostic procedure. A combination of radiotherapy and intrathecal or intraventricular administration of Methotrexate seems to be the most successful treatment.

Adenocarcinoma↗
PubMed1984

Collagenase in the immunohistochemical demonstration of laminin, fibronectin and factor VIII/RAg in nervous tissue after fixation.

The effects of collagenase on the immunohistochemical demonstrability of laminin, fibronectin and Factor VIII/RAg in human nervous tissue have been studied. The influence of this, and other proteolytic enzymes such as pepsin and trypsin, has been investigated in relation to different fixatives. Collagenase gave better results with Carnoy fixed material than after formalin fixation; unlike trypsin and pepsin, it did not produce tissue digestion.

Antigens↗
PubMed1984

GFAP, F VIII/RAg, laminin, and fibronectin in gliosarcomas: an immunohistochemical study.

GFAP, Factor VIII/RAg, laminin, and fibronectin were immunohistochemically investigated in 15 glioblastomas and 15 gliosarcomas . GFAP was found variably positive in the glial areas. F VIII/RAg characterizes the endothelial cells and in gliosarcomas suggests the origin of the sarcomatous component from the endothelial proliferations. Laminin separates the two components and characterizes the inner and the outer basement membranes in the vessels. It is multiplied and thickened in endothelial proliferations, while it is often fragmented in the larger vessel wall proliferations. Our observations confirm that gliosarcoma represents the last stage of a process which starts with the endothelial hyperplasia of glioblastoma.

Antigens↗
PubMed1983

Glial fibrillary acidic protein (GFAP) in human cerebral tumors. An immunohistochemical study.

Glial fibrillary acidic protein (GFAP) was studied in 160 cerebral tumors, mostly of neuro-epithelial nature. It was positive in astroglial tumors with an intensity proportional to the degree of cell differentiation. It was sometimes positive also in non-astroglial tumors, such as oligodendrogliomas and ependymomas, and this finding is discussed in relation to genesis and diagnostic value. In medulloblastomas, there were also positive cells, which could be reactive glia cells included in the tumors or subependymal cells. The demonstration of GFAP is very useful in gliosarcomas for identifying the glial component. It was sometimes positive in hemangioblastomas, and it is discussed in view of the nature of the stromal cells of this tumor.

Brain Neoplasms↗
PubMed1983

Biochemical and histochemical evaluation of glycosaminoglycans in brain tumors induced in rats by nitrosourea derivatives.

The occurrence, distribution and concentration of GAGs in ENU and MNU experimental brain tumors induced in the rat are reported. GAGs have been histochemically studied by Alcian Blue methods; they have been quantified and qualitatively evaluated by electrophoresis of brain extracts. The pattern of GAGs in normal rats is consistent with the data of the literature. No GAG accumulation precedes the tumor development. Early neoplastic proliferations, oligodendroglial and mixed glial microtumors are strongly alcian-positive; the alcianophilia spares clusters of cells developing a cytoplasm. In large tumors, GAGs are histochemically demonstrable in the honey-comb areas of oligodendrogliomas and in peripheral infiltration areas of polymorphic gliomas. The role of the normal nervous tissue and oligodendroglial cells in the accumulation of the GAGs is discussed. The accumulated GAGs seem to rise from the nervous tissue included in the tumors, rather than from the metabolism of tumor cells.

Age Factors↗
PubMed1983

Contributions of immunohistochemistry to the problem of differentiation in medulloblastoma.

The problem of differentiation of medulloblastoma is considered. In this regard 43 medulloblastomas, showing cells with glial or neuronal features by routine histologic methods, were studied. The investigation was carried out by means of the immunohistochemical demonstration of the glial fibrillary acidic protein (GFAP) and the neuron-specific enolase (NSE). In most cases, GFAP-positive cells are preexisting astrocytes; in two cases they correspond to the transitional cells of the subependymal layer. NSE was demonstrated in areas filled with cells with neuroblastic features. The relationship between medulloblastoma with neuron-differentiation and cerebellar neuroblastoma is discussed.

Astrocytes↗
PubMed1983

Properties of the major outer membrane protein from Neisseria gonorrhoeae incorporated into model lipid membranes.

The major outer membrane protein from Neisseria gonorrhoeae was incorporated into artificial planar bilayer membranes by a detergent-dilution procedure. The integrated protein forms voltage-dependent aqueous pores with a minimal pore diameter estimated to be 11 A. A pore of this size suggests a role for this protein in macromolecular sieving at the level of the outer membrane. This protein self-associates preferentially in triplets of three equal unit conductance steps of 130 pS (in 0.1 M NaCl) each. The two-state model may be applied to explain the voltage-dependent conductance. The average lifetime of the open state of single channels is strongly dependent on the applied voltage, the channels shifting to the closed state at higher voltages. The pore is anion selective, differing from porins of other Gram-negative bacteria studied so far but resembling the voltage-dependent anion-selective channel of the outer membrane of mitochondria.

Bacterial Proteins↗
PubMed1982

The ionic dependence of black widow spider venom action at the stretch receptor neuron and neuromuscular junction of crustaceans.

The effects of black widow spider venom (BWSV) on the crayfish stretch receptor and the lobster neuromuscular junction were examined. In crayfish stretch receptor neurons, BWSV caused a slight hyperpolarization followed by a large depolarization. The venom-induced depolarization of the stretch receptor was caused by an increase in membrane conductance to Na+ and Ca2+. Black widow spider venom also caused an increase in the frequency of miniature inhibitory postsynaptic potentials recorded in the stretch receptor. The ability of BWSV to increase the frequency of miniature excitatory postsynaptic potentials (MEPSPs) at the lobster neuromuscular junction was dependent on the divalent cation composition of the bathing medium. Ringer solutions containing Ca2+ supported the greatest venom-induced increase in MEPSP frequency, Mg2+ and Mn2+ supported a moderate increase in MEPSP frequency, while Co2+ and Zn2+ blocked this venom effect entirely. Black widow spider venom did not block axonal conduction in lobster walking leg axons or in the axon of the crayfish stretch receptor. The results suggest that in crustaceans, BWSV interacts specifically with membrane of the soma-dendritic region of the stretch receptor and with nerve terminal membrane, causing an increase in Na+ and Ca2+ conductance.

Animals↗
PubMed1982

Glycosaminoglycans in human cerebral tumors. Part II. Histochemical findings and correlations.

The occurrence and the distribution of GAGs have been studied histochemically in 224 human cerebral tumors by means of Alcian blue techniques. In the normal peritumoral gray matter the alcianophilia is stronger than in the white matter and demonstrated the presence of HA and CS. In the glioma group the alcianophilia, due to HA and CS, is mainly related to the presence of infiltrated cortex. In the other tumors, GAGs are histochemically disclosed in relation to collagen, reticulin, mesodermic areas, etc. The vessels of every tumor show a positive staining for HA, CS and HS. The histochemical findings are consistent with the biochemical ones as reported in Part I, even though the significance of GAGs in cerebral tumors remains unknown.

Astrocytoma↗
PubMed1981

Glycosaminoglycans of brain tumors transplacentally induced by ENU in the rat.

GAGs accumulate in the oligodendrogliomas and in the oligodendroglial component of mixed gliomas induced in rats by transplacental ENU. We studied the period between birth and the appearance of the earliest tumoral lesions and did not find any accumulation preceding the early neoplastic proliferations. These findings, together with the observation that GAGs are present only in the oligodendroglial component of tumors, are in agreement with our previous interpretation that the tumoral transformation of oligodendroglia takes place after it has acquired the ability to interfere with GAG metabolism during myelinogenesis.

Animals↗
PubMed1981

High speed autoradiography on brain tissue sections.

The application of high-speed autoradiography to histologic brain sections of in vivo [3H] thymidine labeled rats is reported. Low doses of isotope have been used. With Kodak NTB3 emulsion, specific nuclear labelling of the subependymal layer was reached after 48 h of exposure. With llford K2 emulsion, the maximal nuclear labelling was achieved within 20 days. The fitness of this technique for studying the nervous tissue kinetics is discussed.

Animals↗
PubMed1980

Experimental brain tumors by transplacental ENU. Multifactorial study of the latency period.

Experimental cerebral tumors have been induced by transplacental ENU. The morphologic study of the brains of treated rats revealed that cellular hyperplasias appear at the 30th day of extrauterine life in the paraventricular white matter, i.e., before the already known "early neoplastic proliferations". Cytofluorimetric investigations failed to demonstrate differences between treated and control rats during the 1st month. On the contrary, adenylate cyclase activity is very high in that period. The duration of the latency period is discussed.

Adenylyl Cyclases↗