Search PubMed⌕ Search

Biomedical subjects

A Mauro

Publications and source records attributed to A Mauro.

At least 37 records · Page 2Linked to original sources
PubMed1994

Tumor cell proliferation and apoptosis in medulloblastoma.

The distribution of proliferating cell nuclear antigen (PCNA)-(clone PC 10)- and Ki-67-(clone MIB-1)-positive nuclei was investigated in 60 medulloblastomas of childhood. Although the labeling index of the two markers did not coincide, both showed a wide range of parallel variations. The percentage of positive nuclei was similar in both classic and desmoplastic tumors. A variable proliferation capacity was found in the different tumor structures. Areas with neuronal and glial differentiation showed very few positive nuclei; these were very abundant in the infiltration areas, and along penetrating vessels from subarachnoidal growths. Pale islands were negative or positive only in their peripheral part. Large-cell areas were richer in positive nuclei than classic ones, accounting for their more malignant character. Hyperchromatic round nuclei, not belonging to necrotic foci and called lymphocyte-like nuclei, differently interpreted in the past, were variably found in every case. They are known, from previous experience, to stain orange with Acridine Orange fluorochroming, like single-stranded DNA. They were not easily distinguishable from mitoses and were stained by in situ end-labeling of DNA strand breaks, as demonstrated by incorporation of labeled nucleotides. They were regarded as possible apoptotic nuclei, representing either a peculiar type of cell death or the preservation of the cell deletion capacity, typical of the embryonal tissue of origin.

Adolescent↗
PubMed1994

Carotid pain during percutaneous angioplasty (PTA). Pathophysiology and clinical features.

Stretching of the internal carotid artery during percutaneous transluminal angioplasty (PTA) may be associated with transient neck, facial or cranial pain. We report a series of 53 cases who received PTA. Cervical pain occurred in 51% of patients, with a radiation to face and scalp in 33%. Analysis focused on: (a) description of pain intensity, quality, timing and location; (b) investigation about the role of individual and technical parameters that could influence the relative risk of pain onset during PTA; (c) comparison with other available data on pain syndromes related to the carotid artery. Intimal flapping on post-angioplasty angiograms, bradycardia during the procedure and previous history of AMI were associated with a higher risk of painful angioplasty. PTA may also serve as a tool to investigate carotid pain and may add further knowledge to the evidence available about the role of the carotid wall in the pathogenesis of facial and cranial pain.

Aged↗
PubMed1992

Haemodynamic changes following carotid occlusion: MRI angiography and transcranial Doppler patterns.

To see the signal changes in MR angiography (MRA) when occlusions or severe stenoses of carotid arteries occur and to relate these data with the velocity values provided by transcranial Doppler sonography (TCD), 20 patients showing symptomatic or asymptomatic unilateral carotid obstructions underwent both MRA and TCD after digital angiography investigation. No MRA signal was recorded immediately downstream from the carotid occlusion. Low flow velocity values in the carotid siphon and middle cerebral artery (MCA) ipsilateral to the carotid obstruction were associated with altered MRA signals corresponding to the same vessels. Turbulence phenomena induced by reversed flow in the anterior cerebral artery induced MRA signal impairments. In carotid occlusions, there may be a relationship between the MRA patterns and the flow velocity variations detected by TCD, but the two approaches have to be applied together since they provide complementary information.

Blood Flow Velocity↗
PubMed1991

Coexpression of platelet-derived growth factor (PDGF) B chain and PDGF B-type receptor in human gliomas.

In this study we analyzed the expression of mRNA for PDGF-B and PDGF B-type receptor (PDGFrecB) in 42 biopsy specimens from human astrocytic gliomas and other brain tumors. All gliomas expressed PDGF-B mRNA at higher levels than found in peritumoral and normal nervous tissues. Levels of PDGF-B transcripts correlated strongly with those of mRNA for glial fibrillary acidic protein. Thus, the production of PDGF-B mRNA may be attributed mainly to tumoral glial cells. PDGFrecB transcripts were found in 24 out of 29 gliomas, in agreement with the hypothesis of an autocrine growth stimulation in these tumors. Moreover, mean levels of PDGFrecB expression were higher in glioblastomas than in astrocytomas and over 30-fold higher in meningiomas than in gliomas. This suggests that in gliomas PDGFrecB can be expressed also by vascular elements, in agreement with the hypothesized existence of a paracrine mechanism that may be responsible for the endothelial hyperplasias.

Astrocytoma↗
PubMed1991

Cerebellar syndrome in adult celiac disease with vitamin E deficiency.

We studied a woman with adult onset celiac disease complicated by a cerebellar syndrome that progressed despite the resolution of the malabsorption symptoms with a gluten free diet. The patient presented vitamin E deficiency and the cerebellar symptoms improved with vitamin E therapy. This case supports the possible role of this deficiency in the development of the neurological complications of celiac disease.

Adult↗
PubMed1990

Vascular response to irradiation in malignant gliomas.

The vascular response to irradiation was studied in peritumoral cortex and tumor areas in 9 autopsied cases of glioblastoma multiforme and in 10 biopsies of reoperated cases. The study was carried out by histological, immunohistochemical and electron microscope procedures. Hyaline thickening of the vessel walls with deformation and impoverishment of endothelial nuclei are the most striking features. Formation of large PAS-positive areas from the confluence of thickened vessel walls and development of a fibroblastic proliferation follow. Fibroblastic areas may entrap tumor glial cells. In PAS-positive areas a special population resembles myofibroblasts of tissue scars. Electron microscope reveals the production of collagen fibrils in and outside vessel walls. The presence of collagen III and IV is in line with the present interpretation of the mesodermic component.

Adult↗
PubMed1990

Epidural anesthesia as an adjunct to retroperitoneal aortic surgery.

Recent developments in vascular surgery suggest that the retroperitoneal approach to the aorta and the use of epidural anesthesia for lower limb revascularization are associated with decreased morbidity and shorter hospital stays. By combining these principles, we sought to determine if retroperitoneal aortic surgery could be performed under epidural anesthesia and if this might be advantageous. Over a 16-month period, 57 patients underwent aortic surgery via the retroperitoneal (n = 33) or transperitoneal (n = 24) approach. In the former, epidural anesthesia was employed in 10 patients, general anesthesia in 3, and combined epidural anesthesia and general anesthesia in the remaining 20. In the transperitoneal group, general anesthesia was employed in 21 patients and combined epidural anesthesia and general anesthesia in 3. Both groups were similar in age and gender, but risk factors were predominant in the retroperitoneal group. With the exception of one death due to aspiration, there were no significant differences between the transperitoneal and retroperitoneal groups with respect to overall morbidity, pulmonary complications, and length of stay in the intensive care unit and hospital. Despite these findings, we favor the combination of epidural and general anesthesia for retroperitoneal aortic surgery. Morbidity was significantly decreased (p less than 0.05) in low-risk retroperitoneal patients when combined epidural anesthesia and general anesthesia were employed.

Adult↗
PubMed1989

The vascular response to tumor infiltration in malignant gliomas. Morphometric and reconstruction study.

Neo-vascularization and endothelial hyperplasia have been shown to be very active in malignant gliomas. In this contribution the vascularization of the cortex infiltrated by malignant gliomas is morphometrically studied and the endothelial proliferations are immunohistochemically investigated and reconstructed by a three-dimensional computer-assisted procedure. Vessel density increases after tumor infiltration in some cases only. The diameter of vessels increases and so does the number of nuclei/vessel after the complete invasion of the cortex when vascular glomeruli develop. In completely infiltrated cortex with development of glomeruli and circumscribed necroses, vessel density is very low. No neoformation of vessels takes place before the complete infiltration of the cortex by the tumor. The hyperplastic formations, usually arranged parallel to the deep or outer cortical layers, take origin from the radially penetrating vessels from the meninges and their lateral branching. The hyperplasia deforms the vascular network, making it often inadequate to supply tumor cells. Immunohistochemically, the cells composing the hyperplastic structures are variably positive for factor VIII/RAg and, at a lesser extent, for alpha-smooth muscle actin. The poorness of the vascular network in many instances of completely infiltrated cortex is responsible for the development of circumscribed necroses.

Brain Neoplasms↗
PubMed1988

Reactive astrocytes in the morphologic composition of peripheral areas of gliomas.

The participation of reactive astrocytes in the morphologic composition of peripheral areas of 25 gliomas was investigated. Reactive astrocytes were studied by the immunohistochemical demonstration of glial fibrillary acidic protein and vimentin. Reactive astrocytes were more abundant around malignant gliomas than around well-differentiated astrocytomas. They underwent modifications when entrapped within the tumor proliferation and became indistinguishable from tumor astrocytes. Mitoses occurred in both types of cells. Reactive astrocytes did participate in the cell composition of gliomas. They might have contributed to tumor growth. Practically, their occurrence might lead to an erroneous diagnosis when small fragments of tissue are examined.

Astrocytes↗
PubMed1988

Membrane currents of rat satellite cells attached to intact skeletal muscle fibers.

Muscle satellite cells play an important role in the postnatal growth of skeletal muscle and in the regeneration of damaged muscle during adult life. Little is known about the physiological properties of satellite cells in their dormant state as they lie adjacent to the intact muscle fibers, underneath the basement membrane. Our recent experiments, using patch clamp techniques, indicate that no tight electrical coupling is present between satellite cells and the muscle fiber dissociated from rat flexor digitorum brevis. Satellite cells possess sodium channels with low sensitivity to tetrodotoxin and at a much lower density than muscle. In addition, satellite cells are insensitive to acetylcholine (ACh) for at least 24 hr after having been removed from the animal, even when detached from their muscle fiber. However, we could measure ACh-evoked currents from satellite cells 48-72 hr in culture, indicating that ACh sensitivity develops with time.

Acetylcholine↗
PubMed1988

Voltage gating of conductance in lipid bilayers induced by porin from outer membrane of Neisseria gonorrhoeae.

Porins, polypeptides of approximately 35 kDa, are present as integral membrane proteins in the outer membranes of a variety of Gram-negative bacteria. As reported previously for a purified porin from Escherichia coli, voltage gating of conductance was found to be induced in a lipid bilayer by the solubilized purified porin, protein I, from Neisseria gonorrhoeae. The unitary response to an applied potential showed a cascade of current from an initial level through at least three levels, more or less equal, to a persisting lower level. The initial level of current corresponded to 1.0-1.3 nS for 0.2 M NaCl on either side of the bilayer. Briefly reducing the potential to zero restored the current to its initial level. Interpretation of the unitary response is suggested by electron microscopic data obtained on negatively stained outer membranes of E. coli indicating the presence of "pores" appearing in triplets. Moreover, low-resolution x-ray and neutron diffraction studies on crystals obtained with an E. coli porin show that three polypeptides associate to form a unit. Combining such structural data with the present electrical data lends support for the hypothesis that the unitary response results from three pores acting as a unit in response to an applied potential. Evidence obtained with the patch-clamp technique is mounting for a similar mechanism of many channels operating as a unit in a variety of cell membranes. The porin channel holds promise as a concrete model for the analysis of voltage gating of ionic conductance.

Bacterial Outer Membrane Proteins↗
PubMed1986

Glial fibrillary acidic protein and vimentin in the experimental glial reaction of the rat brain.

Glial reaction has been studied in the rat by the immunohistochemical demonstration of glial fibrillary acidic protein (GFAP) and vimentin (VIM) in two experimental conditions. The first was represented by a necrotic cerebral lesion obtained by laser irradiation and the second by the development of experimental tumors induced by transplacental ethylnitrosourea. Reactive astrocytes develop not only in the proximity of the lesion but also distant from it. The intensity of the glial response seems to depend upon the normal distribution of astrocytes and the perilesional edema. GFAP decorates all the reactive astrocytes, whereas VIM is positive only in those at the edges of the lesion. The significance of the different responses in the two models and between the two intermediate filaments is discussed.

Animals↗
PubMed1986

Anaplasia and heterogeneity of GFAP expression in gliomas.

GFAP (glial fibrillary acidic protein) distribution was investigated in selected areas of glioblastomas and astrocytomas. The proliferating cell population of glioblastomas was GFAP negative and contained many mitoses which were also negative. The old, deeply located areas were composed of cells with visible cytoplasm, intensely GFAP-positive; mitoses in these areas were both GFAP-positive and negative. GFAP-positive reactive astrocytes, once trapped in the tumor, were no longer distinguishable from positive tumor cells. They sometimes contained mitoses. In astrocytoma, anaplasia was due to the development of a GFAP-negative population with negative mitoses. The problem of dedifferentiation and differentiation of malignant gliomas in discussed taking into account the possibility that malignancy may be due to increasing mutation rates of tumors. The problem of redifferentiation of already dedifferentiated cells is also discussed.

Anaplasia↗
PubMed1986

Simultaneous and successive localization of two antigens in the same tissue section using 3,3'-diaminobenzidine and 1-naphthol basic dye.

We describe two procedures for the simultaneous and successive localization of two antigens in the same tissue section. In the simultaneous staining procedure, the first antigen was localized using 3,3'-diaminobenzidine (DAB), while the second antigen was stained using the 1-naphthol basic dye (1-NBD) method. The colour of the second antigen depended on the basic dye used, and no mixing of colours was observed when the two antigens were localized in different cells or structures. However, sequential double staining proved to be more convenient for the demonstration of two antigens in the same cell. In this procedure, the first antigen was stained using 1-NBD, and the interesting microscopic fields were photographed. The basic dye was then completely removed, and the second antigen was stained using DAB.

3,3'-Diaminobenzidine↗
PubMed1986

Immunohistochemical demonstration of vimentin in human cerebral tumors.

The distribution of vimentin (VIM) has been histochemically investigated in 53 cerebral tumors and compared in gliomas to that of glial fibrillary acidic protein (GFAP). In gliomas VIM is less positive than GFAP, but shows the same distribution. It cannot be considered as indicating immaturity of glial tumor cells. VIM is also positive in glial processes of cerebellar pilocytic astrocytomas, in Schwann cells of neurinomas and in endothelial cells of all oncotypes. In medulloblastomas, VIM decorates reactive glia cells. A diffuse positive reaction has been observed in meningiomas. In hemangioblastomas, besides intervascular and endothelial cells, groups of polygonal cells are intensely positive for both VIM and GFAP. The interpretation of VIM in cerebral tumors is largely based on the distribution patterns of this intermediate filament in the developing CNS of rodents.

Astrocytoma↗
PubMed1986

Immunohistochemistry in neuro-oncology.

The technical modalities of the immunohistochemical demonstration of antigens of neuroectodermal differentiation and of mesenchymal nature in neural tissue are discussed. On the main antigens (S-100 protein, GFAP, Vimentin, Neuronal specific Enolase, neurofilaments, myelin basic protein, carboanhydrase C, FVIII/RAg, laminin, fibronectin) the most important findings are described and critically considered. They are interpreted in the light of the present knowledge on the problems of differentiation of the oncotypes and on particular aspects of bio-pathology of brain tumors.

Astrocytes↗
PubMed1985

1-Naphthol basic dye (1-NBD). An alternative to diaminobenzidine (DAB) in immunoperoxidase techniques.

The usefulness of 1-naphthol as substrate for horseradish peroxidase (HRP) in immunohistochemistry was studied using the peroxidase-antiperoxidase (PAP) and avidin-biotin-complex (ABC) methods in the demonstration of glial fibrillary acidic protein (GFAP), vimentin, carbonic anhydrase C (CA.C), and factor VIII-related antigen (FVIII/RAg) in central nervous tissue and cerebral tumors. In the presence of ammonium carbonate, 1-naphthol is oxidized by HRP and hydrogen peroxide, producing a fine gray-violet precipitate. The oxidation product of 1-naphthol proved capable of binding a great number of basic dyes. For each stain the final reaction product had a characteristic color that was different from the spontaneous color of the dye and from the color displayed by nuclei. The final color obtained with this procedure was alcohol resistant and could be mounted in solvent-based mounting media. The results obtained with the 1-naphthol basic dye (1-NBD) method were compared with those obtained using the diaminobenzidine (DAB) reaction in the demonstration of GFAP-positive astrocytes. The DAB reaction produced a more intense staining but also a coarser precipitate than the 1-NBD reaction. The 1-NBD procedure showed more morphological detail of fine structures and did not obscure nuclei and mitosis. The very low toxicity of 1-naphthol compared with DAB (a suspected carcinogen) is an important advantage of the 1-NBD method, as is its high specificity and sensitivity.

3,3'-Diaminobenzidine↗