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Biomedical subjects

M Melis

Publications and source records attributed to M Melis.

At least 91 records · Page 5Linked to original sources
PubMed1990

[Winging effect in interatrial defect after transseptal mitral valvuloplasty: an anatomical study].

In the balloon catheters the redundancy of the deflated balloon produces 2 or 3 sort of thin wings. The presence of wings can reduce the catheter "pushability" or, in certain conditions, can determine tissue lesion (winging effect). Simulating a transeptal valvuloplasty of the mitral valve by technique of the 2 balloon in human fresh heart, we studied the winging effect over the interatrial septum in 12 hearts; in the first 6 the atrial septum was dilated with a 6 mm balloon (Group A), in the second 6 the atrial septum was dilated with a 10 mm balloon (Group B). The procedure was completed introducing consecutively 2 bigger balloons (15 + 20 mm). We suppose that the winging effect of the 2 bigger balloons (15 + 20 mm) could counter balance the theoretical advantage of a small balloon (6 mm). The atrial septal defect (ASD) after septal dilatation was 5.0 +/- 0.59 mm x 1.56 +/- 0.25 mm (long axis x short axis) in Group A and 6.53 +/- 0.35 x 2.16 +/- 0.39 mm in Group B (p less than 0.01). The final ASD (after introducing the 2 bigger balloons) was 7.04 +/- 1.06 x 2.36 +/- 0.57 mm in Group A and 7.03 +/- 0.18 x 2.16 +/- 0.32 mm in Group B (NS). Our data show that the winging effect can determine biological negative effects.

Catheterization↗
PubMed1989

Lung compartmentalization of increased TNF releasing ability by mononuclear phagocytes in pulmonary sarcoidosis.

The TNF is a monokine with cytotoxic and tumor-necrosing activities; in addition, TNF may play a role in inflammatory processes. The present study evaluates spontaneous and LPS-mediated release of TNF by AMs and autologous peripheral BMs of normal subjects and patients with pulmonary sarcoidosis. A recently developed cytotoxicity assay, specific for detection of TNF activity, was applied. This study demonstrates that (1) unstimulated mononuclear phagocytes released low levels of TNF with no differences between groups; (2) when effector cells were stimulated with LPS, AMs from patients with active pulmonary sarcoidosis released more TNF than AMs recovered from normal subjects and from patients with inactive disease; (3) this increase was compartmentalized to the lungs, since comparisons of TNF production by LPS-stimulated BMs failed to show any difference between study groups. These results suggest that TNF might play a role in the pathogenesis of the alveolitis of pulmonary sarcoidosis.

Adult↗
PubMed1989

Epidemiologic and clinical features of the Guillain-Barre' syndrome in Sardinia in the 1961-1980 period.

Epidemiologic and clinical features of the Guillain-Barrè syndrome in Sardinia, in a twenty years period, were studied. 120 subjects (62 males and 58 females) with Guillain-Barrè syndrome were identified. An annual incidence rate of 0.4/100,000 population was found. The results were compared both with national and international data of the literature. The peculiarity of some aspects was pointed out.

Adolescent↗
PubMed1988

Tumor necrosis factor release by pulmonary alveolar macrophages.

Tumor necrosis factor (TNF) is a monokine with cytotoxic and tumor-necrosing activities that may play a role in host defence against malignancies. The aim of the present study was to assess the ability of pulmonary alveolar macrophages (AMs) to release TNF. To accomplish this, a cytotoxicity assay specific for TNF detection was applied, using as targets actinomycin-D-pretreated WEHI 164 murine sarcoma cells. AMs mediated cytotoxicity levels comparable to those mediated by autologous blood monocytes (BMs). In addition, cytotoxicity was accounted for by a soluble factor released by effector cells and was completely inhibited by the addition of anti-TNF antibodies. These results indicate that AMs are able to release TNF. Moreover, since TNF has now been recognized as an important mediator of inflammation, its production by AMs suggests that this monokine might play a role in the pathogenesis of a variety of nonmalignant lung disorders.

Adult↗
PubMed1988

Structural and ultrastructural modifications following transurethral injection of teflon paste.

Structural and ultrastructural tissue modifications caused by polytetrafluoroethylene (teflon) paste injection in incontinent male patients have been studied. The most considerable observations are: a diffuse interstitial splitting of teflon paste in particles of about 3-100 microns. Given that the tissue reaction is limited to a modest infiltration of lymphocytes and monocytes and a slight increase in the collagen fibres, it is concluded that the teflon paste injection is well tolerated by the tissues.

Humans↗
PubMed1988

Pretreatment scalene node biopsy in cervical carcinoma.

To evaluate incidence of scalene node metastases from carcinoma of the cervix, 20 patients had scalene fat-pad node biopsy. All cases were staged according to FIGO criteria and abdominal lymph nodes were studied by CT and lymphangiography. Scalene node metastases were found in 2 patients with clinically suspicious node and pelvic and paraaortic nodes involvement. Seven patients had sinus histiocytosis in scalene node biopsy and this seems related to a more favourable prognosis. From this study it appears that scalene node biopsy is not a routine procedure and should be performed in all patients with palpable supraclavicular masses or when paraortic nodes are involved.

Biopsy↗
PubMed1987

A chromosome 11-linked determinant controls fetal globin expression and the fetal-to-adult globin switch.

Hybrids formed by fusing mouse erythroleukemia (MEL) cells with human fetal erythroid cells produce human fetal globin, but they switch to adult globin production as culture time advances. To obtain information on the chromosomal assignment of the elements that control gamma-to-beta switching, we analyzed the chromosomal composition of hybrids producing exclusively or predominantly human fetal globin and hybrids producing only adult human globin. No human chromosome was consistently present in hybrids expressing fetal globin and consistently absent in hybrids expressing adult globin. Subcloning experiments demonstrated identical chromosomal compositions in subclones displaying the fetal globin program and those that had switched to expression of the adult globin program. These data indicate that retention of only one human chromosome-i.e., chromosome 11--sufficient for expression of human fetal globin and the subsequent gamma-to-beta switch. The results suggest that the gamma-to-beta switch is controlled either cis to the beta-globin locus or by a trans-acting mechanism, the genes of which reside on human chromosome 11.

Animals↗
PubMed1986

The influence of dexamethasone treatment on the lymphoid and stromal composition of the mouse thymus: a flowcytometric and immunohistological analysis.

The effect of injection of a range of doses of dexamethasone on the distribution of T-cell subpopulations and stromal cells in the thymus of BALB/c mice was investigated with flowcytometry and immunohistology. To this purpose we used monoclonal antibodies directed to the T-cell differentiation antigens Thy-1, T200, Lyt-1, Lyt-2, T4, MEL-14, and monoclonal antibodies directed to various classes of stromal cells. Injection of dexamethasone in increasing doses of 5-130 mg/kg body weight gradually leads to a depletion of the cortical thymocyte population, i.e., bright Thy-1 + ve, dull T-200 + ve, bright Lyt-2 + ve, and bright T4 + ve cells. These cortical cells are very dull MEL-14 + and express variable numbers of Lyt-1 molecules. Also the medulla is affected by dexamethasone although to a lesser extent. Dexamethasone injection at 130 mg/kg selects for a dull Thy-1 + ve, bright T-200 + ve, and bright Lyt-1 + ve medullary population. These cells are either T4 + ve Lyt-2-ve or T4-ve Lyt-2 + ve. Under these conditions, MEL-14 + ve cells were no longer present in the cortex but accumulated in medullary perivascular spaces. Staining of sequential sections showed that this particular subpopulation has a typical "helper" phenotype. This observation provides strong evidence that perivascular compartments are an exit pathway for emigrating T cells. The medullary population contains a phenotypically distinct, dexamethasone-sensitive subpopulation. This conclusion is based on two findings: 130 mg/kg dexamethasone depletes the thymus of all but 4% of the thymocytes, which form a much smaller subpopulation than the population of dull Thy-1 + ve cells (amounting to 15% of the total thymocytes). The medulla contains a subpopulation of dull Lyt-2 + ve cells, which are resistant to 20 mg/kg dexamethasone, but depleted by 130 mg/kg. Dexamethasone also has a severe effect on thymic nonlymphoid cells. Even at low doses, dexamethasone induces TR4 + ve cortical epithelial-reticular cells to become spherical ("nurse cell-like") structures, depleted of lymphoid cells. These stromal cells no longer express MHC antigens in a membrane-bound fashion. In contrast, the medullary epithelial cells appear morphologically unaffected even at a dexamethasone dose of 130 mg/kg.

Animals↗
PubMed1986

Reticular fibroblasts in peripheral lymphoid organs identified by a monoclonal antibody.

We have produced a panel of monoclonal antibodies directed against nonlymphoid cells in central and peripheral lymphoid organs. In this paper we present the reactivity of one of these antibodies, ER-TR7. This antibody detects reticular fibroblasts, which constitute the cellular framework of lymphoid and nonlymphoid organs and their products. In frozen sections of the spleen incubated with this antibody, the red pulp and white pulp are clearly delineated. Furthermore, the major white pulp compartments--the follicles and periarteriolar lymphoid sheath as well as the marginal zone--are recognized by their characteristic labeling patterns. In lymph nodes, the capsule, sinuses, follicles, paracortex, and medullary cords are clearly delineated. In the thymus and bone marrow no such specialized compartments were demonstrated. ER-TR7 reacts with an intracellular component of fibroblasts. Since ER-TR7 does not react with purified laminin, collagen types I-V, fibronectin, heparan sulfate proteoglycan, entactin, or nidogen, it detects a hitherto uncharacterized antigen. The possible role of the ER-TR7 positive reticular fibroblasts in the cellular organization of peripheral lymphoid organs will be discussed.

Animals↗
PubMed1986

Effects of peripheral duct occlusion on exocrine and endocrine pancreas. A histological, immunocytochemical and electron-microscopic study in the pig.

The effects of central and peripheral duct occlusion on the pancreas of the pig were investigated. The occlusion was obtained by injecting into the distal part of the pancreatic duct an ether diluted delicron or a fluid silicone solution. The pancreatic duct was then interrupted. At different intervals, gross morphology of the residual pancreas was studied and specimens were obtained for histology, immunocytochemistry and electronmicroscopy. A rapid progression of sclerotic modifications, with gradual destruction of exocrine gland, substantially concluded after 60 days, was demonstrated. However Langerhans' islets appeared preserved. These findings permit to suggest the application of this valid experimental model of chronic pancreatitis to the conservative treatment of human chronic pancreatitis.

Animals↗
PubMed1985

Adult and fetal human globin genes are expressed following chromosomal transfer into MEL cells.

Somatic cell hybridization of mouse erythroleukemia (MEL) cells and HEL cells, a human erythroleukemia line that produces fetal (gamma) but fails to express adult (beta) globin, was used to test whether the expression of the two human globin genes is regulated cis or trans. An experimental approach using anti-human globin monoclonal antibodies for detection, efficient cloning, and monitoring of hybrids of interest was employed. Further characterization of hybrids used isoelectric focusing for detection of human globins and S1 nuclease mapping. In contrast to the parental HEL line, all chromosome 11-retaining HEL-MEL hybrids expressed human beta-globin, suggesting that the HEL beta-globin genes (i) are transcriptionally competent, (ii) become activated in response to a positive trans-acting element within the MEL environment, and (iii) fail to express into the HEL environment because of either the absence of a positive trans-acting element or the presence of a trans-acting inhibitor of beta-globin gene expression. In addition to beta-globin, the primary HEL-MEL hybrids co-expressed gamma-globin; however, gamma-globin expression segregated by subcloning so that secondary and tertiary clones either expressed only beta-globin or co-expressed gamma- and beta-globin. The results of subcloning can be explained by assuming that gamma-globin gene expression is controlled by a HEL cell-derived transacting element encoded by a gene not syntenic to chromosome 11 or by postulating that the HEL gamma-globin genes become randomly modified during the continuous proliferation of hybrids.

Animals↗
PubMed1985

Marginal zone macrophages in the mouse spleen identified by a monoclonal antibody. Anatomical correlation with a B cell subpopulation.

The reactivity of a monoclonal antibody, ER-TR9, that demonstrates heterogeneity among mononuclear phagocytes is described. In the spleen, ER-TR9 exclusively reacts with a population of macrophages located in the marginal zone. ER-TR9 does not react with macrophage antigen 1-positive red pulp macrophages or any other types of splenic stromal cells. ER-TR9+ ve cells localize in anatomical proximity of a subpopulation of B cells, i.e., B cells that are immunoglobulin M positive and weakly positive to negative for immunoglobulin D. The possible significance of this particular interaction between both cell types during the immune response is discussed.

Animals↗
PubMed1984

[Computerized system for the acquisition and analysis of bioelectric waves].

With collaboration of medicals, electronics and informatics; we have evaluated a method destined to be a potent instrument for the analysis and store of bioelectrical signal. The signal can be taken directly from the subjects or from a tape recorder; we can call again stored for evaluating the gradient grade, the integral and other mathematical evaluations of traits of a curves; in example EEG, EOG, PEV, etc.

Computers↗
PubMed1984

Monoclonal antibodies to stromal cell types of the mouse thymus.

Seven hybridoma cell lines secreting monoclonal antibodies (mAb) to nonlymphoid cells of the mouse thymus have been prepared. These mAb clearly demonstrate the heterogeneity of the thymic stroma. Based on their anatomical distribution patterns observed with the immunoperoxidase technique on frozen tissue sections, they were subdivided into four groups. The first group of mAb, ER-TR1, 2 and 3, detects antigens encoded for by the I region of the major histocompatibility complex. These antigens are expressed on both stromal and lymphoid cells in lymphoid organs. mAb of the second category, ER-TR4, react with epithelial cells in the thymic cortex. mAb of the third group detect stromal cells of the thymic medulla. One antibody of this group, ER-TR5, exclusively reacts with medullary epithelial cells. ER-TR6, the other antibody of this group, reacts with medullary interdigitating cells and macrophages. The fourth type of antibodies, ER-TR7, detects the reticular fibroblasts of the thymus. The possible role of the thymic cell types detected by the present antibodies in T cell differentiation is discussed.

Animals↗