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M Melis

Publications and source records attributed to M Melis.

At least 109 records · Page 6Linked to original sources
PubMed1984

Immunohistology of thymic nurse cells.

The demonstration of thymic nurse cells (TNC), complexes between stromal cells and thymocytes, in cell suspensions of murine thymuses, prompted us to investigate (1) the relationship of TNC to other thymic stromal cell types defined in situ, and (2) the maturation stage of the enclosed thymocytes. To this purpose we incubated frozen sections of TNC suspensions with various monoclonal antisera directed to T cells and stromal cell types, using immunohistology. This approach enabled us to study antigen expression on the "nursing" cell itself and to analyze the phenotype of the enclosed lymphocytes in cross sections of TNC. The results show that lymphocytes enveloped by TNC express high levels of Thy-1, moderate levels of T200, and variable amounts of Lyt-1. Due to enzymatic degradation Lyt-2 expression could not be studied. The enveloped cells also bear PNA receptors, but no detectable I-A/E antigens. Expression of H-2K antigens on enclosed thymocytes varied from weak to absent. The "nursing" cells react with ER-TR4, a monoclonal antibody which detects cortical epithelial-reticular cells. In addition TNC express I-A/E and H-2K antigens. In contrast, TNC do not react with ER-TR 5 and 7, monoclonal antibodies, which detect medullary epithelial cells and reticular fibroblasts, respectively. TNC do not express the macrophage antigens Mac-1 and Mac-2. We conclude that TNC in vitro represent the in vivo association of epithelial-reticular cells with cortical thymocytes. However, the enclosed thymocytes do not constitute a phenotypically distinct subset of subcapsular or outer cortical cells.

Animals↗
PubMed1984

Morphological and statistical investigation of the occurrence of 'tubule-like cells' in the renal corpuscle of the mouse kidney induced by sex hormones.

In this report the authors describe the structural and ultrastructural characteristics of some cells constituting the parietal layer of Bowman's capsule of the mouse kidney, which are very similar to the epithelial cells of the proximal convoluted tubule (tubule-like cells). These elements are noted in mature and immature mice of both sexes, but their fine morphology and statistical incidence seem related to the sex and the age of the mice, as revealed by the different responsiveness of the same animals to sex hormones experimentally administered. Such substances, directly and/or through an influence on gonadotropins (especially luteinizing hormone), are able to modify (mainly increasing) the percentage of renal corpuscles possessing tubule-like cells.

Adrenal Glands↗
PubMed1981

A scanning and transmission electron microscopic study of experimental extrahepatic cholestasis in the rat.

The rat liver after extrahepatic biliary obstruction was studied by SEM and TEM in correlation with basic histochemical techniques. Cholestasis was verified by serological methods. The biochemical data (increase in serum bilirubin values, a gradual lowering of the albumin fraction), in agreement with the ultrastructural results of a sparse RER, suggested a gradual decrease of the protein synthetic activity of the hepatocyte. SEM and TEM revealed numerous fat-storing cells, closely associated with patches of connective fibrils in the subendothelial spaces. Further ultrastructural observations demonstrated: a) a proliferation of the intrahepatic biliary tree (ductular proliferation, including newly formed ducts with sacculation and diverticuli); b) an increased number of canaliculo-ductular junctions and, c) an increase in the length of the bile canalicular network due to its tortuous course, pocketing and side branching. The occurrence of an intact cytoplasmic barrier separating the bile canalicular lumen from the Disse's space together with the results obtained by retrograde infusion of ferritin into the biliary tree suggested that the regurgitation pathway by ductular reabsorption and by transhepatocytic transport is the best documented and most acceptable, at least in the rat.

Animals↗
PubMed1977

The contractile nature of the tubular-like cells of the parietal layer of the Bowman's capsule in male mice. An immunochemical and ultrastructural study.

The tubule-like cells (TLC) of the parietal layer of the Bowman's capsule of the renal corpuscle in normal male mice are provided with bundles of thin microfilaments (50-70 A). Moreover, the ultrastructural observations demonstrated that similar thin filaments (50-70 A) are located in the flattened cells of the parietal layer of the Bowman's capsule and in the tubular cells. All the above cells bind antimyosin-like antibodies. Considering the correspondence between the immunochemical and ultrastructural findings, it is suggested that the microfilaments located in TLC contain a 'myosin-like' protein.

Animals↗
PubMedDate not supplied

Ochronotic arthropathy: structural and ultrastructural features.

Fragments of articular cartilage and synovial membrane in a case of ochronosis were studied by light microscopy (LM), polarized light, and transmission electron microscopy (TEM). Granular and/or shard-shaped pigments were observed in the synovia, cartilage, and subchondral tissue, and dispersed pigment was also seen in the synovial fluid. Zones of the articular cartilage surface showed small erosions near shards, and sometimes, when the degenerative process was in an advanced stage, a substitutive fibrosis of the cartilage edge was demonstrated. LM and TEM observations of the samples studied revealed an alteration of collagen fibrils that appeared wavy and sometimes fragmented with loss of periodicity. They were always mixed with the dispersed pigment. A peculiar finding that characterized this ochronotic case was the complete absence of inflammatory infiltrates or signs of monocyte-macrophage activation. These structural and ultrastructural observations suggest that the pigment deposition in the articular surfaces was due to the synovial fluid circulation and partially to subchondral blood flow, which transports and stores the ochronotic pigments in the synovia and cartilage. These etiopathologic elements associated with the mechanical pathogenesis naturally present in the joints can contribute to the explanation of the pathogenesis and origin of ochronotic arthropathy.

Arthritis↗
PubMedDate not supplied

[Differential diagnostic problems between nodular fasciitis and soft-tissue sarcomas. A review of the literature and a case report].

After a review of literature and the report of a case with intrathoracic location, the authors consider present criteria for a correct diagnosis of low grade soft tissue sarcoma, when the possibility of nodular fasciitis is under evaluation. Nodular fasciitis is a benign pathology up to day not well characterised from the clinical and pathological point of view. The authors conclude that differential diagnosis between low grade soft tissue sarcoma and nodular fasciitis is frequently possible only on the basis of clinical course evaluation; otherwise the management may be inadequate.

Adult↗
PubMedDate not supplied

The impact of an incomplete preoperative colonoscopy in patients with colorectal cancer.

Total large bowel evaluation remains an essential step in the treatment of patients with colorectal cancer (CRC). Colonoscopy is the gold standard in the evaluation of the colon for colorectal tumors, but may be incomplete due to tumor obstruction, which is a frequent event in distal cancers. Double-contrast barium enema has a lower accuracy and is not ideal in the presence of signs of obstruction. In theory, intraoperative colonoscopy is a valid alternative, but its routine use is impeded by various practical limitations. Preoperative survey of the colon in 521 consecutive patients treated for CRC in our department was based on colonoscopy (92.5%). Our series was characterised by a high percentage of distal lesions (76.4%) and therefore by a high percentage of incomplete preoperative colonoscopies (50.4%) due to tumor obstruction. In the presence of an incomplete preoperative colonoscopy, we evaluated the entire colon with a double-contrast barium enema in selected cases (36.7%) and with a postoperative colonoscopy within 3 months of surgery in almost all patients (93.4%). The overall rate of complete endoscopic evaluation, either pre- or postoperatively, was 96.7%. The incidence of adenomas was significantly higher in the preoperative examinations as compared to early postoperative colonoscopy. This means that in distal cancer the vast majority of polyps will be located in the distal colon and therefore included in a standard resection. Four patients (0.8%), required a second operation for treatment of a missed lesion (2 benign and 2 malignant). The need for a repeat surgery apparently did not affect the therapeutic results in these four patients. On the basis of our experience, intraoperative colonoscopy would not appear to be a mandatory procedure in all cases of incomplete preoperative evaluation of the colon. However, in the absence of prospective, randomised trials comparing intraoperative vs early postoperative colonoscopy, the dilemma as to the strategy of choice remains.

Adenoma↗