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Biomedical subjects

G Majno

Publications and source records attributed to G Majno.

At least 73 records · Page 4Linked to original sources
PubMed1973

Mesothelial injury and recovery.

This paper describes the cytologic effects of drying or wetting of visceral peritoneum and the course of mesothelial regeneration. Using en face silver staining and electron microscopy, it was found that mesothelial cells disappeared from the surface after the cecum was either briefly dried or kept wet with isotonic saline for 30 minutes; the fibrin-slide technic showed that such injury caused a loss of the normal serosal fibrinolytic activity. In following the course of mesothelial regeneration using the same technics, it was apparent that free-floating peritoneal mononuclear cells settled on the denuded surface where they spread out, attached to one another, and developed features (eg, microvilli) typical of mature mesothelial cells; such new mesothelium showed a greatly enhanced fibrinolytic activity.

Animals↗
PubMed1973

Human smooth muscle autoantibody. Its identification as antiactin antibody and a study of its binding to "nonmuscular" cells.

When human serum containing smooth muscle autoantibodies (SMA) is incubated with extracts containing thrombosthenin (the contractile material of platelets) or thrombosthenin-A (the actin-like moiety of thrombosthenin), it loses its ability to bind to smooth muscle. Such binding is also diminished when SMA serum is incubated with lysed platelets; this effect is not seen if the SMA serum is incubated with intact platelets. The incubation of other autoantibodies (such as antimitochondrial or antinuclear antibodies) with thrombosthenin does not affect their binding to the specific antigens. It appears that SMA is directed against the actin fraction of thrombosthenin-ie, SMA is an antiactin antibody. Hence the name of antiactin autoantibody (AAA) seems more appropriate than smooth muscle autoantibody (SMA). A study of the distribution of antiactin autoantibody binding in rat, rabbit and man shows that several "nonmuscular" structures contain actin under normal conditions; these include megakaryocytes and platelets, normal rat hepatocytes, the brush borders of renal tubules, the periphery of epithelial cells of the intestine, polymorphs and lymphocytes in lymph nodes (but not thymic cortical lymphocytes). In addition, certain cell types (such as granulation tissue fibroblasts, cultivated fibroblasts, hepatocytes or regenerating liver and epidermal cells growing over a skin wound) can reversibly acquire a massive network of actin-containing microfilaments resembling those in smooth muscle.

Absorption↗
PubMed1972

Granulation tissue as a contractile organ. A study of structure and function.

CONTRACTING GRANULATION TISSUES CONTAIN FIBROBLASTS THAT DEVELOP CHARACTERISTICS TYPICAL OF SMOOTH MUSCLE: (a) They contain an extensive cytoplasmic fibrillar system. (b) They show immunofluorescent labeling of their cytoplasm with human anti-smooth muscle serum. (c) The nuclei show complicated folds and indentations, indicative of cellular contraction. (d) There are cell-to-cell and cell-to-stroma attachments. (e) It is possible to extract similar quantities of actomyosin (having the same adenosine triphosphatase activity) from granulation tissue and from pregnant rat uterus. (f) Strips of granulation tissue, when tested pharmacologically in vitro, behave similarly to smooth muscle. All these data support the view that, under certain conditions, fibroblasts can differentiate into a cell type structurally and functionally similar to smooth muscle and that this cell, the "myo-fibroblast," plays an important role in connective tissue contraction.

Actomyosin↗
PubMed1972

Dupuytren's contracture: fibroblast contraction? An ultrastructural study.

In 6 cases of Dupuytren's disease and 1 of Ledderhose's disease, the nodules of the palmar and plantar aponeurosis were examined by light and electron microscopy. The cells composing these nodules, presumably fibroblasts, showed three significant ultrastructural features: (1) a fibrillar system similar to that of smooth muscle cells; (2) nuclear deformations such as are found in contracted cells, the severest being recognizable by light microscopy (cross-banded nuclei); (3) cell-to-cell and cell-to-stroma attachments. Based on these data and on recent information about the biology of the fibroblasts, it is suggested that these cells are fibroblasts that have modulated into contractile cells (myofibroblasts), and that their contraction plays a role in the pathogenesis of the contracture observed clinically.

Adult↗
PubMed1971

Contraction of granulation tissue in vitro: similarity to smooth muscle.

Strips of granulation tissue from three different experimental models contract in vitro when treated with substances that induce contraction of smooth muscle. Because the fibroblasts in such tissues have some ultrastructural features typical of smooth muscle, our findings indicate that fibroblasts are able to modulate toward a cell type that is morphologically and functionally close to smooth muscle.

Angiotensin II↗