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Biomedical subjects

G Gabbiani

Publications and source records attributed to G Gabbiani.

At least 235 records · Page 13Linked to original sources
PubMed1980

Lymphocyte alpha-actinin. Relationship to cell membrane and co-capping with surface receptors.

Mouse spleen lymphocytes synthesize a protein which comigrates with skeletal muscle alpha-actinin on two-dimensional gel electrophoresis and is immunoprecipitated by an antibody directed against skeletal muscle alpha-actinin. Mouse lymphocyte alpha-actinin is present in membrane fractions, and is immunoprecipitated from lymphocyte detergent lysates by an antiserum made against these purified membranes. The anti-alpha-actinin activity of this antiserum is not adsorbed after incubation with fixed intact lymphocytes. Lymphocyte alpha-actinin does not bind concanavalin A and it is inaccessible to lactoperoxidase-catalyzed surface iodination. Double immunofluorescence shows that alpha-actinin moves concurrently along the cell membrane with redistributed surface immunoglobulins and Thy-1 antigen, and remains associated up to 30 min with surface aggregates of these receptors. Our results suggest that lymphocyte alpha-actinin, as defined by molecular weight and cross reactivity with the antibody against the muscle protein, (a) is associated with the cell membrane, (b) is not expressed at the cell surface, and (c) participates in the movement of surface receptors.

Actinin↗
PubMed1980

Biochemistry and histology of the connective tissue of Dupuytren's disease lesions.

When compared to age-matched control aponeurosis, lesions of Dupuytren's disease contain higher contents of water, collagen and chondroitin-sulphate, as well as increased proportions of soluble collagens and of reducible cross-links; these indicate synthesis of new collagen. The lesions show also increased amounts of type III collagen and an increased hydroxylation and glycosylation of the reducible cross-links. All these parameters are characteristic of granulation and scar tissues. Type III collagen was located by means of immunofluorescence on thin argyrophilic fibres and also within the large fibre bundles which appeared to be disrupted into microbundles. The increase of type III collagen and the presence of myofibroblasts in the apparently unaffected aponeurosis show that the disease is widespread and suggest that it is initiated within the aponeurosis and propagated by the cells migrating along the collagen bundles.

Adult↗
PubMed1979

Intranuclear injection of anti-actin antibodies into Xenopus oocytes blocks chromosome condensation.

The role of contractile proteins in the structural organisation of the interphase nucleus and of metaphase chromosomes is largely unknown. Actin has been found in interphase nuclei of different species, especially in association with condensed chromatin. In the germinal vesicle (nucleus) of Xenopus oocytes, actin has been localised in the nuclear gel supporting the chromosomes and the extrachromosomal nucleoli. It has been reported that the premeiotic lampbrush chromosomes in these germinal vesicles are positively stained for actin and tubulin by the immunoperoxidase technique. Moreover, the longitudinal contraction of these chromosomes is ATP dependent. Therefore it has been suggested that actin participates in the structural organisation of the highly specialised lampbrush chromosomes. However, actin is not a major component of the metaphase chromosome scaffold. The results reported here suggest that actin is involved in the condensation of Xenopus chromosomes.

Actins↗
PubMed1979

An actin-destabilizing factor is present in human plasma.

Plasma and serum of humans or experimental animals contain a factor which destabilizes F-actin. The factor has no DNAse or thrombin activity and after incubation with F-actin does not modify the position of the actin band on a SDS polyacrylamide gel. Hence it probably depolymerizes F-actin.

Actins↗
PubMed1979

Actin is unevenly distributed in the pituitary gland.

In view of the suggestion that actin-like proteins might be involved in the final steps leading to hormone secretion, the actin content of pituitary glands of adult rats was determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis (for total actin), by the DNAse method (which measures predominantly monomeric actin) and by immunocytochemistry. The amount of actin present in the neural lobe, expressed per mg total protein, was found to be comparable to that of other neural tissues. In contrast, in the anterior lobe, the ratio was significantly lower. The intensity of immunofluorescent staining with anti-actin antibodies was higher in the neural lobe than in either anterior or intermediate lobes. The intensity and distribution of tubulin immunofluorescent staining with anti-tubulin antibodies resembled that of anti-actin antibodies. Thus, three independent methods point to an uneven distribution of actin in the subdivisions of the pituitary gland, although all these subdivisions are believed to secrete their hormones by exocytosis. These data suggest that the bulk of actin present in pituitary cells is unlikely to be involved only in exocytosis, but may be implicated also in the intracellular translocation of secretory products.

Actins↗
PubMed1979

Supercontraction in crayfish muscle: correlation with a peculiar actin localization.

Crayfish muscle, like muscles from some other invertebrates, can supercontract. This muscle shortening is characterized by an overlap of thin filaments with crossing of thick filaments through the Z discs. In intact muscle cells, supercontraction does not seem to induce irreversible structural modifications in the tissue. Isolated crayfish myofibrils in the relaxed state cannot be distinguished from vertebrate myofibrils under light microscope, either by phase contrast or by immunofluorescence, with antiactin antibodies, actin being localized in the I bands. However, when isolated crayfish myofibrils are supercontracted, irreversible dammage occurs, most thin filaments being lost. Actin becomes then hardly detectable, being visible, by immunofluorescence, either in the Z discs or evenly distributed in the whole myofibril. During myofibril supercontraction, high amounts of denatured actin, become soluble as shown by SDS-PAGE, by double immunodiffusion, and by DNAse inhibition.

Actins↗
PubMed1979

Actin microfilaments, cell shape, and secretory processes in isolated rat hepatocytes. Effect of phalloidin and cytochalasin D.

The effects of phalloidin and cytochalasin D, drugs which, respectively, stabilize and destabilize actin microfilaments, have been tested on isolated rat hepatocytes. Both drugs produced a modification of cell shape, characterized by protrusions bulging from the cytoplasm. In phalloidin-treated hepatocytes, an accumulation of actin microfilamentous network was detectable at the base of each protrusion by electron microscopy, immunofluorescence, and HMM decoration. This accumulation of microfilaments was absent in cytochalasin D-treated cells. The release of triglycerides, an index of very low density lipoprotein secretion, was inhibited by phalloidin or cytochalasin D, and accompanied by an increase in cellular triglycerides. At the electron microscope examination, triglyceride accumulation was represented by fat droplets and vesicle-enclosed, very low density lipoprotein-like particles. Total protein and albumin secretion was only very slightly modified by either one of these drugs. With the use of various phalloidin analogs, a correlation was observed between their respective ability to stabilize F-actin in vitro, and their effects on cell shape and triglyceride secretion. In conclusion, phalloidin, and cytochalasin D: (a) modify the shape of isolated hepatocytes; (b) inhibit lipoprotein secretion. These effects possibly result from a modification of actin microfilament function.

Actins↗
PubMed1979

The cytoskeleton in cancer cells in animals and humans.

Immunofluorescent staining of human cancer cells with antibodies against actin and myosin shows an important increase of brightness when compared with staining of normal cells from control tissues. Electron microscopic examination of cancer cells shows accumulation of cytoplasmic microfilaments (40--80 A in diameter) with some larger filaments (100--120 A in diameter) scattered in between compared to normal cells from control tissues. Such filaments are particularly abundant at the cell periphery. These findings indicate that the cytoplasmic contractile apparatus of cancer cells is more developed than that of normal cells. Such development may at least in part explain the invasive activity of malignant cells.

Actins↗
PubMed1979

Morphologic and functional changes of the aortic intima during experimental hypertension.

The morphology and permeability to horseradish peroxidase of the rat aortic intima have been investigated in three experimental models of hypertension having different values of plasma renin content and plasma aldosterone level. During hypertension the aortic endothelium shows three main changes: 1) increased arithmetic mean thickness, with prominent rough endoplasmic reticulum and polyribosomes; 2) the appearance of actin microfilament bundles; and 3) increased permeability to horseradish peroxidase. These changes are not present in all models, do not appear to depend on hypertension per se, and are independent of each other. The subendothelial layer of hypertensive animals shows an increased thickness that appears to be correlated with an increase of endothelial cell volume. Our results suggest that: 1) the aortic intima reacts differently to different types of hypertension, and 2) factors other than hypertension per se play a role in the development of vascular changes observed in animals with elevated blood pressure.

Animals↗
PubMed1979

The role of contractile proteins in wound healing and fibrocontractive diseases.

During the healing of an open wound, the majority of granulation tissue fibroblasts (myofibroblasts) acquire morphological, biochemical, pharmacological, and immunological characteristics typical of contractile cells. The presence of contractile proteins and the appearance of gap junctions between several myofibroblasts make them similar to cultivated fibroblasts; these have been proven to develop in vitro a contractile force similar to that exerted by granulation tissue during wound contraction. These observations suggest that myofibroblasts are responsible for granulation tissue contraction. Epidermal cells moving over an open wound also develop a contractile apparatus and many cellular connections in the form of gap junctions. These changes may be the morphological support for epithelial cell movements. The presence of gap junctions between myofibroblasts and healing epidermal cells shows that granulation tissue contraction and epithelial cell movement are probably synchronized rather than individual phenomena.

Actomyosin↗
PubMed1978

Immunofluorescent subcellular localization of some muscle proteins: a comparison between tissue sections and isolated myofibrils.

The localization of parvalbumin in fish white muscle and of the calcium binding protein, of arginine kinase and of glycogen phosphorylase in crayfish tail muscle have been investigated by immunofluorescence using isolated myofibrils and muscle sections as starting materials. It is shown that the four proteins appear to be localized on the thin filaments when myofibrils are used as starting material. This result contrasts with previous observations where it appeared that parvalbumin in fish muscle and arginine kinase in crayfish muscle were distributed uniformly within the cell. This discrepancy is discussed in relation to the high solubility of these proteins. In the light of the present knowledge about striated muscles from these two organisms, it seems that the roles of parvalbumin in fish and of the calcium binding protein in crayfish are probably different.

Animals↗
PubMed1978

Digital contracture deformity after implantation of a silicone prosthesis: light and electron microscopic study.

Following the implantation of a silicone tendon prosthesis for reconstruction of a deep flexor tendon, an extensive, dense, contractile fibrosis developed rapidly. The resulting flexion deformity ultimately necessitated an amputation. The amputated specimen was examined by light and electron microscopy. A great many myofibroblasts were seen in the new tendon sheath, which, because of their contractile properties, probably caused the deformity.

Contracture↗
PubMed1978

Cytoplasmic filaments and gap junctions in epithelial cells and myofibroblasts during wound healing.

During the healing of an experimental skin wound, epidermal cells and granulation tissue fibroblasts (myofibroblasts) develop an extensive cytoplasmic contactile apparatus. Concurrently, the proportion of epidermal cell surface occupied by gap junctions increases when compared to normal skin, and newly formed gap junctions appear between myofibroblasts; this suggests that epidermal cell migration and granulation tissue contraction are synchronized phenomena.

Animals↗
PubMed1978

Autoantibodies (cold lymphocytotoxins, antiactin antibodies and antinuclear factors) in nasopharyngeal carcinoma patients.

LTA, SMA and ANA were found at higher frequencies in sera from NPC patients than in those from matched controls. The frequency and GMTs of LTA-positive sera varied with the origin of the patient (Chinese greater than North African greater than Caucasian, thus paralleling the risk for NPC in each ethnic group) and the stage of the disease (stage IV greater than stage I). A positive correlation was found between LTA and anti-EBV titres with regard to anti-VCA and anti-EBNA antibodies. SMA were specific for actin, and their titres did not correlate with anti-EBV (VCA, EBNA and EA) titres. Although there was no evidence for an abnormal immunogenicity of the self components recognized by the three autoantibodies, their independent augmentations did not favour the alternative hypothesis of a common central mechanism for their production. The origin and the biological significance of these autoantibodies remains, therefore, to be explained.

Actins↗