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Biomedical subjects

G Gabbiani

Publications and source records attributed to G Gabbiani.

At least 217 records · Page 12Linked to original sources
PubMed1982

Effect of phalloidin on liver actin distribution, content, and turnover.

Phalloidin increases F-actin microfilament content and actin-directed immunofluorescence in hepatocytes in vivo and also increases actin polymerization and the stability of F-actin in vitro. We studied the sensitivity of immunofluorescent staining of actin to an actin depolymerizing factor (ADF) as well as actin content, degree of polymerization, and turnover in livers of in vivo phalloidin-treated rats. Pretreatment with ADF abolished anti-actin antibody (AAA) staining of normal liver but did not modify staining of livers from phalloidin-treated animals. Planimetric analyses of SDS-polyacrylamide gels showed the percent actin of total protein was increased by approximately 40% and the absolute amount of actin by approximately 43%, ten days after daily phalloidin treatment (50 micrograms/100 gm body weight). Similar but smaller changes could be seen after one day of treatment. Ultracentrifugational analyses of liver extracts indicated no change in the amount or proportion of G-actin but a 194% increase in the proportion of F-actin in ten-day treated animals, changes also apparent in one day animals. Neither the relative fractional rate of actin synthesis nor its synthesis as a percent of total protein synthesis was altered either at one-day or ten-day post-phalloidin treatment. Dualisotope experiments indicated that the rate of actin degradation was decreased selectively in the one- to three-day period following drug treatment. Thus, phalloidin appears to stabilize actin against the depolymerizing actions of ADF, increases the proportion of F-actin without altering the size of the G-actin pool, and causes accumulation of actin by decreasing its relative rate of degradation.

Actin Depolymerizing Factors↗
PubMed1982

Actin organization and fibrin-clot retractile activity of cultured mouse fibroblasts.

It is known that human and animal fibroblasts are able to induce the retraction of a fibrin clot. In the present study the correlation between (i) fibrin-fibroblasts during growth, (ii) the number of actin stress-lines in mouse fibroblasts during growth in culture, and (iii) the sensitivity of actin stress-lines to a powerful actin-depolymerizing factor (ADF), present in plasma and serum of humans and laboratory animals was investigated. Fibroblasts at early passages (2-4) were tested for these parameters at various intervals after seeding (24, 96, and 168 h). The number of actin stress-lines was progressively higher, while the sensitivity to ADF action was progressively lower in cells cultured from 24 to 168 h; the FCR capacity was significantly decreased at 168 h. These data suggest that cells containing weakly polymerized and/or stabilized actin are more active than those containing highly polymerized and/or stabilized actin in triggering fibroblast contraction.

Actin Depolymerizing Factors↗
PubMed1982

The area of attachment of cytotoxic T lymphocytes to their target cells shows high motility and polarization of actin, but not myosin.

Conjugates of cytotoxic T lymphocytes attached to their target cells were studied by double immunofluorescence on fixed smears to detect simultaneously the localization of actin and myosin within the cells. Actin was found to be polarized in the area of attachment of the lymphocytes (but not of the target cells), whereas myosin remained evenly distributed in the cytoplasm. When living conjugates were brought to 37 degrees C to induce cytotoxicity, this pattern remained unchanged, but observation by interference reflexion microcinematography revealed a high motility of the lymphocytes in the contact area. This localized motility in the area of attachment associated with a peculiar actin polarization, which has no equivalent in any type of cell contact presently known, could represent a necessary step in the sequence of events leading to target cell killing by cytotoxic T lymphocytes.

Actins↗
PubMed1982

Vimentin-containing smooth muscle cells in aortic intimal thickening after endothelial injury.

We evaluated by means of (1) indirect immunofluorescence and (2) densitometric analysis of stained sodium dodecyl sulfate-polyacrylamide gels the distribution and amount of vimentin and desmin in the aortic media and intima of normal rats and of rats in which the endothelium had been removed by means of an inflated balloon catheter. According to previous reports, in normal aorta vimentin was found in endothelial cells and in the majority of smooth muscle cells, and desmin was found in several smooth muscle cells. Smooth muscle cells present in areas of intimal thickening in rats whose aortas were injured with a balloon were stained only with vimentin antibodies, whereas in the media underlying intimal thickening, the distribution of vimentin and desmin was similar to that seen in normal rats. Portions of aorta (media plus intima) with intimal thickening had a significantly increased vimentin to desmin ratio compared with similar portions of aorta in normal rats. These results suggest that after endothelial injury either only vimentin-containing smooth muscle cells are responsible for replication and migration into the intima, or that smooth muscle cells, while migrating into the intima, synthesize only vimentin.

Animals↗
PubMed1982

Volume, surface, and junctions of rat aortic endothelium during experimental hypertension: a morphometric and freeze fracture study.

Three models of hypertension were induced in Wistar rats: (1) aortic ligature between renal arteries, (2) uninephrectomy and Na-rich diet, (3) uninephrectomy, 0.9 per cent NaCl as drinking fluid and subcutaneous administration of desoxicorticosterone acetate (DOCA). We studied in aortic endothelium during the early (7 to 10 days) and late (40 days) phases of these models: (1) volume, surface, and ratios of tight and gap junctions to lateral membrane surface by means of morphometric analysis using thin-sectioning electron microscopy, and (2) organization of tight and gap junctions by means of freeze fracture electron microscopy. Compared with normotensive rats: (1) volume of the endothelial cell layer was increased in all hypertensive situations with the exception of the late group after aortic ligature; the increase was most marked early after aortic ligature and early and late after DOCA; (2) endothelial surface to volume ratio was markedly decreased early after aortic ligature and early and late after DOCA; the ratio of luminal, abluminal, and lateral to total endothelial surface remained unchanged in all hypertensive situations; (3) in all hypertensive situations the ratio of tight junctions to lateral membrane surface increased, whereas the ratio of gap junctions to lateral membrane surface showed no significant change; (4) in all hypertensive situations lateral endothelial plasma membranes contained, in addition to zonular and macular type tight junctions, many small aggregates of intramembrane particles in the P face and particle-free grooves in the E face; these structures were particularly numerous early after aortic ligature and early and late after DOCA; (5) in all hypertensive situations (most early and late after DOCA and least after sodium-rich diet) gap junctions were irregularly shaped in contrast to those of normotensive animals. Our results suggest that : (1) different types of hypertension produced different degrees of hypertrophy of the endothelial cell layer ; (2) hypertension increases the ratio of tight junctions to lateral endothelial membrane surface; the presence of small aggregates of intramembrane particles (probably representing assembly and/or disassembly of tight junctions) in the lateral endothelial plasma membranes is responsible for this phenomenon; (3) hypertension does not change the ratio of gap junctions to lateral membrane surface but results in abnormal gap junction morphology.

Animals↗
PubMed1981

Vascular smooth muscle cells differ from other smooth muscle cells: predominance of vimentin filaments and a specific alpha-type actin.

Smooth muscle cells of the digestive, respiratory, and urogenital tracts contain desmin as their major, if not exclusive, intermediate-size filament constituent and also show a predominance of gamma-type smooth muscle actin. We have now examined smooth muscle tissue of different blood vessels (e.g., aorta, small arteries, arterioles, venules, and vena cava) from various mammals (man, cow, pig, rabbit, rat) by one- and two-dimensional gel electrophoresis of cell proteins and by immunofluorescence microscopy using antibodies to different intermediate-sized filament proteins. Intermediate-sized filaments of vascular smooth muscle cells contain abundant amounts of vimentin and little, if any, desmin. On gel electrophoresis, vascular smooth muscle vimentin appears as two isoelectric variants of apparent pI values of 5.30 and 5.29, shows the characteristic series of proteolytic fragments, and is one of the major cell proteins. Thus vimentin has been demonstrated in a smooth muscle cell present in the body. Vascular smooth muscle cells are also distinguished by the predominance of a smooth muscle-specific alpha-type actin, whereas gamma-type smooth muscle actin is present only as a minor component. It is proposed that the intermediate filament and actin composition of vascular smooth muscle cells reflects a differentiation pathway separate from that of other smooth muscle cells and may be related to special functions and pathological disorders of blood vessels.

Actins↗
PubMed1981

Immunochemical identification of intermediate-sized filaments in human neoplastic cells. A diagnostic aid for the surgical pathologist.

Forty-three tumors were investigated by means of immunofluorescence with the use of antibodies against the following different classes of intermediate-sized (10 nm) filament proteins: 1) cytokeratins, 2) vimentin, and 3) desmin. In general, the immunologic features of tumor-cell intermediate filaments are those present in their tissue of origin. It can be seen, therefore, that, during neoplastic transformation, there are no major changes in the synthesis of the type of intermediate filament proteins when compared to normal tissues. Immunologic identification of these proteins furnishes the surgical pathologist with a quick and clear-cut way to differentiate tumors of mesenchymal origin from epithelial neoplasms, and in particular to distinguish between malignant lymphomas and lymph node metastases of undifferentiated carcinomas.

Adult↗
PubMed1981

Severe familial cholestasis in North American Indian children: a clinical model of microfilament dysfunction?

Studies of 14 North American Indian children with a familial type of severe neonatal cholestasis are described. Jaundice occurred during the neonatal period in 9 children, but disappeared before the end of the 1st yr. Progressive liver damage was documented by the persistence of high levels of alkaline phosphatase, moderate elevation of transaminases, and severe pruritus. Serum bile acids were constantly elevated (3.0-119.5 microgram/ml). Early portal hypertension and variceal bleeding necessitated portal-systemic shunts in 7 children. By light microscopy, the early stage was characterized by hepatitis with giant-cell transformation and biliary stasis. Later on, portal fibrosis became evident and was followed by cirrhosis. By electron microscopy bile canaliculi appeared slightly dilated with preservation or only partial loss of microvilli. They were surrounded by a prominent pericanalicular filamentous web. Immunofluorescence studies indicated the presence of action-containing microfilaments. This group of children might represent a human model of microfilament dysfunction-induced cholestasis.

Actins↗
PubMed1981

Organization of actin in epithelial cells during regenerative and neoplastic conditions. Correlation of morphologic, immunofluorescent, and biochemical findings.

To study the distribution and the degree of polymerization of actin in regenerating and neoplastic cells we have examined: (1) the immunofluorescent staining of these cells with human antiactin antibodies (AAA), (2) the sensitivity of cellular actin to AAA staining after treatment with the actin-depolymerizing factor present in plasma or serum of several animal species, and (3) the total and relative amounts of F- and G-actin in tissue preparations, determined by means of differential centrifugation and densitometric analysis of stained sodium dodecyl sulfate-polyacrylamide gels. There was little or no difference in staining intensity between normal and regenerating or tumoral tissues when treated with AAA, but AAA staining of normal tissues was abolished, whereas staining of regenerating and tumoral tissues remained intense after incubation with actin-depolymerizing factor. Gel analysis showed that normal, regenerating, and neoplastic epidermal cells contained similar amounts of actin. Compared to controls, regenerating liver tissue contained slightly more total actin, nearly the same amount of G-actin, but a substantially increased amount of F-actin. These results suggest that: (1) compared to controls, a greater proportion of regenerating and neoplastic tissue actin is stabilized against the action of actin-depolymerizing factor; (2) changes involving actin in regenerating and neoplastic epithelial cells reflect changes in its degree of polymerization rather than its total amount.

Actins↗
PubMed1981

Desmosomes and gap junctions in precarcinomatous and carcinomatous conditions of squamous epithelia. An electron microscopic and morphometrical study.

By means of morphometrical techniques we have studied the distribution of gap junctions and desmosomes in uterine epithelial cells during normal, preneoplastic and neoplastic conditions, and in skin and oral cavity during normal and neoplastic conditions. The percentage of cell surface occupied by gap junctions as well as the surface to volume ratio of these structures decreases progressively from normal to metaplastic and moderately dysplastic cervical epithelium and is practically null in more severe conditions. The percentage of cell surface occupied by desmosomes decreased significantly from normal to metaplastic epithelium; the decrease is less sharp from metaplastic epithelium to dysplastic epithelium and carcinoma in situ; it then becomes again abrupt from carcinoma in situ to invasive carcinoma. In skin and oral cavity, there is no significant change between the percentage of cell surface occupied by gap junctions as well as the surface to volume ratio of these structures in normal epithelium and basal cell carcinoma. There is a significant change between normal epithelium and squamous cell carcinoma as well as between basal cell carcinoma and squamous cell carcinoma. The percentage of cell surface occupied by desmosomes and the surface to volume ratio of desmosomes decreases significantly between normal epithelium and basal or squamous cell carcinomas as well as between basal and squamous cell carcinomas. It is probable that a lack of chemical and electronic coupling as well as a lack of mechanical adhesion play a role in determining the invasive behavior of malignant cells.

Adult↗
PubMed1980

Distribution of cytoskeletal elements in cultured skin fibroblasts of patients with Duchenne's muscular dystrophy.

Cultured fibroblasts from patients suffering from Duchenne's Muscular Dystrophy were examined by indirect immunofluorescent techniques using antibodies against actin, myosin, tubulin, and intermediate-sized filaments. The cells display normal patterns of microfilamentous bundles (stress fibres), microtubules, and intermediate-sized filaments suggesting a normal organization of these cytoskeletal structures.

Actins↗
PubMed1980

Evidence for hemocyanin formation in the compound eye of Squilla mantis (Crustacea, Stomatopoda).

In the retina and in the subretinal space of the compound eye of Squilla mantis a special kind of pigment cell is present. The crystalline inclusions of this cell have been identified as hemocyanin, as determined (i) by the dimensional congruence of the crystalline substructure with the dimensions of isolated, purified hemocyanin, and (ii) by the immunofluorescence reaction using anti-hemicyanin antibodies. The ultrastructure of these cells, their location and the presence of crystalline bodies in their cytoplasm suggest that they are sites of hemocyanin synthesis and homologous to the cyanocytes or cyanoblasts of Limulus.

Animals↗