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Biomedical subjects

A Benedetto

Publications and source records attributed to A Benedetto.

At least 73 records · Page 4Linked to original sources
PubMed1987

PGJ2, a new antiviral prostaglandin: inhibition of Sendai virus replication and alteration of virus protein synthesis.

Prostaglandin J2 (PGJ2) was found to suppress dramatically Sendai virus replication in African green monkey kidney cells in culture. PGJ2 was not toxic at the active dose to uninfected cells and did not significantly inhibit macromolecular synthesis, but it specifically stimulated the synthesis of a polypeptide of 74,000 mol. wt. In Sendai virus-infected cells, PGJ2 partially inhibited virus protein synthesis and caused an alteration in the mobility of the virus glycoprotein HN in SDS-PAGE, corresponding to a decrease of about 4000 in its mol. wt. We propose that the PGJ2-induced alteration in the molecular structure of the HN protein prevents the insertion of this protein into the cell membrane thereby blocking virus maturation. The alpha,beta-unsaturated carbonyl group in the cyclopentane ring of the PGJ2 molecule may be necessary for antiviral activity.

Antiviral Agents↗
PubMed1987

Dermatitis in a rubber tyre factory.

An outbreak of occupational dermatitis in a rubber tyre factory is reported. An unusual clinical picture was recognized. Patch tests revealed a high sensitization rate to the MBT derivative used: 2-(2'-4'dinitrophenylthio)benzothiazole. Since tests with MBT mix and dinitrophenol were negative; sensitization to a contaminant was suspected. DNCB was traced as the substance responsible.

Dermatitis, Atopic↗
PubMed1986

Sendai virus replication in Friend erythroleukemia cells. I. Acutely and persistently infected cells become resistant to virus-induced lysis.

Friend leukemia cells (FLC) are susceptible to infection by Sendai virus, a member of the paramyxovirus group. FLC constitute a most suitable model to study virus-host cell interactions, because they grow in suspension (thus avoiding the use of trypsin), and provide an easy way of deriving single-cell clones. When FLC are infected with Sendai virus at high m.o.i., a direct, extensive lysis of the cells ensues, whereas lower doses of virus result in a cytocidal infection whose lethality depends mainly on the virus used, standard or defective interfering egg-grown Sendai virus (EGSV), and on the multiplicity of infection (m.o.i). At later times after infection, FLC become resistant to the Sendai induced lysis (SIL). The SIL resistance can be maintained in single-cell clones that had survived the first infection. The maintenance of the resistant phenotype of the clones requires the serial subcultivation of the cells in the presence of activated EGSV. The mechanisms that presumably regulate the appearance of SIL resistance in Sendai infected FLC are discussed.

Cell Fusion↗
PubMed1986

Modulation of the growth of a human erythroleukemic cell line (K562) by prostaglandins: antiproliferative action of prostaglandin A.

Among several prostaglandins (PGs) tested, PGF1 alpha was found to slightly enhance, while PGAs and PGDs were found to drastically inhibit the growth of K562 cells in culture. This effect was dose dependent. While PGD2 was cytotoxic, PGA1 treatment could totally inhibit K562 cell proliferation, without affecting cell viability. PGA1 action was reversible; however, K562 cells totally lost their growth potential after prolonged exposure to PGAs. While it did not significantly affect DNA and RNA synthesis, PGA1 partially inhibited protein synthesis and glycosylation in these cells. In particular, the production of two polypeptides with molecular weights of 92,000 and 46,000, respectively, was decreased, while the synthesis of a protein with a molecular weight of 74,000 was induced. These results strongly support the concept that PGs are involved in the regulation of cell proliferation, and that PGs containing a reactive alpha, beta-unsaturated carbonyl group in the cyclopentane ring are potential antineoplastic agents.

Bucladesine↗
PubMed1985

Induction and maintenance of flattened morphology in highly adhesive Friend leukemia clones depends on the time- and space-specific assembly of microtubular networks.

Indirect immunofluorescent staining with anti-tubulin antibodies, SEM and TEM were applied to study microtubule (MT) assembly in clones isolated from Friend leukemia cells (FLC, 745 A strain) on the basis of their sensitivity to exogenous fibronectin (FN). Kinetics of cell spreading and elongation were studied using computerized image analysis and SEM. In contrast to 745 A cells, FN-sensitive clones (referred to as FF clones) showed elaborate MT networks when observed by immunofluorescent staining as well as by TEM. A good correlation was found between the degree of spreading and elongation of FF cells and the degree and cellular distribution of their MT. The highest concentration of MT networks oriented parallel to the main cellular axis was observed in very elongated FF cells. The majority of MT in interphase FF cells radiated from the centrosomes; some MT apparently originated from the nuclear membranes. TEM showed the existence of morphological differences between centrosomes of 745 A and FF cells. The characteristic ultrastructure of the centrosomes of FF cells was maintained in trypsinized cells, even if such FF cells lost MT's and acquired a spherical morphology. FF cells, treated with a wide spectrum of MT-disrupting agents, promptly acquired a rounded morphology with rapid dissolution of polymerized tubulin. Removal of MT-disrupting agents from the culture medium rapidly restored a flattened morphology with concurrent regeneration of MT's. During recovery from MT-disrupting agents, FF cells showed increased numbers of centrosomes per cell. We conclude that MT networks cooperate in the attachment, spreading and elongation of FF cells isolated from FLC. Moreover, we hypothesize the existence in FF cells of a variant form of centrosomes as compared with those of 745 A cells.

Animals↗
PubMed1984

Biologic and biochemical differences between in vitro and in vivo passaged Friend erythroleukemia cells. II. Changes in cell surface glycoproteins associated with a highly malignant phenotype.

Friend erythroleukemia cells (FLC), serially passaged in vitro or by intraperitoneal injection in DBA/2 mice, exhibit markedly different tumorigenicity and capacity to metastasize. We have attempted to determine whether the differences in tumorigenicity between these two lines of FLC were correlated with any biochemical changes in their cell membranes. Although consistent modifications of FLC membrane gangliosides were detected after FLC multiplied in the peritoneum, the pattern of FLC gangliosides was not a stable characteristic and did not correlate with tumorigenicity. In contrast, analysis of FLC membrane glycoproteins by cell surface labelling techniques (i.e., galactose-oxidase-borohydride techniques and polyacrylamide gel electrophoresis-fluorography) or by metabolic labelling of glycoproteins with 3H-galactose, revealed consistent differences in the high MW region of the gels between parental in vitro passaged FLC (either 745 or 3Cl-8 cells) and clones derived from in vivo passaged cells. No significant differences in the membrane proteins were detected between in vitro and in vivo passaged FLC when lactoperoxidase-catalyzed iodination and polyacrylamide gel electrophoresis-autoradiography were used. It is seen that repeated in vivo passages of FLC resulted in the appearance of different patterns of membrane glycoproteins and that these changes appeared to be associated consistently with the capacity of these cells to grow as tumor ascites and to metastasize to the liver and spleen.

Animals↗
PubMed1984

SV40 immortalization of adult human mesenchymal cells from neuroretina. Biological, functional and molecular characterization.

Human adult mesenchymal cells from neuroretina (human choroid cells, HC) have acquired an infinite lifespan, following phenotypic transformation with a wild-type SV40. Immortalized cells (HC/SV40) contain high numbers of free circular viral DNA, and integrated molecules in a head-to-tail array in the cellular DNA. HC/SV40 cells express both the virus-coded "T" antigens and the cell-coded p53 transformation-associated protein. The transformed phenotype was further characterized by loss of contact inhibition of cell division, inability to induce the retraction of a fibrin clot and to spread within fibrin, and the existence of an altered distribution of actin cables. For the first time we also describe a coupling of the immunofluorescence and the quantitative cytofluorometric analyses, a new transformation parameter, since we show that SV40 transformation causes reorganization of the cell membrane by inducing the unmasking of the antigen recognized by the 4F2 monoclonal antibody, which is present in a "cryptic" form in the untransformed cells. Though the HC/SV40 cells have been continuously passaged over a 3-year period, they have not yet achieved a fully malignant phenotype, since they retain serum-dependency and the presence of a well developed fibronectin pericellular network, and they are not tumorigenic in nude mice. Thus this human immortal cell line constitutes a very useful tool for studying the progression toward full malignancy and the relationships between evolution of transformation parameters and changes in the viral and cellular genome interplay.

Adult↗
PubMed1983

The relationship between prostaglandins and virus replication: endogenous prostaglandin synthesis during infection and the effect of exogenous PGA on virus production in different cell lines and in persistently infected cells.

African Green Monkey Kidney cells were shown to normally synthesize immunoreactive PGE1. Infection of these cells with Sendai virus did not alter rates of PGE1 synthesis, while it stimulated interferon production. PGAs, that we have previously shown to be potent inhibitors of Sendai virus replication in this system, at the same dose (4 micrograms/ml), also strongly inhibited the replication of this virus in HEp-2 cells and in VERO cells, a monkey kidney cell line that does not produce interferon. PGA1 was found to be effective in several cell and virus models, suggesting a broad spectrum of antiviral actions. Finally, we confirmed the observation that PGA1-treatment prevents the establishment of a "carrier state" by Sendai virus, and PGA1-cured cells did not show any sign of persistent infection for periods as long as 110 days after Sendai infection. Attempts to cure already established persistently infected cells were only partially successful.

Alprostadil↗
PubMed1983

Can SV40 transformation reverse commitment to terminal division in human adult cells in vitro?

Adult Human Eye diploid Fibroblasts (HEF) had an extremely low growth potential in vitro (12 duplication cycles), that was identical in all the isolated clones. HEF cells were transformed with SV40 virus at the 10th duplication cycle, at which stage they were already approaching the crisis phase as demonstrated by the slowing down in the proliferation rate and the inability to produce clones. After SV40-transformation the proliferation rate rapidly increased, reaching a maximal level in a few days, and the transformed cells recovered the ability to produce clones. All the SV40-transformed isolated clones underwent 37 duplication cycles and did not show any slowing down in the proliferation rate or any sign of aging to date. We suggest that SV40 virus was able to "rescue" the cells from an irreversible commitment to cease dividing.

Adolescent↗
PubMed1982

Acquisition of sensitivity to exogenous fibronectin by Friend leukemia cells correlates with reduction of their tumorigenic potential.

Strongly adhesive, highly flattened clones (FF clones) can be selected from Friend leukemia cells (FLC) cultivated on top of monolayers of human embryonic fibroblasts (HEF). The flattened phenotype of FF clones is stable during cell replication either in soft agar or in vivo. With the number of passages of FLC on HEF the fibronectin (FN) sensitivity of FF clones increases with a proportional reduction of their tumorigenicity. The FN-sensitivity was defined as the ability of a certain dose of FN to flatten 50% of cells of a given FF clone. Tumorigenicity was defined as the number of FF cells able to give palpable tumors, in 50% of inoculated mice. Exogenous FN does not modify the duplication time of FF clones but strongly influences their growth behavior. In the presence of FN, the growth rate of FF cells is controlled by the size of the growth are available. Highly FN-sensitive FF cells grown on FN-coated substrata die at confluency while FF cells not adherent to substrata escape cell death and grow in suspension. We conclude that the high intrinsic FN-sensitivity of FF cells and FN availability at the site of tumor inoculation could be responsible for the reduced tumorigenicity of highly flattened FF clones.

Animals↗
PubMed1981

Prostaglandins of the A series inhibit Sendai virus replication in cultured cells.

Prostaglandins of the A series (PGA) were shown to be potent inhibitors of Sendai virus replication in African green monkey kidney cells in culture. This antiviral activity was specific for PGA. The effective dose (4 micrograms/ml) was not toxic to the cells and did not alter either host cell metabolism of infectivity of the virus. PGA did not affect the first stages of virus replication and seemed to act by inhibiting virus maturation and/or budding from the cells. The antiviral action of PGA was pharmacological, was not mediated by cAMP and was completely reversible. Possible mechanisms of action include post-translational binding to virus proteins or interaction with interferon.

Animals↗
PubMed1981

Electron spin resonance of growing normal and virus-transformed cells.

A g = 2.003 ESR signal, attributed to a free radical localized in HeLa cell nuclei and mitochondria but absent in membranes and cytoplasm, has been studied as a function of the culture growth cycle in normal (NRK and 3T3) and virus transformed (NRK/RSV and 3T3/SV40) cells. For both these cell pairs, the signal is higher during the "lag" stage and lower during the "growth" stage. The average specific intensity of the signal in normal cells is about twice that in virus-transformed cells. However, the maximal point of resonance during the lag state is higher in transformed cells than in normal ones. The lag stage in NRK and NRK/RSV cells is much longer than in 3T3 and 3T3/SV40 cells, while the maximal value of the g = 2.003 ESR signal occurs, early in the lag stage of 3T3 and 3T3/SV40 cells and late in the lag stage of NRK and NRK/RSV cells.

Animals↗