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Biomedical subjects

P Pippia

Publications and source records attributed to P Pippia.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cellular adhesion in neoplastic and syngeneic normal cells under altered gravitational conditions.

The major objective of several experiments performed in space in the last 15 years was to establish whether single cells are sensitive to gravity. It was found in certain cells that reduced gravity leads to profound changes of a number of physiological functions like genetic expression, cell proliferation, signal transduction and cytoskeleton structure. In cell biology studies microgravity can be simulated on Earth in the clinostat. Nearly all data on experiments in the clinostat are related to cells cultured in suspension and, therefore, to adhesion-independent cells. In contrast, several biological phenomena as neoplastic transformation, cell differentiation, in-vitro cellular aging, contact inhibition and cellular adhesion require mainly cellular systems that are adhesion-dependent. The purpose of this work was: a) to study the behaviour of two rat cell strains (neoplastic SGS/4A and syngeneic fibroblasts FG) in order to test whether adhesion-dependent cells are suitable for clinorotation and b) to investigate cell-cell and cell-substratum adhesion in these cells kept under simulated low-g in the fast rotating clinostat and in hypergravity at l0g in the centrifuge.

Animals↗
PubMed1998

Microgravity simulations with human lymphocytes in the free fall machine and in the random positioning machine.

The purpose of this paper is to present the results obtained in our laboratory with both instruments, the FFM [free fall machine] and the RPM [random positioning machine], to compare them with the data from earlier experiments with human lymphocytes conducted in the FRC [fast rotating clinostat] and in space. Furthermore, the suitability of the FFM and RPM for research in gravitational cell biology is discussed.

Cells, Cultured↗
PubMed1997

Channelling of deoxyribose moiety of exogenous DNA into carbohydrate metabolism: role of deoxyriboaldolase.

In bacteria, the addition of (deoxy)nucleosides or (deoxy)ribose to the growth medium causes induction of enzymes involved in their catabolism, leading to the utilisation of the pentose moiety as carbon and energy source. In this respect, deoxyriboaldolase appears the key enzyme, allowing the utilisation of deoxyribose 5-P through glycolysis. We observed that not only deoxynucleosides, but also DNA added to the growth medium of Bacillus cereus induced deoxyriboaldolase; furthermore, the switch of the culture from aerobic to anaerobic conditions caused a further increase in enzyme activity, leading to a more efficient channelling of deoxyribose 5-P into glycolysis, probably as a response to the low energy yield of the sugar fermentation. In eukaryotes, the catabolism of (deoxy)nucleosides is well known. However, the research in this field has been mainly devoted to the salvage of the bases formed by the action of nucleoside phosphorylases, whereas the metabolic fate of the sugar moiety has been largely neglected. Our results indicate that the deoxyriboaldolase activity is present in the liver of several vertebrates and in a number of cell lines. We discuss our observations looking at the nucleic acids not only as informational molecules, but also as a not negligible source of readily usable phosphorylated sugar.

Aldehyde-Lyases↗
PubMed1997

Anti-inflammatory activity of aqueous extracts and steroidal sapogenins of Agave americana.

Lyophilized aqueous extracts obtained from Agave americana L (Agavaceae) collected in the north of Sardinia were characterized with regard to their steroidal sapogenin content. Extracts of A. americana and genins isolated from them were evaluated for anti-inflammatory properties by testing their effects on carrageenin-induced edema. The effect of orally administered genins on gastric mucous membranes was also assessed. Lyophilized extracts administered by the intraperitoneal route at doses equivalent to 200 and 300 mg/kg of fresh plant starting material, showed good anti-inflammatory activity. Doses of genins (total steroidal sapogenins, hecogenin and tigogenin) equivalent to the amount in the lyophilized extracts produced an antiedentatous effect which was much stronger and more efficacious than that obtained with an i.p. administration of 5 mg/kg of indomethacin or dexamethasone 21-phosphate at a dose equivalent to the molar content of hecogenin administered. At the doses used to evaluate the anti-inflammatory activity, the genins did not have any harmful effect on the gastric mucous membranes. Lesions occurred when significantly higher doses of hecogenin were given, but gastric damage was still less than that caused by the drugs used for comparative purposes.

Animals↗
PubMed1996

Movements and interactions of leukocytes in microgravity.

The mitogenic activation of human lymphocytes resuspended in vitro is dramatically reduced in microgravity. As cell-cell contacts are one of the elements essential for activation, the behaviour of human leukocytes (mainly lymphocytes and monocytes as accessory cells) in the presence of the mitogen concanavalin A was studied in the centrifuge microscope NIZEMI at 0 x g. Aggregates (formed by intercellular bindings of membrane glycoproteins via the tetravalent alpha-glucoside ligand concanavalin A) were found at 0 x g as well as at 1 x g already 12 h after the addition of the mitogen. In general, the aggregates observed at 0 x g after an incubation time of 46 and 78 h were smaller than the corresponding aggregates in the ground control. The findings are of primary importance since they confirm the indirect evidence we had from earlier Spacelab experiments and demonstrate that cell-cell contacts are occurring also in microgravity. In addition, single cells in 0 x g show a significant higher locomotion velocity than the cells at 1 x g. The fact that the locomotion capability is not decreased during the 78-h incubation with concanavalin A provides further evidence that the cells are not proceeding through the cell cycle.

Biotechnology↗
PubMed1996

Activation signals of T lymphocytes in microgravity.

Human peripheral blood lymphocytes and monocytes were activated with concanavalin A with or without exogenous recombinant interleukin 1 (IL-1) alone or IL-1 + interleukin 2 (IL-2) under microgravity conditions to test the hypothesis that lack of production of IL-1 by monocytes is the cause of the near total loss of activation observed earlier on several Spacelab flights. The 60 min failure of the on-board 1 x g reference centrifuge at the time of the addition of the activator renders the in-flight data at 1 x g unreliable. However, the data from a previous experiment on SLS-1 show that there is no difference between the results from the in-flight 1 x g centrifuge and 1 x g on ground. The comparison between the data of the cultures at 0 x g in space and of the synchronous control at 1 x g on ground show that exogenous IL-1 and IL-2 do not prevent the loss of activity (measured as the mitotic index) at 0 x g; production of interferon-gamma, however, is partially restored. In contrast to a previous experiment in space, the production of IL-1 is not inhibited.

Biotechnology↗
PubMed1996

Static cytofluorometry and fluorescence morphology of mitochondria and DNA in proliferating fibroblasts.

The shape, distribution, and content of mitochondria in individual cells were examined during the cell cycle phases (G(0)/G(1), S, G(2) mitosis) in living human fibroblasts by static cytofluorometry and fluorescence microscopy. The morphocytochemical evaluations were performed in cell cultures submitted to double supravital fluorochrome staining with Hoechst 33342 and DiOC(6) to label DNA and mitochondria, respectively. The staining modalities were based on the stability of mitochondrial labeling. The G(1) to early S phases were characterized by the presence of filamentous mitochondria, except during the early postmitotic period. During late S, G(2), and mitotic phases, mitochondrial mass reached its highest value and mitochondria became short and numerous. During the last stage of mitosis, mitochondria were distributed among daughter cells through a cytoplasmic bridge.

Benzimidazoles↗
PubMed1995

Kinetic changes of alpha B crystallin expression in neoplastic cells and syngeneic rat fibroblasts at various subculture stages.

Alpha B crystallin, a structural at variable levels, in many extraocular tissues where it plays a protective role in stress conditions. In fact, heat or toxic shocks, as well as pathological states, increase alpha B crystallin levels in many cell types. Here we show that alpha B crystallin expression is also modulated in subcultures of rat fibroblasts and Galliera sarcoma cells. Western blots analysis with anti alpha B crystallin antibodies reveals the presence of the protein in both cell populations, although the kinetic pattern of expression is different. Galliera fibroblasts constitutively express the protein up to the 70th subculture and afterwards the synthesis ceases. On the other hand, Galliera sarcoma cells do not contain alpha B crystallin in the early stages of the culture, but there is a progressive increases between the 20th and 40th cell subculture. Differences also exist concerning the intracellular distribution: alpha B crystallin is diffusely localized in the cytoplasm of fibroblasts while in sarcoma cells it localizes mainly to the perinuclear region. Alpha B crystallin is totally recovered as soluble protein in the supernatants obtained after low speed centrifugation of fibroblast homogenates, while in sarcoma cells a portion of the protein is also recovered in the insoluble pellet. Intracellular pH measurements show an alkaline cytosol in sarcoma cells compared to fibroblasts. Heat shock treatment of fibroblast subcultures constitutively expressing alpha B crystallin induces an over-expression of the protein, while in fibroblasts whose biosynthetic capacity is lost, heat shock is unable to activate the crystallin gene. Correlation between alpha B crystallin expression and proliferative rate shows that highly proliferating fibroblasts do not express alpha B crystallin, while neoplastic cells do.

Animals↗
PubMed1994

Cytotoxicity of lazaroid U-75412E in human epithelial cell line (Wish).

The 21-aminosteroids (or lazaroids) are a recently synthesized class of compounds demonstrated to protect tissue against damage induced by trauma and/or ischemia. Currently, very little is known about the biological effects of lazaroids. In this work the action of lazaroid U-75412E on a human epithelial cell line (Wish) was evaluated. The data obtained showed an inhibition of cell growth and a dose- and time-dependent decrease of cell viability. Furthermore, a dose- and time-dependent increase of cells in the G2/M phase with the appearance of apoptotic cells was observed by flow cytometric analysis. Nuclear fragmentation was also evident. Lactate dehydrogenase release and scanning electron microscopy experiments suggested that plasma membrane integrity was altered by this compound. The immunofluorescence technique and transmission electron microscopy images also showed intracellular damage, such as alteration of microtubular arrangement, mitochondrial swelling and the presence of vacuoles. This study demonstrated that 1 microM U-75412E was unable to modify these parameters, while higher concentrations (6-75 microM) had a cytotoxic effect on Wish cells.

Antioxidants↗
PubMed1993

[Various nuclear and cytoplasmic parameters in relation to the evolution of an in vitro culture of rat fibroblasts].

A cytokinetic study was performed on progressive subcultures of a cellular strain represented by fibroblasts (FG: Fibroblasts Galliera). Our previous studies on these cells showed morphofunctional changes in relation to cell ageing, indicating the stabilization of a cell line with high proliferative capacity. Furthermore, in the present work, we carried out a comparative analysis with a neoplastic strain (SGS/3A cells), characterized by a low state of cell differentiation. The morphological (fluorescence microscopy) and quantitative (flow cytometry) analysis, examined the relative DNA/protein and DNA/RNA ratios. Moreover, the replicative and mitotic activity and the apoptotic degeneration was determined. The results obtained indicated the existence in this biological model of a different relation between cell growth and cell proliferation. The analysis of our results allowed us to hypothesize that the cellular subpopulation selected during the culture progression of FG cells constitutes a cell line highly able of survival in vitro. In these cells the high proliferative activity is opposite to a reduced metabolism.

Animals↗
PubMed1992

Modifications of adhesion properties and proteoglycan structure in rat embryo fibroblast cultures with increasing passages.

Adhesion properties of rat embryo fibroblast cultures and proteoglycans (PGs) produced both in the growth medium and in the cell layer were investigated with increasing passages. Both cell-cell and cell-substrate adhesion increased with increasing subculture number. Cell adhesion properties were improved by cell treatment with chondroitinase ABC. The increase in subculture number was coupled with a constant increase of PG molecular size, which was particularly evident in cell layer extracts. The ratio HS-PGs/DS-PGs increased with increasing passages. PG modifications are likely to represent evidence of changes in extracellular matrix organization and could play a role in the increase of cell adhesion properties.

Animals↗
PubMed1991

[Cell adhesion in neoplastic cells and syngeneic fibroblasts of the rat: effect of progesterone and estradiol].

Recent advances in the study on the importance of steroid receptors in the treatment of hormone-responsive tumors established the relationship between plasma membrane and the first steps of the cellular response to the endocrine stimulus. We have therefore found interesting to study the influence of estrogen and progesterone on cell adhesion of neoplastic (SGS/3A) and normal syngeneic (FG) cells. We demonstrated the presence of a nuclear estrogenic and a cytosolic progestin receptor in the SGS/3A cells. In syngeneic fibroblasts both receptors are absent. Cell adhesion kinetics obtained determining the percent of single labeled cells with 3H-leucine adhering to confluent monolayer (cell-cell adhesion) showed that the physiological concentrations of estradiol and progesterone induce an inhibition of cell-substratum adhesion (25-30%) in neoplastic cells, but do not influence cell-cell adhesion. In FG cells the two hormones cause an increase of cell-substratum adhesion (35-40%), but do not influence cell-cell adhesion. Results suggest that FG cells, although lacking cytoplasmic or nuclear receptors for estradiol and progesterone, probably have other steroid-receptive molecules involved in adhesive processes on their cell-surface.

Animals↗
PubMed1991

[Estrogen receptor levels in the liver of intact and gonadectomized rats and in cultured hepatocytes].

The concentrations of hepatic estrogen receptor were determined in intact and gonadectomized male and female rats. The hydroxylapatite assay demonstrated that the ablation of gonads induces, in the liver, an increase of estrogen receptors. The data obtained suggests that the synthesis of these receptors in the liver might be estrogen- and androgen-dependent. The same analysis performed on hepatocyte cytosol, derived from ovariectomized females, and cultured for 24, 48 and 72 hours, showed that time of culture is an important factor in determining a decrease of estrogen receptor concentrations in the cells. The results obtained allowed us to conclude that in the maintenance of the normal levels of the hepatic estrogen receptors, either sexual and non-sexual hormones are involved.

Animals↗
PubMed1990

[Effect of dimethyladipimidate and dimethylsuberimidate on cell-cell adhesion in rat fibroblasts].

In a study performed to identify the molecular mechanisms which regulate cell to cell adhesion and contact inhibition in neoplastic and syngeneic normal cells of the rat we have observed that the adhesive capacity depends on the reagents used, either EDTA or trypsin, to release the cells from monolayer. Taking profit of this last property and of the possibility of blocking free -NH2 groups on membrane proteins with specific cross-linking reagents "in vitro", we have studied in this work the behaviour of the proteins of the cell coat involved in cell to cell adhesion of rat fibroblasts FG/2. The cross-linking reagents used were dimethyladipimidate (DMA) and dimethylsuberimidate (DMS). The cells were exposed to the reagents at 0 degrees C for 30'. Cell to cell adhesion was measured by determining the percentage of single cells labeled with 3H-leucine, adhering to a confluent monolayer at different incubation times. The inhibitory effect on cell to cell adhesion brought about by cross-linking reagents indicates that a) EDTA-released cells are more sensitive to both imides than those released with trypsin, b) DMA is more effective on trypsin-released cells and c) DMS is more effective on EDTA-released cells. Therefore, we conclude that the inhibition of adhesion by reaction with the two cross-linking reagents is more likely due to a stiffening of the molecules of the cell coat involved in the adhesion, rather than to the modification of -NH2 residues which should specifically participate to adhesive process.

Animals↗
PubMed1989

[Cell adhesion in rat fibroblasts: effect of tumor promoters].

In a study performed on transformed (SGS/3A) and normal syngeneic rat cells (FG/2) to identify the molecular mechanisms which regulate cell adhesion and contact inhibition in cell transformation, we investigated the effects of tumor promoters on cell to cell adhesion of rat fibroblasts. As tumor promoters we used 12-tetradecanoyl-phorbole-13-acetate (TPA) and the melittin, a polypeptide from bee venom, both substances capable of stimulating the neoplastic transformation. The intercellular adhesion assay consists in determining the percent of single cells labeled with 3H-L-leucine adhering to a confluent monolayer of unlabeled cells at different incubation times. The increase of cell-cell adhesion caused by TPA and melittin confirms what we have constantly observed in other experiments, i.e. that neoplastic cells SGS/3A always have a higher intercellular adhesion capacity than corresponding normal syngenic cells FG/2. Since one of the effects of the tumor promoters is also induction of a reversible alteration of the cytoskeleton, it is likely that their action on intercellular adhesion is regulated by a mechanism analogous to that proposed for explaining the increased intercellular adhesion observed after treatment with antimicrotubular compounds.

Animals↗