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T Dasdia

Publications and source records attributed to T Dasdia.

At least 19 recordsLinked to original sources
PubMed2003

Bread wheat gliadin cytotoxicity: a new three-dimensional cell model.

BACKGROUND: In an attempt to clarify the role of gliadin toxicity in the pathogenesis of gluten intolerance (celiac disease), previous in vitro studies have been based on two-dimensional human cell cultures. However, the specific morphological and biochemical properties of in vivo tissue are better maintained in three-dimensional cell cultures (multicellular spheroids, MCS). The aim of this study was to develop a three-dimensional in vitro model to investigate the effects of gliadin on epithelial cells and broaden our understanding of the early tissue damage occurring in celiac disease. METHODS: The three-dimensionally growing Lovo cell line was exposed to increasing concentrations of peptic-tryptic-digested bread wheat gliadin (from 125 to 1000 microg/mL) for 7 days in order to evaluate cell viability (colony-forming assay), and at the standard concentration of 500 microg/mL for 7 days in order to evaluate MCS diameters, volumes and cell morphology using light and electron microscopy. RESULTS: In comparison with the controls, the cell viability of the gliadin-treated MCS was significantly reduced (20-80%), but there was no difference in size. Various degrees of cell damage (autophagic vacuoles and intra-cytoplasmic lipid-like droplets) were detected by both light and electron microscopy. CONCLUSION: This is the first study investigating the effects of gliadin on MCS. Lovo MCS seem to be responsive to gliadin exposure, thus confirming previous results obtained using two-dimensional cell cultures. The data suggest that three-dimensional cell cultures may be useful in broadening our understanding of some of the early effects of gliadin peptides on epithelial cells.

Adenocarcinoma↗
PubMed2002

In vitro cytotoxic effect of bread wheat gliadin on the LoVo human adenocarcinoma cell line.

The pathogenesis of celiac disease is not completely understood but, although the initial step of the process is still unclear, an altered immune response seems to play a major role. Previous studies of the biological properties of gliadin have highlighted its cytotoxic effects, and the aim of this study was to develop an in vitro technique to study them. The LoVo (human colon adenocarcinoma) cell line grown in two-dimensional cultures was exposed to different concentrations of digested bread wheat gliadin (62, 125, 250, 500 and 750 microg/ml) for 48 h, after which cell growth and oxidative balance (the content of reduced glutathione (GSH), and peroxidase, transferase and reductase activity) was evaluated. Other food proteins were used as controls. Our data revealed a statistically significant inhibition of cell growth in proportion to the gliadin concentration (from 26 to 100%), combined with a decrease in GSH content (-38% at 500 microg/ml) and reduced enzymatic activity (-30% at 500 microg/ml). The controls did not show any noxious effect. Our results confirm the usefulness of LoVo cells in evaluating gliadin cytotoxicity and that they can be used to investigate the biological properties of gliadin.

Adenocarcinoma↗
PubMed1998

Organ culture in 3-dimensional matrix: in vitro model for evaluating biological compliance of synthetic meshes for abdominal wall repair.

A new in vitro method to evaluate the early critical interactions between synthetic prosthetic materials and growing tissues is reported. The correct spatial organization and proper cell to cell interaction required to mimic the in vivo environment was obtained in a 3-dimensional (3-D) embryo organ culture. The clot formed by plasma and chick-embryo extract provided a natural 3-D extracellular matrix that was able to support the growth and differentiation of intestinal tissue dissected from 12-day-old chick embryos. Different materials used for the repair of abdominal wall defects were taken as standards; all the prosthetic materials were devoid of any evident cytotoxic potential over a 10-day culture period, so they did not interfere with the organogenesis process. A polyglactin mesh (Vicryl) was fully incorporated into the growing tissue, but early signs of its degradation were detectable. The biologically inert materials polyethylene terephthalate (Mersilene) and polypropylene (Marlex, Prolene, and Herniamesh) retained their structural integrity when incubated with cultured tissue at 37 degrees C, and they did not hinder cellular proliferation or fibroblast migration. However, the outgrowth behavior was very different while the connective tissue invaded the interstices of the polyethylene terephthalate mesh; the explants and the migrating cells were repelled by hydrophobic polypropylene meshes. These findings are in agreement with other reported results in in vivo studies. Therefore, this method can be considered as reliable and predictable for the evaluation of biopolymers.

Abdominal Muscles↗
PubMed1997

Characterization of a clonal human colon adenocarcinoma line intrinsically resistant to doxorubicin.

Intrinsic low-level resistance to anti-cancer drugs is a major problem in the treatment of gastrointestinal malignancies. To address the problem presented by intrinsically resistant tumours, we have isolated two monoclonal lines from LoVo human colon adenocarcinoma cells: LoVo/C7, which is intrinsically resistant to doxorubicin (DOX); and LoVo/C5, which shows the same resistance index for DOX as the mixed parental cell population. For comparison, we have included in the study a LoVo-resistant line selected by continuous exposure to DOX and expressing a typical multidrug resistant (MDR) phenotype. In these cell lines we have studied the expression and/or activity of a number of proteins, including P-glycoprotein 170 (P-gp), multidrug resistance-associated protein (MRP), lung resistance-related protein (LRP), glutathione (GSH)-dependent enzymes and protein kinase C (PKC) isoforms, which have been implicated in anti-cancer drug resistance. Intracellular DOX distribution has been assessed by confocal microscopy. The results of the present study indicate that resistance in LoVo/C7 cells cannot be attributed to alterations in P-gp, LRP or GSH/GSH-dependent enzyme levels. Increased expression of MRP, accompanied by alterations in the subcellular distribution of DOX, has been observed in LoVo/C7 cells; changes in PKC isoform pattern have been detected in both intrinsically and pharmacologically resistant cells.

ATP-Binding Cassette Transporters↗
PubMed1995

Different vimentin expression in two clones derived from a human colocarcinoma cell line (LoVo) showing different sensitivity to doxorubicin.

We selected two clones, isolated from the human colocarcinoma cell line LoVo, showing a sensitivity to doxorubicin similar to (LoVo clone 5) or three times lower than (LoVo clone 7) the parental cell line. Since vimentin was atypically expressed in a human breast carcinoma cell line made resistant to doxorubicin, we looked at vimentin expression in these two clones with spontaneously different sensitivity to the drug. For comparison we used the parental cell line LoVo WT and LoVo/DX made resistant pharmacologically. mRNA for vimentin was undetectable by Northern blot analysis in LoVo WT and in LoVo clone 5, while expression of this gene was high in LoVo clone 7 and in LoVo/DX. This increase in mRNA levels was not related to an amplification of DNA, as suggested by Southern blot analysis. Immunofluorescence and immunocytochemistry findings confirmed, at protein level, the mRNA data. In LoVo clones 5 and 7, there were respectively 8.6% and 71% vimentin-positive cells, although the two clones showed similar expression of multidrug resistance gene 1 (mdr-1) and accumulated intracellular doxorubicin at similar levels. Similarly, drug efflux was the same for both clones. Our results show for the first time that cells resistant to doxorubicin express vimentin independently of the mdr glycoprotein. However when cells from clone 5 were transfected with human vimentin cDNA, they did not become resistant, indicating that vimentin can be considered as a marker of resistance in these cells but does not give rise to a resistant phenotype by itself.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Effect of low-energy laser irradiation on colony formation capability in different human tumor cells in vitro.

Fibroblasts and lymphocytes are the most widely used cells for studying the so-called biostimulative effect of low-power laser in vitro. In contrast, stimulation of cancer cells by laser light has not been investigated extensively. The present study attempted to evaluate whether or not human tumor cells could exhibit an increase in colony-forming capability following low-watt laser irradiation. LoVo and HT29 (colon carcinoma), MCF7 (breast carcinoma), M14 and JR1 (malignant melanoma) cell lines were irradiated at different doses of light delivered from an argon or an argon-dye laser. Radiant exposures between 4.2 and 150 kJ/m2 at irradiances ranging from 35 to 500 W/m2 were delivered. Results were mixed. Of the 41 experiments performed, five showed a significant statistical increase in the number of colonies (P less than 0.05), whereas three showed a decrease (P less than 0.05). Nevertheless, the trend of most data was toward an increase in colony formation, and Wilcoxon's signed-ranks test suggested that light increases tumor cell culture growth (P less than 0.03).

Breast Neoplasms↗
PubMed1987

Markedly reduced levels of anthracycline-induced DNA strand breaks in resistant P388 leukemia cells and isolated nuclei.

DNA single-strand and double-strand breaks produced by doxorubicin and two anthracycline derivatives (4-demethoxy-daunorubicin and 4'-deoxy-4'-iododoxorubicin) were measured in doxorubicin-sensitive and -resistant P388 leukemia cell lines, using filter elution methods, and compared with cellular drug accumulation to account for major differences in their cytotoxic activities and cross-resistance. The increased cytotoxic potency of the two derivatives reflects at least in part the enhanced drug accumulation by cells that results from their increased lipophilicity. However, the level of protein-linked DNA breaks was not directly related to cellular accumulation of drug analogues. It is possible that enhanced cytotoxicity may also be the consequence of the greatly enhanced ability of analogues to cause DNA strand breaks. The resistant line showed only a modest degree of resistance to both anthracycline derivatives compared with the high degree of resistance to doxorubicin. Although for all the anthracyclines tested drug accumulation was reduced in the resistant line, this did not correlate with the degree of resistance. A differential sensitivity of resistant and parental cell lines to DNA cleavage activity was consistently found for all three drugs tested. However, in contrast to a lack of effect of doxorubicin, the derivatives caused appreciable DNA strand breakage in resistant cells. The enhanced ability of these analogues to break DNA in resistant cells is consistent with the slight cross-resistance with doxorubicin. DNA double-strand breaks produced in isolated nuclei from these cells paralleled the pattern found in whole cells, thus indicating that a nuclear alteration, presumably involving DNA topoisomerases, is associated with anthracycline resistance. Our findings strongly support the hypothesis that anthracycline resistance in these cell variants may be mediated by multiple mechanisms, involving alterations of plasma membrane and changes of nuclear enzymatic activities responsible for DNA strand breaks.

Animals↗
PubMed1986

Comparison of doxorubicin-induced DNA damage in doxorubicin-sensitive and -resistant P388 murine leukemia cells.

Doxorubicin-induced DNA damage was studied in the P388 leukemia cell line and in a doxorubicin-resistant subline by alkaline elution techniques. DNA single-strand breaks and DNA-protein cross-links were determined. Whereas, in the sensitive line, 1 hr exposure to drug induced DNA damage in a concentration-dependent manner, in the resistant line only a marginal effect was observed at high drug concentrations. In contrast, elution kinetics of DNAs from cells irradiated with X-rays were similar in both lines. Although a reduced intracellular drug accumulation was found in resistant cells, this difference could not account for the marked reduction in doxorubicin-induced DNA damage. The degree of resistance of the P388 subline was reduced about 7-fold by verapamil, whereas the extent of DNA damage was unaffected. These results suggest the presence of alternative modes of resistance, independent of membrane changes, in highly resistant cells.

Animals↗
PubMed1984

Interaction of calcium ions and cAMP on the cytotoxic effect of doxorubicin.

Doxorubicin tested at the concentration of 1-2 X 10(-7)M inhibited the cloning efficiency of MS2T cells following 22 and 48 h exposure in complete medium. In the same experimental conditions the [3H]thymidine incorporation was practically unaffected. The inhibitory effect of doxorubicin on cloning efficiency appeared to be directly related with the serum concentration. In fact, this effect became more marked when the cloning efficiency was stimulated by increasing serum concentration in the cultural medium. However, this effect did not seem to be Ca2+ dependent. Similarly doxorubicin displayed a strong inhibitory effect, when the proliferative activity was stimulated by an optimal combination of cAMP and low Ca2+. On the contrary the inhibitory effect of doxorubicin was markedly reduced when the Ca2+ concentration reached the physiological value. These results confirm the direct correlation of the killing effect of doxorubicin with proliferative activity of the cells.

Animals↗
PubMed1983

Enhancement of mitogenic stimuli by phosphatidylinositol.

Phosphatidylinositol added to the medium markedly stimulated the growth-promoting effect of mitogens in normal cells (human lymphocytes and mouse embryo fibroblasts). However, it did not significantly affect quiescent cells or proliferating tumor cell lines (HeLa and MCF-7). The results are consistent with the suggested role of phosphatidylinositol in the widespread mechanism of calcium mobilization.

Adenocarcinoma↗
PubMed1983

Uptake kinetics and intracellular distribution of anthracyclines studied by laser cytofluorometry.

The detection of low amounts of anthracyclines in single cells was attained with a microscope-photometer by employing an argon laser as a fluorescence excitation source. The time course of drug uptake was followed by incubating the cells under the microscope and measuring the increase of fluorescence intensity from the beginning of the drug penetration. An intracellular distribution map of the drug fluorescence was obtained by scanning measurements, through which the more specific sites of binding were visualized. This means of detection is compared with two of the most commonly employed biochemical techniques.

Antibiotics, Antineoplastic↗
PubMed1982

Anti-tumor activity of daunorubicin linked to poly-L-aspartic acid.

Daunorubicin was bound to poly-L-aspartic acid via the methylketone side chain of the drug to avoid reaction of the sugar amino group believed to be essential for optimal drug activity. Attachment of the drug to the polyamino acid by an ester linkage was achieved by nucleophylic substitution reaction of 14-bromo-daunorubicin. Compared with free daunorubicin, the polymeric derivative was less cytotoxic to HeLa cells in vitro, but more effective against all tumor models tested (P388 leukemia, Gross leukemia, MS-2 sarcoma). The binding to the polypeptide markedly reduced drug toxicity but only slightly decreased drug potency. The daunorubicin-poly-L-aspartic acid conjugate demonstrated antitumor activity comparable to that of doxorubicin in leukemia models, but superior to that of doxorubicin in a solid tumor model (MS-2 sarcoma).

Animals↗
PubMed1977

Changes of activity of daunorubicin, adriamycin and stereoisomers following the introduction or removal of hydroxyl groups in the amino sugar moiety.

The results of a study of the effects of hydroxyl groups at positions, 2, 4 and 6 of the amino sugar on the activity of daunorubicin, adriamycin, and stereoisomers are presented. While the 4'-deoxy derivatives showed a slightly increased biological activity as compared with the parent compounds, the derivatives containing an additional hydroxyl group were less active. It is suggested that the changes in the polarity and in the DNA binding ability of these derivatives are the main factors accounting for the difference in the in vivo activity. The possible relations among the pKa values, the DNA binding properties, and the cellular uptake of the compounds are discussed with particular reference to their therapeutic effectiveness.

Animals↗
PubMed1977

Relationship between effects on nucleic acid synthesis in cell cultures and cytotoxicity of 4-demethoxy derivatives of daunorubicin and adriamycin.

Four new derivatives of daunorubicin and two new derivatives of Adriamycin characterized by the absence of the methoxyl groups at the C-4 position have been studied in cell cultures in vitro to establish structure-activity relationships. 4-Demethoxydaunorubicin was 27 to 100 times more active than was daunorubicin when inhibiting the cloning efficiency of exponential-phase HeLa cells and, like daunorubicin, was slightly active on early plateau-phase cells. DNA synthesis in mouse embryo fibroblasts stimulated by fetal calf serum was inhibited equally by the two compounds, although 4-Demethoxydaunorubicin was slightly more active than was daunorubicin when inhibiting RNA synthesis. The beta anomer of 4-demethoxydaunorubicin showed a reduced activity on HeLa cells compared to its alpha anomer, but it was equally active on DNA synthesis. The stereoisomers of 4-demethoxydaunorubicin bearing the inverted configuration in positions 7 and 9 were devoid of significant cytotoxic activity and were only slightly active on DNA synthesis at the doses tested. 4-demethoxyadriamycin and 4-demethoxy-4'-epi-adriamycin were 65 to 500 times more active than was Adriamycin on HeLa cell cloning efficiency and about 10 times more active on DNA synthesis in mouse embryo fibroblasts. Cell uptake in mouse embryo fibroblasts was also investigated for all the new derivatives tested.

Cell Survival↗