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Biomedical subjects

S C Barranco

Publications and source records attributed to S C Barranco.

At least 55 records · Page 3Linked to original sources
PubMed1983

Establishment and characterization of an in vitro model system for human adenocarcinoma of the stomach.

Ten permanent clones derived from a single biopsy specimen of an untreated human adenocarcinoma of the stomach were established and characterized in vitro. Tissue culture growth properties, doubling times, plating efficiencies, growth fractions, cell cycle phase distributions, DNA indices, modal chromosome numbers, and ploidies were determined. Growth fractions were nearly 100%, and doubling times ranged from 23 to 37 hr. The plating efficiencies were generally high for tumor cells in culture, ranging up to 70%. Modal chromosome numbers varied from 45 to 48, with a wider range of variability in about 25% of the cells studied in each clone. In addition, the parent cell line (from which the clones were isolated) was shown to grow in athymic mice and to have the same histochemical and cytological characteristics as the specimen taken from the patient. It is important to characterize human tumor cells in vitro in this detailed manner, since they serve as excellent model systems for other studies involving the heterogeneous responses to drugs and radiation. The identification of mechanisms of drug sensitivity and resistance and the testing of drug and radiation combination treatment schedules in such in vitro systems can provide valuable insight into the design of clinical protocols for treatment of stomach cancer in humans.

Adenocarcinoma↗
PubMed1982

Enhanced cell killing through the use of cell kinetics-directed treatment schedules for two-drug combinations in vitro.

Kinetics-directed drug treatment schedules were tested in Chinese hamster ovary cells. Ten hr after treatment with 1,2:5,6-dianhydrogalactitol (DAG) (at a dose lethal to less than 5% of the cells), a 150% enrichment of cells into the S phase of the cell cycle was observed. This blockade in S phase was reversible and was followed at 18 hr after an exposure to DAG by a 200% increase in the fraction of cells in the G2-M phases of the cell cycle. Bleomycin, known to be most effective against G2 + M cells, had the greatest effect on cell killing when administered at that time. Rapid analysis by flow microfluorometry techniques was used to determine the DAG-induced kinetics changes, thus allowing treatment with the second drugs at the most opportune time. The DAG-induced kinetics changes were also demonstrated in a line of human adenocarcinoma of the stomach in vitro and in Ehrlich ascites tumor cells in vivo. In all cases, the enrichment of cells into S phase was reversible at the doses used and was followed by a reversible blockade in G2-M.

Adenocarcinoma↗
PubMed1982

Use of 1,2:5,6-dianhydrogalactitol in studies on cell kinetics-directed chemotherapy schedules in human tumors in vivo.

Recently, it has been shown that 1,2:5,6-dianhydrogalactitol (DAG) can cause reversible alterations in cell cycle kinetics. Following treatment of CHO cells in vitro and Ehrlich ascites tumor cells in vivo, significant increases in the fraction of cells in S phase were observed to occur, and this was followed by an increase in the fractions of cells in G2 and mitosis. Treatments with S or G2-M phase-specific drugs at the peak enrichment times after DAG was given resulted in greater cell kills than when given by any other schedule. We have extended these kinetics-directed drug schedule studies to human tumors in vivo. The first phase was to determine whether DAG could be used to perturb cell kinetics in vivo as effectively in patients as it was in vitro. In 14 of 17 tumors studied, increases in the S-phase fractions were observed (ranging from 30 to 240% increases). The hr at which the S-phase peaks were observed (post-DAG treatment) was variable among the patients and among the tumors studied. However, this points out the value of obtaining actual cell kinetics data from serially biopsied tumors growing on the body surface and illustrates the importance that these data may have in helping to select an optimal time at which to give an S phase-specific drug. If such tumor cell kinetics-directed scheduling is ultimately shown to be effective, it will represent a means of individualizing therapy for a large fraction of tumor patients whose tumors are growing on or near the surface of the body. The tumors utilized in these studies were squamous carcinomas of the head and neck, skin, anus, and cervix; adenocarcinomas of the breast and rectum; and malignant melanoma. The second phase of this study will be to determine the tumor responses in patients treated with such kinetics-directed schedules.

Adenocarcinoma↗
PubMed1981

Changes in DNA distributions and ploidy of CHO cells as a function of time in culture.

Chinese hamster ovary (CHO) cells maintained in continuous culture for 3 to 5 months may undergo subtle changes in drug sensitivity response, growth kinetics, plating efficiencies, et cetera. Our studies done independently in two different laboratories, using flow cytometry, indicate that the DNA histogram patterns change at about 11 wk, from populations with an approximate diploid DNA content to populations also composed of triploid and tetraploid cells. Chromosome counts also change from distributions of 21 to 22 to populations of cells having 21 to 22, 34 to 35 and 44 to 46 chromosomes. These alterations occur earlier (at 8 to 9 wk) in cell populations previously treated with anticancer drugs.

Animals↗
PubMed1980

Time-dependent changes in drug sensitivity expressed by mammalian cells after exposure to trypsin.

Immediately after a 5-minute exposure to 0.025% trypsin, Chinese hamster ovary cells treated with anticancer drugs exhibited changes in drug sensitivity. Depending on the drug, cells immediately became more sensitive, less sensitive, or showed no change in sensitivity at all. The deviation from normally expected survival values ranged from fourfold to fifty-fold and varied with time (of drug treatment) after trypsinization. By the 12th hour post trypsinization, the drug survival responses had returned to values obtained with untrypsinized cells.

Animals↗
PubMed1979

A simple method for producing different growth fractions in vitro for use in anti-cancer drug studies.

A simple technique has been used experimentally to produce in vitro Chinese hamster ovary cells with growth fractions ranging from 0 to 100%. Known numbers of exponentially growing and plateau-phase tissue culture cells were mixed in various proportions to yield the desired final growth fraction. Cells attach to the culture flask surface within 1 hr of mixing. Treatment at that time with the nitrosourea compounds, CCNU and MeCCNU, resulted in differential drug survival sensitivities that were dependent upon the growth fraction of the population treated.

Animals↗
PubMed1978

Cell killing and kinetic effects of diglycolaldehyde on dividing and nondividing mammalian cells in vitro.

The effects of the anticancer drug diglycolaldehyde (NSC-118994) were studied on Chinese hamster ovary cells growing in vitro. Dividing cells, specifically those in S-phase, were more sensitive to the drug than were nondividing cells, although a large fraction of nondividing cells was also killed by doses up to 800 microgram/ml. Dose-dependent effects on cell progression kinetics were observed in all phases of the cell cycle except in mitosis, during which treated cells progressed at control rates into G1-phase. The inhibition of cell progression from G1- into S-phase (most sensitive phase of the cell cycle) put self-limiting restrictions on the cell killing effects of the drug.

Aldehydes↗
PubMed1978

Differential sensitivities of five rat hepatoma cell lines to anticancer drugs.

Five permanent tumor cell lines derived originally from either a solid or an ascites biopsy of rat hepatoma exhibited differential sensitivities to bleomycin, Adriamycin, 1-beta-D-arabinofuranosylcytosine, hydroxyurea, 1-trans-(2)-chloroethyl)-3-(4-methoylcyclohexyl)-1-nitrosourea, and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea. The cells were least sensitive to hydroxyurea and 1-beta-D-arabinofurano-sylcytosine, with some cell lines being almost totally resistant to these drugs. However, from 25- to 700-fold differences in survival were obtained between cell lines treated with either bleomycin or Adriamycin.

Animals↗
PubMed1977

Cell killing, kinetics, and recovery responses induced by 1,2:5,6-dianhydrogalactitol in dividing and nondividiing cells in vitro.

The survival and cell kinetics effect of 1,2:5,6-dianhydrogalactitol, NSC-132313 (galactitol), were studied on mammalian cells. Nondividing or plateau-phase cells were almost two times more sensitive to galactitol than were cells treated in the dividing state (dose required to reduce survival by 63% on the exponential part of the survival curve (DO)=4.2 mug/ml/hr for dividing cells vs. DO=2.4 mug/ml/hr in nondividing cells). The survival curves were characterized as having shoulder regions, followed by exponential decreases in survival as the drug doses were increased above 12 mug/ml for 1 hour. Synchronized mitotic and G1 phase cells were equally sensitive to galacitol, with approximately 90% of the cells killed by 1-hour exposures to 12.5 mug galactitol/ml. Cells in early S phase were the least sensitive to this drug dose (survival greater than 20%); however, the cells became more sensitive as they progressed through the S phase and into the G2 phase. There were no large differences observed in survival sensitivities anywhere in the cell cycle, suggesting that galactitol was not a cell-cycle phase-specific agent. Cells in mitosis or G1 phases of the cell cycle at the time of treatment with galacitol progressed normally into the next stage of the cell cycle; however, cells exposed to galactitol in S or G2 phases exhibited dose-dependent delays in those phases of the cell cycle. Nondividing cells exposed to high doses of galactitol could not recover from potentially lethal damage (PLD); however, nondividing cells exposed to lower galactitol doses (lethal dose to 10% of the cells) did exhibit slight recovery from PLD. Dividing cells did not recover from PLD at any of the doses tested. Both dividing and nondividing cells were more sensitive (cell kill) to galactitol when it was administered in two dose fractions 4-8 hours apart than when the same total integral dose was given as a single exposure. A 25-50% greater cell kill was achieved in nondividing cell populations given two dose fractions versus a single exposure to galactitol. Up to 60% greater cell kill was obtained with fractionalated doses in dividing cell populations. These responses to fractionated dose treatments were also dose-dependent.

Cell Division↗
PubMed1977

Inhibition of recovery from bleomycin-induced potentially lethal damage.

Mammalian cells are able to recover from bleomycin (Bleo)-induced potentially lethal damage. We examined the influences of inhibitors of DNA, RNA, or protein synthesis on that recovery. Cytosine arabinoside and cycloheximide did not inhibit recovery from Bleo-induced damage; however, actinomycin D (Act D) did inhibit it. At a dose that produced minimal cell killing and inhibited only RNA synthesis, inhibition of recovery by Act D was immediate and complete.

Antimetabolites↗
PubMed1977

Cell cycle time determinations based on liquid scintillation counting of 3H-TdR labeled mitotic cells.

Following a 10 min pulse labeling with 3H-TdR, flasks of asynchronous monolayer cultures of Chinese hamster ovary cells were subjected to mitotic selection at 2 hr intervals. The mitotic index of the selected populations was always greater than 90%. Counts per min per cell obtained by liquid scintillation counting were plotted versus time after the pulse label. Comparisons were made between cycle times obtained by the mitotic-scintillation counting method and by the standard per cent labeled mitosis technique. The resulting curves were used for calculations of the cell cycle times and the lengths of G1, S, G2 and M phases of the cell cycle. There was less than 2% difference in the cell cycle times obtained using the scintillation method as compared to times calculated from autoradiographic data obtained from individual petri dishes. The mitotic-scintillation counting technique is simple, accurate and rapid and allows the calculation of the cell kinetics parameters within 1 hr of the end of the experiment.

Autoradiography↗
PubMed1977

Cell cycle phase recovery from bleomycin-induced potentially lethal damage.

Mammalian cells treated during mitosis with the anticancer drug bleomycin cannot recover from potentially lethal damage. G1- and S-phase cells treated in a similar manner can recover. In synchronized G1- and S-phase cells, and in asynchronous and nondividing populations, the final survival values of recovered cells have always been found to be greater than 0.2. These data suggest that a certain fixed amount of recovery can occur, regardless of the degree of initial bleomycin-induced damage. The mechanism of this particular phenomenon is unknown.

Bleomycin↗
PubMed1976

Differences in the incorporation of thymidine into DNA of normal and cystic fibrosis fibroblasts in vitro.

Although similar fractions of cells were in the S phase of the cell cycle, normal human skin fibroblasts were shown to incorporate more than twice the 3HTdR into their DNA in vitro than did cells obtained from individuals with cystic fibrosis (CF). Obligate heterozygotes incorporated an intermediate amount of the DNA precursor. Studied were initiated to determine the basis of the differential incorporation of 3HTdR among the genotypes. An analog of thymidine, BUdR, produced varied effects on the growth kinetics of the three genotypes. The growth of cells in BUdR resulted in a 50% increase in the population doubling times of all three genotypes, and caused the cell morphology to change from a spindle shape to one in which the cells became broadened and flat, with numerous cytoplasmic projections extending for distances of several cell diameters. The activities of thymidine kinase and the participation of the exogenous and de novo pathways in the synthesis of TMP were found to be approximately the same in all three genotypes. The data suggest that an alteration in the transport of thymidine into the cells may account for the differences in TdR incorporation into DNA, and this may be associated with other changes in cystic fibrosis that are apparently membrane associated.

Bromodeoxyuridine↗
PubMed1976

Modification of the response to actinomycin D-induced sublethal damage by simultaneous recovery from potentially lethal damage in mammalian cells.

Exponentially growing cells and cells that were allowed to enter a plateau or nondividing state of growth by depleting the medium of growth-essential nutrients were used in these studies. Nondividing Chinese hamster ovary cells in vitro are less sensitive to actinomycin D (AMD) than are exponentially growing cells. The cells were tested for their ability to recover from AMD-induced potentially lethal damage (PLD) or sublethal damage. The proliferating and the nonproliferating cells do not recover from PLD or sublethal damage, and they experience further reductions in survival when they are maintained under the medium conditions of their respective growth states. However, when dividing cells are placed in conditions suboptimal for growth (incubated in depleted plateau medium after treatment with AMD), they did exhibit increased survival. The PLD recovery was so great under these conditions that it masked the true response of the cells to fractionated doses of AMD. When adjustments were made for the PLD recovery, the resulting data indicated a slight but measurable increase in survival. Since AMD inhibits cell progression in all stages of the cell cycle, this increase in survival observed with fractionated doses of AMD may be due to true recovery from sublethal damage, although the movement of cells into less sensitive stages of the cell cycle between treatments cannot be ruled out.

Cell Survival↗
PubMed1976

Response of mammalian cells to bleomycin-induced potentially lethal and sublethal damage.

Both dividing and nondividing cells were able to recover from bleomycin-induced potentially lethal damage, but not from sublethal damage. The recovery from bleomycin-induced potentially lethal damage by nondividing cells was twice as great as that exhibited by dividing cells; and, potentially lethal damage recovery was sufficiently high for cells in both growth states to conceal the true response to sublethal damage. Through the use of integral dose fractions of bleomycin, the recovery from potentially lethal damage can be reduced significantly. These data suggest that closely spaced treatments with fractionated doses of bleomycin may be a more effective means of eradicating tumors containing large nondividing cell populations in vivo.

Animals↗
PubMed1976

Electron microscopy and microchemical analysis of cystic fibrosis diploid fibroblasts in vitro.

Fibroblasts derived from cystic fibrosis homozygotes and heterozygotes were compared to normal fibroblasts topologically, ultrastructurally, and microchemically. Topological examinations, by means of scanning electron microscopy (SEM) revealed no significant differences between the 3 genotypes surveyed. The cells were generally flattened and/or fusiform structures that were more or less devoid of surface details. However, the dividing cells, in all of the populations surveyed, were found to have a more or less spherical configuration involving a highly complicated surface. The surface manifestations included blebs, ridges, and microvilli. Representative samples of the cells in all stages of growth, lag phase, exponential phase, and plateau phase, were surveyed in this study. Ultrastructurally, the fibroblasts of the 3 genotypes were found to have similar cytological detail. Highly infolded nuclei, distinct organelle components, and surface details, also seen in the SEM study, were observed. Numerous bundles of microfilaments were noted within the cytoplasm. Metachromatic granules were observed in cells from all 3 genotypes. Microchemical analysis, by means of energy dispersive X-ray analysis, demonstrated slight but recognizable differences in the elemental composition of the 3 genotypes. Of notable interest were the peak intensities of calcium and sulfur. The CF homozygous cells presented higher values for both of the elements when compared to the values observed in the CF heterozygous and normal cell populations. Although consistent differences could be observed in the CF genotypes when compared to the non-CF cells, no attempt was made to quantitate the concentrations of each of the elements within the cells.

Adult↗
PubMed1976

Review of the growth characteristics of cystic fibrosis and normal human diploid fibroblasts in vitro.

The growth kinetics of human diploid skin fibroblasts derived from cystic fibrosis (CF) homozygotes, CF heterozygotes and normal individuals was determined. The population doubling times increased with time in culture, and no difference was observed between the 3 genotypes tested. The cell cycle times remained constant through the 10th subculture, while the growth fraction, or fraction of cells in the cell cycle, decreased with culture time; however, changes in the growth fraction and population doubling time appear to be related to cellular senescence in vitro rather than to cystic fibrosis.

Cell Division↗