Biomedical subjects

F Cortés

Publications and source records attributed to F Cortés.

At least 55 records · Page 3Linked to original sources

PubMed1994

Differences in the adaptive response to radiation damage in G0 human lymphocytes conditioned with hydrogen peroxide or low-dose X-rays.

We have carried out experiments to study the adaptive response in G0 human lymphocytes conditioned with either hydrogen peroxide or low-dose X-rays and challenged with 1.5 Gy of X-rays after stimulation. Peroxide conditioning treatment was given at different times before stimulation, while the low-dose irradiation was delivered at different dose rates just before stimulation of lymphocytes. A protective effect of pre-exposure to H2O2 against radiation damage detected as micronuclei in binucleated cells was evident, regardless of the time of conditioning treatment during G0. For low-dose-irradiated cells, on the other hand, the adaptation observed seemed to depend upon the dose rate, and never reached the extent observed in cells treated with peroxide.

Adaptation, Physiological↗

PubMed1994

Cell interactions in the control of size in Drosophila wings.

The vein locus (vn) includes lethal alleles (designated also defective dorsal discs) that prevent growth of dorsal discs and in viable genetic combinations reduce the number of cells of the adult wing. Those effects are prominent in genetic mosaics. Cell proliferation is reduced in all regions of the wing blade in a local autonomous way. These effects are more extreme when mutant clones occupy full intervein regions bordering veins. Clones have, in addition, nonautonomous effects (accommodation) in the proliferation of wild-type cells of the same wing. These effects are more extreme in double mutant vn (ddd) and ve (rhomboid) allelic combinations. Developmental analysis shows that cell proliferation stops earlier in larval development the stronger the vn allele considered. A model is discussed of how cell proliferation is controlled by cellular interactions.

Aging↗

PubMed1994

Evidence that SCEs induced by mutagens do not occur at the same locus in successive cell cycles: lack of cancellation in three-way stained CHO chromosomes.

An approach based on the synchronization of CHO cells after a first cell cycle incorporating a relatively low amount of bromodeoxyuridine (BrdUrd) into DNA, followed by mutagenic treatment and subsequent culture for second and third generations of BrdUrd incorporation for the scoring of sister chromatid exchanges (SCEs) per cell cycle in three-way differentially (TWD) stained chromosomes, has been used to investigate the possible cancellation of SCEs. Cancellation is expected to occur if two mutagen-induced SCEs occur at exactly the same site in subsequent rounds of replication. Lesions in DNA seem to persist and are able to induce SCE throughout two cell cycles after treatment with the three mutagens tested--mitomycin C (MMC), ethyl methanesulfonate (EMS) and ultraviolet (UV) light--though this latter agent was shown as only moderately persistent. Our results seem to indicate that SCEs induced by these mutagens do not take place at the same locus in successive cell generations, as assessed by a lack of SCE cancellation.

Animals↗

PubMed1994

Exogenous catalase introduced in CHO cells by electroporation does not protect against chromosome damage induced by ionizing radiation.

The relative importance of hydrogen peroxide generated as a consequence of irradiation with X-rays for the production of chromosomal aberrations has been studied in cultured CHO cells. Catalase introduced into cells by electroporation protected DNA from strand breakage induced by hydrogen peroxide given 4h later, and the yield of chromosome aberrations was also reduced. Nevertheless, when the cells were irradiated after treatment with catalase following a similar protocol and the yield of chromosomal aberrations analyzed at metaphase, no protective effect was observed as compared with cells treated with X-rays alone. These observations seem to support the hypothesis that hydroxyl radicals generated from hydrogen peroxide are not a major factor responsible for chromosome damage induced by ionizing radiation.

Animals↗

PubMed1994

Synergistic effect of inhibitors of topoisomerase I and II on chromosome damage and cell killing in cultured Chinese hamster ovary cells.

Simultaneous treatment of cultured Chinese hamster ovary cells with the topoisomerase I inhibitor camptothecin and the topoisomerase II inhibitor 4'-(9-acridinylamino)-methanesulfon-m-anisidide results in a clear synergistic effect on both chromosome damage detected at metaphase and loss of colony-forming ability. In contrast, the effect of combined treatment with these topoisomerase inhibitors on sister chromatid exchanges was not significantly different from that expected if the effects were additive. Taken as a whole, these results seem to support the hypothesis that topoisomerase inhibitors can lead to cell death, presumably when DNA replication forks collide with drug-stabilized cleavable complexes. Nevertheless, no evidence of apoptosis was obtained from DNA fragmentation analysis. The possible clinical implications of our findings are discussed.

Amsacrine↗

PubMed1994

[Subdural hemorrhage of aneurysmal origin].

Although most subdural hematomas are considered to be venous in origin, they may also be of arterial origin. When subdural bleeding is due to the rupture of an intracranial aneurysm, most commonly at the middle cerebral or internal carotid arteries, the amount of subdural blood is usually small and of no clinical importance. We describe two patients with subdural hematomas secondary to rupture of an intracranial aneurysm, who needed prompt surgical treatment. The first patient had a left internal carotid artery aneurysm at the origin of the ophthalmic artery. In the second patient the aneurysm was at the anterior communicating artery and rebled into the subdural space directly through a right intraparenchymatous frontobasal hematoma. The most probable mechanism of subdural bleeding in our two patients was the existence of adhesions between the aneurysm and the arachnoid due to previous minor hemorrhages. The indication of cerebral angiography in a patient with subdural hematoma is based mainly upon the existence of meningeal signs, the presence of blood in more than one intracranial compartment or the rapid progression of bleeding.

Aged↗

PubMed1993

[Nutrition in pregnant women: a study of dietary habits in two base health areas].

OBJECTIVE: To analyse the dietary habits of pregnant women in two base Health areas and to propose modifications in any damaging patterns found. DESIGN: A descriptive study of a crossover type using weekly dietary questionnaires on food consumption and a 24-hour record. SETTING: Almanjayar and Cartuja Health Centres in Granada. PARTICIPANTS: Pregnant women being monitored at the Health Centres who were chosen by randomized sampling (N = 52). MEASUREMENTS AND MAIN RESULTS: We studied the following variables: total energy consumption; intake of carbohydrates, lipides, proteins, fibre, Ca, Mg, Zn, Fe and hydrosoluble and liposoluble vitamins. Average energy consumption was 2516 Kcal per day, although 14.46% of the pregnant women consumed less than 2200 Kcal and in 9.6% average consumption was below 1800 Kcal per day. The energy percentages of total consumption are excessive in the case of proteins (21%), lightly increased in Carbohydrates (51.8%) and acceptable in Lipides (27.2%). In the following there were notable intake deficiencies: Ca (69%), Fe (38.4%), Mg (53.8%), Vit D (49.7%), Folic Acid (81%) and Fibre (33%). On the question of how often food was consumed, we should note the scant consumption of vegetables and alcohol and excessive consumption of refined Carbohydrates. CONCLUSIONS: There are no big nutritional imbalances. The following are necessary: to maintain energy intake between 2200 and 2600 Kcal per day; to find a new equilibrium between animal and vegetable protein consumption, to diminish the intake of complex and refined Carbohydrates and to increase the intake of Fe, Ca, Folic acid and Vitamin D.

Cross-Sectional Studies↗

PubMed1993

Cytogenetic effects of inhibition of topoisomerase I or II activities in the CHO mutant EM9 and its parental line AA8.

The possible relationship between topoisomerase activities and the occurrence of SCE and chromosomal aberrations was investigated in the CHO ethyl methanesulfonate-sensitive mutant EM9 and its parental line, AA8. The Topo II inhibitor m-AMSA induced fewer SCE in EM9 than in AA8, mainly when given during the first S period. When the Topo I inhibitor camptothecin was used, it showed a higher efficiency to induce both chromosomal aberrations and SCE in EM9 than in AA8. The impact of BrdU incorporated into parental DNA on topoisomerase activity was tested using nuclear extracts from both EM9 and AA8 assayed for their ability to decatenate kinetoplast DNA by Topo II and to relax supercoiled plasmid DNA by Topo I. Taken as a whole, the results seem to indicate that there are differences between the two cell lines, consistent with the hypothesis put forward by other investigators that topoisomerases are involved in the molecular mechanism of SCE.

Amsacrine↗

PubMed1993

Higher G2 sensitivity to the induction of chromosomal damage in the CHO mutant EM9 than in its parental line AA8 by camptothecin, an inhibitor of DNA topoisomerase I.

The induction of chromosomal alterations by camptothecin (CPT), an inhibitor of DNA topoisomerase I, in the G2 stage was studied in a CHO mutant cell line EM9, which has an elevated baseline frequency of SCEs, and in its parental cell line AA8. EM9 cells were found to be more sensitive to CPT than the parental cell line. It is proposed that the effect of camptothecin in this phase of the cell cycle is caused by a 'residual' DNA synthesis which is higher in EM9 than in AA8 cells.

Animals↗

PubMed1993

Abnormally high incidence of SCE in three successive cell cycles in the CHO mutant EM9 as detected by a three-way immunoperoxidase differential staining.

A high resolution three-way immunoperoxidase method for the detection of SCE per cell generation in chromosomes with very low levels of BrdU in DNA has been recently standardized in our laboratory. We have made use of this methodology to assess whether the CHO mutant EM9 is solely hypersensitive to BrdU incorporated into template DNA as regards the extraordinarily high SCE frequency observed as compared with its parental line, AA8, or also shows an elevated spontaneous frequency of exchanges. Our results confirm the importance of BrdU incorporated for SCE in EM9 but also show that the estimated yield of spontaneous SCE is about 10 times higher in this mutant than in the parental line, AA8.

Animals↗

PubMed1993

Adaptive response to radiation damage in human lymphocytes conditioned with hydrogen peroxide as measured by the cytokinesis-block micronucleus technique.

We have made use of the cytokinesis-block micronucleus method to evaluate the adaptive response in human lymphocytes from two donors conditioned with low doses of hydrogen peroxide before irradiation with either 1.5 or 3.0 Gy of X-rays. A protective effect of pre-exposure to H2O2 against radiation damage detected as micronuclei in binucleate cells was evident in cells allowed to recover for different periods after X-ray exposure, though cells challenged with 3.0 Gy of X-rays showed the adaptive response at later fixation time than those exposed to the lower dose (1.5 Gy). We propose this protocol as an interesting alternative to the single fixation method to score chromosomal aberrations at metaphase for the study of the adaptive response.

Adaptation, Physiological↗

PubMed1993

Importance of replication fork progression for the induction of chromosome damage and SCE by inhibitors of DNA topoisomerases.

Previous studies have shown the importance of DNA replication fork progression for the cytotoxicity of topoisomerase inhibitors. Nevertheless, while it was concluded that an interference of moving forks with drug-stabilized topo I-DNA complexes is critical for cell death, in the case of topo II only a partial contribution to cell killing was proposed. We have studied the influence of inhibition of DNA replication by aphidicolin on the production of chromosomal aberrations and SCE by topoisomerase inhibitors. Our results seem to indicate that fork progression is necessary for both cytogenetic endpoints. Pulsed field gel electrophoresis also confirmed this conclusion at the level of DNA breakage (double-strand breaks) efficiently induced by m-AMSA treatment alone, but not when aphidicolin was present. Differences found between topo I and topo II inhibitors (camptothecin and m-AMSA, respectively) could be explained as due to differences in their persistence in trapping the 'cleavable complex'.

Amsacrine↗

PubMed1993

Poly-D-lysine enhances the genotoxicity of bleomycin in cultured CHO cells.

Cultured CHO cells were treated with the radiomimetic antitumor agent bleomycin (BLM) and post-treated with the polycationic compound poly-D-lysine (PDL), recently reported by us as able to potentiate chromosome damage induced by X-rays and chemical mutagens in both plant and mammalian cells. Our results seem to indicate that PDL enhances the genotoxic action of BLM measured as induced chromosomal aberrations, colony-forming ability and DNA strand breakage. Taking into account the reported low efficiency of BLM treatment due to problems with cellular uptake, enzymatic degradation and efficient repair, the possibility of optimizing the dose-effectiveness for cancer therapy is discussed.

Animals↗

PubMed1993

Three-way differentiation of Chinese hamster ovary chromosomes by immunoperoxidase technique using a monoclonal anti-bromodeoxyuridine antibody.

A new permanent staining procedure for sister chromatid differentiation (SCD) in cultured Chinese hamster ovary cells has been established by combining the three-way differentiation in third mitosis (M3) chromosomes and the immunoperoxidase reaction developed with 3,3'-diaminobenzidine using a monoclonal anti-bromodeoxyuridine (BrdU) antibody. This procedure allows SCD at very low BrdU concentrations, and the evaluation of the sister chromatid exchange frequencies on a per cell-cycle basis.

3,3'-Diaminobenzidine↗

PubMed1992

Mitomycin C, 4-nitroquinoline-1-oxide and ethyl methanesulfonate induce long-lived lesions in DNA which result in SCEs during successive cell cycles in human lymphocytes.

The present study was carried out in order to analyze how persistent the lesions in DNA are which elicit sister-chromatid exchanges (SCEs), induced by three different chemical agents, mitomycin C (MMC), 4-nitroquinoline-1-oxide (4NQO) and ethyl methanesulfonate (EMS), in proliferating human lymphocytes. Cells were exposed to the mutagens for 1 h just before starting bromodeoxyuridine substitution and SCEs were examined in third-cycle metaphases showing three-way-differential staining, by means of our previously standardized method. The results show that, in spite of the fact that these three compounds have different modes of action, the lesions induced by all of them seem to be capable of persisting in DNA and eliciting SCEs for at least three successive cell cycles.

4-Nitroquinoline-1-oxide↗

PubMed1992

Influence of low doses of BrdU and estimation of spontaneous SCE in CHO chromosomes: three-way differential staining and an immunoperoxidase method.

The influence of low doses of 5-bromodeoxyuridine (BrdU) on the occurrence of sister chromatid exchanges (SCEs) during the first cell cycle, when unsubstituted DNA templates replicate in the presence of the halogenated nucleoside (SCE1) has been assessed in third mitosis (M3) Chinese hamster ovary (CHO) cells showing three-way differential (TWD) staining. In addition, lower concentrations of BrdU, not detectable by Giemsa staining, have been tested by a high resolution immunoperoxidase method (anti-BrdU monoclonal antibody) and SCEs were scored in second mitosis (M2) cells. Our findings was a dose-response curve for SCE1 that allows an estimated mean spontaneous yield of 1.32/cell per cell cycle by extrapolation to zero concentration of BrdU. On the other hand, when the total SCE frequency corresponding to the first and second rounds of replication (SCE1 + SCE2) found in M3 chromosomes was compared with the yield of SCEs scored in M2 cells grown in BrdU at doses lower than 1 microM no further reduction was achieved. This seems to indicate that SCEs can occur spontaneously in this cell line, though the estimated frequency is higher than that reported in vivo.

Animals↗

PubMed1992

Poly-D-lysine in G2 potentiates chromosome damage induced by X-rays and mitomycin C in CHO cells.

A number of reports suggest that the role of radiation-induced G2 arrest is to allow repair of potentially lethal damage in the cells before it comes to mitosis. Though the exact nature of the damage undergoing repair during the delayed G2 is not known, the yield of chromosomal aberrations observed in metaphase seems to be a good parameter to predict reproductive death of cells. In a previous paper, we have shown that poly-D-lysine, acting in a fashion reminiscent of that of caffeine in mammalian cells, is able to induce a premature onset of mitosis concomitant with an increase in the frequency of chromosomal aberrations in mutagen-treated plant cells. Cultured CHO cells were pre-exposed to either X-rays or mitomycin C and given different doses of the polycationic compound during G2 in order to analyze any effect on the frequency of chromatid-type aberrations as well as any modification of cell-cycle kinetics. A potentiation of chromosome damage and a premature arrival at mitosis were observed for both mutagens, though the effect was more evident in X-irradiated cells.

Animals↗

PubMed1992

A comparative study of the potentiating effect of caffeine and poly-D-lysine on chromosome damage induced by X-rays in plant cells.

X-Ray-induced chromosomal aberrations (CA) were potentiated by post-treatments in G2 with either caffeine (caff) or poly-D-lysine (PDL) in root-tip cells of Allium cepa. The enhancement of the yield of CA was concomitant with an increase in the frequency of mitosis. Our results seem to support the idea of a direct relationship between radiation-induced G2 delay and repair of chromosome damage. Here we report on similarities between caffeine and PDL in both decreasing G2 delay and enhancing chromatid aberration yield. The possible molecular mechanism(s) of action responsible for the cytogenetic effects observed are discussed.

Caffeine↗