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Biomedical subjects

F Cortés

Publications and source records attributed to F Cortés.

At least 37 records · Page 2Linked to original sources
PubMed1999

HCA, an immunoglobulin-like adhesion molecule present on the earliest human hematopoietic precursor cells, is also expressed by stromal cells in blood-forming tissues.

We have previously shown that the HCA/ALCAM (CD166) glycoprotein, a member of the immunoglobulin family that mediates both homophilic and heterophilic cell-cell adhesion, via the CD6 ligand, is expressed at the surface of all of the most primitive CD38(-/lo), Thy-1(+), rho123(lo), CD34(+) hematopoietic cells in human fetal liver and fetal and adult bone marrow. In the present report we show that HCA is also expressed by subsets of stromal cells in the primary hematopoietic sites that sequentially develop in the human embryo and fetus, ie, the paraaortic mesoderm, liver, thymus, and bone marrow. Adult bone marrow stromal cells established in vitro, including those derived from Stro-1(+) progenitors and cells from immortalized cell lines, express HCA. In contrast, no HCA expression could be detected in peripheral lymphoid tissues, fetal spleen, and lymph nodes. HCA membrane molecules purified from marrow stromal cells interact with intact marrow stromal cells, CD34(+) CD38(-) hematopoietic precursors, and CD3(+) CD6(+) peripheral blood lymphocytes. Finally, low but significant levels of CD6 are here for the first time detected at the surface of CD34(+) rho123(med/lo) progenitors in the bone marrow and in mobilized blood from healthy individuals. Altogether, these results indicate that the HCA/ALCAM surface molecule is involved in homophilic or heterophilic (with CD6) adhesive interactions between early hematopoietic progenitors and associated stromal cells in primary blood-forming organs.

Adult↗
PubMed1999

Differential expression of KDR/VEGFR-2 and CD34 during mesoderm development of the early human embryo.

Recent findings on vertebrate embryos have provided compelling evidence for the existence of hemangioblasts, i.e. common precursors for endothelial and hematopoietic cells, characterized by expression of the VEGFR2/Flk1 receptor. We describe here a population of KDR+ CD34- mesoderm cells that emerges in early-somitic human embryos, by the beginning of the 4th week of gestation. In the developing blood vessels, KDR-expressing CD34- cells gradually coexpress increasing levels of CD34 antigen. Remarkably, as development proceeds, a KDR+ CD34- contingent persists in the paraaortic splanchnopleura until just prior to the emergence of aorta-associated hematopoietic cell clusters. These observations suggest that KDR+ CD34- mesodermal cells might represent the putative hemangioblastic precursor of human hematopoietic and endothelial lineages.

Antigens, CD34↗
PubMed1999

Topoisomerase activities and levels in irradiated Chinese hamster AA8 cells and in its radiosensitive mutant EM9.

PURPOSE: To investigate possible variations in topoisomerase (topo) I and II activities and levels after X-ray treatment in the radiation repair proficient AA8 Chinese hamster cell line for comparison with the radiation sensitive mutant EM9. MATERIALS AND METHODS: AA8 and EM9 cells were irradiated with 5 Gy of X-rays and the activities of topoisomerases I and II in nuclear extracts were studied. Immunological detection of both topoisomerases was carried out in order to detect any changes in the expression of these enzymes as a consequence of irradiation. RESULTS: Topoisomerase activities and levels in irradiated EM9 cells were the same as in control non-irradiated cells. In fact, both topo I and topo II activities clearly increased shortly after irradiation in the parental AA8 cells, with a more rapid increase for topo I than for topo II. In the AA8 cells, an increased level of topo I detectable immunologically was only observed at a later time (1 h) after irradiation, while no similar change was detectable for topo II. CONCLUSIONS: While this hypothesis needs further testing, an attractive idea is that DNA topoisomerases might be involved in the cellular response to radiation damage, either through a direct participation in repair mechanisms or indirectly.

Animals↗
PubMed1999

Increased levels of DNA topoisomerases in cultured CHO cells treated with the antitumour drug 5-azacytidine.

Cultured Chinese hamster ovary (CHO) cells were treated with the cytidine analogue 5-azacytidine (5-azaC) which, in good agreement with results previously described from studies carried out in other primary or established mammalian cell lines, resulted in extensive chromosome decondensation and a shift in the time of replication of normally late-replicating heterochromatin to earlier replication. DNA topoisomerases (mainly topo I) have been involved in transcription, and the hypomethylating effect of 5-azaC reportedly results in the expression of silenced genes. Whether such an increase in transcription is paralleled by increased levels of both topo I and topo II, as well as by an enhancement in the topoisomerase activities, has been investigated in this work. The results seem to suggest that both the relative amount of topoisomerases and their activities are enhanced after a protracted treatment with the cytidine analogue over those observed in untreated controls. These observations could be significant for antitumour therapy.

Animals↗
PubMed1998

Molecular identity of hematopoietic precursor cells emerging in the human embryo.

It is now accepted from studies in animal models that hematopoietic stem cells emerge in the para-aortic mesoderm-derived aorta-gonad-mesonephros region of the vertebrate embryo. We have previously identified the equivalent primitive hematogenous territory in the 4- to 6-week human embryo, under the form of CD34(+)CD45(+)Lin- high proliferative potential hematopoietic cells clustered on the ventral endothelium of the aorta. To characterize molecules involved in initial stem cell emergence, we first investigated the expression in that territory of known early hematopoietic regulators. We herein show that aorta-associated CD34(+) cells coexpress the tal-1/SCL, c-myb, GATA-2, GATA-3, c-kit, and flk-1/KDR genes, as do embryonic and fetal hematopoietic progenitors later present in the liver and bone marrow. Next, CD34(+)CD45(+) aorta-associated cells were sorted by flow cytometry from a 5-week embryo and a cDNA library was constructed therefrom. Differential screening of that library with total cDNA probes obtained from CD34(+) embryonic liver cells allowed the isolation of a kinase-related sequence previously identified in KG-1 cells. In addition to emerging blood stem cells, KG-1 kinase is also strikingly expressed in all developing endothelial cells in the yolk sac and embryo, which suggests its involvement in the genesis of both hematopoietic and vascular cell lineages in humans.

Antigens, CD34↗
PubMed1998

Enhanced sensitivity to topoisomerase inhibitors in synchronous CHO cells pre-treated with 5-azacytidine.

Multidrug combination has been shown to be very useful to improve antitumor activity as well as to reduce the toxicity of different anti-cancer drugs. We have evaluated the interaction between the hypomethylating agent 5-azacytidine and the topoisomerase I and topoisomerase II inhibitors Camptothecin (CPT) and 4'-(9-acridinylamino) methanesulfon-m-anisidide (m-AMSA) respectively, based on the hypothesis that through the alteration of chromosome replication timing following DNA hypomethylation, the number of replication forks in early S phase might increase, so enhancing the probability of a collision between a blocked cleavable complex (DNA-topo I-CPT or DNA-topo II-m-AMSA) and a replication fork. We have tested the capacity of CPT and m-AMSA to induce chromosomal aberrations as well as reproductive cell death in synchronous cultured Chinese hamster ovary cells after a pretreatment with 5-azacytidine with positive results.

Amsacrine↗
PubMed1998

A high yield of translocations parallels the high yield of sister chromatid exchanges in the CHO mutant EM9.

The fluorescence plus Giemsa (FPG) and fluorescence in situ hybridization (FISH) techniques have been used to determine, respectively, the frequencies of sister chromatid exchanges (SCEs) and stable chromosome aberrations (translocations) induced by different concentrations of BrdU in the Chinese hamster ovary cell mutant EM9 and its parental line AA8. The results indicate that BrdU induced a high frequency of SCEs and translocations in EM9 as compared with AA8, and that the translocation/dicentric ratio was also higher in the mutant cell line than in the parental cell line in both untreated and BrdU-treated cultures. These observations may indicate a possible relationship between the molecular mechanisms involved in the formation of SCEs and translocations.

Animals↗
PubMed1998

[Direct molecular analysis of FMR-1 gene mutation in patients with fragile Xq syndrome and their families].

BACKGROUND: The unequivocal diagnosis of fragile Xq syndrome is based in the direct analysis of the underlying FMR-1 gene mutation, that consists in an increased number of trinucleotide CGG repetitions. AIM: To study families with fragile Xq syndrome, using the Southern technique for the analysis of the mutation. SUBJECTS AND METHODS: Fifteen individuals, pertaining to 6 families with fragile Xq syndrome, were studied. Clinical, cytogenetic and molecular analysis using Southern technique, were done. RESULTS: Five male individuals had a clinically evident syndrome, confirmed by cytogenetic analysis that showed fragility in 10 to 29% of studied cells. One subject with a clinical picture suggesting fragile Xq had a normal cytogenetic study. The other studied subjects were the mothers of the five subjects with the syndrome, that must be carriers, and four brothers. Molecular analysis showed that seven subjects (5 males) had a complete mutation, five (4 females) were carriers of a pre mutation and three (2 males) did not have the mutation. CONCLUSIONS: The Southern technique allows to verify the normal condition of FRAXA locus, identify carriers and to detect complete mutations in fragile Xq syndrome.

Female↗
PubMed1998

[Fetal alcohol syndrome and fetal alcohol effects: importance of early diagnosis and nutritional treatment].

BACKGROUND: Fetal alcohol syndrome (FAS) and fetal alcohol effects (FAE) encompass a pattern of birth defects in persons whose mothers ingested alcohol during pregnancy. People with FAE display fewer of the FAS traits. AIM: To assess the prevalence and features of these affections in a secondary nutritional recovery centre. PATIENTS AND METHODS: All charts of children admitted between 1985 and 1995 were reviewed, and those children diagnosed as having a FAS or FAE by a geneticist were considered for this study. Birth, maternal, social and economic characteristics, psychomotor abilities (using Denver test) and response to nutritional treatment were assessed. RESULTS: During the study period, 1572 infants were admitted to the centre, and 1.97% (70% female) were diagnosed as having a FAS or FAE. These infants were admitted at 11.1 +/- 4.5 months of age and discharged after 96.7 +/- 58.1 months of hospitalisation. Mean mother's age was 33 +/- 7 years, and all belonged to low socioeconomic levels. Mean birth weight was 2048 +/- 431 g and 2469 +/- 619 g in children with FAS and FAE respectively (p < 0.03). Children with FAE performed better for gross and fine motor abilities than those with FAS. No differences were observed for language performance. Sixty five percent of children with FAS and 71% of children with FAE had an adequate weight and height increment during nutritional therapy. A multiple regression analysis showed that age at admission and gestational age were significant predictors of weight gain during therapy. CONCLUSIONS: Alcohol has teratogenic effects on the foetus that affect craneal size and psychomotor development. Alcohol also affects pre and post natal growth.

Alcoholism↗
PubMed1998

Protection provided by exogenous DNA ligase in G0 human lymphocytes treated with restriction enzyme MspI or bleomycin as shown by the comet assay.

DNA double-strand breaks (DSB) may arise either spontaneously during cellular processes or as a result of exposure to DNA-damaging agents such as ionizing radiation, or radiomimetic agents such as restriction endonucleases or bleomycin. It is widely accepted that nonrepaired or misrepaired DSB are the main lesions leading to the production of chromosomal aberrations, mutagenesis, oncogenic transformation, and cell killing. Studies focusing on this relationship, as well as the possible modulation of DNA repair mechanisms, are currently of major interest. A wide variety of test systems are available to study DNA damage. In the last few years, single-cell gel electrophoresis, commonly known as "comet assay," has been considered a rapid, sensitive, and visual method for quantifying DNA strand breaks and alkali-labile damage in individual cells. In this study, making use of the comet assay, we tried to find out if under conditions that maintain chromatin structure the DNA ligase from T4 phage is able to facilitate the rejoining of strand breaks with different end structures, induced by the restriction endonuclease MspI or bleomycin in living human lymphocytes in a nonproliferating state. T4 DNA ligase, as well as the restriction endonuclease or bleomycin, were introduced together by electroporation into human lymphocytes. Our results support the idea that it is possible to modulate the DSB-rejoining of different DNA strand-breaking agents by exogenous T4 DNA ligase.

Bleomycin↗
PubMed1997

Apoptotic and necrotic cell death are both induced by electroporation in HL60 human promyeloid leukaemia cells.

Cell death was induced by electroporation in HL60 cells, a human promyeloid leukaemia strain, in order to determine by both morphological and biochemical criteria whether necrotic or apoptotic processes occurred. Cells sampled at several times after electroporation were analyzed for the assessment of the following end-points: (i) chromosomal DNA fragmentation; (ii) cell viability; (iii) mono- and oligonucleosomes in the cytoplasmic fraction; (iv) apoptotic index; and (v) morphology of treated cells. The results indicate that about 50% of the cells killed by electroporation die through necrosis, while the remaining 50% of the cells undergo apoptosis. Chromosome damage was also studied by cytogenetic analysis at metaphase. The possibility of killing tumour cells by electroporation, as a variant of electrotherapy, constitutes, in our opinion, a promising procedure in cancer therapy, avoiding the undesirable side effects normally derived from treatment with cytotoxic drugs.

Journal Article↗
PubMed1997

T4 DNA ligase reduces chromosome damage and enhances cell survival in CHO cells treated with bleomycin.

The effect of DNA ligase from T4 phage on the modulation of the damage induced by bleomycin was studied. CHO6 cells were electroporated with either bleomycin alone or bleomycin plus T4 DNA ligase, and both cytogenetic and clonogenic assays were carried out in parallel. Our results show that T4 DNA ligase is able to decrease the frequency of chromosome aberrations in bleomycin-treated cells while increasing cell survival.

Animals↗
PubMed1996

Sister chromatid exchange induced by DNA topoisomerases poisons in late replicating heterochromatin: influence of inhibition of replication and transcription.

Previous studies have shown the importance of DNA replication fork progression for the cytotoxicity of topoisomerase inhibitors as well as for their ability to induce chromosomal aberrations and sister chromatid exchange (SCE). In the present report, we have carried out experiments in CHO cells in order to study the induction of SCE by topo I and topo II inhibitors in both euchromatin and late-replicating heterochromatin, as well as the possible influence of inhibition of DNA replication or transcription on the occurrence of SCE. Treatment with the DNA synthesis inhibitor aphidicolin reduced the frequency of SCE induced by topoisomerase inhibitors in constitutive heterochromatin of the X chromosome, while the RNA synthesis inhibitor actinomycin D also had an effect on SCE induced by high doses of the topoisomerase poisons, in spite of the lack of active transcription which characterizes this heterochromatic region.

Amsacrine↗
PubMed1996

On the importance of DNA strand breaks as the first event to initiate sister chromatid exchange (SCE): experiments with restriction endonuclease BglI.

The exact molecular mechanism of sister chromatid exchange (SCE) is still unknown, despite the many reports dealing with this cytogenetic end point published in the last 40 years. One point to be investigated is the nature of the original lesion(s) in DNA leading to the production of SCE. Whereas, for chromosomal aberrations, the importance of DNA double-strand breaks has been well established, there is still controversy about the relative importance of strand breaks and base modifications for triggering the process of SCE formation. In the present paper, we have taken advantage of the ability of the restriction endonuclease BglI to induce SCE and have exploited the fact that preincubation with 2,3-butanedione results in the loss of BgiI ability to cut DNA, while it is still able to recognize its sequence in DNA and bind to it, to see whether this alone is enough to initiate SCE formation, or if a physical DNA double-strand break is required. Our results seem to support the necessity of DNA breaks for SCE production.

Animals↗
PubMed1995

[Delegated prescription by specialists in primary care].

OBJECTIVES: To describe the qualitative-quantitative features of Primary Care prescriptions originated by specialists. DESIGN: A crossover descriptive study. SETTING: Txantrea Health Centre (Pamplona). PATIENTS AND OTHER PARTICIPANTS: All the prescriptions originated by out-clinic or hospital specialists over a two-month period, in three Health Centre clinics. MEASUREMENTS AND MAIN RESULTS: The number of prescriptions passed on to Primary Care was 3,009, costing 5,303,071 pesetas, which was 31.61% of the drugs prescribed and 38.08% of the pharmaceutical expenditure of the three clinics during the period under study. 65.88% of the prescriptions corresponded to out-clinic specialists and 34.11% to hospital specialists. They were not accompanied by a clinical note, the treatment and the length of treatment in 33.46%, 36.55% and 45.39% of cases, respectively. The group and sub-group with most prescriptions passed on were Cardiovascular Apparatus and Calcium antagonists. The commonest active principal was acetylsalicylic acid. 79.89% were taken orally, 88.20% were single drugs and 73.28% of the medicines had high intrinsic value. CONCLUSIONS: An important proportion of Primary Care's pharmaceutical expenditure was identified as originating with specialists. There was scant information given for following up the patients. Improvement of communication between different care levels on the basis of common procedures and objectives would be a useful step towards better quality of care.

Drug Prescriptions↗
PubMed1995

Chromosome damage induced by combined treatments with restriction endonucleases introduced into CHO cells by single or double electroporation.

The possible recombination between non-homologous termini produced by restriction enzymes (REs) introduced in CHO cells by electroporation was studied. For this purpose, different combinations of REs that produced blunt or 5' overhanging DNA double-strand breaks were electroporated into cells either at the same time or separately by double electroporation experiments. Prior to double electroporation, it was confirmed that, once the cells have been electroporated, they resist a second electroporation, as assessed by cell viability analysis. Besides, the efficient and homogeneous introduction of labelled, non-permeable molecules was assessed by fluorescence microscopy. Our results showed interaction for most of the conditions, mainly when the REs were introduced separately. Differences found in the degree of interaction between the combinations studied are discussed.

Animals↗
PubMed1995

T4 DNA ligase modulates chromosome damage induced by restriction endonucleases through an error-free process.

The possible modulation by T4 DNA ligase of the DNA double-strand breaks produced by restriction endonucleases in living mammalian cells was studied. A clear decrease in the frequency of chromosomal aberrations was observed when T4 DNA ligase was included in the electroporation treatment along with restriction enzymes inducing either cohesive- or blunt-ends in DNA. The relative proportions of exchange-type aberrations were similar for both kinds of treatments (with and without ligase), which seems to suggest an error-free ligation by T4 DNA ligase.

Animals↗