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Biomedical subjects

I Domínguez

Publications and source records attributed to I Domínguez.

14 recordsLinked to original sources
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

Electrophysiological and neurochemical study of the rat geniculo-cortical pathway. Evidence for glutamatergic neurotransmission.

The projection from the dorsal lateral geniculate nucleus to the primary visual cortex of the rat was studied electrophysiologically. Electrical stimulation of the dorsal lateral geniculate nucleus and the optic tract produced three types of responses on neurons of area 17: excitation followed by inhibition, excitation and inhibition. These results extend and confirm, in adult rats, previous studies done in rat geniculate-visual cortex cocultures preparations in vitro. The role of glutamate in the neurotransmission of the rat geniculo-cortical pathway was also investigated. In a first set of experiments, the effects of kynurenate, an antagonist of glutamate receptors, on visual cortex neurons with a monosynaptic excitatory response to dorsal lateral geniculate nucleus stimulation were studied. Microiontophoresis of kynurenate in area 17 neurons selectively suppressed the excitatory response to dorsal lateral geniculate nucleus and optic tract stimulation. In a second set of experiments, the effects of electrical stimulation of the dorsal lateral geniculate nucleus and the optic tract on the release of amino acids in the rat visual cortex in vivo were studied. Using the push-pull method, we perfused a discrete region of the visual cortex with artificial cerebrospinal fluid (CSF), and the amino acid content of the perfusates was analysed by high performance liquid chromatography (HPLC). Stimulation of either the dorsal lateral geniculate nucleus or the optic tract significantly increased glutamate release in area 17. The rest of the amino acids studied did not show significant changes. The results provide evidence for the participation of glutamate in the neurotransmission of the geniculo-cortical pathway in the rat.

Animals↗
PubMed1998

[Image processing in the primary visual cortex].

INTRODUCTION: Area 17 or the primary visual area forms the first link in the chain of cerebral analysis of a visual image. The neurones forming the primary visual cortex are characterized by the extreme precision of their connections, functional specialization and hierarchic organization. The spatial precision of the connections within the system for vision permit retinotopic representation in the visual cortex, so that each point of the retina is projected into a specific area of the cortex. The cortical neurones which analyze the characteristics of the image situated in a precise zone of the visual field are themselves organized into a basic functional unit known as a hypercolumn. Within each hypercolumn there are various columnar cell systems with receptive fields having similar characteristics. Thus, each hypercolumn is made up of multiple orientation columns, two ocular dominance columns and 'blob' regions. All these systems permit the analysis of different aspects of the image. The neurones belonging to the orientation columns are sensitive to the orientation, spatial frequency and movement of a visual stimulus; those of the 'blob' regions to colour, and the binocular neurones of the ocular dominance columns to depth. Within each column, the hierarchical pattern of neurone interconnections determines the successive appearance of cells with receptive fields having new properties.

Geniculate Bodies↗
PubMed1998

Antegrade nailing for fractures of the distal femur.

Thirty-five fractures of the distal femur were treated by antegrade intramedullary nailing. All of the fractures were treated by a closed technique. In the cases in which there was extension of the fracture to the knee joint, the fracture initially was stabilized with percutaneous lag screws. Four patients died before fracture healing was complete and 11 were lost to followup. There were 14 extraarticular (Type A) and six intraarticular (Type C1 and Type C2) fractures. All of these fractures healed in a mean time of 17.27 weeks. Functional outcome using the Hospital for Special Surgery knee score was 87. Complications were infrequent with one (5%) pseudarthrosis and no infections. Although this is a very demanding technique, antegrade intramedullary nailing is an efficient procedure compared with other methods of open reduction and internal fixation for difficult distal femoral fractures.

Bone Screws↗
PubMed1995

Construction of Chinese hamster chromosome specific DNA libraries and their use in the analysis of spontaneous chromosome rearrangements in different cell lines.

Chinese hamster (Cricetulus griseus) and a wide variety of cell lines derived from it have been extensively used for radiobiological and genotoxicity studies. In this report, we describe the development of chromosome-specific DNA libraries for Chinese hamster chromosomes 1, 2, 3, 5, 6, 7 and 8 by the linker/adaptor method. The specificity of these probes have been checked by FISH on primary embryonic fibroblast (CHE) metaphase chromosomes. The diploid number of chromosomes in different cell lines of CHO often varies from 19 to 21 and karyotyping is very difficult owing to many spontaneous rearrangements. Using Chinese hamster chromosome-specific DNA libraries, we have analysed the spontaneous chromosome rearrangements in three different Chinese hamster transformed cell lines, V79, CHO-KI and CHO-9. The results indicate that one of each of the first and fifth pair of chromosomes are involved in reciprocal translocations in both CHO-9 and CHO-K1 cells. The hybridisation patterns obtained with chromosome-specific probes 2, 3, 5, 6, 7 and 8 indicated rearrangements have occurred involving terminal and interstitial translocations in V79, CHO-KI and CHO-9 cells.

Animals↗
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

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↗
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↗
PubMed1992

[Positive anti-Borrelia antibodies in patients with clinical manifestations compatible with neuroborreliosis].

The clinical features of 19 patients with neurological manifestations unexplained by another disease and positive serology for Borrelia burgdorferi were studied. ECM was present in only 11% of the cases and 32% referred tick bite. The characteristic features for suspicion of NB according to our series was the presence of polyneuritis in 84% of the cases specially in the form of multiple mononeuritis and involvement of the facial nerve (79%) leading to even greater suspicion with the association of V pair involvement. Seizures, sleep disorders, and higher mental dysfunction may be found in association with other more characteristic neurological features. The typical triad of NB (aseptic meningitis, facial paralysis and polyradiculoneuritis) was found in 21% of the patients and in the absence of another disease to justify the same neuroborreliosis (NB) seemed evident. In all the cases components of this triad were found. Headache, arthralgia, fever and, less frequently, arthritis are other symptoms often past with the presence of anti-BB antibodies. Patients with the shortest evolution most frequently presented antecedents of facial paralysis, sensory alterations and Romberg's sign than patients of longer evolution. CSF demonstrated the presence of pleocytosis in 24% of the cases and in only one patient a slight increase in the intrathecal activity of IgG was observed which may be of use in differential diagnosis with MS. MR showed alterations in 61% of the patients and, while not specific, the lesions present subcortical predominance.

Adult↗
PubMed1990

Evidence for an adaptive response to radiation damage in plant cells conditioned with X-rays or incorporated tritium.

Allium cepa root-tip cells were first exposed to low 'conditioning' doses of ionizing radiation: to X-rays (0.06 or 0.26 Gy) or to incorporated tritium (1.8 x 10(4) or 7.2 x 10(4) Bq/ml; specific activity: 740.0 GBq/mmol) and subsequently given a 'challenge' dose of 1.5 Gy of X-rays. A reduction in X-ray-induced chromosomal damage was brought about by prior exposure to 0.26 Gy of X-rays, while cells receiving the lower conditioning dose (0.06 Gy of X-rays) did not show any significant reduction. In cells grown in the presence of [3H]TdR on the other hand, the adaptive response was evident after both doses given. The results are essentially in agreement with those published by Wolff's group for human lymphocytes in showing that plant cells in vivo can become 'adapted' by exposure to low-level irradiation so that they become more resistant to the clastogenic effects of X-rays delivered subsequently.

Adaptation, Biological↗
PubMedDate not supplied

Alterations in levels of different protein kinase C isotypes and their influence on behavior of squamous cell carcinoma of the oral cavity: epsilon PKC, a novel prognostic factor for relapse and survival.

BACKGROUND: Recent results suggest that some PKC isotypes, when overexposed, confer to cultured fibroblasts certain proliferative advantages, and enhanced tumorigenicity in nude mice, suggesting their participation in carcinogenic process. These findings need to be validated through the investigation of potential alterations of these kinases in common forms of human cancers. MATERIAL AND METHODS: In this prospective study we determined levels of different PKC isozymes by Western blot in tissue extracts from 29 human primary squamous cell carcinomas of the oral cavity, and their respective controls. These expressions were correlated with behavior of tumor and histologic characteristics. RESULTS: Dramatic alterations in different PKC isotypes were found. Thus, increased levels of isotypes alpha, beta, or gamma, and zeta were found in most of the patients, as well as significant correlations between levels of the isotype epsilon and survival-relapse rate and classical PKC isotypes with irregular morphology of tumoral interphase. CONCLUSIONS: These results suggest participation of some PKC isotypes (alpha, beta, gamma, and zeta) in the genesis and behavior (epsilon) of oral cancers. Levels of epsilon PKC could be used as prognostic marker.

Adult↗