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Biomedical subjects

J Quintana

Publications and source records attributed to J Quintana.

At least 19 recordsLinked to original sources
PubMed2003

The inducible isoform of CREM (inducible cAMP early repressor, ICER) is a repressor of CYP19 rat ovarian promoter.

The synthesis of estradiol by the granulosa cells is a prominent event in ovarian physiology and depends on the expression of P450(AROM). FSH induces the expression of P450(AROM) in granulosa cells as a result of the presence in the ovarian promoter of a CRE (cAMP response element)-like sequence (CLS). In rodents, LH downregulates aromatase expression during luteinization by an as yet undescribed mechanism. In granulosa cells, LH increases the expression of the inducible cAMP early repressor (ICER), an isoform of CREM (cAMP-responsive element modulator) that represses cAMP-induced transcription. The possibility that ICER represses the activity of the aromatase ovarian promoter, thus being part of the mechanism underlying the effects of LH was investigated. We have found that: (1) nuclear proteins from forskolin-stimulated granulosa cells were specifically bound to an oligonucleotide containing the CLS sequence of the CYP19 ovarian promoter and one out of the two protein-DNA complexes formed was supershifted by an anti-CREM antibody; (2) in granulosa cells, forskolin-induced increases in P450(AROM) promoter luciferase reporter gene activity were prevented by the transient overexpression of ICER; (3) similar results were obtained in 8-Br-cAMP-stimulated R2C cells, a Leydig tumor cell line routinely used for the study of P450(AROM) promoter activity; (4) both ICER mRNA levels and P450(AROM) promoter-driven luciferase activity were elevated 6 and 12 h after stimulation of R2C cells with 8-Br-cAMP and were decreased 24 and 48 h later; (5) in an R2C polyclonal line overexpressing ICER, the promoter activity at early stages of stimulation was completely attenuated, while 24 and 48 h downregulation was prevented in another R2C line stably transfected with an antisense ICER construct. These results suggest that ICER represses CYP19 ovarian promoter and that LH-induced expression of ICER may serve to downregulate P450(AROM) transcription in granulosa cells during luteinization.

Animals↗
PubMed2001

Monitoring of pesticides in drinking and related waters in NE Spain with a multiresidue SPE-GC-MS method including an estimation of the uncertainty of the analytical results.

A new method, developed in an EC project (SMT4-CT96-2142) for the determination of 22 pesticides in drinking and related waters, has been used to analyze source and drinking water samples in the area of Barcelona (NE Spain). The procedure includes solid-phase extraction of water and subsequent analysis by GC-MS using few selected ions (SIR) in order to increase their sensitivity. The method was subjected to intra and interlaboratory tests and met the requirements of the EC Directive in terms of accuracy, precision and detection limit (0.025 microg/l range in water samples). A detailed analysis of the uncertainty sources of this method is included, which allows to estimate expanded uncertainties in the 10-20% range. The dominant sources of uncertainty are the solid-phase extraction procedure and the chromatographic quantification. Two triazine compounds, simazine and atrazine, are the main pesticides detected in wells of the Llobregat river and in water of the Ter river, respectively.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

Clinical and pathological observations on pigs with postweaning multisystemic wasting syndrome.

The aim of this work was to characterise the lesions and agents present in clinically normal and clinically affected pigs on a farm during an outbreak of postweaning multisystemic wasting syndrome (PMWS), and to evaluate the diagnostic techniques for detecting porcine circovirus type 2 (PCV-2) and other microorganisms. Four pigs in the early stage and 11 pigs in the late stage of the disease, and eight clinically normal pigs were necropsied. Samples of lymphoid tissue and serum were also obtained from 12 slaughter pigs from the same farm. The tissues were examined histopathologically, and in situ hybridisation, serology and PCR were used to detect porcine circovirus type 1 (PCV-1) and/or PCV-2 in tissues and/or sera. The presence of porcine reproductive and respiratory syndrome virus (PRRSV), Aujeszky's disease virus (ADV) and porcine parvovirus (PPV) were also investigated. Characteristic microscopical lesions of PMWS were observed in the lymphoid tissues of the pigs in all three necropsied groups; the lesions were most common and severe in the pigs in the early stage of the disease, less so in the pigs in the late stage of the disease, and least in the clinically normal pigs. PCV-2 infection was detected in all the necropsied pigs by in situ hybridisation and PCR. Only three pigs had the PCV-1 genome in serum or lymph node tissue. In contrast, the slaughter pigs had no microscopical lesions and no PCV-2 nucleic acid in their serum or tissues, and only one of them had the pCV-1 genome in its serum. Immunohistochemical, serological and PCR studies revealed that PRRSV and ADV were also present on the farm during the outbreak.

Animals↗
PubMed2001

Changes in peripheral blood leukocyte populations in pigs with natural postweaning multisystemic wasting syndrome (PMWS).

The objective of the present study was to analyze, by flow cytometry, changes in PBMC subsets in pigs having postweaning multisystemic wasting syndrome (PMWS), a new condition associated to porcine circovirus type 2 (PCV2) infection. Thirteen acutely PMWS affected pigs were selected from a farm seronegative to porcine reproductive and respiratory syndrome virus (PRRSV) and to Aujeszky's disease virus (ADV); 11 clinically healthy pigs were selected from a high health farm with no history of PMWS and free of the major swine pathogens, and used as a control group. All pigs were necropsied, and tissue samples were fixed in formalin; blood with EDTA anticoagulant was used to perform the flow cytometric analysis. PBMC were incubated with mAb against porcine CD3, CD4, CD8, CD25, CD45, IgM, SWC3, and SLA-Class II. Flow cytometric analysis showed substantial changes in leukocyte subsets in the peripheral blood of PMWS-affected pigs, which were characterized by an increase of monocytes, a reduction of T (mainly CD4(+)) and B-lymphocytes, and the presence of low-density immature granulocytes. Altogether, these changes would suggest an inability of acutely PMWS-affected pigs to mount an effective immune response.

Animals↗
PubMed2001

A compensatory mirror cortical mechanism for facial affect processing in schizophrenia.

When primates passively observe other subjects perform specific gestures or actions, premotor and motor cortical areas involved in the internal representation and actual execution of those actions exhibit neuronal activation. This mirror mechanism matches observation, representation, and execution, facilitating internal motor rehearsal, imitation, recognition of actions by others and their meanings, and social learning. Schizophrenic patients have deficits in processing affect displayed by other people's faces, which likely relates to the poor social adaptation and functioning seen in the condition. We hypothesized that, when correctly performing working-memory tasks requiring facial affect processing, schizophrenic patients would show relative increased activity in brain areas involved in social learning and in the internal representation of facial expressions when compared to controls. We used functional magnetic resonance imaging in schizophrenic patients and normal controls to detect relative changes of blood flow in cortical areas related to the representation of facial expressions while the subjects performed simple working-memory tasks with facial emotion diagrams or color circles as cues. We found that, when the task cues were facial expressions in contrast to color circles, the schizophrenic group exhibited increased activation of the face movement areas in motor and pre-motor cortex.

Adult↗
PubMed2001

Granulomatous enteritis and lymphadenitis in Iberian pigs naturally infected with Lawsonia intracellularis.

Intestinal samples and/or lymph nodes of two Iberian pigs from two different farms were submitted for histopathologic examination. Both pigs had proliferation of ileal and/or cecal crypts with almost complete absence of goblet cells. Infection by Lawsonia intracellularis was demonstrated by immunohistochemistry and polymerase chain reaction assay. The mesenteric lymph node of one pig had moderate lymphocyte depletion with granulomatous inflammation of the lymph node parenchyma. Histiocytes and multinucleated giant cells from the lymph node of one pig contained L. intracellularis antigen within the cytoplasm. This pig had also porcine circovirus type 2 (PCV-2) infection, but nucleic acid and antigen of this virus were not demonstrated in the lymph node. The second pig had lymphocyte depletion and marked granulomatous inflammation in Peyer's patches. Histiocytes and multinucleated giant cells in areas of granulomatous inflammation contained L. intracellularis antigen; no PCV-2 nucleic acid or antigen was detected in the tissues of this pig. This is the first description of granulomatous ileitis and lymphadenitis associated with L. intracellularis infection.

Animals↗
PubMed2001

[Clinical significance and frequency of the 11q23/MLL genetic molecular alteration in Chilean infants with acute leukemia].

BACKGROUND: Acute leukemia (AL) in infants generally shows distinctive biologic features and has a poor prognosis. AIM: To study the frequency of the cytogenetic alteration of 11q23 chromosome or the recombination of MLL gene in infants less than 18 months old, with acute leukemia. PATIENTS AND METHODS: We analyzed 37 cases of AL in infants less than 18 months of age diagnosed in Chile from 1989 to 1999. The clinical features and cytogenetic/molecular defects of 11q23MLL gene rearrangement and their influence in prognosis were determined. RESULTS: There were 18 cases of acute Lymphoblastic leukemia (ALL) characterized by female sex (67%) high presenting leukocyte count (median 99 x 109/L), blast cells with a CD10 negative phenotype (50%) and 11q23/MLL rearrangement (39%). Molecular abnormalities of 11q23 were significantly associated with adverse prognosis, with an event free survival (EFS) of only 14 +/- 12%. Interestingly, infants with germ line 11q23 had a very good outcome with an EFS of 73 +/- 11% (p < 0.025). There were 19 cases of acute myeloblastic leukemia (AML) characterized by male sex (63%) high leukocyte count (median 93 x 109/L), FAB-MS morphology (53%) and 11q23/MLL rearrangement (53%). EFS was very poor, 20 +/- 9% and 33 +/- 4% for rearranged and germinal group respectively (p = NS), due to a high mortality rate during the first month of diagnosis. CONCLUSIONS: These findings demonstrate that Chilean ALL infants with 11q23 abnormalities have a very poor prognosis. However those with germinal state can enjoy a prolonged disease free survival with the current treatment protocols.

Blotting, Southern↗
PubMed2000

Regulation by ceramide of epidermal growth factor signal transduction and mitogenesis in cell lines overexpressing the growth factor receptor.

Ceramide has emerged as a pleiotropic signal mediator of cellular responses including differentiation, proliferation, cell cycle arrest and apoptosis. In the present study we evaluated the effect of cell permeant ceramide analogues on ligand-induced tyrosine phosphorylation of the EGF receptor (EGFR), phospholipase Cy (PLCgamma) activity and cell proliferation. Treatment with N-acetylsphingosine (C2-cer) and N-hexanoylceramide (C6-cer) prevented EGF-induced tyrosine trans-phosphorylation of the receptor in two different cell lines overexpressing the human EGFR (A431 and EGF-T17 cells). In contrast, treatment of A431 and EGFR-T17 cells with C2-cer or C6-cer did not affect the ligand binding capacity of the receptor, an effect that was however observed after TPA-induced activation of PKC. In addition EGF-stimulated PLCgamma activity was transiently decreased in A431 cells treated with C6-cer and only a modest, albeit significant reduction on ligand-induced 3H-InsP3 generation was observed in EGFR-T17 cells pretreated with ceramide. We also examined the effect of C2-cer on serum (A431)- or EGF (EGFR-T 17)-induced cell proliferation. Treatment of EGFR-TI7 cells with C2-cer (0.1-10 microM) did not affect cell viability, but prevented EGF-induced 3H-thymidine incorporation in a dose-dependent manner. In contrast, 3H-thymidine incorporation in serum-stimulated A431 cells decreased only at the higher doses of C2-cer used (1-10 microM), being this effect accompanied by a slight, albeit significant (20-25%), reduction in cell viability.

Animals↗
PubMed1999

Improved outcome for acute lymphoblastic leukemia in children of a developing country: results of the Chilean National Trial PINDA 87.

BACKGROUND: The National Chilean Pediatric Oncology Group, PINDA, reports the first prospective, nonrandomized trial for acute lymphoblastic leukemia (ALL), using a modified version of the Berlin-Frankfurt-Munster protocol (ALL BFM 86). The aim of this study was to classify immunophenotypes, to decrease cranial irradiation, and to assess whether this protocol would improve the survival rate. PROCEDURE: From June, 1987, to June, 1992, 444 unselected children were diagnosed with ALL. Of them, 425 were evaluable. Therapy was stratified by risk. Standard-risk (SR) and high-risk (HR) patients received protocols I, M, II, and maintenance therapy. Very-high-risk (VHR) patients received protocol E instead of protocol M. All patients received a prephase treatment consisting of prednisone and intrathecal methotrexate (MTX). HR and VHR patients received cranial irradiation (12-18 Gy). The following changes were made to the ALL BFM 86 protocol: in protocol M, MTX 1 g/m2 instead of 5 g/m2; in protocol E, citarabine 1 g/m2 instead of 2 g/m2; mithoxantrone and ifosfamide were substituted by teniposide and cyclophosphamide. RESULTS: Immunophenotypes: pro-B-ALL, 14%; common ALL, 67.4%; pre-B-ALL, 4.3%; T-ALL, 10%; undifferentiated leukemia (AUL), 4.3%. The overall 5-year event-free survival (EFS) rate was 60% +/- 2% (SE). The 5-year EFS rate for each risk group was: SR 75%, HR 62%, VHR 28%, with a median follow-up of 6.5 years (range 4.5-9.5 years). The cumulative incidence of central nervous system (CNS) relapse was 5.4%. CONCLUSIONS: We have been able successfully to perform a nationwide study. Our strategy to adapt the BFM protocol to our population of patients trial was effective in improving the EFS. The immunophenotype distribution is similar to that in other reported series.

Adolescent↗
PubMed1999

[18F]Fluoro-beta-fluoromethylene-m-tyrosine derivatives show stereo, geometrical, and regio specificities as in vivo central dopaminergic probes in monkeys.

Stereo (D and L), geometrical (E and Z), and regiospecific (2-, 4-, and 6-[18F]fluoro) analogs of beta-fluoromethylene-m-tyrosine (FMMT) have been investigated in adult vervet monkeys (Cercopithecus aethiops sabaeus, n = 12) in vivo with positron emission tomography (PET). Brain transport through the blood-brain barrier and central aromatic amino acid decarboxylase (AAAD)-mediated decarboxylation rates were established. Results show strict structural dependency of the kinetic behavior of radiofluorinated FMMT analogs, with the E-isomer exhibiting a higher specificity over the (Z) geometrical counterpart for central dopaminergic structures. The 6-[18F]fluoro substituted L-(E)-FMMT was also favored over the 2- and 4-[18F]fluorosubstituted isomers in terms of their ability to localize in the same brain areas. The role of PET in drug development is also exemplified in this work.

Animals↗
PubMed1997

Oral 18F-fluoro-2-deoxyglucose for primate PET studies without behavioral restraint: demonstration of principle.

We describe a method of orally administering 18F-fluoro-2-deoxyglucose (FDG) for positron emission tomography (PET) scans to determine local cerebral metabolic rates for glucose (LCMRGlc), normalized to that of whole brain, in fully conscious, non-restrained primates. Oral FDG-PET studies were performed in both non-restrained and chaired monkeys, and in one human where results could be compared with traditional intravenous FDG administration. The oral route of FDG administration gave images and whole brain-normalized PET LCMRGlc results comparable to those obtained by the intravenous route. This oral FDG-PET method may provide a useful means by which to obtain measures of LCMRGlcs for brain structures, relative to each other, in non-restrained, non-drugged primates in field and laboratory studies. This method might also have clinical applications for PET studies of children.

Administration, Oral↗
PubMed1997

Induction of guanosine triphosphate-cyclohydrolase by follicle-stimulating hormone enhances interleukin-1 beta-stimulated nitric oxide synthase activity in granulosa cells.

In cultured granulosa cells, interleukin-1 beta (IL-1 beta) induced a time-dependent (16-72 h) and dose-related (0.3-30 ng/ml) stimulation of nitric oxide (NO) synthase (NOS) activity, as determined by the catalytic conversion of [3H]arginine to [3H]citrulline and NO2- accumulation in the culture medium. Although FSH alone failed to stimulate NOS activity, concomitant treatment with the gonadotropin (200 ng/ ml) or the cell-permeant cAMP analog (Bu)2cAMP (0.5 mM) markedly enhanced IL-1 beta-induced NO generation in cultured granulosa cells. The effect of IL-1 beta on citrulline biosynthesis and NO2- accumulation was abrogated by the NOS inhibitor NG-methyl-L-arginine or the IL-1-receptor antagonist protein. In contrast bacterial endotoxin (lipopolysaccharide), interferon-gamma, or tumor necrosis factor-alpha, which are well known inducers of inducible NOS (iNOS) in a variety of immunocompetent and nonimmunocompetent cell types, failed to increase [3H]citrulline formation or NO2- accumulation in untreated or FSH-stimulated cells. As demonstrated by reverse transcriptase-PCR analysis, IL-1 beta-stimulated NO generation was accompanied by a time-dependent increase in messenger RNA levels for iNOS and GTP-cyclohydrolase (GTPCH), the rate-limiting step for de novo tetrahydrobiopterin (BH4) biosynthesis. Treatment with FSH augmented only GTPCH messenger RNA expression, and a more than additive GTPCH signal was observed when cells were simultaneously challenged with IL-1 beta and FSH. Treatment with the GTPCH inhibitor 2,4-diamino-6-hydroxypyrimidine prevented IL-1 beta-induced NOS activity in untreated or FSH-stimulated cells, and this inhibition was completely reversed by sepiapterin, a substrate for BH4 biosynthesis, via an alternative pterin salvage pathway present in many cell types. As BH4 is an essential cofactor for NOS catalytic activity, these observations strongly suggest that FSH-induced biosynthesis of endogenous BH4 is essential for full iNOS biosynthetic capacity in IL-1 beta-stimulated granulosa cells.

Animals↗