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Biomedical subjects

M Torres

Publications and source records attributed to M Torres.

At least 145 records · Page 8Linked to original sources
PubMed1997

Effects of a copper-bearing intrauterine device on the ovarian function, body weight gain and pregnancy rate of nulliparous heifers.

A copper-bearing intrauterine device (IUD), designed to cause a slight distention of the uterus, was inserted through the cervix into each uterine horn of 230 heifers; an additional 230 heifers served as the control group. Blood was drawn at 0, 1, 2, 20 and 120 d for progesterone and testosterone assays. The heifers were checked twice daily for estrus and examined at 0, 60 and 120 d for weight gain. Thereafter they were bred over a 120-d period. The IUD caused anestrus in 98% of the heifers, with a daily weight gain 25.5 % higher than in the control heifers. Moreover, the device was 100% effective in preventing pregnancy. At 20 and 120 d after IUD insertion progesterone levels averaged 0.7 ng/ml, which was 4 to 5 times lower than in the control animals, suggesting a failure in ovulation or in corpus luteum (CL) formation due to the IUD. Simultaneously, testosterone values were increased up to 8 times in IUD-treated heifers, reaching a mean concentration of 163 pg/ml. Associated histological evaluations of the ovaries from UD-treated heifers revealed the presence of 2 or more cysts per ovary, with marked hyperthecosis in many antral follicles in which the granulosa cell layers were either thinned or lacking. The results suggest that the action of the copper-releasing IUD used in this study resulted in high contraceptive efficiency but also in disturbance of ovarian function. Our findings further raise the possibility of a cause and effect relationship between hyperandrogenism and the higher body weight gain observed in heifers treated with the IUD.

Journal Article↗
PubMed1997

WNTs modulate cell fate and behavior during vertebrate development.

Wnt genes encode a family of secreted glycoproteins that modulate cell fate and behavior in embryos through activation of receptor-mediated signaling pathways. Wnt sequences, patterns of expression and activities are highly conserved in evolution, so it has been possible to gain insights into the functions, and mechanisms of action, of the Wnt genes through a synthesis of genetic and cell biological approaches in different organisms. These studies suggest that there are functionally distinct WNT proteins as assayed by the ability to transform cells and by differences in embryonic responses to ectopic WNT signals. Moreover, gain-of-function and loss-of-function studies both support the involvement of Wnt proteins in modulating cell fate and cell behavior during vertebrate development, often through combinatorial interactions with other signaling pathways to regulate gene expression.

Animals↗
PubMed1997

Distribution of [3H]diadenosine tetraphosphate binding sites in rat brain.

The distribution of the diadenosine tetraphosphate high-affinity binding sites has been studied in rat brain by an autoradiographic method using [3H]diadenosine tetraphosphate as the ligand. The binding characteristics are comparable to those described in studies performed on rat brain synaptosomes. White matter is devoid of specific binding. The range of binding site densities in gray matter varies from 3 to 15 fmol/mg of tissue, exhibiting a widespread but heterogeneous distribution. The highest densities correspond to the seventh cranial nerve, medial superior olive, pontine nuclei, glomerular and external plexiform layers of the olfactory bulb, and the granule cell layer of the cerebellar cortex. Intermediate density levels of binding correspond to different cortical areas, several nuclei of the amygdala, and the oriens and pyramidal layers of the hippocampal formation. The localization of diadenosine tetraphosphate binding sites in the brain may provide information on the places where diadenosine polyphosphate compounds can be expected to function in the central nervous system.

Animals↗
PubMed1997

Identification of the vertebrate Iroquois homeobox gene family with overlapping expression during early development of the nervous system.

In Drosophila the decision processes between the neural and epidermal fate for equipotent ectodermal cells depend on the activity of proneural genes. Members of the Drosophila Iroquois-Complex (Iro-C) positively regulate the activity of certain proneural AS-C genes during the formation of external sensory organs. We have identified and characterized three mouse Iroquois-related genes: Irx1, -2 and -3, which have a homeodomain very similar to that of the Drosophila Iro-C genes. The sequence similarity implies that these three genes represent a separate homeobox family. All three genes are expressed with distinct spatio/temporal patterns during early mouse embryogenesis. These patterns implicate them in a number of embryonic developmental processes: the A/P and D/V patterning of specific regions of the central nervous system (CNS), and regionalization of the otic vesicle, branchial epithelium and limbs.

Amino Acid Sequence↗
PubMed1997

Prostanoids and free radicals in Cl4C-induced hepatotoxicity in rats: effect of astilbin.

A beneficial effect of flavonoids in Cl(4)C-induced hepatoxicity in rats has been reported. In this communication we have evaluated the protective effect of astilbin, an active flavonoid isolated from a crude extract of Hymenaea martiana, as well as its action on liver arachidonate metabolism in Cl(4)C-treated rats. The following groups of rats were studied: Group I = controls; Group II = Astilbine-treated animals (40 mg/Kg); Group III = Cl(4)C-treated at 1 ml/kg; Group IV = Astilbine + ClC4 and Group V = Vitamine E (50 mg/Kg) + Cl(4)C-treated animals. Histological findings, superoxide dismutase activity, lipoperoxides and prostanoid profiling studies revealed that the hepatoprotective effect of astilbine was higher than that of vitamin E. Astilbine was capable to restore lipoperoxides and tissue prostanoids to basal values.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Simulation by a diagnostic CT for the early vocal cord carcinoma.

The CT-based simulation with a 3D planning system permits the optimization of radiotherapy treatments. The goal is to obtain an increase in the local control and survival with a reduction of the treatment related toxicity. In our hospital, we do not have a CT simulator and our 3D planning system is not yet working, therefore, we have developed a system to simulate radiotherapy treatments using a diagnostic CT. We began by simulating an early vocal cord carcinoma. The rules of this simulation are presented using a clinical case as an example.

Humans↗
PubMed1997

Mycobacterium tuberculosis (MTB)-stimulated production of nitric oxide by human alveolar macrophages and relationship of nitric oxide production to growth inhibition of MTB.

SETTING: Although nitric oxide (NO) is a major proximate mediator of microbicidal activity in murine macrophages against intracellular pathogens including mycobacteria, its production by and effector role in human macrophages is not clear. OBJECTIVE: To determine the capacity of Mycobacterium tuberculosis (MTB) to stimulate NO in human monocytes (MN) and alveolar macrophages (AM) and to assess the relationship between NO production and intracellular growth of MTB. DESIGN: NO production (measured as nitrite) by MTB (H37Ra)-infected macrophages and intracellular growth of MTB were measured in cells from 17 healthy subjects. RESULTS: MTB (5:1, MTB:cells) stimulated little to no NO by MN, but induced NO in AM at days 4 and 7 after infection. There was, however, variability in the response by AM to MTB: among seven subjects MTB-induced NO was low (4 +/- 2 microM, mean +/- SE); six subjects were moderate (56 +/- 11); four subjects were high (502 +/- 167). NO synthase inhibitors inhibited the production of NO by AM but did not significantly affect the intracellular growth of MTB, although a trend towards increased intracellular growth was seen on day 4 of culture. Intracellular growth of MTB in AM from low NO producers was significantly higher than that in AM from moderate NO producers, P < or = 0.05. Inducible NO synthase (iNOS) mRNA by RT-PCR was constitutively expressed by both MN and AM, but was further stimulated by MTB in AM > MN; MTB-induced iNOS protein was present in both MN and AM by Western blot analysis. CONCLUSION: Thus, MTB-infected human AM are capable of producing NO and NO production correlates with intracellular growth inhibition of MTB in AM suggesting that NO may serve either directly or indirectly as a mycobactericidal mediator in human tissue macrophages.

Adult↗
PubMed1997

Larval microhabitats of Lutzomyia longipalpis (Diptera: Psychodidae) in an endemic focus of visceral leishmaniasis in Colombia.

An intensive search for the larval habitats of Lutzomyia longipalpis (Lutz & Neiva) was conducted from November 1992 to October 1993 at a small rural community in Colombia where American visceral leishmaniasis is endemic. Emergence traps constructed from polyvinyl chloride pipes were used to sample a variety of soil microhabitats that included edge areas of covered pigpens, cattle corrals, the base of trees, and leaf litter at sites within 40 m of a house, rocks in fields located between 50 and 500 m from houses, and sites within a patch of secondary forest (rocks, base of palm trees, and leaf litter). The teneral status of the sand flies captured in the emergence traps was confirmed by laboratory studies that determined the rate of terminalia rotation in male L. longipalpis and the rate of cuticular growth layer formation of the thoracic phragma in both sexes of this species. A total of 58 teneral sand flies was captured during the study period (49 wk). Fifteen specimens were L. longipalpis; of these 11 (5 sand flies per square meter) were captured near pigpens, 3 (1.4 sand flies per square meter) were captured near rock resting sites, and 1 (1.6 sand flies per square meter) was collected at the base of a tree. The remainder of the sand flies were either L. trinidadensis (Newstead) or L. cayennensis (Flock & Abonnenc). Our results indicate that L. longipalpis larvae were dispersed widely in sites near houses, rather than concentrated in a few optimal microhabitats.

Animals↗
PubMed1997

Assertive community treatment and medication compliance in the homeless mentally ill.

OBJECTIVE: This study describes medication compliance rates among a group of homeless mentally ill subjects who received assertive community treatment. METHOD: The medication compliance of 77 homeless persons who had been referred to an assertive community treatment program was prospectively evaluated at baseline and quarterly for 1 year. RESULTS: A minority of the cohort (29%) was compliant at entry into the assertive community treatment program. Compliance significantly increased after 3 months (57%) and remained high through the year. Medication compliance was associated with fewer psychiatric symptoms but not with better housing placements or fewer days in the hospital. CONCLUSIONS: Medication compliance rates among a cohort of homeless persons with severe mental illness were markedly higher after they entered a program of assertive community treatment.

Adolescent↗
PubMed1997

The Latino Health Advocacy Program: a collaborative lay health advisor approach.

There have been numerous calls in the literature for health educators to develop programs to improve access to and utilization of health and human services by traditionally underserved communities, including Latinos. While the literature suggests several principles that can guide the development of these programs, it is important to address the needs, and build on the strengths, of the specific community of interest. It is, therefore, important to use collaborative approaches in which community members take an active role in the initiation, design, implementation, and evaluation of program activities. Lay health advisor programs are particularly well suited to this approach as they are designed to build on the strength of already existing community relationships to improve community health. This article describes a collaborative, culturally appropriate, holistic, and ecological lay health advisor program--the Latino Health Advocacy Program. Lessons learned and implications for future program development are discussed.

Community Health Services↗
PubMed1996

The axis-inducing activity, stability, and subcellular distribution of beta-catenin is regulated in Xenopus embryos by glycogen synthase kinase 3.

The serine/threonine kinase Xgsk-3 and the intracellular protein beta-catenin are necessary for the establishment of the dorsal-ventral axis in Xenopus. Although genetic evidence from Drosophila indicates that Xgsk-3 is upstream of beta-catenin, direct interactions between these proteins have not been demonstrated. We demonstrate that phosphorylation of beta-catenin in vivo requires an in vitro amino-terminal Xgsk-3 phosphorylation site, which is conserved in the Drosophila protein armadillo. beta-catenin mutants lacking this site are more active in inducing an ectopic axis in Xenopus embryos and are more stable than wild-type beta-catenin in the presence of Xgsk-3 activity, supporting the hypothesis that Xgsk-3 is a negative regulator of beta-catenin that acts through the amino-terminal site. Inhibition of endogenous Xgsk-3 function with a dominant-negative mutant leads to an increase in the steady-state levels of ectopic beta-catenin, indicating that Xgsk-3 functions to destabilize beta-catenin and thus decrease the amount of beta-catenin available for signaling. The levels of endogenous beta-catenin in the nucleus increases in the presence of the dominant-negative Xgsk-3 mutant, suggesting that a role of Xgsk-3 is to regulate the steady-state levels of beta-catenin within specific subcellular compartments. These studies provide a basis for understanding the interaction between Xgsk-3 and beta-catenin in the establishment of the dorsal-ventral axis in early Xenopus embryos.

Amino Acid Sequence↗
PubMed1996

Activation of the mitogen-activated protein kinase pathway by fMet-leu-Phe in the absence of Lyn and tyrosine phosphorylation of SHC in transfected cells.

The chemotactic peptide f-Met-Leu-Phe (fMLP) stimulates leukocyte functions through binding and activation of a specific G-protein-coupled formyl peptide receptor (FPR). Recent studies have shown that stimulation of neutrophils with fMLP induces the activation of two members of the mitogen-activated protein kinase (MAP kinase) family, ERK1 and ERK2, through mechanisms that are not completely understood but may involve the phosphorylation of the adapter protein SHC by the Src-related kinase Lyn. In this study, transfected fibroblasts expressing the rabbit FPR were used to investigate further the role of Lyn and SHC phosphorylation in fMLP-stimulated MAP kinase activation. Stimulation of transfected cells with fMLP resulted in the time- and dose-dependent increase in tyrosine phosphorylation and activation of ERK1 and ERK2 and the activation of MEK, the MAP kinase/ERK kinase. The activation of both ERKs and MEK was inhibited by preincubation of the cells with pertussis toxin, indicating that activation was dependent upon a Gi/Go-like protein that couples to the receptor. Our data also show that, unlike neutrophils, FPR-transfected fibroblasts do not express the Src-related kinase Lyn. In the absence of Lyn, fMLP stimulation did not result in an increased tyrosine phosphorylation of the adapter protein SHC, whereas it was still able to induce MAP kinase activation. These data suggest that Lyn and SHC are not the only upstream signals for activation of the MAP kinase/ERK pathway by fMLP and demonstrate the potential application of the FPR-transfected cells for the delineation of additional signaling mechanisms stimulated by fMLP.

Adult↗
PubMed1996

No increase in micronuclei frequency in cultured blood lymphocytes from a group of filling station attendants.

Service station attendants are workers that are definitely exposed to petroleum derivatives. Taking into account that this exposure has been considered to possess genotoxic risk, here we present data on the biomonitoring of a group of 50 service station workers and 43 controls. Micronuclei (MN) from peripheral blood lymphocytes has been considered as the genetic endpoint to be studied and, in addition, data on the concentration of aromatic hydrocarbons at the workplace, urinary metabolites and differential white blood cell count have also been analysed. The results obtained indicate no significant differences between petrol station attendants and controls, when the effects of petrol exposure were investigated by differential white blood cell count and analysis of MN frequencies in phytohaemagglutinin-stimulated lymphocytes. Regarding the urinary metabolites, a significant increase in the phenol level was found in the exposed workers.

Adolescent↗
PubMed1996

Nerve growth factor induces a multimeric TrkA receptor complex in neuronal cells that includes Crk, SHC and PLC-gamma 1 but excludes P130CAS.

Binding of nerve growth factor (NGF) to the TrkA receptor results in homodimerization, and activation of the intrinsic tyrosine kinase activity of the receptor, leading to multiple phosphorylations. We investigated the in vivo formation and composition of the receptor complex induced by NGF in a central nervous system-derived cell line (B104-neo), transfected with the human cDNA for TrkA. Using receptor-activated immunoprecipitation followed by analysis of the immune complexes by SDS-PAGE and immunoblotting, we show that NGF induces the association of TrkA with c-Crk-II in a multimeric complex that also includes SHC and PLC-gamma 1. While the tyrosine phosphorylation of TrkA, SHC and PLC-gamma 1 increased with time in the presence of NGF and was inhibited by the tyrosine kinase inhibitor K252a, the state of tyrosine phosphorylation of c-Crk-II did not appear to change with NGF treatment. Immunodepletion studies demonstrated that the interaction of c-Crk-II with TrkA not only occurs indirectly through the SHC proteins, but may also involve another mode of binding. Furthermore, we show that c-Crk-II is associated with tyrosine phosphorylated p130CAS in unstimulated cells and that NGF treatment results in the de-association of p130CAS/c-Crk-II complex in the absence of an apparent change in the tyrosine phosphorylation of p130CAS. These results clearly implicate c-Crk-II in the NGF signaling pathway and support the concept that more than one signaling molecule known to participate in the activation of Ras associates with TrkA upon NGF treatment.

Cells, Cultured↗
PubMed1996

Combined low dose dipyridamole-dobutamine stress echocardiography to identify myocardial viability.

OBJECTIVES: We sought to evaluate the effects of combined administration of infra-low dose dipyridamole and low dose dobutamine on assessment of myocardial viability. BACKGROUND: Low dose pharmacologic stress echocardiography with either dobutamine or dipyridamole infusion has been proposed for the recognition of myocardial viability. METHODS: Thirty-four patients with rest wall motion dyssynergy by two-dimensional echocardiography and with angiographically proved coronary artery disease underwent in combination with two-dimensional echocardiographic monitoring: 1) low dose (5 to 10 microgram/kg per min over 3 min) dobutamine infusion; 2) infra-low dose (0.28 mg/kg over 4 min) dipyridamole infusion; 3) combination of infra-low dose dipyridamole infusion immediately followed by low dose dobutamine infusion (combined dipyridamole-dobutamine). RESULTS: Follow-up rest echocardiography was available in 30 patients. After revascularization, 82 segments showed a contractile improvement of > or = 1 grade, whereas 63 segments remained unchanged. The sensitivity of dobutamine, dipyridamole and combined dipyridamole-dobutamine for predicting recovery was 72% (95% confidence interval [CI] 60.9% to 81.3%), 67% (CI 55.8% to 77%) and 94% (CI 86.3% to 97.9%), respectively. The specificity of dipyridamole, dobutamine and combined dipyridamole-dobutamine was 95% (CI 86.7% to 99%), 92% (CI 82.4% to 97.3%) and 89% (CI 78.4% to 95.4%), respectively. The accuracy of the dobutamine, dipyridamole and combined dipyridamole-dobutamine test was 80%, 79% and 92%, respectively (combined dipyridamole-dobutamine vs. dobutamine, p < 0.05; combined dipyridamole-dobutamine vs. dipyridamole, p < 0.01). CONCLUSIONS: Infra-low dose dipyridamole added to low dose dobutamine recruits an inotropic reserve in asynergic segments that were nonresponders after either dobutamine or dipyridamole alone and destined to recover after revascularization.

Adult↗
PubMed1996

T lymphocytic and immature macrophage alveolitis in active pulmonary tuberculosis.

The phenotype of bronchoalveolar cells from 11 healthy subjects and from affected and unaffected lungs of 15 patients with pulmonary tuberculosis (PTB) was determined. An immature macrophage alveolitis was found in the affected lung and the unaffected lung versus controls as determined by morphology and peroxidase activity. T lymphocytic alveolitis also was found in the affected but not the unaffected tuberculous lung compared with healthy controls. The majority of alveolar lymphocytes in unaffected and affected PTB lungs were T cells expressing the alpha beta T cell receptor. Alveolar T cells from both unaffected and affected lungs were activated, as determined by increased expression of CD69 and HLA-DR. Interleukin-2 receptor (IL-2R alpha) expression was, however, unchanged on alveolar lymphocytes from affected lung and was decreased in the unaffected lung. Thus, activated T lymphocytes and immature macrophages in the tuberculous lung are basic to the local immunopathogenesis of PTB.

Adult↗