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Biomedical subjects

M Torres

Publications and source records attributed to M Torres.

At least 181 records · Page 10Linked to original sources
PubMed1995

Clinical validation of the new ELSA-CA 125 II assay: report of a European multicentre evaluation.

The ELSA-CA 125 II is a second-generation radioimmunoassay for the quantification of CA 125 in serum. In a multicentre study involving 49 follow-ups of patients with ovarian cancers, and 880 other patients, 2.8% of healthy persons, 25% of 149 patients with benign gynaecological diseases and 39% of 82 patients with benign non-gynaecological diseases had CA 125 levels above 35 U/ml. Using the 35 U/ml cut-off, sensitivities among epithelial ovarian cancers were found to be 85% in serous tumors, 41% in mucinous tumors and 83% in other types. During follow-up of patients with serous ovarian cancers, we observed an equivalent behaviour of both assays--first- and second-generation--with the clinical evolution. We also compared results obtained with other assays commercially available; these were significantly different when a polyclonal antibody was used in the sandwich assay.

Adolescent↗
PubMed1995

Preservation of surface-dependent properties of viral antigens following immobilization on particulate ceramic delivery vehicles.

B-cell stimulation for the purpose of evoking an effective neutralizing humoral immune response is a surface phenomenon that is exquisitely specific to antigen conformation. Consequently, successful delivery of antigen, such as would be desired in a vaccine, entails preservation of an antigen's apparent native surface (conformational) properties. Prior to testing the actual vaccinating efficacy of delivered antigens, the surface properties could be assessed through a variety of in vitro and in vivo assays in which the measurement standard would be the properties of the antigens in their native state (whole virus). Using surface modified nanocrystalline carbon and calcium-phosphate ceramic particulates (carbon ceramics and brushite), we evaluated the surface activity of immobilized non-nuclear material extracted from HIV-1. Physical characterization showed that the particles with immobilized antigen ("HIV decoys") measured 50 nm in diameter (HIV = 50-100 nm) and exhibited the same zeta potentials as whole (live) HIV. In vitro testing showed that the HIV decoys were recognized by both conformationally nonspecific and specific monoclonal antibodies, were recognized by human IgG from HIV antibody-positive patients, and could promote surface agglomeration among malignant T-cells similar to live HIV. Last, in vivo testing in three vaccinated animal species showed that the HIV decoys elicited humoral and cellular immune responses similar to that evoked by whole (live) HIV.

Animals↗
PubMed1995

Cyclic GMP-dependent protein kinase activation mediates inhibition of catecholamines secretion and Ca2+ influx in bovine chromaffin cells.

The effects of the membrane-permeable cGMP analogue, 8-bromoguanosine 3':5'-cyclic monophosphate on acetylcholine-evoked catecholamine secretion and cytosolic calcium increases were studied in chromaffin cells from the bovine adrenal gland. Preincubation with 100 microM 8-bromoguanosine 3':5'-cyclic monophosphate during 10 and 30 min decreased the acetylcholine-evoked catecholamine release by 16 +/- 3% and 27 /+- 5%, respectively. The cytosolic calcium increases triggered by acetylcholine and 30 mM KCl were also inhibited by 30 min of preincubation with this compound by 27 +/- 4 and 34 /+- 12%, respectively. Changes in membrane potential induced by acetylcholine and KCl were not affected by preincubation with 8-bromoguanosine 3':5'-cyclic monophosphate. The cyclic GMP-dependent protein kinase inhibitor N-[2-(methylamino)ethyl]-5-isoquinoline sulfonamide dihydrochloride-at l micron abolished the inhibitory effect of 8-bromoguanosine 3':5'-cyclic monophosphate on acetylcholine-evoked calcium increase. By contrast, a potent and selective inhibitor against cyclic AMP-dependent protein kinase, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide did not block the 8-bromoguanosine 3':5'-cyclic monophosphate effect. Additionally, 8-bromoguanosine 3':5'-cyclic monophosphate stimulated histone F2b phosphorylation by a partial purified cGMP-dependent protein kinase from chromaffin cells. The extent of histone phosphorylation was reduced by N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride and 8-(4-chlorophenylthio)-guanosine 3':5'-cyclic monophosphorothioate, Rp-isomer, a specific inhibitor against cyclic GMP-dependent protein kinase, whereas it was not modified by N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline sulfonamide. The results suggest that the inhibitory effects of 8-bromoguanosine 3':5' cyclic monophosphate on chromaffin cells are mediated through the activation of cGMP-dependent protein kinase.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1995

Angiotensin II receptor subtypes and phosphoinositide hydrolysis in rat adrenal medulla.

Angiotensin II (ANG) receptor subtypes were characterized by quantitative autoradiography after incubation with the ANG agonist [124I]Sar1-ANG in rat adrenal medulla. ANG receptors are highly localized in adrenal medulla. Specific binding was displaced by 4% and by 95% with the AT, receptor blocker losartan and the AT2 receptor competitor CGP 42112A, respectively. Analysis of competition curves indicated relative binding potencies for the AT2 population of CGP 42112A>PD 123319> PD 123177. ANG stimulated +-nositol phosphate formation in a dose-dependent manner in rat adrenal medulla. Losartan at concentrations of 10(-9) to 10(-5) M antagonized the effect of ANG, whereas PD 123177 or PD 123319 had no antagonistic action. However, at a higher concentration (10(-5) M) PD 123177 or PD 123319 potentiated the effect of ANG on InsP1-accumulation. In the presence of PD 123319 (10(-5) M) ANG dose-response curve was shifted to the left with no change in the maximal effect. This affect was blocked by the addition of losartan (10(-5) M). On the contrary, the addition of CGP 42112A (10(-6) M) inhibited ANG-induced increase in InsP1-accumulation. On the other hand, ANG and CGP 42112A reduced basal cyclic GMP formation, this effect was partially reverted by sodium orthovanadate, a phosphotyrosine phosphatase inhibitor. Our results further demonstrate the presence of two ANG receptor subtypes in adrenal medulla: ANG binding to AT, receptor stimulates inositol phospholipid metabolism, whereas ANG binding to AT2 receptors decreases both inositol phosphate production and cGMP formation.

Adrenal Medulla↗
PubMed1995

A survey of aflatoxins and aflatoxigenic Aspergillus flavus in corn-based products from the Spanish market.

The natural occurrence of aflatoxins B1, B2, G1 and G2, incidence of Aspergillus flavus, and capacity to produce aflatoxins by A. flavus isolates, were investigated in 100 corn-based samples from Spain destined for human and animal consumption. Only one sample for animal consumption and none for human consumption were found to be contaminated with aflatoxins B1 and B2. The levels of contamination were 0.15 micrograms/g of B1 and 0.08 micrograms/g of B2. Of 43 isolate of A. flavus, only 4 were aflatoxin producers.

Aflatoxins↗
PubMed1995

Species composition and relative abundance of sand flies of the genus Lutzomyia (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1993 at a small rural community in Colombia where American visceral leishmaniasis is endemic. Weekly sand fly collections were made from pigpens, houses, and natural resting sites, using hand-held aspirators, sticky (oiled) paper traps, and opossum-baited Disney traps. In total, 263,094 sand flies were collected; L. longipalpis predominated (86.1%), followed by L. trinidadensis (11.0%), L. cayennensis (2.7%), and 8 other Lutzomyia species. The species composition and sex ratio of these sand flies varied among sites and by collection method. L. longipalpis were captured most efficiently by direct aspiration from animal bait. Conversely, sticky paper traps, especially inside houses and at rock resting sites, collected a greater diversity of species, but a lower relative abundance of L. longipalpis.

Animals↗
PubMed1995

Seasonal abundance of Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1993 in a small rural community in Colombia where American visceral leishmaniasis is endemic. Standardized weekly sand fly collections made from pigpens and natural resting sites displayed a bimodal annual abundance cycle, with a small peak occurring in October-November and a larger one in April-May. Time series analysis was employed to quantify the associations between sand fly abundance and weather factors (temperature, relative humidity, and rainfall). In addition to a prominent 6-mo cycle. Fourier analysis of the collection data demonstrated that the L. longipalpis population also exhibited a 5- to 8-wk cycle that may represent the length of larval development. Autoregressive moving average models were fit to weekly collection data and their residuals were regressed against rainfall, temperature, and relative humidity. A significant positive association between female L. longipalpis abundance and the relative humidity and rainfall recorded 3 wk earlier was found, indicating that these factors may be of value in predicting sand fly abundance. Additionally, these data indicated that L. longipalpis larvae may become quiescent during adverse conditions.

Animals↗
PubMed1995

Nocturnal activity patterns of Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

Nocturnal activity of the sand fly Lutzomyia longipalpis (Lutz & Neiva) was studied from August 1991 to July 1992 in a small rural community in Colombia where American visceral leishmaniasis is endemic. During 2 or 3 nights each month, sand flies were collected with hand-held aspirators each hour between 1730 and 0630 hours, from a pigpen and a cattle corral located 30 m apart. Host-seeking activity of L. longipalpis adults was characterized by 2 general patterns: (1) adult sand fly activity increased shortly after sunset and continued until just after sunrise, and (2) peak sand fly activity was greatest early in the evening (1830-2330 hours) and then declined steadily toward morning. Female L. longipalpis activity generally increased after 2030 hours, whereas that of males remained constant or declined as the evening progressed. There were seasonal differences in sand fly abundance between the 2 sites: peak abundance in the cattle corral occurred during hot, dry periods, whereas maximum abundance in the pigpen occurred when relative humidity was higher. Influence of relative humidity on activity varied with season. Sand fly activity tended to decrease at temperatures below 24 degrees C and increase in the presence of moonlight.

Animals↗
PubMed1995

Age structure, blood-feeding behavior, and Leishmania chagasi infection in Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1992 in a small rural community in Colombia where American visceral leishmaniasis (AVL) is endemic. Subsamples of sand flies collected weekly from pigpens, the interior of houses, and natural outdoor resting sites were dissected to determine physiological age and Leishmania chagasi Cunha & Chagas infection rates. Eleven female L. longipalpis had flagellates in their gut, 2 of which were successfully cultured and identified as Leishmania chagasi. The reproductive status, stage of ovarian development, and trophic history of female sand flies varied among sites, habitats, and time of collection. The percentage of parous females ranged from about one-third to two-thirds overall and varied seasonally. Of most relevance to AVL transmission was the finding that 8% of L. longipalpis females were multiparous. In addition, our data suggest that L. longipalpis rest inside houses after blood-feeding outdoors, and that this species can blood-feed more than once during a single gonotrophic cycle.

Aging↗
PubMed1995

Pickled onion-induced asthma: a model of sulfite-sensitive asthma?

BACKGROUND: Asthma elicited by sulfite ingestion has been mainly described in steroid-dependent and in non-atopic asthmatics. We have studied a group of 18 young extrinsic asthmatics who presented with asthma attacks immediately after eating pickled onions. OBJECTIVE: The aim of this study is to ascertain if these asthma attacks are elicited by sulfites contained in pickled onions and the influence of the dose and pH of onions. METHODS: The bronchial hyperreactivity of the patients was assessed by a methacholine challenge test. Oral challenge tests were performed with sodium metabisulfite (MSB) diluted in lemon juice at pH 4.2 and at pH 3.3 (only in patients who did not react with pH 4.2). Two types of pickled onions, Spanish and Dutch pickled onions, were used for oral challenge in seven of the patients. The Monier-Williams method was used to measure the SO2 concentration in pickled onions. RESULTS: The oral provocation test with MBS, pH 4.2, elicited a positive response in six patients (33.3%) and the test at pH 3.3 was positive in three out of 12. No significant difference in PD20 values was found between these groups. Three of the seven patients challenged with Spanish pickled onions had a positive reaction but had no reaction with Dutch pickled onions. The SO2 concentration in Spanish pickled onions varied between 765 and 1182 ppm while in Dutch pickled onions were 200 ppm; this exceeded the permitted level (100 ppm). SO2 release in Spanish pickled onion samples was nearly 2.5 times higher when the pH of the sample decreased from 4.2 to 3.3. CONCLUSION: High levels of SO2 in Spanish pickled onions, and their low pH (3.3) would be the responsible factors of the asthmatic outbreaks after ingestion of Spanish pickled onions by these patients.

Adolescent↗
PubMed1995

Ca(2+)-independent nitric oxide synthase activity in human lung after cardiopulmonary bypass.

BACKGROUND: Because surgery involving cardiopulmonary bypass induces a systemic inflammatory response, the effect of cardiopulmonary bypass on nitric oxide (NO) generation was investigated in human lung tissue. METHODS: Nitric oxide synthase (NOS) activity was measured by the conversion of 14C-L-arginine to 14C-L-citrulline in tissue biopsy samples obtained before and after cardiopulmonary bypass. RESULTS: The Ca(2+)-independent production of NO found before cardiopulmonary bypass was extremely low (1.5 (0.5) pmol citrulline/mg/min), but was increased after the bypass operation (23.6 (11) pmol/mg/min). CONCLUSIONS: Ca(2+)-independent NOS activity was detected in human lung after cardiopulmonary bypass. This finding may provide an important insight into the pathogenesis of the tissue damage and acute phase response observed after such surgery.

Amino Acid Oxidoreductases↗
PubMed1995

Pax-2 controls multiple steps of urogenital development.

Urogenital system development in mammals requires the coordinated differentiation of two distinct tissues, the ductal epithelium and the nephrogenic mesenchyme, both derived from the intermediate mesoderm of the early embryo. The former give rise to the genital tracts, ureters and kidney collecting duct system, whereas mesenchymal components undergo epithelial transformation to form nephrons in both the mesonephric (embryonic) and metanephric (definitive) kidney. Pax-2 is a transcriptional regulator of the paired-box family and is widely expressed during the development of both ductal and mesenchymal components of the urogenital system. We report here that Pax-2 homozygous mutant newborn mice lack kidneys, ureters and genital tracts. We attribute these defects to dysgenesis of both ductal and mesenchymal components of the developing urogenital system. The Wolffian and Müllerian ducts, precursors of male and female genital tracts, respectively, develop only partially and degenerate during embryogenesis. The ureters, inducers of the metanephros are absent and therefore kidney development does not take place. Mesenchyme of the nephrogenic cord fails to undergo epithelial transformation and is not able to form tubules in the mesonephros. In addition, we show that the expression of specific markers for each of these components is de-regulated in Pax-2 mutants. These data show that Pax-2 is required for multiple steps during the differentiation of intermediate mesoderm. In addition, Pax-2 mouse mutants provide an animal model for human hereditary kidney diseases.

Animals↗
PubMed1995

Targeted mutation of the murine goosecoid gene results in craniofacial defects and neonatal death.

The goosecoid gene encodes a homeodomain-containing protein that has been identified in a number of species and has been implicated in a variety of key developmental processes. Initially suggested to be involved in organizing the embryo during early development, goosecoid has since been demonstrated to be expressed during organogenesis-most notably in the head, the limbs and the ventrolateral body wall. To investigate the role of goosecoid in embryonic development, we have inactivated the gene by gene targeting to generate mice mutant for the goosecoid gene. Mice that are homozygous for the goosecoid mutation do not display a gastrulation phenotype and are born; however, they do not survive more than 24 hours. Analysis of the homozygotes revealed numerous developmental defects affecting those structures in which goosecoid is expressed during its second (late) phase of embryonic expression. Predominantly, these defects involve the lower mandible and its associated musculature including the tongue, the nasal cavity and the nasal pits, as well as the components of the inner ear (malleus, tympanic ring) and the external auditory meatus. Although the observed phenotype is in accordance with the late expression domains of goosecoid in wild-type embryos, we suggest that the lack of an earlier phenotype is the result of functional compensation by other genes.

Animals↗
PubMed1995

Synthesis of (+/-)-1-amino-6,7,8,8a-tetrahydro acenaphthene with possible central dopaminergic activity.

We describe the non stereoselective synthesis of (+/-)-1-amino-6,7,8,8a-tetrahydroacenaphthene (14), a novel compound that belongs to the acetanaphtene group, that is presented as a rigid non hydroxylated 2-aminoindan which has a structural disposition of a dopaminergic pharmacophore that possess a phenylethylamine fragment. Intracerebroventricular administration of this compound induces an increase in urinary volume and sodium excretion in conscious rats. The renal actions of 14 were blocked by haloperidol pretreatment, suggesting that 14 acts centrally through a dopaminergic mechanism.

Acenaphthenes↗
PubMed1994

Modulation of the dihydropyridine-insensitive Ca2+ influx by 8-bromo-guanosine-3':5'-monophosphate, cyclic (8-Br-cGMP) in bovine adrenal chromaffin cells.

Pretreatment of chromaffin cells with the permeable analogue of cGMP, 8-Br-cGMP (100 microM), leads to a reduction (35%) of depolarization-evoked intracellular calcium concentration ([Ca2+]i) increases. There is evidence that bovine adrenal chromaffin cells are provided with both dihydropyridine-sensitive and -resistant voltage-sensitive Ca2+ influx pathways. Combined incubations with nifedipine 10 microM and 8-Br-cGMP reduced KCl-evoked intracellular Ca2+ concentration to a greater extent that each compound separately. Moreover, 8-Br-cGMP failed to affect the [Ca2+]i transient induced by the L-type Ca2+ channel agonist Bay K 8644 (1 microM) under conditions of low depolarization. Neomycin (0.2 mM) and omega-AgaToxin-IVA (AgTx) (1 microM) inhibited the calcium transient to a similar extent, and this inhibition was not enhanced by the presence of 8-Br-cGMP. It is concluded that 8-Br-cGMP modulated the dihydropyridine-insensitive Ca2+ influx pathway in the chromaffin cell.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗