Search PubMed⌕ Search

Biomedical subjects

A Flores

Publications and source records attributed to A Flores.

At least 91 records · Page 5Linked to original sources
PubMed1996

Quinolinic acid neurotoxicity: in vivo increased copper and manganese content in rat corpus striatum after quinolinate intrastriatal injection.

Copper and manganese, two essential metals involved in physiological and physiopathological processes in the brain, were measured in corpora striata of rats 7 days after intrastriatal injection of quinolinic acid (QUIN, 240 nmol/l microliters), an N-methyl-D-aspartate (NMDA) receptor agonist with toxic activity. Seven days after QUIN administration, copper and manganese contents were assessed by graphite furnace atomic absorption spectrophotometry. Total copper content was increased by 152% in QUIN-treated rats (18.74 +/- 2.05 micrograms/g) as compared to control animals (7.44 +/- 1.15 micrograms/g), whereas manganese striatal levels were enhanced by 35% (0.30 +/- 0.02 microgram/g) vs. control values (0.22 +/- 0.02 microgram/g). Quinolinate-induced striatal increase in copper and manganese levels were prevented by 23% (9.18 +/- 1.43 micrograms/g) and -0.45% (0.22 +/- 0.03 microgram/g) vs. control values, respectively, in rats pretreated with an NMDA receptor antagonist, dizocilpine (MK-801, 10 mg/kg, i.p.), 60 min before QUIN administration. As an index of QUIN neurotoxicity, striatal GABA levels were also measured 7 days after QUIN injection. GABA content was decreased by-55% in QUIN-lesioned rats (96.37 +/- 8.92 micrograms/g), whereas MK-801 was able to block QUIN-induced GABA depletion by 2% (219.37 +/- 10.60) vs. control values (214.2 +/- 21.88 micrograms/g). These findings suggest that increased concentrations of transition metals can be mediated by selective overactivation of NMDA receptors and might be a consequence of neural loss as well as glial response to damage.

Analysis of Variance↗
PubMed1996

Surgical evaluation and management of refractory constipation in older children.

Chronic constipation is a common childhood problem that accounts for 3% to 5% of pediatric visits and 10% to 25% of referrals to pediatric gastroenterologists. The etiology of constipation can be elusive, and extensive investigation often fails to identify a specific cause. The authors conducted a 5-year retrospective review of the patients referred for deep transanal rectal biopsy to determine the usefulness of this procedure in the evaluation and subsequent surgical management of refractory constipation. Specimens obtained by transanal rectal biopsy established a diagnosis for 30 of the 70 patients, and 17 of these 30 had subsequent procedures in the treatment of their constipation. The authors conclude that transanal rectal biopsy identifies a significant number of patients with previously unidentified neuroenteric disorders who may benefit from additional surgery in the treatment of constipation refractory to medical management.

Biopsy↗
PubMed1996

Changes in transition metal contents in rat brain regions after in vivo quinolinate intrastriatal administration.

Total copper and manganese contents were measured in five rat brain regions 7 days after a unilateral striatal injection of quinolinic acid (QUIN, 240 nmol/ 1 microliter), an endogenous N-methyl-D-aspartate (NMDA) receptor agonist. Concentrations of both transition metals were evaluated in tissue of brain cortex, hippocampus, corpus striatum, midbrain and cerebellum of saline- and QUIN-treated rats using graphite furnace atomic absorption spectrophotometry. Increases in copper content were observed after QUIN striatal injection in cerebellum, hippocampus, midbrain and corpus striatum (37, 55, 71 and 152% as compared against control values, respectively) but not in brain cortex. Manganese levels were found enhanced only in corpus striatum of QUIN-treated rats by 35% vs. control values, but not in all other brain regions analyzed. QUIN-induced increases in regional copper content were partially prevented in hippocampus, midbrain and striatum (17, 57, and 23% vs. control, respectively) by pretreatment of rats with an NMDA receptor antagonist, dizocilpine (MK-801, 10 mg/kg, i.p.), administered 60 min before QUIN microinjection. The same protective effect of dizocilpine was observed against QUIN-induced enhancement of striatal manganese content (-0.45% vs. control). These findings resemble those changes observed in postmortem Huntington's disease brains and suggest that alterations in regional content of copper, but not in manganese, may be a consequence of the spreading of QUIN-induced neurotoxic events into the striatal tissue to the neighboring regions of the brain, by action of QUIN on NMDA receptors.

Animals↗
PubMed1996

[Decubitus ulcers ... again and always].

This article is the result of a comparative study during 1994 and 95 concerning escar prevalence in our Nephrology intensive care unit. Combined paramedical and medical activities concerning preventive and curative care, structured assessment (...), made it possible to decrease escar' prevalence from 19% (1994) to 12% (1995).

Bedding and Linens↗
PubMed1995

Retinoid cycling proteins redistribute in light-/dark-adapted octopus retinas.

In cephalopods, the complex rhodopsin-retinochrome system serves to regenerate metarhodopsin and metaretinochrome after illumination. In the dark, a soluble protein, retinal-binding protein (RALBP), shuttles 11-cis retinal released from metaretinochrome located in the photoreceptor inner segments to metarhodopsin present in the rhabdoms. While in the rhabdoms, RALBP delivers 11-cis retinal to regenerate rhodopsin and in turn binds the all-trans isomer released by metarhodopsin. RALBP then returns all-trans retinal to the inner segments to restore retinochrome. The conventional interpretation of retinoid cycling is contradicted by immunocytochemical studies showing that, in addition to rhodopsin, retinochrome is present in the rhabdomal compartment, making possible the direct exchange of chromophores between the metapigments with the potential exclusion of RALBP. By using immunofluorescence and laser scanning confocal microscopy, we have precisely located opsin, aporetinochrome, and RALBP in light-/dark-adapted octopus retinas. We found differences in the distribution of all three proteins throughout the retina. Most significantly, comparison of cross sections though light- and dark-adapted rhabdoms showed a dramatic shift in position of the proteins. In the dark, opsin and retinochrome colocalized at the base of the rhabdomal microvilli. In the light, opsin redistributed along the length of the microvillar membranes, and retinochrome retreated to a location that is perhaps extracellular. RALBP was present in the core cytoplasm of the photoreceptor outer segments in the dark, and RALBP moved to the periphery in the light. Because of the colocalization of opsin and retinochrome in the dark, we believe that the two metapigments participate directly in chromophore exchange. RALBP may serve to transport additional chromophore from the inner segments to the rhabdoms and may not be immediately involved in the exchange process.

Adaptation, Ocular↗
PubMed1995

[Granulocytic sarcoma: a study of 5 cases].

Granulocytic sarcoma (GS) is a solid tumor of extramedullary localization constituted by immature precursors from the granulocytic series. GS may be diagnosed in different malignant blood diseases involving the granulocytic series, acute non lymphoblastic leukemia (ANLL) being the most frequent, followed by myelodysplastic syndromes (MDS) and chronic myeloproliferative syndromes, specially chronic myeloid leukemia (CML) in blastic crisis. Although the diagnosis of GS is suspected with conventional cytologic and anatomopathologic studies, histochemical staining and immunohistochemical techniques are often required for definitive diagnosis. Five cases (4 males, 1 female; age range 22-77 years) diagnosed with GS in one center over a period of nine years (1984-1993) are described. The GS were located in the lymph nodes, the jaw, paravertebral region, gallbladder and retroperitoneum, respectively. Two patients had refractory anemia with excess of blasts (RAEB). Three patients had ANLL; in one GS constituted the form of relapse, in another GS presented at the time of diagnosis and in the remaining patient GS preceded the diagnosis of ANLL. All the patients died from 2 to 8 months after diagnosis of GS with no response to treatment being observed. Immunohistochemical study of the tumor was performed in 4 patients, being positive for lysozyme and the monocytic MAC-387 monoclonal antibody. Immunocytochemical study of the tumor blasts was carried out with positivity for CD15 being observed. Although uncommon, GS should be suspected in patients with ANLL or MDS with tumors of any localization and at any time during its evolution. Immunocytochemical and immunohistochemical studies are of great value to differentiate GS from other tumors, particularly anaplastic non Hodgkin's lymphomas.

Adult↗
PubMed1995

[Primary extralymphatic non-Hodgkin's lymphomas: the response to treatment and prognostic factors in 73 patients].

BACKGROUND: The aim of the present study was to determine the prognostic factors for treatment response, relapse-free survival (RFS) and overall survival (OS) in a series of 73 patients with primary extranodal lymphomas (PEL). METHODS: All the patients diagnosed with PEL in one center from January 1984 to December 1993 were studied. The Working Formulation was used for histologic classification and the stage was determined according to the Ann Arbor classification modified by Mushoff. Age, sex, localization of the lymphoma, the presence of B symptoms, the existence of bulky disease, human immunodeficiency virus (HIV) infection, the main hematological and biochemical parameters, the histologic grade of malignancy, the immunologic phenotype and stage were reported. Univariate and multivariate analyses of prognostic factors for complete response (CR), RFS and OS were carried out. RESULTS: The most frequent localization of PEL was the gastrointestinal tract (43 cases). Fourteen cases had HIV infection. CR was obtained in 37 out of the 55 patients (67%) of whom 8 (21%) had relapsed. Serum LDH level was the main prognostic factor for CR attainment (p = 0.01). The variables which negatively affected RFS were the presence of HIV infection (p = 0.02), advanced age (p = 0.018) and the existence of B symptoms (p = 0.02). OS was shorter in patients with high LDH levels (p = 0.004) and more aggressive histologic subtype (p = 0.0002). CONCLUSIONS: The prognostic factors observed in the patients with primary extranodal lymphomas are the same as those found in nodal non Hodgkin's lymphomas. The stage is not a factor of bad prognosis if chemotherapy is included in the treatment.

Adult↗
PubMed1995

Suppression of the pleiotropic effects of HisH and HisF overproduction identifies four novel loci on the Salmonella typhimurium chromosome: osmH, sfiW, sfiX, and sfiY.

Insertion mutations that suppress some or all the pleiotropic effects of HisH and HisF overproduction were obtained by using transposons Tn10dTet and Tn10dCam. All suppressor mutations proved to be recessive, indicating that their effects were caused by loss of function; thus, the suppressors identify genes that are necessary to trigger the pleiotropic response when HisH and HisF are overproduced. Genetic mapping of the suppressor mutations identifies four novel loci on the Salmonella typhimurium genetic map. Mutations in osmH (min 49) behave as general suppressors that abolish all manifestations of the pleiotropic response. Mutations in sfiY (min 83) suppress cell division inhibition and thermosensitivity but not osmosensitivity. Mutations that suppress only cell division inhibition define another locus, sfiX (min 44). A fourth novel locus, sfiW (min 19), is also involved in cell division inhibition. The phenotype of sfiW mutations is in turn pleiotropic: they suppress cell division inhibition, make S. typhimurium unable to grow in minimal media, and cause slow growth and abnormal colony and cell shape. The inability of sfiW mutants to grow in minimal medium cannot be relieved by any known nutritional requirement or by the use of carbon sources other than glucose. The hierarchy of suppressor phenotypes and the existence of epistatic effects among suppressor mutations suggest a pathway-like model for the Hisc pleiotropic response.

Alleles↗
PubMed1995

Effects of calcium soaps of fatty acids on postpartum reproductive activity in beef cows and growth of calves.

Beef cows were used to determine the influence of calcium soaps of fatty acids (CSFA) incorporated in a range supplement on postpartum reproductive characteristics and growth of calves. Cows were assigned randomly to receive 0 (C, n = 68) or 125 g/d of CSFA (M, n = 66). Diets were isonitrogenous (23%) and were used during 105 d, beginning at 61 +/- 36 d (range) precalving. Two blood samples were collected monthly (7-d intervals). Weights of calves at 35, 50, and 90 d of age and weaning weight adjusted to 200 d of age were greater in M than in C (46.8 vs 43.8 kg, P < .05; 56.0 vs 50.6 kg, P< .01; 98.8 vs 91.8 kg, P < .01; and 186 vs 173 kg, P < .01, respectively). Body weights at 35 and 50 d postcalving were greater in M than in C cows (334 and 310 kg, P < .01; 329 and 300 kg, P < .01, respectively). A similar tendency was observed in body condition scores in the same postpartum periods (4.1 vs 3.4, P < .01 and 3.6 vs 2.5, P < .01 for M and C, respectively). Concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, and triglycerides were greater (P < .01) in M than in C cows. Percentage of cycling (progesterone > 1 ng/mL) cows at 30 to 90 d postpartum was 38% in M and 22% in C (P < .02). Percentage of pregnant cows during the first half of the breeding season was greater (P < .02) in M (62.5%) than in C cows (35.5%). We concluded that CSFA incorporated in a range supplement during pre- and postpartum periods improved reproductive efficiency and growth of calves.

Aging↗
PubMed1995

[Changes in lipoprotein(a) after heart transplantation].

AIM: The purpose of this study was to analyze the evolutionary changes of lipoprotein (a) levels occurring in heart transplant and to evaluate the possible relationship between the plasma concentration of this lipoprotein and the immunosuppressor drugs normally used in this type of transplant. METHOD: 17 patients undergoing heart transplant and with no history of dyslipemia or dysglucemia were studied. Patients with metabolic alterations after the transplant were excluded (except when these alterations occurred during the first week), as well as those who showed intercurrent processes near to the determinations. These were performed before the transplant, and 1, 2, 4 and 6 months later. RESULTS: An increase of lipoprotein (a) was observed after the transplant, with a subsequent progressive decrease. Significant differences were found between the levels prior to the transplant (9.18 +/- 8.66) and 6 months later (7.53 +/- 8.86), with no differences found between the previous concentrations and the determinations after one month (10.29 +/- 7.58), two months (8.06 +/- 7.90) and four months (8.82 +/- 7.84). Differences were also observed between the values of the first month in relation to the subsequent months, as well as between the 4th and the 6th month. No relationship was noticed between the levels of this lipoprotein and those of cyclosporin (r = 0.10), azatioprine (r = 0.17) and deflazacort (r = 0.19). CONCLUSIONS: The lipoprotein (a) levels increase after heart transplant, with a subsequent gradual decrease even below the previous figures. These levels bear no relationship with the dose of immunosupressors normally used in heart transplant.

Aged↗
PubMed1995

Effects of selected synthetic compounds on growth of Mucor rouxii.

The in vitro activity of four synthetic compounds was tested on fungal cells from Mucor rouxii. The compounds included phenylenediamine, two phenolamines, and quinone. At the concentrations tested (10(-2)-10(-4)M) the compounds exhibited antifungal activity, with the exception of quinone. On the basis of their effects on spore germination, and development of hyphae, phenylenediamine was the more active. The mechanism of action of the compounds is still unknown, but hyphae show morphological alterations and disturb the distribution of calcofluor in the cell wall. This suggests variations in the genesis of the cell wall.

Aniline Compounds↗
PubMed1994

NMDA-mediated potentiation of the afferent synapse in the inner ear.

In an isolated vestibular organ preparation from the axolotl (Ambystoma tigrinum), glycine (10-0.01 microM) perfusion had no effect in the resting control condition, but significantly modified the response of afferent fibres to mechanical stimuli, producing a slowly increasing discharge rate during sinusoidal mechanical stimulation periods. This action was dependent upon the stimulus duration and was antagonized by 7-chloro-kynurenic acid (7-ClKyn), 2-amino-5-phosphonopentanoic acid (AP5), N-allyl-nor-metazocina (MK-801) and extracellular magnesium. These results indicate that glycine modulates the afferent synapse in the vestibular organ, and that, NMDA receptors codify long lasting mechanical stimuli.

2-Amino-5-phosphonovalerate↗
PubMed1994

Evidence for NMDA receptor in the afferent synaptic transmission of the vestibular system.

This study aimed to define the pharmacology and physiological role of the N-methyl-D-aspartate (NMDA) receptor in the synapse between the hair cells and primary afferent neurons in the vestibular system. The spontaneous and mechanically evoked spike discharges of vestibular nerve fibers were extracellularly recorded in isolated inner ear from the axolotl (Ambystoma tigrinum). Pressure ejection of NMDA (10(-6) to 10(-3) M) elicited a dose-dependent increase of the basal spike discharge from the vestibular nerve fibers. Extracellular magnesium antagonized the NMDA effect in a dose-dependent manner. D(-)-2-amino-5-phosphonovaleric acid (AP5, 10(-5) to 10(-3) M) and 7-chloro-kynurenic acid (7ClKyn, 10(-6) to 10(-3) M) inhibited the basal activity of the vestibular nerve fibers. 7ClKyn also diminished the responses elicited by the mechanical stimulation of the preparation. Glycine (10(-9) to 10(-6) M) applied by bath substitution enhanced the NMDA response, and the glycine agonist D-serine partially reversed the 7ClKyn inhibitory action. These results suggest that NMDA receptors participate in the generation of the basal spike discharge of vestibular system primary afferent neurons, but its activation is not critical for the response to brief mechanical stimuli.

2-Amino-5-phosphonovalerate↗
PubMed1994

New methods in Salmonella genetics.

This review summarizes several recent developments in Salmonella genetics; some of the procedures described can be easily adapted to Escherichia coli and have also potential applications in non-enteric bacteria. The novel methods outlined include genetic mapping procedures, ancillary tools for cloning, a strategy for analyzing DNA-protein interactions in vivo, a method for plasmid curing and a procedure for the detection of bacterial virulence genes.

Bacteriophage P22↗
PubMed1994

[Non-Hodgkin's lymphomas in patients with human immunodeficiency virus infections. Clinicopathologic characteristics, treatment response and prognosis in 40 patients].

BASIS: Non-Hodgkin lymphoma (NHL) is one of the commonest neoplasms appearing in subjects infected by the human immunodeficiency virus (HIV). The purpose of this work was to analyse the clinical and laboratory characteristics, along with the clinical course, response to therapy and prognosis in a series of 40 patients with NHL and HIV infection treated in a single institution between 1985 and 1993. METHODS: The following variables at onset were analysed: age, sex, risky behaviour, NHL location, presence of "B" symptoms, haemoglobin value, platelet count, total number of lymphocytes and CD4-positive lymphocyte count, erythrocyte sedimentation rate, LDH levels, serum albumin, beta 2-microglobulin, NHL type and staging. The following variables during follow-up were also examined: treatment administered, achievement of remission and remission duration, date of relapse and death or date of the last control, relapse-free survival (RFS) and overall survival (OS). A multivariate study of the prognostic factors associated to the achievement of remission, RFS and OS were carried out as well. RESULTS: The frequency of NHL amongst the HIV-positive subjects was 4.4%. Thirty cases had high-grade lymphoma, 20 were stage IV and 33 had extranodal locations. Anaemia was the commonest blood impairment and CD4-positive lymphocyte count was below 0.2 x 10(9)/L in 72% of the cases. Twenty-eight patients with systemic NHL received chemotherapy (CHOP in 25 instances, MACOP-B in 3), and of them 6 were alive, 5 in maintained remission, as for this paper's writing. The median RFS was 7 months and the median OS was 11 months. Increased serum LDH was associated with lesser probability of attaining both remission (p = 0.03) and RFS (p = 0.03). Response to therapy was the main factor in determining survival (p = 0.002); after excluding such factor, increased serum LDH and low serum albumin rates correlated negatively with OS (p = 0.004 and p = 0.007, respectively). CONCLUSIONS: HIV-positive patients, when affected by NHL, usually have high-grade lymphoma, frequently in advanced stages and with extra-nodal involvement. They show poor response to therapy. Increased serum LDH level is the main prognostic factor.

Adult↗
PubMed1994

[Marrow hypoplasia associated with congenital dyskeratosis. Case report].

Congenital dyskeratosis is a rare disease involving ectodermal derived tissues and presenting bone-marrow hypoplasia as a complication in one half of the cases. A 25 year-old male is presented who at age 12 showed retarded development with shortness of the 4th finger of his left hand, anomalous implantation of teeth, hyperpigmented skin and hyperkeratosis on his knees, hands and feet. He had anaemia (Hb 92 g/L) and leucopenia (2.7 x 10(9)/L) with neutropenia (0.34 x 10(9)/L) and his bone-marrow showed hypoplasia, especially affecting granulopoiesis. The cytogenetic studies were normal. No treatment was given, and a haematological re-evaluation performed 13 years later showed no significant quantitative changes. Decreased number of myeloid and megakaryocytic colonies were present in the bone-marrow cultures. The clinical and laboratory characteristics of the bone-marrow aplasia associated to congenital dyskeratosis are commented, stress being laid on its differentiation from other constitutional forms of aplasia, especially Fanconi's anaemia.

Adult↗