Search PubMed⌕ Search

Biomedical subjects

E Alvarez

Publications and source records attributed to E Alvarez.

At least 55 records · Page 3Linked to original sources
PubMed2001

Chromosome studies of murine T-cell lymphoid leukemia and derived cell lines.

Several cell lines were previously established from a spontaneous murine T-cell leukemia (LB). The aim of this study was to analyze the G- and C-banded karyotypes of the parental LB tumor cells and the derived cell lines. A sensitive cell line (LBL) from which two sublines originated, as well as Vincristine (LBR-V160) and Doxorubicin (LBR-D160) resistant cell lines, were used. Our results showed that LB cells had a pseudo-diploid karyotype with 40 acrocentric chromosomes in which trisomy of chromosome 14 was the most relevant alteration. The sensitive cell line showed this alteration in all metaphases studied; no changes in karyotypes were observed in either subline, despite their dissimilar morphology and growth patterns. In contrast, both resistant lines displayed a more heterogeneous karyotype with no common markers, except for the finding that chromosome 5 was involved in a trisomy in LBR-V160 and in a translocation with chromosome 12 in LBR-D160. Taking into account that the mdr genes are located in chromosome 5, these results suggest a possible association between such alterations and the acquisition of drug resistance.

Animals↗
PubMed2001

Ovine Echinococcus granulosus transmission dynamics in the province of Rio Negro, Argentina, 1980-1999.

In this work, the impact of a hydatidosis control programme for dogs on the intermediate ovine host was specifically analysed to determine the levels of prevalence achieved and the dynamics of parasite transmission, as well as to evaluate the quality of diagnostic systems in slaughterhouses. A field study was conducted in four slaughterhouses (Valcheta, Los Menucos, Jacobacci, Bariloche) that process animals coming from all the departments within the work area. The control programme for dogs entailed treating dogs with 5 mg/kg praziquantel at 2-month intervals for 20 years. Sample size was determined with a 10% error margin and a 95% significance level. Harvested viscera (liver, lungs, kidneys) were preserved in 5% formaldehyde and sent to the laboratory for diagnostic confirmation of both positive and negative specimens. The 61% initial prevalence dropped to 18.3% at the end of the 10-year period, observed differences proving significant (Chi-square=15.454, P=0.00). There were statistically significant increases in infection prevalence with age (Pearson's Chi-square=133.61, P=0.00). Overall, 37.2% of hydatidosis cases diagnosed in slaughterhouses were considered non-hydatid by histological study. On the other hand, 1.1% of those diagnosed as healthy were found to be infected with hydatidosis. The number of hydatid cysts per animal increased with age: 0.04 in lambs and 1.22 in adults (linear regression equation, -0.0539+0.0127 x age), whereas the average for the whole period was 3.7% in lambs and 20.5% in adults. Viability studies indicated that 63.8% of parasitised animals had viable cysts, out of which 53.3% were fertile. Diagnosis of infection in sheep made by means of an adjusted statistical design and with histological confirmation of the presumptive diagnosis made in slaughterhouses demonstrated the flaws of the official systems for epidemic surveillance of hydatidosis. However, there was no overall significant difference in slaughterhouse and laboratory data.Ro was 0.53 and could imply a decrease in reproductive capacity of the parasite and steady state extinction.

Abattoirs↗
PubMed2001

N-(3-(aminomethyl)benzyl)acetamidine, an inducible nitric oxide synthase inhibitor, decreases colonic inflammation induced by trinitrobenzene sulphonic acid in rats.

Gastrointestinal inflammation has been associated with an increased generation of nitric oxide (NO) and the expression of the inducible NO synthase (iNOS). Using an experimental model of colitis induced by trinitrobenzene sulphonic acid (TNBS), we sought to determine whether the administration of N-(3-(Aminomethyl)benzyl)acetamidine (1400W), a specific inhibitor of iNOS, has a beneficial action on the colonic injury. 1400W (0.4 and 2 mg/kg/day) was administered intraperitoneally from day 5 to 10 after intrarectal instillation of TNBS. TNBS led to colonic ulceration and inflammation, an increase of colonic myeloperoxidase activity and the expression of the calcium-independent NOS from days 1 to 15. 1400W reduced the macroscopic damage and the histological changes induced by TNBS as well as the calcium-independent NOS activity and myeloperoxidase activity determined over 30 min after sacrifice. These findings indicate that the expression of iNOS accounts for most of the damage caused by TNBS and that the administration of 1400W after the onset of colitis has a beneficial action on the colonic injury.

Amidines↗
PubMed2001

SPECT mapping of cerebral activity changes induced by repetitive transcranial magnetic stimulation in depressed patients. A pilot study.

Repetitive transcranial magnetic stimulation (rTMS) is being investigated as an alternative treatment for depression. However, little is known about the clinical role and the neurophysiological mechanisms of the action of rTMS in these patients. In this study, 99mTc-HMPAO single photon emission computed tomography (SPECT) was used to map the effects of left dorsolateral prefrontal rTMS on prefrontal activity in seven patients who met DSM-IV criteria for major depression resistant to pharmacological treatment. rTMS consisted of 30 trains of 2-s duration stimuli (20 Hz, 90% of motor threshold), separated by 30-s pauses. Each patient underwent three SPECTs: at baseline; during the first rTMS; and 1 week after 10 daily sessions of rTMS. Regional cerebral blood flow (rCBF) of each cerebral region was normalized to the rCBF value in the cerebellum and relative changes in normalized rCBF were addressed using a region-of-interest analysis. The Hamilton Depression Rating Scale (HDRS) was used for clinical evaluation before and after rTMS. A significant rCBF increase after the 10 sessions of rTMS was found in the left prefrontal region (MANOVA F=5.29, d.f.=2,10, P=0.027), but no significant rCBF changes were found during the first rTMS session. The remaining cerebral regions showed no significant rCBF changes at any time. Only two patients showed a clinical improvement after rTMS, with 50% reduction of the initial HDRS score. The study was repeated under placebo conditions (identical design but addressing coil discharges to the air) in these two patients, who failed to show any rCBF increase during sham-rTMS. No relationship was found between the percentage of left prefrontal rCBF change and the clinical findings. In conclusion, rTMS of the left prefrontal cortex induces a significant rCBF increase in this region, despite the limited clinical effect in our sample of depressed patients. Cerebral perfusion SPECT is a useful tool to map cerebral activity changes induced by rTMS.

Adult↗
PubMed2001

Dynamics of glyphosate and aminomethylphosphonic acid in a forest soil in Galicia, north-west Spain.

Residues of the herbicide glyphosate (N-phosphonomethylglicine) and its main metabolite, aminomethylphosphonic acid (AMPA), were determined in a forest soil in north-west Spain, previously treated with 5 and 8 l ha(-1) of glyphosate. Both products were monitored in the solid and liquid soil phases for an 8-week period after the treatment. Soil samples were extracted by KH2PO4. Concentrated extracts and liquid phase samples were derivatized with 9-fluorenylmethyl chloroformate (FMOC) before determination by HPLC using an anion exchange column and spectrofluorometric detection. The treated soil peaked at 6.9 microg g(-1) of glyphosate, whereas soil water samples peaked at 0.74 microg ml(-1) of glyphosate. One month after the treatment, both glyphosate and AMPA concentrations in soil and water samples were almost negligible. AMPA peaked at 0.77 microg ml(-1) in soil water samples. Glyphosate and AMPA exhibited high vertical mobility in the treated soil, quickly reaching high concentrations in subsurface horizons where the degradation is slower.

Environmental Monitoring↗
PubMed2001

Identification and characterization of UDP-N-acetylenolpyruvylglucosamine reductase (MurB) from the Gram-positive pathogen Streptococcus pneumoniae.

The UDP-N-acetylenolpyruvylglucosamine reductase (MurB) from a Gram-positive pathogen, Streptococcus pneumoniae, was identified and characterized. The enzyme from S. pneumoniae shows 31% identity with the MurB protein from Escherichia coli, and contains the catalytic residues, substrate-binding residues and FAD-binding motif identified previously in the E. coli protein. The gene was cloned into the pET28a+ expression vector, and the 34.5 kDa protein that it encodes was overexpressed in E. coli strain BL21(DE3) to 30% of total cell protein. The majority of the protein was found to be insoluble. A variety of methods were used to increase the amount of soluble protein to 10%. This was then purified to near homogeneity in a two-step process. The absorption spectrum of the purified protein indicated it to be a flavoprotein, like its E. coli homologue, with a characteristic absorption at 463 nm. The enzyme was shown to be active, reducing UDP-N-acetylglucosamine enolpyruvate with the concomitant oxidation of NADPH, and was characterized kinetically with respect to its two substrates. The enzyme showed properties similar to those of its E. coli counterpart, being activated by univalent cations and being subject to substrate inhibition. The characterization of an important cell wall biosynthesis enzyme from a Gram-positive pathogen provides a good starting point for the discovery of antibacterial agents against MurB.

Amino Acid Sequence↗
PubMed2001

Novel microbial lipases: catalytic activity in reactions in organic media.

2,000 microbial strains were isolated from soil samples and tested to determine their lipolytic activity by employing screening techniques on solid and in liquid media. Culture broths were initially tested with 1,2-O-dilauryl-rac-glycero-3-glutaric acid-resorufinyl ester, a chromogenic substrate specific for lipases. Fourteen lipase-producing microorganisms were selected and their taxonomic identification was carried out. Hydrolysis of tributyrin or olive oil and the esterification of oleic acid with heptanol were selected to preliminary evaluate the catalytic activity of these lipases. All the selected lipases catalysed this esterification reaction with good yields. Resolution of (R,S)-2-(4-isobutylphenyl) propionic acid, (R,S)-1-phenylethanol, (R,S) 1-phenylethylamine and of (R) or (S) glycidol were performed to evaluate the stereoselectivity of these novel enzymes as biocatalysts in reactions in organic media. Lipases from the fungi Fusarium oxysporum and Ovadendron sulphureo-ochraceum gave the best yields and enantioselectivities in the resolution of racemic ibuprofen and 1-phenylethanol. Several lipases displayed a high stereoselectivity in the resolution of chiral amines by an alcoxycarbonylation reaction.

Journal Article↗
PubMed2001

Dorsal subthalamotomy for Parkinson's disease.

We report our experience of unilateral subthalamotomy in patients with Parkinson's disease (PD). Eleven patients were included in a pilot, open-labeled study to assess the effect of unilateral lesion of the subthalamic nucleus (STN) with a minimum of 12 months of follow-up. The guidelines of CAPIT (Core Assessment Program for Intracerebral Transplantation) were followed for recruitment into the study and follow-up assessment. Levodopa equivalents daily intake (mean 967 mg) were unchanged during the first 12 months in all but one patient who stopped medication. The sensorimotor region of the STN was defined by semimicrorecording and stimulation and a thermolytic lesion was placed accordingly. There was a significant reduction in both UPDRS parts II and III in the "off" state at 1-, 6-, and 12-month follow-up. This effect was maintained in four patients up to 24 months. The dyskinesia score did not change postoperatively. Lesion-induced dyskinesias were not a management problem except in one patient who developed a large infarction several days postsurgery. This initial study indicates that a lesion of the STN is not generally associated with hemiballismus in PD. Subthalamotomy may induce considerable motor benefit and could become another surgical option under specific circumstances.

Aged↗
PubMed2001

Sonographic appearance of aggressive angiomyxoma of the scrotum.

Aggressive angiomyxoma (AAM) is a rare, locally infiltrative tumor that occurs almost exclusively in the pelvic and perineal regions of women of childbearing age. We report the unusual case of a 26-year-old man with an AAM presenting as a slowly enlarging scrotal mass. Gray-scale scrotal sonography demonstrated a well-demarcated, hypoechoic, extratesticular, extraepididymal mass with multiple thin, echogenic internal septa. The mass arose inferior to the left testicle and displaced the testicle cephalad. Color Doppler sonography revealed surrounding vascularity but no Doppler signals within the mass. The testicles and epididymides demonstrated normal echogenicity and vascularity. Histologic examination of the excised mass revealed a well-demarcated, nonencapsulated lesion composed of spindle-shaped cells in a myxoid background with a prominent vascular component.

Adult↗
PubMed2001

Antiangiogenic and antitumor effects of a protein kinase Cbeta inhibitor in murine lewis lung carcinoma and human Calu-6 non-small-cell lung carcinoma xenografts.

In cell culture, the compound 317615.2HCl, a potent inhibitor of VEGF-stimulated HUVEC proliferation, was not very effective against Calu-6 non-small-cell lung carcinoma cells (IC50 26 microM). Exposure to combinations of paclitaxel or carboplatin and 317615.2HCl with Calu-6 cells in culture resulted in cell survival that reflected less-than-additivity to additivity of the two agents. Administration of 317615.2HCl orally twice daily to nude mice bearing subcutaneous Calu-6 tumors resulted in a decreased number of intratumoral vessels as determined by CD31 and CD105 staining to 50% of the number in control tumors. 317615.2HCl showed antitumor activity against the Lewis lung carcinoma and increased the tumor growth delay produced by paclitaxel by 5-fold, that produced by gemcitabine by 2-fold and that produced by carboplatin by 1.7-fold. There was a decrease in the number of lung metastases in the Lewis lung carcinoma that paralleled the increased response of the primary tumor with each treatment combination. Administration of 317615.2HCl also increased the tumor growth delay produced by fractionated radiation therapy in the Lewis lung tumor. Treatment with 317615.2HCl was an effective therapy in the Calu-6 non-small-cell lung carcinoma xenograft when the compound was administered early (days 4-18) or later (days 14-30). Combination treatment regimens in which 317615.2HCl was administered along with or sequentially with paclitaxel or carboplatin were much more effective than the chemotherapeutic agents administered alone. 317615.2HCl is in early clinical testing.

Administration, Oral↗
PubMed2001

Modulator activity of PSC 833 and cyclosporin-A in vincristine and doxorubicin-selected multidrug resistant murine leukemic cells.

Multidrug resistance (MDR) lines from a murine T-cell leukemia were selected in increasing vincristine (VCR) or doxorubicin (DOX) concentrations. Daunorubicin (DNR) efflux was evidenced after 25 additional passages with constant 160 ng ml(-1) of either VCR or DOX, an effect that was inhibited by verapamil, cyclosporin-A (CsA) and PSC 833. The expression of Pgp was not evidenced in the resistant cell lines using anti-human Pgp antibodies. Cell proliferation assay showed that cell lines resistant to VCR (LBR-V160) or DOX (LBR-D160) required higher doses of either drug to produce GI50 compared with control cell line obtained after culture in the absence of VCR or DOX. When resistant cell lines were maintained during 60 days in the absence of either VCR or DOX, MDR phenotype reversal was obtained in LBR-D160 while LBR-V160 remained resistant to the drug, as shown by cell proliferation assays and by drug efflux pump functionality. When VCR or DOX were used together with either CsA or PSC 833, the latter was more effective to produce reversal of resistance than the former, whereas CsA presented greater cytotoxic effect than PSC 833 for sensitive and resistant cells. Cross-resistance was found between VCR, DOX and other antineoplasic agents on murine leukemic cell line. VCR was more effective to induce MDR since the resistant cell lines were more stable to the MDR phenotype.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

[The usefulness of the application of nonlinear dynamics in the analysis of electrocardiograms in Chagas' disease patients].

INTRODUCTION AND OBJECTIVES: The application of nonlinear techniques allows the definition of early risk markers in patients with Chagas infection and without any evidence of cardiac involvement evaluated by standard diagnostic test. Nonlinear modeling techniques have proved to be effective in cardiac rhythm analysis, thereby justifying its use in Chagas' disease. PATIENTS AND METHOD: The routine noninvasive test and heart rate variability analysis were performed in Chagas' disease patients and in a group of healthy subjects. In a second phase we used nonlinear analysis in the evaluation of patients with Chagas infection and no evidence of heart disease, Chagasic patients with minimal electrocardiographic abnormalities and healthy controls. RESULTS: Twenty-four-hour electrocardiographic ambulatory monitoring and heart rate variability allowed us to establish differences between the healthy subjects and patients with Chagas infection without evidence of cardiac disease (p c 0.05 and p <0.005). In sharp contrast nonlinear analysis characterized 4 subgroups in Chagasic patients without cardiac involvement (sensitivity and specificity of 1 00%). CONCLUSIONS: Our findings suggest that nonlinear modeling techniques have a high sensitivity and specificity in the early detection of cardiac involvement and very early autonomic disturbance. We recommend that these techniques be applied to patients with high risk of cardiac disease other than Chagasic myocarditis. Our findings should be corroborated with studies in larger populations. We are currently developing a prospective study to this end.

Adult↗
PubMed2001

Randomized controlled trial of aspiration needle versus automated biopsy device for transjugular liver biopsy.

PURPOSE: The efficacy and safety of transjugular liver biopsy used to obtain liver specimens in patients with coagulation disorders have been widely proven. However, histopathologic examination is not always possible because of fragmented samples provided by the aspiration technique. Recently, an automated device with a Tru-Cut-type needle was designed. In this randomized controlled trial, the use of this new device is compared with the traditional method in terms of efficacy and safety. METHOD: Fifty-six patients were included in the study; 28 were randomized to undergo the aspiration technique and 28 were randomized to undergo the automated biopsy technique. RESULTS: Correct positioning of the device was achieved in 93% of patients undergoing the aspiration technique and 96% of patients undergoing the automated biopsy technique (P = NS). Mean duration of the procedure and total number of passes were significantly higher in the aspiration needle group than in the automated device group (22.6 min +/- 12.6 vs 15.5 min +/- 9.4; P = .03, and 3.3 min +/- 1.9 vs 1.5 min +/- 0.63; P < .001, respectively). The number of portal tracts was significantly higher in the automated device group (4.7 +/- 2.5 vs. 2.7 +/- 3.4; P < .05). Adequate specimens for histopathologic evaluation were obtained in 26 patients in the automated device group and 24 patients in the aspiration needle group (92.8% vs 85.7%; P = NS), but a definite histopathologic diagnosis was more frequently obtained with the automated biopsy device (68% vs 43%; P = .05). No significant differences were observed in complication rates (7.14% vs. 10.7%; P = NS). CONCLUSION: The automated biopsy device for transjugular liver biopsy is more effective than an aspiration needle in obtaining good samples for a definite histologic diagnosis.

Adult↗
PubMed2001

Age-related changes in membrane lipid composition, fluidity and respiratory burst in rat peritoneal neutrophils.

The O2*(-) production has been studied in rat peritoneal neutrophils of different age (3, 12 and 24 months), in order to analyse whether the neutrophil respiratory burst is modified with increasing age. To stimulate NADPH oxidase, the enzyme responsible for the respiratory burst, two stimuli that act in different way have been used: phorbol myristate acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (N-FMLP). Production of O2*(-) decreased with age in neutrophils stimulated with N-FMLP (about 40%), but not in the stimulated with PMA. No difference in NADPH oxidase activity was found with age. The NADPH is supplied to the respiratory burst mainly by the pentose phosphate shunt. A progressive and significant decrease in the two most important enzymes of this route, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, was detected as a function of age; in spite of this reduction, the NADPH produced by cells from old animals seems not limiting for the O2*(-) production. The N-FMLP-induced decrease in the O2*(-) production may be related to the age-dependent increase in the membrane fluidity observed. A decline in the cholesterol/phospholipid ratio and a rise in the total polyunsaturated fatty acids content were found, that correlated well with the increase in the membrane fluidity. The decrease (50%) of phosphatidylinositols in the 24-month-old animals may be also related to the age-impairment in the respiratory burst found after stimulation with N-FMLP. These studies suggest that the age-related alterations in neutrophil may result in diminished neutrophil function and increased susceptibility to infection in the ageing.

Aging↗
PubMed2001

Association between seminal plasma carnitine and sperm mitochondrial enzymatic activities.

Cellular parameters of the seminogram have been previously shown to correlate with L-carnitine concentration in the seminal fluid. Carnitine is involved in a variety of metabolic processes playing an important role in maintaining an active oxidative phosphorylation (OXPHOS). Recently, we have found a significant association between the specific activities of the respiratory chain complexes and the seminogram parameters and here we have studied the relationship between the spermatozoa OXPHOS activities and L-carnitine concentration in the seminal plasma. Carnitine, but not prostatic secretions, positive and significantly correlate with mitochondrial respiratory complex activities and the citric acid cycle enzymes citrate synthase and succinate dehydrogenase. It is remarkable that the ratios of the respiratory chain complexes to citrate synthase or succinate dehydrogenase, significant but negatively correlated with L-carnitine concentration. As carnitine in seminal plasma is secreted from the epididymis our results strongly suggest that relationships between carnitine secretion, seminal quality and OXPHOS activities could be because of a parallel response to the same regulatory event.

Carnitine↗
PubMed2001

Effects of psychological techniques on bruxism in children with primary teeth.

Four main causes of bruxism have been studied - high anxiety level, malocclusion, temporomandibular disorders (TMD) and oral habits. Effective dental treatment for this problem is unknown in children with primary teeth, although, high prevalence has been reported. The aim of this study was to investigate the effectiveness of psychological techniques in children with bruxism. A total of 33 children, 3-6 years of age with normal occlusal features, without oral habits, rate in the Conners' parent rating scales (CPRS) and more than 0.75% in Conners' teacher rating scales (CTRS), and one or more temporomandibular joint (TMJ) disorders registered in the Bernal and Tsamtsouris examination, were selected from 188 children. Two psychological techniques, 'directed muscular relaxation' and 'competence reaction', were applied for 6 months. The results were analysed with a Wilcoxon rank sum test. All patients reduced their anxiety level and TMJ disorders, with statistical significance (P < 0.05). The psychological techniques were effective in the reduction of signs of bruxism in children with primary teeth.

Anxiety↗