Browsing by Author "Figueroa, C"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
- ItemAccuracy of invasive and noninvasive tests to diagnose Helicobacter pylori infection after antibiotic treatment(WILLIAMS & WILKINS, 1997) Rollan, A; Giancaspero, R; Arrese, M; Figueroa, C; Vollrath, V; Schultz, M; Duarte, I; Vial, PObjectives: To compare the diagnostic accuracy of the most widely available tests for diagnosis of Helicobacter pylori infection after antibiotic treatment, Methods: A total of 59 H, pylori-positive, duodenal ulcer patients (mean age, 40.7 +/- 11.7 yr; 40 male and 19 female) were treated for 2 wk with either amoxicillin-metronidazole (n = 36) or omeprazole-amoxicillin-tinidazole (n = 23), and after 4 wk, were tested for H, pylori infection by [C-14]urea breath test (UBT), serum IgG antibody level, and multiple antral biopsies for rapid urease testing, histology, Warthin-Starry stain, and polymerase chain reaction to detect H, pylori DNA, Infection status was established by a concordance of test results, Results: H, pylori was eradicated in 47 patients (80%), UBT and rapid urease testing had the best sensitivity and specificity, although not statistically different to Warthin-Starry stain and polymerase chain reaction, Serology and histology had little diagnostic value in this setting due to high proportion of false-positive results, Conclusions: Noninvasive UBT is as accurate in predicting H, pylori status after antibiotic treatment as rapid urease testing and Warthin-Starry stain, Especially for duodenal ulcer patients, UBT could be considered the gold standard to confirm eradication of H, pylori.
- ItemAllopurinol encapsulated in polycyanoacrylate nanoparticles as potential lysosomatropic carrier(2000) González-Martín, G; Figueroa, C; Merino, I; Osuna, AThe activity of allopurinol-loaded polyethylcyanoacrylate nanoparticles against Trypanosoma cruzi was compared to that of free allopurinol using in vitro cultures of epimastigotes. Ethylcyanoacrylate nanoparticles were prepared by an emulsion polymerization process, and formulations containing different concentrations of allopurinol, polyethylcyanoacrylate and surfactants were investigated and analyzed in size and amount of drug entrapped. The nanoparticles obtained were less than 200 nm in size, as measured by electron microscopy and cytometry. The peak amount of allopurinol entrapped in the nanoparticles was 62.8 +/- 1.9 mu g mg(-1) of nanoparticles using 400 mu l of polyethylcyanoacrylate, 200 mu l of surfactant (Tween 20) and 20 mg of allopurinol in 50 mi of polymerization medium and the association efficiency was 100.7%. After 6 h of incubation at pH 7.4 the release of allopurinol from the nanoparticles was 7.4%, while at pH 1.2 only 3.1% was released after 4-6 h (t = 42.8, P < 0.0001). The in vitro studies, using cultures of T. cruzi epimastigotes, demonstrated considerable increases in the trypanocidal activity of the allopurinol-loaded nanoparticles in comparison with a standard solution of allopurinol (91.5 vs. 45.9%) at an allopurinol concentration of 16.7 mu g ml(-1). In addition, it was shown that the unloaded nanoparticles, by mechanisms not completely elucidated, had a trypanocidal activity similar to that of standard solutions of allopurinol. To study cytotoxicity, increasing concentrations of unloaded nanoparticles were incubated on vero-line cell cultures. The concentration that killed 50% cells was 200 mu g ml(-1), four times higher than that necessary to kill 50% of T. cruzi. It is concluded that the polyethylcyanoacrylate nanoparticles constitute a good carrier of drugs against the T. cruzi. The allopurinol loaded-nanoparticles significantly increased the trypanocidal activity in comparison to the free drug. (C) 2000 Elsevier Science B.V. All rights reserved.
- ItemEstrogen and luminal stimulation of rat uterine kallikrein(OXFORD UNIV PRESS INC, 1997) Corthorn, J; Figueroa, C; Valdes, GTo understand the regulation of rat uterine kallikrein, we evaluated its variations in animals that had been ovariectomized and supplemented with estradiol or progesterone, in pseudopregnant animals intraluminally oil-stimulated or unstimulated, and in unilaterally pregnant animals. The content of kallikrein, determined by an RIA highly specific for rK1 (true tissue kallikrein), rose in ovariectomized rats with estradiol supplementation (0.28 +/- 0.03 to 0.44 +/- 0.05 ng/mg) and decreased with progesterone (0.13 +/- 0.02 ng/mg; n = 15; p < 0.001). Kallikrein content rose from Day 1 of pseudopregnancy (PP1) to a maximum on PP7 (0.18 +/- 0.01 to 0.39 +/- 0.04 ng/mg protein; n = 36; p < 0.001). On PP7 with unilateral oil intraluminal stimulation, the decidualized horn had higher kallikrein content than did the contralateral (0.98 +/- 0.09 vs. 0.35 +/- 0.05 ng/mg protein; n = 7; p < 0.001). Immunocytochemistry revealed that mainly rK1 is localized in the luminal and glandular epithelium, and it increased in the stimulated horn. In the unilaterally pregnant rat on Day 7, the fertile horn had a higher kallikrein content than its contralateral control (0.71 +/- 0.07 vs. 0.37 +/- 0.03 ng/mg protein, pt 0.001; n = 8), as well as a higher kininogenase activity (239 +/- 34.3 vs. 83.5 +/- 7.9 ng bradykinin(BK)/h per horn, p < 0.003; and 945 +/- 90 vs. 585 +/- 40 ng 8K/h per gram tissue, p < 0.002; n = 6). These results indicate that estrogen stimulates, whereas progesterone inhibits, kallikrein production, and that hormonal regulation is overridden by intraluminal stimulation, thus associating the enzyme with decidualization.
- ItemInfluence of coastal upwelling and El Nino-Southern Oscillation on nearshore water along Baja California and Chile(2004) Takesue, RK; van Geen, A; Carriquiry, JD; Ortiz, E; Godínez-Orta, L; Granados, I; Saldívar, M; Ortlieb, L; Escribano, R; Guzman, N; Castilla, JC; Varas, M; Salamanca, M; Figueroa, C[ 1] In order to determine the sensitivity of coastal upwelling tracers to seasonal wind forcing and El Nino-Southern Oscillation (ENSO) off Baja California and Chile, nearshore salinity, cadmium (Cd), and nutrients phosphate, silicate, nitrate+ nitrite were monitored in surf zone waters at six locations along the North and South American coasts during 1997-2000. The clearest responses to upwelling favorable wind forcing were observed at the southern tip of Baja California (23.3degreesN) and off central- southern Chile (36.5degreesS). Upwelling tracers at 23.3degrees N were also the most sensitive to El Nino: average summer Cd and nutrient enrichments were 60% lower following El Nino than during the previous non-El Nino upwelling season. At two sites on the northern and central Chile coasts, conditions associated with El Nino resulted in salinity anomalies >1. Such large shifts in nearshore water properties suggest it may be possible to reconstruct past ENSO patterns from geochemical paleonutrient/paleosalinity proxy records preserved in nearshore archives such as mollusc or foraminifera shells.
- ItemSubcellular localization of catalase in sea urchin (Tetrapigus niger) gametes(1997) Figueroa, C; Kawada, ME; Munizaga, A; González, S; Barros, C; Koenig, C; Santos, MJPeroxisomes are essential subcellular organelles that appear to be derived from pre existing organelles. To test the presence of peroxisomes in sea urchin (Tetrapigus niger) sperm and eggs, we performed biochemical and morphological experiments to evaluate the subcellular distribution of catalase as the typical peroxisomal marker. In sea urchin sperm, we found that catalase is localized in the cell cytosol. In contrast, sea urchin eggs contain sedimentable catalase, presumably contained in peroxisome-like structures detected by immunomicroscopy and by cytochemistry. Our results show, for the first time, evidence for the presence of peroxisome-like structures in sea urchin eggs and provide evidence for the peroxisome biogenesis hypothesis by division of preexisting organelles. (C) 1997 Elsevier Science Inc.
- ItemThe long-term reinfection rate and the course of duodenal ulcer disease after eradication of Helicobacter pylori in a developing country(2000) Rollan, A; Giancaspero, R; Fuster, F; Acevedo, C; Figueroa, C; Hola, K; Schulz, M; Duarte, IOBJECTIVE: The aim of this study was to evaluate the effect of Helicobacter pylori (H. pylori) eradication on the natural history of duodenal ulcer disease and the reinfection rate after treatment in a developing country.