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Biomedical subjects

C Alvarez

Publications and source records attributed to C Alvarez.

At least 289 records · Page 16Linked to original sources
PubMedDate not supplied

Study of cytoskeletal changes induced by okadaic acid in BE(2)-M17 cells by means of a quantitative fluorimetric microplate assay.

The diarrhogenic activity of the marine toxin okadaic acid (OA) has been associated to its actin-disrupting effect, which could reflect the loosening of tight junctions in vivo. In this report, we present results obtained using a fluorimetric microplate assay for quantitative measurements of OA-induced changes on F-actin pools in BE(2)-M17 cells. The proposed method shows important advantages over classical methods in terms of rapidity, sensitivity (less than 5000 cells per well) and reproducibility, thus providing a very useful tool for studying F-actin levels in living cells. Results obtained demonstrate a time- and dose-dependent decrease of F-actin pools (IC(50)=100 nM at 1 h) in OA-treated cells, which was partly counteracted by TPA, H89, forskolin, wortmannin, ionomycin and orthovanadate at early stages, but remained unaffected after 24 h of incubation. Cells exposed for 1 h to 1 nM OA showed a slight increase of F-actin pools (1.5-fold), which was blocked by genistein and lavendustin A, thus suggesting a role for tyrosine kinases-dependent pathways in OA-induced polymerization at low concentrations. These results suggest direct interactions of Ser/Thr protein phosphatases with actin-binding proteins in the regulation of actin polymerization, thus indicating that disruption of cytoskeletal structure may be a key mechanism of OA-induced diarrhea.

Actins↗
PubMedDate not supplied

Role of transforming growth factor-beta in growth and injury response of the pancreatic duct epithelium in vitro.

Chronic pancreatitis is characterized by increased levels of expression of transforming growth factor-beta (TGF-beta), particularly in and around the ducts. To examine the consequences of elevated exposure to TGF-beta on the pancreatic duct epithelium, we cultured segments of the main bovine pancreatic duct in the presence of increasing doses of TGF-beta. We also studied the effect of TGF-beta on epithelial injury, produced in this model by exposure to a bile acid. The extent of proliferation, migration, and epithelial damage was measured morphometrically on sections stained with hematoxylin and eosin. Proliferation and apoptosis were qualitatively determined by means of immunohistochemical analysis. In this model of duct cell culture, TGF-beta stimulated cell migration in areas of the explants where the native basement membrane of the duct epithelium was absent. In segments where the native basement membrane remained intact, proliferation was inhibited and apoptosis induced. When the explants were exposed to bile acid, extensive epithelial injury was observed. TGF-beta exposure at high doses (1 nmol/L protected epithelial integrity, but cellular morphology was altered and the process of apoptosis appeared to be increased. Our results suggest that increased periductal levels ot TGF-beta in the setting of pancreatic injury may be intended to promote repair of acute epithelial damage but may have detrimental long-term effects.

Animals↗
PubMedDate not supplied

[A review of the clinical application of dyes in gastrointestinal chromoendoscopy, and their magistral formulation].

OBJECTIVE: To review the drug compounding of dyes employed in chromoendoscopy, and their clinical effectiveness. METHOD: A literature search in Medline, Cochrane Library, and Micromedex was carried out with the term chromoendoscopy as a keyword, and the search was then repeated for each dye found in association with the term endoscopy. A number of monographs, scientific journals, and references quoted in selected papers were also reviewed. Papers collected were then classified according to their methodology. RESULTS: Ninety-six references were found, their original article being recovered for only 57 of these - 13 clinical trials, 21 case series, and 11 reviews. References were found for 7 dyes. Main indications, evidence of effectiveness, administration route, and drug formulation are described for each dye. CONCLUSIONS: The number of papers involved is high, but their accessibility is limited. Evidence is overall scarce, but high in cases such as methylene blue for Barrett s esophagus, lugol in the detection of esophageal carcinoma, and indigo carmine for colonic hyperplastic polyp differentiation. Drug compounding is rather simple, but scarcely developed.

Coloring Agents↗
PubMedDate not supplied

Comparative study of a portable prothrombin time monitor employing three different systems in oral anticoagulant units.

The aim of this study was to evaluate the accuracy of the portable coagulometer CoaguChek (Roche Diagnostics) as a prothrombin time (PT) monitor, and to correlate capillary blood results with those of three different routine methods used for monitoring oral anticoagulant therapy (OAT): capillary, plasma and whole blood samples. Three hospitals participated in the study with a total of 235 patients on OAT. The international normalized ratio (INR) results obtained with CoaguChek were compared with those obtained using each of the routine methods. The study presents a good correlation between the PT monitor and the three methods studied: r = 0.9745 (hospital A), r = 0.9283 (hospital B), r = 0.9136 (hospital C). A simplified concordance test of the methods results in a nine-field comparison table showing concordances of 87.2, 85.7 and 68.4%, respectively. The absolute difference (mean +/- SD) between laboratory A and CoaguChek INRs was 0.0571 +/- 0.2042, with values of 0.04286 +/- 0.3906 for laboratory B and 0.6986 +/- 0.6170 for laboratory C. These results confirm that CoaguChek could be used as a new method for oral anticoagulant monitoring, and is in best agreement with the capillary blood PT system.

Humans↗
PubMedDate not supplied

Hematuria and microalbuminuria after a 100 kilometer race.

An investigation into hematuria and microalbuminuria induced by prolonged physical exercise was carried out by studying 26 runners who took part in a 100 km race by collecting urine samples before, after the race, and 24 hours later. Microscopic hematuria was present in two runners before the race. After this strenuous exercise there was macroscopic hematuria in five runners (19.2%) and microscopic hematuria in nine (34.6%). On examination by phase contrast microscopy there were neither dysmorphic erythrocytes nor red cell casts. Albuminuria was measured by radial immunodiffusion and was expressed as Ualb/Ucreat and Ualb/Uosm ratios. Clinical albuminuria was found in five runners with macroscopic hematuria, and microalbuminuria in 13 of the 21 remainders; in 6 of them it was associated with microscopic hematuria. Twenty-four hours later all of the results were normal with the exception of the five runners who have had macroscopic hematuria and another one with microalbuminuria without hematuria. We conclude that determination of albumin excretion in runners after exercise should be made as well as hematuria, and particular attention should be paid to cases of severe and/or prolonged microalbuminuria, since such individuals may be at risk of renal disease.

Adult↗
PubMedDate not supplied

[Colonic polyps: an analysis of the endoscopic and histopathological aspects].

The present study is a retrospective analysis of the endoscopic and histologic features of 728 polyps resected from 422 patients during the years 1980 to 1991. Mean age of the patients was 52 years (5 to 87), 63% male and 37% female. The histology of the lesions showed: adenoma: 60.3%, hyperplastic: 31.7; juvenile: 2.3% and miscellaneous: 5.7%. The 439 adenomas where found in 270 patients of which 151 (55.9%) were male and 119 (44.1%) female. The 231 hyperplastic polyps where found in 113 patients: 66 (58.4) male and 47 (41.6) female. All the hyperplastic polyps where less than 20 mm in diameter. Of the adenomas, 385 (87.7%) where less than 20 mm in diameter and had macroscopic appearance similar to the hyperplastic polyps. Of the 439 adenomas, 218 (49.6) where pediculated and 221 (50.4%) sessile. Of the hyperplastic polyps 53 (22.9%) where pediculated and 178 (77%) sessile. Of the adenomas, 351 (80%) where tubular and 88 (22%) had a villous component, most of the tubular adenomas where less than 15 mm in diameter and the villous component was more frequent as the polyps increased in size. Of the adenomas, 139 (30%) had dysplasia and of these 10% had cancer which represents a total of 3% of all the adenomas in this series. The grade of dysplasia was more severe as the adenomas was larger in size or had villous component. The polyps were located: 69.6 in the distal colon at the reach of the flexible sigmoidoscope and 30.4% in the proximal colon.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Leiomyosarcoma of the vena cava inferior. The correlation: ultrasound and fine-needle puncture biopsy].

The leiomyosarcoma of the inferior vena cava is a non-frequent tumor, mesenchymal, that has its origin in the smooth muscular tissue of the vascular wall. Its growth is slow and expansive, more frequently found on females. The symptomatology is related to the cava segment where it is located. The diagnosis is performed by ultrasonics, computed tomography and cavography, actually magnetic resonance acquires more and more importance. The treatment is specifically surgery along with radiotherapy and chemotherapy. A case of leiomyosarcoma of the inferior vena cava is presented in which diagnosis was performed using ultrasonics, tomography and cavography confirmed before surgery by biopsy punction with thin needle. In the diagnosis of this pathology it is described the use of intro-surgery ultrasonics.

Biopsy, Needle↗