308 research outputs found
Imaging Ferromagnetic Tracers With An Ac Biosusceptometer
No full textThe aim of this work was to study the feasibility of obtaining images of the distribution of ferromagnetic tracers using an ac biosusceptometer (ACB). The images were generated by mapping the response of the ACB at short distances due to the presence of a ferrite powder dispersed in a planar gel matrix with different shapes. The ACB was scanned over the sample and the voltages generated by the variation in ferrite concentration were sampled. Methods to render and image the distribution of ferromagnetic particles were studied. The generalized Wiener parametric method gave the best results. The system has a potential to be used in functional images of the gastrointestinal tract where a moderate resolution is required. We conclude that this biomagnetic method can be successfully used to generate planar functional images of magnetic particles in the near field. © 2000 American Institute of Physics.71625322538Erol, R.A., Cherian, P., Smallwood, R.H., Brown, B.H., Bardhan, K.D., (1996) Physiol. Meas., 17, pp. A141Ikeya, M., Ishii, H., (1990) J. Magn. Reson., 88, p. 130Smith, C.M., Stevens, A.D., (1994) Br. J. Radiol., 67, p. 1186Roth, B.J., Sepulveda, N.G., Wikswo J.P., Jr., (1989) J. Appl. Phys., 65, p. 361Moreira, M., Murta, L.O., Baffa, O., (1994) Phys. Med. Biol., 39 A, p. 633Miranda, J.R.A., Baffa, O., Oliveira, R.B., Matsuda, N.M., (1992) Med. Phys., 19, p. 445Baffa, O., Oliveira, R.B., Miranda, J.R., Troncon, L.E.A., (1995) Med. Biol. Eng. Comput., 33, p. 353Oliveira, R.B., Baffa, O., Troncon, L.E.A., Miranda, J.R.A., Cambrea, C.R., (1996) Eur. J. Gastroent. Hepatol., 8, p. 491Miranda, J.R.A., Oliveira, R.B., Sousa, P.L., Braga, F.J.H., Baffa, O., (1997) Phys. Med. Biol., 42, p. 1791Daghastanli, N.A., Braga, F.J.H.N., Oliveira, R.B., Baffa, O., (1998) Physiol. Meas., 19, p. 413Forsman, M., Hultin, L., Abrahamsson, H., (1995) Biomagnetism: Fundamental Research and Clinical Applications. Studies in Applied Electromagnetics and Mechanics, 7, p. 739. , edited by C. Baumgartner, L. Deecke, G. Stroink, and S. J. Williamson Elsevier, AmsterdamBasile, M., Neri, M., Carriero, A., Casciardi, S., Comani, S., Del Gratta, C., Donate, L.G., Romani, G.L., (1992) Dig. Dis. Scie., 37, p. 1537Bruno, A.C., (1997) J. Appl. Phys., 82, p. 1Cruvinel, P.E., Cesareo, R., Crestana, S., Mascarenhas, S., (1990) IEEE Trans. Instrum. Meas., 39, p. 745Lim, J.S., (1990) Two-Dimensional Signal and Image Processing, , Prentice-Hall, Englewood Cliffs, NJJ. P. Wikswo, Jr., N. G. Sepulveda, and I. M. Thomas, Ref. 11, p. 789Tan, S., Ma, Y.P., Smith, I.M., Wikswo J.P., Jr., (1996) IEEE Trans. Magn., 32, p. 230Weber, E., (1951) Electromagnetic Fields: Theory and Applications, Mapping of Magnetic Fields, 1. , Wiley, New YorkSpiegel, M.R., (1990) Mathematical Handbook of Formulas and Tables, , McGraw-Hill, New YorkBruno, A.C., Costa Ribeiro, P., Von Der Wied, J.P., Symko, O., (1986) J. Appl. Phys., 59, p. 2584Vrba, J., Fife, A.A., Burbank, M., Weinberg, H., Bricket, P.A., (1982) Can. J. Phys., 60, p. 106
ARNICA, the Arcetri near-infrared camera: Astronomical performance assessment
No full textThe Arcetri near-infrared camera ARNICA was built as a users' instrument for the Infrared Telescope at Gornergrat (TIRGO), and is based on a 256x256 NICMOS 3 detector. In this paper, we discuss ARNICA's optical and astronomical performance at the TIRGO and at the William Herschel Telescope on La Palma. Optical performance is evaluated in terms of plate scale, distortion, point spread function, and ghosting. Astronomical performance is characterized by camera efficiency, sensitivity, and spatial uniformity of the photometry
TP53 gene mutations in gastric carcinoma detected by polymerase chain reaction/single-strand conformation polymorphism analysis of archival material.
No full textTP53 gene mutations, one of the most common alterations described in human tumors, have also been detected in gastric carcinoma, and shown to occur rather late in disease progression. A better assessment of the prognostic value of TP53 gene mutations can be obtained by examining archival material, as this allows stored cases with well-defined histories to be monitored. We performed immunohistochemical and polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analyses of formalin-fixed paraffin-embedded material from nine selected cases of gastric carcinoma at different pathological stages. PCR-SSCP analysis of TP53 exons 5-8 detected missense point mutations in two out of five immunostain(PAb1801)-positive tumors, and a deletion (allowing for a premature stop codon) in one of the remaining four immunostain-negative tumors. Thus, PCR-SSCP analysis represents a feasible strategy for the detection of TP53 alterations in archival material of gastric carcinoma cases
Pathology of the gastric antrum and body associated with Helicobacter pylori infection in non-ulcerous patients: is the bacterium a promoter of intestinal metaplasia?
No full textA series of 115 consecutive, non-ulcerous, dyspeptic patients were examined for Helicobacter pylori (H. pylori) colonization in the gastric antral and/or body mucosa using Giemsa staining. Findings were correlated with the presence and degree of activity of superficial gastritis, deep gastritis, atrophic gastritis and with the presence of intestinal metaplasia. The prevalence of H. pylori positivity was 61.7%. In 59 of the 71 positive patients (83%), H. pylori was detected in the antrum or in both the antral and oxyntic mucosa. In the remaining 12 positive patients, H. pylori was detected only in the oxyntic mucosa and in all these cases, the antrum showed intestinal metaplasia associated with atrophic gastritis (25%). In both antral and oxyntic mucosa, the activity of the gastritis was significantly correlated with H. pylori colonization. Linear logistic regression analysis showed that in patients with intestinal metaplasia the presence of H. pylori infection was significant in predicting the presence of more extensive intestinal metaplasia after adjusting for age. The prevalence of intestinal metaplasia types II and III was 65.5% in the H. pylori positive and 25% in the H. pylori negative patients. The antral mucosa is thought to be the elective site for H. pylori related histological lesions. At a later stage, H. pylori can be detected only in the oxyntic area while the antral mucosa shows extensive metaplastic or atrophic lesions. We would suggest that H. pylori plays a promotional role in the morphogenesis of intestinal metaplasia
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