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Biomedical subjects

A Pousse

Publications and source records attributed to A Pousse.

16 recordsLinked to original sources
PubMed1991

Introducing simultaneous spatial resolution and attenuation correction after scatter removal in SPECT imaging.

A new approach to simultaneous spatial resolution and attenuation correction in SPECT imaging is presented. Before these corrections, scatter is removed on the projections. This removal is performed by spectral constrained factor analysis. The innovation reported here is the use of the different impulse responses of the system, according to the source-detector distance, and their integration in a generalized version of the Chang attenuation correction method. This novel algorithm is evaluated on computed and physical phantoms. In the computer-simulated phantom, the count rates after full-processing are very close to the initial values. In the physical phantom, the contrast is increased by 1.8 after full processing. The activity profiles drawn both on raw projections and reconstructed slices demonstrate the effectiveness of the algorithm for the restoration of spatial resolution. Furthermore, the method improves the quality of the images greatly. A clinical study is also presented. When the whole procedure is applied, the resulting slice matches the corresponding computed tomographic scan very well, which is not the case with the usual back-projected images. The process is fully automatic and the computing time performance allows its daily use for single photon emission tomographic examinations.

Algorithms↗
PubMed1985

Combined effect of chronic bombesin and secretin or cholecystokinin on the rat pancreas.

This work investigates the pancreatico-trophic action of bombesin, a peptide stimulating pancreatic secretion in vivo and in vitro and examines whether this effect is altered by CCK or secretin. Rats were injected three times daily for 5 days either with saline, bombesin (1 or 10 micrograms/kg), CCK (20 I.D.U./kg), secretin (20 C.U./kg) or a combination of bombesin and CCK or secretin. Bombesin alone induced growth of the pancreas beginning with the dose of 10 micrograms/kg. This growth was characterized by an increase of pancreatic weight, its protein, RNA and enzyme content, but not of its DNA content. The ratios of the three former parameters to DNA increased, suggesting cellular hypertrophy. Cholecystokinin alone exhibited a similar trophic action on the pancreas as bombesin. Secretin alone had no effect on pancreatic size and composition. Cholecystokinin and secretin did not modify the pancreatico-trophic response of bombesin. These findings suggest that bombesin, administered for 5 days in the rat, induces pancreatic growth due to cellular hypertrophy. Cholecystokinin has the same effect. However the mode of action, at the cellular level, of bombesin appears to be different from that of cholecystokinin.

Animals↗
PubMed1985

Trophic effect of bombesin on the rat pancreas: is it mediated by the release of gastrin or cholecystokinin?

This work investigates the effect, on the rat pancreas, of a chronic administration of bombesin in function of the dose and duration of treatment and examines whether this effect may be mediated by the release of endogenous gastrin or cholecystokinin. Bombesin, administered three times daily for 5 or 15 days, induced a marked increase in pancreatic weight, its protein, RNA and enzyme contents with the dose of 10 micrograms/kg body weight; the ratios of pancreatic weight, protein and RNA contents to DNA contents increased significantly after a 5 day treatment, suggesting cellular hypertrophy. Pancreatic DNA content was markedly enhanced after a 15 day treatment, suggesting cellular hyperplasia. Antrectomy decreased plasma gastrin levels, but did not alter the pancreatico-trophic action of a 10 micrograms/kg bombesin treatment for 5 days. Proglumide, an inhibitor of cholecystokinin and gastrin in the pancreas, did not affect the growth of the pancreas induced by a 10 micrograms/kg bombesin treatment for 5 days. It is concluded that chronic bombesin induces, in the rat pancreas, cellular hypertrophy or hyperplasia depending on the duration of treatment. Pancreatic hypertrophy is not mediated by the release of endogenous gastrin or cholecystokinin.

Amylases↗
PubMed1979

Do low doses of deoxycholate modify the release of rat jejunal brush border hydrolases?

The in-vivo effects of sodium deoxycholate (DOC) at low concentrations on the release of protein and some brush border hydrolases, sucrase (SA), maltase (MA), leucine aminopeptidase (LA), alkaline phosphatase (AP), have been investigated in the rat by a jejunal perfusion technique. During perfusion with DOC (0.125 or 0.25 mmol/l), enzyme release was not enhanced. After removal of DOC from the perfusion solution with 0.125 mmol/l DOC, there was a steady release of SA, MA and AP although enzyme release was increased linearly in the control and the 0.25 mmol/l DOC groups. The results also confirm the deep localization of AP within the membrane.

Alkaline Phosphatase↗
PubMed1979

Computer program for intestinal spike bursts recognition.

A FORTRAN program has been developed for locating intestinal spike bursts and for estimating their strength. Tested against human scanning, the reliability rate was 92% and the misrecognition rate was 2.5%. This program was applied to the automatisation of the Migrating Myoelectric Complex analysis. A first method computed the percentage of Basic Electrical Rhythm (BER) cycles with superimposed spike bursts. A second one was based on the evaluation of spike bursts strength.

Animals↗
PubMed1978

Computer program for intestinal basic electrical rhythm patterns analysis.

A FORTRAN program has been elaborated for computerized intestinal Basic Electrical Rhythm (BER) analysis. It is based on recognition of individual cycles limits. The reliability of the method was assessed by comparison between computer and visual cycle limits identification. The agreement is 98.2% for BER recorded from the frequency plateau. It is 91.4% for fluctuating BER patterns. For BER frequency computing, drawbacks due to misrecognitions were avoided by cancelling sequences in which they occur.

Computers↗
PubMed1978

Rat intestinal brush border enzymes release by deoxycholate in vivo.

The release of proteins, sucrase (SA), maltase (MA), leucine aminopeptidase (LA) and alkaline phosphatase (AP) activity from rat jejunum by sodium deoxycholate (DOC) was studied by an in vivo perfusion technique. In our experimental conditions, a 2 mmol/1 DOC perfusion for 30 min induced a marked and reversible release of proteins and hydrolases. When specific activities were considered, each enzyme showed a distinct release pattern. Significantly, the SA release was largely increased, the AP release was decreased and there was no correlation between the releases of SA and AP. Furthermore, the various enzymes recovered into the lumen were solubilized at different extents. SA was chiefly present in a soluble and AP in a particular form. The microscopical appearances showed a slight exfoliation of the epithelial cells from the villous tips but no specific changes when compared to the control group. The results are discussed in terms of enzymic localization in the brush border membrane; SA would be located very superficially in the surface membrane and AP buried in the membrane and less accessible than the other enzymes.

Alkaline Phosphatase↗
PubMed1977

Subpopulations of T-lymphocytes in Peyer's patches: sensitivity to antilymphocyte serum and adult thymectomy.

Anti-lymphocyte (ALS) treatment or adult thymectomy of the donor have been shown to depress respectively the cell proliferation and the cytotoxicity in the graft-versus-host (GVH) reaction. A quantitative assay and the histological criteria of the GVH reaction have been used to demonstrate that all the known subpopulations of T-lymphocytes involved in the GVH reaction are present in the Peyer's patches as well as in the spleen and mesenteric lymph nodes in the rat.

Animals↗
PubMed1977

Ex vivo vascular perfusion of the isolated rat small bowel. Importance of the intestinal brush border enzyme-release in basal conditions.

The vascular perfusion of the whole isolated intestine of the rat with homologous non-diluted blood is compared with classical in vivo experiments. During a 2 1/2-hour perfusion procedure no significant difference was noted between the two experimental schedules as far as haemodynamic, histological, mechanical and/or electrical activities of the gut are concerned. However, striking changes in the intestinal brush border enzyme output within the lumen appear between ex vivo and in vivo experiments. The early increase of intraluminal intestinal sucrase, already after the 95th min of perfusion indicate clearly the existence of a subcellular damage even not detectable by other tests of viability. Therefore, it is suggested that release of brush border enzymes might represent an interesting criterion of viability of in vitro or ex vivo preparations.

Alkaline Phosphatase↗
PubMed1976

Simultaneous recording of circular and longitudinal muscle contractions of the canine jejunum.

A method has been developed for monitoring the mechanical activities of individual longitudinal and circular muscles in a 5 millimeters long segment of intact intestine in the anesthetized dog. The longitudinal contractions were recorded by means of a new movement transducer. The circular contractions were recorded simultaneously using a water-filled intraluminal balloon. A precise separation of longitudinal and circular motor activities was obtained with this method. The two muscle layers manifested motor activity most of the time, but their contractions were out of phase. Phase locking was observed only during short periods of time. The contractions were then sequential, the circular one being first.

Animals↗
PubMed1976

A simple device to obtain a pulsatile flow. Application to the vascular perfusion of dogs isolated intestinal segments.

A simple device allowing a pulsatile flow to be obtained in isolated organ perfusion has been developed and applied to the vascular perfusion of isolated canine jejunal segments. The principle of the device consists of superimposing on a constant pressure produced by a roller pump, a pulsatile pressure of which the amplitude, frequency, and shape of the pulses can be adjusted separately and independently of the mean pressure value. The role of the arterial pulse in intestinal vascular perfusion has been studied by comparing the hemodynamic and metabolic behavior during alternate periods of pulsatile and nonpulsatile pumping. While no striking change in vascular resistance was observed, the O2 consumption was significantly increased under pulsatile flow. These results testify to better metabolic conditions and enhanced organ functions under pulsatile pumping and also argue for improved intestinal microcirculation despite the constancy of the vascular resistance.

Animals↗
PubMed1976

The effects of transections on the basic electrical rhythm in the canine jejunum.

The basic electrical rhythm (BER) was studied in situ in the jejunum in 14 anaesthetized mongrel dogs by the mean six monopolar electrodes. The BER frequency was measured in the intact intestine and after proximal and distal transections of the gut 5 cm apart from the electrodes. No significant differences were found between the BER frequencies recorded by each electrode, demonstrating the existence of a frequency plateau which remained after each transection. In the intact intestine the frequency in the plateau was 13.2 +/- 0.3 cpm2. After the proximal transection, this frequency dropped to 12.0 +/- 0.4 cpm (p less than 0.05) and, after the distal transection, it dropped to 10.9 +/- 0.4 cpm (p less than 0.005). This last frequency change shows the influence of the distal intestine on the electrical behaviour of the jejunum.

Action Potentials↗
PubMed1975

Intrahepatic lymphoid tissue graft: course of the Gvh reaction induced by Peyer's patches.

To investigate the thymus-dependent immune competence of Peyer's patches, the course of splenomegaly and hepatic perivascular infiltration (PVI) was studied as criteria of graft-versus-host reaction (GvhR). Parental or F1 hybrid lymphoid tissues, were intrahepatically implanted and the ability of Peyer's patches to induce a GvhR was compared to that of spleen, lymph nodes and thymus. A slight but significant delayed increase of spleen index was observed at the 40th post operative day following Peyer's patches implantation whereas the thymus did not induce any modification of this parameter. On the other hand, the PVI was a very early and precise criterion in monitoring the Gvh reaction induced by Peyer's patches, and allowed to postulate that at least one T-cell function is present within the Peyer's patches.

Animals↗