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S Carpentier

Publications and source records attributed to S Carpentier.

At least 37 records · Page 2Linked to original sources
PubMed1997

Interobserver agreement in the staging of rectal cancer using endoscopic ultrasonography.

BACKGROUND AND STUDY AIMS: In rectal tumors invasion of the rectal fat and perirectal lymph nodes are generally regarded as independent prognostic factors in most prospective series. There are no studies in the literature concerning interobserver agreement on the staging of rectal cancer by endorectal ultrasonography (EUS). The aim of the present study was to assess interobserver agreement using EUS in the TN staging of rectal cancer. PATIENTS AND METHODS: Thirty-seven patients with rectal cancer were investigated at two centers using EUS as part of the pretherapeutic staging (Olympus EUM-3 or EUM-20). All examinations were videotaped and reviewed six months later by four independent observers who assessed the stage of the tumor (from uT1 to uT4) and lymphatic invasion on a blinded basis. When the tumor was assessed as uT3, the observers specified the degree of involvement of the rectal fat (in millimeters). Interobserver agreement was estimated using the kappa coefficient (k) and the intraclass correlation coefficient (ICC). Agreement was classed as poor (k < 0.40), fair to good (0.40 < or = k < 0.75) or excellent (k < or = 0.75). RESULTS: Agreement was fair for uT1 tumors (k = 0.40) and poor for uT2 tumors (k = 0.20). Agreement was good (k = 0.58; CI 0.51 to 0.65) for uT3 tumors; there was a significant interobserver correlation for the exact measure of the extent of rectal fat (ICC = 0.65). The agreement was also good (k = 0.54, CI 0.47 to 0.61) for metastatic lymph nodes. CONCLUSION: As in the case of esophageal cancer, interobserver agreement on the staging of uT2 tumors is poor with EUS. The evaluation of rectal tumors with a poor prognosis shows good interobserver agreement.

Adenocarcinoma↗
PubMed1996

Endoscopic ultrasonographic signs of portal hypertension in cirrhosis.

BACKGROUND: Endoscopic ultrasonography (EUS) has been suggested to investigate portal hypertension (PHT). We compared EUS and endoscopy in the exploration of PHT in cirrhosis. METHODS: In 58 patients with cirrhosis and 16 controls, the presence of esophageal varices and gastric varices was recorded by both endoscopy and EUS, peridigestive varices and perforating veins by EUS. Relationships of patterns with each other and with clinical and biologic data were evaluated. RESULTS: In patients with cirrhosis: esophageal varices were found by endoscopy and EUS in 88% and 55% of cirrhotic cases (p < 0.01), and gastric varices in 17% and 41%, respectively (p < 0.01). Perforating veins, below the gastroesophageal junction, were diagnosed by EUS in 40% of cases and never in controls. A significant relationship was found between perforating veins and the following patterns: peri-digestive varices, gastric varices at EUS, and esophageal varices at endoscopy. In patients with and without cirrhosis: after multivariate analysis, only esophageal varices at endoscopy were independently related to cirrhosis. However, in Child-Pugh class A patients, both esophageal varices and perforating veins were independently related to cirrhosis (diagnostic accuracy, 92%). CONCLUSIONS: EUS is of limited value in the diagnosis of cirrhosis because it gives little additional information to upper gastrointestinal endoscopy. The relationships between perforating veins, varices, and peridigestive varices support the hypothesis that perforating veins are important in the pathogenesis of esophageal and gastric varices.

Endoscopy, Gastrointestinal↗
PubMed1996

Proteins and bioprosthetic calcification in the rat model.

BACKGROUND AND AIM OF THE STUDY: The mechanism of valvular bioprostheses calcification is still unknown, but early studies showed increased Gla-protein content in calcified valves. Using an experimental model, which reproduces the clinical process, we therefore analyzed the role of minerals and proteins in bioprosthetic valvular calcification. METHODS: Glutaraldehyde pretreated porcine valves were studied before and after implantation in rats by X-ray, calcium (Ca) and phosphorus (P) measurement, Fourier Transform Infrared (FTIR) spectroscopy, SDS-PAGE and 45Ca ligand blotting of the extracted proteins. RESULTS: Before implantation, there was no X-ray calcification with very little Ca and P content. After implantation, X-ray calcifications appeared on day seven with increased Ca and P up to day 35 (p < 0.05, ANOVA). FTIR revealed structural proteins alone before implantation, plus minor proportions of lipids on day two, which always preceded Ca and P appearance. Ca and P increased up to day 35, first as amorphous and changed in carbapatite over time. SDS-PAGE before implantation revealed two proteins (66-kD and 54-kD) alone, which were sustained up to day 35. The 66-kD had 45Ca affinity. On day two, many other proteins appeared on SDS-PAGE, four of which (52, 45, 14 and below 14-kD) with 45Ca affinity. Protein pattern did not change from day two to 35. CONCLUSIONS: Valvular bioprosthesis calcification is associated with progressive increase in Ca and P content and at least five calcium-binding proteins: one intrinsic valvular protein, pre-existing to implantation, plus four other, extrinsic valvular proteins adsorbed within the tissue after implantation.

Animals↗
PubMed1995

Multicentre prospective controlled study of Barrett's oesophagus and colorectal adenomas. Groupe d'Etude de l'Oesophage de Barrett.

Previous studies have suggested that patients with Barrett's oesophagus may be at increased risk of colorectal neoplasia, though the association is disputed. In a multicentre prospective study we compared the prevalence of colorectal adenomas in patients with Barrett's oesophagus and controls. Barrett's oesophagus patients (n = 104) had histological confirmation of columnar epithelium extending more than 3 cm above the gastro-oesophageal junction. The 537 controls were patients with symptoms suggesting irritable bowel syndrome. No participant had a personal history of colonic neoplasm. Each patient underwent colonoscopy. Histologically proven adenomas were found in 26 Barrett's patients (25%) and 75 controls (14%). Three colorectal cancers were discovered in each group. The prevalence of adenomas was greater in the Barrett's oesophagus group than in the control group (p < 0.01) but the relation became non-significant after adjustment for age and sex and control for other known risk factors by a logistic regression model (odds ratio 1.4 [0.7-2.7]). The relative risk of adenoma was significantly higher in patients older than 59 than in younger patients (2.2 [1.3-3.5]) and in men than in women (3.4 [2.0-5.7]). Other factors contributing significantly to the risk of adenoma were a family history of colorectal cancer (2.3 [1.1-4.8]), rectal bleeding (2.1 [1.1-3.9]), previous colonic investigation (0.3 [0.1-0.7]), and complete as opposed to partial colonoscopy (6.4 [0.8-48.3]). We conclude that Barrett's oesophagus is not an independent risk factor for colorectal neoplasia and, therefore, is not, in itself an indication for colorectal screening.

Adenoma↗
PubMed1993

[Phosphocalcium metabolism in patients with calcified valvular bioprosthesis].

Calcium and gla-protein content are increased in the calcifications of cardiac bioprostheses. Such calcifications are more frequent during growth, pregnancy and renal failure when bone gla-protein levels are elevated. We investigated whether bone gla-protein and other markers of calcium metabolism play a role in bioprostheses calcifications. Forty-seven patients were separated into 2 groups according to the presence (group A, n = 9) or absence (group B, n = 38) of bioprostheses calcifications, as assessed by echo-doppler and surgery. Plasma levels of calcium, phosphorus, magnesium, creatinine and alkaline phosphatases were measured by standard laboratory methods, parathormone and those of bone gla-protein by specific radioimmunoassays. Results (mean +/- SEM) were compared (group A versus group B, P < 0.01) using Student's test and one-factor variance analysis (ANOVA). Age was similar in both group (53 +/- 12.9 vs 50 +/- 12.3 yrs), whereas duration of implant was greater in group A (104 +/- 12.4 vs 66 +/- 6.5 months, P < 0.01). No statistically significant difference was found between group A and B concerning biochemical and/or hormonal markers of calcium metabolism. These negative results merit to be discussed, and further studies will be needed to explore the potential role of circulating bone gla-protein in bioprostheses calcifications.

Aortic Valve↗
PubMed1993

Terlipressin plus transdermal nitroglycerin vs. octreotide in the control of acute bleeding from esophageal varices: a multicenter randomized trial.

We undertook a multicenter randomized trial to compare the efficacy of terlipressin combined with transdermal nitroglycerin and that of octreotide in the emergency control of acute variceal hemorrhage in cirrhosis. Over 16 mo, 87 patients with endoscopically proved active bleeding from esophageal or cardiac varices were enrolled in five centers in France and randomly assigned to receive intravenous terlipressin (2 mg and then 1 mg/4 hr over 24 hr) and transdermal nitroglycerin (10 mg/12 hr over 24 hr) (group 1) or octreotide (continuous intravenous infusion of 25 micrograms/hr over 12 hr and then 100 micrograms at hr 12 and hr 18 subcutaneously) (group 2). Initial control of bleeding was assessed at the end of 12 hr of treatment on the basis of stability of blood pressure and hematocrit level with no further transfusion requirements. At 12 hr, bleeding was controlled in 59% (24 of 41) in group 1 and 78% (36/46) of group 2 patients (Fisher's exact test, p = 0.064). Mean transfusion requirements over this 12-hr period were significantly greater in group 1 (three blood units; range = 0 to 13) than in group 2 (one blood unit; range = 0 to 5) (p = 0.002). After the first 12 hr, 20% of patients (5 of 24) had repeat bleeding in group 1 compared with 27% (10 of 36) in group 2. During the first 48-hr period, five patients (12%) died in group 1, compared with 3 (6%) in group 2. Few side effects were noted in either group. However, in group 1 two patients experienced severe bradycardia; it resulted in death in one patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1993

[Place of endorectal ultrasonography in the evaluation of staging of cancer of the rectum: before or after preoperative radiotherapy?].

Of 62 patients with rectal carcinoma, who were examined by endorectal ultrasound (EER) before operation, 15 were examined after preoperative external radiation therapy. The results were compared to histological and surgical findings according to the TNM classification. When preoperative radiation therapy was not applied, the diagnostic value of EER was excellent, as well as for the detection of perirectal fat spread as for lymph node involvement. The diagnostic accuracy was respectively 87.2% (CI: 74-95) and 78.0% (CI: 62-90). After irradiation, the diagnostic value was much lower. The diagnostic accuracy was 60% (CI:33-84) and 40% (CI:18-68) for perirectal fat spread and nodal involvement, respectively. This loss of information was due to a decrease in specificity. Radiation treatment was responsible for the occurrence of hypoechoic nodal images and peritumoral hypoechoic areas resulting in an overestimation of the extent of involvement. After irradiation of a rectal malignant tumor, the classical EER signs are no longer adequate to predict locoregional involvement. Endosonographic semiology must be modified to describe the tumor response to non surgical treatment.

Adult↗
PubMed1988

Cardiovascular effects and modulation of noradrenergic neurotransmission following central and peripheral administration of neuropeptide Y.

Experiments have been conducted to evaluate the effect of neuropeptide Y (NPY) administered at three distinct levels of the nervous system: 1) the posterior hypothalamic nucleus, 2) the spinal cord, and 3) the vascular noradrenergic neuroeffector junction. It was observed that NPY produced varying cardiovascular effects at these three distinct sites of the nervous system. Microinjections into the posterior hypothalamic nucleus resulted in an increase in blood pressure, which was reduced by prior microinjection of a muscarinic or H1-histamine antagonist but not an H2-histamine antagonist. In addition to the involvement of histaminergic and cholinergic pathways, the pressor effect of NPY appears to result from an increase in sympathetic outflow. NPY was also seen to decrease the potassium-induced release of norepinephrine (NE) from slices obtained from the posterior hypothalamic nucleus. In contrast to what was observed in the hypothalamus, the intrathecal injection of NPY at a level of T4 or T10 in anesthetized or T10 in unanesthetized rats resulted in a depressor effect as well as a decrease in heart rate. Both an alpha 2- and beta-adrenoceptor antagonist reduced the NPY effect. The depressor effect of intrathecal NPY was attenuated in rats pretreated with reserpine as well as in Spontaneously Hypertensive rats (SHR). These data suggest that the effects of NPY are closely associated with sympathetic preganglionic neurons in the spinal cord. At the vascular noradrenergic neuroeffector junction, NPY decreased the nerve stimulation-induced release of NE while potentiating the contractile response. Moreover, NPY potentiated the increase in perfusion pressure of the perfused mesenteric arterial bed in response to angiotensin, vasopressin, or phenylephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

[Contribution of microradiography in search of calcifications of valvular bioprostheses].

Implantation of a valvular bioprosthesis is one of the best treatments for valvular disease, particularly in children. Unfortunately, their use is limited as calcifications develop over time. Prevention of these calcifications is still an unresolved problem that is under study by Professor Carpentier and coworkers. These investigators have developed an experimental model in which accelerated development of calcifications occurs: fragments of porcine valves implanted under the skin of rats become calcified in a few days. Prior to implantation, the fragments are pretreated in an attempt to delay or prevent the development of calcifications. Two, four, six and eight months after implantation, the fragments are removed and calcifications are looked for using microradiography. Two hundred fragments have been studied. The material and technique used in our study are described. Results are semi-quantitative, based on the volume of calcifications. We conclude that microradiography is faster and more reliable than histology (the only technique used up till now) as it allows to study the entire fragments.

Animals↗
PubMed1987

Prejunctional and postjunctional effects of neuropeptide Y at the noradrenergic neuroeffector junction of the perfused mesenteric arterial bed of the rat.

The effect of neuropeptide Y (NPY) on periarterial nerve stimulation-induced release of norepinephrine (NE) and increase in perfusion pressure in the perfused mesenteric arterial bed of the rat was examined. Perfusate effluents were continuously collected and assayed for endogenous NE by high-pressure liquid chromatography (HPLC) coupled to electrochemical detection. Perfusion pressure was continuously monitored by means of a pressure transducer. Periarterial nerve stimulation (8 or 16 Hz, 60 V, 2-ms duration for 30 s) resulted in a readily detectable increase in NE release and perfusion pressure that was attenuated by the prior administration of tetrodotoxin (TTX) (10(-5) M) or guanethidine (5 X 10(-5) M). NPY exerted both prejunctional and postjunctional effects on noradrenergic neurotransmission in this preparation. The peptide produced a concentration-dependent reduction in the release of NE over a concentration range of 10(-10) - 10(-7) M. A similar inhibition effect occurred at 8, 10, and 16 Hz. In contrast, low concentrations (10(-10) and 10(-9) M) decreased the effect of nerve stimulation on perfusion pressure, whereas higher concentrations (10(-7) M) produced a marked potentiation. The alpha 2-adrenoceptor antagonist, yohimbine, did not alter the inhibitory effect of NPY on evoked NE release or the effect on perfusion pressure. Prazosin similarly did not alter the inhibitory effect of NPY on NE release but prevented the increase in perfusion pressure. We conclude that NPY modulates noradrenergic neurotransmission in the mesenteric arterial bed by decreasing the evoked release of NE and producing a concentration-dependent biphasic response on vascular smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Alterations in the release of norepinephrine at the vascular neuroeffector junction in hypertension.

The field stimulation induced release of 3H-norepinephrine (NE) from the isolated portal vein and endogenous NE from the isolated caudal artery and perfused mesenteric arterial bed of spontaneously hypertensive rats (SHR) and age-matched normotensive rats (Wistar-Kyoto or Sprague-Dawley) was studied. There was a significantly greater release of NE from all three preparations obtained from 10- to 12-week-old SHR compared to normotensive animals. In addition, there was a greater release of NE from the caudal artery of 5- to 6-week-old SHR compared to controls. No differences were seen in the evoked release of NE from portal vein or caudal artery obtained from renal or DOCA salt hypertensives compared to vessels obtained from sham controls. Neuropeptide Y (NPY) produced a concentration-dependent decrease in the field stimulation induced release of NE from the perfused mesenteric artery. Low concentrations of NPY decreased while higher concentrations potentiated the increase in perfusion pressure. The NPY induced inhibition of evoked NE release was not altered by alpha 1- or alpha 2-adrenoceptor antagonists while the alpha 1-adrenoceptor antagonist, prazosin, prevented the postjunctional response. These results are consistent with there being an alteration of NE release at the vascular neuroeffector junction in SHR which may contribute to the development or maintenance of hypertension. NPY exerts a modulatory role in noradrenergic transmission at the vascular neuroeffector junction.

Animals↗
PubMed1986

Comparison of norepinephrine release in hypertensive rats: II. Caudal artery and portal vein.

It was observed that there was a significantly greater field-stimulation induced release of norepinephrine from the portal vein and caudal artery obtained from 28 week old SHR compared to WKY. The greater field-stimulation induced release of norepinephrine observed in the blood vessels of the SHR compared to WKY was not seen in DOCA-salt and one kidney-one clip hypertensive animals with similar elevations of systolic blood pressure. It was also observed that there was an attenuation of the effect of the prejunctional alpha 2-adrenoceptor antagonist, yohimbine to enhance the field-stimulation induced release of norepinephrine from blood vessels of the 28 week old SHR. There was no attenuation of the yohimbine effect in the other two models of hypertension. It is concluded that there is an alteration in the release of norepinephrine from blood vessels of SHR, resulting in a greater evoked release of the transmitter. A decrease in the functional activity of prejunctional alpha 2-adrenoceptor may contribute to the enhanced release of norepinephrine from the blood vessels of the SHR.

Animals↗
PubMed1984

Techniques for prevention of calcification of valvular bioprostheses.

Calcification of valvular bioprostheses in children is a major problem that has stimulated extensive research in our laboratory. In previous reports, we have shown that the rate of calcification could be reduced by decreasing the phosphate content in the tissue or by blocking calcification binding sites with Mg++ and/or with a surfactant (Tween 80). Since then, we have systematically investigated incorporation of numerous other surfactants and of polyacrylamide within the tissue, and these investigations form the basis of this report. The methods of investigation included subcutaneous implantation of treated tissues in growing rabbits, stability tests, and intracardiac implantation in sheep. Results showed that surfactants differed in their efficacy in mitigating calcification, with N-lauroylsarcosine and triton X-100 being the most efficient. Polyacrylamide incorporation was also efficient in calcification mitigation, but this effect was lost after flexibility testing in vitro or implantation in vivo, a drawback that suggests further research is necessary into stabilization of this polymer. This report not only brings attention to new alternatives in calcification mitigation treatment of bioprosthetic tissues but also underlines important points of methodology.

Acrylic Resins↗