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C Coste

Publications and source records attributed to C Coste.

14 recordsLinked to original sources
PubMed2002

Normal-mode-vortex interactions.

Standing surface waves that interact with a confined, vertical, vorticity field with zero net circulation are studied both analytically and experimentally. The surface waves are generated by vertical vibration, and constant vorticity injection is achieved by a rotating disk flush mounted in the cell. Experimental results are indicative of a local wave-vortex interaction (no dislocation), and a simple theoretical model is able to explain them in quantitative detail.

Journal Article↗
PubMed2001

Efficacy of macrolides vs. metronidazole against Entamoeba histolytica clinical isolates.

Current treatment of Entamoeba histolytica infection requires the use of several agents that are effective at different sites of the body. Commonly administered agents such as nitroimidazoles have a high rate of gastrointestinal side effects and their use is restricted during pregnancy. In order to offer new choices, four macrolide antibiotics (erythromycin, clarithromycin, azithromycin, josamycin) and metronidazole were tested for their in vitro activity against E. histolytica. Ten clinically isolated strains from an endemic area (Santo Domingo, Dominican Republic) were tested after polyxenical culture. Protozoan viability was significantly reduced by josamycin after 24 and 48 hours of incubation at a concentration of > or = 50 mg/l, which was slightly higher than that of metronidazole (25 mg/l). No resistance to metronidazole was found. The antiamebic activity of azithromycin, clarithromycin and erythromycin was significant at drug concentrations > or = 100 mg/l. High doses of josamycin, which is a very well tolerated drug, may serve as a useful therapeutic agent in the presence of E. histolytica infection.

Animals↗
PubMed2001

Reduced isoflurane consumption with bispectral index monitoring.

BACKGROUND: Bispectral index (BIS) monitoring has been found to decrease the requirements for propofol, sevoflurane and desflurane and to improve recovery. We wanted to assess the effect of BIS monitoring on intraoperative isoflurane utilisation, and the early recovery profile. METHODS: Eighty patients undergoing various surgical procedures were studied. In the first phase of the study, patients were anaesthetised without the use of BIS, the anaesthetists being blinded to the BIS readings, and isoflurane being administered according to standard clinical practice (control group). In a second phase, isoflurane was titrated to maintain a BIS value between 40 and 60 during surgery, and then 60-70 during 15 min prior to the end of surgery (BIS group). Isoflurane consumption was measured. Recovery times and the time to achieve a modified Aldrete score of 9 were recorded. RESULTS: Despite similar mean BIS levels during maintenance of anaesthesia, the cumulative time spent with BIS values between 40 and 60 during maintenance of anaesthesia was significantly longer in the BIS group as compared with the control group (P<0.001). The isoflurane usage in the BIS group was 12-25% lower than in the control group (P<0.05). The time to awakening and extubation were comparable in the two groups. Although the patients were less sedated (P<0.01) during the three postoperative hours in the BIS (vs. control) group, no significant differences were observed in the time to obtain an Aldrete score of 9. CONCLUSION: The addition of BIS to standard monitoring decreases isoflurane consumption. However, we found only a small advantage in using BIS with respect to recovery from isoflurane anaesthesia.

Adult↗
PubMed2000

Nitrous oxide prevents movement during orotracheal intubation without affecting BIS value.

UNLABELLED: We sought to determine whether the addition of nitrous oxide (N(2)O) to an anesthetic with propofol and remifentanil modifies the bispectral index (BIS) during the induction of anesthesia and orotracheal intubation. Thirty ASA physical status I or II patients were randomly allocated to receive either 50% air in oxygen (control group) or 60%-70% N(2)O in oxygen (N(2)O group) that was commenced via a mask simultaneously with the induction of anesthesia. Anesthesia was performed in all the patients with IV propofol at the target effect compartment site concentration of 4 microg/mL throughout the study. A target-controlled infusion (TCI) of remifentanil was initiated 3 min after the TCI of propofol and maintained at the effect-site concentration of 4 ng/mL until the end of the study. After loss of consciousness, and before the administration of vecuronium 0.1 mg/kg, a tourniquet was applied to one arm and inflated to a value more than the systolic blood pressure. An examiner, blinded to the presence of N(2)O, sought to detect any gross movement within the first minute after tracheal intubation, which was performed 10 min after remifentanil TCI began. Inspired and expired oxygen, N(2)O, and carbon dioxide were continuously monitored. A BIS value was generated every 10 s. Arterial blood pressure and heart rate (HR) were measured noninvasively every minute. Measures of mean arterial pressure (MAP), HR, and BIS were obtained before the induction, before the start of the remifentanil TCI, before laryngoscopy, and 5 min after intubation. No significant intergroup differences were seen in BIS, HR, and MAP throughout the study. Maximum changes in BIS, HR, and MAP with intubation were significant (P < 0.01) for both groups but comparable. Six patients in the control group and none in the N(2)O group moved after intubation (P < 0.05). IMPLICATIONS: We demonstrated that 0.6 minimal alveolar concentration of nitrous oxide combined with a potent anesthetic and an opioid prevents movement after orotracheal intubation without affecting the bispectral index. This demonstrates that the bispectral index is not a useful neurophysiologic variable to monitor the level of anesthesia when nitrous oxide is added to a general anesthetic regimen using propofol and remifentanil.

Adolescent↗
PubMed2000

Acute opioid tolerance: intraoperative remifentanil increases postoperative pain and morphine requirement.

BACKGROUND: Rapid development of acute opioid tolerance is well established in animals and is more likely to occur with large doses of short-acting drugs. The authors therefore tested the hypothesis that intraoperative remifentanil administration results in acute opioid tolerance that is manifested by increased postoperative pain and opioid requirement. METHODS: Fifty adult patients undergoing major abdominal surgery were randomly assigned to two anesthetic regimens: (1) desflurane was kept constant at 0.5 minimum alveolar concentrations and a remifentanil infusion was titrated to autonomic responses (remifentanil group); or (2) remifentanil at 0.1 microg. kg-1. min-1 and desflurane titrated to autonomic responses (desflurane group). All patients were given a bolus of 0.15 mg/kg morphine 40 min before the end of surgery. Morphine was initially titrated to need by postanesthesia care nurses blinded to group assignment. Subsequently, patients-who were also blinded to group assignment-controlled their own morphine administration. Pain scores and morphine consumption were recorded for 24 postoperative h. RESULTS: The mean remifentanil infusion rate was 0.3 +/- 0.2 microg. kg-1. min-1 in the remifentanil group, which was significantly greater than in the desflurane group. Intraoperative hemodynamic responses were similar in each group. Postoperative pain scores were significantly greater in the remifentanil group. These patients required morphine significantly earlier than those in the desflurane group and needed nearly twice as much morphine in the first 24 postoperative h: 59 mg (25-75% interquartile range, 43-71) versus 32 mg (25-75% interquartile range, 19-59; P < 0.01). CONCLUSIONS: Relatively large-dose intraoperative remifentanil increased postoperative pain and morphine consumption. These data suggest that remifentanil causes acute opioid tolerance and hyperalgesia.

Analgesia, Patient-Controlled↗
PubMed1999

Scattering of dislocated wave fronts by vertical vorticity and the Aharonov-Bohm effect. I. Shallow water.

When a surface wave interacts with a vertical vortex in shallow water the latter induces a dislocation in the incident wave fronts that is analogous to what happens in the Aharonov-Bohm effect for the scattering of electrons by a confined magnetic field. In addition to this global similarity between these two physical systems there is scattering. This paper reports a detailed calculation of this scattering, which is quantitatively different from the electronic case in that a surface wave penetrates the inside of a vortex while electrons do not penetrate a solenoid. This difference, together with an additional difference in the equations that govern both physical systems, lead to a quite different scattering in the case of surface waves, whose main characteristic is a strong asymmetry in the scattering cross section. The assumptions and approximations under which these effects happen are carefully considered, and their applicability to the case of the scattering of acoustic waves by vorticity is noted.

Journal Article↗
PubMed1999

Scattering of dislocated wave fronts by vertical vorticity and the Aharonov-Bohm effect. II. Dispersive waves.

Previous results on the scattering of surface waves by vertical vorticity on shallow water are generalized to the case of dispersive water waves. Dispersion effects are treated perturbatively around the shallow water limit, to first order in the ratio of depth to wavelength. The dislocation of the incident wave front, analogous to the Aharonov-Bohm effect, is still observed. At short wavelengths the scattering is qualitatively similar to the nondispersive case. At moderate wavelengths, however, there are two markedly different scattering regimes according to whether the depth is smaller or larger than sqrt[3] times capillary length. In the latter case, dispersion and advection may compensate leading to a spiral interference pattern. The dislocation is characterized by a parameter that depends both on phase and group velocity. The validity range of the calculation is the same as in the shallow water case: wavelengths small compared to vortex radius, and low Mach number. The implications of these limitations are carefully considered.

Journal Article↗
PubMedDate not supplied

Morphological significance of associated epithelial cords and ductlike structures in certain tumors of the pancreatic islets.

The association of epithelial cord cells and ductlike structures in 2 cases of pancreatic islet tumors is presented. The first case was characterized by multiple pancreatic nodes of beta cell insulinoma in a 35-year-old woman. The second case was a Zollinger-Ellison syndrome in a 10-year-old male child with perforated duodenal ulcer due to an islet cell tumor of an aberrant pancreas in the omentrum. Stress is laid upon the striking continuity of the tumorous endocrine and exocrinelike histological formations reproducing the morphological pattern of ducto-insular relationships in histogenesis and islet regeneration.

Adenoma, Islet Cell↗