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Biomedical subjects

O Giraud

Publications and source records attributed to O Giraud.

16 recordsLinked to original sources
PubMed2005

Quantum computing of delocalization in small-world networks.

We study a quantum small-world network with disorder and show that the system exhibits a delocalization transition. A quantum algorithm is built up which simulates the evolution operator of the model in a polynomial number of gates for an exponential number of vertices in the network. The total computational gain is shown to depend on the parameters of the network and a larger than quadratic speedup can be reached. We also investigate the robustness of the algorithm in presence of imperfections.

Journal Article↗
PubMed2002

Nearest-neighbor distribution for singular billiards.

The exact computation of the nearest-neighbor spacing distribution P(s) is performed for a rectangular billiard with a pointlike scatterer inside for periodic and Dirichlet boundary conditions, and it is demonstrated that when s-->infinity this function decreases exponentially. Together with the results of Bogomolny, Gerland, and Schmit [Phys. Rev. E 63, 036206 (2001)], it proves that spectral statistics of such systems is of intermediate type characterized by level repulsion at small distances and exponential fall-off of the nearest-neighbor distribution at large distances. The calculation of the nth nearest-neighbor spacing distribution P(n)(s) and its asymptotics is performed as well for any boundary conditions.

Journal Article↗
PubMed2000

Halothane reduces the early lipopolysaccharide-induced lung inflammation in mechanically ventilated rats.

Several studies suggest that anesthetics modulate the immune response. The aim of this study was to investigate the effect of halothane and thiopental on the lung inflammatory response. Rats submitted or not to intratracheal (IT) instillation of lipopolysaccharides (LPS) were anesthetized with either halothane (0. 5, 1, or 1.5%) or thiopental (60 mg. kg(-1)) and mechanically ventilated for 4 h. Control rats were treated or not by LPS without anesthesia. Lung inflammation was assessed by total and differential cell counts in bronchoalveolar lavage fluids (BALF) and by cytokine measurements (tumor necrosis factor-alpha [TNF-alpha], interleukin-6 [IL-6], macrophage inflammatory protein-2 [MIP-2], and monocyte chemoattractant protein-1 [MCP-1]) in BALF and lung homogenates. In the absence of LPS treatment, neither halothane nor thiopental modified the moderate inflammatory response induced by tracheotomy or mechanical ventilation. Cell recruitment and cytokine concentrations were increased in all groups receiving IT LPS. However, in halothane-anesthetized rats (halothane > or = 1%), but not in thiopental-anesthetized rats, the LPS-induced lung inflammation was altered in a dose-dependent manner. Indeed, when using 1% halothane, polymorphonuclear leukocyte (PMN) recruitment was decreased by 55% (p < 0.001) and TNF-alpha, IL-6, and MIP-2 concentrations in BALF and lung homogenates were decreased by more than 60% (p < 0.001) whereas total protein and MCP-1 concentrations remained unchanged. The decrease of MIP-2 (observed at the protein and messenger RNA [mRNA] level) was strongly correlated to the decrease of PMN recruitment (r = 0.73, p < 0.05). This halothane-reduced lung inflammatory response was transient and was reversed 20 h after the end of the anesthesia. Our study shows that halothane > or = 1%, delivered during 4 h by mechanical ventilation, but not mechanical ventilation per se, alters the early LPS-induced lung inflammation in the rat, suggesting a specific effect of halothane on this response.

Anesthetics, Inhalation↗
PubMed1998

Aging prolongs recovery of psychomotor functions at emergence from propofol-alfentanil anaesthesia.

PURPOSE: To compare recovery of psychomotor function in elderly and young surgical patients at emergence from propofol-alfentanil anaesthesia. METHODS: Ten elderly (> 70 yr) and 10 younger (< 40 yr) patients scheduled for orthopaedic surgery of less than three hours, were anesthetized with nitrous oxide, propofol and alfentanil. Propofol and alfentanil cumulative doses, time from cessation of propofol infusion to eye opening (EO) on verbal command and to extubation were recorded. Psychomotor performance was assessed by the Mini-Mental State (MMS) performed the day prior to surgery and postoperatively at 30, 60, and 120 min, following extubation. Propofol blood concentrations were measured at EO and at each MMS task. RESULTS: Elderly patients were comparable with young patients for preoperative MMS scores, surgery and anaesthesia duration, propofol and alfentanil cumulative doses. Postoperative MMS scores were lower at 30, 60 and 120 min, in elderly patients. Propofol blood concentrations were not different between elderly and young patients at EO, 30, 60 and 120 min. CONCLUSION: Psychomotor performance is impaired in elderly compared with young patients at emergence from propofol-alfentanil anaesthesia. These differences are not likely to be related to propofol accumulation in elderly subjects.

Adult↗
PubMed1998

[A cause of intubation failure: a subglottic bridge].

We report the case of a patient with a history of facio-thoracic burns, the treatment of which included prolonged intubation, whose trachea could not be intubated because of a subglottic obstacle. The ventilation was easily controlled with a laryngeal mask. At the end of surgery for postburn cheloids, laryngoscopy through the laryngeal mask showed a transversal subglottic laryngeal band, a probable sequela of the previous prolonged intubation. The band was resected one week later. The conventional indicators for difficult intubation cannot detect the laryngotracheal obstacles to tracheal tube insertion.

Airway Obstruction↗
PubMed1997

Limits of laryngeal mask airway in patients after cervical or oral radiotherapy.

PURPOSE: To test the efficacy of the LMA in patients with previous oral or cervical radiotherapy, without upper airway obstruction. METHODS: In nine patients after oral or cervical radiotherapy, efficiency of ventilation was assessed after induction of general anaesthesia and LMA insertion. Fibreoptic examination through the tube was performed to check the position of LMA. RESULTS: In patients who had had oral radiotherapy, all five had limited mouth opening and in two, LMA insertion was difficult but permitted good ventilation. In the four patients who had had cervical radiotherapy, LMA insertion was easy but, in two, the lungs were difficult to ventilate and, in two, the lungs could not be ventilated and orotracheal intubation was required. CONCLUSION: In patients with limitation of mouth opening after oral radiotherapy, LMA may represent an alternative to tracheal intubation. In patient with cervical sclerosis after radiotherapy; the use of LMA should be avoided.

Adult↗
PubMed1997

Emergence of elderly patients from prolonged desflurane, isoflurane, or propofol anesthesia.

UNLABELLED: Recovery from prolonged anesthesia might be compromised in elderly patients. Desflurane (DES) may be particularly well suited to achieve a rapid postoperative recovery because of its low lipid solubility. Postoperative recovery was compared in 45 elderly patients randomized to receive either DES, isoflurane (ISO), or propofol (PRO) to maintain anesthesia. Anesthesia was induced with PRO, vecuronium, and fentanyl and maintained with N2O, fentanyl, and the study drug. Times from end of anesthesia to tracheal extubation, eye opening and hand squeezing on command, and ability to state name and date of birth were recorded. Sedation and psychometric evaluation were tested 0.5, 1, 1.5, 2, and 24 h postoperatively. Results are given as means +/- SD. Differences among were analyzed by chi2 or analysis of variance. P < 0.05 compared with DES was considered significant. After a prolonged anesthesia (199 +/- 57 min with DES), immediate recovery times were significantly shorter with DES than with ISO or PRO (times to eye opening: 5.6 +/- 3.4 min, 11.5 +/- 8.4 min, and 11.9 +/- 7.6 min; times to extubation: 6.9 +/- 3 min, 13.1 +/- 8.9 min, 9.9 +/- 6.5 min for DES, ISO, and PRO, respectively). Intermediate recovery, as measured by psychometric testing, sedation levels, and time to discharge from the postanesthesia care unit, was similar in the three groups. In this study, DES provided a transient advantage compared with ISO or PRO with respect to early recovery after prolonged general anesthesia in elderly patients. IMPLICATIONS: Recovery from prolonged anesthesia can sometimes be problematic in elderly patients. We evaluated 45 elderly patients who received either desflurane, isoflurane, or propofol for anesthesia. We found that desflurane provided a transient advantage in terms of postoperative recovery, but whether this difference is clinically important remains to be demonstrated.

Aged↗
PubMed1997

[Chondrosarcoma of the temporomandibular joint. Apropos of a case and review of the literature].

Chondrosarcomas of the temporo-mandibular joint are exceptional and have been previously reported in the literature in only seven cases. A case located in the temporal bone with extension in the infratemporal fossa and the cranial base is presented. Treatment consisted in a wide surgical resection combined with postoperative radiotherapy. The patient is alive with a follow-up of more than two years.

Adult↗
PubMed1997

[Value of fasciocutaneous tensor fasciae latae island flap in the treatment of large abdominal hernias. Apropos of a case].

One case of repeated incisional hernia is reported. This hernia was initially repaired but repeated infection occurred. This hernia was then successfully treated with a fasciocutaneous tensor fasciae latae island flap. The patient was reexamined two years after surgery and presented a functional abdominal wall. Other different reconstructive possibilities of regional myocutaneous flaps are described.

Abdominal Muscles↗
PubMed1989

Activation of mu opioid receptors in the nucleus raphe dorsalis blocks apomorphine-induced aggression in rats: serotonin appears not to be involved.

The role of mu opioid receptors in the nucleus raphe dorsalis (DR) in the control of apomorphine-induced aggression was studied in rats. Administration in the DR of a selective mu opioid receptor agonist, (D-Ala2,N-Me-Phe4,Gly5-ol)-enkephalin (DAGO), in doses ranging from 0.01 to 1 microgram/0.5 microliter, dose-dependently reduced aggression caused by apomorphine 20 mg/kg intraperitoneally. 0.01 microgram DAGO significantly reduced the time spent by the animals in aggressive posture and 0.1 and 1 microgram markedly reduced both aggressive postures and attacks. 5 micrograms (in 0.5 microliter) naloxone in the DR completely antagonized the anti-aggressive effect of DAGO (0.1 microgram/0.5 microliter) injected in the same area. 0.1 and 1 microgram but not 0.01 microgram DAGO significantly increased serotonin (5-HT) metabolism in the striatum, a terminal area almost exclusively innervated by DR, indicating that the activity of 5-HT cells in the DR was modified by DAGO. In animals given 6 micrograms/3 microliters 5,7-dihydroxytryptamine in the DR 11 days before, in which striatal 5-HT levels were markedly depleted, no significant changes were found in the time spent by the apomorphine-treated animals in aggressive postures, numbers of attacks or anti-aggressive effect of 0.1 and 1 microgram DAGO administered in the DR. The study shows for the first time that activation of mu opioid receptors in the DR has a powerful anti-aggressive effect in one model of experimental aggression by a mechanism apparently not involving changes in the activity of 5-HT cells in this area.

Aggression↗
PubMed1987

Exploratory behavior and the dual activity of some psychoactive drugs. Part 1.

Animal behavior in a free environment involves the orienting reflex, a major component of which is exploratory behavior. Exploration is an essential, life-preserving component of animal higher nervous functions and the experiments presented here show that exploratory behavior may differ according to the experimental subjects' emotional baseline. Exploratory performance may accordingly be affected differently by psychoactive drugs.

Alprazolam↗
PubMed1987

Difference in learning and retention by Albino-Swiss mice. Part IV. Effect of some nutrients.

According to the preceding papers, the possible difference in activity of some nutrients on memory retrieval of "good" and "poor" learning mice was studied. Among the substances used, only phenylalanine significantly improved memory recall of poor learning mice. On the contrary, tryptophan, tyrosine, phosphatidylserine and choline did not influence memory retention of previously learned avoidance of both poor and good learning mice.

Amino Acids↗
PubMed1986

Difference in learning and retention by Albino Swiss mice. Part III. Effect of some brain stimulants.

According to the two preceding papers, the possible difference in activity of brain stimulants on memory retrieval of "good" and "poor" learning mice was studied. Among the drugs studied, caffeine, oxiracetam and nicotine significantly improved memory recall of poor learning mice. On the contrary, methylphenidate, fipexide and piracetam did not significantly modify memory retention of previously learned avoidance of both poor and good learning mice.

Animals↗