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Biomedical subjects

M Navez

Publications and source records attributed to M Navez.

12 recordsLinked to original sources
PubMed2005

Investigation of parameters influencing the activation of a Pd/gamma-alumina catalyst during methane combustion.

The progressive activation of a Pd(2 wt %)/gamma-alumina catalyst under the reaction conditions of catalytic combustion of methane (CCM) was studied. The reasons of this activation were investigated by XPS, CO-chemisorption, and HR-TEM. The removal of carbon from the surface cannot explain the observed activation process. Sintering of the palladium particles was detected but this parameter alone does not fully explain the activation process of the catalyst. HR-TEM imaging evidences (i) that PdO is present both in the fresh and the active catalyst and (ii) that the PdO nanoparticles sinter and restructure (surface roughening) during the reaction. Development of preferential faces was not observed. It is suggested that this restructuring may be responsible for the activation process by facilitating the formation of an active oxygen layer on the PdO surface. CCM on Pd/gamma-Al(2)O(3) depends on the thermal history of the catalyst and is a structure-sensitive reaction.

Journal Article↗
PubMed2005

[Primary and atypical facial pain: diagnosis and treatment].

PURPOSE: Facial pain is a frequently encountered symptom in general medical practice and encompass a wide group of facial problems. As correct diagnosis can usually be reached by history and physical examination for well defined typical clinical entities (trigeminal neuralgia, cluster headache) atypical facial pain may have many other potential causes (sinuses infection, temporomandibular joint syndrome, dental disorders...) so that diagnosis not appear an easy task. CURRENT KNOWLEDGE AND KEYPOINTS: Anatomical and physiological organization of facial nociceptive system, particularly trigeminal system, may explain the variability of facial pain. Although symptoms have been clearly identified mechanism of pain production remains controversial. Several factors (psychological, neurological, endocrine...) and mechanisms (neuropathic, vascular, myoarticular) may coexist and explain trouble in diagnosing and treating facial pain. FUTURE PROSPECTS AND PROJECTS: Better knowledge in identifying the cause of facial pain may lead to improve patient care and avoid patient frustration, medical nomadism, repetitive dental and otolaryngologic procedures, and finally non-compliance with treatment.

Facial Nerve Diseases↗
PubMed2001

[Quality of life of lumbago patients cared for in a pain center].

OBJECTIVE: To evaluate the quality of life of patients treated in a pain center. METHOD: Sixty eight patients were assessed during their first consultation, then 6, 12 and 18 months later, using a quality of life questionnaire "SQVP or Subjective Quality of Life Profile" validated in French populations and a panel of questionnaires for the monitoring of chronic pain, recommended by the ANAES (French Agency for Health Assessment). RESULTS: Results showed that: the patients' quality of life was clearly deteriorated (lowest quality in the data base--14,000 patients--with regard to the SQVP); the profile obtained (severe handicap) suggests that the lumbagos are part of a psychiatric context; the patients' quality of life clearly improves after 6 months' treatment, but the pain only stabilizes later.

Adult↗
PubMed2001

[Headaches caused by abuse of symptomatic anti-migraine and analgesic treatment].

These daily or near-daily headaches result from the chronic overuse of all immediate relief antimigraine drugs: ergotamine, analgesics, and/or more recently triptans. Like for much chronic daily headaches, the International Headache Society diagnostic criteria for drug abuse headaches are difficult to apply. Generally, patients confuse primary headaches (usually migraines) with interparoxysmal tension-type headaches called "rebound headaches". Psychosocial factors may play a role. Insidiously, a compulsive automedication results, often in anticipation of headache. This headache syndrome resists symptomatic and prophylactic treatment. These headaches are frequent, very disabling and socioeconomically costly. They are still largely underdiagnosed. Drug-induced headaches may be restricted to those patients who are already headache sufferers. The pathogenesis is not clearly understood: it may involve a deficience of inhibitory pain modulation, a hyperactivation of nociceptive facilitatory systems, and the peripheral and central effects of the incriminating drugs. The withdrawal of all offending analgesic drugs and a multimodality approach are indispensable, but the therapeutic protocoles are actually very heterogeneous and poorly estimated. Non-drug means could be very helpful. Effective education of headache sufferers and regular follow-up are essential to avoid relapses. Prognosis factors have been evoked, but may not be significant for the long term outcome. The rate successfull of is actually estimated at 60 p. cent at five years. The benefits of an adequate management encourage early recognation of drug-induced headaches. This article has in view to take stock of the literature at the end of 1999, and to help physicians become mora aware of this problem and develp a more preventive attitude.

Analgesics↗
PubMed2000

[Pain not associated with hypernociception. A physiopathologic, clinical and therapeutic approach].

It would be simplistic to consider the reality of pain as nothing more than heightened sensitivity to the pain. There are actually five types of pain, and it is often difficult to distinguish between them. Whereas hypernociceptive pain is mainly treated with analgesics belonging to one of the three categories as defined by the WHO, the mechanisms and treatment of the other four types of pain are very different It is obvious that close co-operation between the various healthcare professionals is indispensable in the treatment of these patients, while keeping in mind that the physician is "a symbol, an intermediary, a medicine that's better than medicine: the medicine works because it's a symbol - it's a symbol because it works". (P. Queneau and G. Ostermann.)

Humans↗
PubMed1999

Midazolam effects on implicit and explicit memory processes in healthy subjects.

RATIONALE: Studying midazolam-induced amnesia offers an interesting approach to the organization of normal memory processes, since memory performance can be studied in the same subject in "on" and "off" drug conditions. OBJECTIVE: The present study investigated the effect of midazolam on skill learning. The task and the experimental design we used also allowed us to assess the effect of midazolam on priming and explicit memory. METHODS: Eighteen patients who underwent minor ear surgery and who were anaesthetized with intravenous midazolam, and 18 matched control subjects participated in a mirror reading task on 2 separate days. Patients were tested under midazolam on day 1 and without any medication on day 2. The mirror reading task was made of French words, some of which repeated across trial blocks, others being new. RESULTS: Patients under midazolam read new mirror written words faster with practice, which attested for intact skill learning. Moreover, they read repeated words faster than new words with practice, which was interpreted as reflecting intact priming abilities. These spared implicit memory capacities were observed along with severe explicit memory impairments. Learning for both new and repeated mirror written words on day 2 was similar in patients and in controls, which was interpreted as suggesting that the implicit learning that occurred on day 1 under midazolam was normal. CONCLUSIONS: The quality of skill learning, both in terms of speed of and lasting effect, was normal under midazolam in the task we used. In the context of the present task, midazolam offers an interesting, reversible model of amnesia.

Adult↗
PubMed1996

Regional anaesthesia for outpatient nasal surgery.

Regional anaesthesia is not used widely for outpatient nasal surgery. The aim of this study was to determine the role of nasociliary and infraorbital nerve block in 24 patients undergoing nasal surgery comprising: cosmetic or reconstructive surgery of the nose and surrounding soft tissue, polypal removal, turbinectomy, reduction of fractured nasal bones, small tumour resection or emergency surgery on isolated facial lacerations. Mild sedation with midazolam 0.03 mg kg-1 was used before anaesthesia. Nasociliary and infraorbital blocks were technically easy to perform, safe and provided good intraoperative conditions. Only minor complications were observed, including local bruising in eight patients and transient diplopia in one patient. No patient received general anaesthesia, but infiltration of local anaesthetic was necessary in four patients because of incomplete anaesthesia in the surgical area. Operative conditions were judged as good or excellent by surgeons in 20 of 24 patients. Twenty of 24 patients were very satisfied or satisfied with anaesthesia. Duration of surgery exceeding 60 min and excessive bleeding in the nasopharynx were the main limiting factors for the use of facial regional anaesthesia.

Adult↗
PubMed1996

Effect of pre- vs postoperative tonsillar infiltration with local anesthetics on postoperative pain after tonsillectomy.

BACKGROUND: Since pre-incisional peritonsillar infiltrations of local anesthetic solutions have been suggested to reduce postoperative pain after tonsillectomy, we compared the efficacy of either pre- or postoperative local anesthetic infiltration upon post-tonsillectomy pain. METHODS: After the induction of general anesthesia, 68 consecutive healthy patients, ranging in age from 8 to 65 years, were randomly allocated to either receive peritonsillar infiltration with 0.25% bupivacaine (group 1) or normal saline (group 2) before incision. A third group (group 3) had their peritonsillar region infiltrated with 0.25% bupivacaine after the completion of surgery but before the patients were awakened from anesthesia. All the patients were treated in the same way in the postoperative period: NSAIDs were given intravenously to adults and rectally to children. Acetaminophen was given intravenously or rectally (children aged < 15 yr) if additional analgesic support was requested by the patient. Additional acetaminophen consumption was recorded daily. Pain scores were assessed on every patient with the use of a visual analogue scale (VAS) at rest, 1, 5, 9, 13, 17, 21 and 36 h after surgery, and also on swallowing during the first postoperative day. RESULTS: Global VAS pain scores were lower in the groups treated with bupivacaine infiltration during the first 24 h after surgery (P < 0.05). Supplementary analgesic consumption was lower in group 3 than in group 2 during the 0-9 h interval immediately following surgery (P < 0.05). There were no statistically significant differences for any other parameters between the 3 groups. CONCLUSION: These results suggest that the timing of peritonsillar infiltration with bupivacaine is not of clinical importance and does not affect the quality of postoperative analgesia in patients undergoing tonsillectomy.

Adolescent↗
PubMed1992

[Endoscopic extraction of a foreign body from the distal bronchus in the middle lobe, inaccessible by usual techniques, in a 3-year old child].

The authors report on the extraction of a piece of peanut impacted into the antero-internal bronchus of the right middle lobe, inaccesible to rigid bronchoscopy. After 4 months, this foreign body was visualised by flexible endoscope and removed by this technique under general anesthesia. We initially used a brush to pull the foreign body out of the distal bronchus and then used a biopsy forceps to remove it. Three months later, the chest-X-ray is normal and the child is asymptomatic.

Arachis↗
PubMed1989

[Deafness surgery in adults. The growing role of improved local anesthesia].

As deafness surgery is subject to the two imperatives of safety and reduction of bleeding, local anaesthesia constitutes a very satisfactory solution. The concomitant administration of Midazolam and Buprenorphine relaxes the patient and ensures analgesia and anterograde amnesia, allowing the surgeon to operate under excellent conditions. Over the last 6 months, except in one subject under the age of 16 years and one psychologically very fragile patient, all surgical operations for deafness, regardless of their importance, have been performed under local anaesthesia improved by means of diazanalgesia. It is probable that in the future, numerous cophosurgeons will adopt a similar protocol.

Adolescent↗