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C Lebrun

Publications and source records attributed to C Lebrun.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Vertebral osteosarcoma. Review of the literature apropos of a case].

Osteosarcoma of the vertebral column (OSV) is a rare tumor which represents 0.85% to 2% of all osteosarcomas. In 95% of the cases they manifest themselves through pains and 80% of other cases through neurological disorders. Usually located on lumbar vertebrae it can also be found on the rest of the vertebral column. Its radiologic aspect is one of lysis in 48% of cases but a condensation can also be met in 27% of cases. The differential diagnosis with an osteoblastoma is difficult and must be left in the hands of the pathologist who bases it on precise criteria (cellular pleomorphism, stroma, presence of giant cells...). The secondary osteosarcoma of the vertebral column represents 30% of all cases of OSV. The heterogeneity of the studies has made it difficult to quantify them. The prognosis of OSV is poor: survival average is of 15.3 months and relative risk of recurrence compared to a femoral lesion is of 3.9 months.

Adolescent↗
PubMed1994

[Anesthesia in the patient with a pacemaker or implanted automatic defibrillator].

Many patients carry pace-makers, and even automatic defibrillators. As anyone, these patients may develop surgical diseases and require surgery and anesthesia. The particularities of the anesthetic management of such patients are developed, as well as the needed surgical adaptations (particularly concerning electrocoagulation). Most of these patients can be operated on an anesthetized, taking certain precautions. In some difficult cases, it is necessary to collaborate with a cardiologist.

Anesthesia, General↗
PubMed1993

Antibodies to the extracellular receptor domain restore the hormone-insensitive kinase and conformation of the mutant insulin receptor valine 382.

A mutation substituting a valine for phenylalanine at residue 382 in the insulin receptor alpha-subunit has been found in two sisters with a genetic form of extreme insulin resistance. This receptor mutation impairs the ability of the hormone to activate autophosphorylation of solubilized receptors and phosphorylation of substrates (Accili, D., Mosthaf, L., Ullrich, A., and Taylor, S. I. (1991) J. Biol. Chem. 266, 434-439). We have previously demonstrated that in native receptors insulin induces a conformational change in the receptor beta-subunit, which is thought to be necessary for receptor activation (Baron, V., Gautier, N., Komoriya, A., Hainaut, P., Scimeca, J. C., Mervic, M., Lavielle, S., Dolais-Kitabgi, J., and Van Obberghen, E. (1990) Biochemistry 29, 4634-4641). Hence, it was thought that a defect in this conformational change might explain the functional defect of the mutant receptor. This appears to be the case, as we demonstrate here that the mutant receptor is locked in its inactive configuration. However, we found two monoclonal antibodies, directed to the extracellular domain, which are capable of restoring the mutant receptor kinase activity. The activation of the mutant receptor was accompanied by restoration of conformational changes in the beta-subunit C terminus. From these data, we draw the two following conclusions. (i) A causal link exists between receptor kinase activation and the occurrence of conformational changes. (ii) Ligands other than insulin, such as antibodies, which perturb the extracellular domain, can function as alternative ways to restore the mutant receptor kinase.

3T3 Cells↗
PubMed1993

Chemotherapy and immunotherapy in adult malignant gliomas.

This review summarizes papers published during 1991 and 1992. The poor results obtained in the postneurosurgical treatment of gliomas led researchers to pursue attempts to try to overcome glioma cell resistance. The intra-arterial route was explored in several phase II studies with new drugs and even immunoconjugates; rates of response between 30% to 60% were obtained. New drugs (fotemustine, eflornithine, and estramustine) or combined protocols planned to circumvent chemoresistance were tested and showed some efficiency with moderate toxicity, enlarging the number of drugs available against malignant gliomas. On the contrary, two retrospective analyses warned about the risk of reduction of median time to survival due to adjuvant chemotherapy in anaplastic astrocytomas; this finding, if confirmed, would suggest to defer chemotherapy at the time of recurrence in this type of glial tumor. Immunobiologic therapies as immunomodifiers, immunoconjugates, or cytotoxic lymphocyte-activated killer cells and tumor-infiltrating lymphocytes were tested and allowed some responses to be obtained. In young children, chemotherapy regimens were found to be efficient in malignant plexus choroid carcinomas and low-grade gliomas, allowing radiation therapy to be deferred. Many studies were methodologically unsatisfactory because of uncertain pathology grouping, noncompliance to initial protocols, or too small populations of patients.

Adult↗
PubMed1993

[Blast injuries].

Explore the source record for details and available documents.

Barotrauma↗
PubMed1993

[Ischemic encephalopathy in primary antiphospholipid syndrome].

A 39-year-old man with livedo reticularis, optic neuropathy and acute ischemic encephalopathy (Sneddon's syndrome) had antiphospholipid antibodies. This primary antiphospholipid antibody syndrome was unsuccessfully treated by anticoagulation, corticosteroids and plasma exchanges. Despite a frank reduction of the circulating antibody titers after plasma exchanges, no improvement of the neurological symptoms was observed. Death was related to a systemic complication when the antibody titer was at its lowest level. This case provides further evidence that effective treatment for stroke associated with antiphospholipid antibodies is still wanting.

Adult↗
PubMed1992

Identification of the central tachykinin receptor subclass involved in substance P-induced cardiovascular and behavioral responses in conscious rats.

To identify the tachykinin receptor subclass involved in the central cardiovascular and behavioral actions of substance P (SP), we compared the central actions of SP with those of neurokinin A (NKA) and senktide in conscious chronically instrumented rats. Intracerebroventricular (i.c.v.) injection of SP (an NK1 agonist) and NKA (an NK2 agonist) increased mean arterial pressure (MAP) and heart rate (HR) dose dependently and these cardiovascular responses were associated with the behavioral responses, comprising excessive grooming and exploring. Both peptides were equipotent to produce the cardiovascular and the behavioral responses. Senktide (a highly selective NK-3 agonist), injected i.c.v. increased the HR markedly. The behavioral response, 'wet dog shakes', was observed most frequently after senktide and was dissociated from the HR response. Pretreatment with a peripheral NK-1-selective antagonist, L-668,169, attenuated the NKA-induced cardiovascular and behavioral responses but not the SP-induced responses. However, pretreatment with a peripheral NK-2-selective antagonists, L-659,877, attenuated the SP-induced responses but not the NKA-induced responses. These results suggest that the central cardiovascular and behavioral actions of SP and NKA are mediated by different subclasses of receptors and that the receptor subclasses which are specific for the central nervous system differ from those which mediate the peripheral actions of the two tachykinins.

Animals↗
PubMed1992

Role of brain angiotensin in cardiovascular regulation.

The brain is one of the organs where an intrinsic renin-angiotensin system (RAS) has been described. Stimulation of circumventricular or brainstem angiotensin II (Ang II) receptors engenders a distinct pattern of cardiovascular, endocrine, and behavioral responses featuring blood pressure increase, attenuation of the baroreceptor reflex, drinking, release of pituitary hormones such as vasopressin, oxytocin, and ACTH, and natriuresis. In contrast to most of the other central actions of Ang II, the natriuretic effect cannot be elicited by Ang II as a circulating hormone. Recently, we have shown that stimulation of Ang II AT-1 receptors in the circumventricular organs causes a selective release of norepinephrine (NE) in the paraventricular nucleus (PVN) and in the supraoptic nucleus (SON). As vasopressin is also released from the PVN and SON, it is possible that the Ang II-NE interaction is involved in the release of vasopressin, thereby contributing to central blood pressure regulation and volume control. Finally, a substantial body of results suggests that an overactivity of the brain renin-angiotensin system is one of the contributors to genetic hypertension. However, this idea needs further confirmation.

Angiotensin II↗
PubMed1991

[Effects of tianeptine on learning and memory in mice. Improvement of impairments induced by chronic alcoholism and brain aging].

Tianeptine, a molecule with antidepressant properties, was found to affect certain learning and memory impairments induced by chronic alcoholism and aging in the mouse. Impairment in spontaneous alternation induced by chronic (12 months) alcohol intake and accelerated loss of spatial learning skills related to aging disappeared totally after administration of tianeptine (10 mg.kg-1). In certain situations (discrimination acquisitions), tianeptine was uneffective in older animals at this dosage, but had a facilitating effect in young animals. The effects of tianeptine on serotonin mediated transmission and the probable implication of hypofunctioning central cholinergic systems in the observed impairments are discussed. Tianeptine might reduce the inhibiting action of serotonin terminaisons on acetylcholine release and might thus permit normal cholinergic transmission.

Aging↗
PubMed1990

[Osteosynthesis of thalamic fractures of the calcaneus using triangulation-fixed 1/4-tube plates. Preliminary results of 32 osteosyntheses].

The authors present a new type of osteosynthesis fixture used in calcaneal thalamus fracture repair. This consists in triangulation fixation, the upper- and retromost part of the thalamus being the apex of the triangle. This is performed using 2 or 3 1/4-tube A.O. instrumentation plates, with adaptable positioning according to the type of fracture. This system presents two advantages compared to currently used fixation components: it is less bulky and is associated with a reduced risk of skin-related complications. Calcaneal reconstruction is much more stable because the plates are in alignment with talocalcaneal stress lines, on the one hand, and because they form a truss that counteracts secondary displacement of the reconstructed thalamus. 32 calcaneal syntheses were thus performed during the period between July 1983 and July 1988. These included 8 stage III DUPARC fracture cases (25%), 21 stage IV cases (65.6%), and 3 stage V cases (9.4%). Nine 2-plate fixtures were assembled in an circumflex-like manner and 23 operations involved setting up the fixation components in a "closed triangle". Cuboid anchorage was necessary in 11 cases. Uncomplicated cutaneous necrosis occurred only once in this series (i.e., 3.2%). The stability of this operative procedure was assessed by measurements of Boehler's angle in the immediate postoperative period and after consolidation. The fixation was perfectly stable in 94% of cases (angle loss less than or equal to 5 degrees). Secondary angle loss occurred in 6% of cases (i.e., 2 cases, 8 degrees and 12 degrees respectively), one of which was caused by untimely weight-bearing. Moreover, no case of plate disruption was reported in this series.

Adult↗
PubMed1989

Septal alpha-noradrenergic antagonism in vivo blocks the testing-induced activation of septo-hippocampal cholinergic neurones and produces a concomitant deficit in working memory performance of mice.

In order to test the hypothesis that alpha-noradrenergic receptors in the septum 1) play an important functional role in the mediation of trans-synaptic control of the neurones of the cholinergic septo-hippocampal pathway and 2) produce resultant modulation of working memory performance, we have investigated the effects in vivo of the acute intraseptal injection of an alpha-antagonist, phenoxybenzamine, in mice. Neurochemical analysis was performed using measures of the kinetics of sodium-dependent high-affinity choline uptake in samples of hippocampus from injected mice and their relevant controls in both quiet conditions and immediately following selective working memory testing in an 8-arm radial maze. Results show that whereas the injection of phenoxybenzamine produces no significant alteration of the activity of the cholinergic septo-hippocampal neurones in quiet conditions, the pretrial (20 min) administration of this drug almost totally abolished the usually observed increase in hippocampal cholinergic activity induced by testing. This inhibition of cholinergic activation was associated with a parallel working memory deficit. The results provide further direct support for the hypothesis that septal noradrenergic afferents via alpha-receptors mediate a phasic and net excitatory trans-synaptic influence on the cholinergic septo-hippocampal pathway during working memory testing and thereby significantly contribute to the modulation of the level of working memory performance.

Action Potentials↗
PubMed1989

Metacarpo-phalangeal thumb sprains based on experience with more than 1,000 cases.

The metacarpo-phalangeal thumb sprains are very frequent. They mostly occur during sports (50%), and the ulnar collateral ligament is the structure most frequently ruptured (86%). Surgical repair of all severe lesions and/or bony fragment avulsions has led to 90% of good, and excellent results, when the operation is followed by a proper physical therapy. Criteria for evaluation are considered and so is the management of the old or neglected sprains.

Adolescent↗