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Biomedical subjects

C Masson

Publications and source records attributed to C Masson.

At least 55 records · Page 3Linked to original sources
PubMed2000

Gamma-glutamyltranspeptidase-dependent glutathione catabolism results in activation of NF-kB.

gamma-glutamyltranspeptidase (GGT) is a key enzyme implicated in the homeostasis of intracellular reduced glutathione (GSH) and hence in the regulation of the cellular redox state. Besides, the extracellular cleavage of GSH by GGT leads to reactive oxygen species (ROS) production, depending on the generation and enhanced reactivity of cysteinylglycine (CysGly). Using a model cell line, the V79 GGT, which highly expresses a human GGT transgene, we examined whether the GGT induced oxidant stress could modulate intracellular transcription factors. For the first time, we show that GGT-dependent ROS production induces the NF-kB-binding and transactivation activities. This induction mimicked the one observed by H(2)O(2) and was inhibited by catalase, suggesting the involvement of H(2)O(2) in the NF-kB activation.

Animals↗
PubMed2000

Methadone maintenance vs 180-day psychosocially enriched detoxification for treatment of opioid dependence: a randomized controlled trial.

CONTEXT: Despite evidence that methadone maintenance treatment (MMT) is effective for opioid dependence, it remains a controversial therapy because of its indefinite provision of a dependence-producing medication. OBJECTIVE: To compare outcomes of patients with opioid dependence treated with MMT vs an alternative treatment, psychosocially enriched 180-day methadone-assisted detoxification. DESIGN: Randomized controlled trial conducted from May 1995 to April 1999. SETTING: Research clinic in an established drug treatment service. PATIENTS: Of 858 volunteers screened, 179 adults with diagnosed opioid dependence were randomized into the study; 154 completed 12 weeks of follow-up. INTERVENTIONS: Patients were randomized to MMT (n = 91), which required 2 hours of psychosocial therapy per week during the first 6 months; or detoxification (n = 88), which required 3 hours of psychosocial therapy per week, 14 education sessions, and 1 hour of cocaine group therapy, if appropriate, for 6 months, and 6 months of (nonmethadone) aftercare services. MAIN OUTCOME MEASURES: Treatment retention, heroin and cocaine abstinence (by self-report and monthly urinalysis), human immunodeficiency virus (HIV) risk behaviors (Risk of AIDS Behavior scale score), and function in 5 problem areas: employment, family, psychiatric, legal, and alcohol use (Addiction Severity Index), compared by intervention group. RESULTS: Methadone maintenance therapy resulted in greater treatment retention (median, 438.5 vs 174.0 days) and lower heroin use rates than did detoxification. Cocaine use was more closely related to study dropout in detoxification than in MMT. Methadone maintenance therapy resulted in a lower rate of drug-related (mean [SD] at 12 months, 2.17 [3.88] vs 3.73 [6.86]) but not sex-related HIV risk behaviors and in a lower severity score for legal status (mean [SD] at 12 months, 0.05 [0.13] vs 0.13 [0.19]). There were no differences between groups in employment or family functioning or alcohol use. In both groups, monthly heroin use rates were 50% or greater, but days of use per month dropped markedly from baseline. CONCLUSIONS: Our results confirm the usefulness of MMT in reducing heroin use and HIV risk behaviors. Illicit opioid use continued in both groups, but frequency was reduced. Results do not provide support for diverting resources from MMT into long-term detoxification.

Adult↗
PubMed2000

Statistical analysis and parsimonious modelling of dendrograms of in vitro neurones.

The processes whereby developing neurones acquire morphological features that are common to entire populations (thereby allowing the definition of neuronal types) are still poorly understood. A mathematical model of neuronal arborizations may be useful to extract basic parameters or organization rules, hence helping to achieve a better understanding of the underlying growth processes. We present a parsimonious statistical model, intended to describe the topological organization of neuritic arborizations with a minimal number of parameters. It is based on a probability of splitting which depends only on the centrifugal order of segments. We compare the predictions made by the model of several topological properties of neurones with the corresponding actual values measured on a sample of honeybee (olfactory) antennal lobe neurones grown in primary culture, described in a previous study. The comparison is performed for three populations of segments corresponding to three neuronal morphological types previously identified and described in this sample. We show that simple assumptions together with the knowledge of a very small number of parameters allow the topological reconstruction of representative (bi-dimensional) biological neurones. We discuss the biological significance (in terms of possible factors involved in the determinism of neuronal types) of both common properties and cell-type specific features, observed on the neurones and predicted by the model.

Animals↗
PubMed1999

[Combined sclerosis of the spinal cord "revisited"].

RENEWED INTEREST: There are at least three reasons for revisiting subacute combined degeneration. DIAGNOSIS: There is evidence that diagnosis is too often differed until a time when irreversible lesions of the spinal cord are present. A high degree of suspicion is mandatory. CONTRIBUTION OF MRI: Magnetic resonance imaging of the spine supplies interesting information about the distribution of lesions and their course under treatment. NO: Nitous oxide is an emerging cause of cobalamin deficiency. Patients sometimes develop myeloneuropathy after repeated or single exposure to nitrous oxide. This is explained by inactivation of methylcobalamin as a result of irreversible oxidation.

Anesthetics, Inhalation↗
PubMed1999

[Cerebral venous thromboses].

UNLABELLED: VARIABLE EXPRESSION: The clinical expression of cerebral venous thrombosis varies widely. The only manifestation may be an intracranial hypertension if the thrombus is limited to the superior longitudinal sinus or a predominant lateral sinus. Thrombosis of cortical veins, alone or in association with a sinus thrombus causes venous infarction. PROGNOSIS: Deep venous thrombosis generally leads to coma with signs of intracranial hypertension. However, partial or complete recovery is possible, even with a severe initial presentation, underlining the importance of early diagnosis and treatment. DIAGNOSTIC METHODS: Magnetic resonance imaging (MRI) coupled with magnetic resonance angiography (MRA) can usually confirm the diagnosis without conventional angiography. ETIOLOGICAL DIAGNOSIS: Cerebral venous thrombosis often follows prethrombotic conditions. Infectious causes only account for 10% of the cases and no cause can be identified in about 1 out of 5 cases. TREATMENT: Anticoagulation is indicated even in case of venous infarction with spontaneous bleeding. Thrombolysis can be proposed, particularly for deep venous thrombosis.

Anticoagulants↗
PubMed1999

Cloning and expression of a queen pheromone-binding protein in the honeybee: an olfactory-specific, developmentally regulated protein.

Odorant-binding proteins (OBPs) are small abundant extracellular proteins thought to participate in perireceptor events of odor-pheromone detection by carrying, deactivating, and/or selecting odor stimuli. The honeybee queen pheromone is known to play a crucial role in colony organization, in addition to drone sex attraction. We identified, for the first time in a social insect, a binding protein called antennal-specific protein 1 (ASP1), which binds at least one of the major queen pheromone components. ASP1 was characterized by cDNA cloning, expression in Pichia pastoris, and pheromone binding. In situ hybridization showed that it is specifically expressed in the auxiliary cell layer of the antennal olfactory sensilla. The ASP1 sequence revealed it as a divergent member of the insect OBP family. The recombinant protein presented the exact characteristics of the native protein, as shown by mass spectrometry, and N-terminal sequencing and exclusion-diffusion chromatography showed that recombinant ASP1 is dimeric. ASP1 interacts with queen pheromone major components, opposite to another putative honeybee OBP, called ASP2. ASP1 biosynthetic accumulation, followed by nondenaturing electrophoresis during development, starts at day 1 before emergence, in concomitance with the functional maturation of olfactory neurons. The isobar ASP1b isoform appears simultaneously to ASP1a in workers, but only at approximately 2 weeks after emergence in drones. Comparison of in vivo and heterologous expressions suggests that the difference between ASP1 isoforms might be because of dimerization, which might play a physiological role in relation with mate attraction.

Amino Acid Sequence↗
PubMed1999

Dendritic pattern development of the honeybee antennal lobe neurons: a laser scanning confocal microscopic study.

The processing of odorant signals is performed, in the olfactory bulb of vertebrates or in the antennal lobe of insects, by different types of neurons which display specific morphological and functional features. The present work characterizes the morphogenesis of the main neuronal types which participate in olfactory discrimination in the adult honeybee (Apis mellifera). Neurons were stained intracellularly with Lucifer yellow at different stages of pupal development and in the adult, and imaged by laser scanning confocal microscopy. Attending to branching patterns, all pupal neurons could be attributed to morphological types previously established in the adult. Given the functional importance of intraglomerular dendritic arbors in the processing of olfactory information, the study focused on their development. The two main classes, dense and sparse intraglomerular arbors, display adultlike features as early as the second day of pupal development. However, morphometric measurements and confocal observations show that their general pattern undergoes continuous maturation processes until late pupal stages and after emergence of the adult. Among these, the results point out a pruning of dendritic branches in sparse arbors, but not in dense arbors.

Age Factors↗
PubMed1999

Radial force of coronary stents: a comparative analysis.

High radial force has become an essential feature of new coronary stents. These stents are expected to exhibit sufficient radial force and minimum radial recoil when deployed in atheromatous lesions of various morphologies. The aim of this study was to compare the radial force of 17 coronary stents in vitro (Anglodynamics, ACS Multilink, AVE Micro II and GFX, Bard XT, Biocompatibles PC, Cook GR II, Cordis Crossflex, Hexacath Freedom, Johnson & Johnson PS 153'PS 154, and Crown, Medtronic Wiktor and BeStent BEL-15, Saint-Come SC 1616, Scimed Nir 7 and 9). Two in vitro mechanical tests were performed to assess the stent radial force. The first test measured the deformation of coronary stents in a V-stand by using a deformation controlled by a dynamometer based on a longitudinal generatrix. The precision was of 1 micron. This comparative test highlighted the appreciable variation in behavior of the range of tested stents in terms of resistance to local compression. The line graphs obtained show a very small (and in some cases nonexistent) purely elastic behavior area in the stents, with this result reflecting a small (<0.4 Newtons) range of forces applied to all stents. Above this value, the stents did not return to their size before compression and the line graph remains approximately linear for a long period. It was therefore possible to distinguish between two families of stents on the basis of the presence or absence of this elastic area. In the second test, the stent was deployed in a 3.0-mm elastic tube and a pressure gradient created between the interior and exterior of the tube. The precision was of 50 microns. A typical line graph of the pressure-diameter relationship was recognizable for a given stent. No difference in behavior between the different coronary stents was noted up to 0.3 x 10(5) Pa; subsequently, after 0.3 x 10(5) Pa, sizable deformation differences were visible between the least resistant stent, the BeStent BEL-15, and the most resistant stent, the Crossflex.

Evaluation Studies as Topic↗