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Biomedical subjects

M Besson

Publications and source records attributed to M Besson.

At least 19 recordsLinked to original sources
PubMed2006

Genetic dissociation of two behaviors associated with nicotine addiction: beta-2 containing nicotinic receptors are involved in nicotine reinforcement but not in withdrawal syndrome.

RATIONALE: Nicotine addiction is characterized by two distinct behaviors, chronic compulsive self-administration and the induction of a withdrawal syndrome upon cessation of nicotine consumption. OBJECTIVE: To examine if these two processes rely on beta2-containing nicotinic receptors--beta2*nAChRs--we analyzed the behavior of mice lacking these receptors in the two situations. RESULTS: First, we showed that, in contrast to wild-type (WT) mice, beta2-knockout (beta2-/-) mice exhibit no intra-ventral tegmental area (VTA) nicotine self-administration, whereas their ability to self-administer morphine is intact. However, beta2-/- mice showed some sensitivity to locomotor effects of nicotine, implying an effect of the drug on other nicotinic subtypes. Then, we observed that beta2-/- mice exhibited a normal nicotine withdrawal syndrome, i.e., increased levels of rearing and jumping upon precipitated withdrawal. Thus, the beta2*nAChRs are not involved in the behaviors induced by cessation of nicotine consumption. CONCLUSION: Taken together, the present data demonstrated a genetic dissociation of two distinct behavioral patterns associated with nicotine addiction. They further suggested that independent molecular mechanisms underlie these two aspects, offering the possibility of controlling them separately.

Animals↗
PubMed2006

[Mesenteric hematoma: Unusual complication of a long term oral anticoagulation therapy].

Authors report a case of a 77 years old man who developed a small bowel mesenteric hematoma as consequence of an unusual complication from a long term oral anticoagulation treatment. Computed tomoangiography helpfully suggests diagnosis of a mesenteric hematoma and refuts an organic cause as vascular anomalies, by an equivalent method to conventional angiography, noninvasely. In our case report, patient's deterioration justified an emergency surgery corroborating medical imager findings. Authors review the rare cases previously reported.

Administration, Oral↗
PubMed2006

[Suspected non-accidental trauma in children: pseudofracture of the parietal bone].

We reported the case of a three month old child who was suspected of abuse syndrome because of a possible parietal bone fracture during radiographic investigation. At autopsy, the parietal bone abnormalities were not fractures, but proved to be unossified membranous strips. A review of the literature about normal variants of parietal suture on roentgenograms was made to avoid the diagnosis of non-accidental trauma in children, especially in live children where autopsy cannot be made.

Child Abuse↗
PubMed2006

Targeted in vivo expression of nicotinic acetylcholine receptors in mouse brain using lentiviral expression vectors.

Nicotinic acetylcholine receptors (nAChRs) in the brain exhibit diverse functional properties and ubiquitous distribution. Yet, except for providing a receptor for the exogenously applied nicotine of tobacco products, their role in the normal functioning of the brain has remained elusive. We have used a lentiviral expression vector to re-express the beta2 subunit specifically in the ventral tegmental area (VTA) of beta2-/- mice. The viral vector efficiently expresses beta2- subunit protein leading to new nAChR-binding sites. VTA neurons transduced by the lentiviral vector are responsive to intravenous nicotine when analyzed using in vivo electrophysiology. Nicotine-induced dopamine release from the nucleus accumbens (NuAcc) was also restored in re-expressing beta2-/- mice. Intra-VTA injection of nicotine was found to be reinforcing in both wild-type and beta2-subunit re-expressing beta2-/- mice, but not in beta2-/- mice. Furthermore, in the absence of applied nicotine, the spontaneous slow exploratory behavior of the mice was restored, whereas fast navigation did not change. This latter behavioral analysis suggests a role for beta2* nAChR, specifically expressed in the VTA, in mammalian cognitive function.

Animals↗
PubMed2005

[Social inequalities and health: experiences of a mobile health care unit in Geneva].

Health care professionals are in contact with patients of all social horizons. Healthcare professionals come into contact with patients from all social backgrounds. Low socio-economic status is a well-known determinant of morbidity and mortality. A mobile community health care unit ("Umsco") was created in Geneva in 1996 with the aim of providing health care to very low-income patients who aren't catered for by the traditional healthcare system in Switzerland. The Mobile Unit's patients are mainly female South American illegal immigrants, but also the city' homeless. This article explains how the Unit functions on a day-to-day basis. We describe socio-demographic characteristics of the patients and their main presenting complaints. We also discuss how health care professionals in general can adapt to the specific needs of socially deprived and vulnerable patients.

Community Health Services↗
PubMed2005

Nicotine reinforcement and cognition restored by targeted expression of nicotinic receptors.

Worldwide, 100 million people are expected to die this century from the consequences of nicotine addiction, but nicotine is also known to enhance cognitive performance. Identifying the molecular mechanisms involved in nicotine reinforcement and cognition is a priority and requires the development of new in vivo experimental paradigms. The ventral tegmental area (VTA) of the midbrain is thought to mediate the reinforcement properties of many drugs of abuse. Here we specifically re-expressed the beta2-subunit of the nicotinic acetylcholine receptor (nAChR) by stereotaxically injecting a lentiviral vector into the VTA of mice carrying beta2-subunit deletions. We demonstrate the efficient re-expression of electrophysiologically responsive, ligand-binding nicotinic acetylcholine receptors in dopamine-containing neurons of the VTA, together with the recovery of nicotine-elicited dopamine release and nicotine self-administration. We also quantified exploratory behaviours of the mice, and showed that beta2-subunit re-expression restored slow exploratory behaviour (a measure of cognitive function) to wild-type levels, but did not affect fast navigation behaviour. We thus demonstrate the sufficient role of the VTA in both nicotine reinforcement and endogenous cholinergic regulation of cognitive functions.

Animals↗
PubMed2004

[MR imaging in the evaluation of blunt pancreatic trauma].

Pancreatic injuries caused by blunt trauma are unusual but associated with a high morbidity and a high mortality because of a delay in diagnosis. Clinical and laboratory findings are non-specific. Accurate grading of blunt pancreatic injury with identification of pancreatic duct disruption helps to define practical treatment guidelines. Computed tomography does not allow direct visualization of the pancreatic duct and may result in low accuracy for the detection of ductal injury. Endoscopic retrograde pancreatography is the "gold standard" but invasive (3-5% complication rate, mainly pancreatitis) and may not be possible in up to 30% of patients, or requested after surgery. Endoscopic retrograde pancreatography may be used as a therapeutic modality (stenting of the main pancreatic duct). Magnetic resonance cholangiopancreatography is non invasive and preliminary results are promising. Magnetic resonance cholangiopancreatography detects pseudocysts, has multiplanar capability and complemented with conventional MR imaging allows evaluation of the pancreatic parenchyma.

Humans↗
PubMed2004

[Gastric necrosis from acute dilatation without underlying psychiatric disorder].

Acute gastric dilatation with necrosis is a rare and severe complication associated with anorexia nervosa, bulimia, and psychogenic polyphagia. The Authors report an unusual case without underlying psychiatric context. Gastric necrosis was suspected based on imaging findings (plain radiograph and computed tomography). The detection of these imaging signs in an appropriate clinical setting, even without underlying psychiatric context, is important to avoid any delay in diagnosis and reduce mortality.

Abdominal Pain↗
PubMed2004

Partial thrombosis of an idiopathic azygos vein aneurysm.

Aneurysms of the azygos vein are often asymptomatic, detected on a chest radiograph simulating paratracheal mass. When the aneurysm is totally thrombosed, it is impossible to distinguish it from another cause of mediastinal mass. A case is presented in which partial thrombosis of the aneurysm and communication with the superior vena cava led to a diagnosis on angiography and CT.

Adult↗
PubMed2003

[Characterization of adrenal incidentaloma discovered with tomography. General review].

The detection of an incidentaloma at abdominal Computed Tomography (CT), except CT features that permit a specific diagnosis (hemorrhage, myelolipoma or cyst), become a problem to differentiate adenomas from "non adenomas" (primary or secondary malignancy) incidentalomas. A density of ten Hounsfield units or less with a nonenhanced CT is a feature of benign incidentaloma (essentially lipid-rich adrenal adenomas). There are two limitations of this characterization: incidentalomas initially detected at enhanced CT and lipid-poor adrenal adenomas. The relative enhancement washout on enhanced CT, by using a threshold of 50% washout, permit then to characterized as adenomas or "non adenomas" incidentalomas on a 10-minute-delayed enhanced CT. Limitations of this characterization are only for benign pheochromocytomas and atypical adrenal cortical carcinomas.

Adrenal Gland Neoplasms↗
PubMed2003

The Snodgrass and Vanderwart set revisited: norms for object manipulability and for pictorial ambiguity of objects, chimeric objects, and nonobjects.

In this paper, we propose a standardized set of 480 black-and-white line drawings, half meaningful and half meaningless. Meaningful pictures represent a common object, and were selected from the Snodgrass and Vanderwart set (1980). Meaningless pictures include 120 chimeric objects (made up of two halves of real objects) and 120 nonobjects, that were constructed from the meaningful pictures while controlling for visual complexity. We report the results of two experiments designed to standardize the revisited Snodgrass and Vanderwart set along two important dimensions for picture processing: object manipulability (Experiment 1) and pictorial ambiguity (Experiment 2). The relevance of these dimensions is discussed. Experiment 1 permit us to sort objects into four manipulability categories (i.e., the ease and distinctiveness with which use of the object can be mimed) and to propose a manipulability index. This experiment provides additional evidence for a partial overlap in the dichotomy between man-made objects and living things, on the one hand, and manipulable and unmanipulable objects, on the other hand. In Experiment 2, a pictorial ambiguity index was computed for meaningful and meaningless pictures. The results of this experiment point the distinction between chimeric objects and nonobjects showing that chimeric objects are more complex to process than nonobjects and objects. This standardized set of pictures provides a database and an hopefully useful tool for research in cognitive neuroscience.

Adult↗
PubMed2003

[Enterolith ileus: a rare complication of small bowel diverticulosis].

An elderly patient with subacute small bowel obstruction due to an enterolith that evolved within a small bowel diverticulum is reported. Presence of small bowel diverticulum is not rare. But small bowel obstruction secondary to an enterolith formed within a small bowel diverticulum is a rare complication. Enterolith ileus closely resembles gallstone ileus in its clinical presentation. Diagnosis can be established only by documenting the absence of aerobilia and the presence of small bowel abnormality causing stasis, like small bowel diverticulosis.

Aged↗
PubMed2003

[Isolated dissection of the superior mesenteric artery].

Isolated spontaneous dissection of the superior mesenteric artery is uncommon. We report a case complicated by arterial rupture and discuss diagnostic imaging work-up. Diagnosis is usually made by conventional arteriography. But, dissection can also be diagnosed noninvasively by computed tomography angiography and ultrasound.

Aortic Dissection↗
PubMed2003

[Iatrogenic renal perforation during percutaneous angioplasty].

Percutaneous transluminal angioplasty is recommended as the first choice of therapy for renal artery stenosis. However, morbidity and mortality are significant. Among hemorrhagic complications, renal perforation is unusual. A case is reported, caused by the use of an angled hydrophilic guidewire, in which the diagnosis has been made by computed tomography angiography with typically perirenal hematoma and extravasation of contrast material corresponding to the perforation. This complication has been successfully treated with conservative measures.

Angioplasty, Balloon↗
PubMed2003

[Congenital absence of a cervical spine pedicle: misdiagnosis in a context of trauma].

Absence of a cervical spine pedicle is an exceptional congenital anomaly with a characteristic radiographic triad: i) absence of pedicle producing a pseudo-enlargement of the homolateral foramen, ii) dysplastic aspect with posterior displacement of the homolateral facets and lamina, and iii) defect or absence of the homolateral transverse process. It is particularly important to recognize this radiographic picture in order to avoid misdiagnosis, e.g. unilateral fracture-displacement of the facet joints in a context of acute trauma, as occurred in our case, or pathological enlargement of the foramen (neurofibroma) without trauma. We describe the radiographic presentation of this congenital anomaly, stressing the importance of a homolateral oblique view and the usefulness of computed tomography for correct diagnosis.

Adult↗
PubMed2003

[Radiologic appearance of epiploic appendages and their complications].

A wide spectrum of pathologic processes can involve epiploic appendages, and primary epiploic appendagitis is the most frequent. Pathologic processes are today more frequently identified with the increased use of radiological assessment (ultrasound and computed tomography) of patients presenting with acute abdominal pain. Recognition of specific imaging abnormalities of complications enables the radiologist to make the diagnosis, thus allowing appropriate treatment.

Colon↗