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Biomedical subjects

A Coulon

Publications and source records attributed to A Coulon.

13 recordsLinked to original sources
PubMed2006

Dispersal is not female biased in a resource-defence mating ungulate, the European roe deer.

Dispersal is frequently more prevalent in one sex compared to the other. Greenwood proposed that patterns of sex-biased dispersal among birds and mammals are linked to their mating strategies. For species where males defend resources rather than females, he predicted female-biased dispersal, because males should remain at their birth site where they are familiar with the distribution of the resources that they must defend. Greenwood's hypothesis has been extensively supported among birds, where most species exhibit a resource-defence mating strategy. However, almost no equivalent information is available for mammals as males generally defend mates in this group. An exception is the European roe deer, a resource-defence mating ungulate. We thus tested Greenwood's hypothesis on this atypical mammalian model, looking for female-biased dispersal using sex-specific inter-individual genetic distances. We conclusively show that gene flow is not higher among females compared to males in the studied roe deer population, and hence that dispersal is not female-biased, suggesting that male mating strategy is not the primary selective force driving the evolution of dispersal in roe deer. We discuss the role of female mate choice and intra-sexual competition as possible alternative selective pressures involved.

Animal Migration↗
PubMed2006

Genetic structure is influenced by landscape features: empirical evidence from a roe deer population.

The delimitation of population units is of primary importance in population management and conservation biology. Moreover, when coupled with landscape data, the description of population genetic structure can provide valuable knowledge about the permeability of landscape features, which is often difficult to assess by direct methods (e.g. telemetry). In this study, we investigated the genetic structuring of a roe deer population which recently recolonized a fragmented landscape. We sampled 1148 individuals from a 40 x 55-km area containing several putative barriers to deer movements, and hence to gene flow, namely a highway, rivers and several canals. In order to assess the effect of these landscape features on genetic structure, we implemented a spatial statistical model known as geneland which analyses genetic structure, explicitly taking into account the spatial nature of the problem. Two genetic units were inferred, exhibiting a very low level of differentiation (F(ST) = 0.008). The location of their boundaries suggested that there are no absolute barriers in this study area, but that the combination of several landscape features with low permeability can lead to population differentiation. Our analysis hence suggests that the landscape has a significant influence on the structuring of the population under study. It also illustrates the use of geneland as a powerful method to infer population structure, even in situations of young populations exhibiting low genetic differentiation.

Animals↗
PubMed2004

Landscape connectivity influences gene flow in a roe deer population inhabiting a fragmented landscape: an individual-based approach.

Changes in agricultural practices and forest fragmentation can have a dramatic effect on landscape connectivity and the dispersal of animals, potentially reducing gene flow within populations. In this study, we assessed the influence of woodland connectivity on gene flow in a traditionally forest-dwelling species--the European roe deer--in a fragmented landscape. From a sample of 648 roe deer spatially referenced within a study area of 55 x 40 km, interindividual genetic distances were calculated from genotypes at 12 polymorphic microsatellite loci. We calculated two geographical distances between each pair of individuals: the Euclidean distance (straight line) and the 'least cost distance' (the trajectory that maximizes the use of wooded corridors). We tested the correlation between genetic pairwise distances and the two types of geographical pairwise distance using Mantel tests. The correlation was better using the least cost distance, which takes into account the distribution of wooded patches, especially for females (the correlation was stronger but not significant for males). These results suggest that in a fragmented woodland area roe deer dispersal is strongly linked to wooded structures and hence that gene flow within the roe deer population is influenced by the connectivity of the landscape.

Animals↗
PubMed2002

[Imaging of osteoarticular tuberculosis].

PURPOSE: and methods. To perform an illustrated and educational review of musculoskeletal tuberculosis. RESULTS: As the incidence of musculoskeletal tuberculosis still increases, a review appears justified. The following four main presentations are detailed and illustrated, by emphasizing the value of both CT and MR imaging: a) spine tuberculosis (~ 50%) commonly involves two adjacent vertebral bodies with usual large paravertebral abscesses. The following lesions are highly suggestive of tuberculosis: solitary vertebral involvement, solitary epidural abscess with or without erosive spondylitis; b) osteo-arthritis: peripherally located erosions at synovial insertions with gradual narrowing of the joint space are highly suggestive; c) osteomyelitis: unusual, may involve any bones; d) tenosynovitis and bursitis. CONCLUSION: Imaging studies are essential for diagnosis and to assess the extent of musculo-skeletal tuberculosis.

Bursitis↗
PubMed2001

Radiographic findings in 37 cases of primary CNS lymphoma in immunocompetent patients.

Because of the increasing incidence of primary central nervous system lymphoma (PCNSL), it is essential to recognize this disease in order to start appropriate treatment. We present the characteristic CT and MRI features of this tumour. The findings of 32 CT and 31 MR of 37 immunocompetent patients with biopsy-proved PCNSL are reviewed. The main features are presented and analysed, and are discussed in comparison with proven literature data. Primary central nervous system lymphoma presents as supratentorial solitary lesions in approximately 80% of the patients and multiple lesions in 20%. In contrast to classical data, the lesions are located in deep structures only in one-third of the cases, and involve posterior fossa in 10% of cases. Most of the lesions are hyperdense or isodense (92%) on CT, hypointense or isointense on T1-weighted images, and only about 40% are hyperintense on T2-weighted images. Nearly all the lesions enhance, except after corticosteroid administration. They produce mild oedema and mass effect. Meningeal or ventricular enhancement are rare but suggestive. Calcification, haemorrhage or necrosis are scarce. Although PCNSL in immunocompetent patients have a variable CT and MR appearance, the imaging data often suggest the diagnosis.

Brain Neoplasms↗
PubMed1999

Development of a new experimental model of penicillin-resistant Streptococcus pneumoniae pneumonia and amoxicillin treatment by reproducing human pharmacokinetics.

The increase of penicillin-resistant Streptococcus pneumoniae (PRSP) pneumonia results in a greater risk of antibiotic treatment failure. In vitro data are not sufficient predictors of clinical efficacy, and animal models may be insufficiently contributive, since they often use immunocompromised animals and do not always respect the human pharmacokinetics of antibiotics. We developed an experimental PRSP pneumonia model in immunocompetent rabbits, by using intrabronchial instillation of PRSP (MIC = 4 mg/liter), without any adjuvant. This reproducible model was used to assess amoxicillin efficacy by reproducing human serum pharmacokinetics following 1-g oral or intravenous administrations of amoxicillin every 8 h. Evaluation was performed by using clinical, CT scan, macroscopic, histopathologic, and microbiological criteria. Experimental pneumonia in untreated rabbits was similar to untreated severe human bacteremic untreated pneumonia; in both rabbits and humans, (i) cumulative survival was close to 50%, (ii) red or gray lung congestion and pleuritis were observed, and (iii) lung and spleen concentrations reached 5 and 4 log(10) CFU/g. A 48-h treatment resulted in a significant bacterial clearance in the lungs (1.53 versus 5.07 log(10) CFU/ml, P < 0.001) and spleen (1.00 versus 4.40 log(10) CFU/ml, P < 10(-6)) and a significant decrease in mortality (0% versus 50%, P = 0.02) in treated versus untreated rabbits. No difference was observed on macroscopic and histopathologic lesions between treated and untreated rabbits (P = 0.36 and 0.78, respectively). Similar results were obtained by using a fully penicillin-susceptible S. pneumoniae strain (MIC = 0.01 mg/liter). Our findings suggest that (i) this new model can be contributive in the evaluation of antibacterial agents and (ii) 1 g of amoxicillin three times a day may be sufficient to treat PRSP pneumonia in immunocompetent humans.

Amoxicillin↗
PubMed1998

[Spontaneous intraperitoneal rupture of the ureter].

An unusual case of spontaneous intraperitoneal rupture of the ureter was observed in adult with acute renal pain. Diagnosis was best established with CT rather than intravenous urography. CT demonstrated ureteral leakage with the contrast medium extravasating into the peritoneal cavity. The patient was initially managed successfully by endourology. Secondary stenosis of the ureter required surgery for partial resection of the distal ureter.

Adult↗
PubMed1985

Total and unbound cortisol-, progesterone-, oestrone- and transcortin-binding activities in sera from patients with myocardial infarction: evidence for differential responses of good and bad prognostic cases.

Day-of-admission sera from myocardial infarction patients (MI) and patients with cardiopathies other than MI (non-MI) were analysed for total and unbound cortisol (F), progesterone (P4), oestrone (E1), and corticosteroid binding activities (CBG). The MI who survived (n = 28) showed high increases of F, P4 and E1 compared to healthy controls. By contrast, the MI who died within 10 days of admission (n = 6) had unchanged F and less increased P4 and E1 than survivors. The non-MI (n = 6) had higher F and E1 than controls but normal P4. The unbound steroids were increased in all patients: however, the MI who died showed much smaller rises than survivors (P less than 0.001 for unbound F and E1 increases in survivors vs. deceased). The CBG activity was in all MI lower than in normals (P less than 0.001) but unchanged in non-MI. These results are discussed in terms of the potential significance of unbound plasma steroids as predictors of MI severity.

Adult↗
PubMedDate not supplied

[Abdominal imaging].

Explore the source record for details and available documents.

Diagnostic Imaging↗