Journals
2009 EN
Marc Thiry · Thierry Cheutin · Françoise Lamaye
+4 more
We investigated distribution of the nucleolar phosphoprotein Nopp140 within mammalian cells, using immunofluorescence confocal microscopy and immunoelectron microscopy. During interphase, three-dimensional image reconstructions of confocal sections revealed that nucleolar labelling appeared as several tiny spheres organized in necklaces. Moreover, after an immunogold labelling procedure, gold particles were detected not only over the dense fibrillar component but also over the fibrillar centres of nucleoli in untreated and actinomycin D-treated cells. Labelling was also consistently present in Cajal bodies. After pulse-chase experiments with BrUTP, colocalization was more prominent after a 10- to 15-min chase than after a 5-min chase. During mitosis, confocal analysis indicated that Nopp140 organization was lost. The protein dispersed between and around the chromosomes in prophase. From prometaphase to telophase, it was also detected in numerous cytoplasmic nucleolus-derived foci. During telophase, it reappeared in the reforming nucleoli of daughter nuclei. This strongly suggests that Nopp140 could be a component implicated in the early steps of pre-rRNA processing.
Springer Science+Business Media
Journals
2009 EN
Nicolas Michalski · Vincent Michel · Elisa Caberlotto
+11 more
We assessed the involvement of harmonin-b, a submembranous protein containing PDZ domains, in the mechanoelectrical transduction machinery of inner ear hair cells. Harmonin-b is located in the region of the upper insertion point of the tip link that joins adjacent stereocilia from different rows and that is believed to gate transducer channel(s) located in the region of the tip link's lower insertion point. In Ush1c (dfcr-2J/dfcr-2J) mutant mice defective for harmonin-b, step deflections of the hair bundle evoked transduction currents with altered speed and extent of adaptation. In utricular hair cells, hair bundle morphology and maximal transduction currents were similar to those observed in wild-type mice, but adaptation was faster and more complete. Cochlear outer hair cells displayed reduced maximal transduction currents, which may be the consequence of moderate structural anomalies of their hair bundles. Their adaptation was slower and displayed a variable extent. The latter was positively correlated with the magnitude of the maximal transduction current, but the cells that showed the largest currents could be either hyperadaptive or hypoadaptive. To interpret our observations, we used a theoretical description of mechanoelectrical transduction based on the gating spring theory and a motor model of adaptation. Simulations could account for the characteristics of transduction currents in wild-type and mutant hair cells, both vestibular and cochlear. They led us to conclude that harmonin-b operates as an intracellular link that limits adaptation and engages adaptation motors, a dual role consistent with the scaffolding property of the protein and its binding to both actin filaments and the tip link component cadherin-23.
Springer Science+Business Media
Journals
2009 EN
Dominique Sandmeier · Fred T. Bosman · Maryse Fiche
Training future pathologists is an important mission of many hospital anatomic pathology departments. Apprenticeship--a process in which learning and teaching tightly intertwine with daily work, is one of the main educational methods in use in postgraduate medical training. However, patient care, including pathological diagnosis, often comes first, diagnostic priorities prevailing over educational ones. Recognition of the unique educational opportunities is a prerequisite for enhancing the postgraduate learning experience. The aim of this paper is to draw attention of senior pathologists with a role as supervisor in postgraduate training on the potential educational value of a multihead microscope, a common setting in pathology departments. After reporting on an informal observation of senior and junior pathologists' meetings around the multihead microscope in our department, we review the literature on current theories of learning to provide support to the high potential educational value of these meetings for postgraduate training in pathology. We also draw from the literature on learner-centered teaching some recommendations to better support learning in this particular context. Finally, we propose clues for further studies and effective instruction during meetings around a multihead microscope.
Springer Science+Business Media
Journals
2009 EN
Kshamta B. Hunter · Thomas Lücke · Jürgen W. Spranger
+27 more
Schimke immunoosseous dysplasia (SIOD) is an autosomal recessive multisystem disorder characterized by prominent spondyloepiphyseal dysplasia, T cell deficiency, and focal segmental glomerulosclerosis. Biallelic mutations in swi/snf-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1 (SMARCAL1) are the only identified cause of SIOD, but approximately half of patients referred for molecular studies do not have detectable mutations in SMARCAL1. We hypothesized that skeletal features distinguish between those with or without SMARCAL1 mutations. Therefore, we analyzed the skeletal radiographs of 22 patients with and 11 without detectable SMARCAL1 mutations. We found that patients with SMARCAL1 mutations have a spondyloepiphyseal dysplasia (SED) essentially limited to the spine, pelvis, capital femoral epiphyses, and possibly the sella turcica, whereas the hands and other long bones are basically normal. Additionally, we found that several of the adolescent and young adult patients developed osteoporosis and coxarthrosis. Of the 11 patients without detectable SMARCAL1 mutations, seven had a SED indistinguishable from patients with SMARCAL1 mutations. We conclude therefore that SED is a feature of patients with SMARCAL1 mutations and that skeletal features do not distinguish who of those with SED have SMARCAL1 mutations.
Springer Science+Business Media
Journals
2009 EN
Dominique Gravel · Marilou Beaudet · Christian Messier
Large-scale synchronous variations in community dynamics are well documented for a vast array of organisms, but are considerably less understood for forest trees. Because of temporal variations in canopy gap dynamics, forest communities-even old-growth ones-are never at equilibrium at the stand scale. This paucity of equilibrium may also be true at the regional scale. Our objectives were to determine (1) if nonequilibrium dynamics caused by temporal variations in the formation of canopy gaps are regionally synchronized, and (2) if spatiotemporal variations in canopy gap formation affect the relative abundance of tree species in the understory. We examined these questions by analyzing variations in the suppression and release history of Acer saccharum Marsh. and Fagus grandifolia Ehrh. from 481 growth series of understory saplings taken from 34 mature stands. We observed that (1) the proportion of stems in release as a function of time exhibited a U-shaped pattern over the last 35 years, with the lowest levels occurring during 1975-1985, and that (2) the response to this in terms of species composition was that A. saccharum became more abundant at sites that had the highest proportion of stems in release during 1975-1985. We concluded that the understory dynamics, typically thought of as a stand-scale process, may be regionally synchronized.
Springer Science+Business Media
Journals
2009 EN
Dominique Chapelle · Jean-Frédéric Gerbeau · Jacques Sainte-Marie
+1 more
International audienceThis paper is motivated by the modeling of blood flows through the beating myocardium, namely cardiac perfusion. As in other works, perfusion is modeled here as a flow through a poroelastic medium. The main contribution of this study is the derivation of a general poroelastic model valid for a nearly incompressible medium which experiences finite deformations. A numerical procedure is proposed to iteratively solve the porous flow and the nonlinear poroviscoelastic problems. Three-dimensional numerical experiments are presented to illustrate the model. The first test cases consist of typical poroelastic configurations: swelling and complete drainage. Finally, a simulation of cardiac perfusion is presented in an idealized left ventricle embedded with active fibers. Results show the complex temporal and spatial interactions of the muscle and blood, reproducing several key phenomena observed in cardiac perfusion
Springer Science+Business Media
Journals
2009 EN
Bo Wang · Dominique Cluzel · Liangshu S. Shu
+5 more
International audienceContinuous magmatic activity occurred in the western Chinese Tianshan, Central Asia, from the Carboniferous to the Permian, i.e. before and after the Late Carboniferous amalgamation of Junggar and the Yili Blocks. Zircon U–Pb LA-ICPMS and Ar–Ar data reveal a coincidence in time between regional wrench faulting and granitoid emplacement. Permian post-collisional granitoids crop out within or at the margins of large-scale dextral strike-slip shear zones, some of them show synkinematic fabrics. The whole rock geochemical features of the Early-Middle Permian granitoids indicate an evolution from high-K calc-alkaline towards alkaline series. In other places of the North Tianshan, alkaline magmatism occurred together with deep marine sedimentation within elongated troughs controlled by wrench faults. Therefore, in contrast with previous interpretations that forwarded continental rift or mantle plume hypotheses, the coexistence of diverse magmatic sources during the same tectonic episode suggests that post-collisional lithosphere-scale transcurrent shearing tightly controlled the magmatic activity during the transition from convergent margin to intraplate anorogenic processes
Springer Science+Business Media
Journals
2009 EN
Jean Michel Laffosse · Franck Accadbled · Thierry Odent
+6 more
We implemented an experimental model of asymmetrical compression loading of the vertebral end plate (VEP) in vivo. The macroscopic permeability of the VEP was measured. We hypothesized that static asymmetrical loading on vertebrae altered the macroscopic permeability of the VEP. In scoliosis, solute transport to and from the disc is dramatically decreased especially at the apical intervertebral disc. The decrease in permeability could be induced by mechanical stress. Nine skeletally immature pigs were instrumented with left pedicle screws and compression rod at the T5/T6 and L1/L2 levels. After 3 months, three cylindrical specimens of the VEP were obtained from each of the tethered levels. A previously validated method for measuring permeability, based on the relaxation pressure due to a transient-flow rate was used. A pistoning device generated a fluid flow that fully saturated the cylindrical specimen. The decrease in upstream pressure was measured using a pressure transducer, which allowed the macroscopic permeability to be derived. A microscopic study completed the approach. Overall macroscopic permeability was lower for the tethered VEPs than for the VEPs of the control group, respectively -47% for flow-in (p = 0.0001) and -46% for flow-out (p = 0.0001). In the tethered group, macroscopic permeability of the specimens from the tethered side was lower than macroscopic permeability of those from the non-tethered side, -39% for flow-out (p = 0.024) and -47% for flow-in (p = 0.13). In the control group, the macroscopic permeability was greater in the center of the VEP than in its lateral parts for flow-out (p = 0.004). Macroscopic permeability of the center of the VEPs was greater for flow-out than for flow-in (p = 0.02). There was no significant difference between thoracic and lumbar. This study demonstrated that compression loading applied to a growing spine results in decreased permeability of the VEP. This result could be explained by local remodeling, such as calcification of the cartilage end plate or sclerosis of the underlying bone.
Springer Science+Business Media
Journals
2009 EN
Anne Donnet · Michel LantériMinet · Gilles Géraud
+5 more
Migraine is a common and frequently disabling condition. Nevertheless, many migraine sufferers do not consult for migraine, are not medically followed up and self-treat the attacks. "Tour de France of migraine" consisted of free-access conferences held in six large towns in France following a wide public information campaign. This sensitization campaign aimed at providing participants with educational information on migraine disease and on current therapies. Headache sufferers were then invited to respond to two consecutive questionnaires delivered at the end of the conferences and 3 months later to assess the influence of the information delivered on their migraine management. Tour de France of migraine recruited mainly severe migraine sufferers, most of whom had already consulted and were medically followed up. However, migraine management was often suboptimal in these subjects since most of them found their acute treatment of attacks ineffective and only few of them received a prophylactic treatment. Three months after the conferences, more than half of respondents had consulted for headaches. There was a significant improvement in migraine-related disability, as reflected by a significant decrease in mean Headache Impact Test 6-item score, which might have been related to the higher proportion of subjects receiving a prophylactic treatment of migraine. The Tour de France of migraine campaign revealed the difficulty in sensitizing migraine sufferers towards the necessity of being medically followed up. Mainly patients with severe migraine attended the conferences and derived clinical benefit from the educational program. Other strategies should be developed to reach a wider population of migraine sufferers.
Journals
2009 EN
Gilles Bourgoin · Mathieu Garel · Dominique Dubray
+2 more
We have assessed behavioural and environmental factors influencing the success of global positioning system (GPS) fixes recorded from 15 collared free-ranging female Mediterranean mouflon (Ovis gmelini musimon x Ovis sp.). We have demonstrated that fix success was 8% lower in resting animals (0.81, 95% CI = 0.79–0.84) than in active animals (0.89, 95% CI = 0.86–0.91) at an average temperature (13.8°C), but was similar and relatively constant at lower temperatures. When temperatures increased above the average temperature, fix success strongly decreased in resting animals (0.44, 95% CI = 0.36–0.52 at 30°C) as compared to active animals (0.76, 95% CI = 0.65–0.85). These results probably involved behavioural changes in habitat use of mouflon, as temperature and activity strongly influence the use of cover in ungulates. We also found that the success of GPS fixes was influenced by habitat types, increasing from 0.76 to 0.93 (under average sky openness of 33%) along a continuum going from forested to open areas. After controlling for differences in vegetation, sky openness had a positive effect on fix success (from 0.76 to 0.97 in evergreen oak forest). Our approach based on free-ranging animals and using a robust interpolation procedure should provide biologists with a more reliable method to account for bias in GPS studies.
Springer Science+Business Media