Change in naming abilities between the ages of 50 and 90: The importance of analyzing naming latency

in Stem-, spraak- en taalpathologie (2012, September), 17(2), 126-128

This study tests the controversial hypothesis that word naming difficulties may arise in individuals as young as their 50s. Participants of 25-35, 50-59, 60-69 and above 70 years of age were given a ... [more ▼]

This study tests the controversial hypothesis that word naming difficulties may arise in individuals as young as their 50s. Participants of 25-35, 50-59, 60-69 and above 70 years of age were given a picture naming task. To uncover subtle naming difficulties, correct naming latencies were analyzed, in addition to accuracy. Moreover, in order to control whether the expected slower naming latencies could be due to a general slowing affecting all cognitive tasks, participants were also given an odd/even judgment task to assess cognitive processing speed. In participants in their 50s, we found subtle naming difficulties revealed by longer naming latencies, unaccompanied by any decrease in naming accuracy. The age-related naming disadvantage increased with age with the onset of naming errors. Thus, in adults in their 60s and their 70s, the results showed both a decrease in accuracy and an increase in correct naming latencies. Moreover, the increase in naming latencies remained significant even after controlling for odd/even judgment latencies, suggesting a degradation specific to the picture naming task. We assumed that these slower latencies may result from a language-specific impairment. [less ▲]

Dosimetry for 6-[18F]Fluoro-L-DOPA in humans based on in vivo microPET scans and ex vivo tissue distribution in mice

Poster (2012, September)

Radiation dosimetry of new radiopharmaceuticals generally starts with studies in small animals such as mice and rats. The traditional technique has long been ex vivo measurement of the biodistribution ... [more ▼]

Radiation dosimetry of new radiopharmaceuticals generally starts with studies in small animals such as mice and rats. The traditional technique has long been ex vivo measurement of the biodistribution over time using harvested organs at different times post administration of the radiopharmaceutical. Since this approach requires a significant amount of animals, dynamic microPET studies, where the biodistribution of the tracer over time can be determined in vivo in a single scan, are an invaluable alternative. Due to known imaging artifacts and limitations, such as partial volume effect, a hybrid technique combining harvesting organs (post-scan) and dynamic imaging was introduced to achieve a cross-calibration to account for these limitations. Since 6-[18F]Fluoro-L-DOPA is a widely used PET tracer to study the dopaminergic system in neurology and oncology and there is no sound published dosimetry data, absorbed doses for major organs in humans were estimated using the traditional ex vivo technique and by dynamic microPET imaging in mice, allowing direct comparison of the results from the two techniques. The tissue distribution over time of 6-[18F]Fluoro-L-DOPA was determined by radioassay of harvested organs at 2, 5, 10, 30, 60, 120 minutes post administration (n=5 at each time point) in isoflurane-anaesthetized mice. Dynamic PET images were acquired with a FOCUS 120 microPET for 120 minutes after injection of 6-[18F]Fluoro-L-DOPA followed by radioassay of harvested organs (n=4). A bladder voiding scenario was used to simulate excretion every 2 h. The organ time-activity-curves (TACs) from both methods were extrapolated from a simulated 35 g standard mouse to a 70 kg standard male human using a technique based on organ to bodyweight ratios. The absorbed doses in major human organs were calculated with the commercially available human dosimetry software OLINDA/EXM (Version 1.1) using the extrapolated TACs. The extrapolated organ TACs obtained using the two methods showed a high correlation (average r = 0.94 ± 0.05, p < 0.001). However, TACs from PET alone under- or overestimated the activity in individual organs in contrast to TACs obtained using the cross-calibration of the PET data with the activity in post-scan dissected organs. Those organs in the excretion pathways, comprising bladder wall, kidneys and liver, received the highest organ doses. The total body absorbed dose was 0.0118 mGy/MBq for both the imaging based and harvesting based methods. The effective dose was 0.0193 mSv/MBq for the hybrid imaging-harvesting technique and 0.0189 mSv/MBq for the pure harvesting technique. Scaling errors in the PET TACs are likely caused by quantification errors such as partial volume effects and image artifacts. The use of a hybrid imaging technique to cross-calibrate the TACs improved the accuracy of the imaging-based dosimetry estimates. Therefore the hybrid technique combining dynamic imaging and harvesting organs (post-scan) is a suitable alternative to the gold standard ex vivo radioassay method. It yields comparable results yet reduces significantly the amount of animals needed in the study and can accelerate data acquisition. [less ▲]

Semiquantitative bedside evaluation of the microcirculation via sidestream dark field imaging in dogs

in Proceedings of the 22nd ECVIM-CA Congress (2012, September)

Saturn temperature profiles at low, medium and high latitudes derived from UVIS EUV Solar occultations

Conference (2012, September)

Primary hyperparathyroidism confirmed by histology : sensitivity and predictors of 99mTc-Sestamibi/CT scan

in Abstract Book - 13th International Workshop on Multiple Endocrine Neoplasia (2012, September)

Mixtures of Bagged Markov Tree Ensembles

in Cano Utrera, Andrès; Gómez-Olmedo, Manuel; Nielsen, Thomas (Eds.) Proceedings of the 6th European Workshop on Probabilistic Graphical Models (2012, September)

Markov trees, a probabilistic graphical model for density estimation, can be expanded in the form of a weighted average of Markov Trees. Learning these mixtures or ensembles from observations can be ... [more ▼]

Markov trees, a probabilistic graphical model for density estimation, can be expanded in the form of a weighted average of Markov Trees. Learning these mixtures or ensembles from observations can be performed to reduce the bias or the variance of the estimated model. We propose a new combination of both, where the upper level seeks to reduce bias while the lower level seeks to reduce variance. This algorithm is evaluated empirically on datasets generated from a mixture of Markov trees and from other synthetic densities. [less ▲]

MicroPET Focus 120 scanner use at high-­‐count rate

Poster (2012, September)

Kinetic modeling of physiological processes using imaging techniques requires an accurate measurement of the time-activity curve of the tracer in plasma, known as the arterial input function (IF). The IF ... [more ▼]

Kinetic modeling of physiological processes using imaging techniques requires an accurate measurement of the time-activity curve of the tracer in plasma, known as the arterial input function (IF). The IF can be obtained by manual blood sampling, can be derived from PET images, or continuously measured by the use of small counting systems such as beta microprobes [1]. However, some beta microprobe systems can suffering from high background counts and low sensitivity compared to PET can obligate the use of activities higher than those typical for the imaging system. In the present study, the NEMA NU4-2008 image quality (IQ) phantom [2] was used to evaluate the image quality of the microPET Focus 120 at high activity values. Attenuation correction was obtained from transmission measurement using 57Co point source. Eight emission scans of 20 minutes were performed at decreasing activity starting from 109 MBq to 3.7 MBq (total activity in the field-of-view). To study the effect of normalization in high count rate studies, several normalization scans were performed using activities ranging between 18 and 212 MBq. Images were reconstructed with all corrections using Fourier rebinning and filtered backprojection. The mean activity and the coefficients of variation of the uniform slices were measured. All high activity reconstructed images showed a detector-block-patterned artifact with an overestimation of the counts when normalization activity is higher than that used in the IQ phantom and underestimation of the counts when normalization activity is below the activity used in the IQ phantom. Using the same high activity for acquisition and normalization considerably reduces the patterned-artifact but does not eliminate it entirely. The observed artifact is due to pulse pile-up in the detectors at high count-rates. A dedicated rejection of the pulse pile-up does not appear to have been implemented for the microPET Focus 120. An alternative would be to re-calibrate the detectors with higher activity values to prevent any pile-up effect or to create an attenuation volume into which phantoms or small animals could be inserted thus decreasing the artifact. This latter option is under development. References: [1] G. Warnock et al, European Journal of Nuclear Medicine and Molecular Imaging Research, 1-13 (2011) [2] NEMA Standards Publication NU4-2008. Rosslyn, VA: National Electrical Manufacturers Association; (2008). [less ▲]

Deformation pattern at the western tip of the Corinth Rift

Conference (2012, September)

The Gulf of Corinth in Greece is an active continental rift propagating westward toward the Aegean subduction zone. GPS data shows that deformation rate reaches a maximum of 15 mm/yr at its western tip ... [more ▼]

The Gulf of Corinth in Greece is an active continental rift propagating westward toward the Aegean subduction zone. GPS data shows that deformation rate reaches a maximum of 15 mm/yr at its western tip. The style of extension and strain distribution is well documented offshore in the eastern and central parts of the rift (Bell, 2009). At its most active western extremity, published offshore data is not sufficient to characterize the deformation pattern. High resolution seismic profiles were thus acquired in that region within the framework of the SISCOR project to improve our understanding of fault evolution, seismicity and to be able to construct mechanical models of deformation. Here we investigate the spatio-temporal pattern of the basin subsidence and deposition with sparker data acquired in November 2011. Active faults and correlative time horizons were first mapped. The stratigraphy was then correlated with the eustatic sea-level curve. This sequence stratigraphic interpretation is possible because there are strong glacial-interglacial variations in the depositional environment. In fact lacustrine conditions prevail within the gulf during glacio-eustatic lowstands and are characterized by low amplitudes seismic facies. So synrift sediment isopachs over the last 12 000 and 130 000 yrs could be produced. The interpreted data allow us to: (1) compare deformation pattern at the western tip of the Gulf with the more mature central and eastern part of the Rift; (2) constrain the pattern and the timing of deformation as well as rates of faulting. Reference Bell, R. E., McNeill, L. C., Bull, J. M., Henstock, T. J., Collier, R. E. L., & Leeder, M. R., 2009. Fault architecture, basin structure and evolution of the Gulf of Corinth Rift, central Greece. Basin Research, 21(6), 824-855. doi:10.1111/j.1365-2117.2009.00401.x [less ▲]

Waste management evolution through years: evaluation of improvement using Life Cycle Assessment methodology

Conference (2012, September)

Waste is considered as a major concern of our century. New technologies and attempts to improve appeared through years. The goal of this study was to evaluate the improvement of waste management through ... [more ▼]

Waste is considered as a major concern of our century. New technologies and attempts to improve appeared through years. The goal of this study was to evaluate the improvement of waste management through the last forty years. Four steps of time and of technologies of waste treatment were evaluated in an environmental point of view using the life cycle assessment methodology. The first scenario is situated before 1970 with waste landfilling in an open dump without recuperation and valorization of gas. The second one considers the situation between 1990 and 2008 with a plant comprising grinding and sorting of waste to obtain refused derived fuel fraction (RDF) which was burnt in an incinerator, remaining waste being sent to sanitary landfill with recuperation and valorization of gas in electricity. The third one is the current one, in operation since 2009, with incineration of the whole of the residual municipal waste. The last scenario is about future considering the current installation and adding a biomethanation plant using the collected biodegradable fraction of household waste. This environmental evaluation was performed in accordance with the ISO standards 14040 and 14044 and the environmental impacts were calculated with the ReCiPe methodology. We modeled a specific plant situated in Liege using its technical and environmental reports to be as realistic as possible. Main result of this study is the improvement through years starting from the important environmental impact for the landfilling of waste in an open dump to an environmental gain for some categories with the current installation coupled with biomethanation. Global warming impact from the eighties was reduced by 9 in the years 1990-2008 and by 14 for the current scenario alone or coupled with a biomethanation plant. Some sensitivity analyses were used to evaluate the strength of assumptions with for example using a consequential LCA instead of an attributional one and modifying the electricity origin mix. An uncertainty analysis using Monte-Carlo method showed the robustness of our results. This study confirms the environmental improvement of technologies and emissions of waste management through years. [less ▲]

Les carrières professionnelles des cadres : regard croisé du genre et de l'âge

Conference (2012, September)

Ce papier a pour objectif de réaliser une revue de littérature qui doit permettre de construire une recherche empirique visant à apporter une vision comparative des carrières des hommes et des femmes ... [more ▼]

Ce papier a pour objectif de réaliser une revue de littérature qui doit permettre de construire une recherche empirique visant à apporter une vision comparative des carrières des hommes et des femmes cadres en regard de trois groupes d’âge : les moins de 35 ans, les [35-50] ans et les plus de 50 ans. Nous considérons les deux sexes étant donné que les trajectoires professionnelles sont influencées par le sexe de la personne ainsi que par les stéréotypes et les rôles qui y sont directement associés (genre). Les générations, quant à elles, nous permettront de tenir compte de l’évolution des facteurs de contexte que sont notamment ces rôles attribués au masculin et au féminin à travers les époques. En effet, les constructions sociales liées au sexe des individus sont susceptibles de changer d’une génération à l’autre et donc d’agir distinctement sur les intentions de carrière. Le fait d’introduire la dimension générationnelle, en plus de celle du genre, est l’occasion d’aborder le concept d’intersectionnalité qui consiste en un croisement des groupes cibles propres à la gestion de la diversité. A l’issue de cet aperçu théorique faisant état de la littérature existante relative à cette thématique des carrières des individus occupant un poste à responsabilités, nous pourrons mettre en évidence différentes questions de recherche qu’il nous faudra, dans un second temps, confronter à la réalité du terrain. [less ▲]

Quand l’art parle des restructurations : au-delà du dévoilement, une forme d’expérimentation

Conference (2012, September)

CCL2 as a serum biomarker of idiopathic pulmonary fibrosis in dogs

in Proceedings of 22nd ECVIM Meeting - Masstricht, Netherlands (2012, September)

Imaging technologies to understand grinding at particle scale in a UG-2 platinum ore processing plant

in XXVI INTERNATIONAL MINERAL PROCESSING CONGRESS (IMPC) 2012 PROCEEDINGS / NEW DELHI, INDIA / 24 - 28 SEPTEMBER 2012 (2012, September)

Immunopathogenesis of canine sinonasal aspergillosis

in Proceedings of the 22nd ECVIM-CA Congress (2012, September)

Removal of phosphorous through roasting of oolitic iorn ore with alkaline earth additives

in Proceedings of the XXVI International Mineral Processing Congress (2012, September)

The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to ... [more ▼]

The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to roasting with the addition of either Ca(OH)2 or CaO. The oolitic iron ore is roasted at 900°C for one hour. This reflects in reaction between alkaline earth additive and quartz, aluminosilicates, phosphorus, and some other minor components of the gangue minerals. The application of leaching, physical separation, and wash out of salts has resulted in the decrease of phosphorus from 0.7 to 0.15 % and it is established that the major influencing factor is the concentration of acid and to a less extent duration of the leaching process. About two third of the phosphorus can be removed by roasting with 3 % CaO to hematite, coarse grinding to d50 0.3 mm, dry high intensity magnetic separation and leaching of the magnetic fraction with hydro-chloric or nitric acid. [less ▲]

Erythropoiesis in acromegaly : effect of GH or IGF-1 ? Data from the LAS (Liege Acromegaly Survey)

in Journal für Klinische Endokrinologie und Stoffwechsel (2012, September), 5(3), 45

UNFOLDING SYNTHETIC PEPTIDES BY AFM AT THE SINGLE-MOLECULE LEVEL

Conference (2012, September)

The aim of this study is to investigate the mechanochemical behavior of homopolypeptides able to change their conformation is a stimuli-responsive way. The peptidic secondary structures were studied in ... [more ▼]

The aim of this study is to investigate the mechanochemical behavior of homopolypeptides able to change their conformation is a stimuli-responsive way. The peptidic secondary structures were studied in detail by atomic force microscopy (AFM) at the single-molecule level. Synthetic copolymers containing a polypeptide block were prepared by N-carboxyanhydride amino acid ring-opening polymerization. The polymer chains were grafted as a dilute brush onto gold surfaces and their mechanochemical behavior was then studied by AFM single-molecule force spectroscopy (SMFS). The investigated polypeptide blocks were based on poly(L-glutamic acid), which undergoes a transition from alpha-helix to random coil. This can be induced by external stimuli (pH, ionic strength, temperature) or simply by applying a force. We were able to study the mechanically driven unfolding of the peptide by stretching-release cycles of the biomacromolecule. Stretching the helical peptide resulted in original features in the force-distance traces. Plateaus that are specific for the helical conformation were detected, quantified and discussed. Pulling-relaxing SMFS experiments will eventually lead to a better understanding of the force-induced unfolding of an alpha-helix and the reversibility of the phenomenon. [less ▲]

Characterisation of a scroll expander for small scale absorption power and cooling cycle activated by solar energy or waste heat

Poster (2012, September)

Change in naming abilities between the ages of 50 and 90: The importance of analyzing naming latency

Poster (2012, September)

Introduction This study tests the controversial hypothesis that word naming difficulties may arise in individuals as young as their 50s. According to Feyereisen (1997), these difficulties begin at the age ... [more ▼]

Introduction This study tests the controversial hypothesis that word naming difficulties may arise in individuals as young as their 50s. According to Feyereisen (1997), these difficulties begin at the age of 70, but Nicholas, Connor, Obler, and Albert (1998); Connor, Spiro, Obler, and Albert (2004) observed subtle signs of decreased naming performance in participants in their 50s. However, these studies focused on naming accuracy. To our knowledge, no study has analyzed naming latencies in participants in their 50s in comparison with younger participants. We assume that such analyses may highlight more subtle difficulties in naming. In our study, both naming latencies and naming accuracy were analyzed in a picture naming task presented to 4 age groups: 25-35, 50-59, 60-69 and above 70 years old. If people in their 50s experience subtle naming difficulties, these should be reflected in longer picture naming latencies compared to younger participants. In participants above 70 years of age, the decline should be more apparent and may be underlined not only by slower naming latencies but also by lower picture naming scores. The explanation for naming difficulties in aging is also a matter of debate. According to some authors (e.g., Salthouse, 1996), these difficulties are a consequence of a general slowing in all cognitive tasks, including language, in the elderly. However, other theories suggest that the relevant difficulties are more language-specific and are due to connection weaknesses across the entire language system, leading to more naming errors and longer naming latencies (e.g., Burke, MacKay, Worthley, & Wade, 1991). In order to determine the extent to which the slowing of naming latencies in the elderly is related to a slowing of cognitive processing, participants’ cognitive processing speed was assessed with an odd/even judgment task. We were also interested in seeing whether slowing on the odd/even judgment task arises at the same age than slowing on the picture naming task. Methods Participants Four groups of 30 participants took part in the present study: (1) between 25 and 35 years of age, (2) between 50 and 59 years of age, (3) between 60 and 69 years of age and (4) above 70 years of age (70+). All subjects were native French speakers and reported no history of neurological, cardiac, neuropsychological or psychiatric disorders, and no uncorrected hearing or visual problems. Dementia was excluded with the Mattis Dementia Rating Scale (Schmidt, Freidl, Fasekas, Reinhart, & Grieshofer, 1994). No differences between groups were found for vocabulary level (Mill Hill test; Deltour, 1993) or socio-economic background. Materials Participants performed a picture naming task (150 black and white drawings selected from the set of Bonin, Peereman, Maladier, Méot, and Chalard, 2003). Both the number of correct responses and naming latencies were analyzed. We also analyzed response latencies on an odd/even judgment task on 50 digits from 1 to 9, to assess cognitive processing speed. Results For the picture naming task, an analysis of variance (ANOVA) performed on the number of correctly named items revealed an effect of age, F(3,116)=35.36, p<.001. Tukey post hoc comparisons (p<.05) indicated that the 70+ age group named fewer items correctly than the 60-69 age group, which performed worse than the 25-35 and 50-59 age groups, which in turn did not differ from each other. However, the ANOVA performed on correct naming latencies did not show the same pattern of results. This analysis revealed an effect of age, F(3,116)=35.36, p<.001. Tukey post hoc comparisons (p<.05) indicated that the 25-35 age group responded faster than the 50-59 and 60-69 age groups, which did not differ from each other. The 70+ age group responded more slowly than the 3 younger groups. For the odd/even judgment task, the ANOVA performed on response latencies indicated an effect of age, F(3,116)= 96.40, p<.001. Tukey post hoc comparisons (p<.05) showed that the 25-35 and 50-59 age groups did not differ from each other and responded faster than the 60-69 and 70+ age groups, which in turn did not differ from each other. An analysis of covariance was also performed on naming latencies, using the latencies on the odd/even judgment task as covariate. There was a significant effect of age, F(4,115)=54.56, p<.001. Tukey post hoc analysis indicated that the 25-35 age group responded faster than the 50-59 and 60-69 age groups, which did not differ from each other. The 70+ age group performed more slowly than the 3 younger groups. Thus, a slowing of picture naming latencies was found in participants above 50 years of age. This slowing remained significant even when cognitive processing speed was controlled for. Discussion The increase in correct naming latencies on the picture naming task in participants in their 50s suggests the presence of subtle age-related word finding difficulties. In participants in their 60s, naming difficulties were highlighted by both a decrease in correct responses and an increase in naming latencies. Finally, in participants above 70 years of age, these difficulties became more pronounced in both naming accuracy and naming latencies. Slowing on the picture naming task appears to be greater and to arise earlier in the adult lifespan (in participants in their 50s) than slowing on the odd-even judgment task assessing processing speed (in participants in their 60s). Moreover, this slowing of picture naming latencies in participants in their 50s remained significant even when processing speed was controlled for with an analysis of covariance. In conclusion, these results support the importance of naming latency analyses in uncovering subtle naming difficulties. Furthermore, although we do not exclude a possible impact of general slowing on naming latencies in participants above 50 years of age, these findings suggest that the slowing in naming at this age observed here may be explained by a specific age-related slowing within the language system. References Bonin, P., Peereman, R., Maladier, N., Méot, A., & Chalard, M. (2003). A new set of 299 pictures for psycholinguistic studies: French norms for name agreement, image agreement, conceptual familiarity, visual complexity, image variability, age of acquisition, and naming latencies. Behavior Research Methods, Instruments, & Computers, 35(1), 158-167. Burke, D. M., MacKay, D. G., Worthley, J. S., & Wade, E. (1991). On the tip of the tongue: what causes word finding failures in young and older adults? Journal of Memory and Language, 30(1), 542-579. Connor, L.T., Spiro, A., Obler, L. K., & Albert, M. L. (2004). Change in object naming ability during adulthood. The Journals of Gerontology: Series B, 59(5), 203-209. Deltour, J. J. (1993). Echelle de vocabulaire Mill Hill de J.C. Raven. Braine-le-Chateau, Belgium: Editions l’Application des Techniques Modernes. Feyereisen, P. (1997). A meta-analytic procedure shows an age-related decline in picture naming: Comments on Goulet, Ska et Kahn (1994). Journal of Speech, Language, and Hearing Research, 40(1), 1328-1333. Nicholas, M., Connor, L.T., Obler, L. K., & Albert, M. L. (1998). Aging, Language, and Language Disorders. In M. Taylor Sarno (Ed.), Acquired Aphasia (pp. 413-449). San Diego, CA: Academic Press. Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition. Psychological Review, 103(3), 403-428. Schmidt, R., Freidl, W., Fasekas, F., Reinhart, B., & Grieshofer, P. (1994). Mattis Dementia Rating Scale. [less ▲]

Phenotypical and genotypical surveillance of macrolide and lincosamide resistance in group B streptococcus in Belgium

in Program and Abstract of the 52nd Intersciences Conference on Antimicrobial Agents and Chemotherapy (2012, September)

Background: Constant increase of erythromycin (E) and clindamycin (C) resistance (R) has been observed worldwide among isolates of group B streptococci (GBS). In Belgium, through the 2000s, E R increased ... [more ▼]

Background: Constant increase of erythromycin (E) and clindamycin (C) resistance (R) has been observed worldwide among isolates of group B streptococci (GBS). In Belgium, through the 2000s, E R increased rapidly from 10% to up to 30%. Therefore phenotypical and molecular surveillance of E and C R has to be conducted. Methods: 275 clinical isolates (N1) were obtained from a Belgian surveillance for invasive GBS disease in newborns (59 isolates with 32 early- and 27 late-onset diseases) and adults (216 strains) during 2008 to 2011 and 53 isolates (N2) from vagino-rectal colonization in pregnant women in 2010. E and C MICs were determined by using Etest® (EUCAST interpretive criteria). Furthermore, for the E R isolates, the inducible (iMLS), constitutive (cMLS) and M phenotypes were assessed by a double disk diffusion test; the distribution of genes encoding RNA methylases and efflux pumps was investigated by PCR. Results: Of the N1 and N2 isolates, 92 (33.5%) and 15 (28.3%) were respectively R to E, with a higher rate among serotype V (p <0.001) and serotype IV (p <0.05). Among these 107 E-R isolates, 100 (93.5%) exhibited the MLS phenotype (R to E and CC): 73 were cMLS with E MIC50 >256 mg/L and 27 iMLS with E MIC50/MIC90 12/>256 mg/L. The M phenotype (R to E and S to C) was expressed by 7 (6.5%) of E R isolates with E MIC50/MIC90 4/12 mg/L. One colonizing strain presented a newly described resistance mechanism in GBS: the L phenotype (S to E and R to C) with a C MIC at 8 mg/L. For cMLS, the most common E R genotype was ermB (66%) (p <0.05) followed by ermTR (29%) and ermB+ermTR (5%). All iMLS isolates harbored an ermTR gene except 3 (2 with ermB, 1 with both ermB and ermTR); and all M phenotype were positive for mefA/B gene. Conclusions:1) In Belgium, by year 2010, prevalence of macrolides R in GBS exceeded 30%, 2) MLS R phenotypes (target-site modification) were the majority mechanism; M phenotype (efflux R mechanism) was also prevalent. 3) E and C susceptibility testing and surveillance are mandatory to guide prophylaxis and treatment of serious GBS infections in penicillin-allergic patients (at high risk for anaphylaxis) but also to identify emergence of newly acquired resistance mechanisms such as the L phenotype. [less ▲]

Molecular epidemiology of norovirus in symptomatic and asymptomatic population in Burkina Faso

Poster (2012, September)

Background Noroviruses (NoV), belonging to the family Caliciviridae, are now recognized as the leading cause of gastroenteritis outbreaks worldwide, and represent an important cause of sporadic ... [more ▼]

Background Noroviruses (NoV), belonging to the family Caliciviridae, are now recognized as the leading cause of gastroenteritis outbreaks worldwide, and represent an important cause of sporadic gastroenteritis in both children and adults. Many studies describe NoV epidemiology. However, few data are available about the NoV strains circulating in most of African countries, in particular in Burkina Faso. The population of Burkina Faso is characterized by the young age of its habitants, and most are living in rural environment. Objectives The purpose of this epidemiological study was to determine the prevalence of NoV in Bobo Dioulasso (Southern part of Burkina Faso) by molecular diagnosis methods in patients presenting or not gastroenteritis symptoms, to quantify the excreted viral load, and to genotype the circulating strains. Methods Patients with and without gastro-intestinal disorders were selected in several Health Care Centres of Bobo Dioulasso. Clinical and epidemiological data, as well as stool samples, were collected during 8 weeks through March to April 2011. Viral genomic RNA was automatically extracted with a Maxwell® (Promega) instrument. Molecular detection of genogroups (G) I, II and IV NoV in stool samples was performed by a home-made real-time RT-PCR targeting the ORF1-ORF2 polymerase junction region. For each positive sample, viral load was estimated by using standard curves (successive dilutions of recombinant GI and GII plasmids). Molecular characterization was performed on the detected strains, using both polymerase and capsid regions. Results NoV were detected in 21.6% of the 453 collected stool samples, with a distribution of 21.0% and 23.1% in the samples from the 319 symptomatic (SP) and the 134 asymptomatic patients (AP) respectively. Genogroup distribution was 7.2% for GI, 10.7% for GII and 3.1% for both GI and GII among SP’s samples, and was 11.2% for GI, 10.4% for GII and 1.5% for both GI and GII among AP’s samples. Average viral load values were higher for GI NoV in SP than in AP (p=0.02), when they were higher for GII NoV in AP than in SP (p=0.04). Phylogenic analysis showed a high degree of genotypical diversity in both groups of patients. One recombinant strain GII.7/GII.6 was also detected, to our knowledge, for the first time. Conclusion Even if a true pathogenic role of NoV could not be showed from the study design, it allowed to precise the molecular epidemiology of NoV strains prevalent in a representative country of the East African region. It also showed that asymptomatic patients could play an important role as a NoV “reservoir”. Despite the fact that GII strains, and more precisely those belonging to GII.4 genotype, are nowadays highly reported worldwide, the surprising proportion of NoV GI detected in this study suggests that GI and GII strains should be excreted in equal proportion in the environment. The origin of this epidemiologic difference, even if partially explained by the difference in immunity and genetic sensitivity of the population, is still to be solved. [less ▲]

MANAGING PUBLIC ORDER DURING

Conference (2012, September)

MORPHO-BIOMETRIC CHARACTERIZATION OF TWO LOCAL CHICKEN BREEDS IN VIETNAM

in The Role of Poultry in Improving Human Welfare (2012, September)

In Vietnam, 84% of the 188 million chickens are indigenous. The following local breeds are recorded: Ri, Mia, Te, Tau Vang, Ac, Oke, H’mong, Tre, Choi, Phu Lu Te, To, Dan Khao, Ho, Dong Tao and Van Phu ... [more ▼]

In Vietnam, 84% of the 188 million chickens are indigenous. The following local breeds are recorded: Ri, Mia, Te, Tau Vang, Ac, Oke, H’mong, Tre, Choi, Phu Lu Te, To, Dan Khao, Ho, Dong Tao and Van Phu. Mia, Ho and Dong Tao are reported as endangered or critical, while the Van Phu breed could have been lost during the last years. The phenotypes of the Mia and Ri breeds are described as quite close. The objective of this study is to characterize phenotypically Ri and Mia chickens. The morpho-biometric characterization was conducted according to the recommendation of FAO (1981). A total of 227 adults Ri (174 females and 53 males) and 53 adults Mia (18 males and 35 females) were used for the study. The following colors were observed for Ri and Mia respectively: tan (43.17% and 37.73%), gold salmon (24.23% and 26.42%), wheat (15.42% and 26.42%), dark red (9.69% and 5.66%), silver salmon (3.52% and 3.77%) and copper black (3.96% and 0%). Comb was mostly simple (91.19% and 100%) and red (100% and 100%) for both breeds. The wattles were of the same color as the comb while the color of the legs was yellow. The weights of adult males (2433.89g) and females (1752.86g) of the Mia breed were significantly higher than those of Ri (2053.02g and 1459.22g for males and females respectively). The results show that the external aspect of both breeds is not very different while body weights in the Ri breed were found lower than in the Mia breed. [less ▲]

Urinary, hematologic and biological screening of 108 healthy adult Dogues de Bordeaux : a breed predisposed to a glomerulonephropathy

in Proceedings of the 22nd ECVIM-CA Congress (2012, September)

Les fondements économiques de la motivation des sanctions

in Chainais, Cécile; Fenouillet, Dominique (Eds.) La motivation des sanctions prononcées en justice: nouvelles tendances, nouveaux enjeux (2012, September)

Il existe une approche économique des sanctions. Les économistes proposent ainsi des théories ou des modèles de sanctions qui permettent de calculer la sanction optimale en fonction d'un certain nombre de ... [more ▼]

Il existe une approche économique des sanctions. Les économistes proposent ainsi des théories ou des modèles de sanctions qui permettent de calculer la sanction optimale en fonction d'un certain nombre de paramètres considérés comme pertinents. Cette contribution explore les possibilité pour les juridiction d'emprunter à ces approches économiques lorsqu'elles doivent imposer des sanctions et en motiver le quantum. [less ▲]

A confocal microscopic study of mitochondrial alterations of renal HK-2 cells exposed to an endotoxic stress

Poster (2012, September)

Sepsis has a profound deleterious effect on kidney functions through complex mechanisms, which involve the immune response, inflammatory pathways, intracellular dysfunction and hemodynamic instability ... [more ▼]

Sepsis has a profound deleterious effect on kidney functions through complex mechanisms, which involve the immune response, inflammatory pathways, intracellular dysfunction and hemodynamic instability. Those factors are difficult to discriminate in vivo. To get a better understanding of renal respiratory dysfunction, we developed an in vitro model of sepsis-induced acute kidney injury using proximal tubular epithelial cell lines (HK-2) exposed to a bacterial endotoxin (lipopolysaccharide, LPS). Using this model, our first work has demonstrated that the basal respiration of renal HK-2 cells subjected to endotoxins was altered and presented a strong decrease in the oxygen consumption rates. Our working hypothesis of the pathophysiology of sepsis-induced AKI is based on a change in mitochondrial function that has been termed cytopathic hypoxia. A consequence of mitochondrial function alterations is an inability of the cell to use molecular oxygen for ATP production. The oxidative phosphorylation within mitochondria is interrupted because of the inhibition of cytochrome oxidase. The present investigation was carried out to establish whether mitochondrial alterations might be a mechanism of renal tubular epithelial injury during sepsis. To reach this goal the mitochondrial alterations of renal HK-2 cells exposed to an endotoxic stress was studied by confocal laser-scanning microscope. Confocal microscope allowed observation of the evoked phenomena at the single cell level and in real time. More particulary, mitochondrial morphology, mitochondrial membrane potential (ΔΨm) and generation of reactive oxygen species were recorded using specific vital fluorescent probes and quantified by image processing and analysis. Mitochondrial membrane potential is generated by the mitochondrial electron transport chain. This gradient is critical for the formation of ATP, and a fall in membrane potential is an indicator of mitochondrial dysfunction. ΔΨm was measured using the lipophilic cationic probe TMRE and it was shown that LPS produced a decrease in ΔΨm. In parallel, superoxide generation was measured by using MitoSOX which is selectively targeted to the mitochondria. There was a significant increase in mitochondrial superoxide-specific oxidation of MitoSOX when HK-2 cells were submitted to LPS. Overall, the model of HK-2 cells exposed to LPS displays some key features of sepsis-induced acute kidney injury. The confocal microscopy study has suggested a mechanism of toxicity dependent on mitochondrial oxidant generation and mitochondrial dysfunction. Indeed, the exposure to LPS has resulted in an increased generation of superoxide and a loss of mitochondrial function probably initiated by a fall in mitochondrial potential. [less ▲]

Small animal imaging with human PET

Poster (2012, September)

PET studies provide valuable information in the assessment of animal models for human diseases. MicroPET systems provide the high resolution needed to explore small organs but suffer from a reduced axial ... [more ▼]

PET studies provide valuable information in the assessment of animal models for human diseases. MicroPET systems provide the high resolution needed to explore small organs but suffer from a reduced axial FOV. Multiple bed positions are then used to obtain whole body scans resulting in increased scan time and incomplete dynamic data. In contrast, human PET systems have larger axial FOV but a lower resolution. In this study, an image-based model of the scanner spatial response function combined with a 3D-OSEM reconstruction algorithm were used to improve spatial resolution of the Siemens ECAT EXACT HR+ PET scanner. A stationary double Gaussian model [1] of the ECAT EXACT HR+ point spread function was derived from 18F point source measurements performed at different radial and axial locations in the scanner FOV. This model was used in a 3D-OSEM reconstruction (3D-OSEM-RM). Sinograms were normalized and attenuation and scatter corrected using the Siemens ECAT tools before reconstruction. Both NEMA NU 2-1994 performance phantoms and NEMA NU4-2008 image quality phantom mimicking small animals were used to evaluate the accuracy of corrections for physical effects and the overall image quality. A 50 min dynamic FDG rat study was conducted on the ECAT HR+ and reconstructed with 3D-OSEM-RM. The images were used to compute the metabolic rate of glucose (MRglu) in multiple brain structures. These images were also visually compared to the static image obtained with a FOCUS 120 microPET immediately after the HR+ dynamic scan. The standard deviations of the two Gaussians used to model the transaxial (axial) resolution in a central FOV of 5 cm radius were σ1 = 1.6 (2.75) mm and σ2 = 3.66 (4.16) mm, and the ratio of the weights between the first and second Gaussians was ρ = 0.2 (0.7). Image uniformity and accuracy of scatter and attenuation corrections, evaluated following NEMA NU 2-1994, were found to be very similar between 3D-OSEM, 3D-OSEM-RM, 2D- and 3D-FBP reconstructed images. When using the NEMA NU4-2008 image quality phantom a significant increase of the hot rod recovery coefficient was observed. This effect was rod size dependent and amounted to 17-35% for the 3D-OSEM-RM compared to the 3D-OSEM and to 35-62% compared to the FBP reconstructions. Nevertheless the values obtained with 3D-OSEM-RM were around 20-35% lower than those obtained with the FOCUS 120 microPET scanner. Most of the small brain structures observed on microPET images were also visible on the images obtained with the HR+ scanner and 3D-OSEM-RM. Rat cerebral MRglu values calculated on 3D-OSEM-RM images were in the range of published values [2] (e.g. whole brain = 25.34 μmol/min/100g). Using an approximate model of the ECAT EXACT HR+ spatial response in 3D-OSEM resulted in sufficient image quality for dynamic whole body scans of small rodents, despite the large FOV, and resulted in improved contrast compared to images generated using the built-in software. This methodology will be applied for future small animal dosimetry and modeling studies in our laboratory. [1] Comtat et al. IEEE Nucl Sci Symp Conf Record. pp. 4120-4123 (2008) [2] Schiffer et al. J Nucl Med 48:277-287 (2007) [less ▲]

PET In Conscious Rodents - Quantification of Stress During The Training Process

Poster (2012, September)

Recently several methods for performing PET studies in conscious rodents have been developed [1-3]. These methods have the potential to greatly improve the translational nature of PET studies in rodents ... [more ▼]

Recently several methods for performing PET studies in conscious rodents have been developed [1-3]. These methods have the potential to greatly improve the translational nature of PET studies in rodents. One of the most easily implemented methods is the training of a rat to tolerate head fixation in a restraining device. Training consists of intervals of restraint over several days. However, the stress induced by this training procedure has not been quantified in detail. Limited changes in plasma corticosterone have been reported, but this data may be confounded by sample timing and baseline levels. An implantable telemetry system (Telemetry Research) was used to remotely measure blood pressure, heart rate and core temperature during training. Transmitters were implanted in the abdominal cavity under isoflurane anesthesia, with the blood pressure sensor fixed in the abdominal aorta. Training was started after a recovery period of at least 1 week. Training consisted of a 5 min period of acclimatization in the cage containing the restraining device, followed by increasing durations of restraint in the device on subsequent training days (15, 30, 45, 60, 90 min). Telemetry data was acquired from 5 min prior to acclimatization to 60 minutes post-training. In this initial pilot study, a single rat was trained, without head fixation, for 4 consecutive days and again on day 7. All reported values are mean ± SEM across the five training days. In the home cage, prior to acclimatization, baseline heart rate (HR) was 294 ± 15 bpm. During the acclimatization period, HR was elevated to 411 ± 7 bpm. Immediately after starting training, HR was 419 ± 16 bpm. During the training period HR showed a tendency to decrease, with raised periods at undefined intervals. After return to the home cage, HR remained elevated for 15-20 min before returning to a value (313 ± 9 bpm) close to baseline. A similar pattern was seen in blood pressure (mean; BP). Baseline BP was 76 ± 7 mmHg, increasing to 94 ± 9 mmHg during acclimatization. After commencing training, a peak in BP was reached at 102 ± 8 mmHg. After the 15-20 min recovery interval, BP returned to a baseline of 77 ± 9 mmHg. The HR and BP responses to acclimatization and to the training protocol persisted throughout all training days, with the main noticeable difference being the number of bouts of increased HR, which increased with training duration. Core body temperature (baseline: 37.45 ± 0.21 °C) increased during restraint training, with a subsequent post-training peak (38.21 ± 0.03 °C). Measurement of core temp is complicated during longer training sessions by the need to charge the transmitter. This early data indicates that stress induced by the training procedure for conscious PET persists after several days of training. In subsequent studies the head will be fixed and the effect of the training on plasma corticosterone and central glucose metabolism (using [18F]FDG) will be examined. [1] Momosaki et al. (2004) Synapse 54:207–213 [2] Wyss et al. (2009) NeuroImage 48:339–347 [3] Itoh et al. (2009) J Nucl Med 50:749–756 [less ▲]

Les modèles globaux projettent-ils plus de blocages anticycloniques en Europe pour le futur ?

in Bigot, Sylvain; Rome, Sandra (Eds.) XXVème colloque de l'Association Internationale de Climatologie - Les climats régionaux : observation et modélisation (2012, September)

The IPCC projects more frequent and longer heat waves and droughts during summer for future over Western Europe. These extreme events occur during anticyclonic blocking events. We use atmospheric ... [more ▼]

The IPCC projects more frequent and longer heat waves and droughts during summer for future over Western Europe. These extreme events occur during anticyclonic blocking events. We use atmospheric circulation type classifications to determine if the models project an increase of the number and the persistence of these anticyclonic blockings. For recent climate, the number of blocking events depends on the ability of the models to reproduce the observed general circulation. The future projections do not show any systematic evolution of the number of anticyclonic blockings over Western Europe. Nevertheless, other changes like an increase of the temperature will lead to more frequent heat waves and droughts. [less ▲]

Time- and frequency-domain subspace identification of a nonlinear spacecraft

in Proceedings of the ISMA International Conference on Noise and Vibration Engineering 2012 (2012, September)

The present paper discusses the identification of the SmallSat spacecraft, a real-life nonlinear space structure developed by EADS-Astrium. To this end, two nonlinear subspace identification techniques ... [more ▼]

The present paper discusses the identification of the SmallSat spacecraft, a real-life nonlinear space structure developed by EADS-Astrium. To this end, two nonlinear subspace identification techniques formulated in the time and frequency domains are exploited, referred to as the TNSI and FNSI methods, respectively. The frequency response functions (FRFs) of the underlying linear spacecraft and the nonlinear coefficients are estimated by these approaches. The nonlinear component comprises an inertia wheel mounted on a support, the motion of which is constrained by eight elastomer plots and mechanical stops. This application is challenging for several reasons, which include high modal density, the discontinuous nature of the nonlinearities and order selection of the identified reduced model. [less ▲]

Successions internationales - panorama des difficultés dans les relations belgo-allemandes

Conference (2012, September)

Cette présentation fait le point sur les difficultés que présent le cadre juridique en vigueur actuellement dans les relations belgo-allemandes en matière successorale, pour mieux illustrer l'impact qu ... [more ▼]

Cette présentation fait le point sur les difficultés que présent le cadre juridique en vigueur actuellement dans les relations belgo-allemandes en matière successorale, pour mieux illustrer l'impact qu'aura le Règlement succession dont l'entrée en vigueur est prévue en 2015. [less ▲]

Anodal transcranial direct current stimulation over the visual cortex as a preventive treatment of migraine: a proof-of-concept study.

in Frontiers in Human Neuroscience (2012, September)

GH or IGF-1 : which one is raising blood glucose ? Hints from the LAS (Liege Acromegaly Survey)

in Journal of Klinische Endokrinologie und Stoffwechsel (2012, September), 5(3),

CHARACTERIZATION OF A NOVEL RADIOTRACER TARGETING SYNAPTIC VESICLE PROTEIN 2A (SV2A)

Poster (2012, September)

Synaptic vesicle protein 2A (SV2A) has been identified as the binding site of the antiepileptic levetiracetam (Keppra) [1]. SV2 proteins are critical for proper nervous system function and have been ... [more ▼]

Synaptic vesicle protein 2A (SV2A) has been identified as the binding site of the antiepileptic levetiracetam (Keppra) [1]. SV2 proteins are critical for proper nervous system function and have been demonstrated to be involved in vesicle trafficking. Their implication in epilepsy makes them an interesting therapeutic target, and the widespread distribution of SV2A in particular may provide an opportunity to develop a PET-based measure of neuronal function in brain diseases. [18F]UCB-H is a fluorine-18 radiolabelled PET imaging agent with a nanomolar affinity for the human SV2A protein. Preclinical PET studies in rodents were carried out using male SD rats, imaged under isoflurane anaesthesia in a Siemens Concorde Focus 120 microPET scanner. Arterial input function was measured using an arteriovenous shunt method and beta microprobe system. [18F]UCB-H was injected IV (3.8 ± 0.54 mCi bolus, specific activity 8.5 ± 0.86 Ci/Emol immediately after synthesis) and dynamic PET data acquired in list mode for 90 min. Images were reconstructed using filtered back projection with correction for all physical effects except scatter. These scans revealed high uptake of [18F]UCB-H in brain and spinal cord, matching the expected homogeneous distribution of SV2A in the rodent brain [2]. Notably, the kinetics of [18F]UCB-H uptake in the brain were fast, peaking at up to 30 % ID/cm3 before a rapid decline. Metabolism of [18F]UCB-H in vivo followed a typical pattern of rapid initial metabolism followed by a reducing rate of metabolism over time, with less than 20% of the activity in plasma attributable to the parent compound after 30 minutes, and was highly reproducible between subjects. One major metabolite was identified. The uptake of [18F]UCB-H in the brain over time was well fitted by a classical 1-tissue compartment model. Mean parameter estimates (mean ± SD, n=7, whole brain VOI) were K1: 3.58 ± 0.65 ml/cm3/min, k2: 0.21 ± 0.03 min-1, Vt: 17.21 ± 2.52 ml/cm3. Uptake of [18F]UCB-H was blocked by pretreatment with brivaracetam (21 mg/kg IV, 10 min prior to [18F]UCB-H), a recently described high affinity SV2A ligand with a 20-fold higher affinity for SV2A than levetiracetam [3]. In contrast, pretreatment with ucb-100230-1, a diastereoisomer of brivaracetam with 3200-fold lower affinity for SV2A [3], had no clear effect of the brain uptake of [18F]UCB-H. Our results indicate that [18F]UCB-H is a suitable radiotracer for the quantification of SV2A proteins in vivo and for estimating target occupancy of drugs targeting SV2A. This is the first PET tracer for in vivo quantification of SV2A. The necessary steps for implementation of [18F]UCB-H production under GMP conditions have been completed and first in human studies are planned. References [1] Lynch, B.A. et al. (2004) PNAS 101(26):9861-6. [2] Janz, R. & Sudhof, T.C. (1999) Neuroscience 94(4):1279-1290.[3] Gillard, M. et al. (2011) Eur J Pharmacol 664:36-44. [less ▲]

Aires et agrandissements. Maths & Manips pour la transition primaire-secondaire

in Losanges (2012, September), 18

The Art of the States Project: Performance Effects of Administrative Innovations in US State Governments

Poster (2012, September)

The diversification of early eukaryotes

Conference (2012, September)

Mineralogy of Miocene lacustrine sequences associated with hominid sites in East Africa; indicator of palaeoenvironmental conditions (Tugen Hills, Kenya).

Poster (2012, September)

Effect of body weight losson pulmonary function assessed by 6-minute walk test and arterial blood gases in obese dogs

in Proceedings of 22nd ECVIM Meeting - Maastricht, Netherlands (2012, September)

Un projet de promotion de la santé mentale : des actions élaborées avec une association d'usagers, partenaire du projet

Conference (2012, September)

Current evidence and indications for Prolotherapy with Platelet Rich Plasma in chronic musculoskeletal conditions

in Regional Anesthesia & Pain Medicine (2012, September), 37(5 - Suppl 1), 104-106

The coexistence of a pituitary adenoma and pheochromocytoma (a case report)

in Abstract Book - 13th International Workshop on Multiple Endocrine Neoplasia (2012, September)

Behavioural adaptations of rheophilic fish radio-tracked in a river highly fragmented by hydroelectric plants. Outcomes of a partial reopening of their migration routes.

in Proceedings of the 9th International Conference on Ecohydraulics (2012, September)

Using water resources for hydroelectricity production influences and limits the quality and quantity of habitat available for use by fishes and influences fish mobility. In the Amblève (River Meuse basin ... [more ▼]

Using water resources for hydroelectricity production influences and limits the quality and quantity of habitat available for use by fishes and influences fish mobility. In the Amblève (River Meuse basin, Belgium), the major part of the river is fragmented by hydroelectric power plants that largely prevent the biological movements of the fish population. In 2007, in the hydroelectric site of Lorcé, a modern pool-type fish pass was constructed, re-establishing the upstream movements of fish after more than 80 years of total obstruction. Sixteen different fish species promptly used the new fish pass and the objective of our study was to analyse their behavioural tactics and spawning activity once released upstream of the dam in a previously inaccessible environment. The study focussed on rheophilic holobiotic species, the nase (Chondrostoma nasus), the barbel (Barbus barbus), the European grayling (Thymallus thymallus) and the brown trout (Salmo trutta), which are highly representative of the fish population of the river. The fish were radio-tagged and intensively located using manual tracking techniques during their circum reproduction periods. The results indicate that most individuals of the different species seem to have found usable spawning areas and exploited a large part of the newly usable river stretch (as well as tributaries) located upstream of the fish pass. However, a major problem was observed during the post-spawning period, when the tracked individuals tried to reach their original departure sites (located downstream of the fish pass). The absence of a downstream migration device combined with the passage of all the water through the turbine severely disrupted their post-reproductive movements. [less ▲]

Venus O2 night glow observations with VIRTSI/Venus Express

Conference (2012, September)

Inversion of multi-temporal geoelectrical data sets: insights from several case studies

in Berichte der Geologischen Bundesanstalt (2012, September), 93

Influence of sleep homeostasis and circadian rhythm on waking EEG oscillations during a constant routine

Poster (2012, September)

Introduction & Objectives Human sleep and wake EEG oscillations are modulated by complex non-additive interaction between homeostatic and circadian processes. Quantitative analysis of EEG data, during ... [more ▼]

Introduction & Objectives Human sleep and wake EEG oscillations are modulated by complex non-additive interaction between homeostatic and circadian processes. Quantitative analysis of EEG data, during extended wakefulness, indicate that its frequency-specificity is influenced by both factors, such that low-frequencies (<8Hz) increase with time spent awake (1), thus more homeostatically-driven, while alpha activity undergoes a clear circadian modulation (2). Interindividual differences in sleep-wake regulation in young volunteers are associated with the variable-number tandem-repeat (VNTR) polymorphism in the coding region of the circadian clock gene PERIOD3 (PER3). Individuals homozygous for the longer allele of PER3 (PER35/5) were reported to generate more slow wave activity during NREM sleep and theta activity during wakefulness, relative to individuals with the shorter allele (PER34/4). However, the phase and amplitude of circadian markers do not differ between these genotypes (3). Here we tested the hypothesis if fluctuations in the dynamics of waking EEG frequency-specificity are modulated by a polymorphism in the clock gene PER3, under 42h of sustained wakefulness. Materials and Methods Population. A total of 400 young men and women were recruited, from whom DNA samples and questionnaire data were collected. On the basis of their PER3 polymorphism, 35 healthy young volunteers (age: 19-26 y; 17 females) were recruited, out of which twelve were PER35/5 and twenty-three PER34/4 homozygotes, and matched by age, gender, level of education, chronotype and IQ at the group level. Study protocol. The laboratory part of this study began in the evening of day 1 until day 5 (Fig. 1). During the first 2 nights (habituation and baseline), volunteers followed one out of two possible sleep-wake schedules (00:00-08:00 or 01:00-09:00). Thereafter, participants underwent approximately 42 hours of sustained wakefulness under constant routine (CR) conditions (semi-recumbent position, dim light <5 lux, no time-of-day information), and a subsequent recovery sleep episode. EEG recordings. Continuous EEG measurements with 9 EEG channels (F3, Fz, F4, C3, Cz, C4, Pz, O1, O2) were performed throughout the CR. Waking EEG was recorded every 2-h, during a modified version of the Karolinska Drowsiness Test (KDT) (4). Data presented here pertain to the last 60-sec of KDT, during which subjects were instructed to relax, to fixate a dot displayed on a screen ca. 75cm and to try to suppress blinks. After re-referencing to mean mastoids, recordings were scored using Rechtschaffen criteria. The 1-min EEGs during the KDT were manually and visually scored for artifacts (eye blinks, body movements, and slow eye movements) offline by 2 independent observers. The absolute EEG power density was then calculated for artifact-free 2-s epochs in the frequency range of 0.5 to 20 Hz , overlapping by 1 second using the pwelch function in MATLAB (7.5.0). For data reduction, power density of artifact-free 2-s epochs was averaged over 20-s epochs. Statistics. Waking EEG delta (0.75-4.5Hz), theta (4.75-7.75Hz) and alpha (8-12.0Hz) power density computed on Central derivation (Cz) were analyzed with a mixed-model analysis of variance (PROC Mixed), with main factors “elapsed time awake” and “genotype” (PER34/4 and PER35/5), and the interaction of these two factors. All p-values derived from r-ANOVAs were based on Huynh-Feldt's (H-F) corrected degrees of freedom (p<0.05). Multiple comparisons were performed using Tukey-Kramer test. Theoretical coefficients for the homeostatic sleep pressure (derived from a quasi-linear function) and the circadian oscillation (24-hour period sine wave) were used in a multiple regression model to predict delta, theta and alpha activity during the CR. Prior to multiple regression analysis, data were normalized according to PROC Transreg, in order to derive the best normalization method for linear and non-linear datasets. Results. Delta activity Analysis of delta activity yielded a significant main effect of “elapsed time awake” (F=5.31; p < 0.0001), albeit no significant effects for “genotype” (F=0.01; p = 0.94) nor for the interaction of these factors (F=0.85; p = 0.65). The multiple regression model revealed a significant regression (R² = 0.0433 Adj. R² = 0.0404; F = 15.24; p <0.0001), for the homeostat (p < 0.0001 ) and circadian (p = 0.0006) coefficients. Theta activity Analysis of theta activity yielded a significant main effect of “elapsed time awake” (F= 12.2; p < 0.0001), although no significant effects for “genotype” (F= 0.1; p = 0.70) nor for the interaction of these factors (F= 0.67; p = 0.86). The multiple regression model revealed a significant regression (R²= 0.072 Adj. R² =0.069; F= 26.36; p <0.0001), for the homeostat (p < 0.0001 ) and circadian (p < 0.0001 ) coefficients. Alpha activity Analysis of alpha activity yielded a significant main effect of “elapsed time awake”(F=3.43; p < 0.0001), although no significant effects for “genotype” (F = 0.01; p = 0.92) nor for the interaction of these factors (F= 1.23; p = 0.22). The multiple regression model revealed a significant regression (R²=0.052; Adj. R²=0.05; F =18.63; p <0.0001), for the homeostat (p = 0.0012) and for the circadian (p < 0.0001) coefficients. Conclusion Our results indicate that fluctuations in the dynamics of waking EEG activity are modulated by the circadian and homeostatic processes, although the magnitude of these differences are not underlined by a polymorphism in the clock gene PER3. REFERENCES 1. Cajochen C, Brunner DP, Kräuchi K, Graw P, Wirz-Justice A. Power density in theta/alpha frequencies of the waking EEG progressively increases during sustained wakefulness. Sleep. 1995, 10:890-894. 2. Cajochen C, Wyatt JK, Czeisler CA, Dijk DJ.Separation of circadian and wake duration-dependent modulation of EEG activation during wakefulnessNeuroscience. 2002, 114:1047-60. 3. Viola AU, Archer SN, James LM, Groeger JA, Lo JC, Skene DJ, von Schantz M, Dijk DJ PER3 polymorphism predicts sleep structure and waking performance. Curr Biol 2007,17:613–618. 4. Gillberg M, Kecklund G, Akerstedt T. Relations between performance and subjective rating of sleepiness during a night awake. Sleep 1994, 17:236-241. ACKNOWLEDGEMENTS & SPONSORS Cyclotron Research Centre (CRC) ; Belgian National Funds of Scientific Research (FNRS) ; Actions de Recherche Concertées (ARC, ULg) – Fondation Médicale Reine Elisabeth (FMRE) ; Walloon Excellence in Lifesciences and Biotechnology (WELBIO) ; Wellcome Trust ; Biotechnology and Biological Sciences Research Council (BBSRC) [less ▲]

Diagrammatic experiment in Mathematics and in Works of Art

in Haworth, Karen (Ed.) Proceedings of the 37th Annual Meeting of the Semiotic Society of America (Semiotics 2011) (2012, September)

This talk aims to compare the theory of diagram presented in Peirce’s philosophy of mathematics and reflections on the work of art formulated by Henry Van Lier and René Thom. The Peircean Theory of ... [more ▼]

This talk aims to compare the theory of diagram presented in Peirce’s philosophy of mathematics and reflections on the work of art formulated by Henry Van Lier and René Thom. The Peircean Theory of diagram states that a diagram is a visual configuration characterized as a totality that is necessary and at the same time dynamic and experimental. In his lectures about the relation between the local and the global in art (Apologie du logos, 1990), Thom traces a theory of contours of forms that is very similar to the conception of diagram in Peirce’s philosophy. For Thom, beauty is the result of strategies of framing and of composing parts in a dynamic totality. Van Lier’s reflections on works of art develop the idea of a perfect totality characterized by a syntax of traits that are at the right place and that couldn’t be organized in any other way, without which the work of art would have no efficacy. For my part, I aim to explore these similar conceptions of a necessary totality in the arts (aesthetic necessity) and in mathematical diagrams (the necessity in demonstration through forms) in order to describe the differences and the similarities between the theories and the domains of application. [less ▲]

Dioxin Food Crises and New POPs: Challenges in Analyses

Conference (2012, September)

Use of human dried-blood spots as a minimally invasive method to assess exposure to organic pollutants

Conference (2012, September)

Tra canonizzazione della ‘norma’ ed infrazione. Sondaggi dai frammenti grammaticali latini su papiro (II-VI sec. d.C.)

Conference (2012, September)