Conceptualisation et emploi du passé composé et de l'imparfait en français langue étrangère (L3) au Sri Lanka : l'impact du singhalais langue maternelle (L1) et de l'anglais langue seconde (L2)

Résumé: Notre étude chevauche deux domaines de recherche quasi indissociables : ceux de la linguistique et de la didactique des langues. Comme l'indique le sujet, elle examine la conceptualisation et l'emploi de deux notions aspecto-temporelles du français (le passé composé et l'imparfait), sous l'impact des connaissances grammaticales déjà acquises sur deux autres langues : le singhalais et l'anglais. Notre recherche relève des domaines de la psycholinguistique, de la linguistique acquisitionnelle et de la linguistique comparative. Toutefois, dans le cadre de cette étude, nous examinons ces notions grammaticales françaises et leurs équivalents présumés dans les deux autres langues comme étant des concepts relevant des langues à statuts sociaux spécifiques [à savoir, langue maternelle (L1), langue seconde (L2) et langue étrangère (L3)], dans un contexte particulier d'enseignement/apprentissage et d'acquisition de langue [à savoir, le contexte d'enseignement/apprentissage et d'acquisition du français langue étrangère (FLE) au Sri Lanka]. En ce sens, notre étude est également liée aux domaines de la sociolinguistique et de la didactique des langues, notamment, étrangères. Ce qui pourrait probablement distinguer cette recherche des autres, c'est qu'elle aborde certaines questions linguistiques et didactiques peu étudiées jusqu'ici. Entre autres, l'influence de deux langues sur l'enseignement/apprentissage d'une L3, l'enseignement/apprentissage des langues dans des contextes exolingues et le rôle des transferts dans la conceptualisation des notions grammaticales. Pourtant, lorsque nous avons choisi le contexte d'apprentissage du FLE au Sri Lanka comme terrain de recherche, nous avons également visé d'autres objectifs : examiner les systèmes verbaux de trois langues dont l'imbrication n'a pas encore été objet d'étude ; examiner le système verbal aspecto-temporel peu explicité du singhalais à la lumière des descriptions linguistiques occidentales ; vérifier certains préjugés concernant les liens de proximité et de distance entre les trois langues choisies et étudier les causes de ces préjugés. Notre corpus provient de plusieurs classes de FLE au Sri Lanka. Le public observé était constitué d'adolescents ou d'adultes bilingues ayant le singhalais en L1 et l'anglais en L2. Les cours choisis se distinguaient les uns des autres par plusieurs critères, mais travaillaient tous sur les notions du passé composé et de l'imparfait. A la conclusion de notre étude, nous avons constaté qu'un nombre important de nos hypothèses initiales se sont avérées véridiques. A titre d'exemples, les transferts entre les langues premières et la langue cible sont récurrents et non négligeables chez l'écrasante majorité des apprenants exolingues observés, et parfois, même chez leurs enseignants; si ces apprenants recourent à ces langues pour étayer leur apprentissage, ni leurs enseignants ni leurs manuels provenant de l'étranger ne les guident dans ce travail; les transferts ayant l'anglais pour origine l'emportent considérablement sur ceux provenant du singhalais. De même, suite à l'analyse contrastive des trois systèmes verbaux aspecto-temporels et à l'analyse du corpus, nous avons également eu un résultat imprévu : contrairement à une représentation répandue chez les apprenants singhalais, il existe des points convergents entre leur L1 et le français ; du moins, au niveau de l'emploi de certains temps du passé. Un fait dont on était jusqu'ici ignorants mais dont on peut sûrement profiter dans les cours de FLE au Sri Lanka. Suite à ces observations et à la fin de notre thèse, nous avons fait quelques recommandations didactiques afin d'améliorer les conditions d'enseignement/apprentissage des langues étrangères, au Sri Lanka et ailleurs. Abstract: Our research is related to the fields of both linguistics and didactics, two research areas which are almost inseparable. As the title shows, the thesis examines the issue of conceptualizing and using of two grammatical (aspectual and temporal) concepts of the French language (le passé composé and l'imparfait), under the influence of previously acquired grammatical knowledge of two other languages: Sinhalese and English. Thus, our research is linked to the domains of psycholinguistics, acquisitional linguistics and comparative linguistics. However, within the framework of this study, we will consider the above-mentioned two French grammatical concepts and their presumed equivalents in the other two languages as concepts belonging to three languages with specific social status [i.e. first language (L1), second language (L2) and foreign language (L3)], taught/learnt/acquired in a particular language teaching/learning context [the context of teaching/learning of French as a foreign language (FFL) in Sri Lanka]. In that sense, our study is also associated with the fields of sociolinguistics and language teaching, especially foreign language teaching. What could probably make this study outstanding is that it studies certain linguistic and didactic issues which have not yet been studied. For example, it examines, among other issues, the following: the influence of two languages (i.e. mother tongue -L1 & second language -L2) on the teaching/learning process of a third language (i.e. foreign language- L3); foreign language teaching and learning in an exolingual context (where the target language is not spoken outside the classroom); the role of language transfers in the process of grammatical notion conceptualization. However, in selecting the FFL teaching/learning context in Sri Lanka as our field of research, we had further objectives in mind : i.e. 1) studying the verb systems of three languages whose combination has never been studied before ; 2) studying the aspectual-temporal formation of the Sinhalese verb system (which is hardly taught explicitly) in the light of the linguistic descriptions of dominant European languages; 3) verifying certain preconceived ideas regarding the proximity and the distance between the three chosen languages, and 4) studying the causes for these preconceptions. Our corpus is obtained from a number of FFL classes in Sri Lanka. The observed student groups consisted of bilingual adolescents and adults whose first language (L1) was Sinhalese and the second language (L2) was English. The observed classes differed in many ways but in each of those classes, a common factor was that the students had been learning some aspect of the two grammatical concepts, le passé composé and l'imparfait. Having completed our study, we now see that a considerable number of our initial hypotheses are proven correct. For example, in the exolingual French language teaching/learning context in Sri Lanka where we carried out our research, language transfers between the first and target languages were recurrent and numerous in the work of the greater majority of the observed language learners, and even their teachers; these transfers were so frequent that they could hardly be ignored during the teaching/learning process ; although learners turned to their first languages to facilitate the learning process of a new language, neither their teachers, nor their text books helped them in this task; the transfers originating from English were far too numerous than those originating from Sinhalese; however, contrary to the popular belief among many Sinhalese learners of French, the contrastive analysis of the three aspectual-temporal verb systems and the study of our corpus helped us in proving that there are common linguistic features between the Sinhalese and the French languages ; at least, when it comes to using some of their past tenses. This is a fact which had been ignored up to now but which could probably be used to improve French teaching/learning in Sri Lanka. Taking all observations into account, we made some pedagogical recommendations in the concluding part of our thesis with the view of improving foreign language teaching/learning in Sri Lanka, and elsewhere.

A morphological grading of spinal stenosis: a radiological study on LSS and LBP patients : P173

Introduction: Clinical symptoms and degree of spinal stenosis based on cross sectional dural sac area correlate only weakly in lumbar spinal stenosis (LSS) patients. We conceived a four grade classification system (A, B, C & D) based on the morphology of the dural sac and its contents as seen on T2 axial MRI images. The categories take into account the rootlet/CSF ratio. We applied this grading to three patient groups: LSS scheduled for surgery; LSS following conservative treatment and patients with low back pain (LBP) without leg pain. Materials/Methods: A total of 346 T2 axial MRI images taken from LSS and LBP patients were included in this retroperspective study. 37 patients had decompressive surgery (132 MRI images), 31 conservative treatment (116 MRI images) and 27 patients had unspecific LBP (98 MRI images). Dural sac cross-sectional surface area and morphological grading of the canal were measured digitally both at disc and pedicle level. Intra- and inter-observer reliability were assessed (weighted Cohen's kappa statistics) from 50 MRI images taken from the surgery group. Results: At the most severe disc level, grade A (mild stenosis) was found in 3% of MRI images of the surgical group as opposed to 51% in the conservatively treated group and 85% in the LBP group. Grade B occurred in 8% of the surgical, 20% of the conservative and was negligible in LBP group (below 1%). Grade C and D (severe stenosis) was found in 89% of the surgical group, as opposed to 30% in conservative group and 11% in LBP group. The grades of all groups were comparable at the pedicle levels, exhibiting in 94% a grade A with a maximum at the A1 grade. Pedicle and disc level cross-sectional area were smallest in the surgery group and smaller in the conservative group as compared to the LBP group at the levels L2, L3 and L4. According to cross-sectional area measurements patients from the surgery group seems to have smaller vertebral canal although this was not related to smaller stature. Validation of grading: Average intra-and inter observer kappas were 0.76 and 0.69 respectively, for physicians working in the study originating institution. Combining all observers the kappa values were 0.57 +/- 0.19. and 0.44 +/- 0.19 respectively. Dural sac cross-sectional area measurements showed no statistically significant differences between observers. Conclusion: Since no specific measurement tools are needed the grading suits everyday clinical practice and favours communication of degree of stenosis between practising physicians. In our institution Grade A stenosis was less likely to require surgical treatment. This grading can therefore be an aid in surgical patient selection in teaching units.

Trunk neuromuscular responses to a single whole-body vibration session in patients with chronic low back pain: a cross-sectional study.

OBJECTIVE: Whole-body vibration (WBV) exercise is progressively adopted as an alternative therapeutic modality for enhancing muscle force and muscle activity via neurogenic potentiation. So far, possible changes in the recruitment patterns of the trunk musculature after WBV remain undetermined. The main objective of this study was to evaluate the short-term effects of a single WBV session on trunk neuromuscular responses in patients with chronic low back pain (cLBP) and healthy participants. METHODS: Twenty patients with cLBP and 21 healthy participants performed 10 trunk flexion-extensions before and after a single WBV session consisting of five 1-minute vibration sets. Surface electromyography (EMG) of erector spinae at L2-L3 and L4-L5 and lumbopelvic kinematic variables were collected during the trials. Data were analyzed using 2-way mixed analysis of variance models. RESULTS: The WBV session led to increased lumbar EMG activity during the flexion and extension phases but yielded no change in the quiet standing and fully flexed phases. Kinematic data showed a decreased contribution to the movement of the lumbar region in the second extension quartile. These effects were not different between patients with cLBP and healthy participants. CONCLUSIONS: Increased lumbar EMG activity after a single WBV session most probably results from potentiation effects of WBV on lumbar muscles reflex responses. Decreased EMG activity in full trunk flexion, usually observed in healthy individuals, was still present after WBV, suggesting that the ability of the spine stabilizing mechanisms to transfer the extension torque from muscles to passive structures was not affected.

The predictive value of trabecular bone score (TBS) on whole lumbar vertebrae mechanics: an ex vivo study.

We investigated the association of trabecular bone score (TBS) with microarchitecture and mechanical behavior of human lumbar vertebrae. We found that TBS reflects vertebral trabecular microarchitecture and is an independent predictor of vertebral mechanics. However, the addition of TBS to areal BMD (aBMD) did not significantly improve prediction of vertebral strength. INTRODUCTION: The trabecular bone score (TBS) is a gray-level measure of texture using a modified experimental variogram which can be extracted from dual-energy X-ray absorptiometry (DXA) images. The current study aimed to confirm whether TBS is associated with trabecular microarchitecture and mechanics of human lumbar vertebrae, and if its combination with BMD improves prediction of fracture risk. METHODS: Lumbar vertebrae (L3) were harvested fresh from 16 donors. The anteroposterior and lateral bone mineral content (BMC) and areal BMD (aBMD) of the vertebral body were measured using DXA; then, the TBS was extracted using TBS iNsight software (Medimaps SA, France). The trabecular bone volume (Tb.BV/tissue volume, TV), trabecular thickness (Tb.Th), degree of anisotropy, and structure model index (SMI) were measured using microcomputed tomography. Quasi-static uniaxial compressive testing was performed on L3 vertebral bodies to assess failure load and stiffness. RESULTS: The TBS was significantly correlated to Tb.BV/TV and SMI (râeuro0/00=âeuro0/000.58 and -0.62; pâeuro0/00=âeuro0/000.02, 0.01), but not related to BMC and BMD. TBS was significantly correlated with stiffness (râeuro0/00=âeuro0/000.64; pâeuro0/00=âeuro0/000.007), independently of bone mass. Using stepwise multiple regression models, we failed to demonstrate that the combination of BMD and TBS was better at explaining mechanical behavior than either variable alone. However, the combination TBS, Tb.Th, and BMC did perform better than each parameter alone, explaining 79 % of the variability in stiffness. CONCLUSIONS: In our study, TBS was associated with microarchitecture parameters and with vertebral mechanical behavior, but TBS did not improve prediction of vertebral biomechanical properties in addition to aBMD.

Voltage-gated sodium channel expression in mouse DRG after SNI leads to re-evaluation of projections of injured fibers.

BACKGROUND: Dysregulation of voltage-gated sodium channels (Na(v)s) is believed to play a major role in nerve fiber hyperexcitability associated with neuropathic pain. A complete transcriptional characterization of the different isoforms of Na(v)s under normal and pathological conditions had never been performed on mice, despite their widespread use in pain research. Na(v)s mRNA levels in mouse dorsal root ganglia (DRG) were studied in the spared nerve injury (SNI) and spinal nerve ligation (SNL) models of neuropathic pain. In the SNI model, injured and non-injured neurons were intermingled in lumbar DRG, which were pooled to increase the tissue available for experiments. RESULTS: A strong downregulation was observed for every Na(v)s isoform expressed except for Na(v)1.2; even Na(v)1.3, known to be upregulated in rat neuropathic pain models, was lower in the SNI mouse model. This suggests differences between these two species. In the SNL model, where the cell bodies of injured and non-injured fibers are anatomically separated between different DRG, most Na(v)s were observed to be downregulated in the L5 DRG receiving axotomized fibers. Transcription was then investigated independently in the L3, L4 and L5 DRG in the SNI model, and an important downregulation of many Na(v)s isoforms was observed in the L3 DRG, suggesting the presence of numerous injured neurons there after SNI. Consequently, the proportion of axotomized neurons in the L3, L4 and L5 DRG after SNI was characterized by studying the expression of activating transcription factor 3 (ATF3). Using this marker of nerve injury confirmed that most injured fibers find their cell bodies in the L3 and L4 DRG after SNI in C57BL/6 J mice; this contrasts with their L4 and L5 DRG localization in rats. The spared sural nerve, through which pain hypersensitivity is measured in behavioral studies, mostly projects into the L4 and L5 DRG. CONCLUSIONS: The complex regulation of Na(v)s, together with the anatomical rostral shift of the DRG harboring injured fibers in C57BL/6 J mice, emphasize that caution is necessary and preliminary anatomical experiments should be carried out for gene and protein expression studies after SNI in mouse strains.

Generation and validation of a normative, age-specific reference curve for lumbar spine trabecular bone score (TBS) in French women.

Age-related changes in lumbar vertebral microarchitecture are evaluated, as assessed by trabecular bone score (TBS), in a cohort of 5,942 French women. The magnitude of TBS decline between 45 and 85 years of age is piecewise linear in the spine and averaged 14.5 %. TBS decline rate increases after 65 years by 50 %. INTRODUCTION: This study aimed to evaluate age-related changes in lumbar vertebral microarchitecture, as assessed by TBS, in a cohort of French women aged 45-85 years. METHODS: An all-comers cohort of French Caucasian women was selected from two clinical centers. Data obtained from these centers were cross-calibrated for TBS and bone mineral density (BMD). BMD and TBS were evaluated at L1-L4 and for all lumbar vertebrae combined using GE-Lunar Prodigy densitometer images. Weight, height, and body mass index (BMI) also were determined. To validate our all-comers cohort, the BMD normative data of our cohort and French Prodigy data were compared. RESULTS: A cohort of 5,942 French women aged 45 to 85 years was created. Dual-energy X-ray absorptiometry normative data obtained for BMD from this cohort were not significantly different from French prodigy normative data (p = 0.15). TBS values at L1-L4 were poorly correlated with BMI (r = -0.17) and weight (r = -0.14) and not correlated with height. TBS values obtained for all lumbar vertebra combined (L1, L2, L3, L4) decreased with age. The magnitude of TBS decline at L1-L4 between 45 and 85 years of age was piecewise linear in the spine and averaged 14.5 %, but this rate increased after 65 years by 50 %. Similar results were obtained for other region of interest in the lumbar spine. As opposed to BMD, TBS was not affected by spinal osteoarthrosis. CONCLUSION: The age-specific reference curve for TBS generated here could therefore be used to help clinicians to improve osteoporosis patient management and to monitor microarchitectural changes related to treatment or other diseases in routine clinical practice.

Test-retest reliability of thermal quantitative sensory testing on two sites within the L5 dermatome of the lumbar spine and lower extremity.

INTRODUCTION: Quantitative sensory testing (QST) is widely used in human research to investigate the integrity of the sensory function in patients with pain of neuropathic origin, or other causes such as low back pain. Reliability of QST has been evaluated on both sides of the face, hands and feet as well as on the trunk (Th3-L3). In order to apply these tests on other body-parts such as the lower lumbar spine, it is important first to establish reliability on healthy individuals. The aim of this study was to investigate intra-rater reliability of thermal QST in healthy adults, on two sites within the L5 dermatome of the lumbar spine and lower extremity. METHODS: Test-retest reliability of thermal QST was determined at the L5-level of the lumbar spine and in the same dermatome on the lower extremity in 30 healthy persons under 40 years of age. Results were analyzed using descriptive statistics and intraclass correlation coefficient (ICC). Values were compared to normative data, using Z-transformation. RESULTS: Mean intraindividual differences were small for cold and warm detection thresholds but larger for pain thresholds. ICC values showed excellent reliability for warm detection and heat pain threshold, good-to-excellent reliability for cold pain threshold and fair-to-excellent reliability for cold detection threshold. ICC had large ranges of confidence interval (95%). CONCLUSION: In healthy adults, thermal QST on the lumbar spine and lower extremity demonstrated fair-to-excellent test-retest reliability.

Initiation de l'adhésion leucocytaire : rôle des fucosyltransférases et des ligands des sélectines

RESUME La dissémination extramédullaire des cellules blastiques est une complication majeure des leucémies myéloïdes (LMA) ou lymphoïdes aiguës (LLA). La migration des cellules blastiques dépend de mécanismes semblables à ceux qui régulent la migration des leucocytes dans un site d'inflammation. Parmi ceux-ci, les oligosaccharides fucosylés décorant les ligands des sélectines jouent un rôle clé en interagissant avec les sélectines. PSGL-1 (P-Selectin Glycoprotein Ligand-1) est une protéine de 240 kD, exprimée à la surface des leucocytes, permettant de soutenir le roulement leucocytaire sur les sélectines, le long de la paroi vasculaire. L'interaction de PSGL-1 avec les sélectines nécessite des modifications post-traductionnelles de type sialylation, sulfatation , N et 0-glycosylation. Parmi les enzymes impliqués, les α1,3-fucosyltransférases jouent un rôle important dans la biosynthèse d'oligosaccharides fucosylés, ligands des sélectines (sLex, Lex, VIM-2, CLA). Comme l'expression des α1,3-fucosyltransférases par les cellules blastiques leucémiques n'a pas été étudiée précédemment, nous l'avons recherchée dans 120 cas de leucémies aiguës. Les ARNm des FucT-IV et -VII ont été détectés, par RT-PCR, dans tous les cas testés. L'ARNm de la FucT-IX n'a été observé que dans 40% des leucémies aiguës (48/120). L'ARNm de la FucT-IX est détecté dans 65% des LMA (47/72) et, moins fréquemment, dans 26% des LLA (11/42). A noter que les cas de LLA exprimant la FucT-IX correspondent essentiellement à des LLA secondaires à la transformation d'une leucémie myéloïde chronique ou des LLA de la lignée B de type leucémie/lymphome de Burkitt. L'expression de PSGL-1 et des oligosaccharides fucosylés par les blastes varie significativement parmi les LMA et les LLA : Lex, VIM-2 et sLex étant exprimés plus fréquemment par les myéloblastes que par les lymphoblastes. Le rôle des FucT-IV, -VII et -IX dans la synthèse des Lex, VIM-2, CLA et sLex a été examiné en exprimant l'ADNc de chaque FucT dans des cellules CHO. L'immunophénotypisation des transfectants indique que la FucT-VII synthétise sLex et CLA, mais pas Lex et VIM-2. Lex et VIM-2 sont générés par la FucT-IV. La FucT-IX ne participe qu'à la synthèse de Lex, sa capacité de synthèse de VIM-2 dans les cellules CHO est très faible. Le rôle de la FucT-IX dans la régulation du roulement cellulaire dépendant des sélectines a été testé dans des conditions de flux. Les vitesses de roulement des cellules CHO co-exprimant la FucT-LX, la core-2 01,6-N-acetylglucosaminyltransferase et PSGL-1 sont très élevées sur la P-sélectine (médiane : 497.95 µm/s, n=96) alors qu'elles sont beaucoup plus lentes sur la E-sélectine (médiane 7 µm/s, n=64). Les recrutements sur la E-sélectine des cellules CHO-C2F9PSGL¬1 et des CHO-C2F7PSGL-1 sont similaires (moyenne ± SEM : 127.44 ± 4.38 vs. 151.16 ± 3.16 cellules/min/mm2, n=5). Celui des cellules CHO-C2F4PSGL-1 est par contre plus faible (54.20 ± 2.13 cellules/min/mm2, n=5). Ces résultats indiquent que la FucT-IX est impliquée dans la biosynthèse de Lex, VIM-2 et CLA et qu'elle régule l'interaction des cellules CHO avec la E-sélectine. Contrairement aux FucT-IV et -VII, la FucT-IX ne joue qu'un rôle mineur dans la régulation du roulement cellulaire sur la L- et la P-sélectine. L'expression fréquente de la FucT-IX par les myéloblastes suggère qu'elle pourrait participer avec les FucT-IV et -VII à la régulation de la migration cellulaire dépendant de la E-sélectine. Finalement, ce travail de thèse a été étendu à l'identification des protéines cytoplasmiques qui interagissent avec le domaine cytoplasmique de PSGL-1 et qui pourraient être impliquées dans la transmission de signaux intracellulaires. Les ligands intracellulaires de PSGL-1 seront identifiés par la technique du double hybride qui nous a déjà permis de confirmer que syk et la N-moésine se lient au domaine cytoplasmique de PSGL-1. Des ligands supplémentaires seront identifiés employant une librairie provenant des cellules souches hématopoïétiques comme proie. ABSTRACT Blast cell dissemination is a major complication of acute myeloblastic (AML) and lymphoblastic leukemia (ALL). Blast cell migration is dependent on mechanisms that are similar to those which regulate leukocyte migration into inflammatory lesions. Among them, fticosylated oligosaccharides that decorate selectin ligands play a key role by interacting with selectins. PSGL-1 (P-Selectin Glycoprotein Ligand-1) is a 240 kD glycoprotein constitutively expressed on leucocytes and which supports leukocyte rolling on selectins. PSGL-1 interaction with selectins is dependent on post-translational modifications such as sialylation, sulfation, N- and 0-glycosylation. Among the involved enzymes, the α1,3-fucosyltransferases (FucT) play a major role in generating cell surface glycoconjugates carrying fucosylated oligosaccharides which interact with selectins (sLex, Lex, VIM-2, CLA). Since no information is available on the expression of α1,3-fucosyltransferases by leukemic blast cells, we examined it in 120 cases of acute leukemia. FucT-IV and -VII mRNAs were detected, by RT-PCR, in all tested cases. In contrast, the presence of FucT-IX mRNA was shown in only 40% of patients with acute leukemia (48/120). FucT-IX mRNA was detected in 65% of AML (47/72) and, less frequently, in 26% of ALL (11/42). Importantly, all ALL cases expressing FucT-IX were either secondary leukemia resulting from the transformation of chronic myelocytic leukemia in acute lymphoblastic leukemia or mature B-ALL (FAB L3 subtype or Burkitt lymphoma/leukemia according to WHO classification). FucT-IX was not detected in precursor B or T-ALL. The expression of PSGL-1 and fucosylated epitopes was significantly different among AML and ALL, Lex, VIM-2 and sLex being more frequently expressed by myeloblasts than by lymphoblasts. The role of FucT-IV, -VII and -IX in the biosynthesis of Lex, VIM-2, CLA and sLex was examined by expressing the cDNA of each α1,3-FucT in CHO cells. Immunophenotypic analysis of CHO transfectants indicated that FucT-VII synthesizes sLex and CLA but not Lex or VIM-2. Lex and CLA were generated by both FucT-IV and -IX. FucT-IV and FucT-IX differed in their ability to synthesize VIM-2, FucT-IX being less efficient than FucT-IV. The role of FucT-IX in regulating selectin-dependent rolling was assessed under hydrodynamic flow conditions. P-selectin-dependent interactions were transient and occurred at high velocities (median: 497.95 1,µm/s, n=96). In contrast, much slower rolling velocities were observed on E-selectin (median: 7 µm/s, n=64). The recruitment of CHO-C2F9PSGL-1 and CHO-C2F7PSGL-1 cells was similar on E-selectin (mean ± SEM: 127.44 ± 4.38, n=5 vs 151.16 ± 3.16 cells/min/mm2, n=5). In the other hand, CHO-C2F4PSGL-1 cells were less efficiently recruited on E-selectin (54.20 ± 2.13 cells/min/mm2, n=5). This results indicate that FucT-IX is involved in the biosynthesis of Lex, VIM-2 and CLA and that it confers E-selectin binding activity to CHO cells. By contrast to FucT-IV and -VII, FucT-IX had a minor role in regulating P- and L-selectin-dependent rolling on CHO transfectants. The frequent expression of FucT-IX in myeloblasts suggests that it may participate with FucT-IV and -VII in regulating E-selectin-dependent cell migration into tissues. Finally, this thesis work was extended to the identification of the cytoplasmic proteins interacting with cytoplasmic domain of PSGL-1 that may be involved in transducing intracellular signals. We planned to identify these intracellular ligands of PSGL-1 by using the double hybrid technique and already confirmed that syk and N-moesin bind to the cytoplasmic domain of PSGL-1. Additional PSGL-1 ligands will be sought by the same technique using a CD34+ stem cell library as pray. RESUME DESTINE A UN LARGE PUBLIC : L'adhésion et la migration leucocytaire sont nécessaires à de nombreux processus cellulaires comme la régulation de l'hématopoïèse, mais aussi dans la pathogenèse de l'artériosclérose, des maladies inflammatoires et de la métastatisation des cellules cancéreuses. Les molécules impliquées constituent depuis peu des cibles pour la thérapie du cancer. La migration leucocytaire vers un site d'inflammation dépend de mécanismes complexes, se déroulant en plusieurs étapes, nécessitant l'interaction séquentielle de molécules d'adhésion leucocytaires et endothéliales. Ainsi, chronologiquement, suite à un stimulus inflammatoire, les leucocytes « roulent » sur les cellules endothéliales, sont activées, s'arrêtent et traversent la paroi endothéliale (diapédèse) pour migrer dans les tissus environnants inflammés selon un gradient chimiotactique. La première étape de roulement met en jeu deux molécules principales : PSGL-1 (P-Sélectine Glycoprotéine Ligand-1) du coté des leucocytes et les sélectines du coté de l'endothélium de la paroi vasculaire. L'interaction entre ces deux molécules nécessite des décorations de ces protéines par des sucres, des résidus sulfates et des acides sialiques. Le sucre essentiel à la liaison demeure le fucose qui est attaché aux protéines grâce à des enzymes de la famille des fucosyltransferases. Actuellement, neuf fucosyltransférases humaines ont été identifiées et désignées sous FucT-I à IX. La FucT-IX, dernière fucosyltransférase clonée, a un faible degré d'homologie avec les autres fucosyltransférases mais sa séquence est extrêmement conservée entre les espèces. Ceci traduit son importance par une forte résistance à la pression évolutive. L'examen de son expression au sein de 120 cas de leucémies aiguës a mis en évidence son comportement atypique. En effet, alors que les autres FucTs sont toujours présentes, la FucT¬IX ne s'exprime que dans un cas sur deux en moyenne avec une préférence plus importante pour les leucémies myéloïdes. Ainsi, une étude plus approfondie de cet enzyme à mis en évidence sa capacité à induire une interaction cellulaire plus spécifique de la E-sélectine. Elle décore non seulement des protéines de surface, mais aussi certainement les glycolipides constituant la membrane cellulaire.