15 research outputs found
Improving the potency of biomaterials for tissue growth
In recent years, it has been shown that synthetic biomaterials are not optimal supports for tissue
growth due to their lack of intrinsic biochemical signalling potential. To improve the biological potency
of these biomaterials and increase the reach of tissue engineering, key signalling proteins can be
attached. However, when these proteins are attached via non-specific conjugation chemistries, they
suffer a drastic loss of activity. There is therefore a need for site-selective approaches for protein-
biomaterial conjugation.
In this PhD, ligand-directed chemistry was studied to achieve this goal, with two new approaches to
achieve site selective modification of proteins without the need for protein engineering. The first
approach was based on using peptides as protein-binding ligands, while the second approach was
based on the use of 2-pyridinecarboxaldehydes as N-terminal targeting ligands.
This thesis will first introduce the peptide approach in Chapter 2, with details of the synthesis and
modification of the peptides required, then will focus in Chapter 3 on the binding of these modified
probes to their protein of interest. In Chapter 4, the use of these binding peptides for the formation
of ligand-directed probes will be discussed. Chapter 5 will develop similar chemistry on 2-
pyridinecarboxaldehydes, and finally Chapter 6 will describe the results using these two types of
probes for the modification of proteins.
Our results demonstrate that we can achieve site-selective modification of model proteins,
representing the first traceless modification of protein using pyridinium oxime and N-acyl-N-
sulphonamide (PyOx/NASA) system on a peptide in a traceless manner. With more optimization still
needed, these preliminary results are important for the biomedical field in which protein-biomaterial
conjugation is key for the formation of in-vitro tissue models for the study of various disease such as
myocardial infarction, diabetes, and osteoarthritis
Photochemical Methods for Peptide Macrocylization
Photochemical reactions have been the subject of renewed interest over the last two decades, leading to the development of many new diverse and powerful chemical transformations. More recently, these developments have been expanded to enable the photochemical macrocylization of peptides and small proteins. These constructs benefit from increased stability, structural rigidity, and biological potency over their linear counterparts, providing opportunities for improved therapeutic agents. In this review, we provide an overview of both the established and emerging methods for photochemical peptide macrocyclization, highlighting both the limitations and opportunities for further innovation in the field
Characterization of neutralizing antibodies reacting with the 213-224 amino-acid segment of human galectin-9.
Extra-cellular galectin-9 (gal-9) is an immuno-modulatory protein with predominant immunosuppressive effects. Inappropriate production of gal-9 has been reported in several human malignancies and viral diseases like nasopharyngeal, pancreatic and renal carcinomas, metastatic melanomas and chronic active viral hepatitis. Therefore therapeutic antibodies neutralizing extra-cellular gal-9 are expected to contribute to immune restoration in these pathological conditions. Two novel monoclonal antibodies targeting gal-9 -Gal-Nab 1 and 2-have been produced and characterized in this study. We report a protective effect of Gal-Nab1 and Gal-Nab2 on the apoptotic cell death induced by gal-9 in primary T cells. In addition, they inhibit late phenotypic changes observed in peripheral T cells that survive gal-9-induced apoptosis. Gal-Nab1 and Gal-Nab2 bind nearly identical, overlapping linear epitopes contained in the 213-224 amino-acid segments of gal-9. Nevertheless, they have some distinct functional characteristics suggesting that their three-dimensional epitopes are distinct. These differences are best demonstrated when gal-9 is applied on Jurkat cells where Gal-Nab1 is less efficient than Gal-Nab2 in the prevention of apoptotic cell death. In addition, Gal-Nab1 stimulates non-lethal phosphatidylserine translocation at the plasma membrane and calcium mobilization triggered by gal-9 in these cells. Both Gal-Nab1 and 2 cross-react with murine gal-9. They bind its natural as well as its recombinant form. This cross-species recognition will be an advantage for their assessment in pre-clinical tumor models
Conservative management or cesarean hysterectomy for placenta accreta spectrum: the PACCRETA prospective study
BackgroundPlacenta accreta spectrum is a life-threatening condition that has increased dramatically in recent decades along with cesarean rates worldwide. Cesarean hysterectomy is widely practiced in women with placenta accreta spectrum; however, the maternal outcomes after cesarean hysterectomy have not been thoroughly compared with the maternal outcomes after alternative approaches, such as conservative management.ObjectiveThis study aimed to compare the severe maternal outcomes between women with placenta accreta spectrum treated with cesarean hysterectomy and those treated with conservative management (leaving the placenta in situ).Study DesignFrom a source population of 520,114 deliveries in 176 hospitals (PACCRETA study), we designed an observational cohort of women with placenta accreta spectrum who had either a cesarean hysterectomy or a conservative management (the placenta left in situ) during cesarean delivery. Clinicians prospectively identified women meeting the inclusion criteria and included them at delivery. Data collection started only after the women had received information and agreed to participate in the study in the immediate postpartum period. The primary outcome was the transfusion of >4 units of packed red blood cells within 6 months after delivery. Secondary outcomes were other maternal complications within 6 months. We used propensity score weighting to account for potential indication bias.ResultsHere, 86 women had conservative management and 62 women had cesarean hysterectomy for placenta accreta spectrum during cesarean delivery. The primary outcome occurred in 14 of 86 women in the conservative management group (16.3%) and 36 of 61 (59.0%) in the cesarean hysterectomy group (risk ratio in propensity score weighted model, 0.29; 95% confidence interval, 0.19â0.45). The rates of hysterectomy, total estimated blood loss exceeding 3000 mL, any blood product transfusion, adjacent organ injury, and nonpostpartum hemorrhage-related severe maternal morbidity were lower with conservative management than with cesarean hysterectomy (all adjusted, Pâ€.02); but, the rates of arterial embolization, endometritis, and readmission within 6 months of discharge were higher with conservative management than with cesarean hysterectomy.ConclusionAmong women with placenta accreta spectrum who underwent cesarean delivery, conservative management was associated with a lower risk of transfusion of >4 units of packed red blood cells within 6 months than cesarean hysterectomy
Morphology and genomic hallmarks of breast tumours developed by ATM deleterious variant carriers
Abstract Background The ataxia telangiectasia mutated (ATM) gene is a moderate-risk breast cancer susceptibility gene; germline loss-of-function variants are found in up to 3% of hereditary breast and ovarian cancer (HBOC) families who undergo genetic testing. So far, no clear histopathological and molecular features of breast tumours occurring in ATM deleterious variant carriers have been described, but identification of an ATM-associated tumour signature may help in patient management. Methods To characterise hallmarks of ATM-associated tumours, we performed systematic pathology review of tumours from 21 participants from ataxia-telangiectasia families and 18 participants from HBOC families, as well as copy number profiling on a subset of 23 tumours. Morphology of ATM-associated tumours was compared with that of 599 patients with no BRCA1 and BRCA2 mutations from a hospital-based series, as well as with data from The Cancer Genome Atlas. Absolute copy number and loss of heterozygosity (LOH) profiles were obtained from the OncoScan SNP array. In addition, we performed whole-genome sequencing on four tumours from ATM loss-of-function variant carriers with available frozen material. Results We found that ATM-associated tumours belong mostly to the luminal B subtype, are tetraploid and show LOH at the ATM locus at 11q22â23. Unlike tumours in which BRCA1 or BRCA2 is inactivated, tumours arising in ATM deleterious variant carriers are not associated with increased large-scale genomic instability as measured by the large-scale state transitions signature. Losses at 13q14.11-q14.3, 17p13.2-p12, 21p11.2-p11.1 and 22q11.23 were observed. Somatic alterations at these loci may therefore represent biomarkers for ATM testing and harbour driver mutations in potentially âdruggableâ genes that would allow patients to be directed towards tailored therapeutic strategies. Conclusions Although ATM is involved in the DNA damage response, ATM-associated tumours are distinct from BRCA1-associated tumours in terms of morphological characteristics and genomic alterations, and they are also distinguishable from sporadic breast tumours, thus opening up the possibility to identify ATM variant carriers outside the ataxia-telangiectasia disorder and direct them towards effective cancer risk management and therapeutic strategies
Services culturels et récréatifs
Les Ă©cosystĂšmes agricoles sont lâun des six volets de lâEvaluation française des Ă©cosystĂšmes et des services Ă©cosystĂ©miques (EFESE), programme lancĂ© en 2012 par le MinistĂšre en charge de lâEnvironnement pour apporter des connaissances sur lâĂ©tat actuel et lâutilisation durable des Ă©cosystĂšmes (voir encadrĂ© 2). En 2014, le MinistĂšre de lâEnvironnement a sollicitĂ© lâInra pour prendre en charge le volet relatif aux Ă©cosystĂšmes agricoles. Le programme fĂ©dĂ©rateur de recherche EcoSerV (Services rendus par les Ă©cosystĂšmes), lancĂ© par lâInra en 2013, a Ă©galement soutenu cette Ă©tude quâil va ensuite complĂ©ter et Ă©tendre. LâĂ©cosystĂšme agricole, vu comme lâensemble des parcelles dĂ©diĂ©es Ă la production de biomasse agricole, est configurĂ© et gĂ©rĂ© par lâagriculteur qui combine, dans ses pratiques de production, processus Ă©cologiques et apports dâintrants exogĂšnes. Lâun des enjeux forts associĂ©s Ă lâanalyse des services Ă©cosystĂ©miques est la conception de systĂšmes de production reposant sur la valorisation de ces services, donc peu consommateurs en intrants exogĂšnes et rĂ©pondant aux enjeux de sociĂ©tĂ© tels que la conservation de la biodiversitĂ© ou la limitation des impacts environnementaux
Biens produits par l'Ă©cosystĂšme
Dans EFESE-Ă©cosystĂšmes agricoles, la production agricole de biomasse vĂ©gĂ©tale nâest pas conceptualisĂ©e comme un SE dâapprovisionnement mais comme un processus de production de biens agricoles (cf. section 3.1). Le niveau de production agricole rĂ©sulte des interactions entre les SE de rĂ©gulation dont bĂ©nĂ©ficie lâagriculteur, appelĂ©s « SE intrants » ci-aprĂšs, et des apports dâintrants exogĂšnes (ex. Ă©nergie du travail du sol, fertilisants et amendements, eau dâirrigation, produits phytosanitaires). DiffĂ©rents modes de production de biens vĂ©gĂ©taux peuvent ĂȘtre distinguĂ©s suivant la part relative de la production agricole permise par les SE de rĂ©gulation pour un niveau de production donnĂ©e. Par exemple, il est possible de distinguer les systĂšmes de production « conventionnels » dont le niveau de production agricole est fortement basĂ© sur les intrants exogĂšnes, des systĂšmes de production, souvent qualifiĂ©s dâ« agroĂ©cologiques », dont le niveau de production agricole est fortement dĂ©terminĂ© par les SE dit « intrants » (Bommarco et al., 2013; Duru et al., 2015a; Gliessman, 2007; Therond et al., 2017)
: Rapport scientifique de l'étude réalisée par l'INRA - Novembre 2017
Lâambition de lâĂ©tude Inra "EFESE-EA" est de dĂ©crire les mĂ©canismes et dĂ©terminants de la fourniture des services Ă©cosystĂ©miques par les Ă©cosystĂšmes agricoles sur la base d'une revue des connaissances existantes, et de procĂ©der Ă leur Ă©valuation Ă lâĂ©chelle nationale sur la base dâindicateurs dĂ©finis dans le cadre de lâĂ©tude. Lâorganisation du travail, telle que prĂ©vue en dĂ©but dâĂ©tude, se voulait sĂ©quentielle : (1) identification et spĂ©cification biophysiques dâune liste de biens agricoles et services Ă©cosystĂ©miques ; (2) Ă©valuation biophysique : quantification du niveau de fourniture des biens et services identifiĂ©s Ă lâĂ©tape (1) (3) Ă©valuation Ă©conomique : quantification de la valeur Ă©conomique des services (le plus souvent dans une unitĂ© monĂ©taire) Dans le temps imparti Ă lâĂ©tude, le collectif dâexperts a donnĂ© la prioritĂ© aux volets biophysiques (1) et (2) afin : - dâinstruire de façon robuste la conceptualisation des biens et services (volet 1) : ce travail constitue un front de recherche actuel, associĂ© Ă une littĂ©rature acadĂ©mique abondante mais parfois non stabilisĂ©e, que le collectif dâexperts sâest attachĂ© Ă analyser de façon Ă proposer des choix de conceptualisation argumentĂ©s ; - de pousser au maximum lâexercice dâĂ©valuation biophysique (volet 2) dans le cadre de la demande initiale formulĂ©e par le MEEM : cartographier la production dâun large panel de biens agricoles et les SE rendus par les Ă©cosystĂšmes agricoles Ă la rĂ©solution spatiale la plus fine possible, et Ă lâĂ©chelle France entiĂšre. A noter que le prĂ©sent exercice ne constituant pas un projet de recherche mais bien une Ă©tude institutionnelle Inra (au sens des procĂ©dures DEPE), lâensemble des Ă©valuations dĂ©veloppĂ©es dans le prĂ©sent rapport est rĂ©alisĂ©e Ă partir de donnĂ©es existantes, aucun travail dâexpĂ©rimentation visant Ă acquĂ©rir de nouvelles donnĂ©es de terrain nâayant Ă©tĂ© conduit. Il rĂ©sulte de ce choix de priorisation que : - le volet dâĂ©valuation Ă©conomique (3) est initiĂ© pour quelques SE mais peu dĂ©veloppĂ© en comparaison des volets (1) et (2) ; - tout en veillant Ă Ă©laborer des mĂ©thodologies dâĂ©valuation biophysiques traçables et robustes, les experts ont pris le parti de proposer des mĂ©thodologies plus exploratoires pour quelques SE pour lesquels les donnĂ©es actuelles ne permettent pas dâĂ©valuer directement le niveau de fourniture Ă lâĂ©chelle France entiĂšre : dans ces cas particuliers (signalĂ©s explicitement dans les sections du rapport dont ils font lâobjet), les mĂ©thodologies ont Ă©tĂ© mises en Ćuvre jusquâĂ la rĂ©alisation des cartographies dans le but de donner Ă voir le potentiel quâoffrent ces mĂ©thodologies et la nature des rĂ©sultats quâelles peuvent produire sous condition de leur validation France entiĂšre, plutĂŽt que dans le but dâinterprĂ©ter pour eux-mĂȘmes les rĂ©sultats obtenus. Les experts se sont alors particuliĂšrement attachĂ©s Ă relativiser les rĂ©sultats quantitatifs ainsi produits, et Ă accompagner les cartographies dâun descriptif dĂ©taillĂ© des protocoles de validation quâil faudrait mettre en Ćuvre dans les suites de lâĂ©tude pour stabiliser et valider ces mĂ©thodologies exploratoires. Ce parti pris du groupe de travail EFESE-Ă©cosystĂšmes agricoles est compatible avec lâobjectif poursuivi dans le programme EFESE, qui se donne pour objectif de produire un guide mĂ©thodologique pour lâĂ©valuation des biens et SE en en pointant les limites, difficultĂ©s, prĂ©cautions et amĂ©liorations possibles associĂ©es Ă chacune des pistes avancĂ©es