Combined chemical synthesis and tailored enzymatic elongation provide fully synthetic and conjugation-ready Neisseria meningitidis serogroup X vaccine antigens

Studies on the polymerization mode of Neisseria meningitidis serogroup X capsular polymerase CsxA recently identified a truncated construct that can be immobilized and used for length controlled on-column production of oligosaccharides. Here, we combined the use of a synthetic acceptor bearing an appendix for carrier protein conjugation and the on-column process to a novel chemo-enzymatic strategy. After protein coupling of the size optimized oligosaccharide produced by the one-pot elongation procedure, we obtained a more homogeneous glycoconjugate compared to the one previously described starting from the natural polysaccharide. Mice immunized with the conjugated fully synthetic oligomer elicited functional antibodies comparable to controls immunized with the current benchmark MenX glycoconjugates prepared from the natural capsule polymer or from fragments of it enzymatically elongated. This pathogen-free technology allows the fast total in vitro construction of predefined bacterial polysaccharide fragments. Compared to conventional synthetic protocols, the procedure is more expeditious and drastically reduces the number of purification steps to achieve the oligomers. Furthermore, the presence of a linker for conjugation in the synthetic acceptor minimizes manipulations on the enzymatically produced glycan prior to protein conjugation. This approach enriches the methods for fast construction of complex bacterial carbohydrates

Conformational and Immunogenicity Studies of the Shigella flexneri Serogroup 6 O-Antigen: The Effect of O-Acetylation.

The pathogenic bacterium Shigella is a leading cause of diarrheal disease and mortality, disproportionately affecting young children in low-income countries. The increasing prevalence of antibiotic resistance in Shigella necessitates an effective vaccine, for which the bacterial lipopolysaccharide O-antigen is the primary target. S. flexneri serotype 6 has been proposed as a multivalent vaccine component to ensure broad protection against Shigella. We have previously explored the conformations of S. flexneri O-antigens from serogroups Y, 2, 3, and 5 that share a common saccharide backbone (serotype Y). Here we consider serogroup 6, which is of particular interest because of an altered backbone repeat unit with non-stoichiometric O-acetylation, the antigenic and immunogenic importance of which have yet to be established. Our simulations show significant conformational changes in serogroup 6 relative to the serotype Y backbone. We further find that O-acetylation has little effect on conformation and hence may not be essential for the antigenicity of serotype 6. This is corroborated by an in vivo study in mice, using Generalized Modules for Membrane Antigens (GMMA) as O-antigen delivery systems, that shows that O-acetylation does not have an impact on the immune response elicited by the S. flexneri serotype 6 O-antigen

Regioselective Glycosylation Strategies for the Synthesis of Group Ia and Ib Streptococcus Related Glycans Enable Elucidating Unique Conformations of the Capsular Polysaccharides

Group B Streptococcus serotypes Ia and Ib capsular polysaccharides are key targets for vaccine development. In spite of their immunospecifity these polysaccharides share high structural similarity. Both are composed of the same monosaccharide residues and differ only in the connection of the Neu5Acα2-3Gal side chain to the GlcNAc unit, which is a β1-4 linkage in serotype Ia and a β1-3 linkage in serotype Ib. We described development of efficient regioselective routes for GlcNAcβ1-3[Glcβ1-4)]Gal synthons giving access to different GBS Ia and Ib repeating unit frameshifts. These glycans were used to probe the conformation and molecular dynamics of the two polysaccharides, highlighting the different presentation of the protruding Neu5Acα2-3Gal moieties on the polysaccharide backbones and a higher flexibility of Ib polymer compared to Ia which can impact epitope exposure.Bio-organic Synthesi

GMMA as an alternative carrier for a glycoconjugate vaccine against Group A streptococcus

Group A Streptococcus (GAS) causes about 500,000 annual deaths globally, and no vaccines are currently available. The Group A Carbohydrate (GAC), conserved across all GAS serotypes, conjugated to an appropriate carrier protein, represents a promising vaccine candidate. Here, we explored the possibility to use Generalized Modules for Membrane Antigens (GMMA) as an alternative carrier system for GAC, exploiting their intrinsic adjuvant properties. Immunogenicity of GAC-GMMA conjugate was evaluated in different animal species in comparison to GAC-CRM197; and the two conjugates were also compared from a techno-economic point of view. GMMA proved to be a good alternative carrier for GAC, resulting in a higher immune response compared to CRM197 in different mice strains, as verified by ELISA and FACS analyses. Differently from CRM197, GMMA induced significant levels of anti-GAC IgG titers in mice also in the absence of Alhydrogel. In rabbits, a difference in the immune response could not be appreciated; however, antibodies from GAC-GMMA-immunized animals showed higher affinity toward purified GAC antigen compared to those elicited by GAC-CRM197. In addition, the GAC-GMMA production process proved to be more cost-effective, making this conjugate particularly attractive for low- and middle-income countries, where this pathogen has a huge burden

Comparaison entre arcthérapie volumétrique modulée et tomothérapie pour le cancer du col utérin, avec irradiation lomboaortique

International audienceObjectif de l’étudeLa radiothérapie conformationnelle avec modulation d’intensité (RCMI) pour les cancers du col utérin a prouvé sa supériorité dosimétrique en termes de toxicité digestive, comparativement à la radiothérapie conformationnelle non modulée. L’arcthérapie volumétrique modulée a montré son intérêt dosimétrique comparativement à la RCMI à faisceaux statiques. L’objectif de notre étude était de comparer arcthérapie volumétrique modulée et tomothérapie pour des cancers du col utérin avec irradiation lomboartique.Patientes et méthodesLes dosimétries à 45 Gy de dix patientes ont été comparées entre les deux techniques (arcthérapie volumétrique modulée et tomothérapie) ainsi qu’avec la radiothérapie conformationnelle non modulée, avec recueil de la dose reçue par les volumes cibles prévisionnels, les reins, l’intestin, le rectum, la vessie, la moelle osseuse et la moelle épinière, ainsi que la dose intégrale.RésultatsUne différence significative a été observée en faveur de l’arcthérapie volumétrique modulée et de la tomothérapie sur la radiothérapie conformationnelle non modulée pour l’épargne intestinale (volumes recevant respectivement 20, 30 et 45 Gy : V20 Gy, V30 Gy et V45 Gy), rectale (V30 Gy et V45 Gy), vésicale (V30 Gy et V45 Gy) et rénale (volume recevant 12 Gy [V12 Gy], dose moyenne, V20 Gy). Les volumes recevant 20, 30 et 45 Gy étaient significativement plus grands avec la radiothérapie conformationnelle non modulée qu’avec l’arcthérapie volumétrique modulée et la tomothérapie. La différence était en faveur de la tomothérapie comparativement à l’arcthérapie volumétrique modulée pour le V12 Gy des reins et le V45 Gy de la vessie.ConclusionCette étude confirme l’intérêt des techniques d’arcthérapie volumétrique modulée et de tomothérapie pour l’irradiation pelvienne et lomboaortique des cancers du col comparativement à la radiothérapie conformationnelle non modulée. Il y avait peu de différence entre l’arcthérapie volumétrique modulée et la tomothérapie, en dehors d’une meilleure épargne rénale avec la tomothérapie, ce qui peut être intéressant pour des patientes recevant des chimiothérapies néphrotoxiques

: End of the commercialisation of 192Ir wires in France: Proposals of the groupe de Curiethérapie de la SFRO

International audienceIn 2014, the production of iridium 192 wires in France ended. Thus brachytherapy departments had to move to high-dose rate and pulsed-dose rate afterloading techniques. Most of them had already made this migration for some indications, based on the habits and investments. The brachytherapy group organised meetings and opened discussions to share the clinical knowledge and answer to the questions raised by this migration. This made it possible to resolve and describe quite all the clinical and technical cases of brachytherapy. The development of high technology included the use of 3D dosimetry and optimisation of dose distribution and fractionation. The teaching policy of new technologies contributes to the improvement of treatment quality. Last but not least, a better reimbursement of brachytherapy is necessary and currently negotiated.L’arrêt de la commercialisation des fils d’iridium 192 est intervenu au début de l’année 2014 en France. Cela a obligé les services de curiethérapie à reporter toutes leurs indications en utilisant des techniques avec projecteurs de source de débit pulsé ou de haut débit de dose. La plupart avaient déjà effectué cette migration pour une partie de leurs indications, selon les habitudes et les moyens. Les discussions et réunions organisées autour du groupe de curiethérapie ont permis un échange fructueux et la complémentarité des pratiques permet de répondre à la demande. La conversion est donc possible et effectuée pour quasiment toutes les indications habituelles de curiethérapie de bas débit de dose. Ce changement de pratiques oblige à la généralisation de la curiethérapie de haute technicité, fondée sur la dosimétrie tridimensionnelle et l’optimisation de la distribution de dose et la prescription du débit de dose ou du fractionnement. La poursuite de l’enseignement de ces techniques contribue également au maintien et à l’amélioration de la qualité. Une meilleure valorisation de cette curiethérapie est nécessaire et actuellement en cours de discussion

Clinical predictors of fracture in patients with shoulder dislocation: systematic review of diagnostic test accuracy studies

BACKGROUND: Pre-reduction radiographs are conventionally used to exclude fracture before attempts to reduce a dislocated shoulder in the Emergency Department. However, this step increases cost, exposes patients to ionising radiation, and might delay closed reduction. Some studies have suggested that pre-reduction imaging may be omitted for a sub-group of patients with shoulder dislocations. OBJECTIVES: To determine whether clinical predictors can identify patients that might safely undergo closed reduction of a dislocated shoulder without pre-reduction radiographs. >METHODS: A systematic review and meta-analysis of diagnostic test accuracy studies that have evaluated the ability of clinical features to identify concomitant fractures in patients with shoulder dislocation. The search was updated to 23rd June 2022 and language limits were not applied. All fractures were included except for Hill-Sachs lesions. Quality assessment was undertaken using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Data were pooled and meta-analysed by fitting univariate random effects and multi-level mixed effects logistic regression models. RESULTS: Eight studies reported data on 2,087 shoulder dislocations and 343 concomitant fractures. The most important potential sources of bias were unclear blinding of those undertaking the clinical (6/8 studies) and radiographic (3/8 studies) assessment. The prevalence of concomitant fracture was 17.5%. The most accurate clinical predictors were age >40 (LR+ 1.8 [95% CI 1.5-2.1]; LR- 0.4 [0.2-0.6]), female sex (LR+ 2.0 [1.6-2.4], LR- 0.7 [0.6-0.8]), first time dislocation (LR+ 1.7 [1.4-2.0]; LR-0.2 [0.1-0.5]), and presence of humeral ecchymosis (LR+ 3.0-5.7; LR- 0.8-1.1). The most important mechanisms of injury were: high-energy mechanism fall (LR+ 2.0-9.8, LR-0.4-0.8), fall >1 flight of stairs (LR+ 3.8 [95% CI 0.6-13.1]; LR- 1.0 [95% CI 0.9-1.0]), and motor vehicle collision (LR+ 2.3 [0.5-4.0]; LR- 0.9 [0.9-1.0]). The Quebec Rule had a sensitivity of 92.2% (95% CI 54.6-99.2%) and specificity (33.3%, 23.1-45.3%) but the Fresno-Quebec rule identified all clinically important fractures across two studies: sensitivity 100% (95% CI 89-100%) in the derivation dataset and 100% (90-100%) in the validation study. The specificity ranged from 34% (95% CI 28-41%) in the derivation dataset to 24% (16-33%) in the validation study. CONCLUSION: Clinical prediction rules may have a role in supporting shared decision making after shoulder dislocation, particularly in the pre-hospital and remote environments when delay to imaging is anticipated.</p

Implantation of fiducial markers in the liver for stereotactic body radiation therapy: Feasibility and results

International audiencePurposeRobotic stereotactic body radiation therapy (SBRT) for the treatment of hepatocellular carcinoma requires the perilesional implant of gold fiducial markers for detection by scopy. The purpose of this study is to determine whether the implant of gold fiducial markers is still possible and, if so, with which imaging technique and with what results.Materials and methodsThis is a prospective study based on the implant of fiducial markers in the liver in our department for a treatment by SBRT for a hepatocellular carcinoma in 38 patients (49 lesions to treat) over a period of one year. As the first choice, it consisted of sonographic guidance and, if not possible, CT-scan guidance was used.ResultsThe mean number of fiducial markers implanted per procedure was 2.68(± 0.61) with almost exclusive sonographic guidance (36 out of 38 patients or 95% of the patients). The mean distance between the markers and the lesion was 32 mm (± 11 mm) and that between the markers was 17 mm (± 7 mm).ConclusionSBRT is being evaluated for the treatment of liver lesions. The radiologist has an important role to play since the implant of fiducial markers in the liver is indispensable. It is almost always possible with sonographic guidance, including for lesions not accessible to microbiopsies, a treatment by radiofrequency or for lesions poorly individualisable by sonography or CT-scan