Carriers and Antigens: New Developments in Glycoconjugate Vaccines.

Glycoconjugate vaccines have proven their worth in the protection and prevention of infectious diseases. The introduction of the type b vaccine is the prime example, followed by other glycoconjugate vaccines. Glycoconjugate vaccines consist of two components: the carrier protein and the carbohydrate antigen.

The First-in-Human Synthetic Glycan-Based Conjugate Vaccine Candidate against .

, the causative agent of shigellosis, is among the main causes of diarrheal diseases with still a high morbidity in low-income countries. Relying on chemical synthesis, we implemented a multidisciplinary strategy to design SF2a-TT15, an original glycoconjugate vaccine candidate targeting 2a (SF2a). Whereas the SF2a O-antigen features nonstoichiometric O-acetylation, SF2a-TT15 is made of a synthetic 15mer oligosaccharide, corresponding to three non-O-acetylated repeats, linked at its reducing end to tetanus toxoid by means of a thiol-maleimide spacer.

Immunochemical and biophysical characterization of inactivated Sabin poliovirus products: Insights into rapid quality assessment tools.

The aim of this study was to demonstrate the strength of combining immunochemical and biophysical analysis tools for assessing the quality of Sabin inactivated poliovirus vaccine (Sabin-IPV) bulk products. We assessed Sabin-IPV serotypes 1, 2 and 3 from six different manufacturers and evaluated their comparability through biosensor analysis and biophysical characterization methods, including tryptophan fluorescence and asymmetrical flow field-flow fractionation - multi-angle light scattering analysis. These methods enabled us to assess antigenic as well as conformational and structural integrity profiles, respectively.

A Synthetic Carbohydrate Conjugate Vaccine Candidate against Shigellosis: Improved Bioconjugation and Impact of Alum on Immunogenicity.

Conjugation chemistry is among the most important parameters governing the efficacy of glycoconjugate vaccines. High robustness is required to ensure high yields and batch to batch reproducibility. Herein, we have established a robust bioconjugation protocol based on the thiol-maleimide addition.

HPAEC-PAD quantification of Haemophilus influenzae type b polysaccharide in upstream and downstream samples.

Due to the rapidly increasing introduction of Haemophilus influenzae type b (Hib) and other conjugate vaccines worldwide during the last decade, reliable and robust analytical methods are needed for the quantitative monitoring of intermediate samples generated during fermentation (upstream processing, USP) and purification (downstream processing, DSP) of polysaccharide vaccine components. This study describes the quantitative characterization of in-process control (IPC) samples generated during the fermentation and purification of the capsular polysaccharide (CPS), polyribosyl-ribitol-phosphate (PRP), derived from Hib. Reliable quantitative methods are necessary for all stages of production; otherwise accurate process monitoring and validation is not possible.

Physicochemical and immunochemical assays for monitoring consistent production of tetanus toxoid.

The detoxification of tetanus toxin by formaldehyde is a crucial step in the production of tetanus toxoid. The inactivation results in chemically modified proteins and it determines largely the ultimate efficacy and safety of the vaccine. Currently, the quality of tetanus toxoid lots is evaluated in potency and safety tests performed in animals.

HPAEC-PAD method for the analysis of alkaline hydrolyzates of Haemophilus influenzae type b capsular polysaccharide.

A gradient method has been devised for the rapid analysis of alkaline hydrolyzates of Haemophilus influenzae type b (Hib) capsular polysaccharide-based vaccines by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). As compared with published procedures, peak shape and sensitivity were significantly improved with this approach, analysis time was short and there was little interference from impurities. The limits of detection and quantification were established with a purified reference polysaccharide.

Which postures are most suitable in assessing spinal fusion using radiostereometric analysis?

Background: Up to now, plain radiographs are not well suited to assess spinal fusion. Radiostereometric analysis performed for two postures may deliver more reliable results. However, it is unknown, which postures are most suitable for this procedure.

Contour propagation in MRI-guided radiotherapy treatment of cervical cancer: the accuracy of rigid, non-rigid and semi-automatic registrations.

External beam radiation treatment for patients with cervical cancer is hindered by the relatively large motion of the target volume. A hybrid MRI-accelerator system makes it possible to acquire online MR images during treatment in order to correct for motion and deformation. To fully benefit from such a system, online delineation of the target volumes is necessary.

Intrafraction motion in patients with cervical cancer: The benefit of soft tissue registration using MRI.

Background And Purpose: During radiation delivery, target volumes change their position and shape due to intrafraction motion. The extent of these changes and the capability to correct for them will contribute to the benefit of an MRI-accelerator in terms of PTV margin reduction. Therefore, we investigated the primary CTV motion within a typical IMRT delivery time for cervical cancer patients for various correction techniques: no registration, rigid bony anatomy registration, and rigid soft tissue registration.

Integrating a 1.5 T MRI scanner with a 6 MV accelerator: proof of concept.

At the UMC Utrecht, The Netherlands, we have constructed a prototype MRI accelerator. The prototype is a modified 6 MV Elekta (Crawley, UK) accelerator next to a modified 1.5 T Philips Achieva (Best, The Netherlands) MRI system.

An automatic system for in vitro cell migration studies.

This paper describes a system for in vitro cell migration analysis. Adult neural stem/progenitor cells are studied using time-lapse bright-field microscopy and thereafter stained immunohistochemically to find and distinguish undifferentiated glial progenitor cells and cells having differentiated into type-1 or type-2 astrocytes. The cells are automatically segmented and tracked through the time-lapse sequence.

Variation in target and rectum dose due to prostate deformation: an assessment by repeated MR imaging and treatment planning.

In daily clinical practice, implanted fiducial markers are used to correct for prostate motion, but not for prostate deformation. The aim of this study is to investigate the variation in target and rectum dose due to the deformation of the prostate gland (without seminal vesicles). Therefore, we performed five to six MRI scans of eight healthy volunteers that exhibited large variation in rectal volume and thus prostate deformation.

A novel method for comparing 3D target volume delineations in radiotherapy.

When comparing delineations it is often useful to obtain a local measure of distance between the volume surfaces. Commonly used methods for analysing local distance exhibit fundamental drawbacks which may cause overestimation of the distance or lead to asymmetry in the measure. This paper describes a new method that aims to solve these problems.

Dissimilar or orthogonal reversed-phase chromatographic systems: A comparison of selection techniques.

Developing an analytical separation procedure for an unknown mixture is a challenging issue. An important example is the separation and quantification of a new drug and its impurities. One approach to start method development is the screening of the mixture on dissimilar chromatographic systems, i.

MRI/linac integration.

Purpose/objectives: In radiotherapy the healthy tissue involvement still poses serious dose limitations. This results in sub-optimal tumour dose and complications. Daily image guided radiotherapy (IGRT) is the key development in radiation oncology to solve this problem.

Review on modelling aspects in reversed-phase liquid chromatographic quantitative structure-retention relationships.

In the literature an increasing interest in quantitative structure-retention relationships (QSRR) can be observed. After a short introduction on QSRR and other strategies proposed to deal with the starting point selection problem prior to method development in reversed-phase liquid chromatography, a number of interesting papers is reviewed, dealing with QSRR models for reversed-phase liquid chromatography. The main focus in this review paper is put on the different modelling methodologies applied and the molecular descriptors used in the QSRR approaches.

The evaluation of two-step multivariate adaptive regression splines for chromatographic retention prediction of peptides.

Both the multivariate adaptive regression splines (MARS) and the two-step MARS (TMARS) methodologies were applied in a quantitative structure-retention relationship (QSRR) context. For seven RPLC systems, QSRR models were built that describe the retention times of a set of peptides using a large set of molecular descriptors as potential predictor variables. The use of QSRR models for chromatographic retention prediction of peptides may be valuable in proteomic research to improve the number of correct peptide identifications.

Retention prediction of peptides based on uninformative variable elimination by partial least squares.

A quantitative structure-retention relationship analysis was performed on the chromatographic retention data of 90 peptides, measured by gradient elution reversed-phase liquid chromatography, and a large set of molecular descriptors computed for each peptide. Such approach may be useful in proteomics research in order to improve the correct identification of peptides. A principal component analysis on the set of 1726 molecular descriptors reveals a high information overlap in the descriptor space.

Evaluation of chemometric techniques to select orthogonal chromatographic systems.

Several chemometric techniques were compared for their performance to determine the orthogonality and similarity between chromatographic systems. Pearson's correlation coefficient (r) based color maps earlier were used to indicate selectivity differences between systems. These maps, in which the systems were ranked according to decreasing or increasing dissimilarities observed in the weighted-average-linkage dendrogram, were now applied as reference method.

Selection of orthogonal reversed-phase HPLC systems by univariate and auto-associative multivariate regression trees.

In order to select chromatographic starting conditions to be optimized during further method development of the separation of a given mixture, so-called generic orthogonal chromatographic systems could be explored in parallel. In this paper the use of univariate and multivariate regression trees (MRT) was studied to define the most orthogonal subset from a given set of chromatographic systems. Two data sets were considered, which contain the retention data of 68 structurally diversive drugs on sets of 32 and 38 chromatographic systems, respectively.

Prediction of gastro-intestinal absorption using multivariate adaptive regression splines.

Multivariate adaptive regression splines (MARS) and a derived method two-step MARS (TMARS) were used for modelling the gastro-intestinal absorption of 140 drug-like molecules. The published absorption values for these molecules were used as response variable and calculated molecular descriptors as potential explanatory variables. Both methods were compared and their potential use in quantitative structure-activity relationship (QSAR) context evaluated.

Multivariate adaptive regression splines (MARS) in chromatographic quantitative structure-retention relationship studies.

The multivariate adaptive regression splines (MARS) methodology was applied to build quantitative structure-retention relationships (QSRRs). The response (dependent variable) in the MARS models consisted of the logarithms of the extrapolated retention factors (log k(w)) of 83 structurally diverse drugs on a Unisphere PBD column, using isocratic elutions at pH 11.7.

Classification and regression tree analysis for molecular descriptor selection and retention prediction in chromatographic quantitative structure-retention relationship studies.

The use of the classification and regression tree (CART) methodology was studied in a quantitative structure-retention relationship (QSRR) context on a data set consisting of the retentions of 83 structurally diverse drugs on a Unisphere PBD column, using isocratic elutions at pH 11.7. The response (dependent variable) in the tree models consisted of the predicted rention factor (log kw) of the solutes, while a set of 266 molecular descriptors was used as explanatory variables in the tree building.