Continuous suspension cell culture monitoring in bioreactors using quantitative imaging

Monitoring of suspension cell cultures often relies on sampling followed by a staining procedure. Estimations of cell count and cell viability are traditionally performed once a day using Trypan-Blue cell exclusion as a method of choice. Stained samples are destroyed afterwards creating toxic waste. Sampling a bioreactor and counting cells involve manual operations and weekend work is regularly needed. Differential Digital Holographic Microscopy (DDHM) is a new quantitative imaging technique that allows cell counting as well as cell viability monitoring in a continuous, label-free set-up. No need for sampling (thus eliminating the risk of contamination), staining and waiting for results generated by an off-line counter: results are available in nearly real-time during the whole run. Compared to classical light microscopy, Differential Digital Holographic Microscopy offers: The ability to refocus images post acquisition The collection of quantitative phase information (optical density), covering the shape and density of an object. This quantitative phase parameter (not captured by the human eye) is the key advantage in numerous applications developed at OVIZIO. DDHM helps the operator to continuously track total cell density and cell viability, while the OsOne software plots the cell growth curve, live on the screen. Moreover, OsOne also shows real-time images of cells, offering the experienced operator a particularly convenient tool to check the condition of the cell culture. In this study, we compared the results generated by the iLine F microscope with off-lines methods applying sampling and Trypan-Blue staining. OVIZIO’s iLine F was benchmarked versus the Vi-Cell XR (Beckman Coulter). A bioreactor equipped with a BioConnect (OVIZIO’s continuous, closed loop, sampling device) plugged into an iLine F was inoculated with CHO cells at 0.3x106 viable cells/mL in CD-CHO medium (Life Technologies) for a final volume of 2L. The culture was sampled daily via the usual sampling port for Vi-Cell cell count. The iLine F was set to generate 2 data points (cell counts and viability measurement) per hour. The culture was left to grow in batch mode so it was possible to also capture the decrease in cell viability at the end of the bioreactor run. An excellent correlation factor R² was obtained for the viable cell density demonstrating that the results achieved with the label-free DDHM method are in line with current methods applying Trypan-Blue staining. Furthermore, the iLine F shows the benefit of having the full trend of the culture which can be more relevant than a single point, on a single sample, once a day. The availability of full data at the single cell level, for the whole experiment, allows to envision the use of the iLine F in a PAT approach. Indeed the large amount of data produced can be used to perform various statistical analysis on the cell population in order to define and control critical parameters of the cell culture process

Volumetric Cell-and-Portal Generation

International audienceWe present an algorithm to generate a cell-and-portal decomposition of general indoor scenes. The method is an adaptation of the 3D watershed transform, computed on a distance-to-geometry sampled field. The watershed is processed using a flooding analogy in the distance field space. Flooding originates from local minima, each minimum producing a region. Portals are built as needed to avoid the merging of regions during their growth. As a result, the cell it deals with parametric curves, implicit surfaces, volumetric data and polygon soups in a unified way

A Low Dimensional Framework for Exact Polygon-to-Polygon Occlusion Queries

Despite the importance of from-region visibility computation in computer graphics, efficient analytic methods are still lacking in the general 3D case. Recently, different algorithms have appeared that maintain occlusion as a complex of polytopes in Plücker space. However, they suffer from high implementation complexity, as well as high computational and memory costs, limiting their usefulness in practice. In this paper, we present a new algorithm that simplifies implementation and computation by operating only on the skeletons of the polyhedra instead of the multi-dimensional face lattice usually used for exact occlusion queries in 3D. This algorithm is sensitive to complexity of the silhouette of each occluding object, rather than the entire polygonal mesh of each object. An intelligent feedback mechanism is presented that greatly enhances early termination by searching for apertures between query polygons. We demonstrate that our technique is several times faster than the state of the art

Recombinant gp350 vaccine for infectious mononucleosis: A phase 2, randomized, double-blind, placebo-controlled trial to evaluate the safety, immunogenicity, and efficacy of an Epstein-Barr virus vaccine in healthy young adults

Background. To date, there is no commercially available vaccine to prevent infectious mononucleosis, a disease frequently induced by Epstein-Barr virus (EBV) infection in adolescents or adults devoid of preexisting immunity to the virus. Methods. A total of 181 EBV-seronegative, healthy, young adult volunteers were randomized in a double-blind fashion to receive either placebo or a recombinant EBV subunit glycoprotein 350 (gp350)/aluminum hydroxide and 3-O-desacyl-4'-monophosphoryl lipid A (AS04) candidate vaccine in a 3-dose regimen. Results. The vaccine had demonstrable efficacy (mean efficacy rate, 78.0% [95% confidence interval {CI}, 1.0% -96.0%]) in preventing the development of infectious mononucleosis induced by EBV infection, but it had no efficacy in preventing asymptomatic EBV infection. One month after receipt of the final dose of gp350 vaccine, 98.7% of subjects showed seroconversion to anti-gp350 antibodies (95% CI, 85.5%-97.9%), and they remained anti-gp350 antibody positive for > 18 months. Furthermore, there were no concerns regarding the safety or reactogenicity of the gp350/AS04 vaccine. Conclusion. These data support the clinical feasibility of using an EBV vaccine to prevent infectious mononucleosis

Phase I/II studies to evaluate safety and immunogenicity of a recombinant gp350 Epstein-Barr virus vaccine in healthy adults

Two double-blind randomised controlled studies (phase I and I/II) were performed to assess for the first time the safety and immunogenicity of a recombinant subunit gp350 Epstein-Barr virus (EBV) vaccine in 148 healthy adult volunteers. All candidate vaccine formulations had a good safety profile and were well tolerated, with the incidence of solicited and unsolicited symptoms within a clinically acceptable range. One serious adverse event was reported in the phase I trial which was considered to be of suspected relationship to vaccination. The gp350 vaccine formulations were immunogenic and induced gp350-specific antibody responses (including neutralising antibodies). (c) 2007 Elsevier Ltd. All rights reserved

Dépistage néonatal des hémoglobinopathies dans la région bruxelloise

We realised this study in order to determine the frequency of abnormal haemoglobins and to appreciate the need for a neonatal screening for haemoglobinopathies in Brussels. Over a two year-period, 9575 cord blood samples were systematically screened. The study disclosed following results ' 40% of newborns were from regions at risk for haemoglobinopathies and abnormal haemoglobins were present in 2,5% of the neonates tested. This frequency is similar to those reported elsewhere m North Europe. The most frequent abnormal haemoglobins were the Hb S, Bart's, C, D and E. Three cases of severe forms of sickle cell anaemia were identified. The frequency of abnormal haemoglobins and Hb S traits combined to the high rats of mixed marriages (16%) justifies the need for a universal screening for haemoglobinopathies in Brussels.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Volumetric cell-and-portal generation

We present an algorithm to generate a cell-and-portal decomposition of general indoor scenes. The method is an adaptation of the 3D watershed transform, computed on a distance-to-geometry sampled field. The watershed is processed using a flooding analogy in the distance field space. Flooding originates from local minima, each minimum producing a region. Portals are built as needed to avoid the merging of regions during their growth. As a result, the cell-and-portal decomposition is closely linked to the structure of the models. In a building, the algorithm finds all the rooms, doors and windows. To restrict the memory load, a hierarchical implementation of the algorithm is presented. We also explain how to handle possible model degeneracies -such as cracks, holes and interpenetrating geometries- using a pre-voxelisation step. The hierarchical algorithm, preceded when necessary by the pre-voxelisation, was tested on a large range of models. We show that it is able to deal with classical architectural models, as well as cave-like environments and large mixed indoor/outdoor scenes. Thanks to the intermediate distance field representation, the algorithm can be used regardless of the way the model is represented: it deals with parametric curves, implicit surfaces, volumetric data and polygon soups in a unified way.SCOPUS: cp.jFLWINinfo:eu-repo/semantics/publishe