Phaseguide assisted liquid lamination for magnetic particle-based assays

We have developed a magnetic particle-based assay platform in which functionalised magnetic particles are transferred sequentially through laminated volumes of reagents and washing buffers. Lamination of aqueous liquids is achieved via the use of phaseguide technology; microstructures that control the advancing air–liquid interface of solutions as they enter a microfluidic chamber. This allows manual filling of the device, eliminating the need for external pumping systems, and preparation of the system requires only a few minutes. Here, we apply the platform to two on-chip strategies: (i) a one-step streptavidin–biotin binding assay, and (ii) a two-step C-reactive protein immunoassay. With these, we demonstrate how condensing multiple reaction and washing processes into a single step significantly reduces procedural times, with both assay procedures requiring less than 8 seconds

Million-dollar mathematics : an honors thesis (HONRS 499)

This examination explores three of the challenging "Millennium Prize Problems" that were announced in 2000 by the Clay Mathematical Institute of Cambridge, Massachusetts. They are offering a $1 million prize for the solution to any one of the seven long-standing mathematical questions as a way to "celebrate mathematics in the new millennium" (www.claymath.org). The first section investigates the zeros of the Zeta Function to consider the Riemann Hypothesis. In the second section, the P versus NP problem is examined to try to determine if these two classes of mathematical problems are actually the same. The third section deals with the Birch and SwinnertonDyer Conjecture, explaining This investigation of these very difficult problems is meant to explain the statements of each problem, provide any background information, and explore related examples to establish a foundation about some of most significant and interesting mathematical problems of the new millennium.Honors CollegeThesis (B.?.

Membrane-free culture and real-time barrier integrity assessment of perfused intestinal epithelium tubes

In vitro models that better reflect in vivo epithelial barrier (patho-)physiology are urgently required to predict adverse drug effects. Here we introduce extracellular matrix-supported intestinal tubules in perfused microfluidic devices, exhibiting tissue polarization and transporter expression. Forty leak-tight tubules are cultured in parallel on a single plate and their response to pharmacological stimuli is recorded over 125 h using automated imaging techniques. A study comprising 357 gut tubes is performed, of which 93% are leak tight before exposure. EC50-time curves could be extracted that provide insight into both concentration and exposure time response. Full compatibility with standard equipment and user-friendly operation make this Organ-on-a-Chip platform readily applicable in routine laboratories

Qu’en penseraient mes pairs? Comparaison entre la méthode fondée sur l'opinion et celle fondée sur la prédiction dans l'évaluation de cours de formation médicale continue

Background: Although medical courses are frequently evaluated via surveys with Likert scales ranging from “strongly agree” to “strongly disagree,” low response rates limit their utility. In undergraduate medical education, a new method with students predicting what their peers would say, required fewer respondents to obtain similar results. However, this prediction-based method lacks validation for continuing medical education (CME), which typically targets a more heterogeneous group than medical students. Methods: In this study, 597 participants of a large CME course were randomly assigned to either express personal opinions on a five-point Likert scale (opinion-based method; n = 300) or to predict the percentage of their peers choosing each Likert scale option (prediction-based method; n = 297). For each question, we calculated the minimum numbers of respondents needed for stable average results using an iterative algorithm. We compared mean scores and the distribution of scores between both methods. Results: The overall response rate was 47%. The prediction-based method required fewer respondents than the opinion-based method for similar average responses. Mean response scores were similar in both groups for most questions, but prediction-based outcomes resulted in fewer extreme responses (strongly agree/disagree). Conclusions: We validated the prediction-based method in evaluating CME. We also provide practical considerations for applying this method.Contexte : Bien que les cours de médecine soient fréquemment évalués au moyen d'enquêtes avec des échelles de Likert allant de « totalement d'accord » à « totalement en désaccord », les faibles taux de réponse en limitent l'utilité. Dans l'enseignement médical prédoctoral, une nouvelle méthode dans laquelle les étudiants prédisent ce que leurs pairs diraient, nécessite moins de répondants pour obtenir des résultats similaires. Cependant, cette méthode fondée sur la prédiction n'est pas validée pour la formation médicale continue (FMC), qui cible généralement un groupe plus hétérogène que les étudiants en médecine. Méthodes : Dans cette étude, 597 participants à un grand cours de FMC ont été choisis au hasard pour exprimer leur opinion personnelle sur une échelle de Likert en cinq points (méthode fondée sur l'opinion; n = 300) ou à prédire le pourcentage de leurs pairs choisissant chaque option de l'échelle de Likert (méthode fondée sur la prédiction; n = 297). Pour chaque question, nous avons calculé le nombre minimum de répondants nécessaire pour obtenir des résultats moyens stables à l'aide d'un algorithme itératif. Nous avons comparé les scores moyens et la distribution des scores entre les deux méthodes. Résultats : Le taux de réponse global était de 47 %. La méthode fondée sur la prédiction a nécessité moins de répondants que celle fondée sur l'opinion pour des réponses moyennes similaires. Les scores moyens des réponses étaient similaires dans les deux groupes pour la plupart des questions, mais les résultats fondés sur la prédiction ont donné lieu à moins de réponses extrêmes (totalement d'accord/totalement en désaccord). Conclusions : Nous avons validé la méthode fondée sur la prédiction dans l'évaluation de la FMC. Nous présentons également des considérations pratiques pour la mise en œuvre de cette méthode

Design and analysis of a microplate assay in the presence of multiple restrictions on the randomization

Experiments using multi-step protocols often involve several restrictions on the randomization. For a specific application to in vitro testing on microplates, a design was required with both a split-plot and a strip-plot structure. On top of two-level treatment factors and the factors that define the randomization restrictions, a multi-level fixed blocking factor not involving further restrictions on the randomization had to be added. We develop a step-by-step approach to construct a design for the microplate experiment and analyze a response. To consolidate the approach, we study various alternative scenarios for the experiment.Comment: 31 pages, 13 tables, 4 figure

Endoglin and squamous cell carcinomas

Despite the fact that the role of endoglin on endothelial cells has been extensively described, its expression and biological role on (epithelial) cancer cells is still debatable. Especially its function on squamous cell carcinoma (SCC) cells is largely unknown. Therefore, we investigated SCC endoglin expression and function in three types of SCCs; head and neck (HNSCC), esophageal (ESCC) and vulvar (VSCC) cancers. Endoglin expression was evaluated in tumor specimens and 14 patient-derived cell lines. Next to being expressed on angiogenic endothelial cells, endoglin is selectively expressed by individual SCC cells in tumor nests. Patient derived HNSCC, ESCC and VSCC cell lines express varying levels of endoglin with high interpatient variation. To assess the function of endoglin in signaling of TGF-β ligands, endoglin was overexpressed or knocked out or the signaling was blocked using TRC105, an endoglin neutralizing antibody. The endoglin ligand BMP-9 induced strong phosphorylation of SMAD1 independent of expression of the type-I receptor ALK1. Interestingly, we observed that endoglin overexpression leads to strongly increased soluble endoglin levels, which in turn decreases BMP-9 signaling. On the functional level, endoglin, both in a ligand dependent and independent manner, did not influence proliferation or migration of the SCC cells. In conclusion, these data show endoglin expression on individual cells in the tumor nests in SCCs and a role for (soluble) endoglin in paracrine signaling, without directly affecting proliferation or migration in an autocrine manner.</p

Development of a gut-on-a-chip model for high throughput disease modeling and drug discovery

A common bottleneck in any drug development process is finding sufficiently accurate models that capture key aspects of disease development and progression. Conventional drug screening models often rely on simple 2D culture systems that fail to recapitulate the complexity of the organ situation. In this study, we show the application of a robust high throughput 3D gut-on-a-chip model for investigating hallmarks of inflammatory bowel disease (IBD). Using the OrganoPlate platform, we subjected enterocyte-like cells to an immune-relevant inflammatory trigger in order to recapitulate key events of IBD and to further investigate the suitability of this model for compound discovery and target validation activities. The induction of inflammatory conditions caused a loss of barrier function of the intestinal epithelium and its activation by increased cytokine production, two events observed in IBD physiopathology. More importantly, anti-inflammatory compound exposure prevented the loss of barrier function and the increased cytokine release. Furthermore, knockdown of key inflammatory regulators RELA and MYD88 through on-chip adenoviral shRNA transduction alleviated IBD phenotype by decreasing cytokine production. In summary, we demonstrate the routine use of a gut-on-a-chip platform for disease-specific aspects modeling. The approach can be used for larger scale disease modeling, target validation and drug discovery purpose

Million-dollar mathematics : an honors thesis (HONRS 499)

This examination explores three of the challenging "Millennium Prize Problems" that were announced in 2000 by the Clay Mathematical Institute of Cambridge, Massachusetts. They are offering a $1 million prize for the solution to any one of the seven long-standing mathematical questions as a way to "celebrate mathematics in the new millennium" (www.claymath.org). The first section investigates the zeros of the Zeta Function to consider the Riemann Hypothesis. In the second section, the P versus NP problem is examined to try to determine if these two classes of mathematical problems are actually the same. The third section deals with the Birch and SwinnertonDyer Conjecture, explaining This investigation of these very difficult problems is meant to explain the statements of each problem, provide any background information, and explore related examples to establish a foundation about some of most significant and interesting mathematical problems of the new millennium.Thesis (B.?.)Honors Colleg