Microfluidic cell fragmentation for mechanical phenotyping of cancer cells

Circulating tumor cells (CTCs) shed from the primary tumor undergo significant fragmentation in the microvasculature, and very few escape to instigate metastases. Inspired by this in vivo behavior of CTCs, we report a microfluidic method to phenotype cancer cells based on their ability to arrest and fragment at a micropillar-based bifurcation. We find that in addition to cancer cell size, mechanical properties determine fragmentability. We observe that highly metastatic prostate cancer cells are more resistant to fragmentation than weakly metastatic cells, providing the first indication that metastatic CTCs can escape rupture and potentially initiate secondary tumors. Our method may thus be useful in identifying phenotypes that succumb to or escape mechanical trauma in microcirculation.     

Connecting with the horizon: developing teachers’ appreciation of mathematical structure

A professional learning program for teachers of junior secondary mathematics regarding the content and pedagogy of senior secondary mathematics is the context for this study of teachers’ mathematical and pedagogical knowledge. The analysis of teachers’ reflections on their learning explored teachers’ understanding of mathematical connections and their appreciation of mathematical structure. The findings indicate that a professional learning program about senior secondary mathematics can enable practicing teachers to deepen and broaden their knowledge for teaching junior secondary mathematics and develop their practice to support their students’ present and future learning of mathematics. Further research is needed about professional learning approaches and tasks that may enable teachers to imbed and develop awareness of structure in their practice.     

Knowledge and Dignity in the Era of “Big Data”

Private companies and government agencies are now creating and tapping into vastly more data than ever before. These data flows include enormous amounts of personal information and raise questions about privacy and intellectual policy that could have profound impacts on our lives. While data collection and creation are nearly ubiquitous, the instruments of collection and analysis are often hidden in order to track more natural behavior. Recent revelations of massive governmental data collection offer the country, and librarians in particular, an opportunity to discuss and question the societal implications of “Big Data,” and the policies that govern them.     

Electron paramagnetic resonance imaging

In this part we shall outline the challenges one faces while developing time-domain radiofrequency (RF) EPR imaging spectrometer for in vivo studies. Time-domain or FT-EPR is quite a different animal compared to the CW modality. The evolution of FT-EPR instrumentation at the National Cancer Institute, NIH, USA and representative examples of application in cancer research are outlined in this article.     

Urban‐rural dichotomy in Malaysian elections

This article synthesizes the findings of two empirical surveys carried out in 1986 and 1990 in Malaysia. It also presents a brief historical background of the political process in the country, as well as an overview of the Malaysian media. Finally, it touches on the latest general elections in Malaysia, held in 1995, and their implications.     

Electrocoalescence based serial dilution of microfluidic droplets

Dilution of microfluidic droplets where the concentration of a reagent is incrementally varied is a key operation in drop-based biological analysis. Here, we present an electrocoalescence based dilution scheme for droplets based on merging between moving and parked drops. We study the effects of fluidic and electrical parameters on the dilution process. Highly consistent coalescence and fine resolution in dilution factor are achieved with an AC signal as low as 10 V even though the electrodes are separated from the fluidic channel by insulator. We find that the amount of material exchange between the droplets per coalescence event is high for low capillary number. We also observe different types of coalescence depending on the flow and electrical parameters and discuss their influence on the rate of dilution. Overall, we find the key parameter governing the rate of dilution is the duration of coalescence between the moving and parked drop. The proposed design is simple incorporating the channel electrodes in the same layer as that of the fluidic channels. Our approach allows on-demand and controlled dilution of droplets and is simple enough to be useful for assays that require serial dilutions. The approach can also be useful for applications where there is a need to replace or wash fluid from stored drops.     

Implementation of a project-based molecular biology laboratory emphasizing protein structure-function relationships in a large introductory biology laboratory course

In introductory laboratory courses, many universities are turning from traditional laboratories with predictable outcomes to inquiry-inspired, project-based laboratory curricula. In these labs, students are allowed to design at least some portion of their own experiment and interpret new, undiscovered data. We have redesigned the introductory biology laboratory course at Brandeis University into a semester-long project-based laboratory that emphasizes concepts and contains an element of scientific inquiry. In this laboratory, students perform a site-directed mutagenesis experiment on the gene encoding human γD crystallin, a human eye lens protein implicated in cataracts, and assess the stability of their newly created protein with respect to wild-type crystallin. This laboratory utilizes basic techniques in molecular biology to emphasize the importance of connections between DNA and protein. This project lab has helped engage students in their own learning, has improved students' skills in critical thinking and analysis, and has promoted interest in basic research in biology.     

Electron Paramagnetic Resonance imaging

EPR (Electron Paramagnetic Resonance) imaging is particularly useful in monitoring hypoxic zones in tumors which are highly resistant to radiation and chemotherapeutic treatment. This first part of the article covers aspects of CW (continuous wave) imaging with details of FT (pulsed Fourier Transform)-EPR imaging covered in Part 2, to be published in the next issue of Resonance.