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Extracellular matrix microstructure and mechanics are crucial to breast cancer progression and invasion into surrounding tissues. The peritumor collagen network is often dense and aligned, features which in vitro models lack. Aspiration of collagen hydrogels led to densification and alignment of microstructure surrounding embedded cancer cells. Two metastasis-derived breast cancer cell lines, MDA-MB-231 and MCF-7, were cultured in initially 4 mg/ml collagen gels for 3 days after aspiration, as well as in unaspirated control hydrogels. Videomicroscopy during aspiration, and at 0, 1, and 3 days after aspiration, epifluorescence microscopy of phalloidin-stained F-actin cytoskeleton, histological sections, and soluble metabolic byproducts from constructs were collected to characterize effects on the embedded cell morphology, the collagen network microstructure, and proliferation. Breast cancer cells remained viable after aspiration-ejection, proliferating slightly less than in unaspirated gels. Furthermore, MDA-MB-231 cells appear to partially relax the collagen network and lose alignment 3 days after aspiration. Aspiration-ejection generated aligned, compact collagen network microstructure with immediate cell co-orientation and higher cell number density apparently through purely physical means, though cell-collagen contact guidance and network remodeling influence cell organization and collagen network microstructure during subsequent culture. This study establishes a platform to determine the effects of collagen density and alignment on cancer cell behavior, with translational potential for anticancer drug screening in a biomimetic three-dimensional matrix microenvironment, or implantation in preclinical models. [ABSTRACT FROM AUTHOR]

We have developed a user-friendly microfluidic device for the study of gradientmediated bacterial behaviors, including chemotaxis. This device rapidly establishes linear concentration gradients by exploiting solute diffusion through porous membranes in the absence of convective flows. As such, the gradients are created rapidly and can be sustained for long time periods (e.g., hours), sufficient to evaluate cell phenotype. The device exploits a unique simple bilayer configuration that enables rapid setup and quick reproducible introduction of cells. Its reusability represents an additional advantage in that it need not be limited to settings with microfluidics expertise. We have successfully demonstrated the applicability of this tool in studying the chemotactic response of Escherichia coli to glucose. When coupled with our recent Python program, quantified metrics such as speed, ratio of tumble to run, and effective diffusivity can be obtained from slow frame rate videos. Moreover, we introduce a chemotaxis partition coefficient that conveniently scores swimming behavior on the single-cell level. [ABSTRACT FROM AUTHOR]

Chemotaxis is a phenomenon which enables cells to sense concentrations of certain chemical species in their microenvironment and move towards chemically favorable regions. Recent advances in microbiology have engineered the chemotactic properties of bacteria to perform novel functions, but traditional methods of characterizing chemotaxis do not fully capture the associated cell motion, making it difficult to infer mechanisms that link the motion to the microbiology which induces it. Microfluidics offers a potential solution in the form of gradient generators. Many of the gradient generators studied to date for this application are flow-based, where a chemical species diffuses across the laminar flow interface between two solutions moving through a microchannel. Despite significant research efforts, flow-based gradient generators have achieved mixed success at accurately capturing the highly subtle chemotactic responses exhibited by bacteria. Here we present an analysis encompassing previously published versions of flow-based gradient generators, the theories that govern their gradientgenerating properties, and new, more practical considerations that result from experimental factors. We conclude that flow-based gradient generators present a challenge inherent to their design in that the residence time and gradient decay must be finely balanced, and that this significantly narrows the window for reliable observation and quantification of chemotactic motion. This challenge is compounded by the effects of shear on an ellipsoidal bacterium that causes it to preferentially align with the direction of flow and subsequently suppresses the cross-flow chemotactic response. These problems suggest that a static, nonflowing gradient generator may be a more suitable platform for chemotaxis studies in the long run, despite posing greater difficulties in design and fabrication. [ABSTRACT FROM AUTHOR]

Joint industrial development zones have emerged among cities in the Yangtze River Delta region in recent years. Given that such zones involve collaboration between different authorities, this has implications for the practice of urban governance in China. This article examines these processes in relation to the Jiangyin Economic Development Zone in Jingjiang (JZJ) using debates around urban growth coalitions. Two categories of actors, different levels of local government and business sectors, are identified and their interactions in coalition-building are analysed in detail. After tracing the process of coalition formation, this paper argues that growth coalitions can form between two cities involving processes above the urban scale in a globalising era. In addition, a local government-big business coalition, similar to its Western counterparts, is dominating industrial zone construction within Chinese urban growth. [ABSTRACT FROM AUTHOR]

We surveyed 65 patients age 13 years or older who had been treated for malignant bone tumors and were in remission at least 1 year after limb-sparing surgery (LS) or amputation (AMP) to assess general satisfaction with the surgical outcome and its impact on various areas of functioning. Of 130 eligible patients, 65 responded (61 treated for osteosarcoma, 3 for Ewing's sarcoma, and 1 for mesenchymoma). The median current age of the cohort was 25.8 years (range, 14.2 to 47.5 years). The median time from surgery was 14.2 years (range, 4.0 to 30.4 years) for the AMP group, and 5.5 years (range, 2.0 to 13.8 years) for the LS patients. Questionnaire responses of patients treated with AMP compared to those who had LS surgery showed no significant differences in the impact of the surgical procedure on educational and occupational status, functional limitations, pain intensity and degree of pain interference, emotional distress, interpersonal/social interactions and self-image, rehabilitation experience, and overall satisfaction with the surgical procedure. Functional limitation was significantly related to pain interference, as well as emotional distress, self-image, and interpersonal difficulties for the entire cohort. Our findings highlight procedure-related advantages and difficulties that may potentially enhance decision making regarding the selection of the surgical procedure for individual patients with malignant bone tumors of an extremity [ABSTRACT FROM PUBLISHER]

Programmable 3D cell assembly under physiological pH conditions is achieved using electrodeposited stimuli-responsive alginate gels in a microfluidic device, with parallel sidewall electrodes enabling direct observation of the cell assembly. Electrically triggered assembly and subsequent viability of mammalian cells is demonstrated, along with spatially programmable, multi-address assembly of different strains of E. colicells. Our approach enables in vitrostudy of dynamic cellular and inter-cellular processes, from cell growth and stimulus/response to inter-colony and inter-species signaling. [ABSTRACT FROM AUTHOR]