A multi-site metastasis-on-a-chip microphysiological system for assessing metastatic preference of cancer cells

Metastatic disease remains one of the primary reasons for cancer-related deaths, yet the majority of in vitro cancer models focus on the primary tumor sites. Here, we describe a metastasis-on-a-chip device that houses multiple bioengineered three-dimensional (3D) organoids, established by a 3D photopatterning technique employing extracellular matrix-derived hydrogel biomaterials. Specifically, cancer cells begin in colorectal cancer (CRC) organoid, which resides in a single microfluidic chamber connected to multiple downstream chambers in which liver, lung, and endothelial constructs are housed. Under recirculating fluid flow, tumor cells grow in the primary site, eventually enter circulation, and can be tracked via fluorescent imaging. Importantly, we describe that in the current version of this platform, HCT116 CRC cells preferentially home to the liver and lung constructs; the corresponding organs of which CRC metastases arise the most in human patients. We believe that in subsequent studies this platform can be implemented to better understand the mechanisms underlying metastasis, perhaps resulting in the identification of targets for intervention.     

Quantitative comparisons ofin situ microbial biodiversity by signature biomarker analysis

Microscopic examinations have convinced microbial ecologists that the culturable microbes recovered from environmental samples represent a tiny proportion of the extant microbiota. Methods for recovery and enzymatic amplification of nucleic acids from environmental samples have shown that a huge diversity existsin situ, far exceeding any expectations which were based on direct microscopy. It is now theoretically possible to extract, amplify and sequence all the nucleic acids from a community and thereby gain a comprehensive measure of the diversity as well as some insights into the phylogeny of the various elements within this community. Unfortunately, this analysis becomes economically prohibitive if applied to the multitude of niches in a single biome let alone to a diverse set of environments. It is also difficult to utilize PCR amplification on nucleic acids from some biomes because of coextracting enzymatic inhibitors. Signature biomarker analysis which potentially combines gene probe and lipid analysis on the same sample, can serve as a complement to massive environmental genome analysis in providing quantitative comparisons between microniches in the biome under study. This analysis can also give indications of the magnitude of differences in biodiversity in the blome as well as provide insight into the phenotypic activities of each community in a rapid and cost-effective manner. Applications of signature lipid biomarker analysis to define quantitatively the microbial viable biomass of portions of an Eastern USA deciduous forest, are presented.     

Conformational study of a nine residue fragment of the antigenic loop of foot-and-mouth disease virus.

The nine-residue peptide Ac-TASARGDLA-NHMe was selected as model peptide in order to understand the conformational features of the antigenic loop of foot-and-mouth disease virus (FMDV). A throughout exploration of the conformational space has been carried out by means of molecular dynamics (MD) and energy minimization. The calculations have been carried out using the AMBER force field. Solvent effects have been included by an effective dielectric constant of epsilon = 4r. The lowest energy conformation presents a secondary structure constituted by an alpha-helix at the N-terminal end followed by two gamma-turns in the central region. The rest of the accessible minima found present also a high tendency to form gamma-turns. Finally, a 100 ps MD trajectory calculation at 298 K suggest a stability of the secondary structure elements of the lowest energy conformation.     

Comparison of Isocitrate Dehydrogenase Activity, Pyruvate Kinase Activity, and Polyphenol Content in Physiologically Different Pine Callus Tissue

During the growth of callus tissue of slash pine (Pinus elliottil Engelm.) several physiologically different types of tissue can be observed, often within the same culture. Different tissues were selected, based on color appearance, and used to determine isocitrate dehydrogenase and pyruvate kinase activity, and total polyphenol content. Isocitrate dehydrogenase and pyruvate kinase activity in yellow tissue was 3- to 5-fold greater than in brown tissue, whereas the polyphenol content in yellow tissue was approximately 5-fold less than in brown tissue. Dark brown callus, which also contained large amounts of polyphenols, did not have detectable enzyme activity. The differences in optimal concentrations of substrate and cofactors for the isocitrate dehydrogenase and pyruvate kinase reactions in yellow and brown tissues were very minor and therefore cannot account for the 3- to 5-fold difference in enzyme activity between these tissues. Also, the addition of brown or dark-brown tissue extract to the yellow tissue extract did not inhibit isocitrate dehydrogenase or pyruvate kinase activity in the yellow tissue extract.     

Preferential selection of Cys‐constrained peptides from a random phage‐displayed library by anti‐glucitollysine antibodies

Phage‐displayed peptides recognized by two monoclonal antibodies against glucitollysine were selected. The most prominent feature of the peptide panel was the presence of paired Cys in most of them (21/24 peptides). The availability of a wide variety of peptides having differently spaced paired Cys, as well as truly linear Cys‐free peptides, gave the opportunity to explore the role of disulfide bridges in phage selection. Some Cys‐containing peptides came from a Cys‐flanked cyclic 9‐mer library, but most of them (18/21) were derived from a totally random 12‐mer library, and hence the presence of Cys was dictated by the selector antibodies. Motifs shared by several peptides (potentially involved in binding) often contained or were flanked by Cys residues. Binding of all Cys‐containing phage‐displayed peptides was abolished/decreased after a reducing treatment. Screening a random peptide library (without invariant Cys residues) is powerful enough to clearly reveal the need, preferences, and diversity of Cys‐mediated structural constraints for recognition. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.