The mechanical effects of chemical stimuli on neurospheres.

The formulation of more accurate models to describe tissue mechanics necessitates the availability of tools and instruments that can precisely measure the mechanical response of tissues to physical loads and other stimuli. In this regard, neuroscience has trailed other life sciences owing to the unavailability of representative live tissue models and deficiency of experimentation tools. We previously addressed both challenges by employing a novel instrument called the cantilevered-capillary force apparatus (CCFA) to elucidate the mechanical properties of mouse neurospheres under compressive forces. The neurospheres were derived from murine stem cells, and our study was the first of its kind to investigate the viscoelasticity of living neural tissues in vitro. In the current study, we demonstrate the utility of the CCFA as a broadly applicable tool to evaluate tissue mechanics by quantifying the effect that oxidative stress has on the mechanical properties of neurospheres. We treated mouse neurospheres with non-cytotoxic levels of hydrogen peroxide and subsequently evaluated the storage and loss moduli of the tissues under compression and tension. We observed that the neurospheres exhibit viscoelasticity consistent with neural tissue and show that elastic modulus decreases with increasing size of the neurosphere. Our study yields insights for establishing rheological measurements as biomarkers by laying the groundwork for measurement techniques and showing that the influence of a particular treatment may be misinterpreted if the size dependence is ignored.

A new instrument for interfacial dilational rheology.

We present a new design for an interfacial dilational rheometer that can generate oscillatory dilational strain on a planar air-liquid interface. The strain is generated by a pneumatic mechanism involving a deformable film, which forms a circular barrier that can contract or expand under different pressures. The interfacial stress is measured using a Wilhelmy rod. We carefully examine and demonstrate the effects of potential sources of measurement error, including inertia, drag, buoyancy, flow from the bulk phase, and surface waves. The design avoids mixed deformations present in other instruments and is currently capable of accurate measurements at frequencies up to ∼0.1 Hz and dilational strains below 0.001, with potential for higher frequencies after further theoretical development. We demonstrate the integration of the interfacial dilational rheometer with a Langmuir trough by measuring the compression isotherm of an insoluble surfactant, stearic acid. Furthermore, we verify the capability of the interfacial dilational rheometer to perform frequency and amplitude sweeps and present the storage and loss moduli for a water-soluble surfactant, sodium dodecylbenzenesulfonate, at different concentrations.

Anti-tumor effects of an ID antagonist with no observed acquired resistance.

ID proteins are helix-loop-helix (HLH) transcriptional regulators frequently overexpressed in cancer. ID proteins inhibit basic-HLH transcription factors often blocking differentiation and sustaining proliferation. A small-molecule, AGX51, targets ID proteins for degradation and impairs ocular neovascularization in mouse models. Here we show that AGX51 treatment of cancer cell lines impairs cell growth and viability that results from an increase in reactive oxygen species (ROS) production upon ID degradation. In mouse models, AGX51 treatment suppresses breast cancer colonization in the lung, regresses the growth of paclitaxel-resistant breast tumors when combined with paclitaxel and reduces tumor burden in sporadic colorectal neoplasia. Furthermore, in cells and mice, we fail to observe acquired resistance to AGX51 likely the result of the inability to mutate the binding pocket without loss of ID function and efficient degradation of the ID proteins. Thus, AGX51 is a first-in-class compound that antagonizes ID proteins, shows strong anti-tumor effects and may be further developed for the management of multiple cancers.

Histoplasmosis in an off-trail Hiker receiving ustekinumab: Implications for Preventive and diagnostic strategies for patients receiving anti-IL-12/23 therapy.

Ustekinumab, an IL-12/23 inhibitor, is an important agent in treatment of inflammatory bowel disease and psoriasis. Clinical trials have not demonstrated significantly increased infection risk with ustekinumab. We report a case of disseminated histoplasmosis in the setting of ustekinumab and methotrexate following a hike in the Catskill Mountains, a region not commonly associated with Histoplasma encapsulatum. To our knowledge, this is the first reported case of newly acquired histoplasmosis complicating treatment with ustekinumab.

Development of a cardiac-and-piezoelectric hybrid system for application in drug screening.

In this paper, a cardiac-and-piezoelectric hybrid system is developed for drug screening. The core structure is a polyvinylidene-fluoride piezoelectric membrane that serves as a flexible structure to interact with hiPSC cardiomyocytes and that measures the contraction profile of cardiomyocytes. This design enables the capability of electrically monitoring cardiomyocytes without the aid of an optical system. To guide cardiomyocytes aligning on this circular piezoelectric membrane, concentric rings of polydimethylsiloxane microgrooves are bonded to its surface. Experimental results demonstrate that seeded cardiomyocytes can align and elongate along the circular microgrooves to form a concentric pattern. To promote cardiomyocyte maturation, bipolar stimulation is conducted using a pin and a ring electrode made of a 304 stainless steel sheet. Furthermore, to maintain body temperature and minimize environmental noise, a 304 stainless steel box is constructed to enclose the cardiac-and-piezoelectric hybrid platform. It serves as an incubator and is electrically grounded for electromagnetic interference shielding. Using this system, continuous and repeated contractions of cardiomyocytes can be developed and monitored electrically. The system performance is verified using two commercial drugs: isoproterenol and metoprolol. It is experimentally demonstrated that this system can monitor the dosage effect of both drugs. Our results also show that the measured EC50 and IC50 values of contraction frequency and amplitude are in the same range. These findings suggest that both drugs can influence the beat frequency and contraction force simultaneously. In summary, taking advantage of the electro-mechanical coupling effect of the piezoelectric membrane, this system could be scaled up to perform automatic and parallel screenings for drug discoveries.

L1CAM defines the regenerative origin of metastasis-initiating cells in colorectal cancer.

Metastasis-initiating cells with stem-like properties drive cancer lethality, yet their origins and relationship to primary-tumor-initiating stem cells are not known. We show that L1CAM+ cells in human colorectal cancer (CRC) have metastasis-initiating capacity, and we define their relationship to tissue regeneration. L1CAM is not expressed in the homeostatic intestinal epithelium, but is induced and required for epithelial regeneration following colitis and in CRC organoid growth. By using human tissues and mouse models, we show that L1CAM is dispensable for adenoma initiation but required for orthotopic carcinoma propagation, liver metastatic colonization and chemoresistance. L1CAMhigh cells partially overlap with LGR5high stem-like cells in human CRC organoids. Disruption of intercellular epithelial contacts causes E-cadherin-REST transcriptional derepression of L1CAM, switching chemoresistant CRC progenitors from an L1CAMlow to an L1CAMhigh state. Thus, L1CAM dependency emerges in regenerative intestinal cells when epithelial integrity is lost, a phenotype of wound healing deployed in metastasis-initiating cells.

Publisher Correction: TGF-ß orchestrates fibrogenic and developmental EMTs via the RAS effector RREB1.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

TGF-ß orchestrates fibrogenic and developmental EMTs via the RAS effector RREB1.

Epithelial-to-mesenchymal transitions (EMTs) are phenotypic plasticity processes that confer migratory and invasive properties to epithelial cells during development, wound-healing, fibrosis and cancer1-4. EMTs are driven by SNAIL, ZEB and TWIST transcription factors5,6 together with microRNAs that balance this regulatory network7,8. Transforming growth factor ß (TGF-ß) is a potent inducer of developmental and fibrogenic EMTs4,9,10. Aberrant TGF-ß signalling and EMT are implicated in the pathogenesis of renal fibrosis, alcoholic liver disease, non-alcoholic steatohepatitis, pulmonary fibrosis and cancer4,11. TGF-ß depends on RAS and mitogen-activated protein kinase (MAPK) pathway inputs for the induction of EMTs12-19. Here we show how these signals coordinately trigger EMTs and integrate them with broader pathophysiological processes. We identify RAS-responsive element binding protein 1 (RREB1), a RAS transcriptional effector20,21, as a key partner of TGF-ß-activated SMAD transcription factors in EMT. MAPK-activated RREB1 recruits TGF-ß-activated SMAD factors to SNAIL. Context-dependent chromatin accessibility dictates the ability of RREB1 and SMAD to activate additional genes that determine the nature of the resulting EMT. In carcinoma cells, TGF-ß-SMAD and RREB1 directly drive expression of SNAIL and fibrogenic factors stimulating myofibroblasts, promoting intratumoral fibrosis and supporting tumour growth. In mouse epiblast progenitors, Nodal-SMAD and RREB1 combine to induce expression of SNAIL and mesendoderm-differentiation genes that drive gastrulation. Thus, RREB1 provides a molecular link between RAS and TGF-ß pathways for coordinated induction of developmental and fibrogenic EMTs. These insights increase our understanding of the regulation of epithelial plasticity and its pathophysiological consequences in development, fibrosis and cancer.

ID1 Mediates Escape from TGFß Tumor Suppression in Pancreatic Cancer.

TGFß is an important tumor suppressor in pancreatic ductal adenocarcinoma (PDA), yet inactivation of TGFß pathway components occurs in only half of PDA cases. TGFß cooperates with oncogenic RAS signaling to trigger epithelial-to-mesenchymal transition (EMT) in premalignant pancreatic epithelial progenitors, which is coupled to apoptosis owing to an imbalance of SOX4 and KLF5 transcription factors. We report that PDAs that develop with the TGFß pathway intact avert this apoptotic effect via ID1. ID1 family members are expressed in PDA progenitor cells and encode components of a set of core transcriptional regulators shared by PDAs. PDA progression selects against TGFß-mediated repression of ID1. The sustained expression of ID1 uncouples EMT from apoptosis in PDA progenitors. AKT signaling and mechanisms linked to low-frequency genetic events converge on ID1 to preserve its expression in PDA. Our results identify ID1 as a crucial node and potential therapeutic target in PDA. SIGNIFICANCE: Half of PDAs escape TGFß-induced tumor suppression without inactivating the TGFß pathway. We report that ID1 expression is selected for in PDAs and that ID1 uncouples TGFß-induced EMT from apoptosis. ID1 thus emerges as a crucial regulatory node and a target of interest in PDA.This article is highlighted in the In This Issue feature, p. 1.

Flura-seq identifies organ-specific metabolic adaptations during early metastatic colonization.

Metastasis-initiating cells dynamically adapt to the distinct microenvironments of different organs, but these early adaptations are poorly understood due to the limited sensitivity of in situ transcriptomics. We developed fluorouracil-labeled RNA sequencing (Flura-seq) for in situ analysis with high sensitivity. Flura-seq utilizes cytosine deaminase (CD) to convert fluorocytosine to fluorouracil, metabolically labeling nascent RNA in rare cell populations in situ for purification and sequencing. Flura-seq revealed hundreds of unique, dynamic organ-specific gene signatures depending on the microenvironment in mouse xenograft breast cancer micrometastases. Specifically, the mitochondrial electron transport Complex I, oxidative stress and counteracting antioxidant programs were induced in pulmonary micrometastases, compared to mammary tumors or brain micrometastases. We confirmed lung metastasis-specific increase in oxidative stress and upregulation of antioxidants in clinical samples, thus validating Flura-seq's utility in identifying clinically actionable microenvironmental adaptations in early metastasis. The sensitivity, robustness and economy of Flura-seq are broadly applicable beyond cancer research.

Design and analysis of a triple reflection grazing incidence x-ray telescope.

A triple reflection grazing incidence x-ray telescope is proposed and evaluated. This form of an optical system can detect x-ray energy that is close to the optical axis, which solves the problems encountered by traditional Wolter-type systems. In this paper, we also propose a new design method to ensure that the entire telescope structure is compact and integrated. Finally, a proof-of-concept design with an acceptable image quality is proposed.

Identification of the Colicin V Bacteriocin Gene Cluster by Functional Screening of a Human Microbiome Metagenomic Library.

The forces that shape human microbial ecology are complex. It is likely that human microbiota, similarly to other microbiomes, use antibiotics as one way to establish an ecological niche. In this study, we use functional metagenomics to identify human microbial gene clusters that encode for antibiotic functions. Screening of a metagenomic library prepared from a healthy patient stool sample led to the identification of a family of clones with inserts that are 99% identical to a region of a virulence plasmid found in avian pathogenic Escherichia coli. Characterization of the metagenomic DNA sequence identified a colicin V biosynthetic cluster as being responsible for the observed antibiotic effect of the metagenomic clone against E. coli. This study presents a scalable method to recover antibiotic gene clusters from humans using functional metagenomics and highlights a strategy to study bacteriocins in the human microbiome which can provide a resource for therapeutic discovery.

Design of a compact two-channel panoramic optical system.

We propose a new panossramic optical system that provides an additional field of view (FOV) channel without expanding the physical size of a conventional panoramic annular lens (PAL). The two channels are contained within one PAL, their optical paths do not interfere with each other, and the two images are realized on a single image plane. A prototype panoramic lens was developed that provides a 360° × (38-80°) front FOV channel and a 360° × (102-140°) back FOV channel.

TGF-ß Tumor Suppression through a Lethal EMT.

TGF-ß signaling can be pro-tumorigenic or tumor suppressive. We investigated this duality in pancreatic ductal adenocarcinoma (PDA), which, with other gastrointestinal cancers, exhibits frequent inactivation of the TGF-ß mediator Smad4. We show that TGF-ß induces an epithelial-mesenchymal transition (EMT), generally considered a pro-tumorigenic event. However, in TGF-ß-sensitive PDA cells, EMT becomes lethal by converting TGF-ß-induced Sox4 from an enforcer of tumorigenesis into a promoter of apoptosis. This is the result of an EMT-linked remodeling of the cellular transcription factor landscape, including the repression of the gastrointestinal lineage-master regulator Klf5. Klf5 cooperates with Sox4 in oncogenesis and prevents Sox4-induced apoptosis. Smad4 is required for EMT but dispensable for Sox4 induction by TGF-ß. TGF-ß-induced Sox4 is thus geared to bolster progenitor identity, whereas simultaneous Smad4-dependent EMT strips Sox4 of an essential partner in oncogenesis. Our work demonstrates that TGF-ß tumor suppression functions through an EMT-mediated disruption of a lineage-specific transcriptional network.

Functional metagenomic discovery of bacterial effectors in the human microbiome and isolation of commendamide, a GPCR G2A/132 agonist.

The trillions of bacteria that make up the human microbiome are believed to encode functions that are important to human health; however, little is known about the specific effectors that commensal bacteria use to interact with the human host. Functional metagenomics provides a systematic means of surveying commensal DNA for genes that encode effector functions. Here, we examine 3,000 Mb of metagenomic DNA cloned from three phenotypically distinct patients for effectors that activate NF-κB, a transcription factor known to play a central role in mediating responses to environmental stimuli. This screen led to the identification of 26 unique commensal bacteria effector genes (Cbegs) that are predicted to encode proteins with diverse catabolic, anabolic, and ligand-binding functions and most frequently interact with either glycans or lipids. Detailed analysis of one effector gene family (Cbeg12) recovered from all three patient libraries found that it encodes for the production of N-acyl-3-hydroxypalmitoyl-glycine (commendamide). This metabolite was also found in culture broth from the commensal bacterium Bacteroides vulgatus, which harbors a gene highly similar to Cbeg12. Commendamide resembles long-chain N-acyl-amides that function as mammalian signaling molecules through activation of G-protein-coupled receptors (GPCRs), which led us to the observation that commendamide activates the GPCR G2A/GPR132. G2A has been implicated in disease models of autoimmunity and atherosclerosis. This study shows the utility of functional metagenomics for identifying potential mechanisms used by commensal bacteria for host interactions and outlines a functional metagenomics-based pipeline for the systematic identification of diverse commensal bacteria effectors that impact host cellular functions.

Development and utilization of a web-based application as a robust radiology teaching tool (radstax) for medical student anatomy teaching.

Rationale and Objectives: The primary role of radiology in the preclinical setting is the use of imaging to improve students' understanding of anatomy. Many currently available Web-based anatomy programs include either suboptimal or overwhelming levels of detail for medical students.Our objective was to develop a user-friendly software program that anatomy instructors can completely tailor to match the desired level of detail for their curriculum, meets the unique needs of the first- and the second-year medical students, and is compatible with most Internet browsers and tablets.Materials and Methods: RadStax is a Web-based application developed using free, open-source, ubiquitous software. RadStax was first introduced as an interactive resource for independent study and later incorporated into lectures. First- and second-year medical students were surveyed for quantitative feedback regarding their experience.Results: RadStax was successfully introduced into our medical school curriculum. It allows the creation of learning modules with labeled multiplanar (MPR) image sets, basic anatomic information, and a self-assessment feature. The program received overwhelmingly positive feedback from students. Of 115 students surveyed, 87.0% found it highly effective as a study tool and 85.2% reported high user satisfaction with the program.Conclusions: RadStax is a novel application for instructors wishing to create an atlas of labeled MPR radiologic studies tailored to meet the specific needs their curriculum. Simple and focused, it provides an interactive experience for students similar to the practice of radiologists.This program is a robust anatomy teaching tool that effectively aids in educating the preclinical medical student.

A systematic analysis of the PARP protein family identifies new functions critical for cell physiology.

The poly(ADP-ribose) polymerase (PARP) family of proteins use NAD(+) as their substrate to modify acceptor proteins with ADP-ribose modifications. The function of most PARPs under physiological conditions is unknown. Here, to better understand this protein family, we systematically analyse the cell cycle localization of each PARP and of poly(ADP-ribose), a product of PARP activity, then identify the knockdown phenotype of each protein and perform secondary assays to elucidate function. We show that most PARPs are cytoplasmic, identify cell cycle differences in the ratio of nuclear to cytoplasmic poly(ADP-ribose) and identify four phenotypic classes of PARP function. These include the regulation of membrane structures, cell viability, cell division and the actin cytoskeleton. Further analysis of PARP14 shows that it is a component of focal adhesion complexes required for proper cell motility and focal adhesion function. In total, we show that PARP proteins are critical regulators of eukaryotic physiology.

Gene patents: a broken incentives system.

The proliferation of patents on human genes has raised important ethical questions centered on the conflict of patient rights and intellectual property rights. With the Supreme Court's June 2013 decision that altered the patent eligibility of genetic material, it is important to reexamine the ethical implications of gene patents as a concept. Such patents suggest an ownership of genetic material that may hinder access to healthcare and inhibit medical progress. The application of the current patent system to genetic material thus violates patients' rights without fulfilling the system's goal of promoting innovation, suggesting a need for a revised incentives infrastructure.