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Rho guanine nucleotide exchange factors (RhoGEFs) regulate Rho GTPase activity and cytoskeletal and cell adhesion dynamics. βPix, a CDC42/RAC family RhoGEF encoded by ARHGEF7, is reported to modulate human colon cancer cell proliferation and postwounding restitution of rat intestinal epithelial monolayers. We hypothesized that βPix plays a role in maintaining intestinal epithelial homeostasis. To test this hypothesis, we examined βPix distribution in the human and murine intestine and created mice with intestinal epithelial-selective βPix deletion [βPix(flox/flox)/Tg(villin-Cre); Arhgef7 CKO mice]. Using Arhgef7 conditional knockout (CKO) and control mice, we investigated the consequences of βPix deficiency in vivo on intestinal epithelial and enteroid development, dextran sodium sulfate-induced mucosal injury, and gut permeability. In normal human and murine intestines, we observed diffuse cytoplasmic and moderate nuclear βPix immunostaining in enterocytes. Arhgef7 CKO mice were viable and fertile, with normal gross intestinal architecture but reduced small intestinal villus height, villus-to-crypt ratio, and goblet cells; small intestinal crypt cells had reduced Ki67 staining, compatible with impaired cell proliferation. Enteroids derived from control mouse small intestine were viable for more than 20 passages, but those from Arhgef7 CKO mice did not survive beyond 24 h despite addition of Wnt proteins or conditioned media from normal enteroids. Adding a Rho kinase (ROCK) inhibitor partially rescued CKO enteroid development. Compared with littermate control mice, dextran sodium sulfate-treated βPix-deficient mice lost more weight and had greater impairment of intestinal barrier function, and more severe colonic mucosal injury. These findings reveal βPix expression is important for enterocyte development, intestinal homeostasis, and resistance to toxic injury. NEW & NOTEWORTHY To explore the role of βPix, a guanine nucleotide exchange factor encoded by ARHGEF7, in intestinal development and physiology, we created mice with intestinal epithelial cell Arhgef7/βPix deficiency. We found βPix essential for normal small intestinal epithelial cell proliferation, villus development, and mucosal resistance to injury. Moreover, Rho kinase signaling mediated developmental arrest observed in enteroids derived from βPix-deficient small intestinal crypts. Our studies provide insights into the role Arhgef7/βPix plays in intestinal epithelial homeostasis.

Despite great advances in our understanding of the pathobiology of colorectal cancer and the genetic and environmental factors that mitigate its onset and progression, a paucity of effective treatments persists. The five-year survival for advanced, stage IV disease remains substantially less than 20%. This review examines a relatively untapped reservoir of potential therapies to target muscarinic receptor expression, activation, and signaling in colorectal cancer. Most colorectal cancers overexpress M3 muscarinic receptors (M3R), and both in vitro and in vivo studies have shown that activating these receptors stimulates cellular programs that result in colon cancer growth, survival, and spread. In vivo studies using mouse models of intestinal neoplasia have shown that using either genetic or pharmacological approaches to block M3R expression and activation, respectively, attenuates the development and progression of colon cancer. Moreover, both in vitro and in vivo studies have shown that blocking the activity of matrix metalloproteinases (MMPs) that are induced selectively by M3R activation, i.e., MMP1 and MMP7, also impedes colon cancer growth and progression. Nonetheless, the widespread expression of muscarinic receptors and MMPs and their importance for many cellular functions raises important concerns about off-target effects and the safety of employing similar strategies in humans. As we highlight in this review, highly selective approaches can overcome these obstacles and permit clinicians to exploit the reliance of colon cancer cells on muscarinic receptors and their downstream signal transduction pathways for therapeutic purposes.

AA amyloidosis, previously known as secondary amyloidosis, has been associated with multiple chronic inflammatory conditions, including various autoimmune diseases and rarely chronic infection. Hereby, we present a case of AA amyloidosis secondary to chronic infection which initially presented with nausea and hematemesis. Endoscopic biopsies revealed diffuse AA amyloid deposition in the stomach, but not the esophagus. AA Amyloidosis presumably compromised gastric motility, promoted reflux related esophageal ulcers and erosions, and caused his cardiac and renal insufficiency. Therefore, endoscopic biopsies could be practical investigation to identify AA amyloidosis in the setting of chronic inflammatory diseases, especially with multi-organ involvement.

Background Expression and activation of subtype-3 muscarinic receptors (M3R) plays an important role in the progression of colorectal neoplasia. Method Herein, we describe the role of muscarinic receptors in colon cancer, focusing specifically on M3R, illustrate how M3R over-expression and activation of post-receptor signaling pathways potentiates tumor progression, and explore the efficacy and safety of a variety of therapeutic approaches that can target the molecules involved. Results Colon cancers overexpress M3R mRNA (CHRM3) and protein, and post-M3R signaling stimulates cell proliferation. Post-M3R signal transduction is complex, involving interplay between epidermal growth factor receptors (EGFR)/ERK and protein kinase C (PKC)/p38 mitogen-activated protein (MAP) kinase signaling pathways. In particular, the development of an invasive and metastatic phenotype requires that these signaling interactions augment cellular release of a key collagenase, matrix metalloproteinase-1 (MMP1). Blocking either M3R activation or post-M3R signaling attenuates MMP1 release and colon cancer invasiveness. Conclusion Parsing the complexities of these signaling interactions is important, not only to understand these mechanisms of cancer initiation and progression, but also to develop novel treatment modalities. Since the vast majority of persons with colon cancer die from disseminated disease, preventing or reversing metastatic spread of cancer cells by targeting M3R, post-M3R signaling, or MMP1 has therapeutic potential.

Cancers arising from gastrointestinal epithelial cells are common, aggressive, and difficult to treat. Progress in this area resulted from recognizing that the biological behavior of these cancers is highly dependent on bioactive molecules released by neurocrine, paracrine, and autocrine mechanisms within the tumor microenvironment. For many decades after its discovery as a neurotransmitter, acetylcholine was thought to be synthesized and released uniquely from neurons and considered the sole physiological ligand for muscarinic receptor subtypes, which were believed to have similar or redundant actions. In the intervening years, we learned this former dogma is not tenable. (1) Acetylcholine is not produced and released only by neurons. The cellular machinery required to synthesize and release acetylcholine is present in immune, cancer, and other cells, as well as in lower organisms (e.g., bacteria) that inhabit the gut. (2) Acetylcholine is not the sole physiological activator of muscarinic receptors. For example, selected bile acids can modulate muscarinic receptor function. (3) Muscarinic receptor subtypes anticipated to have overlapping functions based on similar G protein coupling and downstream signaling may have unexpectedly diverse actions. Here, we review the relevant research findings supporting these conclusions and discuss how the complexity of muscarinic receptor biology impacts health and disease, focusing on their role in the initiation and progression of gastric, pancreatic, and colon cancers.

M3 muscarinic receptor (M3R) expression is increased in colon cancer; M3R activation stimulates colon cancer cell invasion via cross-talk with epidermal growth factor receptors (EGFR), post-EGFR activation of mitogen-activated protein kinase (MAPK) extracellular signal-related kinase 1/2 (ERK1/2), and induction of matrix metalloproteinase-1 (MMP1) expression. MMP1 expression is strongly associated with tumor metastasis and adverse outcomes. Here, we asked whether other MAPKs regulate M3R agonist-induced MMP1 expression. In addition to activating ERK1/2, we found that treating colon cancer cells with acetylcholine (ACh) stimulated robust time- and dose-dependent phosphorylation of p38 MAPK. Unlike ERK1/2 activation, ACh-induced p38 phosphorylation was EGFR-independent and blocked by inhibiting protein kinase C-α (PKC-α). Inhibiting activation of PKC-α, EGFR, ERK1/2, or p38-α/β alone attenuated, but did not abolish ACh-induced MMP1 expression, a finding that predicted potentiating interactions between these pathways. Indeed, ACh-induced MMP1 expression was abolished by incubating cells with either an EGFR or MEK/ERK1/2 inhibitor combined with a p38-α/β inhibitor. Activating PKC-α and EGFR directly with the combination of phorbol 12-myristate 13-acetate (PMA) and EGF potentiated MMP1 gene and protein expression, and cell invasion. PMA- and ACh-induced MMP1 expression were strongly diminished by inhibiting Src and abolished by concurrently inhibiting both p38-α/β and Src, indicating that Src mediates the cross-talk between PKC-α and EGFR signaling. Using siRNA knockdown, we identified p38-α as the relevant p38 isoform. Collectively, these studies uncover novel functional interactions between post-muscarinic receptor signaling pathways that augment MMP1 expression and drive colon cancer cell invasion; targeting these potentiating interactions has therapeutic potential.

Although epidemiological evidence in humans and bile acid feeding studies in rodents implicate bile acids as tumor promoters, the role of endogenous bile acids in colon carcinogenesis remains unclear. In this study, we exploited mice deficient in the ileal apical sodium-dependent bile acid transporter (ASBT, encoded by SLC10A2) in whom fecal bile acid excretion is augmented more than 10-fold. Wild-type and Asbt-deficient (Slc10a2 (-/-) ) male mice were treated with azoxymethane (AOM) alone to examine the development of aberrant crypt foci, the earliest histological marker of colon neoplasia and a combination of AOM and dextran sulfate sodium to induce colon tumor formation. Asbt-deficient mice exhibited a 54% increase in aberrant crypt foci, and 70 and 59% increases in colon tumor number and size, respectively. Compared to littermate controls, Asbt-deficient mice had a striking, 2-fold increase in the number of colon adenocarcinomas. Consistent with previous studies demonstrating a role for muscarinic and epidermal growth factor receptor signaling in bile acid-induced colon neoplasia, increasing bile acid malabsorption was associated with M3 muscarinic and epidermal growth factor receptor expression, and activation of extracellular signal-related kinase, a key post-receptor signaling molecule.

For graphene-based electrode materials, N doping is one of the leading approaches for enhancing the performance of supercapacitors. However, such an outstanding performance is suppressed by the agglomeration of graphene and unspecified N incorporation. Here, we demonstrate a direct growth of vertically epitaxial graphene nanowalls (GNWs) on flexible carbon cloths (CCs) via microwave plasma-enhanced chemical vapor deposition, whereby predominantly N doping was sequentially achieved by introducing in situ NH 3 plasma, to form N-doped GNWs (NGNWs). The vertically aligned three-dimensional (3D) architecture of epitaxial NGNWs and their unique selectivity to the specific N dopants make such electrodes an ideal platform, not only for enhancing the capacitive performance but also for studying the role of the C N bonding configuration in its performance. Remarkably, NGNW supercapacitors exhibit an excellent specific capacitance of 991.6 F/g (estimation based on the actively contributing component) and an apparent area-normalized capacitance of 1488.9 mF/cm 2 , at a specific current of 14.8 A/g. This approach allows us to achieve an energy density of 275.4 Wh/kg at a power density of 14.8 kW/kg (specific current of 14.8 A/g), and a power density of 74.1 kW/kg at an energy density of 232.6 Wh/kg (specific current of 74.1 A/g) in 1 M H 2 SO 4 .

An on-chip growth technique aiming at large-scale production of few-layer epitaxial graphene nanowall (EGNW) arrays by microwave plasma enhanced chemical vapor deposition has been demonstrated. This hetero-architecture is formed by growing edge-oriented SiC nanowalls on Si substrates, followed by surface graphitization, consequently, thus resulting in a heterojunction composed of a 2H-SiC nanowall sheathed by few-layer strained graphene. Similar to epitaxial graphene grown on SiC in an ultrahigh vacuum ambient, structural compressive strain was found in the EGNW and can be relaxed as the layer number of graphene layers increases. More significantly, the SiC-supported strained graphene nanowalls show a remarkably improved catalytic activity ∼425 A/g and low onset potential ∼0.23 V (vs. Ag/AgCl) for the electro-oxidation of methanol as well as excellent pH sensitivity, thus demonstrating their potential applications in sensors, catalyst supports, and other electrochemical devices.

Preterm infants face many challenges in transitioning from the in utero to extrauterine environment while still immature. Failure of the preterm gut to successfully mature to accommodate bacteria and food substrate leads to significant morbidity such as neonatal necrotizing enterocolitis. The intestinal epithelial barrier plays a critical role in gut protection. Heat shock protein 70 (Hsp70) is an inducible cytoprotective molecule shown to protect the intestinal epithelium in adult models. To investigate the hypothesis that Hsp70 may be important for early protection of the immature intestine, Hsp70 expression was evaluated in intestine of immature rat pups. Data demonstrate that Hsp70 is induced by exposure to mother’s milk. Hsp70 is found in mother’s milk, and increased Hsp70 transcription is induced by mother’s milk. This Hsp70 colocalizes with the tight junction protein ZO-1. Mother’s milk-induced Hsp70 may contribute to maintenance of barrier function in the face of oxidant stress. Further understanding of the means by which mother’s milk increases Hsp70 in the ileum will allow potential means of strengthening the intestinal barrier in at-risk preterm infants.

Aim Strong evidence reveals important differences between cancers in the proximal vs. distal colon. Animal models of metastatic colon cancer are available but with varying degrees of reproducibility and several important limitations. We explored whether there were regional differences in the location of murine colon cancers and assessed the utility of murine models to explore the biological basis for such differences. Methods We re-analyzed data from our previous studies to assess the regional distribution of murine colon cancer. In survival surgery experiments, we injected HT-29 human colon cancer cells into the wall of the cecum or distal colon of Nu(NCr)-Foxn1nu or NOD.Cg-PrkdcscidIl2rgTim1Wji/SzJ mice and compared the development of primary tumors and metastases. Results Within 7-17 weeks after intramural cecal injection of HT-29 cells, eight mice failed to develop solid primary tumors or metastases. In contrast, within four weeks after cell injection into the distal colon, 13 mice developed metastases - 12 mice developed subcutaneous metastases; of these, four developed liver metastases and one developed both liver and lung metastases. One mouse developed liver metastases only. Histological examination confirmed these lesions were adenocarcinomas. Conclusion Our findings reveal the preferential growth of murine colon neoplasia and invasive human orthotopic xenografts in the distal mouse colon. The new approach of injecting cells into the distal colon wall results in a pattern of colon cancer development that closely mimics the progression of metastatic colon cancer in humans. This novel model of colon neoplasia has great potential for exploring anatomical differences in colon cancer and testing novel therapeutics.

Mucosal inflammation, through cytokines such as interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha), has many effects on the intestinal epithelium, including selective translational inhibition of the cytoprotective protein heat shock protein 70 (Hsp70). To further elucidate the mechanisms underlying this effect, we examined the role of stress granules in mediating the actions of these proinflammatory cytokines. Using conditionally immortalized young adult mouse colonic epithelial cells, we demonstrate that IFN-gamma and TNF-alpha, which upregulate eukaryotic initiation factor-alpha (eIF-2alpha) phosphorylation and reduce Hsp70 translation, significantly enhance stress granule formation in heat-shocked intestinal epithelial cells. The IFN-gamma and TNF-alpha effects in upregulation of stress granule formation and downregulation of Hsp70 were eIF-2alpha dependent, and the effect could be negated by blocking eIF-2alpha phosphorylation with use of an RNA-dependent protein kinase inhibitor. Correspondingly, IFN-gamma and TNF-alpha increased binding of cytoplasmic proteins to the 3'-untranslated region of Hsp70 mRNA, suggesting specific recruitment of Hsp70 to stress granules as the mechanism of IFN-gamma and TNF-alpha inhibition of Hsp70 translation. We thus report a novel linkage between inflammatory cytokine production, stress granule formation, and Hsp70 translation inhibition, providing additional insights into the response of intestinal epithelial cells to inflammatory stress.

Surface carbonization of Si(1 0 0) using C 2 H 2 as the carbon source was performed in a cold-wall-type chemical vapor deposition reactor at a low pressure of 5 Torr. The carbonization process as a function of C 2 H 2 partial pressure and treatment time was investigated using X-ray photoemission spectroscopy. It was found that in comparison with a complete transformation to SiC surface on Si(1 1 1) by 8 min treatment of 5×10 −2 Torr C 2 H 2 at 1343 K, the carbonization on Si(1 0 0) under the same condition forms excessive carbon, plausibly due to the larger C 2 H 2 adsorption heat on Si(1 0 0) surface. Reducing C 2 H 2 partial pressure to 1.8×10 −3 Torr and treatment time to 2 min was enough for Si(1 0 0) to form a saturated carbide layer of about 2.0 nm in thickness. Subsequent 3C–SiC(1 0 0) epitaxial film growth was found successful especially on a 10 s carbonization-treated surface that has the least amount of excessive carbon.

author, Bacteria use quorum sensing molecules (QSMs) to communicate within as well as across species, however, the effects of QSM on eukaryotic host cells are less understood. We report that the quorum-sensing pentapeptide, competence and sporulation factor (CSF), of a Gram-positive bacterium Bacillus subtilis, activates key survival pathways including p38 MAP kinase and protein kinase B (Akt) in intestinal epithelial cells and also induces cytoprotective heat shock proteins (Hsps), the latter which prevent oxidant-induced intestinal epithelial cell injury and loss of barrier function. These effects of CSF depend on its uptake by an apical membrane organic cation transporter-2 (OCTN2). OCTN2-transported CSF therefore serves as an example of a unique mechanism of host-bacterial interactions allowing the host to monitor changes in colonic flora behavior or composition.

Background Compromised colonic butyrate production resulting from low dietary fiber or altered gut microbiota may promote colon neoplasia. Previous reports indicate these actions are mediated in part by altered levels of miRNAs, including suppressed expression of the oncogenic miR-17-92a cluster. Here, we sought to identify the mechanisms underlying these effects of butyrate in colon cancer. Methods miR-92a levels were measured in archived human colon cancer and adjacent normal colon specimens by microarray and quantitative RT-PCR (qPCR). The effects of butyrate and other histone deacetylase inhibitors (suberoylanilide hydroxamic acid (SAHA) and valproic acid) on primary (pri-miR17-92a), precursor and mature miR-92a were analyzed in HCT-116 and HT-29 human colon cancer cells using qPCR. The effects of butyrate, SAHA and valproic acid on protein levels of c-Myc, Drosha and p57 were measured in HCT-116 cells using immunoblotting. Regulation of C13orf25 promoter activity by butyrate was analyzed by luciferase reporter assay using modified pGL3 constructs containing a wild-type or mutated c-Myc binding site. Expression of c-Myc was modulated using siRNA or adenovirus vectors. p57 mRNA and protein were measured before and after transfection with miR-92a-mimic molecules. Following butyrate treatment and miR-92a-mimic transfection, apoptosis was analyzed by TUNEL staining and caspase-3 immunoblotting. Results Microarray, confirmed by qPCR, revealed a seven-fold increase in miR-92a levels in sporadic human colon cancer tissue compared to adjacent normal colon. Treating human colon cancer cells with butyrate reduced the levels of pri-miR17-92a, precursor and mature miR-92a, as well as c-Myc. SAHA and valproic acid had similar effects. Mutation of the c-Myc binding site diminished butyrate’s inhibitory effects on C13orf25 promoter activity. Silencing c-Myc expression reduced miR-92a levels. c-Myc over-expression neutralized butyrate-induced attenuation of pri-miR17-92a. Exogenous miR-92a inhibited butyrate-induced p57 expression and reversed the beneficial actions of butyrate on colon cancer cell proliferation and apoptosis. Conclusions Our findings identify a novel cellular mechanism whereby butyrate inhibits miR-92a transcription by reducing c-Myc, thus augmenting p57 levels. These actions diminish colon cancer cell proliferation and stimulate apoptosis. This newly described regulation of oncogenic miRNA biogenesis expands our understanding of colon cancer cell biology and identifies novel therapeutic targets.

Single-crystalline InN nanobelts have been synthesized using Au as the catalyst by a guided-stream thermal chemical vapor deposition technique. The resultant InN nanobelts typically have widths ranging from 20 to 200 nm, a width to thickness ratio of 2-10, and lengths of up to several tens of micrometers. Structural analysis shows that these InN nanobelts have a wurtzite structure and exhibit a rectangular cross section with self-selective facets, i.e., the nanobelts are enclosed only by ±(001) and ±(110) planes with [110] being the exclusive growth direction along their long axis. This facet selectivity can be understood by the differences in the surface energies of the different facets. Photoluminescence (PL) spectra of InN nanobelts show a sharp infrared emission peak at 0.76 eV with a full width at half maximum of 14 meV, narrower than the values reported for InN epilayers. The integrated PL intensity is found to increase linearly with the excitation power, which suggests that the observed PL can be attributed to direct band-to-band emission.

Surface carbonization of Si(1 1 1) using C 2 H 2 as the carbon source was performed at 1343 K and 5 Torr in a thermal chemical vapor deposition reactor. The evolution of the carbonization process as a function of the C 2 H 2 treatment time was investigated using atomic force microscopy and X-ray photoemission spectroscopy analytical techniques. It was found that at a C 2 H 2 partial pressure of 5.0×10 −2 Torr, the initial SiC nucleation proceeds to increase the surface roughness up to 0.2 nm after 5 min carbonization. When the carbonization is performed up to 8 min, the SiC nuclei saturate, reducing the surface roughness back to its original value at a saturation SiC thickness of about 1.4 nm.Subsequent SiC(1 1 1) epitaxial growth on the 8 min-carbonization surface was found to have a smooth surface morphology and void-free interface.

We report the optoelectronic device properties of individual Au–silica hybrid nanowires prepared by microwave plasma enhanced chemical vapor deposition. Due to the surface plasmon resonance (SPR) effect the photo-responsivity peak strongly depends on the shape of the embedded gold nanostructures in the silica nanowire in which the shape can be modified by controlling the growth time of Au–silica nanowires. Finite difference time domain (FDTD) simulation shows that the electric field distribution profiles of Au–silica hybrid nanowires support the photo-responsivity spectrum results. The photodetector performance of the Au-NPs@silica nanowire is investigated. The single Au-NPs@silica nanowire exhibits unique photo-responsivity in the visible range (500 nm), high selectivity, high photoconductive gain, and very fast rise (141 μs) and decay (298 μs) time constants. Furthermore, the mechanism for the high photoconductive gain is also discussed. This result implies that the Au-NPs@silica nanowire can be applied for future nanoscale optoelectronic devices.

Colonic microbiota ferment non-absorbed dietary fiber to produce prodigious amounts of short chain fatty acids (SCFAs) that benefit the host through a myriad of metabolic, trophic, and chemopreventative effects. The chemopreventative effects of the SCFA butyrate are, in part, mediated through induction of p21 gene expression. In this study, we assessed the role of microRNA(miRNA) in butyrate's induction of p21 expression. The expression profiles of miRNAs in HCT-116 cells and in human sporadic colon cancers were assessed by microarray and quantitative PCR. Regulation of p21 gene expression by miR-106b was assessed by 3' UTR luciferase reporter assays and transfection of specific miRNA mimics. Butyrate changed the expression of 44 miRNAs in HCT-116 cells, many of which were aberrantly expressed in colon cancer tissues. Members of the miR-106b family were decreased in the former and increased in the latter. Butyrate-induced p21 protein expression was dampened by treatment with a miR-106b mimic. Mutated p21 3'UTR-reporter constructs expressed in HCT-116 cells confirmed direct miR-106b targeting. Butyrate decreased HCT-116 proliferation, an effect reversed with the addition of the miR-106b mimic. We conclude that microbe-derived SCFAs regulate host gene expression involved in intestinal homeostasis as well as carcinogenesis through modulation of miRNAs.

Cytoprotective heat shock proteins (Hsps) are critical for intestinal homeostasis and are known to be decreased in inflammatory bowel diseases. Signals responsible for maintenance of Hsp expression are incompletely understood. In this study, we find that Hsp25/27 and Hsp70 protein expressions are differentially regulated along the longitudinal length of the large intestine, being highest in the proximal colon and decreasing to the distal colon. This longitudinal gradient was similar in both conventionally colonized mouse colon as well as biopsies of human proximal and distal colon but was abolished in the colon of germ-free mice, suggesting a role of intestinal microbiota in the Hsp regional expression. Correspondingly, analysis of 16S ribosomal RNA genes of bacteria from each colonic segment indicated increased bacterial richness and diversity in the proximal colon. The mechanism of regulation is transcriptional, as Hsp70 mRNA followed a similar pattern to Hsp70 protein expression. Lysates of mucosa-associated bacteria from the proximal colon stimulated greater Hsp25 and Hsp70 mRNA transcription and subsequent protein expression in intestinal epithelial cells than did lysates from distal colon. In addition, transrectal administration of cecal contents stimulated Hsp25 and Hsp70 expression in the distal colon. Thus host-microbial interactions resulting in differential Hsp expression may have significant implications for the maintenance of intestinal homeostasis and possibly for development of inflammatory diseases of the bowel.

Author, Background: The organic cation transporter OCTN2 is located on the IBD5 risk allele and has been implicated in the pathogenesis of inflammatory bowel diseases (IBD). It expressed in the apical membrane of gut epithelium and transports many solutes including bacteria-derived mediators which appear to be involved in host-microbial interactions. To explore its role further, we examined its expression and potential regulatory factors in human IBD and in experimental models. Methods: Human colonic epithelial cells (Caco2BBE) were used to investigate effects of inflammatory mediators on OCTN2 activity and expression. Apical membrane expression of OCTN2 was assessed by surface biotinylation. Rag-1-/-deficient mice were used to determine the potential role of adaptive immune cells in the regulation of intestinal OCTN2 expression. C57Bl/6 mice were treated with the pro-inflammatory cytokines, IFN- and TNF-, to determine expression and activity of OCTN2. OCTN2 expression in human IBD specimens was assessed by Western blotting and immunohistochemistry. Results: OCTN2 activity and expression are regulated by the state of intestinal inflammation. OCTN2 expression in colonic tissues of Rag-1-/-deficient mice was significantly reduced. Treatment with IFN- and TNF- increased intestinal OCTN2 expression, particularly in the colon. IFN- increased both total and apical membrane expression of OCTN2, whereas TNF- stimulated apical expression. Similar results were observed in Caco2BBE cells. Colonic epithelial OCTN2 expression was increased in actively inflamed areas of both Crohn’s disease and ulcerative colitis. Conclusions: Intestinal epithelial OCTN2 expression is increased by intestinal inflammation, most likely through increased levels of proinflammatory cytokines. These findings suggest that OCTN2 may be involved in the restoration of intestinal homeostasis under conditions of inflammation-associated stress.

Although the inducible heat shock protein 70 (Hsp70) is essential for maintaining intestinal homeostasis in colitis, it is translationally downregulated in inflamed colonic mucosa, paradoxically rendering the gut more susceptible to injury. We examined the basis for this process by analyzing the role of untranslated regions (UTR) of Hsp70 mRNA in inflammation-associated downregulation in vitro and in vivo. Using luciferase-reporter assays in young adult mouse intestinal epithelial cells, we determined that cytokine-induced translational inhibition of Hsp70 mRNA was mediated by the 3′UTR, but not 5′UTR. In vivo, dextran sodium sulfate (DSS) colitis was induced in wild-type (WT) and villin-promoter regulated “UTR-less” Hsp70 transgenic (TG) mice, the latter exhibiting intestinal epithelial-specific transgene expression. Progressive downregulation of colonic Hsp70 protein expression was observed in WT, but not in TG, mice with increasing severity of mucosal inflammation, confirming the essential role of the 3′UTR in mediating inflammation-associated downregulation of Hsp70. Hsp70 TG mice demonstrated significantly lower endoscopic and histological inflammation scores in DSS-induced colitis than WT. In conclusion, downregulation of Hsp70 expression in inflamed mucosa is mediated by translational inhibition requiring the 3′UTR, resulting in increased mucosal injury. By forcing intestinal epithelial-specific Hsp70 expression in vivo, the severity of experimentally induced colitis was significantly reduced.

Growth and luminescence properties of InN nanobelts (InNNBs) and InGaN nanowires (NWs) by MOCVD and thermal CVD will be presented, along with their relation and difference to thin film counterparts. While there is a growing acceptance of the low band gap (0.6-0.7 eV) of InN, the optical properties of the actual samples still suffered, presumably due to the difficulty in obtaining high-quality samples and/or controlling their defect and carrier concentrations. However, the free-standing nanobelts can be nearly defect-free, allowing an excellent opportunity for fundamental investigations on unique dimensionality. InNNBs show photoluminescence (PL) in IR with peak width of 14 meV, the sharpest reported to date for InN. Interestingly, with increasing excitation intensity, InNNBs reveal an anomalously large blueshift in PL, compared to thin films; along with a decrease in the phonon frequencies as evident by Raman measurements. Surface band bending, converse piezoelectric effect, and photoelastic effects are employed to explain these behaviors. As for InGaN NWs, both In-rich and Ga-rich ternary nanowires have been synthesized by simply varying growth temperature. Morphological and structural characterizations reveal a phase-separated microstructure wherein the isovalent heteroatoms are self-aggregated, forming self assembled quantum dots (SAQDs) embedded in NWs. The SAQDs are observed to dominate the emission behavior of both In-rich and Ga-rich nanowires, which has been explained by proposing a multi-level band schema.

BACKGROUND Heat shock protein 70 (Hsp70) regulates protein biosynthesis and refolding of denatured proteins. Since Hsp70 participates in recovery from stress injury, we examined the effect of Hsp70 genetic deletion in the azoxymethane (AOM)/dextran sulfate sodium (DSS) model of inflammation and colon cancer. METHODS Hsp70 mutant mice (Hsp70.1(-/-)/70.3(-/-)) and wild-type (WT) littermates received AOM and three cycles of DSS and were killed 24 weeks later. Tumors were graded for histology and immunostained for p53, adenomatous polyposis coli, beta-catenin, cyclooxygenase-2 (Cox-2) and inducible nitric oxide synthase (iNOS) and sequenced for p53 mutations. RESULTS Elevated adenomas developed in 4/10 WT mice with no dysplasia in adjacent mucosa. In contrast, 7/8 Hsp70 knock out (KO) mice developed chronic mucosal inflammation and multifocal areas of flat dysplasia and 4/8 progressed to invasive carcinomas arising in a background of flat dysplastic mucosa. These differences in the incidence of flat dysplasia and invasive cancers were significant (P < 0.05). Nuclear p53 was stronger in Hsp70 KO tumors compared with WT tumors, and sequencing confirmed p53 mutations in 2/5 tumors from Hsp70(-/-) versus 0/5 in WT mice. In Hsp70 WT tumors, beta-catenin was predominantly nuclear, compared with membranous beta-catenin in Hsp70(-/-) tumors, suggesting that Hsp70 regulates beta-catenin in colonic tumorigenesis. Cox-2 and iNOS levels were increased in tumors from Hsp70(-/-) mice compared with Hsp70 WT tumors. CONCLUSIONS Hsp70-deleted mice treated with AOM/DSS develop flat invasive colonic tumors that mimic many histological and molecular features of ulcerative colitis colon cancer. This model will be useful to dissect the role of Hsp70 in inflammatory bowel disease colon cancer.

Background & Aims: Inducible heat shock proteins (iHsp), Hsp25/27 and Hsp70, play essential roles in protecting cells against stress and, in intestinal mucosal inflammation, potentially lessening the extent and severity of injury. We examined the expression and regulation of iHsp in human and experimental inflammatory bowel diseases (IBD) and in vitro. Methods: iHsp expression and regulation were assessed in normal and IBD colonic biopsy specimens, IL-10−/− mice, and young adult mouse colonic epithelial cells by immunohistochemistry, Western blot, and real-time polymerase chain reaction (PCR). Phosphorylation of double-stranded RNA-dependent protein kinase (PKR) and eukaryotic initiation factor-2α (eIF-2α) was determined by Western blot. Results: Hsp25/27 and Hsp70 levels were selectively reduced in areas of active mucosal inflammation associated with human IBD and IL-10−/− mice with colitis. Wild-type mice treated in vivo with interferon (IFN)-γ + tumor necrosis factor (TNF)-α also demonstrated reduced colonic Hsp25/27 and Hsp70. In young adult mouse colonic epithelial cells, IFN-γ+TNF-α inhibited heat induction of Hsp25/27 and Hsp70, an effect not associated with changes in iHsp messenger RNA or protein half-lives but caused by suppressed de novo iHsp synthesis. IFN-γ+TNF-α cotreatment activated PKR, resulting in phosphorylation and inactivation of eIF-2α, an essential factor in protein translation. These effects were not due to induced apoptosis and could be negated by PKR-inhibitor and short interfering RNA to PKR. Increased phosphorylation of PKR and eIF-2α were also observed in active IBD tissues. Conclusions: Mucosal inflammation is associated with iHsp down-regulation, an effect that appears mediated by translational down-regulation by proinflammatory cytokines. In the context of IBD, we propose that this mechanism contributes to the severity, extent, and persistence of inflammation-induced mucosal injury.

We have studies of the changes in the surface states of carbonized Si(111) substrates treated under various temperature programs prior to high-temperature 3C-SiC film growth in a low pressure chemical vapor deposition system using SiH4, C2H2, and H2 as reactant gases. The carbonized Si surface underwent a change in bonding from SiC to disordered graphite, together with the formation of etch pits, when heated directly from the carbonization temperature of 1343 K to the growth temperature of 1523 K under a H2 flow over a period of 5 min; this transformation deteriorated the quality of the subsequent 3C-SiC growth. In contrast, a void-free stoichiometric SiC surface was preserved when we inserted a rapid cooling step, to near room temperature, under a H2 flow of 352 sccm within a period of 15 min after shutting off the C2H2 gas flow at the end of the surface carbonization process. The sharp temperature decrease in this program sealed off the carbonized substrate surface and, thus, led to a high film quality for subsequent 3C-SiC(111) growth.

A Taiwan-based team led by Kuei-Hsien Chen has improved the room-temperature gas-sensing properties of silica nanowire-based systems by incorporating gold nanoparticles inside the nanowire in a ‘peas-in-a-pod’ manner. Upon shining light on the device, surface plasmon resonance occurs at gold nanoparticles that absorb the visible light (from a 532 nm laser) at room temperature. Under this irradiation, a gold-embedded silica nanowire undergoes photogeneration of electrons and holes at a higher rate than its plain silica counterpart. As a result, the nanowire's conductivity is enhanced and the sensing of oxygen at the wire's surface is facilitated by the molecule's interaction with photogenerated electrons, while its recovery (desorption) is improved by the presence of the holes. As neither gold nor silica nanoparticles are known to be toxic, the gold-silica nanowire system holds promise for measuring oxygen in biological and medical applications.

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We report the enhanced electrical conductivity properties of single gold-peapodded amorphous silica nanowires synthesized using microwave plasma enhanced chemical vapor deposition. Dark conductivity of the gold-peapodded silica nanowires can be adjusted by controlling the number of incorporated metal nanoparticles. The temperature-dependent conductivity measurement reveals that the band tail hopping mechanism dominates the electron transport in the gold-peapodded silica nanowires. The high conductivity in the nano-peapodded nanowires with more embedded gold-nanoparticles can be explained by the higher density of hopping states and shorter hopping distance. These Au-embedded amorphous silica nanowires have provided a new approach to enhance not only the electron conduction, but also the chemical-sensor response/sensitivity.

The surface plasmon (SP) excitations of gold/silica nanowire, investigated by electron energy-loss spectroscopy in conjunction with scanning transmission electron microscopy, are found to be anisotropic with stronger SP intensities observed along the transverse direction of the nanowire. This indicates that the charge carriers generated near the surface of the nanowires by the decay of SP resonance play a significant role to the enhanced photoconductivity. This conclusion is reaffirmed by the polarization dependent photoconductivity measurement.

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