Redistribution of β-catenin in response to EGF and lithium signalling in human oesophageal squamous carcinoma cell lines

BACKGROUND: The β-catenin link between membrane-bound cadherins and the actin cytoskeleton regulates cell adhesion and consequently metastasis. Abnormal stabilisation of β-catenin enhances its transcriptional activities. Factors affecting β-catenin's functions are important in understanding metastatic diseases such as oesophageal squamous cell carcinoma (SCC). RESULTS: In human oesophageal SCCs β-catenin localises predominantly to the plasma membrane. The presence of free β-catenin in the cytoplasm/nucleus was low. This indicates that β-catenin's activities are skewed towards cell-cell adhesion in these oesophageal SCCs. Exposure to EGF or Li alone, produced a slight increase in membrane concentrations but only Li induced β-catenin stabilisation in the cytoplasm. In combination, EGF and Li decreased membrane-associated β-catenin, concomitantly increasing cytoplasmic concentrations. Convergence of these signalling pathways appears to induce a β-catenin shift from the membrane into the cytoplasm. CONCLUSION: Therefore, although the adhesive role of β-catenin appears to be intact, exogenous signals increase the stability of free β-catenin thereby reducing cell-cell adhesion in these tumours

Climate Variability and Ross River Virus Transmission in Townsville Region, Australia 1985 to 1996

Background How climate variability affects the transmission of infectious diseases at a regional level remains unclear. In this paper, we assessed the impact of climate variation on the Ross River virus (RRv) transmission in the Townsville region, Queensland, north-east Australia. Methods Population-based information was obtained on monthly variations in RRv cases, climatic factors, sea level, and population growth between 1985 and 1996. Cross-correlations were computed for a series of associations between climate variables (rainfall, maximum temperature, minimum temperature, relative humidity and high tide) and the monthly incidence of RRv disease over a range of time lags. The impact of climate variability on RRv transmission was assessed using the seasonal auto-regressive integrated moving average (SARIMA) model. Results There were significant correlations of the monthly incidence of RRv to rainfall, maximum temperature, minimum temperature and relative humidity, all at a lag of 2 months, and high tide in the current month. The results of SARIMA models show that monthly average rainfall (β=0.0012, p=0.04) and high tide (β=0.0262, p=0.01) were significantly associated with RRv transmission, although temperature and relative humidity did not seem to have played an important role in the Townsville region. Conclusions Rainfall, and high tide were likely to be key determinants of RRv transmission in the Townsville region

Retinoic acid-responsive CD8 effector T-cells are selectively increased in IL-23-rich tissue in gastrointestinal GvHD.

Gastrointestinal (GI) graft-versus-host disease (GvHD) is a major barrier in allogeneic hematopoietic stem-cell transplantation (AHST). The metabolite retinoic acid (RA) potentiates GI-GvHD in mice via alloreactive T-cells expressing the RA-receptor-alpha (RARα), but the role of RA-responsive cells in human GI-GvHD remains undefined. We therefore used conventional and novel sequential immunostaining and flow cytometry to scrutinize RA-responsive T-cells in tissues and blood of AHST patients and characterize the impact of RA on human T-cell alloresponses. Expression of RARα by human mononuclear cells was increased after RA exposure. RARαhi mononuclear cells were increased in GI-GvHD tissue, contained more cellular RA-binding proteins, localized with tissue damage and correlated with GvHD severity and mortality. Using a targeted candidate protein approach we predicted the phenotype of RA-responsive T-cells in the context of increased microenvironmental IL-23. Sequential immunostaining confirmed the presence of a population of RARahi CD8 T-cells with the predicted phenotype, co-expressing the effector T-cell transcription factor T-bet and the IL-23-specific receptor. These cells were increased in GI- but not skin-GvHD tissues and were also selectively expanded in GI-GvHD patient blood. Finally, functional approaches demonstrated RA predominantly increased alloreactive GI-tropic RARahi CD8 effector T-cells, including cells with the phenotype identified in vivo. IL-23-rich conditions potentiated this effect by selectively increasing b7 integrin expression on CD8 effector T-cells and reducing CD4 T-cells with a regulatory cell phenotype. In conclusion we have identified a population of RA-responsive effector T-cells with a distinctive phenotype which are selectively expanded in human GI-GvHD and represent a potential new therapeutic target

Self-employment in an equilibrium model of the labor market

Self-employed workers account for between 8% and 30% of participants in the labor markets of OECD countries, Blanch ower (2004). This paper develops and estimates a general equilibrium model of the labor market that accounts for this sizable proportion. The model incorporates self-employed workers, some of whom hire paid employees in the market. Employment rates and earnings distributions are determined endogenously and are estimated to match their empirical counterparts. The model is estimated using the British Household Panel Survey (BHPS). The model is able to estimate nonpecuniary amenities associated with employment in di erent labor market states, accounting for both different employment dynamics within state and the misreporting of earnings by self-employed workers. Structural parameter estimates are then used to assess the impact of an increase in the generosity of unemployment benefits on the aggregate employment rate. Findings suggest that modeling the self-employed, some of whom hire paid employees implies that small increases in unemployment benefits leads to an expansion in aggregate employment

Evidence for a Prepore Stage in the Action of Clostridium perfringens Epsilon Toxin

Clostridium perfringens epsilon toxin (ETX) rapidly kills MDCK II cells at 37°C, but not 4°C. The current study shows that, in MDCK II cells, ETX binds and forms an oligomeric complex equally well at 37°C and 4°C but only forms a pore at 37°C. However, the complex formed in MDCK cells treated with ETX at 4°C has the potential to form an active pore, since shifting those cells to 37°C results in rapid cytotoxicity. Those results suggested that the block in pore formation at 4°C involves temperature-related trapping of ETX in a prepore intermediate on the MDCK II cell plasma membrane surface. Evidence supporting this hypothesis was obtained when the ETX complex in MDCK II cells was shown to be more susceptible to pronase degradation when formed at 4°C vs. 37°C; this result is consistent with ETX complex formed at 4°C remaining present in an exposed prepore on the membrane surface, while the ETX prepore complex formed at 37°C is unaccessible to pronase because it has inserted into the plasma membrane to form an active pore. In addition, the ETX complex rapidly dissociated from MDCK II cells at 4°C, but not 37°C; this result is consistent with the ETX complex being resistant to dissociation at 37°C because it has inserted into membranes, while the ETX prepore readily dissociates from cells at 4°C because it remains on the membrane surface. These results support the identification of a prepore stage in ETX action and suggest a revised model for ETX cytotoxicity, i) ETX binds to an unidentified receptor, ii) ETX oligomerizes into a prepore on the membrane surface, and iii) the prepore inserts into membranes, in a temperature-sensitive manner, to form an active pore

Susceptibility of hamsters to clostridium difficile isolates of differing toxinotype

Clostridium difficile is the most commonly associated cause of antibiotic associated disease (AAD), which caused ~21,000 cases of AAD in 2011 in the U.K. alone. The golden Syrian hamster model of CDI is an acute model displaying many of the clinical features of C. difficile disease. Using this model we characterised three clinical strains of C. difficile, all differing in toxinotype; CD1342 (PaLoc negative), M68 (toxinotype VIII) and BI-7 (toxinotype III). The naturally occurring non-toxic strain colonised all hamsters within 1-day post challenge (d.p.c.) with high-levels of spores being shed in the faeces of animals that appeared well throughout the entire experiment. However, some changes including increased neutrophil influx and unclotted red blood cells were observed at early time points despite the fact that the known C. difficile toxins (TcdA, TcdB and CDT) are absent from the genome. In contrast, hamsters challenged with strain M68 resulted in a 45% mortality rate, with those that survived challenge remaining highly colonised. It is currently unclear why some hamsters survive infection, as bacterial and toxin levels and histology scores were similar to those culled at a similar time-point. Hamsters challenged with strain BI-7 resulted in a rapid fatal infection in 100% of the hamsters approximately 26 hr post challenge. Severe caecal pathology, including transmural neutrophil infiltrates and extensive submucosal damage correlated with high levels of toxin measured in gut filtrates ex vivo. These data describes the infection kinetics and disease outcomes of 3 clinical C. difficile isolates differing in toxin carriage and provides additional insights to the role of each toxin in disease progression

To bite or not to bite! A questionnaire-based survey assessing why some people are bitten more than others by midges

BACKGROUND: The Scottish biting midge, Culicoides impunctatus, responsible for more than 90% of biting attacks on human beings in Scotland, is known to demonstrate a preference for certain human hosts over others. METHODS: In this study we used a questionnaire-based survey to assess the association between people's perception of how badly they get bitten by midges and their demographic, lifestyle and health related characteristics. RESULTS: Most people (85.8%) reported being bitten sometimes, often or always with only 14.2% reporting never being bitten by midges when in Scotland. There was no association between level of bites received and age, smoking, diet, exercise, medication, eating strongly flavoured foods or alcohol consumption. However, there was a strong association between the probability of being bitten and increasing height (in men) and BMI (in women). A large proportion of participants (33.8%) reported experiencing a bad/severe reaction to midge bites while 53.1% reported a minor reaction and 13.1% no reaction at all. Also, women tend to react more than men to midge bites. Additionally, the results indicated that the susceptibility to being bitten by midges is hereditary. CONCLUSIONS: This study suggests that midges prefer to bite men that are tall and women that have a large BMI, and that the tendency for a child to be bitten or not could be inherited from their parent. The study is questionnaire-based; therefore, the interpretation of the results may be limited by the subjectivity of the answers given by the respondents. Although the results are relevant only to the Scottish biting midge, the approach used here could be useful for investigating human-insect interactions for other insects, particularly those which transmit pathogens that cause disease

Tumor Susceptibility Gene 101 (TSG101) Is a Novel Binding-Partner for the Class II Rab11-FIPs

The Rab11-FIPs (Rab11-family interacting proteins; henceforth, FIPs) are a family of Rab11a/Rab11b/Rab25 GTPase effector proteins implicated in an assortment of intracellular trafficking processes. Through proteomic screening, we have identified TSG101 (tumor susceptibility gene 101), a component of the ESCRT-I (endosomal sorting complex required for transport) complex, as a novel FIP4-binding protein, which we find can also bind FIP3. We show that α-helical coiled-coil regions of both TSG101 and FIP4 mediate the interaction with the cognate protein, and that point mutations in the coiled-coil regions of both TSG101 and FIP4 abrogate the interaction. We find that expression of TSG101 and FIP4 mutants cause cytokinesis defects, but that the TSG101-FIP4 interaction is not required for localisation of TSG101 to the midbody/Flemming body during abscission. Together, these data suggest functional overlap between Rab11-controlled processes and components of the ESCRT pathway

Epigenetic and metabolic reprogramming of fibroblasts in Crohn's disease strictures reveals histone deacetylases as therapeutic targets.

BACKGROUND & AIMS: No effective therapeutic intervention exists for intestinal fibrosis in Crohn's disease [CD]. We characterised fibroblast subtypes, epigenetic and metabolic changes, and signalling pathways in CD fibrosis to inform future therapeutic strategies. METHODS: We undertook immunohistochemistry, metabolic, signalling pathway and Epigenetic [Transposase-Accessible Chromatin using sequencing] analyses associated with collagen production in CCD-18Co intestinal fibroblasts and primary fibroblasts isolated from stricturing [SCD] and non-stricturing [NSCD] CD small intestine. SCD/ NSCD fibroblasts were cultured with TGFβ and valproic acid [VPA]. RESULTS: Stricturing CD was characterised by distinct histone deacetylase [HDAC] expression profiles, particularly HDAC1, HDAC2, and HDAC7. As a proxy for HDAC activity, reduced numbers of H3K27ac+ cells were found in SCD compared to NSCD sections. Primary fibroblasts had increased extracellular lactate [increased glycolytic activity] and intracellular hydroxyproline [increased collagen production] in SCD compared to NSCD cultures. The metabolic effect of TGFβ-stimulation was reversed by the HDAC inhibitor VPA. SCD fibroblasts appear "metabolically primed" and responded more strongly to both TGFβ and VPA. Treatment with VPA revealed TGFβ-dependent and independent Collagen-I production in CCD-18Co cells and primary fibroblasts. VPA altered the epigenetic landscape with reduced chromatin accessibility at the COL1A1 and COL1A2 promoters. CONCLUSIONS: Increased HDAC expression profiles, H3K27ac hypoacetylation, a significant glycolytic phenotype, and metabolic priming, characterise SCD-derived as compared to NSCD fibroblasts. Our results reveal a novel epigenetic component to Collagen-I regulation and TGFβ-mediated CD fibrosis. HDAC inhibitor therapy may 'reset' the epigenetic changes associated with fibrosis