Inhibitor of DNA-binding 4 contributes to the maintenance and expansion of cancer stem cells in 4T1 mouse mammary cancer cell line

The cancer stem cell (CSC) hypothesis proposes that CSCs are the root of cancer. CSC-targeted therapies may prevent cancer relapse and provide more effective treatment. The expression of aldehyde dehydrogenase 1, as assessed by the Aldefluor assay, has been recognized as a marker of CSCs in breast cancer. Inhibitors of DNA-binding proteins (IDs) have an important role in stem cell differentiation. In this study, we examined IDs necessary for the regulation of stem properties in Aldefluorpos 4T1 cells. When the expression profile of IDs in Aldefluorneg and Aldefluorpos 4T1 cells was compared, qRT-PCR analysis showed that ID4 expression was highly upregulated in Aldefluorpos 4T1 cells. In addition, knockdown of ID4 expression suppressed the properties of CSCs, including their sphere-forming ability and side population phenotype. The findings suggest that ID4 may be a therapeutic target for the treatment of advanced breast cancer

Proton Pump Inhibitors Inhibit Metformin Uptake by Organic Cation Transporters (OCTs)

Metformin, an oral insulin-sensitizing drug, is actively transported into cells by organic cation transporters (OCT) 1, 2, and 3 (encoded by SLC22A1, SLC22A2, or SLC22A3), which are tissue specifically expressed at significant levels in various organs such as liver, muscle, and kidney. Because metformin does not undergo hepatic metabolism, drug-drug interaction by inhibition of OCT transporters may be important. So far, comprehensive data on the interaction of proton pump inhibitors (PPIs) with OCTs are missing although PPIs are frequently used in metformin-treated patients. Using in silico modeling and computational analyses, we derived pharmacophore models indicating that PPIs (i.e. omeprazole, pantoprazole, lansoprazole, rabeprazole, and tenatoprazole) are potent OCT inhibitors. We then established stably transfected cell lines expressing the human uptake transporters OCT1, OCT2, or OCT3 and tested whether these PPIs inhibit OCT-mediated metformin uptake in vitro. All tested PPIs significantly inhibited metformin uptake by OCT1, OCT2, and OCT3 in a concentration-dependent manner. Half-maximal inhibitory concentration values (IC50) were in the low micromolar range (3–36 µM) and thereby in the range of IC50 values of other potent OCT drug inhibitors. Finally, we tested whether the PPIs are also transported by OCTs, but did not identify PPIs as OCT substrates. In conclusion, PPIs are potent inhibitors of the OCT-mediated metformin transport in vitro. Further studies are needed to elucidate the clinical relevance of this drug-drug interaction with potential consequences on metformin disposition and/or efficacy

TSLP-activated dendritic cells induce human T follicular helper cell differentiation through OX40-ligand.

T follicular helper cells (Tfh) are important regulators of humoral responses. Human Tfh polarization pathways have been thus far associated with Th1 and Th17 polarization pathways. How human Tfh cells differentiate in Th2-skewed environments is unknown. We show that thymic stromal lymphopoietin (TSLP)-activated dendritic cells (DCs) promote human Tfh differentiation from naive CD4 T cells. We identified a novel population, distinct from Th2 cells, expressing IL-21 and TNF, suggestive of inflammatory cells. TSLP-induced T cells expressed CXCR5, CXCL13, ICOS, PD1, BCL6, BTLA, and SAP, among other Tfh markers. Functionally, TSLP-DC-polarized T cells induced IgE secretion by memory B cells, and this depended on IL-4Rα. TSLP-activated DCs stimulated circulating memory Tfh cells to produce IL-21 and CXCL13. Mechanistically, TSLP-induced Tfh differentiation depended on OX40-ligand, but not on ICOS-ligand. Our results delineate a pathway of human Tfh differentiation in Th2 environments

Functional and expression analysis of the metal-inducible dmeRF system from Rhizobium legumionosarum bv. viciae

A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metallidurans has been identified in the genome of Rhizobium leguminosarum UPM791. The R. leguminosarum dmeF gene is located downstream of an open reading frame (designated dmeR) encoding a protein homologous to the nickel- and cobalt-responsive transcriptional regulator RcnR from Escherichia coli. Analysis of gene expression showed that the R. leguminosarum dmeRF genes are organized as a transcriptional unit whose expression is strongly induced by nickel and cobalt ions, likely by alleviating the repressor activity of DmeR on dmeRF transcription. An R. leguminosarum dmeRF mutant strain displayed increased sensitivity to Co(II) and Ni(II), whereas no alterations of its resistance to Cd(II), Cu(II), or Zn(II) were observed. A decrease of symbiotic performance was observed when pea plants inoculated with an R. leguminosarum dmeRF deletion mutant strain were grown in the presence of high concentrations of nickel and cobalt. The same mutant induced significantly lower activity levels of NiFe hydrogenase in microaerobic cultures. These results indicate that the R. leguminosarum DmeRF system is a metal-responsive efflux mechanism acting as a key element for metal homeostasis in R. leguminosarum under free-living and symbiotic conditions. The presence of similar dmeRF gene clusters in other Rhizobiaceae suggests that the dmeRF system is a conserved mechanism for metal tolerance in legume endosymbiotic bacteria

Chronic non-specific low back pain - sub-groups or a single mechanism?

Copyright 2008 Wand and O'Connell; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Low back pain is a substantial health problem and has subsequently attracted a considerable amount of research. Clinical trials evaluating the efficacy of a variety of interventions for chronic non-specific low back pain indicate limited effectiveness for most commonly applied interventions and approaches. Discussion: Many clinicians challenge the results of clinical trials as they feel that this lack of effectiveness is at odds with their clinical experience of managing patients with back pain. A common explanation for this discrepancy is the perceived heterogeneity of patients with chronic non-specific low back pain. It is felt that the effects of treatment may be diluted by the application of a single intervention to a complex, heterogeneous group with diverse treatment needs. This argument presupposes that current treatment is effective when applied to the correct patient. An alternative perspective is that the clinical trials are correct and current treatments have limited efficacy. Preoccupation with sub-grouping may stifle engagement with this view and it is important that the sub-grouping paradigm is closely examined. This paper argues that there are numerous problems with the sub-grouping approach and that it may not be an important reason for the disappointing results of clinical trials. We propose instead that current treatment may be ineffective because it has been misdirected. Recent evidence that demonstrates changes within the brain in chronic low back pain sufferers raises the possibility that persistent back pain may be a problem of cortical reorganisation and degeneration. This perspective offers interesting insights into the chronic low back pain experience and suggests alternative models of intervention. Summary: The disappointing results of clinical research are commonly explained by the failure of researchers to adequately attend to sub-grouping of the chronic non-specific low back pain population. Alternatively, current approaches may be ineffective and clinicians and researchers may need to radically rethink the nature of the problem and how it should best be managed

Interactive seminars or small group tutorials in preclinical medical education: results of a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Learning in small group tutorials is appreciated by students and effective in the acquisition of clinical problem-solving skills but poses financial and resource challenges. Interactive seminars, which accommodate large groups, might be an alternative. This study examines the educational effectiveness of small group tutorials and interactive seminars and students' preferences for and satisfaction with these formats.</p> <p>Methods</p> <p>Students in year three of the Leiden undergraduate medical curriculum, who agreed to participate in a randomized controlled trial (RCT, n = 107), were randomly allocated to small group tutorials (n = 53) or interactive seminars (n = 54). Students who did not agree were free to choose either format (n = 105). Educational effectiveness was measured by comparing the participants' results on the end-of-block test. Data on students' reasons and satisfaction were collected by means of questionnaires. Data was analyzed using student unpaired t test or chi-square test where appropriate.</p> <p>Results</p> <p>There were no significant differences between the two educational formats in students' test grades. Retention of knowledge through active participation was the most frequently cited reason for preferring small group tutorials, while a dislike of compulsory course components was mentioned more frequently by students preferring interactive seminars. Small group tutorials led to greater satisfaction.</p> <p>Conclusions</p> <p>We found that small group tutorials leads to greater satisfaction but not to better learning results. Interactive learning in large groups might be might be an effective alternative to small group tutorials in some cases and be offered as an option.</p

Crystal structure of the CusBA heavy-metal efflux complex of Escherichia coli

Gram-negative bacteria, such as Escherichia coli, expel toxic chemicals via tripartite efflux pumps spanning both the inner and outer membranes. The three parts are: 1) a membrane fusion protein connecting 2) a substrate-binding inner membrane transporter to 3) an outer membrane-anchored channel in the periplasmic space. A crystallographic model of this tripartite efflux complex has been unavailable simply because co-crystallization of different components of the system has proven to be extremely difficult. We previously described the crystal structures of both the inner membrane transporter CusA1 and membrane fusion protein CusB2 of the CusCBA efflux system3,4 from E. coli. We here report the co-crystal structure of the CusBA efflux complex, revealing the trimeric CusA efflux pump interacts with six CusB protomers at the upper half of the periplasmic domain. These six CusB molecules form a channel extending contiguously from the top of the pump. The affinity of the CusA and CusB interaction was found to be in the micromolar range. Finally, we predicted a three-dimensional structure of the trimeric CusC outer membrane channel, and develop a model of the tripartite efflux assemblage. This CusC3-CusB6-CusA3 model presents a 750 kDa efflux complex spanning the entire bacterial cell envelope to export Cu(I)/Ag(I) ions

Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport

Gram-negative bacteria, such as Escherichia coli, frequently utilize tripartite efflux complexes in the resistance-nodulation-cell division (RND) family to expel diverse toxic compounds from the cell.1,2 The efflux system CusCBA is responsible for extruding biocidal Cu(I) and Ag(I) ions.3,4 No prior structural information was available for the heavy-metal efflux (HME) subfamily of the RND efflux pumps. Here we describe the crystal structures of the inner membrane transporter CusA in the absence and presence of bound Cu(I) or Ag(I). These CusA structures provide important new structural information about the HME sub-family of RND efflux pumps. The structures suggest that the metal binding sites, formed by a three-methionine cluster, are located within the cleft region of the periplasmic domain. Intriguingly, this cleft is closed in the apo-CusA form but open in the CusA-Cu(I) and CusA-Ag(I) structures, which directly suggests a plausible pathway for ion export. Binding of Cu(I) and Ag(I) triggers significant conformational changes in both the periplasmic and transmembrane domains. The crystal structure indicates that CusA has, in addition to the three-methionine metal binding site, four methionine pairs - three located in the transmembrane region and one in the periplasmic domain. Genetic analysis and transport assays suggest that CusA is capable of actively picking up metal ions from the cytosol, utilizing these methionine pairs/clusters to bind and export metal ions. These structures suggest a stepwise shuttle mechanism for transport between these sites

Self-rated health, work characteristics and health related behaviours among nurses in Greece: a cross sectional study

BACKGROUND: Previous studies on self-rated health among nurses have indicated an association of low job satisfaction and stress in relation to poor self-rated health. The relationship between self rated health and the specific work characteristics and health related behaviours of nurses to our knowledge have not been adequately studied. OBJECTIVE: To investigate the health profile of nurses working in hospitals in North West Greece and to examine the associations between self rated health (SRH) and health related behaviours and work characteristics in this group of hospital employees. METHODS: A self-administered questionnaire was distributed to a random sample of 443 nurses working in all the hospitals in North West Greece. Regression analysis was used to examine the relationship of health related behaviours and work characteristics with self rated health among the nurses. RESULTS: A total of 353 responded to the questionnaire (response rate 80%) of which 311 (88%) were female and 42 (12%) male. The mean age (standard deviation) of the respondents was 36 years (5.6) and their mean years of working as nurses were 13.5 years (5.9). Almost half of the nurses' smoked, and about one third were overweight or obese. About 58% (206) of the nurses reported having poor health while 42% (147) reported having good health. Self-rated health was independently associated with gender, effort to avoid fatty foods and physical activity, according to multiple logistic regression analysis. CONCLUSION: The population studied presented a relatively poor health profile, and a high proportion of poor SRH. Though female gender and effort to avoid fatty foods were associated with poor SRH, and exercise and white meat consumption with good SRH, specific work characteristics were not associated with SRH