Transcription Factor NFE2L1 Decreases in Glomerulonephropathies after Podocyte Damage

Podocyte cellular injury and detachment from glomerular capillaries constitute a critical factor contributing to kidney disease. Notably, transcription factors are instrumental in maintaining podocyte differentiation and homeostasis. This study explores the hitherto uninvestigated expression of Nuclear Factor Erythroid 2-related Factor 1 (NFE2L1) in podocytes. We evaluated the podocyte expression of NFE2L1, Nuclear Factor Erythroid 2-related Factor 2 (NFE2L2), and NAD(P)H:quinone Oxidoreductase (NQO1) in 127 human glomerular disease biopsies using multiplexed immunofluorescence and image analysis. We found that both NFE2L1 and NQO1 expressions were significantly diminished across all observed renal diseases. Furthermore, we exposed human immortalized podocytes and ex vivo kidney slices to Puromycin Aminonucleoside (PAN) and characterized the NFE2L1 protein isoform expression. PAN treatment led to a reduction in the nuclear expression of NFE2L1 in ex vivo kidney slices and podocytes.

YAP Translocation Precedes Cytoskeletal Rearrangement in Podocyte Stress Response: A Podometric Investigation of Diabetic Nephropathy

Podocyte loss plays a pivotal role in the pathogenesis of glomerular disease. However, the mechanisms underlying podocyte damage and loss remain poorly understood. Although detachment of viable cells has been documented in experimental Diabetic Nephropathy, correlations between reduced podocyte density and disease severity have not yet been established. YAP, a mechanosensing protein, has recently been shown to correlate with glomerular disease progression, however, the underlying mechanism has yet to be fully elucidated. In this study, we sought to document podocyte density in Diabetic Nephropathy using an amended podometric methodology, and to investigate the interplay between YAP and cytoskeletal integrity during podocyte injury. Podocyte density was quantified using TLE4 and GLEPP1 multiplexed immunofluorescence. Fourteen Diabetic Nephropathy cases were analyzed for both podocyte density and cytoplasmic translocation of YAP via automated image analysis. We demonstrate a significant decrease in podocyte density in Grade III/IV cases (124.5 per 10⁶ μm³) relative to Grade I/II cases (226 per 10⁶ μm³) (Student's t-test, p < 0.001), and further show that YAP translocation precedes cytoskeletal rearrangement following injury. Based on these findings we hypothesize that a significant decrease in podocyte density in late grade Diabetic Nephropathy may be explained by early cytoplasmic translocation of YAP.

Abstract 2995: Dissecting renal cell carcinoma vulnerabilities: Using CRISPR/Cas9 to study resistance to glutaminase inhibition

The aim of this study was to identify genes, which when knock out confer resistance to a novel glutaminase inhibitor in Renal Cell Carcinoma (RCC). RCC represents around 3% of all malignancies worldwide, with its most common type, clear cell RCC (ccRCC), making up around 70-80% of all RCC. The most frequent genomic alteration in ccRCC involves loss of VHL gene in &gt;90% of ccRCC cases. Large-scale cancer genomics sequencing studies have identified several driver genes beyond VHL, particularly PBRM1 (40%), SETD2 (15%), and BAP1 (10%). RCC is characterised by significant tumour heterogeneity and inherent (in 25-30% cases) or acquired resistance to available chemotherapeutics. Glutamine addiction is a potential new therapeutic target for RCC as it has been recently shown not only to rely on glutamine for energy generation and maintenance of redox homeostasis, but also de novo pyrimidine synthesis. CB-839 is a small, orally administered reversible inhibitor of human kidney-type glutaminase (GLS). CB-839 is currently in early phase clinical trials and shows promising results. Given the significant incidence of resistance to previously approved therapies, we have applied a genome-scale CRISPR/Cas9 approach in a cell culture model of ccRCC (786-0 cell line) to identify candidate genes, which when knocked down confer resistance to CB-839. Next generation sequencing data analysis of drug-selected sgRNA library representation from two timepoints was performed using the MAGeCKFlute bioinformatics workflow. We conducted the screen in two biological replicates and verified successful genome-scale sgRNA library coverage at baseline in both cases. As a result, we identified candidate genes and pathways that are implicated in tumour metabolism, autophagy and metastasis. Additionally, this analysis identified KD genes, which in combination with CB-839 are synthetic lethal. We have prioritized the top 12 candidate genes, which we are validating in four cell lines (786-0, A498, A704 and Caki-1). After establishing CRISPR/Cas9 single gene knockdown (KD) cell lines, KD is confirmed using RT-qPCR and Western Blot, followed by functional analysis. KD cells were treated with increasing concentrations of the drug in parallel with a cell line containing a scrambled sgRNA to detect growth changes between the two. After in vitro validation, we performed ex vivo validation of the candidate hits. Our data show that the genome-scale CRISPR/Cas9 approach is effective in identifying candidates modulating drug resistance to CB-839.

Citation Format: Aleksandra M. Raczka, Paul A. Reynolds. Dissecting renal cell carcinoma vulnerabilities: Using CRISPR/Cas9 to study resistance to glutaminase inhibition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2995.

Abstract 4440: Genetic knockdown of the E3 ubiquitin ligase Itch increases pancreatic cell line sensitivity to cancer therapeutics: A comparison between different gene editing techniques

Introduction: E3 ligases are responsible for tagging ubiquitin onto substrates to either activate, relocate or target the substrate for degradation via the proteasome. Previous studies have shown that genetic knockdown of the E3 ubiquitin ligase Itch caused an increase in sensitivity to gemcitabine in pancreatic cancer models both in-vitro (cell lines) and in-vivo (mouse xenografts). Here we test the hypothesis that Itch knockdown sensitises pancreatic cell lines to existing cancer therapeutics, using both transient and stable knockdown methods.

Experimental Procedures: Knockdown of Itch in MiaPaCa2 (p53 mutant) and Capan 2 (p53 WT) cells was performed using both siRNA and CRISPR-Cas9 techniques; validated by western blot and RT-PCR. Alongside parental and scrambled controls, cells were treated with either doxorubicin, gemcitabine or γ-radiation. For doxorubicin and gemcitabine treatment, cells were exposed to the drug for 24 hours before it was removed. In the case of irradiation; cells were subject to 0-4Gy of radiation before being passaged onto plates. Cell viability was assessed in 96-well plates using a combination of a Sulforhodamine B assay (SRB) to quantify live cells 4 days post-treatment, and automated cytometry analysis (Celigo) to assess well confluence over each of the 4 days. Clonogenicity was also assessed by aliquoting cells at low initial density and treating the cells with distinct doses dependent on mode of treatment and cell line. After 7 days number of colonies using a colony formation algorithm on Celigo.

Data Summary: Transient knockdown of Itch in p53-/- cells was sufficient to decrease cell viability. This decrease in cell viability was further potentiated by the application of gemcitabine, doxorubicin or radiation. Stable knockdown using CRISPR-Cas9 increased MiaPaCa2 cell sensitivity to low-dose doxorubicin and radiation (5-10nM and 0.5-1Gy respectively). Whilst statistically significant, the change in response was not as large as that observed with the transient knockdown. In p53 WT cells there was no significant difference in cell sensitivity upon Itch knockdown.

Conclusions: The data from this investigation support the hypothesis of Itch being a possible target for sensitising pancreatic cell lines to cancer therapeutics. However the discrepancies in response to treatment between the transient and stable Itch knockdown scenarios raises the possibility that, in the case of the stable knockdown, the cells have adapted to the absence of Itch. This presents a potential weakness in using CRISPR-Cas9 in long-term experiments where the downstream consequences of gene silencing are not immediate.

Citation Format: Oliver J. Read, David J. Harrison, Paul A. Reynolds. Genetic knockdown of the E3 ubiquitin ligase Itch increases pancreatic cell line sensitivity to cancer therapeutics: A comparison between different gene editing techniques [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4440.

Glutaminase inhibition in renal cell carcinoma therapy

Receptor tyrosine kinase inhibitors have been a standard first-line therapy for renal cell carcinoma (RCC) for over a decade. Although they stabilize the disease, they are unable to remove all tumor cells, leading to relapse. Moreover, both intrinsic and acquired resistance to therapy are a significant health burden. In order to overcome resistance, several combination therapies have been recently approved by the FDA. Another approach takes advantage of altered metabolism in tumor cells, which switch to alternative metabolic pathways to sustain their rapid growth and proliferation. CB-839 is a small molecule inhibitor of kidney type glutaminase (GLS). GLS is often upregulated in glutamine addicted cancers, enhancing glutamine metabolism for the production of energy and the biosynthesis of various cellular building blocks. CB-839 is currently in clinical trials for several tumors, including clear cell (cc)RCC, both as monotherapy and in combination with the approved therapeutic agents everolimus, cabozantinib and nivolumab. Early results of Phase 1/2 clinical trials look promising, especially for CB-839 plus cabozantinib, and all combinations seem to be well tolerated. However, cancer cells can activate compensatory pathways to overcome glutaminolysis inhibition. Therefore, genetic and metabolomic studies are crucial for the successful implementation of CB-839 alone or in combination in subgroups of ccRCC patients.

A rapid review of serious games: From healthcare education to dental education

INTRODUCTION

Games involving technology have the potential to enhance hand-eye coordination and decision-making skills. As a result, game characteristics have been applied to education and training, where they are known as serious games. There is an increase in the volume of literature on serious games in healthcare education; however, evidence on their impact is still ambiguous.

AIMS

The aims of this study were (i) to identify high-quality evidence (systematic reviews or meta-analyses) regarding impacts of serious games on healthcare education; and (ii) to explore evidence regarding impacts of serious games in dental education.

METHODS

A rapid review of the literature was undertaken to synthesise available evidence and examine serious games in healthcare education (Stage 1) and dental education (Stage 2).

RESULTS

Nine systematic reviews were included in Stage 1, four of which were of high, three of moderate and two of low quality. For Stage 2, two randomised control trials with moderate quality were included. The findings demonstrated that serious games are potentially effective learning tools in terms of knowledge and skills improvement, although outcomes of serious games over traditional learning approaches were not consistent. In addition, serious games appeared to be more engaging and satisfying for students, which could be considered as the most important positive impact.

CONCLUSION

Serious games provide an option for healthcare and dental education but remain underutilised and researched. At best, they offer a similar experience to other methods in relation to educational outcome; however, they can provide a supplementary strategy to engage students and improve learner satisfaction.

Abstract 1855: NUC-1031 overcomes resistance associated with gemcitabine in cancer patients

NUC-1031 (NuCana plc) is a phosphoramidate transformation of gemcitabine and the first anti-cancer compound based on ProTide technology (Slusarczyk et al., 2014). It overcomes the main resistance mechanisms associated with gemcitabine and is currently in Phase I, II and III trials for biliary, ovarian, and pancreatic cancers respectively. High expression of dCK is required for activation of gemcitabine, which competes directly with deoxycytidine (dC) as a substrate for dCK. We aimed to compare the mode of action of NUC-1031 with gemcitabine. A panel of pancreatic and ovarian cancer cell lines were treated for 2h to 24h with NUC-1031 or gemcitabine at the EC50 dose and were observed for 96h. Cell morphology and death were observed using time-lapse microscopy. Cell cycle analysis was performed using BrdU labeling and flow cytometry. Exogenous dC was added to the cells either when they were plated or at the time of the treatment, to observe the effect on the sensitivity of cells to NUC-1031 and gemcitabine. Variation of expression of dCK was determined using RT-qPCR and western blotting. Cytospin, followed by immunocytochemistry, was performed to determine the intracellular localization of dCK. Expression of dCK was assessed in tissue samples from patients in the clinical studies using a modified Allred scoring system. After 48h, most cells treated with NUC-1031 show a 24h period when they neither divide nor die, after which they then undergo apoptosis. By contrast, cells treated with gemcitabine start to die sooner, showing features of necrosis and apoptosis. A higher proportion of cells treated with NUC-1031 exhibited a G2/M arrest compared to those treated with gemcitabine or control samples. Protein expression of dCK was increased in MiaPaCa2 cells soon after treatment with gemcitabine compared with NUC-1031. The pool of endogenous nucleotides was altered by addition of dC, inducing significant resistance to gemcitabine, both when dC was added at the time of the treatment and when cells were plated (EC50 respectively 2.5 and 9 times higher than in control cells). NUC-1031 was associated with a moderate decrease in sensitivity when dC was added at the time of the treatment and when cells were plated (EC50 3 times higher than in control cells). Immunohistochemistry of 50 primary tumours from patients enrolled in a Phase 1 study for NUC-1031 showed low-level dCK expression in almost all tumours studied. Our findings indicate that NUC-1031 has a more targeted mode of action to induce cell death than gemcitabine. Also, although a small amount of dCK may be required for maximal sensitivity to NUC-1031, dCK levels are not a limiting step for NUC-1031 efficacy.

Citation Format: Jennifer Bré, Awa Sarr, Peter Mullen, In Hwa Um, Sarah P. Blagden, Paul A. Reynolds, David J. Harrison. NUC-1031 overcomes resistance associated with gemcitabine in cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1855.

Abstract 572: Genome-scale CRISPR/Cas9 screen identifies factors required for sensitivity to pyrimidine nucleoside analogs

NUC-1031 (NuCana plc), is a phosphoramidate transformation of gemcitabine, which bypasses cancer cell resistance mechanisms to gemcitabine. This compound showed promising results in clinical studies (phase I/II), demonstrating tumor reduction and durable disease control in patients who were refractory to or had relapsed on gemcitabine. Here, we adopted an unbiased approach to uncover genes and pathways involved in gemcitabine and NUC-1031 resistance. We performed a genome-wide knockdown screen using CRISPR/Cas9 technology in the pancreatic cancer cell line MiaPaCa2. Potential candidates from the screen were validated by gene inactivation using individual or combined single guide (sg)RNA targeting sequences. The effect of gene knockdown on NUC-1031 and gemcitabine resistance was assessed by monitoring cell survival after drug treatment using Celigo cytometry to assess cell number. EC50 values were determined using the resulting survival curves. This screen generated a list of 4 candidate genes potentially involved in NUC-1031 resistance. Two candidates were investigated further: DCK and DCTPP1, both involved in pyrimidine metabolism, especially in the maintenance of the dCMP/dCTP pool. DCK knockdown induced significant resistance to gemcitabine (EC50 350 times higher than in control cells) and a degree of resistance to NUC-1031 (EC50 7 times higher than in control cells). A less robust effect was observed when DCTPP1 was inactivated. DCTPP1 knockdown induced a small decrease in sensitivity to NUC-1031 (EC50 1.5 times higher than in control cells).

These results highlight the potential role of dCMP/dCTP pool regulation by DCK and DCTPP1 in sensitivity to pyrimidine nucleoside analogs and may provide a useful biomarker for patient selection.

Citation Format: Awa SARR, Jennifer Bré, Peter Mullen, Sarah Blagden, In Hwa Um, David J. Harrison, Paul A. Reynolds. Genome-scale CRISPR/Cas9 screen identifies factors required for sensitivity to pyrimidine nucleoside analogs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 572.

Podocyte injury elicits loss and recovery of cellular forces

In the healthy kidney, specialized cells called podocytes form a sophisticated blood filtration apparatus that allows excretion of wastes and excess fluid from the blood while preventing loss of proteins such as albumin. To operate effectively, this filter is under substantial hydrostatic mechanical pressure. Given their function, it is expected that the ability to apply mechanical force is crucial to the survival of podocytes. However, to date, podocyte mechanobiology remains poorly understood, largely because of a lack of experimental data on the forces involved. We perform quantitative, continuous, nondisruptive, and high-resolution measurements of the forces exerted by differentiated podocytes in real time using a recently introduced functional imaging modality for continuous force mapping. Using an accepted model for podocyte injury, we find that injured podocytes experience near-complete loss of cellular force transmission but that this loss of force is reversible under certain conditions. The observed changes in force correlate with F-actin rearrangement and reduced expression of podocyte-specific proteins. By introducing robust and high-throughput mechanical phenotyping and by demonstrating the significance of mechanical forces in podocyte injury, this research paves the way to a new level of understanding of the kidney. In addition, in an advance over established force mapping techniques, we integrate cellular force measurements with immunofluorescence and perform continuous long-term force measurements of a cell population. Hence, our approach has general applicability to a wide range of biomedical questions involving mechanical forces.

Lessons learned on recruitment and retention in hard-to-reach families in a phase III randomised controlled trial of preparatory information for children undergoing general anaesthesia

BACKGROUND

Recruitment and retention are documented as two of the most difficult elements of conducting clinical trials. These issues are even more challenging in paediatric trials, particularly when the families being recruited and retained are deemed 'hard to reach'.

METHODS

Through the authors' own reflection on the conduct of the trial this paper examines recruitment and retention with hard to reach families from the perspective of a recently completed clinical trial on preparatory information for children undergoing general anaesthesia for tooth extractions in which approximately 83% of those approached and eligible agreed to participate.

RESULTS

The lessons learned for recruitment include: the importance of children's assent; maximising limited resources when screening and approaching potential participants; valuing families' time; and developing effective professional relationships. The retention rate was 83-85.5% at follow up time points up to 3.5 weeks following recruitment, insights into how this was accomplished include: ensuring continuity of care; determination to connect via telephone; valuing families' time; and close monitoring of appointment date changes.

CONCLUSIONS

Implications for future paediatric trials with hard to reach families are discussed.

TRIAL REGISTRATION

ISRCTN18265148 ; NIHR Portfolio 10,006. Date of Registration: 29 November 2013. The trial was registered after commencement but before completion of data collection.

Crumbs 3b promotes tight junctions in an ezrin-dependent manner in mammalian cells

Crumbs 3 (CRB3) is a component of epithelial junctions, which has been implicated in apical-basal polarity, apical identity, apical stability, cell adhesion, and cell growth. CRB3 undergoes alternative splicing to yield two variants: CRB3a and CRB3b. Here, we describe novel data demonstrating that, as with previous studies on CRB3a, CRB3b also promotes the formation of tight junctions (TJs). However, significantly we demonstrate that the 4.1-ezrin-radixin-moesin-binding motif of CRB3b is required for CRB3b functionality and that ezrin binds to the FBM of CRB3b. Furthermore, we show that ezrin contributes to CRB3b functionality and the correct distribution of TJ proteins. We demonstrate that both CRB3 isoforms are required for the production of functionally mature TJs and also the localization of ezrin to the plasma membrane. Finally, we demonstrate that reduced CRB3b expression in head and neck squamous cell carcinoma (HNSCC) correlates with cytoplasmic ezrin, a biomarker for aggressive disease, and shows evidence that while CRB3a expression has no effect, low CRB3b and high cytoplasmic ezrin expression combined may be prognostic for HNSCC.

Willing to Be Involved in Cancer

Genome sequencing is now a common procedure, but prior to this, screening experiments using protein baits was one of the routinely used methods that, occasionally, allowed the identification of new gene products. One such experiment uncovered the gene product called willin/human Expanded/FRMD6. Initial characterization studies found that willin bound phospholipids and was strongly co-localised with actin. However, subsequently, willin was found to be the closest human sequence homologue of the Drosophila protein Expanded (Ex), sharing 60% homology with the Ex FERM domain. This in turn suggested, and then was proven that willin could activate the Hippo signalling pathway. This review describes the increasing body of knowledge about the actions of willin in a number of cellular functions related to cancer. However, like many gene products involved in aspects of cell signalling, a convincing direct role for willin in cancer remains tantalisingly elusive, at present.

Fibroblasts in Head and Neck Squamous Cell Carcinoma Associated With Perineural Invasion Have High-Level Nuclear Yes-Associated Protein (YAP) Expression

We retrospectively studied the expression of Yes-associated protein (YAP) using immunohistochemical staining in 10 cases of head and neck squamous cell carcinoma with associated perineural invasion. We find that fibroblasts in areas associated with perineural invasion show higher levels of nuclear YAP compared to fibroblasts in the stroma of normal mucosa, with a median cell count of 35.4 per high-power field in the former and 3.9 in the latter. No differences were observed between the expression of YAP phosphorylated at Ser127 in the tumoral stroma compared to that in the normal mucosa, with a median cell count expression of 4.9 in the former versus 5.0 in the latter. Therefore, a strong and increased nuclear YAP expression in fibroblasts associated with perineural invasion in head and neck squamous cell carcinoma suggests that YAP-mediated transcription programs in these fibroblasts may contribute to perineural invasion.

Human tissue in systems medicine

Histopathology, the examination of an architecturally artefactual, two-dimensional and static image remains a potent tool allowing diagnosis and empirical expectation of prognosis. Considerable optimism exists that the advent of molecular genetic testing and other biomarker strategies will improve or even replace this ancient technology. A number of biomarkers already add considerable value for prediction of whether a treatment will work. In this short review we argue that a systems medicine approach to pathology will not seek to replace traditional pathology, but rather augment it. Systems approaches need to incorporate quantitative morphological, protein, mRNA and DNA data. A significant challenge for clinical implementation of systems pathology is how to optimize information available from tissue, which is frequently sub-optimal in quality and amount, and yet generate useful predictive models that work. The transition of histopathology to systems pathophysiology and the use of multiscale data sets usher in a new era in diagnosis, prognosis and prediction based on the analysis of human tissue.

Willin, an upstream component of the hippo signaling pathway, orchestrates mammalian peripheral nerve fibroblasts

Willin/FRMD6 was first identified in the rat sciatic nerve, which is composed of neurons, Schwann cells, and fibroblasts. Willin is an upstream component of the Hippo signaling pathway, which results in the inactivation of the transcriptional co-activator YAP through Ser127 phosphorylation. This in turn suppresses the expression of genes involved in cell growth, proliferation and cancer development ensuring the control of organ size, cell contact inhibition and apoptosis. Here we show that in the mammalian sciatic nerve, Willin is predominantly expressed in fibroblasts and that Willin expression activates the Hippo signaling cascade and induces YAP translocation from the nucleus to the cytoplasm. In addition within these cells, although it inhibits cellular proliferation, Willin expression induces a quicker directional migration towards scratch closure and an increased expression of factors linked to nerve regeneration. These results show that Willin modulates sciatic nerve fibroblast activity indicating that Willin may have a potential role in the regeneration of the peripheral nervous system.

Cytoplasmic ezrin and moesin correlate with poor survival in head and neck squamous cell carcinoma

Members of the 4.1 superfamily of proteins, including ezrin, moesin, merlin, and willin regulate many normal physiologic processes such as cellular shape, motility, and proliferation. In addition, they contribute both to tumor development and tumor progression. We reported previously that strong cytoplasmic ezrin expression was independently associated with poorer patient survival. One hundred and thirty-one histologically confirmed primary head and neck squamous cell carcinomas were examined prospectively for cancer progression and survival at a large health care center in the Bronx, NY, USA. Immunohistochemical analysis of ezrin, moesin, merlin, and willin expression in tissue microarray samples of primary head and neck squamous cell carcinoma revealed a significant association of increased cytoplasmic ezrin with poor cancer survival. Global RNA analyses suggest that cancers with high cytoplasmic ezrin have a more invasive phenotype. This study supports our previous findings associating cytoplasmic ezrin with more aggressive behavior and poorer outcome and indicates the need for a multi-institutional study to validate the use of cytoplasmic ezrin as a biomarker for treatment planning in head and neck squamous cell carcinoma.

Hsa-miR-375 is differentially expressed during breast lobular neoplasia and promotes loss of mammary acinar polarity

Invasive lobular carcinoma (ILC) of the breast, characterized by loss of E-cadherin expression, accounts for 5-15% of invasive breast cancers and it is believed to arise via a linear histological progression. Genomic studies have identified a clonal relationship between ILC and concurrent lobular carcinoma in situ (LCIS) lesions, suggesting that LCIS may be a precursor lesion. It has been shown that an LCIS diagnosis confers a 15-20% risk of progression to ILC over a lifetime. Currently no molecular test or markers can identify LCIS lesions likely to progress to ILC. Since microRNA (miRNA) expression changes have been detected in a number of other cancer types, we explored whether their dysregulation might be detected during progression from LCIS to ILC. Using the Illumina miRNA profiling platform, designed for simultaneous analysis of 470 mature miRNAs, we analysed the profiles of archived normal breast epithelium, LCIS lesions found alone, LCIS lesions concurrent with ILC, and the concurrent ILCs as a model of linear histological progression towards ILC. We identified two sets of differentially expressed miRNAs, the first set highly expressed in normal epithelium, including hsa-miR-224, -139, -10b, -450, 140, and -365, and the second set up-regulated during lobular neoplasia progression, including hsa-miR-375, -203, -425-5p, -183, -565, and -182. Using quantitative RT-PCR, we validated a trend of increasing expression for hsa-miR-375, hsa-miR-182, and hsa-miR-183 correlating with ILC progression. As we detected increased expression of hsa-miR-375 in LCIS lesions synchronous with ILC, we sought to determine whether hsa-miR-375 might induce phenotypes reminiscent of lobular neoplasia by expressing it in the MCF-10A 3D culture model of mammary acinar morphogenesis. Increased expression of hsa-miR-375 resulted in loss of cellular organization and acquisition of a hyperplastic phenotype. These data suggest that dysregulated miRNA expression contributes to lobular neoplastic progression.

Effectiveness and acceptability of face-to-face, blended and e-learning: a randomised trial of orthodontic undergraduates

AIM

This study compared e-learning (EL), face-to-face learning (F2FL) and blended learning (BL) with respect to their effectiveness and student attitudes towards them. It also evaluated the effect of the order in which the components (EL and F2FL) of blended learning are delivered.

DESIGN

This was a prospective cluster randomised trial comparing four parallel groups.

METHOD

Eight groups of fourth year dental undergraduate students were randomly allocated to one of four intervention groups: EL, F2FL, BL1 or BL2. These four groups were assessed for their baseline comparability of knowledge and skills. Each then received the same cephalometric tutorial but delivered by the allocated mode of learning. Effectiveness was immediately assessed with a MCQ which measured short-term recall of knowledge. Student attitudes were evaluated with a questionnaire followed by a focus group discussion.

RESULTS

Ninety (57%) students completed the study. Pearson's chi-square test found no statistically significant difference between F2FL and BL; EL alone was less effective (P<0.05) for four MCQ questions but with no difference for the remaining six questions. Overall students were positive towards each learning modality, but a one-way analysis of variance found BL was the most and F2FL was the least accepted (P=0.002). EL was significantly (P=0.028) less preferred. The order of the components in BL had no significant effects.

CONCLUSION

These results suggest that BL is more likely than either F2FL or EL alone, to be both effective and accepted when delivering cephalometric education to undergraduates.

Mechanochemical synthesis and in vitro anti-Helicobacter pylori and uresase inhibitory activities of novel zinc(II)-famotidine complex

The mechanochemical synthesis and characterization of a zinc complex with famotidine is described. The complex was characterized by microanalysis and a number of spectroscopic techniques. The complex was of M:L dihydrate type. Derivatization of famotidine with zinc appears to enhance the activity of the drug by inhibiting the growth of Helicobacter pylori (two reference and 34 clinical isolates). The complex inhibited the growth of H. pylori in an MIC range of 1-8 microg mL(-1). The anti-H. pylori activity of the zinc-famotidine complex against antibiotic-resistant strains was nearly comparable to that of antibiotic-susceptible strains. The complex was found to be far less toxic than the parent drug, as demonstrated by its higher LD(50) value. In the human urease enzyme inhibition assay the complex exhibited significant inhibition. The new complex appears to be more useful in eradicating both the antibiotic-susceptible and antibiotic-resistant strains of H. pylori.

Sizing, stoichiometry and optical absorbance variations of colloidal cadmium sulphide nanoparticles

Simple preparative methods were used to synthesise cadmium sulphide particles in the size ranges larger than those associated with quantum confinement. UV/visible absorption spectra were measured. Rayleigh and Mie theories were used to analyse normalised absorption spectra to allow estimates of particle size and number to be obtained simultaneously. Each model was utilised in an appropriate size and wavelength range. Surprisingly, Mie calculations were found to over-estimate the absorbance of particles below 50 nm radius. Powder X-ray diffraction results showed the crystallites to be independent of particle size and suggested that the particles grew through aggregation of smaller bodies. The Mie results could therefore be interpreted in terms of changes in the particles' optical indicatrix with radius. Large poly-crystalline particles (>50 nm radius) should possess a near spherical indicatrix, fulfilling the assumptions of the Mie theory. The indicatrix of particles smaller than 50 nm should become increasingly anisotropic with decreasing size, leading to discrepancies between the Mie model and measured data. Although the results could also be explained through changes in the magnitude of the particle refractive index, compositional (Auger electron spectroscopy, energy dispersive X-ray analysis) and structural (powder X-ray diffraction) analyses of the particles complicate the hypothesis. Energy dispersive X-ray results showed that small cadmium sulphide particles possessed a large excess of sulphur suggesting a change in effective cadmium sulphide stoichiometry.

Supporting the learner and teacher online

Whether on or off campus, all students need support if they are to successfully complete their studies. Although 'good teachers' should be 'good teachers' in any medium, their support is especially important when technology is involved. Previous articles in the series have shown that the advent of ICT has added to the complexity of the type and provision of this help and advice, not least because it now involves technical as well as pedagogical and pastoral elements. However, rather than being a problem, ICT, particularly through its online facilities, can provide levels of support over and above those required by traditional face-to-face teaching. This has implications for tutors as well as students as it places greater pressure on their time and requires them to have a new skills-set, a situation that needs to be resolved if the full benefits of online support are to be realised.

Abstract LB-334: Signals from the microenvironment induce a malignant program accompanied by de novo epigenetic remodeling

Introduction: The active acquisition of epigenetic changes is a poorly understood but important process in development, differentiation, and disease. Our work has recently demonstrated that repression of the p16/pRb pathway in human epithelial cells, a condition common to stem cells and many tumor cells, induces dynamic epigenetic remodeling resulting in the targeted methylation of selected CpG islands. We hypothesized that cells in this epigenetically-plastic state can be programmed by the microenvironment to acquire epigenetic changes that promote tumorigenesis.

Methods: Normal human mammary epithelial cells (HMEC) and HMEC with repressed p16 were first transduced with constitutively active Ha-rasV12. In order to mimic the secretory aspects of the extracellular environment, the cells were subsequently cultured in a serum-rich environment.

Results: When p16-repressed cells were challenged with oncogenic stress, they failed to undergo the classic proliferative arrest as documented in normal cells. When further stressed by being cultured in a serum-rich environment, they spontaneously immortalized and exhibited phenotypic changes indicative of epithelial to mesenchymal transition (EMT). The EMT was accompanied by de novo methylation of the E-cadherin promoter and increased motility.

Conclusions: These data demonstrate that signals from the microenvironment can induce phenotypic and gene expression changes that result in de novo epigenetic alterations important in tumor progression.

Morphologically normal-appearing mammary epithelial cells obtained from high-risk women exhibit methylation silencing of INK4a/ARF

PURPOSE

p16(INK4a) has been appreciated as a key regulator of cell cycle progression and senescence. Cultured human mammary epithelial cells that lack p16(INK4a) activity have been shown to exhibit premalignant phenotypes, such as telomeric dysfunction, centrosomal dysfunction, a sustained stress response, and, most recently, a dysregulation of chromatin remodeling and DNA methylation. These data suggest that cells that lack p16(INK4a) activity would be at high risk for breast cancer development and may exhibit an increased frequency of DNA methylation events in early cancer.

EXPERIMENTAL DESIGN

To test this hypothesis, the frequencies of INK4a/ARF promoter hypermethylation, as well as four additional selected loci, were tested in the initial random periareolar fine needle aspiration samples from 86 asymptomatic women at high risk for development of breast cancer, stratified using the Masood cytology index.

RESULTS

INK4a/ARF promoter hypermethylation was observed throughout all early stages of intraepithelial neoplasia and, importantly, in morphologically normal-appearing mammary epithelial cells; 29 of 86 subjects showed INK4a/ARF promoter hypermethylation in at least one breast. Importantly, INK4a/ARF promoter hypermethylation was not associated with atypia, and the frequency of hypermethylation did not increase with increasing Masood cytology score. The frequency of INK4a/ARF promoter hypermethylation was associated with the combined frequency of promoter hypermethylation of retinoic acid receptor-beta2, estrogen receptor-alpha, and breast cancer-associated 1 genes (P = 0.001).

CONCLUSIONS

Because INK4a/ARF promoter hypermethylation does not increase with age but increases with the frequency of other methylation events, we predict that INK4a/ARF promoter hypermethylation may serve as a marker of global methylation dysregulation.

Portable digital assistants (PDAs) in dentistry: part II--pilot study of PDA use in the dental clinic

AIM

To describe a simple technical evaluation of the access, security issues and uses of wireless networked PDAs in a dental clinic and report a pilot study investigating students' educational use of PDAs to access a Virtual Learning Environment (VLE) in a dental clinic.

OBJECTIVES

To undertake a technical evaluation of wireless networking to PDAs focusing on security issues, robustness of the system and accessibility particularly to educational resources. To evaluate the impact of using a PDA on undergraduate students in the dental clinic and at home.

DESIGN

Part II describes the technical and educational evaluation of PDAs used by one group of 12 undergraduate fourth year students in the Primary Dental Care clinic. A cross over trial of six students with PDAs and six without was carried out during one semester of 12 weeks.

METHODS

Technical issues such as secure internet access using wireless connectivity were addressed. An assessment of the general and educational use and the students' attitudes towards using PDAs was undertaken using online questionnaires and focus group discussions.

RESULTS

Over 90% of participants wanted PDAs as part of their dental kit. The potential of PDA use in dental training was demonstrated by a good to excellent response by over 75% of participants to having access to online support materials, particularly videos, being able to make notes for individual study and to keep a diary of their commitments to teaching sessions. Recreational use included a 100% good to excellent response to playing games and keeping a diary.

CONCLUSION

The PDA proved to be a convenient and versatile mode of access to online education. Technical solutions enabled a substantial proportion of the functionality of WebCT (Web Course Tools) to be accessed by the students in a clinical environment. Both novice and experienced users were able to appreciate the use of the PDA and the less able considered that their ICT skills had improved. However, further research is needed to determine how students use a range of new technologies in their undergraduate programmes. The Dental Institute plans to recommend that all students will use this device in the future throughout their five-year curriculum, and the scoping of the implications of this recommendation is underway.

Portable Digital Assistants (PDAs) in dentistry: Part I

AIM

To provide a basic understanding of the features of a portable digital assistant (PDA) and how it may be useful for the general dental practitioner.

OBJECTIVES

To outline the various types, functions and applications of a PDA and suggest its use for the dental professional now and in the future. To enable appreciation of the technology and educational evaluation carried out in the pilot study reported in Part II.

DESIGN

Part I is a descriptive account of the use and function of the PDA in dentistry and its potential for the future.

METHOD

A review of the literature was carried out drawing on evidence from general healthcare and assessments of portable computing aids evaluated in a dentally related setting. RESULTS Choosing a PDA for use in dental practice is complex but should be based on the user's needs mapped to key features, size and cost of the device.

CONCLUSION

No ideal customisable mobile digital solution currently exists but evidence from general healthcare use suggests that there are valuable features that can aid the general dental practitioners such as personal management and point of source assistance.

Tumor Suppressor p16INK4A Regulates Polycomb-mediated DNA Hypermethylation in Human Mammary Epithelial Cells

Alterations in DNA methylation are important in cancer, but the acquisition of these alterations is poorly understood. Using an unbiased global screen for CpG island methylation events, we have identified a non-random pattern of DNA hypermethylation acquired in p16-repressed cells. Interestingly, this pattern included loci located upstream of a number of homeobox genes. Upon removal of p16(INK4A) activity in primary human mammary epithelial cells, polycomb repressors, EZH2 and SUZ12, are up-regulated and recruited to HOXA9, a locus expressed during normal breast development and epigenetically silenced in breast cancer. We demonstrate that at this targeted locus, the up-regulation of polycomb repressors is accompanied by the recruitment of DNA methyltransferases and the hypermethylation of DNA, an endpoint, which we show to be dependent on SUZ12 expression. These results demonstrate a causal role of p16(INK4A) disruption in modulating DNA hypermethylation, and identify a dynamic and active process whereby epigenetic modulation of gene expression is activated as an early event in breast tumor progression.

Investigation into potential mechanisms promoting biocompatibility of polymeric biomaterials containing the phosphorylcholine moiety

Phosphorylcholine (PC) moieties were chemically attached to surfaces of polymer microparticles by addition of 2-methylacryloyloxyethyl phosphorylcholine monomer to the seeded, semi-continuous polymerisations of methyl methacrylate (MMA) and butyl acrylate (BA). The surface of the bio-functionalised polymer microparticles was principally characterised using X-ray photoelectron spectroscopy (XPS), dynamic nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), photon correlation spectroscopy (PCS), acoustophoresis and enzyme-linked immunosorbent assays (ELISA). It was found that the persulphate initiating species are concealed behind the phosphorylcholine containing monomer sequence located on the surface of the microparticles. The combination of analytical techniques showed that the surfaces of the polymer microparticles are extremely mobile above the glass transition temperature of the co-polymer and able to rearrange depending on the environment in which they are placed. This allows the phosphorylcholine moiety to be preferentially expressed at the surface in aqueous media, but not so in the dry state or conditions of ultra-high vacuum. In terms of the nature of the biocompatibility of phosphorylcholine containing polymers, no evidence was found for the irreversible structuring of water molecules around the phosphorylcholine moiety in the wet state. The results of this work suggest that a more likely contributory reason for the protein-resistant nature of phosphorylcholine containing polymers is the mobility of the phosphorylcholine moiety. Increases in biocompatibility correspond with increases in the hydrophilicity of a polymer surface when phosphorylcholine is preferentially expressed. A large free water fraction may be present in the phosphorylcholine containing monomer sequence, as part of a hydrogel structure located at the surface of the polymer microparticles. This, coupled with concomitant modification of the local electrical double-layer very close to the surface may also play a critical role in reducing protein-surface interactions.

The Anglo-Italian collaboration: a report of the first steps in implementing the Bologna Declaration

This report summarises the accomplishments of King's College London and Università degli Studi di Brescia in establishing an Anglo-Italian Collaboration. The aim was to develop areas of enterprise in clinical practice, teaching and research that reflected the principles of the Bologna Declaration.

Identification of a DNA-binding site and transcriptional target for the EWS-WT1(+KTS) oncoprotein

Desmoplastic small round cell tumor (DSRCT) is defined by a chimeric transcription factor, resulting from fusion of the N-terminal domain of the Ewing's sarcoma gene EWS to the three C-terminal zinc fingers of the Wilms' tumor suppressor WT1. Although DNA-binding sites have been defined for the uninterrupted WT1 zinc finger domains, the most prevalent isoforms of both WT1 and EWS-WT1 have an insertion of three amino acids [lysine, threonine, and serine (KTS)], which abrogates binding to known consensus sequences and transactivation of known target genes. Here, we used cDNA subtractive hybridization to identify an endogenous gene, LRRC15, which is specifically up-regulated after inducible expression of EWS-WT1(+KTS) in cancer cell lines, and is expressed within primary DSRCT cells. The chimeric protein binds in vitro and in vivo to a specific element upstream of LRRC15, leading to dramatic transcriptional activation. Mutagenesis studies define the optimal binding site of the (+KTS) isoform of EWS-WT1 as 5'-GGAGG(A/G)-3'. LRRC15 encodes a leucine-rich transmembrane protein, present at the leading edge of migrating cells, the expression of which in normal tissues is restricted to the invasive cytotrophoblast layer of the placenta; small interfering (siRNA)-mediated suppression of LRRC15 expression in breast cancer cells leads to abrogation of invasiveness in vitro. Together, these observations define the consequence of (KTS) insertion within WT1-derived zinc fingers, and identify a novel EWS-WT1 transcriptional target implicated in tumor invasiveness.

Induction of BAIAP3 by the EWS-WT1 chimeric fusion implicates regulated exocytosis in tumorigenesis

Desmoplastic small round cell tumor (DSRCT) is defined genetically by the chimeric fusion of the Ewing's sarcoma and Wilms' tumor genes, generating a novel transcription factor, EWS-WT1. By using cells with inducible EWS-WT1 to screen high-density microarrays, we identified BAIAP3 as a transcriptional target of the chimera. The BAIAP3 promoter is specifically bound in vivo by the (-KTS) isoform of EWS-WT1, consistent with its activation in reporter assays. BAIAP3 encodes a protein implicated in regulated exocytosis, which is colocalized with a secreted growth factor within cytoplasmic organelles. Ectopic expression of BAIAP3 in tumor cells dramatically enhances growth in low serum and colony formation in soft agar. BAIAP3 therefore encodes a transcriptional target of an oncogenic fusion protein that implicates the regulated exocytotic pathway in cancer cell proliferation.

Induction of the interleukin-2/15 receptor beta-chain by the EWS-WT1 translocation product

EWS-WT1 is a chimeric transcription factor resulting from fusion of the N-terminal domain of the Ewing sarcoma gene EWS to the three C-terminal zinc fingers of the Wilms tumor suppressor WT1. This translocation underlies desmoplastic small round cell tumor (DSRCT), which is noted for the abundance of reactive stroma surrounding islets of tumor cells, suggestive of paracrine signals contributing to tumor cell proliferation. Hybridization to high-density oligonucleotide microarrays can be used to identify targets of EWS-WT1. Expression of EWS-WT1 from a tetracycline-regulated promoter leads to the induction of growth-associated genes, of which the most remarkable is the beta-chain of the interleukin-2/15 receptor (IL-2/15Rbeta). Potent transcriptional activation by the chimeric protein maps to two bindings sites within the IL-2/15Rbeta promoter. Analysis of primary DSRCT tumor specimens demonstrates high levels of IL-2/15Rbeta within the tumor cells, along with expression of IL-2 and IL-15 by the abundant hyperplastic endothelial cells within the reactive stroma. Activation of this cytokine signaling pathway is consistent with the nuclear localization of its downstream effectors, phosphorylated STAT3 and STAT5. These observations suggest that the transcriptional induction of a cytokine receptor by a tumor-associated translocation product enables a proliferative response of epithelial cancer cells to ligands secreted by the surrounding stroma.

Tetrachlorobis(N1-phenylacetamidino-kappaN2)rhenium(IV) at 11 K by X-ray diffraction and at 20 K by neutron diffraction

The crystal structure of the title compound, [ReCl(4)(C(8)H(10)N(2))(2)], has been determined by X-ray diffraction at 11 K and by neutron diffraction at 20 K. The accurate and extensive data sets lead to more precise determinations than are available from earlier work. The agreement in atomic positional and displacement parameters at these very low temperatures is good. The results will facilitate re-examination of the magnetic structure of the complex. The Re atom lies on a special position and the molecule has twofold crystallographic symmetry.

Participating dentists' assessment of the pilot regional online videoconferencing in dentistry (PROVIDENT) project

OBJECTIVE

To assess the educational effectiveness of delivering continuing professional education (CPE) from dental schools to small groups of dentists at distant sites via videoconferenced links using relatively inexpensive equipment and ISDN2 links.

DESIGN

41 videoconferences between the four campuses of London Dental Schools and postgraduate centres in South East England were assessed using a pre-piloted questionnaire which contained open and specific questions. The questionnaire was given to all participants at the end of each videoconference. Answers to the specific questions were graded using the Likert scale.

RESULTS

40 of the 41 videoconferences were completed satisfactorily and were attended by 257 participants, all of whom completed questionnaires. However, no individual question was answered by all the participants. Of the responses 90% were positive on the topics of appropriateness of the teaching material for delivery by videoconference and of its educational level. 90% of responses also indicated a wish to attend further videoconferences and satisfaction at avoiding the need to travel to London for similar educational activity. 87% rated the lecturers as good or excellent in their use of the medium. 85% of responses indicated that the question and answer sessions within the videoconferences were useful and 82% that the visual aids enhanced the sessions. The technical aspects of the videoconferences were rated positively but to a lesser extent than the educational aspects with 69% of positive responses for visibility of visual aids, 54% for sound quality and 76% for the lecturers use of the technology. The technical aspects of the videoconferences improved during the pilot study. In response to the open questions, participants stated that they found the most useful aspects of the videoconferences were not having to travel, access to first rate lecturers, the discussions and the opportunity to interact with experts.

CONCLUSIONS

The participants in this pilot study were positive about the use of videoconferencing to deliver educational material from dental schools to small groups. Once the technology has improved, this medium has the potential to provide CPE for dentists at work or at home in response to their specific needs.

A study of videoconferencing for postgraduate continuing education in dentistry in the UK--the teachers' view

Videoconferencing is an established method for providing medical education over long distances. Our aims were to assess the feasibility of videoconferencing in dental postgraduate education, to evaluate its practicability, teacher satisfaction and evaluate equipment. Twenty-seven teachers from the 4 London Dental Schools provided 41 postgraduate dental education sessions on a range of topics to regional postgraduate centres and dental practices as part of the Thames Health Region's programme. Videoconferencing was carried out using a relatively inexpensive personal computer system link using ISDN2 telephone lines and Z350 protocol. Presenter views and assessment were obtained by questionnaire, interview and videotape. Teachers felt that minimal additional preparation time was required for videoconferencing and 21/27 preferred it to in-person teaching, most noting the saving in travel time. Only 3 of the teachers were dissatisfied with their ability to communicate, 4 were equivocal and 20 were either pleased or very pleased. The teachers largely enjoyed the experience and performed well in the new medium. However, sound quality proved inadequate in 5/41 links and most sessions included some periods of suboptimal sound. Only 4 teachers were satisfied with their ability to perform question and answer interaction with the audience. We conclude that experienced teachers adapt readily to videoconferencing and learn to communicate effectively very quickly. Teachers were positive about the medium despite its shortcomings and improvements in sound quality would allow a rapid expansion of postgraduate dental education by videoconference.

Loss of heterozygosity at 7p in Wilms' tumour development

Chromosome 7p alterations have been implicated in the development of Wilms' tumour (WT) by previous studies of tumour cytogenetics, and by our analysis of a constitutional translocation (t(1;7)(q42;p15)) in a child with WT and radial aplasia. We therefore used polymorphic microsatellite markers on 7p for a loss of heterozygosity (LOH) study, and found LOH in seven out of 77 informative WTs (9%). The common region of LOH was 7p15-7p22, which contains the region disrupted by the t(1;7) breakpoint. Four WTs with 7p LOH had other genetic changes; a germline WT1 mutation with 11p LOH, LOH at 11p, LOH at 16q, and loss of imprinting of IGF2. Analysis of three tumour-associated lesions from 7p LOH cases revealed a cystic nephroma-like area also having 7p LOH. However, a nephrogenic rest and a contralateral WT from the two other cases showed no 7p LOH. No particular clinical phenotype was associated with the WTs which showed 7p LOH. The frequency and pattern of 7p LOH demonstrated in our studies indicate the presence of a tumour suppressor gene at 7p involved in the development of Wilms' tumour.

Localization of a novel t(1;7) translocation associated with Wilms' tumor predisposition and skeletal abnormalities

Cytogenetic analysis of predisposition syndromes has played a critical role in the elucidation of the genetics of Wilms' tumor (WT). Therefore, we became interested in a patient who presented with a WT and a nephrogenic rest in the contralateral kidney (suggestive of a predisposition) and a de novo t(1;7)(q42;p15) constitutional translocation as the only visible cytogenetic abnormality. He also had bilateral radial aplasia and other skeletal abnormalities, but there was no manifestation of any syndrome previously associated with WT. In the tumor, the translocation was retained, and the other 7p region was lost by the formation of an isochromosome i(7q). Here, we report the localization of the chromosome 7 breakpoint within a yeast artificial chromosome (YAC) contig by using fluorescence in situ hybridization (FISH), localizing the breakpoint between markers sWSS355 and sWSS1449. A number of YACs span the breakpoint and, thus, contain the region that is disrupted by the translocation. This may represent the site of a novel tumor suppressor gene that is involved in WT and also in normal renal development.

Structures of Some Complexes Containing the ReIVCl4 Unit

The X-ray crystal structure determinations of five complexes of rhenium(IV) containing the ReCl4L2 unit, with L monodentate , are reported, one at 92 K. They are: (1) cis -( HNCMeNHPh )2ReCl4, Pccn , a 21.677(4), b 7.253(1), c 12.470(2) Ǻ, R1(2σ) 0.0217, Rw 0.0473; (2) the di ( acetonitrile ) solvate of (1), Pī , a 10.005(2), b 12.120(2), c 12.744(2) Ǻ, α 72.19(1), β 67.65(1), γ 90.95(1)°, R1(2σ) 0.0311, Rw 0.0819; (3) cis -(HN= CMeNH (p-C6H4Me))2ReCl4, Pna21, a 12.782(2), b 8.237(1), c 21.279(3) Ǻ, R1(2σ) 0.0497, Rw 0.1066; (4) cis-( thf )2ReCl4, P 212121, a 7.785(2), b 12.666(4), c 14.253(5) Ǻ, R1(2σ), 0.0326, Rw 0.0827; and (5) trans-(Me2PhP)2ReCl4, P 21/c, a 9.701(2), b 13.739(6), c 8.324(2) Ǻ, β 106.83(2), R1(2σ) 0.0241, Rw 0.0613. The Re-Cl bond lengths in these and six other ReIVCl4L2 octahedral complexes are compared, and no distinct trans-effect of the donor atom on the chlorine atoms is seen either where L is monodentate as in our compounds or where L2 is a chelate ligand, as in the examples from the literature, although the results are much less clear there.

Low-Temperature Structure and Magnetic Properties of Tetraphenylarsonium Tetrachloronitridotechnetate(VI)

The crystal structure of [As(C6H5)4] [TcNCl4] was determined at 120 K by X-ray diffraction and at 28 K by neutron diffraction. The crystals are tetragonal, space group P4/n, with a 1260.4(3) and c 773.2(2) pm at 120 K. The [TcNCl4]-anion possesses exact C4v symmetry, with Tc≡N distances of 160.3(2) and 162.5(4)pm at 120 and 28 K respectively. Magnetic susceptibilities were measured on single crystals from 300 to 4.5 K. The results indicate a well behaved S ½ system following the Curie-Weiss law with θ -0.13 K

Protein quality of enteral nutrition products is consistent with label claims during shelf life and beyond expiration date

OBJECTIVE

Eternal formulas were monitored during their shelf life and beyond expiration date to examine protein quality.

DESIGN

Protein quality was determined by protein efficiency ratio (PER) bioassays and amino acid analyses.

SETTING

A certified laboratory performed the PER tests according to procedures established by the Association of Official Analytical Chemists and recognized by the US Food and Drug Administration (FDA). The amino acid analyses were performed in our laboratory using validated methods.

SAMPLES

Commercially available formulas (Ensure, Osmolite HN, TwoCal HN) that contained protein blends of caseinates or caseinates with soybean protein isolate were studied.

MAIN OUTCOME MEASURES

Achievement of protein-quality values greater than or equal to 70% of the fresh reference casein value as determined by the PER method would be consistent with adequate protein quality as described by the FDA. Levels of indispensable amino acids that meet or exceed the standards established by the National Research Council of the National Academy of Sciences are considered high-quality proteins. Levels of amino acids throughout shelf life were compared with published label claims.

RESULTS

Amino acid analyses, which included measurement of tryptophan and total sulfur amino acids, revealed that both fresh and outdated products met or exceeded standards for proteins of high biologic value and were consistent with label claims. The PER values ranged from 90% to 96% of the control diet for fresh product and 82% to 87% for products evaluated after expiration.

CONCLUSION

The enteral products studied provide high-quality protein throughout the shelf life of the product.

The Conformations of the Hexaammineruthenium(III) Ion in Simple Salts

Single-crystal X-ray diffraction results are presented for six hexaammineruthenium (III) salts, viz. [ Ru (NH3)6]2(SO4)35H2O, [ Ru (NH3)6] CdCl5, [ Ru (NH3)6]ZnCl5, [ Ru (NH3)6]Cl2SCN, [ Ru (NH3)6]2(S2O6)3.H2O, and a salt of approximate formula [ Ru (NH3)6]2 [POF5]3.4H2O. The 11 independent cations in these and other published structures do not adopt a single conformation in respect of hydrogen atom disposition. Analysis of the N- Ru -N-H dihedral angles and their correlations strongly suggests that the conformation is random, given the crystallographic site symmetry. The structure with torsional energy calculated at a minimum by ab initio methods is not observed. This suggests that there are only a limited number of interionic geometries feasible in crystallization. Such a limitation suggests that computing crystal structures, with no assumptions as to space group or any other assumption, is not an open-ended problem with excessive alternatives.

Single-Crystal Magnetic Properties of [Co(NH3)5(OH2)] [Cr(CN)6] Between 2 and 300 K

The magnetic susceptibilities along and perpendicular to the c axis (hexagonal setting) between 2.0 and 300 K at a magnetic field of 1.00 T, and the magnetizations at field strengths up to 5.00 T, are presented for single crystals of [Co(NH3)5(OH2)] [Cr(CN)6]. The results are interpreted in terms of zero-field splitting (2D) of the ground 4A2g term by spin-orbit coupling and of magnetic exchange interaction between the chromium atoms. The magnetic exchange is modelled as one of Ising or mean-field in type. The exchange is found to be quite small: J = -0.18(6) cm-1 if the Ising model is employed, and -0.03(1) cm-1 for the mean-field model. The model adopted for the exchange has a strong influence on the value of the parameter D obtained. When the Ising model is used D is deduced to be -0.28(9) cm-l; when the mean-field model is used D is -0.14(4) cm-l. The g-values deduced are in agreement with those from e.s.r. measurements at higher temperatures and do not depend on the exchange model. In any case, D is found to be sufficiently large that it must be considered in a polarized neutron diffraction experiment on the compound.

The Ground State in Cs2KFe(CN)6 From Single-Crystal Magnetic Properties

The single-crystal magnetic susceptibilities from 4.5 to 300 K, and the magnetizations at 4.5 K from 0.25 to 5 T, of Cs2KFe(CN)6 along a, b and c* are reported. The data are fitted well by a crystal field model with splitting of the ground-state 2T2g term of the hexacyanoferrate (III) ion. The three variable parameters of the model were the two representing the low-symmetry splitting of the t2g orbitals, and the effective reduction in the orbital angular momentum. Four other parameters were fixed at values known or estimated from other experiments on hexacyanoferrate (III) ions, including polarized neutron diffraction which determines the orientation of lower-symmetry crystal field components. The crystal field has only inversion symmetry with respect to the ligand axes, with a non-cubic component which is almost uniaxial with respect to the a,b,c * axis system.

Homology between proteins controlling Streptomyces fradiae tylosin resistance and ATP-binding transport

A tylosin(Ty)-producing strain of Streptomyces fradiae contains at least three genes, tlrA, tlrB, tlrC, specifying resistance to Ty (TyR). The complete nucleotide sequence of the TyR-encoding gene, tlrC, and the transcription start point of the gene were determined. The sequence contains an open reading frame coding for a protein of 548 amino acids (aa) with an Mr of 59129. The TlrC protein was identified by expression of the cloned gene by in vitro coupled transcription and translation in cell-free extracts derived from Streptomyces lividans. The N- and C-terminal halves of TlrC share extensive homology, suggesting that the protein evolved through tandem gene duplication. Each half of the deduced TlrC aa sequence also shows significant homology to numerous eukaryotic and prokaryotic membrane-associated, active-transport protein subunits. The homologous proteins include examples from the systems responsible for efflux of cytotoxic drugs from multidrug-resistant human cells and for export of hemolysin from Escherichia coli. The greatest similarity to TlrC is in regions containing the ATP-binding sites found in these proteins. These results suggest a role for the tlrC gene product as part of a multiple component, ATP-dependent transport system for the active excretion of Ty from the producing organism.