PDGFRß Signaling Cooperates with ß-Catenin to Modulate c-Abl and Biologic Behavior of Desmoid-Type Fibromatosis.

PURPOSE: This study sought to identify ß-catenin targets that regulate desmoid oncogenesis and determine whether external signaling pathways, particularly those inhibited by sorafenib (e.g., PDGFRß), affect these targets to alter natural history or treatment response in patients. EXPERIMENTAL DESIGN: In vitro experiments utilized primary desmoid cell lines to examine regulation of ß-catenin targets. Relevance of results was assessed in vivo using Alliance trial A091105 correlative biopsies. RESULTS: CTNNB1 knockdown inhibited hypoxia-regulated gene expression in vitro and reduced levels of HIF1α protein. ChIP-seq identified ABL1 as a ß-catenin transcriptional target that modulated HIF1α and desmoid cell proliferation. Abrogation of either CTNNB1 or HIF1A inhibited desmoid cell-induced VEGFR2 phosphorylation and tube formation in endothelial cell co-cultures. Sorafenib inhibited this activity directly but also reduced HIF1α protein expression and c-Abl activity while inhibiting PDGFRß signaling in desmoid cells. Conversely, c-Abl activity and desmoid cell proliferation were positively regulated by PDGF-BB. Reduction in PDGFRß and c-Abl phosphorylation was commonly observed in biopsy samples from patients after treatment with sorafenib; markers of PDGFRß/c-Abl pathway activation in baseline samples were associated with tumor progression in patients on the placebo arm and response to sorafenib in patients receiving treatment. CONCLUSIONS: The ß-catenin transcriptional target ABL1 is necessary for proliferation and maintenance of HIF1α in desmoid cells. Regulation of c-Abl activity by PDGF signaling and targeted therapies modulates desmoid cell proliferation, thereby suggesting a reason for variable biologic behavior between tumors, a mechanism for sorafenib activity in desmoids, and markers predictive of outcome in patients.

Qualitative analysis of the cognitive triad in a sample of the general population in response to the COVID-19 pandemic.

This paper explored cognitive responses to the COVID-19 pandemic in those selfreporting depressive symptoms during a period of realistic health, economic and social threat. Negative cognitions are a key therapy target for evidence-based psychological interventions. A cross-sectional survey was conducted with a convenience sample from the general population between December 2020 and February 2021. Adult respondents (n = 555) completed open text-box questions which provided prompts of the cognitive triad: "I am…/I am not…"; "Other people are…/Other people are not…"; "The world is…". These qualitative data were analysed using reflexive thematic analysis. Thematic responses were compared between people who self-reported moderate depressive symptoms (n = 223) and those who did not (n = 332). Fourteen independent themes were identified. Those self-reporting depressive symptoms described significantly fewer positive cognitions across all three aspects of the cognitive triad, X2 = 60.40 p < 0.01;  X2 = 10.51 p < 0.05; X2 = 12.22 p < 0.01. Those self-reporting depressive symptoms also reported more self-referent negative cognitions. These data highlighted that an absence of positive cognitions differentiated the two groups more greatly than negative cognitions. These data have implications for the cognitive targets in psychological therapies in realistic high-stress situations. This paper explored cognitive responses to the COVID-19 pandemic in those selfreporting depressive symptoms during a period of realistic health, economic and social threat. Negative cognitions are a key therapy target for evidence-based psychological interventions. A cross-sectional survey was conducted with a convenience sample from the general population between December 2020 and February 2021. Adult respondents (n = 555) completed open text-box questions which provided prompts of the cognitive triad: "I am…/I am not…"; "Other people are…/Other people are not…"; "The world is…". These qualitative data were analysed using reflexive thematic analysis. Thematic responses were compared between people who self-reported moderate depressive symptoms (n = 223) and those who did not (n = 332). Fourteen independent themes were identified. Those self-reporting depressive symptoms described significantly fewer positive cognitions across all three aspects of the cognitive triad, X2 = 60.40 p < 0.01;  X2 = 10.51 p < 0.05; X2 = 12.22 p < 0.01. Those self-reporting depressive symptoms also reported more self-referent negative cognitions. These data highlighted that an absence of positive cognitions differentiated the two groups more greatly than negative cognitions. These data have implications for the cognitive targets in psychological therapies in realistic high-stress situations.

Clinical outcomes and safety of anakinra in the treatment of multisystem inflammatory syndrome in children: a single center observational study.

BACKGROUND AND OBJECTIVE: Evidence for the treatment of multisystem inflammatory syndrome in children (MIS-C) is lacking. Anakinra, which targets IL-1-mediated inflammation, is reserved for refractory cases of MIS-C; however, its use in the treatment of MIS-C is not clearly established. PATIENTS AND METHODS: To examine a role for anakinra in MIS-C, we performed a single center observational cohort study of all MIS-C patients diagnosed at our children's hospital from May 15 to November 15, 2020. Demographics, clinical features, diagnostic testing, and cardiac function parameters were compared between MIS-C patients treated with intravenous immunoglobulin (IVIG) monotherapy and IVIG with anakinra (IVIG + anakinra). RESULTS: Among 46 patients with confirmed MIS-C, 32 (70%) were in the IVIG + anakinra group, of which 9 (28%) were also given corticosteroids (CS). No patients were treated with anakinra alone. MIS-C patients in the IVIG + anakinra group were enriched in a CV shock phenotype (p = 0.02), and those with CV shock were treated with higher doses of anakinra for a longer duration. Furthermore, MIS-C patients in the IVIG + anakinra group exhibited improvements in fever and cardiac function with or without CS. No significant adverse events were observed, and no differences in IL-1ß levels were found among MIS-C patients in the IVIG + anakinra group. CONCLUSIONS: Anakinra treatment, which was co-administered with IVIG primarily in patients with severe MIS-C, was associated with improvements in fever and cardiac function, and demonstrated a favorable side-effect profile. These findings suggest a role for adjunctive anakinra in the treatment of severe MIS-C.

A confirmatory factor analysis of a cognitive model of COVID-19 related anxiety and depression.

The mental health impact of the COVID-19 pandemic has been significant, with many regions across the globe reporting significant increases in anxiety, depression, trauma, and insomnia. This study aims to validate a potential cognitive model of maintenance factors of COVID-19 related distress by examining psychological predictors of distress, and their goodness-of-fit as a coherent model. Participants from the general population (n = 555) were recruited using a cross-sectional on-line survey design, assessing Demographic factors, Anxiety, Depression, Loneliness, COVID-19 related distress, Trauma Cognitions related to COVID-19, Rumination, Safety Behaviours, Personality Factors, and Mental Effort related to COVID-19. A series of stepwise linear regressions found that components of the model were significant and accounted for a large percentage of variance when examining Covid-19 related distress (R2 = 0.447 Covid Stress Scale), Anxiety (R2 = 0.536 DASS-Anxiety Subscale) and Depression (R2 = 0.596 Depression DASS-subscale). In a confirmatory factor analysis, Loneliness, Post-Traumatic Cognitions about Self, Post-Traumatic Cognitions about the World, Emotional Stability, and Mental Effort related to COVID-19 loaded onto a single factor. The final model showed adequate fit (CFI = 0.990, TLI = 0.983, RMSEA = 0.053 (0.027-0.080), GFI = 0.986, SRMR = 0.0216, χ2 = 23.087, p = .006). The results highlight the importance of cognitive factors, such as post-traumatic cognitions, rumination, and mental effort in maintaining COVID-19 related distress.

Integrin-α10 Dependency Identifies RAC and RICTOR as Therapeutic Targets in High-Grade Myxofibrosarcoma.

Myxofibrosarcoma is a common mesenchymal malignancy with complex genomics and heterogeneous clinical outcomes. Through gene-expression profiling of 64 primary high-grade myxofibrosarcomas, we defined an expression signature associated with clinical outcome. The gene most significantly associated with disease-specific death and distant metastasis was ITGA10 (integrin-α10). Functional studies revealed that myxofibrosarcoma cells strongly depended on integrin-α10, whereas normal mesenchymal cells did not. Integrin-α10 transmitted its tumor-specific signal via TRIO and RICTOR, two oncoproteins that are frequently co-overexpressed through gene amplification on chromosome 5p. TRIO and RICTOR activated RAC/PAK and AKT/mTOR to promote sarcoma cell survival. Inhibition of these proteins with EHop-016 (RAC inhibitor) and INK128 (mTOR inhibitor) had antitumor effects in tumor-derived cell lines and mouse xenografts, and combining the drugs enhanced the effects. Our results demonstrate the importance of integrin-α10/TRIO/RICTOR signaling for driving myxofibrosarcoma progression and provide the basis for promising targeted treatment strategies for patients with high-risk disease. SIGNIFICANCE: Identifying the molecular pathogenesis for myxofibrosarcoma progression has proven challenging given the highly complex genomic alterations in this tumor type. We found that integrin-α10 promotes tumor cell survival through activation of TRIO-RAC-RICTOR-mTOR signaling, and that inhibitors of RAC and mTOR have antitumor effects in vivo, thus identifying a potential treatment strategy for patients with high-risk myxofibrosarcoma. Cancer Discov; 6(10); 1148-65. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 1069.

Near universal detection of alterations in CTNNB1 and Wnt pathway regulators in desmoid-type fibromatosis by whole-exome sequencing and genomic analysis.

CTNNB1 mutations or APC abnormalities have been observed in ∼85% of desmoids examined by Sanger sequencing and are associated with Wnt/ß-catenin activation. We sought to identify molecular aberrations in "wild-type" tumors (those without CTNNB1 or APC alteration) and to determine their prognostic relevance. CTNNB1 was examined by Sanger sequencing in 117 desmoids; a mutation was observed in 101 (86%) and 16 were wild type. Wild-type status did not associate with tumor recurrence. Moreover, in unsupervised clustering based on U133A-derived gene expression profiles, wild-type and mutated tumors clustered together. Whole-exome sequencing of eight of the wild-type desmoids revealed that three had a CTNNB1 mutation that had been undetected by Sanger sequencing. The mutation was found in a mean 16% of reads (vs. 37% for mutations identified by Sanger). Of the other five wild-type tumors sequenced, two had APC loss, two had chromosome 6 loss, and one had mutation of BMI1. The finding of low-frequency CTNNB1 mutation or APC loss in wild-type desmoids was validated in the remaining eight wild-type desmoids; directed miSeq identified low-frequency CTNNB1 mutation in four and comparative genomic hybridization identified APC loss in one. These results demonstrate that mutations affecting CTNNB1 or APC occur more frequently in desmoids than previously recognized (111 of 117; 95%), and designation of wild-type genotype is largely determined by sensitivity of detection methods. Even true CTNNB1 wild-type tumors (determined by next-generation sequencing) may have genomic alterations associated with Wnt activation (chromosome 6 loss/BMI1 mutation), supporting Wnt/ß-catenin activation as the common pathway governing desmoid initiation.

MDM2 turnover and expression of ATRX determine the choice between quiescence and senescence in response to CDK4 inhibition.

CDK4 inhibitors (CDK4i) earned Breakthrough Therapy Designation from the FDA last year and are entering phase III clinical trials in several cancers. However, not all tumors respond favorably to these drugs. CDK4 activity is critical for progression through G1 phase and into the mitotic cell cycle. Inhibiting this kinase induces Rb-positive cells to exit the cell cycle into either a quiescent or senescent state. In this report, using well-differentiated and dedifferentiated liposarcoma (WD/DDLS) cell lines, we show that the proteolytic turnover of MDM2 is required for CDK4i-induced senescence. Failure to reduce MDM2 does not prevent CDK4i-induced withdrawal from the cell cycle but the cells remain in a reversible quiescent state. Reducing MDM2 in these cells drives them into the more stable senescent state. CDK4i-induced senescence associated with loss of MDM2 is also observed in some breast cancer, lung cancer and glioma cell lines indicating that this is not limited to WD/DDLS cells in which MDM2 is overexpressed or in cells that contain wild type p53. MDM2 turnover depends on its E3 ligase activity and expression of ATRX. Interestingly, in seven patients the changes in MDM2 expression were correlated with outcome. These insights identify MDM2 and ATRX as new regulators controlling geroconversion, the process by which quiescent cells become senescent, and this insight may be exploited to improve the activity of CDK4i in cancer therapy.

Surface-enhanced resonance Raman scattering nanostars for high-precision cancer imaging.

The inability to visualize the true extent of cancers represents a significant challenge in many areas of oncology. The margins of most cancer types are not well demarcated because the cancer diffusely infiltrates the surrounding tissues. Furthermore, cancers may be multifocal and characterized by the presence of microscopic satellite lesions. Such microscopic foci represent a major reason for persistence of cancer, local recurrences, and metastatic spread, and are usually impossible to visualize with currently available imaging technologies. An imaging method to reveal the true extent of tumors is desired clinically and surgically. We show the precise visualization of tumor margins, microscopic tumor invasion, and multifocal locoregional tumor spread using a new generation of surface-enhanced resonance Raman scattering (SERRS) nanoparticles, which are termed SERRS nanostars. The SERRS nanostars feature a star-shaped gold core, a Raman reporter resonant in the near-infrared spectrum, and a primer-free silication method. In genetically engineered mouse models of pancreatic cancer, breast cancer, prostate cancer, and sarcoma, and in one human sarcoma xenograft model, SERRS nanostars enabled accurate detection of macroscopic malignant lesions, as well as microscopic disease, without the need for a targeting moiety. Moreover, the sensitivity (1.5 fM limit of detection) of SERRS nanostars allowed imaging of premalignant lesions of pancreatic and prostatic neoplasias. High sensitivity and broad applicability, in conjunction with their inert gold-silica composition, render SERRS nanostars a promising imaging agent for more precise cancer imaging and resection.

Whole-exome sequencing identifies a recurrent NAB2-STAT6 fusion in solitary fibrous tumors.

Solitary fibrous tumors (SFTs) are rare mesenchymal tumors. Here, we describe the identification of a NAB2-STAT6 fusion from whole-exome sequencing of 17 SFTs. Analysis in 53 tumors confirmed the presence of 7 variants of this fusion transcript in 29 tumors (55%), representing a lower bound for fusion frequency at this locus and suggesting that the NAB2-STAT6 fusion is a distinct molecular feature of SFTs.

Copy number losses define subgroups of dedifferentiated liposarcoma with poor prognosis and genomic instability.

PURPOSE: Molecular events underlying progression of well-differentiated liposarcoma (WDLS) to dedifferentiated liposarcoma (DDLS) are poorly defined. This study sought to identify copy number alterations (CNA) associated with dedifferentiation of WDLS, with DDLS morphology, and with patient outcomes. EXPERIMENTAL DESIGN: Fifty-five WDLS and 52 DDLS were analyzed using Agilent 244K comparative genomic hybridization and Affymetrix U133A expression arrays. CNAs were identified by RAE analysis. Thirty-nine of the DDLS specimens were categorized morphologically by a single pathologist. RESULTS: Nine regions of CNA were identified as recurrent in DDLS but not WDLS; 79% of DDLS had at least one of these CNAs. Loss of the chromosome segment 11q23-24, the most common event, was observed only in DDLS that morphologically resembled the genomically complex sarcomas, undifferentiated pleomorphic sarcoma and myxofibrosarcoma. 11q23-24 loss was itself associated with increased genomic complexity in DDLS. Loss of 19q13, but not 11q23-24, was associated with poor prognosis. Median disease-specific survival was shorter for patients with19q13 loss (27 months) than for patients with diploid 19q13 (>90 months; P < 0.0025), and 19q13 loss was associated with local recurrence (HR, 2.86; P = 0.013). Common copy number losses were associated with transcriptional downregulation of potential tumor suppressors and adipogenesis-related genes (e.g., EI24 and CEBPA). CONCLUSIONS: Dedifferentiation of WDLS is associated with recurrent CNAs in 79% of tumors. In DDLS, loss of 11q23-24 is associated with genomic complexity and distinct morphology whereas loss of 19q13 predicts poor prognosis. CNAs in liposarcoma improve risk stratification for patients and will help identify potential tumor suppressors driving liposarcoma progression.

Restoration of C/EBPα in dedifferentiated liposarcoma induces G2/M cell cycle arrest and apoptosis.

Well-differentiated liposarcoma (WDLS) and dedifferentiated liposarcoma (DDLS) represent the most common biological group of liposarcoma, and there is a pressing need to develop targeted therapies for patients with advanced disease. To identify potential therapeutic targets, we sought to identify differences in the adipogenic pathways between DDLS, WDLS, and normal adipose tissue. In a microarray analysis of DDLS (n = 84), WDLS (n = 79), and normal fat (n = 23), C/EBPα, a transcription factor involved in cell cycle regulation and differentiation, was underexpressed in DDLS when compared to both WDLS and normal fat (15.2- and 27.8-fold, respectively). In normal adipose-derived stem cells, C/EBPα expression was strongly induced when cells were cultured in differentiation media, but in three DDLS cell lines, this induction was nearly absent. We restored C/EBPα expression in one of the cell lines (DDLS8817) by transfection of an inducible C/EBPα expression vector. Inducing C/EBPα expression reduced proliferation and caused cells to accumulate in G2/M. Under differentiation conditions, the cell proliferation was reduced further, and 66% of the DDLS cells containing the inducible C/EBPα expression vector underwent apoptosis as demonstrated by annexin V staining. These cells in differentiation conditions expressed early adipocyte-specific mRNAs such as LPL and FABP4, but they failed to accumulate intracellular lipid droplets, a characteristic of mature adipocytes. These results demonstrate that loss of C/EBPα is an important factor in suppressing apoptosis and maintaining the dedifferentiated state in DDLS. Restoring C/EBPα may be a useful therapeutic approach for DDLS.

Small RNA sequencing and functional characterization reveals MicroRNA-143 tumor suppressor activity in liposarcoma.

Liposarcoma remains the most common mesenchymal cancer, with a mortality rate of 60% among patients with this disease. To address the present lack of therapeutic options, we embarked upon a study of microRNA (miRNA) expression alterations associated with liposarcomagenesis with the goal of exploiting differentially expressed miRNAs and the gene products they regulate as potential therapeutic targets. MicroRNA expression was profiled in samples of normal adipose tissue, well-differentiated liposarcoma, and dedifferentiated liposarcoma by both deep sequencing of small RNA libraries and hybridization-based Agilent microarrays. The expression profiles discriminated liposarcoma from normal adipose tissue and well differentiated from dedifferentiated disease. We defined over 40 miRNAs that were dysregulated in dedifferentiated liposarcomas in both the sequencing and the microarray analysis. The upregulated miRNAs included two cancer-associated species (miR-21 and miR-26a), and the downregulated miRNAs included two species that were highly abundant in adipose tissue (miR-143 and miR-145). Restoring miR-143 expression in dedifferentiated liposarcoma cells inhibited proliferation, induced apoptosis, and decreased expression of BCL2, topoisomerase 2A, protein regulator of cytokinesis 1 (PRC1), and polo-like kinase 1 (PLK1). The downregulation of PRC1 and its docking partner PLK1 suggests that miR-143 inhibits cytokinesis in these cells. In support of this idea, treatment with a PLK1 inhibitor potently induced G(2)-M growth arrest and apoptosis in liposarcoma cells. Taken together, our findings suggest that miR-143 re-expression vectors or selective agents directed at miR-143 or its targets may have therapeutic value in dedifferentiated liposarcoma.

Evaluation of linezolid for the treatment of Clostridium difficile infection caused by epidemic strains using an in vitro human gut model.

OBJECTIVES: Therapeutic options in Clostridium difficile infection (CDI) are limited. We examined linezolid activity in vitro and potential therapeutic efficacy using a gut model of CDI. METHODS: MICs were determined by agar incorporation for 118 diverse C. difficile faecal isolates, including epidemic strains and strains with reduced susceptibility to metronidazole. CDI was established in two gut model experiments using C. difficile epidemic strains (ribotypes 027 and 106) and linezolid was dosed to achieve human gut concentrations. RESULTS: Linezolid demonstrated good in vitro activity against 98% of the isolates. Two isolates (PCR ribotypes 023 and 067) demonstrated resistance to linezolid, although supplementary susceptibility testing of ribotype 023 isolates did not detect further resistance. In a gut model that simulates CDI, linezolid reduced the duration of cytotoxin production by C. difficile PCR ribotype 027 without influencing viable counts of vegetative forms of the organism. C. difficile PCR ribotype 106 viable counts declined at a faster rate than those of PCR ribotype 027 following dosing with linezolid, but cytotoxin titres declined at a similar rate to an untreated control. Gut flora perturbation occurring on linezolid exposure reversed after drug cessation. Recrudescence of spore germination with subsequent cytotoxin was seen with the C. difficile ribotype 106 strain. Resistance to linezolid was not detected either during linezolid instillation or post-dosing. CONCLUSIONS: Linezolid may reduce toxin levels, as reported in staphylococci and streptococci. Further evaluation is warranted of the effect of linezolid on expression of C. difficile toxin, and to investigate potential recurrence of CDI following cessation of linezolid.

Expression profiling of liposarcoma yields a multigene predictor of patient outcome and identifies genes that contribute to liposarcomagenesis.

Liposarcomas are the most common type of soft tissue sarcoma but their genetics are poorly defined. To identify genes that contribute to liposarcomagenesis and serve as prognostic candidates, we undertook expression profiling of 140 primary liposarcoma samples, which were randomly split into training set (n = 95) and test set (n = 45). A multigene predictor for distant recurrence-free survival (DRFS) was developed by the supervised principal component method. Expression levels of the 588 genes in the predictor were used to calculate a risk score for each patient. In validation of the predictor in the test set, patients with low risk score had a 3-year DRFS of 83% versus 45% for high risk score patients (P = 0.001). The HR for high versus low score, adjusted for histologic subtype, was 4.42 (95% CI, 1.26-15.55; P = 0.021). The concordance probability for risk score was 0.732. In contrast, the concordance probability for histologic subtype, which had been considered the best predictor of outcome in liposarcoma, was 0.669. Genes related to adipogenesis, DNA replication, mitosis, and spindle assembly checkpoint control were all highly represented in the multigene predictor. Three genes from the predictor, TOP2A, PTK7, and CHEK1, were found to be overexpressed in liposarcoma samples of all five subtypes and in liposarcoma cell lines. RNAi-mediated knockdown of these genes in liposarcoma cell lines reduced proliferation and invasiveness and increased apoptosis. Taken together, our findings identify genes that seem to be involved in liposarcomagenesis and have promise as therapeutic targets, and support the use of this multigene predictor to improve risk stratification for individual patients with liposarcoma.

Effects of exposure of Clostridium difficile PCR ribotypes 027 and 001 to fluoroquinolones in a human gut model.

The incidence of Clostridium difficile infection is increasing, with reports implicating fluoroquinolone use. A three-stage chemostat gut model was used to study the effects of three fluoroquinolones (ciprofloxacin, levofloxacin, and moxifloxacin) on the gut microbiota and two epidemic C. difficile strains, strains of PCR ribotypes 027 and 001, in separate experiments. C. difficile total viable counts, spore counts, and cytotoxin titers were determined. The emergence of C. difficile isolates with reduced antibiotic susceptibility was monitored with fluoroquinolone-containing medium, and molecular analysis of the quinolone resistance-determining region was performed. C. difficile spores were quiescent in the absence of fluoroquinolones. Instillation of each fluoroquinolone led to C. difficile spore germination and high-level cytotoxin production. High-level toxin production occurred after detectable spore germination in all experiments except those with C. difficile PCR ribotype 027 and moxifloxacin, in which marked cytotoxin production preceded detectable germination, which coincided with isolate recovery on fluoroquinolone-containing medium. Three C. difficile PCR ribotype 027 isolates and one C. difficile PCR ribotype 001 isolate from fluoroquinolone-containing medium exhibited elevated MICs (80 to > or =180 mg/liter) and possessed mutations in gyrA or gyrB. These in vitro results suggest that all fluoroquinolones have the propensity to induce C. difficile infection, regardless of their antianaerobe activities. Resistant mutants were seen only following moxifloxacin exposure.

Comparison of oritavancin versus vancomycin as treatments for clindamycin-induced Clostridium difficile PCR ribotype 027 infection in a human gut model.

OBJECTIVES: To compare the efficacy of oritavancin and vancomycin in the treatment of Clostridium difficile infection (CDI) using an in vitro human gut model. METHODS: We induced CDI by instilling clindamycin into an in vitro gut model primed with pooled human faeces and C. difficile ribotype 027 spores. Oritavancin and vancomycin were instilled in separate experiments at levels equivalent to those expected in the faeces (vancomycin) of patients or levels limited by the solubility of the drug (oritavancin). RESULTS: Clindamycin exposure elicited C. difficile proliferation and high-level cytotoxin production in both experiments. Vancomycin instillation reduced vegetative C. difficile numbers within 1 day but did not affect the numbers of C. difficile spores. Oritavancin instillation markedly reduced C. difficile vegetative numbers and spores to below the limits of detection within 2 days. Cytotoxin titres in both experiments declined to the limits of detection after instillation with oritavancin or vancomycin, but did so more quickly (within 5 days) in the vancomycin experiment. Cessation of vancomycin instillation was associated with further C. difficile proliferation and high-level cytotoxin production. Conversely, toxin recrudescence was not observed following cessation of oritavancin. CONCLUSIONS: Both oritavancin and vancomycin were effective in treating clindamycin-induced CDI in a human gut model, but only oritavancin appeared active against spore forms of C. difficile. Furthermore, recurrence of high-level cytotoxin production was observed following vancomycin instillation but not oritavancin. Oritavancin therapy may be more effective in treating CDI than vancomycin, possibly because it may prevent recrudescence of C. difficile spores.

Emergence of reduced susceptibility to metronidazole in Clostridium difficile.

OBJECTIVES: Antimicrobial treatment for Clostridium difficile infection (CDI) has typically been metronidazole, although reports have questioned the efficacy of this option. We screened recently isolated C. difficile (2005-06) for susceptibility to metronidazole and compared results for historic isolates (1995-2001). METHODS: C. difficile ribotypes 001 (n = 86), 106 (n = 81) and 027 (n = 48) and isolates from the 10 other most prevalent ribotypes in Leeds (n = 57) were screened using spiral gradient endpoint analysis (SGE). C. difficile with metronidazole SGE MICs > or = 6 mg/L were analysed further by agar incorporation and Etest. Multiple-locus variable-number tandem-repeat analysis (MLVA) typing was performed for 28 C. difficile isolates. RESULTS: No reduced metronidazole susceptibility was observed in C. difficile ribotypes 106 and 027 (geometric mean SGE MICs 1.11 and 0.90 mg/L, respectively). In contrast, 21 (24.4%) C. difficile ribotype 001 demonstrated reduced susceptibility to metronidazole (geometric mean SGE MICs 3.51 mg/L, P < 0.001). Variations in susceptibility were observed relating to the method and media, but increased metronidazole MICs were confirmed by an agar incorporation method. Geometric mean agar incorporation MICs for historic C. difficile ribotype 001 (n = 72) were 1.03 (range 0.25-2) mg/L compared with 5.94 (4-8) mg/L (P < 0.001) for recent isolates displaying reduced metronidazole susceptibility. MLVA typing revealed two clonal complexes of C. difficile with reduced susceptibility to metronidazole. CONCLUSIONS: We have demonstrated the emergence of reduced susceptibility to metronidazole in 24.4% of the recent C. difficile ribotype 001 isolates from our institution. Our observations could have implications in the clinical setting due to the poor penetration of metronidazole into the colon.

In vitro susceptibility of genotypically distinct and clonal Clostridium difficile strains to oritavancin.

OBJECTIVES: Clostridium difficile infection is a nosocomial disease of increasing importance. First-line treatment is limited to metronidazole or vancomycin. Oritavancin is a lipoglycopeptide with activity against Gram-positive bacteria, including drug-resistant pathogens. MICs of oritavancin, metronidazole and vancomycin for genotypically distinct C. difficile strains, including epidemic C. difficile PCR ribotypes 001 and 027, were determined by agar incorporation and broth macrodilution methods. In agar incorporation methods, the impact of supplements on oritavancin MICs was tested to address oritavancin binding to surfaces. METHODS: Thirty-three genotypically distinct C. difficile strains were identified by PCR ribotyping. Wilkins Chalgren agar incorporation plates containing oritavancin, metronidazole and vancomycin were prepared with and without 0.002% polysorbate-80 (P80) and lysed horse blood (2%). Broth macrodilution MICs of oritavancin, metronidazole and vancomycin were determined in Brucella broth. Inoculated agar incorporation plates and broth macrodilution tubes were cultured anaerobically at 37 degrees C for 48 h. RESULTS: Broth macrodilution MICs were lower than agar incorporation MICs for oritavancin, but not for metronidazole and vancomycin. Oritavancin broth macrodilution MIC(90)s were 2- to 4-fold lower than the corresponding agar incorporation MIC(90)s, while geometric mean MICs were >5-fold lower. Oritavancin broth macrodilution MIC(90)s were approximately 2- and 5-fold lower than those for metronidazole and vancomycin. Metronidazole was the most active antimicrobial agent against C. difficile using agar incorporation methods. Oritavancin agar incorporation MIC(90)s were unaffected by 0.002% P80 and/or 2% lysed horse blood. CONCLUSIONS: Oritavancin was at least 4-fold more potent than vancomycin against the majority (25/33) of C. difficile strains tested by broth macrodilution. Oritavancin activity may be underestimated by agar incorporation methods, regardless of the use of P80 or lysed horse blood.

Resolution of creatine and phosphocreatine 1H signals in isolated human skeletal muscle using HR-MAS 1H NMR.

Proton NMR spectra of freshly isolated human skeletal muscle samples contain creatine and phosphocreatine resonances with distinct chemical shifts that are easily visualized with magic angle spinning (MAS, spinning the sample rapidly at 54.7 degrees with respect to the magnetic field) methods. The identification of the phosphocreatine resonance was based on two findings: that (i) the possible small dipolar coupling does not contribute to line splitting under rapid MAS, and (ii) the 1H signal decreases concurrently with the phosphocreatine resonance observed in 31P NMR experiments. In the MAS 1H spectra, the phosphocreatine resonance remains a singlet with a linewidth of less than 3 Hz. The creatine resonances are split into two peaks with linewidths at half height of approximately 2 and 6 Hz, respectively. The resonance with the broader linewidth represents creatine that is significantly motion-restricted and suggests that a creatine pool in muscle tissue is highly compartmentalized.