The genomic landscape of acute lymphoblastic leukemia with intrachromosomal amplification of chromosome 21.

Intrachromosomal amplification of chromosome 21 defines a subtype of high-risk childhood acute lymphoblastic leukemia (iAMP21-ALL) characterized by copy number changes and complex rearrangements of chromosome 21. The genomic basis of iAMP21-ALL and the pathogenic role of the region of amplification of chromosome 21 to leukemogenesis remains incompletely understood. In this study, using integrated whole genome and transcriptome sequencing of 124 patients with iAMP21-ALL, including rare cases arising in the context of constitutional chromosomal aberrations, we identified subgroups of iAMP21-ALL based on the patterns of copy number alteration and structural variation. This large data set enabled formal delineation of a 7.8 Mb common region of amplification harboring 71 genes, 43 of which were differentially expressed compared with non-iAMP21-ALL ones, including multiple genes implicated in the pathogenesis of acute leukemia (CHAF1B, DYRK1A, ERG, HMGN1, and RUNX1). Using multimodal single-cell genomic profiling, including single-cell whole genome sequencing of 2 cases, we documented clonal heterogeneity and genomic evolution, demonstrating that the acquisition of the iAMP21 chromosome is an early event that may undergo progressive amplification during disease ontogeny. We show that UV-mutational signatures and high mutation load are characteristic secondary genetic features. Although the genomic alterations of chromosome 21 are variable, these integrated genomic analyses and demonstration of an extended common minimal region of amplification broaden the definition of iAMP21-ALL for more precise diagnosis using cytogenetic or genomic methods to inform clinical management.

Lessons learned from regional training of paediatric nephrology fellows in Africa.

BACKGROUND: Access to care for children with kidney disease is limited in less well-resourced regions of the world and paediatric nephrology (PN) workforce development with good practical skills is critical. METHODS: Retrospective review of a PN training program and trainee feedback from 1999 to 2021, based at Red Cross War Memorial Children's Hospital (RCWMCH), University of Cape Town. RESULTS: A regionally appropriate 1-2-year training program enrolled 38 fellows with an initial 100% return rate to their country of origin. Program funding included fellowships from the International Pediatric Nephrology Association (IPNA), International Society of Nephrology (ISN), International Society of Peritoneal Dialysis (ISPD), and the African Paediatric Fellowship Program (APFP). Fellows were trained on both in- and out-patient management of infants and children with kidney disorders. "Hands-on skills" training included examination, diagnosis and management skills, practical insertion of peritoneal dialysis catheters for management of acute kidney injury and kidney biopsies. Of 16 trainees who completed > 1 year of training, 14 (88%) successfully completed subspecialty exams and 9 (56%) completed a master's degree with a research component. PN fellows reported that their training was appropriate and enabled them to make a difference in their respective communities. CONCLUSIONS: This training program has successfully equipped African physicians with the requisite knowledge and skills to provide PN services in resource-constrained areas for children with kidney disease. The provision of funding from multiple organizations committed to paediatric kidney disease has contributed to the success of the program, along with the fellows' commitment to build PN healthcare capacity in Africa. A higher resolution version of the Graphical abstract is available as Supplementary information.

Merging Strategy, Improvisation, and Conversation to Solve Problems in Target Synthesis.

Total synthesis has long been depicted as the quest to conquer the structures created by nature, requiring an unflinching, single-minded devotion to the task. The goal is achieved by chemists with grit, strength of will, and a competitive spirit. While there is some truth to this viewpoint, it does not fully capture the rich experiences gained in this research realm. In our lab, strategic planning, improvisation, and conversation have worked in concert to enable progress. This Account summarizes our efforts to synthesize four different bioactive targets: merrilactone A, rocaglamide, phomactin A, and tetrapetalone A. Certain missteps were integral to success in these synthetic projects. As such, we include the hiccups, and their roles in the evolution of the strategies, along with the results that aligned with our expectations.Two of these projects (merrilactone A and rocaglamide) culminated in the total synthesis of the targets. The challenges presented by merrilactone A spawned a new design strategy for pentannulation using Nazarov cyclization chemistry. This work demonstrated that Lewis acid catalysis is often a viable electrocyclization strategy in activated, polarized pentadienyl cation intermediates. We sought to apply the same logic to the rocaglamide target, but precursors we prepared did not behave according to plan. This situation pushed us to adapt our approach to match the innate reactivity of the substrate, resulting in an on-the-spot improvisation that was not only integral to the success of the project but also expanded our understanding of pentadienyl cation chemistry. In the other two projects (phomactin A and tetrapetalone A), we did not complete a total synthesis but did build the polycyclic core of the target. Even though the hetero [4 + 2] cycloaddition plan for assembling the macrocyclic oxadecalin ring system of phomactin A failed, the original experimental design still enabled us to solve the problem. Through a wholly unanticipated series of events, our focus on the oxadecalin ring system primed us for the discovery of a sequential iodoaldol/oxa-Michael sequence, using the original [4 + 2] building blocks. Then, the bridging ring present in phomactin A demanded we implement this sequence in a transannular fashion. Finally, our successful synthesis of the tetrapetalone core was enabled by consultations with others in the community. Each bond formation seemed to require different expertise, and in three separate instances (C-N cross-coupling, diastereoselective ring-closing metathesis, and oxidative dearomatization) synthetic challenges were overcome through conversation and collaboration.In our experience, the amount of creative power we summon during a target synthesis project correlates directly with the magnitude of the structural challenges we face. When reactivity surprises us, we analyze the problem anew, consult with colleagues, and improvise with the tools at hand. The inevitable misbehavior of a complex system is a strong motivating force, and one that has helped to shape our research program for nearly two decades.

Constitutional and somatic rearrangement of chromosome 21 in acute lymphoblastic leukaemia.

Changes in gene dosage are a major driver of cancer, known to be caused by a finite, but increasingly well annotated, repertoire of mutational mechanisms. This can potentially generate correlated copy-number alterations across hundreds of linked genes, as exemplified by the 2% of childhood acute lymphoblastic leukaemia (ALL) with recurrent amplification of megabase regions of chromosome 21 (iAMP21). We used genomic, cytogenetic and transcriptional analysis, coupled with novel bioinformatic approaches, to reconstruct the evolution of iAMP21 ALL. Here we show that individuals born with the rare constitutional Robertsonian translocation between chromosomes 15 and 21, rob(15;21)(q10;q10)c, have approximately 2,700-fold increased risk of developing iAMP21 ALL compared to the general population. In such cases, amplification is initiated by a chromothripsis event involving both sister chromatids of the Robertsonian chromosome, a novel mechanism for cancer predisposition. In sporadic iAMP21, breakage-fusion-bridge cycles are typically the initiating event, often followed by chromothripsis. In both sporadic and rob(15;21)c-associated iAMP21, the final stages frequently involve duplications of the entire abnormal chromosome. The end-product is a derivative of chromosome 21 or the rob(15;21)c chromosome with gene dosage optimized for leukaemic potential, showing constrained copy-number levels over multiple linked genes. Thus, dicentric chromosomes may be an important precipitant of chromothripsis, as we show rob(15;21)c to be constitutionally dicentric and breakage-fusion-bridge cycles generate dicentric chromosomes somatically. Furthermore, our data illustrate that several cancer-specific mutational processes, applied sequentially, can coordinate to fashion copy-number profiles over large genomic scales, incrementally refining the fitness benefits of aggregated gene dosage changes.

The ability to cross the blood-cerebrospinal fluid barrier is a generic property of acute lymphoblastic leukemia blasts.

Prevention of central nervous system (CNS) relapse is critical for cure of childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Despite this, mechanisms of CNS infiltration are poorly understood, and the timing, frequency, and properties of BCP-ALL blasts entering the CNS compartment are unknown. We investigated the CNS-engrafting potential of BCP-ALL cells xenotransplanted into immunodeficient NOD.Cg- ITALIC! Prkdc (ITALIC! scid) ITALIC! Il2rg (ITALIC! tm1Wjl)/SzJ mice. CNS engraftment was seen in 23 of 29 diagnostic samples (79%): 2 of 2 from patients with overt CNS disease and 21 of 27 from patients thought to be CNS negative by diagnostic lumbar puncture. Histologic findings mimic human pathology and demonstrate that leukemic cells transit the blood-cerebrospinal fluid barrier situated close to the dural sinuses, the site of recently discovered CNS lymphatics. Retrieval of blasts from the CNS showed no evidence for chemokine receptor-mediated selective trafficking. The high frequency of infiltration and lack of selective trafficking led us to postulate that CNS tropism is a generic property of leukemic cells. To test this, we performed serial dilution experiments which showed CNS engraftment in 5 of 6 mice after transplant of as few as 10 leukemic cells. Clonal tracking techniques confirmed the polyclonal nature of CNS-infiltrating cells, with multiple clones engrafting in both the CNS and periphery. Overall, these findings suggest that subclinical seeding of the CNS is likely to be present in most BCP-ALL patients at original diagnosis, and efforts to prevent CNS relapse should concentrate on effective eradication of disease from this site rather than targeting entry mechanisms.

Dynamic clonal progression in xenografts of acute lymphoblastic leukemia with intrachromosomal amplification of chromosome 21.

Intrachromosomal amplification of chromosome 21 is a heterogeneous chromosomal rearrangement occurring in 2% of cases of childhood precursor B-cell acute lymphoblastic leukemia. These abnormalities are too complex to engineer faithfully in animal models and are unrepresented in leukemia cell lines. As a resource for future functional and preclinical studies, we have created xenografts from the leukemic blasts of patients with intrachromosomal amplification of chromosome 21 and characterized them by in-vivo and ex-vivo luminescent imaging, flow immunophenotyping, and histological and ultrastructural analyses of bone marrow and the central nervous system. Investigation of up to three generations of xenografts revealed phenotypic evolution, branching genomic architecture and, compared with other B-cell acute lymphoblastic leukemia genetic subtypes, greater clonal diversity of leukemia-initiating cells. In support of intrachromosomal amplification of chromosome 21 as a primary genetic abnormality, it was always retained through generations of xenografts, although we also observed the first example of structural evolution of this rearrangement. Clonal segregation in xenografts revealed convergent evolution of different secondary genomic abnormalities implicating several known tumor suppressor genes and a region, containing the B-cell adaptor, PIK3AP1, and nuclear receptor co-repressor, LCOR, in the progression of B-cell acute lymphoblastic leukemia. Tracking of mutations in patients and derived xenografts provided evidence for co-operation between abnormalities activating the RAS pathway in B-cell acute lymphoblastic leukemia and for their aggressive clonal expansion in the xeno-environment. Bi-allelic loss of the CDKN2A/B locus was recurrently maintained or emergent in xenografts and also strongly selected as RNA sequencing demonstrated a complete absence of reads for genes associated with the deletions.

CREBBP knockdown enhances RAS/RAF/MEK/ERK signaling in Ras pathway mutated acute lymphoblastic leukemia but does not modulate chemotherapeutic response.

Relapsed acute lymphoblastic leukemia is the most common cause of cancer-related mortality in young people and new therapeutic strategies are needed to improve outcome. Recent studies have shown that heterozygous inactivating mutations in the histone acetyl transferase, CREBBP, are particularly frequent in relapsed childhood acute lymphoblastic leukemia and associated with a hyperdiploid karyotype and KRAS mutations. To study the functional impact of CREBBP haploinsufficiency in acute lymphoblastic leukemia, RNA interference was used to knock down expression of CREBBP in acute lymphoblastic leukemia cell lines and various primagraft acute lymphoblastic leukemia cells. We demonstrate that attenuation of CREBBP results in reduced acetylation of histone 3 lysine 18, but has no significant impact on cAMP-dependent target gene expression. Impaired induction of glucocorticoid receptor targets was only seen in 1 of 4 CREBBP knockdown models, and there was no significant difference in glucocorticoid-induced apoptosis, sensitivity to other acute lymphoblastic leukemia chemotherapeutics or histone deacetylase inhibitors. Importantly, we show that CREBBP directly acetylates KRAS and that CREBBP knockdown enhances signaling of the RAS/RAF/MEK/ERK pathway in Ras pathway mutated acute lymphoblastic leukemia cells, which are still sensitive to MEK inhibitors. Thus, CREBBP mutations might assist in enhancing oncogenic RAS signaling in acute lymphoblastic leukemia but do not alter response to MEK inhibitors.

Analysis of a breakpoint cluster reveals insight into the mechanism of intrachromosomal amplification in a lymphoid malignancy.

A distinct sub-group of B-cell precursor acute lymphoblastic leukemia, defined by intrachromosomal amplification of chromosome 21 (iAMP21), is restricted to older children and has been associated with a poor outcome. Accurate diagnosis is important for appropriate risk stratification for treatment. It could be improved by understanding the initiating mechanism. iAMP21 is characterized by amplification of a 5.1-24 Mb region of chromosome 21, which includes the RUNX1 gene. It is thought to arise through a breakage-fusion-bridge (BFB) mechanism. Breakpoints initiating BFB cycles were determined from recent array data from 18 patients. Three occurred within the PDE9A gene. Other patients with breakpoints in PDE9A were identified by fluorescence in situ hybridization and molecular copy number counting. Sequencing defined a 1.7 Kb breakpoint cluster region, positioned 400 bp distal to an extensive region enriched for CA repeats with the potential to form Z-DNA. None of the rearranged sequences showed the inverted repeat structure characteristic of BFB; instead PDE9A was fused to intergenic regions of chromosome 21 or to genes on other chromosomes. These observations indicated that previously unrecognized complex events, involving microhomology-mediated end joining, preceded or accompanied initiation of the BFB cycle. A chi-like heptomer, CCTCAGC, contained four of the breakpoints, two within PDE9A and two within partner Alu-repeat sequences. This heptomer was closely homologous to a breakpoint hotspot within the TCF3 gene, suggesting involvement of a common novel recombinogenic mechanism that might also contribute to the recombinogenic potential of Alu repeats. These findings provide insight into potential mechanisms involved in the formation of iAMP21.

Genomic characterization implicates iAMP21 as a likely primary genetic event in childhood B-cell precursor acute lymphoblastic leukemia.

Intrachromosomal amplification of chromosome 21 (iAMP21) defines a distinct subgroup of childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) that has a dismal outcome when treated with standard therapy. For improved diagnosis and risk stratification, the initiating genetic events need to be elucidated. To investigate the genetic basis of BCP-ALL, genomes of 94 iAMP21 patients were interrogated by arrays, FISH, and multiplex ligation-dependent probe amplification. Most copy number alterations targeted chromosome 21, reinforcing the complexity of this chromosome. The common region of amplification on chromosome 21 was refined to a 5.1-mb region that included RUNX1, miR-802, and genes mapping to the Down syndrome critical region. Recurrent abnormalities affecting genes in key pathways were identified: IKZF1 (22%), CDKN2A/B (17%), PAX5 (8%), ETV6 (19%), and RB1 (37%). Investigation of clonal architecture provided evidence that these abnormalities, and P2RY8-CRLF2, were secondary to chromosome 21 rearrangements. Patient outcome was uniformly poor with standard therapy irrespective of the presence or absence of these changes. This study has provided evidence that chromosome 21 instability is the only anomaly among those so far investigated that is common to all iAMP21 patients, and therefore the initiating event is likely to be found among the complex structural rearrangements of this abnormal chromosome.

Conflicts of interest ethics: silencing expertise in the development of international clinical practice guidelines.

BACKGROUND: It is unclear whether global experts with financial conflicts of interest (FCOIs) should be included in, be excluded from, or have a limited role in developing international clinical practice guidelines (CPGs). Optimal management of FCOIs to ensure independent, expert CPGs remains ethically contested. OBJECTIVE: To manage FCOIs and examine whether an ethics framework with discussion recusal by experts with FCOIs affects deliberations and voting on a CPG. DESIGN: Development of an ethics framework grounded on transparency and proportional management of COIs, including self-recusal, evaluation of the effect on COIs and CPG process by quantification of voting on recommendations, and qualitative assessment of experts' ethics dialogue. SETTING: International consensus meeting to formulate a CPG in gastroenterology. PARTICIPANTS: 34 experts from 15 countries. MEASUREMENTS: Counting the votes of experts with and without declared FCOIs and qualitative assessment of ethics discussions. RESULTS: 62% of experts reported at least 1 FCOI. Eight out of 21 recommendations presented potential FCOIs. Experts with conflicts recused themselves from discussing 6 of the 8 recommendations, leaving a majority of nonconflicted discussants (median, 22; range, 19 to 26) for the 6 recommendations. Recusals did not affect voting outcomes but may have diluted the richness of the discussions. Ethics dialogue revealed accord on transparency but underscored challenges to proportional management of COIs beyond basic disclosure. Concerns about bias, COI definitions, expertise, and integrity express important international ethics questions. LIMITATION: Small participant numbers and application of the framework to only 1 meeting of 1 CPG. CONCLUSION: An ethics framework may help to identify and manage COIs and catalyze both ethics dialogue and innovative COI standards that seek to balance impartiality and expertise for trusted CPGs. Optimal balancing remains contested. Recommendations include frameworks, interdisciplinary analysis, and international policy initiatives to better manage COIs in the CPG process. PRIMARY FUNDING SOURCE: Canadian Association of Gastroenterology; European Association for Gastroenterology and Endoscopy; Asian Pacific Society of Digestive Endoscopy; and Institute of Diabetes, Metabolism, and Nutrition of the Canadian Institutes of Health Research.

Convergent synthesis of thiodiazole dioxides from simple ketones and amines through an unusual nitrogen-migration mechanism.

We report the modular preparation of dihydro-1,2,5-thiodiazole dioxide heterocycles starting from methyl ketones and primary amines. This one-pot, three-component coupling employs 2,3-dimethylimidazole-1-sulfonyl azide triflate as a coupling reagent and oxidant. The transformation is scalable and various ketones and amines can be used, yielding thiodiazole dioxide products in up to 89% yield. In addition, 15N- and 13C-labeling studies suggest a mechanism involving a 1,2-nitrogen migration. Together with the mechanistic studies, DFT calculations provide insight into the reaction pathway and set the stage for further exploration of the mechanistic nuances of reactions that use sulfamoyl azides. In combination with the demonstrated modularity of the approach reported herein, the derivatization of the thiodiazole dioxide products highlights the potential of this methodology to rapidly access diverse chemical structures.

Disruption to the FOXO-PRDM1 axis resulting from deletions of chromosome 6 in acute lymphoblastic leukaemia.

A common problem in the study of human malignancy is the elucidation of cancer driver mechanisms associated with recurrent deletion of regions containing multiple genes. Taking B-cell acute lymphoblastic leukaemia (B-ALL) and large deletions of 6q [del(6q)] as a model, we integrated analysis of functional cDNA clone tracking assays with patient genomic and transcriptomic data, to identify the transcription factors FOXO3 and PRDM1 as candidate tumour suppressor genes (TSG). Analysis of cell cycle and transcriptomic changes following overexpression of FOXO3 or PRDM1 indicated that they co-operate to promote cell cycle exit at the pre-B cell stage. FOXO1 abnormalities are absent in B-ALL, but like FOXO3, FOXO1 expression suppressed growth of TCF3::PBX1 and ETV6::RUNX1 B-ALL in-vitro. While both FOXOs induced PRDM1 and other genes contributing to late pre-B cell development, FOXO1 alone induced the key transcription factor, IRF4, and chemokine, CXCR4. CRISPR-Cas9 screening identified FOXO3 as a TSG, while FOXO1 emerged as essential for B-ALL growth. We relate this FOXO3-specific leukaemia-protective role to suppression of glycolysis based on integrated analysis of CRISPR-data and gene sets induced or suppressed by FOXO1 and FOXO3. Pan-FOXO agonist Selinexor induced the glycolysis inhibitor TXNIP and suppressed B-ALL growth at low dose (ID50 < 50 nM).

A survey of the practice of after-hours and emergency endoscopy in Canada.

OBJECTIVE: To determine staffing and practice patterns for after-hours endoscopy service in Canada. METHODS: A link to a web-based survey was sent by e-mail to all clinical members of the Canadian Association of Gastroenterology in February 2011. A priori, it was planned to compare variations in practice among gastroenterologists (GIs) performing endoscopy in different regions of Canada, between pediatric and adult GIs, and between university and community hospitals. RESULTS: Of 422 potential respondents, 168 (40%) responded. Of the 139 adult GIs, 61% performed after-hours endoscopy in the endoscopy suite where daytime procedures were performed, 62% had a trained endoscopy nurse available for all procedures, 38% had access to propofol sedation, 12% reprocessed the endoscopes themselves or with the help of a resident, 4% had out-of-hospital patients come directly to their endoscopy suite and 53% were highly satisfied. The adult endoscopists practising at community hospitals were more likely to have an anesthetist attend the procedure. Regional differences were noted, with more involvement of anesthetists (13%) and availability of propofol (50%) in Ontario, more frequent reprocessing of endoscopes in the central reprocessing units in British Columbia (78%) and almost universal availability of a trained endoscopy nurse (96%) with concomitant higher endoscopist satisfaction (84% highly satisfied) in Alberta. CONCLUSIONS: More than one-third of surveyed endoscopists across the country do not have a trained endoscopy nurse to assist in after-hours endoscopy - the time period when urgent patients often present and typically require therapeutic endoscopic interventions. There are significant regional differences in the practice of after-hours endoscopy in Canada.

Planetary stewardship in an urbanizing world: beyond city limits.

Cities are rapidly increasing in importance as a major factor shaping the Earth system, and therefore, must take corresponding responsibility. With currently over half the world's population, cities are supported by resources originating from primarily rural regions often located around the world far distant from the urban loci of use. The sustainability of a city can no longer be considered in isolation from the sustainability of human and natural resources it uses from proximal or distant regions, or the combined resource use and impacts of cities globally. The world's multiple and complex environmental and social challenges require interconnected solutions and coordinated governance approaches to planetary stewardship. We suggest that a key component of planetary stewardship is a global system of cities that develop sustainable processes and policies in concert with its non-urban areas. The potential for cities to cooperate as a system and with rural connectivity could increase their capacity to effect change and foster stewardship at the planetary scale and also increase their resource security.

The Carbon Cost of Travel to a Medical Conference: Modelling the Annual Meeting of the Canadian Association of Gastroenterology.

Objectives: We estimated and compared the travel related carbon emissions of the annual meeting of the Canadian Association of Gastroenterology between the two most common geographical locations of the meeting. Methods: We modelled the car, train and flight travel journey of each registrant to two annual meetings. One was held in Toronto, close to where the majority of Gastroenterogists live, the other in Banff in the west of the country. We used validated carbon emission outputs per kilometer of travel. Results: The average per capita distance travelled to the Toronto meeting was 2845 km, resulting in 0.540 tonnes (t) of CO2equivalent (CO2e) emitted per person. When the meeting was held in Banff emissions were 41% higher than those in Toronto with an average distance travelled of 3949 km and 0.760t of CO2e emitted per person. Almost all of the travel related carbon emissions for both meetings were generated by flying. Conclusions: Even when held close to the largest population centre, there is a large environmental impact from travel to annual meetings. Importantly, choice of meeting location has a very big impact on difference in carbon emissions. Societies need to consider the site of meetings and reduce the number of in-person attendees if they wish to reduce their carbon footprint. Hybrid models participants should be considered. Our analysis also suggests, other medical societies who wish to model their annual meetings can use a simplified model, using flying distance only, to estimate travel-related emissions.

Knowledge gaps in the management of refractory reflux-like symptoms: Healthcare provider survey.

BACKGROUND: Refractory reflux-like symptoms have a substantial impact on patients and healthcare providers. The aim of the survey was to qualitatively assess the needs and attitudes of practicing clinicians around the management of refractory reflux symptoms and refractory gastroesophageal reflux disease (rGERD). METHODS: An International Working Group for the Classification of Oesophagitis (IWGCO) steering committee invited clinicians to complete an online survey including 17 questions. KEY RESULTS: Of the 113 clinicians who completed the survey, 70% were GIs, 20% were primary care physicians, and 10% were other specialties. Functional heartburn was considered the most common reason for an incomplete response to proton pump inhibitor (PPI) therapy (82%), followed by stress/anxiety (69%). More GIs identified esophageal hypersensitivity as a cause, while more non-GIs identified esophageal dysmotility and non-reflux-related esophageal conditions. As the first step, most clinicians would order investigations (70-88%). Overall, 72% would add supplemental therapy for patients with partial response, but only 58% for those with non-response. Antacid/alginate was the most common choice overall, while non-GIs were more likely to add a prokinetic than were GIs (47.8 vs. 24.1%). Approximately 40% of clinicians would switch PPIs in patients with partial response, but only 29% would do so in non-responders. Preferences for long-term therapy were highly variable. The most common initial investigation was upper endoscopy. Choice of esophageal manometry and pH monitoring was more variable, with no clear preference for whether pH monitoring should be conducted on, or off, PPI therapy. CONCLUSIONS AND INFERENCES: The survey identified a number of challenges for clinicians, especially non-GI physicians, treating patients with refractory reflux-like symptoms or rGERD on a daily basis.

hiPSC-derived bone marrow milieu identifies a clinically actionable driver of niche-mediated treatment resistance in leukemia.

Leukemia cells re-program their microenvironment to augment blast proliferation and enhance treatment resistance. Means of clinically targeting such niche-driven treatment resistance remain ambiguous. We develop human induced pluripotent stem cell (hiPSC)-engineered niches to reveal druggable cancer-niche dependencies. We reveal that mesenchymal (iMSC) and vascular niche-like (iANG) hiPSC-derived cells support ex vivo proliferation of patient-derived leukemia cells, affect dormancy, and mediate treatment resistance. iMSCs protect dormant and cycling blasts against dexamethasone, while iANGs protect only dormant blasts. Leukemia proliferation and protection from dexamethasone-induced apoptosis is dependent on cancer-niche interactions mediated by CDH2. Consequently, we test CDH2 antagonist ADH-1 (previously in Phase I/II trials for solid tumors) in a very aggressive patient-derived xenograft leukemia mouse model. ADH-1 shows high in vivo efficacy; ADH-1/dexamethasone combination is superior to dexamethasone alone, with no ADH-1-conferred additional toxicity. These findings provide a proof-of-concept starting point to develop improved, potentially safer therapeutics targeting niche-mediated cancer dependencies in blood cancers.

Point-of-care, peer-comparator colonoscopy practice audit: The Canadian Association of Gastroenterology Quality Program--Endoscopy.

BACKGROUND: Point-of-care practice audits allow documentation of procedural outcomes to support quality improvement in endoscopic practice. OBJECTIVE: To evaluate a colonoscopists' practice audit tool that provides point-of-care data collection and peer-comparator feedback. METHODS: A prospective, observational colonoscopy practice audit was conducted in academic and community endoscopy units for unselected patients undergoing colonoscopy. Anonymized colonoscopist, patient and practice data were collected using touchscreen smartphones with automated data upload for data analysis and review by participants. The main outcome measures were the following colonoscopy quality indicators: colonoscope insertion and withdrawal times, bowel preparation quality, sedation, immediate complications and polypectomy, and biopsy rates. RESULTS: Over a span of 16 months, 62 endoscopists reported on 1279 colonoscopy procedures. The mean cecal intubation rate was 94.9% (10th centile 84.2%). The mean withdrawal time was 8.8 min and, for nonpolypectomy colonoscopies, 41.9% of colonoscopists reported a mean withdrawal time of less than 6 min. Polypectomy was performed in 37% of colonoscopies. Independent predictors of polypectomy included the following: endoscopy unit type, patient age, interval since previous colonoscopy, bowel preparation quality, stable inflammatory bowel disease, previous colon polyps and withdrawal time. Withdrawal times of less than 6 min were associated with lower polyp removal rates (mean difference -11.3% [95% CI -2.8% to -19.9%]; P=0.01). DISCUSSION: Cecal intubation rates exceeded 90% and polypectomy rates exceeded 30%, but withdrawal times were frequently shorter than recommended. There are marked practice variations consistent with previous observations. CONCLUSION: Real-time, point-of-care practice audits with prompt, confidential access to outcome data provide a basis for targeted educational programs to improve quality in colonoscopy practice.

International consensus recommendations on the management of patients with nonvariceal upper gastrointestinal bleeding.

DESCRIPTION: A multidisciplinary group of 34 experts from 15 countries developed this update and expansion of the recommendations on the management of acute nonvariceal upper gastrointestinal bleeding (UGIB) from 2003. METHODS: The Appraisal of Guidelines for Research and Evaluation (AGREE) process and independent ethics protocols were used. Sources of data included original and published systematic reviews; randomized, controlled trials; and abstracts up to October 2008. Quality of evidence and strength of recommendations have been rated by using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. RECOMMENDATIONS: Recommendations emphasize early risk stratification, by using validated prognostic scales, and early endoscopy (within 24 hours). Endoscopic hemostasis remains indicated for high-risk lesions, whereas data support attempts to dislodge clots with hemostatic, pharmacologic, or combination treatment of the underlying stigmata. Clips or thermocoagulation, alone or with epinephrine injection, are effective methods; epinephrine injection alone is not recommended. Second-look endoscopy may be useful in selected high-risk patients but is not routinely recommended. Preendoscopy proton-pump inhibitor (PPI) therapy may downstage the lesion; intravenous high-dose PPI therapy after successful endoscopic hemostasis decreases both rebleeding and mortality in patients with high-risk stigmata. Although selected patients can be discharged promptly after endoscopy, high-risk patients should be hospitalized for at least 72 hours after endoscopic hemostasis. For patients with UGIB who require a nonsteroidal anti-inflammatory drug, a PPI with a cyclooxygenase-2 inhibitor is preferred to reduce rebleeding. Patients with UGIB who require secondary cardiovascular prophylaxis should start receiving acetylsalicylic acid (ASA) again as soon as cardiovascular risks outweigh gastrointestinal risks (usually within 7 days); ASA plus PPI therapy is preferred over clopidogrel alone to reduce rebleeding.

Survey of access to gastroenterology in Canada: the SAGE wait times program.

BACKGROUND: Assessment of current wait times for specialist health services in Canada is a key method that can assist government and health care providers to plan wisely for future health needs. These data are not readily available. A method to capture wait time data at the time of consultation or procedure has been developed, which should be applicable to other specialist groups and also allows for assessment of wait time trends over intervals of years. METHODS: In November 2008, gastroenterologists across Canada were asked to complete a questionnaire (online or by fax) that included personal demographics and data from one week on at least five consecutive new consultations and five consecutive procedure patients who had not previously undergone a procedure for the same indication. Wait times were collected for 18 primary indications and results were then compared with similar survey data collected in 2005. RESULTS: The longest wait times observed were for screening colonoscopy (201 days) and surveillance of previous colon cancer or polyps (272 days). The shortest wait times were for cancer-likely based on imaging or physical examination (82 days), severe or rapidly progressing dysphagia or odynophagia (83 days), documented iron deficiency anemia (90 days) and dyspepsia with alarm symptoms (99 days). Compared with 2005 data, total wait times in 2008 were lengthened overall (127 days versus 155 days; P<0.05) and for most of the seven individual indications that permitted data comparison. CONCLUSION: Median wait times for gastroenterology services continue to exceed consensus conference recommended targets and have significantly worsened since 2005.