Publications by authors named "Lee Roth"

22 Publications

  • Page 1 of 1

An SNX10-dependent mechanism downregulates fusion between mature osteoclasts.

J Cell Sci 2021 May 11;134(9). Epub 2021 May 11.

Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel.

Homozygosity for the R51Q mutation in sorting nexin 10 (SNX10) inactivates osteoclasts (OCLs) and induces autosomal recessive osteopetrosis in humans and in mice. We show here that the fusion of wild-type murine monocytes to form OCLs is highly regulated, and that its extent is limited by blocking fusion between mature OCLs. In contrast, monocytes from homozygous R51Q SNX10 mice fuse uncontrollably, forming giant dysfunctional OCLs that can become 10- to 100-fold larger than their wild-type counterparts. Furthermore, mutant OCLs display reduced endocytotic activity, suggesting that their deregulated fusion is due to alterations in membrane homeostasis caused by loss of SNX10 function. This is supported by the finding that the R51Q SNX10 protein is unstable and exhibits altered lipid-binding properties, and is consistent with a key role for SNX10 in vesicular trafficking. We propose that OCL size and functionality are regulated by a cell-autonomous SNX10-dependent mechanism that downregulates fusion between mature OCLs. The R51Q mutation abolishes this regulatory activity, leading to excessive fusion, loss of bone resorption capacity and, consequently, to an osteopetrotic phenotype in vivo. This article has an associated First Person interview with the joint first authors of the paper.
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http://dx.doi.org/10.1242/jcs.254979DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8182410PMC
May 2021

Reverse and Forward Engineering Multicellular Structures with Optogenetics.

Curr Opin Biomed Eng 2020 Dec 14;16:61-71. Epub 2020 Oct 14.

University of Pennsylvania, Department of Bioengineering, 240 Skirkanich Hall, 210 South 33 Street, Philadelphia, Pennsylvania, 19104, United States.

Understanding how cells self-organize into functional higher-order structures is of great interest, both towards deciphering animal development, as well as for our ability to predictably build custom tissues to meet research and therapeutic needs. The proper organization of cells across length-scales results from interconnected and dynamic networks of molecules and cells. Optogenetic probes provide dynamic and tunable control over molecular events within cells, and thus represent a powerful approach to both dissect and control collective cell behaviors. Here we emphasize the breadth of the optogenetic toolkit and discuss how these methods have already been used to reverse-engineer the design rules of developing organisms. We also offer our perspective on the rich potential for optogenetics to power forward-engineering of tissue assembly towards the generation of bespoke tissues with user-defined properties.
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http://dx.doi.org/10.1016/j.cobme.2020.100250DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7945718PMC
December 2020

ETS Proteins Bind with Glucocorticoid Receptors: Relevance for Treatment of Ewing Sarcoma.

Cell Rep 2019 10;29(1):104-117.e4

Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address:

The glucocorticoid receptor (GR) acts as a ubiquitous cortisol-dependent transcription factor (TF). To identify co-factors, we used protein-fragment complementation assays and found that GR recognizes FLI1 and additional ETS family proteins, TFs relaying proliferation and/or migration signals. Following steroid-dependent translocation of FLI1 and GR to the nucleus, the FLI1-specific domain (FLS) binds with GR and strongly enhances GR's transcriptional activity. This interaction has functional consequences in Ewing sarcoma (ES), childhood and adolescence bone malignancies driven by fusions between EWSR1 and FLI1. In vitro, GR knockdown inhibited the migration and proliferation of ES cells, and in animal models, antagonizing GR (or lowering cortisol) retarded both tumor growth and metastasis from bone to lung. Taken together, our findings offer mechanistic rationale for repurposing GR-targeting drugs for the treatment of patients with ES.
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http://dx.doi.org/10.1016/j.celrep.2019.08.088DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6899513PMC
October 2019

The Prevalence of Irritable Bowel Syndrome Among Board-Certified Medical Doctors In Saudi Arabia: A Cross-sectional Study.

J Can Assoc Gastroenterol 2020 Dec 11;3(6):e32-e36. Epub 2019 Jun 11.

Department of Medicine, King Fahad Specialist Hospital-Dammam, Saudi Arabia.

Introduction: Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders. A pooled analysis showed a global prevalence of 11.2%. Few studies looked at the prevalence of IBS in health care providers. The aim of this study was to determine the prevalence of IBS among board-certified physicians and surgeons.

Methods: Board-certified physicians and surgeons in Saudi Arabia were invited to complete a web-based survey. It included questions regarding participant demographics, specialty, practice type and hours worked per week. The Rome IV-validated questionnaire was used to identify subjects with IBS. The primary outcome of the study was the prevalence of IBS among physicians. Secondary outcomes included exploring the effect on IBS prevalence of age, gender, marital status, work hours, specialty, gastroenterology subspecialty and working in a public versus private hospital.

Results: The final analysis included 594 subjects, with 419 males and a median age of 41. The vast majority (86%) were married. Nearly 90% worked in a public hospital exclusively, and the median number of hours worked per week was 48. The overall prevalence of IBS was 16.3%. In a binary logistic regression model, age (odds ratio [OR] = 0.931, < 0.0001), gender (OR = 0.504, = 0.003) and work hours (OR = 2.397, < 0.0001) significantly predicted the presence of IBS. Marital status and specialty did not predict IBS prevalence.

Discussion: This cross-sectional study shows that the prevalence of IBS among physicians in Saudi Arabia to be 16.3%. IBS was more common in females, those who worked longer hours and younger physicians. There was no association between practicing certain specialties and IBS. However, the lack of difference in our cohort may be attributed to the relatively small sample size from each specialty.
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http://dx.doi.org/10.1093/jcag/gwz020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7678731PMC
December 2020

Phosphorylation of the phosphatase PTPROt at Tyr is a molecular switch that controls osteoclast activity and bone mass in vivo.

Sci Signal 2019 01 8;12(563). Epub 2019 Jan 8.

Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.

Bone resorption by osteoclasts is essential for bone homeostasis. The kinase Src promotes osteoclast activity and is activated in osteoclasts by the receptor-type tyrosine phosphatase PTPROt. In other contexts, however, PTPROt can inhibit Src activity. Through in vivo and in vitro experiments, we show that PTPROt is bifunctional and can dephosphorylate Src both at its inhibitory residue Tyr and its activating residue Tyr Whereas wild-type and PTPROt knockout mice exhibited similar bone masses, mice in which a putative C-terminal phosphorylation site, Tyr, in endogenous PTPROt was replaced with phenylalanine had increased bone mass and reduced osteoclast activity. Osteoclasts from the knock-in mice also showed reduced Src activity. Experiments in cultured cells and in osteoclasts derived from both mouse strains demonstrated that the absence of phosphorylation at Tyr caused PTPROt to dephosphorylate Src at the activating site pTyr In contrast, phosphorylation of PTPROt at Tyr enabled PTPROt to recruit Src through Grb2 and to dephosphorylate Src at the inhibitory site Tyr, thus stimulating Src activity. We conclude that reversible phosphorylation of PTPROt at Tyr is a molecular switch that selects between its opposing activities toward Src and maintains a coherent signaling output, and that blocking this phosphorylation event can induce physiological effects in vivo. Because most receptor-type tyrosine phosphatases contain potential phosphorylation sites at their C termini, we propose that preventing phosphorylation at these sites or its consequences may offer an alternative to inhibiting their catalytic activity to achieve therapeutic benefit.
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http://dx.doi.org/10.1126/scisignal.aau0240DOI Listing
January 2019

SILAC identifies LAD1 as a filamin-binding regulator of actin dynamics in response to EGF and a marker of aggressive breast tumors.

Sci Signal 2018 01 30;11(515). Epub 2018 Jan 30.

Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel.

Mutations mimicking growth factor-induced proliferation and motility characterize aggressive subtypes of mammary tumors. To unravel currently unknown players in these processes, we performed phosphoproteomic analysis on untransformed mammary epithelial cells (MCF10A) that were stimulated in culture with epidermal growth factor (EGF). We identified ladinin-1 (LAD1), a largely uncharacterized protein to date, as a phosphorylation-regulated mediator of the EGF-to-ERK pathway. Further experiments revealed that LAD1 mediated the proliferation and migration of mammary cells. LAD1 was transcriptionally induced, phosphorylated, and partly colocalized with actin stress fibers in response to EGF. Yeast two-hybrid, proximity ligation, and coimmunoprecipitation assays revealed that LAD1 bound to actin-cross-linking proteins called filamins. Cosedimentation analyses indicated that LAD1 played a role in actin dynamics, probably in collaboration with the scaffold protein 14-3-3σ (also called SFN). Depletion of LAD1 decreased the expression of transcripts associated with cell survival and inhibited the growth of mammary xenografts in an animal model. Furthermore, LAD1 predicts poor patient prognosis and is highly expressed in aggressive subtypes of breast cancer characterized as integrative clusters 5 and 10, which partly correspond to triple-negative and HER2-positive tumors. Thus, these findings reveal a cytoskeletal component that is critically involved in cell migration and the acquisition of oncogenic attributes in human mammary tumors.
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http://dx.doi.org/10.1126/scisignal.aan0949DOI Listing
January 2018

An oligoclonal antibody durably overcomes resistance of lung cancer to third-generation EGFR inhibitors.

EMBO Mol Med 2018 02;10(2):294-308

Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel

Epidermal growth factor receptor () mutations identify patients with lung cancer who derive benefit from kinase inhibitors. However, most patients eventually develop resistance, primarily due to the T790M second-site mutation. Irreversible inhibitors (e.g., osimertinib/AZD9291) inhibit T790M-EGFR, but several mechanisms, including a third-site mutation, C797S, confer renewed resistance. We previously reported that a triple mixture of monoclonal antibodies, 3×mAbs, simultaneously targeting EGFR, HER2, and HER3, inhibits T790M-expressing tumors. We now report that 3×mAbs, including a triplet containing cetuximab and trastuzumab, inhibits C797S-expressing tumors. Unlike osimertinib, which induces apoptosis, 3×mAbs promotes degradation of the three receptors and induces cellular senescence. Consistent with distinct mechanisms, treatments combining 3×mAbs plus sub-inhibitory doses of osimertinib synergistically and persistently eliminated tumors. Thus, oligoclonal antibodies, either alone or in combination with kinase inhibitors, might preempt repeated cycles of treatment and rapid emergence of resistance.
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http://dx.doi.org/10.15252/emmm.201708076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5801506PMC
February 2018

A new role of the membrane-type matrix metalloproteinase 16 (MMP16/MT3-MMP) in neural crest cell migration.

Int J Dev Biol 2017 ;61(3-4-5):245-256

Koret School of Veterinary Medicine, The Hebrew University, Rehovot, Israel.

Neural crest cells (NCCs) are a transient population of neuroectodermal-originated cells that populate the dorsal neural tube (dNT), before migrating and giving rise to multiple cell lineages in the developing embryo. Prior to their migration, NCCs undergo epithelial-to-mesenchymal-transition (EMT) through which they lose cell contacts and detach from the dNT to invade their surrounding environment. Multiple signals and transcription factors have been identified to regulate these events. Yet, less is known regarding effectors that act downstream to execute the actual NCC separation and migration. Matrix metalloproteinases (MMPs) are a family of proteases that degrade the extracellular matrix as well as other pericellular proteins during processes of tissue remodeling, angiogenesis and metastasis. Previously, we and others have demonstrated the role of the gelatinases MMP2 and MMP9 during the onset of NCC migration. Several evidences link the cleavage and activation of these secreted gelatinases to the activity of membrane-type MMPs (MT-MMP), such as MMP14 and MMP16, which are tethered to plasma membrane and affect various cellular behaviors. The aim of this study was to investigate whether MMP16 acts in NCCs. Here we demonstrate the expression of MMP16 mRNA and protein in cranial NCCs in avian embryos. Knockdown of MMP16 inhibited NCC migration. This inhibition was rescued by the addition of recombinant MMP16, which was also sufficient to increase proper NCC migration. Furthermore, excess MMP16 caused enhanced NCC EMT, concomitant with degradation of dNT-related proteins, laminin and N-cadherin. Altogether, these results uncover MMP16 as a new effector participating in EMT and in the migration of NCCs.
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http://dx.doi.org/10.1387/ijdb.160286dsDOI Listing
June 2018

A module of inflammatory cytokines defines resistance of colorectal cancer to EGFR inhibitors.

Oncotarget 2016 Nov;7(44):72167-72183

Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, Bologna, Italy.

Epidermal Growth Factor Receptor (EGFR) activates a robust signalling network to which colon cancer tumours often become addicted. Cetuximab, one of the monoclonal antibodies targeting this pathway, is employed to treat patients with colorectal cancer. However, many patients are intrinsically refractory to this treatment, and those who respond develop secondary resistance along time. Mechanisms of cancer cell resistance include either acquisition of new mutations or non genomic activation of alternative signalling routes. In this study, we employed a colon cancer model to assess potential mechanisms driving resistance to cetuximab. Resistant cells displayed increased ability to grow in suspension as colonspheres and this phenotype was associated with poorly organized structures. Factors secreted from resistant cells were causally involved in sustaining resistance, indeed administration to parental cells of conditioned medium collected from resistant cells was sufficient to reduce cetuximab efficacy. Among secreted factors, we report herein that a signature of inflammatory cytokines, including IL1A, IL1B and IL8, which are produced following EGFR pathway activation, was associated with the acquisition of an unresponsive phenotype to cetuximab in vitro. This signature correlated with lack of response to EGFR targeting also in patient-derived tumour xenografts. Collectively, these results highlight the contribution of inflammatory cytokines to reduced sensitivity to EGFR blockade and suggest that inhibition of this panel of cytokines in combination with cetuximab might yield an effective treatment strategy for CRC patients refractory to anti-EGFR targeting.
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http://dx.doi.org/10.18632/oncotarget.12354DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5342152PMC
November 2016

Yield of screening colonoscopy in renal transplant candidates.

Can J Gastroenterol Hepatol 2015 Nov-Dec;29(8):423-6. Epub 2015 Jun 12.

Background: Cardiovascular disease is the most common cause of death among patients with end-stage renal disease undergoing maintenance dialysis. Renal transplantation offers a survival advantage to patients with end-stage renal disease; it is also associated with a three- to fivefold increase in the risk of developing a neoplasm.

Objective: To determine the yield of screening colonoscopy among patients with chronic kidney disease who were considered for renal transplantation.

Methods: Patients were included if they were ≥50 years of age, had chronic kidney disease and were being considered for renal transplantation. They underwent a screening colonoscopy that was performed as part of their pretransplant workup. Data from December 2008 to May 2014 were collected retrospectively for all eligible patients.

Results: During the study period, 433 patients were considered for renal transplantation. Of these, 170 underwent colonoscopies as part of their pretransplant workup. One was excluded because of previous history of colon cancer. Of the 169 procedures performed, ≥1 polyp(s) was diagnosed in 24%. The most common pathological diagnoses were hyperplastic polyp or normal colonic tissue. Fifteen (37%) patients had tubular adenomas and one patient had a sessile serrated adenoma. Advanced adenomas, defined as villous, tubulovillous or high-grade dysplasia, were found in four patients. Adenocarcinoma was diagnosed in one patient.

Conclusion: In a population of asymptomatic potential kidney transplant recipients ≥50 years of age, the prevalence of colorectal adenomatous polyps was 24%. Colonoscopy appeared to be useful as a screening tool in potential transplant recipients.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699600PMC
http://dx.doi.org/10.1155/2015/823835DOI Listing
September 2016

Navigator-3, a modulator of cell migration, may act as a suppressor of breast cancer progression.

EMBO Mol Med 2015 Mar;7(3):299-314

Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel

Dissemination of primary tumor cells depends on migratory and invasive attributes. Here, we identify Navigator-3 (NAV3), a gene frequently mutated or deleted in human tumors, as a regulator of epithelial migration and invasion. Following induction by growth factors, NAV3 localizes to the plus ends of microtubules and enhances their polarized growth. Accordingly, NAV3 depletion trimmed microtubule growth, prolonged growth factor signaling, prevented apoptosis and enhanced random cell migration. Mathematical modeling suggested that NAV3-depleted cells acquire an advantage in terms of the way they explore their environment. In animal models, silencing NAV3 increased metastasis, whereas ectopic expression of the wild-type form, unlike expression of two, relatively unstable oncogenic mutants from human tumors, inhibited metastasis. Congruently, analyses of > 2,500 breast and lung cancer patients associated low NAV3 with shorter survival. We propose that NAV3 inhibits breast cancer progression by regulating microtubule dynamics, biasing directionally persistent rather than random migration, and inhibiting locomotion of initiated cells.
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http://dx.doi.org/10.15252/emmm.201404134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4364947PMC
March 2015

Diurnal suppression of EGFR signalling by glucocorticoids and implications for tumour progression and treatment.

Nat Commun 2014 Oct 3;5:5073. Epub 2014 Oct 3.

Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel.

Signal transduction by receptor tyrosine kinases (RTKs) and nuclear receptors for steroid hormones is essential for body homeostasis, but the cross-talk between these receptor families is poorly understood. We observed that glucocorticoids inhibit signalling downstream of EGFR, an RTK. The underlying mechanism entails suppression of EGFR's positive feedback loops and simultaneous triggering of negative feedback loops that normally restrain EGFR. Our studies in mice reveal that the regulation of EGFR's feedback loops by glucocorticoids translates to circadian control of EGFR signalling: EGFR signals are suppressed by high glucocorticoids during the active phase (night-time in rodents), while EGFR signals are enhanced during the resting phase. Consistent with this pattern, treatment of animals bearing EGFR-driven tumours with a specific kinase inhibitor was more effective if administered during the resting phase of the day, when glucocorticoids are low. These findings support a circadian clock-based paradigm in cancer therapy.
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http://dx.doi.org/10.1038/ncomms6073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4205848PMC
October 2014

Increased duration of dual pegylated interferon and ribavirin therapy for genotype 1 hepatitis C post-liver transplantation increases sustained virologic response: a retrospective review.

Saudi J Gastroenterol 2013 Sep-Oct;19(5):223-9

Department of Gastroenterology and Hepatology, Western University, London, Canada.

Background/aim: In patients with advanced post-transplant hepatitis C virus (HCV) recurrence, antiviral treatment (AVT) with interferon and ribavirin is indicated to prevent graft failure. The aim of this study was to determine and report Canadian data with respect to the safety, efficacy, and spontaneous virologic response (SVR) predictors of AVT among transplanted patients with HCV recurrence.

Patients And Methods: A retrospective chart review was performed on patients transplanted in London, Ontario and Edmonton, Alberta from 2002 to 2012 who were treated for HCV. Demographic, medical, and treatment information was collected and analyzed.

Results: A total of 85 patients with HCV received pegylated interferon with ribavirin post-liver transplantation and 28 of the 65 patients (43%) with genotype 1 achieved SVR. Of the patients having genotype 1 HCV who achieved SVR, there was a significantly lower stage of fibrosis (1.37 ± 0.88 vs. 1.89 ± 0.96; P = 0.03), increased ribavirin dose (total daily dose 1057 ± 230 vs. 856 ± 399 mg; P = 0.02), increased rapid virologic response (RVR) (6/27 vs. 0/31; P = 0.05), increased early virologic response (EVR) (28/28 vs. 18/35; P = 0.006), and longer duration of therapy (54.7 ± 13.4 weeks vs. 40.2 ± 18.7; P = 0.001). A logistic regression model using gender, age, RVR, EVR, anemia, duration of therapy, viral load, years' post-transplant, and type of organ (donation after cardiac death vs. donation after brain death) significantly predicted SVR (P < 0.001), with duration of therapy having a significant odds ratio of 1.078 (P = 0.007).

Conclusions: This study identified factors that predict SVR in HCV-positive patients who received dual therapy post-transplantation. Extending therapy from 48 weeks to 72 weeks of dual therapy is associated with increased SVR rates. Future studies examining the role of extended therapy are needed to confirm these findings, since the current study is a retrospective one.
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http://dx.doi.org/10.4103/1319-3767.118133DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3793474PMC
April 2014

Calponin 2 acts as an effector of noncanonical Wnt-mediated cell polarization during neural crest cell migration.

Cell Rep 2013 Mar 14;3(3):615-21. Epub 2013 Mar 14.

Institute of Zoology, University of Hohenheim, Garbenstrasse 30, 70593 Stuttgart, Germany.

Neural crest cells (NCCs) migrate throughout the embryo to differentiate into cell types of all germ layers. Initial directed NCC emigration relies on planar cell polarity (PCP), which through the activity of the small GTPases RhoA and Rac governs the actin-driven formation of polarized cell protrusions. We found that the actin binding protein calponin 2 (Cnn2) was expressed in protrusions at the leading edge of migratory NCCs in chicks and frogs. Cnn2 knockdown resulted in NCC migration defects in frogs and chicks and randomized outgrowth of cell protrusions in NCC explants. Morphant cells showed central stress fibers at the expense of the peripheral actin network. Cnn2 acted downstream of Wnt/PCP, as migration defects induced by dominant-negative Wnt11 or inhibition of RhoA function were rescued by Cnn2 knockdown. These results suggest that Cnn2 modulates actin dynamics during NCC migration as an effector of noncanonical Wnt/PCP signaling.
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http://dx.doi.org/10.1016/j.celrep.2013.02.015DOI Listing
March 2013

Sleep disruption secondary to overnight call shifts is associated with irritable bowel syndrome in residents: a cross-sectional study.

Am J Gastroenterol 2012 Aug;107(8):1151-6

Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.

Objectives: Sleep disruption has been associated with irritable bowel syndrome (IBS). We hypothesized that residents with greater sleep disruption secondary to intermittent overnight call shifts would have a higher prevalence of IBS.

Methods: Postgraduate residents completed a Web-based survey including demographic data, frequency and characteristics of call shifts, the Rome III questionnaire, and the IBS-quality of life measure.

Results: For every hour of sleep deprivation while on call vs. off call, the odds ratio for an increased likelihood of IBS was 1.32, after adjustment for age and gender. The mean number of calls per block, sleep deprivation while on call, and specialty program vs. family practice each predicted the severity of IBS.

Conclusions: Sleep disruption secondary to overnight call in residents was associated with an increased prevalence of IBS.
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http://dx.doi.org/10.1038/ajg.2011.486DOI Listing
August 2012

A cross-sectional study of the association between overnight call and irritable bowel syndrome in medical students.

Can J Gastroenterol 2012 May;26(5):281-4

Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5W9, Canada.

Background: Shift work has been associated with irritable bowel syndrome (IBS), which includes gastrointestinal symptoms such as abdominal pain, constipation and diarrhea. Overnight call shifts also lead to a disruption of the endogenous circadian rhythm.

Hypothesis: Medical students who perform intermittent overnight call shifts will demonstrate a higher prevalence of IBS symptoms when compared with medical students who perform no overnight call shifts.

Methods: First- and second-year (preclinical) medical students have no overnight call requirements, whereas third- and fourth-year medical (clerkship) students do have overnight call requirements. All medical students at the Schulich School of Medicine and Dentistry (London, Ontario) were invited to complete an anonymous, web-based survey or an identical paper copy that included demographic data, the Rome III questionnaire and the IBS-Quality of Life measure (IBS-QOL). The prevalence of IBS symptoms and quality of life secondary to those symptoms were determined.

Results: Data were available for 247 medical students (110 preclinical students, 118 clerkship students and 19 excluded surveys). There was no significant difference in the presence of IBS between preclinical and clerkship students (21 of 110 [19.1%] versus 26 of 118 [22.0%]; P=0.58). The were no significant differences in mean (± SD) IBS-QOL score of those with IBS between preclinical (43.5±8.3) and clerkship students (45.7±13.8) (P=0.53).

Conclusions: Participation in overnight call was not associated with the development of IBS or a lower quality of life secondary to IBS in medical students.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3352844PMC
http://dx.doi.org/10.1155/2012/865915DOI Listing
May 2012

Sargramostim (GM-CSF) for induction of remission in Crohn's disease: a cochrane inflammatory bowel disease and functional bowel disorders systematic review of randomized trials.

Inflamm Bowel Dis 2012 Jul 2;18(7):1333-9. Epub 2012 May 2.

Faculty of Health Sciences, McMaster University, Hamilton, Canada.

Background: We planned to systematically review the efficacy of sargramostim (granulocyte colony stimulating factor [GM-CSF]) for remission induction in patients with Crohn's disease (CD).

Methods: A literature search to April 2011 was performed to identify all randomized trials studying sargramostim in patients with CD. The Cochrane risk of bias tool was used to evaluate study quality and the GRADE criteria were utilized to assess the overall quality of the evidence.

Results: Three randomized studies (total 537 patients) were identified. The risk of bias was low for the three included studies. There was no statistically significant difference in the proportion of patients who achieved clinical remission (GM-CSF 25.3%; placebo 17.5%; relative risk [RR] 1.67; 95% confidence interval [CI] 0.80-3.50; P = 0.17), or 100-point clinical response (GM-CSF 38.3%; placebo 24.8%; RR 1.71 95% CI 0.98-2.97; P = 0.06). There was no statistically significant difference in the proportion of patients (GM-CSF 95.8%; placebo 89.3%) who experienced adverse events (RR 1.07; 95% CI 0.99-1.16; P = 0.08), or serious adverse events (GM-CSF 12.0% vs. placebo 4.8%; RR 2.21; 95% CI 0.84-5.81; P = 0.11).

Conclusions: Sargramostim does not appear to be more effective than placebo for induction of clinical remission or improvement in active CD. However, the GRADE analysis indicates that the overall quality of the evidence for the primary and secondary outcomes was low due to sparse data and heterogeneity, indicating that further research likely would have a significant impact on the effect estimates.
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http://dx.doi.org/10.1002/ibd.22973DOI Listing
July 2012

Somatostatin analogues for the treatment of enterocutaneous fistulas: a systematic review and meta-analysis.

World J Surg 2012 May;36(5):1016-29

Department of General Surgery, University of Western Ontario, 1963 Beaverbrook Ave, London, ON, N6H 5X4, Canada.

Background: Enterocutaneous fistulas are abnormal connections between the skin and gastrointestinal tract that most commonly occur after surgery. Somatostatin analogues have been used in their treatment. The objective of the present study was to determine if somatostatin analogues shorten the time to closure of postoperative enterocutaneous fistulas compared to placebo.

Methods: We searched Medline, EMBase, the Cochrane Central Register of Controlled Trials, as well as reference lists of textbooks and relevant articles for randomized controlled trials (RCT) comparing somatostatin analogues to control in the treatment of postoperative enterocutaneous fistulas. We systematically assessed trials for eligibility and validity, and extracted data in duplicate. We pooled data across studies using a random effects model.

Results: Our initial search yielded 720 studies, of which eight RCT ultimately met eligibility criteria and were included in this review. Somatostatin analogues significantly decreased the time to closure of fistulas compared to placebo {weighted mean difference (WMD)--6.37 days [95% confidence interval (CI) -8.33, -4.42]}. The duration of hospital stay was also significantly decreased with somatostatin analogue treatment [WMD--4.53 days (95% CI -8.29, -0.77)]. No difference in mortality was identified with somatostatin treatment [RR 0.87 (95% CI 0.49-1.55)].

Conclusions: Somatostatin analogues appear to decrease the duration of enterocutaneous fistulas and duration of hospital stay, but no mortality benefit was identified. The quality of evidence for outcomes in this review ranged from low to moderate. Future large, blinded, RCT would be useful in improving the confidence in the treatment effects identified in this systematic review and meta-analysis.
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http://dx.doi.org/10.1007/s00268-012-1494-3DOI Listing
May 2012

Matrix metalloproteinase 9/gelatinase B is required for neural crest cell migration.

Dev Biol 2012 Apr 8;364(2):162-77. Epub 2012 Feb 8.

The Institute of Biochemistry and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University, Rehovot, Israel.

This study determined the role of MMP9/gelatinase B during the migration onset of Neural Crest Cells (NCC) in avian embryos. NCC are neuroepithelial progenitors that convert into mesenchyme and migrate along defined paths throughout the embryo. To engage in migration, NCC loose cell contacts, detach from the neural tube and invade the surrounding environment. Multiple signals and transcription factors that regulate these events have been identified. Nevertheless, little is known regarding effectors that act downstream to execute the actual NCC migration. Matrix metalloproteinases (MMPs) compose a large family of enzymes whose principal substrates are basement membranes, adhesion proteins and the extracellular matrix (ECM) components. A major subgroup of MMPs, the gelatinases (MMP9 and 2) are central to many adult physiological and pathological processes, such as tumor metastasis and angiogenesis, in which cell-cell and cell-matrix contacts are degraded to allow migration. As NCC undergo similar processes during development, we hypothesized that MMP9 may also promote the migration of NCC. MMP9 was found to be expressed in delaminating and migrating NCC of both cranial and trunk axial levels. Blocking MMP9 resulted in a dramatic inhibition of NCC delamination and migration, without perturbing specification or survival. This inhibition occurred at regions containing both premigratory and migrating cells, indicative for the central role of MMP9 in executing the detachment of NCC from the neural tube as well as their migration. Conversely, excess MMP9 enhanced mesenchymalization and delamination of NCC and accelerated progenitors to undergo precocious migration. Examination of the mechanistic activity of MMP9 revealed its capability to degrade the adhesion molecule N-cadherin as well as the basement-membrane protein laminin within or around NCC, respectively. Altogether, our study reveals MMP9 as a novel effector which is required for NCC delamination and migration.
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http://dx.doi.org/10.1016/j.ydbio.2012.01.028DOI Listing
April 2012

Sargramostim (GM-CSF) for induction of remission in Crohn's disease.

Cochrane Database Syst Rev 2011 Nov 9(11):CD008538. Epub 2011 Nov 9.

London Health Sciences Centre - Victoria Hospital, London, Canada.

Background: Crohn's disease is an inflammatory condition of the gut, thought to involve an overactive immune response to gut flora. A novel theory postulates possible immunodeficiency as a cause, and aims to use sargramostim (granulocyte macrophage colony stimulating factor, GM-CSF) to boost the immune system in an effort to test this hypothesis.

Objectives: The primary objectives were to determine the efficacy and safety of sargramostim for induction of remission in patients with clinically active Crohn's disease.

Search Methods: A systematic search of MEDLINE, EMBASE, and CENTRAL was conducted from inception to April 2011. Reference lists of relevant review articles were also searched. Trial registries and abstract databases including Digestive Diseases Week (1980-2010) and United European Gastroenterology Week (2005-2009) were searched to identify studies published in abstract form.

Selection Criteria: Randomized controlled trials of sargramostim for the treatment of patients with active Crohn's disease were considered for inclusion.

Data Collection And Analysis: Data from selected articles were extracted and the Cochrane Risk of Bias tool applied independently by two authors. The primary outcome was induction of clinical remission as defined by a Crohn's Disease Activity Index (CDAI) of < 150 at the end of treatment. Secondary outcomes included clinical responses measures on the CDAI and safety outcomes. Pooled risk ratios (RR) and 95% confidence intervals (CI) were calculated for dichotomous outcomes, in most cases using a random effects model due to high heterogeneity.

Main Results: Three studies were identified, 2 published as full papers and one in abstract form (537 patients). The risk of bias was low for the 3 included studies. There was no statistically significant difference in the proportion of patients (GM-CSF 25.3% versus placebo 17.5%) who achieved clinical remission (RR 1.67; 95% CI 0.80 to 3.50; P = 0.17; 3 studies; 537 patients). There was no statistically significant difference in the proportion of patients (GM-CSF 38.3% versus placebo 24.8%) who achieved a 100-point clinical response (RR 1.71 95% CI 0.98 to 2.97; P = 0.06; 3 studies; 537 patients). There was no statistically significant difference in the proportion of patients (GM-CSF 54.3% versus placebo 44.2%) who achieved a 70 point clinical response (RR 1.23; 95% CI 0.83 to 1.82; P = 0.30; 1 study; 124 patients). There was no statistically significant difference in the proportion of patients (GM-CSF 95.8% versus placebo 89.3%) who experienced at least one adverse event (RR 1.07; 95% CI 0.99 to 1.16; P = 0.08; 2 studies; 251 patients), or serious adverse events (GM-CSF 12.0% versus placebo 4.8%; RR 2.21; 95% CI 0.84 to 5.81; P = 0.11; 2 studies; 251 patients). The incidence of bone pain, musculoskeletal chest pain, and dyspnea were higher in patients treated with sargramostim compared to placebo. Other adverse events commonly associated with sargramostim such as pulmonary capillary leak syndrome, pulmonary edema, heart failure, fever, and neurotoxicity were not reported in these studies.

Authors' Conclusions: Sargramostim does not appear to be more effective than placebo for induction of clinical remission or clinical improvement in patients with active Crohn's disease. However, the GRADE analysis indicates that the overall quality of the evidence for the primary (clinical remission) and secondary outcomes (clinical response) was low indicating that further research is likely to have an impact on the effect estimates.
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http://dx.doi.org/10.1002/14651858.CD008538.pub2DOI Listing
November 2011

Predictors of disease severity in ulcerative colitis patients from Southwestern Ontario.

World J Gastroenterol 2010 Jan;16(2):232-6

Division of Gastroenterology, London Health Sciences Centre, Victoria Hospital, 800 Commissioner's Road East, London, Ontario, N6A 5W9, Canada.

Aim: To understand the demographic characteristics of patients in Southwestern Ontario, Canada with ulcerative colitis (UC) in order to predict disease severity.

Methods: Records from 1996 to 2001 were examined to create a database of UC patients seen in the London Health Sciences Centre South Street Hospital Inflammatory Bowel Disease Clinic. To be included, patients' charts were required to have information of their disease presentation and a minimum of 5 years of follow-up. Charts were reviewed using standardized data collection forms. Disease severity was generated during the chart review process, and non-endoscopic Mayo Score criteria were collected into a composite.

Results: One hundred and two consecutive patients' data were entered into the database. Demographic analyses revealed that 51% of the patients were male, the mean age at diagnosis was 39 years, 13.7% had a first degree relative with inflammatory bowel disease (IBD), 61.8% were nonsmokers and 24.5% were ex-smokers. In 22.5% of patients the disease was limited to the rectum, in 21.6% disease was limited to the sigmoid colon, in 22.5% disease was limited to the left colon, and 32.4% of patients had pancolitis. Standard multiple regression analysis which regressed a composite of physician global assessment of disease severity, average number of bowel movements, and average amount of blood in bowel movements on year of diagnosis and age at time of diagnosis was significant, R(2) = 0.306, F (7, 74) = 4.66, P < 0.01. Delay from symptoms to diagnosis of UC, gender, family history of IBD, smoking status and disease severity at the time of diagnosis did not significantly predict the composite measure.

Conclusion: UC severity is associated with younger age at diagnosis and year of diagnosis in a longitudinal cohort of UC patients, and may identify prognostic UC indicators.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2806562PMC
http://dx.doi.org/10.3748/wjg.v16.i2.232DOI Listing
January 2010

Episodic palpitations in pheochromocytoma.

CMAJ 2009 Nov 28;181(10):714. Epub 2009 Sep 28.

Department of Medicine, London Health Sciences Centre, London, Ontario.

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http://dx.doi.org/10.1503/cmaj.090124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2774366PMC
November 2009