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Recent documents in eScholarship@UMMS
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Linda Cabral and Judy Savageau on Improve Your Surveys by Conducting Cognitive Interviews

Thu, 01/09/2014 - 3:20pm

Blog post to AEA365, a blog sponsored by the American Evaluation Association (AEA) dedicated to highlighting Hot Tips, Cool Tricks, Rad Resources, and Lessons Learned for evaluators. The American Evaluation Association is an international professional association of evaluators devoted to the application and exploration of program evaluation, personnel evaluation, technology, and many other forms of evaluation. Evaluation involves assessing the strengths and weaknesses of programs, policies, personnel, products, and organizations to improve their effectiveness.

MA PCMH Eval Week: Ann Lawthers on Triangulation Using Mixed Methods Appeals to Diverse Stakeholder Interests

Thu, 01/09/2014 - 3:20pm

Blog post to AEA365, a blog sponsored by the American Evaluation Association (AEA) dedicated to highlighting Hot Tips, Cool Tricks, Rad Resources, and Lessons Learned for evaluators. The American Evaluation Association is an international professional association of evaluators devoted to the application and exploration of program evaluation, personnel evaluation, technology, and many other forms of evaluation. Evaluation involves assessing the strengths and weaknesses of programs, policies, personnel, products, and organizations to improve their effectiveness.

This blog post was posted to AEA365 during a week of posts featuring the team at the University of Massachusetts Medical School that helped to evaluate the Massachusetts Patient-Centered Medical Home Initiative.

Prenatal oral health education in U.S. dental schools and obstetrics and gynecology residencies

Thu, 01/09/2014 - 10:25am

Prenatal oral health (POH) is an important health issue, but dental and obstetrical clinicians are not meeting the oral health needs of pregnant patients. This study evaluates how training contributes to this paradox with a national survey of sixty dental school deans and 240 obstetrics and gynecology residency program directors. Response rates were 53 percent and 40 percent for deans and program directors, respectively. According to the respondents, 94 percent of responding dental schools provided POH education, only 39 percent of responding residencies taught POH, and 65 percent of responding deans and 45 percent of responding program directors were aware of current POH guidelines. The residencies exposing trainees to guidelines were three times more likely to have POH training. Barriers to POH education were reported to include too few pregnant patients in clinical settings (for responding dental schools) and lack of faculty expertise (for responding residencies). The majority of responding deans and program directors agreed they would add more POH education if the American College of Obstetricians and Gynecologists issued a policy statement or practice bulletin. The majority of responding dental deans reported teaching POH in their schools, but clinical exposure was limited; less than half of responding residencies included POH training. Future efforts should include distribution of POH guidelines/consensus statements to educators and learners, increasing exposure of dental students to pregnant patients, and developing faculty expertise in residencies.

Glucan particles for selective delivery of siRNA to phagocytic cells in mice

Wed, 01/08/2014 - 1:18pm

Phagocytic macrophages and dendritic cells are desirable targets for potential RNAi (RNA interference) therapeutics because they often mediate pathogenic inflammation and autoimmune responses. We recently engineered a complex 5 component glucan-based encapsulation system for siRNA (small interfering RNA) delivery to phagocytes. In experiments designed to simplify this original formulation, we discovered that the amphipathic peptide Endo-Porter forms stable nanocomplexes with siRNA that can mediate potent gene silencing in multiple cell types. In order to restrict such gene silencing to phagocytes, a method was developed to entrap siRNA-Endo-Porter complexes in glucan shells of 2-4 μm diameter in the absence of other components. The resulting glucan particles containing fluorescently labelled siRNA were readily internalized by macrophages, but not other cell types, and released the labelled siRNA into the macrophage cytoplasm. Intraperitoneal administration of such glucan particles containing siRNA-Endo-Porter complexes to mice caused gene silencing specifically in macrophages that internalized the particles. These results from the present study indicate that specific targeting to phagocytes is mediated by the glucan, whereas Endo-Porter peptide serves both to anchor siRNA within glucan particles and to catalyse escape of siRNA from phagosomes. Thus we have developed a simplified siRNA delivery system that effectively and specifically targets phagocytes in culture or in intact mice.

Functional overlap among distinct G1/S inhibitory pathways allows robust G1 arrest by yeast mating pheromones

Wed, 01/08/2014 - 12:40pm

In budding yeast, mating pheromones arrest the cell cycle in G1 phase via a pheromone-activated Cdk-inhibitor (CKI) protein, Far1. Alternate pathways must also exist, however, because deleting the cyclin CLN2 restores pheromone arrest to far1 cells. Here we probe whether these alternate pathways require the G1/S transcriptional repressors Whi5 and Stb1 or the CKI protein Sic1, whose metazoan analogues (Rb or p27) antagonize cell cycle entry. Removing Whi5 and Stb1 allows partial escape from G1 arrest in far1 cln2 cells, along with partial derepression of G1/S genes, which implies a repressor-independent route for inhibiting G1/S transcription. This route likely involves pheromone-induced degradation of Tec1, a transcriptional activator of the cyclin CLN1, because Tec1 stabilization also causes partial G1 escape in far1 cln2 cells, and this is additive with Whi5/Stb1 removal. Deleting SIC1 alone strongly disrupts Far1-independent G1 arrest, revealing that inhibition of B-type cyclin-Cdk activity can empower weak arrest pathways. Of interest, although far1 cln2 sic1 cells escaped G1 arrest, they lost viability during pheromone exposure, indicating that G1 exit is deleterious if the arrest signal remains active. Overall our findings illustrate how multiple distinct G1/S-braking mechanisms help to prevent premature cell cycle commitment and ensure a robust signal-induced G1 arrest.

Human Cytomegalovirus Reprograms the Expression of Host Micro-RNAs whose Target Networks are Required for Viral Replication: A Dissertation

Wed, 01/08/2014 - 11:49am

The parasitic nature of viruses requires that they adapt to their host environment in order to persist. Herpesviruses are among the largest and most genetically complex human viruses and they have evolved mechanisms that manipulate a variety of cellular pathways and processes required to replicate and persist within their hosts. Human cytomegalovirus (HCMV), a member of the β- herpesvirus sub-family, has the capacity to influence the expression of many host genes in an effort to create an optimal environment for infection. One mechanism utilized by HCMV to alter gene expression is the host RNA interference (RNAi) pathway. This is evidenced by a requirement of host factors to process viral micro-RNAs (miRNAs) and by the dynamic expression of host miRNAs during infection.

The work presented in this dissertation demonstrates that productive HCMV infection reprograms host miRNA expression in order to positively influence infection. I was able to identify a cohort of infection-associated host miRNAs whose change in expression during infection was highly significant. Using the enhancer-promoter sequences of this panel of host miRNAs, I statistically enriched for the presence of functional transcription factor binding sites that regulated the expression of two highly conserved clusters of host miRNAs: miR132/212 and miR143/145. Given that inhibiting their infection-associated change in expression during infection was detrimental to viral replication, it suggests that HCMV mechanistically influences the expression of these miRNA clusters. In order to determine the functional relevance of these miRNAs, I assembled a cohort of potential miRNA target genes using gene expression profiles from primary fibroblasts. By statistically enriching for miRNA recognition elements (MRE) in the respective 3’-UTR sequences, I generated a miRNA target network that includes thousands of host genes. I evaluated the efficacy of our novel miRNA target prediction algorithm by confirming the functionality of enriched MREs present in the 3’-UTR of KRas and by confirming anecdotal miRNA targets from published studies. Gene ontology terms enriched from infection-associated host miRNA target networks suggest that the utility of host miRNAs may extend to multiple host pathways that are required for viral replication. The targeting of multiple miRNAs to shared genes increased the statistical likelihood of target site enrichment. I propose that identifying cooperative miRNA networks is essential to establishing the functional relevance of miRNAs in any context. By combining contextual data on the relative miRNA/mRNA abundance with statistical MRE enrichments, one will be able to more accurately characterize the biological role of miRNAs.

A Role for Intraflagellar Transport Proteins in Mitosis: A Dissertation

Wed, 01/08/2014 - 11:49am

Disruption of cilia proteins results in a range of disorders called ciliopathies. However, the mechanism by which cilia dysfunction contributes to disease is not well understood. Intraflagellar transport (IFT) proteins are required for ciliogenesis. They carry ciliary cargo along the microtubule axoneme while riding microtubule motors. Interestingly, IFT proteins localize to spindle poles in non-ciliated, mitotic cells, suggesting a mitotic function for IFT proteins. Based on their role in cilia, we hypothesized that IFT proteins regulate microtubule-based transport during mitotic spindle assembly. Biochemical investigation revealed that in mitotic cells IFT88, IFT57, IFT52, and IFT20 interact with dynein1, a microtubule motor required for spindle pole maturation. Furthermore, IFT88 co-localizes with dynein1 and its mitotic cargo during spindle assembly, suggesting a role for IFT88 in regulating dynein-mediated transport to spindle poles. Based on these results we analyzed spindle poles after IFT protein depletion and found that IFT88 depletion disrupted EB1, γ-tubulin, and astral microtubule arrays at spindle poles. Unlike IFT88, depletion of IFT57, IFT52, or IFT20 did not disrupt spindle poles. Strikingly, the simultaneous depletion of IFT88 and IFT20 rescued the spindle pole disruption caused by IFT88 depletion alone, suggesting a model in which IFT88 negatively regulates IFT20, and IFT20 negatively regulates microtubulebased transport during mitosis. Our work demonstrates for the first time that IFT proteins function with dynein1 in mitosis, and it also raises the important possibility that mitotic defects caused by IFT protein disruption could contribute to the phenotypes associated with ciliopathies.

Structure-based Targeting of Transcriptional Regulatory Complexes Implicated in Human Disease: A Dissertation

Wed, 01/08/2014 - 11:48am

Transcriptional regulatory complexes control gene expression patterns and permit cellular responses to stimuli. Deregulation of complex components upsets target gene expression and can lead to disease. This dissertation examines proteins involved in two distinct regulatory complexes: C-terminal binding protein (CtBP) 1 and 2, and Interferon Regulatory Factors (IRF) 3 and 5. Although critical in developmental processes and injury response, CtBP transcriptional repression of cell adhesion proteins, pro-apoptotic factors, and tumor suppressors has been linked to the pathogenesis of multiple forms of cancer. IRFs function in the immune system and have been implicated in autoimmune disorders.

Understanding IRF activation is critical to treating pathogens that target IRF function or for future autoimmune disease therapies. We attempted to determine crystal structures that would provide the details of IRF activation, allowing insight into mechanisms of pathogen immune evasion and autoimmune disorders. Although no new structures were solved, we have optimized expression of C-terminal IRF-3 / co-activator complexes, as well as full-length IRF3 and IRF5 constructs. Modifying the constructs coupled with new crystal screening will soon result in structures which detail IRF activation, advancing understanding of the roles of IRF family members in disease.

Through structural and biochemical characterization we sought to identify and develop inhibitors of CtBP transcriptional regulatory functions. High concentrations of CtBP substrate, 4-Methylthio 2-oxobutyric acid (MTOB), have been shown in different cancer models to interfere with CtBP transcriptional regulation. We began the process of structure based drug design by solving crystal structures of both CtBP family members bound to MTOB. The resulting models identified critical ligand contacts and unique active site features, which were utilized in inhibitor design. Potential CtBP inhibitors were identified and co-crystallized with CtBP1. One such compound binds to CtBP more than 1000 times more tightly than does MTOB, as a result of our structure-based inclusion of a phenyl ring and a novel pattern of hydrogen bonding. This molecule provides a starting point for the development of compounds that will both bind more tightly and interfere with transcriptional signaling as we progress towards pharmacologically targeting CtBP as a therapy for specific cancers.

Investigation of Multiple Concerted Mechanisms Underlying Stimulus-induced G1 Arrest in Yeast: A Dissertation

Wed, 01/08/2014 - 11:48am

Progression through the cell cycle is tightly controlled, and the decision whether or not to enter a new cell cycle can be influenced by both internal and external cues. For budding yeast one such external cue is pheromone treatment, which can induce G1 arrest. Two distinct mechanisms are known to be involved in this arrest, one dependent on the arrest protein Far1 and one independent of Far1, but the exact mechanisms have remained enigmatic. The studies presented here further elucidate both of these mechanisms.

We looked at two distinct aspects of the Far1-independent arrest mechanism. First, we studied the role of the G1/S regulatory system in G1 arrest. We found that deletion of the G1/S transcriptional repressors Whi5 and Stb1 compromises Far1-independent arrest, but only partially, and that this partial arrest failure correlates to partial de-repression of G1/S transcripts. Deletion of the CKI Sic1, however, is more strongly required for arrest in the absence of Far1, though not when Far1 is present. Together, this demonstrates that functionally overlapping regulatory circuits controlling the G1/S transition collectively provide robustness to the G1 arrest response. We also sought to reexamine the phenomenon of pheromone-induced loss of G1/S cyclin proteins, which we suspected could be another Far1-independent arrest mechanism. We confirmed that pheromone treatment has an effect on G1 cyclin protein levels independent of transcriptional control. Our findings suggest that this phenomenon is dependent on SCFGrr1but is at least partly independent of Cdc28 activity, the CDK phosphorylation sites in Cln2, and Far1. We were not, however, able to obtain evidence that pheromone increases the degradation rate of Cln1/2, which raises the possibility that pheromone reduces their synthesis rate instead.

Finally, we also studied the function of Far1 during pheromone-induced G1 arrest. Although it has been assumed that Far1 acts as a G1/S cyclin specific CDK inhibitor, there has been no conclusive evidence that this is the case. Our data, however, suggests that at least part of Far1’s function may actually be to interfere with Cln-CDK/substrate interactions since we saw a significant decrease of co-pulldown of Cln2 and substrates after treatment with pheromone. All together, the results presented here demonstrate that there are numerous independent mechanisms in place to help robustly arrest cells in G1.

Morphogenetic Requirements for Embryo Patterning and the Generation of Stem Cell-derived Mice: A Dissertation

Wed, 01/08/2014 - 11:48am

Cell proliferation and differentiation are tightly regulated processes required for the proper development of multi-cellular organisms. To understand the effects of cell proliferation on embryo patterning in mice, we inactivated Aurora A, a gene essential for completion of the cell cycle. We discovered that inhibiting cell proliferation leads to different outcomes depending on the tissue affected. If the epiblast, the embryonic component, is compromised, it leads to gastrulation failure. However, when Aurora A is inactivated in extra-embryonic tissues, mutant embryos fail to properly establish the anteroposterior axis. Ablation of Aurora A in the epiblast eventually leads to abnormal embryos composed solely of extra-embryonic tissues. We took advantage of this phenomenon to generate embryonic stem (ES) cell-derived mice. We successfully generated newborn pups using this epiblast ablation chimera strategy. Our results highlight the importance of coordinated cell proliferation events in embryo patterning. In addition, epiblast ablation chimeras provide a novel in vivo assay for pluripotency that is simpler and more amenable to use by stem cell researchers.

Argonautes Promote Male Fertility and Provide a Paternal Memory of Germline Gene Expression in C. elegans

Wed, 01/08/2014 - 10:34am

During each life cycle, germ cells preserve and pass on both genetic and epigenetic information. In C. elegans, the ALG-3/4 Argonaute proteins are expressed during male gametogenesis and promote male fertility. Here, we show that the CSR-1 Argonaute functions with ALG-3/4 to positively regulate target genes required for spermiogenesis. Our findings suggest that ALG-3/4 functions during spermatogenesis to amplify a small RNA signal that represents an epigenetic memory of male-specific gene expression. CSR-1, which is abundant in mature sperm, appears to transmit this memory to offspring. Surprisingly, in addition to small RNAs targeting male-specific genes, we show that males also harbor an extensive repertoire of CSR-1 small RNAs targeting oogenesis-specific mRNAs. Together, these findings suggest that C. elegans sperm transmit not only the genome but also epigenetic binary signals in the form of Argonaute/small RNA complexes that constitute a memory of gene expression in preceding generations.

Genetic Deficiency of CD40 in Mice Exacerbates Metabolic Manifestations of Diet-induced Obesity: A Dissertation

Tue, 01/07/2014 - 12:06pm

The past two decades have seen an explosive increase of obesity rates worldwide, with more than one billion adults overweight and 300 million of them obese. Obesity and its associated complications have become leading causes of morbidity and mortality in the United States and major contributing factors to the rising costs of national health care.

The pathophysiology of obesity and type 2 diabetes in rodents and humans is characterized by low-grade inflammation and chronic activation of immune pathways in adipose tissue and liver. The CD40 receptor and its ligand, CD40L, initiate immune cell signaling promoting inflammation, but conflicting data on CD40L-null mice confound its role in obesity-associated insulin resistance. A clear understanding of how CD40 and its ligand communicate to regulate and sustain the inflammatory environment of obesity is lacking. Here we demonstrate that CD40 receptor deficient mice on a high-fat diet display the expected decrease in hepatic cytokine levels, but paradoxically exhibit liver steatosis, insulin resistance and glucose intolerance compared with their age-matched wild-type controls. Hyperinsulinemic-euglycemic clamp studies also demonstrated insulin resistance in glucose utilization by the CD40-null mice compared with wild-type mice. In contrast to liver, visceral adipose tissue in CD40 deficient animals harbors elevated cytokine levels and infiltration of inflammatory cells, particularly macrophages and CD8+ effector T cells. In addition, ex vivo explants of epididymal adipose tissue from CD40-null mice display elevated basal and isoproterenol-stimulated lipolysis, suggesting a potential increase of lipid efflux from visceral fat to the liver.

These findings reveal that 1) CD40-null mice represent an unusual model of hepatic steatosis with reduced hepatic inflammation, and 2) CD40 unexpectedly functions in adipose tissue to attenuate the chronic inflammation associated with obesity, thereby protecting against hepatic steatosis.

Structure and Dynamics of Viral Substrate Recognition and Drug Resistance: A Dissertation

Tue, 01/07/2014 - 12:06pm

Drug resistance is a major problem in quickly evolving diseases, including the human immunodeficiency (HIV) and hepatitis C viral (HCV) infections. The viral proteases (HIV protease and HCV NS3/4A protease) are primary drug targets. At the molecular level, drug resistance reflects a subtle change in the balance of molecular recognition; the drug resistant protease variants are no longer effectively inhibited by the competitive drug molecules but can process the natural substrates with enough efficiency for viral survival. Therefore, the inhibitors that better mimic the natural substrate binding features should result in more robust inhibitors with flat drug resistance profiles. The native substrates adopt a consensus volume when bound to the enzyme, the substrate envelope. The most severe resistance mutations occur at protease residues that are contacted by the inhibitors outside the substrate envelope. To guide the design of robust inhibitors, we investigate the shared and varied properties of substrates with the protein dynamics taken into account to define the dynamic substrate envelope of both viral proteases. The NS3/4A dynamic substrate envelope is compared with inhibitors to detect the structural and dynamic basis of resistance mutation patterns. Comparative analyses of substrates and inhibitors result in a solid list of structural and dynamic features of substrates that are not shared by inhibitors. This study can help guiding the development of novel inhibitors by paying attention to the subtle differences between the binding properties of substrates versus inhibitors.

Investigating Cancer Molecular Genetics using Genome-wide RNA Interference Screens: A Dissertation

Tue, 01/07/2014 - 12:06pm

The development of RNAi based technologies has given researchers the tools to interrogate processes as diverse as cancer biology, metabolism and organ development. Here I employ genome-wide shRNA screens to discover the genes involved in two different processes in carcinogenesis, oncogene-induced senescence [OIS] and epigenetic silencing of tumor suppressor genes [TSGs].

OIS is a poorly studied yet significant tumor suppressing mechanism in normal cells where they enter cell cycle arrest [senescence] or programmed cell death [apoptosis] in the presence of an activated oncogene. Here I employ a genomewide shRNA screen and identify a secreted protein, IGFBP7, that induces senescence and apoptosis in melanocytes upon introduction of the oncogene BRAFV600E. Expression of BRAFV600E in primary cells leads to synthesis and secretion of IGFBP7, which acts through autocrine/paracrine pathways to inhibit BRAF-MEK-ERK signaling and induce senescence and apoptosis. Apoptosis results from IGFBP7-mediated upregulation of BNIP3L, a proapoptotic BCL2 family protein. Recombinant IGFBP7 has potent pro-apoptotic and anti-tumor activity in mouse xenograft models using BRAFV600E-postive melanoma cell lines. Finally, IGFBP7 is epigenetically silenced in human melanoma samples suggesting IGFBP7 expression is a key barrier to melanoma formation.

Next I investigated the factors involved in epigenetic silencing in cancer. The TSG p14ARFis inactivated in a wide range of cancers by promoter hypermethylation through unknown mechanisms. To discover p14ARF epigenetic silencing factors, I performed a genome-wide shRNA screen and identified ZNF304, a zinc finger transcription factor that contains a Krüppel-associated box [KRAB] repressor domain. I show that ZNF304 binds to the p14ARF promoter and recruits a KRAB co-repressor complex containing KAP1, SETDB1 and DNMT1 for silencing. We find oncogenic RAS signaling to promote the silencing of p14ARF by USP28-mediated stabilization of ZNF304. In addition I find ZNF304 to be overexpressed in human colorectal cancers and responsible for hypermethylation of over 50 TSGs known as Group 2 CIMP marker genes. My findings establish ZNF304 as a novel oncogene that directs epigenetic silencing and facilitates tumorigenicity in colorectal cancer.

Role of Map4k4 in Skeletal Muscle Differentiation: A Dissertation

Tue, 01/07/2014 - 12:06pm

Skeletal muscle is a complicated and heterogeneous striated muscle tissue that serves critical mechanical and metabolic functions in the organism. The process of generating skeletal muscle, myogenesis, is elaborately coordinated by members of the protein kinase family, which transmit diverse signals initiated by extracellular stimuli to myogenic transcriptional hierarchy in muscle cells. Mitogen-activated protein kinases (MAPKs) including p38 MAPK, c-Jun N terminal kinase (JNK) and extracellular signal-regulated protein kinase (ERK) are components of serine/threonine protein kinase cascades that play important roles in skeletal muscle differentiation. The exploration of MAPK upstream kinases identified mitogen activated protein kinase kinase kinase kinase 4 (MAP4K4), a serine/threonine protein kinase that modulates p38 MAPK, JNK and ERK activities in multiple cell lines. Our lab further discovered that Map4k4 regulates peroxisome proliferator-activated receptor γ (PPARγ) translation in cultured adipocytes through inactivating mammalian target of rapamycin (mTOR), which controls skeletal muscle differentiation and hypotrophy in kinase-dependent and -independent manners. These findings suggest potential involvement of Map4k4 in skeletal myogenesis.

Therefore, for the first part of my thesis, I characterize the role of Map4k4 in skeletal muscle differentiation in cultured muscle cells. Here I show that Map4k4 functions as a myogenic suppressor mainly at the early stage of skeletal myogenesis with a moderate effect on myoblast fusion during late-stage muscle differentiation. In agreement, Map4k4 expression and protein kinase activity are declined with myogenic differentiation. The inhibitory effect of Map4k4 on skeletal myogenesis requires its kinase activity. Surprisingly, none of the identified Map4k4 downstream effectors including p38 MAPK, JNK and ERK is involved in the Map4k4-mediated myogenic differentiation. Instead, expression of myogenic regulatory factor Myf5, a positive mediator of skeletal muscle differentiation is transiently regulated by Map4k4 to partially control skeletal myogenesis. Mechanisms by which Map4k4 modulates Myf5 amount have yet to be determined.

In the second part of my thesis, I assess the relationship between Map4k4 and IGF-mediated signaling pathways. Although siRNA-mediated silencing of Map4k4 results in markedly enhanced myotube formation that is identical to the IGF-induced muscle hypertrophic phenotype, and Map4k4 regulates IGF/Akt signaling downstream effector mTOR in cultured adipocytes, Map4k4 appears not to be involved in the IGF-mediated ERK1/2 signaling axis and the IGF-mediated Akt signaling axis in C2C12 myoblasts. Furthermore, Map4k4 does not affect endogenous Akt signaling or mTOR activity during C2C12 myogenic differentiation.

The results presented here not only identify Map4k4 as a novel suppressor of skeletal muscle differentiation, but also add to our knowledge of Map4k4 action on multiple signaling pathways in muscle cells during skeletal myogenesis. The effects that Map4k4 exerts on myoblast differentiation, fusion and Myf5 expression implicate Map4k4 as a potential drug target for muscle mass growth, skeletal muscle regeneration and muscular dystrophy.

Risk Factors for Treatment Failure With Antiosteoporosis Medication: The Global Longitudinal Study of Osteoporosis in Women (GLOW)

Tue, 01/07/2014 - 10:18am

Antiosteoporosis medication (AOM) does not abolish fracture risk, and some individuals experience multiple fractures while on treatment. Therefore, criteria for treatment failure have recently been defined. Using data from the Global Longitudinal Study of Osteoporosis in Women (GLOW), we analyzed risk factors for treatment failure, defined as sustaining two or more fractures while on AOM. GLOW is a prospective, observational cohort study of women aged ≥55 years sampled from primary care practices in 10 countries. Self-administered questionnaires collected data on patient characteristics, fracture risk factors, previous fractures, AOM use, and health status. Data were analyzed from women who used the same class of AOM continuously over 3 survey years and had data available on fracture occurrence. Multivariable logistic regression was used to identify independent predictors of treatment failure. Data from 26,918 women were available, of whom 5550 were on AOM. During follow-up, 73 of 5550 women in the AOM group (1.3%) and 123 of 21,368 in the non-AOM group (0.6%) reported occurrence of two or more fractures. The following variables were associated with treatment failure: lower Short Form 36 Health Survey (SF-36) score (physical function and vitality) at baseline, higher Fracture Risk Assessment Tool (FRAX) score, falls in the past 12 months, selected comorbid conditions, prior fracture, current use of glucocorticoids, need of arms to assist to standing, and unexplained weight loss ≥10 lb (≥4.5 kg). Three variables remained predictive of treatment failure after multivariable analysis: worse SF-36 vitality score (odds ratio [OR] per 10-point increase, 0.85; 95% confidence interval [CI], 0.76-0.95; p = 0.004); two or more falls in the past year (OR, 2.40; 95% CI, 1.34-4.29; p = 0.011), and prior fracture (OR, 2.93; 95% CI, 1.81-4.75; p < 0.0001). The C statistic for the model was 0.712. Specific strategies for fracture prevention should therefore be developed for this subgroup of patients. © 2014 American Society for Bone and Mineral Research.

Timing of video capsule endoscopy relative to overt obscure GI bleeding: implications from a retrospective study

Mon, 01/06/2014 - 11:47am

BACKGROUND: Diagnostic yield of video capsule endoscopy (VCE) may be higher if it is performed closer to the time of overt obscure GI bleeding (OOGIB).

OBJECTIVE: To evaluate the diagnostic yield of VCE and rate of therapeutic intervention for OOGIB for inpatients and outpatients with respect to timing of the intervention.

DESIGN: Retrospective cohort study.

SETTING: Tertiary academic center.

PATIENTS: Patients who had VCE for OOGIB between August 2008 and August 2010.

INTERVENTIONS: VCE for inpatients versus outpatients.

MAIN OUTCOME MEASURES: Diagnostic yield and rate of therapeutic intervention for inpatients versus outpatients.

RESULTS: One hundred forty-four inpatients (65 women) and 116 outpatients (49 women) were included. Diagnostic yield was 65.9% for inpatients versus 53.4% for outpatients (P = .054). Inpatients were divided into those who had VCE within 3 days (<3 >days; n = 90) of admission versus after 3 days (>3 days; n = 54). Active bleeding and/or an angioectasia was found in 44.4% of the3-day group (P = .046) versus 25.8% of the outpatients. Therapeutic intervention was performed in 18.9% of the3-day group (P = .046) versus 10.3% of outpatients. Diagnostic yield and therapeutic intervention rate between the >3-day group and outpatients were not significantly different. Length of stay (days) was less in the3-day cohort (P < .0001).

LIMITATIONS: Long-term outcomes were not studied. This was a retrospective study.

CONCLUSIONS: Early deployment of VCE within 3 days of admission results in a higher diagnostic yield and therapeutic intervention rate and an associated reduction of length of stay.

Sickle cell trait is not associated with endemic Burkitt lymphoma: an ethnicity and malaria endemicity-matched case-control study suggests factors controlling EBV may serve as a predictive biomarker for this pediatric cancer

Fri, 01/03/2014 - 4:02pm

Endemic Burkitt lymphoma (eBL) is associated with Epstein-Barr virus (EBV) and Plasmodium falciparum coinfections. Malaria appears to dysregulate immunity that would otherwise control EBV, thereby contributing to eBL etiology. Juxtaposed to human genetic variants associated with protection from malaria, it has been hypothesized that such variants could decrease eBL susceptibility, historically referred to as "the protective hypothesis." Past studies attempting to link sickle cell trait (HbAS), which is known to be protective against malaria, with protection from eBL were contradictory and underpowered. Therefore, using a case-control study design, we examined HbAS frequency in 306 Kenyan children diagnosed with eBL compared to 537 geographically defined and ethnically matched controls. We found 23.8% HbAS for eBL patients, which was not significantly different compared to 27.0% HbAS for controls [odds ratio (OR) = 0.85; 95% confidence interval (CI) 0.61-1.17; p-value = 0.33]. Even though cellular EBV titers, indicative of the number of latently infected B cells, were significantly higher (p-value < 0.0003) in children residing in malaria holoendemic compared to hypoendemic areas, levels were not associated with HbAS genotype. Combined, this suggests that although HbAS protects against severe malaria and hyperparasitemia, it is not associated with viral control or eBL protection. However, based on receiver operating characteristic curves factors that enable the establishment of EBV persistence, in contrast to those involved in EBV lytic reactivation, may have utility as an eBL precursor biomarker. This has implications for future human genetic association studies to consider variants influencing control over EBV in addition to malaria as risk factors for eBL.

Racial and ethnic differences in primary, unscheduled cesarean deliveries among low-risk primiparous women at an academic medical center: a retrospective cohort study

Fri, 01/03/2014 - 4:02pm

BACKGROUND: Cesarean sections are the most common surgical procedure for women in the United States. Of the over 4 million births a year, one in three are now delivered in this manner and the risk adjusted prevalence rates appear to vary by race and ethnicity. However, data from individual studies provides limited or contradictory information on race and ethnicity as an independent predictor of delivery mode, precluding accurate generalizations. This study sought to assess the extent to which primary, unscheduled cesarean deliveries and their indications vary by race/ethnicity in one academic medical center.

METHODS: A retrospective, cross-sectional cohort study was conducted of 4,483 nulliparous women with term, singleton, and vertex presentation deliveries at a major academic medical center between 2006-2011. Cases with medical conditions, risk factors, or pregnancy complications that can contribute to increased cesarean risk or contraindicate vaginal birth were excluded. Multinomial logistic regression analysis was used to evaluate differences in delivery mode and caesarean indications among racial and ethnic groups.

RESULTS: The overall rate of cesarean delivery in our cohort was 16.7%. Compared to White women, Black and Asian women had higher rates of cesarean delivery than spontaneous vaginal delivery, (adjusted odds ratio {AOR}: 1.43; 95% CI: 1.07, 1.91, and AOR: 1.49; 95% CI: 1.02, 2.17, respectively). Black women were also more likely, compared to White women, to undergo cesarean for fetal distress and indications diagnosed in the first stage as compared to the second stage of labor.

CONCLUSIONS: Racial and ethnic differences in delivery mode and indications for cesareans exist among low-risk nulliparas at our institution. These differences may be best explained by examining the variation in clinical decisions that indicate fetal distress and failure to progress at the hospital-level.

Identification of a novel variant of LMP-1 of EBV in patients with endemic Burkitt lymphoma in western Kenya

Fri, 01/03/2014 - 4:01pm

BACKGROUND: Epstein Barr virus (EBV) is a gammaherpesvirus that is associated with nasopharyngeal carcinoma (NPC) and endemic Burkitt lymphoma (eBL). EBV carries several latent genes that contribute to oncogenesis including the latent membrane protein 1 (LMP-1), a known oncogene and constitutively active CD40 homolog. Variation in the C terminal region of LMP-1 has been linked to NPC pathogenesis, but little is known regarding LMP-1 variation and eBL.

RESULTS: In the present study, peripheral blood samples were obtained from 38 eBL patients and 22 healthy controls in western Kenya, where the disease is endemic. The LMP-1 C-terminal region from these samples was sequenced and analyzed. The frequency of a 30 base pair deletion of LMP-1 previously linked to NPC was not associated with eBL compared to healthy controls. However a novel LMP-1 variant was identified, called K for Kenya and for the G318K mutation that characterizes it. The K variant LMP-1 was found in 40.5% of eBL sequences and 25.0% of healthy controls. All K variant sequences contained mutations in both of the previously described minimal T cell epitopes in the C terminal end of LMP-1. These mutations occurred in the anchor residue at the C-terminal binding groove of both epitopes, a pocket necessary for MHC loading.

CONCLUSIONS: Overall, our results suggest that there is a novel K variant of LMP-1 in Kenya that may be associated with eBL. Further studies are necessary to determine the functional implications of the LMP-1 variant on early events in eBL genesis.