John Del Valle

Host specificity of Helicobacter pylori strains and host responses in experimentally challenged nonhuman primates

BACKGROUND & AIMS The specificity of colonization by Helicobacter pylori and complex host-bacterium interactions cannot be readily examined in humans. The aim of this study was to perform such analyses in rhesus monkeys. METHODS Four animals that had been cured of natural H. pylori colonization were challenged with a mixture of 7 strains of human origin, and bacteria recovered during periodic videogastroscopy were DNA fingerprinted. RESULTS Three animals carried mixtures of several strains for 4 months, after which strain J166 predominated. In the fourth animal, only strain J238 was isolated from the earliest phase of colonization through 7 months, but strain J166 again became predominant by 10 months after the challenge. Gastritis scores and plasma gastrin and anti-H. pylori immunoglobulin G titers reached levels observed in naturally colonized animals by 4 months after the challenge; however, no plasma immunoglobulin A response was observed up to 10 months. CONCLUSIONS These results show that (1) natural colonization does not elicit protective immunity against subsequent H. pylori challenge; (2) individuals differ in susceptibility to different H. pylori strains during initial stages of colonization; and (3) certain strains are better suited than others for long-term survival in different hosts. These observations show the complexity of H. pylori-host interactions.

Treatment of Helicobacter gastritis with IL-4 requires somatostatin.

Fifty percent of the worlds population is infected with Helicobacter pylori; however, treatment has been insufficient to eradicate the organisms due to rising antibiotic resistance. Helicobacter infection is characterized by induction of a T helper 1 lymphocyte (Th1) immune response, hypergastrinemia, and suppressed tissue somatostatin (SOM) levels. However, the mechanism by which the immune response regulates acid secretion is not known. We show here that treatment with IFN-γ, a Th1 cytokine, was sufficient to induce gastritis, increase gastrin, and decrease SOM levels within 7 days. In contrast, the T helper 2 lymphocyte cytokine IL-4 increased SOM levels and effectively suppressed gastrin expression and secretion. This result demonstrated reciprocal regulation of acid regulatory peptides by immune modulators. IL-4 pretreatment prevented gastritis in infected wild-type but not in SOM null mice. Thus, the ability of IL-4 to oppose a Th1-mediated infection required SOM. Immunofluorescence was used to document the presence of IL-4 receptors on the gastric SOM-secreting cell (D cell). Moreover, IL-4 stimulated SOM release from primary D cell cultures. Treatment of mice chronically infected with Helicobacter felis for 2 mo with the SOM analogue octreotide resolved the inflammation. Thus, a mechanism by which IL-4 resolves inflammation in the stomach is by stimulating the release of SOM from gastric D cells.

Teaching Internal Medicine Residents Quality Improvement and Patient Safety: A Lean Thinking Approach

Patient safety (PS) and quality improvement (QI) are among the highest priorities for all health systems. Resident physicians are often at the front lines of providing care for patients. In many instances, however, QI and PS initiatives exclude trainees. By aligning the goals of the health system with those of the residency program to engage residents in QI and PS projects, there is a unique opportunity to fulfill both a corporate and educational mission to improve patient care. Here, the authors briefly describe one residency program’s educational curriculum to provide foundational knowledge in QI and PS to all its trainees and highlight a resident team—based project that applied principles of lean thinking to evaluate the process of responding to an in-hospital cardiopulmonary arrest. This approach provided residents with a practical experience but also presented an opportunity for trainees to align with the health system’s approach to improving quality and safety.

EGF receptor activation stimulates endogenous gastrin gene expression in canine G cells and human gastric cell cultures.

Gastrin release from the antral gastrin-expressing cell (G cell) is regulated by bombesin and luminal factors. Yet, these same extracellular regulators do not stimulate expression of the gene. Since the gastric mucosa expresses large quantities of EGF receptor ligands such as TGFalpha, we examined whether EGF receptor ligands stimulate gastrin gene expression in gastrin-expressing cell cultures. EGF receptor activation of primary cultures stimulated gastrin gene expression about twofold; whereas bombesin treatment of antral G cell cultures stimulated gastrin release but not gene expression. EGF and TGFalpha were weak stimulants of gastrin release. EGF receptor activation of AGS human gastric adenocarcinoma cell line stimulated gastrin gene expression nearly fourfold; and gastrin reporter constructs transfected into AGS cells were stimulated more than fourfold by EGF. EGF induction was conferred by the previously defined GC-rich gastrin EGF response element (gERE) element located at -68 to -53 bp upstream from the cap site since a mutation of the gERE element abolished both basal and EGF induction. Moreover, EGF treatment of AGS cells stimulated binding of the transcription factor Sp1 to this element. Collectively, these results demonstrate that gastrin gene expression and gastrin release are regulated by different signaling pathways: gene expression by EGF receptor activation and gastrin secretion by neuropeptides and luminal factors.

Gastrin induces c-fos gene transcription via multiple signaling pathways

We previously observed that the trophic actions of gastrin (G17) on the AR42J rat acinar cell line are mediated by mitogen-activated protein kinase (MAPK)-induced c-fos gene transcription via protein kinase C (PKC)-dependent and -independent pathways. In this study, we further investigated the signaling pathways that target c-fos in response to G17. G17 led to a sixfold induction in luciferase activity in cells transfected with plasmids containing the -356+109 sequence of the murine c-fos promoter, which includes the Sis-inducible element (SIE), serum response element (SRE), and the Ca2+/cAMP response element (CRE) regulatory elements. Addition of either the selective PKC inhibitor GF-109203X or the MAPK/extracellular signal-regulated kinase inhibitor PD-98059 resulted in an 80% reduction in luciferase activity. G17 induced the transcriptional activity of both Elk-1 and Sap-1a, transcription factors that bind to the E26 transformation specific (Ets) DNA sequence of the SRE, and this effect was inhibited by both GF-109203X and PD-98059. Point mutations in the Ets sequence led to a 4-fold induction of c-fos transcription stimulated by G17 and to a 1.3-fold induction in response to epidermal growth factor (EGF). In contrast, mutations in the CA rich G (CArG) sequence of the SRE prevented transcriptional activation by both G17 and EGF. G17 induction of the Ets mutant construct was unaffected by either GF-109203X or PD-98059. Because activation of the SRE involves the small GTP-binding protein Rho A, we examined the role of Rho A in G17 induction of c-fos transcription. Inactivation of Rho A by either the specific inhibitor C3 or by expression of a dominant negative Rho A gene inhibited G17 induction of both the wild-type and the Ets mutant constructs by 60%. C3 also inhibited G17-stimulated AR42J cell proliferation. Thus G17 targets the c-fos promoter CArG sequence via Rho A-dependent pathways, and Rho A appears to play an important role in the regulation of the trophic action of G17.

Cell type-specific requirement of the MAPK pathway for the growth factor action of gastrin

Gastrin (G17) has a CCKB receptor-mediated growth-promoting effect on the AR42J rat acinar cell line that is linked to induction of both mitogen-activated protein kinase (MAPK) and c- fos gene expression. We investigated the mechanisms that regulate the growth factor action of G17 on the rat pituitary adenoma cell line GH3. Both AR42J and GH3 cells displayed equal levels of CCKB receptor expression and similar binding kinetics of125I-labeled G17. G17 stimulation of cell proliferation was identical in both cell lines. G17 stimulation of GH3 cell proliferation was completely blocked by the CCKBreceptor antagonist D2 but not by the MEK inhibitor PD-98059 or the protein kinase C inhibitor GF-109203X, which completely inhibited G17 induction of AR42J cell proliferation. G17 induced a c- fos SRE-luciferase reporter gene plasmid more than fourfold in the AR42J cells, whereas it had no effect in the GH3 cells. In contrast to what we observed in the AR42J cells, G17 failed to stimulate MAPK activation and Shc tyrosyl phosphorylation and association with the adapter protein Grb2. Epidermal growth factor induced the MAPK pathway in the GH3 cells, demonstrating the integrity of this signaling system. G17 induced Ca2+ mobilization in both the GH3 and AR42J cells. The calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide inhibited AR42J cell proliferation by 20%, whereas it completely blocked G17 induction of GH3 cell growth. The Ca2+ ionophore ionomycin stimulated GH3 cell proliferation to a level similar to that observed in response to G17, but it had no effect on AR42J cell proliferation. Thus there are cell type specific differences in the requirement of the MAPK pathway for the growth factor action of G17. Whereas in the AR42J cells G17 stimulates cell growth through activation of MAPK and c- fos gene expression, in the GH3 cells, G17 fails to activate MAPK, and it induces cell proliferation through Ca2+-dependent signaling pathways. Furthermore, induction of Ca2+mobilization in the AR42J cells appears not to be sufficient to sustain cell proliferation.Gastrin (G17) has a CCKB receptor-mediated growth-promoting effect on the AR42J rat acinar cell line that is linked to induction of both mitogen-activated protein kinase (MAPK) and c-fos gene expression. We investigated the mechanisms that regulate the growth factor action of G17 on the rat pituitary adenoma cell line GH3. Both AR42J and GH3 cells displayed equal levels of CCKB receptor expression and similar binding kinetics of 125I-labeled G17. G17 stimulation of cell proliferation was identical in both cell lines. G17 stimulation of GH3 cell proliferation was completely blocked by the CCKB receptor antagonist D2 but not by the MEK inhibitor PD-98059 or the protein kinase C inhibitor GF-109203X, which completely inhibited G17 induction of AR42J cell proliferation. G17 induced a c-fos SRE-luciferase reporter gene plasmid more than fourfold in the AR42J cells, whereas it had no effect in the GH3 cells. In contrast to what we observed in the AR42J cells, G17 failed to stimulate MAPK activation and Shc tyrosyl phosphorylation and association with the adapter protein Grb2. Epidermal growth factor induced the MAPK pathway in the GH3 cells, demonstrating the integrity of this signaling system. G17 induced Ca2+ mobilization in both the GH3 and AR42J cells. The calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide inhibited AR42J cell proliferation by 20%, whereas it completely blocked G17 induction of GH3 cell growth. The Ca2+ ionophore ionomycin stimulated GH3 cell proliferation to a level similar to that observed in response to G17, but it had no effect on AR42J cell proliferation. Thus there are cell type specific differences in the requirement of the MAPK pathway for the growth factor action of G17. Whereas in the AR42J cells G17 stimulates cell growth through activation of MAPK and c-fos gene expression, in the GH3 cells, G17 fails to activate MAPK, and it induces cell proliferation through Ca2+-dependent signaling pathways. Furthermore, induction of Ca2+ mobilization in the AR42J cells appears not to be sufficient to sustain cell proliferation.

Impact of a Veterans Affairs Continuity Clinic on Resident Competencies in Women's Health

AbstractBACKGROUND: Education in women’s health is now considered a core curricular component during residency training in Internal Medicine. There is potential for insufficient training in women’s health for residents with a continuity clinic based at a Veterans Affairs (VA) hospital. OBJECTIVE: To determine the impact of a 3-year continuity clinic based at a VA hospital on residents’ self-reported competencies in women’s health. DESIGN: Cross sectional survey using an internal website. SETTING: University-based residency program in Ann Arbor, Michigan. MEASUREMENTS AND MAIN RESULTS: Comparison of residents with a VA clinic with residents with non-VA clinics (university and community) in self-reported competencies in knowledge base, counseling, and physical exam skills in the area of women’s health. Responses were obtained from 66% (n=72) of eligible residents. When compared to residents with either a university hospital- or community-based clinic site, VA-based residents reported less confidence in the majority of competencies surveyed. Clinic site had the strongest impact in the knowledge base domain, accounting for between 17% and 33% of the variance in each specific competency. For estimated number of Pap smears and breast exams done in the prior year, VA-based residents reported doing, on average, less than 5 of each per year while non-VA residents reported doing between 11 and 20 of each exam. CONCLUSIONS: Our data suggest that despite other clinical opportunities in women’s health during ambulatory rotations, regular clinical experiences in women’s health in the continuity clinic setting are necessary to improve education in this area.

Introduction to the mentoring, education, and training corner.

a m f u a t G Welcome to this new section in GASTROENTEROLOGY entitled, Mentoring, Education, and Training Corner (MET Corner). It will focus on a critical aspect of our profession, the education, development, and support of young learners and protéés. We are in a period of steady and exciting change across ociety and the pressures that we face as members of the edical community are a reflection of these changes. Many rgue that being a physician, as we’ve known it, is threatned with transformation from a vocation to a career in hich up-and-coming practitioners are forced to be conerned with finishing a shift rather than caring for the atient in a compassionate and thoughtful manner. Young cientists, independent of their degree, are feeling the presure of shrinking funding margins and the reality of buildng individual recognition in an environment where team cience is flourishing. Moreover, the decreasing number of ndividuals choosing careers in academic medicine, espeially in the physician scientist pathway, is very concerning or the future of scientific discovery and education.1–4 Despite all of these potential challenges, there are enormous opportunities and intellectual resources that make the present time an extremely exciting one to be part of. In light of this confluence of challenges and opportunities, today more than ever, we need to guide and nurture our trainees to reach their maximal potential as members of our field and do so while maintaining the standards of professionalism in highest regard. In addition, it is essential to provide intellectual resources to the members of our community in an effort to meet the demands of our evolving environment. The science of learning and teaching in medicine has continued to incorporate pedagogical theory and best practices. The number of scientific publications devoted to mentoring, medical education, and training has grown exponentially over the past decade.5–18 Opportunities for ormal training in research methodology, both in basic nd clinical sciences, have also grown (eg, the NIH K wards: http://grants.nih.gov/training/careerdevelopentawards.htm). Unfortunately, due to the at times rantic pace of our professional lives and the large volme of information published, it is often difficult to stay breast of the important contributions being made in hese areas. Our goal is to provide the readership of ASTROENTEROLOGY a series of mini-reviews on the topics of mentoring, education, and training, bringing to the forefront the evidence available for best practices. Our expert guest authors will provide reviews on a wide array of topics extending from career opportunities in all aspects of our field, to the key steps to success in ones chosen discipline, to gender and ethnic diversity, to training updates, to the balancing of home-life with work-life. We will also address timely topics in education, with the hope of providing evidence-based best practices to become more successful teachers during an era of increased regulation on learner’s availability. As part of the process, we will also partner with key committees within the AGA such as the Education & Training and Women’s Committees, in an effort to address topics and issues relevant to the membership at large. The material presented will be organized by overarching themes. For example, our initial series of articles will be devoted to a host of topics on mentoring, education, and training within an academic environment. Given the somewhat unique nature of this section as a regular feature, we hope that our readers will find it of interest and will also provide us with input and topics they would like to see covered. To inaugurate this section we’ve asked the former President of the AGA Institute, Dr Tadataka (Tachi) Yamada to share his perspective on mentoring. Dr Yamada has had an extraordinary journey through an illustrious career. The journey has included academic medicine, serving as Chairman of the Department of Internal Medicine at the University of Michigan Medical School; industry as Director of Research and Development and member of the Board of Directors at GlaxoSmithKline; and most recently, his energy has been directed to the realm of charitable enterprise, serving as the President of the Global Health Program for the Gates Foundation. Mentorship has also played a central role in

Response to the Institute of Medicine's Recommendations on Resident Duty Hours: The Medical Residency Program and GI Fellowship Viewpoints

In December 2008, the Institute of Medicine released a report (www.iom.edu/residenthours) on the Accreditation Council for Graduate Medical Educations current duty hour regulations for medical residents. The following two articles address the reports recommendations from the perspectives of the medical residency program and GI fellowship.

Hepatectomy impairs hepatic processing of somatostatin-14.

Somatostatin-14 (SS-14) inhibits the hepatotrophic effect of a variety of growth factors in cultured hepatocytes. We hypothesized that hepatic somatostatin processing might be altered during regeneration. Male Sprague-Dawley rats underwent the intraportal injection of radiolabeled SS-14 after sham or 70% hepatectomy. To study the mechanisms of hepatic SS-14 transport in the rat, the lysosomal enzyme inhibitors, chloroquine and leupeptin, and the microtubule inhibitors, vinblastine and colchicine, were administered 1 to 2 hours prior to the intraportal injection of SS-14. Bile was collected, organs were weighed, and radioactivity was quantitated. The analysis of serial timed collections of bile revealed that, for saline, chloroquine, and leupeptin, peak biliary radioactivity appeared at 20 minutes. Pretreatment with vinblastine and colchicine abolished the 20-minute peak of radioactivity. The appearance of biliary and hepatic iodine 125-SS-14 (125I-[tyr11]-SS-14) at various times after 70% hepatectomy showed a significant decrease starting at 2 hours, which persisted for up to 24 hours. In regenerating liver, both vinblastine and chloroquine decreased 125I-[tyr11]-SS-14 in bile and the liver. In summary, after sham or 70% hepatectomy, vinblastine and colchicine inhibit biliary and increase hepatic 125I-[tyr11]-SS-14 accumulation. After 70% hepatectomy was performed, chloroquine also inhibited 125I-[tyr11]-SS-14 accumulation. We concluded that an important mechanism for hepatic regeneration is decreased responsiveness to SS-14, by decreased SS-14 uptake and increased SS-14 degradation.