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I M Modlin

Publications and source records attributed to I M Modlin.

At least 19 recordsLinked to original sources
PubMed2006

Role of CCN2/CTGF in the proliferation of Mastomys enterochromaffin-like cells and gastric carcinoid development.

Mastomys enterochromaffin-like (ECL) cell proliferation is initially gastrin driven, but once neoplasia develops, cells become gastrin autonomous. We hypothesized that CCN2 (CTGF), a mitogenic growth factor, may regulate ECL cell proliferation. A Mastomys GeneChip database was examined (dCHIP) to identify CCN2 expression levels. CCN2 in normal and tumor ECL cell preparations obtained using FACS (100 nM acridine orange) was examined by real-time PCR. CCN2 protein was identified in mucosal and ECL cell preparations by immunohistochemistry. Short-term cultured cells were stimulated with either CCN2 or CCN2 + EGF, and proliferation was measured (MTT assay). The ERK1/2 inhibitor PD-98059 (0.1-100 microM) was assessed in terms of CCN2 (1 ng/ml)-mediated proliferation and ERK1/2 phosphorylation. CCN2 transcript and protein was then examined in clinical gastric carcinoids. The ccn2 transcript was upregulated in tumor samples compared with the normal mucosa (+2.36-fold, P < 0.01). PCR demonstrated that ccn2 was not expressed in FACS-prepared (>98% pure) normal ECL cells but was elevated in tumor ECL cell fractions (41.3 +/- 10.7-fold). Immunostaining of the Mastomys gastric mucosa and FACS preparations confirmed that CCN2 protein was present in ECL tumors but not in normal ECL cells. Neither CCN2 nor CCN2 + EGF stimulated normal ECL cell proliferation. CCN2 stimulated tumor proliferation (EC50 approximately 0.01 ng/ml); EGF significantly augmented (P < 0.01) CCN2-induced tumor cell proliferation (EC50 = 20 pg/ml). PD-98059 inhibited CCN2-induced proliferation (-12 +/- 3%, P < 0.05) and ERK1/2 phosphorylation (-34 +/- 5%, P < 0.05) in tumor cells. In clinical samples, both CCN2 transcript and protein were elevated in gastrin-autonomous carcinoids (P < 0.02) compared with the normal mucosa. In conclusion, CCN2 may be a proliferative regulator of Mastomys ECL neoplastic proliferation once these cells become autonomous of gastrin regulation. Identification of CCN2 in gastric carcinoid tissue may be useful both as an indicator of ECL cell transformation and may define gastrin autonomy, a criteria of gastric carcinoid malignancy.

Animals↗
PubMed2006

Review article: from gastrin to gastro-oesophageal reflux disease--a century of acid suppression.

To commemorate Edkins' discovery of gastrin in 1905, we review a century of progress in the physiology and pathobiology of gastrin and acid secretion especially as it pertains to clinical aspects of gastro-oesophageal reflux disease. Although initially ignored, Edkins' observations eventually led to the enthusiastic investigation of gastrin and acid regulation in peptic ulcer disease, culminating in important therapeutic advances in the management of acid peptic disease. Following the improved understanding of gastric secretory physiology, and the development of acid suppressants with increasing efficacy, the use of surgical intervention for peptic ulcer disease was almost eliminated. Surgery became obsolete with the discovery of Helicobacter pylori. Three other advances are also influencing modern practice: the gastrotoxicity of aspirin and non-steroidal anti-inflammatory drugs is now increasingly appreciated, the role of endoscopy in the diagnosis and therapy of upper gastrointestinal bleeding, and the use of intravenous acid-suppressive agents. The major issue for the future resides within the epidemic of gastro-oesophageal reflux disease. How to diagnose, categorize and treat this condition and how to identify and prevent neoplasia, are the challenges of the new century.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

Isolation, functional characterization, and transcriptome of Mastomys ileal enterochromaffin cells.

Although the enterochromaffin (EC) cell is one of the primary neuroendocrine regulatory cells of the small intestine, the lack of a purified cell system has precluded characterization of the cell and limited precise physiological evaluation. We developed methodology to obtain a pure population of Mastomys ileal EC cells, evaluated their functional regulation, and defined the transcriptome. Mastomys ilea were everted, end ligated, pronase-collagenase digested, and Nycodenz gradient centrifuged, and EC cells were collected by fluorescence-activated cell sorting (FACS) of acridine orange-labeled cells. Enrichment was confirmed by immunostaining of tryptophan hydroxylase and chromogranin A, specific EC cell markers, serotonin content, EC cell marker gene expression, and electron microscopy. Pituitary adenylate cyclase-activating polypeptide (PACAP), somatostatin, and gastrin receptor expression was determined by real-time RT-PCR. Live post-FACS-sorted cells were cultured, and the effects of forskolin, isoproterenol, acetylcholine, GABAA, PACAP-38, and gastrin on serotonin secretion were measured by ELISA. GeneChip Affymetrix profiling of FACS-sorted cells was undertaken to obtain the EC cell transcriptome. FACS produced a >70-fold enrichment of EC cells with a serotonin content of 240 +/- 22 ng/mg protein. Preparations were 99 +/- 0.7% pure by immunostaining for tryptophan hydroxylase. Vasoactive intestinal peptide/PACAP receptor 1 (VPAC1) and somatostatin receptor 2 were present, whereas PACAP receptor 1 (PAC1) and CCK2 receptors were undetectable. Forskolin, isoproterenol, and PACAP-38 stimulated serotonin secretion at EC50 values of 5 x 10(-10), 4.5 x 10(-10), and 1.2 x 10(-9) M, respectively. Isoproterenol stimulated cAMP levels by approximately 3.5 +/- 0.62-fold vs. unstimulated cells (EC50 of approximately 10(-9) M). Octreotide, acetylcholine, and GABAA inhibited serotonin secretion with IC50 values of 3 x 10(-11), 3 x 10(-10), and 2.9 x 10(-10) M, respectively. Gastrin had no effect on serotonin secretion. The naive EC cell transcriptome revealed highly expressed EC cell marker genes, the absence of marker genes for other small intestinal cell types, and a receptor profile that included cholinergic, adrenergic, dopaminergic, serotoninergic, GABAergic, and prostaglandin receptors. We were able to isolate homogeneous preparations (>99%) of live ileal EC cells and demonstrated regulation of serotonin secretion as well as established the normal EC cell transcriptome. Application of this methodology to normal and diseased human ileum will facilitate the elucidation of the pathophysiology of EC cells.

Acetylcholine↗
PubMed2005

Edkins and a century of acid suppression.

In 1905, John Edkins (1863-1940) undertook the studies of gastrin that have subsequently formed the basis for a century of investigation into the physiological basis of acid secretion and led to the elucidation of a variety of acid-suppressive pharmacological agents that have revolutionized the management of acid peptic disease. Although his name is known to few, his contributions to the physiology of gastric secretion and his study of spiral organisms in the stomach were prescient and to this day remain models of insightful and rigorous research. As a mentor, his educational impact was exemplified by the fact that he was the first to teach physiology to women in the United Kingdom. Gastrin has evolved from an initially unaccepted phenomenon, to be recognized as an important hormone and a fundamental component of regulatory biology as well as a clinically relevant biomarker of disease. Its critical role in the modulation of acid secretion has become a sine qua non and has been extended to include a broad regulatory proliferative role in the mucosa of the gastrointestinal tract. The pivotal role of gastrin in gastric physiology, biology and clinical medicine is now well accepted and reflects the fundamental contributions that Edkins made to the identification of the agent and the elucidation of its function. As a result of the delineation of the neural and hormonal regulatory mechanisms of acid secretion, the scientific basis of acid peptic disease has become apparent. The identification of histamine receptors and proton pumps has led to the discovery of novel pharmacotherapeutic agents capable of producing acid suppression of such efficacy that surgery has become virtually obsolete in the treatment of the disease process. A century after the initial observations by Edkins of gastrin, the identification of Helicobacter pylori and the ability to eradicate it, as well as the use of the proton pump inhibitor class of drugs, have revolutionized the management of gastroduodenal ulceration and gastroesophageal reflux disease. Both patients and physicians owe a great debt to Edkins, whose seminal observations regarding gastrin initiated an era of gastrointestinal scientific, clinical and pharmacological advance that has culminated in the ability to treat and cure acid peptic disease.

Animals↗
PubMed2004

Global expression analysis of ECL cells in Mastomys natalensis gastric mucosa identifies alterations in the AP-1 pathway induced by gastrin-mediated transformation.

Enterochromaffin-like (ECL) cell hyperplasia and then irreversible neoplasia can be generated in the African rodent Mastomys natalensis using the H2 receptor blocker, loxtidine, for 8-16 wk. We used a GeneChip approach complemented by standard technologies to identify gene expression alterations in the gastric mucosa during gastrin-mediated ECL cell transformation. Gastric mucosa (mucosal scrapping) and ECL cell-enriched fractions were obtained from untreated Mastomys (controls) and from animals treated with loxtidine for 8 wk (hyperplasia). Tumor ECL cells were obtained by hand-dissection of gastric ECL cell nodules from animals treated with loxtidine for >16 wk and from a spontaneously developed ECL cell tumor. RNA was isolated, examined on rat U34A GeneChips, and comparison analysis was performed to identify altered gene expression. Alterations in gene expressions were examined further by immunohistochemistry, quantitative RT-PCR (Q-RT-PCR), sequencing and Western blot. GeneSpring analysis demonstrated alterations in few genes (<20) in hyperplastic and tumor mucosa. The histamine H1 receptor was consistently increased in proliferating mucosa. This gene change was confirmed by Q-RT-PCR. Other genes showing alterations included neural-(chromogranin A and somatostatin), cell-cycle-, and AP-1-associated genes. Immunostaining confirmed alterations in neural markers. Cluster analysis of ECL cell-enriched samples demonstrated that c-fos and junD were differently regulated. Q-RT-PCR and Western blot in prospectively collected gastric mucosal samples confirmed the differential expression of Fos and Jun. The negative regulators of AP-1, JunD, and Menin were decreased in tumor mucosa. A missense of unknown function was noted in the menin gene. Hypergastrinemia in an animal model of gastric carcinoids differentially altered the histamine type 1 receptor and gene expression and protein composition of AP-1. These results suggest that expression of this receptor and an altered composition of AP-1 with a loss of inhibition play a role in ECL cell transformation.

Amino Acid Sequence↗
PubMed2003

Molecular strategies and 111in-labelled somatostatin analogues in defining the management of neuroendocrine tumour disease: a new paradigm for surgical management.

This manuscript provides a gene-chip examination of gastric ECL cell proliferation in an animal model of neuroendocrine tumour disease. Data that were used to identify molecular targets were then utilised to develop novel therapeutic strategies as appropriate adjuncts to surgery in human disease. Alterations in growth-mediated cell signaling (the AP-1 pathway) and in the cell cycle were identified in ECL cell tumours in the animal model and confirmed in human tumour tissue. The growth-inhibitory somatostatin receptor subtype 2 was identified as a potential clinical target. An investigation of patients with neuroendocrine tumours treated using SSTR2 targeted radiotherapy [111In]pentetreotide producing encouraging preliminary results. Fifty-six per cent of patients with evaluable hormone markers demonstrated stable levels or a significant decrease in one or more measured markers. This data demonstrate that gene pathways recognised to be altered in an animal model of a human disease can be used to identify therapeutic agents. This approach was successfully used to discover novel strategies that can be both effective and appropriate adjuncts to surgery for patients with neuroendocrine tumour disease.

Animals↗
PubMed2002

The pepsinogen releasing effect of Helicobacter pylori lipopolysaccharide.

BACKGROUND: Helicobacter pylori lipopolysaccharide (LPS) affects pepsinogen release by a nontoxic mechanism. We hypothesized that this effect was characteristic of the organism and related to the clinical status of the strain. MATERIALS AND METHODS: LPS was isolated from 11 H. pylori strains whose pathogenic profile was known and four other nongastric bacteria. The effects of luminal LPS on guinea pig gastric mucosal pepsinogen release was evaluated using the Ussing chamber technique. CCK-8 (10(-9)M) was used as a positive control. RESULTS: H. pylori LPS dose-dependently stimulated pepsinogen release with a maximal stimulation at 250 microg/ml (approximately 4500; p < .001 vs. control). LPS from other Helicobacter or Campylobacter species had no effect on pepsinogen release. ANOVA demonstrated significant differences in the efficacies of pepsinogen release between the 11 clinical H. pylori strains (p < .0001) despite the fact that they were all cagA+ and 90 had the cytotoxic vacA subtype s1. Physical and chemical disruption of the LPS suggested that both the structure and the carbohydrate composition of this molecule may play a critical role in pepsinogen release. Polymyxin B partly (p < .03) inhibited and dephosphorylation completely inhibited (p = .0002) LPS-stimulated pepsinogen release. CONCLUSION: Pepsinogen release is an innate property of all cagA+H. pylori LPS. The structure of the molecule and composition of side-chains are important in this response which appears to be partially lipid A driven.

Adult↗
PubMed2001

PACAP mediates the neural proliferative pathway of Mastomys enterochromaffin-like cell transformation.

BACKGROUND AND AIM: Pituitary adenylate-cyclase activating peptide (PACAP) is a more potent proliferative agent than gastrin for rat enterochromaffin-like (ECL) cell proliferation in vitro. The role of this neurotransmitter during gastrin-mediated ECL cell tumor formation and gastrin-autonomous ECL cell neoplasia is unknown. METHODS AND RESULTS: ECL cell transformation was induced in the Mastomys using 16 wk H2 receptor blockade of acid inhibition. Examination of the epithelial fundic mucosa demonstrated that PACAP-immunoreactivity significantly increased in the tumor mucosa compared to the naïve stomach, and was associated with ECL cells. Naïve and tumor ECL cells were then purified (approximately 95%) from Mastomys and the presence of all three PACAP/VPAC receptor subtypes was demonstrated by polymerase chain-reaction amplification. Thereafter, cells were maintained in short-term (48 h) primary cultures. PACAP significantly (p<0.05) increased 24 h bromo-deoxyuridine uptake (approximately 4-fold) in both cell types with estimated EC(50) values of approximately 4x10(-16) M and approximately 2x10(-16) M, respectively. Specific receptor antagonists (PAC1/VPAC1) of PACAP competitively inhibited these proliferative effects in naïve cells. Oligonucleotide antisense directed against PAC1 significantly inhibited PACAP-stimulated DNA synthesis by approximately 85% (p<0.05) in tumor cells. CONCLUSION: PACAP is a potent and effective modulator of ECL cell proliferation. The expression of this neuropeptide and its receptors, particularly PAC1, suggest the existence of a neural regulatory pathway of ECL cell proliferation and transformation.

Animals↗
PubMed2001

Van Swieten and the renaissance of the Vienna Medical School.

The period until 1745 found the Viennese medical system languishing far behind advances made in other major European centers. This chaotic situation was reversed by the foresight and breadth of vision of the Empress Maria Theresa, who initiated considerable reform in Austria by actively recruiting the best minds of the time to reduce the intellectual and technologic differences. Her ability to entice one of Boerhaave's most eminent pupils, Gerard van Swieten, to leave Leiden for Vienna, particularly benefited the Vienna Medical School. In 1745 van Swieten assumed responsibility for reconfiguration of the patronage and nepotism-ridden medical system of the Austro-Hungarian Empire. As a first task, he swiftly expunged the influence of the Jesuits and other religious orders from medicine and established formal training and examinations, transforming the medical discipline into a meritocracy. Excelling as a physician and an innovative teacher, he also established a close personal relationship with the Empress and became her medical confidante. To a large part, the success of this first great Viennese medical school was owed to de Haen, who left Leiden to implement Boerhaave's method of clinical teaching. As a result of these innovations and with considerable support from the Empress, the University of Vienna, particularly its medical school, within a few decades achieved recognition throughout Europe as a seat of learning and scholarship. Van Swieten would not be remembered today if his contribution had been only scholarly or scientific achievements. He propelled Austrian medicine to a level commensurate with that of other European states of the day by 27 years of dedicated and industrious service.

Austria↗
PubMed2001

Ernest Starling and the discovery of secretin.

The demonstration by Bayliss and Starling that acid liberates a chemical messenger from the cells of the duodenal and jejunal mucosa and that this, by traveling through the blood, excites the pancreas to secrete revolutionized physiology. It subsequently provided the impetus to establish endocrinology as a specialist field in medicine. Together, their contributions to physiology covered a vast sphere of knowledge, ranging from hormones to the heart and from enzymes to osmotic forces. Every subject that they studied was augmented by their efforts, and their lucid scientific writing brought both clarity and organization to the field of physiological endeavor throughout the world. Both contributed in a very definite way to crystallizing physiology into a rigorous scientific discipline and their respective texts the "Principles of General Physiology" (Bayliss) and the "Principles of Human Physiology" (Starling) established a framework of thought that for decades remained the lodestar of physiological science. As mentors, they devoted themselves to aspirant physiologists from all parts of the world, and their dedication to the activities of the Physiological Society in London was legendary. Indeed from 1896, when Starling became secretary, until the death of Bayliss in 1924, the two ran this august body in one capacity or another for more than a quarter of a century. There is little doubt that the felicitous collaboration that led to the discovery of secretin and the introduction of the concept of chemical messengers represents an advance that not only revolutionized physiological thought but the entire face of clinical medicine.

England↗
PubMed2001

Cyclin D1 antisense oligonucleotide inhibits cell growth stimulated by epidermal growth factor and induces apoptosis of gastric cancer cells.

The cyclin D1 protein is one of the cell cycle regulators required for cell cycle progression through G1 phase to S phase. The cyclin D1-cyclin-dependent kinase (CDK) system is thought to control the cell cycle through mediating extracellular signals from mitogens, such as epidermal growth factor (EGF). In this study, we attempted to examine the therapeutic effect of cyclin D1 antisense oligonucleotides (AS/D1) on cell proliferation and apoptosis of the gastric cancer cell line MKN-74, in the presence and absence of EGF-stimulation. Evaluation of cell survival and DNA synthesis revealed that enhanced cell growth following EGF-stimulation was completely inhibited by a 24 h pre-incubation with 100 nM AD/D1. This inhibition was down to 19.3% compared with maximal DNA synthesis after stimulation with 3 nM EGF alone. Western blotting demonstrated that while EGF-stimulation led to cyclin D1 over-expression, AS/D1 inhibited cyclin D1 protein expression. We also demonstrated the induction of apoptosis in MKN-74 cells by AS/D1. In conclusion, EGF-stimulated MKN-74 cell proliferation was inhibited by AS/D1, which could overcome EGF-induced cyclin D1 over-expression. AS/D1 also affected cell survival by inducing apoptosis through cell cycle arrest following cyclin D1 depletion. Thus, AS/D1 may be a candidate for use as a novel cancer therapy specifically targeted against the over-expression of cyclin D1 enhanced by EGF in malignant cells.

Apoptosis↗
PubMed2000

Intravenous pantoprazole rapidly controls gastric acid hypersecretion in patients with Zollinger-Ellison syndrome.

BACKGROUND & AIMS: Parenteral control of gastric acid hypersecretion in conditions such as Zollinger-Ellison syndrome (ZES) or idiopathic gastric acid hypersecretion is necessary perioperatively or when oral medications cannot be taken for other reasons (e.g., during chemotherapy, acute upper gastrointestinal bleeding, or in intensive care unit settings). METHODS: We evaluated the efficacy and safety of 15-minute infusions of the proton pump inhibitor pantoprazole (80-120 mg every 8-12 hours) in controlling acid output for up to 7 days. Effective control was defined as acid output >10 milliequivalents per hour (mEq/h) (<5 mEq/h in patients with prior acid-reducing surgery) for 24 hours. RESULTS: The 21 patients enrolled had a mean age of 51.9 years (range, 29-75) and a mean disease duration of 8.1 years (range, <0.5-21); 13 were male, 7 had multiple endocrine neoplasia syndrome type I, 4 had undergone acid-reducing surgery, 2 had received chemotherapy, and 13 had undergone gastrinoma resections without cure. Basal acid output (mean +/- SD) was 40.2 +/- 27.9 mEq/h (range, 11.2-117.9). In all patients, acid output was controlled within the first hour (mean onset of effective control, 41 minutes) after an initial 80-mg intravenous pantoprazole dose. Pantoprazole, 80 mg every 12 hours, was effective in 17 of 21 patients (81%) for up to 7 days. Four patients required upward dose titration, 2 required 120 mg pantoprazole every 12 hours, and 2 required 80 mg every 8 hours. At study end, acid output remained controlled for 6 hours beyond the next expected dose in 71% of patients (n = 15); mean acid output increased to 4.0 mEq/h (range, 0-9.7). No serious or unexpected adverse events were observed. CONCLUSIONS: Intravenous pantoprazole, 160-240 mg/day administered in divided doses by 15-minute infusion, rapidly and effectively controlled acid output within 1 hour and maintained control for up to 7 days in all ZES patients.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2000

Helicobacter pylori alters gastric epithelial cell cycle events and gastrin secretion in Mongolian gerbils.

BACKGROUND & AIMS: Human colonization with Helicobacter pylori increases the risk for distal gastric adenocarcinoma, possibly by altering gastric epithelial cell cycle events and/or gastrin secretion. This study aimed to determine whether H. pylori virulence-related characteristics affect apoptosis, proliferation, and gastrin levels in a rodent model of gastric adenocarcinoma. METHODS: Mongolian gerbils were challenged with H. pylori wild-type or isogenic cagA(-) and vacA(-) mutants, and apoptotic and proliferating cells were identified by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling and proliferating cell nuclear antigen immunohistochemistry, respectively. Serum gastrin levels were determined by radioimmunoassay. RESULTS: Gastric epithelial cell turnover was no different after infection with the wild-type, cagA(-), or vacA(-) strains. H. pylori infection significantly increased antral apoptosis 2-4 weeks after challenge, before apoptotic indices decreased to baseline. In contrast, antral proliferation rates were significantly higher 16-20 weeks after inoculation, but then decreased by 40 weeks. Antral proliferation was significantly related to serum gastrin levels, whereas antral apoptosis was inversely related to acute inflammation and lymphoid follicles. CONCLUSIONS: In H. pylori-infected gerbils, enhanced antral apoptosis is an early and transient cell cycle event. Epithelial cell proliferation peaks later and is significantly related to increased gastrin levels, suggesting that epithelial cell growth in H. pylori-colonized mucosa may be mediated by gastrin-dependent mechanisms.

Animals↗