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1.
Behav Processes ; 169: 103990, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31678324

ABSTRACT

The problem solving capabilities of dolphins are suggested to be indicative of advanced cognition. When confronted with a novel problem, dolphins can plan their behavior to create a more efficient strategy than that which was previously modeled. The present study investigated dolphins' ability to plan their behaviors using an interactive apparatus with accompanying weights. Two problems were presented to evaluate dolphins' ability to plan by collecting several weights at once, thus solving the apparatus more efficiently. In contrast to previous findings, dolphins in the present study failed to plan their behavior. Rather, individual differences in problem solving strategies arose throughout the study and are described here. Dolphins engaged in several strategies in order to attempt to obtain the fish reward, including approaches that were not modeled. Strategies for solving the submerged interactive apparatus (SIA) included emulation, freeloading, water flow manipulation, and physical manipulation of the SIA. The SIA was continually solved by a single individual who rarely consumed the food reward, suggesting that she may have been motivated to participate for the challenge itself. Though not indicative of planning, the results of the present study demonstrate the plasticity of dolphin problem solving capabilities and spatial reasoning.


Subject(s)
Bottle-Nosed Dolphin/physiology , Problem Solving/physiology , Animals , Cognition/physiology , Female , Male , Reward
2.
Eur Psychiatry ; 41S: S681, 2017 Apr.
Article in English | MEDLINE | ID: mdl-28859824

ABSTRACT

This article has been removed: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been removed at the request of the authors due to errors in the author list.

3.
Int J Obes Suppl ; 6(Suppl 1): S22-S27, 2016 Dec.
Article in English | MEDLINE | ID: mdl-28685026

ABSTRACT

The gastrointestinal (GI) tract has a central role in nutritional homeostasis, as location for food ingestion, digestion and absorption, with the gut endocrine system responding to and regulating these events, as well as influencing appetite. One key GI hormone with the full spectrum of these activities is cholecystokinin (CCK), a peptide released from neuroendocrine I cells scattered through the proximal intestine in response to fat and protein, with effects to stimulate gall bladder contraction and pancreatic exocrine secretion, to regulate gastric emptying and intestinal transit, and to induce satiety. There has been interest in targeting the type 1 CCK receptor (CCK1R) for drug development to provide non-caloric satiation as an aid to dieting and weight loss; however, there have been concerns about CCK1R agonists related to side effects and potential trophic impact on the pancreas. A positive allosteric modulator (PAM) of CCK action at this receptor without intrinsic agonist activity could provide a safer and more effective approach to long-term administration. In addition, CCK1R stimulus-activity coupling has been shown to be negatively affected by excess membrane cholesterol, a condition described in the metabolic syndrome, thereby potentially interfering with an important servomechanism regulating appetite. A PAM targeting this receptor could also potentially correct the negative impact of cholesterol on CCK1R function. We will review the molecular basis for binding natural peptide agonist, binding and action of small molecules within the allosteric pocket, and the impact of cholesterol. Novel strategies for taking advantage of this receptor for the prevention and management of obesity will be reviewed.

4.
Br J Pharmacol ; 171(5): 1085-101, 2014 Mar.
Article in English | MEDLINE | ID: mdl-23889342

ABSTRACT

Class B guanine nucleotide-binding protein GPCRs share heptahelical topology and signalling via coupling with heterotrimeric G proteins typical of the entire superfamily of GPCRs. However, they also exhibit substantial structural differences from the more extensively studied class A GPCRs. Even their helical bundle region, most conserved across the superfamily, is predicted to differ from that of class A GPCRs. Much is now known about the conserved structure of the amino-terminal domain of class B GPCRs, coming from isolated NMR and crystal structures, but the orientation of that domain relative to the helical bundle is unknown, and even less is understood about the conformations of the juxtamembranous amino-terminal tail or of the extracellular loops linking the transmembrane segments. We now review what is known about the structure and function of these regions of class B GPCRs. This comes from indirect analysis of structure-function relationships elucidated by mutagenesis and/or ligand modification and from the more direct analysis of spatial approximation coming from photoaffinity labelling and cysteine trapping studies. Also reviewed are the limited studies of structure of some of these regions. No dominant theme was recognized for the structures or functional roles of distinct regions of these juxtamembranous portions of the class B GPCRs. Therefore, it is likely that a variety of molecular strategies can be engaged for docking of agonist ligands and for initiation of conformational changes in these receptors that would be expected to converge to a common molecular mechanism for activation of intracellular signalling cascades.


Subject(s)
Receptors, G-Protein-Coupled/chemistry , Amino Acid Sequence , Humans , Ligands , Molecular Sequence Data , Protein Conformation , Receptors, G-Protein-Coupled/metabolism
5.
Int J Obes Suppl ; 4(Suppl 1): S9-S13, 2014 Jul.
Article in English | MEDLINE | ID: mdl-27152167

ABSTRACT

Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone secreted from L cells in the distal small intestine and proximal colon after a meal that acts as an incretin to augment the insulin response, while also inhibiting glucagon and slowing gastric emptying. These characteristics of GLP-1, as well as its ability to reduce islet beta cell apoptosis and expand beta cell mass and its cardioprotective and neuroprotective effects, provide a broad spectrum of actions potentially useful for the management of type-2 diabetes mellitus. GLP-1 also has the added advantage of having its incretin effects dependent on the level of serum glucose, only acting in the presence of hyperglycaemia, and thereby preventing hypoglycemic responses. Although natural GLP-1 has a very short half-life, limiting its therapeutic usefulness, a variety of analogues and formulations have been developed to provide extended actions and to limit side effects. However, all of these peptides require parenteral administration. Potentially orally active small-molecule agonists acting at the GLP-1 receptor are also being developed, but have not yet been approved for clinical use. Recent insights into the molecular nature of the class B G-protein-coupled GLP-1 receptor has provided insights into the modes of binding these types of ligands, as well as providing opportunities for rational enhancement. The advantages and disadvantages of each of these agents and their possible clinical utility will be explored.

6.
Br J Pharmacol ; 168(3): 644-57, 2013 Feb.
Article in English | MEDLINE | ID: mdl-22946511

ABSTRACT

BACKGROUND AND PURPOSE: Alternative splicing expands proteome diversity to GPCRs. Distinct receptor variants have been identified for a secretin family GPCR, the calcitonin receptor (CTR). The possible functional contributions of these receptor variants are further altered by their potential interactions with receptor activity-modifying proteins (RAMPs). One variant of the human CTR lacks the first 47 residues at its N terminus [Δ(1-47)hCT((a)) ]. However, very little is known about the pharmacology of this variant or its ability to interact with RAMPs to form amylin receptors. EXPERIMENTAL APPROACH: Δ(1-47)hCT((a)) was characterized both with and without RAMPs in Cos7 and/or HEK293S cells. The receptor expression (ELISA assays) and function (cAMP and pERK1/2 assays) for up to six agonists and two antagonists were determined. KEY RESULTS: Despite lacking 47 residues at the N terminus, Δ(1-47)hCT((a)) was still able to express at the cell surface, but displayed a generalized reduction in peptide potency. Δ(1-47)hCT((a)) retained its ability to interact with RAMP1 and formed a functional amylin receptor; this also appeared to be the case with RAMP3. On the other hand, its interaction with RAMP2 and resultant amylin receptor was reduced to a greater extent. CONCLUSIONS AND IMPLICATIONS: Δ(1-47)hCT((a)) acts as a functional receptor at the cell surface. It exhibits altered receptor function, depending on whether it associates with a RAMP and which RAMP it interacts with. Therefore, the presence of this variant in tissues will potentially contribute to altered peptide binding and signalling, depending on the RAMP distribution in tissues.


Subject(s)
Receptor Activity-Modifying Proteins/metabolism , Receptors, Calcitonin/genetics , Receptors, Calcitonin/metabolism , Animals , COS Cells , Chlorocebus aethiops , Cyclic AMP/metabolism , HEK293 Cells , Humans , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/metabolism , Peptides/pharmacology , Protein Isoforms , Receptor Activity-Modifying Proteins/genetics , Receptors, Calcitonin/agonists , Receptors, Calcitonin/antagonists & inhibitors , STAT5 Transcription Factor
7.
Zoo Biol ; 32(1): 45-53, 2013.
Article in English | MEDLINE | ID: mdl-22622768

ABSTRACT

Dolphin shows and dolphin interaction programs are two types of education programs within zoological institutions used to educate visitors about dolphins and the marine environment. The current study examined the short- and long-term effects of these programs on visitors' conservation-related knowledge, attitude, and behavior. Participants of both dolphin shows and interaction programs demonstrated a significant short-term increase in knowledge, attitudes, and behavioral intentions. Three months following the experience, participants of both dolphin shows and interaction programs retained the knowledge learned during their experience and reported engaging in more conservation-related behaviors. Additionally, the number of dolphin shows attended in the past was a significant predictor of recent conservation-related behavior suggesting that repetition of these types of experiences may be important in inspiring people to conservation action. These results suggest that both dolphin shows and dolphin interaction programs can be an important part of a conservation education program for visitors of zoological facilities.


Subject(s)
Animals, Zoo , Behavior, Animal/physiology , Conservation of Natural Resources/statistics & numerical data , Dolphins/physiology , Zoology/education , Adult , Animals , Attitude , Humans , Regression Analysis , Surveys and Questionnaires , United States
8.
Neurology ; 78(22): 1714-20, 2012 May 29.
Article in English | MEDLINE | ID: mdl-22459677

ABSTRACT

OBJECTIVE: To identify the gene responsible for 14q32-linked dominant spinal muscular atrophy with lower extremity predominance (SMA-LED, OMIM 158600). METHODS: Target exon capture and next generation sequencing was used to analyze the 73 genes in the 14q32 linkage interval in 3 SMA-LED family members. Candidate gene sequencing in additional dominant SMA families used PCR and pooled target capture methods. Patient fibroblasts were biochemically analyzed. RESULTS: Regional exome sequencing of all candidate genes in the 14q32 interval in the original SMA-LED family identified only one missense mutation that segregated with disease state-a mutation in the tail domain of DYNC1H1 (I584L). Sequencing of DYNC1H1 in 32 additional probands with lower extremity predominant SMA found 2 additional heterozygous tail domain mutations (K671E and Y970C), confirming that multiple different mutations in the same domain can cause a similar phenotype. Biochemical analysis of dynein purified from patient-derived fibroblasts demonstrated that the I584L mutation dominantly disrupted dynein complex stability and function. CONCLUSIONS: We demonstrate that mutations in the tail domain of the heavy chain of cytoplasmic dynein (DYNC1H1) cause spinal muscular atrophy and provide experimental evidence that a human DYNC1H1 mutation disrupts dynein complex assembly and function. DYNC1H1 mutations were recently found in a family with Charcot-Marie-Tooth disease (type 2O) and in a child with mental retardation. Both of these phenotypes show partial overlap with the spinal muscular atrophy patients described here, indicating that dynein dysfunction is associated with a range of phenotypes in humans involving neuronal development and maintenance.


Subject(s)
Chromosomes, Human, Pair 14 , Cytoplasmic Dyneins/genetics , Genes, Dominant , Lower Extremity , Mutation, Missense , Polymorphism, Single Nucleotide , Spinal Muscular Atrophies of Childhood/genetics , Child, Preschool , Chromosomes, Human, Pair 14/genetics , Cytoplasmic Dyneins/metabolism , Female , Genes, Dominant/genetics , Humans , Infant , Male , Sequence Analysis, DNA/methods
9.
Acta Myol ; 30(2): 109-16, 2011 Oct.
Article in English | MEDLINE | ID: mdl-22106713

ABSTRACT

BACKGROUND: Charcot Marie Tooth disease (CMT) affects one in 2500 people. Genetic testing is often pursued for family planning purposes, natural history studies and for entry into clinical trials. However, identifying the genetic cause of CMT can be expensive and confusing to patients and physicians due to locus heterogeneity. METHODS: We analyzed data from more than 1000 of our patients to identify distinguishing features in various subtypes of CMT. Data from clinical phenotypes, neurophysiology, family history, and prevalence was combined to create algorithms that can be used to direct genetic testing for patients with CMT. FINDINGS: The largest group of patients in our clinic have slow motor nerve conduction velocities (MNCV) in the upper extremities. Approximately 88% of patients in this group have CMT1A. Those who had intermediate MNCV had primarily CMT1X (52.8%) or CMT1B (27.8%). Patients with very slow MNCV and delayed walking were very likely to have CMT1A (68%) or CMT1B (32%). No patients with CMT1B and very slow MNCV walked before 15 months of age. Patients with CMT2A form our largest group of patients with axonal forms of CMT. INTERPRETATION: Combining features of the phenotypic and physiology groups allowed us to identify patients who were highly likely to have specific subtypes of CMT. Based on these results, we created a series of algorithms to guide testing. A more detailed review of this data is published in Annals of Neurology (1).


Subject(s)
Case Management/organization & administration , Charcot-Marie-Tooth Disease/diagnosis , Charcot-Marie-Tooth Disease/genetics , Genetic Testing/methods , Neural Conduction , Upper Extremity , Age of Onset , Algorithms , Charcot-Marie-Tooth Disease/epidemiology , Charcot-Marie-Tooth Disease/physiopathology , Electrodiagnosis , Genetic Testing/standards , Genetic Testing/statistics & numerical data , Humans , Inheritance Patterns , Motor Neurons/pathology , Patient Selection , Pedigree , Practice Guidelines as Topic/standards , Prevalence , Severity of Illness Index , Upper Extremity/innervation , Upper Extremity/physiopathology
10.
Zoo Biol ; 30(4): 365-70, 2011.
Article in English | MEDLINE | ID: mdl-20872877

ABSTRACT

Stereotypic behavior is observed in many species within zoological institutions. Attempts to reduce such behavior typically involve some form of environmental enrichment that provides opportunities for species appropriate behavior or some degree of control within the environment. However, environmental enrichment has never been completely successful in eliminating stereotypic behavior for an entire group of animals within a zoological facility. In the wild, stereotypic behavior is rarely observed. Documenting the occurrence of stereotypic behavior in the wild, and circumstances in which it occurs, could help provide insight into the causes of such behavior within zoological institutions. The following commentary details the observations of wild lemon sharks (Negaprion brevirostris) engaging in a stereotyped swimming pattern behind a research vessel north of Grand Bahama Island, Bahamas. We consider a possible explanation for the sharks' behavior and hope to stimulate conversation as well as increase examination of animal management routines in zoological facilities.


Subject(s)
Behavior, Animal/physiology , Sharks/physiology , Stereotyped Behavior/physiology , Animals , Swimming
11.
Zoo Biol ; 29(1): 68-79, 2010.
Article in English | MEDLINE | ID: mdl-19382165

ABSTRACT

With the growing trend in zoos to build complex, naturalistic exhibits comes the potential for exhibits to be so densely vegetated or complex that animals are not easily seen by zoo visitors. This can negatively impact the visitor's visiting experience and the zoo's ability to communicate conservation and education messages. Over the past 9 years, Disney's Animal Kingdom has developed a process for monitoring and improving the visibility of animals on display to the public. This animal visibility process utilizes a data collection system whereby systematic observations are collected each week. The percentage of observations where at least one animal was visible is recorded for each species and compared to an 80% visibility criterion. Species that do not reach this criterion for 4 consecutive weeks are discussed at animal management meetings. If the problems associated with animal visibility cannot be easily solved, the animal-care teams partner with the research team to conduct a second process, called the Visibility Issues Process. This process provides additional information for the animal-care team to utilize in developing a plan to improve visibility. Although the processes described here are specific to the infrastructure at Disney's Animal Kingdom, the basic concepts of (1) a formalized visibility data collection process, (2) a visibility criterion to which managers of species are held accountable, and (3) a process for planning to improve animal visibility without negatively impacting animal welfare are fundamental concepts that can be developed at individual institutions and incorporated into that zoo's existing infrastructure.


Subject(s)
Animal Welfare , Animals, Zoo , Housing, Animal , Animals , Time Factors
12.
Biochem Soc Trans ; 35(Pt 4): 709-12, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17635130

ABSTRACT

The secretin receptor is prototypic of Class II GPCRs (G-protein-coupled receptors), based on its structural and functional characteristics and those of its natural agonist ligand. Secretin represents a linear 27-residue peptide with diffuse pharmacophoric domain. The secretin receptor includes the typical signature sequences for this receptor family within its predicted transmembrane segments and the highly conserved six cysteine residues contributing to three intradomain disulfide bonds within its long N-terminus. This domain is critical for secretin binding based on receptor mutagenesis and photoaffinity labelling studies. Full agonist analogues of secretin incorporating a photolabile moiety at various positions throughout the pharmacophore covalently label residues within this region, while only N-terminal probes have labelled the core helical bundle domain. Combining insights coming from receptor structural studies, peptide structure-activity relationship considerations, photoaffinity labelling, and application of fluorescence techniques has resulted in the development of a working model of the secretin-receptor complex. This supports the initial docking of the peptide agonist within a cleft in the receptor N-terminus, providing the opportunity for an endogenous sequence within that domain to interact with the core of the receptor. This interaction is believed to be key in the molecular basis of conformational change associated with activation of this receptor. The site of action of this endogenous agonist could also provide a possible target for small molecule agonists to act.


Subject(s)
Receptors, G-Protein-Coupled/chemistry , Receptors, G-Protein-Coupled/metabolism , Receptors, Gastrointestinal Hormone/chemistry , Receptors, Gastrointestinal Hormone/metabolism , Secretin/chemistry , Secretin/physiology , Amino Acid Sequence , Animals , Humans , Ligands , Molecular Sequence Data , Protein Binding/physiology , Receptors, G-Protein-Coupled/genetics , Receptors, Gastrointestinal Hormone/genetics
13.
Percept Mot Skills ; 94(3 Pt 1): 921-6, 2002 Jun.
Article in English | MEDLINE | ID: mdl-12081298

ABSTRACT

The purpose of this study was to examine the predictive validity of the Miller Assessment for Preschoolers in a sample of children in Israel. 30 children (M age 7 yr., 8 mo.) were selected from a group of typical children registered in 4 Mother and Child Health Care Centers in central Israel; they were originally tested as preschoolers (M age 3 yr., 10 mo.) on this procedure. They were retested after an interval of 5 to 7 yr. on academically related tests. Correlations between the Total scores and most of the follow-up test scores indicate significant correspondence (.41-.70). Regression analysis indicated that visuomotor integration and handwriting accounted for 58% of the variance. These results contribute to the empirical evidence regarding the predictive abilities of this procedure and indicate its validity cross-culturally over an extended follow-up interval of 5 to 7 yr.


Subject(s)
Aptitude Tests/statistics & numerical data , Learning Disabilities/diagnosis , Mass Screening/statistics & numerical data , Child , Child, Preschool , Female , Follow-Up Studies , Humans , Israel , Learning Disabilities/prevention & control , Learning Disabilities/psychology , Male , Psychometrics , Reproducibility of Results , Risk Assessment/statistics & numerical data
14.
J Biol Chem ; 276(51): 48040-7, 2001 Dec 21.
Article in English | MEDLINE | ID: mdl-11673456

ABSTRACT

Dimerization of some G protein-coupled receptors has recently been demonstrated, but how widespread this phenomenon might be and its functional implications are not yet clear. We have utilized biophysical and biochemical techniques to evaluate whether the type A cholecystokinin (CCK) receptor can form oligomeric complexes in the plasma membrane and the impact of ligand binding and signaling on such complexes. We investigated the possibility of bioluminescence resonance energy transfer (BRET) between receptor constructs that included carboxyl-terminal tags of Renilla luciferase or yellow fluorescent protein. Indeed, co-expression of these constructs in COS cells resulted in the constitutive presence of a significant BRET signal above that in a series of controls, with this signal reduced by co-expression of competing non-tagged CCK receptors. The presence of an oligomeric complex of CCK receptor molecules was confirmed in co-immunoprecipitation experiments. Occupation of CCK receptors with agonist ligands (CCK or gastrin-4) resulted in the rapid reduction in BRET signal in contrast to the enhancement of such a signal reported after agonist occupation of the beta(2)-adrenergic receptor. These effects on CCK receptor oligomerization were concentration-dependent, correlating with the potencies of the agonists. A smaller effect was observed for a partial agonist, and no effect was observed for antagonist occupation of this receptor. Agonist-induced reduction in BRET signal was also observed for pairs of CCK receptors with a donor-acceptor pair situated in other positions within the receptor. Manipulation of the phosphorylation state of CCK receptor using protein kinase C activation with phorbol ester or inhibition with staurosporine had no effect on the basal level or agonist effect on CCK receptor oligomerization. This provides the first evidence for CCK receptor oligomerization in living cells, with insights that the active conformation of this receptor dissociates these complexes in a phosphorylation-independent manner.


Subject(s)
GTP-Binding Proteins/metabolism , Receptors, Cholecystokinin/metabolism , Animals , Base Sequence , Biopolymers , Cell Line , DNA Primers , Energy Transfer , Luminescent Measurements , Rats , Receptors, Cholecystokinin/agonists
15.
Acta Astronaut ; 49(3-10): 477-82, 2001.
Article in English | MEDLINE | ID: mdl-11669134

ABSTRACT

The selection, definition, and development phases of a Life Sciences flight research experiment has been consistent throughout the past decade. The implementation process, however, has changed significantly within the past two years. This change is driven primarily by the shift from highly integrated, dedicated research missions on platforms with well defined processes to self contained experiments with stand alone operations on platforms which are being concurrently designed. For experiments manifested on the International Space Station (ISS) and/or on short duration missions, the more modular, streamlined, and independent the individual experiment is, the more likely it is to be successfully implemented before the ISS assembly is completed. During the assembly phase of the ISS, science operations are lower in priority than the construction of the station. After the station has been completed, it is expected that more resources will be available to perform research. The complexity of implementing investigations increases with the logistics needed to perform the experiment. Examples of logistics issues include- hardware unique to the experiment; large up and down mass and volume needs; access to crew and hardware during the ascent or descent phases; maintenance of hardware and supplies with a limited shelf life,- baseline data collection schedules with lengthy sessions or sessions close to the launch or landing; onboard stowage availability, particularly cold stowage; and extensive training where highly proficient skills must be maintained. As the ISS processes become better defined, experiment implementation will meet new challenges due to distributed management, on-orbit resource sharing, and adjustments to crew availability pre- and post-increment.


Subject(s)
Biological Science Disciplines/organization & administration , Research , Space Flight/organization & administration , Humans , International Agencies/organization & administration , Spacecraft , United States , United States National Aeronautics and Space Administration , Weightlessness
16.
Am J Physiol Endocrinol Metab ; 281(5): E938-45, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11595649

ABSTRACT

Molecular mechanisms for the regulation of islet amyloid polypeptide (IAPP) gene expression remain unclear. In the present study, we investigated the effects of glucose and forskolin on IAPP gene regulation in the INS-1 islet beta-cell line. Both glucose and forskolin increased the level of expression of this gene, as measured by Northern blot analysis, and increased IAPP gene transcription in a time- and concentration-dependent manner, as demonstrated in a reporter gene assay. Although inhibition of protein kinase A activity with H-89 eliminated the effect of forskolin on this gene, the glucose effect was unaffected. This supported the predominant use of a protein kinase A-independent signaling pathway for glucose regulation of the IAPP gene. Electrophoretic mobility shift assay further indicated that glucose and forskolin regulated expression of this gene by targeting different elements of the promoter. Mutation of the cAMP regulatory element flanking the IAPP coding region resulted in the loss of most of the forskolin-stimulated IAPP gene promoter activity, whereas glucose-enhanced IAPP gene transcription was unaffected. These results demonstrate parallel and distinct regulatory pathways involved in glucose- and forskolin-induced IAPP gene expression in this model beta-cell system.


Subject(s)
Amyloid/genetics , Colforsin/pharmacology , Gene Expression Regulation/drug effects , Glucose/pharmacology , Signal Transduction , Sulfonamides , Adenylyl Cyclase Inhibitors , Blotting, Northern , Carcinoma, Pancreatic Ductal , Cyclic AMP-Dependent Protein Kinases/antagonists & inhibitors , Enzyme Activation/drug effects , Enzyme Inhibitors/pharmacology , Humans , Islet Amyloid Polypeptide , Isoquinolines/pharmacology , Pancreatic Neoplasms , RNA, Messenger/analysis , Reverse Transcriptase Polymerase Chain Reaction , Tetradecanoylphorbol Acetate/pharmacology , Tumor Cells, Cultured
17.
J Biol Chem ; 276(47): 44146-56, 2001 Nov 23.
Article in English | MEDLINE | ID: mdl-11553617

ABSTRACT

In the present work we examined localization and behavior of G protein-coupled receptors (GPCR) in polarized exocrine cells to address the questions of how luminal to basal Ca(2+) waves can be generated in a receptor-specific manner and whether quantal Ca(2+) release reflects partial release from a continuous pool or an all-or-none release from a compartmentalized pool. Immunolocalization revealed that expression of GPCRs in polarized cells is not uniform, with high levels of GPCR expression at or near the tight junctions. Measurement of phospholipase Cbeta activity and receptor-dependent recruitment and trapping of the box domain of RGS4 in GPCRs complexes indicated autonomous functioning of G(q)-coupled receptors in acinar cells. These findings explain the generation of receptor-specific Ca(2+) waves and why the waves are always initiated at the apical pole. The initiation site of Ca(2+) wave at the apical pole and the pattern of wave propagation were independent of inositol 1,4,5-trisphosphate concentration. Furthermore, a second Ca(2+) wave with the same initiation site and pattern was launched by inhibition of sarco/endoplasmic reticulum Ca(2+)-ATPase pumps of cells continuously stimulated with sub-maximal agonist concentration. By contrast, rapid sequential application of sub-maximal and maximal agonist concentrations to the same cell triggered Ca(2+) waves with different initiation sites. These findings indicate that signaling specificity in pancreatic acinar cells is aided by polarized expression and autonomous functioning of GPCRs and that quantal Ca(2+) release is not due to a partial Ca(2+) release from a continuous pool, but rather, it is due to an all-or-none Ca(2+) release from a compartmentalized Ca(2+) pool.


Subject(s)
GTP-Binding Proteins/metabolism , Pancreas/metabolism , Receptors, Cell Surface/metabolism , Animals , Cell Polarity , Pancreas/cytology , Rats
18.
Infect Immun ; 69(9): 5857-63, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11500464

ABSTRACT

Modifications of mucosal phospholipids have been detected in samples from patients with Helicobacter pylori-positive gastritis. These alterations appear secondary to increased phospholipase A2 activity (PLA2). The cytosolic form of this enzyme (cPLA2), normally involved in cellular signaling and growth, has been implicated in cancer pathogenesis. The aim of this study was to investigate cPLA2 expression and PLA2 activity in the gastric mucosae of patients with and without H. pylori infection. In gastric biopsies from 10 H. pylori-positive patients, cPLA2 levels, levels of mRNA as determined by reverse transcriptase PCR, levels of protein as determined by immunohistochemistry, and total PLA2 activity were higher than in 10 H. pylori-negative gastritis patients. To clarify whether H. pylori had a direct effect on the cellular expression of cPLA2, we studied cPLA2 expression in vitro with different human epithelial cell lines, one from a patient with larynx carcinoma (i.e., HEp-2 cells) and two from patients with gastric adenocarcinoma (i.e., AGS and MKN 28 cells), incubated with different H. pylori strains. The levels of cPLA2, mRNA, and protein expression were unchanged in Hep-2 cells independently of cellular adhesion or invasion of the bacteria. Moreover, no change in cPLA2 protein expression was observed in AGS or MKN 28 cells treated with wild-type H. pylori. In conclusion, our study shows increased cPLA2 expression and PLA2 activity in the gastric mucosae of patients with H. pylori infection and no change in epithelial cell lines exposed to H. pylori.


Subject(s)
Gastric Mucosa/enzymology , Gastritis/microbiology , Helicobacter Infections/enzymology , Helicobacter Infections/microbiology , Helicobacter pylori/physiology , Phospholipases A/metabolism , Adult , Aged , Cytosol/enzymology , Epithelial Cells/enzymology , Gastritis/enzymology , Humans , Middle Aged , Phospholipases A2 , Tumor Cells, Cultured
19.
Gastroenterology ; 121(3): 640-5, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11522748

ABSTRACT

BACKGROUND & AIMS: Islet amyloid polypeptide (IAPP) levels are elevated in pancreatic cancer and may be a useful marker of pancreatic cancer-associated diabetes. The aim of this study was to compare the sensitivity and specificity for pancreatic cancer of IAPP with that of CA19-9, examine clinical characteristics of diabetes in pancreatic cancer, and define the relationship of IAPP to diabetes of pancreatic cancer. METHODS: Fasting serum glucose, IAPP, and CA 19-9 were measured in 130 subjects with pancreatic cancer, 250 subjects with other pancreatic and peripancreatic diseases, and 116 controls. In pancreatic cancer patients, we noted tumor stage and the presence and duration of diabetes. RESULTS: IAPP was markedly elevated in pancreatic cancer, especially in patients with diabetes. However, the sensitivity of IAPP for pancreatic cancer was less than that of CA 19-9 (40% vs. 75%; P < 0.001). Diabetes was present in 46% of pancreatic cancers and 55% of resectable tumors. In pancreatic cancer with diabetes, the sensitivity of IAPP was only 50%. In resectable cancer it was 27%. CONCLUSIONS: IAPP is elevated in pancreatic cancer but is not sensitive enough to replace or complement existing tests. Diabetes occurs early and frequently in pancreatic cancer. Development of a sensitive and specific marker for pancreatic-associated diabetes might lead to diagnosis of resectable pancreatic cancer.


Subject(s)
Amyloid/blood , Biomarkers, Tumor/blood , Pancreatic Neoplasms/blood , Pancreatic Neoplasms/diagnosis , Aged , Blood Glucose , CA-19-9 Antigen/blood , Diabetes Mellitus/blood , Diabetes Mellitus/diagnosis , Female , Humans , Islet Amyloid Polypeptide , Male , Predictive Value of Tests , Sensitivity and Specificity
20.
Am J Physiol Gastrointest Liver Physiol ; 281(2): G507-14, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11447031

ABSTRACT

Differences in the molecular structure or organ distribution of receptors can limit the usefulness of a given species for drug studies. In this work, we have studied cholecystokinin (CCK) receptors in cynomolgus monkey, an animal model useful for preclinical testing. The type A CCK receptor cDNA was cloned and predicted to encode a 428 amino acid peptide that was 98% identical to the human receptor. Only 2 of the 10 residues that were distinct from the human receptor were not present in other cloned CCK receptor species. A Chinese hamster ovary cell line that stably expressed this receptor was developed. The cynomolgus receptor expressed in this environment was functionally indistinguishable from the human receptor, binding CCK with high affinity [inhibition constant (K(I)) = 1.8 +/- 0.5 nM] and exhibiting a potent intracellular calcium signaling response to this hormone (EC(50) = 6.6 +/- 2.1 pM). Like the human type A CCK receptor, this receptor was expressed prominently in monkey gallbladder and stomach and was expressed in low levels in brain and pancreas. The type B CCK receptor cDNA was cloned from stomach and brain (450 residue receptor that is 96% identical to the human receptor), where it was highly expressed yet was undetectable in gallbladder or pancreas. This work confirms the relevance of the cynomolgus species for preclinical testing of drugs acting on the type A CCK receptor.


Subject(s)
Macaca fascicularis/genetics , Receptors, Cholecystokinin/biosynthesis , Receptors, Cholecystokinin/genetics , Amino Acid Sequence , Animals , Base Sequence , CHO Cells , Cloning, Molecular , Cricetinae , Humans , Macaca fascicularis/metabolism , Molecular Sequence Data , RNA, Messenger/biosynthesis , Receptor, Cholecystokinin A , Receptor, Cholecystokinin B , Receptors, Cholecystokinin/physiology , Sequence Homology, Amino Acid , Tissue Distribution
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