Gastritis, Helicobacter pylori, and proton pump inhibitors.
Explore the source record for details and available documents.
Gastric Acidity Determination↗
Biomedical subjects
G Sachs
Publications and source records attributed to G Sachs.
The anticonvulsant lamotrigine in treatment-resistant manic-depressive illness.
Anticonvulsants are used extensively in the treatment of bipolar disorder. Treating depression in bipolar disorder can be difficult because of the limited antidepressant effects of the standard mood stabilizers and the tendency of antidepressants to induce mania or decrease cycle length. Lamotrigine is a new anticonvulsant with few side effects that may have mood-stabilizing and elevating effects. Its mechanism of action probably involves the inhibition of excessive release of excitatory amino acids such as glutamate. Antiglutamatergic agents may be antidepressant and mood stabilizing. A case series of 16 patients treated with lamotrigine (dose range 50 mg to 250 mg, mean dose of responders = 141 mg) is presented along with two case reports. All patients were considered treatment-resistant bipolar type I or II. Patients were rated on average 5 weeks after starting lamotrigine using a semistructured follow-up form that included symptom rating, Clinical Global Impressions (CGI), and Global Assessment of Functioning (GAF) scores. Eight of 16 patients were rated as "responders" (CGI < or = 2) and had a mean increase of 16 in their GAF scores. Lamotrigine seems to have antidepressant and mood-stabilizing effects, but this requires confirmation in randomized, controlled trials.
Adult↗
Physiology of isolated gastric endocrine cells.
The regulation of gastric acid secretion is achieved in the periphery by interplay between three major gastric endocrine cells: the enterochromaffin-like (ECL) cell, the gastrin or G cell, and the somatostatin or D cell. Regulation of these cells is via stimulatory or inhibitory paracrine, endocrine, and neural pathways. Upregulation of ECL function is determined by activation of CCK-B receptors, by gastrin, and by activation of beta-adrenergic receptors, as well as by acetylcholine in some (10-29%) of the cells. Gastrin and acetylcholine produce typical biphasic calcium signals. Inhibition of ECL cell histamine release and calcium signaling is produced by somatostatin acting at a type 2 receptor, histamine acting at a histamine-3 receptor, and by peptide PYY. Stimulation of ECL cells results in activation of chloride channels, and there is evidence that voltage-dependent calcium channels, along with the receptor-operated calcium channels, also are responsible for elevation of [Ca]i. Depolarization-activated K+ channels presumably restore the potential after depolarization by activation of the chloride channel. The D cell is activated by either gastrin or CCK and appears to be inhibited by acetylcholine and somatostatin. The G cell is activated by acetylcholine and gastrin-releasing peptide (GRP) and is inhibited by somatostatin. The functional integration of these three cell types is the primary determinant of the degree of stimulation of the parietal cell.
Animals↗
Effect of hypokalemia on the abundance of HK alpha 1 and HK alpha 2 protein in the rat kidney.
An H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) contributes to potassium reabsorption by the collecting ducts of the rat kidney. mRNAs for two isoforms of the H(+)-K(+)-ATPase, HK alpha 1 and HK alpha 2, have been found in the rat kidney. To evaluate whether the HK alpha 1 and HK alpha 2 proteins are present in the rat kidney, microsomes enriched in HK alpha 1 or HK alpha 2 were isolated using the MiniMac magnetic separation system with antibodies directed against either HK alpha 1 (HK 12.18) or HK alpha 2 (AS 31.7). Immunoblots of rat kidney microsomal protein isolated with HK 12.18 revealed a band approximately 94 kDa in size that comigrated with the G1 fraction of the stomach. Immunoblots of rat kidney microsomal protein isolated with AS 31.7 revealed a band slightly greater than 94 kDa that comigrated with a band obtained from rat colonic microsomal protein. To examine the effect of perturbations in potassium metabolism, the abundance of the HK alpha 1 and HK alpha 2 isoforms was compared in rats fed a normal or potassium-deficient diet. A low-potassium diet increased the abundance of HK alpha 2, whereas that of HK alpha 1 was not altered. These data suggest that HK alpha 2 might be the isoform responsible for potassium conservation by the kidney.
Animals↗
Acid secretion and Helicobacter pylori.
Explore the source record for details and available documents.
Animals↗
Localization of mRNA for the muscarinic M1 receptor in rat stomach.
Cholinergic stimulation of receptors in the oxyntic mucosa results in secretion of mucus, pepsinogen and hydrochloric acid. There has been speculation as to the cellular localization of these receptors in the mucosa and as to which subtype is present in the different cell types. In the present study, utilizing radioactive riboprobes for the M1 muscarinic receptor subtype, we carried out in situ hybridization to determine which cells of the gastric corpus transcribe mRNA for this receptor. The antisense M1 probe hybridized strongly on the zymogen cells and, to a lesser extent, on the surface mucous cells and the muscle layers. Control sections from brain also displayed specific hybridization.
Animals↗
Dimerization of the gastric H+, K(+)-ATPase.
When the gastric H+, K(+)-ATPase was solubilized by n-dodecyl beta-D-maltoside and electrophoresed in blue native-polyacrylamide gels (BN-PAGE), one major band at about 360 kDa was observed. Since this band was recognized by both monoclonal antibodies 1218 (anti-alpha) and wheat germ agglutinin (anti-beta), the H+, K(+)-ATPase in its native state exists in a dimeric (alpha beta)2 form. The site of interaction between the heterodimers was determined using Cu(2+)-phenanthroline cross-linking. The Cu(2+)-phenanthroline reagent reacted with the H+, K(2+)-ATPase activity. This cross-linking and enzyme inhibition were prevented by ATP. Cross-linking followed by N-ethylmaleimide blockade of maleimide-reactive SH groups, then reduction and fluorescein 5-maleimide labeling, then reduction and fluorescent tryptic peptide of about 6.5 kDa that had been cross-linked. Since its N-terminal amino acid is Val561, the peptide probably ends at Arg616 or Arg621 and Cys565 and/or Cys615 are probably within the region of closest contact between the two alpha-subunits.
Amino Acid Sequence↗
Cloning and membrane topology of a P type ATPase from Helicobacter pylori.
Southern blot screening of a genomic Helicobacter pylori library was employed to find a P type ATPase using a mixture of 16 DNA oligonucleotides coding for the DKTGT(I/L)T consensus sequence specific for the phosphorylation site of this family of ATPases. A positive clone, pRH439, was isolated and sequenced. The inserted 3.4-kb H. pylori DNA contained an intact open reading frame encoding a protein of 686 amino acids carrying the consensus sites for phosphorylation and ATP binding. The amino acid sequence exhibits a 25-30% identity with bacterial Cd2+ and Cu2+ ATPases. Genomic Southern blot analysis showed that this ATPase was present in all H. pylori strains examined, whereas it was not detectable in Campylobacter jejuni and other bacteria. The membrane topology of this ATPase was investigated using in vitro transcription/translation of fusion vectors to find signal anchor and/or stop transfer sequences. Eight regions of the H. pylori ATPase acted as signal anchor and/or stop transfer sequences and were ordered pairwise along the polypeptide chain placing the N and C-terminal amino acids in the cytoplasm. These transmembrane segments are contained between positions 73 and 92 (H1), 98 and 125 (H2), 128 and 148 (H3), 149 and 176 (H4), 309 and 327 (H5), 337 and 371 (H6), 637 and 658 (H7), and 659 and 685 (H8). The membrane domain of the ATPase, therefore, consists of at least four pairs of transmembrane segments with the phosphorylation site and ATP binding domain located in the large cytoplasmic loop between H6 and H7. The cytoplasmic domain contains several histidines and cysteines, perhaps indicative of divalent cation binding sites. There are several charged amino acids (3 Lys, 2 Glu, 2 Asp), predicted to be in the membrane domain mainly in H2, H3, and H4 and a Cys-Pro-Cys putative metal ion site in H6. The extracytoplasmic domain also has several charged amino acids (5 Glu, 1 Asp, 1 Lys, 1 Arg). It is likely that this novel protein is a heavy metal cation transporting ATPase and belongs to a family of P type ATPases containing eight transmembrane segments.
Adenosine Triphosphatases↗
Relationship between the use of unconventional therapies and disease-related concerns: a study of patients with inflammatory bowel disease.
We studied the use of unconventional therapies of a well-defined population of 105 patients with inflammatory bowel disease (IBD; 72 with Crohn's disease and 33 with ulcerative colitis) who were attending a university out-patient clinic. The following items were used to compare those patients who used unconventional therapies with those who did not. We compared disease-related data, sociodemographic variables, patients' disease-related concerns, and their perceived level of information about IBD. Concerns were measured with the Rating Form of IBD Patient Concerns (RFIPC), inflammatory disease activity was assessed by physicians with the Crohn's disease activity index (CDAI) and the clinical activity index (CAI). Of the 97 (92.4%) patients who answered all questions, 33 (34%) reported using unconventional therapies in addition to conventional therapy. In their level of information about IBD and in their clinical and sociodemographic data, they were not different from the IBD patients who were not using alternative treatments. In their duration of disease, there was a significant difference (p < 0.0002). The longer the disease duration, the more often patients used unconventional therapies. The most important differences between users and nonusers were the following: patients who used unconventional therapies were more concerned about having surgery (p < 0.001), being treated as different (p < 0.04), and feeling out of control (p < 0.05). We conclude that there is a relationship between the use of unconventional therapies and some disease-related concerns, which should be considered in clinical practice. This may help these patients avoid using unproven and expensive alternative therapies.
Adult↗
The effect of environmental pH on the proton motive force of Helicobacter pylori.
BACKGROUND & AIMS: Responses of the proton motive force (the driving force for protons) in Helicobacter pylori to varying medium pH may explain gastric colonization. The aim of this study was to determine the effect of external pH (pHout) on the proton motive force, the sum of the pH gradient, and the potential difference across the bacterial membrane. METHODS: Intracellular pH (pHin) was measured by bis-carboxyethyl-carboxy fluorescein fluorescence and transmembrane potential difference (PD) by fluorescent quenching of 3,3'-dipropyl thiadicarbocyanine iodide at differing pHout and was correlated with survival. RESULTS: PD was -131 +/- 0.36 mV (n = 3), and pHin was about 8.4 at loading pHout 7.0. PD increased as pHout was increased from 4.0 to 8.0, giving a constant proton motive force of about -220 mV. Outside these limits, PD collapsed irreversibly to zero. Addition of 5 mmol/L urea to weak buffer at pH 3.0 or 3.5 prevented irreversible collapse of PD by elevation of pHout caused by NH3 production. Urea addition to weak buffer at pH 7.0 collapsed the PD as urease activity increased the pHout to about 8.4. Survival was also limited to this range of pHout. CONCLUSIONS: H. pylori survives over the range of pHout where it maintains a proton motive force. The effect of urease activity on pHout, while allowing gastric survival in acidic media, may limit survival in nonacidic media.
Ammonium Chloride↗
Selective ligand-induced intracellular calcium changes in a population of rat isolated gastric endocrine cells.
BACKGROUND & AIMS: Peripheral regulation of acid secretion depends mainly on stimulation or inhibition of the three major gastric endocrine cells (enterochromaffin-like, gastrin, and somatostatin). The aim of this paper was to define physiological responses of enterochromaffin-like, gastrin, and somatostatin cells in a mixed endocrine cell population by measuring ligand-selective changes of intracellular calcium ([Ca2+]i) in individual cells. METHODS: Endocrine cells were enriched from a rat gastric cell suspension by elutriation, a density-gradient fractionation, and a 48-hour short-term culture. [Ca2+]i responses of individual cells to various ligands such as gastrin/carboxy-terminal cholecystokinin octapeptide and selective cholecystokinin antagonists, carbachol, and gastrin-releasing peptide were monitored using video imaging in a perfusion chamber. Characteristic [Ca2+]i changes distinguished the three cell types, confirmed by immunostaining. RESULTS: All enterochromaffin-like cells respond to cholecystokinin-B receptor stimulation, but only a few respond to carbachol. Gastrin cells respond to both gastrin-releasing peptide and carbachol but not to cholecystokinin-receptor agonists. Somatostatin cells have both stimulatory cholecystokinin-A and cholecystokinin-B receptors and inhibitory muscarinic receptors. All cells have inhibitory somatostatin receptors. CONCLUSIONS: Calcium-signaling responses of gastric endocrine cells are distinctive. This allows individual cell types in a mixed population to be characterized and permits an analysis of the hormones and transmitters that act directly on a specific cell type.
Animals↗
Corticosteroid-induced mania after single regional application at the celiac plexus.
Explore the source record for details and available documents.
Bipolar Disorder↗
Regional cerebral blood flow changes after light therapy in seasonal affective disorder.
There is considerable evidence to indicate that depressive disorders may be associated with changes in regional cerebral blood flow (rCBF), and that successful treatment may reverse these changes. We studied patients with seasonal affective disorder (SAD) using 99Tcm-hexamethylpropylene amine oxime (99TCm-HMPAO) single photon emission tomography (SPET) to examine the effect of light therapy on rCBF. Ten depressed patients (8 females, 2 males) with a mean (+/- S.D.) age of 33.5 +/- 11.3 years underwent 99TCm-HMPAO SPET studies before and after light therapy. The treatment response was evaluated using the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorders Version (SIGH-SAD). A patient was considered responsive to light therapy if the post-treatment SIGH-SAD score was reduced by 60% or more in comparison to the pre-treatment score (responders, n = 5; non-responders, n = 5). Pre- and post-treatment SIGH-SAD scores and SPET data were compared in each patient. An improvement in depressive symptoms after light therapy was associated with an increase in rCBF in the frontal and cingulate regions as well as the thalamus. Such changes were not seen in non-responsive subjects.
Adult↗
Capacity of Helicobacter pylori to generate ionic gradients at low pH is similar to that of bacteria which grow under strongly acidic conditions.
Helicobacter pylori colonized the highly acidic human gastric mucosa. At pH 3.0 to 7.0, this bacterium maintained a nearly neutral internal pH. Its membrane potential changed reciprocally with the pH gradient so that a relatively constant proton motive force was maintained. Possible, the capacity to maintain an appropriate transmembrane ionic gradient at a low pH contributes to the pathogenic propensities of this bacterium.
Carbonyl Cyanide m-Chlorophenyl Hydrazone↗
Potassium and chloride currents in rat gastric enterochromaffin-like cells.
The gastric enterochromaffin-like (ECL) cell secretes histamine in response to secretagogues (gastrin, acetylcholine) by calcium signaling-dependent exocytosis of intracellular vacuoles containing the hormone. ECL cells were isolated from rat fundic gastric mucosa by elutriation and density-gradient centrifugation. Currents across the plasma membrane were measured using whole cell patchclamp methods. These cells had a low conductance of 0.5 nS and resting potential of -50 mV. Depolarization activated a K+ current that was blocked by Ba2+. Steady-state current in absence of K+ was due to Cl- because of the magnitude of the reversal potential and the effects of Cl- removal. Stimulation of secretion by gastrin, cholecystokinin octapeptide (CCK-8), and the phorbol ester 12-O-tetradecanoylphorbol 13-acetate activated the Cl- conductance with a time course similar to that of histamine release. Therefore the ECL cell maintains a high resting potential, largely due to K+ currents, and stimulation of secretion activates a Cl- current, perhaps deriving from the membrane of the secretory granule that fuses with the plasma membrane. The depolarization that ensues may activate the K+ current to maintain the membrane potential during exocytosis.
Animals↗
Placental echolucencies: does their presence influence outcome following genetic amniocentesis?
Women undergoing genetic amniocentesis procedures were evaluated for the presence of ultrasonographic echolucencies within the placenta. Non-calcified sonolucencies < 4 to 5 cm were classified as subchorionic hematomas (SH). Of the 1,000 pregnancies evaluated, 153 (15%) pregnancies manifested SH prior to amniocentesis (study group). The indications for referral were similar in the study and control groups. There were 13 (1.3%) losses: 3 and 10 in the study and control groups, respectively, with no statistical difference in fetal losses between the groups: RR 1.52 (95% confidence interval 0.56-4.14; p = 0.32). Placental sonolucencies < 4 to 5 cm in diameter appear to be incidental ultrasound findings not associated with increased fetal loss following genetic amniocentesis. Complications following invasive prenatal diagnosis cannot be attributed to the presence of these common ultrasound findings.
Adult↗
The membrane topology of the rat sarcoplasmic and endoplasmic reticulum calcium ATPases by in vitro translation scanning.
The membrane topology of the rat endoplasmic reticulum (ER) and sarcoplasmic reticulum (SR) Ca2+ ATPases were investigated using in vitro transcription/translation of fusion vectors containing DNA sequences encoding putative membrane-spanning domains. The sequences of these Ca2+ ATPases are identical except for the COOH-terminal end, which contains an additional predicted transmembrane segment in the ER ATPase. The M0 and M1 fusion vectors (Bamberg, K., and Sachs, G. (1994) J. Biol. Chem. 269, 16909-16919) encode the NH2-terminal 101 (M0 vector) or 139 (M1 vector) amino acids of the H,K-ATPase alpha subunit followed by a linker region for insertion of putative transmembrane sequences and, finally, the COOH-terminal 177 amino acids of the H,K-ATPase beta subunit containing five N-linked glycosylation consensus sequences. The linker region was replaced by the putative transmembrane domains of the Ca2+ ATPases, either individually or in pairs. Transcription and translation were performed using [35S]methionine in a reticulocyte lysate system in the absence or presence of canine pancreatic microsomes. The translated fusion protein was identified by autoradiography following separation using SDS-polyacrylamide gel electrophoresis. When testing single transmembrane segments, this method detects signal anchor activity with M0 or stop transfer activity with M1. The first four predicted SERCA transmembrane domains acted as both signal anchor and stop transfer sequences. A construct containing the fifth predicted transmembrane segment was able to act only as a stop transfer sequence. The sixth transmembrane segment did not insert cotranslationally into the membrane. The seventh was able to act as both a signal anchor and stop transfer sequence, and the eighth showed stop transfer ability in the M1 vector. The ninth transmembrane segment had both signal anchor and stop transfer capacity, whereas the tenth transmembrane segment showed only stop transfer sequence properties. The eleventh transmembrane sequence, unique to the ER Ca2+ ATPase, had both signal anchor and stop transfer properties. These translation data provide direct experimental evidence for 8 or 9 of the 10 or 11 predicted transmembrane sequences in the current topological models for the SR or ER Ca2+ ATPases, respectively.
Amino Acid Sequence↗
Determination of the sidedness of the carboxy-terminus of the Na+/K(+)ATPase alpha-subunit using lactoperoxidase iodination.
The orientation of the carboxy-terminal pair of tyrosines of the Na+/K(+)-ATPase alpha-subunit with respect to the plane of the plasma membrane was determined. The approach was based on lactoperoxidase-catalysed radioiodination of the tyrosine residues accessible on the surface of the enzyme molecule in intact cells of a pig kidney embryonic cell line and those accessible in a broken plasma membrane fraction and in isolated membrane-bound Na+/K(+)-ATPase. The labeled alpha-subunit was isolated by SDS gel electrophoresis followed by electroblotting. Then the COOH-terminal amino acids were hydrolyzed by carboxypeptidases B and Y. Radioactivity and quantitative analysis of the protein and released amino acids showed that the COOH-terminal tyrosine residues of the alpha-subunit were only accessible to modification only when lactoperoxidase had access to the inner side of the plasma membrane. Therefore, the COOH-terminus of the Na+/K(+)-ATPase alpha-subunit is located on the cytoplasmic surface of the pump molecule and its polypeptide chain must have an even number of transmembrane segments.
Amino Acid Sequence↗