Biomedical subjects

Adam J Smolka

Publications and source records attributed to Adam J Smolka.

5 recordsLinked to original sources

PubMed2007

IL-1beta modulation of H,K-ATPase alpha-subunit gene transcription in Helicobacter pylori infection.

Helicobacter pylori infection of the human gastric body induces hypochlorhydria by perturbing acid secretion. H. pylori inhibits parietal cell H,K-ATPase alpha-subunit (HKalpha) gene and protein expression, providing a mechanistic basis for clinical hypochlorhydria. Given that H. pylori infection increases gastric mucosal IL-1beta, an acid secretory inhibitor, we investigated the role of IL-1beta in H. pylori-mediated inhibition of HKalpha transcription. Human gastric adenocarcinoma (AGS) cells were transfected with promoter-reporter constructs containing human HKalpha 5'-flanking sequence deletions. IL-1beta (10 ng/ml) had no effect on the transcriptional activity of six progressively shorter deletion constructs of the HKalpha promoter (HKalpha2179-HKalpha340) and significantly stimulated the activity of HKalpha206, HKalpha177, HKalpha165, and HKalpha102 deletion constructs (80%, 100%, 46%, and 35%, respectively). H. pylori inhibited the transcriptional activity of HKalpha2179, HKalpha206, HKalpha177, and HKalpha165; IL-1beta relieved the H. pylori inhibition of HKalpha2179 and HKalpha206 activity but not HKalpha177 and HKalpha165 activity. AGS cell pretreatment with a MEK1/2 inhibitor prevented the IL-1beta-mediated stimulation, but p38 and JNK pathway inhibitors did not. IL-1beta mRNA levels in AGS cells were low and unaffected by H. pylori, and ELISAs of H. pylori-conditioned AGS culture media showed no measurable IL-1beta secretion. These data indicate that an IL-1beta-dependent cis-response element lies downstream of -206 nt in the HKalpha promoter and that IL-1beta-mediated upregulation of HKalpha transcription is affected by an ERK1/2 kinase signal pathway. We conclude that an IL-1beta-responsive HKalpha cis element positively regulates HKalpha gene transcription in shortened deletion constructs and that H. pylori-induced inhibition of HKalpha transcription is not mediated by IL-1beta.

5' Flanking Region↗

PubMed2006

PrepMS: TOF MS data graphical preprocessing tool.

UNLABELLED: We introduce a simple-to-use graphical tool that enables researchers to easily prepare time-of-flight mass spectrometry data for analysis. For ease of use, the graphical executable provides default parameter settings, experimentally determined to work well in most situations. These values, if desired, can be changed by the user. PrepMS is a stand-alone application made freely available (open source), and is under the General Public License (GPL). Its graphical user interface, default parameter settings, and display plots allow PrepMS to be used effectively for data preprocessing, peak detection and visual data quality assessment. AVAILABILITY: Stand-alone executable files and Matlab toolbox are available for download at: http://sourceforge.net/projects/prepms

Algorithms↗

PubMed2004

Endogenous ouabain-like factor (OLF) secretion is modulated by nicotinic mechanisms in rat adrenocortical cells.

This study tested the hypothesis that rat adrenocortical secretion of endogenous ouabain-like factor (OLF) is regulated by nicotinic mechanisms. OLF secreted by dispersed cell suspensions of zona glomerulosa (ZG) and fasciculata/reticularis (ZFR) cells was found to co-elute with authentic ouabain by reverse phase HPLC; OLF concentrations in cell supernatants were measured by radioimmunoassay. Nicotine (10(-6) - 10(-3) M) stimulated significant OLF secretion in rat adrenocortical cells. Acetylcholine (10(-7) - 10(-4) M) and eserine (10(-7) - 10(-3) M) stimulated OLF secretion in ZG cells at lower concentrations and stimulated at higher concentrations. Acetylcholine had no effect on ZFR secretion of OLF, but eserine stimulated OLF secretion. ACTH (10(-8) M) strongly potentiated the OLF stimulatory effect of nicotine in ZG cells; however significant interactions between nicotine and ACTH or angiotensin II on OLF secretion in ZFR cells were not apparent. The ganglionic blockers hexamethonium and mecamylamine further potentiated the effect of nicotine, implicating nicotinic acetylcholine receptors (nAChRs) in regulation of OLF secretion. The alpha7-receptor antagonist methyllycaconitine (MLA) dose-dependently inhibited the effect of nicotine in the ZG cells, and in ZFR cells MLA potentiated nicotine-induced OLF secretion. These data suggest that nicotinic regulation may underlie OLF secretion by rat adrenocortical cells, and strongly suggest presence of functional nicotinic acetylcholine receptors on these cells.

Acetylcholine↗

PubMed2004

Inhibition of gastric H,K-ATPase activity and gastric epithelial cell IL-8 secretion by the pyrrolizine derivative ML 3000.

BACKGROUND: ML 3000 ([2,2-dimethyl-6-(4-chlorophenyl)-7-phenyl-2,3-dihydro-1H-pyrrolizine-5-yl]-acetic acid) is an inhibitor of both cyclooxygenase and 5-lipoxygenase in vitro, and shows promise as a novel non-steroidal anti-inflammatory drug (NSAID). Unlike conventional NSAIDs which are associated with gastric ulcerogenic effects, ML 3000 causes little or no damage to the gastric mucosa, even though it significantly depresses gastric prostaglandin synthesis. METHODS: As part of an effort to clarify mechanisms underlying the gastric sparing properties of ML 3000, we studied the effects of ML 3000 on H,K-ATPase activity in vitro, on acid accumulation in isolated gastric parietal cells, and on IL-8 secretion by gastric epithelial cells in culture. RESULTS: SCH28080-sensitive H,K-ATPase activity in highly-purified pig gastric microsomes was dose-dependently inhibited by ML 3000 (IC50 = 16.4 microM). Inhibition was reversible, and insensitive to ML 3000 acidification in the pH range 2.0-8.0. In rabbit gastric parietal cells,ML 3000 dose-dependently inhibited histamine-stimulated acid accumulation (IC50 = 40 microM) and forskolin-stimulated acid accumulation (IC50 = 45 microM). Lastly, in human gastric adenocarcinoma (AGS) cells, ML 3000 dose-dependently inhibited both baseline and IL-1beta-stimulated (20 ng/ml) IL-8 secretion with IC50s of 0.46 microM and 1.1 microM respectively. CONCLUSION: The data indicate that ML 3000 affects acid-secretory mechanisms downstream of cAMP mobilization induced by histamine H2 receptor activation, that it directly inhibits H,K-ATPase specific activity, and that baseline gastric epithelial cell IL-8 secretory inhibition may be mediated by ML 3000 inhibition of 5-lipoxygenase activity. We conclude that these gastric function inhibitory data may underlie the gastric sparing properties of ML 3000.

Acetates↗

PubMedDate not supplied

Parietal cell carcinoma of gastric cardia: immunophenotype and ultrastructure.

The case is reported of a clinically aggressive parietal cell carcinoma of the gastric cardia in a 67-year-old man. Histologically, the tumor was a poorly differentiated adenocarcinoma with a predominantly solid growth pattern, though with areas exhibiting glandular morphology and with extensive lymphatic invasion. The tumor cells had eosinophilic, finely granular cytoplasm, with focal Alcian blue-positive mucin in the gland lumens. Ultrastructural examination of the pleural metastasis and gastrectomy specimen demonstrated many mitochondria, tubulovesicular profiles of endoplasmic reticulum, and intracytoplasmic lumens, which resembled intracellular canaliculi of parietal cells. Immunohistochemically, there was positive staining of tumor cells for the parietal cell specific antibodies to H/K-ATPase and human milk fat globule-2 (HMFG-2).

Adenocarcinoma↗