{"title":"[Value of nuclear medicine methods in hepato-gastroenterology--tumor detection].","authors":"R P Baum, G Hör","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":76844,"journal":{"name":"Zeitschrift fur Gastroenterologie. Verhandlungsband","volume":"26 ","pages":"134-6"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12877720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Widespread distribution of receptors for the peptide hormones cholecystokinin (CCK) and gastrin in the gut and in the CNS suggests therapeutic potential for selective antagonists of these hormones. Discovery of the natural product Asperlicin provided a new class of non-peptidal CCK antagonists, but oral bioavailability in this class remained elusive. With Asperlicin as a guide, the new, selective, orally bioavailable, high affinity CCK-A antagonist, MK-329 (L-364,718; Devazepide) and CCK-B/gastrin antagonist, L-365,260 have been developed. Biological profiles of these compounds are presented and results of early clinical evaluation of MK-329 are described. The significance of these agents as models for development of non-peptidal ligands for other receptors are briefly summarized.
{"title":"Molecular design of potent specific antagonists for the gastrin and cholecystokinin receptors.","authors":"B E Evans","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Widespread distribution of receptors for the peptide hormones cholecystokinin (CCK) and gastrin in the gut and in the CNS suggests therapeutic potential for selective antagonists of these hormones. Discovery of the natural product Asperlicin provided a new class of non-peptidal CCK antagonists, but oral bioavailability in this class remained elusive. With Asperlicin as a guide, the new, selective, orally bioavailable, high affinity CCK-A antagonist, MK-329 (L-364,718; Devazepide) and CCK-B/gastrin antagonist, L-365,260 have been developed. Biological profiles of these compounds are presented and results of early clinical evaluation of MK-329 are described. The significance of these agents as models for development of non-peptidal ligands for other receptors are briefly summarized.</p>","PeriodicalId":76844,"journal":{"name":"Zeitschrift fur Gastroenterologie. Verhandlungsband","volume":"26 ","pages":"269-71"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12878307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P B Salbach, U Janssen-Timmen, C Blattner, R Ziegler, A J Habenicht
It is well established that the low density lipoprotein (LDL) pathway functions to maintain a constant concentration of cellular cholesterol, but LDL effects that are unrelated to cholesterol metabolism have not been studied in great detail. In the present investigation we demonstrate that the LDL receptor pathway regulates cellular levels of free arachidonic acid (AA) and hence prostaglandin (PG) synthesis. We used platelet-derived growth factor (PDGF)-stimulated fibroblasts as a model system to investigate mechanism of LDL-dependent PG synthesis. PDGF-stimulated but not quiescent cells formed radiolabelled prostacyclin (PGI2) and PGE2 upon incubation with LDL that had been reconstituted with cholesteryl-(1-14C)-arachidonate (rec-LDL), while fibroblasts from patients that are afflicted with the LDL receptor negative phenotype of familial hypercholesterolaemia (FH) failed to synthesize significant amounts of PGs. Furthermore cells that had been preincubated with chloroquine or an anti LDL receptor antibody, that prevents binding of LDL to its receptor, did not produce significant amounts of PGs upon incubation with rec-LDL. Moreover incubation of PDGF-stimulated cells with LDL or AA led to a time and concentration-dependent inactivation of PGH synthase, the rate limiting enzyme of PG synthesis. When taken together our results establish a new role of the classical LDL receptor pathway of Brown and Goldstein by demonstrating that LDL provides AA to fibroblasts for eicosanoid formation and that LDL has a profound inhibitory effect on the key enzyme of PG synthesis, the PGH synthase.
{"title":"A new role for the low density lipoprotein receptor.","authors":"P B Salbach, U Janssen-Timmen, C Blattner, R Ziegler, A J Habenicht","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>It is well established that the low density lipoprotein (LDL) pathway functions to maintain a constant concentration of cellular cholesterol, but LDL effects that are unrelated to cholesterol metabolism have not been studied in great detail. In the present investigation we demonstrate that the LDL receptor pathway regulates cellular levels of free arachidonic acid (AA) and hence prostaglandin (PG) synthesis. We used platelet-derived growth factor (PDGF)-stimulated fibroblasts as a model system to investigate mechanism of LDL-dependent PG synthesis. PDGF-stimulated but not quiescent cells formed radiolabelled prostacyclin (PGI2) and PGE2 upon incubation with LDL that had been reconstituted with cholesteryl-(1-14C)-arachidonate (rec-LDL), while fibroblasts from patients that are afflicted with the LDL receptor negative phenotype of familial hypercholesterolaemia (FH) failed to synthesize significant amounts of PGs. Furthermore cells that had been preincubated with chloroquine or an anti LDL receptor antibody, that prevents binding of LDL to its receptor, did not produce significant amounts of PGs upon incubation with rec-LDL. Moreover incubation of PDGF-stimulated cells with LDL or AA led to a time and concentration-dependent inactivation of PGH synthase, the rate limiting enzyme of PG synthesis. When taken together our results establish a new role of the classical LDL receptor pathway of Brown and Goldstein by demonstrating that LDL provides AA to fibroblasts for eicosanoid formation and that LDL has a profound inhibitory effect on the key enzyme of PG synthesis, the PGH synthase.</p>","PeriodicalId":76844,"journal":{"name":"Zeitschrift fur Gastroenterologie. Verhandlungsband","volume":"26 ","pages":"107-9"},"PeriodicalIF":0.0,"publicationDate":"1991-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12877713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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