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J F Rehfeld

Publications and source records attributed to J F Rehfeld.

At least 19 recordsLinked to original sources
PubMed1992

Co-transcription of the gastrin and cholecystokinin genes with selective translation of gastrin mRNA in a human gastric carcinoma cell line.

So far, no cells have been found to synthesize both of the homologous hormones, cholecystokinin and gastrin. Northern analysis and reverse transcription PCR showed, that the human gastric carcinoma cell line (AGS) expresses both a gastrin mRNA of 0.7 kb and a cholecystokinin transcript of 0.8 kb. A library of sequence-specific radioimmunoassays, cleavage with processing-like enzymes and chromatography subsequently revealed that the gastrin mRNA was translated into progastrin that was constitutively secreted into the medium (45 +/- 3 pmol/l). Neither procholecystokinin nor any of its processing products were detectable in cells and media. The results suggest that differentiation into gastrin- or cholecystokinin-producing cells may be regulated at the translational level. The gastric cell line, AGS, provides a model for studies of translational regulation of cell differentiation.

Blotting, Northern↗
PubMed1992

In vivo immunosorption--a method for the examination of hormone heterogeneity at low plasma concentrations. Application to progastrin and its products.

In order to investigate whether antibody desorption followed by chromatography is useful for the study of ligand heterogeneity in plasma, endogenous plasma gastrins were released from immunoglobulins by denaturation of antisera from 11 rabbits immunized against different fragments of human progastrin. The molecular nature of the in vivo immunosorbed plasma gastrins was characterized by gel chromatography monitored by a library of sequence-specific radioimmunoassays before and after enzyme cleavage. Subsequently, the plasma gastrins were compared with tissue gastrins in extracts of rabbit antral mucosa. The results show that carboxyamidated gastrins and their immediate glycine-extended precursors circulate in rabbit plasma. The carboxyamidated gastrins eluted as gastrin-34 and gastrin-17, both in sulfated and non-sulfated form. Correspondingly, glycine-extended gastrin-34 and gastrin-17 also occurred in plasma. The results confirm that the plasma of immunized animals contains substantial quantities of the corresponding endogenous ligands bound to specific antibodies. This in vivo immunosorption phenomenon can be used to study the molecular heterogeneity of hormones and their precursors, when they circulate in concentrations which are otherwise too low to permit examination of their molecular nature.

Amino Acid Sequence↗
PubMed1992

Identification of cholecystokinin/gastrin peptides in frog and turtle. Evidence that cholecystokinin is phylogenetically older than gastrin.

Peptides homologous to mammalian cholecystokinin (CCK) and gastrin in brain, antrum, and small intestine of an amphibian (the bullfrog, Rana catesbeiana) and a reptile (the turtle, Pseudomys scripta) were characterized. All tissues contained peptides reacting with antisera specific for the carboxyamidated C-terminal tetrapeptide common for CCK and gastrin. Extracts of all tissues, except the turtle antrum, also reacted with an antiserum specific for mammalian sulfated CCK, while no extract contained peptides reacting with an antiserum specific for mammalian gastrin. Both species contained predominantly small acidic forms in the brain and larger less acidic forms in the antrum and intestine. The antral peptides of both species were identified. The largest frog gastrin was a 47-residue peptide: DLLASLTHEQ KQLIMSQLLP ELLSELSNAE DHLHPMRDRD YAGWMDF.NH2. The largest turtle gastrin was a 52-residue peptide: DLLEALSQDQ KLLMAKFLPH IYAELANREG NWHEDAALRP LHDHDYPGWM DF.NH2. They display 51% similarity. Having Tyr in position 7 from the C-terminus, both resemble structurally mammalian CCK rather than gastrin, which suggests that CCK is phylogenetically older than gastrin. The turtle antral peptide contains a Tyr followed by Pro as in chicken gastrin. Thus, apparently at the stage of reptiles, a route different from the mammalian was taken in order to evolve a specific gastrin function.

Amino Acid Sequence↗
PubMed1992

Expression, but failing maturation of procholecystokinin in cerebellum.

The cerebellum is the only region of the central nervous system which has been found to be devoid of cholecystokinin (CCK). The assays used, however, have been directed against the alpha-amidated C-terminus of fully processed CCK peptides. Using Northern blot analysis and a library of radioimmunoassays specific for different sequences of proCCK in combination with chromatography and enzyme cleavage, we have now examined the expression and processing of proCCK in fetal, neonatal and adult cerebellar tissue from man, pig and rat. In rat cerebellum CCK mRNA was present already in the fetal state. Two weeks after birth the concentrations declined. Also proCCK was found in significant concentrations in the fetal human and rat cerebellum (approximately 20 pmol/g); but already before birth the expression began to decrease towards low concentrations in adults. The adult porcine cerebellum contained 3.2 pmol proCCK and glycine-extended processing intermediates per gram (range less than 0.1-10.4 pmol/g), and 0.8 pmol carboxyamidated CCK per gram (range 0.1-4.1 pmol/g) varying in size from CCK-58 to CCK-5. For comparison, the adult porcine cerebral cortex contained 757 pmol carboxyamidated CCK/g, 20 pmol glycine-extended CCK/g and no proCCK. We conclude that cerebellum expresses proCCK with the highest level of expression in fetal life. In comparison with other regions of the brain, the maturation to transmitter-active, carboxyamidated CCK peptides is, however, attenuated in both fetal and adult cerebellar tissue.

Aging↗
PubMed1992

Isolation, structure, and activity of -Phe-Met-Arg-Phe-NH2 neuropeptides (designated calliFMRFamides) from the blowfly Calliphora vomitoria.

Thirteen neuropeptides varying in length from 7 to 11 residues and ending C-terminally in -Phe-Met-Arg-Phe-NH2 (calliFMRFamides 1-13) and one dodecapeptide ending in -Met-Ile-Arg-Phe-NH2 (calliMIRFamide 1) have been isolated from thoracic ganglia of the blowfly Calliphora vomitoria. Different repeating patterns of amino acid sequences enable the peptides to be arranged into distinct groups. One such group of five nonapeptides has the sequence Xaa-Pro-Xaa-Gln-Asp-Phe-Met-Arg-Phe-NH2. Three peptides in this group, with the N-terminal tripeptide sequences Thr-Pro-Gln-, Thr-Pro-Ser-, and Ser-Pro-Ser-, are able to induce fluid secretion from the isolated salivary gland of Calliphora at a concentration of 0.1 to 1 nM. However, two other members of this group with the N-terminal tripeptide sequences Lys-Pro-Asn- and Ala-Pro-Gly-, the latter being the most abundant peptide isolated, were inactive in this assay, as were all the other peptides isolated. This indicates that the N terminus (in addition to the C terminus as previously found for FMRFamides of other organisms) is crucial for at least some biological activities.

Amino Acid Sequence↗
PubMed1992

Effects of gastric fundectomy and antrectomy on the exocrine pancreas in the hamster.

The effect of gastric fundectomy and antrectomy on growth of the exocrine pancreas was studied in hamsters over 5 and 25 d. Sham-operated animals served as controls. After 5 d, basal plasma gastrin concentrations were significantly increased in fundectomized animals (80.3 +/- 20.6 pmol/L) and significantly decreased in antrectomized animals (11.6 +/- 1.1 pmol/L) as compared with the controls (20.0 +/- 1.7 pmol/L). Similar differences were present among the 25-d groups, whereas basal plasma cholecystokinin (CCK) concentrations did not differ significantly between any groups at any time. At 5 d after fundectomy, there was a significant increase in pancreatic tissue [3H]-thymidine uptake and total DNA content, both of which were reduced 5 d after antrectomy. Autoradiography showed significantly increased [3H]-thymidine labeling index of acinar, intralobular duct, and centroacinar cells of the pancreas at 5 d after fundectomy. The increased intralobular duct cell labeling index persisted 25 d after fundectomy. Labeling indexes after antrectomy did not differ significantly from those in the controls, although antrectomized animals had the lowest values in all three cell compartments at 25 d. At 25 d, pancreatic wet wt and total DNA and protein content were significantly increased after fundectomy and significantly reduced after antrectomy. These findings indicate that fundectomy in the hamster induces pancreatic exocrine tissue hyperplasia and hypertrophy, whereas antrectomy leads to retardation of pancreatic growth.

Animals↗
PubMed1992

Ontogeny of procholecystokinin maturation in rat duodenum, jejunum, and ileum.

Expression and processing of procholecystokinin (proCCK) in rat intestine during development were examined using sequence-specific immunoassays, cleavage with processing-like enzymes, and chromatography. Fetal proCCK concentrations were similar in duodenum, jejunum, and ileum, but the maturation to CCK followed different courses: duodenal CCK increased from 14 pmol/g in the fetus to 86 pmol/g 4 days after birth and then declined to 17 pmol/g in the adult. In jejunum, CCK varied from 34 pmol/g in the fetus to 127 pmol/g at day 7, decreased to 54 pmol/g at day 21, and increased again to 93 pmol/g in the adult. Ileal CCK decreased from 20 pmol/g in the fetus to 10 pmol/g postnatally. Whereas duodenal proCCK after birth matured completely to carboxyamidated CCK, jejunoileal proCCK matured only partially. Chromatography showed an increase of tyrosine-sulfation and proteolytic processing of N-terminal sequences. At day 7 jejunal cholecystokinin octapeptide (CCK-8) constituted only a minute fraction of the carboxyamidated CCK, of which less than half was sulfated. However, in the adult jejunum, CCK-8 constituted a significant fraction, which was completely sulfated. It is concluded that the CCK gene is well expressed at propeptide level in the fetal small intestine. Postpartum maturation of proCCK, however, is late and differs in the three parts of the small intestine. The belated maturation supports the hypothesis that factors other than CCK regulate pancreatic growth in fetal and neonatal life.

Amino Acid Sequence↗
PubMed1992

Gastrin and cancer.

Explore the source record for details and available documents.

Amino Acid Sequence↗
PubMed1992

Endogenous hypercholecystokininemia model in the hamster: trophic effect on the exocrine pancreas.

Using Syrian golden hamsters, we studied the effect of pancreaticobiliary diversion (PBD) on plasma cholecystokinin (CCK) and exocrine pancreatic tissue over 5, 10, and 24 days. As compared with sham-operated controls, PBD-operated animals had increased plasma CCK concentrations by 228, 318, and 207% at 5, 10, and 24 days, respectively. Correspondingly, pancreatic wet weight increased by 24, 61, and 87%; total pancreatic protein by 6, 57, and 73%; and total pancreatic DNA by 35, 52, and 98%, respectively. At 5 days, but not at 10 and 24 days, there was a significant increase in the pancreatic tissue DNA concentration (p less than 0.01) and [3]H-thymidine incorporation into DNA (p less than 0.02). Autoradiography showed increased [3]H-thymidine labeling index in acinar cells at 5 and 10 days after PBD (p less than 0.01 and p less than 0.005). Although not significant, ductal cell labeling index was also increased at 5 and 10 days. These findings provide evidence that, as in the rat, PBD in the hamster induces hypercholecystokininemia with ensuing pancreatic hyperplasia and hypertrophy. The hamster model may be useful for studies on the effect of endogenous CCK on pancreatic ductal cell carcinogenesis and diseases of the gallbladder, neither of which can be studied in the rat.

Animals↗
PubMed1992

Gastric fundic epithelial proliferation after pancreaticobiliary diversion. Studies with quantitative histological analysis and autoradiography in the hamster.

The effect of pancreaticobiliary diversion (PBD) with hypercholecystokininemia on the gastric fundic mucosa was studied in the Syrian golden hamster over 5 and 24 days. Sham-operated animals served as controls. Basal plasma gastrin concentrations were significantly decreased on days 5 and 24. Five days after PBD, there was a significant increase in the scintigraphically measured [3H]-thymidine incorporation into fundic tissue. Correspondingly, there was a significant increase in the number of cells with [3H]-thymidine-labeled DNA in the proliferative zone of the fundic mucosa. The total number of cells in the gastric pits, the number of cells in the proliferative zone and the proliferation index were also significantly increased 5 days after PBD. Although the mean values of all variables were higher after PBD than in the control group on day 24, these increases were not significant. It is concluded that PBD at least transiently stimulates gastric fundic epithelial proliferation in the hamster. Whether this is an effect of hypercholecystokininemia remains to be definitely proven in further studies.

Animals↗
PubMed1992

Effects of gastric fundectomy and antrectomy on the colonic mucosa in the hamster.

The effects of gastric fundectomy and antrectomy on the colonic mucosa were studied in hamsters over 5 and 25 days. Sham-operated animals served as controls. Basal plasma gastrin concentrations were significantly increased after fundectomy and significantly decreased after antrectomy. Five days after fundectomy, there was a significant increase in scintigraphically determined colonic tissue [3H]-thymidine uptake and [3H]-thymidine labeling index of goblet cells, both of which were reduced 5 days after antrectomy. After fundectomy, the labeling index was maximal in differentiating-proliferative cells in the midportion of the colonic crypts, whereas the labeling index of the immature proliferative cells at the base of the crypts did not differ from that in the controls. On day 25, the crypt size and the number and percentage of goblet cells in the crypts were significantly increased in fundectomized animals. The number and percentage of goblet cells in antrectomized animals were significantly reduced on day 25. It is concluded that fundectomy in the hamster induces colonic mucosal hyperplasia with goblet cell proliferation, whereas antrectomy leads to retardation of colonic goblet cell proliferation.

Achlorhydria↗
PubMed1992

Does vagotomy affect the growth of the pancreas in the rat?

Vagotomy has been claimed to have a growth-promoting effect on the pancreas in the rat. The present study failed to show differences in total or relative pancreatic weight and DNA content between vagally intact and vagally denervated rats, whether normoCCKemic or hyperCCKemic after pancreaticobiliary diversion during 2-8 weeks. Contrary to the claims made in several recent reports, vagotomy does not seem to influence the growth of the rat pancreas.

Animals↗
PubMed1992

Pancreatic atrophy in rats produced by the cholecystokinin-A receptor antagonist devazepide.

According to recent reports, the powerful and selective cholecystokinin (CCK)-A receptor antagonist devazepide (also referred to as L-364,718 or MK-329) is without effect on the weight of the pancreas. This has been interpreted to mean that basal and meal-stimulated endogenous CCK does not play a major role in the normal maintenance of the pancreas. In the present study we show that continuous subcutaneous infusion of devazepide effectively and dose-dependently reduced the weight of the pancreas both in normal rats and in hyperCCKemic rats (because of pancreaticobiliary diversion). The maximum reduction of the pancreatic weight was 40%. Maximum or near-maximum effects were seen with a dose of 200 micrograms/kg/h. The DNA content of the pancreas was also reduced. The reduction in weight and DNA content of the pancreas was maximal after 10 days. Provided that devazepide acts solely by inhibiting CCK-A receptors, we can conclude that endogenous CCK plays an important role in both normal and stimulated growth of the rat pancreas.

Animals↗
PubMed1991

Immunohistochemical study of cholecystokinin peptide in rat spinal motoneurons.

With the aid of indirect immunofluorescence histochemistry and sequence specific antibodies a possible localization of cholecystokinin (CCK) peptide in spinal motoneurons has been analyzed. To increase peptide levels, the sciatic nerve was ligated, and the area around the ligation was studied 24 hours later. For comparison, antisera raised against calcitonin gene-related peptide (CGRP) and substance P were employed. With CCK specific antisera (directed to the N-terminal portion of CCK-8 or the midportion of CCK-33) accumulation of peptide-like immunoreactivity (LI) was observed in large, dilated axonal swellings proximal to, but at some distance from, the ligature. Such accumulations were also observed with C-terminally directed CCK antiserum, but in addition numerous axons of smaller diameter extending up to the ligation contained this type of immunoreactivity. The latter antiserum is thought to cross-react with CGRP. In fact, this staining pattern was indistinguishable from the one seen after incubation with CGRP antiserum. In contrast substance P-LI could not be seen in the larger dilated axons but only in large numbers of thinner fibers close to the ligation. Double staining experiments revealed that the large dilations contained both CGRP- and CCK-specific LI. Distal to the ligation CGRP- and substance P- but no specific CCK-LI could be observed. The present findings support the view that CCK mRNA in spinal motoneurons is translated into CCK peptide, at least after axotomy, and that the peptide is transported into the motoneuron axon. However, compared to CGRP the CCK levels are presumably low, and the functional role of CCK peptide in motoneurons remains to be established.

Animals↗
PubMed1991

Omeprazole 20 mg three days a week and 10 mg daily in prevention of duodenal ulcer relapse. Double-blind comparative trial.

In a double-blind, parallel-group clinical trial of 195 patients with duodenal ulcers who after a short-term study had relief of pain and healed ulcers proved endoscopically, 65 were randomized to receive 20 mg omeprazole 3 days a week (once in the morning from Friday to Sunday), 64 to receive 10 mg omeprazole once daily in the morning, and 66 to receive placebo for up to 6 months. The patients underwent repeat endoscopy with biopsy of the gastric fundic mucosa (qualitative assessment of argyrophilic cell population), assessment of symptoms, and laboratory screening with measurement of basal serum gastrin concentrations at 3 and 6 months or more often if indicated by recurrence of symptoms. At 3 months, endoscopically proved ulcer relapse occurred in 16% receiving 20 mg omeprazole 3 days a week; 21% receiving 10 mg omeprazole daily; and 50% receiving placebo. At 6 months, corresponding rates were 23%, 27%, and 67% with 95% confidence intervals of difference between the placebo group and omeprazole groups of 28%-60% and 24%-56% (P less than 0.00001), respectively, and between omeprazole groups of -19%-11% (NS). No major clinical or laboratory side effects were noted. Thus both omeprazole regimens are effective and safe in preventing duodenal ulcer relapse.

Adolescent↗
PubMed1991

Progastrin and its products in the cerebellum.

So far the only CNS neurons found to express gastrin have been hypothalamohypophyseal. Using a library of radioimmunoassays specific for different sequences of porcine progastrin in combination with chromatography and enzyme cleavages, 21 or 24 porcine cerebelli was now found to contain progastrin or its products. Sixteen cerebelli processed progastrin via glycine-extended intermediates to bioactive, carboxyamidated gastrin-17 and -34, half of the gastrins being tyrosine O-sulfated. The mean concentration of carboxyamidated gastrins was 0.8 pmol/g tissue (range less than 0.1-2.1 pmol/g), of glycine-extended intermediates 0.1 pmol/g (range less than 0.1-0.3 pmol/g) and of progastrin 0.4 pmol/g (range less than 0.1-1.0 pmol/g). The results show that the gastrin gene is expressed in more than a single region of the brain.

Amino Acid Sequence↗
PubMed1991

Cionin, a protochordean hybrid of cholecystokinin and gastrin: biological activity in mammalian systems.

The protochordean octapeptide cionin is structurally a hybrid of mammalian cholecystokinin (CCK) and gastrin, and thus their possible common ancestor. To determine whether cionin behaves like CCK or gastrin, we examined its effect on canine fundic somatostatin cells and on porcine and bovine gallbladder muscles. Cionin released somatostatin with a potency (ED50 0.15 nM) and efficacy (14.8% of cell content) similar to that of CCK-8 (ED50 0.12 nM, efficacy 16.7%). The efficacies but not the potencies of CCK-8 and cionin differed from those of sulfated gastrin (0.12 nM, 9.7%), nonsulfated gastrin (0.20 nM, 9.4%), and nonsulfated CCK-8 (0.30 nM, 10.4%). CCK and gastrin stimulated contractions of porcine gallbladder muscle strips in a concentration-dependent manner with no differences in efficacy but with characteristic differences in potency. CCK-8 and cionin displayed similar potencies of ED50 2.0 and 2.6 nM; both were significantly different from the ED50 of 0.4 microM for sulfated gastrin and 2.3 microM for nonsulfated gastrin. CCK radioligand binding to membrane-enriched preparations of porcine and bovine gallbladder muscularis was specific and of high affinity. The equilibrium data revealed that binding of CCK and gastrin peptides best fit a single site. CCK-8 and cionin displayed similar affinities [Kd 0.5 nM (porcine), 0.5 nM (bovine, CCK) vs. Kd 0.8 and 0.9 nM (cionin), respectively]. These differed again significantly from Kd 0.6 and 1.5 microM (sulfated gastrin) and 0.7 and 0.2 microM (nonsulfated gastrin). The results show that cionin behaves like CCK rather than gastrin in mammals.

Amino Acid Sequence↗