Biomedical subjects

M Höcker

Publications and source records attributed to M Höcker.

At least 37 records · Page 2Linked to original sources

PubMed1996

The human histidine decarboxylase promoter is regulated by gastrin and phorbol 12-myristate 13-acetate through a downstream cis-acting element.

Transcriptional regulation of the human histidine decarboxylase (HDC) gene by gastrin and the phorbol ester phorbol 12-myristate 13-acetate (PMA) was studied using transient transfection of human HDC promoter-luciferase constructs in a human gastric carcinoma cell line (AGS-B) that expresses the human cholecystokinin-B/gastrin receptor. The transcriptional activity of the human HDC promoter was stimulated 3-4-fold by gastrin and 13-fold by PMA, effects that could be blocked by down-regulation or antagonism of protein kinase C. 5'- and 3'-deletion analysis demonstrated that the sequence responsible for gastrin- and PMA-stimulated transactivation (gastrin response element (GAS-RE)) was located in a region (+2 to +24) downstream of the transcriptional start site (+1) in the human HDC promoter and contained a palindrome (5'-CCCTTTAAATAAAGGG-3'). When ligated upstream of the herpes simplex virus 1 thymidine kinase promoter, a single copy of the GAS-RE was sufficient to confer responsiveness to gastrin and PMA. Electrophoretic mobility shift assays with specific competitors and factor-specific antibody supershifts showed that the labeled GAS-RE bound a novel nuclear factor(s). In addition, both gastrin and PMA increased binding of this factor to the GAS-RE. Hence, the palindromic GAS-RE site is sufficient to explain the gastrin/PMA responsiveness of the human HDC promoter and appears to bind a novel transcription factor.

Base Sequence↗

PubMed1996

Rat histidine decarboxylase promoter is regulated by gastrin through a protein kinase C pathway.

The enzyme L-histidine decarboxylase (HDC; EC 4.1.1.22), which converts L-histidine to histamine, plays a key role in the regulation of acid secretion. In the rat and human stomach, the peptide hormone gastrin appears to be one of the main regulators of HDC expression. In rats, marked elevation of gastric HDC mRNA abundance was observed within 12 h after induction of hypergastrinemia by a single injection of the proton-pump blocker omeprazole. In situ hybridization revealed that HDC expression occurred in the basal third of gastric glands where enterochromaffin-like cells are localized. To study the regulation of HDC gene transcription, 1,291 nucleotides of the 5'-flanking region of the rat HDC gene and the noncoding portion of exon 1 were cloned and sequenced. Gastrin and cholecystokinin (CCK) octapeptide equipotently stimulated the transcriptional activity of the rat HDC promoter three- to fourfold, and deletion analysis revealed the presence of a gastrin response element within 201 nucleotides upstream of the translational start site. Time-course studies revealed maximal activation of the HDC promoter after 12-36 h. Direct stimulation of protein kinase C (PKC) with the phorbol ester phorbol 12-myristate 13-acetate (PMA) substantially elevated rat HDC promoter activity, whereas induction of Ca2+ -dependent signaling pathways with thapsigargin was without effect. Downregulation or blockade of PKC abolished the effects of gastrin and PMA on the HDC promoter. These data indicate that stimulation of the CCK-B/gastrin receptor activates the rat HDC promoter in a time- and dose-dependent fashion and that this effect is primarily mediated via a PKC-dependent signaling pathway. Use of HDC as a model gene will allow further investigation of the intracellular pathways that are involved in gastrin-dependent gene regulation.

Animals↗

PubMed1995

Differential inhibitory effects of serine/threonine phosphatase inhibitors and a calmodulin antagonist on phosphoinositol/calcium- and cyclic adenosine monophosphate-mediated pancreatic amylase secretion.

BACKGROUND: Protein phosphorylation and dephosphorylation events are considered to be key steps in the control of agonist-induced pancreatic enzyme release. This study was designed to characterize the role of serine/threonine phosphatases in phosphoinositol/calcium- and cyclic adenosine monophosphate (cAMP)-mediated stimulus-secretion coupling in rat pancreatic acini. METHODS: Isolated rat pancreatic acini were incubated with either the serine/threonine phosphatase inhibitors okadaic acid, calyculin A, and cyclosporin A or the calmodulin antagonist W-7. Amylase secretion was stimulated with cholecystokinin (CCK)-8, secretin, vasoactive intestinal polypeptide (VIP) or pituitary adenylate cyclase-activating polypeptide (PACAP), and the intracellular second messengers calcium and cAMP were determined. RESULTS: Okadaic acid or calyculin A reduced secretagogue-stimulated amylase release to near-basal levels. Inhibition of cAMP-mediated secretion (by VIP, secretin, or PACAP) occurred at lower concentrations than with inositol triphosphate (IP3)/Ca(2+)-dependent enzyme release (via CCK). Cyclosporin A diminished CCK-8-stimulated secretion by 35%, whereas secretion in response to cAMP-mediated secretagogues was not affected. W-7 completely inhibited acinar secretion in response to cAMP-or IP3/Ca(2+)-mediated secretagogues. Binding of 125I-CCK-8- or 125I-PACAP-(1-27) to acini was not influenced by the phosphatase inhibitors or W-7. Okadaic acid and calyculin A affected neither CCK-8-stimulated intracellular Ca2+ release nor PACAP-(1-27)-stimulated cAMP synthesis, whereas W-7 inhibited by 50% and 40%, respectively. CONCLUSIONS: The inhibitory profiles of okadaic acid, calyculin A, cyclosporin A, and W-7 indicate that phosphatases 1 and 2A play a relevant role in cAMP-mediated enzyme release, whereas phosphatases 1 and 2B are predominantly involved in IP3/Ca(2+)-dependent stimulus-secretion coupling. The calmodulin antagonist W-7 interferes at multiple steps of intracellular signal-transduction pathways.

Amylases↗

PubMed1994

Calyculin A, okadaic acid and W-7 interfere with a distal step in pancreatic acinar signal transduction.

The effects of the serine/threonine phosphatase inhibitors calyculin A, okadaic acid and the calmodulin antagonist W-7 on amylase secretion were studied in pancreatic acini. Calyculin A and okadaic acid dose-dependently inhibited amylase secretion to basal levels when stimulated with the intracellularly acting secretagogues thapsigargin, 8-br-cAMP or PMA. W-7 dose-dependently inhibited thapsigargin- or 8-br-cAMP-induced amylase secretion. In combination, thapsigargin, 8-br-cAMP and PMA induced amylase secretion comparable to the stimulation by cholecystokinin. Their effect was significantly inhibited by calyculin A, okadaic acid or W-7. These data imply that type 1- and 2b-phosphatases and calmodulin play a key role in the stimulation of exocrine pancreatic secretion at a distal step of both the Ca2+/IP3- and cAMP-mediated signal-transduction pathways.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1994

Cyclosporine A inhibits protein-kinase-C-mediated amylase release from isolated rat pancreatic acini.

The present study was performed to characterize a direct influence of cyclosporine A (CsA) on exocrine pancreatic enzyme secretion. CsA inhibited dose-dependently amylase release from isolated rat pancreatic acini in response to carbachol or cholecystokinin octapeptide (CCK-8). A significant reduction in amylase release by 17% was observed at 0.2 mumol/l CsA (p < 0.001) when compared to controls. At 0.2 mmol/l, CsA reduced amylase release in response to both secretagogues by maximally 45%, whereas basal secretion was not affected. CsA had no influence on CCK-8-stimulated increase in intracellular Ca2+ concentrations or amylase release in response to the Ca2+ ionophore A 23187. In contrast, the dose-response curve for amylase secretion induced by the phorbol ester phorbolmyristate-13-acetate was shifted to the right without a reduction of the maximal secretory response. Unexpectedly, vasoactive-intestinal-polypeptide- and secretin-stimulated acinar secretion was not diminished by CsA. In isolated pancreatic lobules exposed to 0.1 mmol/l CsA, amylase release stimulated by cerulein or veratridine was reduced by 26.7 +/- 2 or 28.3 +/- 4%, respectively. CsA had no influence on the displacement of 125I-Bolton-Hunter-labeled CCK-8 from acinar CCK receptors. The ultrastructure of cellular organelles in isolated lobules was not altered after incubation with 0.1 mmol/l CsA for 60 min. Our data suggest that CsA interferes with protein-kinase-C-mediated signal transduction in isolated rat pancreatic acini, without affecting cAMP-dependent signalling.

Amylases↗

PubMed1994

Serine/threonine phosphatases play a role in stimulus-secretion coupling in pancreatic acinar cells.

The role of serine/threonine phosphatases in Ca2+/IP3- and cAMP- mediated stimulus-secretion coupling was investigated in isolated pancreatic acinar cells. Cyclosporine A, an inhibitor of type 2b serine/threonine phosphatases, maximally reduced CCK-8-stimulated amylase secretion by 33%. In contrast, the secretory response to secretin or PACAP-(1-27) was not significantly altered by cyclosporine A independent of the secretagogue-concentration okadaic acid significantly reduced amylase release, induced by Ca2+/IP3-mediated- (CCK-8) or cAMP-mediated agonists (secretin, PACAP-(1-27), VIP) at concentrations that primarily inactivate type 1 and 2b phosphatases. Calyculin A, another type 1 and 2a phosphatase inhibitor, had a similar inhibitory effect on CCK-8-, secretin- or PACAP-(1-27)-induced secretion. In permeabilized acini, cyclosporine A reduced calcium-induced amylase release by 20%, whereas okadaic acid and calyculin A had an inhibitory effect by 55% and 52%, respectively. The ultrastructure of CsA-incubated acinar cells was not different from vehicle-incubated control lobules. In contrast, incubation with okadaic acid for 60 min resulted in morphological alterations of the Golgi apparatus, leading to a fragmentation of Golgi cisternae into small vesicles. Our data suggest a role of type 1 and 2b phospatases in stimulus-secretion coupling of both signal-transduction pathways in pancreatic acinar cells. These phosphatases might also be important for the maintenance of pancreatic cellular ultrastructure.

Amylases↗

PubMed1993

PD 135158, a CCKB/gastrin receptor antagonist, stimulates rat pancreatic enzyme secretion as a CCKA receptor agonist.

The CCKB/gastrin receptor antagonist, PD 135158 (CAM 1028), surprisingly stimulates lipase release from isolated rat pancreatic acini dose dependently in a biphasic manner, with identical efficacy but lower potency compared to cholecystokinin octapeptide (CCK-8). Half-maximal stimulation occurred at 0.6 microM and maximal secretion was induced at 50 microM. Supramaximal concentrations decreased lipase release. Acinar lipase secretion in response to 25 pM CCK-8 or 1 microM CAM-1028 was abolished by 5 microM of the specific CCKA receptor antagonist loxiglumide (CR 1505), half-maximal inhibition was observed at 0.6 microM for CCK-8 and 0.4 microM for PD 135158. These data demonstrate that the CCKB/gastrin receptor antagonist, PD 135158, acts as a full agonist at the rat pancreatic CCKA receptor.

Animals↗

PubMed1993

Putrescine uptake in rat pancreatic acini: effect of secretagogues and growth factors.

Polyamines [putrescine (Put), spermidine, and spermine] are normal cellular constituents that can modulate cellular proliferation and differentiation in a number of tissue and cell types. Transport is one of the mechanisms that control intracellular polyamine content. The present investigation explores the influence of cholecystokinin (CCK), other secretagogues [carbachol, bombesin, vasoactive intestinal polypeptide (VIP)], insulin, insulin-like growth factor 1 (IGF-1), and epidermal growth factor (EGF) on Put uptake in rat pancreatic acini. Insulin, IGF-1, and EGF stimulated Put uptake by 30-40%. Insulin did not enhance intracellular metabolism of Put. In contrast, CCK and the other secretagogues inhibited this transport system by 40-50% of control (VIP by 23% only). Further investigations of the inhibitory effect of CCK revealed that the maximal uptake rate of Put (Vmax) shifted from 346 pmol [14C]Put/mg DNA-min (control) to 265 pmol [14C]Put/mg DNA-min (100 pM CCK), whereas the Km was only moderately influenced. Augmented Put efflux as well as increased production of endogenous Put (possibly induced by CCK) did not contribute to this change in transport kinetics. In addition, the inhibition of Put uptake induced by CCK was specific and dose dependent up to 100 pM. CCK at 1,000 pM exerted only minor inhibition (20% of control). Incubation with the Ca-ionophore A 23187 did not influence Put accumulation, whereas treatment with the phorbol ester phorbol 12-myristate-13-acetate led to enhanced Put uptake (30-40%). Pretreatment of the acini with 1 mM ouabain led to a reduction of Put uptake by 43%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

PACAP and VIP stimulate enzyme secretion in rat pancreatic acini via interaction with VIP/PACAP-2 receptors: additive augmentation of CCK/carbachol-induced enzyme release.

The binding and biological effect of pituitary adenylate cyclase activating polypeptide (PACAP), a novel hypothalamic peptide with high sequence homology to vasoactive intestinal polypeptide (VIP), were studied in rat AR 4-2 J pancreatic carcinoma cells and isolated rat pancreatic acini. PACAP(1-27) and analogue PACAP(1-23, VIP-24-28), but not VIP, displaced potently and reversibly 125I-PACAP(1-27) from binding to an abundantly expressed high affinity PACAP-preferring receptor on AR 4-2 J cells, referred to as "PACAP-1 receptor." High affinity binding was dependent on N-terminal and C-terminal residues of PACAP(1-27): PACAP(1-24,Cys-25) (7.3 +/- 1.6 microM), PACAP(1-23) (8.2 +/- 1.5 microM), VIP (> 30 microM), PACAP(3-27), PACAP(1-19), PACAP(3-19), PACAP(1-12), and PACAP(18-38) (all > 50 microM) showed low or no binding potency. In contrast, high and low affinity binding of 125I-VIP to AR 4-2 J cells was displaced equipotently by PACAP(1-27) and VIP, thus defining on these cells, in addition, two scarcely expressed binding sites, designated "VIP/PACAP-2 receptor," similar or identical to the previously described high and low affinity acinar VIP receptor. Binding of 125I-PACAP(1-27) to a high and low affinity binding site on rat pancreatic acini was inhibited equipotently by PACAP(1-27) and VIP, identifying these sites as VIP/PACAP-2 receptors. PACAP(1-23) recognized both type 2 binding sites with only slightly lower affinity. PACAP(1-27), PACAP(1-38), PACAP(1-23, VIP-24-28), and PACAP(1-23) equipotently stimulated acinar lipase release and cyclic AMP production in pancreatic acini. Co-incubation of PACAP(1-27) or VIP with cholecystokinin-8 or carbachol revealed additive effects on enzyme secretion. Our results suggest the predominant expression of VIP/PACAP-2 receptors on rat pancreatic acini, whereas AR 4-2 J cells express mainly PACAP-1 receptors. PACAP is a potent ligand for both receptor types and has to be regarded as a novel VIP-like pancreatic secretagogue.

Amino Acid Sequence↗

PubMed1992

Determination of plasma cholecystokinin (CCK) concentrations by bioassay and radioimmunoassay in man. A critical evaluation.

The present investigation was designed to perform a direct comparison of a rat pancreatic acini bioassay system and a specific CCK radioimmunoassay (antiserum G-160) for the measurement of fasting and meal-stimulated plasma CCK in the presence and absence of the CCK receptor antagonist loxiglumide. The G-160 CCK antiserum is directed against the C-terminal O-sulfated tyrosine residue of the CCK molecule which is essential for full bioactivity of CCK peptides. For plasma extraction prior to bioassay measurement, hydrophobic reverse-phase chromatography on octadecylsilane cartridges was employed and resulted in simultaneous adsorption and elution of both CCK peptides and loxiglumide with recoveries of 87.5 +/- 9% and 75.0 +/- 5.9%, respectively. In the absence of loxiglumide, fasting and meal-stimulated values for CCK-like bioactivity and CCK-immunoreactivity (IR-CCK) were nearly identical (basal values: 1-2 pmol/l; meal-stimulated plateau levels: 4-6 pmol/l). After intravenous infusion of loxiglumide (30 mg/kg/h for 10 min, 10 mg/kg/h thereafter), resulting in plasma steady state levels of 200-300 mumol/l, meal-stimulated CCK-like bioactivity was undetectable, whereas IR-CCK levels were augmented 6.5-fold. In the bioassay system, standard samples containing 50 mumol/l loxiglumide produced complete inhibition of acinar lipase release in response to 50 pmol/l synthetic CCK-8. We conclude, that postprandial circulating non-CCK-like factors do not contribute significantly to the direct receptor-mediated stimulation of exocrine pancreatic secretion. The good agreement of CCK-like bioactivity and IR-CCK levels in the absence of loxiglumide confirms the sensitive and specific recognition of bioactive CCK peptides by the G-160 antiserum and suggests that this antibody exerts binding characteristics probably similar to a pancreatic acinar receptor.

Adult↗

PubMed1992

Putrescine uptake and metabolism in isolated rat pancreatic acini.

In addition to de novo synthesis, polyamine uptake is one of the major mechanisms in the regulation of intracellular polyamine concentrations. The aim of the present study was to investigate the uptake of putrescine (PUT) in isolated rat pancreatic acini and its further metabolic transformation. PUT accumulation was nearly linear over 60 min, showed saturation kinetics with an apparent Km of 3 x 10(-5) M and a Vmax of 346 pmol [14C]-PUT/min/mg DNA and decreased with decreasing temperature. Potassium cyanide (KCN) and dinitrophenol (DNP) inhibited PUT uptake. In the absence of a transmembrane Na+ gradient, PUT uptake decreased by 50%. After 60 min of incubation, 31% of the accumulated [14C]-PUT was metabolized. PUT uptake was stimulated by several amino acids, except for lysine, by decreasing the apparent Km for PUT uptake. PUT accumulation was reduced by spermidine (0.1 mM) by about 90%. Acetylated polyamines had only a minor effect. The release of radioactive material from prelabelled acini was only 10-20% after 90 min.

Amino Acids↗

PubMed1991

Cholecystokinin receptor antagonist loxiglumide modulates plasma levels of gastro-entero-pancreatic hormones in man. Feedback control of cholecystokinin and gastrin secretion.

The effect of the potent specific cholecystokinin (CCK) receptor antagonist loxiglumide on meal-stimulated plasma concentrations of CCK, gastrin, pancreatic polypeptide (PP), neurotensin, glucose-dependent insulinotropic polypeptide (GIP), insulin and C peptide was investigated in a placebo-controlled study in 10 healthy male volunteers. Intravenous infusion of loxiglumide (10 mg kg-1 h-1) significantly augmented integrated incremental IR-CCK levels 7.3-fold after stimulation by a standard breakfast (504 +/- 54 vs 3.665 +/- 365 pmol-1 135 min-1, P less than 0.001), as measured by a specific CCK radioimmunoassay. Basal IR-CCK concentrations were not affected by administration of loxiglumide. Oral treatment with bile acids (2 g ursodeoxycholic acid plus 2 g chenodeoxycholic acid) together with the meal abolished this augmentation, whereas high-dose substitution with pancreatic enzymes (4.2 g pancreatin) reduced elevated IR-CCK levels by only 38%. CCK-like bioactivity, determined by a bioassay using rat pancreatic acini, was not detectable in all samples that contained loxiglumide at plasma concentrations of 100-250 micrograms ml-1. Plasma gastrin concentrations in response to the breakfast were elevated 3.2-fold during loxiglumide infusion and not influenced by substitution with bile acids or pancreatic enzymes. Meal-stimulated integrated incremental plasma PP concentrations were significantly suppressed (55-65% inhibition, P less than 0.01) by loxiglumide. Infusion of the CCK receptor antagonist only slightly increased postprandial peak plasma glucose, insulin and C-peptide levels, whereas GIP and neurotensin levels were not significantly influenced. These findings suggest: (i) CCK secretion is under feedback control by intraduodenal bile acids and to a lesser extent by pancreatic enzymes; (ii) simultaneous extraction of CCK and loxiglumide results in circulating plasma CCK-like bioactivity of zero; (iii) gastrin secretion is feedback controlled via an indirect mechanism probably involving CCK-induced somatostatin secretion; (iv) release of PP is under inhibitory control of CCK; (v) CCK does not play a major role as insulinotropic hormone in the entero-insular axis in humans.

Adult↗

PubMed1991

Role of CCK in regulation of pancreaticobiliary functions and GI motility in humans: effects of loxiglumide.

To evaluate the physiological role of cholecystokinin (CCK) in humans, we studied the influence of the specific CCK receptor antagonist loxiglumide (CR 1505) on gallbladder contraction, pancreatic enzyme output, plasma CCK concentrations, mouth-to-cecum transit time (MCTT), stool weight, and fecal fat excretion. Infusion of CCK-8, producing CCK plasma levels of 10-12 pmol/l, decreased gallbladder volume to 21% of the initial volume (P less than 0.01) and increased bilirubin output 8- to 10-fold and pancreatic enzyme secretion 2- to 4-fold. Infusion of loxiglumide (10 mg.kg-1.h-1 iv) abolished CCK-8-stimulated enzyme and bilirubin output. Basal gallbladder volume increased 68% during loxiglumide infusion (P less than 0.001) and 137% (P less than 0.001) after 7 days of oral loxiglumide treatment (3 x 1.6 g/day). Gallbladder contraction and bilirubin output in response to the intraduodenal instillation of a liquid meal (382 kcal) was completely inhibited by loxiglumide; gallbladder volume even increased 45% postprandially during loxiglumide infusion (P less than 0.02) and 145% after long-term loxiglumide treatment (P less than 0.001). Meal-stimulated pancreatic enzyme output was diminished 46-53% after acute and 25-29% after chronic administration of loxiglumide. Meal-stimulated integrated plasma CCK-immunoreactive (CCK-ir) concentrations, determined by RIA, were 3.2-fold higher during loxiglumide infusion (P less than 0.02); plateau CCK levels were markedly elevated (10.1 +/- 1.4 vs. 3.7 +/- 0.5 pM). Plasma CCK-like bioactivity, measured by a sensitive bioassay, was identical to CCK-ir levels in the absence of loxiglumide; in the presence of loxiglumide, no circulating CCK-like bioactivity was detectable, indicating complete inhibition of plasma CCK. MCTT was augmented 24% (P less than 0.05). Oral treatment with loxiglumide increased stool weight 72% (P less than 0.01) and fecal fat excretion 186% (P less than 0.001). In conclusion, 1) meal-induced gallbladder contraction and fasting tone are primarily controlled by CCK; 2) the contribution of CCK to the intestinal phase of postprandial pancreatic enzyme secretion is 40-50%; 3) GI motility and absorption are partially controlled by CCK; and 4) postprandial CCK secretion is substantially augmented by loxiglumide via an unknown mechanism.

Adult↗

PubMed1991

[The marginal periodontium on osseointegrated implants--literature review and own investigations. 2. Own investigations].

19 IMZ-implants with a medium age of incorporation of 10.5 months were examined at four sites concerning their periimplantary situation. Gingival index, bleeding on probing, pocket depth and composition of subgingival plaque corresponded in 67% of the examined sites with periodontal health. Favourable correlations were stated between the values of plaque index and of the bleeding on probing as well as between the wide of fixed gingiva and the dimension of gingival recession. Compared to bridge constructions more unfavourable results concerning the amount of plaque and clinical criteria of the gingival margin were observed in case of mucosal fixed prostheses.

Adult↗

PubMed1990

Measurement of tissue cholecystokinin (CCK) concentrations by bioassay and specific radioimmunoassay: characterization of the bioactivity of CCK-58 before and after tryptic cleavage.

Cholecystokinin (CCK) was measured in an extract of porcine brain by a bioassay system based on the enzyme release from isolated pancreatic acini and a specific radioimmunoassay. The tissue extract represented a crude peptide preparation of porcine brain that contained several molecular forms of CCK, most of them of high molecular weight including CCK-58. The different molecular forms of CCK in the porcine brain extract were isolated by high performance liquid chromatography (HPLC). Determination of CCK-like bioactivity and immunoreactivity after HPLC was performed in parallel by bioassay and radioimmunoassay, respectively CCK-58 was the most abundant molecular form in the porcine brain extract, followed by CCK-33, and CCK-8. Both assay systems measured similar relative concentrations of all different molecular forms of CCK. To elucidate the biological potency of CCK-58 before and after tryptic cleavage, a CCK-58-enriched fraction was prepared by HPLC. Part of this material was quantitatively cleaved by trypsin resulting in the formation of small molecular forms of CCK. Bioactivity and immunoreactivity of equal amounts of cleaved and uncleaved material (= CCK-58) were determined by bioassay and radioimmunoassay in parallel. Cleavage of CCK-58 increased CCK-like bioactivity by 260% and CCK-like immunoreactivity by 310%. These results indicate that in a rat pancreatic acini system, porcine CCK-58 exerts 25-30% bioactivity compared to smaller CCK forms. The specific CCK antiserum G-160 seems to possess 25-30% affinity to CCK-58 in comparison to trypsin-cleaved CCK-58. It can be concluded that this antiserum exhibits an affinity to different molecular forms of CCK which parallels their relative bioactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Cholecystokinin receptor antagonist loxiglumide: influence on bilio-pancreatic secretion and gastrointestinal hormones in man.

We characterized the effect of the specific cholecystokinin (CCK) receptor antagonist loxiglumide (CR 1505) on gallbladder contraction, pancreatic enzyme output and plasma CCK concentrations determined by radioimmunoassay and bioassay. Gallbladder emptying and bilirubin output in response to the intraduodenal administration of a mixed liquid meal were completely inhibited by an intravenous infusion of loxiglumide (10 mg/kg/h). In contrast, meal-stimulated pancreatic enzyme secretion was diminished by only 30-40%. CCK concentrations in response to the test meal were 3-fold higher during infusion of loxiglumide, as determined by radioimmunoassay. In the absence of the antagonist, the bioassay measured CCK plasma levels identical to those determined by radioimmunoassay. In the presence of loxiglumide, CCK-like bioactivity was not detectable, indicating that the plasma concentrations of the CCK receptor antagonist were sufficient to abolish all circulating CCK-like bioactivity. We conclude that fasting volume and meal-induced contraction of the gallbladder are controlled by CCK. Postprandial pancreatic enzyme secretion, however, is mainly mediated by non-CCK-dependent mechanisms. Plasma CCK-like immunoreactivity is increased by loxiglumide, whereas plasma CCK-like bioactivity is zero in the presence of an CCK-receptor antagonist.

Adult↗

PubMed1989

[Acceptance of the dental care for the elderly and old people].

By way of introduction, there is represented the value of oral health in view of the well-being and physical powers of aged persons. Rfefering to literary findings and own test results, the psychosocial problems which have to be considered in the stomatological attendance of aged citizens are analysed. In this connection, there are defined especially those factors wich have a positive or negative influence, respectively on the demands of aged citizens as to the attendence. Concluding, there is put emphasis on the tasks which arise in the field of education, instruction, continued professional training and medical care.

Aged↗

PubMed1989

[Overview of dental care in the elderly and old people].

On the basis of the demographic developments, the present status of oral health and the national indicators for oral health in old people, the general points of organization of the dental care was demonstrated. In this coherence it was point to different groups of patients. Especially the factors influencing the behaviour of taking up dental care was emphasized.

Aged↗