Insulinotropic properties of synthetic human gastric inhibitory polypeptide in man: interactions with glucose, phenylalanine, and cholecystokinin-8.

The quantitative contribution of glucose-dependent insulinotropic polypeptide [gastric inhibitory polypeptide (GIP)] to the incretin effect after oral glucose (augmentation of insulin secretion over the degree that is explained by the glycemic rise) is not known. Therefore, hyperglycemic clamp experiments (8 mmol/L, corresponding to postprandial glucose concentrations) were performed in healthy volunteers, and synthetic human GIP was infused for 60 min at a rate (approximately 1.3 pmol/kg.min) that results in plasma GIP concentrations similar to those occurring after oral glucose loads of 75 g. The MCR for exogenous GIP was approximately 6 mL/kg.min; the decay after ceasing infusion was exponential with a t1/2 of about 18 min, and the resulting volume of distribution was about 140 mL/kg. At euglycemic (basal) plasma glucose concentrations (5.0 mmol/L) similar values were found. Insulin secretion was stimulated by hyperglycemia alone, but was greatly (2.3-fold based on C-peptide) potentiated by GIP infusions (P less than or equal to 0.001 for integrated incremental values). When integrated incremental responses over 120 min of GIP, immunoreactive insulin, and immunoreactive C-peptide were compared after oral glucose and during GIP infusions, no significant differences were found. Peak glucose concentrations after oral glucose (7.6 +/- 0.6 mmol/L) were similar to mean plasma glucose values during clamp experiments (8.2 +/- 0.1 mmol/L; P = 0.124). However, mean glucose concentrations after oral glucose were lower (6.0 +/- 0.3 mmol/L; P = 0.0004). Additional infusion of sulfated cholecystokinin-8 (25 pmol/kg.h) or the amino acid phenylalanine (1.7 mumol/kg.min) did not further stimulate insulin secretion and had no influence on the pharmacokinetics of exogenous GIP. It is concluded that human synthetic GIP is insulinotropic in man and that this activity may well explain a substantial part of the incretin effect after oral glucose. There is no interaction with cholecystokinin or phenylalanine in concentrations found after mixed meals.

Complete tyrosine O-sulfation of gastrin in adult and neonatal cat pancreas.

We have found gastrin in both the adult and neonatal cat pancreas. In contrast with the main production sites, antrum and duodenum, gastrin in the pancreas occurs in a single molecular form, tyrosine O-sulfated gastrin-17. Since tyrosine sulfation increases the pancreozymic effect of gastrin, the complete sulfation seems functionally expedient.

Cell-specific processing of pro-cholecystokinin and pro-gastrin.

The present review argues that the gastrin-cholecystokinin family is a suitable model for the study of cell-specific processing of pro-hormones. First, the homologous active site of the hormones is a precisely defined tetrapeptide amide, which is well preserved during evolution. Second, the genes of both hormones are translated in a variety of cells (neurons, endocrine cells, paracrine cells, lymphocytes, etc,), but to a varying degree during ontogenesis and pathogenesis of various diseases. Third, each pro-hormone contains multiple processing sites (mono- and dibasic cleavage sites, amidation sites and consensus sequences for seryl phosphorylation and tyrosyl sulfation) leaving ample room for variations in the post-translational processing. The review discusses examples of cell-specific processing that appears to be functionally expedient.

Radioimmunoassay of cholecystokinin: comparison of different tracers.

We have compared the binding of cholecystokinin (CCK) antibodies with different sequence-specificities to Bolton-Hunter labeled CCK-33 (125I-BH-CCK-33), CCK-8 (125I-BH-CCK-8) and chloramine-T iodinated gastrin-17 (125I-gastrin-17). The antibody binding was expressed as the final antiserum dilution ('titer') and the effective equilibrium constant of the binding (Ko eff). Antibodies specific for the C- or the N-terminal sequence of CCK-8 all bound well to 125I-BH-CCK-8. In contrast, some of the antibodies directed against the common C-terminus of CCK and gastrin displayed remarkably low binding of 125I-gastrin-17 or 125I-BH-CCK-33, whereas all antisera specific for the N-terminal or midsequence of CCK-33 bound 125I-BH-CCK-33 well. The lower binding of 125I-BH-CCK-33 to some C-terminal antibodies raised against gastrin may be due to a C-terminal conformation of CCK-33 different from that of gastrin. In accord with the high specific radioactivity of 125I-BH-CCK-8, the best sensitivity of CCK radioimmunoassays was obtained with the CCK-8 tracer.

The molecular nature of cholecystokinin in the feline pancreas and related nervous structures.

Nerve terminals in pancreatic islets and ganglia containing cholecystokinin (CCK)/gastrin-like peptides are particularly abundant in the cat. In order to elucidate the possible origin and molecular nature of the peptides in these nerves, extracts of the feline pancreas, vagus, sympathetic trunk, and celiac-superior mesenteric ganglion were examined by gel chromatography monitored by sequence-specific radioimmunoassays. Small amounts of CCK-33 and CCK-8 were present in the pancreatic terminals. In the vagus and the sympathetic trunk, CCK, mainly as CCK-8, occurred in concentrations of 3.5 and 3.7 pmol/g. The celiac-superior mesenteric ganglion contained 40 pmol CCK/g distributed in five forms, including a predominant CCK-8-like component and a component eluting like CCK-4. Gastrins were not detected in the nervous structures. The results suggest that the celiac-superior mesenteric ganglia, the vagal nerves and the sympathetic trunks all may contribute to the CCK nerve terminals in the feline pancreas.

Plasma concentrations of regulatory peptides in obesity following modified sham feeding (MSF) and a liquid test meal.

Plasma concentrations of regulatory peptides were monitored in groups of obese and normal-weight subjects following modified sham feeding and a liquid fatty meal. Following modified sham feeding a significant increase in immunoreactive cholecystokinin (CCK) in plasma was recorded in both groups. In the obese subjects, however, the concentrations following sham feeding were significantly lower than in normal-weight subjects, and the initial part of the response was negative. Basal and modified sham feeding stimulated immunoreactive pancreatic polypeptide (PP) concentrations in plasma did not differ between the groups. After the liquid fatty meal plasma CCK concentrations increased similarly in both groups. In contrast immunoreactive neurotensin and somatostatin concentrations following the meal were lower in the obese group, and a changed concentration-time pattern for somatostatin was observed in the obese group. Postprandial concentrations of PP and immunoreactive gastrin were not different in the groups. The results indicate that the plasma concentration patterns of CCK, somatostatin and NT are disarranged in obesity. The changes may promote rapid propulsion and absorption of ingested food, and facilitate deposition of fat in adipose tissue in obesity and thus may be of pathophysiological importance.

Plasma cholecystokinin concentrations in patients with advanced chronic pancreatitis.

Plasma concentrations of cholecystokinin (CCK) have been reported to be elevated in patients with chronic pancreatitis. The elevations are suggested to be due to increased release of CCK from the upper small intestine secondary to the absence of protease activity (trypsin and chymotrypsin) in the intestinal lumen. We have studied plasma CCK levels before and after liquid as well as solid meals in eight patients with pancreatic insufficiency due to advanced chronic pancreatitis and in eight healthy controls. CCK concentrations were measured with a sensitive and specific radioimmunoassay using an antibody directed against the sulfated tyrosyl region of CCK. No differences in basal or maximal postprandial plasma CCK levels between patients and controls were observed. In the liquid meal study, basal CCK concentrations in patients and controls were 2.2 +/- 0.7 and 2.5 +/- 0.4 pM, respectively, with maximal postprandial concentrations of 9.6 +/- 2.2 and 11.2 +/- 1.4 pM. In the solid meal study, basal CCK concentrations in patients and controls were 2.5 +/- 0.6 and 2.6 +/- 0.4 pM, respectively, with maximal postprandial concentrations of 9.4 +/- 1.6 and 8.6 +/- 1.4 pM. The only difference observed was a significantly longer time interval to maximal plasma CCK levels in patients as compared with controls after the liquid meal. Two patients with no detectable trypsin activity in the small intestinal lumen during a Lundh test meal had basal CCK levels of 1.3 and 1.8 pM. Thus, the present study does not support the hypothesis that trypsin is involved in the regulation of CCK release.(ABSTRACT TRUNCATED AT 250 WORDS)

Concentrations of secretin and CCK in plasma and pancreatico-biliary secretion in response to intraduodenal acid and fat.

To study the effect of emulsified oleic acid on pancreatic secretion and concentrations of secretin and cholecystokinin (CCK) in plasma, eight normal subjects received three sets of duodenal perfusates containing peptone pH 6.0 or pH 2.7, with and without 20 mM oleic acid. Pancreatic secretion was measured by an indicator dilution technique. At pH 6.0, peptone and oleic acid was about as effective as peptone pH 2.7 in stimulating secretin release. However, oleic acid in addition produced a three-fold increase in plasma CCK and was five times as effective as pH 2.7 in stimulating duodenal flow. Also, at pH 2.7, oleic acid augmented pancreatic secretion and concentrations of CCK and secretin in plasma. Duodenal output of amylase and bile salts was independent of the pH of infusate. Low pH alone was a very weak stimulant of CCK release and did not stimulate output of amylase and bile. Emulsified oleic acid is a potent releaser of secretin and CCK and augments the acid-induced pancreatic secretion.

Pancreatic polyamine concentrations and cholecystokinin plasma levels in rats after feeding raw or heat-inactivated soybean flour.

We investigated the trophic effect on the pancreas of male Wistar rats fed up to 20 days with either raw soybean flour (RSF) containing an active trypsin inhibitor or heat-inactivated soybean flour (HSF). The concentrations of the polyamines putrescine, spermidine, and spermine in the pancreas as well as cholecystokinin (CCK) concentrations in arterial and portal vein plasma were measured. Plasma CCK concentrations were measured by a sensitive radioimmunoassay specific for the sulfated region of CCK, whereas polyamine concentrations are determined by reversed phase high-performance liquid chromatography. The levels of CCK in both arterial and portal vein plasma were significantly higher in RSF- compared with HSF-fed rats, the concentration in the portal vein being twice as high compared with the aorta. A significant increase in pancreatic weight and protein content was positively correlated to an increase in putrescine and spermidine in the pancreas of RSF-fed rats compared with HSF-fed controls, whereas the spermine content did not differ between the two groups. The pancreatic DNA content in RSF-fed rats was significantly above control values of day 20 only. These data support the hypothesis that the trophic effect of soybean trypsin inhibitor on the pancreas is mediated by CCK and that polyamines might play an important role in CCK-induced pancreatic growth.

The molecular nature of cholecystokinin in human plasma.

Using a radioimmunoassay specific for the bioactive, tyrosine-sulfated sequence of cholecystokinin (CCK) we have studied the molecular nature of CCK in plasma from normal human subjects. CCK was extracted from postprandial plasma by Sep-Pak cartridges prior to Sephadex G-50 gel chromatography. Four CCK components eluting like CCK-58, CCK-33, CCK-22, and CCK-8, were identified in all samples. Of these, CCK-33- and CCK-8-like peptides predominated. The heterogeneity of circulating CCK emphasizes the importance of plasma assays that measure all bioactive forms of CCK.

Frequency of suicidal thought and self-destructive behavior among females.

The focus of the present investigation was to examine the importance of a control group in suicide research and to develop an instrument to distinguish between levels of suicidal thought among subjects who had a history of attempted suicide and among a comparison group of nonsuicidal individuals. The sample was comprised of female university students ranging in age from 18 to 25 years. A 31-item questionnaire designed by the investigator was given to 199 students, 20 of whom were found to have histories of one or more previous suicide attempts. The remaining 179 nonsuicidal subjects were divided into two categories based on the frequency of expressed suicidal thought. Fifty individuals were randomly selected from each of these two groups. The three groups (individuals who had attempted suicide, individuals who had not attempted suicide but who thought about suicide on a frequent basis, and individuals who had not attempted suicide and who thought about suicide on an infrequent basis) were compared on the variables of motivation for suicidal thoughts, history of self-destructive behaviors, probability of a future suicide attempt, and age of first suicidal considerations. A chi-square analysis was performed on each of these items in order to assess the extent to which the items discriminated among the three comparison groups. The differences among the three groups on each of the items were found to be statistically significant at less than the .01 level. The results of the study have provided support for the necessity of a distinction between groups within a nonsuicidal comparison population and for the suggestion that there may be a quantitative relationship between the frequency of suicidal thought and the likelihood of attempted suicide.

The impact of social change on child mental health in Eastern Europe.

The transition of the Eastern European countries in the past 12 years from totalitarian, communist societies to democratic societies has had a broad impact on children's mental health, both positively and negatively. This transition has not been without economic difficulties. All countries in the region experienced a significant deterioration of output that has affected the availability of commodities and services. Although recovery has been achieved in some Eastern European countries and is in progress in other countries, reversal of the cutbacks in allocations to necessary services that protect children and families may take longer to achieve. Movement toward a free market economy and greater individualism also has focused attention away from the role of society to protect and provide care for its citizens, especially the most vulnerable. On the positive side, mental health, as a concept for children and adults, comes to be appreciated only in a society that values and safeguards individual rights. Democratic process within the family, the depoliticization of mental illness, the passage of laws assuring basic children's rights, services for and public awareness about children abuse, reforms in education, the proliferation of mental health clinics and support centers, and the resumption of training of mental health professionals all set a tone to first consider, then assure, the positive development of children's mental health.

The unique specificity of antibodies in modern radioimmunochemistry--an essay on assays.

The gradual recognition and exploitation of the specificity of antibodies in peptide radioimmunoassays (RIA) during the last three decades are reviewed. From the old fashioned RIA techniques of the sixties through sequence-specific RIA libraries of the seventies to residue-specific immunoassays of the eighties, the RIA technique has to an increasing degree been based on the ability to select strictly monospecific antibodies in high-titered polyclonal antisera. High-avidity monospecific antibodies from polyclonal antisera provide the RIA technology of to-day with unrivalled specificity. This specificity again has increased the utility of RIA as a tool in basic as well as clinical biochemistry.

Child and adolescent mental health emergency services in Eastern European former Iron Curtain countries.

This paper describes the evolution of child and adolescent mental health emergency services in Eastern European countries over the past decade since the dissolution of the Iron Curtain. The process of helping countries to organize services, as facilitated by the authors through their training and mentoring of Eastern European mental health professionals, organized by the Children's Mental Health Alliance Foundation, with funding from the Soros Foundation, is described. This paper is a prelude to reports from six Eastern European countries which describe in more detail how child and adolescent mental health emergencies are evaluated and treated locally.

Evaluation of a radioimmunoassay for cholecystokinin in human plasma.

A sensitive and specific radioimmunoassay for cholecystokinin (CCK) in human plasma was developed using an antiserum specific for sequence 26-29 of CCK-33 and 125I-Bolton-Hunter labelled sulphated CCK-8 as tracer. Plasma was extracted in 96% ethanol before assay. The detection limit of the assay was 0.3 pmol/l. CCK-33 and CCK-8 were stable in plasma at 0 degree C for at least 3 h, but CCK-8 was degraded at 21 degrees C. The trypsin inhibitor, aprotinin, did not affect the degradation of CCK-8, while the aminopeptidase inhibitor, bestatin, had a significant inhibitory effect. The basal plasma concentration of CCK in 44 normal subjects was 1.6 +/- 0.2 pmol/l, ranging from undetectable (less than 0.3 pmol/l) to 4.4 pmol/l. After the ingestion of a mixed meal in seven normal subjects, concentrations of plasma CCK rose from 2.0 +/- 0.2 to 7.4 +/- 0.7 pmol/l. Diurnal registration in nine people showed similar increments after each meal. The validity of the assay was further substantiated by a strong correlation between CCK measurements of identical samples with other CCK specific antisera.

Cholecystokinin in pig plasma: release of components devoid of a bioactive COOH-terminus.

Using radioimmunoassays specific for different sequences of cholecystokinin (CCK), we studied the intestinal release of CCK in pigs. After stimulation by intraduodenal infusion of HCl, plasma CCK concentrations, measured with an antiserum specific for the sulfated, bioactive sequence of CCK, increased from 1.4 +/- 0.7 to 42.7 +/- 11.7 pM in portal plasma and from 0.5 +/- 0.3 to 12.3 +/- 1.5 pM in peripheral plasma. The concentrations measured with an antiserum specific for the NH2-terminal sequence 5-10 of CCK-33 were considerably higher, increasing from 64 +/- 17 to 139 +/- 14 pM in portal plasma and from 69 +/- 7 to 102 +/- 9 pM in peripheral plasma. Chromatography suggested that the NH2-terminal immunoreactivity consisted of large CCK fragments devoid of the bioactive COOH-terminal octapeptide, i.e., desocta and/or desnona CCK-58, CCK-39, and CCK-33. The bioactive forms in both portal and peripheral plasma comprised CCK-58-, CCK-33-, CCK-22-, CCK-12-, and CCK-8-like forms. Generally, the CCK-22-like component predominanated, but although CCK-8 was more abundant than CCK-33 in portal plasma, these forms occurred in equal amounts in peripheral plasma. Large amounts of NH2-terminal immunoreactivity were also found in the venous effluent of the isolated perfused duodenum after stimulation with gastrin-releasing peptide; the venous perfusate contained mainly CCK-22- and CCK-8-like material, which together constituted greater than 80% of the bioactive CCK components. Both duodenal and jejunal mucosa contained components resembling NH2-terminal fragments as well as large amounts of intact CCK-58 and CCK-33.(ABSTRACT TRUNCATED AT 250 WORDS)

Fat and pancreatic secretion.

In 10 healthy volunteers we investigated the effects of intraduodenal oleic acid at various concentrations (0-40 mM) and at various degrees of emulsification on pancreaticobiliary secretion and the release of secretin and cholecystokinin (CCK) into plasma. We found that the release of the two hormones was directly related to the dose of fat and to the degree of emulsification. The threshold of CCK release (and amylase output) was low in comparison with the threshold for secretin release (and bicarbonate or volume output). When the degree of emulsification of the fat was increased, no simple relation was observed between hormone levels and pancreatic exocrine secretion. The output of bile salts was identical at various fat concentrations. We conclude that both secretin and CCK are dose-dependently released by emulsions of oleic acid in normal man and that the thresholds for release are probably different.