Molecular forms of islet amyloid polypeptide (IAPP/amylin) in four mammals

Using reverse-phase high performance liquid chromatography combined with radioimmunoassays for human and rat/mouse islet amyloid polypeptide (IAPP), we identified molecular forms of IAPPs in pancreata of four mammals including species in which islet amyloid deposition occurs (human and cat) and those in which amyloid deposition does not occur (rat and mouse). In human pancreas, IAPP (1-37) was the major molecular form, and IAPP (17-37), IAPP (24-37) and four IAPP-immunoreactive peptides were detected as minor components. In rat, mouse and cat pancreata, IAPP (1-37) and IAPP (19-37) were identified with the latter being the major molecular form. Major processing takes place at a single arginine residue at position 18 of rat/mouse and cat IAPPs, but not at the histidine at position 18 of human IAPP, indicating that arginine could yield different processing of IAPP between the 3 species and human. Different processing of IAPP by species suggests that processing of IAPP in pancreas is not responsible for islet amyloid formation. Identification of molecular forms of IAPP is helpful in elucidating the physiological function of the IAPP molecule and in determining the type of system regulating biosynthesis and catabolism of the peptide.

Regulation of Growth Hormone-releasing Hormone Gene Expression and Secretion

Growth hormone (GH)-releasing hormone (GRH) is a stimulatory hypothalamic hypophysiotropic hormone which, along with an inhibitory peptide, somatostatin (SRIF), regulates the synthesis and secretion of GH in anterior pituitary somatotrophs. Although GHRH genes in several species have been characterized, there is only a limited understanding of the neural and hormonal mechanisms regulating GRH biosynthesis and secretion. Recent progress in PCR and in situ hybridization techniques as well as hGRF-transgenic animal models have provided an opportunity to study the regulation of GRH gene expression and secretion as well as its metabolism. The difference in 5'-untranslated sequences in both mouse and rat GRH cDNAs from hypothalamus and placenta has also suggested tissue-specific regulation of the GRH gene. GH excess has been shown to result in a decrease in hypothalamic GRH mRNA as well as GRH content and secretion while GH deficiency caused by hypophysectomy, hypothyroidism or genetic dwarfism causes an increase in GRH mRNA levels as tested by Northern blot analysis or in situ hybridization. Treatment of animals with GH or SRIF inhibits the increased GRH gene expression in the hypothalamic arcuate nucleus. Double immunocytochemistry for hypothalamic GRH and SRIF has shown both axo-perikaryal and axo-axonal connections between GRH- and SRIF- containing neurons. SRIF binding and GH receptor mRNA are demonstrated on a subpopulation of GRH-containing neurons in the hypothalamic arcuate nucleus. It is therefore possible to conclude that regulation of GRH gene expression, primarily related to inhibitory feedback effects of GH and IGFs on hypothalamic GRH gene expression, is mediated at least in part by SRIF or GH. The single transcript of the human GRH gene encodes a 108 amino acid precursor, prepro-hGRH, which is cleaved into the signal peptide and the remaining peptide, pro-hGRH. The latter is further processed to yield two equipotent forms of the releasing hormone, hGRH(1-44)-NH2, hGRH(1-40)-OH, and a carboxyl-terminal peptide (hGCTP) of unknown function. Studies in transgenic mice demonstrate the processing of hGRH-prohormone into both mature forms of hGRH and hGCTP, and provide evidence that hGRH(1-40)-OH is derived from hGRH(1-44)-NH2.(ABSTRACT TRUNCATED AT 400 WORDS)

[A case of bilateral Bochdalek hernia in an adult]

A 71-year-old male was found to have bilateral posteromedial masses on routine roentgenogram during admission for treatment of traffic accident related injuries. These masses were initially considered to be posterior mediastinal tumors, however, CT scan demonstrated a left diaphragmatic defect and the adipose nature of the bilateral masses (CT number: left -29, right -132). MRI also demonstrated a large amount of fat accumulation in the abdomen. CT scan and MRI are therefore very useful for the diagnosis of Bochdalek hernia in adults.

Identification and characterization of islet amyloid polypeptide in mammalian gastrointestinal tract

We identified and determined the content and molecular form of islet amyloid polypeptide (IAPP/amylin) in the gastrointestinal (GI) tract of human, rat, mouse and cat. IAPP was isolated by anti- IAPP- IgG immunoaffinity chromatography and reverse-phase high performance liquid chromatography coupled with radioimmunoassays for human and rat/mouse IAPPs. Human IAPP [1-37], [17-37] and [24-37] were identified in human stomach with IAPP [1-37] being the major molecular form. In the GI tract of rat, mouse and cat, IAPP [1-37] and IAPP [19-37] were identified with the latter being the major molecular form. IAPP is present from stomach to colon with the highest concentration being observed in pyloric antrum of stomach. IAPP content in rat antrum fell to 69% of control after 4 days of fasting, with the molar ratio of IAPP [19-37] to IAPP [1-37] increasing from 1.4 in controls to 2.9 in fasted rats. Identification of IAPP and characteristic morphology of IAPP- cells in the GI tract indicate a possible biological function of IAPP as a gastrointestinal peptide.

Interleukin-1 (IL-1) stimulates the release of corticotropin-releasing factor (CRF) from superfused rat hypothalamo-neurohypophyseal complexes (HNC) independently of the histaminergic mechanism

We demonstrated previously that interleukin-1 (IL-1) (recombinant human IL-1 alpha and -1 beta) stimulated the release of corticotropin-releasing factor (CRF) from the superfused rat hypothalamo-neurohypophyseal complex (HNC), independently of the cholinergic system. In the present study we studied the effects of IL-1 on the release of CRF not only from the HNC but also from the isolated hypothalamus of rats in a superfusion system to define the origin of measured CRF and the site of IL-1 action. We also studied the possible involvement of the histaminergic system in the mediation of the stimulation by IL-1. An increase in CRF was elicited from the HNC and the isolated hypothalamus in a dose-dependent manner by human recombinant IL-1 beta in concentrations of 0.1-10 nM with similar time courses. Histamine in concentrations of 1-100 nM also elicited qualitatively similar increases of CRF from these two types of explants. The increases in CRF release from the HNC induced by 10 nM of histamine were completely suppressed in the combined presence of pyrilamine (10 microM) and cimetidine (10 microM), an H1 and an H2 receptor antagonist, respectively. On the other hand, the increase in CRF release induced by 10 nM IL-1 beta was not affected by the combination of these two antagonists. These results indicate that IL-1 stimulates CRF release from the median eminence through an action on the hypothalamus, and that the stimulatory effect of IL-1 is probably independent of the histaminergic system.

Islet amyloid polypeptide in insulinoma and in the islets of the pancreas of non-diabetic and diabetic subjects

Amyloid deposition is a common pathological feature in insulinoma and in the islets of the pancreas in type-2 diabetic patients. The present immunohistochemical study revealed that normal B-cells, insulinoma, and amyloid deposits in insulinoma and diabetic pancreatic islets were commonly immunoreactive with antiserum to C-terminal synthetic tetradecapeptide of human islet amyloid polypeptide (IAPP) (24-37). Amyloid fibrils in insulinoma were also positive to IAPP by immunoelectron microscopy. A high level of IAPP was detected in the plasma and tissue of a insulinoma patient by radioimmunoassay suggesting that amyloid deposition in insulinoma is due to overproduction of IAPP. Amyloid deposits immunoreactive to IAPP were also seen in all diabetic pancreatic islets, but in no non-diabetic islets. There was much amyloid deposition in the islets of severe diabetics, whose B-cells demonstrated decreased immunoreactivities for IAPP and insulin. The IAPP content of the pancreas was 649.0 and 847.7 pg/mg wet weight in each of two diabetic patients, and 1034.6 and 1447.7 pg/mg wet weight in two non-diabetic patients. The present study revealed that IAPP is a bioactive peptide secreted from islet B-cells and are amyloidogenic peptide concerned in diabetogenensis and/or the progression of type-2 diabetes mellitus.

Interleukin-1 (IL-1) stimulates arginine vasopressin (AVP) release from superfused rat hypothalamo-neurohypophyseal complexes independently of cholinergic mechanism

We studied whether interleukin-1 (IL-1) affects the release of arginine vasopressin (AVP) from the superfused hypothalamo-neurohypophyseal complex (HNC) of rats. Involvement of the cholinergic system in the mediation of IL-1 on AVP release from HNC was also examined. Both human recombinant IL-1 alpha and -1 beta elicited a rapid increase of AVP from HNC in a dose-dependent manner at concentrations ranging from 0.1 to 10 nM. However, neither IL-1 alpha nor -1 beta at concentrations of 100 nM increased AVP, and even suppressed the stimulatory effect of 10 nM IL-1 alpha and -1 beta added later. Acetylcholine at concentrations of 1 to 100 nM caused a dose-dependent, rapid increase in AVP, whereas AVP release induced by 10 nM acetylcholine was completely suppressed by the combined presence of 10 microM hexamethonium, a nicotinic receptor antagonist, and 50 microM atropine, a muscarinic receptor antagonist. On the other hand, AVP release induced by 10 nM IL-1 alpha and -1 beta was not affected by the combination of the two antagonists. These results suggest that both IL-1 alpha and -1 beta may stimulate AVP release by acting directly on the hypothalamo-neurohypophyseal system, and that the stimulatory effect of IL-1 on AVP release may be independent of the cholinergic system.

Stimulation by interleukin-1 (IL-1) of the release of rat corticotropin-releasing factor (CRF), which is independent of the cholinergic mechanism, from superfused rat hypothalamo-neurohypophysial complexes

The effects of interleukin-1 (IL-1) and interferon-gamma (Ifn-gamma) on the release of corticotropin-releasing factor (CRF) from superfused hypothalamo-neurohypophysial complexes (HNC) of rats were examined in the present study. In this in vitro system, the release of CRF from HNC was not affected by any dose of human recombinant Ifn-gamma tested (0.1, 1 and 10 nM). In contrast, a rapid increase of CRF from HNC was elicited in a dose-dependent manner by human recombinant IL-1 alpha and -1 beta in concentrations of 0.1-10 nM. The involvement of the cholinergic system in the mediation of the stimulatory effect of IL-1 on CRF release was evaluated. Acetylcholine in concentrations of 1-100 nM also elicited a rapid increase of CRF. The increase in CRF release induced by 10 nM of acetylcholine was completely suppressed in the presence of both hexamethonium (10 microM) and atropine (50 microM), a nicotinic and a muscarinic receptor antagonist, respectively. On the other hand, the increase in CRF release induced by 10 nM IL-1 alpha or -1 beta was not affected by these two antagonists. These results indicate that IL-1 stimulates CRF release through an action on the hypothalamo-neurohypophysial system, most likely on the hypothalamus, and that the stimulatory effect of IL-1 is probably independent of the cholinergic system.

Distribution and characterization of immunoreactive porcine C-type natriuretic peptide

C-type natriuretic peptide (CNP) is a new member of the natriuretic peptide family recently identified in porcine brain (1). We raised an antiserum against porcine CNP and set up a radioimmunoassay (RIA) for CNP. Using this RIA system, distribution of immunoreactive (ir-) CNP in porcine tissue was measured and compared with that of ir-atrial natriuretic peptide (ANP) and ir-brain natriuretic peptide (BNP). Tissue concentration of ir-CNP in brain was the highest of the three natriuretic peptides at about 0.79 pmol/g wet wt. CNP was present in medulla-pons in high concentration, with a significant concentration detected in cerebellum. In contrast, ir-CNP was not detected in peripheral tissue, including heart, in a significant concentration. These data demonstrated sharp contrasts in the distribution of the three natriuretic peptides, suggesting that CNP is a natriuretic peptide functioning in the central nervous system.

Use of inactive beta-D-galactosidase for elimination of interference by anti-beta-D-galactosidase antibodies in immune complex transfer enzyme immunoassay for anti-thyroglobulin IgG in serum using beta-D-galactosidase from Escherichia coli as label

A novel enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-thyroglobulin IgG using beta-D-galactosidase from Escherichia coli as label was reported previously. This immunoassay was highly sensitive in demonstrating anti-thyroglobulin IgG not only in all patients with Graves' disease and chronic thyroiditis but also in a large proportion of healthy subjects. However, the detection of anti-thyroglobulin IgG at low levels in some serum samples was difficult, probably due to the presence of anti-beta-D-galactosidase antibodies. In the present study, the use of inactive beta-D-galactosidase was tested for elimination of interference by anti-beta-D-galactosidase antibodies. Preincubation of serum samples with excess of inactive beta-D-galactosidase resulted in sufficiently low backgrounds to detect low levels of anti-thyroglobulin IgG with little effect on the dose-response of anti-thyroglobulin IgG. As a result, it was revealed that anti-thyroglobulin IgG was present in almost all healthy subjects as well as all patients with Graves' disease and chronic thyroiditis.

Isolation and identification of islet amyloid polypeptide in normal human pancreas

To identify islet amyloid polypeptide (IAPP) present in normal human pancreas, we isolated the peptide from a soluble peptide fraction of amyloid deposit-free pancreata of two non-diabetic patients by using reverse-phase high performance liquid chromatography coupled with a radioimmunoassay specific for human IAPP. IAPP(1-37) and IAPP(17-37) were isolated and their complete amino acid sequences were determined up to the C-terminus. Identification of IAPP in normal human pancreas suggests the possible biological function of IAPP as a novel pancreatic hormone in humans.

Islet amyloid polypeptide (IAPP) in the gastrointestinal tract and pancreas of man and rat

An immunohistochemical study for islet amyloid polypeptide (IAPP) was made on the gastrointestinal (GI) tract and pancreas of man and rat, using antisera raised against a synthetic peptide of C-terminal human IAPP (24-37) and a synthetic peptide of rat IAPP (18-37). A large number of IAPP-immunoreactive cells were found in the pyloric antrum, and a small number in the body of the stomach in both man and rat. Cytoplasmic processes extended out from the bipolar peripheral region of the immunoreactive cells, rather like neuronal processes, and some appeared to make contact with other immunoreactive cells. In addition, small numbers of immunoreactive cells were also seen in the duodenum and rectum, whereas they were absent from the jejunum, ileum and large intestine. An examination was made for evidence of colocalization of IAPP-immunoreactive material with material immunoreactive for gastrin, somatostatin, vasoactive intestinal polypeptide, pancreatic polypeptide, insulin, and glucagon, but none was found. IAPP-immunoreactive cells were also found in the pancreas of non-diabetic and non-insulin-dependent diabetic patients, but they were completely absent from a patient with insulin-dependent diabetes mellitus despite the presence of IAPP in the plasma. The results of these studies suggest that the peptide may have a biological role in situ in the GI tract and, in addition to the pancreas, may be a possible source of plasma IAPP.

Characterization of magnesium dependent adenosine 5'-triphosphatase in bovine brain cytoplasmic dynein

The Mg2(+)-ATPase activity of cytoplasmic dynein isolated from bovine brain was examined in the absence of microtubules. Cytoplasmic dynein in the absence of microtubules showed Mg2(+)-ATPase activity with two distinct Km values, 272 microM and 11.8 microM. The initial burst of Pi liberation, which was due to occurrence of slow decomposition of reaction intermediate, was 0.67 mol per mol of cytoplasmic dynein. These results indicate that Mg2(+)-ATPase reaction of cytoplasmic dynein in the absence of microtubules is similar to that of flagellar and ciliary dyneins which have been shown not to hydrolyze ATP via a single pathway.

A case of Graves' disease associated with Klinefelter's syndrome

Graves' disease was found in a 41-year-old, married male patient with Klinefelter's syndrome. The patient began having finger tremor 5 years previously, and developed palpitation and weight loss 3 months prior to examination. He had a diffuse goiter, exophthalmos, and atrial fibrillation. Plasma levels of T3, T4 and free T4 were 2.8 ng/ml, 16.6 micrograms/dl and 4.5 ng/dl respectively. [123I] uptake was 53%, and TSH receptor antibody was 75%. Although he had no gynecomastia, his general physical appearance was that of typical eunuchoism. Chromosome studies showed a karyotype of 47,XXY. A diagnosis of Graves' disease associated with Klinefelter's syndrome was made.

Gallbladder function and plasma cholecystokinin levels in diabetes mellitus

Contractile motility of the gallbladder and plasma cholecystokinin (CCK) responses to egg yolk administration were studied in 28 diabetic patients and 12 normal subjects. The patients were divided into three groups: group A (n = 10) had no diabetic neuropathy, group B (n = 8) had diabetic neuropathy with little autonomic neuropathy, and group C (n = 10) had advanced diabetic autonomic neuropathy. In groups A and B, contraction of the gallbladder after egg yolk administration was not significantly different from that of normal subjects. However, in group C, gallbladder contraction was impaired (p less than 0.01-0.05), compared with that in normal subjects. After the administration of egg yolk, plasma CCK levels increased from 12.4 +/- 4.5 to 25.3 +/- 12.0 pg/ml in normal subjects. In group A, plasma CCK levels increased from 17.9 +/- 8.5 to 39.3 +/- 14.2 pg/ml, and in group B, from 15.2 +/- 5.1 to 38.3 +/- 9.9 pg/ml. In group C, however, plasma CCK levels increased from 33.1 +/- 13.9 to 72.4 +/- 31.9 pg/ml, and fasting CCK levels and responses to egg yolk were significantly higher than those in normal subjects and in groups A and B (p less than 0.01-0.05). In conclusion, this study showed that in a group of diabetic patients with autonomic neuropathy, gallbladder contraction was impaired despite the exaggerated CCK response to egg yolk.

Kinetic properties and isozyme composition of myosin in the mdx mutant mouse

Skeletal muscle fibers from muscular dystrophic mice (C57BL/10-mdx) 1-4 months of age show elevated free Ca2+ concentrations both at resting and stimulated states, although contractility of adult (2-12 months old) mouse is similar to that of normal mouse. To evaluate the sensitivity of the contractile system of adult mdx mouse muscle to elevated free Ca2+ concentration, Mg2(+)-adenosine triphosphatase (ATPase) activity was examined using myosin, myosin B, and reconstituted actomyosin. Myosin Mg2(+)-ATPase activity of the mdx mouse was significantly higher than that of the normal mouse. Myosin B ATPase activity of the mdx mouse was also higher than that of normal mouse in free Ca2+ concentrations between 10(-9) and 10(-5) M, though there was no difference in the Ca2+ concentration required for half maximal activation of ATPase activity, 2 x 10(-7) M. Polymerized actin (FA) isolated from normal and mdx mice activated rabbit myosin Mg2(+)-ATPase identically, while activation of Mg2(+)-ATPase in mdx myosin by rabbit FA was significantly lower than that in normal mouse myosin. Rapid Pi liberation by Mg2(+)-ATPase in mdx mouse myosin was about half that of normal mouse myosin, being consistent with low activation of Mg2(+)-ATPase activity by rabbit FA. Polyacrylamide gel electrophoresis in the presence of pyrophosphate showed that myosin molecules of mdx and normal mice were both composed of three isozymes, although the fast migrating myosin isozyme (M1) was decreased while the slow migrating band (M3) was increased in mdx myosin. Subunit composition of myosin analyzed by polyacrylamide gel electrophoresis in the presence of SDS showed that the content of the smallest light chain (LC3) in mdx myosin was lower than that of normal mouse myosin, which agreed with findings that mdx myosin contained less M1 isozyme than normal myosin. These results indicated that the lowered response of mdx muscle fibers to elevated Ca2+ concentration can be attributed to the isozyme composition of myosin in mdx mouse.

[A case of hemiballism successfully treated by sulpiride, caused by lesions of the striatum]

A case of hemiballism caused by infarction in the left striatum on MRI was reported. Hemiballism is generally associated with lesions in the subthalamic nucleus. However, hemiballism occasionally occurs as a result of lesions outside the subthalamic nucleus. Hemiballism is a benign condition with spontaneous recovery in most cases, but hemiballism caused by lesions outside the subthalamic nucleus is reported to tend to persist for a long term. In our case without involvement of the subthalamic nucleus, hemiballism so far continued for three months since the onset. Successful pharmacological treatments of ballism with haloperidol or phenothiazines were well known. In our case, the treatments of ballism with these drugs were unsuccessful due to drug-induced hepatic dysfunction. Instead of these drugs, ballism was improved by administration of 150 mg of sulpiride per day with no side effects. Sulpiride may be beneficial for persistent hemiballism caused by the extra subthalamic lesions.

Regional distribution and molecular forms of rat islet amyloid polypeptide

Using a highly sensitive and specific radioimmunoassay (RIA) for rat islet amyloid polypeptide (IAPP), we clarified regional distribution and molecular forms of rat IAPP. IAPP[1-37] and IAPP[19-37] were identified in normal rat pancreas by sequence analyses IAPP[19-37], accounting for 57% of IAPP-immunoreactivity in rat pancreas, is a major molecular form of rat IAPP moiety. In human, however, IAPP[1-37] is the major component, with IAPP[17-37] composing as little as 2-6% of IAPP-immunoreactivity in pancreas. This indicates that processing of IAPP in pancreas differs in species. A large amount of IAPP (328.5 +/- 25.0 pmol/g wet weight) was found in rat pancreas and the peptide was also detected in pyloric antrum of the stomach, duodenum, jejunum, ileum, and colon at 0.1-0.8% of the level of pancreas. It was not detected in central nervous system. The content of rat IAPP in pancreas fell to 54% of control after 4 day fasting. The distribution of IAPP suggests its possible endocrine or paracrine function in pancreas and gastrointestinal tract.

Islet amyloid polypeptide, a novel pancreatic peptide, is a circulating hormone secreted under glucose stimulation

Islet amyloid polypeptide (IAPP) was identified in human plasma using immunoaffinity chromatography, gel filtration and reverse- phase high performance liquid chromatography coupled with radioimmunoassay specific for the peptide. IAPP[1-37], IAPP[17-37], and other two IAPP- related peptides which were putative pro-IAPPs or different processing products of IAPP, were isolated. All of these IAPPs were also found in human pancreatic extract, indicating that they were secreted from B cell secretory granules into the circulation. IAPP[1-37] is a major molecular form of IAPP in the pancreas, but it accounted for 31% of immunoreactive IAPP in the plasma. Plasma concentration of IAPP in normal individuals increased to 3.0 times the basal level in response to oral administration of 75 g glucose. This study indicated that IAPP is a circulating hormone secreted under glucose stimulation.

Islet amyloid polypeptide response to glucose, insulin, and somatostatin analogue administration

We determined islet amyloid polypeptide (IAPP) response in plasma to oral and intravenous glucose administration and intravenous insulin injection in nondiabetic subjects. Moreover, we studied the effect of somatostatin analogue SMS 201-995 on glucose-induced IAPP secretion in nondiabetic subjects. Plasma IAPP concentration was determined by radioimmunoassay. Oral administration of 75 g glucose (n = 8) significantly increased plasma IAPP levels from 4.5 +/- 0.7 to 14.0 +/- 1.7 pM (P less than 0.01) 60 min after administration. Intravenous administration of 10 g glucose (n = 7) also caused a significant increase in plasma IAPP from 5.0 +/- 0.4 to 11.6 +/- 0.9 pM (P less than 0.01) 5 min after injection. Plasma IAPP significantly decreased from 5.1 +/- 0.4 to 2.9 +/- 0.4 pM (P less than 0.01) 60 min after intravenous insulin injection (n = 8). Pretreatment with SMS 201-995 completely abolished IAPP and insulin secretion to intravenous glucose injection. A significant correlation was found between plasma IAPP and insulin levels in oral and intravenous glucose administration and between plasma IAPP and C-peptide levels during insulin-induced hypoglycemia. These results suggest that IAPP is cosecreted with insulin in response to a glucose load and secretion of IAPP is inhibited by hypoglycemia and somatostatin. IAPP may serve as a novel pancreatic hormone to control carbohydrate metabolism.

Chicken atrial natriuretic peptide (chANP) and its secretion

An immunohistochemical study using antiserum raised against synthetic chicken natriuretic polypeptide was used to investigate the distribution of this peptide in the chicken heart. Immunoreactive cells, both in the atrial and ventricular walls, were identified by electron microscopy, and electron-dense granules in the atrial and ventricular cardiocytes were revealed to be storage sites of the peptide. The electron-dense material, thought to be the peptide, was found in the sarcoplasmic reticulum, and it is suggested that a secretory pathway of the peptide through the latter to extracellular space, may be present, in addition to an exocytotic one.

Sensitive time-resolved fluorimetric immune-complex-transfer immunoassay for antithyroglobulin IgG in serum

A sensitive time-resolved fluorimetric immune-complex-transfer immunoassay for antithyroglobulin IgG in serum is described. Antithyroglobulin IgG in test serum was reacted with dinitrophenyl europium ion-labeled thyroglobulin. The complex formed of antithyroglobulin IgG and dinitrophenyl europium ion-labeled thyroglobulin was trapped onto two polystyrene balls coated with affinity-purified rabbit antidinitrophenyl bovine serum albumin IgG. The polystyrene balls were washed to eliminate nonspecific IgG in the test serum, and the complex was eluted from the polystyrene balls with dinitrophenyl-L-lysine and transferred to two polystyrene balls coated with affinity-purified rabbit antihuman IgG gamma-chain IgG. Europium ion bound to the polystyrene balls was measured by time-resolved fluorimetry. Antithyroglobulin IgG was demonstrated in all patients with Graves' disease and all patients with chronic thyroiditis. This immunoassay was more sensitive than the conventional enzyme immunoassay and less time-consuming than the previously described immune-complex-transfer enzyme immunoassays, although there were larger assay variations.

Effects of atropine, proglumide, and somatostatin analogue (SMS 201-995) on bombesin-induced gallbladder contraction and CCK secretion in humans

The effects of atropine, proglumide, and somatostatin analogue (SMS 201-995) on bombesin-induced gallbladder contraction and plasma cholecystokinin (CCK) secretion were investigated in healthy volunteers. The gallbladder size was measured by real-time ultrasonography and the plasma CCK levels by radioimmunoassay. Bombesin (5 micrograms/30 min infusion) induced gallbladder contractions that reduced the gallbladder area to 36.6 +/- 2.1% of the original area 45 min after bombesin infusion, and caused a significant increase of plasma CCK from a basal level of 10.3 +/- 1.8 pg/ml to a peak level of 42.9 +/- 8.9 pg/ml (p less than 0.01) at 20 min. Atropine (500 micrograms, im) inhibited significantly (p less than 0.01) the gallbladder contraction (maximum contractile rate, 78.7 +/- 6.4%) in response to bombesin without any change of plasma CCK secretion, whereas proglumide (800 mg/day for 3 days, per os) decreased slightly but not significantly the gallbladder contraction, and had no effect on plasma CCK secretion. On the other hand, SMS 201-995 (50 micrograms, sc) almost completely inhibited both bombesin-induced CCK secretion and gallbladder contraction (maximum contractile rate, 93.6 +/- 6.2%). These findings suggest that atropine inhibits bombesin-induced gallbladder contraction, not via suppression of CCK release, but probably by inhibiting cholinergic mechanisms, whereas somatostatin inhibits gallbladder contraction, at least in part, by the suppression of bombesin-stimulated CCK secretion.