Primary Pancreatic Secretinoma: Further Evidence Supporting Secretin as a Diarrheogenic Hormone.

OBJECTIVES: To document the existence of primary pancreatic secretinoma in patients with watery diarrhea syndrome (WDS) and achlorhydria and establish secretin as a diarrheogenic hormone. BACKGROUND: Vasoactive intestinal peptide (VIP) has been widely accepted as the main mediator of WDS. However, in 1968, Zollinger et al reported 2 female patients with pancreatic neuroendocrine tumors, WDS, and achlorhydria. During surgery on the first, a 24-year-old patient, they noticed distended duodenum filled with fluid and a dilated gallbladder containing dilute bile with high bicarbonate concentration. After excision of the tumor, WDS ceased and gastric acid secretion returned. The second, a 47-year-old, patient's metastatic tumor extract given intravenously in dogs, produced significantly increased pancreatic and biliary fluid rich in bicarbonate. They suggested a secretin-like hormone of islet cell origin explains WDS and achlorhydria. These observations, however, predated radioimmunoassay, immunohistochemical staining, and other molecular studies. METHODS: The first patient's tumor tissue was investigated for secretin and VIP. Using both immunohistochemistry and laser microdissection and pressure catapulting technique for RNA isolation and subsequent reverse transcription polymerase chain reaction, the expression levels of secretin, and VIP were measured. RESULTS: Immunoreactive secretin and its mRNA were predominantly found in the tumor tissue whereas VIP and its mRNA were scarce. CONCLUSIONS: The findings strongly support that the WDS and achlorhydria in this patient may have been caused by secretin as originally proposed in 1968 and that secretin may act as a diarrheogenic hormone.

Endocrine cells in the human common bile duct in patients with obstructive jaundice.

BACKGROUND/AIMS: There was no data about endocrine cells in the extrahepatic bile duct in secondary cholangitis due to obstructive jaundice. The aim of the present study is to investigate immunohistochemically the endocrine cell types in the lower part of the human common bile duct in biopsy samples, collected during drainage because of complete or incomplete obstruction, caused mainly by stones. We explained the presence of various hormone-producing endocrine cells in this region with the regulation of physiological and pathological processes there. METHODOLOGY: We used light and electron microscopic immunohistochemistry. RESULTS: More gastrin-positive, somatostatin-positive, secretin-positive, serotonin-positive, chromogranin- A-positive and synaptophysin-positive endocrine cells were found compared to control preparations. CONCLUSIONS: Occurrence of endocrine cells may relate to disturbed bile flow and to formation of calculi. Endocrine cell hyperplasia may be related to longstanding inflammation as in chronic cholecystitis and all secreted hormones from the described ECs can support pathologic process in the choledochus, i.e. inflammation, increased mucus secretion, fibrosis, muscle contraction, etc. We may state that various ECs (similar to those in duodenum) present in the lower part of the large bile duct and their hormones exert action on physiology (motility, secretion) and pathology (inflammation and fibrosis) in that part of the biliary tree.

Diffusion-weighted MRI of the pancreas: correlation with secretin endoscopic pancreatic function test (ePFT).

RATIONALE AND OBJECTIVES: To evaluate the correlation between apparent diffusion coefficient (ADC) values of the pancreas on diffusion-weighted imaging (DWI) and pancreatic exocrine function determined by HCO(3) concentration in the secretin endoscopic pancreatic function test (ePFT). MATERIALS AND METHODS: Mean ADC values derived from 10 different points of the pancreatic gland on DWI were reviewed in 14 patients with normal (peak HCO(3) > or = 80 mEq/L) and 14 patients with abnormal (peak HCO(3) < 80 mEq/L) ePFT results. Magnetic resonance cholangiopancreatography (MRCP) images of the same patients were evaluated for the diagnosis of chronic pancreatitis. Correlation between ADC values and HCO(3) concentration as well as Cambridge scores in MRCP was performed using Spearman's correlation test. RESULTS: Mean ADC value of the pancreas was 1.52 +/- 0.13 x 10(-3) mm(2)/s in patients with abnormal ePFT results and 1.78 +/- 0.07 x 10(-3) mm(2)/s in the normal group. There was a significant statistical difference between the ADC values of the pancreas in the two groups (P < .0001). There was also a statistically significant correlation between HCO(3) level and ADC value of the pancreas in the study patients (r = 0.771, P < .0001). Morphologic changes of the pancreas according to the Cambridge classification were also well correlated with the mean ADC values (r = -0.763, P < .0001). CONCLUSIONS: Strong correlation between ADC value and pancreatic exocrine function as well as Cambridge score for chronic pancreatitis exists. Further studies are needed to determine the cut off ADC value for chronic pancreatitis.

[Clinicopharmacological study of gastrointestinal drugs from the viewpoint of postmarketing development].

Pharmaceutical development starts with the discovery of a new compound. Drugs become commercially available after non-clinical and clinical studies, but processes that take place after marketing are also important for pharmaceutical development. In recent years, use of the phrase "Ikuyaku" meaning postmarketing development has become more common. Sometimes, the proper usage, indications and harmful effects of a drug are discovered only after it becomes commercially available and is administered to many patients. Hence, pharmacists need to actively perform postmarketing studies to reveal the true nature of drugs. In the present clinicopharmacological study, we investigated the effects of histamine H(2) receptor antagonists (H(2)-RAs) on the plasma concentrations of gastrointestinal peptides from the viewpoint of postmarketing development. First we established an enzyme immunoassay for secretin, which is involved in gastrointestinal motility. Then we used this and existing peptide assays to investigate the above-mentioned issues. Ranitidine and nizatidine increased the plasma concentration of motilin. It is believed that the plasma concentration of Ach is elevated by ranitidine and nizatidine, which possesses an anti-AchE activity, and that the increased the plasma concentration of Ach facilitated release of motilin, elevating the plasma concentration of motilin. When compared to the placebo, lafutidine significantly increased the plasma concentration of CGRP (calcitonin gene-related peptide) and substance P. Furthermore, released CGRP stimulated CGRP1 receptors to facilitate secretion of somatostatin. Therefore, lafutidine appears to protect the gastric mucosa and regulate gastrointestinal motility. The same results were obtained with ranitidine and nizatidine. While H(2)-RAs have a common function in suppressing the secretion of gastric acid, they do not exhibit the same effects on factors related to recurrence of peptic ulcer, such as gastrointestinal motility and blood flow in the gastrointestinal mucosa. Hence, measuring the plasma concentration of gastrointestinal peptides can be used to estimate the effects of drugs on gastrointestinal motility. From the viewpoint of postmarketing development, we are in the process of establishing indicators for the proper usage of pharmaceutical drugs. Pharmacists need to closely follow and monitor adverse reactions. In order to further improve monitoring of drug therapy, it will be necessary to assess not only the blood concentrations of drugs, but also biological reactions to the drugs. Since the levels of peptides reflect the clinical efficacy of gastrointestinal drugs, measuring peptide levels appears to be useful for selecting appropriate drugs.

Cholangiocyte anion exchange and biliary bicarbonate excretion.

Primary canalicular bile undergoes a process of fluidization and alkalinization along the biliary tract that is influenced by several factors including hormones, innervation/neuropeptides, and biliary constituents. The excretion of bicarbonate at both the canaliculi and the bile ducts is an important contributor to the generation of the so-called bile-salt independent flow. Bicarbonate is secreted from hepatocytes and cholangiocytes through parallel mechanisms which involve chloride efflux through activation of Cl- channels, and further bicarbonate secretion via AE2/SLC4A2-mediated Cl-/HCO3- exchange. Glucagon and secretin are two relevant hormones which seem to act very similarly in their target cells (hepatocytes for the former and cholangiocytes for the latter). These hormones interact with their specific G protein-coupled receptors, causing increases in intracellular levels of cAMP and activation of cAMP-dependent Cl- and HCO3- secretory mechanisms. Both hepatocytes and cholangiocytes appear to have cAMP-responsive intracellular vesicles in which AE2/SLC4A2 colocalizes with cell specific Cl- channels (CFTR in cholangiocytes and not yet determined in hepatocytes) and aquaporins (AQP8 in hepatocytes and AQP1 in cholangiocytes). cAMP-induced coordinated trafficking of these vesicles to either canalicular or cholangiocyte lumenal membranes and further exocytosis results in increased osmotic forces and passive movement of water with net bicarbonate-rich hydrocholeresis.

Lipasa: una enzima singular por sus interacciones neuro-hormonales. (Revisión y análisis experimental y clínico) / Lipase: a particular enzyme because of its neuro-hormonal interactions

Un objetivo de esta presentación es el de analizar las peculiaridades distintivas de la enzima lipasa proveniente de diferentes fuentes: gástrica (LG), intestinal (LI)hepática (LH), lipoproteica (LLP), pero, en especial, aquella de la pancreática (LP), sobre todo en lo relativo a sus interacciones neuro-hormonales.(AU)

Use of capillary electrophoresis in drug quality assessment of synthetic porcine secretin.

The purity profile for porcine secretin attributable to contamination by equilibrium products such as aspartoyl(3) secretin has been shown to be dependent on the pH of the analytical system. Capillary zone electrophoresis (CZE) methods have been developed for the efficient separation of synthetic porcine secretin, its equilibrium products and other impurities in aqueous solutions at both acidic and alkaline pH. These conditions are more representative of those used for the reconstitution and administration of porcine secretin, and good results cannot be achieved using HPLC due to poor peak shape above pH 5.8. The influence of various CZE operational parameters was systematically examined. The methods were validated for accuracy, precision, linearity, LOD and LOQ. A comparative evaluation of the stability of test solutions was determined using CZE and HPLC over a range of pH values. HPLC and CZE methods produced similar results at low pH.

A stereological evaluation of secretin and gastric inhibitory peptide-containing mucosal cells of the perinatal small intestine of the pig.

Stereological methods were used to quantify secretin and gastric inhibitory peptide (GIP)-immunoreactivity (GIP-IR) in paraffin sections of the duodenum, jejunum and ileum of fetal and neonatal piglets. In addition, sections were processed for GLP-1-immunohistochemistry. The volume density of the tunica mucosa increased after birth, giving rise to a decreased volume density of the tela submucosa and tunica muscularis. Generally known region-specific morphological distinctions were reflected in differing volume densities of the various layers. The highest volume density of GIP-IR epithelial cells was observed in the jejunum of the neonate. In contrast, the volume density of secretin-IR epithelial cells was highest in the duodenum of both fetal and neonatal piglets. The volume occupied by GIP-IR and secretin-IR epithelial cells increased in the jejunum after birth. Additionally, ileal secretin-IR epithelial cells were more numerous in the neonatal piglet. In conclusion, the quantitative and qualitative presence of GIP-IR and secretin-IR epithelial cells agree with earlier reports of their presence and co-localization between GIP-IR and GLP-1-IR, in the pig small intestine. Furthermore, the differences suggest that age- and region-related functional demands are temporally and probably causally related with the morphological diversification of the intestine and its endocrine cells.

What may be the anatomical basis that secretin can improve the mental functions in autism?

Autism was first described and characterized as a behavioral disorder more than 50 years ago. The major abnormality in the central nervous system is a cerebellar atrophy. The characteristic histological sign is a striking loss or abnormal development in the Purkinje cell count. Abnormalities were also found in the limbic system, in the parietal and frontal cortex, and in the brain stem. The relation between secretin and autism was observed 3 years ago. Clinical observations by Horváth et al. [J. Assoc. Acad. Minor. Physicians 9 (1998) 9] supposed a defect in the role of secretin and its receptors in autism. The aim of the present work was to study the precise localization of secretin immunoreactivity in the nervous system using an immunohistochemical approach. No secretin immunoreactivity was observed in the forebrain structures. In the brain stem, secretin immunoreactivity was observed in the mesencephalic nucleus of the trigeminal nerve, in the superior olivary nucleus, and in scattered cells of the reticular formation. The most intensive secretin immunoreactivity was observed in the Purkinje cells of the whole cerebellum and in some of the neurons of the central cerebellar nuclei. Secretin immunoreactivity was also observed in a subpopulation of neurons in the primary sensory ganglia. This work is the first immunohistochemical demonstration of secretin-immunoreactive elements in the brain stem and in primary sensory ganglia.

Curative resection of microgastrinomas based on the intraoperative secretin test.

The intravenous secretin injection test (secretin test) has been used for the differential diagnosis of gastrinoma. In this study we report that the intraoperative secretin test (IOS test) is also useful for determining the extent of curability in patients with Zollinger-Ellison syndrome (ZES). Twelve patients with ZES underwent surgical exploration and the IOS test. The results of the IOS test were obtained by rapid radioimmunoassay of the serum gastrin level (IRG) within 60 minutes. The test was diagnosed as negative when the maximum increase of serum IRG was less than 80 pg/ml and also less than 20% of the basal serum IRG level. Three of the twelve patients underwent pancreatoduodenectomy (PD), and two patients underwent distal pancreatectomy. Extirpation of duodenal tumors with dissection of regional lymph nodes was performed in seven patients. In two of the seven patients the IOS test remained positive after extirpation of the duodenal tumors and the dissection of regional lymph nodes. In one patient PD was performed on the basis of the positive results, and the IOS test became negative after PD. In the other patient, two tiny metastatic liver tumors were identified and were resected, but the IOS test did not become negative. We closed the abdomen in 11 patients when we obtained negative results from the IOS test. The results of the IOS test were almost identical to the data obtained by the standard assay postoperatively. The serum IRG levels of all but one patient fell to the normal level, and the secretin test became negative postoperatively. The IOS test is thus useful and indispensable for curative resection of microgastrinomas in patients with ZES.

An immunohistochemical study of endocrine cells in the alimentary tract of the red-bellied frog, Bombina orientalis.

The regional distribution and relative frequency of endocrine cells was studied immunohistochemically (PAP method) in the alimentary tract of the red-bellied frog, Bombina orientalis, using antisera against serotonin, somatostatin, chromogranin (CG), cholecystokinin (CCK)-8, bombesin, secretin, glucagon and pancreatic polypeptide (PP). Eight kinds of endocrine cells were identified in this study. These immunoreactive cells were located in the gastric glands of the stomach regions and in the intestinal or esophageal epithelium with variable frequencies. They were spherical or spindle-shaped. Serotonin- and somatostatin-immunoreactive cells were demonstrated in the whole alimentary tract including esophagus. CG-immunoreactive cells were restricted to the stomach. CCK-8-immunoreactive cells were observed from the antrum to the ileum. Bombesin-immunoreactive cells were restricted to the stomach. Secretin-immunoreactive cells were demonstrated in the pylorus, duodenum and ileum. Glucagon-immunoreactive cells were found in the antrum and duodenum. PP-immunoreactive cells were detected from the antrum to the rectum. In conclusion, throughout the alimentary tract of the red-bellied frog, the different regional distribution and relative frequency of endocrine cells were demonstrated. The regional distributions and relative frequencies of the endocrine cells in the alimentary tract of the red-bellied frog were resembled to those of the other anuran species except for esophagus.

Assessment of exocrine pancreatic dysfunction in chronic pancreatitis.

The clinical diagnosis of chronic pancreatitis is usually based on imaging studies, pancreatic function tests, and the presence of characteristic clinical features. In Japan, diagnostic criteria for chronic pancreatitis were established in 1995. The secretin test (a duodenal intubation test) and the combination of noninvasive tests, N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA) and fecal chymotrypsin (FCT), have been recommended for evaluating exocrine pancreatic function in patients with chronic pancreatitis. In the present study, the diagnostic value of these two noninvasive tests was compared to the secretin test. Although noninvasive tests are less sensitive and specific for determining exocrine pancreatic dysfunction than the secretin test, greater reliability for diagnosing chronic pancreatitis can be obtained by performing the BT-PABA and FCT simultaneously. Assessment of exocrine pancreatic function is important not only to diagnose chronic pancreatitis but also to decide a treatment method with pancreatic enzyme preparation.

Abnormalities of small intestinal endocrine cells in non-obese diabetic mice.

The endocrine cells in the duodenum of pre-diabetic and diabetic female non-obese diabetic (NOD) mice aged 22-24 weeks were studied by means of immunohistochemistry and computed image analysis as well as by radioimmunoassays of tissue extracts. As controls, 12 female BALB/cJ mice of the same age as NOD mice were used. The number of secretin-immunoreactive cells increased in diabetic but not in pre-diabetic NOD mice. The level of extractable secretin was higher in both pre-diabetic and diabetic NOD mice. The number of GIP-, CCK/gastrin-, and serotonin-immunoreactive cells was significantly reduced in both pre-diabetic and diabetic NOD mice. There was no statistical difference in the number of somatostatin-immunoreactive cells between the NOD mice and controls. The level of GIP was higher and gastrin was lower in NOD mice compared to controls. There was no statistical difference in the somatostatin level between the NOD mice and controls. The cell secretory index was elevated in all the endocrine cell types except CCK/gastrin cells. It has been suggested that some of the changes in the duodenal endocrine cells could be attributed to the diabetes state, but most of the changes seem to take place before the onset of diabetes. The abnormalities in the duodenal endocrine cells observed here in an animal model for diabetes type I might have relevance for the gastrointestinal dysfunction displayed in human diabetes.

Magnetically labeled secretin retains receptor affinity to pancreas acinar cells.

Previously, we have developed a colloidal dextran-stabilized monocrystalline iron oxide nanocompound (MION-46) as a magnetic label for magnetic resonance imaging (MRI). In an effort to use this magnetic label to visualize pancreatic receptor function by MRI in vivo, we investigated the potential of secretin as a vector molecule. Secretin receptors, abundant on exocrine pancreas cells, recognize secretin through its amidated carboxyl terminal. In order to conjugate secretin to MION, we utilized the specific interaction between biotin and streptavidin, since direct conjugation of human secretin to MION has previously resulted in low yields and low affinity of the conjugate (unpublished results). Initially, we biotinylated the N-terminal primary amino group of secretin (60% yield). In a separate step, streptavidin (SA) was immobilized onto the surface dextran molecules of MION (79% yield) by reductive amination. Each secretin molecule was conjugated to one biotin molecule and each MION particle to an average of two SA molecules. The biotinylated secretin was then conjugated to MION through the biotin-streptavidin interaction (90% yield). The secretin-biotin-streptavidin-MION construct thus contained approximately two secretin molecules per MION. An in vitro competitive binding assay of pancreatic acinar cells demonstrated that the magnetically labeled secretin retained affinity to the secretin receptors. In vivo distribution studies in rats showed a significantly higher pancreatic accumulation of the secretin-biotin-streptavidin-MION construct as compared to the control group that had received unmodified MION. Our data indicate that bioactive peptides can be attached to dextran-coated iron oxide particles through the biotin-streptavidin interaction while retaining receptor affinity. Such target-specific agents have potential use in MR imaging to probe for a variety of receptor systems.

The C-terminus ends of secretin and VIP interact with the N-terminal domains of their receptors.

C-terminally truncated secretin and VIP molecules were synthesized, and their ability to occupy the recombinant secretin and VIP1 receptors stably expressed in Chinese hamster ovary (CHO) cells and to stimulate adenylate cyclase activity was studied. On secretin receptors, secretin (1-26) and secretin (1-24) were 10- and 50-fold less potent but as efficient as secretin (1-27); VIP (1-27) was as potent and efficient as VIP (1-28), and VIP (1-26) and VIP (1-25) were both 100-fold less potent. On VIP1 receptor, VIP (1-28) and VIP (1-27) were equipotent and VIP (1-26) and VIP (1-25) were 10- and 300-fold less potent, respectively; secretin (1-27) and secretin (1-26) were of equally low affinity and 10-fold more potent than secretin (1-24). Thus, the secretin and the VIP1 receptors had different selectivity profiles for the recognition of C-terminally truncated secretin and VIP derivatives. The chimeric receptors consisting in the N-terminal part of the secretin receptor on the core of the VIP1 receptor (N-Sn/VIP1.r) and in the N-terminal part of the VIP1 receptor on the core of the secretin receptor (N-VIP1/Sn.r) exhibited the selectivity pattern of the secretin and VIP1 receptors, respectively. The results suggest that the C-terminal end of secretin and VIP interacts with the N-terminal domain of the secretin and VIP receptors.

Recovery of the pancreas after acute pancreatitis is not necessarily complete.

In 38 patients, exocrine pancreatic function was tested by means of the secretin-pancreozymin test (SPT) and pancreatic duct system with endoscopic retrograde cholangiopancreatography (ERCP) 34 +/- 36 mo (mean +/- SD, range 1-156 mo) following acute pancreatitis. SPT and ERCP results were both normal in 19 (50%). They were both abnormal in four (11%) patients (group 1). Fourteen (37%) patients with normal SPT had abnormal ERCP test results (group 2), and one (3%) patient with normal ERCP had abnormal SPT (group 3). All patients except one of group 2 could be followed up within a mean observation time of 105 +/- 46 mo (range 24-168 mo): Chronic pancreatitis developed in all four patients of group 1, in one patient of group 2, and in the single patient of group 3, and suspected chronic pancreatitis in another patient of group 2. Eleven of the remaining 12 patients with abnormal ERCP results, but normal exocrine pancreatic function (group 2), showed no signs or symptoms of acute or chronic pancreatitis. It is concluded that (1) recovery to normal does not necessarily occur after acute pancreatitis, (2) progression to chronic pancreatitis is possible at a considerable percentage, and (3) duct changes demonstrated by ERCP may persist without any later signs and symptoms of acute or chronic pancreatitis.

An immunocytochemical study of the respiratory system of Podarcis hispanica (Reptilia).

The endocrine cells and nerves of the respiratory tract of the reptile Podarcis hispanica were investigated by immunocytochemistry under light microscopy. Immunoreactivities were more numerous in the lung than in the trachea. In the tracheal epithelium, endocrine cells immunoreactive to PHI, PYY, and Leu-enkephalin were detected, while immunoreactivity to serotonin, calcitonin, CGRP, PHI, and Leu-enkephalin was found in pulmonary endocrine cells. Numerous nerve fibers positive to NSE, PGP9.5, chromogranin, tyrosine hydroxylase, calcitonin, CGRP, bombesin, substance P, VIP, NPY, and PYY were found in the lungs. In addition, neurons positive to NSE and PGP9.5 were also found. Immunoreactivities to PHI and PYY in cells and to NSE, PGP9.5, chromogranin, tyrosine hydroxylase, calcitonin, CGRP, and PYY in nerves, were reported first in the respiratory system of reptiles.

Diagnostic tests in chronic pancreatitis.

We review the values of various tests in the diagnosis of suspected chronic pancreatitis, and we give a practical approach to diagnosis. Most cases can be diagnosed by a consideration of history, simple radiology, and serum enzymes. Problems arise in patients with noncalcific early chronic pancreatitis, in whom pain alone is the main feature. In these patients, a sequence of tests may be required to arrive at a diagnosis of probable or possible pancreatitis to one that is proven. In some cases, only time will tell.