Jejunal Extracts Research Articles

Continuous ingestion of sodium chloride solution promotes allergen absorption and may exacerbate allergy symptoms on ovalbumin-induced food allergy in mice.

Various studies have reported relationships between salt intake and diseases, such as hypertension, cardiovascular disease, stroke, gastric cancer, and bronchial asthma. However, no reports exist on the relationship between salt intake and food allergies. In this study, we investigated the effect of continuous ingestion of sodium chloride (NaCl) on allergy symptoms using a mouse model of food allergy. BALB/c mice were divided into four groups of 6-8 animals each. The control-water group (CW) and sensitization-water group (SW) groups were provided free access to water, and the control-1% NaCl group (CS) and sensitization-1% NaCl group (SS) groups were provided a 1% NaCl solution. The SW and SS groups were sensitized with 50 µg ovalbumin (OVA) at 2 timepoints by intraperitoneal injection. After oral administration of OVA, anaphylactic response was measured and blood was collected. The mice were sacrificed, and serum levels of OVA and anti-OVA immunoglobulin (Ig)E and IgG1 were measured by enzyme-linked immunosorbent assays. The sodium ion (Na+) concentrations in duodenal and jejunal extracts were measured using a Na+ ion meter. The results suggested that continuous ingestion of a 1% NaCl solution for 36 days promoted allergen absorption and may have aggravated allergy symptoms in the mice. However, NaCl ingestion did not affect Na+ concentrations in the small intestine or OVA-specific antibody production.

Cholecystokinin—From Local Gut Hormone to Ubiquitous Messenger

Cholecystokinin (CCK) was discovered in 1928 in jejunal extracts as a gallbladder contraction factor. It was later shown to be member of a peptide family, which are all ligands for the CCK1 and CCK2 receptors. CCK peptides are known to be synthetized in small intestinal endocrine I-cells and cerebral neurons. But in addition, CCK is expressed in several endocrine glands (pituitary cells, thyroid C-cells, pancreatic islets, the adrenals, and the testes); in peripheral nerves; in cortical and medullary kidney cells; in cardial myocytes; and in cells of the immune system. CCK peptides stimulate pancreatic enzyme secretion and growth, gallbladder contraction, and gut motility, satiety and inhibit acid secretion from the stomach. Moreover, they are major neurotransmitters in the brain and the periphery. CCK peptides also stimulate calcitonin, insulin, and glucagon secretion, and they may act as natriuretic peptides in the kidneys. CCK peptides are derived from proCCK with a C-terminal bioactive YMGWMDFamide sequence, in which the Y-residue is partly O-sulfated. The plasma forms are CCK-58, -33, -22, and -8, whereas the small CCK-8 and -5 are potent neurotransmitters. Over the last decades, CCK expression has also been encountered in tumors (neuroendocrine tumors, cerebral astrocytomas, gliomas, acoustic neuromas, and specific pediatric tumors). Recently, a metastastic islet cell tumor was found to cause a specific CCKoma syndrome, suggesting that circulating CCK may be a useful tumor marker.

The Cell-Specific Pattern of Cholecystokinin Peptides in Endocrine Cells Versus Neurons Is Governed by the Expression of Prohormone Convertases 1/3, 2, and 5/6

Most peptide hormone genes are, in addition to endocrine cells, also expressed in neurons. The peptide hormone cholecystokinin (CCK) is expressed in different molecular forms in cerebral neurons and intestinal endocrine cells. To understand this difference, we examined the roles of the neuroendocrine prohormone convertases (PC) 1/3, PC2, and PC5/6 by measurement of proCCK, processing intermediates and bioactive, alpha-amidated, and O-sulfated CCK peptides in cerebral and jejunal extracts of null mice, controls, and in the PC5/6-expressing SK-N-MC cell-line. In PC1/3 null mice, the synthesis of bioactive CCK peptide in the gut was reduced to 3% of the translational product, all of which was in the form of alpha-amidated and tyrosine O-sulfated CCK-22, whereas the neuronal synthesis in the brain was largely unaffected. This is opposite to the PC2 null mice in which only the cerebral synthesis was affected. SK-N-MC cells, which express neither PC1/3 nor PC2, synthesized alone the processing intermediate, glycine-extended CCK-22. Immunocytochemistry confirmed that intestinal endocrine CCK cells in wild-type mice express PC1/3 but not PC2. In contrast, cerebral CCK neurons contain PC2 and only little, if any, PC1/3. Taken together, the data indicate that PC1/3 governs the endocrine and PC2 the neuronal processing of proCCK, whereas PC5/6 contributes only to a modest endocrine synthesis of CCK-22. The results suggest that the different peptide patterns in the brain and the gut are due to different expression of PCs.

Characterization of structural and catalytic differences in rat intestinal alkaline phosphatase isozymes

To understand the differences between the rat intestinal alkaline phosphatase isozymes rIAP-I and rIAP-II, we constructed structural models based on the previously determined crystal structure for human placental alkaline phosphatase (hPLAP). Our models of rIAP-I and rIAP-II displayed a typical alpha/beta topology, but the crown domain of rIAP-I contained an additional beta-sheet, while the embracing arm region of rIAP-II lacked the alpha-helix, when each model was compared to hPLAP. The representations of surface potential in the rIAPs were predominantly positive at the base of the active site. The coordinated metal at the active site was predicted to be a zinc triad in rIAP-I, whereas the typical combination of two zinc atoms and one magnesium atom was proposed for rIAP-II. Using metal-depleted extracts from rat duodenum or jejunum and hPLAP, we performed enzyme assays under restricted metal conditions. With the duodenal and jejunal extract, but not with hPLAP, enzyme activity was restored by the addition of zinc, whereas in nonchelated extracts, the addition of zinc inhibited duodenal IAP and hPLAP, but not jejunal IAP. Western blotting revealed that nearly all of the rIAP in the jejunum extracts was rIAP-I, whereas in duodenum the percentage of rIAP-I (55%) correlated with the degree of AP activation (60% relative to that seen with jejunal extracts). These data are consistent with the presence of a triad of zinc atoms at the active site of rIAP-I, but not rIAP-II or hPLAP. Although no differences in amino acid alignment in the vicinity of metal-binding site 3 were predicted between the rIAPs and hPLAP, the His153 residue of both rIAPs was closer to the metal position than that in hPLAP. Between the rIAPs, a difference was observed at amino acid position 317 that is indirectly related to the coordination of the metal at metal-binding site 3 and water molecules. These findings suggest that the side-chain position of His153, and the alignment of Q317, might be the major determinants for activation of the zinc triad in rIAP-I.

Immunochemical Studies on Macromolecular Gastrins: Evidence that “big big gastrins” are artifacts in blood and mucosa, but truly present in some large gastrinomas

Whereas true macromolecules are present in some large gastrinomas, it is still unsettled whether macromolecular gastrin–earlier designated gastrin (BBG) – is truly present in blood and tissue. This question has now been evaluated by gel and affinity chromatography monitored radioimmunochemically. Gel chromatography on small Sephadex G-50 columns (10 by 500 mm) of serum from 8 normal fasting subjects confirmed that apparent immunoreactivity is eluted in the void volume. However, in contrast to the established serum gastrins (components I to IV) the apparent serum BBG was not removed by affinity chromatography. The amount of apparent BBG was related to the amount of proteins present in the void volume fractions and to the ability of serum proteins to interfere with the binding affinity of three different antisera used. Gel chromatography on Sephadex G-50 columns of antral, duodenal, and jejunal extracts revealed in the void volume only when large amounts of extracts were applied to the columns. By refiltration of these void volume fractions the apparent BBG disappeared and immunoreactivity was now eluted corresponding to components I, II (gastrin-34 or big gastrin), and III (gastrin-17 or little gastrin). In contrast to these findings an extract of a large gastrinoma, previously used to substantiate the nature of BBG, contained a number of macromolecules with apparent molecular masses ranging from 30,000 to 100,000 daltons. These gastrins, defined as BBG by their elution in the void volume of Sephadex G-50 columns, were removed by affinity chromatography using antibodies specific for the carboxyl terminal sequence of gastrin-17 from buffer or serum solutions. Elution in urea gradient on Sephadex G-50 columns of extracts from further three gastrinomas disclosed BBG in still one tumor. The results indicate that there are no detectable true macromolecular gastrins in serum and non-neoplastic gastrointestinal mucosa. The apparent BBG is rather attributable to interference in the assay by normal serum proteins or to weak noncovalent protein-binding of smaller gastrins. In contrast, true macromolecules consisting of gastrin-17 covalently coupled in its amino-terminus to proteins of varying length are present in detectable amounts in some large gastrinomas.

Characterization of glucagon-like immunoreactivity (GLI).

The present studies were designed to obtain further information concerning the chemical interrelationships of the fractions of glucagon-like immunoreactivity (GLI) present in gastrointestinal tissues, their biologic activity, and their immunochemical and electrophoretic properties. Chromatography of canine jejunal extracts on a Bio-Gel P-10 column separated GLI into two fractions; one, designated Peak II, eluted with the glucagon-I-131 marker (molecular weight 3,500), while the other, designated Peak I, appeared before the insulin-I-131 marker (molecular weight >6,000). Neither rechromatography, nor incubation in 8 M urea, acetic acid, or mercaptoethanol changed the elution volume of Peak I; however, trypsin caused a major loss of immunoreactivity and a shift of residual immunoreactivity to the postglucagon-I-131 zone. Peak I was devoid of glycogenolytic activity in the perfusedrat liver, as was its tryptic product, while Peak II was consistently as active as pancreatic glucagon. Immunoprecipitated Peak II was also active, proving that the immunoreactive fraction was responsible for its biologic action. Unlike pancreatic glucagon, Peak I, Peak II, and the tryptic product of Peak I diluted disproportionately with the less specific antiserum; however, Peak II could not be differentiated from pancreatic glucagon by means of polyacrylamide gel disc electrophoresis. It is concluded that (1) Peak I does not consist of Peak II bound noncovalently either to itself or to another protein; (2) Peak I and its tryptic product are devoid of glycogenolytic activity while Peak II has the approximate activity of pancreatic glucagon; (3) the glycogenolytic and immunoreactive components in the eluate containing Peak II are probably on the same molecule; (4) both Peak I, its tryptic product, and Peak II are immunologically different from pancreatic glucagon.

Effects of gastric and jejunal juice extracts on gastric acid secretion.

AbstractThe specificity of inhibition of i.v. injected extracts prepared from the gastric antral juice of dogs was studied by comparison with extracts prepared from canine fundic and jejunal pouches. The extracts were prepared by dialysis against water and lyophilization, and injected in doses of 1 mg/kg b.w. into Heidenhain pouch dogs secreting at a steady state from constantly infused histamine. Extracts of antral juice (22 expts. in 5 dogs) were found to inhibit gastric secretion in 17 expts. (average 63.6%), while in 4 expts. there was stimulation of gastric secretion (average 57%). Extracts of fundic juice were tested in 21 expts. in 4 dogs, and showed inhibition in 10 (average 50.4%) and stimulation in 10 expts. (average 54.8%). The extracts obtained from jejunal secretions were tested in 15 expts. on 3 dogs, and showed inhibition of gastric acid secretion in 9 expts. (average 50.6%), while in 4 expts. there was significant stimulation of the secretion (47.7%). Rectal temperature was increased more than 0.5° C in 8 of the experiments with antral juice extracts, in 4 with fundic extracts, and in 7 with jejunal extracts. Inhibition or stimulation was observed in these experiments. It is concluded that dialyzed and lyophilized extracts from gastrointestinal secretions contain substances that either stimulate or inhibit gastric secretion. The inhibitory effect could not be completely explained by pyrogenicity of extracts.

Demonstration and Characterization of a Second Fraction of Glucagon-Like Immunoreactivity in Jejunal Extracts

Demonstration and Characterization of a Second Fraction of Glucagon-Like Immunoreactivity in Jejunal Extracts