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Query: UNIPROT:P06889 (Mol)
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The glycogen concentration in liver is altered in various pathophysiologic states. In fasted rats, it is higher in diabetic, and lower in adrenalectomized rats compared to control animals. In fed rats, it is lower in diabetic, and little changed in adrenalectomized animals compared to controls. We were interested in determining whether the activity of glycogenin, a self-glycosylating protein that initiates the synthesis of new glycogen molecules, could explain these differences in liver glycogen concentration. Glycogenin activity was measured by the incorporation of 14C-glucose from UDP-U-14C-glucose into an acid-precipitable product before and after amylase treatment of liver extracts. The glycogenin activity was similar in normal, diabetic and adrenalectomized fasted animals, regardless of the hepatic glycogen concentration. In fasted rats, glycogenin was present predominantly as the free-form of the enzyme, i.e., not attached to an amylase-digestible glycan, presumably glycogen. In contrast, in fed rats, the majority, if not all of the glycogenin was incorporated into a glycogen-like (proteoglycan) molecule. Proteoglycan synthase activity, previously identified in normal fed rats, also was present in diabetic and adrenalectomized fed rats, and the activity was similar. Thus, the altered ability to store hepatic glycogen in diabetic fed and fasted and adrenalectomized fasted rats cannot be explained by decreases in glycogenin or proteoglycan synthase activities, at least as measured using the present assays.
Cell Mol Biol (Noisy-le-grand) 1998 Sep
PMID:Liver glycogenin activity in diabetic and adrenalectomized rats. 976 98

Adrenergic stimulation of parotid secretion was investigated in anaesthetised brushtail possums to ascertain fluid secretion rates and salivary composition. Because neither alpha- nor beta-adrenergic stimulation evoked saliva output, infusion of the adrenergic agonists was superimposed on a pre-existing bethanechol-stimulated flow. Isoprenaline infusion (2.4 nmol min-1) increased salivary amylase activity, [protein]; [HCO3]; [PO4] and [Ca], and amylase/Ca and protein/Ca ratios; reduced [Cl]; [K] and osmolality; but did not alter H+ activity; [urea]; [Na]; [Mg]; amylase/protein or saliva/plasma urea ratios. These data are consistent with isoprenaline stimulating acinar secretion of protein, Ca and PO4 but not the ion transport necessary for primary fluid formation at the endpieces and modifying transport of monovalent ions in the excurrent ducts. Consequently, the possum parotid has beta-adrenergic receptors in both the endpieces and excurrent ducts. Phenylephrine infusions at 2.4 and 24 nmol min-1 were without effect whereas phenylephrine at 240 nmol min-1 caused changes in salivary composition which paralleled those for isoprenaline administration but were generally of lesser magnitude. Thus, the possum parotid has few or no alpha-adrenergic receptors and the salivary response elicited was the result of cross-reaction of phenylephrine with beta-adrenergic receptors.
Comp Biochem Physiol A Mol Integr Physiol 1998 Jun
PMID:Response of the parotid gland of the brushtail possum, Trichosurus vulpecula, to adrenergic stimulation. 977 9

This study employs the pancreas of normal and diabetic rats to investigate the relationship between the endocrine and exocrine pancreas in the control of exocrine secretion employing enzyme and immunohistochemical and physiological techniques. Acetylcholine esterase (ACh-E) positive nerves were distributed in the interacinar regions of the pancreas lying close to the exocrine cells. There was no difference between the cholinergic innervation of the pancreas in normal and diabetic rat. Insulin (INS) immunopositive cells were observed in the peripheral and central portions of the Islet of Langerhans in the pancreas of normal rat. In the diabetic animals the number of INS-positive cells were decreased. In contrast, glucagon (GLU) and somatostatin (SOM)-immunopositive cells were identified mainly in the peripheral parts of the Islets of Langerhans and their numbers increased markedly in the diabetic pancreas. Insulin alone had no significant effect on amylase secretion in the normal pancreas whereas GLU and SOM evoked small increases in amylase out compared to basal. In contrast, the islet hormones have no detectable secretory effect on the diabetic pancreas compared to control. Both electrical field stimulation (EFS) of intrinsic secretomotor nerves and exogenous application of acetylcholine (ACh) resulted in marked increases in amylase secretion. In pancreatic acini and acinar cells ACh evoked dose-dependent increases in amylase release. In normal pancreatic segments a combination of either INS or GLU with EFS or ACh resulted in marked potentiation of amylase output. In contrast, SOM inhibited the EFS-evoked amylase output but enhanced the secretory response to ACh. In pancreatic acini and acinar cells from normal rat and in pancreatic segments from diabetic rats, the islet hormones had no potentiating effect on the ACh-evoked secretory response. Similarly, in the diabetic rat the islet hormone had no effect on EFS-evoked amylase output. In fura-2 loaded pancreatic acinar cells ACh-induced a marked increase in intracellular free calcium concentration [Ca2+]i compared to basal. Either INS or GLU, but not SOM, elicited a small increase in [Ca2+]i. Combining either INS or GLU with ACh resulted in a potentiation of [Ca2+]i compared with ACh alone. In contrast, SOM had no significant effect on the ACh-induced [Ca2+]i compared to the response obtained with ACh alone. In pancreatic acinar cells of diabetic rat ACh-elicited similar magnitude of [Ca2+]i compared to acinar cells of normal rat. However, when the islet hormones were combined with ACh there was no enhancement of [Ca2+]i compared to ACh alone. The results indicate that the potentiation of either EFS or ACh-evoked secretory responses by the islet hormones seem to occur only in pancreatic segments which have intact viable Islets of Langerhans and not in either acini and acinar cells or from the pancreas of diabetic rat. Moreover, it is apparent that cellular Ca2+ is involved with the interaction of ACh with either INS or GLU.
Int J Mol Med 1998 Mar
PMID:Effects of islet hormones on nerve-mediated and acetylcholine-evoked secretory responses in the isolated pancreas of normal and diabetic rats. 985 77

This study compared pancreatic tissue growth and functional changes during the first 3 postnatal days in piglets and rat pups. In piglets the absolute weight and the relative weight per unit body weight of the pancreas increased by 97 and 70%, respectively, while in rat pups the same parameters decreased by 33 and 48%, respectively, during this period. The specific activity of pancreatic amylase rose by 336% while that of trypsin, chymotrypsin and lipase remained at newborn level in piglets. In rat pups the specific activities of all enzymes measured declined by 61 to 92% during the first 3 postnatal days. The rate of postnatal pancreatic growth in the two species coincide with the levels of epidermal growth factor and insulin-like growth factors in maternal milk as reported in the literature, suggesting that milk-borne growth factors may stimulate pancreatic development in newborn animals.
Comp Biochem Physiol A Mol Integr Physiol 1998 Aug
PMID:Comparison of growth and development of the exocrine pancreas in pigs and rats during the immediate postnatal period. 1040 Apr 93

Vertebrate gastrointestinal hormones were tested on their ability to liberate digestive enzymes from the crustacean midgut gland. CCK-8 (desulfated form), gastrin, bombesin, secretin, and substance P were detected to release enzymes. Maximal concentrations observed were 5 nM CCK for protease release, 1 nM gastrin for protease and 100 nM for amylase release, 100 nM bombesin for protease release, 10 nM secretin for amylase and protease release, and 100 nM substance P for protease release. Unlike in vertebrates, glucagon was unable to stimulate enzyme release in crustaceans, this also applies to the counterpart insulin. These results may support the assumption that Crustacea possess endogenous factors resembling the above mentioned vertebrate hormones, at least in such a way that the appropriate receptors have the capacity to accept these hormones.
Comp Biochem Physiol B Biochem Mol Biol 1999 Jun
PMID:Release of digestive enzymes from the crustacean hepatopancreas: effect of vertebrate gastrointestinal hormones. 1042 22

Glucose-dependent insulinotropic polypeptide (GIP) plays an important role in stimulating insulin release in the pancreas as well as inhibiting gastric acid secretion in the stomach. GIP has been found in specific endocrine cells located in the mucosal layer of the small intestine and in the submandibular salivary gland. In this study, the tissue-specific expression of GIP guided by 1.2 kb of the human GIP (hGIP) gene 5' flanking region was investigated by a transgenic mouse approach. A chimeric promoter-reporter gene construct linking the 5'-flanking region of the hGIP gene with the thymidine kinase gene of the herpes simplex virus was introduced into the genomes of mice by microinjection. By reverse transcriptase-PCR (RT-PCR) and thymidine kinase assays, transgene expression was found in the stomach and pancreas. The enzyme activity detected in the stomach was about 6-fold higher than that found in the pancreas, suggesting that GIP may be expressed in the stomach. This observation is supported by RT-PCR studies since both human and mouse GIP transcripts are detected in the stomach and small intestine. In addition, distinct GIP-producing cells were identified in both tissues in mouse by in situ hybridization and immunohistochemical staining. Taken together, our data demonstrate for the first time that GIP is expressed in human and mouse stomach.
Mol Cell Endocrinol 1999 Aug 20
PMID:Glucose-dependent insulinotropic polypeptide gene expression in the stomach: revealed by a transgenic mouse study, in situ hybridization and immunohistochemical staining. 1050 10

Little is known about the changes in pancreatic enzyme storage in acute pancreatitis. We have performed flow cytometric studies of zymogen granules from rats with acute pancreatitis induced by hyperstimulation with caerulein. A comparison was made with rats treated with hydrocortisone (10 mg/kg/day) over 7 days before inducing pancreatitis in order to find out whether the amount of enzymes stored in the pancreas plays a key role in the development of pancreatitis. The potentially therapeutic effect of L-364,718 (0.1 mg/kg/day, for 7 days), a CCK receptor antagonist, was assayed in the rats with caerulein-induced pancreatitis which had previously received the hydrocortisone treatment. A significant increase in the intragranular enzyme content was observed 5 h after hyperstimulation with caerulein. The highest values were reached in the rats previously treated with hydrocortisone. The greatest pancreatic enzyme load was parallel to the highest values in plasma amylase, edema and haematocrit observed. Acute pancreatitis was reversed seven days later. At this stage smaller granules appeared in the pancreas whose enzyme content was similar to that of controls when no treatment was applied after pancreatitis. In contrast, L-364,718 administration prevented the favourable evolution of pancreatitis since the antagonism exerted on CCK receptors induced a blockade of secretion of the large amounts of enzymes stored in the pancreas. Moreover, the enzyme content in zymogen granules was below normal values since the stimulatory CCK action on enzyme synthesis can be inhibited by L-364,718. Our results suggest that the efficiency of CCK antagonists, as potential therapy, would also depend on the load of enzymes in the pancreas when acute pancreatitis is produced.
Mol Cell Biochem 1999 Oct
PMID:The recovery of acute pancreatitis depends on the enzyme amount stored in zymogen granules at early stages. 1056 81

We have cloned a regulatory gene for amylase synthesis in Aspergillus oryzae. This gene, amyR, encodes a 604-amino acid transcriptional activator with a Cys6 zinc cluster, that shows extensive homology to the DNA binding domain of GAL4 from Saccharomyces cerevisiae. The DNA binding domain of amyR binds to two types of sequences found in a number of promoters from Aspergillus genes coding for starch-degrading enzymes. One type of binding site is characterized by two CGG triplets separated by eight nucleotides. The other type has only one CGG triplet, which is followed by the sequence AAATTTAA.
Mol Gen Genet 1999 Dec
PMID:A new transcriptional activator for amylase genes in Aspergillus. 1062 49

Both male and female adult stages of the sand fly Lutzomyia longipalpis have detectable amylase activity in their salivary glands, as indicated by formation of p-nitrophenyl-alpha-D-maltoside from p-nitrophenyl-alpha-D-octoside and by hydrolysis of 4-nitrophenyl-alpha-D-maltoheptaoside-4,6,-O-ethylidene. No salivary alpha-glucosidase was detected. Amylase activity was also found in the crop and midgut of female flies, although in a smaller amount. Salivary amylase is significantly reduced from the salivary glands immediately after a blood meal, as is the case with salivary alpha-glucosidases in mosquitoes. Presence of salivary gland amylase in these sand flies, and absence of salivary alpha-glucosidase, indicates that in nature these insects may have a significant intake of carbohydrates in the form of starch, as suggested by their plant-feeding behavior, previously demonstrated by Schlein and Warburg (Schlein, Y., Warburg, A., 1986. Phytophagy and the feeding cycle of Phlebotomus papatasi (Diptera: Psychodidae) under experimental conditions. Journal of Medical Entomology 23, 11-15), and Alexander and Usma (Alexander, B., Usma, M.C., 1994. Potential sources of sugar for the phlebotomine sandfly Lutzomyia youngi (Diptera: Psychodidae) in a Columbia coffee plantation. Ann. Trop. Med. Parasitol. 88, 543-549).
Insect Biochem Mol Biol 2000 Apr
PMID:Salivary amylase activity of the phlebotomine sand fly, Lutzomyia longipalpis. 1072 93

The adult coffee berry borer (Hypothenemus hampei Ferrari [Coleoptera: Scolytidae]), a major insect pest of coffee, has two major digestive alpha-amylases that can be separated by isoelectric focusing. The alpha-amylase activity has a broad pH optimum between 4.0 and 7.0. Using pH indicators, the pH of the midgut was determined to be between 4.5 and 5.2. At pH 5.0, the coffee berry borer alpha-amylase activity is inhibited substantially (80%) by relatively low levels of the amylase inhibitor (alphaAI-1) from the common bean, Phaseolus vulgaris L., and much less so by the amylase inhibitor from Amaranthus. We used an in-gel zymogram assay to demonstrate that seed extracts can be screened to find suitable inhibitors of amylases. The prospect of using the genes that encode these inhibitors to make coffee resistant to the coffee berry borer via genetic engineering is discussed.
Insect Biochem Mol Biol 2000 Mar
PMID:Alpha-amylases of the coffee berry borer (Hypothenemus hampei) and their inhibition by two plant amylase inhibitors. 1073 88


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