Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intravenous infusion of synthetic secretin for periods up to 24 h in conscious rats was combined with in-vitro amino acid incorporation in isolated pancreatic lobules and high-resolution separation of individual enzyme proteins by two-dimensional isoelectric focusing and SDS gel electrophoresis. With this method persistent changes in the biosynthesis of ten enzyme and isoenzyme proteins can be studied as a result of prolonged secretin stimulation. Three major patterns of response were observed: progressive increases in the synthetic rates were found in six out of ten enzyme proteins with most pronounced changes in the synthetic rates of lipase (4.10-fold increase), two forms of proelastase (2.80-fold increase, respectively), the two acidic forms of trypsinogen and chymotrypsinogen (2.60- and 2.40-fold increase, respectively), and of ribonuclease (2.30-fold increase). Only moderate changes (1.30- to 1.90-fold increase) occurred in the synthetic rates of four isoenzymatic forms of procarboxypeptidase and the basic forms of chymotrypsinogen and trypsinogen, respectively. No absolute change in the rate of synthesis was observed in both forms of amylase. These data obtained after secretin stimulation differ significantly from previous results after caerulein stimulation, but it is not clear so far whether this is due to differential effects of the two second messengers released by each of the hormones on the level of transcription or translation.
 ...
PMID:In-vivo stimulation of rat pancreatic acinar cells by infusion of secretin. II. Changes in individual rates of enzyme and isoenzyme biosynthesis. 241 53

Because of the location of the pancreas deep in the abdominal cavity, laboratory tests play a major role in the diagnosis of pancreatic diseases. Amylase and lipase determinations in serum are most frequently performed and they complement each other. However, false positive and false negative results are observed. In order to increase the sensitivity and specificity of diagnostic tests, urine amylase determinations, measurements of the CAmyl Ccreat ratio and amylase isoenzyme determinations are performed. The benefits of these procedures and their limitations will be discussed. The increased sensitivity and specificity of immunoreactive trypsin determinations and contributions of this test to the early diagnosis of pancreatic disease will be described. This test seems to have some usefulness in the early diagnosis of cancer, together with the secretin and pancreozymine-cholecystokinin test and the test for ribonuclease activity in serum.
 ...
PMID:Enzyme measurements in the investigation of pancreatic diseases. 616 Aug 3

We have examined the secretogogue responsiveness and the pattern of secretory proteins produced by a transplantable rat pancreatic acinar cell tumor. Dispersed tumor cells were found to discharge secretory proteins in vitro when incubated with hormones that act on four different classes of receptors: carbamylcholine, caerulein, secretin-vasoactive intestinal peptide, and bombesin. With all hormones tested, maximal discharge from tumor cells was only about one-half that of control pancreatic lobules, but occurred at the same dose optima except for secretin, whose dose optimum was 10-fold higher. Biochemical analysis of secretory proteins discharged by the tumor cells was carried out by crossed immunoelectrophoresis and by two-dimensional isoelectric focusing-SDS polyacrylamide gel electrophoresis. To establish a baseline for comparison, secretory proteins from normal rat pancreas were identified according to enzymatic activity and correlated with migration position on two-dimensional gels. Our results indicate that a group of basic polypeptides including proelastase, basic trypsinogen, basic chymotrypsinogen, and ribonuclease, two out of three forms of procarboxypeptidase B, and the major lipase species were greatly reduced or absent in tumor cell secretion. In contrast, the amount of acidic chymotrypsinogen was notably increased compared with normal acinar cells. Although the acinar tumor cells are highly differentiated cytologically and express functional receptors for several classes of pancreatic secretagogues, they show quantitative and qualitative differences when compared with normal pancreas with regard to their production of secretory proteins.
 ...
PMID:Biochemical analysis of secretory proteins synthesized by normal rat pancreas and by pancreatic acinar tumor cells. 618 2

Laboratory tests are the object of continuous interest in acute as well as chronic pancreatic disease. Enzymic assays play an important role, particularly in screening for pancreatic disease. The diagnostic contribution of amylase, isoamylases, immunoreactive trypsin and lactoferrin, ribonuclease and galactosyltransferase, as well as the problem of chronic nonpancreatic hyperamylasemia is reviewed. Functional methods detect a normal or abnormal function and in this sense the results should be interpreted. Present evaluation of the pancreozymin-secretin test, the Lundh test, fecal chymotrypsin, determination of stimulated chymotrypsin secretion by peroral synthetic substrates marked with 4-aminobenzoic acid, duodenal excretion of 75Se-methionine and plasma pancreatic polypeptide is given. Up to now, immunologic methods have not fulfilled the expectations in spite of considerable attention paid to them in recent years.
 ...
PMID:[Developments in the laboratory diagnosis of diseases of the exocrine pancreas (author's transl)]. 702 8

Secretion stimulates ductular bile secretion by binding to receptors on intrahepatic bile duct epithelial cells (i.e., cholangiocytes). In the rat, this choleretic effect increases after bile duct ligation (BDL). Although cholangiocyte proliferation induced by BDL contributes to secretin-induced hypercholeresis, the mechanisms modulating these alterations in secretin-induced ductular bile secretion are obscure. Thus we studied the expression of secretin receptor mRNA (SR-mRNA) in purified liver cells from normal and BDL rats. Northern blot analysis and RNase protection assays with mRNA from purified liver cells demonstrated SR-mRNA only in cholangiocytes; moreover, SR gene expression showed a seven- to ninefold increase in individual cholangiocytes from BDL rats compared with controls. This increase in SR-mRNA expression was related to a similar increase in the rate of transcription of SR-mRNA in cholangiocytes from BDL rats. Thus our studies indicate that 1) SR-mRNA is detected in liver only in cholangiocytes; 2) BDL causes an increase in SR-mRNA in individual cholangiocytes; and 3) the increase in SR-mRNA after BDL is partly related to an increase in the rate of transcription of SR-mRNA by cholangiocytes after BDL. Our data suggest that upregulation of the SR gene may contribute to secretin-induced hypercholeresis.
 ...
PMID:Upregulation of secretin receptor gene expression in rat cholangiocytes after bile duct ligation. 751 77

Previous work from our laboratory has implicated hormone-induced plasma membrane movement (i.e., endo- and exocytosis) in water and electrolyte transport by the epithelial cells that line the ducts in the liver (i.e., cholangiocytes). To further explore the cellular mechanisms regulating ductal bile secretion, we infused somatostatin and/or secretin intravenously into rats 2 wk after either bile duct ligation (BDL), a procedure that induces selective proliferation of cholangiocytes, or sham surgery and measured bile flow and biliary constituents. We also determined the effect of somatostatin on basal and secretin-induced exocytosis by purified cholangiocytes isolated from rat liver after BDL. Finally, we studied the expression of the somatostatin receptor gene by both ribonuclease (RNase) protection and nuclear run-on assays using cDNA encoding for two subtypes of the somatostatin receptor gene (i.e., SSTR1 and SSTR2). In vivo, somatostatin infusion caused a dose-dependent bicarbonate-poor decrease (57% maximal decrease below baseline; P < 0.05) in bile flow in BDL but not in sham-operated rats; in contrast, secretin caused a dose-dependent bicarbonate-rich choleresis (228% maximal increase above baseline; P < 0.05) in BDL but not in sham-operated rats. Simultaneous or prior infusion of somatostatin inhibited the secretin-induced hypercholeresis in BDL rats. In vitro, somatostatin had no effect on basal exocytosis by cholangiocytes isolated from BDL rats; however, somatostatin inhitibed (88% maximal inhibition; P < 0.05) secretin-induced exocytosis by cholangiocytes in a dose-dependent fashion. In addition, somatostatin inhibited secretin-induced increases in levels of adenosine 3',5'-cyclic monophosphate (cAMP) in cholangiocytes isolated from BDL rats.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Somatostatin inhibits secretin-induced ductal hypercholeresis and exocytosis by cholangiocytes. 763 87

Pituitary adenylate cyclase activating polypeptide (PACAP) is a new member of the secretin/glucagon/vasoactive intestinal peptide (VIP) family. It stimulates adenylate cyclase in cultured rat pituitary cells, which have PACAP-specific receptors and expression of pituitary hormones. Therefore, PACAP is considered as a hypophysiotropic hormone. If so, there might be a feedback regulatory mechanism between pituitary hormones and hypothalamic PACAP. In the present study, we used nuclear run-on and RNase protection assays to examine whether transcription of the PACAP gene in the rat hypothalamus would change after hypophysectomy. PACAP levels in the hypothalamus were also determined by radioimmunoassay. The transcriptional rate of the PACAP gene and PACAP mRNA content decreased 1 and 2 weeks after hypophysectomy. Radioimmunoassayable PACAP levels in the hypothalamus also decreased after hypophysectomy. These findings suggest that the reduced rate of PACAP gene transcription after hypophysectomy causes the decreased mRNA and peptide levels in the hypothalamus. Replacement with GH, PRL, T4, corticosterone, and testosterone significantly restored PACAP mRNA levels in hypophysectomized rats to those in control animals. The results suggest that feedback regulation takes place between pituitary hormones or pituitary-dependent factors and hypothalamic PACAP.
 ...
PMID:Effect of hypophysectomy on pituitary adenylate cyclase activating polypeptide gene expression in the rat hypothalamus. 765 92

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a member of the secretin/glucagon/vasoactive intestinal peptide (VIP) family. Our immunohistochemical and in situ hybridization histochemical studies indicated that PACAP-like immunoreactivity (PACAP-LI) and its mRNA were present in the germ cells in the rat testis. Because the testicular function is regulated by the pituitary gonadotropins, effect of hypophysectomy on the PACAP gene expression was investigated in the rat testis as an attempt to reveal the regulation of the testicular PACAP by the pituitary. The levels of testicular PACAP mRNA, which were determined by RNase protection assay, increased 2 weeks after hypophysectomy. In contrast, the levels of radioimmunoassayable PACAP decreased 2 weeks after the surgery. Immunohistochemistry showed that hypophysectomy did not change the distribution of PACAP-LI, although the number of immunopositive cells was markedly reduced after hypophysectomy. The replacement treatments of hypophysectomized animals with FSH or LH+FSH restored testicular PACAP mRNA to the levels in the control animals. On the other hand, all of these treatments (testosterone, LH, FSH, or LH+FSH) significantly increased radioimmunoassayable PACAP in the hypophysectomized rat testis. The results suggest that both testicular PACAP and its mRNA expression are regulated by the hypothalamic-pituitary-gonadal activity, and that FSH may play a major role in this regulation.
 ...
PMID:Effect of hypophysectomy on pituitary adenylate cyclase-activating polypeptide gene expression in the rat testis. 853 85

Secretin is an important regulator of pancreatic function, but the molecular basis of its actions is not well understood. We have, therefore, used in situ autoradiography, photoaffinity labeling, and RNase protection assays with healthy rat pancreas, dispersed acinar cells, and pancreas depleted of acinar cells to explore the cellular distribution and molecular identity of high-affinity secretin receptors in this complex organ. The autoradiographic examination of 125I-labeled [Tyr10]rat secretin-27 binding to normal pancreas demonstrated saturable and specific high-affinity binding sites on both acinar and duct cells, with a uniform lobular distribution, but with no binding above background over islets or vascular structures. Photoaffinity labeling demonstrated that the ductular binding site in acinar cell-depleted copper-deficient rat pancreas represented the same glycoprotein with a molecular weight of 50,000-62,000 that was present on acinar cells. RNase protection assays confirmed the molecular identity of the secretin receptors expressed on these distinct cells. The apparent absence or extreme low density of similar secretin receptors on islets and pancreatic vascular structures suggests that the pharmacological effects of secretin on those cells may either be indirect or mediated by another secretin family receptor that recognizes this hormone with lower affinity.
 ...
PMID:Cellular distribution of secretin receptor expression in rat pancreas. 984 82

We recently reported that secretin induces the exocytic insertion of functional aquaporin-1 water channels (AQP1) into the apical membrane of cholangiocytes and proposed that this was a key process in ductal bile secretion. Because AQP1 is present on the basolateral cholangiocyte membrane in low amounts, we hypothesized that another AQP must be expressed at this domain to facilitate transbasolateral water movement. Thus, we investigated the expression, subcellular localization, possible regulation by secretin, and functional activity of AQP4, a mercury-insensitive water channel expressed in other fluid transporting epithelia. Using reverse transcription-polymerase chain reaction (RT-PCR) on RNA prepared from purified rat cholangiocytes, we amplified a product of 311 bp that was 100% homologous to the reported AQP4 sequence. RNase protection assay confirmed the presence of an appropriate size transcript for AQP4 in cholangiocytes. Immunoblotting detected a band of approximately 31 kd corresponding to AQP4 in basolateral but not apical membranes of cholangiocytes. Secretin did not alter the amount of plasma membrane AQP4 but, as expected, induced AQP1 redistribution from intracellular to apical plasma membranes. Functional studies showed that AQP4 accounts for about 15% of total cholangiocyte membrane water permeability. Our results indicate that: (1) cholangiocytes express AQP4 messenger RNA (mRNA) and protein and (2) in contrast to AQP1, which is targeted to the apical cholangiocyte membrane by secretin, AQP4 is constitutively expressed on the basolateral cholangiocyte membrane and is secretin unresponsive. The data suggest that AQP4 facilitates the basolateral transport of water in cholangiocytes, a process that could be relevant to ductal bile formation.
 ...
PMID:Expression of aquaporin-4 water channels in rat cholangiocytes. 1082 57


1 2 Next >>