Biomedical subjects
M Kitagawa
Publications and source records attributed to M Kitagawa.
The effect of pituitary adenylate cyclase activating polypeptide (PACAP) on amylase secretion from guinea pig pancreatic acini.
Pituitary adenylate cyclase activating polypeptide (PACAP) is a novel hypothalamic peptide, structurally related to vasoactive intestinal peptide (VIP). Our previous study in conscious dogs revealed that PACAP stimulated exocrine pancreatic secretion in a manner different from VIP. The objectives of this study were to characterize the effects of PACAP on amylase secretion and intracellular cAMP production in guinea pig pancreatic acini and to compare them with those of VIP and secretin. PACAP38 and PACAP27 (10(-10)-10(-8)M) stimulated amylase secretion from pancreatic acini in a concentration-related manner. The order of potency for amylase secretion was PACAP27 = VIP > PACAP38. The maximally stimulated amylase secretion by PACAP27 was not enhanced by VIP or secretin, but was synergistically increased by cholecystokinin and A23187. PACAP38 and PACAP27 (10(-2)-10(-7)M) increased intracellular cAMP levels in a concentration-related manner. The potency for cAMP production was PACAP38 = PACAP27 = VIP. These results suggest that PACAP38 and PACAP27, like VIP, directly stimulate amylase secretion from guinea pig pancreatic acini through alterations in cellular cAMP levels.
Activation of PKN, a novel 120-kDa protein kinase with leucine zipper-like sequences, by unsaturated fatty acids and by limited proteolysis.
PKN, a novel protein kinase with catalytic domain homologous to PKC family and unique amino terminal leucine zipper-like sequences, was purified partially from COS7 cells transfected with the cDNA construct encoding human PKN for enzymatic characterization of the enzyme. Using serine containing synthetic peptides based on PKC pseudosubstrate sites as the phosphate acceptors, kinase activities estimated from partially purified PKN were not stimulated by Ca2+/phosphatidylserine/diolein but were activated several-fold to several tens-fold by 40 microM unsaturated fatty acids, such as arachidonic acid, linoleic acid, and oleic acid. Autophosphorylation of the immunoprecipitates using anti-PKN antiserum was also stimulated by various unsaturated fatty acids. Limited proteolysis of PKN with trypsin induced an enhancement of the peptide kinase activity that was almost independent of arachidonic acid.
Involvement of ecto-ATPase as an ATP receptor in the stimulatory effect of extracellular ATP on NO release in bovine aorta endothelial cells.
The secretion of nitric oxide (NO) was stimulated by the addition of ATP or ADP, but not by AMP or adenosine, in cultured bovine aorta endothelial cells. Inhibitors of ecto-ATPase, NaN3 and Ap5A, significantly inhibited the stimulation, while an inhibitor of P2Y-purinoceptor and ecto-ATPase, RB2, completely suppressed it. A non-hydrolyzable ATP analogue, AMP-PNP, stimulated NO release; the stimulation was completely suppressed by RB2 but not by NaN3 and Ap5A. Therefore, only P2Y-purinoceptor was involved in the stimulation by AMP-PNP, while both ecto-ATPase and P2Y-purinoceptor were involved in the stimulation by ATP and ADP. It is not clear whether the stimulation is dependent on the dephosphorylation activity of ecto-ATPase or not, but the enzyme appears to act as an ATP and ADP receptor for signal transduction through adenine nucleotides.
Involvement of the IRF-1 transcription factor in antiviral responses to interferons.
The mechanisms underlying interferon (IFN)-induced antiviral states are not well understood. Interferon regulatory factor-1 (IRF-1) is an IFN-inducible transcriptional activator, whereas IRF-2 suppresses IRF-1 action. The inhibition of encephalomyocarditis virus (EMCV) replication by IFN-alpha and especially by IFN-gamma was impaired in cells from mice with a null mutation in the IRF-1 gene (IRF-1-/- mice). The IRF-1-/- mice were less resistant than normal mice to EMCV infection, as revealed by accelerated mortality and a larger virus titer in target organs. The absence of IRF-1 did not clearly affect replication of two other types of viruses. Thus, IRF-1 is necessary for the antiviral action of IFNs against some viruses, but IFNs activate multiple activation pathways through diverse target genes to induce the antiviral state.
Cellular commitment to oncogene-induced transformation or apoptosis is dependent on the transcription factor IRF-1.
The transcriptional activator interferon regulatory factor 1 (IRF-1) and its antagonistic repressor IRF-2 are regulators of the interferon (IFN) system and of cell growth. Here we report that embryonic fibroblasts (EFs) from mice with a null mutation in the IRF-1 gene (IRF-1-/- mice) can be transformed by expression of an activated c-Ha-ras oncogene. This property is not observed in EFs from wild-type or IRF-2-/- mice but is still observed in EFs from mice deficient in both genes. The transformed phenotype of ras-expressing IRF-1-/- EFs could be suppressed by the expression of the IRF-1 cDNA. Thus, IRF-1 functions as a tumor suppressor. Furthermore, expression of the c-Ha-ras oncogene causes wild-type but not IRF-1-/- EFs to undergo apoptosis when combined with a block to cell proliferation or treated by anticancer drugs or ionizing radiation. Hence, IRF-1 may be a critical determinant of oncogene-induced cell transformation or apoptosis.
The frequency of a concomitant early esophageal cancer in male patients with oral and oropharyngeal cancer. Screening results using Lugol dye endoscopy.
BACKGROUND: Male patients with oral and oropharyngeal cancer are known to have high risk of concomitant esophageal cancer developing. Thus, mass screening programs are pursued to detect such esophageal cancer early, and in a mass screening trial of patients with early oral and oropharyngeal cancer, the efficacy of Lugol dye endoscopy for detecting concomitant esophageal cancers has been evaluated. METHODS: Lugol dye was used in an endoscopic screening of 101 patients with oral cancer and 26 with oropharyngeal cancer; all of the patients were men. RESULTS: Among these 127 patients, eight (6.3%) clinical asymptomatic concomitant esophageal cancers were detected, and four of these eight cancers were found in the patients with oropharyngeal cancer. Five of these eight superficial lesions could not be detected by ordinary endoscopy or barium study. CONCLUSION: Our results show that Lugol dye endoscopy is indispensable for monitoring male patients with oral or oropharyngeal cancer to detect an early concomitant esophageal cancer. In addition, a higher frequency of concomitant esophageal cancer was seen in the patients with oropharyngeal cancer than in the patients with oral cancer.
Immunological characterization of pancreatic stone protein in human urine.
In order to study the mechanism and origin of urine pancreatic stone protein (PSP), PSP was analyzed in the urine and sera from healthy subjects, patients with renal disease, and intensive care patients by Mono S chromatography and Western blotting. The elution patterns could be classified into three types. In control urine, a single peak of immunoreactive PSP (peak I) was identified at the position of PSP-S2-5 (type A). In three of seven patients with renal disease, another peak of urine immunoreactive PSP (peak II) was recognized at the position slower than that corresponding to that of PSP-S1 (type B). In urine from one patient with diabetic nephropathy, a third peak of immunoreactive PSP (peak III) was eluted between peaks I and II (type C). In Western blotting, the bands in urine from patients with renal disease and of those in ICU mainly appeared at the positions of high-molecular-weight types of PSP and PSP-S2-5, respectively. These results suggest that the kidney can be another major source of urine PSP in addition to the pancreas.
Renal cell carcinoma producing alpha-fetoprotein (AFP) with a unique lectins-affinity profile.
Renal cell carcinoma (RCC) producing alpha-fetoprotein (AFP) is a rare entity and merely 7 cases have been reported so far. The present case, a 71-year-old woman, showed a high serum AFP level of 204 ng/ml. The RCC of the autopsied right kidney consisted mainly of spindle-shaped or bizarre sarcomatous tumor cells. AFP was immunolocalized only in the concomitant clear cell component. Concanavalin A (Con A)-nonadsorption rate of serum AFP was 42%, which was an intermediate value between those of yolk sac tumors and metastatic liver carcinomas. Lens culinalis agglutinin (LCA)-affinity study of the patient's AFP showed an unknown peak X, which was eluted between the known peaks 2 and 3. These results suggest a certain structural alteration in carbohydrate moieties of the AFP derived from this RCC. A review of the clinicopathologic features of 8 patients with AFP-producing RCC was made to understand the pathophysiology of AFP-producing neoplasms.
Trypsin(ogen) content of pancreatic calculi in chronic calcified pancreatitis in man.
Protein analysis of intraductal precipitates and calculi is important to elucidate the mechanism of stone formation in chronic pancreatitis. We revealed human cationic trypsin immunoreactivity in protein extracts of pancreatic stones from 11 of 13 patients with chronic calcified pancreatitis, ranging from 0 to 42.3 ng/micrograms protein. On gel filtration the immunoreactivity eluted as one peak, which is identical to that of human cationic trypsinogen. On immunostaining of pancreatic stone, using an immunogold technic and scanning electron microscopy, the immunoreactivity was observed more densely in the amorphous portion of the center of the stones than in the concentric laminar layer of the periphery. Only negligible activity was detected for elastase 1 or amylase in the stone extracts. These results suggest that the presence of trypsinogen in pancreatic stone is not due to coprecipitation or adsorption of pancreatic enzymes but that trypsinogen is more likely involved in an initial step of intraductal precipitate formation than in a subsequent step of stone formation. However, the absence of trypsinogen in the stones from two of the 13 patients also suggests that trypsinogen is not the sole protein initiating precipitate formation.
Immunolocalization of platelet-derived growth factor, transforming growth factor-beta, and fibronectin in acute megakaryoblastic leukemia manifesting tumor formation.
Acute megakaryoblastic leukemia (AMKL) manifesting myelofibrosis and tumor formation in the liver with marked increase of reticulin is described. The megakaryoblastic nature of the leukemic cells of the bone marrow and the hepatic tumor nodule was established by positive immunohistochemical stains for CD41a and CD41b on frozen tissue sections. Immunolocalization of the platelet-derived growth factor (PDGF) protein and transforming growth factor (TGF)-beta protein also was demonstrated in the leukemic cells of the bone marrow and the hepatic tumor. Further, the deposition of fibronectin that has been known as the ligand of CD41a molecule and collagen types I and IV were recognized in the extracellular matrix of the bone marrow and the hepatic tumor. These results suggest that specific expression of growth factor proteins by the leukemic cells may selectively regulate the fibrosis of the bone marrow as well as the tumor formation of AMKL. The expression of adhesion molecules and growth factor proteins by the leukemic cells and the deposition of extracellular matrix are discussed in relation to the myelofibrosis as well as the tumor-forming nature of AMKL.
Safety evaluation of lipase G from Penicillium camembertii.
Lipase G, a partial glycerides eliminating enzyme produced by Penicillium camembertii, was subjected to safety evaluation studies to establish its safety when used as a processing aid in the food industry. The toxicological studies on the enzyme included a 90-day gavage study with rats, a mutagenicity study using bacteria, and a pathogenicity study using mice. The no-adverse-effect level from the 90-day gavage toxicity study was 2000 mg/kg body weight/day for rats. There was no evidence of mutagenic potential. The micro-organism was evaluated for pathogenicity using mice and classified as a non-pathogen. Results indicate that the production and use of lipase G may be regarded as safe for the enzyme production worker and the consumer.
Effect of oxetanocin G, a novel nucleoside analog, on DNA synthesis by hepatitis B virus virions.
The novel nucleoside oxetanocin G, 9-(2-deoxy-2-hydroxymethyl-beta-D-erythro-oxetanosyl)guanine (OXT-G), that is a derivative of oxetanocin A, was studied in relation to its action on the synthesis of hepatitis B virus (HBV) DNA and cellular DNA in an HBV-producing cell line, HB611 (T. Tsurimoto, A. Fujiyama, and K. Matsubara, Proc. Natl. Acad. Sci. USA 84:444-448, 1987). The median effective concentration of OXT-G against HBV replication was 1.5 microM, and the median cytotoxic concentration was more than 1,000 microM. At the same concentration, OXT-G did not inhibit cellular DNA synthesis or viral RNA synthesis. Chemically synthesized OXT-GTP inhibited the HBV endogenous DNA polymerase reaction and was incorporated into HBV DNA strands at a low efficiency compared with the incorporation of dGTP. A synthetic primer-template study revealed that OXT-GTP was incorporated into DNA strands at a low efficiency and that further extension of the DNA strand by using the 2' position of the incorporated OXT-G could take place.
A useful diagnostic method for drug-induced pneumonitis: a case report.
A 51 year-old male was admitted to our hospital with chief complaints of fever, dry cough and dyspnea. Chest X-ray films and his history of taking Chinese medicine for liver dysfunction were suggestive of drug-induced pneumonitis. Lymphocyte stimulation test (LST) to causative Chinese medical drugs of Sho-saiko-to and Dai-saiko-to was negative with peripheral blood lymphocytes (PBL), but was positive with lymphocytes from bronchoalveolar lavage fluid (BALF). In vivo challenge test for Sho-saiko-to was positive. The LST with BALF-lymphocytes proved to be very useful in making a diagnosis of drug-induced pneumonitis.
Monitoring serum tryptic activity and effect of trypsin inhibitor on rat acute pancreatitis.
The effect of a novel synthetic trypsin inhibitor, 4-(2-succinimidoethylthio)-phenyl 4-guanidinobenzoate methanesulfonate (E3123), on severe acute pancreatitis was studied in trypsin-taurocholate-induced acute experimental pancreatitis in rats. Rats were divided into four groups according to difference of subdivided doses of E3123 with fixing the total dose at 3 mg/kg body weight. Group A: 1.5 mg/kg of E3123 subcutaneously (SC) each at 1 h before and after induction of pancreatitis. Group B: 1 mg/kg SC each at 1 h before, 1 and 3 h after induction. Group C: 1.5 mg/kg SC each at 1 and 3 h after induction. Group D: 1.5 mg/kg SC each at 3 and 5 h after induction of pancreatitis. The survival rate at 24 h was significantly improved in group B (77% in group B, vs. 36% in paired control; p < 0.01) and in group C (70 vs. 38%; p < 0.05), but not in group A or D. Residual tryptic activity of serum alpha 2-macroglobulin trypsin complex (alpha 2M-TRY) was reduced after the injection of E3123 though immunoreactive trypsin remained unchanged in the early phase of pancreatitis. The reduction of alpha 2M-TRY reflected the inhibitory capacity of E3123 in plasma. E3123 showed favorable effects on the initial stage of severe acute pancreatitis and the effects were probably based on the inhibition of alpha 2M-TRY activity in serum.
Regulation of pancreatic polypeptide release is mediated through M3 muscarinic receptors.
The purpose of this study was to determine the regulation of pancreatic polypeptide (PP) release by using pirenzepine (a specific M1 muscarinic receptor antagonist), 4-diphenylacetoxy-N-methylpiperidine methobromide (4-DAMP, a specific M3 muscarinic receptor antagonist), atropine (a nonspecific muscarinic receptor antagonist), and loxiglumide (cholecystokinin, CCK, receptor antagonist) in dogs. In conscious dogs with chronic gastric and duodenal fistulas, release of PP and exocrine pancreatic secretion were stimulated by constant intravenous infusion of CCK-8 (200 ng/kg/h). Graded doses of pirenzepine (0.18-4.7 mmol/kg/h), 4-DAMP (6.7-180 nmol/kg/h), or atropine (0.89-24 nmol/kg/h) dose-dependently reduced plasma PP responses to CCK-8 without influence on exocrine pancreatic secretion. ID50 calculated from these results were 492 +/- 150 nmol/kg/h for pirenzepine, 10.7 +/- 1.8 nmol/kg/h for 4-DAMP and 19.4 +/- 5.2 nmol/kg/h for atropine. A similar sequence in the inhibitory potency was observed in 2-deoxy-D-glucose (2-DG, 100 mg/kg)-stimulated PP release, exocrine pancreatic, and gastric secretions. On the other hand, loxiglumide, a CCK receptor antagonist, did not influence PP release stimulated by 2-DG. These findings suggest that both CCK- and 2-DG-stimulated PP releases are mainly under cholinergic nerve control mediated by M3 muscarinic receptor in dogs.