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H Nagase

Publications and source records attributed to H Nagase.

At least 361 records · Page 20Linked to original sources
PubMed1993

Modulation of insulin secretion by hepatic vagotomy in cirrhotic rats.

There is evidence that glucose sensors and arginine sensors are present in the hepato-portal system and exert a reflex regulation of the pancreatic neuroendocrine system in normal rats. To investigate the function of these sensor systems in liver cirrhosis, we examined the effect of hepatic vagotomy on plasma glucose and insulin concentrations after intraperitoneal (IP) injection of glucose or L-arginine in carbon tetrachloride (CCl4)-induced cirrhotic rats. After IP glucose injection, hepatic vagotomy decreased plasma insulin with elevation of plasma glucose in control rats; however, in cirrhotic rats, this procedure did not affect either plasma glucose or insulin concentrations. After IP arginine injection, hepatic vagotomy increased plasma insulin and reduced plasma glucose in control rats, although in cirrhotic rats, this procedure did not affect plasma glucose but did increase plasma insulin concentrations. These results suggest that function of the glucose sensor in CCl4-induced cirrhotic rats is disturbed, although that of the arginine sensor is retained.

Afferent Pathways↗
PubMed1993

Hypergastric acid secretion in rats with ventromedial hypothalamic lesions.

This study was designed to investigate abnormal gastric acid secretion in ventromedial hypothalamic (VMH)-lesioned rats. Basal secretion and secretion stimulated by pentagastrin (25 micrograms/kg, IP) or histamine (2 mg/kg/h, IV) were significantly higher in VMH-lesioned rats than in sham VMH-lesioned rats. Subdiaphragmatic vagotomy and methyl atropine treatment (5 mg/kg, IV) remarkably decreased both basal (about 36-44%) and stimulated secretion (about 36-67%) in VMH-lesioned rats, but did not completely reverse it to normal. Serum insulin and glucose levels were significantly higher in VMH-lesioned rats, but serum gastrin levels were not. VMH-lesioned rats showed significantly heavier gastric dry weight; however, no difference in the mucosal layer/total layer ratio of the gastric wall and the density of the parietal cells was observed between the two groups, indicating that the total number of parietal cells might have increased in VMH-lesioned rats because the increase of gastric dry weight can be presumed to be due to increase of the gastric mucosal layer as well as total layer. These results suggest that vagal activation is one of the main contributors to hypergastric acid secretion in VMH-lesioned rats, but that other factors such as increase of parietal oxyntic cell number may also contribute.

Animals↗
PubMed1993

Isolation of substances from glossy privet (Ligustrum lucidum Ait.) inhibiting the mutagenicity of benzo[a]pyrene in bacteria.

Methanol and hot-water extracts of glossy privet (Ligustrum lucidum Ait.) inhibited the mutagenic activity of benzo[a]pyrene in Salmonella typhimurium TA98 with S9 mix. The methanol extract was fractionated with ether and n-hexane. As the active components, oleanolic and ursolic acids were isolated, which were soluble in ether and insoluble in n-hexane. The hot-water extract was fractionated to water, 60% and 100% methanol fractions. Nuezhenide was isolated from the 60% methanol fraction as the active component.

Antimutagenic Agents↗
PubMed1993

The mutagenicity of organotin compounds as environmental pollutants.

The mutagenicity of 14 organotin compounds which have been reported to be environmental pollutants, their environmental metabolites and inorganic tin (SnCl4) was studied. The experiments were carried out by a modification of the conventional Salmonella assay. Each tested chemical was removed by washing the tested strain with phosphate buffer, before the strain with top agar was poured onto minimal glucose agar. By this method, we were able to estimate the mutagenicity of organotin compounds which had antibacterial activity. It was apparent that mono-n-butyltin oxide, n-butyltin trichloride, di-n-butyltin dichloride, tri-n-butyltin chloride, bis-(tri-n-butyltin)-oxide and dimethyltin dichloride were mutagens on Salmonella typhimurium TA100 and bis-(tri-n-butyltin)-oxide showed the highest mutagenicity. With S. typhimurium TA98, di-n-butyltin dichloride was found to be a mutagen.

Environmental Pollutants↗
PubMed1993

Hepatic vagal amino acid sensors modulate amino acid induced insulin and glucagon secretion in the rat.

To clarify the physiological role of vagal amino acid sensors in the liver, the effect of hepatic vagotomy and/or celiac vagotomy (sectioning of the hepatic branch and/or the celiac branches of the vagus nerve) on the secretion of insulin and glucagon after intraperitoneal injection of neutral (L-alanine, L-leucine, and L-phenylalanine), acidic (L-glutamate), or nonmetabolized (cycloleucine) acids, was examined in rats. Hepatic vagotomy enhanced both plasma glucose and glucagon concentrations after intraperitoneal injection of alanine more than those in sham-vagotomized (control) rats, while after intraperitoneal injection of leucine, hepatic vagotomy decreased plasma glucose concentrations and enhanced plasma insulin concentrations more than in control animals. These effects, following both alanine and leucine administration, were blocked by celiac vagotomy. Glutamate, phenylalanine, and cycloleucine stimulation in hepatic-vagotomized rats caused no significant differences in plasma glucose, insulin, or glucagon levels as compared to those in sham-vagotomized rats. Celiac vagotomy alone did not affect plasma glucose, insulin, or glucagon concentrations after stimulation by these five amino acids. The physiological role of alanine and leucine sensors may be to prevent amino acid-induced exaggerated pancreatic hormone secretion and to maintain blood glucose homeostasis, while glutamate, phenylalanine, and cycloleucine have no effect on this pancreatic neuroendocrine system.

Amino Acids↗
PubMed1993

Effects of hypothyroidism with treatment of an anti-thyroid drug, propylthiouracil on immune responses in chickens.

The effect of a wide range of doses of propylthiouracil (PTU, 0.01-5%) on the immune responses of young male chickens was examined. One-day-old chickens were rendered hypothyroid by PTU supplemented in the feed for 4 weeks. At all doses PTU treatment caused a significant dose-related reduction in body weight (except at 0.01%) and in relative lymphoid organ weights. Skin response to phytohemagglutinin (PHA) was significantly greater in the chickens treated with low doses of PTU (0.01-0.1%) and significantly less in the chickens treated with high doses of PTU (1.5-5%) than that in control chickens. Number of splenic plaque forming cells (PFC) to sheep red blood cells (SRBC) was significantly increased in the chickens treated with low doses of PTU. Concentrations of serum 3,3',5-triiodothyronine (T3) and thyroxin (T4) were significantly lower in the chickens treated with all doses of PTU. Addition of T3 to the feed supplemented with 0.01% PTU replaced the serum T3 concentration and reduced the skin response to PHA and the number of the splenic PFC. These data confirm our previous observations that a low dose of PTU enhances and a high dose suppresses the immune responses of young male chickens.

Adrenal Glands↗
PubMed1993

Multiple forms of the APC gene transcripts and their tissue-specific expression.

We have detected multiple forms of RNA transcript from APC, the gene which is responsible for familial adenomatous polyposis (FAP). Transcriptional initiation occurs at three sites in two distinct non-translating exons at the 5' end of the gene. At least five different forms of 5' non-coding sequences, generated by alternative splicing, exist. The splicing mechanism seems to be regulated in a tissue-specific fashion, and one type of transcript contained an additional exon, which was transcribed specifically in brain. Analyses of mRNAs from two colorectal-tumor cell lines by reverse-transcriptase polymerase chain reaction (RT-PCR) revealed that one or another of the transcriptional forms was absent in both cell lines. This observation suggested the presence of mutations in the control region or the first exon of APC, or that mutation(s) could have affected the splicing efficiency or transcriptional initiation of the gene in these tumors. Furthermore, we found that the alternative splicing involving the 19 kDa protein of signal recognition particle (SRP19) gene, that is known to occur at exon 14 of APC, is also controlled in a tissue-specific manner, and one type of transcript lacked in some organs.

Adenomatous Polyposis Coli↗
PubMed1993

Evaluation of molecular genetic diagnosis in the management of familial adenomatous polyposis coli: a population based study.

A population based clinical and molecular genetic study of familial adenomatous polyposis coli (FAPC) was performed to investigate the value of molecular genetic analysis and ophthalmological assessment in the presymptomatic diagnosis of FAPC. The point prevalence of affected patients was 2.62 x 10(-5) (1/38,000) and the minimum heterozygote prevalence was estimated at 3.8 x 10(-5) (1/26,000). Eight of 33 (24%) probands were new mutations. Forty-eight asymptomatic relatives at 50% prior risk aged between 10 and 40 years were assessed for risk modification with linked DNA markers: in nine subjects (18%) the family structure was unsuitable for linkage based analysis, but 32 subjects were informative with a panel of intragenic and closely linked markers (25 had a combined age/DNA related risk of < 1% (low risk group) and seven were at high risk (DNA predicted risk > 99%)). Ophthalmological assessment for CHRPEs showed that 27/43 (63%) affected patients and high risk relatives and 0/18 low risk relatives had more than three CHRPEs. Interfamilial variation in CHRPE expression was apparent. This study has shown that DNA based risk modification with intragenic and closely linked DNA markers is informative in most FAPC families. In addition to the clinical benefits of presymptomatic diagnosis for FAPC, the reduction in screening for low risk relatives (365 person years in the present study) means that molecular genetic diagnosis of FAPC is a cost effective procedure.

Adenomatous Polyposis Coli↗
PubMed1993

Effects of kappa-agonist on the antinociception and locomotor enhancing action induced by morphine in mice.

The antinociception of intracerebroventricular injection (i.c.v.) of morphine was markedly abolished by pretreatment with naloxonazine (micro 1-antagonist), s.c.; beta-funaltrexamine (micro 1/micro 2-antagonist), i.c.v.; DSP-4 (noradrenaline neurotoxin), s.c.; or p-chlorophenylalanine (serotonin synthesis inhibitor), s.c. in the mouse 55 degrees C hot-plate assay. Pretreatment with nor-binaltorphimine (kappa-antagonist), i.c.v. or PCPA, s.c. drastically blocked the kappa-agonist U-50,488H-induced supraspinal antinociception. These findings indicate either noradrenergic or serotonergic involvement in the mediation of the antinociceptio of i.c.v.-morphine through mu-receptors. On the contrary, the antinociception of i.c.v.- U-50,488H through kappa-receptors appears to depend on the serotonergic but not noradrenergic systems. The antinociceptive interaction between the i.c.v.-morphine and -U-50,488H was an additive effect. On the other hand, i.c.v.-morphine dose-dependently increased the locomotion in mice, and this hyperlocomotion of morphine was drastically blocked by pretreatment with either beta-funaltrexamine, i.c.v. or 6-hydroxydopamine (dopamine depletor), i.c.v. I.c.v.-U-50,488H dose-dependently reduced the increasing locomotion of i.c.v.-morphine, but not that of s.c.-apomorphine (dopamine receptor agonist), and this effect of U-50,488H was completely reversed by pretreatment with nor-binaltorphimine, i.c.v. These results suggest that coadministration of kappa-agonists can suppress the dopamine-related hyperlocomotion of mu-agonists without decreasing the anti-nociception of mu-agonists in mice.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1993

Production of matrix metalloproteinase 1 (interstitial collagenase) and matrix metalloproteinase 2 (gelatinase A: 72 kDa gelatinase) by ovine endometrial cells in vitro: different regulation and preferential expression by stromal fibroblasts.

Ovine endometrial cells (epithelial plus stromal), prepared from ovariectomized ewes treated with oestrogen and progesterone to mimic the luteal phase of the oestrous cycle were maintained in serum-free medium for 48 h in the presence or absence of phorbol myristate acetate (PMA, 100 nmol l-1), a known stimulus for production of matrix metalloproteinases (MMP) in other cells. Matrix metalloproteinase-1 (MMP-1, interstitial collagenase) and matrix metalloproteinase-2 (MMP-2, gelatinase A) activities were expressed by the cells in the absence of PMA; most were in the latent form and required activation by (4-aminophenyl) mercuric acetate (APMA). Exposure to PMA over 48 h resulted in a significant increase in MMP-1 activity but only a modest and nonsignificant increase in MMP-2 activity. Gelatin zymography demonstrated that proMMP-2 (72 kDa) was produced by both PMA-treated and untreated cells and an active form of 67 kDa was also present. Immunolocalization of MMP-1 and MMP-2 was seen within the cells following treatment with monensin. Highly purified epithelial and stromal cells were similarly cultured and analysis of the conditioned medium showed that MMP-1 and MMP-2 were produced predominantly by stromal rather than epithelial cells. Thus, both MMP-1, which degrades interstitial collagens, and MMP-2, an important enzyme for degradation of type IV and V collagens, are synthesized and released by ovine endometrial stromal cells in culture, but MMP-1 is produced primarily upon stimulation, whereas MMP-2 production is constitutive.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Frequent somatic mutations of the APC gene in human pancreatic cancer.

The APC (adenomatous polyposis coli) gene is responsible for familial adenomatous polyposis and is also associated with the development of sporadic tumors of the colon and stomach. To investigate whether or not mutations of APC play any role in tumors arising in other organs, we examined somatic mutations of this gene in sporadic (nonfamilial) renal cell carcinomas, hepatocellular carcinomas, and cancers of the lung and pancreas. DNAs isolated from tumors were examined by means of a RNase protection analysis, coupled with the polymerase chain reaction followed by DNA sequencing of the polymerase chain reaction products. By screening a part of the APC coding region, we detected somatic mutations in four of ten pancreatic cancers; each of these mutations would yield a truncated APC product due to a 1- or 5-base pair deletion. These results imply that mutations in APC contribute to carcinogenesis in the pancreas.

Base Sequence↗
PubMed1992

Role of central ATP-sensitive potassium channels in the analgesic effect and spinal noradrenaline turnover-enhancing effect of intracerebroventricularly injected morphine in mice.

Glibenclamide is one of the most potent sulfonylurea-derived antidiabetic drugs which block the adenosine triphosphate-sensitive potassium (KATP) channels. In the present study, we found that none of morphine, U-50,488H (a selective kappa agonist) and baclofen (a selective GABAB agonist) added to the incubation medium at concentrations up to 10(-4) M had appreciable effect on the specific binding of [cyclohexyl-2,3-3H(N)]glibenclamide ([3H]glibenclamide) to the isolated mouse brain microsomes. The analgesic activity induced by intracerebroventricular injection (i.c.v.) of morphine but not U-50,488H was antagonized by pretreatment with either i.c.v. glibenclamide or beta-funaltrexamine (beta-FNA; a selective mu antagonist) in mice. Furthermore, the increasing effect of i.c.v. morphine on the spinal noradrenaline (NA) turnover was greatly antagonized by i.c.v. pretreatment with either beta-FNA or glibenclamide. From these results, we demonstrated that KATP channels play an important role as indirect modulators of the supraspinal analgesia induced by mu agonist but not kappa agonist in mice, and the activation of descending noradrenergic system induced by i.c.v. morphine appears to be suppressed by the blockade of KATP channels.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1992

Tetronothiodin, a novel CCKB receptor ligand, antagonizes cholecystokinin-induced Ca2+ mobilization in a pituitary cell line.

We found a novel nonpeptide CCKB receptor antagonist, tetronothiodin (Ro 09-1468), in the culture broth of Streptomyces sp. NR0489. The structure of the compound (C31O8H38S), which has a 19-membered ring with an alpha-acyltetronic acid and tetrahydrothiophene moiety, is completely different from that of any known CCK receptor antagonist. Tetronothiodin inhibited [125I]CCK-8 binding to rat brain CCKB receptors with an IC50 of 3.6 nM, whereas it showed only weak affinity for rat CCKA receptors (IC50 = 70 microM). As demonstrated autoradiographically, tetronothiodin concentration dependently inhibited [125I]CCK-8 binding to CCKB receptors in rat forebrain slices. The effects of tetronothiodin on cytosolic Ca2+ concentrations in GH3 cells, a rat anterior pituitary tumor cell line, were investigated with the fura-2 method. Tetronothiodin inhibited CCK-8-induced Ca2+ mobilization without affecting basal cytosolic Ca2+ concentrations. In conclusion, tetronothiodin is a new, potent and highly selective CCKB receptor antagonist. It is a useful tool for investigating the pharmacological and physiological roles of CCKB receptors.

Animals↗
PubMed1992

A highly selective delta 1-opioid receptor antagonist: 7-benzylidenenaltrexone.

In guinea pig brain membranes 7-benzylidenenaltrexone (BNTX) possesses 100-fold greater affinity (Ki = 0.1 nM) for [3H]DPDPE [3H][D-Pen2,D-Pen5]enkephalin) binding sites (delta 1) relative to those of [3H]DSLET ([3H][D-Ser2,Leu5]enkephalin-Thr6) (delta 2). The ED50 dose ratio (tail flick) in mice for the antagonism of DPDPE-induced antinociception of BNTX (6.3 pmol i.c.v.) was 7.2, whereas for DSLET, morphine and U69593 it was not significantly different from unity. The fact that there was no correlation of the binding or in vivo data for BNTX with antagonist potency in smooth muscle preparations suggests that the in vitro pharmacologic activity is mediated by delta-opioid subtypes that are different from those in the brain.

Animals↗
PubMed1992

Purification and characterization of matrix metalloproteinase 9 from U937 monocytic leukaemia and HT1080 fibrosarcoma cells.

The precursor of matrix metalloproteinase 9 (proMMP-9), also known as '92 kDa progelatinase/type IV procollagenase', was purified from the conditioned medium of U937 monocytic leukaemia and HT1080 fibrosarcoma cell lines stimulated with phorbol 12-myristate 13-acetate. ProMMP-9 in these culture media is non-covalently complexed with the 29 kDa tissue inhibitor of metalloproteinases (TIMP), but free proMMP-9 was separated from the TIMP-proMMP-9 complex by chromatography on Green A Dyematrex gel. The final product was homogeneous on SDS/PAGE, with a molecular mass of 88 kDa without reduction and 92 kDa with reduction. Treatment of proMMP-9 with 4-aminophenylmercuric acetate converted the 88 kDa precursor into 80 kDa and 68 kDa forms. Gelatin-containing zymographic analysis showed zones of lysis associated with all three species. However, only the 68 kDa species was shown to be catalytically active by its ability to bind to alpha 2-macroglobulin. In the presence of an equimolar amount of TIMP, only the 80 kDa species was generated by treatment with 4-aminophenylmercuric acetate, but no enzyme activity was detected. This indicates that TIMP binds to the 80 kDa intermediate and inhibits the generation of the active 68 kDa species. Eight endopeptidases (trypsin, chymotrypsin, plasmin, plasma kallikrein, thrombin, cathepsin G, neutrophil elastase and thermolysin) were tested for their ability to activate proMMP-9. Of them, trypsin was the most effective activator of proMMP-9. Only partial activation (10-30%) was observed with plasmin, cathepsin G and chymotrypsin. The active forms generated by trypsin were identified as 80 kDa, 74 kDa and 66 kDa by their abilities to bind to alpha 2-macroglobulin. In the presence of an equimolar amount of TIMP, proMMP-9 was also converted into the same molecular-mass species by trypsin, but they were not proteolytically active. This suggests activated MMP-9 is inhibited by TIMP. Activated MMP-9 digested gelatin, type-V collagen, reduced carboxymethylated transferrin and, to a lesser extent, type-IV collagen and laminin A chain. The specific activity against gelatin was estimated to be 15,000 units/mg (1 unit = 1 microgram of gelatin degraded/min at 37 degrees C) by titration with alpha 2-macroglobulin. Comparative studies on digestion of gelatin and collagen types IV and V by MMP-9 and MMP-2 indicated that both enzymes degrade these substrates into similar fragments. However, the susceptibilities of laminin, fibronectin and reduced carboxymethylated transferrin to these two MMPs were sufficiently different to indicate differences in substrate specificities between these two closely related proteinases.

Electrophoresis, Polyacrylamide Gel↗
PubMed1992

Correlation between the location of germ-line mutations in the APC gene and the number of colorectal polyps in familial adenomatous polyposis patients.

Recently we have isolated the adenomatous polyposis coli (APC) gene which causes familial adenomatous polyposis (FAP), and its germ-line mutations in a substantial number of FAP patients have been identified. On the basis of this information, we compared the location of germ-line mutations in the APC gene in 22 unrelated patients (12 of whom have been reported previously) with the number of colorectal polyps developed in FAP patients; 17 were sparse types and five were profuse types. All but one of the mutations were considered to cause truncation of the gene product by frame-shift due to deletion (14 cases) or nonsense mutation (seven cases). The location of the germ-line mutations seems to correlate with the two clinical types; germ-line mutations in five FAP patients with profuse polyps were observed between codon 1250 and codon 1464, whereas mutations in 17 FAP patients with fewer polyps were observed in the other regions of the APC gene. The result suggests that the number of colorectal polyps in FAP patients may be associated with a difference in the stability or biological function of the truncated APC protein.

Adenomatous Polyposis Coli↗