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Biomedical subjects

H Ueda

Publications and source records attributed to H Ueda.

At least 757 records · Page 42Linked to original sources
PubMed1987

A Met-enkephalin releaser (kyotorphin)-induced release of plasma membrane-bound Ca2+ from rat brain synaptosomes.

The neuropeptide kyotorphin (Tyr-Arg) released 45Ca2+ from synaptosomal membrane preparations of the rat lower brainstem. This dipeptide also decreased plasma membrane-bound Ca2+ ([Ca2+]m), determined using chlorotetracycline, in the slice and synaptosome of the rat lower brainstem. Taken together with other data indicating that kyotorphin induces an increase in synaptosomal intracellular Ca2+ ([Ca2+]i) in a Ca2+ channel-independent manner, it is suggested that kyotorphin may mobilize the [Ca2+]m and thus increase the [Ca2+]i in the nerve terminals of the rat lower brainstem.

Analgesics↗
PubMed1987

Kyotorphin (tyrosine-arginine) synthetase in rat brain synaptosomes.

Kyotorphin (Tyr-Arg) is a unique neuropeptide which produces analgesia by releasing Met-enkephalin from slices of the brain and spinal cord. Recent studies revealed that kyotorphin possesses the properties of neurotransmitter/neuroregulator. In the present study, we identified a kyotorphin synthetase in the soluble fraction of rat brain synaptosomes (synaptosol) and characterized it. The enzyme partially purified with Sephacryl S-300 showed an absolute requirement for ATP, MgCl2, tyrosine, and arginine. The optimal pH was 7.5-9.0 and the pI was determined to be 6.1-6.2 by isoelectric focusing. The Km was 25.6 microM for tyrosine, 926 microM for arginine, 294 microM for ATP, and 442 microM for MgCl2. The Vmax was 34.0 pmol/mg of protein/h. The apparent molecular size of this "kyotorphin synthetase" further purified by the DE52 column was 240,000-245,000 daltons, estimated using TSKgel G4000SW column chromatography. The enzyme reaction is represented by the following equation: Tyr + Arg + ATP + MgCl2 + kyotorphin synthetase----Tyr-Arg (kyotorphin) + AMP + PPi + MgCl2 + kyotorphin synthetase. The regional distribution and subcellular localization of the synthetase showed a close correlation to that of kyotorphin levels in the rat brain. The amounts of kyotorphin formed from amino acids by the synthetase in the dialyzed synaptosol was 3.0-4.0 times higher than that from precursor proteins by processing enzymes within the 30 min incubation.

Analgesics↗
PubMed1987

The specific opioid kappa-agonist U-50,488H inhibits low Km GTPase.

DAGO, a specific opioid mu-agonist stimulated the low Km GTPase activity of membranes of the guinea-pig striatum at 1-1000 nM and this effect was antagonized by naloxone 10-100 nM. On the other hand, U-50,488H, a specific opioid kappa-agonist inhibited the low Km GTPase activity of membranes of the guinea-pig cerebellum at 1-100 nM. As this effect was antagonized by MR2266 but not by naloxone, the findings suggest that opioid mu- and kappa-receptor stimulation is probably linked to the stimulation and inhibition of low Km GTPase, respectively.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1987

Tissue-specific and periodic changes in the nuclease sensitivity of the fibroin gene chromatin in the silkworm Bombyx mori.

Nuclei of substantial purity were isolated from the middle or posterior silk glands of the silkworm Bombyx mori larvae. Both the fibroin H- and L-chain gene sequences in the isolated nuclei from the posterior silk glands of the fifth instar larvae, where the genes are transcribed actively, are extremely sensitive to the digestion with DNaseI; on the other hand, these sequences in the middle silk gland nuclei from the same larvae, where the genes are not expressed, are markedly resistant to the digestion. The H-chain gene sequences in the posterior silk gland nuclei from the fifth instar larvae are also highly susceptible to the digestion with micrococcal nuclease, HinfI, and HhaI. The digestion products with micrococcal nuclease show a continuous size distribution. The H-chain gene sequences in the middle silk gland nuclei or the posterior silk gland nuclei from the fourth molting stage are cleaved partially into nucleosome dimer to oligomer sizes upon digestion with higher concentrations of micrococcal nuclease, suggesting that the inactive forms of the H-chain gene chromatin are constructed by folding of the chromatin fiber containing a regular array of nucleosomes. Hypersensitive sites to micrococcal nuclease are present near both ends of the second exon, a major body of the fibroin H-chain gene, in both the active and inactive forms of the chromatin. The DNaseI or micrococcal nuclease sensitivity of the H-chain gene chromatin in the posterior silk gland nuclei shows periodical changes corresponding to the intermolt-molt-intermolt cycle.

Animals↗
PubMed1987

Purified opioid mu-receptor is of a different molecular size than delta- and kappa-receptors.

Opioid mu-receptors were solubilized from rat brains with 0.5% Triton X-100 in the presence of 0.32 M sucrose and then purified with 6-succinyl morphine-Affi-Gel 102 column. Purified materials showed a major band with mol.wt. 58,000 Da and a minor band with mol.wt. 41,000 Da. Affinity cross linking with [3H]DAGO, a selective mu-opioid agonist, to the neural membranes and purified materials revealed that opioid mu-binding protein has a mol.wt. of 58,000 Da, a value totally different from that of delta- (mol.wt. 18,500 Da) and kappa- (mol.wt. 36,000 Da) binding protein.

Animals↗
PubMed1987

Subconvulsive doses of intracisternal bicuculline methiodide, a GABAA receptor antagonist, produce potent analgesia as measured in the tail pinch test in mice.

Bicuculline methiodide, a GABAA antagonist produced potent analgesia in the tail pinch test when it was given intracisternally (i.c.) but not intrathecally (i.t.). The ED50 was 5 ng/mouse. This analgesia was antagonized by i.c. muscimol, a GABAA agonist. On the contrary, muscimol (i.t.) produced bicuculline-reversible analgesia. These findings suggest that brain GABA may transmit the nociceptive information while GABA in the spinal cord may inhibit it.

Analgesics↗
PubMed1987

A novel proenkephalin processing carboxypeptidase and its activation by cyclic AMP dependent protein kinase.

Carboxypeptidase B-like enzymes cleaving Met-enkephalin-Arg from synaptosomes of the rat striatum purified using a DEAE-cellulose column and Met-Arg-CH-Sepharose 4B affinity column proved to be different from enkephalin-convertase, lysosomal carboxypeptidase B-like enzyme, pancreas carboxypeptidase B and carboxypeptidase Y, in effects of inhibitors and activators, pH optimum (7.5-8.5) and molecular size (50,000). This enzyme, named "Processin CP-E" was activated by cAMP dependent protein kinase, and the Vmax was increased from 4.3 to 13.3 microM/min/mg protein, while the Km (28.2 microM) was unchanged.

Animals↗
PubMed1987

Immunocytochemistry of human chorionic gonadotropin in human chorionic villi.

The immunocytochemical localization of human chorionic gonadotropin was investigated in chorionic villi from the seventh to twelfth week of gestation. By the light microscopic peroxidase-antiperoxidase technique, positive reactions of human chorionic gonadotropin were found exclusively in the syncytiotrophoblast. Immunoelectron microscopy by means of the protein A-gold technique reveals localization of the immunoreactive gold particles in two kinds of membrane-bound granular inclusions in this cell; one type is granules of 200 to 300 nm in diameter with moderate electron density and the other is large electron-dense bodies of 500 to 1000 nm. The former seems to be Golgi-derived secretory granules that play a role in the release of human chorionic gonadotropin from the syncytiotrophoblast. Although the origin of the latter is still uncertain, a certain amount of this hormone might be stored or treated by lysosomal digestion in the large bodies during these stages.

Antigen-Antibody Reactions↗
PubMed1987

The effects of Escherichia coli endotoxin as a trigger for hepatic infection of rabbits with Fusobacterium necrophorum.

To evaluate the effects of endotoxin in hepatic infection with Fusobacterium necrophorum, rabbits were given several combinations of F. necrophorum and Escherichia coli endotoxin. Severe hepatic necrosis with multiplication of F. necrophorum was induced by inoculation of endotoxin via the bile duct and following inoculation of both endotoxin and F. necrophorum. Inoculation with F. necrophorum alone, preceded by inoculation of endotoxin via the bile duct, also induced hepatic necrosis, whereas rabbits which received a single inoculation of endotoxin or F. necrophorum had only slight necrotic lesions. The pathogenetic mechanism of experimental hepatic infection with F. necrophorum is discussed.

Animals↗
PubMed1987

A novel method for the synthesis of kyotorphin, Tyr-Arg, and 3H-Tyr-Arg, catalyzed by tyrosyl-tRNA synthetase from Bacillus stearothermophilus.

A novel method of dipeptide synthesis is described that can be carried out in aqueous solution and does not require complicated protecting and deprotecting procedures. An analgesic neuropeptide named kyotorphin, H-Tyr-Arg-OH, was synthesized from unprotected tyrosine and arginine in a new enzymatic reaction catalyzed by immobilized tyrosyl-tRNA synthetase from Bacillus stearothermophilus. The reaction could be a useful tool in the syntheses of radioisotope-labeled oligopeptides to be used in receptor binding assays. 3H-Kyotorphin was prepared by this method at a yield of 72% and could be used in receptor binding assays after a single chromatographic separation.

Amino Acyl-tRNA Synthetases↗
PubMed1987

Immunocytochemistry on the localization of 5-hydroxytryptamine in monkey and rabbit taste buds.

Immuno-electron microscopy with the protein A-gold method demonstrated immunoreactive gold particles against 5-hydroxytryptamine localized in cored vesicles aggregating around presynaptic terminals of the gustatory cells in monkey and rabbit taste buds. The positive reactions were also found in the intragemmal and subepithelial nerve fibers. The role of these cored vesicles in taste transduction is still uncertain but the data strongly suggest that they may participate in a serotonergic modulation of a cholinergic synaptic transmission from the gustatory cells to the nerve endings.

Animals↗
PubMed1987

31P NMR studies on the isolated perfused mandibular gland of the rat.

Phosphorus nuclear magnetic resonance (31P NMR) was used to study energy metabolism in the rat mandibular gland. The gland was isolated, perfused arterially and set in the NMR tube. At rest, 7 resonance peaks were observed and 6 peaks identified from low field as: 1) sugar phosphates (SP) and nucleotide monophosphate (NMP), 2) inorganic phosphate (Pi), 3) creatine phosphate (PCr), 4) gamma-nucleotide triphosphate (NTP) and beta-nucleotide diphosphate (NDP), 5) alpha-NTP, alpha-NDP, NAD+, and NADH, 6) an unknown peak, and 7) beta-NTP. From the results of high performance liquid chromatography (HPLC), NTP consisted mainly of ATP and GTP, and UTP was not detected. The tissue contents of ATP and GTP in the perfused gland were determined by HPLC as 1.86 +/- 0.03 and 0.37 +/- 0.01 mmol/kg wet tissue (S.E., n = 5). From 31P NMR and HPLC data, the tissue levels of creatine phosphate, ADP, and sugar phosphates were estimated as 3.3, 0.4, and 4.2 mmol/kg wet tissue, respectively. The cessation of perfusion decreased the tissue levels of PCr and ATP and increased those of Pi and SP. On the other hand, administration of acetylcholine (1 microM), which is an optimal dose for secretion, decreased PCr and increased Pi but did not change SP. The ATP was unchanged initially and slowly decreased to the lower level during sustained secretion. These findings suggest that a sustained secretion requires more energy from ATP hydrolysis rather than initial secretion.

Acetylcholine↗
PubMed1987

[Clinicopathological study of AFP producing gastric cancer--significance of AFP in gastric cancer].

We experienced fifteen cases (3.9%) out of 387 with gastric cancer showing elevation of alphafetoprotein (AFP) in serum. In these cases AFP producing cells in primary lesion demonstrated positive for anti-AFP by means of immunohistochemical study. In this report, clinicopathological feature and clinical significance as a tumor marker of gastric cancer were discussed. Gross type showed Borrmann II and III which were located in atrophic area in the stomach. Histological type revealed papillary, moderately differentiated and poorly differentiated adenocarcinoma, all of which showed medullary growth in stroma. In clinical field, liver metastasis was observed in 12(80%) of 15 cases. In these cases, elevation of serum AFP was already observed before the detection of liver metastases by CT or Echo. Immunohistochemical study showed no difference between primary tumor and metastases, and no AFP positive cells were seen in 68 early gastric cancers without elevation of serum AFP.

Aged↗
PubMed1987

The effects in the excess administration of prostaglandin E1 on the indicator enzymes of organella membrane in gastric mucosa.

Administration of excess vitamin A to rats causes gastric ulceration. In this study the effects on the gastric mucosa of excess vitamin A and excess prostaglandin E1, alone and in combination, were studied. Prostaglandin E1 protected against ulceration by vitamin A. Vitamin A labilized marker enzymes from four different membrane systems, namely those of the lysosomes, mitochondria, endoplasmic reticulum and plasma membrane, whereas only the effect on lysosomes was prevented by prostaglandin E1. Indeed, the prostaglandin alone labilized the enzymes from plasma membrane and endoplasmic reticulum and also damaged mitochondrial membranes. Both vitamin A and prostaglandin E1 caused a reduction in the total number and an increase in irregularly-shaped mitochondria in the parietal cells and produced dilation of the endoplasmic reticulum in both parietal and chief cells. It is noteworthy that prostaglandin E1 effectively prevents ulceration by vitamin A despite the extent to which it damages these membrane systems. These findings lend support to the hypothesis that vitamin A ulceration of the gastric mucosa is mediated via release of lysosomal enzymes, following damage to the lysosomal membranes.

5'-Nucleotidase↗