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K Shiba

Publications and source records attributed to K Shiba.

At least 109 records · Page 6Linked to original sources
PubMed1995

In vivo characterization of radioiodinated 2-(4-phenylpiperidino)cyclohexanol (vesamicol) analogs: potential radioligand for mapping presynaptic cholinergic neurons.

Iodovesamicol analogs, radioiodinated at the ortho (1), meta(2) and para(3) positions of the 4-phenylpiperidine moiety, were evaluated as potential presynaptic cholinergic neuron mapping agents. Significant accumulation of m-[125I]iodovesamicol (mIV(2)) (about 3% of the injected dose) was noted in the rat brain with prolonged retention times. The accumulation of mIV(2) in the rat brain was decreased by 67% by 5 min pre-injection of dl-vesamicol(1 mumol/kg). Pre-injection of (+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperdine[(+)-3-PPP](0.75 mumol/kg) did not markedly decrease the levels of radiotracers (oIV(1) and mIV(2)) in the rat brain. These results suggest that radioidinated m-iodovesamicol (mIV(2)) is suitable for use in presynaptic cholinergic neuron mapping.

Animals↗
PubMed1995

Atypicality of several antipsychotics on the basis of in vivo dopamine-D2 and serotonin-5HT2 receptor occupancy.

An in vivo receptor binding technique was used to evaluate the binding profiles of typical and atypical antipsychotic drugs to striatal dopamine-D2 and frontal serotonin-5-HT2 receptors in a rat brain using more specific ligands than those previously employed. [3H]-YM-09151-2 or [3H]-ketanserin was injected into the tail vein 10 minutes after administration of test drugs. One hour after the ligand injection, radioactivities in the striatum, frontal cortex, and cerebellum were counted to obtain receptor occupancies by the test drugs. Higher ratios of potency in occupying 5-HT2 versus D2 receptors were found for clozapine, RMI-81512, and tiospirone compared to haloperiodol and pimozide. Zotepine, mosapramine, and clocapramine produced ratios that fall between these two groups. Chlorpromazine was exceptional as a typical antispychotic by these criteria. Relatively strong antagonism of 5-HT2 receptors by atypical antipsychotics was confirmed by this in vivo measure of receptor binding using more selective ligands than those used in previous studies.

Animals↗
PubMed1995

Dual-tracer autoradiography using 125I-iomazenil and 99Tcm-HMPAO in experimental brain ischaemia.

To investigate the utility of neuroreceptor imaging in ischaemic cerebrovascular disorders, dual-tracer autoradiography using 99Tcm-hexamethylpropyleneamine oxime (HMPAO) for the evaluation of cerebral blood flow and 125I-iomazenil for the evaluation of central-type benzodiazepine receptor density was performed in experimental brain ischaemia created by occlusion of the unilateral middle cerebral artery of the rat. In the acute phase of ischaemia, 125I-iomazenil accumulation showed less of a decrease than 99Tcm-HMPAO in the cerebral cortex of the lateral convexity and in the lateral segment of the caudate putamen in the lesioned cerebral hemisphere. In the sub-acute phase, both 125I-iomazenil and 99Tcm-HMPAO accumulation increased in the lesion compared with the acute phase. A large accumulation of 99Tcm-HMPAO and 125I-iomazenil in the lesion was considered to be due to luxury perfusion and penetration of 125I-iomazenil hydrophilic metabolites from the blood into the brain tissue through the altered blood-brain barrier. In the chronic phase, 125I-iomazenil accumulation showed a more marked decrease than 99Tcm-HMPAO in the lesion. Moreover, the ipsilateral thalamus, which is remote from the lesion, revealed decreased 125I-iomazenil accumulation despite normal 99Tcm-HMPAO accumulation. Since the central-type benzodiazepine receptors are principally located not on the glial cells but on the neurons, the receptor density may exhibit a change that parallels the neuron density. These results suggest that central-type benzodiazepine receptor imaging is useful for the evaluation of neuronal damage when used in conjunction with brain perfusion imaging in ischaemic cerebrovascular disorders, except in the sub-acute phase.

Acute Disease↗
PubMed1995

Inositol monophosphatase activity from the Escherichia coli suhB gene product.

The suhB gene is located at 55 min on the Escherichia coli chromosome and encodes a protein of 268 amino acids. Mutant alleles of suhB have been isolated as extragenic suppressors for the protein secretion mutation (secY24), the heat shock response mutation (rpoH15), and the DNA synthesis mutation (dnaB121) (K. Shiba, K. Ito, and T. Yura, J. Bacteriol. 160:696-701, 1984; R. Yano, H. Nagai, K. Shiba, and T. Yura, J. Bacteriol. 172:2124-2130, 1990; S. Chang, D. Ng, L. Baird, and C. Georgopoulos, J. Biol. Chem. 266:3654-3660, 1991). These mutant alleles of suhB cause cold-sensitive cell growth, indicating that the suhB gene is essential at low temperatures. Little work has been done, however, to elucidate the role of the product of suhB in a normal cell and the suppression mechanisms of the suhB mutations in the aforementioned mutants. The sequence similarity shared between the suhB gene product and mammalian inositol monophosphatase has prompted us to test the inositol monophosphatase activity of the suhB gene product. We report here that the purified SuhB protein showed inositol monophosphatase activity. The kinetic parameters of SuhB inositol monophosphatase (Km = 0.071 mM; Vmax = 12.3 mumol/min per mg) are similar to those of mammalian inositol monophosphatase. The ssyA3 and suhB2 mutations, which were isolated as extragenic suppressors for secY24 and rpoH15, respectively, had a DNA insertion at the 5' proximal region of the suhB gene, and the amount of SuhB protein within mutant cells decreased. The possible role of suhB in E. coli is discussed.

Base Sequence↗
PubMed1995

Metabolism of Cyanox in the rat. I. Absorption, disposition, excretion and biotransformation.

1. To examine the metabolic fate of Cyanox [O-4-cyanophenyl O, O-dimethyl phosphorothioate, cyanophos, CYAP], rats of both sexes were administered [phenyl-4C]Cyanox as a single oral dose at levels of 0.5 mg/kg (low-dose group) or 25 mg/kg (high-dose group), or as multiple doses at 50 mg/kg/day once daily for 7 days (repeat-dose group). 2. The radiocarbon was almost completely eliminated from rats within 7 days after administration in both low- and high-dose groups. 14C-recoveries (expressed as % relative to the dosed 14C) in faeces and urine were 2-3 and 95-96% respectively for the low-dose and 13-14 and 86% respectively for the high-dose. 3. 14C-tissue residues on the seventh day after a single administration were generally low. Peak 14C-concentrations in blood and kidney occurred at 0.5 h (high-dose) and decreased rapidly thereafter. 4. Sex-related differences in the amounts of metabolites were observed in both groups. With the low-dose, the major metabolite was 4-cyanophenylsulphate in both sexes. However, in the high-dose, the major metabolites were 4-cyanophenyl sulphate and desmethylcyanoxon in males, but 4-cyanophenyl sulphate and desmethylcyanox in females. These findings indicate that the amounts or the types of enzymes responsible for oxidative desulphuration or oxidative dearylation in males are different from those in females. In the male rat given repeat doses significant differences in the amounts of metabolites in excreta were observed between early and final dosing. 5. The greater formation of desmethylcyanoxon in the male rat in the high-dose case is consistent with the higher incidence of toxicity in this sex.

Absorption↗
PubMed1995

[N-acetyl-beta-D-glucosaminidase].

N-acetyl-beta-D-glucosaminidase (NAG), one of the glycolytic enzymes, is distributed in various tissue cells. Among them, the lysosome in the renal proximal tubular cells contains high amount of NAG. NAG is secreted in urine when kidney is damaged. Urinary NAG, therefore, is used as a marker which can detect the extent of the renal damage. Electrophoresis divides urinary NAG into three isozymes, pre A, A, and B forms. In normal males, the percentages of three isozymes are 12.3 +/- 5.56%, 73.15 +/- 4.77%, and 14.81 +/- 2.90%, respectively. In normal females, they are 12.87 +/- 4.70%, 65.47 +/- 4.61%, and 21.70 +/- 5.03%, respectively. The measurement of urinary NAG isozymes is useful to determine the type and severity of renal disease, especially renal tubular disease.

Acetylglucosaminidase↗
PubMed1994

Human glycyl-tRNA synthetase. Wide divergence of primary structure from bacterial counterpart and species-specific aminoacylation.

Several class I and class II human tRNA synthetases are clearly related to their bacterial counterparts. We report here the cloning, cDNA sequence, deduced primary structure, and expression in bacteria of a class II human glycyl-tRNA synthetase. While the human sequence aligns well with a Bombyx mori and a Saccharomyces cerevisiae sequence for glycyl-tRNA synthetase, particularly in the region of the class II-defining sequence motifs, it diverges widely from that of the Escherichia coli enzyme. The divergence is so great that from the sequences alone we cannot conclude that the human and E. coli proteins are descended from homologous genes. Moreover, even though the human and E. coli class II alanyl-tRNA synthetases cross-acylate their respective tRNAs, aminoacylations by the recombinant human and E. coli glycyl-tRNA synthetases are restricted to their homologous tRNAs. The species-specific aminoacylations correlate with a nucleotide sequence difference at a location in the acceptor stem that is known to be critical for aminoacylations by the E. coli enzyme. Thus, glycyl-tRNA synthetase may have followed a path of historical development different in at least some respects from that of several other tRNA synthetases.

Acylation↗
PubMed1994

Transpedicular fixation with Zielke instrumentation in the treatment of thoracolumbar and lumbar injuries.

STUDY DESIGN: Sixty-five patients who underwent transpedicular fixation for thoracolumbar and lumbar injuries were studied for type of injury, the severity of paralysis, the degree of postoperative correction, and instrumentation failures. OBJECTIVES: To evaluate the surgical approaches and the selection of instrumentation to determine indications for using the transpedicular fixation procedure. SUMMARY OF BACKGROUND DATA: Various transpedicular fixation devices have been used for different type of injuries, and satisfactory postoperative results were not obtained in some studies. METHODS: Forty patients had burst fractures, 19 had fracture dislocations, and six had chance-type fractures. An anterior decompression procedure was used for most cases of burst fracture and some cases of fracture dislocation where anterior compression factors were present. The Zielke or modified Zielke system was used as an internal fixator for posterior segmental fixation. RESULTS: No patient had neurologic deterioration after surgery. Twenty of 28 patients with incomplete lesions improved postoperatively according to Frankel grades. The instrumentation failed in only one patient, in whom a nonunion developed. CONCLUSION: With transpedicular fixation, it is possible to provide solid internal fixation that is circumscribed to the injured vertebral segments. The elasticity of the Zielke rod makes it an excellent transpedicular fixation device because it is easily attached and reduction is easily performed. Anterior decompression with fusion needs to be used with transpedicular fixation in the treatment of injuries (especially burst fractures).

Adult↗
PubMed1994

Human cytoplasmic isoleucyl-tRNA synthetase: selective divergence of the anticodon-binding domain and acquisition of a new structural unit.

We show here that the class I human cytoplasmic isoleucyl-tRNA synthetase is an exceptionally large polypeptide (1266 aa) which, unlike its homologues in lower eukaryotes and prokaryotes, has a third domain of two repeats of an approximately 90-aa sequence appended to its C-terminal end. While extracts of Escherichia coli do not aminoacrylate mammalian tRNA with isoleucine, expression of the cloned human gene in E. coli results in charging of the mammalian tRNA substrate. The appended third domain is dispensable for detection of this aminoacylation activity and may be needed for assembly of a multisynthetase complex in mammalian cells. Alignment of the sequences of the remaining two domains shared by isoleucyl-tRNA synthetases from E. coli to human reveals a much greater selective pressure on the domain needed for tRNA acceptor helix interactions and catalysis than on the domain needed for interactions with the anticodon. This result may have implications for the historical development of an operational RNA code for amino acids.

Amino Acid Sequence↗
PubMed1994

In vivo dopamine-D2 and serotonin-5-HT2 receptor binding study of risperidone and haloperidol.

An in vivo receptor binding technique was applied to evaluate the affinities of risperidone and haloperidol for dopamine-D2 receptors (D2) and serotonin-5-HT2 receptors (5-HT2) in rat brain with [3H]YM-09151-2 and [3H]ketanserin as selective ligands. Radioactivities were obtained in the striatum frontal cortex, and cerebellum of the rats treated with the ligands. Time course study of receptor occupancy at 25 to 250 min after single doses of the drugs (1 mg/kg, IP) showed higher 5-HT2 occupancy in the frontal cortex and lower D2 occupancy in the striatum by risperidone than by haloperidol. Dose-response analysis of receptor occupancy revealed risperidone demonstrated higher binding affinity for 5-HT2 than for D2, while the reverse was observed with haloperidol. It appeared that risperidone (1 mg/kg, IP), but not haloperidol (1 mg/kg, IP), demonstrated regional selectivity in D2 occupancy favouring frontal cortex more than the striatum. That risperidone displayed a higher ratio of 5-HT2 to D2 in occupancy than haloperidol is in agreement with the previous findings obtained in vitro.

Animals↗
PubMed1994

Time course of dopamine1,2 and serotonin2 receptor binding of antipsychotics in vivo.

An in vivo receptor binding technique was applied to evaluate the affinities of clozapine (20 mg/kg), RMI-81582 (20 mg/kg), and haloperidol (1 mg/kg) for dopamine D1, D2 and serotonin 5-HT2 receptors in rat brain with [3H]-SCH23390, [3H]-YM-09151-2, and [3H]-ketanserin as selective ligands. The time course study of receptor occupancy at 25 to 250 min after intraperitoneal administration of the drugs showed higher 5-HT2 and lower D2 receptor occupancies of clozapine and RMI-81582 than those of haloperidol both in the striatum and frontal cortex. The 5-HT2/D2 ratios of receptor occupancy for clozapine and RMI-81582 were about 6 to 8 times higher than that for haloperidol. Stable occupancies of D1 receptors were observed only with RMI-81582 and clozapine, the former demonstrating the higher occupancy. These findings are in agreement with the previous findings obtained under in vitro conditions and may account for some part of the properties of atypical antipsychotic drugs.

Animals↗
PubMed1994

A simple staining method for dna and rna blotted on a membrane using a polyethyleneimine-enzyme conjugate.

We describe a new method for the detection of nucleic acids fixed on a membrane involving enzyme-conjugated polyethyleneimine. This method is based on the strong ionic interaction of the cationic polymer, polyethyleneimine (aziridine), with nucleic acids. Sensitivities of 10 pg for DNA and 1 ng for rRNA were achieved in slot-spot blotting experiments. DNA fragments blotted onto a membrane by Southern transfer can be stained after hybridization with a labeled nucleic acid probe. By combining this method with a non-isotopic detection system, the positions of probe hybridized and non-hybridized signals were visualized as distinct colors on the same membrane without superimposing any other image. This technique should have wide application for the detection of nucleic acids fixed on membranes in blot-hybridization experiments.

Alkaline Phosphatase↗
PubMed1994

Studies of diabetic nephropathy. I. Effects of storage time and temperature on microalbuminuria.

The effect of storage time and temperature on the immunological turbidimetric measurement of a low concentration of albumin in urine was investigated. In storage at -20 degrees C, the albumin level decreased, but the rate of this decrease differed considerably among specimens. However, under storage at room temperature for 2 weeks, or at 4 degrees C for 5 weeks albumin levels did not show significant changes. At -40 degrees C and -80 degrees C there were only slight decreases. At -40 degrees C decreases were slightly greater than at -80 degrees C. Therefore, -80 degrees C was found to be the optimal temperature for long-term storage of urinary albumin. Some of the specimens showed a 50% decrease in albumin level after storage for 9 weeks at -20 degrees C, but remained unchanged after storage for the same period at -80 degrees C. A pair of specimens preserved at -20 degrees C and -80 degrees C were isolated by SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). After electrophoresis, urinary proteins were stained by silver staining to observe bands, and albumin content was determined by immunoblotting. A decrease in albumin concentration was also observed by densitometric detection.

Albuminuria↗
PubMed1994

Development of a thermoelectric cooling apparatus for high-voltage isoelectric focusing on a cellulose acetate membrane.

To develop an isoelectric focusing apparatus using a cellulose acetate membrane (Separax EF), we have designed a thermoelectric cooling isoelectric apparatus. This apparatus has two characteristics. Firstly, the cooling system was switched to a thermoelectric cooling system from an ice-cooling system. Secondly, the chamber lid of the electrophoretic apparatus was also devised so that samples could be applied without opening the chamber lid. With this apparatus we could perform the isoelectric focusing without worrying about room temperature and humidity in the laboratory. Applying 2000 V for an extra 5 min with our module cooling system, we achieved a much higher degree of resolution with three sheets of cellulose acetate membrane (Separax EF) overlaid for simultaneous electrophoresis. Thus, three types of information could be obtained from only one electrophoretic procedure.

Biocompatible Materials↗
PubMed1994

Urinary protein fractions in healthy subjects using cellulose acetate membrane electrophoresis followed by staining with acid violet 17.

We fractionated normal urinary proteins obtained from 40 healthy subjects using cellulose acetate membrane electrophoresis and stained them with Acid Violet 17. The electrophoretic patterns were classified into four groups. Each of groups I, II, III, IV had an albumin peak and 1, 2, 3, and 4 additional globulin peaks, respectively. Within-day variation study showed that the pattern was fundamentally specific to the individual, although some intermediate cases were observed. We were unable to determine which type was standard for normal subjects. However, the concentration of Tamm-Horsfall protein was speculated to be an important factor in determining the patterns. Group III showed significantly higher values than group I in urine albumin, total protein, and beta-N-acetyl-D-glucosaminidase and this group was believed to include subjects in the subclinical stage of a glomerular disease. All specimens belonging to group IV showed an obvious fraction of alpha 1 globulin which is often found in urine specimens of patients with renal diseases of tubular origin or other pathological conditions.

Acetylglucosaminidase↗
PubMed1994

Metabolism of tetramethrin isomers in rat: II. Identification and quantitation of metabolites.

1. To examine the metabolic fate of (1RS, trans)- or (1RS, cis)-tetramethrin [3, 4, 5, 6-tetrahydrophthalimidomethyl (1RS, trans)- or (1RS, cis)-chrysanthemate], rat was administered a single oral dose of trans- or cis-[alcohol-14C]tetramethrin at dose levels of 2 or 250 mg/kg. 2. The radiocarbon was almost completely eliminated from rat within 7 days after administration in all groups. 14C-recoveries (expressed as percentages relative to the dosed 14C) in faeces and urine were 38-58 and 42-58% respectively in rat administrated trans-[alcohol-14C]tetramethrin, and in faeces and urine were 66-91 and 9-31% respectively in rat administered cis-[alcohol-14C]tetramethrin. 3. Fourteen metabolites found in excreta were purified by using several chromatographic techniques and identified by spectroanalyses (nmr and MS). Five sulphonate derivatives and three dicarboxylic acid derivatives were found. 4. The main metabolites were sulphonate derivatives in the faeces, and in the urine, alcohols, dicarboxylic acid and reduced metabolites derived from the 3,4,5,6-tetrahydrophthalimide moiety.

Animals↗
PubMed1994

Metabolism of tetramethrin isomers in rat. I. Identification of a sulphonic acid type of conjugate and reduced metabolites.

1. Urinary and faecal metabolites in rat treated with 14C-labelled (1RS, trans)-tetramethrin [3,4,5,6-tetrahydrophthalimidomethyl (1RS, trans)-chrysanthemate] were identified using chromatographic techniques and spectroanalyses (nmr and ms). 2. 3-Hydroxy-cyclohexane-1,2-dicarboximide was found to be a major and unique urinary metabolite, reduced at the 1,2-double bond of the 3,4,5,6-tetrahydrophthalimide moiety. 3. The major faecal metabolites were sulphonic acid conjugates, having a sulphonic acid group incorporated into the double bond of the 3,4,5,6-tetrahydrophthalimide moiety. 4. On the basis of the metabolites identified here, the major biotransformation reactions of trans-tetramethrin in rats are: (1) cleavage of the ester linkage; (2) cleavage of the imide linkage; (3) hydroxylation of the cyclohexene or cyclohexane ring of the 3,4,5,6-tetrahydrophthalimide moiety; (4) oxidation at the methyl group of the isobutenyl moiety; (5) reduction at the 1,2-double bond of the 3,4,5,6-tetrahydrophthalimide moiety; and (6) incorporation of a sulphonic acid group into the 1,2-double bond of the 3,4,5,6-tetrahydrophthalimide moiety.

Animals↗