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Biomedical subjects

S Ueno

Publications and source records attributed to S Ueno.

At least 217 records · Page 12Linked to original sources
PubMed1995

Photolysis of a newly synthesized caged glycine activates the glycine receptor of rat CNS neurons.

The functions of 12 different newly synthesized caged glycines were examined on strychnine-sensitive glycine receptors on rat hypothalamic neurons using photochemical and physiological methods. Quantitative analysis of Cl- current induced by photolyzed glycines revealed N-[1-(2-nitrophenyl)ethylcarbonoxyl] glycine (N4-caged glycine) to be the most effectively photolyzed. The current amplitude induced by photolyzed N4-caged glycine was almost the same as that induced by normal glycine. We propose N-[1-(2-nitrophenyl)ethylcarbonoxyl] to be a useful photolabile moiety for new caged neurotransmitters.

Animals↗
PubMed1995

Effect of dimethylthiourea on chromium (VI)-induced DNA single-strand breaks in Chinese hamster V-79 cells.

The effect of 1,3-dimethyl-2-thiourea (DMTU), a specific hydroxyl radical scavenger on chromate-induced DNA breaks, was studied using Chinese hamster V-79 cells. Incubation of cells with Na2CrO4 plus DMTU resulted in a small but significant decrease in cellular levels of the metal-caused DNA single-strand breaks. Electron spin resonance studies showed that DMTU did not affect the formation of chromium (V) complexes either in cells or in the reaction of Na2CrO4 with reduced glutathione in vitro, however, DMTU suppressed the generation of hydroxyl radicals in the reaction of hydrogen peroxide and chromium (V) in vitro. Thus, Na2CrO4-induced DNA breaks were inhibited by DMTU, possibly due to its ability to scavenge hydroxyl radicals. These and other previous studies indicated that the formation of hydroxyl radicals contribute to the induction of DNA breaks by Na2CrO4 in intact cells, but presumably is not the only mechanism involved.

Animals↗
PubMed1995

The simian virus 40 large T antigen does not inhibit translation of the 14-kDa myelin basic protein mRNA in reticulocyte lysates or in transfected cells.

Viral T antigens are transcription factors that have been suspected of inhibiting expression of the myelin basic protein (MBP) mRNA at the translational level in vitro and in vivo. The effect of simian virus 40 (SV40) large T antigen (T-ag) was examined on the translation of the 14-kDa MBP mRNA in reticulocyte lysates and on MBP expression after transfection into cells that express SV40 T-ag. SV40 T-ag did not inhibit translation of 14-kDa MBP cRNAs in cell-free translations even at 30 microM (approximately 600 micrograms/ml) T-ag. Permanent transfection of COS-1 cells (which endogenously express SV40 T-ag) with the 14-kDa MBP cDNA resulted in the expression of the 14-kDa MBP as determined by western blot analysis. Permanent transfection of N20.1 cells, an oligodendrocyte line immortalized with a temperature-sensitive SV40 T-ag, with the 14-kDa MBP cDNA construct also resulted in the expression of the 14-kDa MBP under conditions in which the cells expressed functional SV40 T-ag. These results indicate that SV40 T-ag does not prevent expression of the MBP gene at the translational level and that in those immortalized oligodendrocyte lines that express MBP mRNA, but not MBP protein, some factor other than the SV40 large T-ag is responsible for the posttranscriptional regulation.

Animals↗
PubMed1995

Somatic mosaicism of CAG repeat in dentatorubral-pallidoluysian atrophy (DRPLA).

An unstable expansion of CAG repeat in the coding region of the DRPLA gene on chromosome 12p is the mutation specific for hereditary dentatorubral-pallidoluysian atrophy (DRPLA). We studied the CAG expansion in brain and other tissues from six unrelated DRPLA patients. The CAG repeat lengths showed distinct differences between tissues. The sizes of the CAG expansion in various regions of the brain except the cerebellum were generally larger by several repeats than in other peripheral tissues. Brain samples showed greater variation of the expansion compared with other tissues, but neither the size of the CAG expansion nor the degree of CAG repeat variation parallels the detailed findings of neuropathological involvement. We conclude that somatic instabilities of the CAG repeat cause tissue variability of the CAG repeat size in DRPLA but other region or cell type-specific factors would be involved to explain the selectivity of cell damage in DRPLA.

Adult↗
PubMed1995

Functional consequences of substitution of the disulfide-bonded segment, Cys127-Cys150, located in the extracellular domain of the Na,K-ATPase beta subunit: Arg148 is essential for the functional expression of Na,K-ATPase.

The Cys127-Cys150 disulfide-bonded loop (L1) of the Torpedo californica Na,K-ATPase beta 1 subunit was substituted with the corresponding loop of the rat beta 1, mouse beta 2, or pig H,K-ATPase beta subunit. All the substituted mutant beta subunits assembled with the Na,K-ATPase alpha subunit in a trypsin-resistant manner. The mutants with L1 from the Na,K-ATPase beta subunit isoforms (rat beta 1 and mouse beta 2) each formed a functional complex with the Na,K-ATPase alpha subunit. On the other hand, the complex of the alpha subunit with the mutant beta subunit that was substituted with the pig H,K-ATPase beta subunit L1 was inactive as to ATP hydrolysis. Ser131 and Phe148 located within L1 of the pig H,K-ATPase beta subunit-substituted mutant were back-mutated to Pro131 and Arg148, respectively. The Phe148 to Arg mutation restored the ability of the mutant beta subunit substituted with the H,K-ATPase beta subunit L1 to form a functional complex with the alpha subunit. These results suggested that the Cys127-Cys150 loop of the Na,K-ATPase beta 1 subunit, especially Arg148, plays a critical role in the functional expression of Na,K-ATPase.

Amino Acid Sequence↗
PubMed1995

Differential changes in alpha- and beta-adrenoceptors in the cerebral cortex and hippocampus of the Mongolian gerbil after unilateral brain ischemia.

BACKGROUND AND PURPOSE: Changes in adrenoceptors in the cerebral cortex and hippocampus of Mongolian gerbils after brain ischemia were investigated. METHODS: Twenty-four hours after unilateral occlusion of the common carotid artery, alpha 1-, alpha 2-, and beta-receptors of the membrane fraction of the cerebral cortex or the hippocampus were analyzed by binding assay with the use of [3H]prazosin, [3H]p-aminoclonidine, and [125I]cyanopindolol as radioligands, respectively. RESULTS: In the cerebral cortex, the number of binding sites (Bmax) and the dissociation constant (Kd) of [3H]prazosin were not altered, whereas the Bmax value of [3H]p-aminoclonidine binding was decreased by 30% and that of [125I]cyanopindolol binding by 16% without a change in Kd values for the ligands. In the hippocampus, the Bmax values of [3H]prazosin, [3H]p-aminoclonidine, and [125I]cyanopindolol bindings were decreased by 21%, 53%, and 19%, respectively, but there was no change in the Kd values for the ligands. The bindings of [3H]prazosin and [3H]p-aminoclonidine of the contralateral side of the cerebral cortex and the hippocampus were not altered by ischemia, but that of [125I]cyanopindolol was decreased when compared with normal tissues. CONCLUSIONS: These results show that ischemia results in a decrease in brain alpha 1-, alpha 2-, and beta-adrenoceptors to various degrees, depending on the brain area and the types of receptors, and suggest that vulnerability of the brain to ischemia is different depending on brain areas and that the regulatory mechanisms of alpha 1-, alpha 2-, and beta-receptors are different.

Animals↗
PubMed1995

DNA analysis in hereditary dentatorubral-pallidoluysian atrophy: correlation between CAG repeat length and phenotypic variation and the molecular basis of anticipation.

Hereditary dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disease with variable clinical phenotypes. Progressive ataxia, choreoathetosis, and dementia are the main clinical features of adult-onset cases, whereas the main feature in juvenile-onset DRPLA is progressive myoclonus epilepsy. Earlier onset is apparent in successive generations (anticipation). The molecular abnormality underlying DRPLA is an expanded, unstable CAG trinucleotide repeat on chromosome 12p. We analyzed 71 DNA samples obtained from 12 Japanese DRPLA pedigrees that included 38 affected individuals. Normal alleles had 7 to 23 repeats, DRPLA alleles 53 to 88 repeats. DRPLA alleles also were detected in five asymptomatic family members. Patients with juvenile onset had significantly larger repeats than did those with adult onset, and there was a significant negative correlation between CAG repeat length and age at onset. In 80% of the paternal transmissions, there was an increase of more than five repeats, whereas all the maternal transmissions showed either a decrease or an increase of fewer than five repeats. There was a significant correlation between father-child differences in repeat length and differences in age at onset. The analysis of CAG repeat length is a reliable diagnostic test for DRPLA and is of value for the presymptomatic detection of individuals at risk. The expansion of CAG repeats is important in phenotypic variation and anticipation. In addition, the sex of the transmitting parent has a significant effect on the molecular mechanism of anticipation.

Adolescent↗
PubMed1995

[Identification of motor area by transcranial magnetic stimulation using an "eight-figure" coil in patients with motor paralysis].

In patients with motor paralysis, we tried to identify the functional motor area by transcranial magnetic stimulation using an "eight-figure" coil designed by Ueno. Motor evoked potentials (MEPs) were recorded in 7 patients from 50 to 64 years old, and in 5 normal volunteers 26 to 45 years old. They were stimulated at 49 points over an unilateral hand motor area, and at 21 points over a foot motor area, and surface MEPs were recorded on their contralateral thenar muscle and abductor hallucis brevis muscle. In normal volunteers, the optimal eddy current for stimulating the hand motor area was directed anteriorly parallel to the midline, and for stimulating the foot motor area, it was postero-laterally directed with an angle of 45 degrees towards the midline. MEPs could be induced at their muscle contractions during which their thumbs and middle fingers softly touched each other, and their halluxes slightly flexed. In five patients two kinds of amplitude mappings reconstructed from MEPs were obtained at rest or at muscle contraction. A line connecting these two peaks on an amplitude mapping was regarded as an "MEP-motor area". A geographical difference between the MEP-motor area and MRI-motor area (identified by an MRI surface image) was studied at muscle contraction and at rest. In normal subjects the sites of the MEP-motor area and of the MRI-motor area coincided, whereas, in patients with space-occupying lesions near the central sulcus, the MEP-motor areas were located 1 to 2cm posterior to MRI-motor areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

An application of powder metallurgy to dentistry.

Generally, the dental casting method is used to fabricate dental prostheses made with metal. The method of fabricating dental prostheses from sintered titanium alloy has certain advantages: the elimination of casting defects, a sintering temperature that is lower than the melting point, and a shorter processing time. By examining (1) the properties of green, sintered compacts of titanium powder, (2) the effects of adding aluminum powder on the properties of green, sintered compacts of Ti-Al compound, and (3) the effects of adding copper powder on the properties of green, sintered compacts of Ti-Al-Cu compound, the authors developed a sintered titanium alloy on a trial basis. Because the properties satisfied the requirements of dental restorations, a powder metallurgical method of making dental restorations from this sintered titanium alloy was devised. Applications of such sintered titanium alloys for the metal coping of metal-ceramic crowns and denture base plates were discussed.

Aluminum↗
PubMed1994

Expression of (Na, K) ATPase/Ca-ATPase chimeric proteins in Xenopus oocytes revealed that the COOH-terminal one-third of the (Na, K) ATPase alpha-subunit is involved in assembly with the beta-subunit.

Chimeric proteins consisting of parts from the alpha-subunit of Torpedo californica (Na, K) ATPase (N) and the rabbit sarcoplasmic reticulum Ca-ATPase (C) were expressed in Xenopus oocytes by injecting the respective chimeric cRNA in combination with cRNA for the beta-subunit of Torpedo (Na, K) ATPase. The chimeric protein (NCN) that consisted of the NH2-terminal and COOH-terminal one-thirds of the alpha-subunit of the (Na, K) ATPase and the central one-third of the Ca-ATPase was able to assemble with the beta-subunit in the same fashion as the wild-type alpha-subunit of the (Na, K) ATPase (NNN). On the other hand, chimeric proteins in which the COOH-terminal one-third was derived from the Ca-ATPase (NNC and NCC) were unable to form stable complexes with the beta-subunit. These results suggest that the COOH-terminal one-third of the (Na, K) ATPase alpha-subunit is required for the assembly with the beta-subunit.

Animals↗
PubMed1994

The 3'-untranslated region of mouse myelin basic protein gene increases the amount of mRNA in immortalized mouse oligodendrocytes.

The 3'-untranslated region (UTR) of the myelin basic protein (MBP) mRNA has been found previously to enhance the translational efficiency of the coding region by two-fold in cell-free translational systems. In this study, we transfected eukaryotic expression vectors containing the reporter cDNA for chloramphenicol acetyltransferase (CAT) with or without the mouse MBP cDNA 3'-UTR into cultured cells. CAT activity in the mouse oligodendrocyte cell line, N20.1, transfected with a CAT cDNA containing the MBP 3'-UTR [CAT-MBP 3'-UTR], was twice as high as that of the CAT cDNA without the 3'-UTR; CAT activities for the two constructs were the same in the mouse fibroblast cell line, NIH 3T3. Using reverse transcriptase PCR quantitative analysis, the expression of mRNA was determined. The level of the [CAT-MBP 3'-UTR] mRNA was about ten times higher than CAT mRNA in N20.1 cells but they were the same in NIH 3T3 cells. We conclude that the 3'-UTR of MBP gene increases gene expression at both the mRNA and protein levels in oligodrocyte cell lines, probably through a post-transcriptional mechanism such a message stabilization.

3T3 Cells↗
PubMed1994

A new variant Cu/Zn superoxide dismutase (Val7-->Glu) deduced from lymphocyte mRNA sequences from Japanese patients with familial amyotrophic lateral sclerosis.

We have identified a new mutant Cu/Zn superoxide dismutase (SOD1) deduced from the nucleotide sequences of peripheral blood lymphocyte mRNA from Japanese patients with familial amyotrophic lateral sclerosis (FALS). Sequence analysis of reverse transcriptase-initiated PCR amplified mRNA revealed a heterozygosity indicative of one normal allele and one variant allele with a T-->A transversion. This base change led to replacement of valine by glutamic acid at position 7 of 153-residue SOD1 molecule, and produced a new restriction site for Alu I in the exon 1. Restriction fragment length polymorphism analysis confirmed the linkage of this mutation with this type of FALS. Both enzymatic activity and protein of the SOD1 were reduced in red blood cells from the patient.

Adult↗
PubMed1994

Protection by prosaposin against ischemia-induced learning disability and neuronal loss.

Prosaposin, the protein precursor of saposins A, B, C, and D which activate sphingolipid hydrolases, is abundant in several brain regions including the hippocampus. We infused prosaposin continuously for 7 days into the lateral ventricle of gerbils starting 3 hours before 3-min of forebrain ischemia. Using the step-down passive avoidance task, we demonstrated that ischemia-induced learning disability is prevented almost completely by prosaposin infusion. Subsequent light and electron microscopic examinations showed that pyramidal neurons in the CA1 field of the hippocampus as well as synapses within the strata moleculare, lacunosum/radiatum and oriens of the field were significantly more numerous in gerbils infused with prosaposin infusion than in those receiving saline infusion. These findings suggest that prosaposin possesses neurotrotrophic activity to protect hippocampal CA1 neurons from lethal ischemic damage.

Animals↗
PubMed1994

Methylmercury-induced augmentation of oxidative metabolism in cerebellar neurons dissociated from the rats: its dependence on intracellular Ca2+.

Effect of methylmercury chloride on oxidative metabolism of cerebellar neurons dissociated from the rats was examined using 2',7'-dichlorofluorescin (DCFH) which is oxidized by cellular hydrogen peroxide to be a fluorescent compound (DCF) and fluo-3, an indicator for intracellular Ca2+ concentration ([Ca2+]i). Methylmercury at 1 microM or less did not affect DCF fluorescence of cerebellar neurons. Further increase in concentration of methylmercury (up to 30 microM) induced changes in DCF fluorescence. Thus, DCF fluorescence was slightly attenuated during 5 min after applying methylmercury to the neurons, indicating a decrease in oxidation of DCFH. Thereafter, DCF fluorescence was time-dependently augmented in continued presence of methylmercury, indicating an increase in DCFH oxidation. Although methylmercury-induced augmentation of DCF fluorescence was greatly suppressed under external Ca(2+)-free condition, it was not the case for methylmercury-induced attenuation of DCF fluorescence. Methylmercury at 3 microM or more dose-dependently increased the [Ca2+]i. Results suggest that methylmercury increases intracellular Ca2+ in cerebellar neurons, resulting in an increase in formation of reactive oxygen species that may contribute to cell injury.

Aniline Compounds↗
PubMed1994

Pituitary adenylate cyclase-activating polypeptides (PACAPs) increase cAMP in rat cerebral microvessels.

Effect of PACAP on cAMP level in the rat cerebral microvessels was investigated. The cerebral microvessels were prepared from rat cerebral cortex by albumin flotation and glass beads filtration technique. When the microvessels were incubated with PACAP 27, PACAP 38 and VIP, cAMP in the microvessels was increased rapidly reaching a plateau value within 60 s. PACAP 27, PACAP 38 and VIP increased cAMP level in a dose-dependent manner with EC50 values of 4.7, 7.0 and 34 nM, respectively. These results suggest that PACAPs play a role in the regulation of the cerebral microvessel function.

Animals↗
PubMed1994

Effects of stimulation side on human middle latency auditory evoked magnetic fields.

We investigated the effects of the stimulation side on middle latency auditory evoked responses (MLR) with neuromagnetic methods. Middle latency auditory evoked magnetic fields elicited by 1.0 ms clicks presented at ipsilateral and contralateral ear were recorded with a 7-channel DC SQUID. The amplitudes and latencies of the magnetic equivalents of Pa and Pb responses, which are the two main peaks of MLR, were measured. The amplitude of the contralateral Pa response was found to be significantly larger than the ipsilateral Pa response. On the other hand, no significant difference was observed in the latencies of Pa and Pb between the ipsi- and contralateral responses.

Acoustic Stimulation↗