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Biomedical subjects

T Nishimoto

Publications and source records attributed to T Nishimoto.

At least 163 records · Page 9Linked to original sources
PubMed1988

Molecular cloning of the cDNA of human X chromosomal gene (CCG1) which complements the temperature-sensitive G1 mutants, tsBN462 and ts13, of the BHK cell line.

The tsBN462 cell line, a temperature-sensitive (ts) mutant isolated from the hamster cell line, BHK21/13 has a ts defect in G1 progression and belongs to the same complementation group as the ts13 cell line. We cloned human cDNA which can complement both tsBN462 and ts13 mutations, from the cDNA library of the secondary ts+ transformant (K-1-1) of tsBN462 cells using, as a probe, the isolated human X chromosomal genomic DNA. The cloned DNA is 5.3 kb long and has an open reading frame of 4662 bp, encoding a protein of 178,768 daltons. The putative protein is hydrophilic with a tandem repeat of 120 amino acids in the C-terminal region. An amino acid sequence (PPKKKRRV), similar to the consensus sequence for the nuclear translocation signal, is located immediately before the tandem repeat of amino acids.

Amino Acid Sequence↗
PubMed1988

Cross-resistance of novobiocin-resistant BHK cell line to topoisomerase II inhibitors.

A novobiocin-resistant BHK cell line, designated as NovrA2, was found to exhibit cross-resistance to other topoisomerase II inhibitors such as 4'-dimethylepipodophyllotoxin-4-(4,6-O-ethylidine-beta-D-glu copyranoside) (VP-16), adriamycin, and 4'-(9-acridinyl-amino)methanesulfon-m-anisidide (m-AMSA), and also to different types of drugs such as vinblastine and arabinocytidine. Nalidixic acid-resistant cells (A2Nalr) of the NovrA2 cell line were phenotypically reverted to novobiocin sensitivity like wild-type cells and were also partially reverted to sensitivity to VP-16 and adriamycin, but not to vinblastine and arabinocytidine. When VP-16 was added to cell culture, the drug-induced DNA strand breaks were much fewer in NovrA2 cells than in BHK cells. This reduced level of strand breaks in NovrA2 cells was not due to reduced drug uptake, because the two cell lines accumulated similar levels of radiolabeled VP-16. VP-16 also induced fewer DNA breaks in isolated nuclei of NovrA2 cells than in those of BHK cells. There was no significant difference in the VP-16-induced DNA cleavage activities of partially purified topoisomerase II from BHK and Novr cells. These results show that the resistance of NovrA2 cells to various drugs is not acquired by a defense mechanism related to membrane permeability and suggest that the resistance of the NovrA2 cells to topoisomerase II inhibitors might be due in part to alteration in a topoisomerase II associated factor(s).

Amsacrine↗
PubMed1988

Identification and characteristics of actinomycetes useful for semicontinuous treatment of domestic animal feces.

Selected strains of actinomycetes useful for practicing semicontinuous treatment of swine and poultry feces were identified as Streptomyces antibioticus S-4, S. puniceus N-50-2, S. nigrifaciens N-9-3, Thermoactinomyces vulgaris HIR-60, and Thermomonospora viridis HIR-50. These five obligately aerobic strains grew preferably on nonsterilized fresh swine feces in 24 h without any additives. They assimilated offensive volatile fatty acids in the swine and poultry feces. Cultures of these five strains were mixed and used as seed for the practical treatments of 1 ton of swine feces over the wide temperature range of 15 to 60 degrees C. Strain HIR-50 grew most predominantly on both fresh swine and poultry feces at 50 to 55 degrees C and decomposed uric acid. For the efficient penetration of mycelia into the feces, manures were mixed once a day so as not to break the solid mass, and the dehydration rate of feces had to be controlled in proportion to the mycelial growth rate. The actinomycete biofertilizer thus manufactured in 10 days was odorless and promotive of plant growth.

Journal Article↗
PubMed1988

Simple and effective method of electroporation for introduction of plasmid and cosmid DNAs to mammalian cells.

We have established a simple and efficient method of electroporation applicable to gene transfer in mammalian cells. It uses a single decaying pulse of around 1 ms at room temperature in the medium such as Saline G appropriate for repair of pulse-induced pores in the plasma membrane. Many types of cells (both floating and adherent) could be transformed efficiently by the electric field strengths between 1-2 kV/cm. For instance P3U1, mouse myeloma cell, could be transformed by a pulse at 1.2 kV/cm with the frequency of 10(-2) per viable cells and with survivals of 90%. We have applied these conditions to transform tsBN2 cell line of BHK21/13 by a cosmid clone (approximately 45 kb) carrying the human gene complementing to tsBN2 mutation. Significant levels of transformation were observed for this gene. Since this gene can only work as a whole size (approximately 30 kb), the results show that electroporation is useful to introduce cosmid or possibly genomic DNA to mammalian cells.

Animals↗
PubMed1987

Isolation and characterization of novobiocin-resistant BHK cells.

We isolated two novobiocin-resistant mutants which were stable and approximately three and four times more resistant than the parent cells to novobiocin. Both mutants (Novr A2, Novr A41) were more sensitive than the wild-type cells to nalidixic acid, and cold sensitive for cell growth. When we isolated derivatives of Novr A2 and Novr A41 cells which are resistant to nalidixic acid, those are found to be phenotypically reverted to novobiocin sensitivity like wild-type cells, thereby suggesting the relationship between the targets for novobiocin and for nalidixic acid. But the cold sensitivity did not always revert to wild type, with accompanying resistance to nalidixic acid. The DNA and RNA syntheses of Novr mutants were more resistant to novobiocin but more sensitive to nalidixic acid, than those of wild-type cells. However, in vitro assays of wild-type and Novr cell extracts were unable to demonstrate any differences in the sensitivity of topoisomerase II activity to inhibition by novobiocin. While the targets of novobiocin and nalidixic acid show a mutual interaction in vivo and play a role in DNA replication and transcription, our results suggest that these targets are probably not topoisomerase II.

Animals↗
PubMed1987

Isolation of a human X chromosome-linked gene essential for progression from G1 to S phase of the cell cycle.

The tsBN462 cell line, a temperature-sensitive (ts) mutant isolated from the hamster cell line, BHK21/13, cannot progress into S phase at 39.5 degrees C, following the release from isoleucine deprivation. The mutant cells were transfected with high molecular weight (HMW) DNA from human KB cells, and several human DNA bands were found to be conserved through three cycles of ts+ transformation. Conserved human DNA was isolated from the cosmid library of the secondary ts+ transformant (K-1-1), using 32P-labelled total human DNA as a probe. The isolated human DNA covers about 70 kb of human DNA flanked with hamster DNA, and originates from the human X chromosome. The middle part (56 kb) of the isolated human DNA was conserved through the primary, secondary and tertiary ts+ transformation, without gross rearrangement.

Animals↗
PubMed1987

Efficacy of acupuncture treatment in autonomic ataxia.

Recently Coefficient Variation of R-R interval derived from patient's ECG is advocated to be an objective and quantitative method of analyzing autonomic nerve function. In the present study, we used this method to make an evaluation of the acupuncture treatment on the patients suffering from autonomic ataxia. Twenty-one patients were admitted to this therapy according to the results of CMI (Cornell Medical Index) test. (4 males, 17 females, mean age was 49.9 y.o.) ECG machine was used to measure the R-R interval every 100 heart beats before and after the treatment, and through this survey, the mean R-R interval (mR-R) and Coefficient Variation (C.V. SD/mR-R x 100%) were obtained. Subjective complaints were obtained at the same time, too. The mR-R became extended in 14 out of 21 patients after treatment and mean value of mR-Rs after treatment was significantly increased than prior to treatment. (871.6 msec-before 918.3 msec-after p less than 0.05) As for C.V. the mean value was not markedly changed but the variance was decreased significantly (1.67-before 0.47-after p less than 0.025), and 60% of subjective complaints were improved after treatment. These results suggest that acupuncture therapy is effective on the patients who have been diagnosed as having autonomic ataxia by regulating autonomic nerve function.

Acupuncture Therapy↗
PubMed1987

Down-regulation of central serotonin S2 receptors after repeated treatment with quinupramine in rats.

The present studies were undertaken to determine whether the repeated administration of quinupramine caused down- or up-regulation of beta-, alpha 2-adrenergic, serotonin S2, imipramine and muscarinic cholinergic receptors, as had been demonstrated for tricyclic and atypical antidepressant drugs. Quinupramine administered at 10 mg/kg (p.o.) twice daily for 10 days caused a down-regulation of serotonin S2 receptors in the frontal cortex of the rat as determined by [3H]ketanserin binding. However, quinupramine did not alter the binding populations of beta-adrenergic, muscarinic cholinergic and alpha 2-adrenergic receptors in the rat brain as determined by the Scatchard analysis of the [3H]ligand binding data. Differing from quinupramine, imipramine caused down-regulation of beta-adrenergic and serotonin S2 receptor bindings, and it caused slight but significant up-regulation of muscarinic cholinergic receptor bindings. These results show that the antidepressant activity of quinupramine is associated with the central serotonin system, but not with the beta-adrenergic system. Accordingly, quinupramine, chemically one of the typical tricyclic antidepressant drugs, seems to be pharmacologically one of the atypical antidepressant drugs, and it was suggested that the central serotonin system plays an important role in the antidepressant activity of quinupramine.

Animals↗
PubMed1987

Effects of quinupramine on the central monoamine uptake systems and involvement of pharmacokinetics in its pharmacological activities.

The effects of a new tricyclic antidepressant drug, quinupramine, on the monoamine uptake of rat brain homogenate preparations were studied in comparison with imipramine. Pharmacokinetic studies on quinupramine and imipramine in plasma and brain were also performed in rats after a single oral administration. Quinupramine had few effects on the noradrenaline and serotonin uptake both in in vitro and ex vivo models. After the administration of [3H]quinupramine, the unchanged drug was estimated as 60-75% of the total radioactivity in the cerebral cortex. Imipramine and desipramine preferentially inhibited the uptake of serotonin and noradrenaline, respectively, in vitro. After the administration, imipramine showed a marked inhibitory effect on noradrenaline uptake. A considerable amount of desipramine but not imipramine could be detected in the brain and plasma after the administration of [3H]imipramine. These results demonstrate that 1) the antidepressant activity of quinupramine cannot be attributed to inhibition of monoamine uptake, 2) unchanged quinupramine penetrates into the CNS and affects some of the processes of neurotransmission and 3) the pharmacological activities of imipramine, when administered orally, may be attributed to desipramine, the metabolite formed.

Animals↗
PubMed1987

Binding characteristics of [3H]quinupramine to rat brain membrane fractions.

The binding characteristics of [3H]quinupramine to rat brain membrane fractions were studied. The specific binding of [3H]quinupramine to rat brain membrane fractions was stable, reversible and saturable. Scatchard analysis of the data from saturation experiments indicated that the specific binding was a single population with an affinity (KD) of 3.04 nM, a maximal binding site number (Bmax) of 714 fmol/mg protein, and a Hill coefficient (nH) of 1.08. Compounds known to inhibit muscarinic cholinergic receptors such as atropine and quinuclidinyl benzilate were the most potent competitors of [3H]quinupramine binding. When the drug potencies in inhibiting [3H]quinupramine binding were tested in the presence of 10 nM atropine, mianserin was the most potent competitor. Studies of the subcellular fractions showed that there was an enrichment of [3H]quinupramine binding sites in the synaptosome fraction. The regional distribution study revealed the highest densities of binding sites in the cerebral cortex and the lowest in the cerebellum. Thus, the specific binding of [3H]quinupramine observed here can be accounted for by both muscarinic cholinergic and serotonin S2 receptors.

Animals↗
PubMed1987

Noradrenaline content in canine lower urinary tract tissue.

To examine the distribution of sympathetic nerve fibers in the lower urinary tract, the noradrenaline content was measured in the urinary bladder dome and base, and proximal and distal urethra of the male and female dogs, using high pressure liquid chromatography-electrochemical detection (HPLC-ED). The noradrenaline content was the highest in the proximal urethra and the lowest in the urinary bladder dome in both sexes. The noradrenaline content of the proximal urethra was significantly higher in the male than in the female, whereas the content of the urinary bladder base and the distal urethra was lower in the male than in the female. These data suggest that sympathetic innervation is the richest in the proximal urethra in the lower urinary tract and that there is a sex difference in the sympathetic innervation in the lower urinary tract.

Animals↗
PubMed1987

Chromosome condensation may enhance X-ray-related cell lethality in a temperature-sensitive mutant (tsBN2) of baby hamster kidney cells (BHK21).

In the tsBN2 cell line, which has a temperature-sensitive defect in the regulatory mechanism for chromosome condensation, the lethal effect of X rays was enhanced by incubating the cells at a nonpermissive temperature (40 degrees C) following X irradiation. This enhancement was suppressed in the presence of cycloheximide, which inhibits induction of premature chromosome condensation. The findings obtained in the case of delayed incubation at 40 degrees C and in synchronized cells indicate that X-ray-related potentially lethal damage, which can be expressed by chromosome condensation, is produced in the cells at any stage of the cell cycle, but it is repairable for all cells except those at around the late G2-M phase, where chromosome condensation occurs at a permissive temperature (33.5 degrees C). These observations suggest that the high sensitivity of late G2-M cells to X rays is caused by the events associated with chromosome condensation.

Animals↗