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Y Sakai

Publications and source records attributed to Y Sakai.

At least 793 records · Page 44Linked to original sources
PubMed1987

Excitatory action of N-acetylaspartylglutamate on Purkinje cells in guinea pig cerebellar slices: an intrasomatic study.

The action of N-acetylaspartylglutamate (NAAG) on Purkinje cell somata in guinea pig cerebellar slices was intracellularly investigated in comparison with L-aspartate (Asp) and L-glutamate (Glu). A synthetic NAAG sample used was confirmed not to be contaminated with free Glu and Asp. NAAG, applied by either iontophoresis or superfusion, dose-dependently depolarized Purkinje cell somata, and iontophoretically applied NAAG decreased the membrane resistance in voltage- and Mg2+-dependent manners, like Asp or Glu. Relative depolarizing potencies seemed to be Glu greater than NAAG not equal to Asp in the presence of external Mg2+ and Asp greater than NAAG greater than or equal to Glu in the absence of Mg2+. In addition to this selective blocking effect of Mg2+, 2-amino-5-phosphonovalerate (APV) antagonized the actions of NAAG and Asp more strongly than that of Glu, while 2-amino-4-phosphonobutyrate showed rather non-selective antagonisms. The reversal potential of the NAAG action was at about 10 mV and similar to that of the action of Asp or Glu. These results suggest that NAAG itself is excitatory to guinea pig cerebellar Purkinje cells and is likely to be acting on Asp- and APV-sensitive, Mg2+-dependent receptors on cerebellar Purkinje cells.

Animals↗
PubMed1987

Na+/adenosine co-transport in Vibrio parahaemolyticus.

Adenosine transport in Vibrio parahaemolyticus was studied. Na+ greatly stimulated adenosine uptake. Addition of adenosine to a cell suspension under anaerobic conditions elicited Na+ uptake, and the Na+ uptake was inhibited by monensin, an Na+ ionophore. Imposition of an electrochemical potential of Na+ or a membrane potential in energy-depleted cells elicited adenosine uptake. Therefore, adenosine transport in this organism was concluded to proceed by an Na+/adenosine co-transport mechanism. The Na+/adenosine co-transport system was induced when cells were grown in the presence of adenosine, and repressed by glucose. Although Na+ uptake elicited by adenosine was reduced by glucose, it was enhanced by methyl alpha-glucoside, which reduced the intracellular ATP level. Thus, the effects of glucose and the glucoside on the Na+/adenosine co-transport system did not seem to be due to inducer exclusion, but to be related to the intracellular ATP level.

Adenosine↗
PubMed1987

A novel mechanism for utilization of extracellular AMP in Vibrio parahaemolyticus.

Vibrio parahaemolyticus could grow with AMP, ADP or ATP as the sole source of carbon. In the presence of Cl-, a membrane-bound Cl(-)-dependent 5'-nucleotidase seemed to hydrolyze the nucleotides extracellularly, and then the cells took up the resulting adenosine. In the absence of Cl-, although no significant dephosphorylation of the nucleotides occurred, the cells could still grow with AMP, but not with ADP or ATP. Moreover, in the presence of Cl-, Zn2+ inhibited the 5'-nucleotidase, and inhibited growth of the cells with ADP or ATP, but not with AMP, as the carbon source. V. parahaemolyticus was unable to grow with adenine or ribose 5-phosphate. These results suggested that the cells might have an AMP transport system. In fact, Na+ uptake was observed on addition of AMP to a cell suspension in the absence of Cl-, indicating Na+-AMP cotransport.

5'-Nucleotidase↗
PubMed1987

Nucleotide sequence of the bovine parainfluenza 3 virus genome: its 3' end and the genes of NP, P, C and M proteins.

We present the nucleotide sequence of bovine parainfluenza 3 virus (BPIV3) genome from its 3' end to the opening region of the F gene, through the NP, P plus C, and M genes. Comparison of the sequence with those reported for other paramyxoviruses indicated that BPIV3 was most similar to human parainfluenza 3 virus (HPIV3), and also very similar to Sendai virus in the structural make-up of its genome and the amino acid sequences of its gene products, suggesting that these three viruses constitute a paramyxovirus subgroup from which Newcastle disease and measles viruses are separable. In BPIV3 and Sendai virus, the NP and M proteins, the main structural elements, were more highly conserved than the functionally important P and C proteins. This tendency was also observed even in BPIV3 and HPIV3. Virus-specific amino acid sequences of the NP and M proteins were found at the carboxyl and amino terminal regions, respectively. BPIV3 M mRNA was found to have aberrations in its poly A attachment site.

Amino Acid Sequence↗
PubMed1987

Nucleotide sequence of the bovine parainfluenza 3 virus genome: the genes of the F and HN glycoproteins.

By analysing complementary DNA clones constructed from genomic RNA of bovine parainfluenza 3 virus (BPIV3), we determined the nucleotide sequence of the region containing the entire F and HN genes. Their deduced amino acid sequences showed about 80% homologies with those of human parainfluenza 3 virus (HPIV3), about 45% with those of Sendai virus, and about 20% with those of SV5 and Newcastle disease virus (NDV), indicating, together with the results described in the preceding paper on the NP, P, C and M proteins of BPIV3, that BPIV3, HPIV3 and Sendai virus constitute a paramyxovirus subgroup, and that BPIV3 and HPIV3 are very closely related. The F and HN proteins of all these viruses, including SV5 and NDV, however, were shown to have protein-specific structures as well as short but well-conserved amino acid sequences, suggesting that these structures and sequences are related to the activities of these glycoproteins.

Amino Acid Sequence↗
PubMed1987

Neurulation in the mouse. I. The ontogenesis of neural segments and the determination of topographical regions in a central nervous system.

Ontogenesis of neural segments and positional relationships between the segments and other organs during neurulation were studied in 1,423 ICR mouse embryos by binocular dissecting, light, and scanning electron microscopy. Late in the presomite stage, two transverse sulci, preotic and otic, were seen on the prospective luminal surface of the neural folds. By somite stage 19, the former subdivided into five neuromeres, and by somite stage 21, the latter subdivided into four neuromeres. From the rostral, preotic sulcus, moreover, five other neuromeres were formed by somite stage 20, and between the otic sulcus and the first somite, two neuromeres were formed by somite stage 28. In the caudal part, from the level of the first somite, a total of 39 neuromeres were formed one after another by somite stage 39, and their positions almost correlated with each corresponding somite. Furthermore, the isthmus grew in the boundary between the fifth and sixth neuromere. The most protruding zone in the preotic sulcus formed the eighth neuromere and was located adjacent to the first branchial arch and the trigeminal ganglion. The most protruding zone in the otic sulcus also formed the 11th neuromere and was located adjacent to the second branchial arch. The 12th and 13th neuromeres were situated adjacent to the otic vesicle; the 23rd to 28th neuromeres, adjacent to the forelimb bud; and the 40th to 46th neuromeres, adjacent to the hindlimb bud.

Animals↗
PubMed1987

Pelvic lymph node metastasis of uterine cervical cancer.

The state of pelvic lymph node metastasis was observed in 627 cases of Okabayashi's radical hysterectomy performed from 1950 to 1984 of which 589 cases with a known 5-year survival rate were examined according to their relationship to prognosis. The incidence of lymph node metastasis was 29.7%, becoming progressively higher with succeeding clinical stages. The metastasis rates according to site were 6.9% hypogastric nodes, 4.9% obturator nodes, 4.4% iliac nodes, and 25.0% parametrial nodes. Among the factors considered in the postoperative classification, lymph node metastasis demonstrated high values in cervical infiltration cancer, positive parametrial infiltration, positive vaginal invasion, and infiltration into the uterine body and L type of CPL classification. The 5-year survival rate was 83.0% in negative cases of pelvic lymph node metastasis, while in positive cases, it was as poor as 45.8%. Considering the relationship of various factors, it is shown that the presence of lymph node metastasis has a great effect on prognosis.

Female↗
PubMed1987

Hyperactivity of Ca channels in vasa deferentia smooth muscle of diabetic rats.

Contractile responses of strips of the prostatic end of vasa deferentia isolated from streptozotocin-treated diabetic rats were investigated with five agonists. Agonists induced similar biphasic responses in vasa deferentia from diabetic and age-matched control rats six to seven weeks after streptozotocin. Twitches were observed superimposed on contractions induced by the adrenergic agonists in strips from most of the diabetic rats. Strips from the diabetic rats developed significantly greater tension than those from the controls. Especially, strips from diabetics had remarkably greater dose-related responses to Ca, and greater Ca influx, than controls when tested in the presence of either KCl or clonidine. The results suggest that both voltage-dependent Ca channels and receptor-operated Ca channels contribute to potentiation of contractile responses in diabetes.

Animals↗
PubMed1987

Properties of the membrane-bound 5'-nucleotidase and utilization of extracellular ATP in Vibrio parahaemolyticus.

Vibrio parahaemolyticus utilized ATP, ADP or AMP as the sole source of carbon. About three times higher activity of membrane-bound 5'-nucleotidase was observed in cells grown in the presence of these nucleotides than in their absence: and therefore the enzyme seems to be inducible. Since the 5'-nucleotidase activity could be measured with whole cells, the active site of this enzyme appears to be outwardly oriented. Both Mg2+ and Cl- were required for activity. Among the divalent cations tested, Mn2+ and Co2+ could replace Mg2+ to some extent, whereas Zn2+ strongly inhibited activity. Among the anions tested, Br-, I- and NO3- could replace Cl-, but SO4(2-) and CH3COO- could not. When cells were grown with ATP, Cl- was indispensable and Zn2+ strongly inhibited growth. Therefore, it is concluded that extracellular ATP and other 5'-nucleotides are cleaved by the membrane-bound 5'-nucleotidase outside the cells and that the adenosine produced is then utilized.

5'-Nucleotidase↗
PubMed1987

Isolation and Characterization of a Catabolite Repression-Insensitive Mutant of a Methanol Yeast, Candida boidinii A5, Producing Alcohol Oxidase in Glucose-Containing Medium.

Mutants exhibiting alcohol oxidase (EC 1.1.3.13) activity when grown on glucose in the presence of methanol were found among 2-deoxyglucose-resistant mutants derived from a methanol yeast, Candida boidinii A5. One of these mutants, strain ADU-15, showed the highest alcohol oxidase activity in glucose-containing medium. The growth characteristics and also the induction and degradation of alcohol oxidase were compared with the parent strain and mutant strain ADU-15. In the parent strain, initiation of alcohol oxidase synthesis was delayed by the addition of 0.5% glucose to the methanol medium, whereas it was not delayed in mutant strain ADU-15. This showed that alcohol oxidase underwent repression by glucose. On the other hand, degradation of alcohol oxidase after transfer of the cells from methanol to glucose medium (catabolite inactivation) was observed to proceed at similar rates in parent and mutant strains. The results of immunochemical titration experiments suggest that catabolite inactivation of alcohol oxidase is coupled with a quantitative change in the enzyme. Mutant strain ADU-15 was proved to be a catabolite repression-insensitive mutant and to produce alcohol oxidase in the presence of glucose. However, it was not an overproducer of alcohol oxidase and, in both the parent and mutant strains, alcohol oxidase was completely repressed by ethanol.

Journal Article↗
PubMed1987

The mode of action of ifenprodil tartrate in isolated canine cerebral and femoral arteries.

Tension of isolated rings of cerebral and femoral arteries was measured isometrically and Ca2+ movement in these arteries was measured by 45Ca flux to study the mode of action of ifenprodil tartrate (IFT). IFT (10(-7)-10(-4) M) induced relaxation in basilar and femoral arteries contracted by K+ (50 mM). During normoxia (O2 aeration) it induced contraction in arteries contracted by prostaglandin (PG)F2 alpha (10(-5) M), but induced relaxation during hypoxia (N2 aeration). In K+-induced contraction the relaxed tension induced by IFT was reversed by addition of Ca2+ in a dose-dependent manner. The IFT induced relaxation of femoral arteries contracted by K+ was attenuated in Ca2+-free solution containing 0.1 mM EGTA, and the effect of IFT on basilar and femoral arteries contracted by PGF2 alpha was reversed. IFT inhibited K+-induced Ca2+ uptake in cerebral and femoral arteries. IFT enhanced PGF2 alpha-induced Ca2+ uptake in cerebral arteries under normoxia, but inhibited it under hypoxia. The results suggest that the action of IFT may be due to alteration of Ca2+ utilization by vascular cells through blockade of potential-sensitive channels, and this action may reflect regional differences between arteries.

Adrenergic alpha-Antagonists↗
PubMed1987

Enhanced percutaneous absorption of ionizable water-soluble drugs.

The percutaneous absorption of diltiazem hydrochloride (DIL) and disodium cromoglycate (DSCG) [representative, respectively, of cationic and anionic water-soluble drugs] was studied in rabbits, using films prepared from water-soluble components. When corresponding fat-soluble counter-ions were added to films prepared using the electrically neutral components polyvinylalcohol and glycerol, the percutaneous absorption of the drugs was enhanced. Furthermore, when non-electrolytes such as BL-9EX or urea were added to the films together with the counter-ions, the bioavailability of the drugs increased. Consequently, it is postulated that ionizable water-soluble drugs are absorbed through skin by forming fat-soluble ion-pairs and additionally that the barrier function against absorption is reduced by non-electrolytes such as BL-9EX or urea. Such non-electrolytes must not hinder the formation of ion-pairs between the drugs and corresponding counter-ions.

Animals↗