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Biomedical subjects

K Hotta

Publications and source records attributed to K Hotta.

At least 271 records · Page 15Linked to original sources
PubMed1985

Transient intracellular calcium movement coupled with mechanical activity of smooth muscle.

Change of intracellular free Ca in smooth muscle was monitored using Quin 2, Ca sensitive fluorescence dye. Upon electrical stimulus, increase of light emission from the sample occurred in two phases. Procaine and caffeine inhibited and facilitated, respectively, the 2nd phase of intensity change, which coincided with the mechanical response. It is concluded that the released Ca from intracellular store sites may play a key role for the mechanical activation of smooth muscles.

Aminoquinolines↗
PubMed1985

Mechanisms involved in contraction of smooth muscles of the rat portal vein as induced by sodium depletion.

Responses to external Na depletion were investigated in the rat portal vein, using a microelectrode and an isometric force transducer. Mechanical response to Na depletion was characterized by a large tonic contraction with phasic contractions in a choline solution, and by phasic contractions without a tonic contraction in a Li solution. An identical depolarization of the membrane occurred in either choline or Li solution. After the tonic contraction was established in the Na-free choline-solution, the vein all but completely relaxed with partial re-admission of Na, while maintaining constant the concentration of choline. The Na-free choline-solution at 13 degrees C did not induce the tonic contraction. In nominal Ca-free solution, no contraction occurred with a depletion of Na. A tonic contraction was also induced by Na depletion in the presence of Mn but not Ca. It is concluded that with depletion of both external and internal Na, Ca and Mn may enter the cell through channels usually occupied by Na.

Animals↗
PubMed1985

Tension development in frog skeletal muscle induced by silver ions.

In single fibers of frog toe muscles placed in a Cl- free MOPS solution containing 1.8 mM Ca2+, tension developed slowly in the presence of very low concentrations of Ag+. This tension was not blocked by the administration of Co2+ or Ni2+. On the other hand, two types of transient tensions developed with the application of 5 microM Ag+, in fibers pretreated with 0-Ca2+ MOPS solution, containing either 2 mM Co2+ or 1mM Ni2+, for 10 min. In the presence of divalent cations or TTX, the first repetitive twitch-like contraction disappeared, indicating this tension is induced by action potentials repeatedly generated by the lack of divalent cations. The 2nd subsequent transient tension was caused by 5 microM Ag+ in the presence of various kinds of divalent cations, or TTX. After reversion to the resting tension, the fiber was contracted by adding more than 0.1 mM of Ca2+ or 25 mM caffeine to the external medium. Even when placed in a Ca2+-free solution containing 3 mM EGTA and 3 mM Mg2+ for 30 min, the fiber still developed an appreciable tension in response to 5 microM Ag+. These findings suggest that a transient development of the Ag+-induced tension does not require the presence of external Ca2+. A specific sulfhydryl reagent, pCMPS, did not contract the muscle fiber. Therefore, Ag+ may develop tension by mediating unknown chemical reaction(s) other than the sulfhydryl group on T-tubular membrane proteins.

4-Chloromercuribenzenesulfonate↗
PubMed1985

New antibiotic-producing streptomycetes, selected by antibiotic resistance as a marker. I. New antibiotic production generated by protoplast fusion treatment between Streptomyces griseus and S. tenjimariensis.

A novel antibiotic was found after performing an interspecific fusion treatment between Streptomyces griseus and S. tenjimariensis by the selection of clones with a unique antibiotic resistance. Nonantibiotic-producing mutants of streptomycin (SM)-producing S. griseus SS-1198 with resistance to SM and istamycin (IS)-producing S. tenjimariensis SS-939 with resistance to kanamycin (KM) were protoplasted, mixed with polyethyleneglycol and regenerated. Resistant clones to both SM and KM were found among spores of the regenerated culture at a frequency of 10(-6). Their growth appearance was identical with that of S. griseus. Antibiotic productivity was found only in clones resistant to both 20 approximately 50 micrograms/ml of KM and 400 micrograms/ml of SM. The antibiotic produced by a selected strain, SK2-52, proved to be different from SM and IS.

Anti-Bacterial Agents↗
PubMed1985

New antibiotic-producing streptomycetes, selected by antibiotic resistance as a marker. II. Features of a new antibiotic-producing clone obtained after fusion treatment.

A new antibiotic-producing Streptomyces strain SK2-52 obtained by a protoplast fusion treatment between Streptomyces griseus NP1-1 and S. tenjimariensis NM16 showed taxonomical features identical with those of S. griseus. The strain resistant to wider range of aminoglycoside antibiotics than the parental strains. This multiple resistance corresponded to the activities of streptomycin kinase and acetyltransferase which were probably derived from S. griseus NP1-1. Clones with fast-growth and reduced antibiotic productivity frequently segregated from strain SK2-52, while their antibiotic resistance was stable. The results suggest that the fusion treatment caused a genetic change in S. griseus which enhanced the expression of genes for unique multiple resistance to aminoglycoside antibiotics and also induced new antibiotic production.

Anti-Bacterial Agents↗
PubMed1985

[Relief of experimental cerebral vasospasm by the intrathecal administration of a calcium antagonist (diltiazem)--in comparison with intra-arterial administration].

The effect of an intra-arterial administration of diltiazem on experimental cerebral vasospasm was previously reported by us. In the present study, the effect of diltiazem on cerebral vasospasm, intracranial pressure and systemic blood pressure were investigated using dogs. Cerebral vasospasm was induced by an injection of 5 ml of autologous blood into the cisterna magna. Diltiazem (10(-6) M) was administrated into the cisterna magna and the dilating effect of the drug on the basilar artery was monitored angiographically. The intrathecal administration of diltiazem relieved the vasospasm for more than 30 minutes, same as that of the intra-arterial administration. However, the intracranial and blood pressures remained unchanged. The changes of concentration of the drug in CSF and plasma following the intracisternal administration of 14C-diltiazem were measured using rabbits. The concentration of an administered diltiazem in CSF and plasma was quickly decreased and reduced to 2% of its initial value after one hour (t1/2 = 8 min). Our results show that even the concentration of diltiazem is very low in CSF, the vasodilating effect continues for more than 30 min. This suggests that the intrathecal administration of diltiazem may be useful for the prevention and treatment of the cerebral vasospasm following subarachnoid hemorrhage.

Animals↗
PubMed1984

Preparation of eight ovalbumin subfractions by combined lectin affinity chromatography.

Ovalbumin was fractionated by successive lectin affinity chromatography using concanavalin A/Sepharose and wheat germ agglutinin/Sepharose. Eight glycoprotein fractions, all behaving as ovalbumin on polyacrylamide gel electrophoresis, were obtained. To characterize the carbohydrate chains, the asparaginyl-carbohydrates were prepared from the Pronase digests of the ovalbumin fractions and their dansyl derivatives were analyzed by high-performance liquid chromatography. The elution profile of the dansylated asparaginyl-carbohydrates from each subfraction was compared with that from the unfractionated ovalbumin. The results indicated that the above eight subfractions could be separated from each other according to their carbohydrate chains and that three of the subfractions were homogeneous with respect to their carbohydrate chains.

Carbohydrate Sequence↗
PubMed1984

Effect of methionine-enkephalin on the spontaneous electrical and mechanical activity of the smooth muscle of the rat portal vein.

In the longitudinal smooth muscle of the isolated rat portal vein, methionine-enkephalin (Met-enkephalin) increased the spontaneous contraction with a concentration as low as 10(-8)M. When the membrane activity was recorded using a microelectrode, Met-enkephalin enhanced the spike burst activity but without any effect on the resting membrane potential. Naloxone, phentolamine, atropine and reserpine pre-treatment did not inhibit the excitatory effect of Met-enkephalin on the spontaneous contraction. These results suggest that the excitatory effect of Met-enkephalin on the mechanisms involved in the automaticity may be a direct action on smooth muscle or relate to presynaptic action on a non-adrenergic non-cholinergic system.

Animals↗
PubMed1984

Comparative study of avian ovalbumins by means of glycosidase treatment and following HPLC analysis of their dansyl glycopeptides.

Dansylated glycopeptides (DNS-GP) derived from ovalbumins (chicken, quail, goose and turkey) were treated with commercial endo-beta-N-acetyl-glucosaminidases (Endo-D and Endo-H). Susceptibility of DNS-GP components against those enzymes was examined by analysing the reaction product by HPLC. As reported previously (H. Iwase, Y. Kato and K. Hotta, 1984, Comp. Biochem. Physiol., 77B, 743-747), DNS-GP from chicken ovalbumin was separated into 13 peaks (C1-13) on HPLC. Beta-galactosidase treatment of the DNS-GP resulted in the disappearance of three peaks and the increase of their neighboring peaks. The results indicated that among 13 DNS-GP components from chicken ovalbumin, three (C6,8,11) were bearing galactose residue at the nonreducing terminal and another three (C7,9,12) would be bearing a galacto- sugar chain from each corresponded component.

Animals↗
PubMed1984

Effects of fasting on mucus glycoprotein in rat stomach.

Quantitative changes and chemical composition of gastric mucus glycoproteins in rats after fasting for 24 and 72 hr were studied. The amount of glycoproteins increased in the corpus mucosa during these periods (220% in control for 72 hr), but remained the same in the antrum. The acidity of corpus glycoproteins decreased during the fasting.

Animals↗
PubMed1984

Anti-mRNA: specific inhibition of translation of single mRNA molecules.

A plasmid was constructed to generate RNA complementary to the beta-galactosidase mRNA under control of the phage lambda PL promoter. When this anti-mRNA was produced, synthesis of beta-galactosidase was dramatically inhibited (98%). Syntheses of galactoside permease and transacetylase, whose coding sequences are downstream of the beta-galactosidase coding region, are inhibited to a lesser degree, 80% and 55%, respectively. The generation of anti-mRNA that can be targeted to inhibit a single species of mRNA molecule within cells provides a potent mechanism by which specific transcripts can be translationally inactivated. This can be used to determine the function of proteins as well as to select cloned genes in a single rapid and convenient step.

Acetyltransferases↗
PubMed1984

Isolation and bacterial expression of a murine alpha leukocyte interferon gene.

A murine alpha interferon gene (MuIFN-alpha A) was isolated from a murine genomic DNA library in phage lambda. The gene was cloned and its sequence determined. It was expressed in Escherichia coli under the control of the trp promoter/operator which resulted in antiviral activity on mouse L-cells. MuIFN-alpha A exhibits 60% homology to HuIFN-alpha A at the amino acid level.

Animals↗
PubMed1984

Purification and characterization of two biosynthetic intermediates of ovalbumin.

Ovalbumin was extracted with a buffered Triton X-100 solution from oviduct slices incubated with [35S]methionine or [2-3H]mannose and was purified by CM-cellulose and Sephacryl S-200 column chromatography. The labeled ovalbumin was fractionated on a concanavalin A (Con A)/Sepharose column at room temperature. Six fractions were separated: Two unadsorbed fractions, OA and OB; and four adsorbed fractions, OC, OD, OE, and OF. Fractions OA, OB, OC, and OD corresponded to the four fractions prepared from unlabeled ovalbumin as previously reported (Iwase, H. et al. (1981) J. Biol. Chem. 256, 5638-5642). Fractions OE and OF were novel constituents of the labeled ovalbumin, although a small amount of OE was also present in unlabeled ovalbumin. Pulse-chase experiments indicated that both OE and OF behaved as biosynthetic intermediates of the other ovalbumin fractions, namely OA, OB, OC, and OD. Partial structural analyses involving endo-beta-N-acetylglucosaminidase treatment and subsequent Bio-Gel P-4 chromatography showed that both OE and OF were composed of components bearing high mannose-type sugar chains which consisted of Man9GlcNAc2, Man8GlcNAc2, or Man7GlcNAc2. We failed to distinguish OF from OE on the basis of their carbohydrate chains. However, on SDS slab gel electrophoresis, the OF band migrated slower than the OE band.

Animals↗
PubMed1984

Effect of temperature and Zn2+ on isometric contractile properties and electrical phenomena of frog (Rana) and Xenopus skeletal muscle fibers.

Effects of temperature and Zn2+ on the isometric contractile properties of toe muscle fibers of Rana catesbeiana and Xenopus laevis were studied. The maximum twitch tension almost doubled when the temperature was lowered from 20 to 4 degrees C in Rana muscles but not in Xenopus muscles, although the duration of action potential in Xenopus muscle was increased slightly more than that seen in the Rana species. The maximum rate of rise of tension was greater in Xenopus muscle than in the Rana muscle, at 20 degrees C. The prolongation of the time-to-peak tension following exposure to low temperature (4 degrees C) was more pronounced in Rana than in Xenopus muscles. These results suggest that the speed of release and reuptake of Ca2+ by the sarcoplasmic reticulum (SR) differs in Rana and Xenopus muscles and that these factors may be related to differences in the SR and the T-tubular morphology. In Rana muscles, Zn2+ prolonged the falling phase of the action potential and potentiated the twitch tension. In Xenopus muscles, Zn2+ marginally prolonged the duration of action potential and the twitch tension was not markedly potentiated. These results indicate that Zn2+ potentiates the twitch by prolonging the action potential and that Rana muscles are more sensitive to the effects of Zn2+.

Action Potentials↗
PubMed1984

Changes of gastric mucus glycoproteins with aspirin administration in rats.

The qualitative changes of gastric mucus glycoproteins occurring after aspirin dosing in rats were further investigated. Mucus glycoprotein contents of test animals were 55 and 53% of the control value at 3 and 7 h after dosing, respectively. The glycoproteins were further fractionated by CM-Sepharose CL-6B chromatography. 5 fractions were separated, 1 unadsorbed (fraction 1) and 4 adsorbed (fractions 2-5). Ratios of the major fractions 1:2:4 were 36:47:17 for control, 40:35:25 3 h after aspirin dosing, and 47:33:20 7 h after aspirin administration. Fractions 1, 2, and 4 corresponded to sulfomucin and sialomucin (relatively high content of sialic acid), sialomucin, and neutral mucin, respectively. While the absolute amount of each mucus glycoprotein fraction decreased with aspirin administration, the diminution of fraction 2 was distinct.

Animals↗