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Biomedical subjects

K Hotta

Publications and source records attributed to K Hotta.

At least 253 records · Page 14Linked to original sources
PubMed1986

Gastric mucus glycoprotein in different rat strains.

The extent of gastric damage induced by aspirin was found to differ according to rat strain. The occurrence of ulcers varied, from high to low, in the following strain order: Donryu, Sprague-Dawley (SD) and Wistar. The content of corpus mucus glycoprotein was essentially the same in all the strains: about 6 mg as hexose of dry tissue. Antral mucus glycoprotein content increased in the order Wistar, SD and Donryu: 7.1, 8.3 and 9.1 mg, respectively. Gastric mucus glycoprotein carbohydrate composition was essentially the same in all three strains. The relatively low proportions of N-acetylglucosamine, galactose and sialic acid from the antrum was a characteristic feature in contrast to mucus glycoprotein from the corpus which contained a high proportion of these sugars.

Animals↗
PubMed1986

Effects of aspirin on gastric mucus glycoprotein in fed and fasted rats.

Gastric lesions induced by aspirin increased the ulcer index and incidence with prolongation of fasting time. Aspirin decreased gastric mucus glycoprotein in both the corpus and antrum. However, the rate of decrease in mucus glycoprotein induced by aspirin differed according to feeding habits and the gastric region. Qualitative change in corpus mucus glycoprotein was induced by aspirin.

Animals↗
PubMed1986

Inhibition of Zn2+-induced potentiation of twitch tension by Ni2+ in frog muscle.

Effect of Ni2+ on Zn2+-induced potentiation of twitch tension was studied electrophysiologically in the toe muscle fibers of Rana catesbeiana. The major findings of this investigation are as follows. When 2 mM Ni2+ was applied to fibers in a normal Ringer's solution containing 50 microM Zn2+ (Zn2+ solution), the Zn2+-potentiated twitch tension decreased remarkably to about one-third of that before Ni2+ treatment. This concentration of Ni2+ caused a 23% decrease in the duration of action potential which had been prolonged by Zn2+ (6.61-5.09 ms). Ni2+ (2 mM) added to normal Ringer's solution led to increases of about 30 and 42% in twitch tension and in the duration of action potential, respectively. A slight increase in the mechanical threshold was induced by 2 mM Ni2+. The inhibitory action of Ni2+ on the twitch tension in Zn2+ solution was larger than that in the case of tetanus tension. Diltiazem (40 microM), a Ca2+ channel blocker, did not inhibit the twitch tension potentiated in Zn2+ solution. These results suggest that the decrease in Zn2+-potentiated twitch tension by Ni2+ may possibly derive from impairment of the propagation of action potential along the T tubules.

Action Potentials↗
PubMed1986

Chemical modification of calcium release from the sarcoplasmic reticulum of mechanically skinned skeletal bullfrog muscle fibers.

Several types of reagents that react with amino acid side chains induced repetitive phasic contracture of skinned skeletal muscle from frogs. The presence of 10 mM procaine or 5 mM magnesium in the medium or disruption of the sarcoplasmic reticulum (SR) eliminated this contracture, indicating that the calcium-induced calcium-release mechanism of SR is involved in the contraction. Dithiothreitol inhibited the contracture induced by chloramine T, N-acetylimidazole, or p-chloromercuriphenylsulfonic acid (pCMPS) but not in the case of carbodiimide, phenylglyoxal, trinitrobenzenesulfonic acid, diethylpyrocarbonate (DEP), or N-chlorosuccinimide (NCS). Therefore, modification of groups other than the sulfhydryl ones seems to induce contractures under such conditions. The amplitude of the caffeine-induced contracture decreased after treatment with pCMPS, DEP, or NCS. NCS shifted the pCa-tension curve toward low pCa in the SR-disrupted fibers. This shift would explain the decrease in the caffeine contracture. It is tentatively concluded that pCMPS and DEP release a large amount of calcium from SR.

Animals↗
PubMed1986

Effect of cimetidine on gastric mucus glycoprotein biosynthesis.

The effects of cimetidine on gastric mucus glycoprotein biosynthesis in rat gastric mucosa were investigated using organ culture technique. 2 h following oral administration of cimetidine (40 mg/kg body weight), corpus tissue was placed in the organ culture. Mucus glycoprotein synthesis was accelerated to 137% of control (p less than 0.01). In order to investigate the direct effect of cimetidine on mucus glycoprotein biosynthesis, corpus tissue was cultured in the medium containing cimetidine. 100 microM cimetidine enhanced mucus glycoprotein biosynthesis to 174% (p less than 0.01). Cimetidine was found to stimulate gastric mucus glycoprotein biosynthesis both in vivo and in vitro.

Animals↗
PubMed1986

Electrical responses of the smooth muscle of the guinea-pig cerebral artery to brief electrical stimulation.

Electrical responses to brief electrical stimulation were investigated in the cerebral artery of a guinea-pig using a microelectrode. A single brief stimulus (0.05 ms) induced a spike potential followed by a depolarizing slow-potential, and these events were associated with muscle contraction. An outward current injected into the smooth muscle cell induced spike potential but failed to induce depolarizing slow-potential. These activities persisted in the presence of TTX (10(-6) M), guanethidine (5 X 10(-6) M), or atropin (10(-5) M). TEA (5 mM) enhanced the amplitude of the spike potential, but not that of the depolarizing slow-potential. When the external Na was reduced, the membrane transiently hyperpolarized. During this period, the depolarizing slow-potential could be evoked. In a Cl-deficient solution, the membrane depolarized and the amplitude of the depolarizing slow-potential decreased. From these observations it is believed that the contribution of K, Na, or Cl is minor. In a 20 mM-Ca solution, a brief stimulation induced neither spike potential nor depolarizing slow-potential, but did induce a hyperpolarizing slow-potential. The hyperpolarizing slow-potential was also induced in a Na-deficient solution, but only after completion of Na re-distribution across the membrane. These observations suggest that a substance released by brief stimulation produces a prolonged change in ionic conductances of the smooth muscle membrane, allowing the muscle to contract for a certain period.

Animals↗
PubMed1986

Bagougeramines A and B, new nucleoside antibiotics produced by a strain of Bacillus circulans. I. Taxonomy of the producing organism and isolation and biological properties of the antibiotics.

A bacterial isolate from soil, designated as TB-2125 had a unique pattern of multiple resistance to aminoglycoside antibiotics (AG) and produced new nucleoside antibiotics. Taxonomic properties of this strain fell into those of Bacillus circulans, providing unique characteristics such as strict susceptibility to acidic pH, motility of colony as well as multiple AG-resistance. Two new antibiotics which were named bagougeramines A and B had a broad antimicrobial activity and a specific activity against the two spotted spider mite.

Animals↗
PubMed1986

Production of novel antibiotic, dopsisamine, by a new subspecies of Nocardiopsis mutabilis with multiple antibiotic resistance.

An actinomycete isolate designated as TS-1980 with multiple resistance to aminoglycoside antibiotics was found to produce novel antibiotics. The strain showed taxonomic features identical to the type strain of Nocardiopsis mutabilis except for the temperature range for growth and the utilization of mannitol and raffinose. Based on the capability of growing at lower temperature range, the strain was named N. mutabilis subsp. cryophilis subsp. nov. Physico-chemical and biological characterization of a purified antibiotic revealed its novel polyamine-type nature with a broad antimicrobial activity. The antibiotic was named dopsisamine.

Actinomycetales↗
PubMed1985

Silver ion-induced tension development and membrane depolarization in frog skeletal muscle fibres.

Silver ions elicit dose-dependently a transient contracture in single fibres of bull-frog toe muscle placed in 0-Ca2+, Cl- -free MOPS solution containing 3 mM Mg2+ and NO3-. To elucidate the mechanisms involved, changes in membrane potential and in tension development were continuously measured following exposure to Ag+. The effect of Ag+ on contraction in fibres in which the membrane had been depolarized by elevating the external K+ concentration was also examined. The major findings of this investigation are as follows. (1) The mechanical threshold was shifted towards more negative potentials by 5 mV (-51 to -56 mV), when Ca2+ and Cl- in the Ringer's solution were replaced with Mg2+ and NO3-, respectively. (2) On the exposure of the fibres to 5 microM Ag+, the membrane potential decreased by 1.6 mV from -87.8 mV and tension was developed. (3) In fibres soaked in a solution containing 10 mM K+ (corresponding to a membrane potential of -69.5 mV), 5 microM Ag+ produced a large contracture similar to that seen in the control solution. (4) The Ag+-induced contracture was inactivated when more than 20 mM K+ was used. (5) The membrane depolarization evoked by either 20 or 50 microM Hg2+ did not produce contraction. (6) Muscle fibres which had been exposed to 20 microM Hg2+ for 5 min responded to 5 microM Ag+ by a transient tension development. These findings strongly suggest that Ag+-induced tension development is not associated with depolarization of the surface membrane but rather is caused by specific actions of Ag+ on membrane proteins in the T-tubules.

Animals↗
PubMed1985

Effects of fasting on mucus glycoprotein biosynthesis in rat stomach.

Biosynthetic activity of gastrin mucus glycoprotein in rats after fasting for 24 and 72 hr was studied by the organ culture technique. Fasting produced a slight reduction in gastric mucus glycoprotein biosynthesis in the corpus and antrum (about 70-90% of fed rats). Sulfation of gastric mucus glycoprotein was restrained in the corpus (18% in control for 72 hr).

Animals↗
PubMed1985

Blood group antigens A, B, H, Lea, Leb, and I(Ma) in resting and tetragastrin stimulated gastric juice of patients with non-neoplastic diseases of the stomach.

In view of the anomalous expression of blood group and related antigens in the gastric mucosae of patients with malignant and premalignant diseases of the stomach, and the potential clinical value of their measurement, a preliminary study has been performed on the blood group antigens A, B, H, Lea, Leb, and I(Ma) in glycoprotein rich extracts of the resting and tetragastrin stimulated gastric juice of patients without evidence of gastric cancer. The aim has been to assess whether the antigenic profiles known to distinguish the gastric mucosae of secretors from those of non-secretors are reflected in the glycoproteins of gastric juice. Antigenic profiles which distinguish secretors from non-secretors were observed in the stimulated rather than the resting gastric juice as follows: the A, B or H antigens but not I(Ma) were strongly expressed in the glycoproteins of secretors, while I(Ma) was the antigen characteristic of non-secretors. On the other hand, there was considerable overlap in the Lea and Leb antigen values in the resting and stimulated gastric juice of secretors and non-secretors. Among these antigens, I(Ma) is known to appear as a neo-antigen in the gastric mucosae of secretors with malignant and premalignant diseases of the stomach. Thus this antigenic determinant is potentially a clinically useful marker in the gastric juice of 75% of the population who are secretors. The clinical value of the levels of this antigen in the gastric juice now deserves investigation.

ABO Blood-Group System↗
PubMed1985

Hg2+-induced contracture in mechanically skinned fibers of frog skeletal muscle.

In mechanically skinned fibers of the semitendinosus muscle of bullfrogs, we examined the role of membrane sulfhydryl groups on Ca2+ release from the sarcoplasmic reticulum (SR). Hg2+, a sulfhydryl reagent (20-100 microM), induced a repetitive contracture of skinned fibers, and this contracture did not occur in skinned fibers in which the SR had been disrupted by treatment with a detergent (Brij 58). Procaine (10 mM), Mg2+ (5 mM), or dithiothreitol (1 mM) blocked the Hg2+-induced contracture. Ag+ or p-chloromercuribenzenesulfonic acid produced similar contractures to that induced by Hg2+. We conclude that Hg2+ releases Ca2+ from SR of a skinned fiber by modifying sulfhydryl groups on the SR membrane, and suggest that the Ca2+ released by Hg2+ may trigger a greater release of Ca2+ from SR to develop tension.

Animals↗
PubMed1985

Characterization of sulfated glycoconjugates in human gastric mucosa.

Radiolabeled glycoconjugates were prepared by incorporation of [35S]sulfate and [3H]glucosamine into the gastric mucosa of human gastric resection specimens, using organ culture techniques. Specimens which incorporated higher amounts of [35S]sulfate into high molecular glycoconjugates (Fr-1) were designated as group I. The average specific activity in Fr-1 of group I was 30 times that of group II, but the glucosamine uptake remained about the same in all cases. All specimens in group I were positive to intestinal metaplasia in their adjacent mucosal area. The sulfated glycoproteins in Fr-1 of group I were found to incorporate 80% of the 35S and the remaining 20% by sulfated glycosaminoglycans. But the glycoconjugates constituting all the Fr-1 of group II were identified as glycoproteins and incorporating 35S only to a small extent were identified as sulfated glycoproteins. The susceptibility of the glycoproteins from group I mucosa to pronase digestion was different from that of group II. The glycoproteins synthesized in group I mucosa were as sulfated glycoproteins as well as nonsulfated glycoproteins and glycosaminoglycans, while the group II glycoproteins consisted primarily of nonsulfated glycoproteins.

Adult↗