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Biomedical subjects

K Hotta

Publications and source records attributed to K Hotta.

At least 307 records · Page 17Linked to original sources
PubMed1982

Ca2+ release from sarcoplasmic reticulum vesicles derived from longitudinal reticulum and terminal cisternae of frog skeletal muscle.

Fragmented sarcoplasmic reticulum (FSR) of bullfrog skeletal muscle was fractionated into light and heavy sarcoplasmic reticulum (LSR and HSR) by sucrose density gradient centrifugation. Morphological and biochemical studies revealed that large parts of LSR and HSR were derived from longitudinal reticulum and terminal cisternae of SR, respectively. The Ca2+ uptake ability and ATPase activity of LSR were higher than those of HSR. Ca2+ release from Ca2+ preloaded SR vesicles by changing the medium from K-gluconate to KCl was suppressed by addition of 0.3 M sucrose or glucose; there was no correlation between Ca2+ release and membrane potential change either in LSR or HSR vesicles. Dantrolene sodium (DAN, 20 microM) had no effect on Ca2+ release. It is concluded that ion-induced Ca2+ release from SR (both HSR and LSR) in the isolated system is due to an osmotic effect.

Animals↗
PubMed1982

Mechanism of resistance to aminoglycoside antibiotics in nebramycin-producing Streptomyces tenebrarius.

Streptomyces tenebrarius ISP 5477, which produces nebramycins, was highly resistant to the following aminoglycoside antibiotics: neamine, ribostamycin, butirosin A, neomycin B, paromomycin, kanamycin A, dibekacin, gentamicin C complex, lividomycin A, istamycin B and streptomycin. Polyphenylalanine synthesis on the ribosomes of this strain was highly resistant to neamine, ribostamycin, butirosin A, kanamycins A, B and C, dibekacin, gentamicin C complex and istamycin B, moderately resistant to lividomycin A and streptomycin, but sensitive to neomycin B and paromomycin. Moreover, cell free extract of the strain contained phosphotransferase and N-acetyltransferase. The former enzyme was confirmed to be an aminoglycoside 6-phosphotransferase which inactivated streptomycin; the latter inactivated kanamycins B and C, dibekacin, neamine, neomycin B, paromomycin, lividomycin A, butirosin A and ribostamycin, but did not inactivate kanamycin A, gentamicin C complex and sagamicin, suggesting an aminoglycoside 2'-acetyltransferase. These results indicated that the high resistance of S. tenebrarius ISP 5477 to a wide range of aminoglycoside antibiotics is due to ribosomal resistance and to the inactivating enzymes, aminoglycoside N-acetyltransferase(s) and aminoglycoside 6-phosphotransferase.

Acetyltransferases↗
PubMed1981

Ovalbumin subfractionation and individual difference in ovalbumin microheterogeneity.

Purified ovalbumin from hen egg white was fractionated by concanavalin A (Con A)/Sepharose chromatography. Four major fractions were separated, one unadsorbed fraction OA, followed by a minor fraction OA', and three adsorbed fractions OB, OC, and OD. The recovery was over 90%. Fractional ratios (OA:OB:OC:OD) were 16:6:37:41. The amino acid composition of the four fractions were quite similar. Galactose was only detected in OA, and the mannose content in OD was high as compared to that of the other fractions. The glycopeptide resulting from pepsin digestion of ovalbumin was also fractionated by Con A/Sepharose. Four fractions were obtained, and they corresponded to fractions OA, OB, OC, and OD. The amino acid compositions of the peptides were identical, indicating that they were derived from the same region in ovalbumin. In order to study individual differences in ovalbumin microheterogeneity, ovalbumin samples prepared from individual eggs were subfractionated on Con A/Sepharose. Four ovalbumin samples prepared from the eggs of a single hen revealed the same elution profile and the same fractional ratios. Fractional ratios of 17 individual preparations varied from 7:2:19:72 to 27:5:40:28 (OA:OB:OC:OD). A constant relation was found among the fractional ratios: the OB, OC and OD contents were dependent on the OA content, and the proportion of OD was in inverse relation to those of OA and OC. The OB content was low and did not change in all ranges of OA content. The present observations indicate that a single hen produces ovalbumin with qualitatively and quantitatively similar carbohydrate chains by unknown mechanisms; moreover, individual differences exist in ovalbumin microheterogeneity which follow constant patterns.

Amino Acids↗
PubMed1981

Efficacy of anti-ulcer drugs on the recovery of gastric mucosal glycoproteins with aspirin-induced gastric damage in rat.

The efficacy of two anti-ulcer drugs, Cimetidine and Cetraxate, on the mucus glycoproteins of gastric mucosa in the aspirin-induced gastric damage was studied in rats. Simultaneous or previous oral administration of Cimetidine or Cetraxate with aspirin reduced the diminution of the mucus glycoproteins which was occurred by aspirin administration. The recovery of the content of mucus glycoprotein in drug dosed rats occurred within 3 h after aspirin dosing and was nearly 90% of control at 5 h in all cases. Single administration of Cetraxate or Cimetidine produced an increase in the mucus glycoprotein content greater than that of the untreated control. Although a macroscopical method for the measurement of gastric damage was applied to this work, neither erosions nor linear ulcers were observed in all cases except the single administration of aspirin. The biochemical method used should be able to assess the efficacy of drugs on the mucosal lesion which cannot be expressed as the ulcer index.

Animals↗
PubMed1981

Age-related changes of cardiac control function in man. With special reference to heart rate control at rest and during exercise.

Heart rate control function at rest and during exercise in regard to age were studied in 39 healthy male volunteers (age 15 to 75). The heart rate control function during exercise was evaluated by using system analysis of heart rate response to two-step exercises (66 and 84 steps/min). No age-related changes were found in the resting heart rate at supine position or in oxygen consumption at upright rest and during the exercises. However, the mean value and the magnitude of variation of the heart rate at upright rest and the difference of heart rate at upright and supine rest showed significant negative correlations with age. As age advanced, the transfer function of the system during exercise exhibited characteristic changes depending on the frequency ranges. These findings suggest that activity of both sympathetic and parasympathetic nervous systems were depressed at rest, and that contributions of sympathetic and vagal nervous systems during exercise are more enhanced and more depressed, respectively, in older subjects than in younger subjects.

Adolescent↗
PubMed1981

Noradrenaline and calcium induced tension in aortic strips of normotensive and spontaneously hypertensive rats.

Development of tension in aortic helical strips was studied using the male Kyoto Wistar normotensive (KNR) and age-, sex-matched spontaneously hypertensive rats (SHR) (8 to 10 weeks) to clarify the contractile response of vascular smooth muscle in SHR. In Ca2+-containing solution, noradrenaline-induced tension was smaller in SHR than in KNR. After washing the strips with Ca2+-free EGTA solution, the tension that developed by the addition of Ca2+ was greater in SHR than in KNR. Tension induced by the combination of Ca2+ and noradrenaline was the same between the KNR and SHR. It is assumed that these differences between the KNR and SHR aortic strips may be attributed to the abnormal contractility of the vascular smooth muscle in SHR.

Animals↗
PubMed1981

Relationship between membrane potential and calcium ion fluxes in the fragmented sarcoplasmic reticulum.

The relation between membrane potential and Ca2+ fluxes in the skeletal fragmented sarcoplasmic reticulum (FSR) was investigated using cyanine dye (diS-C3-(5) as a potential probe. Change of membrane potential and Ca2+ release from FSR were induced by changing the ionic composition of the medium. When the medium was changed from K-gluconate to Tris-gluconate, a large fluorescence intensity change was observed, while no Ca2+ release occurred. On the other hand, when the medium was changed from K-gluconate to KCl, Ca2+ release occurred notwithstanding a relatively small fluorescence intensity change. This KCl-induced Ca2+ release from FSR was inhibited by the addition of sucrose. Also, the presence of both permeable anion and cation was required for induction of Ca2+ release. These results suggest that there is no correlation between "depolarization" and Ca2+ release. Ca2+ uptake by FSR created the positive-inside potential which was reversed by the application of Ca2+ ionophore A23187. The addition of valinomycin or nigericin, and the replacement of Cl- with gluconate-affected potential formation. These facts suggest that Ca2+ uptake is accompanied by K+ efflux and/or Cl- influx for partial compensation of the change.

Animals↗
PubMed1981

Resistance mechanisms of kanamycin-, neomycin-, and streptomycin-producing streptomycetes to aminoglycoside antibiotics.

Streptomyces kanamyceticus ISP5500, S. fradiae ISP5063 and S. griseus ISP5236, which produce kanamycin, neomycin or streptomycin respectively, were highly resistant to the antibiotics they produced. Polyphenylalanine synthesis in cell free systems was also resistant to the action of the antibiotics. Reciprocal exchange between ribosomes and S150 fractions from the three strains revealed that the S150 fraction of each strain had an enzyme activity that inactivated the appropriate antibiotic whereas the ribosomes were susceptible to the antibiotics. It was concluded that the resistance of the in vitro polyphenylalanine synthesizing systems of these antibiotics was due to the presence of inactivating enzymes. Furthermore, S. fradiae and S. kanamyceticus were highly resistant to aminocyclitol-containing aminoglycoside antibiotics other than those produced by the two strains. In these cases, the inactivating enzymes were found to have a major role in the resistance mechanism. However, the resistance of S. kanamyceticus ISP5500 to streptomycin seems to be due to resistance at the ribosomal level.

Aminoglycosides↗
PubMed1981

Self-resistance of a Streptomyces which produces istamycins.

Streptomyces tenjimariensis SS-939, a producer of istamycins, is highly resistant to its own antibiotics and grows in Tryptic Soy Broth containing istamycin A or B at 3,000 microgram/ml. No istamycin-inactivating enzyme was detected in extracts of strain SS-939. Polyphenylalanine synthesis in an in vitro system, consisting of the S-150 fraction and ribosomes prepared from strain SS-939, was not inhibited by 200 microgram/ml of istamycins. Using reciprocally reconstituted systems consisting of S-150 fractions and ribosomes from strain SS-939 and those from Streptomyces griseus ISP5236 (istamycin-sensitive strain), ribosomes of strain SS-939 were found to be resistant to istamycins. Thus, ribosomes have the main role in the self-resistance mechanism of S. tenjimariensis SS-939.

Aminoglycosides↗
PubMed1981

[The phenol turbidity test for measurement of pulmonary surfactants in amniotic fluid--rapid test for fetal lung maturity (author's transl)].

A simple and sensitive procedure for the quantitative estimation of pulmonary surfactants in the amniotic fluid is described. The method is based on the formation of turbidity from the amniotic fluid surfactants with phenol. Amniotic fluid drawn through an intrauterine catheter was centrifuged at 2000 rpm for 5 min. One ml of 5% aqueous phenol solution was added to 1.0 ml of the diluted supernatant. Control solution was prepared by addition of 1.0 ml of distilled water to the supernatant, instead of phenol solution. The turbidity was measured spectrophotometrically against control at 340 nm 5 to 10 min after agitation on a Vortex mixer for 5 sec. The turbidity obtained from amniotic fluid with phenol was proportional to the increase in total phospholipids in the fluid measured enzymatically. Moreover, only lecithin in the phospholipids was related to the turbidity formation. Sphyngomyelin, lysolecithin, phosphatidylethanolamin did not produce any turbidity with phenol. The spectrophotometric reading of 87 cases (31-41 weeks) was ranged at 0.18-3.52. Four cases with lower value (0.40) showed neonatal respiratory problem. The phenol turbidity test is more useful for the detection of fetal lung maturity comparing with the generally used shake test.

Amniotic Fluid↗
PubMed1980

Autonomic nervous control of the heart in exercising man.

Effects of pharmacological denervation with propranolol (0.2 mg.kg-1) and/or atropine (0.04 mg.kg-1) on the control system of heart rate during exercise were studied using a frequency domain analysis, to evaluate the cardiac control function of autonomic nervous systems in man. Propranolol decreased the gain of the system in low frequency range and increased the gain slightly in middle and high frequency ranges. The phase angle of the system was advanced over the whole frequency range observed. Atropine decreased and delayed the gain and phase angle, respectively, especially in high frequency range. The combined administration of blockades significantly decreased the gain and delayed the phase angle in the whole and high frequency ranges, respectively. These findings suggest that sympathetic and parasympathetic nervous systems act nearly independently in controlling heart rate during exercise; that they act in different manners; and that the characteristics of the systems can feasibly be used to estimate clinically the cardiac control function of autonomic nerves in man.

Adult↗