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Biomedical subjects

T Udagawa

Publications and source records attributed to T Udagawa.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Impairment of neuromuscular transmission in fatigued canine diaphragm].

The role of impairment of neuromuscular transmission in fatigued canine diaphragm was investigated by comparing the function of fatigued diaphragm with that of neuromuscular junction (NMJ)-blocked diaphragm. Diaphragmatic fatigue was produced by intermittent supramaximal stimulation of bilateral phrenic nerves. Partial NMJ blockade was obtained by vecuronium bromide administered intravenously. During control study, no fade was observed either in integrated diaphragmatic electric activity (Edi) or transdiaphragmatic pressure (Pdi). In fatigued diaphragm, Edi generated by 100 Hz showed a remarkable fade. The fade was prominent in high frequency fatigue. In NMJ-blocked diaphragm, fade was observed in Pdi as well as in Edi produced by 100 Hz. The fade of Edi by 100 Hz was prominent. In low frequency fatigue, both Pdi and Edi produced by 20 Hz test stimulation were significantly lower than control values. These results show that in addition to impairment of excitation-contraction coupling, neuromuscular blockade is involved, at least in part, in low frequency diaphragmatic fatigue.

Animals↗
PubMed1988

[The effect of naproxen on fever following transcatheter arterial embolization of hepatic tumors].

In the cases of trans-catheter arterial embolization (TAE) for hepatic malignancies, naproxen has been evaluated for its antipyretic effect. Each patient not given naproxen manifested a remarkable and prolonged fever despite treatment by antibiotics. In those who received an administration of naproxen, however, a significant suppression of fever was achieved (P 0.01-0.001). No remarkable influence was found on the white blood cell counts, the serum GOT and LDH levels by the naproxen. Similarly, no untoward effect due to naproxen was found on the ulcerogenicity in the gastro-duodenum. Thus, for hepatic malignancies, naproxen could be useful in the symptomatic treatment of a fever following a TAE.

Adult↗
PubMed1987

Conjugation-dependent recovery of the Na+ pump in a mutant of Vibrio alginolyticus lacking three subunits of the Na+ pump.

The Na+ pump-deficient mutant, Nap1, of Vibrio alginolyticus was found to lack three subunits of Na+-dependent NADH:quinone oxidoreductase complex. Although a spontaneous Na+ pump positive revertant did not appear from Nap1, transconjugants that recovered both the Na+ pump activity and the subunits were isolated from Nap1 conjugated with the wild type. Moreover, the wild type was found to contain two different sizes of plasmids. These results suggest the possibility that the Na+ pump is encoded by a plasmid.

Biological Transport, Active↗
PubMed1986

Generation of Na+ electrochemical potential by the Na+-motive NADH oxidase and Na+/H+ antiport system of a moderately halophilic Vibrio costicola.

Cells of Vibrio costicola at pH 8.5 generate both membrane potential (inside negative) and delta pH (inside acidic) in the presence of a proton conductor, carbonyl cyanide m-chlorophenylhydrazone (CCCP). The generation of CCCP-resistant membrane potential was inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide that is known to inhibit the Na+-motive NADH oxidase of Vibrio alginolyticus. NADH oxidase, but not lactate oxidase, of inverted membrane vesicles prepared from V. costicola required Na+ for a maximum activity and was inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide. By the oxidation of NADH, inverted membrane vesicles generated concentration gradients of Na+ across the membrane, whose magnitude was always larger than that of delta pH by about 50 mV. In contrast, magnitudes of delta pH and Na+ concentration gradients generated by the oxidation of lactate were similar. Na+ translocation in the presence of lactate was inhibited by CCCP but little affected by valinomycin. On the other hand, Na+ translocation in the presence of NADH was resistant to CCCP and stimulated by valinomycin. Amiloride, an inhibitor for a eucaryotic Na+/H+ antiport system, inhibited the lactate-dependent Na+ translocation but had little effect on the NADH-dependent Na+ translocation. These results indicate that a primary event of lactate oxidation is the translocation of H+, which then causes the generation of Na+ concentration gradients via the secondary Na+/H+ antiport system. We conclude that the NADH oxidase of V. costicola translocates Na+ as an immediate result of respiration, leading to the generation of Na+ electrochemical potential.

Amiloride↗
PubMed1986

Long-term inhalation studies of diesel exhaust on F344 SPF rats. Incidence of lung cancer and lymphoma.

Chronic inhalation studies of diesel exhaust (SPM 4.9 + 1.6 mg m-3) on SPF Fischer 344 rats were carried out to elucidate its effect on health. The most prominent changes observed were proliferative change of type II alveolar epithelium and respiratory bronchiolar epithelium which appeared after 6 months of exposure, and extended according to the exposure duration to whole exhaust. Neoplastic changes were found in 2-year-exposed rats, some of them being malignant. The rate of malignant tumors was higher in the rats observed for 6 months after 2 years of exposure to whole exhaust. Malignant lymphoma with a highly frequent complication of leukemia was the main cause of death in the rats exposed to filtered as well as whole exhaust, and the rate was significantly higher than that of the control group. Mammary adenoma and fibroma were seen more in the exposed groups than in the control group and multi-tumors were noted only in both exposed groups.

Animals↗