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Biomedical subjects

Y Takashima

Publications and source records attributed to Y Takashima.

At least 145 records · Page 8Linked to original sources
PubMed1984

Alterations in erythrocyte membrane lipids in abetalipoproteinemia: phospholipid and fatty acyl composition.

Scanning electron microscopic observation revealed that there were wide variations including typical acanthocytes in morphology of erythrocytes from a patient with abetalipoproteinemia. The erythrocyte membrane phospholipids and cholesterol contents from a patient was higher by 25% compared to an age-matched control subject. Analysis of phospholipid composition of red blood cells showed an increase of sphingomyelin (25.1----30.1%) with a concomitant decrease of lecithin (27.5----21.0%). Thus, the sphingomyelin/lecithin ratio was increased dramatically (0.91----1.43). As for fatty acyl chain composition of main phospholipids, an increased percentage of palmitic acid and docosahexaenoic acid and a decreased proportion of arachidonic acid and lignoceric acid were observed for sphingomyelin. There was an increment of palmitic acid which was accompanied with a decrease of linoleic acid in lecithin. On the other hand, no significant difference was shown in the fatty acid composition of phosphatidylethanolamine and phosphatidylserine plus phosphatidylinositol between a patient and control.

Abetalipoproteinemia↗
PubMed1984

7-(Ethoxycarbonyl)-6,8-dimethyl-2-phenyl-1(2H)-phthalazinone derivatives: synthesis and inhibitory effects on platelet aggregation.

7-(Ethoxycarbonyl)-6,8-dimethyl-2-phenyl-1(2H)-phthalazinone derivatives and several analogues were synthesized and their inhibitory effects on platelet aggregation were evaluated. Structure-activity relationships are discussed. All synthesized compounds showed no appreciable effect on platelet aggregation induced by adenosine diphosphate, but most of them inhibited effectively the arachidonic acid induced platelet aggregation. The parent compound, 2-phenyl derivatives, and ortho-substituted 2-phenyl derivatives show the most potent inhibition of all compounds.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

Potentiation of antiaggregating activity of adenosine by a phosphodiesterase inhibitor, EG626 (oxagrelate), in human platelets in vitro.

EG626 (oxagrelate), a specific inhibitor of cyclic AMP phosphodiesterase, produced in vitro a concentration-dependent inhibition of platelet aggregation induced by collagen and ADP in human platelets. When adenosine was added to the platelet rich plasma (PRP) in the presence of a threshold concentration of EG626, the potency of adenosine in inhibiting platelet aggregation was markedly potentiated. This potentiating effect of EG626 proved to be synergistic, but not additive and was accompanied by a marked accumulation of cyclic AMP in the platelets. The antiaggregating and cyclic AMP increasing activities of adenosine were little affected by S-(p-nitrobenzyl)-6-thioguanosine (6TG), an uptake inhibitor of adenosine, or 2'-deoxycoformycin, an inhibitor of adenosine deaminase. The incorporation of adenosine into platelets was abolished by 6TG. These observations indicate that incorporation of adenosine into platelets is not required for inhibition of aggregation or an increase in cyclic AMP and that the site of action of adenosine is probably extracellular. It also appears that the synergistic action by EG626 is not the result of an inhibition of adenosine uptake and/or adenosine deaminase. This speculation is supported in part by the finding that EG626 also potentiates the antiaggregating activity of 2-chloroadenosine. Antiaggregating activity of prostaglandin E1, an activator of adenylate cyclase, was markedly potentiated in combination with EG626. Dibutyryl cyclic AMP showed a time-dependent inhibition of the platelet aggregation, and the inhibitory action was markedly potentiated by EG626. Qualitatively similar results were obtained with another phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX). All these data suggest that the synergistic potentiation of the antiaggregating activity of adenosine by EG626 might be due to the synergistic accumulation of cyclic AMP in the platelets. This action is mediated through activation of adenylate cyclase by adenosine in combination with the inhibition of cyclic AMP phosphodiesterase by EG626.

1-Methyl-3-isobutylxanthine↗
PubMed1984

[Fundamental and clinical studies on ceftazidime in the field of obstetrics and gynecology].

Fundamental and clinical studies were carried out on ceftazidime ( CAZ ), a new cephalosporin antibiotic, with the following results. Following each 1.0 g of drip infusion and bolus intravenous injection, transfer of CAZ to the internal genital organs was found to be good. Transfer of CAZ into exudate of the pelvic dead space was also good. CAZ was given to 6 cases. Clinical efficacy was good in 5 cases and poor in 1 case. No side effects were observed in any case. The above results demonstrated that CAZ is a safe and effective drug.

Adolescent↗
PubMed1983

Vial effect and background subtraction method in low-level tritium measurement by liquid scintillation counter.

Counting efficiencies of individual Teflon vials used in low-level tritium measurement by a liquid scintillation counter were investigated. The efficiency observed was fairly varied among vials in spite of being prepared in the same way. And the plots of the efficiency vs the external standard ratio give a straight line. More detailed investigation showed that this vial quenching and chemical quenching are simultaneously corrected by an external standard ratio. On the basis of the above results an appropriate background subtraction method is proposed.

Environmental Pollutants↗
PubMed1982

Effects of 7-ethoxycarbonyl-6,8-dimethyl-4-hydroxymethyl-1(2H)-phthalazinone (EG626) on the spinal trigeminal nucleus, ventral posteromedial nucleus, and sensory cortex.

Effects of 7-ethoxycarbonyl-6,8-dimethyl-4-hydroxymethyl-1 (2H)-phthalazinone (EG626) on the spinal trigeminal nucleus (STN), ventral posteromedial nucleus (VPM), and sensory cortex were examined in cats anesthetized with alpha-chloralose in comparison with the effects of morphine. EG626 produced a dose-dependent inhibition of the polysynaptic components of the cortical field potentials upon VPM stimulation and either facilitatory or inhibitory effects on the polysynaptic components of the VPM field potential upon stimulation of the medial lemniscus, while the drug failed to affect the STN field potential with trigeminal nerve stimulation. Morphine inhibited the postsynaptic components of the STN field potentials and to a lesser extent, the polysynaptic components of the cortical field potential; and the effects of morphine on the VPM field potential were similar to those seen with EG626. Pretreatment of the animal with naloxone antagonized the facilitatory effect on the VPM field potentials produced by morphine, but not those by EG626. Morphine and EG626 induced either a prolonged increase in the blood flow or transient increase followed by a decrease in the blood flow in the VPM. These results suggest that EG626 may impair the polysynaptic transmission and/or neuron excitability in the sensory cortex and the VPM at least partly due to the change in blood flow there as does morphine. Unlike morphine, however, EG626 did not produce any obvious effect on the STN.

3',5'-Cyclic-AMP Phosphodiesterases↗