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Biomedical subjects

A Maeda

Publications and source records attributed to A Maeda.

At least 325 records · Page 18Linked to original sources
PubMed1990

Rapid focus reduction neutralization test of influenza A and B viruses in microtiter system.

A rapid neutralization test for influenza A and B viruses was developed. In this method, a 96-well tissue culture plate was used for the preparation of cell monolayers and the peroxidase-antiperoxidase staining technique was used for the visualization of foci infected with these viruses. In the presence of trypsin and tragacanth gum, clear foci developed 1 day after infection. A linear relationship between virus dilutions and numbers of foci was observed. When neutralizing antibodies in some test sera were assayed, a good correlation was observed between the titers obtained by the focus method and those obtained by the ordinary plaque method. In addition, many serum specimens were investigated by the neutralization test, and it was demonstrated that the test is useful for serological studies of influenza.

Animals↗
PubMed1989

[Effect of trazodone (KB-831) and its metabolites on brain monoamines in rat].

The effects of trazodone (KB-831) and its metabolites on the uptake, turnover and contents of monoamines in rats were studied in comparison with those of imipramine and mianserin. Trazodone exhibited a more potent inhibitory effect on the uptake of [3H] 5-hydroxytryptamine (5-HT) into brain synaptosomes than on the uptake of [3H]norepinephrine (NE). Trazodone at 10-30 mg/kg, p.o., also inhibited the p-chloramphetamine-induced depletion of 5-HT in rat brain, but not the 6-hydroxydopamine-induced NE depletion in rat heart. Trazodone was the most selective 5-HT uptake inhibitor among the drugs tested in vitro. Its metabolite, m-chlorophenyl-piperazine (m-CPP), inhibited 5-HT and NE uptake in vitro, but not in vivo. Trazodone (100 mg/kg) and imipramine (30-100 mg/kg) inhibited the depletion of NE induced by alpha-methyl-p-tyrosine, whereas mianserin (100 mg/kg) facilitated it. At 1 hr after a single administration of each drug, an increase in 5-HT content and a decrease in 5-hydroxyindole-3-acetic acid (5-HIAA) content were observed when 30 mg/kg trazodone was used. At 100 mg/kg, trazodone increased the levels of dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and decreased the NE content. m-CPP (10-30 mg/kg) produced similar effects on monoamine contents to those of trazodone. Imipramine and mianserin had no effect on monoamine contents even at a dose of 100 mg/kg. After 3 weeks of successive administration, an increase in 5-HT and a decrease in 5-HIAA were induced by trazodone and m-CPP at 1 hr, but not at 17 hr, after the final administration. Imipramine decreased the contents of NE and 5-HIAA, and its effects lasted for 17 hr. These results suggest that trazodone is a selective 5-HT uptake inhibitor and that its neurochemical profile is different from those of imipramine and mianserin.

Animals↗
PubMed1989

[Statistical study of factors related to occurrence and progression of retinopathy in extremely premature infants: especially clinical changes in PaCO2 and pH].

Out of 39 premature infants admitted to the NICU in Toho University Hospital from January 1983 to December 1985 and surviving for 2 months after birth, 22 extremely premature infants who were closely matched in terms of gestational age and body weight at birth were divided into 4 groups (operated group, non-operated A group, non-operated B group and broncho-pulmonary dysplasia (BPD) group) to assess the effect of respiratory management on retinopathy of prematurity (ROP). ROP occurred at a high frequency in extremely premature infants weighing less than 1,000 g. In most of the infants who underwent operation (cryocauterization), PaCO2 values were low for 1 month after birth, whereas pH tended to rise. In the non-operated B group, PaCO2 was almost normal, and pH tended toward acidosis. BPD, which causes severe respiratory disturbance, was observed in 4 cases, 3 of whom showed a rise in PaCO2 within 1 month after birth, but mild ROP. Thus, it was considered that PaCO2 and pH exacerbated ROP.

Carbon Dioxide↗
PubMed1989

Selective effector coupling of muscarinic acetylcholine receptor subtypes.

Attempts have been made by means of recombinant DNA technology to understand the molecular basis of the functional heterogeneity of the muscarinic acetylcholine receptor (mAChR). Molecularly defined mAChR subtypes have been produced from the cloned DNAs in Xenopus oocytes and NG108-15 neuroblastoma-glioma hybrid cells as transient and stable expression systems, respectively, and agonist-induced cellular responses have been examined. The results obtained provide evidence that mAChR subtypes are selectively coupled with different effector systems, albeit not exclusively.

Animals↗
PubMed1988

Different sensitivities to agonist of muscarinic acetylcholine receptor subtypes.

Muscarinic acetylcholine receptor (mAChR) III expressed in Xenopus oocytes, like mAChR I, mediates activation of a Ca2+-dependent Cl- current, whereas mAChR IV, like mAChR II, principally induces activation of Na+ and K+ currents in a Ca2+-independent manner. mAChR III has a sensitivity to agonist of about one order of magnitude higher than that of mAChR I in mediating the Ca2+-dependent current response in Xenopus oocytes and in stimulating phosphoinositide hydrolysis in NG108-15 neuroblastoma-glioma hybrid cells. The agonist-binding affinity of mAChR III is also about one order of magnitude higher than that of mAChR I.

Acetylcholine↗
PubMed1988

Tissue distribution of mRNAs encoding muscarinic acetylcholine receptor subtypes.

The tissue distribution of the mRNAs encoding muscarinic acetylcholine receptors (mAChRs) I, II, III and IV has been investigated by blot hybridization analysis with specific probes. This study indicates that exocrine glands contain both mAChR I and III mRNAs, whereas smooth muscles contain both mAChR II and III mRNAs. All four mAChR mRNAs are present in cerebrum, whereas only mAChR II mRNA is found in heart.

Animals↗
PubMed1988

Selective coupling with K+ currents of muscarinic acetylcholine receptor subtypes in NG108-15 cells.

The primary structures of two muscarinic acetylcholine receptor (mAChR) species, designated as mAChR I and mAChR II, have been elucidated by cloning and sequence analysis of DNAs complementary to the porcine cerebral and cardiac messenger RNAs, respectively. mAChR I and mAChR II expressed in Xenopus oocytes differ from each other both in acetylcholine-induced response and in antagonist binding properties. These results, together with the differential tissue location of the two mAChR mRNAs, have indicated that pharmacologically distinguishable subtypes of the mAChR represent distinct gene products. The primary structures of two additional mammalian mAChR species, designated as mAChR III and mAChR IV, have subsequently been deduced from the nucleotide sequences of the cloned cDNAs or genomic DNAs. We report here that mAChR I and mAChR III expressed in NG108-15 neuroblastoma-glioma hybrid cells, but not mAChR II and mAChR IV, efficiently mediate phosphoinositide hydrolysis, activation of a Ca2+-dependent K+ current and inhibition of the M-current, a voltage-dependent K+ current sensitive to muscarinic agonists.

Acetylcholine↗