Biomedical subjects

I Maeda

Publications and source records attributed to I Maeda.

At least 73 records · Page 4Linked to original sources

PubMed1991

Automated determination of creatine kinase activity in serum with use of thermostable glucokinase.

We measured creatine kinase (CK, EC 2.7.3.2) activity in serum with a new reagent system utilizing thermostable glucokinase (EC 2.7.1.2). Automated determinations were performed with Toshiba's Model TBA-80S Biochemical Analyzer. Precision studies demonstrated within-run and between-run CVs of 0.4%-2.4% and 2.8%-3.1%, respectively. The response linearity was confirmed for CK activity up to 1000 U/L at 37 degrees C. CK activities correlated well (r = 0.997) with those obtained by the manual method recommended by the German Society for Clinical Chemistry (measuring at 37 degrees C) involving hexokinase (EC 2.7.1.1). However, CK activities measured by our method were consistently higher than those of the hexokinase method at reaction temperatures of 30, 37, and 40 degrees C. These data indicate that the new method with thermostable glucokinase is better than that with thermo-unstable hexokinase for determination of CK activity in serum.

Automation↗

PubMed1990

Changes in insulin receptor kinase with aging in rat skeletal muscle and liver.

To see if insulin receptor kinase activity alters with aging, the activity of wheat germ agglutinin-purified receptor preparations from liver and skeletal muscle was compared in 2-, 4-, 10-, and 20-mo-old rats. Basal and insulin-stimulated autophosphorylation of liver insulin receptor and its kinase activities toward histone 2b and poly(Glu4Tyr1) did not alter with aging. On the other hand, the muscle insulin receptor showed different results. Insulin-stimulated increases of autophosphorylation and the kinase activity toward histone 2b above basal were comparable in the four groups. However, insulin-stimulated phosphorylation of poly(Glu4Tyr1) was decreased in 20-mo-old rats compared with 10- and 4-mo-old rats. These results indicate that insulin receptor kinase activity could vary under certain conditions, depending on the substrate used to measure the activity. It is concluded that insulin receptor kinase activity does not change markedly during the process of aging, although subtle changes seem to exist.

Adenosine Triphosphate↗

PubMed1988

[The development of a high sensitivity and high linearity fluorescence microphotometry system for distribution analysis of neurotransmitter in the brain].

A new fluorescence microphotometry system was developed for analysis of the distributions and amounts of neurotransmitter and its related chemical substances in the smaller brain regions. This system can measure fluorescence intensity of 10,000 points in animal brain slices which were immunohistochemically and histochemically stained. This system mounts a photomultiplier tube of high sensitivity and high linearity to a detector; therefore, this system surpasses in quantitative capability by two figures compared with an image analyzer which uses a high-sensitivity TV camera. The high-precision step-motor scanning stage moves under the objective lens of the fluorescence microscope and analyzes the entire surface of the slice: measuring speed, 250 points/min; maximum measuring area, 76 X 52 mm. The data of fluorescence intensity and position (X and Y value) on the slice are transmitted to a computer, calculated statistically and displayed two- and three-dimensionally. In this study, immunohistochemical distribution and intensity of acetylcholine, choline acetyltransferase and acetylcholinesterase in the rat cervical spinal cord were measured. The distributions of their chemical substances are consistent with previous observations. This system is applicable to a wide range of neuroscience studies.

Acetylcholine↗

PubMed1988

Ocular hypotensive effects of monoamine oxidase-A inhibitors in rabbit.

The effects of monoamine oxidase-A (MAO-A) inhibitors with epinephrine on intraocular pressure in the pigmented rabbit were studied. MAO-A inhibitors were used topically with or without various concentrations of epinephrine. For the measurement of intraocular pressure, applanation pneumatonography was used and tissue MAO activities were determined by radiometric assay. After topical administration with clorgyline, MAO-A activities in the bulbar conjunctiva and the iris-ciliary body were remarkably inhibited, whereas MAO-B inhibition was minimal. Maximal reduction of intraocular pressure with 0.05% epinephrine was 3.2 mmHg. Single administration of clorgyline, amiflamine, moclobemide or CGP 11305-A caused decreases in the intraocular pressure of 2.0, 2.5, 1.8 and 2.4 mmHg, respectively. In the coadministration experiments with epinephrine, the ocular hypotensive effects of epinephrine were potentiated with clorgyline, amiflamine, moclobemide and CGP 11305-A (6.6, 4.8, 5.6 and 5.8 mmHg). On the contrary, they were not influenced by the MAO-B inhibitor deprenyl. These results indicated that MAO-A inhibitors potentiated the ocular hypotensive effects of epinephrine, and that the coadministration of a reversible MAO-A inhibitor with epinephrine might be useful for patients with glaucoma.

Animals↗

PubMed1987