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Biomedical subjects

T Takagi

Publications and source records attributed to T Takagi.

At least 757 records · Page 42Linked to original sources
PubMed1986

A high molecular weight protease in the cytosol of rat liver. II. Properties of the purified enzyme.

The properties of a soluble endoprotease from rat liver were studied. The enzyme was purified in a latent form. It sedimented as a single component with a sedimentation coefficient (S(0)20,w) of 19.8 S. Measurement by quasi-elastic light scattering gave a diffusion coefficient (D(0)20,w) of 2.5 X 10(-7) cm2 X s-1 and an effective hydrodynamic radius of 85 A. The enzyme had an unusually high molecular weight, estimated as 743,000 by sedimentation equilibrium and 722,000 by sedimentation velocity and diffusion measurements and as 760,000 by a recently developed low-angle laser light scattering method. Judging from electron microscopic observation and the calculated frictional and axial ratios, the enzyme molecule is disc-shaped. Analysis of the far-ultraviolet circular dichroic spectrum showed that the enzyme contains 50% alpha-helical, 25% beta-sheet, and 15% unordered structures with 10% beta-turns. The isoelectric point of the enzyme is 5.0. These properties indicate that the purified enzyme is a homogeneous molecule. In addition, the enzyme is a simple protein since it contains no measurable amounts of nucleic acid carbohydrate or lipid.

Amino Acids↗
PubMed1986

Assessment of the role of non-ADH ethanol oxidation in vivo and in hepatocytes from deermice.

Deermice genetically lacking alcohol dehydrogenase (ADH-) were used to quantitate the effect of 4-methylpyrazole (4-MP) on non-ADH pathways in hepatocytes and in vivo. Although primarily an inhibitor of ADH, 4-methylpyrazole was also found to inhibit competitively the activity of the microsomal ethanol-oxidizing system (MEOS) in deermouse liver microsomes. The degree of 4-MP inhibition in ADH- deermice then served to correct for the effect of 4-MP on non-ADH pathways in deermice having ADH (ADH+). In ADH+ hepatocytes, the percent contributions of non-ADH pathways were calculated to be 28% at 10 mM and 52% at 50 mM ethanol. When a similar correction was applied to in vivo ethanol clearance rates in ADH+ deermice, non-ADH pathways were found to contribute 42% below 10 mM and 63% at 40-70 mM blood ethanol. The catalase inhibitor 3-amino-1,2,4-triazole, while reducing catalase-mediated peroxidation of ethanol by 83-94%, had only a slight effect on blood ethanol clearance at ethanol concentrations below 10 mM, and no effect at all at 40-70 mM ethanol. These results indicate that non-ADH pathways (primarily MEOS) play a significant role in ethanol oxidation in vivo and in hepatocytes in vitro.

Alcohol Dehydrogenase↗
PubMed1986

Amino acid sequence of vitamin D-dependent calcium-binding protein from bovine cerebellum.

The amino acid sequence of vitamin D-dependent calcium-binding protein from bovine cerebellum has been determined. It is composed of 260 amino acid residues and its N-terminus is acetylated. The molecular mass is calculated to be 29 851 Da. The presence of six calcium-binding sites (I-VI) has been proposed, two of them (sites II and VI) have lost their calcium-binding function through amino acid replacements, and the other four are able to bind calcium. Six calcium-binding domains are supposed to be derived from two gene duplications of the two ancestral calcium-binding domains. In comparison with the sequence of chick intestinal calcium-binding protein deduced from a cDNA sequence [(1985) Nucleic Acids Res. 13, 8867-8881], the bovine calcium-binding protein is two amino acid residues shorter at the N-terminus and the other parts show 78.5% identity.

Amino Acid Sequence↗
PubMed1986

Direct current potential changes of the vagal nuclear area induced by trigeminal stimulation.

To elucidate the mechanism of the Reilly syndrome (irritation syndrome), direct current (DC) potential changes in the medulla oblongata were investigated. Ipsilateral and contralateral trigeminal stimulation induced a DC potential shift above the vagal nuclear area in the medulla. Maxillary and mandibular nerve stimulation showed a summation effect. Continuous stimulation of the tooth pulp cavity by croton oil induced a progressively developed DC shift. DC potential change by trigeminal stimulation was accompanied by the same process of elevation of extracellular potassium concentration. These findings suggest that trigeminal stimulation increases the excitability of vagal nuclear neurons and consequently provokes the Reilly syndrome.

Animals↗
PubMed1986

Binding of lithium dodecyl sulfate to polyacrylamide gel at 4 degrees C perturbs electrophoresis of proteins.

Although polyacrylamide gel has no affinity to lithium dodecyl sulfate (LDS) at 25 degrees C, the gel maximally binds 17 mg of LDS per gram dry weight at 4 degrees C. When polyacrylamide gel electrophoresis is carried out at 4 degrees C in the presence of LDS instead of sodium dodecyl sulfate (SDS) using a continuous buffer system, migration of proteins with lower molecular weight is accelerated as a result of the deficiency of LDS in the frontal region of the gel. When the gel is saturated with LDS, electrophoresis in the presence of LDS at 4 degrees C shows a resolution higher than that of SDS-polyacrylamide gel electrophoresis at 25 degrees C.

Electrophoresis, Polyacrylamide Gel↗
PubMed1986

The inhibitory action of melatonin on the contractile response to 5-hydroxytryptamine in various isolated vascular smooth muscles.

The effects of melatonin on the contractile responses to 5-hydroxytryptamine (5-HT), norepinephrine (NE), angiotensin-1 (AT-1) and potassium were determined on the rabbit isolated aorta, iliac and renal arteries. Melatonin, at 10(-4) or 10(-3) M inhibited the response to 5-HT in the aorta, iliac and renal arteries. Melatonin, at 10(-3) M, had a negligible effect on the responses to NE and AT-1 in all preparations used. The potassium-induced contraction of all 3 preparations used was slightly inhibited by only the high concentration of melatonin (10(-3) M). In a Ca+-free medium with EGTA (0.1 mM), the residual response to 5-HT (10(-5) or 10(-4) M) were inhibited by melatonin (10(-4) or 10(-3) M) in all preparations used. In a Ca2+-free medium with EGTA (0.01 mM), nifedipine (10(-6) M) and 5-HT (5 X 10(-7) M), application of Ca2+ (2 mM) resulted in a tonic contraction, related to receptor operated channels, of all preparations. This Ca2+ dependent, nifedipine insensitive contraction was markedly inhibited or abolished by melatonin at 10(-5) and 10(-4) M. These results demonstrated that melatonin had a generally greater inhibitory effect on the response to 5-HT than those to NE, AT-1 and potassium in vascular smooth muscles. Also the results suggest that action of melatonin on the 5-HT induced contraction is more related to interference with Ca2+ influx through receptor operated channels than release of intracellular Ca2+ from the store site.

Angiotensin I↗
PubMed1986

Instability of an arginine-overproducing mutant of Serratia marcescens and its stabilization.

Arginine productivity of an arginine-producing mutant of Serratia marcescens decreased during successive batch culturing. The mutant grew more slowly than the parent strains in a minimal medium, and spontaneously produced derivatives that grew more rapidly than the mutant. A large majority of the derivatives required N-acetylglutamate or arginine for growth, due to lack of N-acetylglutamate synthase, the argA gene product. The argA1 allele carried by the mutant was found to be relatively unstable. While the mutation rate in a stable argA mutant allele was less than 1 X 10(-8) per cell per generation, that in the argA1 allele was 9 X 10(-7). The instability of the arginine productivity, therefore, was owing to both a disadvantage of the mutant in growth and a high mutability in the argA1 allele. In addition to the auxotrophs, the unstable arginine-producing mutant spontaneously produced at low frequency stable arginine-producing derivatives; among them, AT428 formed N-acetylglutamate synthase with a reduced affinity for glutamic acid. The derivative showed restored capability for propagation, and stably produced a large amount of arginine in the presence of glutamic acid or fumaric acid. By transductional analysis, the derivative was found to have acquired in the argA allele an additional mutation leading to the reduced affinity independently of the original one leading to the feedback-resistant enzyme.

Acetyltransferases↗
PubMed1986

Marked effect of cations on the separation of spinach thylakoid chlorophyll-proteins on polyacrylamide gel electrophoresis at 0 degree C in the presence of alkanolammonium dodecyl sulfates.

The separation of spinach thylakoid chlorophyll-proteins on polyacrylamide gel electrophoresis at 0 degrees C in the presence of dodecyl sulfate is markedly influenced by the kind of surfactant cation in the media used for solubilization and electrophoresis. The mode of separation can thus be modulated through the cation selection. Three kinds of alkanolammonium dodecyl sulfates were tested and their abilities as to the dissociation of the molecular assemblies of chlorophyll-proteins were found to decrease in the following order: tris(hydroxymethyl)methylammonium, triethanolammonium and triisopropanolammonium. Comparison of the electrophoretic patterns obtained with different kinds of cation may help clarify the hierarchy of the molecular assemblies of chlorophyll-proteins.

Cations↗
PubMed1986

Ganglioside GM1 localization in cholinergic neurons visualized by use of a double avidin-biotin complex system.

Localization of ganglioside GM1 in cholinergic neurons from the septal area of a primary culture newborn rat brain was studied with a double avidin-biotin complex system. Cholinergic neurons were identified by double immunolabeling techniques that use choline acetyltransferase (ChAT) and neurofilament (NF) protein-antibodies. ChAT-positive neurons also were stained for ganglioside GM1 by using an avidin-biotin complex technique.

Animals↗
PubMed1986

The instantaneous impedance frequency curve of the ventricle with the regional ischemia.

We studied the feasibility of using the impedance frequency curve method (IFM) to detect the myocardial physical heterogeneity of a cross-circulated isolated canine left ventricle with regional ischemia. The curve changed from a single-peak configuration to a double-peak configuration after the LAD coronary flow cessation and returned to the single-peak configuration with the reperfusion of LAD coronary flow. We concluded that IFM can be a useful tool to describe the physical heterogeneity of the ventricular muscle under the regional ischemia.

Animals↗