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Biomedical subjects

S Tamura

Publications and source records attributed to S Tamura.

At least 757 records · Page 42Linked to original sources
PubMed1982

Pharmacology of 4-benzyol-1-indancarboxylic acid (TAI-901) and 4-(4-methylbenzoyl)-1-indancarboxylic acid (TAI-908).

Pharmacological studies on the derivatives of 1-indancarboxylic acid yielded 4-benzoyl-1-indancarboxylic acid (TAI-901) and 4-(4-methylbenzoyl)-1-indancarboxylic acid (TAI-908). The relative potency (R.P.) of TAI-901 and TAI-908 assessed in parallel line assays (indomethacin - 1) demonstrated that both compounds were highly analgesic against various noxious stimuli induced in experimental animals. R.P. values of TAI-901 were 1.0, 1.7, 4.4 and 2.8 in the phenylquinone writhing, acetic acid writhing, adjuvant arthritic pain and urate arthritic pain tests, respectively. R.P. values of TAI-908 were 1.6, 2.0, 4.7 and 7.0, respectively, in these tests. Both compounds were more inhibitory than indomethacin against acute inflammation, but less inhibitory against chronic inflammation. The inhibitory activities of TAI-901 and TAI-908 on the prostaglandin biosynthesis by microsomes of rabbit renal medulla were 2.2 and 2.6 times that of indomethacin. TAI-901 was 1/3.8 1/7.1, and TAI-908 was 1/16.7 and 1/12.5 as toxic as indomethacin in male rats and mice, respectively.

Analgesics↗
PubMed1981

Correlation between pharmacological and opiate receptor binding activities of tetrapeptide acylhydrazide analogs of enkephalin.

The pharmacological and opiate receptor binding activities of four synthetic tetrapeptide acylhydrazide analogs of enkephalin (EK compound) were compared with those of reference compounds. EK-159 administered subcutaneously was less analgesic, while EK-209, EK-259 and EK-272 were more potent than morphine in the hot plate, Haffner's and phenylquinone writhing tests in mice. EK-272 being the most active was comparable to what was found with FK-33824. IC50 values of EK compounds in a sodium-free medium in the opiate receptor binding assay were lower than the values seen with morphine. The binding activities of EK compounds in 100 mM NaCl medium showed a clearer correlation with their analgesic activities than was seen in the absence of sodium ion. The binding affinity of EK-272 was the highest and the sodium response ratio (IC50 + NaCl/IC50-NaCl) was slightly lower than that of pentazocine. The analgesic action in rodents, respiratory inhibition in rabbits, inhibition of intestinal movement in mice, and hyperthermic action in rats, were all qualitatively, but not quantitatively similar to the effects seen with morphine. The analgesic action of EK compounds was relatively resistant to the antagonizing effect of naloxone and the EK compounds modified the analgesic action of morphine. These properties were inversely correlated with the sodium response ratios.

Analgesics↗
PubMed1981

Induction of DNA ligase during stimulation of DNA synthesis in intact rat liver by a dietary manipulation.

After a nutritional shift from a protein-free to a diet containing 50% casein, the activity of DNA ligase increases in intact rat liver in correlation with the induction of hepatic DNA replication. The treated rat liver as well as control rat liver contains a single species of DNA ligase having a sedimentation coefficient of about 5.5 S. The administration of cycloheximide in vivo completely inhibits the increase in DNA ligase activity and in DNA synthesis, indicating that DNA ligase is induced in the hepatic cells replicating DNA. In contrast to DNA ligase, DNA kinase is unchanged in the activity level by the dietary manipulation.

Animal Nutritional Physiological Phenomena↗
PubMed1981

Three-dimensional echocardiography for spatial visualization and volume calculation of cardiac structures.

A new computerized image processing system was developed and applied clinically for three-dimensional visualization and volume calculation of cardiac structures, which were recorded in more than seven original two-dimensional echocardiograms in parallel planes. Three-dimensional display of this series of original two-dimensional echocardiograms was performed automatically using an overlaid display with different gray levels designating depths. The limitation of the present study was in the recording of original two-dimensional echocardiograms in parallel planes.

Cardiac Volume↗
PubMed1981

Purification and characterization of Mg2+-dependent glycogen synthase phosphatase (phosphoprotein phosphatase IA) from rat liver.

Phosphoprotein phosphatase IA, which represents the major glycogen synthase phosphatase activity in rat liver cytosol, has been purified to apparent homogeneity by chromatography on DEAE-cellulose, histone - Sepharose-4B and Sephadex G-100. The molecular weight of the purified enzyme was 40 000 by gel filtration and 48 000 by sodium dodecyl sulfate gel electrophoresis, Phosphatase IA is therefore a monomeric protein. When treated with 80% ethanol at room temperature, phosphatase IA underwent an inactivation which was totally prevented by 2 mM MgCl2. Catalytically, phosphatase IA has a preference for glycogen synthase D compared with phosphatases IB and II and obligatorily requires Mg2+ or Mn2+ for activity. Maximum activity was attained at 5 mM MgCl2. Since Mg2+ does not activate other phosphoprotein phosphatases in rat liver cytosol, we propose the term 'Mg2+-dependent glycogen synthase phosphatase' for phosphatase IA.

Animals↗
PubMed1981

Characterization of DNA kinase from calf thymus.

DNA kinase has been purified to homogeneity from calf thymus. The purified enzyme, with a specific activity of 16.7 units/mg protein at 25 degrees C, exhibited a sharp pH/activity curve with a pH optimum at 5.5 and low activity at alkaline pH. The molecular weight of the enzyme was estimated by dodecylsulfate/polyacrylamide gel electrophoresis to be 5.4 X 10(4). The enzyme has a sedimentation coefficient of 4.0 S. An apparent molecular weight of 5.6 X 10(4) and a Stokes' radius of 3.3 nm were estimated by gel-filtration on Sephadex G-100. The enzyme phosphorylates neither yeast RNA nor poly(A) instead of DNA. Compared with rat liver DNA kinase, calf thymus DNA kinase is relatively resistant to the inhibition by sulfate (Ki = 7 mM) and pyrophosphate (Ki = 5 mM). The enzyme activity is markedly stimulated by polyamines at the sub-optimal concentration of Mg2+ but not by monovalent cations.

Animals↗
PubMed1981

Inhibition of prostaglandin biosynthesis by clidanac and related compounds: structural and conformational requirements for PG synthetase inhibition.

The inhibition of prostaglandin (PG) biosynthesis by clidanac (6-chloro-5-cyclohexyl-1-indancarboxylic acid, TAI-284), its metabolites and some analogues has been examined using various microsomal preparations as enzyme source. Clidanac and some analogues were among the most potent inhibitors. The (+)-isomer of clidanac was shown to be 1000 times more potent than the (-)-isomer in inhibiting PG synthetase activity. The cis-3'-hydroxyl metabolite which retains anti-inflammatory activity comparable to that of clidanac had much less inhibitory activity. Structure-activity studies with clidanac analogues showed that the position of halogen substitution in 1-indancarboxylic acid is of considerable significance for the conformational requirement for binding to the enzyme.

Animals↗
PubMed1981

Optical isomerization of R(-)-clidanac to the biologically active S(+)-isomer in guinea-pigs.

Optical isomerization of clidanac (RS-6-chloro-5-cyclohexyl-1-indancarboxylic acid, I), an anti-inflammatory drug having a chiral centre in its molecule, was evaluated in guinea-pigs. After oral administration of R(-)-I, the biologically active S(+)-isomer was detectable in the plasma, in the early stages. At 3 h after dosing R(-)-I, the plasma contained above 90% of the S(+)-isomer. Little conversion of S(+)-I to R(-)-I was observed. This may account for the equivalent in vivo activities of R(-)- and S(+)-I in this species. Determination of the enantiomeric composition required derivatization of the enantiomers to their diastereomeric amides after which thin layer chromatography (t.l.c.) was used for the separation. The quantitative determination of the compounds so-separated was accomplished by in situ measurements of the u.v.-reflectance. The t.l.c.-u.v.-densitometric procedure was also used to determine the plasma concentration of I.

Animals↗
PubMed1981

Fine structural aspects on the cold follicles in the aged mouse thyroid.

Age related changed of TSH-responsiveness and the iodinating capacity of thyroid follicles in mice 3, 10 and 19-20 months of age were investigated by light and electron microscopy partly using 125I radioautography. In 3-month-old mice almost all the thyroid follicles respond to exogenous TSH stimulation and many reabsorbed colloid droplets appear in most follicle epithelial cells. In aged mice extremely large follicles appear in the thyroid. Though some of them react to TSH, others do not show any responsibility to repeated injections of TSH. In 10-month-old mice, TSH-unresponsive follicles occupy about 4.5% of the total number of follicles, and in 19-20-month-old animals about 20%. The follicles of this type, named "cold" follicles, are very large in size and fail to concentrate radioiodine even after repeated injections of TSH. The large lumina of these follicles are surrounded by strongly attenuated epithelial cells. The apical surfaces of these atrophied cells are almost flat. The cytoplasm is occupied by large mitochondria, large secondary lysosomes, rough endoplasmic reticulum with dilated cisternae, and small Golgi apparatus. Some cells in normal follicles are degenerated without losing their cuboidal or columnar shape, showing swelling of the cisternae of rough endoplasmic reticulum and accumulation of secondary lysosomes. The present study indicates that the aging of the thyroid may be manifested by two changes: one is the appearance of "cold" follicles surrounded by attenuated and atrophied cells, and the other is degeneration in normal-shaped, TSH-reactive follicles.

Aging↗
PubMed1981

Effect of organic thio-compounds on detoxication of glucuronyltransferase and beta-glucuronidase in the rat liver.

In this study, an effect of single administration of organic thio-compounds on the combined use with uridine diphosphate glucuronic acid was investigated. In the single administration of organic thio-compounds to Wistar strain rats, the synthesis of glucuronide was slightly accelerated by glutathione or methionine, but it was not so much as in the single administration of UDPGA. The glucuronyltransferase activity was accelerated, when either taurine or methionine was administered in combination with UDPGA. None of these organic thio-compounds used in this study showed more significant inhibitory action of beta-glucuronidase activity than UDPGA in the single administration. It was perceived, however that the inhibitory action of beta-glucuronidase activity was much accelerated, when UDPGA was administered in combination either with taurine or methionine. In the administration of organic thio-compounds to Gunn strain rats, cysteine was detected to be the compound which accelerated the synthesis of glucuronide. It was also noted that no organic thio-compounds used in this study affected as influence on beta-glucuronidase activity.

Animals↗