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Biomedical subjects

M Kawamura

Publications and source records attributed to M Kawamura.

At least 811 records · Page 45Linked to original sources
PubMed1985

Time-dependent inhibition of the cyclooxygenase pathway by 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid.

We examined effects of small dose (1 microM or less) of exogenous 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid (12-HPETE) on the formation of cyclooxygenase products from exogenous arachidonic acid (AA) in washed human platelets. With a simultaneous addition of AA, 12-HPETE did not affect the formation of thromboxane (TX)B2 and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT). However, by being preincubated with platelets before an addition of AA, 0.1 microM or greater of 12-HPETE inhibited the formation of TXB2 and HHT dose-dependently. In addition, the inhibitory effect of 12-HPETE increased as the preincubation time was prolonged. These results suggest that 12-HPETE is a strong inhibitor for the cyclooxygenase pathway.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1985

Papain digestion of the subunits of (Na,K)-ATPase.

Membrane-bound (Na,K)-ATPases were exposed to limited papain digestion. We could not find the active (Na,K)-ATPase lacking glycoprotein subunit for the enzymes from three different sources (outer medulla of dog kidney, electric organs of Narke japonica and larvae of Artemia salina). It seemed unlikely that the glycoprotein subunit was selectively removed from (Na,K)-ATPase by papain digestion.

Animals↗
PubMed1985

The amino acid sequence of the fluorescein-labeled peptides of electric ray and brine shrimp (Na,K)-ATPase.

(Na,K)-ATPase from Torpedo californica (electric ray) and Artemia salina (brine shrimp) was labeled with fluorescein 5'-isothiocyanate (FITC) with concomitant loss of activity. Both inactivation and binding were inhibited in the presence of ATP. The sequence of the peptide resulting from tryptic digest containing labeled lysine from both enzymes is Tyr-Leu-Leu-Val-Met-Lys*-Gly-Ala-Pro-Glu-Arg. Thus the primary structure of this region is shown to be conserved in the enzymes of a nonvertebrate and a vertebrate.

Amino Acid Sequence↗
PubMed1985

Action of a cysteine proteinase from pupae of the blowfly Aldrichina grahami on the oxidized B-chain of bovine insulin.

A cysteine proteinase purified from pupae of the blowfly (A. grahami) was tested for its peptide-bond specificity against the oxidized B-chain of insulin. Fifteen peptides were separated on HPLC using both gradient and isocratic elution methods. Analyses of amino acid content and N-terminal amino acids indicated that these were eleven homogeneous peptides produced by digestion and undigested insulin B-chain. Glu13-Ala14 and Tyr26-Thr27 were the major cleavage sites, and Asn3-Gln4, Cys7-Gly8, Tyr16-Leu17, Leu17-Val18 and Cys19-Gly20 were also often cleaved. These findings show the similarity between this enzyme and cathepsin L.

Amino Acid Sequence↗
PubMed1985

[Chronopharmacological study of physical dependence on morphine in rats].

Relationship between withdrawal time or naloxone injection time and withdrawal signs were examined in morphine-treated rats. Sixty-five rats were treated chronically with morphine-admixed food (1 mg/g food) for 7 days and were divided into 13 groups. The rats of 4 groups were abruptly withdrawn from morphine, and the rats of another 4 groups were given naloxone (3 mg/kg, s.c.) at 20:00 on the 8 th day and 2:00, 8:00 and 14:00 on the 9 th day after the morphine administration, respectively. Withdrawal signs were observed at intervals of 2 hr. After each naloxone injection, abnormal behaviors were observed for 60 min, and body weight was measured for 3 hr at intervals of 15 or 30 min. In the withdrawal test, weight loss at 24 hr after withdrawal in each group was approximately 10%, and there was no difference between each group. However, the body weight of non-treated rats and morphine-treated rats increased during the night period (20:00-8:00) and decreased during the daytime (8:00-20:00). Therefore, body weight reached the minimum at 20:00, and then this time is appropriated for withdrawal. In the naloxone test, withdrawal signs in the night period were more potent than that in the daytime. The withdrawal signs induced by naloxone at 8:00 showed the maximum magnitude. Plasma morphine levels in rats treated with morphine-admixed food were high in the night period and low in the daytime. These results suggest that the magnitude of naloxone-precipitated withdrawal signs depends on the amount of morphine in the plasma.

Animals↗
PubMed1985

Corticoidogenic effect of acetylcholine in bovine adrenocortical cells.

The effect of acetylcholine (ACh) on corticoidogenesis in primary cultured bovine adrenocortical cells was examined. One hour exposure to 10(-3) M ACh resulted in a stimulative effect on corticoidogenesis in the freshly isolated cells, and the effect of ACh grew intense during primary culture and reached the maximum on day 2. ACh showed the effect at a higher concentration than 10(-6) M. Thus the primary 2-day cultured cells were used. The corticoidogenic effect of ACh was inhibited by atropine but not by hexamethonium. The effect of ACh was dose dependent, and the extracellular Ca++ was obligatory in inducing the effect. These results suggest that the corticoidogenic effect of ACh may be due to an increase in Ca++-influx via muscarinic receptor in adrenocortical cells.

Acetylcholine↗
PubMed1985

Effect of dietary taurine on cholesterol gallstone formation and tissue cholesterol contents in mice.

The inhibitory effect of dietary taurine on cholesterol gallstone formation was studied using male mice of Jcl:ICR strain. Mice were provided three kinds of semi-purified diet; a cholesterol-free diet (standard), a lithogenic diet containing 0.5% cholesterol and 0.25% sodium cholate (C-CA), and a lithogenic diet supplemented with 5% taurine. The changes of total cholesterol in serum, cholesterol mass in the liver and the gall bladder, and gallstone incidence were studied as a function of time. Gallstone formation was observed only in the mice fed on the C-CA diet for more than 3 weeks. The changes of serum cholesterol concentration were not consistent with gallstone formation. The cholesterol mass of the liver in taurine-supplemented mice decreased after the 3rd week. Cholesterol content of the gall bladder increased with cholesterol gallstone formation. Therefore, the inhibitory effect of dietary taurine on cholesterol gallstone formation may be related to the decrease in cholesterol content of the liver.

Animals↗
PubMed1985

[Chemotherapy of ovarian cancer based on in vitro (HTCA) and in vivo (nude mice) chemosensitivity testing].

The human tumor clonogenic assay (HTCA) and the human tumor xenograft system implanted in nude mice were performed simultaneously in an ovarian cancer patient as chemosensitivity testing. Eight anticancer drugs (5-FU, MMC, VCR, ACD, BLM, VLB, CDDP, and ADM) were applied to the HTCA and the human tumor xenograft system. In the HTCA, 5-FU and MMC were sensitive, VCR was moderately sensitive, and ACD, BLM, VLB, CDDP, and ADM were resistant. In the human tumor xenograft system, MMC, VCR, and ADM showed tumor regression (++), and CDDP, VLB, BLM, 5-FU, and ACD exhibited no response (-). Two of the three drugs, which were classified as sensitive or intermediately sensitive in the HTCA, showed tumor regression (++) in the human tumor xenograft system. And four of the five drugs, which were resistant in the HTCA, exhibited no response (-) in the human tumor xenograft system. Clinically, PVB therapy (CDDP, VLB, and BLM) was applied to the present patient, but after recurrence, 5-FU + MMC therapy was applied on the basis of the results of the HTCA. In addition, ADM was added with reference to the results of the human tumor xenograft system. As a result of this therapy, the tumor growth was inhibited. It is possible from the present data that simultaneous chemosensitivity testing of the HTCA and the human tumor xenograft system implanted in nude mice is very useful when choosing sensitive anticancer drugs.

Animals↗
PubMed1985

Management of inflammation: lipid peroxide as a parameter for a better understanding of inflammatory processes.

The management of inflammation, based on an overall, coordinated observation of the inflammatory system, requires the assessment of the validity and biological significance of the various components in inflammation, a procedure that is more reliable than the interpretation of individual measurements in isolation. Such an overall approach, here developed from the model of carrageenin-induced inflammation, also predicates that lysosomal enzymes, lipid peroxide and proamidase (related, respectively, to the inflammatory response in a narrow sense, to tissue damage and to tissue repair) are three basic parameters required when studying inflammatory processes. This overall approach, moreover, shows that the inflammatory process must be regarded as being diachronic, and that in the light of the observation of exudate fluid it can be divided into three main stages, namely an early stage of exudation related to lipid peroxide, an intermediate stage of exudate dilution related to granuloma amidase, and a later stage of exudate concentration related to granuloma amidase and plasma protein.

Amidohydrolases↗