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Biomedical subjects

T Sekine

Publications and source records attributed to T Sekine.

At least 217 records · Page 12Linked to original sources
PubMed1987

[Clinical trial of SM-108 in myeloproliferative disorders].

SM-108 (4-carbamoylimidazolium-5-olate) is a new purine antagonist which blocks IMP dehydrogenase, the key enzyme of de novo GMP biosynthesis. Eleven patients were entered into a clinical study of SM-108 for the treatment of myeloproliferative disorders. These included 10 cases of chronic myelogenous leukemia (CML) and one case of essential thrombocythemia (ET). Two cases of CML had received prior chemotherapy. SM-108 was given orally at a dose of 400-600mg/m2 daily. Of nine evaluable cases, four cases of CML achieved complete responses and two cases of CML achieved partial responses (response rate = 66.7%). The duration of drug action was short, and the daily dosage required adjustment at frequent intervals. Long-term response without therapy has not been seen with SM-108 in CML. There was no response in the case of ET. The side effects included constipation (1/11), diarrhea (1/11) and mild hepatic toxicity (1/11). No cardiac or renal toxicity was observed.

Adult↗
PubMed1987

Liver cell myosin: isolation and properties.

We have purified myosin from isolated rabbit liver cells that had been previously shown to be well separated from blood vessels and connective tissue (Okamoto, Y. et al. (1983) J. Biochem. 94, 645-653). It comprises a 200-kDa heavy chain and light chains of 24-kDa, 22-kDa, and 17-kDa. In the light chain composition and in the mobility in PPi-PAGE, liver cell myosin differs from the myosin in liver blood vessels. The light chains of liver cell myosin were phosphorylated by myosin light-chain kinase from chicken gizzard and the Mg2+-ATPase activity of phosphorylated myosin was activated 10-fold by F-actin.

Animals↗
PubMed1987

Gel ointment of verapamil for percutaneous absorption.

A gel ointment of verapamil designed for systemic action by transdermal absorption was prepared. The amount of drug released in vitro decreased progressively when increasing amounts (from 20 to 50%) of ethanol-propylene glycol (2:1, v/v) were incorporated into the ointment. Transdermal absorption of the drug in vivo was studied in rats. Verapamil was found in the systemic circulation, and plasma drug levels were maintained at a plateau for 12 hours after application. The effect of two additives on absorption was also examined. Azone, a cycloheptanone derivative, increased plasma levels of verapamil up to tenfold, the effect being greatly dependent on the amount of alcohols in the formulation. Isopropyl myristate did not influence systemic absorption, but it effectively increased absorption into skin. We conclude that the gel ointment can be used for transdermal drug delivery when an adequate absorption promoter is added.

Administration, Cutaneous↗
PubMed1986

An immunoglobulin G inhibiting lactate dehydrogenase activity.

We found extremely low (6 U/l) serum lactate dehydrogenase (LDH, EC 1.1.1.27) activity in a patient with uterine myoma. The patient's serum inhibited purified LDH isoenzymes. One milliliter serum neutralized 73 U purified LDH-1 isoenzyme, equivalent to 300-500-fold the amount of LDH in 1 ml of normal serum. The serum inhibitor was purified by ordinary procedures using chromatographies and identified as IgG which contains both kappa- and lambda-chains. The IgG is very unique in showing higher affinity to the H- than M-subunit of the LDH tetramer, in contrast with the IgGs already reported. After removal of the myoma, the anti-LDH activity gradually decreased with a half-life of 20 days corresponding to that of IgG and finally almost disappeared. This indicates a possibility that the myoma cells produce some factors such as B-cell growth and differentiation factors.

Chromatography↗
PubMed1986

Difference between subfragment-1 and heavy meromyosin in their interaction with F-actin.

To elucidate the difference between subfragment-1 and heavy meromyosin in their interaction with F-actin, we used limited tryptic digestion and cross-linking with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The binding of actin to subfragment-1 lowers the susceptibility of the 50K-20K junction of its heavy chain to tryptic digestion. At a molar ratio of one actin to one subfragment-1, all the sites were gradually cleaved by trypsin whereas the sites were completely protected in the presence of a 2-fold molar excess of actin over subfragment-1. In the case of heavy meromyosin, nearly half of the sites were protected completely by the presence of an equimolar amount of actin to its heads suggesting that the two heads of heavy meromyosin bound actin in a different manner. The rate of the cross-linking reaction between subfragment-1 heavy chain and actin with 1-ethyl-3-[3-(dimethylamino) propyl]carbodiimide also depended on the molar ratio of actin to subfragment-1. The rate was maximum at a molar ratio of about 5 actin to 1 subfragment-1. When heavy meromyosin was cross-linked to actin, the maximum rate was observed at a molar ratio of about 3 actin to 1 heavy meromyosin head, the level being about 60% that for subfragment-1 and actin. It was suggested that the presence of the subfragment-2 portion of heavy meromyosin caused these differences by restricting the motion of the two heads.

Actins↗
PubMed1986

Proton efflux during Ca2+ uptake in a reconstituted Ca2+ pump system.

Ca2+-pump of sarcoplasmic reticulum was partially purified and solubilized with Triton-X100 in the presence of excess phospholipids. Vesicles were reconstituted by removal of Triton with Amberlite XAD-2 and the subsequent freeze-thaw/sonication method (Kasahara, M. and Hinkle, P. C. (1977) J. Biol. Chem., 252: 7384-7390). In the reconstituted system, H+ was ejected during Ca2+ uptake and in the initial Ca2+ uptake, the molar ratio of ejected H+ to Ca2+ was found to be about 1 in the presence of a permeant anion, SCN-.

Animals↗
PubMed1986

Subcellular fractionation of Trypanosoma cruzi; isolation and characterization of plasma membranes from epimastigotes.

A procedure is described for the isolation of subcellular fractions from epimastigotes of Trypanosoma cruzi. The method could separate most of the nuclei, mitochondria and microsomes. The plasma membranes were purified by discontinuous density gradient centrifugation in alkaline buffer containing sucrose and magnesium. The yield of plasma membrane was 3.7 mg of protein per 10(9) epimastigotes, accounting for approximately 4.2% of the total cell proteins. The plasma membrane obtained from the 34-50% interface of sucrose density gradients was shown, by electron microscopy, to be completely free of other organella and was homogeneous according to enzymatic marker criteria. The specific activity of the 5'-nucleotidase and acid phosphatase were 96- and 5.5-fold, respectively, higher than that in the total cells, suggesting that the enzymes can be considered as good plasma membrane markers for T. cruzi. The results confirmed the possibility of the presence of membrane-bound acid phosphatase of T. cruzi.

Acid Phosphatase↗
PubMed1986

[Primary malignant lymphoma of the rectum--a case report].

The patient was a 69-year-old woman who complained of bloody stools and abdominal pain. A tumor was removed with abdominoperineal excision, and histologic examination revealed malignant lymphoma associated with reactive lymphoreticular hyperplasia. The lesion was of the diffuse, medium-sized cell type according to the classification of the Japan Lymphoma Study Group.

Aged↗
PubMed1985

Location of the SH group of the alkali light chain on the myosin head as revealed by electron microscopy.

The location of the single cysteinyl residue of the alkali light chain on the myosin head was determined by electron microscopy. The cysteinyl residue of isolated alkali light chain 2 was biotinylated and the light chain was exchanged with that of heavy meromyosin in 4.7 M-NH4Cl. Avidin was attached to the biotin in the heavy meromyosin and the complex was rotary shadowed and observed in the electron microscope. The distance from the head-rod junction to the centre of avidin was 8(+/- 3) nm (mean value +/- standard deviation: n = 105).

Animals↗
PubMed1985

A streamlined method of subfragment one preparation from myosin.

A rapid procedure for isolating subfragment one (SF1) from myosin was found. SF1 can be isolated specifically from proteolytic digests of myosin in the presence of a millimolar concentration of magnesium chloride. Under such ionic conditions all of the rod portion and undigested myosin is selectively precipitated. A nucleotide trapping experiment indicated how important quick preparation of SF1 is for maintaining the active site structure. This method can also be utilized in the preparation of heavy meromyosin.

Adenosine Diphosphate↗
PubMed1985

Carbohydrate antigen defined by a monoclonal antibody raised against a gastric cancer xenograft.

A monoclonal antibody, ST-4-39, was obtained by using a human gastric cancer xenograft, St-4, as an immunogen. Immunization was achieved by transferring immunocompetent mouse spleen cells into a nude mouse bearing St-4. Hybridomas were produced with the spleen cells of the mouse after rejection of the tumor and screened for immunohistochemical reactivity with cancers and normal tissues on formalin-fixed paraffin sections. ST-4-39 immunohistochemically reacted with various cancers including gastric, colorectal and pancreatic cancers as well as some normal tissues. ST-4-39 and NS 19-9 differed in immunohistochemical reactivity, although they reacted with some cancers and a few normal tissues in common. PBS extracts of normal and cancer tissues were examined for antigen reactive with ST-4-39 by sandwich enzyme immunoassay. Extractable antigen was detected in adenocarcinomas of colon, stomach and lung, while it was detected only in salivary gland and trachea among normal tissues examined. Gel filtration analysis of the antigen indicated a molecular weight of greater than or equal to 1 X 10(6), and the antigenic determinant was suggested to be a carbohydrate chain with terminal sialic acid by studies using periodic acid, neuraminidase and pronase treatments. Furthermore, the ST-4-39 antigen affinity-purified from two gastric cancer strains was shown to contain multiple carbohydrate determinants including sialyl-Lewisa and sialyl-Lewisx, suggesting the antigen to be a mucin.

Animals↗
PubMed1985

[Evaluation of absolute non-curative resection in colorectal carcinoma].

A total of 241 cases with colorectal carcinoma were treated surgically at our hospital in the past 8 years. Of these, the non-curative resection was performed in 62 cases (absolute non-curative resection in 54 and relative non-curative resection in 8). In this study 54 cases (27 colonic carcinoma and 27 rectal carcinoma) with absolute non-curative resection were evaluated from the aspect of pathologic findings and survival rate according to the non-curative factors (liver metastasis, peritoneal dissemination, lymph node metastasis and distant metastasis). Seventeen cases (63.0%) had two or more non-curative factors in the cases with colonic carcinoma and 21 cases (77.8%) one factor, especially liver metastasis, in the cases with rectal carcinoma. In the cases with rectal carcinoma, the invasion to the adjacent structures was recognized in 48.1%. The survival rates were correlated with the extent of the non-curative factors in the cases with absolute non-curative resection. However, longer survival would be expected, if the primary tumor could be resected, even in absolute non-curative resection for colorectal carcinoma.

Adenocarcinoma↗