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Biomedical subjects

N Takai

Publications and source records attributed to N Takai.

121 records · Page 7Linked to original sources
PubMed1979

Separation of drugs by high-performance liquid chromatography with porous polymer resins.

The separation of cold drugs and neuroleptics by high-performance liquid chromatogarphy with the porous polymer resin DVB-MCL-O (or 11-30-0), which is a styrene-divinylbenzene-methyl methacrylate copolymer substituted with hydroxymethyl groups, was studied. This copolymer was compared with the commercial porous polymers Hitachi gel 3011, 3011-0 and 3030. A very small theoretical plate height was obtained by using DVB-MCL-O and methanol-ammonia solution (99:1) as the stationary and mobile phases, respectively. This combination was found to be the most suitable for the rapid separation of condensed aromatic ring compounds.

Analgesics↗
PubMed1975

Analysis of Dns-amino acids by liquid chromatography. I. Selection of optimum mobile phase composition for separation of Dns-amino acids on polyvinyl acetate gel.

The separation of a mixture of ten Dns-amino acids (Gns-Gly, -Ala, -Val, -Leu, -Pro, -Hypro, -Met, -Ser, -Asn and -Gln) was carried out by liquid chromatography by using macroreticular polyvinyl acetate gel as a packing material. Different mobile phase systems were investigated, based mainly on mixtures of n-hexane with ethanol, methanol, chloroform, acetone, methyl ethyl ketone, ethyl acetate, dioxane and tetrahydrofuran. The solvent composition was fixed so as to elute all of the components of the sample mixture in a practical period of 2 h. Satisfactory separation of the ten components was obtained with the n-hexane-ethanol (90:10) system. The presence of methanol as a modifier in the n-hexane was effective in reducing the elution time, but the separation was not as satisfactory. Chloroform or dioxane was useful only for the separation of Ser, Asn and Gln. Acetone, methyl ethyl ketone, ethyl acetate and tetrahydrofuran were not suitable for practical separations of Dns-amino acids.

Amino Acids↗
PubMedDate not supplied

Simultaneous determination of catecholamines, their basic metabolites and serotonin in urine by high-performance liquid chromatography using a mixed-mode column and an eight-channel electrochemical detector.

A high-performance liquid chromatographic method for simultaneous determination of free catecholamines, their basic metabolites and serotonin in human urine was developed. The compounds were separated on a precolumn of cation-exchange resin and a mixed-mode (C18/cation-exchange) column and determined by an eight-channel electrochemical detector. By this method, free norepinephrine (NE), epinephrine (E), dopamine (DA), normetanephrine (NMN), metanephrine (MN), 3-methoxy-tyramine (3-MT) and serotonin (5-HT) were determined in 40 min with inter-assay precision of 1.9, 3.2, 1.2, 1.6, 1.6, 5.5 and 3.2%, respectively. Detection limits were between 0.05 (E) and 0.3 (3-MT) pmol. The mean values of analytical recovery for NE, E, DA, NMN, MN, 3-MT, 5-HT were 99, 104, 104, 99, 102, 109 and 99%, respectively.

Buffers↗
PubMedDate not supplied

Atypical polypoid adenomyoma in a patient with hyperprolactinemia.

We report a case of an atypical polypoid adenomyoma in a patient with hyperprolactinemia. A 23-year-old Japanese woman was admitted complaining of atypical genital bleeding. Specula examination revealed a walnut-size polypoid mass extruding from the cervix. The patient was oligomenorrheac, and endocrine analysis showed hyperprolactinemia. Transvaginal ultrasonography and magnetic resonance imaging revealed an endometrial polypoid mass (4 x 3 x 3 cm) arising from the lower segment of the uterine corpus. The pathologic diagnosis of the tumor after polypectomy was atypical polypoid adenomyoma. It is suggested that ovarian dysfunction caused by hyperprolactinemia may be involved in the pathogenesis of atypical polypoid adenomyoma in the present case.

Adenomyoma↗
PubMedDate not supplied

Expression of receptor tyrosine kinase EphB4 and its ligand ephrin-B2 is associated with malignant potential in endometrial cancer.

The protein kinases includes many oncogenes and growth-factor receptors, as well as genes that are involved in cell cycle regulation. EphB4 receptors are a subfamily of receptor tyrosine kinases that are activated by ephrin-B2 ligands and are thought to play an important role in the development and oncogenesis of various tissues. However, very little experimental evidence exists to support this hypothesis. To elucidate the involvement of EphB4 and ephrin-B2 in endometrial carcinogenesis, we used fluorescent immunohistochemistry to analyze serial frozen sections of 20 endometrial carcinomas and 20 normal endometria for EphB4 and ephrin-B2 protein expression. We analyzed the relationship between the patient's characteristics and the percentages of EphB4- and ephrin-B2-stained cells. EphB4 expression was significantly associated with histological grade (p < 0.001) and certain clinical stages. Ephrin-B2 Expression was significantly associated with the presence of invasion to > 1/2 myometrium (p = 0.002). Our results demonstrate that increased EphB4 and ephrin-B2 expression may reflect or induce in endometrial carcinomas increased potential for growth and tumorigenicity. Furthermore, these results suggest that EphB4 receptor kinase may modulate the biological behavior of endometrial carcinomas through autocrine and/or paracrine activation, which is caused by ephrin-B2 ligands that are expressed in the same or neighbouring cells by immunohistochemistry.

Adenocarcinoma↗