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Biomedical subjects

H Tokumoto

Publications and source records attributed to H Tokumoto.

25 records · Page 2Linked to original sources
PubMed1987

Interleukin 4 (IgG1 induction factor): a multifunctional lymphokine acting also on T cells.

A cDNA encoding the murine interleukin 4 (IL4) (IgG1 induction factor/B cell-stimulating factor no. 1) was recently cloned (Noma et al., Nature 1986.319: 640; Lee et al., Proc. Natl. Acad. Sci. USA 1986. 83: 2061). In this report we tested recombinant IL 4 in various T cell assays. It was found that IL 4 activated the murine T cell line CTLL to increased DNA synthesis but not to growth. It also activated normal concanavalin A (Con A)-stimulated T cells both to increased DNA synthesis and to growth. These T cell growth factor-like activities were not inhibitable by anti-IL 2 receptor antibodies. Evidence is given that both Lyt-2+ and L3T4+ T cells responded to IL 4. Finally, IL 4 acted synergistically with phytohemagglutinin or Con A on normal T lymphocytes as well as on thymocytes. These data, as well as those of others, imply that lymphokines have a broader range of activity than previously anticipated.

Animals↗
PubMed1986

Specificity of prostaglandin D2 binding to synaptic membrane fraction of rat brain.

The structural requirement of the prostaglandin D2 molecule for binding to the synaptic membrane fraction of rat brain was extensively studied by using various prostaglandin D derivatives. Most strict specificity was found in the structures of the cyclo-pentane ring and the double bond in 13,14-position. The addition and deprivation of the double bond in alpha- and omega-chain, except on 13,14-position, moderately affected the binding. The modification in the carboxyl terminus and omega-chain terminus did not seriously influence the binding. BW 245C and 9-beta-prostaglandin D2, potent agonists for the prostaglandin D2 receptor in the platelet membrane, were almost ineffective. [3H]prostaglandin D2 binding was not affected by the addition of various neuroactive substances to the binding assay mixture. Further, prostaglandin D2 did not affect the known neurotransmitter receptor bindings in the rat brain.

Animals↗
PubMed1985

Specific bindings of prostaglandin D2, E2 and F2 alpha in postmortem human brain.

Binding activities specific for each of [3H]prostaglandin (PG) D2, E2 and F2 alpha were detected in the P2 fraction of the human brain homogenates. The bindings were time-dependent, saturable and of high affinity; Kd values were 30 nM for all the PG bindings. Regional distribution of these binding activities was determined by measuring specific bindings with 10 nM [3H]PG-D2, [3H]PG-E2 and [3H]PG-F2 alpha in the P2 fractions from 17 brain regions. The PG-D2 binding activity was high in the hypothalamus, amygdala and hippocampus followed by cerebellar nuclei, thalamus, nucleus accumbens and cerebral cortex. The PG-E2 binding sites were similarly concentrated in the hypothalamus and the limbic system, but, unlike the PG-D2 binding, no significant binding of [3H]PG-E2 was observed in cerebellar nuclei, cerebellar cortex and putamen. Compared with these two PG bindings, PG-F2 alpha binding activity was low in many areas, but significant binding was detected in the amygdala, cingulate cortex, cerebellar medulla, hippocampus, nucleus accumbens, midbrain and hypothalamus. These results suggest the presence and specific distribution of three distinct types of PG binding activities, i.e. specific binding of PG-D2, PG-E2 and PG-F2 alpha, in the human brain.

Brain↗
PubMed1983

Localization of prostaglandin D2 binding protein and NADP-linked 15-hydroxyprostaglandin D2 dehydrogenase in the Purkinje cells of miniature pig cerebellum.

High-affinity binding sites specific for prostaglandin D2 were visualized by the autoradiographical technique assisted by computerized image processing and color coding. In the cerebellum of miniature pig, high density of the binding was observed in the cortex, mainly in the Purkinje cell layer. Immunohistochemical studies on the cellular localization of NADP-linked 15-hydroxyprostaglandin D2 dehydrogenase were performed with the same cerebellum and revealed the presence of this enzyme also in the Purkinje cells. These findings imply that prostaglandin D2 binds to the Purkinje cells and, after its action, is degraded in situ by the specific degradative enzyme.

Animals↗
PubMed1982

An NADP-linked 15-hydroxyprostaglandin dehydrogenase specific for prostaglandin D2 from swine brain.

NADP-linked prostaglandin D2 dehydrogenase was purified from swine brain to apparent homogeneity, as judged by polyacrylamide gel electrophoresis and ultracentrifugation. Using the purified enzyme free of the 15-ketoprostaglandin delta 13-reductase activity, the reaction product was identified as 15-ketoprostaglandin D2 by mass spectrometry and spectrophotometry. The purified enzyme was a monomeric protein of a molecular weight of 29,000 +/- 1,000. It had a relative abundance of hydrophobic amino acids such as leucine, alanine, and valine. The optimal pH of the enzyme reaction was 9.5. The purified enzyme exhibited high substrate specificity for prostaglandin D2 and strict specificity for NADP. The Vmax and the Km values for prostaglandin D2 and NADP were 22.0 nmol/min/mg of protein at 24 degrees C and 52 microM and 0.4 microM, respectively. The Vmax and the Km values for various types of prostaglandins for 8.6 nmol/min/mg of protein at 24 degrees C and 250 microM for D1; 8.0 and 350 for E2; 3.4 and 400 for F2 alpha; and 9.6 and 540 for I2. Prostaglandin A2, B2, and E1 could not serve as substrate. Although other NADP-linked 15-hydroxyprostaglandin dehydrogenases were reported to contain the NADPH-linked prostaglandin E 9-ketoreductase activity, this enzyme was free of the reductase activity. These results indicate that this dehydrogenase is responsible for the specific inactivation of prostaglandin D2 in the brain.

Amino Acids↗