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T Asakura

Publications and source records attributed to T Asakura.

At least 37 records · Page 2Linked to original sources
PubMed2001

Glutathione-S-transferase-pi expression regulates sensitivity to glutathione-doxorubicin conjugate.

We have reported that glutathione-doxorubicin conjugate (GSH-DXR) exhibited potent cytotoxicity against tumor cells and inhibited glutathione-S-transferase (GST) enzyme activity. In order to determine whether or not the expression of GST-pi lowered the cytotoxicity of GSH-DXR, cytocidal activity of the conjugate was examined using tumor cells in which the level of GST-pi expression was regulated by transfecting GST-pi cDNA in the correct or reverse direction and comparing with that of DXR. Enhancement of GST-pi expression by transfecting GST-pi sense cDNA into human hepatoblastoma HepG2 cells in which GST-pi expression was extremely low caused an increase in GST activity from 0.26 to 55.0 nmol/mg/min and a marked reduction in transfectant sensitivity to GSH-DXR to 1/120 (0.15-18 nM IC50) although the sensitivity to DXR was slightly decreased to 1/2.6 (380-990 nM IC50). By contrast, a high GST-pi-expressing human colon cancer cell line, HT29, showed a decrease in GST enzyme activity from 72.0 to 45.9 nmol/mg/min after transfecting GST-pi antisense cDNA and a marked improvement in transfectant sensitivity to GSH-DXR was observed (28-2.9 nM IC50) compared with the transfectant sensitivity to DXR (1020-320 nM IC50). Additionally, the expression of GST-pi in HepG2 cells caused a decrease in GSH-DXR-induced activation of caspase-3, which was an apoptotic marker, whereas the suppression of GST-pi in HT29 cells showed an increase in caspase-3 activation. These results suggested that the cytocidal efficacy of GSH-DXR, but not that of DXR, was controlled by the level of GST-pi expression in the cells.

Antineoplastic Agents↗
PubMed2001

Adhesion of N-methacryloyl-omega-amino acid primers to collagen analyzed by 13C NMR.

Previously, we reported that the strength of the interaction between N-methacryloyl-omega-amino acid (NMomegaA) primers and dentinal collagen exhibited a strong correlation with the bond strength of the resin to etched dentin. To determine the pertinent functional groups of the amino acid residues in the dentinal collagen, to which the amide and/or the carboxylic acid groups of the NMomegaAs are adsorbed, we used 13C NMR techniques--primarily through the observation of spin-lattice relaxation times, Ti--to investigate the adsorption characteristics resulting from the interaction of NMomegaAs with a model oligopeptide for collagen, (PPG)5. The addition of NMomegaAs to a collagenous solution resulted in a decrease in the T1 values of the carbonyl carbons attributed to the carboxylic acid of the C-terminal Gly and to the third amide of the N-terminal Pro residues in the (PPG)5 molecule, thus reflecting the formation of hydrogen-bonded interactions.

Adhesiveness↗
PubMed2001

Occurrence of coring in insulin vials and possibility of rubber piece contamination by self-injection.

Coring is reported to occur because rubber pieces are shaved off from a rubber stopper when a needle is inserted into the rubber stopper of transfusion liquid formulation. We verified whether coring really occurs in insulin vials of self-injecting patients. We collected insulin cartridges from 30 hospitalized patients and used the primary injection (trial injection), the secondary injection and the cartridge remaining preparation as samples. We observed the rubber pieces using a microscope and measured the shape, number of pieces. The occurrence rate of coring was 73% for the primary injection, 47% for the secondary injection and 97% for the cartridge remaining preparation. The rubber pieces in the primary injection and the secondary injection which went through the needle are mostly in aggregate shape and the rubber pieces in the cartridge remaining preparation which did not go through the needle are mostly in needle-like shape. A number of small rubber pieces are found in both the primary injection and the secondary injection, indicating a high possibility that rubber pieces may be injected under subcutaneous tissue. The coring is considered to occur because needles are repeatedly inserted and rotated at the same spot. It is required to improve the structure to mount a needle to the pen-type injector in future. Coring is a very serious problem from the medical and pharmaceutical points of view. Further study should be made on the implication to latex allergy and lipodystrophy.

Adult↗
PubMed2001

[Research regarding proper use of insulin in diabetes patients].

In treating diabetes over the long term, controlling the daily life is very important and cannot be neglected. In particular, the patient's awareness and practice of their treatment had a great influence on their treatment. However, there has been very little scientific research done with regard to how much the patient understands the instructions about taking their medicine and whether they actually follow those instructions. Due to these facts, in this research we studied what guidance should be given when taking medicines made from insulin after analyzing the results of an investigation taken from the patients' point of view. In carrying out a study on the education and the degree of understanding of insulin self-injections, it became clear that older patients' ability to understand diminished, and the patients forgot to shake the NPH insulin immediately before injection. And, in more than a few cases, even when the NPH insulin was shaken, injections took place after some time had passed. After studying the amount of time that elapses once sedimentation begins, it was found that the insulin is effective if it is injected within 2.5 minutes of being shaken. Next, a study was carried out on the problems of maintaining the quality of life (QOL) of patient while continuing the treatment for diabetes. As a result, it became clear that the patient's lifestyle, including psychological factors, exerts a large influence on continuing the correct treatment. In particular, in cases of insulin injections when the patient eats out, younger patients tend to be more susceptible to psychological influence. This suggests that there is a need to work on guidance for the patient in taking their medicine. And, such guidance should strictly adhere to information regarding the patient's lifestyle, which comes through good communication with the patient. On the other side, the coring of the insulin vial of insulin was examined in terms of medicine production technology. As a result, the occurrence of coring is seen irrespective of the type of needle and the temperature of the rubber vial stopper, and the fact that rubber fragments were found in the injection solution, suggesting the possibility of subcutaneous rubber fragments through injection. Further examination of the problems of continued long-term treatment of injected medicines may be necessary in the future. Due to the necessity of self-control of patients and the long time span of treatment that is involved, maintaining the QOL of the patient is important in diabetes treatment. We feel that it is important to give guidance about treatment, which fits the patients' lifestyles.

Diabetes Mellitus↗
PubMed2001

A case of hemosuccus pancreaticus associated with hereditary pancreatitis.

We report a 25-year-old male with hemosuccus pancreaticus associated with hereditary pancreatitis. He was originally diagnosed as having familial chronic pancreatitis at the age of 12, because his brother was also diagnosed as having pancreatitis. No history of pancreatitis was found in their parents. The patient was admitted because of a growing pancreatic pseudocyst. While he had undergone conservative treatment for the pseudocyst, computed tomography incidentally revealed a pancreatic pseudoaneurysm. Endoscopic examination revealed spontaneous bleeding from the major papilla. Interventional embolization was successfully performed. An R122H mutation in the cationic trypsinogen gene was identified in this patient, his brother, and his mother, indicating that they have hereditary pancreatitis. To our knowledge, this is the first report of hemosuccus pancreaticus associated with hereditary pancreatitis. Mutational screening is useful for the diagnosis of hereditary pancreatitis, especially in patients whose diagnosis is inconclusive based on the traditional clinical criteria.

Adult↗
PubMed2000

Calpain inhibitor inhibits secretory granule maturation and secretion of GH.

Clathrin- and AP-1-coated buds are present on immature secretory granules of endocrine cells that mature into clathrin-uncoated granules. The mechanism of clathrin and adaptor protein uncoating has remained obscure. Benzyloxycarbonyl-L-leucyl-L-leucinal (ZLLal), a calpain inhibitor, reduced growth hormone (GH) secretion with intracellular accumulation, in a GH-secreting rat pituitary tumor cell. Pulse and chase demonstrated that ZLLal retarded the turnover of clathrin (Clt.H) and adaptins. ZLLal-treatment co-immunoprecipitated the increased amounts of GH with Clt.H and adaptins compared to control cells, suggesting the intracellular accumulation of immature secretory granules. Clt.H and adaptins were limited-proteolyzed by m-calpain in vitro, indicating that calpain may be involved partly in the maturation of secretory granules in endocrine cells via the process of clathrin uncoating.

Adaptor Protein Complex alpha Subunits↗
PubMed2000

Characterization of Brachyury-downstream notochord genes in the Ciona intestinalis embryo.

The notochord has two major roles during chordate embryogenesis, as a source of inductive signals for the patterning of neural tube and paraxial mesoderm and as a supportive organ of the larval tail. Despite the recent identification of mutations that affect the notochord development in vertebrate embryos, little is known about genes that are expressed in the differentiating notochord itself. In the urochordate ascidian Ciona intestinalis, Brachyury (Ci-Bra) plays a key role in notochord differentiation. In a previous study, we isolated cDNA clones for nearly 40 potential Ci-Bra target genes that are expressed in notochord cells (H. Takahashi et al., 1999, Genes Dev. 13, 1519-1523). Here we characterized 20 of them by determining the complete nucleotide sequences of the cDNAs. These genes encode a broad spectrum of divergent proteins associated with notochord formation and function. Two genes encode ascidian homologs of the Drosophila Prickle LIM domain proteins and another encodes the ERM protein, all 3 of which appear to be involved in the control of cytoskeletal architecture. In addition, genes for netrin, leprecan, cdc45, ATP:citrate lyase, ATP sulfurylase/APS kinase, protein tyrosine phosphatase, beta4-galactosyltransferase, fibrinogen-like protein, divergent tropomyosin-like proteins, and Drosophila Pellino-like protein were identified. The observation of the netrin gene expression in the notochord may provide the first molecular evidence that the ascidian notochord is a source of signals as in vertebrates. In addition, the present information should be used to identify nonchordate deuterostome tissues homologous to the notochord as well as genes which are expressed in the notochord cells of vertebrate embryos.

Amino Acid Sequence↗
PubMed2000

Solid-state NMR determination of the secondary structure of Samia cynthia ricini silk.

Silks are fibrous proteins that form heterogeneous, semi-crystalline solids. Silk proteins have a variety of physical properties reflecting their range of functions. Spider dragline silk, for example, has high tensile strength and elasticity, whereas other silks are better suited to making housing, egg sacs or the capture spiral of spiders' webs. The differing physical properties arise from variation in the protein's primary and secondary structure, and their packing in the solid phase. The high mechanical performance of spider dragline silk, for example, is probably due to a beta-sheet conformation of poly-alanine domains, embedded as small crystallites within the fibre. Only limited structural information can be obtained from diffraction of silks, so further characterization requires spectroscopic studies such as NMR. However, the classical approach to NMR structure determination fails because the high molecular weight, repetitive primary structure and structural heterogeneity of solid silk means that signals from individual amino-acid residues cannot be resolved. Here we adapt a recently developed solid-state NMR technique to determine torsion angle pairs (phi, psi) in the protein backbone, and we study the distribution of conformations in silk from the Eri silkworm, Samia cynthia ricini. Although the most probable conformation in native fibres is an anti-parallel beta-sheet, film produced from liquid directly extracted from the silk glands appears to be primarily alpha-helical.

Animals↗
PubMed2000

Cyclin E overexpression in transitional cell carcinoma of the bladder.

We attempted to clarify the relationship between cyclin E to p27(Kip1), Ki-67 and clinicopathologic features in transitional cell bladder carcinoma. Immunohistochemical staining of archival tissue specimens of transitional cell bladder carcinoma obtained from 94 patients was performed by the labeled streptavidin-biotin-peroxidase method. Overexpression of cyclin E protein was observed in 38 of the 94 (40.4%) specimens, and was positively correlated with histological grade, Ki-67 LI and p27(Kip1) labeling index (LI). These data suggest that cyclin E may be associated with aggressive tumor growth, and may have a relationship with p27(Kip1) for the regulation of cell cycle progression in transitional cell bladder carcinoma.

Carcinoma, Transitional Cell↗
PubMed2000

An advantage for use of isotope labeling and NMR chemical shifts to analyze the structure of four homologous IgG-binding domains of staphylococcal protein A.

Because of the complexity arising from the large molecular size and the amino acid sequence homologies of IgG-binding domains of Staphylococcal Protein A (SpA), we have introduced, a combination of stable isotope labeling and both qualitative and quantitative investigations of the structural dependence of the NMR chemical shifts for its structure analysis. In order to enable selective isotope labeling with high efficiency, a mutated low molecular weight Protein A (LPA; MWt = 27 kDa) which consists of E, D, A, B and 13 residues of the C-domain was used in this study. Amide proton chemical shifts, measured using uniformly 15N-labeled LPA and LPA labeled selectively with 15N-alanine, show that the turn between helices 1 and 2, and its tertiary interactions with helix 3, are very similar in all domains. This contradicts previous results obtained using independent structure calculations on isolated domains. The close similarity in NH and 15N chemical shifts of alanine residues in the interdomain linker suggests that the linker maintains a similar structure both in isolated domains and in the intact protein. We show that the high-field shifted methyl signal of Ala 48 is affected by the ring-current effect arising from Phe 30, and has a very similar helical environment in all four domains. Thus, helix 3 is present in all domains, as we previously reported [Kikuchi et al., J Biochem Biophys Method, 1999:38:203-208], even though it is not observed in the crystal structure [Deisenhofer J. Biochemistry 1981;20:2361-2370].

Alanine↗
PubMed2000

Enhancement of hemoglobin and F-cell production by targeting growth inhibition and differentiation of K562 cells with ribonucleotide reductase inhibitors (didox and trimidox) in combination with streptozotocin.

Upon appropriate drug treatment, the human erythroleukemic K562 cells have been shown to produce hemoglobin and F-cells. Fetal hemoglobin (Hb F) inhibits the polymerization events of sickle hemoglobin (Hb S), thereby ameliorating the clinical symptoms of sickle cell disease. Ribonucleotide reductase inhibitors (RRIs) have been shown to inhibit the growth of myeloid leukemia cells leading to the production of Hb F upon differentiation. Of the RRIs currently in use, hydroxyurea is the most effective agent for Hb F induction. We have examined the capacity of two novel RRIs, didox (DI) and trimidox (TRI), in combination with streptozotocin (STZ), to induce hemoglobin and F-cell production. The K562 cells were cultured with different concentrations of didox-STZ or trimidox-STZ at a fixed molar ratio of 3:1 and 1:5 for 96 hr, respectively. At pre-determined time intervals, aliquots of cells were obtained and total hemoglobin (benzidine positive) levels, number of F-cells, and Hb F were determined by the differential staining technique, fetal hemoglobin assay kit, and fluorescence cytometry respectively. The effect of combined drug treatment on the growth of K562 cells was examined by isobologram analysis. Our results indicate that a synergistic growth-inhibitory differentiation effect occurred when didox or trimidox was used in combination with STZ on K562 cells. There was an increase in the number of both benzidine-positive normoblasts and F-cells, accompanied by morphologic appearances typical of erythroid maturation. On day 4, the number of benzidine-positive cells showed a 6-9-fold increase and the number of F-cells was between 2.5- and 5.7-fold higher than the respective controls. Based upon these results, treatment with a ribonucleotide reductase inhibitor, such as didox or trimidox, in combination with STZ, might offer an additional promising option in sickle cell disease therapy.

Antineoplastic Agents↗
PubMed2000

Biosynthesis of L-alanine, a major amino acid of fibroin in Samia cynthia ricini.

The derivation of alanine in fibroin was investigated using NMR and selective isotopic labelling. 2H2O infused orally into 5th instar larvae was incorporated into the proton of the methyl group of alanine in fibroin. Proton exchange among alanine, glycine and serine was also found. Incorporation of 13C from [2-(13)C]acetate into alanine C2 and C3 and glycine C2 in fibroin, and also C4 of free glutamine plus glutamate was observed in vivo. Hemolymph contained a peak for C4 of glutamate plus glutamine, and an alanine C3 peak appeared transiently. Thus, it is suggested that the C-skeleton of alanine formed was derived from L-malate via the TCA-cycle, and that this alanine is utilized in part for fibroin synthesis. Spectra of the hemolymph extract of larvae infused orally with [15N2]urea showed no 15N-compounds, whereas those of larvae injected subcutaneously showed only one peak of urea, whose intensity decreased with time, as shown in the in vivo spectra of a living larva infused with [15N2]urea. The solution NMR spectrum of fibroin showed no 15N-labelled compounds. Temporal changes in the peak intensities of six compounds in the spectra of a living larva infused with [15N]ammonium demonstrated a process in which 15N was incorporated into fibroin containing 15N-alanine through the amide group of glutamine and the amino group of glutamate. Thus, alanine biosynthesis from the TCA-cycle originates mainly from water, L-malate and ammonium. The fact that no 15N-urea was detected in the hemolymph extract of larvae infused with [15N]ammonium suggests that 15N-urea found in the above in vivo spectra may be that accumulated in the hindgut. Thus, excess ammonium in the body causes the production of urea by the urea-cycle. In Samia larvae, urea was not reutilized but excreted. The metabolic relationships between the assimilation of ammonium and the function of the urea-cycle are discussed.

Acetates↗