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Biomedical subjects

N Yoshida

Publications and source records attributed to N Yoshida.

At least 55 records · Page 3Linked to original sources
PubMed2002

Bacterium-based heavy metal biosorbents: enhanced uptake of cadmium by E. coli expressing a metallothionein fused to beta-galactosidase.

We investigated the potential utility of a recombinant E. coli that expresses the human metallothionein II gene as a fusion protein with beta-galactosidase as a heavy metal biosorbent. E. coli cells expressing the metallothionein fusion demonstrated enhanced binding of Cd2+ compared to cells that lack the metallothionein. It was shown that the metallothionein fusion was capable of efficiently removing Cd2+ from solutions. Approximately 40% of the Cd2+ accumulated by the recombinant cells free in suspension was associated with the outer cell membrane, and 60% of that was present in the cytoplasm.

Biodegradation, Environmental↗
PubMed2002

Changed activation of HIV-1 LTR in monocytoid cells by mycobacteria with temporal progression of infection.

Coincubation of monocytoid cell line U937 cells cotransfected with HIV-1 LTR CAT plasmid and Tat expression plasmid, with Mycobacterium smegmatis, M. avium, M. bovis BCG and M. tuberculosis enhanced chloramphenicol acetyltransferase (CAT) production, indicating that these mycobacteria could activate the LTR in this cell line. The amount of CAT in the cells coincubated with M. smegmatis was higher than that infected with the other mycobacteria after 12, 24 and 48 hour time periods. However, the amount of CAT production in the cells cocultured with M. tuberculosis was higher than those coincubated with the other mycobacteria at 72 hours. These findings indicated that avirulent mycobacteria such as M. smegmatis may activate HIV replication at an early time and its effects are gradually decreased, while the effect of virulent M. tuberculosis increased gradually, and lasted for a long time resulting in an acceleration of HIV disease in patients.

Chloramphenicol O-Acetyltransferase↗
PubMed2001

Central antiemetic effects of AS-8112, a dopamine D2, D3, and 5-HT(3) receptor antagonist, in ferrets.

The involvement of a central mechanism in the antiemetic effect of AS-8112 ((R)-5-bromo-N-(1-ethyl-4-methylhexahydro-1H-1,4-diazepin-6-yl)-2-methoxy-6-methylamino-3-pyridinecarboxamide x 2 fumarate), a novel and potent dopamine D2, D3, and 5-HT(3) receptor antagonist, was investigated in ferrets. Intracerebroventricularly administered AS-8112 dose dependently inhibited R(+)-7-OH-DPAT (R(+)-7-hydroxy-2-(N,N-di-n-propylamino) tetraline)-induced emesis (ID(50); 0.11 microg/kg, i.c.v.). In addition, AS-8112 (10 microg/kg, i.c.v.) significantly inhibited emesis induced by cisplatin. Ondansetron (10 microg/kg, i.c.v.) also inhibited cisplatin-induced emesis, but did not inhibit R(+)-7-OH-DPAT-induced emesis. S(-)-eticlopride (10 microg/kg, i.c.v.) did not inhibit emesis induced by cisplatin. However, racemic CP-99,994 ((+/-)-(2S, 3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine) (10 microg/kg, i.c.v.) inhibited both cisplatin- and R(+)-7-OH-DPAT-induced emesis. These results suggest that the antiemetic effects of AS-8112 are centrally mediated via dopamine D3 and 5-HT(3) receptors in ferrets.

Animals↗
PubMed2001

Daphnicyclidins A-H, novel hexa- or pentacyclic alkaloids from two species of Daphniphyllum.

Eight highly modified Daphniphyllum alkaloids with unprecedented fused hexa- or pentacyclic skeletons, daphnicyclidins A-H (1-8), have been isolated from the stems of Daphniphyllum humile and D.teijsmanni, and their structures were elucidated on the basis of spectroscopic data and chemical means. The stereochemistry was elucidated by combination of NOESY correlations, X-ray crystallographic data, and CD analyses.

Alkaloids↗
PubMed2001

Development of tunable picosecond dye laser for multiphoton ionization of dioxin precursors in supersonic jet/time-of-flight mass spectrometry.

A distributed-feedback dye laser has been developed for achieving the efficient multiphoton ionization of chlorobenzene and dichlorobenzene, that is, precursor molecules of dioxins. This tunable picosecond laser with a narrow spectral line width, that is, a nearly transform-limited pulse, provides a more efficient ionization than the nanosecond laser, which is currently in use in supersonic jet spectrometry. The advantage of picosecond over nanosecond and femtosecond lasers is also discussed on the basis of the theoretical model reported in a previous paper.

Air Pollutants↗
PubMed2001

Improvement of a mediator-type biochemical oxygen demand sensor for on-site measurement.

We characterized a mediator-type biochemical oxygen demand (BOD) sensor with a three-electrode system using potassium ferricyanide (FC) and Pseudomonas fluorescens in our previous study. In the present study, we have utilized the advantages of a mediator-type biosensor, which does not require air-supply equipment for on-site measurements, and made a fully disposable sensor tip for a portable device. The tip consists of a two-electrode system with P. fluorescens immobilized on a cellulose acetate membrane and is packaged in polyester film to prevent it from drying out. By aeration with a 0.1 M NaCl solution of P. fluorescens (after growth), the sensor responses as well as their reproducibility and stability have been successfully improved. The responses increased more than seven times, and the calibration curve from 15 to 260 mg l(-1) also remained linear although the response decreased approximately half the original after at least 35 days in storage. The reproducibility of the sensor responses improved to 12.7% (average of relative standard deviations (RSDs)) in the calibration curve obtained by using the Organization for Economic Cooperation and Development synthetic sewage. Examination of real samples from three different sources showed that the BOD as determined by the sensor correlates well with the conventional 5-day BOD method (r(2)=0.982, 0.823, and 0.809). Consequently, the aeration process makes it possible to realize rapid, and in situ measurements without the long conditioning process that is generally required to activate the microorganisms immobilized on bio-films before use. Finally, we have designed a portable device that utilizes our disposable sensor tip.

Biosensing Techniques↗
PubMed2001

Clathrin box in G protein-coupled receptor kinase 2.

beta(1)-Adrenergic receptor (beta(1)AR) shows the resistance to agonist-induced internalization. However, beta(1)AR can internalize as G protein-coupled receptor kinase 2 (GRK2) is fused to its carboxyl terminus. Internalization of the beta(1)AR and GRK2 fusion protein (beta(1)AR/GRK2) is dependent on dynamin but independent of beta-arrestin and phosphorylation. The beta(1)AR/GRK2 fusion protein internalizes via clathrin-coated pits and is found to co-localize with the endosome that contains transferrin. The fusion proteins consisting of beta(1)AR and various portions of GRK2 reveal that the residues 498-502 in the carboxyl-terminal domain of GRK2 are critical to promote internalization of the fusion proteins. This domain contains a consensus sequence of a clathrin-binding motif defined as a clathrin box. In vitro binding assays show that the residues 498-502 of GRK2 bind the amino-terminal domain of clathrin heavy chain to almost the same extent as beta-arrestin1. The mutation of the clathrin box in the carboxyl-terminal domain of GRK2 results in the loss of the ability to promote internalization of the fusion protein. GRK2 activity increases and then decreases as the concentration of clathrin heavy chain increases. Taken together, these results imply that GRK2 contains a functional clathrin box and directly interacts with clathrin to modulate its function.

Amino Acid Sequence↗
PubMed2001

Requirement of phospholipase Cdelta4 for the zona pellucida-induced acrosome reaction.

Several phospholipase C (PLC) isoforms have been found in male and female mammalian gametes, and splicing isoforms of PLCdelta4 are predominantly expressed in testis. Here we report that male mice in which the PLCdelta4 gene had been disrupted either produced few small litters or were sterile. In vitro fertilization studies showed that insemination with PLCdelta4-/- sperm resulted in significantly fewer eggs becoming activated and that the calcium transients associated with fertilization were absent or delayed. PLCdelta4-/- sperm were unable to initiate the acrosome reaction, an exocytotic event required for fertilization and induced by interaction with the egg coat, the zona pellucida. These data demonstrate that PLCdelta4 functions in the acrosome reaction that is induced by the zona pellucida during mammalian fertilization.

Acrosome↗
PubMed2001

Chrysotile asbestos fibers mediate transformation of Escherichia coli by exogenous plasmid DNA.

The ability of chrysotile asbestos fibers to introduce the exogenous plasmid pUC18 into Escherichia coli JM109 cells was tested. Cells were transformed with pUC18 DNA although the frequency of transformation was quite low: 759+/-301 transformants were obtained per microgram of pUC18. Plasmids were purified from E. coli which had been transformed by mediation with chrysotile asbestos. Following this, the plasmids were confirmed to be pUC18 by Southern hybridization. This asbestos-mediated transformation was optimal within 5 min when 10 mg ml(-1) of asbestos was used. Plasmids up to 7.69 kb were introduced by this method.

Asbestos, Serpentine↗
PubMed2001

Interleukin (IL)-4/IL-9 and exogenous IL-16 induce IL-16 production by BEAS-2B cells, a bronchial epithelial cell line.

Previous studies have suggested that bronchial epithelial cells may perpetuate airway inflammation. We have reported that the bronchial epithelial cell line BEAS-2B can produce interleukin (IL)-16, a potent chemoattractant for CD4+ T cells. IL-16 is thought to regulate airway inflammation in asthmatics. Recent studies showed that IL-4 induces inflammatory cytokines in bronchial epithelial cells and that IL-9 is a candidate gene for development of asthma. The present study demonstrated that BEAS-2B cells produced specifically IL-16 by synergistic effects of IL-4 + IL-16, or IL-9 + IL-16, and that the synthesized IL-16 induced migration of CD4+ T cells. This study is a first report indicating that IL-16 production may be maintained by an autocrine machinery by epithelial cell-derived IL-16 with IL-4 and IL-9 in asthma.

Bronchi↗
PubMed2001

The inducible nitric oxide synthase inhibitor ONO-1714 blunts dextran sulfate sodium colitis in mice.

In mice with acute dextran sulfate sodium colitis, we examined the effect of inducible nitric oxide synthase inhibition by (1S,5S,6R,7R)-7chloro-3-amino-5methyl-2-azabicyclo[4.1.0]heptane hydrochloride (ONO-1714) on colonic biochemistry, injury, and inflammation. Colonic luminal nitrate and nitrite were measured by the Griess reaction; inducible nitric oxide synthase messenger RNA expression by reverse transcription-polymerase chain reaction; and nitrotyrosine by immunohistochemistry. Mice with colitis showed increases in nitrate and nitrite, inducible nitric oxide synthase messenger RNA, and numbers of cells staining for nitrotyrosine. Colonic inflammation was severe. ONO-1714 inhibited increases in nitrate and nitrite and numbers of nitrotyrosine-positive cells; injury and inflammation also were reduced. Dextran sulfate sodium-induced increases in thiobarbituric acid-reactive substances, a lipid peroxidation marker, were blunted by ONO-1714, which also inhibited increases in mucosal inflammatory cytokines. Nitric oxide produced by inducible nitric oxide synthase may contribute to colonic inflammation by nitrosation, oxidative damage, and enhanced inflammatory cytokines.

Amidines↗
PubMed2001

Microenvironment of endosomal aqueous phase investigated by the mobility of microparticles using fluorescence correlation spectroscopy.

Temporal observation of the dynamic behavior of molecules in cells gives information about the physiological environment at the region of interest. Here we report the direct measurement of the mobility of rhodamine-labeled microparticles (14 and 35 nm in diameter) ingested in endosomes of cultured bovine aortic endothelial cells using fluorescence correlation spectroscopy (FCS). The fluctuation of fluorescent signals from microparticles were measured by FCS. Obtained autocorrelation functions (FAFs) were analyzed by the 2-D multicomponent model according to an evaluation procedure we newly developed. It was found that microparticles moved freely in endosomes with average diffusion coefficients of 4.3 x 10(-8) and 2.7 x 10(-8) cm2 s(-1) for 14 and 35 nm, which were 45% slower than in water. This result implies that the endosomal aqueous phase is homogeneous with the viscosity about 2.2 times of water. Our study also proposes the new use of FCS for investigation of the internal space of organelles.

Animals↗
PubMed2001

Defect in SHAP-hyaluronan complex causes severe female infertility. A study by inactivation of the bikunin gene in mice.

Hyaluronan (HA) associates with proteins and proteoglycans to form the extracellular HA-rich matrices that significantly affect cellular behaviors. So far, only the heavy chains of the plasma inter-alpha-trypsin inhibitor (ITI) family, designated as SHAPs (serum-derived hyaluronan-associated proteins), have been shown to bind covalently to HA. The physiological significance of such a unique covalent complex has been unknown but is of great interest, because HA and the ITI family are abundant in tissues and in plasma, respectively, and the SHAP-HA complex is formed wherever HA meets plasma. We abolished the formation of the SHAP-HA complex in mice by targeting the gene of bikunin, the light chain of the ITI family members, which is essential for their biosynthesis. As a consequence, the cumulus oophorus, an investing structure unique to the oocyte of higher mammals, had a defect in forming the extracellular HA-rich matrix during expansion. The ovulated oocytes were completely devoid of matrix and were unfertilized, leading to severe female infertility. Intraperitoneal administration of ITI, accompanied by the formation of the SHAP-HA complex, fully rescued the defects. We conclude that the SHAP-HA complex is a major component of the HA-rich matrix of the cumulus oophorus and is essential for fertilization in vivo.

Alpha-Globulins↗
PubMed2001

Requirement of cyclin B2, but not cyclin B1, for bipolar spindle formation in frog (Rana japonica) oocytes.

Cyclin B, the regulatory subunit of maturation-promoting factor (MPF), comprises several subtypes that are presumed to confer different functions on MPF although no direct evidence has been provided to date. To clarify the difference in the roles of cyclins B1 and B2, we used frog (Rana japonica) oocytes in which MPF is formed only after progesterone stimulation because it is possible to produce oocytes containing either cyclin B1-MPF or cyclin B2-MPF by antisense RNA-mediated translational inhibition of each mRNA. Using this advantage, we investigated the functions of cyclins B1 and B2 and obtained the following results: (a) oocytes synthesizing cyclin B2-MPF underwent meiosis I and II with formation of a bipolar spindle at each metaphase; (b) oocytes synthesizing cyclin B1-MPF formed a monopolar spindle at metaphase I and extruded an abnormal polar body; and (c) both oocytes underwent germinal vesicle breakdown (GVBD) and chromosome condensation. Immunocytochemical observations also revealed continuous localization of cyclin B2 on the spindle during meiosis. These results provide evidence of the requirement of cyclin B2, but not cyclin B1, for organizing the bipolar spindle, though either cyclin B1 or B2 is redundant for inducing GVBD and chromosome condensation.

Animals↗