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Biomedical subjects

T Yashiki

Publications and source records attributed to T Yashiki.

At least 37 records · Page 2Linked to original sources
PubMed1992

Oligo-2',5'-adenylate synthetase activity in cells persistently infected with human T-lymphotropic virus type I (HTLV-I).

Spontaneous production of interferon-gamma (IFN-gamma) was shown in several T-lymphoblastoid cell lines persistently infected with human T-lymphotropic virus (HTLV-1). However, the produced IFN-gamma was not always associated with the induction of the antivirus state. The induction of oligo-2',5'-adenylate synthetase (2-5AS) by IFN was studied in five human T-cell lines persistently infected with HTLV-I (MT-1, MT-2, SMT-1, HUT 102 and OKM-2). Four cell lines are able to produce IFN-gamma spontaneously, while the OKM-2 cell line is not. Poor induction of 2-5AS was recognized in three (MT-1, MT-2 and SMT-1) of the four cell lines producing IFN-gamma, though the poor induction was improved after long-term cultivation of cells with IFN-alpha. On the contrary, in the OKM-2 cell line, significant activity of the enzyme was induced by IFN-alpha. Induction of 2-5AS was not correlated with cell growth inhibition, but with the antivirus state. Furthermore, an inverse relationship between IFN-gamma production and 2-5AS induction was demonstrated in these cell lines with the exception of HUT 102 cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Sequence specific block of in vitro DNA synthesis with isopropyl phosphotriesters in template oligodeoxyribonucleotides.

We have synthesized four oligodeoxyribonucleotides each bearing an isopropyl phosphotriester at a defined position. These oligomers were used as templates for in vitro DNA synthesis catalyzed by Escherichia coli DNA polymerase I large fragment. Results showed that the phosphotriester inhibits the DNA chain elongation and the level of the inhibition is dependent on the base 5' to the phosphotriester.

Base Sequence↗
PubMed1991

High-performance liquid chromatographic determination of lansoprazole and its metabolites in human serum and urine.

A simple and sensitive high-performance liquid chromatographic method with ultraviolet detection is described for the simultaneous determination of lansoprazole and its metabolites in human serum and urine. The analytes in serum or urine were extracted with diethyl ether-dichloromethane (7:3, v/v) followed by evaporation, dissolution and injection into a reversed-phase column. The recoveries of authentic analytes added to serum at 0.05-2 micrograms/ml or to urine at 1-20 micrograms/ml were greater than 88%, with the coefficients of variation less than 7.1%. The minimum determinable concentrations of all analytes were 5 ng/ml in serum and 50 ng/ml in urine. The method was successfully applied to a pharmacokinetic study of lansoprazole in human.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1991

Column-switching techniques for high-performance liquid chromatography of ibuprofen and mefenamic acid in human serum with short-wavelength ultraviolet detection.

Column-switching techniques for high-performance liquid chromatography of two acidic drugs, ibuprofen and mefenamic acid, in human serum with short-wavelength ultraviolet detection are described. The method involved extraction of the analyte from acidified serum followed by the chromatographic analysis using column switching. Three ODS columns were used each with different mobile phase, utilizing the difference of ion-pair formation or of ionization caused by pH change. The method offered high sensitivity and selectivity, with short-wavelength ultraviolet detection at 221 nm for ibuprofen and at 219 nm for mefenamic acid. The detection limits were 0.5 ng/ml (2.4 pmol/ml) for ibuprofen and 0.1 ng/ml (0.4 pmol/ml) for mefenamic acid using 1 ml of serum, both at a signal-to-noise ratio of 3. With some modifications, the principle of the method would be applicable to other acidic compounds in biological fluids.

Chromatography, High Pressure Liquid↗
PubMed1991

Cloning of a DNA fragment encoding the 5'-terminus of the botulinum type E toxin gene from Clostridium butyricum strain BL6340.

Chromosomal DNA was extracted from toxigenic Clostridium butyricum strain BL6340 isolated from a case of infant botulism. After digestion by EcoRI, a DNA fragment of about 1 kbp was cloned into Escherichia coli using lambda gt11, and was subcloned into pUC118. The E. coli cells transformed with this cloned fragment produced a 33 kDa protein which reacted with monoclonal antibodies recognizing the light chain (Lc) component of botulinum type E toxin. The nucleotide sequence of the cloned fragment was determined. The sequence was similar to that from botulinum type E toxin gene fragments previously determined by our laboratory (strains Mashike, Otaru and Iwanai). Several highly homologous sequences among the botulinum type A, C, E, butyricum and tetanus toxin genes were found in both translated and untranslated regions. These results suggest that the toxin gene of C. butyricum may have evolved by transfer from C. botulinum.

Amino Acid Sequence↗
PubMed1991

Inhibition of DNA chain elongation by a phosphotriester linkage in template oligodeoxyribonucleotides.

We synthesized two oligodeoxyribonucleotides bearing an isopropyl phosphotriester at defined positions using new phosphorobisamidite chemistry. Diastereomers were separated with HPLC and their template properties were analyzed. Priming oligodeoxyribonucleotides labeled with 32P at the 5'-end were annealed to the modified oligodeoxyribonucleotides and elongated with DNA polymerase I large fragment from Escherichia coli. Results show that the phosphotriester inhibits the DNA chain elongation partially and the extents of the inhibition are remarkably different between the two diastereomers.

Base Sequence↗
PubMed1990

High-performance liquid chromatographic determination of phenylpropanolamine in human plasma and urine, using column switching combined with ion-pair chromatography.

A highly sensitive and selective high-performance liquid chromatographic method with ultraviolet detection at 205 nm, without prior derivatization, is described for the determination of phenylpropanolamine in human plasma and urine. The method involved extraction of plasma or urine at a basic pH with diethyl ether, and chromatographic analysis using column switching combined with ion-pair chromatography. In the first octadecylsilica column, the drug was preseparated from endogenous substances in samples by ion-pair chromatography. After column switching, in the second octadecylsilica column, the heart-cut fraction containing the analyte was further separated by reversed-phase chromatography. The detection limits were 0.4 ng/ml in plasma and 8 ng/ml in urine, both at a single-to-noise ratio of 3. The method was applied to the determination of the drug in plasma and urine after oral administration of 25 mg of phenylpropanolamine hydrochloride in water to a healthy human volunteer.

Chromatography, High Pressure Liquid↗
PubMed1990

The nucleotide and deduced amino acid sequences of EcoRI fragment containing the 5'-terminal region of Clostridium botulinum type E toxin gene cloned from Mashike, Iwanai and Otaru strains.

Chromosomal DNAs were extracted from toxigenic three Clostridium botulinum type E strains isolated from food-borne botulism. After digestion by EcoRI, the fragments were cloned into Escherichia coli by using bacteriophage lambda gt11 and screened with monoclonal antibody recognizing the light chain component of botulinum type E toxin. The fragments (about 1 kbp size) cloned from each strain were recloned into a plasmid vector pUC118. The E. coli cells transformed with the recombinant plasmids produced 33 kDa protein with or without IPTG (isopropyl-beta-D-thiogalactopyranoside) which reacted with the monoclonal antibody. The nucleotide sequences of the cloned EcoRI fragments from the three type E strains were identical and contain the 5'-terminal region of the type E toxin gene. It was also found that there exist several highly homologous nucleotide sequences among the botulinum types A, C and E, and tetanus toxin genes in both translated and untranslated regions.

Amino Acid Sequence↗
PubMed1990

Gastro-intestinal absorption of ethyl 2-chloro-3-[4-(2-methyl-2-phenylpropyloxy)phenyl]propionate from different dosage forms in rats and dogs.

To obtain information as to a suitable formulation of ethyl 2-chloro-3-[4-(2-methyl-2-phenylpropyloxy)-phenyl]propionate (AL-294), an antihyperlipidemic drug of low water solubility, the bioavailability after its oral administration in various dosage forms was evaluated in rats and dogs. After AL-294 was administered orally, AL-294 acid (2-chloro-3-[4-(2-methyl-2-phenylpropyloxy)phenyl]propionic acid), which is a metabolite of AL-294, was detected in the plasma. Therefore, absorbability of AL-294 was evaluated using plasma AL-294 acid levels. AL-294 in an oil solution or in a gelatin capsule showed poor absorption, whereas it's absorption was greatly enhanced in the form of an emulsion. The postprandial administration also showed better absorption. The elimination rate of AL-294 acid from the plasma after oral administration of the emulsion was similar to that after intravenous administration of a sodium salt of AL-294 acid.

Animals↗
PubMed1989

Determination of manidipine and its pyridine metabolite in human serum by high-performance liquid chromatography with ultraviolet detection and column switching.

A highly sensitive and selective high-performance liquid chromatographic method using column switching is described for the determination of the dihydropyridine calcium antagonist manidipine (I),2-[4-(diphenylmethyl)-1-piperazinyl]ethyl methyl (+/- )-1,4-dihydro-2,6-dimethyl-4-(m-nitrophenyl)-3,5- pyridinedicarboxylate, and its pyridine metabolite (II), 2-[4-(diphenylmethyl)-1-piperazinyl]ethyl methyl 2,6-dimethyl-4-(m-nitrophenyl)-3,5-pyridinedicarboxylate, in human serum. The method is based on the combination of the column-switching technique and ion-pair chromatography. In the first ODS column, I and II are preseparated from endogenous substances in serum with a mobile phase containing sodium nonane sulphonate as an ion-pair reagent. After column switching, in the second ODS column, the heart-cut fraction containing I and II is further separated from the co-eluted substances through the first column with a mobile phase containing no ion-pair reagent. By using microbore columns with a diameter of 2.1 mm, the sensitivity is almost double that given by conventional bore columns with a diameter of 4.6 mm. The method offers high sensitivity and selectivity with short-wavelength ultraviolet detection at 230 nm. The detection limits of both I and II are 0.1 ng/ml using 1 ml of serum. The method is suitable for the pharmacokinetic study of I.2HCl after oral administration to man.

Administration, Oral↗
PubMed1989

Sensitive high-performance liquid chromatographic determination of ionic drugs in biological fluids with short-wavelength ultraviolet detection using column switching combined with ion-pair chromatography: application to basic compounds.

A highly sensitive and selective high-performance liquid chromatographic method with short-wavelength UV detection is described for the determination of ionic compounds in biological fluids, which was applied to two basic compounds, 2-(3-[4-(4-fluorophenyl)-1-piperazinyl]propyl)-6,7,8,9-tetrahydro-2H-nap htho [2,3-b][1,4]oxazin-3(4H)-one (I) and methyl 2-(4-diphenylmethyl-1-piperazinyl)ethyl (+/-)-1,4-dihydro-2,6-dimethyl-4-(m-nitrophenyl)-3,5-pyridinedicarboxyla te (II), in human serum. The method is based on the combination of the column-switching technique and ion-pair chromatography. In the first ODS column, the analyte is pre-separated from endogenous substances in serum by ion-pair chromatography. After column switching, in the second ODS column the heart-cut fraction containing the analyte is further separated by non-ion-pair chromatography from coeluted endogenous substances from the first ODS column. The proposed method offered high sensitivity and selectivity with UV detection at 215 nm for I and 230 nm for II. The detection limits were 0.2 ng/ml for both I and II using 1 ml of serum. The principle of the proposed method would be applicable to both acidic and basic compounds in biological fluids with a suitable ion-pair reagent.

Chromatography, High Pressure Liquid↗
PubMed1988

Decrease of oligo-2',5'-adenylate synthetase activity in BALB3T3 cell persistently infected with Moloney murine leukemia virus.

The induction of oligo-2',5'-adenylate synthetase (2-5AS) activity by interferon (IFN) was decreased in BALB3T3 cells persistently infected with Moloney murine leukemia virus (Mo-MLV) as compared with uninfected cells. Furthermore, the correlation between increased susceptibility to vesicular stomatitis virus (VSV) infection and reduced 2-5AS activity was recognized in the Mo-MLV persistently infected cells. The decrease of enzyme activity was confirmed by a solid phase reaction and an analysis of reaction products by Fast Polynucleotide Liquid Chromatography (FPLC) in addition to a liquid phase reaction. In a solid-phase reaction, the enzyme protein binds to polyinosinate-cytidylate (Poly I:C) agarose beads and other cellular proteins can be washed out from the reaction mixtures. Therefore, these results indicate that the decrease of IFN-induced enzyme activity is due to the suppression of transcription and/or translation of 2-5AS mRNA. A decreased amount of 2-5AS mRNA in persistently infected cells was observed by Northern blot and dot-blot hybridization. On the other hand, cell lysate of Mo-MLV infected cells inhibited the 2-5AS activity in liquid phase reaction. The inhibition may also be partly due to the degradation of oligo-2',5'-adenylate (2-5A) formed by 2-5AS.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Oligo-2',5'-adenylate synthetase activity in K562 cell lines persistently infected with measles or mumps virus.

Fluctuation of oligo-2',5'-adenylate synthetase (2-5AS) activity was examined in K562 cells infected with vaccine strains of measles virus (strains AIK-C and CAM-70) and mumps virus (strains Torii and Miyahara). Persistent infection was easily established in the mumps virus-infected cells without significant cytolysis or cell killing. In contrast, most of the cells infected with measles virus were killed by extensive cytolysis within 3 to 4 days. The small number of cells that did survive became persistently infected. That these persistently infected cells carried a virus antigen was confirmed by fluorescein isothiocyanate-labelled anti-measles virus rabbit antiserum and anti-mumps virus rabbit antiserum. The cells produced infectious progeny virus as well as interferon (IFN). Little induction of 2-5AS activity by IFN was demonstrated during the early stages of infection by these viruses. Similar results were observed in some of the persistently infected cells but not, however, K-CMP cells (K562 cells persistently infected with CAM-70) or K-MMP cells (K562 cells persistently infected with Miyahara). Failure to induce 2-5AS activity was unchanged in cells cultured for more than 6 months. The decrease of 2-5AS activity observed in K-MTP cells (K562 cells persistently infected with Torii) was the result of suppression of transcription of 2-5AS mRNA. On the other hand, a normal level of mRNA was found in K-AKP cells (K562 cells persistently infected with AIK-C). Therefore, it is suggested that the decrease of 2-5AS activity in K-AKP cells may be due to a failure to translate 2-5AS mRNA.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

[Clinical study on the effect of adjuvant immunochemotherapy using OK-432 and 5-FU in pharyngeal and laryngeal cancers].

A randomized controlled trial was carried out on 38 pharyngeal and 59 laryngeal previously untreated cancers to evaluate the effects of adjuvant immunochemotherapy using 5-FU with and without OK-432. After each fundamental therapy, 5-FU was given orally at a dose of 200-300 mg/day for more than a year. OK-432 was intracutaneously administered at a dose of 5KE once a week for more than a year. Three-year survival rates and disease-free intervals were estimated for the two groups. In cases of pharyngeal cancer, the 3-year survival rate was 58% in both groups and the disease-free interval rates for up to 3 years after the fundamental therapy was 49% in the OK-432 + 5-FU group and 52% in the 5-FU group. These results showed no statistically significant difference. In laryngeal cancers, the 3-year survival rate was 96% in the OK-432 + 5-FU group and 82% in the 5-FU group. These results also showed no statistically significant difference. The disease-free interval rates were 87% in the OK-432 + 5-FU group and 64% in the 5-FU group, revealing a statistically significant difference (p less than 0.1). This suggests that OK-432 is more effective in producing a higher survival rate in cases of laryngeal cancer.

Administration, Oral↗
PubMed1987

Orally active 1-(cyclohexyloxycarbonyloxy)alkyl ester prodrugs of cefotiam.

Orally active 1-(alkyl substituted cyclohexyloxycarbonyloxy)alkyl ester prodrugs (9b-h) of 7 beta-[2-(2-aminothiazol-4-yl)acetamido]-3- [[[1-(2-dimethylaminoethyl)-1H-tetrazol-5-yl]thio]-methyl]ceph+ ++-3- em-4-carboxylic acid (cefotiam, CTM) have been studied as well as the thia (9i) and aza (9j) analogs. These represent derivatives of the 1-(cyclohexylacetoxy)ethyl ester (2) of CTM. The syntheses and oral bioavailability (BA) in mice are described. Among them, the 1-(cyclohexyloxycarbonyloxy)butyl ester (9h) gave the highest BA, 93.5%; the esters having a cyclohexyloxy group in the ester moiety gave BAs of more than 75%, although the BA of the 1-(ethoxycarbonyloxy)ethyl ester (9a) was only 23.9%. The thia analog showed a moderate BA, 46%, but the aza analog, 9j, did not show a BA of CTM. These results indicate that the 1-(substituted cyclohexyloxycarbonyloxy)alkyl group was the suitable promoiety to improve the oral BA of CTM. Chiral 1-(alkoxycarbonyloxy)alkyl groups used as the ester moiety, gave an almost 1: 1 mixture of diastereoisomeric esters. These were tested as such. However, an experiment in which the separated isomers of the 1-(cyclohexyloxycarbonyloxy)ethyl ester (9d) were administered orally confirmed that both diastereoisomers gave identical BAs.

Administration, Oral↗