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Biomedical subjects

T Tsuchiya

Publications and source records attributed to T Tsuchiya.

At least 325 records · Page 18Linked to original sources

Detoxification of paraquat poisoning: effects of alkylsulfates and alkylsulfonates on paraquat poisoning in mice and rats.

The study revealed that high molecular polyvinyl sulfate (PVP) or sulfonate (PVS), and low molecular alkyldisulfonates (NaO3S(CH2)nSO3Na, n = 2--5: EDS, TDS, BDS and PDS) can alleviate acute toxicity of the herbicide, paraquat dichloride (PQ) in mice. Their activity as antidotes and the mode of the action varied depending on molecular size. The survival rate for mice receiving PQ at 200 mg/kg alone was increasingly improved when the dose of antidotes was increased from 8 to 10 times the dose of PQ; all the test compounds, except EDS (70% survival), achieved a survival rate of 100%. When test compounds were orally dosed to mice in a mixture with PQ, they improved LD50 of PQ alone. With the low molecular compounds EDS, TDS, BDS and PDS, the value increased to about 2 to 3 times (300-458 mg/kg) over that of PQ alone (140 mg/kg). With high molecular PVS and PVP, the combination reached about a 7 fold (900-1000 mg/kg) increase in LD50 value. The formation of lipid peroxide in lungs of rats due to PQ tended to be suppressed by concomitant administration of carbohydrate sulfate (DS and GS). PVP, BDS and TDS were more effective in depressing synthesis of lipid peroxide than DS or GS in the lungs, although BDS and TDS were less effective in suppressing PQ absorption from the rat small intestine than DS, GS or PVP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

New oral dosage form for elderly patients: preparation and characterization of silk fibroin gel.

The pharmaceutical utility of silk fibroin as a possible material for an oral dosage form for elderly patients was investigated. Silk fibroin gel (SFG) was prepared from its aqueous solution. The gel formation was studied as a function of adjusted pH and concentration of silk fibroin (SF). On the basis of Fourier transform infrared spectroscopy of SFG, the transition from the random coil to the beta-structure was observed. The rate of gelation was sufficiently accelerated by the addition of glycerol to the SF aqueous solution. The glycerol content also affected the rate of gelation of the SF solution. Rheological properties of SFG were evaluated using a creep meter. The SF content and/or glycerol content affected the breaking stress of SFG. Moisture desorption from SFG was retarded with an increase in glycerol content. It was found that SFG was able to be prepared at room temperature (20 +/- 5 degrees C), and the SF content and glycerol content affected the formation and physicochemical properties of SFG.

Administration, Oral↗

New oral dosage form for elderly patients. II. Release behavior of benfotiamine from silk fibroin gel.

Silk fibroin gel (SFG) containing benfotiamine (BTMP) was prepared. The release behavior of BTMP from SFG was studied as a function of silk fibroin (SF) content and glycerol content, and the influence of the existence of beta-cyclodextrin (beta-CD) on the physicochemical properties of SFG were investigated. The release rate of BTMP from SFG was retarded by an increase in SF concentration. The addition of beta-CD affected both the release properties and rheological properties of the SFG. It was found from the results of the "paddle-bead method" that the release profiles of BTMP from SFG were inversely proportional to the SFG firmness.

Adjuvants, Immunologic↗

[Gastric emptying of semi-solid meal in normal man with special reference to relationship between plasma acetoaminophen concentrations and gastric emptying time].

Correlation between gastric emptying time measured by a radioisotope method and plasma acetoaminophen level was studied in 11 preoperative early gastric cancer in semisolid meal. A significant correlation was found between both gastric emptying half-time and plasma acetoaminophen level at 30, 45 minutes after ingestion of meal, and plasma acetoaminophen level at maximum. We conclude that acetoaminophen analysis is useful to measure gastric emptying at semisolid meal.

Acetaminophen↗

Assessment of genetic variations within populations of Sika deer in Japan by analysis of randomly amplified polymorphic DNA (RAPD).

Random amplified polymorphic DNA (RAPD) was exploited as a genetic marker to assess the level of genetic variation in populations of Sika deer, Cervus nippon, in Japan. DNA samples were collected from three local populations in Japan, namely, Kinkazan, Goyozan and Ashoro populations. Four arbitrary primers, when used individually, amplified an average of five RAPD fragments in the polymerase chain reaction (PCR). The number of polymorphic bands was scored to calculate band-sharing coefficients within populations. Average band-sharing coefficients revealed a higher degree of homogeneity in the Kinkazan population. Samples collected from larger populations, namely, Ashoro and Goyozan, revealed greater polymorphism than samples from the Kinkazan deer. Our data suggest that RAPD is useful as a marker for detecting genetic variations in populations of Sika deer with reduced levels of genetic diversity.

Animals↗

A new hypothesis of tumorigenesis induced by biomaterials: inhibitory potentials of intercellular communication play an important role on the tumor-promotion stage.

A possible mechanism of tumorigenesis induced by the polyetherurethanes (PEUs) is clarified as follows: the tumor-promoting activities of the PEUs were stronger than the initiating activities; the promotion was facilitated by the polyether soft segment moiety such as poly (tetramethylene oxide) (PTMO), resulting in the inhibition of the gap-junctional intercellular communication; this inhibition was caused by leachable oligomers, degradation, and direct cell/material interaction. On the basis of our recent studies, we also propose a new hypothesis that inhibitory potentials of the intercellular communication play an important role on the tumor-promoting stage in various biomaterials.

Biocompatible Materials↗

Studies on the tumor-promoting activities of additives in biomaterials: inhibition of metabolic cooperation by additives such as pigments and phenolic antioxidants.

The inhibitory activities on the intercellular gap-junctional communication were investigated using the V79 metabolic cooperation (MC) assay for the detection of tumor-promoting activities of additives such as pigments and phenolic antioxidants. Among six pigments, four chemicals showed inhibitory activities. The inhibitory potencies were ranked in the following order: sudan I > purple 201 > blue 204 > green 202. Sudan I and purple 201 showed stronger inhibitory activities than lithocholic acid, which is known to be a tumor promotor. However, quinizarine and red 225 did not inhibit at any concentration. Relating to eight phenolic antioxidants, four chemicals also showed inhibitory activities. Combining the present findings with previous ones, there are many factors that have tumor-promoting activities via inhibitory action on gap-junctional intercellular communication in biomaterials.

Animals↗

Studies on the tumor-promoting activity of polyethylene: inhibitory activity of metabolic cooperation of polyethylene films containing an antioxidant.

Tumor-promoting activity, inhibitory activity on the gap-junctional intercellular communication of polyethylene (PE) film containing a model antioxidant, 2,2'-methylene-bis(4-methyl-6-tert-butylphenol) (MBMBP), at various amounts was assessed by V79 metabolic cooperation (MC) assay. The extracts prepared from PE film containing MBMBP showed the inhibitory activities and the potencies of the inhibitory activities depended on the amount of MBMBP involved in the film, whereas the extract prepared from MBMBP-free PE film did not show any inhibitory activities. However, the inhibitory activities were observed when MC assay was carried out on the surface of the MBMBP-free film. These findings indicate that tumor-promoting activity of PE film is influenced by the surface property of the film as well as by amount and kind of additives incorporated.

Antioxidants↗

Posterior bite raising effects on a primary anterior crossbite case.

Stainless steel crowns were cemented on the mandibular primary molars to make bite raising for an anterior reversed bite case. Chewing force and MKG were recorded before and after bite raising. Data from MKG revealed that co-ordination pattern of muscle activities after bite raising became higher in masseter muscles than those before anterior reversed bite was corrected easily without any incisal interferences by using this treatment method.

Bite Force↗

F0F1-ATPase of Vibrio parahaemolyticus: purification using new detergents and characterization.

Previous attempts to isolate a stable F0F1-ATPase complex (H(+)-translocating ATPase) from Vibrio parahaemolyticus have been unsuccessful. Using new non-ionic detergents (alkyl thiomaltosides), a stable F0F1 complex with a high specific activity (15-25 units/mg protein) was purified and characterized. The purified F0F1-ATPase consists of eight subunits (alpha, beta, gamma, delta, epsilon, a, b and c). The new detergents, in combination with sucrose (or glycerol), lipid, dithiothreitol and phenylmethylsulfonyl fluoride, effectively stabilized the F0F1 complex. The ATPase activity of the F0F1 complex was greatly increased by anions, such as SO4(2-) and SO3(2-). Sodium ion increased the activity by about 2-fold. Dicyclohexylcarbodiimide, Zn2+, 4-acetamido-4'-isothiocyanostilben-2,2'disulfonate and tetrachlorosalicylanilide inhibited F0F1-ATPase activity. Ethanol, which stimulated F1-ATPase activity, inhibited F0F1-ATPase activity. Methanol, Na3VO4 and bafilomycin A1 did not have any significant effect on F0F1-ATPase activity, although methanol, like ethanol, stimulated F1-ATPase activity.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗

Cloning and sequencing of the gene for the lactose carrier of Citrobacter freundii.

The gene coding for the lactose carrier of Citrobacter freundii was cloned into the plasmid pBR322. The gene was sequenced and the amino acid sequence was found to be 70% identical to the lactose carrier of E. coli. All of the charged residues in the membrane spanning region were conserved. The sugar specificity is somewhat different from that of E. coli. The C. freundii carrier has less activity for lactose and more activity for o-nitrophenyl-galactose (ONPG) than the carrier of E. coli.

Amino Acid Sequence↗

Modulation of AP-1 activity by nitric oxide (NO) in vitro: NO-mediated modulation of AP-1.

To understand the role of nitric oxide (NO) in controlling the specific DNA-binding activities of transcriptional factors, we investigated the in vitro effect of the NO-donor sodium nitroprusside (SNP) on the AP-1 activity of cultured mouse cerebellar granule cells. A gel-mobility assay showed that SNP inhibited AP-1 activity in the presence, but not the absence of dithiothreitol (DTT). This DTT-dependent inhibition of AP-1 activity by SNP corresponded with the activation of the chemical reactivity of SNP with DTT, which can be monitored by the production of nitrite (NO2-). In contrast, diamide, a typical sulfhydryl oxidizing agent, inhibited AP-1 activity in the absence of DTT and its inhibitory effect was reversed competitively by DTT. Studies using structurally or functionally related analogues of SNP demonstrated that S-nitrosylation of the AP-1 moiety mediated by some NO-carriers but not by free NO, which can be produced by the chemical reaction of SNP with DTT, was responsible for the inhibition of AP-1 activity, suggesting NO-mediated regulation of the AP-1 transcriptional factor.

3T3 Cells↗

Distinct kinetics of subunit autolysis in mammalian m-calpain activation.

Subunit autolysis of mammalian m-calpain upon activation was examined in kinetic terms using a set of antibodies recognizing different portions of the protease. Activation of m-calpain by calcium resulted in no apparent autolysis in the large catalytic subunit, whereas the small regulatory subunit underwent immediate autolysis followed by substrate proteolysis. This profile of subunit autolysis is distinct from that of the other ubiquitous isozyme, mu-calpain, in which autolysis of the large subunit and then of the small subunit precedes substrate proteolysis under the normal conditions. The activation state of m-calpain thus is not reflected by the large subunit autolysis. The mode and role of autolysis may vary among calpain isozymes.

Amino Acid Sequence↗

Retrovirus-mediated gene transfer of human pyruvate kinase (PK) cDNA into murine hematopoietic cells: implications for gene therapy of human PK deficiency.

With the advent of recent molecular studies, nonspherocytic hemolytic anemia caused by red blood cell pyruvate kinase (PK) deficiency is now considered to be caused by a structural mutation of the PK-LR gene. Because PK deficiency is a monogenic disorder, the introduction of the normal PK gene into a patient's bone marrow stem cells should cure the disorder. To study the feasibility of gene therapy for PK deficiency, we first constructed the PK retrovirus pMNSM-hPK using human liver-type PK (LPK) cDNA and obtained a producer cell line of E86/AmPK. By using the supernatant of this virus-producer cell, we transduced NIH/3T3 cells, mouse leukemic cells (NFS60, FDCP-2), and human leukemic cells (K562, HEL). The expression of human LPK enzyme activity was ascertained from the retrovirally transduced NIH/3T3 cells. Northern blot analysis demonstrated the expression of the human LPK mRNA in each transduced cell line. Furthermore, bone marrow stem cells (c-kit+, Lin-, Thy-1lo) sorted by fluorescence-activated cell sorting were also transduced by the producer cells in the presence of interleukin-3 and interleukin-6, and were transplanted into lethally irradiated C57BL/6 mice. Polymerase chain reaction analysis demonstrated the expression of human LPK mRNA in both the peripheral blood and hematopoietic organs on day 30 and on day 135 of bone marrow transplantation.

Animals↗

Cloning and sequencing of an Na+/H+ antiporter gene from the marine bacterium Vibrio alginolyticus.

A gene has been cloned from a DNA library from the marine bacterium Vibrio alginolyticus that functionally complements a mutant strain of Escherichia coli, NM81, defective in an Na+/H+ antiporter (NhaA). The cloned Vibrio gene restored NM81 to grow in a medium containing 0.5 M NaCl at pH 7.5 and concomitantly led to an increase in Na+/H+ antiport activity. The nucleotide sequence of the cloned fragment revealed an open reading frame, which encodes a protein with a predicted 383 amino acid sequence and molecular mass of 40,400 Da. The hydropathy profile is characteristic of a membrane protein with 11 membrane spanning regions. The deduced amino acid sequence is 58% identical with E. coli NhaA.

Amino Acid Sequence↗

Limited diffusibility of gene products directed by a single nucleus in the cytoplasm of multinucleated myofibres.

Two types of beta-galactosidase genes, whose products are distributed in the nucleus (N beta-gal) or cytoplasm (C beta-gal), were injected with fructose intramuscularly into the quadriceps of adult mice. Regionally restricted and overlapped distributions of both gene products were observed in the myofibres. These findings indicate that N beta-gal is incorporated into the nucleus responsible for its synthesis and that C beta-gal becomes located in the vicinity of the nucleus after its synthesis. This restricted location of C beta-gal in myofibres remained unchanged during the development of infant mouse muscle. Thus, the gene products directed by the nucleus of myofibres seem to show limited diffusibility, suggesting a universal localization of subcellular domains in myofibres.

Animals↗

Improved sensitivity and decreased sample size in a cytotoxicity test for biomaterials: a modified colony microassay using a microplate and crystal violet staining.

Modified Eagle's minimum essential medium supplemented with 5% fetal calf serum was highly sensitive to cytotoxicity and formed large control colonies in the V79 colony assay. A highly sensitive cytotoxicity test was developed using 96-well microtiter plates. Test chemicals or extracts of polyurethane materials containing the same chemicals were added 24 h after inoculation of cell suspensions. The cells were fixed and stained with crystal violet after additional culture for 6 days (V79 cells) or 10 days (Balb/3T3 cells). In terms of sensitivity and rapid quantitative measurement, this modified colony microassay, using a low cell density in 96-well microplates, was superior to various cytotoxicity tests such as colony, growth inhibition, cytolethality, and agar diffusion assays.

Animals↗

Molecular characterization of rice genes specifically expressed in the anther tapetum.

In situ localization of mRNA was carried out on two cDNAs (Osc4 and Osc6) that had been isolated from rice anthers at the microspore stage. The mRNA corresponding to each cDNA was shown to be localized only in the tapetal cells of the rice immature anthers, but not in the microspores or the mature pollen. The corresponding genomic clone, Osg6B, was isolated, and its 5'-upstream region was found to regulate beta-glucuronidase expression in the tapetum of transgenic tobacco. A set of 5' deletions was also generated and a 1095 bp 5' region was revealed to be necessary for activation of the Osg6B promoter in transgenic tobacco.

Base Sequence↗