Biomedical subjects

T Tsuchiya

Publications and source records attributed to T Tsuchiya.

At least 145 records · Page 8Linked to original sources

PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 25). Effects of 2- and 4- week repeated-dosing of dibromoacetic acid.

To assess the sensitivity of rats to a testicular toxicant, 2- and 4-week repeated-dose studies using dibromoacetic acid (DBAA) were performed. Four groups of 6- or 8-week old male SD rats were given DBAA at a daily dosage of 0, 5, 50 or 250 mg/kg. The highest dose was given for 2 weeks, and the others for 2 and 4 weeks. There were no effects on body or testicular weights in any of the DBAA-treated groups. However, the mean absolute epididymal weight in the 250 mg/kg group was significantly lower than that of the control group. Histopathologically, atypical residual bodies (ARBs) and retention of Step 19 spermatids were evident with this high dose. In the same group, ARBs in the epididymal ducts and narrowing of these lumina were also observed. Retention of Step 19 spermatids was similarly apparent in the testes of animals given 50 mg/kg for 2 or 4 weeks, and in one animal given 5 mg/kg for 4 weeks. Based on these data, DBAA testicular toxicity is histopathologically detectable within 2-weeks of repeated dosing at an appropriate dose.

Acetates↗

PubMed2000

The effects of temperature on the mechanical performance in fatigued single muscle fibers of the frog induced by twitch and tetanus.

Muscle fatigue induced by consecutive twitches or tetani was studied in single skeletal muscle fibers of the frog, Rana japonica. The fatigue by twitch appeared sooner after the start of stimulation at lower temperatures (2-5 degrees C) than at higher ones (15-20 degrees C), while the fatigue by tetanus appeared sooner at higher temperatures. When a twitch-fatigued fiber was bathed in a solution with caffeine (15 mM), the contracture force was much higher than the fatigued force, while in tetanus fatigue, the force by caffeine was not different from the fatigued force. The length-force relation in fatigued fibers was compared with that in pre-fatigue at low and high temperatures. It was noticed that the ascending limb of the length-force curve in fatigued fibers by twitch was lower than that in pre-fatigue at the low temperatures; namely, the fatigue by twitch was more marked in shorter muscle length, while no marked change in the length-force relation was detected in the tetanus fatigue at the low and high temperatures. The maximum shortening velocity, measured by the slack test, decreased in both types of fatigue. These results suggest that the fatigue by twitch may be mainly due to the failure of activation of the contractile system, while in the fatigue by tetanus, the rate of the interaction between actin and myosin may be impaired due to the change in intracellular chemical environment.

Adenosine Triphosphate↗

PubMed2000

[Pulmonary adenocarcinoma with central ossification].

A 70-year-old woman was admitted in April 1997 because a coin lesion in the left middle lung field was observed on chest roentgenograms. The lesion had slightly increased in size since 1994, when it was first pointed out. Chest computed tomography elucidated a high density area with irregular borders in the center of the shadow in S 3 a. Transbronchial biopsy revealed adenocarcinoma, and a left upper lobectomy was performed. The resected specimen demonstrated a tumor with central ossification and pleural indentation. Histologic examination determined that the the tumor was a papillary adenocarcinoma with central ossification containing marrow tissue. Primary lung cancer with central ossification is very rare, and only 6 cases have been reported to date, including this case.

Adenocarcinoma, Papillary↗

PubMed2000

Aldose reductase mRNA expression is associated with rapid development of diabetic microangiopathy in Japanese Type 2 diabetic (T2DM) patients.

There appears to be an obvious difference in the susceptibility to diabetic microangiopathy among Type 2 diabetic (T2DM) patients. We examined the hypothesis that aldose reductase (AR) messenger ribonucleic acid (mRNA) expression may be enhanced in diabetic patients susceptible to diabetic microangiopathy by measuring AR mRNA expression in the polymorphonuclear leukocytes (PMNs) obtained from T2DM patients. The AR mRNA and beta-actin mRNA expressions were measured by reverse transcription-polymerase chain reaction method. The relative AR mRNA expression to beta-actin mRNA expression significantly increased in the PMNs of T2DM patients, compared to normal healthy controls. The relative AR mRNA expression tended to increase with an increase of glycosylated haemoglobin A1c (HbA1c) levels. The patients who showed both progressive diabetic retinopathy and diabetic neuropathy within 10 years after the diagnosis of T2DM (Group I) showed significantly 1.6 times higher AR mRNA expressions than those who have not shown both complications over 10 years after diagnosis (Group II), in spite of no obvious difference in glycaemic control between both groups. The present data indicate that the AR mRNA expression increased in the PMNs of T2DM patients and there is an obvious difference in the PMNs AR mRNA expression between T2DM patients susceptible and relatively resistant to the development of diabetic microangiopathy.

Aged↗

PubMed2000

A study on task-analysis of clinical pathologists as medical consultants in Nihon University Hospital--a Japanese perspective by comparison with current status in the USA.

To identify our role and the customers' satisfaction, the on-call consultation service records of the Department of Clinical Pathology, Nihon University School of Medicine, Itabashi Hospital (NUIH), were analyzed. Between 1995 and 1998, 1,789 consultation services were recorded, and approximately 40% were from physicians, and 50% were from medical technologists. During office hours, many physicians made contact with us at the office of clinical pathology, the clinical laboratory and other places in the hospital by various means. They asked us to interpret multidisciplinary laboratory data, and to provide the specific information that might affect clinical management. Medical technologists asked for clinical information of patients with extreme measured values and requested that we contact with physicians. In contrast, on weekends/holidays or after routine working hours, physicians sometimes requested non-automated laboratory tests such as peripheral blood smears/bone marrow smears or Gram stains. The major contents of our responses to medical technologists were concerned with blood banking and handling of instruments not to be operated in routine work. These results reconfirm that we are still required to have clinical competence for common laboratory procedures and to have the capability of interpretation of multidisciplinary laboratory data in the university hospital. Traditionally, most Japanese clinical pathologists have been focused their attention on bench work in research laboratories. However, the present study shows that the clinical pathologists need to bridge the real gap between laboratory technology and patient care. Our on-call service system can enhance the education of clinical pathologists, and improve not only laboratory quality assurance but also patient care. In addition, in response to a need for customer access to this service with a shortage of clinical pathologists, a more effective method would be to set up a proactive systemic approach in a more rigorous academic environment adopting advances in medical informatics.

Consultants↗

PubMed1999

Expression of human histo-blood group ABO genes is dependent upon DNA methylation of the promoter region.

We have investigated the regulatory role of DNA methylation in the expression of the human histo-blood group ABO genes. The ABO gene promoter region contains a CpG island whose methylation status correlates well with gene expression in the cell lines tested. The CpG island was found hypomethylated in some cell lines that expressed ABO genes, whereas the other cell lines that did not express ABO genes were hypermethylated. Whereas constitutive transcriptional activity of the ABO gene promoter was demonstrated in both expressor and nonexpressor cell lines by transient transfection of reporter constructs containing the ABO gene promoter sequence, HhaI methylase-catalyzed in vitro methylation of the promoter region prior to DNA transfection suppressed the promoter activity when introduced into the expressor gastric cancer cell line KATOIII cells. On the other hand, in the nonexpressor gastric cancer cell line MKN28 cells, treatment with DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine resulted in demethylation of the ABO gene promoter and appearance of A-transferase messages, as well as A-antigens synthesized by A-transferase. Taken together, these studies suggest that DNA methylation of the ABO gene promoter may play an important role in the regulation of ABO gene expression.

ABO Blood-Group System↗

PubMed1999

Cloning of chlorophyllase, the key enzyme in chlorophyll degradation: finding of a lipase motif and the induction by methyl jasmonate.

Chlorophyllase (Chlase) is the first enzyme involved in chlorophyll (Chl) degradation and catalyzes the hydrolysis of ester bond to yield chlorophyllide and phytol. In the present study, we isolated the Chlase cDNA. We synthesized degenerate oligo DNA probes based on the internal amino acid sequences of purified Chlase from Chenopodium album, screened the C. album cDNA library, and cloned a cDNA (CaCLH, C. album chlorophyll-chlorophyllido hydrolase). The deduced amino acid sequence (347 aa residues) had a lipase motif overlapping with an ATP/GTP-binding motif (P-loop). CaCLH possibly was localized in the extraplastidic part of the cell, because a putative signal sequence for endoplasmic reticulum is at the N terminus. The amino acid sequence shared 37% identity with a function-unknown gene whose mRNA is inducible by coronatine and methyl jasmonate (MeJA) in Arabidopsis thaliana (AtCLH1). We expressed the gene products of AtCLH1 and of CaCLH in Escherichia coli, and they similarly exhibited Chlase activity. Moreover, we isolated another full-length cDNA based on an Arabidopsis genomic fragment and expressed it in E. coli, demonstrating the presence of the second Arabidopsis CLH gene (AtCLH2). No typical feature of signal sequence was identified in AtCLH1, whereas AtCLH2 had a typical signal sequence for chloroplast. AtCLH1 mRNA was induced rapidly by a treatment of MeJA, which is known to promote senescence and Chl degradation in plants, and a high mRNA level was maintained up to 9 h. AtCLH2, however, did not respond to MeJA.

Acetates↗

PubMed1999

Melibiose carrier of Escherichia coli: use of cysteine mutagenesis to identify the amino acids on the hydrophilic face of transmembrane helix 2.

The melibiose carrier from Escherichia coli is a galactoside-cation symporter. Based on both experimental evidence and hydropathy analysis, 12 transmembrane helices have been assigned to this integral membrane protein. Transmembrane helix 2 contains several charged and polar amino acids that have been shown to be essential for the cation-coupled transport of melibiose. Starting with the cysteine-less melibiose carrier, we have individually substituted cysteine for amino acids 39-66, which includes the proposed transmembrane helix 2. In the resulting derivative carriers, we measured the transport of melibiose, determined the effect of the hydrophilic sulfhydryl reagent, p-chloromercuribenzenesulfonic acid (PCMBS), on transport in intact cells and inside out vesicles, and examined the ability of melibiose to protect the carrier from inactivation by the sulfhydryl reagent. We found a set of seven positions in which the reaction with the sulfhydryl reagent caused partial or complete loss of carrier function measured in intact cells or inside-out vesicles. The presence of melibiose protected five of these positions from reaction with PCMBS. The reaction of two additional positions with PCMBS resulted in the partial loss of transport function only in inside-out vesicles. Melibiose protected these two positions from reaction with the reagent. Together, the PCMBS-sensitive sites and charged residues assigned to helix 2 form a cluster of amino acids that map in three rows with each row comprised of every fourth residue. This is the pattern expected of residues that are part of an alpha-helical structure and thus the rows are tilted at an angle of 25 degrees to the helical axis. We suggest that these residues line the path of melibiose and its associated cation through the carrier.

4-Chloromercuribenzenesulfonate↗

PubMed1999

Synthesis and antitumor activity of 5'-demethyl-5'-trifluoromethyl-daunorubicin and -doxorubicin.

The title compounds were prepared by coupling phenyl 4-O-acetyl-2,3,6-trideoxy-6,6,6-trifluoro-1-thio-3-trifluoroacetamido -alpha-L- and beta-L-lyxo-hexopyranoside with daunomycinone. The key step of this synthesis is the C-trifluoromethylation of a 1-protected 2,3-dideoxy-3-azido-D-erythro-pentodialdose, prepared from 2-deoxy-D-erythro-pentose, to give a 6,6,6-trifluoro-L-lyxo-hexose derivative. The synthetic products showed higher cytotoxicity than doxorubicin against most of the human tumor cell lines tested in vitro, possibly by the effect of the CF3 group at C-5'.

Antineoplastic Agents↗

PubMed1999

Role of the amino-terminal region of the DnaA protein in opening of the duplex DNA at the oriC region.

We report in this paper that the amino acid residues Ile-26 and Leu-40 of the DnaA protein are essential for the DNA replication activity in vitro. Lines of evidence to support this conclusion are as follows. Variants of the DnaA protein containing either an Ile-26-Ser or Leu-40-Ser replacement were unable to support oriC DNA replication in vitro. Though the mutant DnaA proteins retained the capability to bind oriC DNA, they were unable to open the duplex DNA at oriC. Based on these and other results, we conclude that the N-terminal region of the DnaA protein is involved in the oligomerization of this protein, an essential step for the duplex opening activity at oriC.

Bacterial Proteins↗

PubMed1999

Involvement of Arg-328, Arg-334 and Arg-342 of DnaA protein in the functional interaction with acidic phospholipids.

We reported previously that three basic amino acids (Arg-360, Arg-364 and Lys-372) of DnaA protein are essential for its functional interaction with cardiolipin. In this study, we examined the effect of mutation of some basic amino acids in a potential amphipathic helix (from Lys-327 to Ile-345) of DnaA protein on this interaction. ATP binding to the mutant DnaA protein, in which Arg-328, Arg-334 and Arg-342 were changed to acidic amino acids, was less inhibited by cardiolipin than that of the wild-type protein, as was the case for mutant DnaA protein with mutations of Arg-360, Arg-364 and Lys-372. A mutant DnaA protein with mutations of all six basic amino acids showed the most resistance to the inhibition of ATP binding by cardiolipin. These results suggest that Arg-328, Arg-334 and Arg-342, like Arg-360, Arg-364 and Lys-372, are also involved in the functional interaction between DnaA protein and acidic phospholipids.

Adenosine Diphosphate↗

PubMed1999

Significance of late diastolic potential preceding Purkinje potential in verapamil-sensitive idiopathic left ventricular tachycardia.

BACKGROUND: Verapamil-sensitive idiopathic left ventricular tachycardia (VT) is due to reentry with an excitable gap. A late diastolic potential (LDP) is recorded during endocardial mapping of this VT, but its relation to the reentry circuit and significance in radiofrequency (RF) ablation remain to be elucidated. METHODS AND RESULTS: Sixteen consecutive patients with this specific VT were studied (12 men and 4 women; mean age, 32 years). In all patients, sustained VT was induced and during left ventricular endocardial mapping, LDP preceding Purkinje potential (PP) was recorded at the basal (11 patients), middle (3 patients), or apical septum (2 patients). The area with LDP recording was confined to a small region (0.5 to 1.0 cm2) in each patient and was included in the area where PP was recorded (2 to 3 cm2). The relative activation times of LDP, PP, and local ventricular potential (V) at the LDP recording site to the onset of QRS complex were -50.4+/-18.9, -15.2+/-9.6, and 3.0+/-13.3 ms, respectively. The earliest ventricular activation site during VT was identified at the posteroapical septum and was more apical in the septum than the region with LDP in every patient. In 9 patients, VT entrainment was done by pacing from the right ventricular outflow tract while recording LDP. During entrainment, LDP was orthodromically captured, and as the pacing rate was increased, the LDP-to-PP interval was prolonged, whereas stimulus-to-LDP and PP-to-V interval were constant. In 3 patients, the pressure applied to the catheter tip at the LDP region resulted in conduction block between LDP and PP and in VT termination. RF energy application at the LDP recording site successfully eliminated VT. CONCLUSIONS: LDP was suggested to represent the excitation at the entrance to the specialized area with a conduction delay in response to the increase in the rate within the critical slow conduction zone participating in the reentry circuit of this VT. LDP can be a useful marker for successful RF ablation for this VT.

Action Potentials↗

PubMed1999

Uncompetitive inhibition of superoxide generation by a synthetic peptide corresponding to a predicted NADPH binding site in gp91-phox, a component of the phagocyte respiratory oxidase.

The large subunit of cytochrome b558, gp91-phox, is believed to play a key role in superoxide generation in neutrophils by accepting electrons from NADPH and donating them to molecular oxygen. We found that a peptide corresponding to a predicted NADPH binding site in gp91-phox inhibited superoxide generation in a cell-free system consisting of neutrophil membrane and cytosol. Minimum essential sequence for the inhibition was KSVWYK, which corresponded to residues 420-425 (IC50 = 30 microM). Unlike other peptides known to inhibit the reaction, this peptide was effective even when added to the system after activation or to activated membrane from stimulated neutrophils. Furthermore, the peptide inhibited superoxide generation in a membrane system activated without cytosol. Kinetic analysis revealed that the peptide inhibited the reaction uncompetitively. These results suggest that the peptide combines with the activated cytochrome b558-NADPH complex and thereby inhibits electron transfer from NADPH to molecular oxygen.

Amino Acid Sequence↗

PubMed1999

Macromolecular antimicrobial glycoprotein, achacin, expressed in a methylotrophic yeast Pichia pastoris.

A cDNA encoding achacin, an antimicrobial glycoprotein from the body surface mucus of giant African snail Achacina fulica Férussac, was expressed in a methylotrophic yeast, Pichia pastoris, and recombinant achacin (rAch) was secreted in yeast minimal medium in a polyglycosylated form with 80 kDa. Carbohydrate analysis revealed that the glycosylated moiety of rAch was composed of 50 mol mannose and 2 mol N-acetylglucosamine residues. Antimicrobial activity using Escherichia coli and Staphylococcus aureus showed that the rAch had a behavior similar to its native counterpart. The rAch showed so wide an antimicrobial spectrum that 0.1 mg/ml rAch inhibited the growth of Pseudomonas fluorescens, Staphylococcus epidermidis, and Streptococcus faecalis in addition to E. coli and S. aureus, whereas it did not appreciably affect the growth of Proteus mirabilis, Bacillus cereus and Micrococcus luteus. The rAch was also effective in preventing growth of Vibrio anguillarum and Vibrio parahaemolyticus. The results suggested that the rAch had great potential of using as an antimicrobial agent.

Animals↗

PubMed1999

Synthesis and antitumor activity of 7-O-[2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L-talopyranosyl]- daunomycinone and -adriamycinone.

7-O-[2,6-Dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L-talopyranosyl]- daunomycinone and -adriamycinone have been prepared by the coupling of 3,4-di-O-acetyl-2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L- talopyranosyl iodide with daunomycinone. The key steps in this synthesis are the regioselective fluorination of methyl alpha-D-lyxopyranoside to give the 4-deoxy-4-fluoro-beta-L-ribopyranoside and the C-trifluoromethylation of the aldehydo-L-ribose derivative to give the 1,1,1-trifluoro-5-monofluoro-L-altritol derivative. Antitumor activities of the synthetic products were compared with those for the 2'-deoxy-2'-fluoro and 2',6'-dideoxy-5'-C-trifluoromethyl analogs.

Animals↗

PubMed1999

Inhibition of focus formation of transformed cloned cells by contact with non-transformed BALB/c 3T3 A31-1-1 cells.

When transformed cells were co-cultured with various densities of non-transformed BALB/c 3T3 A31-1-1 cells, the number of transformed cell foci decreased as the density of the A31-1-1 cells was increased. Under the condition of separate co-cultivation in which transformed cloned cells could not make contact with A31-1-1 cells, no inhibitory effect was induced. We examined with a dye-transfer assay the formation of heterologous gap-junctional intercellular communication (GJIC), links between the transformed cells and A31-1-1 cells before and after focus formation. Heterologous GJIC was observed almost always before, but almost never after, focus formation. Using time-lapse photography to record the fate of transformed cloned cells that did not form foci in the co-cultivation, it was noted that most of them were living, but did not proliferate. These results suggested that focus formation of transformed cloned cells was inhibited by contact with non-transformed A31-1-1 cells.

3T3 Cells↗

PubMed1999

Expression of leptin receptor in lung: leptin as a growth factor.

Leptin receptors are expressed in various tissues in rodents but their function is not clear. The present studies were undertaken to investigate the function of the leptin receptor in mouse and human lungs. Cell proliferation, assessed with [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT), was significantly less in primary cultures of tracheal epithelial cells of db/db mice than in those of their lean littermates. Mouse recombinant leptin significantly increased cell proliferation only in lean mice, but not in db/db mice. Reverse transcription-polymerase chain reaction (RT-PCR) study demonstrated the existence of a long form, OB-Rb type leptin receptor in both human lung tissue and lung squamous cell line (SQ-5). Cell proliferation, assessed with MTT, was dose-dependently increased in SQ-5 cells incubated with 10-1000 ng/ml human recombinant leptin for 6 h. The 5-bromo-2'-deoxyuridine (BrdU) uptake into SQ-5 cells was also increased by the addition of 10-100 ng/ml human recombinant leptin. Mitogen-activated protein (MAP) kinase activity was significantly increased by 10 and 100 ng/ml human recombinant leptin in SQ-5 cells. MAP kinase kinase (MEK)-1-specific inhibitor, (2-[2-amino-3-methoxyphenyl]-4H-1-benzopyran-4-one) (PD98059), blocked the increase in BrdU uptake into SQ-5 cells caused by human recombinant leptin. In conclusion, leptin (OB-Rb) receptors exist in human lung tissue and leptin may have stimulatory effects on the proliferation of cells of a human cell line and mouse tracheal epithelial cells through its specific leptin receptor.

Animals↗

PubMed1999

Expression of functional Na+/H+ antiporters of Helicobacter pylori in antiporter-deficient Escherichia coli mutants.

An open reading frame with a sequence homologous to Escherichia coli Na+/H+ antiporter A (ENhaA) was found in the total genomic sequence of Helicobacter pylori, a pathogenic bacterium of gastric inflammation, and was named HNhaA. The primary sequences and the hydropathy profiles of ENhaA and HNhaA were very homologous except for one additional region found in HNhaA. This sequence has about 40 hydrophilic amino acid residues inserted at the position next to residue 235 of ENhaA which corresponds to residue 245 of HNhaA. HNhaA was expressed in E. coli mutants deficient in Na+/H+ antiporters and complemented the salt-sensitive phenotype of the mutants. Membrane vesicles prepared from these transformants of HNhaA using mutants deficient in the antiporters had the antiporter activities. Surprisingly, the antiporter activity in the transformant membranes was high at acidic and neutral pH, while ENhaA did not function at these pHs. A hydrophilic region around residue 235 in ENhaA and the additional hydrophilic region of about 40 residues in the same region found in HNhaA might be responsible for this difference in activity by acting as putative pH sensors.

Amino Acid Sequence↗