Search PubMed⌕ Search

Biomedical subjects

T Kubota

Publications and source records attributed to T Kubota.

At least 325 records · Page 18Linked to original sources
PubMed1998

A stimulation factor for hydrolysis of ATP bound to DnaA protein, the initiator of chromosomal DNA replication in Escherichia coli.

Hydrolysis of ATP bound to DnaA protein by its intrinsic ATPase activity negatively controls chromosomal DNA replication in Escherichia coli. We developed a new in vitro assay system for ATP hydrolysis, which makes feasible a search for factors affecting the ATPase activity of DnaA protein. A crude cell extract enhanced the hydrolysis of ATP bound to DnaA protein, in a dose-dependent manner. Gel-filtration analyses revealed a single entity of the stimulation factor for the ATP hydrolysis and an apparent molecular mass of 170 kDa. The stimulation activity for ATP hydrolysis coeluted with the inactivation activity for DnaA protein initiating an oriC DNA replication, as determined by anion-exchange and gel-filtration column chromatographies. Activity of the stimulation factor required DNA and ATP. These observations suggested that IdaA protein, a previously described negative factor for DnaA protein, inactivated DnaA protein through stimulation of the hydrolysis of ATP bound to DnaA protein.

Adenosine Diphosphate↗
PubMed1998

Gene arrangement in the upstream region of Clostridium botulinum type E and Clostridium butyricum BL6340 progenitor toxin genes is different from that of other types.

The cluster of genes encoding the botulinum progenitor toxin and the upstream region including p21 and p47 were divided into three different gene arrangements (class I-III). To determine the gene similarity of the type E neurotoxin (BoNT/E) complex to other types, the gene organization in the upstream region of the nontoxic-nonhemagglutinin gene (ntnh) was investigated in chromosomal DNA from Clostridium botulinum type E strain Iwanai and C. butyricum strain BL6340. The gene cluster of type E progenitor toxin (Iwanai and BL6340) was similar to those of type F and type A (from infant botulism in Japan), but not to those of types A, B, and C. Though genes for the hemagglutinin component and P21 were not discovered, genes encoding P47, NTNH, and BoNT were found in type E strain Iwanai and C. butyricum strain BL6340. However, the genes of ORF-X1 (435 bp) and ORF-X2 (partially sequenced) were present just upstream of that of P47. The orientation of these genes was in inverted direction to that of p47. The gene cluster of type E progenitor toxin (Iwanai and BL6340) is, therefore, a specific arrangement (class IV) among the genes encoding components of the BoNT complex.

Botulinum Toxins↗
PubMed1998

Selective antitumor activity of MKT-077, a delocalized lipophilic cation, on normal cells and cancer cells in vitro.

BACKGROUND AND OBJECTIVES: 1-Ethyl-2-¿[3-ethyl-5-(3-methylbenzothiazolin-2-yliden)]-4-+ ++oxothiazolidin-2-ylidenemethyl¿pyridium chloride (MKT-077, formerly known as FJ776), a delocalized lipophilic cation, is known to accumulate in the mitochondria, according to the negative potential inside the mitochondria, and exert its cytotoxicity. METHODS: The single-cell suspensions of human cancer cell lines, human spleen cells, and fresh cancer specimens obtained from patients with gastric carcinoma were used for the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay. RESULTS: The antitumor activity of MKT-077 was dose and concentration related, and 50% inhibitory concentrations (IC50) ranged from 1.7 to 14.3 microg/ml, with a mean +/- standard deviation (SD) of 8.4 +/- 4.6 microg/ml. The IC50 of fresh surgical spleen-cell specimens ranged from 0.34 microg/ml to >100 microg/ml in a 48 h incubation, with a mean +/- SD of 66.5 +/- 37.7 microg/ml. When the antitumor activity of MKT-077 was compared between gastric cancer cells and spleen cells obtained from the same patient, the concentration-dependent antitumor activity of this agent was obvious in the cancer cells, while no significant cytotoxicity was observed in the spleen cells. The fresh surgical specimens of gastric cancer showed higher sensitivity to MKT-077 than did spleen cells at a concentration of 30 microg/ml, with a statistically significant difference at P < 0.05. CONCLUSIONS: The selective antitumor activity of MKT-077 was confirmed using fresh surgical specimens and warrants further investigation.

Antineoplastic Agents↗
PubMed1998

Antitumor spectra of anthracyclines against gastric cancer tissues obtained from surgical specimens with reference to P-glycoprotein expression.

BACKGROUND AND OBJECTIVES: Although the mechanism of P-glycoprotein (Pgp)-related resistance of doxorubicin is known, it has not been clarified for other anthracycline derivatives. We have examined the chemosensitivity of gastric cancer tissues to three anthracyclines in relation to Pgp expression. METHODS: Sixty-six surgical specimens obtained from patients with gastric cancer were subjected to histoculture drug response assay using doxorubicin (DXR), epirubicin (EPI), and 4'-O-tetrahydropyranyldoxorubicin (pirarubicin; THP). The cutoff concentrations used were 15 microg/ml for DXR and EPI and 17 microg/ml for THP. RESULTS: A 50% or more inhibition index (I.I.) was regarded as sensitive, at which the correlation rates were 95.8% (23/24) and 74.2% (49/66) for DXR-EPI and DXR-THP, respectively. Twenty-six specimens were immunohistochemically stained with monoclonal antibody to Pgp, with a positive rate of 53.8% (14/26). In Pgp-positive specimens, all cases were resistant to DXR and 28.6% (4/14) of cases were sensitive to THP, while the antitumor activity of EPI was essentially identical to that of DXR. CONCLUSIONS: The expression of Pgp might affect resistance to DXR and EPI, although THP may partially impair this resistance, suggesting the clinical usefulness of THP in treatment of DXR-refractory gastric carcinoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

End-systolic pressure-dimension relationship of in situ mouse left ventricle.

The increasing popularity of genetically engineered mice in cardiovascular research has made it important to evaluate cardiac function in small animals. We have developed a system to enable simultaneous pressure-dimension analysis of the mouse left ventricle. The chest was opened under anesthesia, and a 1.4 F micromanometer catheter was inserted into the left ventricle through the apex. A pair of sonomicrometry crystals were attached to the anterior and posterior walls using tissue adhesive. Pressure and dimension were recorded simultaneously at baseline and after isoproterenol injection (1 micro g, intraperitoneally). The ascending aorta was occluded transiently to estimate the end-systolic pressure-dimension relationship (ESPDR), which was parameterized subsequently by the quadratic equation: Pes=C2 X (Des-D0)2+E0 X (Des-D0), where Pes is end-systolic pressure, Des is end-systolic dimension, D0 is the dimension axis intercept, E0 is the local slope at D0, and C2 is the curvilinearity coefficient. The maximum and minimum external dimensions at baseline were 5.82+/-0.50 (s.d.) mm and 5.49+/-0.46 mm with fractional shortening of 0.057+/-0.014 (n=12). The ESPDR was significantly curvilinear and increased convexity after isoproterenol injection (C2, -444+/-281 to -1113+/-780 mmHg/mm2, P<0. 05; E0, 536+/-175 to 889+/-276 mmHg/mm, P<0.001), while the dimension axis intercept remained relatively constant (D0, 5.39+/-0. 46 to 5.37+/-0.52 mm). In conclusion, the combination of miniature piezo-electric crystals and a micromanometer enables continuous measurement of pressure and dimension of in situ mouse left ventricle. This technology may be useful in evaluating the cardiac phenotype of genetically engineered mice.

Animals↗
PubMed1998

Antitumor activity of paclitaxel and epirubicin in human breast carcinoma, R-27.

The antitumor effect of paclitaxel, epirubicin, and both in combination was tested using R-27, an estrogen receptor-positive human breast carcinoma. In an in vivo study using nude mice both drugs showed an additive effect, whereas they showed a supraadditive pattern in in vitro MTT assay. The combination of paclitaxel and epirubicin may enhance the antitumor effect on breast carcinoma.

Animals↗
PubMed1998

Preoperative evaluation of the chemosensitivity of breast cancer by means of double phase 99mTc-MIBI scintimammography.

The chemosensitivity of breast cancer is important for its management, but it is difficult to evaluate preoperatively. Tc-99m hexakis-2-methoxyisobutylisonitrile (MIBI) scintimammography has been reported to indicate the expression of P-glycoprotein, which is one factor concerned with multidrug resistance. We developed a chemosensitivity assay by using surgical specimens to investigate whether 99mTc-MIBI scintimammography findings before the operation are related to chemosensitivity according to our assay. Fifteen patients with primary breast cancer were enrolled into the study. Early and delayed images were obtained at 10 and 120 minutes after intravenous injection of 99mTc-MIBI, respectively. Regions of interest were placed on the tumors and the contralateral healthy breasts in each patient to estimate 99mTc-MIBI uptake in the tumor, and retention indices were then calculated to assess the washout of 99mTc-MIBI. Chemosensitivity assay was performed by incubating surgical specimens with anticancer agents such as doxorubicin, epirubicin, pinorubicin, mitomycin C, cisplatin and 5-fluorouracil. 99mTc-MIBI washout on scintimammography was successfully related to inhibition ratios on chemosensitivity tests when compared with 99mTc-MIBI uptake by the tumor. In particular, high correlation coefficients were obtained between the retention index of 99mTc-MIBI and the inhibition ratios of doxorubicin (r = 0.75), epirubicin (r = 0.60) and pinorubicin (r = 0.62), but poor correlation was found for mitomycin C (r = 0.44) and cisplatin (r = 0.31). Our results indicate that the retention index of 99mTc-MIBI is closely correlated to chemosensitivity to anthracyclines, suggesting that double-phase scintimammography allows preoperative prediction of chemosensitivity of breast cancer.

Adult↗
PubMed1998

[Surgical repair of coronary sinus type partial anomalous pulmonary venous drainage with intact atrial septum].

We experienced a rare form of PAPVD without atrial septal defect. The patient was a 33-year-old male and he was referred to our institute because of mild right pulmonary congestion detected by a routine chest X-P. Enlarged coronary sinus, right atrium and right ventricle were documented by UCG. The Qp/Qs was 1.9 and pulmonary artery pressure was 38/7 mmHg (mean: 17 mmHg) by cardiac catheterization. Selective pulmonary angiogram showed that all right pulmonary veins drained into the coronary sinus without evidence of an atrial septal defect. Enhanced chest CT clearly demonstrated the connection between the right pulmonary vein and the coronary sinus. Intracardiac repair without atrial baffle was carried out under hypothermic cardiopulmonary bypass. Under cardiac arrest with cardioplegia, the common wall between the right pulmonary vein and the left atrium was incised and the connection between the right pulmonary vein and the left atrium was established. The flap made by this incision was brought posterior to close the right pulmonary vein opening to the coronary sinus. The postoperative course was uneventful and the minimum diameter of the right pulmonary vein was found to be 15.5 mm by a postoperative pulmonary artery angiogram. This operative method without an atrial baffle could be an alternative procedure for coronary sinus type PAPVD.

Adult↗
PubMed1998

Combined toxicity of methanol and formic acid: two cases of methanol poisoning.

Two fatalities caused by methanol ingestion are presented. Quantitative analysis of methanol and formic acid using head-space gas chromatography showed concentrations of methanol and formic acid in the femoral blood of each subject of 2.19 mg/ml and 0.41 mg/ml, and 1.96 mg/ml and 0.38 mg/ml, respectively. We concluded that death was due to methanol ingestion and the mechanism causing death involved the combined effects of the anesthetic action of methanol itself and metabolic acidosis by formic acid. Forensic toxicokinetic analysis indicated that both victims had ingested about 100 g of methanol or more.

Adult↗
PubMed1998

The effects of prostaglandin E1 and tyrosine kinase inhibitors on energy status and protein synthetic ability in hepatic ischemia-reperfusion injury.

The effects of prostaglandin E1 (PGE1) and tyrosine kinase inhibitors on hepatic energy status and protein synthesis in ischemic livers were studied using 31P-magnetic resonance spectroscopy in a rat model. The continuous administration of PGE1 significantly increased the beta-adenosine triphosphate/inorganic phosphate (beta-ATP/Pi) ratio and hepatic protein synthesis rate (HPS) after ischemia-reperfusion injury. Microscopic examination showed that the continuous administration of PGE1 inhibited the development of sinusoidal hemorrhage and edema. Thus, it was concluded that PGE1 has a beneficial effect on ischemia-reperfusion injury in the liver. Pretreatment with tyrosine kinase inhibitor also increased the beta-ATP/Pi ratio; however, when tyrosine kinase inhibitor was injected before ischemia, the HPS became significantly reduced. Based on these data, the protective effect of tyrosine kinase inhibitor is unconvincing.

Alprostadil↗
PubMed1998

Production of urokinase-type plasminogen activator (u-PA) and plasminogen activator inhibitor-1 (PAI-1) in human brain tumours.

We investigated the role of plasminogen activators (PAs) and their inhibitor (plasminogen activator inhibitor-1, PAI-1) in human brain tumours. The amounts of urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor-1 (PAI-1), and the activity of u-PA and t-PA were determined by enzyme-linked immunosorbent assay (ELISA), and u-PA and PAI-1 were immunolocalized using monoclonal antibodies in human brain tumours and normal brain tissues. The tissues were surgically removed from 64 patients; normal brain tissue (5 cases), low-grade glioma (4 cases), high-grade glioma (17 cases), metastatic tumour (9 cases), meningioma (benign 12 cases, malignant 6 cases), acoustic schwannoma (11 cases). u-PA activity and u-PA and PAI-1 antigen levels were significantly elevated in malignant brain tumours (malignant meningiomas, high-grade gliomas, and metastatic tumours) and acoustic schwannomas but very low in benign meningiomas, low-grade gliomas and normal brain. There was no difference in t-PA antigen levels among normal and malignant tissues, however levels of t-PA activity were markedly decreased in metastastic tumours. All malignant brain tumour tissues showed positive immunostaining for u-PA and PAI-1, however, some tumour cells showed negative intensity while others showed strong intensity for these antibodies. This contrasts to the homogeneous staining pattern found in acoustic schwannoma. These findings indicate that malignancy in human brain tumours is associated with elevated levels of u-PA and PAI-1 and that an imbalance between these proteins in a micro-environment contributes (ascribes) to tumour cell invasion.

Adolescent↗
PubMed1998

Poor induction of interferon-induced 2',5'-oligoadenylate synthetase (2-5 AS) in cells persistently infected with mumps virus is caused by decrease of STAT-1 alpha.

Poor induction of interferon-induced 2',5'-oligoadenylate synthetase (2-5AS) has been demonstrated in cells persistently infected with mumps virus as compared with uninfected cells. As for the number of interferon (IFN) receptors and the level of IFN regulatory factors (IRF-1 and IRF-2) mRNAs, there was little difference between them. Therefore, it is suggested that the IFN-alpha signaling system is ineffective in the persistently infected cells. Components of IFN-stimulating gene factor 3 alpha (ISGF-3 alpha), STAT-1 alpha (p91) and STAT-2 (p113), were investigated in human amnion (FL), human nasopharyngeal cancer (KB), human T-lymphoid (HUT 78), and human B-lymphoid (Akata) cells persistently infected with mumps virus. STAT-1 alpha, but not STAT-2, disappeared in these persistently infected cells, and this factor was not restored by treatment of these cells with IFN. However, no difference was observed between the levels of STAT-1 alpha mRNA transcript in persistently infected and uninfected control cells. It is reasonable to infer that the poor induction of 2-5AS activity is due to the decrease of STAT-1 alpha in correlation with the IFN-signal transduction pathway. Furthermore, induction of other IFN-stimulated genes (ds-RNA activated protein kinase, PKR, and MxA protein) was also reduced in the cells persistently infected with mumps virus.

2',5'-Oligoadenylate Synthetase↗
PubMed1998

Metabolism of warfarin enantiomers in Japanese patients with heart disease having different CYP2C9 and CYP2C19 genotypes.

OBJECTIVE: To determine whether genetic polymorphism of cytochrome P450 (CYP) 2C9 affects the in vivo metabolism of warfarin enantiomers. METHODS: Eighty-six Japanese patients heart disease who were given warfarin participated in the study. Plasma unbound concentrations of warfarin enantiomers and urinary (S)-7-hydroxywarfarin concentrations were measured by means of a chiral HPLC and ultrafiltration technique to calculate the unbound oral clearance (CLpo,u) for the enantiomers and the formation clearance (CLm) for (S)-warfarin 7-hydroxylation. Genotyping for CYP2C9 (the wild type [wt], Arg144/Cys, and I1e359/Leu) and for CYP2C19 (wt, ml, and m2) was performed with a polymerase chain reaction method. RESULTS: Three patients were heterozygous for the CYP2C9 Leu359 mutation but none were homozygous for the mutation (the allele frequency of 0.017). None had a CYP2C9 Cys144 allele. The medians for (S)-warfarin CLpo,u and its 7-hydroxylation CLm obtained from heterozygotes of CYP2C9 Leu359 were significantly less than those obtained from homozygotes of the wt allele, as follows: 234 ml/min (range, 156 to 269 ml/min) versus 632 ml/min (range, 180 to 2070 ml/min) (p < 0.001) and 0.20 ml/min (range, 0.05 to 0.77 ml/min) versus 0.80 ml/min (range, 0.05 to 14.9 ml/min) (p < 0.05), respectively. In contrast, no difference was observed in (R)-warfarin CLpo,u between the groups. The allele frequencies for CYP2C19 m1 and CYP2C19 m2 were 0.26 and 0.14, respectively, indicating 15% of patients were genotypically poor metabolizers of CYP2C19. No difference in CLpo,u for warfarin enantiomers was observed between the assumed CYP2C19 phenotypes. CONCLUSION: Heterozygotes for CYP2C9 I1e359/Leu allele have reduced in vivo metabolism of (S)-warfarin but not (R)-warfarin. Because (S)-warfarin has a greater anticoagulant potency than its (R)-congener, the genetic polymorphism of CYP2C9 may partly account for the large interpatient variability in therapeutic dosages of warfarin.

Adult↗
PubMed1998

Relationship between maternal group B streptococcal colonization and pregnancy outcome.

OBJECTIVE: To examine the association of maternal colonization with group B streptococcus (GBS) with preterm labor and premature rupture of the membranes (PROM). METHODS: Vaginal cultures were conducted in 615 women at 22-26 weeks' gestation and again on admission for term delivery, preterm labor, or PROM. Antibiotics were not given antenatally based on a GBS-positive culture result. Fisher exact test and maximum likelihood analysis were used for statistical analysis. RESULTS: The rates of preterm labor and PROM were not significantly different between GBS-positive and GBS-negative women in both the antenatal screening and the screening on admission. According to maximum-likelihood analyses, the known risk factors for preterm labor and PROM collectively were important risk factors for preterm labor (odds ratio: 6.48), but GBS colonization during pregnancy was not a risk factor for preterm labor or PROM. In the antenatal screening, the proportion of subjects with lactobacilli-reduced vaginal flora was significantly higher in GBS-positive women (14.3%; ten of 70) than in GBS-negative women (6.4%; 35 of 545) (P = 0.26). Bacteria associated with bacterial vaginosis (Gardnerella vaginalis and anaerobes) were isolated in only 3.7% (23 of 615) of all subjects. CONCLUSION: Vaginal colonization with GBS was not associated with preterm labor and PROM in an obstetric population with a low incidence of bacterial vaginosis-associated bacteria, despite the presence of lactobacilli-reduced flora in GBS-positive women.

Adult↗
PubMed1998

Synovial fluid cytokines and proteinases as markers of temporomandibular joint disease.

PURPOSE: In this article, biochemical markers in the synovial fluid (SF) for detecting intraarticular inflammation and early cartilage degradation of the temporomandibular joint (TMJ) disease were examined. PATIENTS AND METHODS: SF was obtained from 25 TMJs in 22 patients with internal derangement (ID) or osteoarthritis (TMJ-OA), 15 asymptomatic TMJs in 11 normal volunteers, and 10 osteoarthritic knee joints (KNEE-OA). Cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA), and the proteinase activities were detected by enzymography. RESULTS: SF from TMJs with ID and OA showed higher (P < .05) levels (330.1 +/- 347.7 pg/100 microg SF protein) of IL-1beta than the asymptomatic control TMJs (76.7 +/- 95.3 pg/100 microg of SF protein). SF from TMJs with OA contained significantly (P < .05) higher levels of IL-1beta (531.8 +/- 379.6 pg/100 microg of SF protein) and IL-6 (979 +/- 552 pg/100 microg SF protein) than those with ID (IL-1beta: 216.7 +/- 280.1 pg, IL-6: 293 +/- 434 pg). Two matrix metalloproteinases (MMPs) with gelatinolytic activities at 92 kDa and 72 kDa were consistently detected in both the TMJ-SF (either normal or disease) and SF from KNEE-OA. Also detected were weak bands with molecular weight of 83 and 66 kDa. These bands were clearly shown, particularly in knee joints with advanced stages of OA. Western blot analysis delineated that these were active forms of MMP-9 (83 kDa) and MMP-2 (66 kDa). The same bands were also detected in TMJs with OA that showed high levels of IL-1beta and IL-6. CONCLUSION: These findings suggest that concomitant increases in the levels of cytokines (IL-1 and IL-6) and active forms of MMPs could be potential catabolic markers for cartilage degradation in the TMJ.

Adolescent↗
PubMed1998

Cloning and sequencing of BeS-1 gene encoding the immunogenic antigen of Streptococcus sanguis KTH-1 isolated from the patients with Behçet's disease.

In order to analyze the immunopathologic mechanisms of Behçet's disease, the gene (bes-1) encoding a streptococcal antigen correlated with the disease was cloned and sequenced, and protein produced by this clone was identified by Western immunoblotting using serum antibody from the patient. Cellular DNA of Streptococcus (S.) sanguis serotype KTH-1 (uncommon serotype 1, strain 113-20) from the patient was extracted and digested with EcoRI. The digested fragments were cloned into the cloning vector lambda gt11, and then the resulting DNA library was immunoscreened using the patient's serum antibody to serotype KTH-1. The immunopositive clone of the 1.5 kbp fragment was subcloned into pUC 118 plasmid (pU8BeS1-1) and sequenced. The sequence showed that the 3'-terminal half side region of this insert contained 962bp of open-reading frame (ORF) discontinued at the EcoRI restriction site, and the stop codon was not found. The nucleotide sequence of the remaining additional 3'-terminal region of this gene encoding whole BES-1 was determined by genome walking. The whole ORF of bes-1 consisted of 849 amino acid residues with a calculated molecular mass of 95 kDa. The residues in a portion of the amino acid sequence showed a 60% correspondence to those of the human intraocular peptide Brn-3b.

Amino Acid Sequence↗