Search PubMed⌕ Search

Biomedical subjects

T Tamura

Publications and source records attributed to T Tamura.

At least 181 records · Page 10Linked to original sources
PubMed2000

Maternal plasma zinc concentrations and pregnancy outcome.

BACKGROUND: There is no consensus in the literature as to whether maternal zinc nutriture is associated with pregnancy outcome or fetal growth. OBJECTIVE: We evaluated the associations between plasma zinc concentrations during pregnancy and various measures of pregnancy outcome and neonatal conditions at birth. DESIGN: We measured zinc concentrations in plasma samples obtained at a mean of 16 wk of gestation (range: 6-34 wk) from 3448 women who were screened for a trial designed to evaluate the effect of zinc supplementation on fetal growth. Subjects were from low socioeconomic backgrounds and attended a public health clinic for their prenatal care. Plasma zinc concentrations were compared with pregnancy outcome, including complications during pregnancy and delivery, and anthropometric measures and Apgar scores of neonates. RESULTS: Plasma zinc concentrations declined as gestation progressed. After plasma zinc concentrations were adjusted for gestational age, they were not significantly associated with any measure of pregnancy outcome or neonatal condition. CONCLUSION: We conclude that plasma zinc concentrations during the late first trimester to the early third trimester do not predict pregnancy outcomes in women of a low socioeconomic background.

Adult↗
PubMed2000

Molecular mechanism of the impairment in activation signal transduction in CD4(+) T cells from old mice.

It is well known that IL-2 production of CD4(+) T cells from old mice (old T cells) is impaired. In this study, we have examined TCR complex zeta chain expression of old T cells and their TCR downstream signal transduction pathways stimulated with anti-CD3. Activation of protein tyrosine kinases, Fyn and ZAP-70, and turnover of inositol phosphates stimulated with anti-CD3 were severely impaired in old T cells, although levels of these proteins were comparable to those in young T cells. Increase in intracellular Ca2+ concentration in old T cells was also impaired. Old T cells starting the Ca(2+) oscillation by the anti-CD3 stimulation were severely decreased in number and the oscillation waves were broader in shape. T cells with zeta-FcvarepsilonRgamma heterodimer in the TCR-CD3 complex were increased in proportion in old T cells with a concomitant decrease in the T cells with zeta-zeta homodimer. The density of the TCR-CD3 complex on old T cells was confirmed to be comparable to that on young T cells. The impairment in TCR downstream signal transduction pathways and the increase in zeta-FcvarepsilonRgamma heterodimer in the TCR-CD3 complex were confirmed to be the situation in Th1 clones established from old mice. These results indicate that old T cells are impaired in response to TCR stimulation, because T cells with the TCR-CD3 complex containing the zeta-FcvarepsilonRgamma heterodimer are increased in proportion in old T cells.

Aging↗
PubMed2000

Pharmacokinetic and pharmacodynamic analysis of bis-acetato-ammine-dichloro-cyclohexylamine-platinum(IV) (JM216) administered once a day for five consecutive days: a phase I study.

BACKGROUND: Bis-acetato-ammine-dichloro-cyclohexylamine-platinum(IV) (JM216) is the first orally given platinum complex that shows in vitro cytotoxicity comparable to that of cisplatin and in vivo cytotoxicity superior to those of cisplatin and carboplatin. METHODS: We conducted an escalating-dose (50, 75, 100, 120 mg/m2) phase I study of JM216 administered orally once a day for five consecutive days in patients with solid tumors to establish the toxicity profile, maximum tolerated dose (MTD) and pharmacokinetic profile. Twenty-three patients were enrolled and all were assessable for toxicity. RESULTS: The MTD was 120 mg/m2/day and the dose-limiting toxicities were leukopenia, thrombocytopenia, anemia and diarrhea. Because of the delayed hematological toxicities, it was difficult to repeat cycles every 26 days in some patients. Tumor shrinkage was observed in two patients with breast cancer, both of whom were resistant to doxorubicin. A pharmacokinetic study showed that the areas under the concentration-time curve (AUC) and peak plasma concentrations (Cmax) for total platinum (Pt) on days 1 and 5 and ultrafiltered Pt (UF-Pt) on day 1 increased in proportion to the dose of JM216. The AUCs for both total and UF-Pt on day 5 were higher than the AUCs on day 1. The AUC for UF-Pt on day 5 showed the best correlation with percentage reduction in leukocyte count and in absolute neutrophil count. CONCLUSION: The recommended dose for phase II studies is 100 mg/m2/day every 4-6 weeks. The observation of tumor shrinkage in previously heavily treated breast cancer patients supports a phase II investigation.

Administration, Oral↗
PubMed2000

Bacterial meningitis observed in a phase I trial of vinorelbine, cisplatin and thoracic radiotherapy for non-small cell lung cancer: report of a case and discussion on dose-limiting toxicity.

Although neutropenia increases the risk of life-threatening infections, bacterial meningitis is rarely encountered as a complication during cancer chemotherapy in adults with a solid tumor. A 66-year-old male with adenosquamous carcinoma of the lung, cT2N3M0, stage IIIB, was enrolled in a phase I trial of chemoradiotherapy and treated with cisplatin 80 mg/m2 (122 mg/ body) on day 1, vinorelbine 20 mg/m2 (32 mg/body) on days 1 and 8 and thoracic radiotherapy 30 Gy/15 fractions, beginning on day 2, with dexamethasone administered for antiemesis at a dose of 16 mg on day 1, 8 mg on days 2 and 3, 4 mg on day 4 and 2 mg on day 5. The patient developed headache and fever on day 6 of the second cycle of the treatment and bacterial meningitis was diagnosed based on the findings of consciousness disturbance, an elevated peripheral blood leukocyte count and numerous leukocytes in the cerebrospinal fluid. In spite of the doctor's delay in establishing the exact diagnosis, the bacterial meningitis in this case was successfully treated with intensive antibiotic therapy. This life-threatening complication, equivalent to a grade 4 non-hematological adverse reaction, was not counted as dose-limiting toxicity in the current phase I trial, because there are only a few reports of bacterial meningitis associated with cancer chemotherapy and it developed in this case without any associated decrease in the peripheral blood leukocyte count.

Aged↗
PubMed2000

Platinum-based chemotherapy with or without thoracic radiation therapy in patients with unresectable thymic carcinoma.

BACKGROUND: Thymic carcinoma is a rare mediastinal neoplasm with poor prognosis. Although the clinical benefit of chemotherapy for thymic carcinoma is controversial, cisplatin-based chemotherapy with or without radiation therapy is ordinarily adopted in advanced cases. We evaluated the clinical outcome of platinum-based chemotherapy with or without radiation therapy in unresectable thymic carcinoma patients. METHODS: Ten patients with unresectable thymic carcinoma were treated with platinum-based chemotherapy with or without radiation therapy in the National Cancer Center Hospital between 1989 and 1998. We reviewed the histological type, treatment, response and survival of these patients. RESULTS: Four of the 10 patients responded to chemotherapy and both the median progression-free survival period and the median response duration were 6.0 months. The median survival time was 11.0 months. There was no relationship between histological classification and prognosis. CONCLUSIONS: Platinum-based chemotherapy with or without thoracic radiation is, regardless of tumor histology, marginally effective in advanced thymic carcinoma patients, giving only a modest tumor response rate and short response duration and survival.

Adult↗
PubMed2000

Phase I study of a weekly infusion of irinotecan hydrochloride (CPT-11) and a 14-day continuous infusion of etoposide in patients with lung cancer: JCOG trial 9408.

BACKGROUND: The aim was to determine the maximum tolerated dose (MTD) and recommended dose of irinotecan hydrochloride (CPT-11) in combination with a 14-day continuous infusion of etoposide in patients with refractory advanced lung cancer (LC), especially small cell lung cancer (SCLC). METHODS: Etoposide was administered continuously at 25 mg/m2/day for 14 days. The initial dose of CPT-11 was 40 mg/m2 given as a 90 min intravenous infusion on days 1, 8 and 15 and the dose escalation of CPT-11 was planned in increments of 20 mg/m2 until severe or life-threatening toxic effects were observed. RESULTS: Nine refractory or advanced LC patients (eight at level 1, one at level 2) were entered in this study, of whom two at level 1 were not assessable for toxicity because of patient's refusal and progressive disease. One treatment-related death due to pulmonary toxicity and one patient with hypotension who needed catecholamine for more than 48 h were observed at level 1, a CPT-11 dose of 40 mg/m2. The MTD of CPT-11 was 40 mg/m2. Therapeutic efficacy could be assessed in seven patients, of whom two achieved a partial response. CONCLUSIONS: This regimen was too toxic and the recommended dose was outside the levels in this study. One has to consider pulmonary toxicity when using CPT-11, especially for patients previously treated with cytotoxic agents for which pulmonary toxicity has been reported.

Adenocarcinoma↗
PubMed2000

Two-terpyridine.Cu(II) complexes-containing antisense systems for rapid and highly site-specific RNA cleavage.

In an approach toward artificial ribonucleases, novel RNA cleaving systems were constructed that contained two terpyridine.Cu(II) residues. The first antisense system used tandem Cu(II) complex--2'-O-methyloligonucleotide 5'- and 3'-conjugates to cleave an RNA substrate. The second system, which will be described in a future paper, contained two contiguous Cu(II) complex residues at an internal site of a 2'-O-methyloligonucleotide. We found that the first system rapidly cleaved RNA with high site-specificity. Based on these results, we expect the second system to also show efficient RNA cleavage.

Base Sequence↗
PubMed2000

Crystal structure of the pyridoxal 5'-phosphate dependent L-methionine gamma-lyase from Pseudomonas putida.

L-Methionine gamma-lyase (MGL) catalyzes the pyridoxal 5'-phosphate (PLP) dependent alpha,gamma-elimination of L-methionine. We have determined two crystal structures of MGL from Pseudomonas putida using MAD (multiwavelength anomalous diffraction) and molecular replacement methods. The structures have been refined to an R-factor of 21.1% at 2.0 and 1.7 A resolution using synchrotron radiation diffraction data. A homotetramer with 222 symmetry is built up by non-crystallographic symmetry. Two monomers associate to build the active dimer. The spatial fold of subunits, with three functionally distinct domains and their quarternary arrangement, is similar to those of L-cystathionine beta-lyase and L-cystathionine gamma-synthase from Escherichia coli.

Amino Acid Sequence↗
PubMed2000

Purification and characterization of cytochrome c-553 from Helicobacter pylori.

Helicobacter pylori, a microaerophilic Gram-negative spiral bacterium residing in the human stomach, contains a small size soluble cytochrome c. This cytochrome c was purified from the soluble fraction of H. pylori by conventional chromatographies involving octyl-cellulose and CM-Toyopearl. Its reduced form gave an alpha absorption band at 553 nm, and thus the cytochrome was named H. pylori cytochrome c-553. The cytochrome, giving a band below 10,000 Da upon SDS-PAGE, was determined to have a mass of 8,998 by time of flight mass spectroscopy. Its N-terminal peptide sequence was TDVKALAKS---, indicating that the nascent polypeptide was cleaved to produce a signal peptide of 19 amino acid residues and a mature protein composed of 77 amino acid residues. The cb-type cytochrome c oxidase oxidized ferrocytochrome c-553 of this bacterium actively (V(max) of about 250 s(-1)) with a small K(m) (0.9 microM). Analysis of the effect of the salt concentration on the oxidase activity indicated that oxidation of cytochrome c-553 is highly inhibited under high ionic conditions. The amino acid sequence of H. pylori cytochrome c-553 showed the closest similarity to that of Desulfovibrio vulgaris cytochrome c-553, and these sequences showed a weak relationship to that of the cytochrome c(8)-group among class I cytochromes c.

Amino Acid Sequence↗
PubMed2000

Modifying effects of ethinylestradiol but not methoxychlor on N-ethyl-N-nitrosourea-induced uterine carcinogenesis in heterozygous p53-deficient CBA mice.

It is unknown whether endocrine-disrupting chemicals (EDCs) with estrogenic activities have any modifying effects on uterine carcinogenesis. In our previous study, we established a uterine-carcinogenesis model that is useful for detecting tumor-modifying effects of EDCs by the administration of N-ethyl-N-nitrosourea (ENU) to female heterozygous p53-deficient CBA mice [p53 (+/-) mice]. To investigate the effects of ethinylestradiol (EE) and methoxychlor (MXC) on development of ENU-induced uterine tumors, female p53 (+/-) mice and their wild-type littermates [p53 (+/+) mice] received an intraperitoneal injection of 120 mg/kg body weight (bw) of ENU, followed, in Group 1, by no further treatment; in Group 2, by a diet containing 1 ppm EE; in Group 3, by a diet containing 5 ppm EE for 4 weeks and 2.5 ppm EE thereafter; and in Group 4, by a diet containing 2000 ppm MXC for 26 weeks. Uterine proliferative lesions that were induced were composed of both endometrial-stromal and epithelial-cell types. Endometrial stromal sarcomas were induced in p53 (+/-) mice of Groups 1 to 4, and the incidence (87%) in Group 3 was significantly increased compared to Group 1 (47%). Atypical hyperplasias (clear-cell type) of the endometrial gland in p53 (+/-) mice were seen at incidences of 0, 14, 60, and 0% in Groups 1, 2, 3, and 4, respectively, while their incidence in p53 (+/+) mice was 0, 7, 53, and 0%, respectively, with a significant difference between Groups 1 and 3 in both cases. One p53 (+/-) mouse in Group 3 also had an adenocarcinoma consisting of clear cells, and the PCNA labeling indices of the clear-cell atypical hyperplasias, and this endometrial adenocarcinoma, were higher than those of glandular hyperplasias. The present study suggests that 2.5 ppm EE, but not MXC, exerts tumor-promoting effects on stromal and epithelial proliferative lesions of the uteri in p53 (+/-) mice initiated with ENU.

Adenocarcinoma, Clear Cell↗
PubMed2000

Intrageneric relationships among Micromonospora species deduced from gyrB-based phylogeny and DNA relatedness.

The phylogenetic structure of genus Micromonospora within actinomycetes was examined by analysing the gyrB sequences of 15 validly described species and four subspecies. All but one of the Micromonospora strains formed a tight cluster, as had previously been demonstrated by a 16S rDNA-based phylogenetic analysis. However, the intrageneric relationships deduced from the gyrB-based phylogeny were different from those based on their 16S rDNA sequences. To examine which phylogeny would be more relevant for classifying genus Micromonospora, DNA-DNA hybridization experiments were performed. The gyrB-based classification agrees with the results of the DNA-DNA hybridization studies, indicating that this classification method is useful for analysing the phylogenetic relationships of high G+C Gram-positive bacteria at the level of the genomic species. Genus Micromonospora was reclassified into the following 14 species: Micromonospora echinospora, Micromonospora pallida, Micromonospora nigra, Micromonospora purpureochromogenes, Micromonospora aurantiaca, Micromonospora carbonacea, Micromonospora chalcea, Micromonospora chersina, Micromonospora coerulea, Micromonospora gallica, Micromonospora halophytica, Micromonospora inositola, Micromonospora olivasterospora and Micromonospora rosaria.

DNA Gyrase↗
PubMed2000

Acrocarpospora gen. nov., a new genus of the order Actinomycetales.

The taxonomic position of two actinomycete strains isolated from soil was studied. The isolates contained glutamic acid, alanine and meso-diaminopimelic acid as cell-wall amino acids and menaquinone MK-9(H4) and madurose in the whole-cell hydrolysate. Phylogenetic analysis revealed that the isolates belonged to the family Streptosporangiaceae, but not to any known genus, and formed a monophyletic cluster with Streptosporangium corrugatum. On the basis of morphological characteristics, phylogenetic analysis and DNA-DNA hybridization, the name Acrocarpospora gen. nov. is proposed for a new genus containing the isolates and Streptosporangium corrugatum, and Acrocarpospora pleiomorpha sp. nov. R-31T (= IFO 16267T), Acrocarpospora macrocephala sp. nov. R-55T (=IFO 16266T) and Acrocarpospora corrugata comb. nov. IFO 13972T are described.

Actinomycetales↗
PubMed2000

Actinoalloteichus cyanogriseus gen. nov., sp. nov.

Phylogenetic analysis of 'Actinoalloteichus cyanogriseus' based on its 16S rDNA sequence confirmed that the organism belongs to the family Pseudonocardiaceae. It contains glutamic acid, alanine and meso-diaminopimelic acid as cell wall amino acids, and menaquinone 9 (H4). Its taxonomic characteristics differ from those of the previously described organisms of the family Pseudonocardiaceae. On the basis of these morphological, physiological, chemotaxonomic and phylogenetic analyses, a new genus, Actinoalloteichus, is proposed, along with a new species, namely Actinoalloteichus cyanogriseus sp. nov. The type strain is A. cyanogriseus IFO 14455T (= AS 4.1159T = JCM 6095T).

Alanine↗
PubMed2000

Footprint-based personal recognition.

This paper proposes a new method of personal recognition based on footprints. In this method, an input pair of raw footprints is normalized, both in direction and in position for robustness image-matching between the input pair of footprints and the pair of registered footprints. In addition to the Euclidean distance between them, the geometric information of the input footprint is used prior to the normalization, i.e., directional and positional information. In the experiment, the pressure distribution of the footprint was measured with a pressure-sensing mat. Ten volunteers contributed footprints for testing the proposed method. The recognition rate was 30.45% without any normalization (i.e., raw image), and 85.00% with our method.

Biomedical Engineering↗
PubMed2000

Preliminary study of continuous glucose monitoring with a microdialysis technique and a null method--a numerical analysis.

Monitoring of the subcutaneous tissue glucose concentration is an attractive method for continuous monitoring of the glucose concentration in diabetic patients. Several researchers have studied this, but no satisfactory method has been developed. We have proposed a new method, which can measure the glucose concentration of subcutaneous tissue continuously, even as the efficiency of membrane perfusion and sensor performance decline. Two reference solutions were prepared with concentrations higher and lower than the objective solution. They were perfused alternately for different ratios of perfusion times. The glucose concentration, after perfusing microdialysis, was detected and the trend of changes in the concentration was used to control the ratio of the two perfusion solutions. When the trend was a unity, the glucose concentration was calculated from the ratio of the two perfusion solutions. The numerical study was performed with a compartment model and a basic control theory. In simulation, the 90% response time to step change was approximately 7 min, which is fast enough when compared with the fluctuation of glucose in the electrolyte. This result suggested that this new system might be useful for continuous monitoring of the glucose concentration in subcutaneous tissue.

Biosensing Techniques↗
PubMed2000

Attenuation of hyperoxia-induced growth inhibition in H441 cells by gene transfer of mitochondrially targeted glutathione reductase.

Reactive oxygen species (ROS) are implicated as agents of cellular damage in pulmonary oxygen toxicity. Glutathione (GSH) and GSH-dependent antioxidant enzymes protect against damage by ROS, and recycling of glutathione disulfide (GSSG) to GSH by glutathione reductase (GR) is essential for the optimum functioning of this system. Exposure to hyperoxia inhibits lung development in newborn animals and humans, and attenuates cell growth in proliferating cell cultures. Considerable evidence supports a role for ROS as growth-altering molecules. Previously, we have observed that gene transfer of GR to mitochondria in H441 cells, using a vector containing a mitochondrial leader sequence (LGR), protected these cells against t-BuOOH-induced cytotoxicity. The present studies tested the hypothesis that gene transfer of LGR would attenuate the cytostatic effects of hyperoxia exposure in H441 cells. H441 cells (0.9 x 10(6) cells/plate) transfected with adenovirus containing LGR or the complementary DNA (cDNA) for manganese superoxide dismutase in reverse orientation (DOS) as a control construct, and untransfected cells (CON) were maintained in 21% oxygen (normoxia) or 95% oxygen (hyperoxia) for 48 h, and cell growth was assessed by cell counts and by reduction of the tetrazolium dye 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to formazan. Cells maintained in normoxia achieved normal growth (CON, 1.98; DOS, 1.91; LGR, 2.0 x 10(6) cells/plate). Hyperoxia inhibited cell growth and the reduction of MTT; however, cells transfected with LGR had greater mitochondrial GR activities (CON, 16+/-2; DOS, 19+/-3; LGR, 322+/-18 mU/mg of protein), sustained more normal growth patterns (CON, 1.25+/-0.12; DOS, 1.24 +/-0.21, LGR, 1.8+/-0.25 x 10(6) cells/plate), and had less inhibition of MTT reduction (CON, 29; DOS, 27; LGR, 16% inhibition, P<0.01) after exposure to hyperoxia for 48 h than was observed in cells transfected with DOS or in control cells not infected with virus. In addition, resistant cells had higher mitochondrial GSH levels and maintained mitochondrial GSH/GSSG ratios in hyperoxia, suggesting that maintaining mitochondrial GSH homeostasis determined critical aspects of cell division in these studies. The mechanisms for sustaining cell growth during hyperoxia in H441 cells with enhanced mitochondrial GR activities are unknown, but similar effects in infants exposed to supplemental oxygen could be highly beneficial.

Adenoviridae↗