Biomedical subjects

T Ueda

Publications and source records attributed to T Ueda.

At least 559 records · Page 31Linked to original sources

PubMed1996

Characterization and subcellular localization of a small GTP-binding protein (Ara-4) from Arabidopsis: conditional expression under control of the promoter of the gene for heat-shock protein HSP81-1.

Small GTP-binding proteins belonging to the rab/YPT family play key roles at various steps in intracellular transport pathways in yeast and mammalian cells. Many members of rab/YPT family have been isolated from plants to date. However, detailed information about the localization and function of the gene products remains limited, even though intracellular transport is likely to be involved in important phenomena such as cell elongation, transport of storage proteins, determination and maintenance of cell polarity and intercellular signal transduction. We have attempted to establish transgenic Arabidopsis plants that overexpress ARA-4, a rab/YPT homologue in order to analyze the function and the localization of the gene product. For overexpression and also for regulation of the expression of this gene, the promoter of the gene for HSP81-1 was employed to drive the transcription of ARA-4 in transgenic plants. The response of the introduced genes to heat shock was analyzed. Upon heat-shock treatment, the ARA-4 gene was efficiently transcribed and translated. The induction of ARA-4 by heat shock was transient, and at least two distinct forms of this protein were found in membrane and cytosolic fractions from transgenic plants. Prolonged incubation after heat shock reduced the amount of the cytosolic form of the induced protein, and the cytosolic form of the protein thus probably represents the unprocessed precursor. Using transgenic plants, we determined the subcellular localization of the product of ARA-4. The protein was predominantly localized on Golgi-derived vesicles, Golgi cisternae and the trans-Golgi network.

Arabidopsis↗

PubMed1996

Replication patterns of repetitive DNA sequences on the W chromosome are altered during development of the chick embryo.

A novel method was developed to study developmental changes in the replication pattern of repetitive DNA sequences on the W chromosome (W-DNA) of the female chick embryo. The amount of total nuclear DNA and W-DNA as well as 5-bromodeoxyuridine (BrdU) incorporation was successively measured on the same cells using multiparametric microfluorometry. With this method we first examined the possibility of changes in replication patterns of W-DNA during development. Measurements were conducted on various heterogeneous cell populations obtained from whole embryo on Day 0.4 and Day 1, and from pectoral muscle, neural tube, liver, and oogonium on Day 9. Parameters of W-DNA replication, duration, and timing were found to vary according to the stage of embryonic development. Developmental features of these changes were further studied on specific cell types during their critical developmental processes. In scutate scale dermis, the W-DNA replication duration showed a characteristic lengthening from around 0.45C during Day 5 through Day 7.4 to 0.9C during Day 7.7 through Day 7.9 and shortening to 0.37C during Day 8.1 through Day 12. Transient lengthening in W-DNA replication duration was also observed in erythrocytes; 0.65C ->1.0C ->0.6C during Day 0.9 through Day 2.17. Timing also shifted earlier in accord with changes in the duration. Replication rate of whole genome DNA was monitored by measuring BrdU incorporation on respective cells and found, to a large extent, comparable to that of W-DNA. The data suggest that a link might be operative between replication patterns of genes and the developmental program.

Animals↗

PubMed1996

A new method for identifying the amino acid attached to a particular RNA in the cell.

To investigate the function of tRNAs or any other aminoacylable RNAs in vivo, it is important to be able to estimate the amounts and species of aminoacylated RNAs in living cells. We have developed a method of analyzing amino acids attached to particular tRNAs obtained from cells. After the ester bond between the amino acid and the 3'-adenosine moiety of a specific aminoacyl-tRNA is stabilized by acetylation of the amino acid with [14C]acetic anhydride, the aminoacyl-tRNA can be fished out with a solid-phase-attached DNA probe. The 14C-labeled acetylamino acid is then released from the thus purified acetyl-aminoacyl-tRNAs by alkaline treatment and detected by TLC analysis.

Acetic Anhydrides↗

PubMed1996

Allelic losses at loci on chromosome 10 are associated with metastasis and progression of human prostate cancer.

DNA samples from tumors and paired normal tissues from 48 patients with prostate cancer (stage B, 16 cases; stage C, 14 cases; stage D, 18 cases) were examined with 26 polymorphic markers spanning chromosome 10. Allelic losses were observed in 17 of the 46 cases (37%) that were informative with at least one of the markers. Detailed deletion mapping identified two distict commonly deleted regions on the long arm of chromosome 10 (10q22-q24:7 cM and 10q25.1:17 cM) and one on 10p, suggesting that at least three tumor suppressor genes associated with prostate cancer are present on this chromosome. We observed loss of heterozygosity more frequently in tumors from fatal cases (stage D, 8/16, 50%) than in localized tumors (stage B, 0/16, 0%; P = 0.001 or stage B + C, 5/30, 17%; P = 0.02 Fisher's exact test). All metastatic tissues showed allelic loss at one or more loci on 10q. In five of the nine patients from whom DNAs were available from both metastatic and primary tumors, the primary cancer foci had no detectable abnormality of chromosome 10, while the metastatic foci showed allelic loss on chromosome 10. These results suggested that inactivation of one or more tumor suppressor genes on chromosome 10 plays an important role in late stages of prostate cancer.

Adenocarcinoma↗

PubMed1996

Distribution of immunoreactive 2',5'-oligoadenylate synthetase in mouse reproductive organs.

Although 2', 5'-oligoadenylate synthetase (2-5AS) is an enzyme induced by inferferon (IFN) or viral infections and mediates one of the principal antiviral pathways turned on by IFN, low constitutive levels of the enzyme can be detected in various "normal" animals that have not been treated with IFN or virus. The distribution of this enzyme in the female and male reproductive organs of normal healthy mice was studied by Western blotting and by an immunohistochemical method, using a specific monoclonal antibody. On Western blotting, an antibody to 42-kD 2-5AS reacted with extracts from the ovary, oviduct, uterus, vagina, and placenta among the female reproductive organs, and testis, epididymis, and ductus deferens in the male. Immunohistochemically, the 2-5AS was localized on the following cells in the female reproductive organs: oocytes in the ovary; epithelium in the oviduct, uterus, and vagina; and trophoblasts in the placenta. Furthermore, the 2-5AS was localized on the epithelium and muscular layer in the ductus deferens and epithelium in the penis of the male mice, whereas the epithelium of the testis, epididymis, and seminal vesicle were stained faintly. It is well known that IFN is produced continuously in normal mice, so the 2-5AS in the tissues of normal mice is considered to be induced by such IFN produced under physiological conditions. Expression of the 2-5AS on the epithelium and trophoblasts in the reproductive organs may be responsible for the prevention of viral infections. However, the enzyme in oocytes may have some functions other than as an antiviral agent, since the enzyme was not detectable in embryos during early development.

2',5'-Oligoadenylate Synthetase↗

PubMed1996

Tracheal lipoma obstructing the right main bronchus: report of a case.

Most tracheal tumors are malignant, and benign neoplasms are extremely rare. We herein report the case of a 60-year-old woman with a tracheal lipoma obstructing the right main bronchus in whom a preoperative diagnosis was not able to be established. Thus, a thoracotomy was performed followed by complete resection of the tumor including two rings of the tracheal wall. Pathologic examination confirmed that the tumor was a lipoma covered with tracheal epithelium, extending between the cartilage into the outer layer of the trachea.

Bronchial Diseases↗

PubMed1996

Resected acinar cell carcinoma of the pancreas with tumor thrombus extending into the main portal vein: report of a case.

The incidence of acinar cell carcinoma has been reported to be about 1% of all pancreatic neoplasms, and pancreatic cancer combined with tumor growth extending into the portal vein is a rare condition. We herein report a case of acinar cell carcinoma of the pancreas with a tumor thrombus extending into the main portal trunk. Preoperative imaging of the portal vein, consisting of computed tomography (CT), magnetic resonance imaging (MRI), and angiography, revealed an oval shadow defect in the main portal trunk along with an irregular mass in the pancreatic head. At operation, we confirmed a tumor thrombus extending from a tumor in the pancreatic head into the main portal trunk via the pancreatoduodenal veins. A pancreatoduodenectomy combined with partial resection of the portal vein was thus performed under a temporary portal vein shunt from the ileocecal vein to the umbilical vein. Immunohistochemical examination for alpha 1-antichimotrypsin and electron microscopic examination confirmed the diagnosis of acinar cell carcinoma of the pancreas with a tumor thrombus in the portal vein. Surgical excision combined with portal vein resection may therefore improve the prognosis of selected patients with portal tumor thrombus.

Carcinoma, Acinar Cell↗

PubMed1996

Possible involvement of Rab11 p24, a Ras-like small GTP-binding protein, in intracellular vesicular transport of isolated pancreatic acini.

Rab11 p24 is a Ras-like small guanosine triphosphate (GTP)-binding protein, and specific antibodies against it were newly developed to explore its function. Using the antibody, Rab11 p24 was shown to be abundant in rat pancreas as well as in most rat tissues. To explore the involvement of Rab11 p24 into the exocytotic process, the subcellular distribution of Rab11 p24 in rat pancreatic acini was evaluated also by use of the antibody. When the isolated acini were incubated with 1 x 10(-10) M cholecystokinin octapeptide (CCK-8) that induced the maximal stimulation, the amount of Rab11 p24 increased in the fractions of plasma membrane and zymogen granules, but decreased in the cytosol fraction. This redistribution was time-dependent and occurred within 1 min after the CCK-8 stimulation and reached a maximal level within 2 min after the stimulation. Moreover, a light microscopic immunolabeling technique on the isolated rat pancreatic acini also revealed that higher immunoreactivity with Rab11 p24 was observed over the zymogen granule membrane under CCK-8 stimulation. The present results indicate that Rab11 p24 is translocated from cytosol to the membrane fraction during stimulation with CCK-8 and suggest that Rab11 p24 is involved in the intracellular vesicular transport of isolated acini.

Animals↗

PubMed1996

The effect of methylprednisolone on platinum kinetics and urinary enzyme excretion following intravenous cisplatin in vivo and on the growth inhibition of LLC-PK1 cells by cisplatin in vitro.

In order to evaluate the mechanism of the protective action of methylprednisolone against cisplatin-induced nephrotoxicity, platinum kinetics and urinary enzyme excretion following intravenous cisplatin, with or without methylprednisolone, were studied in vivo. The growth inhibition of LLC-PK1 cells by cisplatin in the presence or absence of methylprednisolone was studied in vitro. Rats intravenously injected with cisplatin combined with subcutaneous methylprednisolone 4 h prior to the cisplatin injection excreted more platinum in urine than rats treated with cisplatin alone. Both plasma and kidney platinum concentrations in rats injected with both cisplatin and methylprednisolone were significantly lower than those in rats given cisplatin alone at 4 h after cisplatin injection. However, there was no significant difference in urinary excretion of lactate dehydrogenase, gamma-glutamyl transpeptidase or N-acetyl-beta-D-glucosaminidase between methylprednisolone-treated rats and control rats. Methylprednisolone did not affect the inhibitory effects of cisplatin on the cell growth of LLC-PK1. These findings indicate that methylprednisolone-induced increase in urinary platinum excretion, accompanied by a decrease in plasma and kidney platinum concentrations following cisplatin injection in rats, may be one of the mechanisms responsible for the protective action of methylprednisolone.

Acetylglucosaminidase↗

PubMed1996

Skip metastasis to the mediastinal lymph nodes in non-small cell lung cancer.

BACKGROUND: Whether any difference exists in clinical characteristics between resected non-small cell lung cancer with either skip or ordinary mediastinal lymph node metastases (N2 disease) needs to be clarified. METHODS: There were 110 patients with stage IIIA N2 disease. Thirty-three patients demonstrating no metastasis at the hilar nodes [skip (+) group] were compared with the other 77 patients [skip (-) group]. To investigate the extent of nodal involvement, we classified the mediastinal lymph nodes into three regions (superior, inferior, or aortic). RESULTS: There were no significant differences regarding histologic type, T status, or the site of the primary tumors between the skip (+) and the skip (-) N2 groups. In the skip (+) group, mediastinal node metastasis was found in only one region (level 1) in 30 patients (90.9%) and in two regions (level 2) in 3 (9.1%), whereas 28 patients (36.4%) from the skip (-) group revealed mediastinal metastasis at two or three regions (level 2 or 3). The overall survival rate at 5 years after operation was 35% in the skip (+) group and 12.7% in the skip (-) group (p = 0.054). This favorable clinical outcome in the skip (+) group could be explained partially by the higher proportion of patients with level 1 metastases. Furthermore, regarding patients with level 1 disease, the skip (+) group tended to have a better prognosis than the skip (-) group (p = 0.096). CONCLUSIONS: These results suggest that patients with skip mediastinal lymph node metastases represent a unique subgroup of N2 disease.

Carcinoma, Non-Small-Cell Lung↗

PubMed1996

Reduced immunogenicity of monomethoxypolyethylene glycol-modified lysozyme for activation of T cells.

Chemical modification of proteins with monomethoxypolyethylene glycol (mPEG) will reduce the immunogenicity of proteins. In the present study, we evaluated the effect of mPEG modification on the capacity of hen egg-white lysozyme (HEL) to stimulate T cells. Lymph node cells (LNCs) from mice immunized with HEL or with mPEG-HEL conjugate were cultured with these antigens, then we measured the proliferation and IL-2 production. mPEG-modification lowered the T cell activating capacity of HEL, both in vitro and in vivo. Neither toxicity, nor antigen non-specific immunosuppressive capacity was observed with mPEG-HEL and unconjugated mPEG. Suppressor cells were unlikely to be generated in the mPEG-HEL-primed LNCs. We next examined the behavior of mPEG-HEL during antigen processing. The capacity of HEL and mPEG-HEL to be incorporated by live cells was much the same. However, the susceptibility to various proteases, including endosomal/lysosomal enzymes, was significantly decreased by mPEG modification. The increased resistance of mPEG-HEL to proteolytic degradation implied that the conjugate was poorly presented to T cells. This may be an important factor related to the low immunogenicity of mPEG modified proteins.

Animals↗

PubMed1996

Cardiac energy metabolism at several stages of adriamycin-induced heart failure in rats.

To evaluate the changes in myocardial energy metabolism in the progressively failing myocardium, we measured myocardial level of adenosine triphosphate (ATP) using high-performance liquid chromatography (HPLC), and levels of lactate, alanine and free carnitine using 1H-nuclear magnetic resonance (NMR) spectroscopy in rats injected with adriamycin. The drug was injected intraperitoneally 2.5 mg/kg 6 times over a period of 2 weeks. Measurements were obtained 1 day (1 d), 3 weeks (3 w) and 6 weeks (6 w) after the last injection. No deaths were observed until the end of the 3rd week. The cumulative mortality rate 6 weeks after the last injection was 48%. ATP and free carnitine levels were not significantly changed at 1 d, while myocardial lactate was increased by 33% from the control values (P < 0.05). Lactate levels were reduced significantly, but not progressively, at 3 w (31% of control values) and at 6 w (69% of control values). Similar changes were observed in alanine levels. Free carnitine levels were progressively decreased at 3 w (74% of control values) and at 6 w (57% of control values). Changes in ATP levels paralleled those of free carnitine. Data suggest that a decrease in the myocardial level of free carnitine may be involved in progression of the heart failure induced by adriamycin in rats.

Adenosine Triphosphate↗

PubMed1996

Structural feature of the initiator tRNA gene from Pyrodictium occultum and the thermal stability of its gene product, tRNA(imet).

Pyrodictium occultum is a hyperthermophilic archaeum that grows optimally at 105 degrees C. To study how tRNA molecules in P occulrum are thermally stabilized, we isolated the initiator tRNA gene from the organism using a synthetic DNA probe of 74 bp containing the known nucleotide sequences that are conserved in archaeal initiator tRNAs. A HindIII fragment of 700 bp containing the Pyrodictium initiator tRNA gene was cloned and sequenced by cycle sequencing. The nucleotide sequence revealed that the Pyrodictium initiator tRNA gene has no introns, and that the 3'CCA terminus is encoded. The tRNA gene also contained a unique TATA-like sequence, AAGCTTATAA, which is likely the promoter proposed for archaeal rRNA genes, 450 bp upstream of the 5' end of the tRNA coding region. In the region adjacent to the 3' end of the tRNA coding region, there was a sig G-C base pair inverted repeat followed by a C-rich sequence like the p-independent transcription termination signal of bacterial genes. The Pyrodictium initiator tRNA sequence predicted from the gene sequence contained all of the nucleotide residues A1, A37, U54, A57, U60, and U72, in addition to three G-C base pairs in the anticodon stem region, which are characteristic of archaeal initiator tRNAs. The melting temperature (Tm) of the unmodified initiator tRNA synthesized in vitro using the cloned tRNA gene as a template was 80 degrees C, which is only two degrees lower than that calculated from the G-C content in the stem regions of the tRNA. In contrast, the Tm of the natural initiator tRNA isolated from P occultum was over 100 degrees C. Analysis of digests of purified Pyrodictium initiator tRNA by means of HPLC-mass spectrometry and [32P] post-labeling, indicated that the tRNA contains a variety of modified nucleosides. These results suggest that the extraordinarily high melting temperature of P occultum tRNA(Met)i is due to posttranscriptional modification.

Archaea↗

PubMed1996

Two nucleotides 5'-adjacent to the anticodon of rat cytoplasmic tRNA(Asp) are not edited.

Cytoplasmic tRNA(Asp) of rat liver was purified by the solid-phase hybridization method and its nucleotide sequence was analyzed by Donis-Keller's method. The results suggested that the two nucleotides next to the anticodon were identical to its gene sequence, a finding that is inconsistent with a previous report demonstrating by several methods that C32 and T33 on the tRNA(Asp) gene are post-transcriptionally converted to U32 and C33, respectively (Beier et al (1992) Nucleic Acids Res 20, 2679-2683). Our results indicate that the tRNA hybridized to an oligonucleotide, designed on the basis of the tRNA(Asp) gene sequence, undergoes no editing and possesses C32 and U33 as predicted from the DNA sequence. Analysis of cDNA synthesized from the purified tRNA(Asp) by the RT-PCR method supported the finding that RNA editing is not involved in the maturation process of rat cytoplasmic tRNA(Asp).

Adenosine Triphosphate↗

PubMed1996

Relation between severity of magnesium deficiency and frequency of anginal attacks in men with variant angina.

OBJECTIVES: We evaluated whether the severity of magnesium deficiency was correlated with the frequency of attacks of variant angina. BACKGROUND: Magnesium deficiency may be associated with the development of variant angina. However, the relation between the activity of variant angina and magnesium deficiency remains to be elucidated. METHODS: We assessed the body magnesium status of 18 men with variant angina: Group 1 (> or = 4 attacks/week, n = 7) and Group 2 (< 4 attacks/week, n = 11). Concentrations of magnesium were determined in serum, urine, mononuclear cells and erythrocytes, and the 24-h magnesium retention rate was determined. RESULTS: Group 1 showed a higher 24-h magnesium retention rate (mean +/- SEM 63.5 +/- 7.6% vs. 24.9 +/- 2.7%, p < 0.01) and a lower intracellular concentration of magnesium in mononuclear cells and erythrocytes than did Group 2 (respectively, 156.3 +/- 13.5 vs. 212.1 +/- 6.9 fg/cell, p < 0.01; and 3.5 +/- 0.5 vs. 5.2 +/- 0.4 fg/cell, p < 0.05), demonstrating the presence of magnesium deficiency in Group 1. The 24-h magnesium retention rate and intracellular concentrations of magnesium in mononuclear cells and erythrocytes correlated well with the frequency of anginal attacks (r = 0.78, p < 0.01; r = -0.78, p < 0.01; r = -0.62, p < 0.01, respectively) for all patients. CONCLUSIONS: Data suggest that the magnesium status of men with variant angina is closely related to disease activity.

Aged↗

PubMed1996

Long-term 1-carnitine treatment prolongs the survival in rats with adriamycin-induced heart failure.

BACKGROUND: The most serious consequence of heart failure is the shortened life expectancy, which may be associated with myocardial energy starvation. METHODS AND RESULTS: Eight-week-old male Sprague-Dawley rats received 6 intraperitoneal injections of adriamycin (group A: total dose; 15 mg/kg body weight) or vehicle (group C) over 2 weeks. Rats then received either 272 mg/kg daily of oral 1-carnitine (A-LC and C-LC groups) or saline (A-S and C-S groups) for 6 weeks. The cumulative mortality rate in the A-LC group was significantly lower than in the A-S group (13 vs 42%, P = .028). Myocardial levels of high-energy phosphate compounds (ATP and creatine phosphate) and fatty acid metabolites (free carnitine, short-chain and long-chain acylcarnitine, and long-chain acyl CoA) in the left ventricle were measured the day after the last dose of drug or vehicle was administered. ATP was decreased by 73%, creatine phosphate by 61%, free carnitine by 52%, short-chain acylcarnitine by 48%, and long-chain acylcarnitine by 56% in the A-S group compared to the C-S group. Long-chain CoA was increased by 168% in the A-S group. Levels of myocardial high-energy phosphate compounds and fatty acid metabolites were near normal in adriamycin- and 1-carnitine-treated rats. CONCLUSIONS: Preservation of the myocardial level of carnitine by 1-carnitine treatment prolonged survival of rats with adriamycin-induced failure by improving the myocardial metabolism of fatty acids.

Acyl Coenzyme A↗

PubMed1996

Protective effect of dipyridamole against lethality and lipid peroxidation in liver and spleen of the ddY mouse after whole-body irradiation.

The effects of dipyridamole on radiation damage in the mouse were investigated. Dipyridamole (i.p. 2 mg/mouse) administered 1 h before exposure, protected against gamma-irradiation. Pretreatment significantly decreased the death rate at 30 days from 89 to 33% (p<0.001) after 9 Gy whole-body irradiation. LD50 at 30 days was increased from 6.67 to 7.65 Gy in the dipyridamole pretreated group. The level of thiobarbituric acid reactive substances (TBARS) in the liver and spleen, a measure of free radical initiated liver peroxidation, increased 155, 193, 195, and 236% of control (without irradiation) in liver, and 132, 146, 168, and 276% of control (without irradiation) in spleen on days 2, 4, 7, and 10 after 9 Gy of whole-body irradiation respectively. The TBARS levels in both liver and spleen 2 days after irradiation were reduced to 73 +/- 7 and 60 +/- 19% respectively after dipyridamole treatment (2 mg/mouse, i.p. injection 1 h before exposure). In electron microscopic studies, mitochondria and endoplasmic reticulum in the irradiated mouse liver were swollen, but otherwise appeared normal after dipyridamole treatment. These results suggest that dipyridamole has a protective effect on animal survival 30 days after 60Co gamma-irradiation and inhibits lipid peroxidation - which is thought to play a part in the radiation injury in mouse liver and spleen.

Animals↗

PubMed1996

Nitric oxide concentrations in the follicular fluid and apoptosis of granulosa cells in human follicles.

To study the relationship between follicular atresia, apoptosis, and nitric oxide (NO) generation in follicular development, steroidogenesis, NO levels in follicular fluid and apoptosis were analysed in the various sized follicles of women receiving ovarian stimulation with human menopausal gonadotrophin (HMG)-human chorionic gonadotrophin (HCG) treatments for in-vitro fertilization (IVF)-embryo transfer. The follicles were divided into three groups by diameter: large follicle, > or = 18 mm; medium follicle, > or = 12 and < or = 15 mm; small follicle, < or = 10 mm. Follicular fluid was obtained from 20 women 34 h after HCG administration, and the concentrations of oestradiol, progesterone and testosterone, and nitrite, nitrate, arginine and citrulline were measured. Granulosa cells obtained from each group of follicular fluid were stained with Hoechst dye, and nuclear morphology was examined by a fluorescence microscopy. Oestradiol and progesterone concentrations in large follicles were significantly (P < 0.01) higher than those in medium or small follicles, and testosterone concentrations in small follicles were significantly (P < 0.01) higher than those in large follicles. There were no significant differences in the concentrations of nitrite, nitrate, arginine and citrulline among three groups. The percentage of apoptotic cells with nuclear fragmentation was significantly (P < 0.01) higher in small follicles than in large follicles. The present results suggested that small follicles with poor response to HMG may undergo atresia through apoptosis. No significant difference in the follicular NO level between large and small follicles led us to speculate on a different responsiveness to NO in these two types of follicles.

Adult↗