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Biomedical subjects

T Yano

Publications and source records attributed to T Yano.

At least 181 records · Page 10Linked to original sources
PubMed1999

H(+)-translocating NADH-quinone oxidoreductase (NDH-1) of Paracoccus denitrificans. Studies on topology and stoichiometry of the peripheral subunits.

The proton-translocating NADH-quinone oxidoreductase (NDH-1) of Paracoccus denitrificans is composed of at least 14 subunits (NQO1-14) and is located in the cytoplasmic membrane. In the present study, topological properties and stoichiometry of the 7 subunits (NQO1-6 and NQO9) of the P. denitrificans NDH-1 in the membranes were investigated using immunological techniques. Treatments with chaotropic reagents (urea, NaI, or NaBr) or with alkaline buffer (pH 10-12) resulted in partial or complete extraction of all the subunits from the membranes. Of interest is that when NaBr or urea were used, the NQO6 and NQO9 subunits remained in the membranes, whereas the other subunits were completely extracted, suggesting their direct association with the membrane part of the enzyme complex. Both deletion study and homologous expression study of the NQO9 subunit provided a clue that its hydrophobic N-terminal stretch plays an important role in such an association. In light of this observation and others, topological properties of the subunits in the NDH-1 enzyme complex are discussed. In addition, determination of stoichiometry of the peripheral subunits of the P. denitrificans NDH-1 was completed by radioimmunological methods. All the peripheral subunits are present as one molecule each in the enzyme complex. These results estimated the total number of cofactors in the P. denitrificans NDH-1; the enzyme complex contains one molecule of FMN and up to eight iron-sulfur clusters, 2x[2Fe-2S] and 6x[4Fe-4S], provided that the NQO6 subunit bears one [4Fe-4S] cluster.

Base Sequence↗
PubMed1999

Effects of isoflurane and hexafluorodiethyl ether on human recombinant GABA(A) receptors expressed in Sf9 cells.

Effects of volatile anesthetics and a volatile convulsant on human recombinant gamma-aminobutyric acid (GABA) type A receptor responses were studied using the whole cell configuration of the patch clamp technique. Sf9 cells were transfected with bacuroviruses carrying cDNAs of alpha1beta2, alpha1beta2gamma2s, alpha3beta2 and alpha3beta2gamma2s subunit combinations of the human GABA(A) receptor. Clinical concentrations of isoflurane (a volatile anesthetic) enhanced the GABA-induced current of the alpha1beta2gamma2s and alpha3beta2gamma2s GABA(A) subunit combinations. On the other hand, isoflurane suppressed the current of the alpha1beta2 and alpha3beta2 subunit combinations, indicating that the anesthetic effects depended upon the presence of gamma2s subunit. A high concentration (2 mM) of isoflurane generated a surge current following the washout of GABA and the anesthetic. Hexafluorodiethyl ether (a volatile convulsant) decreased the GABA-response of the both alpha3beta2gamma2s and alpha3beta2 constructs without generating a surge current. The results suggest that volatile agents affect the receptor-ionophore complex via direct interaction with proteins but not through a perturbation of the membrane lipid environment. A hypothetical sequential model for the anesthetic action is presented.

Anesthetics, Inhalation↗
PubMed1999

Nucleotide sequences of genes for ribosomal protein L41 and tRNAThr(AGU) from Coprinus cinereus.

The nucleotide sequences of genes for the homolog in Coprinus cinereus of the eukaryotic ribosomal protein L41 and for tRNAThr(AGU) are reported. The gene for tRNAThr(AGU) was located upstream of the gene for the L41 ribosomal protein, and these genes were adjacent to each other but in opposite orientations. The deduced amino acid sequence of ribosomal protein L41 exhibited strong homology to those of L41 proteins of several yeasts. The 56th amino acid of the deduced protein was proline, as it is in the L41 protein of a cycloheximide-sensitive strain of yeast. The putative secondary structure of the tRNA gene resembled the characteristic cloverleaf structure of tRNAs. Elements resembling an A-box and a B-box were found in the gene for tRNAThr(AGU). These boxes are known as internal promoter elements in genes for eukaryotic tRNAs.

Amino Acid Sequence↗
PubMed1999

Positron emission tomography in juvenile Alexander disease.

A 13-year-old boy with cervical kyphosis was diagnosed as having juvenile Alexander disease because of the typical MRI findings, abnormally elevated alphaB-crystallin and heat shock protein 27 in the cerebrospinal fluid. Positron emission tomography with 18F-fluorodeoxyglucose demonstrated hypometabolism in the frontal white matter corresponding to the areas with leukodystrophy. However, the overlying gray matter preserved normal glucose metabolism.

Adolescent↗
PubMed1999

NADH-quinone oxidoreductase: PSST subunit couples electron transfer from iron-sulfur cluster N2 to quinone.

The proton-translocating NADH-quinone oxidoreductase (EC 1.6.99.3) is the largest and least understood enzyme complex of the respiratory chain. The mammalian mitochondrial enzyme (also called complex I) contains more than 40 subunits, whereas its structurally simpler bacterial counterpart (NDH-1) in Paracoccus denitrificans and Thermus thermophilus HB-8 consists of 14 subunits. A major unsolved question is the location and mechanism of the terminal electron transfer step from iron-sulfur cluster N2 to quinone. Potent inhibitors acting at this key region are candidate photoaffinity probes to dissect NADH-quinone oxidoreductases. Complex I and NDH-1 are very sensitive to inhibition by a variety of structurally diverse toxicants, including rotenone, piericidin A, bullatacin, and pyridaben. We designed (trifluoromethyl)diazirinyl[3H]pyridaben ([3H]TDP) as our photoaffinity ligand because it combines outstanding inhibitor potency, a suitable photoreactive group, and tritium at high specific activity. Photoaffinity labeling of mitochondrial electron transport particles was specific and saturable. Isolation, protein sequencing, and immunoprecipitation identified the high-affinity specifically labeled 23-kDa subunit as PSST of complex I. Immunoprecipitation of labeled membranes of P. denitrificans and T. thermophilus established photoaffinity labeling of the equivalent bacterial NQO6. Competitive binding and enzyme inhibition studies showed that photoaffinity labeling of the specific high-affinity binding site of PSST is exceptionally sensitive to each of the high-potency inhibitors mentioned above. These findings establish that the homologous PSST of mitochondria and NQO6 of bacteria have a conserved inhibitor-binding site and that this subunit plays a key role in electron transfer by functionally coupling iron-sulfur cluster N2 to quinone.

Azirines↗
PubMed1999

Redesigning the substrate specificity of an enzyme by cumulative effects of the mutations of non-active site residues.

Directed evolution was used to change the substrate specificity of aspartate aminotransferase. A mutant enzyme with 17 amino acid substitutions was generated that shows a 2.1 x 10(6)-fold increase in the catalytic efficiency (kcat/Km) for a non-native substrate, valine. The absorption spectrum of the bound coenzyme, pyridoxal 5'-phosphate, is also changed significantly by the mutations. Interestingly, only one of the 17 residues appears to be able to contact the substrate, and none of them interact with the coenzyme. The three-dimensional structure of the mutant enzyme complexed with a valine analog, isovalerate (determined to 2.4-A resolution by x-ray crystallography), provides insights into how the mutations affect substrate binding. The active site is remodeled; the subunit interface is altered, and the enzyme domain that encloses the substrate is shifted by the mutations. The present results demonstrate clearly the importance of the cumulative effects of residues remote from the active site and represent a new line of approach to the redesign of enzyme activity.

Amino Acid Sequence↗
PubMed1999

Extracellular signal-regulated kinase mediates renal regeneration in rats with myoglobinuric acute renal injury.

In vitro data support that extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), members of mitogen-activated protein (MAP) kinases, mediate the signal transduction pathways responsible for the cell proliferation. However, in vivo role of these MAP kinases is poorly understood. Intramuscular injection of 50% glycerol solution induces acute renal failure in rats. This injury is known as a model of rhabdomyolysis in human. To investigate the molecular mechanism of the signaling pathway in this injury, we examined the role of ERK and JNK. After the glycerol injection JNK was rapidly and transiently activated at about 4 h, while the activation of ERK was gradually increased and the levels were sustained at least to 24 h. Next, we examined the expression of cell-cycle related proteins after the glycerol injection using Western blot analysis. The levels of proliferating cell nuclear antigen (PCNA) protein as a marker for cell proliferation were induced at 2 h and significantly increased to 24 h after the injection. In addition, cyclins D1, D2, and D3 as markers for G1 phase also increased with similar time courses. To examine whether activation of ERK and/or JNK are involved in the renal regeneration after the glycerol injection, we examined the effect of genistein, which is an inhibitor of tyrosine kinase, on the activation of ERK and JNK. Administration of genistein to rats with this injury decreased the activation of ERK, but not JNK. The induction of PCNA and cyclin D1 was also prevented by this treatment. In this condition, renal function was further worsened as compared to control rats. These results provide the first evidence that ERK may be involved in the repair process of renal tubules damaged by this injury.

Animals↗
PubMed1999

Washout rate of 123I-metaiodobenzylguanidine increased by posture change or exercise in normal volunteers.

123I-metaiodobenzylguanidine (MIBG) imaging detects sympathetic nerve function in the heart. The present study was conducted to clarify whether posture change or exercise affects 123I-MIBG kinetics in normal volunteers. Seven subjects underwent three 123I-MIBG studies, i.e., supine protocol, sitting protocol and exercise protocol. Planar 123I-MIBG images were obtained at 15 minutes, 1 hour and 4 hours after injection of 123I-MIBG. The washout rate (WR) from 15 minutes to 1 hour in the supine position in all subjects was similar for all three protocols, whereas the WR from 1 hour to 4 hours was significantly augmented in the sitting protocol and the exercise protocol as compared to the supine protocol (p < 0.05 and p < 0.01). The serum concentration of noradrenaline was significantly increased from the baseline to the 4 hour sampling in the sitting protocol and the exercise protocol (both p < 0.01), but was not altered in the supine protocol. The WR from 1 hour to 4 hours significantly correlated with the noradrenaline concentration in 4 hour sampling (r = 0.59, p < 0.01). It also significantly correlated with an increase in the noradrenaline concentration from the baseline to the 4 hour sampling (r = 0.53, p < 0.05). It is concluded that posture change or exercise affects the WR of 123I-MIBG in normal healthy subjects.

3-Iodobenzylguanidine↗
PubMed1999

Regulation of methionine adenosyltransferase activity by the glutathione level in rat liver during ischemia-reperfusion.

Hepatic ischemia was induced by clamping the hepatic artery, portal vein, and bile duct. After 15 min of ischemia, the hepatic glutathione (GSH) content rapidly decreased. On the other hand, after the start of reperfusion, the hepatic GSH levels promptly increased and reached a peak at about 1 h, and thereafter decreased to a minimum level by 2 h. Under such conditions, we examined the changes in the methionine adenosyltransferase (MAT) activity in the liver. Though the time course of MAT activity was somewhat delayed compared with that of the hepatic GSH levels, both patterns were substantially similar during ischemia-reperfusion. In contrast to the changes in the MAT activity during ischemia-reperfusion, the levels of MAT protein were unchanged during these periods. When endogenous antioxidant coenzyme Q(10) (CoQ(10)) was administered to rats prior to ischemia, both the reduction in the MAT activity and hepatic GSH levels induced by ischemia-reperfusion were protected. Our findings suggest that CoQ(10) may posttranslationally regulate the MAT activity via the changes in the GSH level in the liver.

Animals↗
PubMed1999

Serum levels of parathyroid hormone-related protein are not elevated in patients with T-cell prolymphocytic leukemia.

T-cell prolymphocytic leukemia (T-PLL) is a rare post-thymic T-cell neoplasm which shares most clinical features with adult T-cell leukemia (ATL). We measured serum level of C-terminal parathyroid hormone-related protein (C-PTHrP) in patients with T-PLL and ATL. Serum C-PTHrP levels of eight patients with T-PLL (median 36.8 pmol/l; range 27.0-50.2 pmol/l) did not differ from those of 30 human T-lymphotropic virus type I (HTLV-I)-seronegative blood donors (median 37.0 pmol/l; range 22.6-54.0 pmol/l). The C-PTHrP levels in ten ATL patients (median 69.6 pmol/l; range 42.5-899.4 pmol/l) were significantly higher than those in healthy controls (p<0.0001) or T-PLL patients (p=0.001). We suggest that the serum level of PTHrP can provide useful information for differentiating between T-PLL and ATL.

Adult↗
PubMed1999

A case of recurrent hepatocellular carcinoma treated with laparoscopic microwave coagulation therapy after minimally invasive hepatic surgery.

A case of hepatocellular carcinoma (HCC) in which the patient repeatedly underwent minimally invasive hepatic procedures is reported. The patient was a 71-year-old man who underwent transthoracic microwave coagulation therapy (MCT) for initial HCC nodules in segment VIII and subsequent laparoscopic MCT for small intrahepatic recurrent nodules in the left hepatic lobe. At this writing, the patient was alive and well without tumor recurrence 29 months after the initial surgery. Minimally invasive hepatic surgery alleviates perihepatic adhesion and allows subsequent laparoscopic surgery in the case of intrahepatic HCC recurrence.

Aged↗
PubMed1999

Inhibition of human endometrial cancer cell growth in vitro and in vivo by somatostatin analog RC-160.

OBJECTIVE: Our purpose was to investigate the effect of the somatostatin analog RC-160 on the growth of the HEC-1 human endometrial cancer cell line in vivo and in vitro. STUDY DESIGN: Nude mice bearing subcutaneous implanted HEC-1 tumors were treated for 25 days with RC-160 (100 microgram/d) delivered by osmotic minipumps. In cultured HEC-1 cells radioreceptor assay of somatostatin was performed, and the expression of messenger ribonucleic acid for somatostatin receptor subtypes (somatostatin receptors 1-5) was analyzed by reverse transcription-polymerase chain reaction. The effects of RC-160 on epidermal growth factor-stimulated cell proliferation and tyrosine phosphorylation of epidermal growth factor receptor were examined by colorimetric assay and Western blotting, respectively. RESULTS: The treatment with RC-160 resulted in a significant decrease in tumor volume, tumor weight, and serum insulin-like growth factor I levels compared with those values in control animals. The presence of high-affinity somatostatin binding sites and the expression of somatostatin receptor 2 and somatostatin receptor 3 messenger ribonucleic acid were demonstrated in HEC-1 cells by radioreceptor assay and reverse transcription-polymerase chain reaction, respectively. Epidermal growth factor-stimulated proliferation of HEC-1 cells was inhibited by RC-160 in a dose-dependent manner. Western blotting revealed that epidermal growth factor-induced tyrosine phosphorylation of epidermal growth factor receptor was inhibited by RC-160, which suggests that the direct inhibitory effect of RC-160 on HEC-1 cell growth might be mediated in part by interference with epidermal growth factor receptor phosphorylation. CONCLUSION: These results indicate that somatostatin analog RC-160 inhibits the growth of HEC-1 human endometrial cancer cells, thus implying its potential clinical utility in treating endometrial cancer.

Animals↗
PubMed1999

Activation of extracellular signal-regulated kinase in lung tissues of mice treated with carcinogen.

The activation of extracellular signal-regulated kinase (ERK) in lung tissues of mice, as determined by the appearance of phosphorylated form, was observed on day 30 after urethane injection, and the activation also occurred in urethane-induced lung tumors. Immunohistochemical analysis using anti-phosphorylated ERK antibody indicated that the active form of ERK localized in alveolar epithelial cells. Furthermore, we confirmed by immunoprecipitation and immunoblot analysis that other essential components of the ERK cascade, that is, Ras, Raf and MEK (known as ERK kinase) were activated. These results indicate that the activation of the ERK signal in alveolar epithelial cells at the early stage of urethane-induced lung carcinogenesis is an important factor to develop lung tumors.

Animals↗
PubMed1999

Postoperative adjuvant adoptive immunotherapy with lymph node-LAK cells and IL-2 for pathologic stage I non-small cell lung cancer.

We conducted a clinical trial of adoptive immunotherapy with lymph node-lymphokine-activated killer (LN-LAK) cells and recombinant interleukin 2 (rIL-2) for a surgical adjuvant therapy of pathologic stage I non-small cell lung cancer. The regimen consisted of the subcutaneous administration of low-dose rIL-2 for 6 consecutive days and the transfer of ex vivo generated LAK cells from regional lymph node lymphocytes, obtained at the time of surgical operation. A group of 19 patients with primary lung cancer received the immunotherapy about 2 weeks after surgery (pulmonary lobectomy). The regimen was postoperatively well tolerated by the patients. In peripheral blood lymphocytes (PBL) obtained after the treatment, the proportion of CD3+ T cells predominantly increased with the increase of CD4+ T cell subsets. On the other hand, the proportion of CD20+ B cells decreased. Both NK and LAK activity of PBL significantly increased. However, the immunomodulatory effects did not result in a prolongation of the postoperative survival time in comparison to the postoperative survival of patients (n = 21) with surgery alone during the same period. These results suggested that the treatment with low-dose LN-LAK cells and concurrent low-dose IL-2 could, therefore, neither reduce nor eradicate minimal micrometastatic diseases.

Aged↗
PubMed1999

SSPE following neonatal measles infection.

The authors report a case of subacute sclerosing panencephalitis in a child who had measles during the neonatal period. At 3 years, 6 months of age, over a period of a few weeks, the patient lost the ability to sit unaided as a result of progressive truncal ataxia, without apparent cognitive changes, simulating acute cerebellar ataxia. His symptoms improved in 1 month, and he was able to walk again with support, but mental alteration and periodic mild head nodding on awakening followed. His illness was diagnosed as subacute sclerosing panencephalitis on the basis of the elevated titers of measles antibodies in the cerebrospinal fluid. Measles infection before 1 year of age is a risk factor of subacute sclerosing panencephalitis, but reports about patients with neonatal measles infection are rare. Immaturity of the brain at the time of measles infection may not only be a risk factor but may also influence the clinical course of the disease.

Age of Onset↗
PubMed1999

Rapid measurement and control of the moisture content of compost using near-infrared spectroscopy.

In a compost fermentation of soybean-curd (tofu) refuse, the effects of the moisture content of the compost on the compost reaction were studied. The moisture content of the compost was a very important factor for good fermentation. Near-infrared spectroscopy (NIRS) was applied to the determination of the moisture content of the compost. The reflected rays in the wavelength range between 400 and 2500 nm were measured at 2 nm intervals. The absorption of water was observed at three wavelengths, 960, 1406 and 1888 nm. To formulate a calibration equation, a multiple linear regression analysis was carried out between the near-infrared spectral data at 960 nm (sample number, n = 50) and on the moisture content obtained using a drying method. The values of the simple correlation coefficient and the standard error of calibration were 0.987 and 1.33%, respectively. To validate the calibration equation obtained, the moisture content in the prediction sample set (n = 35) not used for formulating the calibration equation was calculated using the calibration equation, and compared with the values obtained using the drying method. Good agreement was observed between the results of the drying method and those of the NIRS method. The simple correlation coefficient and standard error of prediction were 0.979 and 1.85%, respectively. Then, the NIRS method was applied to a practical situation in which the moisture content was measured and controlled during the compost fermentation, and good results were obtained. The study indicates that NIRS is a useful method for measurement and control of the moisture content in the compost of soybean-curd refuse.

Journal Article↗