PubMed Health⌕ Search

Biomedical subjects

Masaki Yamada

Publications and source records attributed to Masaki Yamada.

11 recordsLinked to original sources
PubMed2007

alpha-ketoglutaric semialdehyde dehydrogenase isozymes involved in metabolic pathways of D-glucarate, D-galactarate, and hydroxy-L-proline. Molecular and metabolic convergent evolution.

Azospirillum brasilense possesses an alternative pathway of l-arabinose metabolism in which alpha-ketoglutaric semialdehyde (alphaKGSA) dehydrogenase (KGSADH) is involved in the last step, the conversion of alphaKGSA to alpha-ketoglutarate. In the preceding studies, we identified a set of metabolic genes of the l-arabinose pathway including the KGSADH gene (Watanabe, S., Kodaki, T., and Makino, K. (2006) J. Biol. Chem. 281, 2612-2623; Watanabe, S., Kodaki, T., and Makino, K. (2006) J. Biol. Chem. 281, 28876-28888; Watanabe, S., Shimada, N., Tajima, K., Kodaki, T., and Makino, K. (2006) J. Biol. Chem. 281, 33521-33536). Here, we describe that A. brasilense possesses two different KGSADH isozymes from l-arabinose-related enzyme (KGSADH-I); that is, d-glucarate/d-galactarate-inducible KGSADH-II and hydroxy-l-proline-inducible KGSADH-III. They were purified homogeneously from A. brasilense cells grown on d-galactarate or hydroxy-l-proline, respectively. When compared with KGSADH-I, amino acid sequences of KGSADH-II and KGSADH-III were significantly similar but not totally identical. Physiological characterization using recombinant enzymes revealed that KGSADH-II and KGSADH-III showed similar high substrate specificity for alphaKGSA and different coenzyme specificity; that is, NAD(+)-dependent KGSADH-II and NADP(+)-dependent KGSADH-III. In the phylogenetic tree of the aldehyde dehydrogenase (ALDH) superfamily, KGSADH-II and KGSADH-III were poorly related to the known ALDH subclasses including KGSADH-I. On the other hand, ALDH-like ycbD protein involved in d-glucarate/d-galactarate operon from Bacillus subtilis is closely related to the methylmalonyl semialdehyde dehydrogenase subclass but not A. brasilense KGSADH isozymes. To estimate the correct function, the corresponding gene was expressed, purified, and characterized. Kinetic analysis revealed the physiological role as NADP(+)-dependent KGSADH. We conclude that three different types of KGSADH appeared in the bacterial evolutional stage convergently. Furthermore, even the same pathway such as l-arabinose and d-glucarate/d-galactarate metabolism also evolved by the independent involvement of KGSADH.

Aldehyde Oxidoreductases↗
PubMed2006

Phosphoproteomic profiling of human SH-SY5Y neuroblastoma cells during response to 6-hydroxydopamine-induced oxidative stress.

Dopaminergic neurons are known to be vulnerable to age-related neuronal disorders due to reactive oxygen species (ROS) generated during dopamine metabolism. However, it remains unclear what kinds of proteins are involved in the response to oxidative stress. We examined changes in whole proteins and phosphoproteins in the human dopaminergic neuroblastoma cell line SH-SY5Y under oxidative stress induced by the dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA). Proteins of SH-SY5Y cells at various stages of oxidative stress were separated by two-dimensional gel electrophoresis for comparative analysis. Increase in glutathione-S-transferase pi was detected on SYPRO Ruby-stained gels by computer-aided image analysis. Stress-induced alterations in phosphoproteins were detected by Pro-Q Diamond staining. Elongation factor 2, lamin A/C, T-complex protein 1, and heterogeneous nuclear ribonucleoprotein H3 were identified by MALDI-TOF mass spectrometry as stress-responsive elements.

Blotting, Western↗
PubMed2006

Convenient structural analysis of glycosphingolipids using MALDI-QIT-TOF mass spectrometry with increased laser power and cooling gas flow.

Matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS) was applied to the structural characterization of neutral glycosphingolipids. Lithium adduct ions of glycosphingolipids were analyzed using MALDI-QIT-TOF MS under strong conditions of increased laser power and cooling gas flow. The relative intensities of fragment ions were increased under the strong conditions, and the resulting spectra revealed the presence of oligosaccharide ions fragmented from the glycosphingolipids. Consequently, the oligosaccharide sequences of the glycosphingolipids were readily obtained. To obtain more detailed structural information, MS/MS (MS2) and MS/MS/MS (MS3) analyses were performed with selection of the lactosylceramide and ceramide ions, respectively. The resulting data were sufficient to determine the structures of both the oligosaccharide and the ceramide moiety of each glycosphingolipid. The fragmentation patterns of MS2 and MS3 for Forssman glycolipid under the strong conditions were comparable to those of MS3 and MS4 obtained under standard conditions, respectively. Thus, MALDI-QIT-TOF MS with increased laser power and cooling gas flow is a convenient method for glycosphingolipid analysis.

Carbohydrate Sequence↗
PubMed2005

Impact of orotate phosphoribosyl transferase activity as a predictor of lymph node metastasis in gastric cancer.

Orotate phosphoribosyl transferase (OPRT) is an essential nucleotide metabolic enzyme for cell proliferation and also a key enzyme for conversion of 5-FU to its active form in tumor tissue. The association between tumor OPRT activity and pathophysiological status, including lymph node metastasis [pN+], and the impact of OPRT for predicting pN+ were investigated in gastric cancer. The lymph node status of 73 resectable gastric cancer patients was analyzed preoperatively by computed tomography (CT), ultrasonography and magnetic resonance, and the OPRT activity of collected tumor tissue was measured. Then these data were compared with pathological observation of a surgical lymph node specimen. OPRT activity in the tumor tissue decreased as the depth of invasion increased. An OPRT test demonstrated superior sensitivity and comparable accuracy and sensitivity for predicting pN+, against current imaging diagnoses. Furthermore, the analysis of node negative patients by CT revealed that 80% of false negative patients were retrieved by this OPRT test. Thus, OPRT activity in tumor tissue was a powerful predictor of pN+ in resectable gastric cancer, and the preoperative OPRT test, when it becomes possible, would provide a basis for accurate evaluation of disease status, which is indispensable for the planning of personalized therapy.

Aged↗
PubMed2003

Nitration of 2'-deoxyguanosine by a NO/O2 gas mixture: identification and characterization of N2-nitro-2'-deoxyguanosine.

[reaction: see text] A gas mixture of NO and O(2) was bubbled into 2'-deoxyguanosine solution at neutral pH and 37 degrees C. A novel nitrated nucleoside was generated in the reaction mixture in addition to 8-nitroguanine, 8-nitroxanthine, 2'-deoxyxanthosine, xanthine, and guanine. The novel nucleoside was identified as N(2)-nitro-2'-deoxyguanosine by spectrometric data.

Deoxyguanosine↗
PubMed2003

[Anesthetic management for infected abdominal aneurysm].

A 48-year-old man was scheduled for repair of mycotic abdominal aortic aneurysm. Extraanatomic bypass was performed due to infection of the aneurysm. General anesthesia combined with continuous epidural anesthesia was performed. In spite of severe blood loss, hemodynamic state was stable during anesthesia and postoperative period. He was managed in the intensive care unit without any complication. In this anesthetic management, it is very important to maintain adequate cardiac output and circulating blood volume to prevent visceral ischemia.

Anesthesia, Epidural↗
PubMed2003

[Retroperitoneal emphysema during total hip replacement].

A 55-year-old woman with rheumatic arthritis was scheduled for total hip replacement. The procedure was performed under combined spinal and epidural anesthesia. Intraoperatively, the part of acetabular roof was cracked by reaming the region but she did not complain of any symptom. However, during pulse irrigation she complained of abdominal pain. After the operation, abdominal distension was noticed and retroperitoneal emphysema was disclosed. She was managed in a ward without problems postoperatively.

Anesthesia, Epidural↗
PubMed2002

Novel repair activities of AlkA (3-methyladenine DNA glycosylase II) and endonuclease VIII for xanthine and oxanine, guanine lesions induced by nitric oxide and nitrous acid.

Nitrosation of guanine in DNA by nitrogen oxides such as nitric oxide (NO) and nitrous acid leads to formation of xanthine (Xan) and oxanine (Oxa), potentially cytotoxic and mutagenic lesions. In the present study, we have examined the repair capacity of DNA N-glycosylases from Escherichia coli for Xan and Oxa. The nicking assay with the defined substrates containing Xan and Oxa revealed that AlkA [in combination with endonuclease (Endo) IV] and Endo VIII recognized Xan in the tested enzymes. The activity (V(max)/K(m)) of AlkA for Xan was 5-fold lower than that for 7-methylguanine, and that of Endo VIII was 50-fold lower than that for thymine glycol. The activity of AlkA and Endo VIII for Xan was further substantiated by the release of [(3)H]Xan from the substrate. The treatment of E.coli with N-methyl-N'-nitro-N-nitrosoguanidine increased the Xan-excising activity in the cell extract from alkA(+) but not alkA(-) strains. The alkA and nei (the Endo VIII gene) double mutant, but not the single mutants, exhibited increased sensitivity to nitrous acid relative to the wild type strain. AlkA and Endo VIII also exhibited excision activity for Oxa, but the activity was much lower than that for Xan.

DNA Glycosylases↗
PubMed2002

External control of Her2 expression and cancer cell growth by targeting a Ras-linked coactivator.

Overproduction of the Her2 oncoprotein has been found in approximately 30% of breast tumors, and patients who have Her2 excesses typically have more aggressive disease. Here we show that the expression of the Her2 gene can be decreased by inhibiting the interaction of the two cancer-linked proteins, DRIP130/CRSP130/Sur-2 (a Ras-linked subunit of human mediator complexes) and ESX (an epithelial-restricted transcription factor). Disruption of the interaction by a short cell-permeable peptide reduced the expression of the Her2 gene and specifically impaired the growth and viability of Her2-overexpressing breast cancer cells. The association of ESX with DRIP130 is mediated by a small hydrophobic face of an 8-aa helix in ESX, suggesting a therapeutic approach to incapacitating the Her2 gene by small organic molecules.

Amino Acid Sequence↗
PubMed2002

Formation of a fairly stable diazoate intermediate of 5-methyl-2'-deoxycytidine by HNO2 and NO, and its implication to a novel mutation mechanism in CpG site.

The intermediate produced from 5-methyl-2'-deoxycytidine ((5me)dCyd) by HNO2 and NO treatments was isolated and characterized. When 10mM (5me)dCyd was incubated with 100mM NaNO2 at pH 3.7 and 37 degrees C, a previously unidentified product was formed. The product was identified as a diazoate derivative of (5me)dCyd, 1-(beta-D-2'-deoxyribofuranosyl)-5-methyl-2-oxopyrimidine-4-diazoate ((5me)dCyd-diazoate), on the bases of several measurements including LC/MS. The time course of the concentration change of the diazoate showed a characteristic profile of a reaction intermediate, and the steady state concentration was 2.3 microM (0.023% yield). When an aqueous solution of 10mM (5me)dCyd (10 mL) was bubbled by NO at 37 degrees C under aerobic conditions holding the pH around 7.4, the diazoate was also generated. The yield of the diazoate was 0.041 micromol (0.041% yield) at 20 mmol of NO absorption. At physiological pH and temperature (pH 7.4, 37 degrees C), the diazoate was converted to dThd exclusively with a first order rate constant k=9.1x10(-6) x s(-1) (t(1/2)=21 h). These results show that the diazoate is generated as a relatively stable intermediate in the reactions of (5me)dCyd with HNO2 and NO and further suggest that the diazoate can be formed in cellular DNA with biologically relevant doses of HNO2 and NO.

Azo Compounds↗