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Biomedical subjects

M Maeda

Publications and source records attributed to M Maeda.

At least 973 records · Page 54Linked to original sources
PubMed1989

Chemical synthesis of the 24 RNA fragments corresponding to hop stunt viroid.

A general and practical synthetic method of oligoribonucleotides (10-20 mers) by using the cyanoethyl phosphoramidite approach was described. In this experiment 9-phenylxanthen-9-yl (Pix) and 9-(4-methoxy)phenylxanthen-9-yl (Mox) groups were employed for the 5'-hydroxyls and tetrahydropyranyl (Thp) group was used for the 2'-hydroxyl protecting groups. In addition, suitable acyl groups were introduced for the protection of the lactam functions of guanine and uracil moieties.

Base Sequence↗
PubMed1989

Dicyclohexylcarbodiimide-binding protein is a subunit of the Methanosarcina barkeri ATPase complex.

Membrane ATPase of Methanosarcina barkeri was inhibited by N, N'-dicyclohexylcarbodiimide (DCCD), whereas the extrinsic alpha beta complex of the same enzyme was not. Consistent with this finding, a 6,000 dalton (6 kDa) membrane protein was preferentially labeled with radioactive DCCD. The DCCD-sensitive ATPase was solubilized from the membranes with octylglucoside and purified in the presence of this detergent. The purified ATPase contained the alpha and beta subunits and also at least four additional proteins (40, 27, 23 and 6 kDa). The 6 kDa protein in the purified enzyme reacted with DCCD, indicating that it is a subunit of an integral part of the M. barkeri ATPase complex.

Carbodiimides↗
PubMed1989

[Experimental study of hemodynamic changes following superior mesenteric arterial injection of various contrast media].

Following the superior mesenteric arterial injection of three contrast media, [38% Meg/Na Amidotrizoate, 76% Meg/Na Amidotrizoate, Iopamidol (370 mg l/ml)], and isotonic saline, we measured and analyzed the changes of superior mesenteric arterial blood flow rate for 10 minutes continuously in 6 dogs by means of electromagnetic flow meter. Blood volume change of superior mesenteric arterial blood flow was calculated by integration of blood flow. After injection of the agents, superior mesenteric arterial flow increased and returned to control level. The duration was influenced by the agent's osmolality. Therefore, volume change was analyzed because it is concurrent index of flow and duration. Correlation between volume change (increase) of superior mesenteric arterial blood flow and the agent's osmolality was shown. (r = 0.985, p less than 0.01). Increased blood volume of local arterial blood flow appears to be a desirable index for estimating vasodilatory effect of contrast media.

Animals↗
PubMed1989

Amino acid sequence of the alpha and beta subunits of Methanosarcina barkeri ATPase deduced from cloned genes. Similarity to subunits of eukaryotic vacuolar and F0F1-ATPases.

The atpA and atpB genes coding for the alpha and beta subunits, respectively, of membrane ATPase were cloned from a methanogen Methanosarcina barkeri, and the amino acid sequences of the two subunits were deduced from the nucleotide sequences. The methanogenic alpha (578 amino acid residues) and beta (459 amino acid residues) subunits were highly homologous to the large and small subunits, respectively, of vacuolar H+-ATPases; 52% of the residues of the methanogenic alpha subunit were identical with those of the large subunit of vacuolar enzyme of carrot or Neurospora crassa, respectively, and 59, 60, and 59% of the residues of the methanogenic beta subunit were identical with those of the small subunits of N. crassa, Arabidopsis thaliana, and Sacharomyces cerevisiae, respectively. The methanogenic subunits were also highly homologous to the corresponding subunits of Sulfolobus acidocaldarius ATPase. The methanogenic alpha and beta subunits showed 22 and 24% identities with the beta and the alpha subunits of Escherichia coli F1, respectively. Furthermore, important amino acid residues identified genetically in the E. coli enzyme were conserved in the methanogenic enzyme. This sequence conservation suggests that vacuolar, F1, methanogenic, and S. acidocaldarius ATPases were derived from a common ancestral enzyme.

Adenosine Triphosphatases↗
PubMed1989

Cell culture of small round cell tumor originating in the thoracopulmonary region. Evidence for derivation from a primitive pluripotent cell.

The authors describe a 14-year-old girl with small round cell tumor originating in the chest wall analyzed by the extensive studies including light and electron microscopic examination, histochemical study, immunochemical study, cytogenetics, and gene analysis. A cell line producing carcinoembryonic antigen (CEA) and neuron-specific enolase (NSE) has been established from pleural effusion of the pulmonary metastatic tumor. Cytogenetic analysis disclosed a reciprocal translocation (11;22)(q24;q12). Additionally, immunocytochemical studies demonstrated that CEA, NSE, vimentin, cytokeratin, and epithelial membrane antigens are positive, but desmin and S-100 protein are negative. Although neurofilament was negative in the pulmonary metastatic tumor cells, it became positive in cell line in vitro. These results suggest that this tumor may be derived from the primitive and pluripotential cells, differentiating into mesenchymal, epithelial, and neural features in variable proportions.

Adolescent↗
PubMed1989

Pig gastric (H+ + K+)-ATPase. Lys-497 conserved in cation transporting ATPases is modified with pyridoxal 5'-phosphate.

Pig gastric (H+ + K+)-ATPase can be covalently modified with pyridoxal 5'-phosphate (PLP) (about 1 mol/mol enzyme), and this modification is not observed in the presence of ATP, suggesting that PLP binds to a specific Lys residue in the ATP binding site or the region in its vicinity (Maeda, M., Tagaya, M., and Futai, M. (1988) J. Biol. Chem. 263, 3652-3656). The peptides labeled with radioactive PLP could be released from the gastric membrane vesicles quantitatively by chymotrypsin treatment, and two peptides were purified by high performance liquid chromatographies. These peptides were not obtained from vesicles incubated with PLP in the presence of ATP. The sequences of the two peptides were NH2-Asn-Ser-Thr-Asn-Lys-Phe-COOH and NH2-Ser-Thr-Asn-Lys-Phe-COOH, exactly corresponding to residues 493-498 and 494-498, respectively, of pig gastric (H+ + K+)-ATPase sequenced recently (Maeda, M., Ishizaki, J., and Futai, M. (1988) Biochem. Biophys. Res. Commun. 157, 203-209). Lys-497 was concluded to be the binding site of PLP, as pyridoxyl-Lys was identified at the corresponding position. This Lys residue is conserved in (Na+ + K+)- and Ca2+-ATPases. The possible amino acid residues in the catalytic site of gastric (H+ + K+)-ATPase are discussed.

Adenosine Triphosphatases↗
PubMed1989

Expression of different combinations of interleukins by human T cell leukemic cell lines that are clonally related.

We have analyzed expression patterns of 7 lymphokine mRNAs by Northern blot analyses in 19 different human T cell clones derived from patients with adult T cell leukemia. However, we were not able to reveal particular combinations of lymphokine production that allowed classification of human T cells. Especially, four clonally related leukemic lines that were established independently from the same patient with adult T cell leukemia expressed different combinations of lymphokine mRNAs, indicating that the expression of various lymphokines is not fixed but rather variable even among progenies of a single T cell clone.

Clone Cells↗
PubMed1989

Evaluation by exercise Doppler echocardiography of maintenance of cardiac output during ventricular pacing with or without chronotropic response.

To examine the effectiveness of activity-initiated rate-responsive pacing, this study assessed the increases in stroke volume and cardiac output during randomized treadmill exercise in rate-responsive and fixed-rate ventricular (VVI) pacing in 10 patients. Stroke volume index and cardiac index were determined by suprasternal Doppler measurements. Compared with the findings during VVI pacing, the rate-responsive pacing was associated with (1) prolongation of exercise duration (8.0 +/- 4.0 vs 7.3 +/- 3.6 minutes, p less than 0.05); (2) greater exercise-induced positive chronotropic response (mean maximal heart rate 127 +/- 12 vs 78 +/- 15 beats/min, p less than 0.001); (3) smaller increase in stroke volume index (38 +/- 10 vs 50 +/- 11 ml/m2, p less than 0.001), and (4) greater increase in cardiac index (4.7 +/- 1.1 vs 3.9 +/- 1.0 liters/min/m2, p less than 0.001). A significant correlation was observed between age and percent increase in stroke volume index during VVI pacing (p less than 0.05). These findings indicate that VVI pacing increased stroke volume more than did rate-responsive pacing, especially in younger patients, but the increase in cardiac output was less than that seen with rate-responsive pacing due to the absence of chronotropic response. Accordingly, an activity-sensing, rate-responsive pacemaker can effectively increase the heart rate, significantly augment cardiac output and extend the duration of exercise.

Adult↗
PubMed1989

Intracellular hydroxyl radical production induced by recombinant human tumor necrosis factor and its implication in the killing of tumor cells in vitro.

This study investigated the effect of recombinant human tumor necrosis factor (rhTNF) on hydroxyl radical production by established cell lines in vitro, and its implication in the killing of tumor cells by rhTNF. During incubation of TNF sensitive mouse tumorigenic fibroblast L-M cells (2 X 10(7) cells) in the presence of rhTNF (100 U), hydroxyl radical production as detected by the evolution of methane gas from dimethyl sulfoxide increased gradually, at 18 h reaching 1.8 times that in the absence of rhTNF. This increase was dependent on the concentration of rhTNF and was effectively prevented by the simultaneous addition of anti-rhTNF monoclonal antibody III 2F3, which inhibited both the binding of rhTNF to its receptor and the cytotoxic activity of rhTNF. The addition of iron chelator 2,2'-bipyridine, which inhibits iron-catalized Fenton reaction and so inhibits hydroxyl radical generation, suppressed both the increase of hydroxyl radical production and the cytotoxicity induced by rhTNF. A similar increase in hydroxyl radical production in the presence of rhTNF was also detected with TNF-sensitive human myosarcoma-derived KYM cells, but no such increase was detected with TNF insensitive human embryonic lung fibroblast HEL cells. The results show that rhTNF induces increased hydroxyl radical production in TNF-sensitive cells, and suggest that this plays an important role in the mechanism of tumor cell killing by rhTNF.

2,2'-Dipyridyl↗
PubMed1989

Mutational replacements of conserved amino acid residues in the alpha subunit change the catalytic properties of Escherichia coli F1-ATPase.

Four Escherichia coli mutants with defects in the alpha subunit of H+-ATPase (F0F1) (strain KF154, Pro-281----Leu; KF101 and KF131, Ala-285----Val; KF114, Arg-376----Cys) were isolated, and the kinetic properties of their F1-ATPases were studied. All the mutations so far identified are clustered in the two defined regions of the alpha subunit. With F1 of strain KF114, as with F1 of uncA401 (Ser-373----Phe; T. Noumi, M. Futai, and H. Kanazawa (1984) J. Biol. Chem. 259, 10076-10079), the rate of multisite hydrolysis of ATP was 4 X 10(-3)-fold lower than that with wild-type F1, suggesting that residues Ser-373 and Arg-376 or the regions in their vicinities are essential for positive catalytic cooperativity. With F1 from strain KF101, multisite hydrolysis was higher (about 40% of that of the wild type), but the F1 was unstable and showed defective interaction with the membrane sector (F0). The F1 from KF154 had lower multisite hydrolysis (about 10% of that of the wild type) but could support slow growth by oxidative phosphorylation.

Adenosine Triphosphate↗
PubMed1989

Chemiluminescent assay of various enzyme activities and its application to enzyme immunoassays.

A highly sensitive chemiluminescent assay for NAD(P)H have been developed. The principle of the method is as follows; NAD(P)H reduces molecular oxygen to superoxide anion (O2-) and hydrogen peroxide (H2O2) in the presence of 1-methoxy-5-methylphenazinium methyl sulphate (1-MPMS) as electron mediator. The produced O2- and H2O2 can be measured by chemiluminescent reaction using isoluminol (IL) and microperoxidase (m-POD). A linear relationship between chemiluminescence intensity and NAD(P)H concentration (log/log) was obtained ranged from 10(-9) mol/l to 10(-5) mol/l. This chemiluminescent reaction has been coupled to the assay of glucose-6-phosphate dehydrogenase (G6PDH), beta-D-galactosidase (beta-Gal) and alkaline phosphatase (ALP). The detection limits of G6PDH, beta-Gal and ALP were 10(-18) mol, 10(-20) mol and 10(-18) mol per assay, respectively. The chemiluminescent assay of these enzymes applied to chemiluminescent enzyme immunoassay for 17 alpha-hydroxy-progesterone and DNA hybridization assay using these enzymes as label.

Alkaline Phosphatase↗
PubMed1989

Chemiluminescent assay of co-factors.

Bioluminescent methods are widely used for the assay of the co-factors, NADH and ATP. Although the bioluminescent method is highly sensitive, the enzymes used are unstable and expensive. Therefore a chemiluminescent method would be valuable in clinical routine assay. We have developed a chemiluminescent method for the assay of NADH using the 1-methoxy-5-methylphenazinium methyl sulphate (1-MPMS)/isoluminol(IL)/microperoxidase(m-POD) system. In order to increase the sensitivity of this method, enzymatic cycling system was coupled to the chemiluminescent assay of NADH. Alcohol dehydrogenase and malate dehydrogenase were used as the cycling enzyme. The standard curve was obtained in the range from 3 X 10(-14) to 5 X 10(-12) mol/assay. The detection limit of NADH was 30 fmol/assay which was comparable to that of the bioluminescent method using bacterial luciferase. Two chemiluminescent methods for the assay of ATP have been developed. Method 1 is the system using hexokinase/G6PDH and 1-PMS/IL/m-POD, and method 2 is the system based on the enzymatic cycling reaction of ATP using hexokinase/pyruvate kinase. Method 2 is 1000/fold more sensitive than the method 1. The detection limit of ATP was 10 fmol/assay.

Adenosine Triphosphate↗
PubMed1989

Signalling pathway of tumor necrosis factor in normal and tumor cells.

Several aspects of the activity and effects of tumor necrosis factor (TNF) were investigated to gain further insight into its cytotoxic mechanism. The relation between number of TNF receptors and TNF susceptibility of both tumor cells and normal cells was studied, utilizing a specific binding assay. Among the tumor cells, a fairly close correlation (r = 0.855) was observed between receptor number and sensitivity to TNF. No cytotoxic effect by TNF was observed on any of the normal cells tested, even though TNF receptors were shown to be present, and cell proliferation was apparently stimulated by TNF in some cases. TNF internalization and intracellular distribution were studied by pulse-labelling and Percoll density gradient centrifugation. In L-M (murine tumorigenic fibroblasts, highly sensitive to TNF cytotoxicity) cells and HEL (human embryonic lung cells, non-sensitive to TNF cytotoxicity) cells, receptor-bound 125I-labelled recombinant human TNF was rapidly internalized and delivered to lysosomes within 15-30 min, and this was followed by degradation and release into the culture medium. The presence of either a cytoskeletal disrupting agent or a lysosomotropic agent was observed to inhibit the cytotoxic effect of TNF, thus also indicating that TNF internalization, followed by delivery to lysosomes, is essential in the cytolytic mechanism of TNF. As observed by [3H]uridine incorporation, TNF did not affect RNA synthesis in L-R cells (TNF-resistant cell lines derived from L-M cells) and HEL cells, but markedly stimulated (by 3.5 times) RNA synthesis in L-M cells.

Animals↗
PubMed1989

Mapping and nucleotide sequence of a new HLA class II light chain gene, DQB3.

A genomic clone specifying a new HLA class II antigen beta chain, DQB3, was isolated from a human genomic phage library using a DQB1 cDNA probe under low stringency conditions. Southern hybridization and nucleotide sequence analyses identified the beta 2 domain exon (exon 3) with several deleterious mutations and the CP-TM-CY exon [connecting peptide, transmembrane, and cytoplasmic regions, (exon 4)], but the first, second, and fifth exons encoding the 5' UT-leader, the beta 1 domain, and the 3' UT domain of normal beta chains, respectively, were entirely missing. The nucleotide sequences of these two exons were distinct from those of other class II beta chain genes, but slightly more related to the DQB1 and DQB2 genes than to other class II genes. The DQB3 sequence mapped between DQA2 and DQB1, 15 kb upstream from DQA2, by analysis of overlapping cosmid clones. This mapping was supported by the fact that Taq I, Msp I, and Bam HI DQB3 polymorphisms were perfectly correlated with the DQA2 polymorphism and not with any polymorphisms in the DR or DQ subregion, suggesting the presence of a hot spot for recombination between DQB3 and DQB1.

Amino Acid Sequence↗
PubMed1989

Postoperative results of distal partial gastrectomy, selective vagotomy plus antrectomy, and selective proximal vagotomy for duodenal ulcers.

We investigated the postoperative results of distal partial gastrectomy, selective vagotomy plus antrectomy, and selective proximal vagotomy, to evaluate their effectiveness in the treatment of duodenal ulcers. The operative mortality of selective vagotomy plus antrectomy and selective proximal vagotomy seemed to be lower when compared to distal partial gastrectomy, although each procedure showed a sufficiently low mortality. The acid reduction rate was significantly lower after selective proximal vagotomy than after the other procedures (p less than 0.01). However, the rate of ulcer recurrence following selective proximal vagotomy tended to be higher compared with the other procedures. All three procedures showed good results according to Visick's grading and postoperative symptoms occurred in about 50 per cent of all patients, no matter what the procedure. The regaining of physical ability was significantly greater following selective proximal vagotomy than following distal partial gastrectomy (p less than 0.05) and the capacity to work was also better after vagotomy, particularly selective vagotomy plus antrectomy (p less than 0.05). Thus, although distal partial gastrectomy and selective vagotomy plus antrectomy proved superior regarding the low ulcer recurrence rate and acid reduction, while selective proximal vagotomy proved superior for improving the quality of life, on the whole, the three operations promise almost equivalent results.

Adult↗