Search PubMed⌕ Search

Biomedical subjects

M Maeda

Publications and source records attributed to M Maeda.

At least 1,027 records · Page 57Linked to original sources
PubMed1989

[Diagnostic value of the cortico-medullary contrast on dynamic CT and MRI in chronic renal parenchymal diseases].

Correlation between cortico-medullary contrast (CMC) and dynamic CT or MRI for chronic renal parenchymal diseases was evaluated compared with serum creatinine level (Cr). Forty two kidneys of 23 patients were chronic glomerulonephritis (12), chronic pyelonephritis (12), chronic renal failure (4), and other diseases (14). Thirty two kidneys with low Cr (under 1.6) were demonstrated the good CMC by dynamic CT and T1-weighted image (IR) of 0.5 T. Six with middle of Cr (between 1.6 and 3.0) were showed a decrease in CMC and four with high Cr (over 3.0) had no CMC. CMC correlated with Cr.

Chronic Disease↗
PubMed1989

[Excretory urography with non-ionic contrast medium; clinical reassessment of the necessity of water deprivation].

The prospective study was performed to reassess the necessity of water deprivation before excretory urography (IVP) with non-ionic contrast medium. 35 adults were deprived of water before IVP and divided into two groups. First group was received 250 ml 5% glucose solution and lopamidol-300 (1 ml/kg, maximum dose; 50 ml). Second group received contrast medium only. Image quality of IVP of the two groups were compared. In the first group the visualization of ureter and bladder were better than the second group. There was no significant difference in the caliceal and pelvic visualization between the two groups. Water deprivation was suggested to be unnecessary in IVP with non-ionic contrast medium.

Adult↗
PubMed1989

Influence of gestation on renal function in gravida with IgA nephropathy.

Nineteen pregnancies in 17 women with IgA nephropathy (IgAGN) were studied in terms of the influence of gestation on the natural course of renal function in IgAGN. We performed serial examinations of the serum creatinine (S-Cr) levels before and during pregnancy and after delivery. Group I comprised 11 pregnancies in 10 gravida who revealed proteinuria (1.1 +/- 0.7 g/day; mean +/- SD) and microhematuria before pregnancy. The S-Cr before pregnancy averaged 0.86 +/- 0.13 mg/dl. Group II comprised 8 pregnancies in 7 gravida who showed isolated microhematuria. The S-Cr before pregnancy averaged 0.81 +/- 0.06 mg/dl. In group I, S-Cr did not decrease during pregnancy and was elevated at delivery and at 1-4 weeks after delivery (1.03 +/- 0.29 mg/dl, p less than 0.05) in comparison with the level before pregnancy. In group II, S-Cr decreased significantly during pregnancy and was not elevated at delivery or after delivery. The above results suggest that gestation had a slight and transient adverse effect on renal function in IgAGN with proteinuria.

Creatinine↗
PubMed1989

[Sequential internal mammary-coronary artery bypass].

A total of ten patients have undergone sequential bypass grafting of the internal mammary artery (IMA) to the coronary arteries at Osaka Medical College. Operative procedures included left IMA bypass to the left anterior descending (LAD) artery and its major diagonal branch in six patients; to the obtuse marginal branch and diagonal branch in three patients; and to the first and the second diagonal branches in one patient. The right internal mammary artery was concomitantly utilized in 4 patients and saphenous vein graft was also utilized in 6 patients. Postoperative angiographic studies were performed in nine patients within 6 months after operation and in all 18 sites of IMA anastomoses, the IMA sequential grafts were patent. Since sequential IMA-coronary bypass technique means the increase of arterial graft, we believe that this technique should be used for multivessel coronary revascularization especially in younger patients.

Adult↗
PubMed1988

cDNA cloning and sequence determination of pig gastric (H+ + K+)-ATPase.

Complementary DNA to pig gastric mRNA encoding (H+ + K+)-ATPase was cloned, and its amino acid sequence was deduced from the nucleotide sequence. The enzyme contained 1034 amino acid residues (Mr. 114,285) including the initiation methionine. The sequence of pig (H+ + K+)-ATPase was highly homologous with that of the corresponding enzyme from rat, but had high degree of synonymous codon changes. Potential sites of phosphorylation by cAMP-dependent protein kinase and N-linked glycosylation sites were identified. The amino terminal region contained a lysine-rich sequence similar to that of the alpha subunit of (Na+ + K+)-ATPase, although a cluster of glycine residues was inserted into the sequence of the (H+ + K+)-ATPase. As the pig enzyme is advantageous for biochemical studies, the information of the primary structure is useful for further detailed studies.

Adenosine Triphosphatases↗
PubMed1988

Functional domains of epsilon subunit of Escherichia coli H+-ATPase (F0F1).

Mutants of the uncC gene for the epsilon subunit (138 amino acid residues) of Escherichia coli H+-ATPase were isolated: strain KF53 (Gln-72----end) and KF148(SD-) (two base substitutions in the Shine-Dalgarno sequence, GGAGG----AAAGG). These strains did not have F1 bound to membranes and were unable to grow by oxidative phosphorylation. A series of plasmids carrying truncated uncC genes were constructed and introduced into strain KF148(SD-). Analyses of KF148(SD-) cells with different plasmids indicated that the amino-terminal fragment of the epsilon subunit of 78-80 amino acid residues was capable of forming active membrane-bound F1-ATPase, whereas that of 73 residues was not, indicating that the carboxyl-terminal half of the epsilon subunit is not necessary for the active enzyme. Furthermore, results indicated that residues between 73 and 78-80 may have a critical role(s) in binding F1 to F0. Truncated epsilon subunits of 80 and 93 residues were identified in purified F1 from cells carrying the respective uncC genes, and only the latter subunit had intrinsic activity to inhibit ATPase of F1, suggesting that residues between 80 and 93 are essential for the inhibitory activity.

Amino Acid Sequence↗
PubMed1988

Fo portion of Escherichia coli H+-ATPase. Carboxyl-terminal region of the b subunit is essential for assembly of functional Fo.

Six chromosomal uncF mutants of Escherichia coli defective in the b subunit of H+-ATPase (156 amino acid residues) were identified (KF92, Met-1----Val; KF164, Gln-64----end; KF61 and KF144, Gln-104----end; KF138, Gln-106----end; and KF79, Gln-123----end). The membranes of all these mutants had low ATPase activities (less than 5% of that of the wild type), and no functional H+ pathway, although the truncated b subunits were integrated into these membranes. These findings suggest that about 30 carboxyl-terminal amino acid residues of the b subunit are essential for formation of the F1-binding site and H+ pathway. For examination of the role(s) of the carboxyl-terminal region(s) or residue(s) of the b subunit, recombinant plasmids carrying truncated uncF genes of various lengths were constructed by in vitro muta-genesis and introduced into a recA1 derivative of strain KF92 (Met-1----Val). Analyses of the membranes from the resulting strains demonstrated that almost the entire carboxyl-terminal region of the b subunit is necessary for formation of functional Fo, since loss of the carboxyl-terminal residue resulted in significant reduction of both F1 binding and H+ translocation, and loss of two or more residues abolished both activities completely.

Alleles↗
PubMed1988

Induction of synthesis of tumor necrosis factor in human and murine cell lines by exogenous recombinant human tumor necrosis factor.

Treatment of sensitive human myosarcoma cells (KYM-S) with exogenous tumor necrosis factor (r-TNF) resulted in the production of TNF by the cells. The newly synthesized cellular TNF was identified immunologically on Western blots and as a single 1.8-kilobase band on Northern blots. TNF synthesis began within 2 h of administration of the exogenous TNF in a dose-dependent manner. r-TNF also induced TNF synthesis in mouse tumorigenic fibroblasts (L-M). Resistant sublines of these cells as well as TNF nonsensitive human diploid fibroblasts possessed TNF mRNA without pretreatment, indicating an inverse correlation between levels of TNF expressed and sensitivity to the cytotoxic effects of exogenous TNF. It is conceivable that the newly synthesized cellular TNF functions in some protective manner to block cytolytic effects of exogenous TNF.

Animals↗
PubMed1988

Continuous internalization of tumor necrosis factor receptors in a human myosarcoma cell line.

The cell dynamics of the receptor for tumor necrosis factor (TNF) were examined in TNF-sensitive KYM cells derived from human myosarcoma. With receptor synthesis inhibited by cycloheximide, the half-life of the surface TNF receptor was 2 h in the absence of TNF and 30 min in its presence, suggesting that the TNF receptor is non-recycling and that its internalization is accelerated by TNF. During cell incubation with TNF receptor degradation suppressed by chloroquine, the number of surface TNF receptors remained approximately constant, but the total number of surface and internal TNF receptors increased gradually, at 3 h reaching 1.5 times the initial number, thus suggesting continuous synthesis, externalization, internalization, and degradation of the TNF receptor in the absence of cycloheximide. On cell incubation with 125I-TNF, the intracellular quantity of the pulse-labeled TNF-receptor complex promptly increased, reaching a maximum at 20 min, and then gradually declined, thus confirming that the TNF receptor is internalized as a TNF-receptor complex in the presence of TNF. During incubations with protein synthesis suppressed by cycloheximide following surface TNF receptor digestion by trypsin, TNF receptors reappeared on the cell surface, increasing in number to a peak at 60 min and gradually decreasing, and cells previously exposed to cycloheximide with or without TNF showed no recurrence of surface TNF receptors, suggesting that the TNF receptor is non-recycling. The results of the study thus suggest that the TNF receptor is continuously internalized and degraded intracellularly by lysosomes without being recycled regardless of the presence or absence of TNF and, further, that its internalization is accelerated when it is part of the TNF-receptor complex.

Cell Line↗
PubMed1988

Intrinsic membrane sector (Fo) of H+-ATPase (FoF1) from Escherichia coli. Mutations in the alpha subunit give Fo with impaired proton translocation and F1 binding.

Mutant alleles for the alpha subunit of H+-translocating ATPase (FoF1) were cloned from Escherichia coli strains isolated in this laboratory. Determination of their DNA sequence revealed four nonsense mutations (KF3 and KF9, Gln-20----end; KF24, Trp-111----end; KF2, Trp-231----end; KF70, Gln-252----end) and one missense mutation (KF45, Pro-143----Ser). The membranes of all the mutants except strain KF9 (KF3) had 50-70% of ATPase activities of the wild-type. Unlike the F1-ATPase of the wild-type, those of the mutants were insensitive to dicyclohexylcarbodiimide and were easier to solubilize from membranes. As membranes of strain KF24 had F1-ATPase activity, these results suggest that at least a part of the F1-binding sites could be formed without a region between residues 111 and the carboxyl terminus of the alpha subunit. However, normal interactions between Fo and F1 require regions between residues 252 and 271 (carboxyl terminus) and in the vicinity of Pro-143. Membranes of strain KF45 were capable of forming a low ATP-driven H+ gradient, whereas other membranes were not. The possibility that the region between residues 252 and 271 is involved in H+ translocation is discussed.

Alleles↗
PubMed1988

A homologous sequence between H+-ATPase (F0F1) and cation-transporting ATPases. Thr-285----Asp replacement in the beta subunit of Escherichia coli F1 changes its catalytic properties.

A sequence of 10 amino acids (I-C-S-D-K-T-G-T-L-T) of ion motive ATPases such as Na+/K+-ATPase is similar to the sequence of the beta subunit of H+-ATPases, including that of Escherichia coli (I-T-S-T-K-T-G-S-I-T) (residues 282-291). The Asp (D) residue phosphorylated in ion motive ATPase corresponds to Thr (T) of the beta subunit. This substitution may be reasonable because there is no phosphoenzyme intermediate in the catalytic cycle of F1-ATPase. We replaced Thr-285 of the beta subunit by an Asp residue by in vitro mutagenesis and reconstituted the alpha beta gamma complex from the mutant (or wild-type) beta and wild-type alpha and gamma subunits. The uni- and multisite ATPase activities of the alpha beta gamma complex with mutant beta subunits were about 20 and 30% of those with the wild-type subunit. The rate of ATP binding (k1) of the mutant complex under uni-site conditions was about 10-fold less than that of the wild-type complex. These results suggest that Thr-285, or the region in its vicinity, is essential for normal catalysis of the H+-ATPase. The mutant complex could not form a phosphoenzyme under the conditions where the H+/K+-ATPase is phosphorylated, suggesting that another residue(s) may also be involved in formation of the intermediate in ion motive ATPase. The wild-type alpha beta gamma complex had slightly different kinetic properties from the wild-type F1, possibly because it did not contain the epsilon subunit.

Adenosine Triphosphatases↗
PubMed1988

Ab initio molecular orbital study of the mispairing ability of a nucleotide base analogue, N4-aminocytosine.

The intrinsic properties of N4-aminocytosine, a base analogue of cytosine, are analyzed by an ab initio molecular orbital method. Relative stabilities of four possible isomeric structures of N4-aminocytosine are shown. The more stable isomer has the smaller dipole moment, so the relative stabilities of the isomers in solutions are subject to solvent polarity. The mutagenicity of this base analogue must arise because it can behave like either cytosine or thymine. It can form a guanine-cytosine-like base pair more easily than cytosine, and an adenine-thymine-like base pair less easily than thymine.

Chemical Phenomena↗
PubMed1988

Determination of FDP in human plasma by a novel latex immunoassay.

Distribution analyzing latex immunoassay (DALIA), a sensitive method based on the agglutination of latex particles coated with monoclonal antibody, was developed for determination of fibrin degradation products (FDP) in human plasma. The agglutination is measured by using an electric particle counter designed for medical research to determine the volume-ratio of agglutinated to non-agglutinated particles. Interference by serum constituents is avoided by coating the particles with the F(ab')2 fragments of monoclonal antibody and by using suitable latex particles. This assay enabled the determination of FDP in concentrations of 16 to 4000 ng/ml in less than 15 minutes. The mean concentrations of FDP in the plasma of 98 normal subjects and 142 patients with apparent disseminated intravascular coagulation (DIC) were 0.69 and 13.24 micrograms/ml, respectively. Analytical recovery of FDP in plasma samples averaged 104%. The correlation coefficient of DALIA with enzyme immunoassay using two monoclonal antibodies, was 0.809. The results obtained by analyzing the cross-reactivity with related components of FDP and the inhibitory effect of D monomer indicated that the present method can effectively detect the high molecular weight (HMW) fragments of FDP produced in the early stage of plasmin digestion.

Antibodies, Monoclonal↗