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Biomedical subjects

K Matsuda

Publications and source records attributed to K Matsuda.

At least 595 records · Page 33Linked to original sources
PubMed1988

Sequence and over-expression of subunits of adenosine triphosphate synthase in thermophilic bacterium PS3.

The primary structures of all the subunits of thermophilic ATP synthase were determined, and its alpha, beta and gamma subunits could be over-expressed in Escherichia coli, because these subunits were stable and reconstitutable. DNA of 7500 base pairs in length was found to contain a cluster of nine genes for subunits of ATP synthase. The order of their reading frames (size in base pairs) was: I(381): a(630): c(216): b(489): delta(537): alpha(1507): gamma(858): beta(1419): epsilon(396), I being a gene for a small hydrophobic, basic protein expressed in vitro. All the termini of TF0F1 subunits were confirmed by peptide sequencing. Large quantities of the overexpressed thermophilic alpha, beta and gamma subunits were prepared from the extract of E. coli, by a few purification steps.

Amino Acid Sequence↗
PubMed1988

Effect of an anti-ulcer drug, plaunotol, and its metabolites on NAD+ dependent 15-hydroxyprostaglandin dehydrogenase from gastric mucosa.

15-Hydroxyprostaglandin dehydrogenase was partially purified from hog gastric mucosa by about 1000-fold with a 13.5% yield. Its molecular weight was estimated to be 32,000 daltons by gel filtration. The enzyme was inhibited by some metabolites of plaunotol [(2E, 6Z, 10E)-7-hydroxymethyl-3,11,15-trimethyl-2,6,10,14-hexadecatetrae n-1- ol], a new anti-ulcer drug. The inhibition patterns for substrates, prostaglandin E1 and NAD+ were both uncompetitive with Ki values of 7.8 and 19.7 microM, respectively.

Animals↗
PubMed1988

The pathophysiological role of digitalis-like substance in essential hypertension.

In order to investigate the role of digitalis-like substance in patients with essential hypertension, levels of plasma digitalis-like substance were measured in nine normotensive, 12 normal-renin and seven low-renin essential hypertensive subjects. The level of plasma digitalis-like substance was determined by using two different methods, the digoxin radio-immunoassay established by our laboratory and Na+,K+-ATPase inhibitory activity (modified Hamlyn's method). There was a significant positive correlation between plasma immunoreactive digitalis-like substance and Na+,K+-ATPase inhibitory activity in plasma samples. Both values were significantly higher in hypertensives than in normotensives. Moreover, Na+,K+-ATPase inhibitory activity was significantly higher in low-renin hypertensives than in normal-renin hypertensives or normotensives. These findings suggest (1) digoxin radio-immunoassay may be able to determine the level of plasma digitalis-like substance; (2) digitalis-like substance is increased in essential hypertensives, especially in low-renin hypertensives; (3) the level of digitalis-like substance might be related to plasma renin activity, and mediated by a change in plasma volume; and (4) the activity of the digitalis-like substance may contribute to the pathophysiology of essential hypertension.

Adult↗
PubMed1988

Formation of UDP-Xylose and Xyloglucan in Soybean Golgi Membranes.

Soybean (Glycine max) membranes co-equilibrating with Golgi vesicles in linear sucrose gradients contained UDP-glucuronate carboxy-lyase and xyloglucan synthase activities. Digitonin solubilized and increased the activity of the membrane-bound UDP-glucuronate carboxy-lyase. UDP-xylose did not inhibit the transport of UDP-glucuronate into the lumen of Golgi vesicles but repressed the decarboxylation of the translocated UDP-glucuronate. The results suggest that UDP-glucuronate is transported into the vesicles by a specific carrier and decarboxylated to UDP-xylose within the lumen. On incubation of UDP-[(14)C]glucuronate with Golgi membranes in the presence of UDP-glucose, [(14)C]xylose-labeled xyloglucan was formed. Although the K(m) value of UDP-glucuronate for the decarboxylation was 240 micromolar, the affinity of UDP-glucuronate for xyloglucan formation (31 micromolar) was similar to that of UDP-xylose (28 micromolar), suggesting a high turnover of UDP-xylose. The biosynthesis of UDP-xylose from UDP-glucuronate probably occurs in Golgi membranes, where xyloglucan subsequently forms from UDP-xylose and UDP-glucose.

Journal Article↗
PubMed1988

The relation of anatomy to water movement and cellular response in young barley leaves.

Young barley (Hordeum vulgare L. cv Arivat) leaves were examined anatomically and physiologically to infer the pathway of transpirational water movement and to explain why the growing region is more responsive to osmotic stress than the expanded blade. Vessels with open lumens extend from the intercalary meristem to the expanded blade, and all vessels are clustered in five vascular bundles that are separated by 20 closely packed mesophyll cells. Heat pulse transport data confirmed the anatomical suggestion that water moves through the growing region in vessels and not intercellularly, and also showed that stress reduces xylem water transport within 1 minute while transpiration remained unaffected. Water equal in volume to twice that expected in the xylem, and which exchanges more readily with water in the nutrient solution than with most water in tissues, can be extracted easily from growing tissues. It is hypothesized that this water is xylem plus cell wall water, that osmotic stress will quickly reduce its in situ water potential, and that stress causes growth to stop because cells in the growing region can respond rapidly to changes in water potential around them. In the expanded blade, bundles containing vessels are three and eight cells away from the closest and next substomatal cavities. This allows xylem water loss to occur predominantly through the closest stomata, and the expanded blade is believed to be less responsive because effects of stress on xylem water potential are confined largely to cells immediately around the vessels.

Journal Article↗
PubMed1988

DNA-binding activity of hepatitis B e antigen polypeptide lacking the protaminelike sequence of nucleocapsid protein of human hepatitis B virus.

The characteristics of binding of hepatitis B core antigen (HBcAg) and hepatitis B e antigen (HBeAg) polypeptides to hepatitis B virus (HBV) DNA were analyzed. HBcAg polypeptide from recombinant HBV core particles and HBeAg polypeptide from partially purified serum HBeAg were prepared and verified to have molecular weights of 21,500 (P21.5) and of 17,000 (P17) and 18,000 (P18), respectively, by immunoblot analysis. By reaction of these proteins on a nitrocellulose membrane with cloned 32P-HBV DNA, it was revealed that the HBeAg polypeptide, which lacks the C-terminal 34 amino acids of P21.5, as well as the HBcAg polypeptide, bound to the DNA. The secondary structures of nucleocapsid proteins of HBV, woodchuck hepatitis virus, and ground squirrel hepatitis virus were predicted by the Garnier algorithm. Amino acid sequences which, in addition to those of the C-terminal regions, may contribute to binding were proposed to be the 21-amino-acid residues located at amino acids 100 to 120 of the nucleocapsid proteins of these hepadnaviruses.

Algorithms↗
PubMed1988

Fetal breathing and sleep state responses to graded carboxyhemoglobinemia in sheep.

To investigate CO effects on brain oxygenation, graded carboxyhemoglobinemia (HbCO) was produced in nine unanesthetized fetal sheep by infusing CO-laden erythrocytes in exchange for fetal blood. For the 1st h after this procedure, the mean fetal carboxyhemoglobin levels were 16.5 +/- 0.4% [control (C) = 1.4 +/- 0.4%] for mild HbCO, 22.7 +/- 0.6% (C = 1.8 +/- 0.4%) for moderate HbCO, and 27.8 +/- 0.5% (C = 2.1 +/- 0.7%) for severe HbCO. This induction of HbCO significantly reduced mean preductal arterial PO2 values to 4.3 Torr below control for mild HbCO, 4.6 Torr below control for moderate HbCO, and 5.5 Torr below control for severe HbCO. The respective arterial O2 contents were decreased by 17, 21, and 29%. Mean arterial pH was lowered only during severe HbCO, and arterial PCO2 values were unchanged. HbCO produced a fetal tachycardia. Mean arterial blood pressure was only increased during severe HbCO. The incidences of rapid eye movements and breathing activity were decreased by HbCO in a dose-dependent manner. When related to calculated brain tissue PO2, these decreases were similar to those measured during hypoxic hypoxia and anemia, suggesting that carboxyhemoglobin effects result solely from diminished oxygenation. It is concluded that 1) the peripheral arterial chemoreceptors in the fetus apparently have little effect on hypoxic inhibition of breathing and 2) the carboxyhemoglobin concentrations required to inhibit fetal breathing are greater than those likely to be encountered clinically.

Animals↗
PubMed1988

Myocardial positron tomography with N-13 ammonia in assessment of aortocoronary bypass surgery.

A total of 20 patients were examined at rest and during stress with N-13-ammonia myocardial positron emission tomography (PET) before and after aortocoronary bypass surgery in an attempt to evaluate the effect of surgery on myocardial perfusion and to predict the graft status. The PET images were divided into anterior, septal, apical, lateral and posteroinferior segments for analysis and were evaluated as "normal" (no perfusion defects during stress and at rest), "ischemia" (stress-induced defects) and "fibrosis" (persistent defects both at rest and during stress). Approximately 90% of the segments which were ischemic before surgery became normal after surgery. Thus, ischemic changes are highly reversible, and the vessels perfusing these ischemic areas are most suitable for bypass surgery. However, most of the persistent defects failed to respond to revascularization surgery and, hence, represented irreversibly damaged myocardium. In predicting graft status, graft patency could be demonstrated by normal perfusion in postoperative images (p less than 0.01) or by improved perfusion when pre- and postoperative images were compared (p less than 0.01). However, graft occlusion could not be predicted reliably. This study demonstrated that PET with N-13 ammonia was useful in the assessment of the effects of aortocoronary bypass surgery. However, this technique was not significantly superior to thallium-201 single-photon emission computed tomography for only qualitative analysis.

Adult↗
PubMed1988

Mode of action of BO-1341: transport pathway through the outer membrane of Escherichia coli.

BO-1341, a new semisynthetic cephalosporin having a 6,7-dihydroxyisoquinolinium moiety at the C-3 methylene, possesses potent antibacterial activity against Gram-negative bacteria including glucose-nonfermentative bacteria, especially Pseudomonas aeruginosa. In order to elucidate the mechanisms of action, the transport pathway of BO-1341 through the outer membrane of Escherichia coli was studied. The antibacterial activity of BO-1341 was not affected by the deficiency in OmpF and OmpC porin channels compared with its wild-type strain, but was affected by the iron concentration in the medium. Susceptibility testing with the mutants involved in the iron transport system indicated that the tonB mutant was resistant to BO-1341. Analysis of the spontaneous mutants resistant to BO-1341 revealed a mutation in the tonB gene. The strong activity of BO-1341 and the lack of cross-resistance to other cephalosporins may be attributable to the unique transport system through the outer membrane of Gram-negative bacteria.

Anti-Bacterial Agents↗