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J Minami

Publications and source records attributed to J Minami.

88 records · Page 5Linked to original sources
PubMed1987

Ca2+ uptake by corpus-luteum plasma membranes. Evidence for the presence of both a Ca2+-pumping ATPase and a Ca2+-dependent nucleoside triphosphatase.

Plasma-membrane vesicles from rat corpus luteum showed an ATP-dependent uptake of Ca2+. Ca2+ was accumulated with a K1/2 (concn. giving half-maximal activity) of 0.2 microM and was released by the bivalent-cation ionophore A23187. A Ca2+-dependent phosphorylated intermediate (Mr 100,000) was detected which showed a low decomposition rate, consistent with it being the phosphorylated intermediate of the transport ATPase responsible for Ca2+ uptake. The Ca2+ uptake and the phosphorylated intermediate (E approximately P) displayed several properties that were different from those of the high-affinity Ca2+-ATPase previously observed in these membranes. Both Ca2+ uptake and E approximately P discriminated against ribonucleoside triphosphates other than ATP, whereas the ATPase split all the ribonucleoside triphosphates equally. Both Ca2+ uptake and E approximately P were sensitive to three different Hg-containing inhibitors, whereas the ATPase was inhibited much less. Ca2+ uptake required added Mg2+ (Km = 2.2 mM), whereas the ATPase required no added Mg2+. The maximum rate of Ca2+ uptake was about 400-fold less than that of ATP splitting; under different conditions, the decomposition rate of E approximately P was 1,000 times too slow to account for the ATPase activity observed. All of these features suggested that Ca2+ uptake was due to an enzyme of low activity, whose ATPase activity was not detected in the presence of the higher-specific-activity Ca2+-dependent ATPase.

Adenosine Triphosphate↗
PubMed1987

Enzymic detection of adhesion of enteropathogenic Escherichia coli to HEp-2 cells.

We established a new method for detecting enteropathogenic Escherichia coli adhering to HEp-2 cells. An essential part of the method is an assay of beta-galactosidase activity of adhered bacterial cells. It consisted of the following steps: (1) culture of bacterial cells in a medium containing isopropyl-thio-beta-D-galactoside, an inducer of beta-galactosidase; (2) incubation of a bacterial culture with monolayered HEp-2 cells in a 96-well culture plate; (3) washing wells to remove bacterial cells which did not adhere to HEp-2 cells, and (4) enzymic reaction for beta-galactosidase activities. However, a calibration curve for the enzyme activity, obtained from each bacterial sample, showed that 10(5) bacteria per well permitted an accurate estimation. The enzyme activity of adhered bacteria to the monolayered cells showed that 10(7) bacteria were appropriate for the adherence assay. The number of adhered bacteria thus obtained was in good agreement with a viable cell count. The result indicates that the new method is more reliable than a widely used method, counting the number of bacteria under a microscope. The present method also makes it easy to detect adherent strains of E. coli in large numbers of specimens.

Bacterial Adhesion↗
PubMed1987

Monoclonal antibodies to human erythrocyte membrane Ca++-Mg++ adenosine triphosphatase pump recognize an epitope in the basolateral membrane of human kidney distal tubule cells.

Human calcium transporting tissues were examined to determine whether they contained a protein similar to the Ca++-Mg++ adenosine triphosphatase (Ca++-Mg++ATPase) pump of the human erythrocyte membrane. Tissues were processed for immunoperoxidase staining using monoclonal antibodies against purified Ca++-Mg++ATPase. In human kidneys, specific staining was found only along the basolateral membrane of the distal convoluted tubules. Glomeruli and other segments of the nephron did not stain. Staining of erythrocytes in human spleen was readily observed. Human small intestine, human parathyroid, and human liver showed no antigens that crossreacted with the antibodies to Ca++-Mg++ATPase. Specific staining of distal tubule basolateral membranes from the kidney of a chimpanzee was also noted. Our experiments show, for the first time, that basolateral membranes of the human distal convoluted tubule contain a protein that is immunologically similar to the human erythrocyte Ca++-Mg++ATPase. These observations suggest that the cells of the distal convoluted tubules of human kidney may have a calcium pump similar to that of human erythrocyte membranes.

Animals↗
PubMed1984

Quantitative analysis of the production of heat-labile enterotoxin by enterotoxigenic Escherichia coli.

A modified method of passive immune hemolysis (PIH) was applied to the quantitative assay of heat-labile enterotoxin (LT) produced by enterotoxigenic Escherichia coli. The method enabled the measurement of 0.2 to 1.2 ng LT. The production of LT by enterotoxigenic E. coli under various conditions was analyzed using the modified method. LT production was intense during the logarithmic growth phase and decreased during the stationary growth phase. Lincomycin (50 to 100 micrograms/ml) affected cell growth slightly, but enhanced production of LT until the late-stationary growth phase. About 90% of the LT produced was retained in the cell, and the rest was excreted into the culture medium. The initial pH of the culture medium affected LT production. Alkaline pH enhanced LT production, though growth was depressed. Aeration enhanced both growth and LT production.

Aerobiosis↗
PubMed1983

Inhibition of phagocytosis by erythrocyte membrane sialoglycoprotein on target liposomes.

Sialoglycoprotein (GP) of human erythrocytes was incorporated into liposomes and its effect on the Fc receptor-mediated phagocytic reaction of human PMN cells was examined. Whereas liposomes carrying 2,4-dinitrophenylated lipid were, upon opsonization with rabbit anti-DNP, readily ingested by PMN cells and induced the NBT-reducing reaction, these reactions were markedly suppressed when GP was incorporated into the target liposomes. The inhibitory activity was found in the glycophorin A and B fractions, but the latter was more active than the former on a weight basis. It was estimated that incorporation of only a single molecule of GP per vesicle of 6000 lipid molecules may be sufficient to protect the particle from phagocytosis, but there was an apparent antagonism between the suppressive GP and opsonizing antibody as, with more antibody, more GP became necessary to inhibit phagocytosis. The effect of GP was largely abolished by trypsin treatment of GP-bearing liposomes or by the addition of F(ab')2 of anti-GP.

Dose-Response Relationship, Immunologic↗
PubMed1982

Effects of thiamin on vitamin B6 synthesis in yeasts.

The effects of exogenous thiamin on the growth yield and vitamin B6 content of 18 strains of yeasts and a few strains of bacteria were examined. The addition of thiamin hardly affected the growth yield of the yeasts tested, except for two strains Saccharomyces uvarum strain 4228 and Saccharomyces uvarum IFO 0751. In contrast, the vitamin B6 content of all the yeasts tested, except Pichia membranaefaciens IFO 0189, decreased markedly in the presence of thiamin. In S. uvarum IFO 1265, the synthesis of vitamin B6 was maximally inhibited by the addition of thiamin (1.5 nmol ml-1) to the growth medium without affecting cell growth, whereas the amounts of cellular vitamin B6 increased in the presence of the thiamin antagonist, pyrithiamin or oxythiamin, at concentrations that did not affect growth. When [4'-14C]pyridoxine. HCl (0.5 micrograms ml-1) was added to the growth medium at least 54% of the added isotope was incorporated into the cells during 24 h incubation. In the presence of thiamin (15 nmol ml-1), at least 32% of the added isotope was incorporated. The metabolism of [4'-14C]pyridoxine. HCl to inactive forms having no vitamin B6 activity was not stimulated by the addition of thiamin. Thus, vitamin B6 synthesis in many yeasts was affected by thiamin, whereas, in bacteria, growth yield and vitamin B6 content were not affected by thiamin.

Bacillus subtilis↗
PubMed1977

Studies on the bacterial spore coat 6 effects of alkali extraction on the spore of Bacillus thiaminolyticus.

Thin sections of the spore of Bacillus thiaminolyticus Matsukawa and Misawa show a characteristic surface structure with five ridges, and a series of three district layers. The outer layer of the spore coat was peeled off by SDS sonic treatment, and than the middle layer was solubilized by alkali extraction of the SDS sonic-treated spore. The spores subjected to these treatments were still refractile, heat resistant, and contained dipicolinic acid, but lost their resistance to mechanical shock.

Antigens, Bacterial↗
PubMed1977

Studies on the bacterial spore coat. 6. Effects of alkali extraction on the spore of Bacillus thiaminolyticus.

Thin sections of the spore of Bacillus thiaminolyticus Matsukawa and Misawa show a characteristic surface structure with five ridges, and a series of three distinct layers. The outer layer of the spore coat was peeled off by SDS sonic treatment, and then the middle layer was solubilized by alkali extraction of the SDS sonic-treated spore. The spores subjected to these treatments were still refractile, heat resistant, and contained dipicolinic acid, but lost their resistance to mechanical shock.

Bacillus↗
PubMedDate not supplied

Assessment of QT interval and QT dispersion following stellate ganglion block using computerized measurements.

BACKGROUND AND OBJECTIVES: Prolongation of QT interval and QT dispersion (QTD) may be associated with an increased risk of arrhythmias. This study was designed to investigate the effects of right or left stellate ganglion block (SGB) on RR interval, QT interval, the rate-corrected QT (QTc) interval, QTD and the rate-corrected QTD (QTcD) using computerized measurements. METHODS: Ten healthy volunteers underwent both right and left SGBs using 7 mL 1% mepivacaine with a 7-day interval between the 2 blocks. The measurement from the 12-lead electrocardiogram was performed for 60 minutes after SGB. RESULTS: Right SGB induced a significant decrease of RR interval immediately after the block, and significant increases of QT interval, QTc interval, QTD, and QTcD from immediately through 50 minutes after the block (P <.01). Left SGB induced a significant decrease of RR interval, and significant increases of QTc interval and QTD immediately after the block (P <.01). Left SGB also produced a significant decrease of QT interval from 20 through 50 minutes after the block, and a significant decrease of QTc interval from 30 through 50 minutes after the block (P <.05). CONCLUSIONS: Right SGB induces increases of the QT interval, QTc interval, QTD, and QTcD, and left SGB induces decreases of the QT interval and QTc interval.

Adult↗
PubMedDate not supplied

Comparison of the effects of amlodipine and losartan on 24-hour ambulatory blood pressure in hypertensive patients.

Effects of amlodipine (AML), a long-acting calcium antagonist, and losartan (LOS), an angiotensin II receptor antagonist, on 24-hr blood pressure profile were compared in 15 patients with essential hypertension. After 4 weeks of placebo period, the patients were treated with AML or LOS in a random crossover design for 12-16 weeks each. Either drug was given once daily at 0800 and the doses were titrated so that the office blood pressure was reduced lower than 140/90mmHg. At the end of each period, 24-hr blood pressure was monitored. Average office blood pressure was lowered from 158 +/- 2/ 98 +/- 2 mmHg to 134 +/- 1/87 +/- 1 mmHg by AML and 134 +/- 2/88 +/- 1 mmHg by LOS. Average 24-hr blood pressure was also reduced from 144 +/- 3/ 92 +/- 2 mmHg to 131 +/- 2/84 +/- 2 mmHg by AML and 135 +/- 3/85 +/- 2 mmHg by LOS. The averaged 24-hr systolic blood pressure was significantly lower in AML than in LOS (p < 0.05). Then, the 24-hr blood pressure was analyzed for four segments; morning (0530-0900 h), daytime (0930-1800 h), evening (1830-2300 h) and night (2330-0500 h). Although the daytime blood pressure was comparable between AML and LOS, systolic blood pressure in the evening and morning hours were lower in AML than in LOS (133 +/- 2 vs. 138 +/- 3mmHg,p<0.01; 129 +/- 3 vs. 134 +/- 4,p<0.05). Troughtopeakratio of antihypertensive effect on systolic blood pressure was significantly greater in AML than in LOS (62 +/- 5% vs. 55 +/- 4%, p < 0.05). Either drug did not cause reflective increase in pulse rate over 24 hours. These results suggest that both AML and LOS are equally effective in lowering daytime blood pressure without eliciting reflex tachycardia, however, the antihypertensive effect of AML lasts longer than that of LOS. Such information seems important to achieve 24-hr blood pressure control using these drugs.

Adult↗
PubMedDate not supplied

Effects of amlodipine and nifedipine retard on autonomic nerve activity in hypertensive patients.

1. The effects of 1,4-dihydropyridine calcium antagonists with different biological half-lives, amlodipine and nifedipine retard on 24 h blood pressure (BP), heart rate (HR) and autonomic nerve activity in patients with essential hypertension were compared. 2. Twenty patients (six men and 14 women; mean (+/- SEM) age 63 +/- 2 years) with essential hypertension were enrolled in the present study. Their ambulatory BP and electrocardiograms were monitored for 24 h at intervals of 30 min with a portable recorder after a 4 week drug-free period, after a 4 week treatment period with amlodipine (2.5 or 5 mg once daily) and after a 4 week treatment period with nifedipine retard (10 or 20 mg twice daily). The order of the three periods was randomized. Autonomic nerve activity was evaluated by power spectral analysis of HR variability, using the high frequency (HF) component as an index of parasympathetic activity and the ratio of the low frequency (LF) to the HF component as an index of sympathovagal balance. 3. Amlodipine and nifedipine retard significantly lowered the 24 h BP to a similar extent (amlodipine: -12.7 +/- 2.6/-5.6 +/- 1.4 mmHg, P < 0.01/P < 0.01; nifedipine retard: -15.1 +/- 2.1/-6.9 +/- 1.5 mmHg, P < 0.01/P < 0.01). Amlodipine did not change the 24 h average HR, while nifedipine retard significantly increased it (+3.3 +/- 1.2 b.p.m., P < 0.05). Amlodipine also did not change the HF component or the ratio of the LF to the HF component. However, nifedipine retard significantly decreased the HF component (P < 0.01) and increased the ratio of the LF to the HF component (P < 0.05). 4. These results suggest that nifedipine retard caused a decrease in parasympathetic activity and an increase in sympathetic activity with reflex tachycardia in these patients with essential hypertension, while amlodipine did not produce such effects on the autonomic nervous system.

Amlodipine↗