Search PubMed⌕ Search

Biomedical subjects

H Terada

Publications and source records attributed to H Terada.

At least 145 records · Page 8Linked to original sources
PubMed1994

Simultaneous measurement of [Na+]i and Ca2+ transients in an isolated myocyte: effects of strophanthidin.

We have developed a new method to measure [Na+]i and Ca2+ transients of a beating cardiac myocyte using a Na(+)-sensitive fluorescent probe, sodium-binding benzofuran isophthalate (SBFI) and a Ca(2+)-sensitive fluorescent probe, fluo-3. There was no interaction between two probes, and the artifact due to contraction could be eliminated in the measurement of [Na+]i. [Na+]i in guinea pig ventricular myocytes stimulated at 1 Hz was 8.0 +/- 0.7mM. Strophanthidin (10 microM), initially, increased the amplitude and the basal level of Ca2+ transients in association with an increase in [Na+]i. When arrhythmias were induced, the amplitude of Ca2+ transients decreased while [Na+]i and the basal level of Ca2 transients continued to increase. These results suggested that the diastolic [Ca2+]i was closely related to [Na+]i. However, the systolic [Ca2+]i, which could be influenced by other factors, was dissociated from [Na+]i in the condition of Ca2+ overload.

Aniline Compounds↗
PubMed1994

The role of Na+/H+ exchange and the Na+/K+ pump in the regulation of [Na+]i during metabolic inhibition in guinea pig myocytes.

To investigate the mechanisms of Na+ loading during metabolic inhibition (MI), [Na+]i and pHi were measured in quiescent guinea pig myocytes using fluorescent probes, sodium-binding benzofuran isophthalate and 2,7,bis(carboxyethyl)-5,6-carboxyfluorescein. When myocytes were exposed to MI (3.3 mM amobarbital and 5 microM carbonyl cyanide m-chlorophenylhydrazone, without glucose) for 20 min, [Na+]i increased from 8.3 +/- 0.7 mM to 17.7 +/- 1.3 mM (p < 0.01) and pHi decreased from 7.22 +/- 0.03 to 7.00 +/- 0.04 (p < 0.05). The inhibition of Na(+)-H+ exchange by hexamethylene amiloride (HMA) significantly attenuated the increase in [Na+]i during MI (9.3 +/- 0.9 mM; p < 0.01 vs MI without HMA). When a K(+)-free solution was perfused to inhibit the Na+/K+ pump in the presence of HMA, there was an immediate increase in [Na+]i during MI. Perfusion of a K(+)-free solution after 10 min of MI caused no change in the rate of the increase in [Na+]i. We concluded that 1) Na+/H+ exchange was an important mechanism for Na+ elevation during MI, and 2) the Na+/K+ pump was functional during the early phase of MI, but was inhibited 10 min after MI in this model.

Amiloride↗
PubMed1994

Importance of loops of mitochondrial ADP/ATP carrier for its transport activity deduced from reactivities of its cysteine residues with the sulfhydryl reagent eosin-5-maleimide.

The effects of various compounds such as the transport substrate ADP and the transport inhibitors carboxyatractyloside (CATR) and bongkrekic acid (BKA) on the labeling of cysteine residues in the ADP/ATP carrier of bovine heart submitochondrial particles by the SH reagent eosin-5-maleimide (EMA) were studied. Of the four cysteine residues in the carrier, the labeling of Cys159 by EMA progressed predominantly and rapidly, and those of Cys56 and Cys256 moderately, but Cys128 was not labeled, as we reported previously [Majima, E., et al. (1993) J. Biol. Chem. 268, 22181-22187]. ADP inhibited the labelings of Cys56, Cys159, and Cys256 by EMA. BKA markedly inhibited the labeling of Cys159 by EMA, and also the labeling of Cys256, but did not affect the labeling of Cys56, suggesting that it binds from the matrix side to a region close to Cys159 in the second loop facing the matrix space. CATR completely inhibited the labeling by EMA when added on the cytosolic side, but had no effect when added on the matrix side. From these results, the conformational changes of the carrier induced by CATR, BKA, and ADP are discussed. Furthermore, a mechanism of adenine nucleotide transport through the ADP/ATP carrier in association with change in its conformation is proposed.

Adenine Nucleotides↗
PubMed1994

Normal differentiation of rat brown adipocytes in primary culture judged by their expressions of uncoupling protein and the physiological isoform of glucose transporter.

We examined the effects of dexamethasone (DEX) on the expressions of key proteins concerned with energy metabolism in brown adipocytes during their differentiation in primary culture. Transcripts of the uncoupling protein (UCP), lipoprotein lipase (LPL) and CCAAT enhancer binding protein alpha (C/EBP alpha) genes were observed in brown adipocytes cultured in the presence of insulin and thyroid hormones but in the absence of DEX. However, the mRNA level of UCP decreased with the culture period after confluence, and significant mRNA encoding type-1 glucose transporter (GLUT1) was detected in brown adipocytes cultured without DEX, whereas type-4 glucose transporter (GLUT4) was predominantly expressed in mature brown adipocytes in vivo. In contrast, DEX added after confluence consistently elevated the mRNA levels of UCP, LPL and C/EBP alpha, and repressed the level of GLUT1 in a manner synchronized with increase in the level of GLUT4. Therefore, it is concluded that DEX as well as insulin and thyroid hormones is essential for differentiation of brown adipose precursor cells into mature cells that are similar to brown adipocytes in vivo.

Adipocytes↗
PubMed1994

Steady state transcript levels of the type II hexokinase and type 1 glucose transporter in human tumor cell lines.

The steady state transcript levels of two hexokinase isozymes and type 1 glucose transporter in human tumor cell lines were analyzed. In HepG2 cells, both type II hexokinase and type 1 glucose transporter were highly expressed. However, in cell lines A431 and HeLa, in which the expression level of type 1 glucose transporter was lower than that in HepG2 cells, the amount of type II hexokinase transcript was almost negligible.

Amino Acid Sequence↗
PubMed1994

Significant stabilization of the phosphatidylcholine bilayer structure by incorporation of small amounts of cardiolipin.

The effects of the negatively charged phospholipid cardiolipin on the structural properties of egg-yolk phosphatidylcholine (EyPC) liposomal membranes were studied by monitoring the water permeability of the liposomes caused by osmotic shrinkage in hypertonic glucose solution. Incorporation of small amounts of bovine heart cardiolipin (BhCL) into the EyPC membranes caused a significant decrease in their water permeability associated with stabilization of the membrane structure. Much evidence obtained by attenuated total reflection IR spectroscopy suggested that incorporation of BhCL into the EyPC membranes causes a cooperative conformational change in the EyPC polar head groups, but does not alter the fluidity of the bilayer structure in the fluid liquid crystalline state. Incorporation of small amounts of BhCL stabilized the intermolecular hydrogen-bonded network including water molecules of the hydration layers at the bilayer surface that are important for the stable bilayer configuration of the EyPC molecules. The antisymmetric PO2- frequencies of the EyPC membrane with incorporated BhCL suggested that the BhCL content of 50 mol% induced a change in the phase behaviors of mixed BhCL/EyPC membranes.

Animals↗
PubMed1994

Structural basis of potent antiperoxidation activity of the triterpene celastrol in mitochondria: effect of negative membrane surface charge on lipid peroxidation.

The structural basis of the potent inhibitory effect of the triterpene celastrol on lipid peroxidation of rat liver mitochondria initiated by adenosine 5'-diphosphate (ADP) and Fe2+ was studied in comparison with the effects of its analogs, pristimerin and acetylcelastrol. The dienone-phenol moiety and the anionic carboxyl group of celastrol were concluded to be important for their antiperoxidative action: The former moiety directly scavenges radicals and the latter donates the membrane with a negative surface charge, making it more resistant to peroxidation. Celastrol is suggested to inhibit the peroxidation of the outer and inner mitochondrial membrane by direct radical scavenging, and also to prevent the attack of oxygen radicals on the inner membrane by increasing its negative surface charge.

Adenosine Diphosphate↗
PubMed1994

Simultaneous measurement of intracellular Na+ and Ca2+ during K(+)-free perfusion in isolated myocytes.

To study the relationship between intracellular Na+ concentration ([Na+]i) and intracellular Ca2+ concentration ([Ca2+]i), guinea pig ventricular myocytes were loaded with both the Na(+)-sensitive probe, sodium-binding benzofuran isophthalate (SBFI), and the Ca(2+)-sensitive probe, fluo 3. [Na+]i was measured from the ratio image at 510 nm when excited at 340/380 nm. [Ca2+]i, expressed as the percent change of corrected fluo 3 fluorescence, was measured at 540 nm when excited at 500 nm. The fluorescent spectra of these probes were sufficiently different to allow for simultaneous measurement. After 30 min perfusion of K(+)-free solution, [Na+]i of rod-shaped cells increased from 6.4 +/- 0.5 to 20.6 +/- 2.6 mM, and [Ca2+]i increased to 256 +/- 36% of the control. [Ca2+]i was higher in spontaneously contracting cells and shortened cells than in rod-shaped cells at similar levels of [Na+]i. When Ca(2+)-free solution or Ni2+ (5 mM) was applied, [Ca2+]i was lower than in cells perfused with K(+)-free solution alone. It was suggested that extracellular Ca2+ and the Na(+)-Ca2+ exchange were involved in the increase in [Ca2+]i. In conclusion, we have developed a new method for the simultaneous measurement of [Na+]i and [Ca2+]i in isolated myocytes, which should be useful to study the relation between [Na+]i and [Ca2+]i.

Aniline Compounds↗
PubMed1994

Regulation of [Na+]i and [Ca2+]i in guinea pig myocytes: dual loading of fluorescent indicators SBFI and fluo 3.

To investigate the mechanisms regulating intracellular Na+ and Ca2+ concentrations ([Na+]i and [Ca2+]i, respectively), we monitored both ion concentrations simultaneously using fluorescent probes, Na(+)-binding benzofuran isophthalate (SBFI) and fluo 3, in unstimulated guinea pig ventricular myocytes. After the addition of 500 microM strophanthidin, [Na+]i increased gradually from 6.6 +/- 0.6 to 20.1 +/- 1.6 mM (mean +/- SE) at 50 min. [Ca2+]i, expressed as the percentage change of corrected fluo 3 fluorescence, was kept at the low level during the first 20 min and then began to increase to 447 +/- 81% of the control at 50 min. The addition of 1 microM hexamethylene amiloride prevented the increases in both [Na+]i and [Ca2+]i. The perfusion of Ca(2+)-free solution or 5 mM Ni(2+)-containing solution suppressed the increase in [Ca2+]i. In cells that exhibited spontaneous contractile activities, [Ca2+]i increased further than that in quiescent cells, whereas [Na+]i levels were similar. In the presence of 1 microM ryanodine, both the spontaneous contractile activities and the further increase in [Ca2+]i were eliminated. These findings indicated that 1) the pathway of Na+ entry was mainly through Na(+)-H+ exchange and that the elevated [Na+]i induced Ca2+ entry mediated by the reverse mode of Na(+)-Ca2+ exchange, and 2) the entered Ca2+ triggered the ryanodine-sensitive Ca2+ release from the sarcoplasmic reticulum, causing the dissociation in the relationship between [Na+]i and [Ca2+]i.

Amiloride↗
PubMed1994

Fungal metabolites. X. The effect of peptide antibiotics, trichosporin-Bs, on the respiratory activity of mitochondria.

The effect of the trichosporin-Bs, peptide antibiotics, on the respiration of mitochondria was investigated. Trichosporin-Bs stimulated the respiratory rate of state 4 rat liver mitochondria in a dose-dependent manner. The maximum respiratory rate obtained by trichosporin-Bs was essentially the same as for 2,4-dinitrophenol and SF6847. Trichosporin-B-VIb released oligomycin-inhibited respiration of mitochondria. This means that trichosporin-Bs are uncouplers of oxidative phosphorylation. The stimulatory effect of trichosporin-B-VIb, a component of trichosporin-Bs, on mitochondrial respiration was increased by inorganic phosphate but not by other permeant anions studied. These results suggest that the stimulation of mitochondrial respiration by trichosporin-B-VIb is mediated by the same mechanism as is operating in the case of hypelcins and alamethicins. Furthermore, the relative potencies of trichosporin-Bs on the mitochondrial respiration and their relative hydrophobicities were examined. A clear relationship was observed between the uncoupling potencies of trichosporin-Bs and their relative hydrophobicities.

2,4-Dinitrophenol↗
PubMed1994

Ca2+ waves and intracellular Ca2+ concentration in guinea pig and rat myocytes.

We measured [Ca2+]i of guinea pig and rat myocytes with Ca2+ waves, using fura-2 fluorescence image processing. In guinea pig myocytes, Ca2+ waves were absent during the control perfusion period, but could be induced by the addition of strophanthidin (100 microM) or sodium cyanide (NaCN: 2 mM) to the perfusate. The [Ca2+]i increased from the control values of 69 +/- 5 nM and 46 +/- 2 nM, to 263 +/- 9 (p < 0.05 vs. control) nM and 225 +/- 20 (p < 0.05) nM, respectively, when cells exhibited Ca2+ waves. Although 13% (16 of 121) of the rat myocytes displayed Ca2+ waves during the control perfusion, the [Ca2+]i with Ca2+ waves (56 +/- 9 nM) did not differ from [Ca2+]i in the absence of Ca2+ waves (54 +/- 3 nM). Ca2+ waves were induced by the perfusion with a high Ca2+ solution (24.5 microM) or NaCN (2 microM), and [Ca2+]i increased from the control values of 67 +/- 11 nM and 74 +/- 5 nM, to 231 +/- 41 (p < 0.05 vs. control) nM and 266 +/- 64 nM, respectively, when cells exhibited Ca2+ waves. The Ca2+ waves were abolished by the removal of extracellular Ca2+, or by the perfusion with ryanodine (10 microM) or caffeine (20 mM). In conclusion, it was shown that Ca2+ waves were due to oscillatory Ca2+ release and that the absolute value of [Ca2+]i is important for the appearance of Ca2+ waves in guinea pig and rat myocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Malignant pleural mesothelioma presenting as achalasia.

A 65-year-old man with an occupational history of asbestos exposure developed dysphagia and vomiting. Clinical examinations at onset revealed a dilated esophagus with smooth narrowing at the gastroesophageal junction and no apparent tumor in and around the esophagus. Achalasia was suspected. Dysphagia progressed gradually and examinations performed three months after the onset disclosed a tumor in the pleural and the peritoneal cavities. At laparotomy, the tumor extended from the pleural cavity into the peritoneal cavity. Histological examination of the biopsied specimen demonstrated malignant mesothelioma. We report the first case of malignant pleural mesothelioma presenting as achalasia.

Aged↗
PubMed1994

Infective endocarditis caused by an indigenous bacterium (Gemella morbillorum).

A case of infective endocarditis (IE) caused by a rare pathogen, Gemella morbillorum, is presented. Because of persistent low-grade fever after dental treatment, the patient was given oral antibiotics. Whereas he was diagnosed as having aortic regurgitation by a cardiologist, and IE was not suggested unfortunately. After long-term chemotherapy over five months, he was aware of nocturnal dyspnea and Gemella morbillorum was detected by blood culture. Then, he was treated with intravenous administration of Penicillin-G, and underwent surgical operation for valve replacement. No cases of IE due to this organism have been reported in Japan.

Endocarditis, Bacterial↗
PubMed1994

[The effect of subcutaneous administration of buprenorphine with patient controlled analgesia system for post-operative pain relief].

We conducted a study comparing patients receiving continuous subcutaneous administration of analgesia with self controlled analgesia system (CSAA group) with those receiving continuous epidural infusion (Epi group) for postoperative analgesia after abdominal surgery. Fourteen patients were randomized into two groups: CSAA group (n = 7) received 20 micrograms.h-1 of buprenorphine (Bu) subcutaneously with additional 20 micrograms of Bu using Baxter infusor BB+PCA; Epg group (n = 7) received continuous epidural infusion of 0.4 mg of Bu and 46 ml of 0.25% bupivacaine daily (16.7 micrograms.h-1 of Bu) using Baxter infusor 2 ml.h-1 type. In both groups, patients received supplemental 0.1 mg of Bu subcutaneously as needed. During 48-hour postoperatively, verbal descriptor pain scale, sedative scale, visual analogue scale, supplemental doses of Bu, and side effects were evaluated. There was no significant difference of verbal descriptor pain scale, sedative scale, visual analogue scale, and supplemental doses of Bu between CSAA group and Epi group. Total doses of Bu during the first 12 hours postoperatively (CSAA group: 0.37 +/- 0.08 mg, Epi group: 0.30 +/- 0.08 mg) were significantly more than those during other 12-hour period in both groups (P < 0.05). There was no severe side effect in both groups. We conclude that continuous subcutaneous administration of analgesic was effective for postoperative analgesia, and almost the same analgesic effect was obtained as compared with continuous epidural analgesia. We calculated that the adequate dose of Bu subcutaneously during early postoperative period to be about 30 micrograms.h-1 of Bu.

Aged↗
PubMed1994

Studies on in vitro paraquat and diquat removal by activated carbon.

The adsorption characteristics of paraquat and diquat onto activated carbon in vitro were discussed for the primary treatment of acute poisoning by accidental, suicidal or homicidal ingestion of paraquat containing herbicides. Paraquat was adsorbed onto activated carbon more abundantly and more rapidly in physiological saline solution than that in artificial gastric juice and distilled water. Most suitable solvent for paraquat removal by activated carbon was physiological saline solution (0.9% sodium chloride solution). No significant correlation was observed between the ability of paraquat removal and the properties of adsorbent. Paraquat was preferentially adsorbed onto activated carbon in the mixed solution. The adsorption abilities by activated carbon (the removal ratio, the amount adsorbed and the adsorption rate) for paraquat were larger than those for diquat, and it was enhanced by added sodium chloride and added magnesium sulfate. Enhancing effect for adsorption removal was proportional to the saline concentration. As addition of salts into carbon suspension enhanced the adsorption ability, it will contribute to the effective treatment of acute poisoning.

Adsorption↗
PubMed1994

[Effects of midazolam as intramuscular premedicant administered 15 and 30 min before induction of anesthesia].

We compared effects of midazolam as intramuscular premedicant on hypnosis, sedation and antegrade amnesia when administered 15 (32 cases) and 30 (35 cases) min before induction of anesthesia. Hypnosis was obtained in 97 and 91%, and sedation in 97 and 100% of patients administered midazolam 15 and 30 min before induction, respectively. Antegrade amnesia was observed in 97 and 72% of patients administered midazolam 15 and 30 min before, respectively (statistically significant). If midazolam is administered 15 min before, the respiratory depression, one of its unacceptable side effects, may hardly occur because patient arrives operating room before its onset. We conclude that the appropriate time for administration of midazolam as intramuscular premedicant is 15 min, rather than 30 min, before the induction of anesthesia.

Adult↗
PubMed1994

[A quantitative approach to the rCBF response to acetazolamide using 99mTc-HMPAO and graphical analysis].

A simple noninvasive method for a quantitative measurement of brain perfusion is presented using intravenous radionuclide angiography with 99mTc-hexamethylpropylene amine oxime (HMPAO). Graphical analysis was employed for the evaluation of the unidirectional influx constant (ku) of the tracer from the blood to the brain and the initial distribution volume (Vn) for the tracer, which is the volume of the exchangeable region plus the plasma space. The ku and Vn values were standardized to provide objective and comparable values, brain perfusion indices (BPI) and corrected Vn (Corr. Vn), between subjects by setting the size ratio of ROI(brain) to ROI(aorta) at 10 and 1, respectively. BPI and Corr. Vn of the whole brain were measured before and 20 min after injection of 1 g acetazolamide. After acetazolamide administration, BPI and Corr. Vn increased in all eight subjects with cerebrovascular diseases and one with a pituitary adenoma, by a mean of x 1.26 and 1.24, respectively. Increase of BPI showed a significant correlation with increase of Corr. Vn. This technique is easy to apply as an adjunct to SPECT and may be helpful in the measurement of brain perfusion changes in the acetazolamide test.

Acetazolamide↗