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H Okino

Publications and source records attributed to H Okino.

At least 19 recordsLinked to original sources
PubMed1992

The failure of radical scavengers to attenuate the incidence of reperfusion arrhythmias despite improvement of cardiac function.

We studied the concomitant effects of scavengers of reactive oxygen species (ROS) on both cardiac function and the incidence of arrhythmias. Isolated rat heart was perfused with a working mode paced at 300 beats/min. The left coronary artery was occluded for 5, 7, 15, or 60 min and reperfused thereafter for 30 min. Superoxide dismutase and catalase were infused from 5 min prior to reperfusion to the end of reperfusion in the scavenger treatment group. In the 60-min ischemia group with scavenger treatment, the cardiac output was significantly higher than that in the untreated group at both 10 and 30 min of reperfusion (P less than 0.01). In the 15-min ischemia group with scavenger treatment, the cardiac output showed a tendency toward a higher value than that in the untreated group. The incidence of reperfusion arrhythmias occurring after a short ischemic time (5, 7, or 15 min) were similar in the scavenger treated and untreated groups; but, with a preceding ischemia of 60 min, the incidence of ventricular tachycardia was higher in the scavenger treated group than in the untreated group (P less than 0.02). In conclusion, scavengers improved contractile dysfunction but did not attenuate the incidence of arrhythmias.

Animals↗
PubMed1992

Marked alternans of the elevated ST segment during occlusion of the left anterior descending coronary artery in percutaneous transluminal coronary angioplasty: clinical background and electrocardiographic features.

To investigate the clinical background and the electrocardiographic features of marked alternans of the elevated ST segment during coronary angioplasty, we examined 12-lead electrocardiograms recorded continuously during occlusion of the left anterior descending coronary artery by balloon inflation in 41 patients. The incidence of marked ST alternans was 27% of 41 patients and 15% of 117 balloon occlusions. The incidence decreased progressively from the first to the third occlusion. The time course of ST alternans was determined. Compared with patients without ST alternans, patients with ST alternans had a shorter history of angina, less severe stenosis of the target lesion before coronary angioplasty, more leads showing ST elevation during occlusion, higher ST elevation during occlusion and lower incidence of previous myocardial infarction in the left anterior descending coronary arterial area. ST alternans recorded on the surface electrocardiogram may thus be considered a marker of acute severe and extensive myocardial ischemia.

Adult↗
PubMed1992

New nonradioactive microspheres and more sensitive X-ray fluorescence to measure regional blood flow.

We developed new nonradioactive microspheres and used more sensitive X-ray fluorescence spectrometers than used previously to measure regional blood flow in the heart and other organs. We demonstrated the chemical stability of eight kinds of heavy element-loaded microspheres and validated their use for regional blood flow measurement by comparing duplicate flows measured with radioactive and/or nonradioactive microspheres in both acute and chronic dog experiments. The wavelength-dispersive spectrometer (Philips PW 1480) has a higher sensitivity than the previously described X-ray fluorescent system and reduced the number of microspheres required for accurate measurement. The fine energy resolution of this system makes it possible to increase the numbers of different kinds of microspheres to be quantitated, but at present only eight kinds are available. We also used a synchrotron radiation-excited energy dispersive spectrometer. The monochromatic synchrotron radiation allowed us to obtain much higher signal-to-background ratios of X-ray fluorescence spectra than with the wavelength-dispersive system (50 dB more for Zr-loaded microspheres) and will enable analysis of fluorescent activity in smaller regions (< 20 mg) than the radioactive method does.

Animals↗
PubMed1991

Investigation of the existence and biological role of L-arginine/nitric oxide pathway in human platelets by spin-trapping/EPR studies.

The aim of the present study was to apply spin trapping/EPR spectroscopy to investigate the existence and biological role of the L-arginine/nitric oxide pathway in human platelet aggregation. Three different spin traps were used: two nitroso, 3,5-dibromo-4-nitrosobenzenesulfonate (DBNBS) and 2-methyl-2-nitrosopropane (MNP), and a nitrone, 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The effect of spin-trap concentration on the collagen-induced human platelet aggregation was compared to the anti-aggregatory effect caused by L-arginine. The results show that the nitroso spin traps (DBNBS and MNP) are more effective than L-arginine in preventing platelet aggregation. DMPO has virtually no effect on the collagen-induced aggregation except at a high concentration (300 mM). Furthermore, activation of platelets with a low concentration of collagen (17 micrograms/ml) and in the presence of DBNBS or MNP yields several EPR-detectable spin adducts. Some of the observed spin adducts do not correspond to those originating from the interaction of a free radical, nitric oxide (NO.) gas, with the spin traps [Arroyo, C.M. & Kohno, M. (1991) Free Radical Res. Commun. 14, 145-155]. Only one adduct of DBNBS, with a relative intensity of 0.1, observed in the washed-platelet experiment and in the presence of superoxide dismutase, is similar to the EPR spectrum obtained following a reaction of pure NO. gas with DBNBS. This suggests that the EPR spectrum of the DBNBS adduct consisting of a triplet may originate from the production of NO. by these cells. Additional DBNBS and MNP spin adducts were generated during platelet activation in the presence of Ca2+ and of a cytosol-depleted L-arginine preparation from washed platelets to which L-arginine was subsequently added. The formation of these DBNBS and MNP spin adducts were inhibited by N omega-methyl-L-arginine (MeArg, 100 microM), suggesting that these originated from a product of NO synthase. Furthermore, the formation of DBNBS and MNP spin adducts in platelet suspensions was enhanced by the presence of superoxide dismutase; however, their formation was prevented by the endothelial-derived relaxing factor (EDRF) inhibitors methylene blue and hemoglobin. The results from the MeArg and EDRF inhibitor experiments support the existence of the L-arginine/NO pathway in platelets. In addition, the prevention of spin-adduct formation by EDRF inhibitors, suggests that the mechanisms of EDRF formation and the L-arginine/NO pathway in endothelial cells and platelets are similar.(ABSTRACT TRUNCATED AT 400 WORDS)

Arginine↗
PubMed1991

Amino acids responsible for flagellar shape are distributed in terminal regions of flagellin.

The shape of the flagellar filaments of the bacterium Salmonella typhimurium under ordinary conditions is a left-handed helix. In addition to the normal wild-type filament, non-helical (i.e. straight), right-handed helical (early), or circular (semi-coiled and coiled) filaments and filament with small amplitude (fl-type) have been found in mutants or in filaments reconstituted in vitro. We analysed wild-type flagellin and flagellins from 17 flagellar-shape mutants (6 with straight filaments, 6 with curly filaments, 4 with coiled filaments and 1 with fl-type filament) by amino acid sequencing to identify the mutational sites. All mutant flagellins except that of the fl-type filament had single mutations; the fl-type flagellin had two mutations in the molecule. The sites of these mutations were localized in alpha-helical segments of the terminal regions of flagellin. A possible mechanism of the polymorphism of the flagellar filament is discussed.

Amino Acid Sequence↗
PubMed1991

Effects of fura-2 and indo-1 on [Ca++]i in spontaneously beating cultured heart cells.

Changes in contractility and intracellular free Ca([Ca++]i) were measured in spontaneously beating cultured heart cells following exposure to indo-1 acetoxymethyl ester (indo-1AM) and fura-2 acetoxymethyl ester (fura-2AM). Although a 10 microM concentration of indo-1AM slightly decreased the beating rate, 5 and 10 microM concentrations of fura-2AM produced arrest of contraction within 10 min. However, contractility returned to normal after washing. With indo-1, the diastolic and peak systolic levels of [Ca++]i were 282 +/- 23 and 1107 +/- 122 nM, respectively, and 84 +/- 8 and 582 +/- 93 nM, respectively, with fura-2. The difference between the indo-1 and fura-2 generated responses are statistically significant (p less than 0.01). These results demonstrate that indo-1 and fura-2 can affect [Ca++]i, but the influence of indo-1 is less than that of fura-2 in the heart cells.

Animals↗
PubMed1990

Stoichiometric analysis of the flagellar hook-(basal-body) complex of Salmonella typhimurium.

The stoichiometries of components within the flagellar hook-(basal-body) complex of Salmonella typhimurium have been determined. The hook protein (FlgE), the most abundant protein in the complex, is present at approximately 130 subunits. Hook-associated protein 1 (FlgK) is present at approximately 12 subunits. The distal rod protein (FlgG) is present at approximately 26 subunits, while the proximal rod proteins (FlgB, FlgC and FlgF) are present at only approximately six subunits each. The stoichiometries of the proximal rod proteins and hook-associated protein 1 are, within experimental error, consistent with values of 5 or 6, and 11, respectively. Such values would correspond to either one or two turns of a helical structure with a basic helix of approximately 5.5 subunits per turn, which is the geometry of both the hook and the filament and, one supposes, the rod and hook-associated proteins. These stoichiometries may derive from rules for the heterologous interactions that occur when a helical structure consists of successive segments constructed from different proteins; the stoichiometries within the hook and the distal portion of the rod must, however, be set by different mechanisms. The stoichiometries for the ring proteins are approximately 26 subunits each for the M-ring protein (FliF), the P-ring protein (FlgI), and the L-ring protein (FlgH); the protein responsible for the S-ring feature is not known. The rings presumably have rotational rather than helical symmetry, in which case the stoichiometries would be directly constrained by the intersubunit bonding angle. The ring stoichiometries are discussed in light of other information concerning flagellar structure and function.

Amino Acid Sequence↗
PubMed1990

The detection of technical failures in perfused heart with ischemia and reperfusion by epicardial NADH fluorescence.

This study documents the value of continuous observation of nicotinamide adenine dinucleotide (NADH) fluorescence (NADH-F). NADH-F monitoring is used to identify ischemic regions for the recognition of minor technical failures associated with ischemia and reperfusion experiments in the isolated perfused heart system. The visualization of NADH-F is possible by simply irradiating the heart with ultraviolet light. Rat hearts, in the working-heart mode, were subjected to occlusion/reperfusion of the left coronary artery, and analyzed. The perfusate was filtered through a 5 micron pore membrane. Out of 281 hearts which were judged to be free of technical failures by conventional physiological indices (heart rate greater than 200/min, cardiac output greater than 34 ml/min, and coronary flow 9-14 ml/min), 43 (15%) disclosed an abnormal NADH-F area prior to the coronary intervention. During coronary intervention, 29 technical failures were detected as indicated by sparse NADH-F distribution with occlusion, delayed disappearance of NADH-F upon reperfusion, or the exhibition of an abnormal NADH-F region unassociated with the coronary artery supply area. These technical failures are not detectable without the use of NADH-F, although the actual number of failures detected may depend on the skill of the operator. We recommend NADH-F monitoring for any preparations which do not contain hemoglobin, since NADH-F is an intrinsic probe for ischemia and is easily applicable to a variety of experiments.

Animals↗
PubMed1990

Study on a new index of fetal respiratory function: a novel optical analysis of the amniotic fluid by the vacuum-dried infrared attenuated total reflection (ATR) method.

For the purpose of detecting fetal pulmonary maturity with real-time convenience but reliable accuracy, infrared spectrophotometry of amniotic fluid lipids was introduced using our newly developed optical device. The peak areas at the wave number of 1740 cm-1 on the infrared spectra (called "PA1740") were measured in 29 specimens sampled from 29 pregnant women, and compared with the Lecithin/Sphingomyelin (L/S) ratio of the same samples. Statistical analysis revealed that the PA1740 was almost as reliable as the L/S ratio, and these indices illustrated pulmonary immaturity in cases with a PA1740 less than 0.9 and an L/S ratio less than 2.0. PA1740 is absolutely independent of the effect on the concentration of lecithin in the amniotic fluid because of a combination of the vacuum-drying process and the absorbance correction, and can be completed in less than 20 minutes from sampling of the amniotic fluid by a very simple manipulation. In conclusion, the new index, PA1740, will be a more practical method for prediction of the fetal pulmonary maturity than methods such as the well known L/S ratio.

Amniotic Fluid↗
PubMed1990

[Platelet activation during thrombolysis and percutaneous transluminal coronary angioplasty in the acute phase of myocardial infarction].

To clarify the mechanism of recanalization and reocclusion in thrombolysis and percutaneous transluminal coronary angioplasty (PTCA), the plasma concentrations of beta-thromboglobulin (beta-TG), thromboxane B2 (TXB2) and platelet aggregation adenosine diphosphate (ADP) (2 microM/ml, collagen 2 micrograms/ml) were assessed in 11 normal subjects and in 19 patients with acute myocardial infarction whose infarct-related vessels were recanalized by thrombolysis and/or PTCA. In patients with acute myocardial infarction, the plasma concentrations of beta-TG and TXB2 were significantly higher than those in normal subjects (beta-TG: 128 +/- 132 ng/ml vs 38 +/- 17 ng/ml, TXB2: 131 +/- 154 pg/ml vs 36 +/- 18 pg/ml). Collagen-induced platelet aggregation decreased significantly in patients with acute myocardial infarction; whereas, ADP-induced platelet aggregation showed no significant difference. Infarct-related vessels recanalized by thrombolysis (seven patients: group 1) and PTCA (seven patients: group 2) were patent on the follow-up angiograms. Infarct-related vessels were reoccluded in five patients immediately after PTCA or during the follow-up angiography (group 3). Beta-TG and TXB2 did not change before and after recanalization in groups 1 and 2, but increased significantly after recanalization in group 3 (beta-TG: 155 +/- 185 ng/ml----269 +/- 233 ng/ml, TXB2: 104 +/- 87 pg/ml----169 +/- 91 pg/ml). Platelet aggregation did not differ significantly among the three groups. We concluded that platelets are not activated during thrombolysis and/or PTCA in cases without reocclusion, while platelets are markedly activated during PTCA in cases with reocclusion. Thus, it is suggested that platelet activation plays an important role in the mechanism of reocclusion.

Adenosine Diphosphate↗
PubMed1990

[Atrio-ventricular pressure difference associated with mitral valve motion].

Pressure difference (PD) across the mitral valve was analyzed by a computer-aided catheter system in dogs. Positive PD (PPD) was consistently traced in the initial phase of rapid filling. While heart rate (HR) was below 100 beat/min, a negative PD (NPD) followed the above PPD. In the period between the NPD and the 2nd PPD due to atrial contraction, PD was kept at zero, while LA and LV pressures were gradually elevated by pulmonary venous return. As HR exceeded 100, 2 positive peaks of PD merged into M-shaped or mono-peaked PD. Through higher inflow resistance produced by artificial mitral stenosis, PPD peak decayed without NPD. In mitral regurgitation with an acute volume overload, all of the PD amplitudes were exaggerated. Thus the quick reversal of PD suggested the effect in blood filling process across the mitral valve.

Animals↗
PubMed1989

Release of flagellar filament-hook-rod complex by a Salmonella typhimurium mutant defective in the M ring of the basal body.

A Salmonella typhimurium strain possessing a mutation in the fliF gene (coding for the component protein of the M ring of the flagellar basal body) swarmed poorly on a semisolid plate. However, cells grown in liquid medium swam normally and did not show any differences from wild-type cells in terms of swimming speed or tumbling frequency. When mutant cells were grown in a viscous medium, detached bundles of flagellar filaments as long as 100 microns were formed and the cells had impaired motility. Electron microscopy and immunoelectron microscopy revealed that the filaments released from the cells had the hook and a part of the rod of the flagellar basal body still attached. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis showed that the rod portion of the released structures consisted of the 30-kilodalton FlgG protein. Double mutants containing this fliF mutation and various che mutations were constructed, and their behavior in viscous media was analyzed. When the flagellar rotation of the mutants was strongly biased to either a counterclockwise or a clockwise direction, detached bundles were not formed. The formation of large bundles was most extreme in mutants weakly biased to clockwise rotation.

Bacterial Proteins↗
PubMed1989

Limitations in calculating left ventricular volume by two dimensional geometry--an exised canine heart study.

The left ventricle was removed from 76 dogs and was cast in silicone, in vitro, under three fixing pressure levels to simulate various end-diastolic pressures. This cast was designated as a silicone cast. The waxen cast was constructed by adding attachments which protrude inside the LV cavity, such as the papillary muscles and trabeculae carneae to the silicone cast. The cast volumes were compared with the volume calculated by the area-length method, including ellipsoid and paraboloid models, and by Chapman's method in which silhouettes of the silicone casts projected on 4 planes were used. Under a lower fixing pressure, the volume of papillary muscles and trabeculae carneae accounted for about 35% of the LV volume which was independent of either size of heart or weight of the dog. This ratio was reduced at higher fixing pressure levels. The relationship between the cast volume and the volume calculated by the silhouette method was linearly proportional. However, the deviation increased with higher fixing pressure levels and with larger ventricular volumes in all calculation methods, indicating the shape of the left ventricle cannot be represented by any ideal symmetrical spherical model. The calculated volume agreed with its corresponding cast volume with an error of less than 10% if either the fixing pressure level was below 5 mmHg, or the volume was less than 50 ml.

Animals↗
PubMed1988

Is superoxide demonstration by electron-spin resonance spectroscopy really superoxide?

A recent study has indicated that the generation of an oxygen radical in freeze-clamped myocardium on reperfusion can be directly demonstrated using electron-spin resonance spectroscopy (ESR). However, the results need to be analyzed with caution, since artifactual radicals are misleading problems common to this method. To test whether that reported superoxide is truly the biologically existing radical or an artifactual radical, we performed experiments using isolated, perfused rat and rabbit hearts and open-chest canine hearts subjected to ischemia/reperfusion. Radicals were freeze trapped at 77 degrees K, and ESR measurements were made. The ESR spectra exhibited four free radicals. Among these, two radicals which had been previously claimed as superoxide and a nitrogen-centered radical were shown as mechanically yielded artifactual radicals. These were produced by pulverization of the frozen sample. In artifact-free samples, superoxide could not be detected. The radicals native to the myocardium were identified as coenzyme Q10-. and another radical the species of which remains unclear.

Animals↗