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Biomedical subjects

H Toda

Publications and source records attributed to H Toda.

At least 109 records · Page 6Linked to original sources
PubMed1993

Direct vascular effect of ropivacaine in femoral artery and vein of the dog.

A study was conducted to examine the direct vascular effect of ropivacaine, in comparison with the effect of bupivacaine and lidocaine. Changes in tension induced by ropivacaine (10(-5)-3 x 10(-3) mol l-1) and lidocaine (10(-5)-10(-2) mol l-1) were examined cumulatively in vascular rings of dog femoral artery and vein under basal tension, or in those which had been precontracted with phenylephrine submaximally in Krebs' bicarbonate solution at 37 degrees C aerated with 95% O2 and 5% CO2 (pH 7.4). The change in tension induced by 10(-2) mol l-1 ropivacaine was tested under basal tension in vascular rings bathed in HEPES buffer (pH 6.8). Ropivacaine induced greater constriction than bupivacaine at concentrations over 10(-3) mol l-1 in vascular rings under basal tension (P < 0.01). The maximal contraction was induced by ropivacaine at 10(-3) mol l-1, averaging 51.5 +/- 2.8% (n = 11) and 27.0 +/- 3.7% (n = 12) of the maximal contraction induced by epinephrine in the artery and vein, respectively, and the contractions induced by ropivacaine at 10(-2) mol l-1 were 16.3 +/- 2.0% (n = 11) and 5.5 +/- 1.1% (n = 9), respectively. Phenylephrine (10(-6) mol l-1)-precontracted artery was contracted significantly by ropivacaine at 3 x 10(-4) mol l-1 and 10(-3) mol l-1, and by bupivacaine at 3 x 10(-4) mol l-1, whereas the phenylephrine (10(-6) mol l-1)-precontracted vein was relaxed by these anesthetics. Lidocaine did not exert constricting effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Amides↗
PubMed1993

Accommodative and pupillary responses to sinusoidal target depth movement.

We evaluated the accommodative and pupillary responses to sinusoidal target depth movement in 10 normal subjects and one patient by analysing frequency responses and associated Bode plots. The phase of the pupillary response significantly lagged behind that of accommodative response, which suggests that they are controlled by separate central nervous systems. We measured the baseline shift of each response trace using a regression line and found that they were larger at higher stimulation frequencies. A patient with severe asthenopia showed a considerable baseline shift in accommodative response. These analyses may be useful for the quantitative assessment of dynamic accommodation and pupillary response.

Accommodation, Ocular↗
PubMed1993

Differential activation of polymorphonuclear leukocytes from peripheral blood and exudate in surgical patients.

We examined the effects of surgical trauma on polymorphonuclear leukocyte (PMN) chemotaxis, production of phagocytosis-dependent intracellular chemiluminescence (CL) and production of phagocytosis-independent total CL in two groups: group A with esophageal cancer, and group B with gastric cancer. The scale of surgical trauma was quantified by measuring interleukin-6 in plasma and exudate from drainage tubes. We found a significant augmentation of chemotaxis, total CL and intracellular CL in both groups during the post-operative week. In group A, the increments in both chemotaxis and total CL of circulating cells were smaller than those in group B, but there was no significant difference in intracellular CL between the two groups. Exudate PMNs were more chemotactic, but produced smaller amounts of total CL than circulating cells. No significant difference in intracellular CL between exudate and circulating PMNs was detected, indicating that phagocytic activity was not affected. We conclude that severe surgical trauma causes circulating PMNs with high chemotactic activity to migrate to sites of injury, but that preactivated PMNs in exudate examined in vitro produce lower amounts of reactive oxygen metabolites in response to soluble chemoattractants in vitro than cells circulating in plasma.

Adult↗
PubMed1993

Myocardial infarct size can be estimated from serial plasma myoglobin measurements within 4 hours of reperfusion.

BACKGROUND: An early estimation of infarct size is useful for the appropriate early treatment of patients with acute myocardial infarction. We evaluated how early and how accurately infarct size could be estimated from serial plasma myoglobin (Mb) measurements in patients with successful reperfusion. METHODS AND RESULTS: We measured plasma Mb and creatine kinase (CK) in 35 patients in whom reperfusion therapy was successfully performed. Blood samples were collected at 15-minute intervals for 2 hours after reperfusion, at 30-minute intervals for the subsequent 2 hours, and at 3-6-hour intervals until 52 hours after reperfusion. Plasma Mb was measured by a newly developed turbidimetric latex agglutination assay. Total Mb and CK release (sigma Mb, sigma CK) were calculated with a one-compartment model. The mean chord motion in the most hypokinetic 50% of the infarct-related artery territory was calculated from follow-up ventriculograms as an index of the severity of regional hypokinesis. There were significant correlations between sigma Mb and sigma CK (r = 0.89), between log sigma Mb and the severity of regional hypokinesis (r = -0.85), and between log sigma CK and the severity of regional hypokinesis (r = -0.74). The time required for the cumulative Mb release curves to reach a plateau was 64 +/- 28 minutes. An additional 53 +/- 14 minutes was required to calculate the disappearance rate constant of Mb, and 15 minutes was necessary for the assay. Therefore, the total time required for sigma Mb to be available was 132 +/- 40 minutes, significantly shorter than the time required for sigma CK, 24.3 +/- 9.1 hours (p < 0.001). The infarct size could be estimated from the sigma Mb in 34 of 35 patients within 4 hours of reperfusion. CONCLUSIONS: Infarct size can be estimated accurately 4 hours after reperfusion by calculating the sigma Mb in patients with successful reperfusion.

Clinical Enzyme Tests↗
PubMed1992

A simple, rapid method for purification of epsilon-subunit, coupling factor 6, subunit d, and subunit e from rat liver H(+)-ATP synthase and determination of the complete amino acid sequence of epsilon-subunit.

The rat liver mitochondrial epsilon-subunit, coupling factor 6, subunit d, and subunit e of H(+)-ATP synthase, which are all extra subunits with no counterparts in Escherichia coli, were purified by reverse-phase high performance liquid chromatography. The complete amino acid sequence of the rat epsilon-subunit was determined by automated Edman degradation of the whole protein and derived peptides. The protein contains 50 amino acids and has a molecular mass of 5635 kDa. It is a basic hydrophilic protein with an isoelectric point of 10.5. The sequence of the rat epsilon-subunit is highly homologous with that of the epsilon-subunit of bovine heart and slightly similar to those of the epsilon-subunit of the yeast and sweet potato mitochondria. However, it has no homology with any subunit of bacterial or chloroplast H(+)-ATP synthase.

Amino Acid Sequence↗
PubMed1992

Amino acid sequence of calmodulin from Euglena gracilis.

The complete amino acid sequence of calmodulin from Euglena gracilis was determined by isolation and sequence analyses of peptides derived from calmodulin by digestion with trypsin and Staphylococcus aureus V8 protease. Euglena calmodulin consists of 148 amino acid residues; it lacks tryptophan and cysteine and contains one tyrosine, three histidine and two NE-trimethyllysine residues/molecule of the protein. Its N-terminus was blocked with an acetyl group and C-terminal lysine was trimethylated. Euglena calmodulin is the first calmodulin so far examined in which the C-terminal lysine is trimethylated. The comparison of amino acid sequences between Euglena and human brain calmodulins indicated 17 amino acid substitutions in Euglena calmodulin.

Amino Acid Sequence↗
PubMed1992

Protease inhibitors (gebexate mesylate and ulinastatin) stimulate intracellular chemiluminescence in human neutrophils.

The effect of protease inhibitors on the intracellular production of free radicals was investigated by measuring chemiluminescence (CL) elicited from phagocytosed luminol-bound microspheres (Lumispheres) in human neutrophils stimulated with formylmethionyl-leucyl-phenylalanine (fMLP), interleukin-8 (IL-8), phorbol 12-myristate 13-acetate, or diacylglycerol. Both gabexate mesylate (Foy) and ulinastatin (Miraclid), urinary trypsin inhibitor, increased intracellular CL in a dose dependent manner. Compared to control buffer without protease inhibitor, gabexate mesylate (322 micrograms/ml) caused about a 10-fold increase in intracellular CL in stimulated neutrophils, and ulinastatin (3100 U/ml) a twofold increase in neutrophils stimulated with fMLP or IL-8. When the protease inhibitors were added to the cell suspension after the phagocytosis of lumispheres, CL responses rapidly increased again to the level which was observed when both protease inhibitors and neutrophil stimulants were incubated simultaneously. In contrast, extracellular release of oxygen metabolites from stimulated neutrophils, assayed by a conventional measurement of luminol-dependent CL, was reduced by the protease inhibitors in a dose dependent fashion. When luminol-unbound microspheres were incubated with neutrophils stimulated by fMLP in luminol solution, extracellular CL was almost completely inhibited by gabexate mesylate. These results indicate that the protease inhibitors enhance the generation of intracellular CL and suppress the extracellular release of free radicals.

Dose-Response Relationship, Drug↗
PubMed1992

Functional roles of the lateral suprasylvian cortex in ocular near response in the cat.

The lateral suprasylvian (LS) area, an extrastriate visual area in the cat, has been suggested to play an important role in processing motion in 3-dimensional visual space. In addition, the LS area is related to all three components of the ocular near response, i.e. lens accommodation, pupillary constriction, and ocular convergence: microstimulation in this area evoked these intra- and extraocular movements, and neuronal discharges associated with these movements were also found. Anatomical pathways, direct and indirect, from this area to premotor nuclei in the brainstem are known to exist. The present paper reviews studies useful for assessing the functional roles played by the LS area in triggering and modulating component movements in the ocular near response.

Accommodation, Ocular↗
PubMed1992

Ocular convergence-related neuronal responses in the lateral suprasylvian area of alert cats.

Neuronal spike discharges were recorded from the lateral suprasylvian (LS) area while ocular convergence was elicited in five alert cats. Ocular convergence was elicited by presenting a visual target moving in depth. Cats were rewarded for convergence eye movement. In 9 out of 426 cells sampled in the caudal postero-medial LS area, the number of spikes was positively correlated with the peak eye velocities during ocular convergence. Significant correlation was found mostly within 400 ms preceding the moment at which the maximum velocity of ocular convergence was obtained. The result favors the hypothesis that the LS area plays an important role in the integrative control of ocular convergence.

Animals↗
PubMed1992

Circulating interleukin 6 as a useful marker for predicting postoperative complications.

We examined postoperative serial changes in the levels of serum interleukin 6 (IL-6), serum acute phase reactants (APRs) and plasma neutrophil elastase (NE) in patients with various cancers and reviewed these changes in patients who did, and did not, show postoperative complications. Serum IL-6 level was elevated after surgery, peaking on the first postoperative day. Elevation of serum APRs and plasma NE levels also followed. There was a significant correlation between the serum peak level of IL-6 and those of APRs and NE (P less than 0.01). Moreover, there was a significant difference in the serum IL-6 level in patients with and without complications. The relationship between the serum IL-6 greater than 400 pg/ml and the incidence of postoperative complications was also marked. These results suggest that circulating IL-6 is a clinically useful marker for the earliest detection and prediction of postoperative complications.

Adult↗
PubMed1992

Comparison of shape recovery ratios in various intraocular lens haptics.

Since understanding the mechanical properties of intraocular lens (IOL) haptic materials can minimize decentration after surgery, we have examined shape recovery ratios of various intraocular lens haptics (polypropylene [PP], polyvinylidene fluoride [PVDF], extruded poly(methyl methacrylate) [PMMA]) currently on the market under conditions that approximate clinical use. The results using various Ascon lens-holding forceps and compression tests, during which the lenses were held in a cylindrical holder for seven days, one month, and three months, indicated that PVDF haptics had better shape recovery capability than PP and extruded three-piece PMMA haptics.

Lenses, Intraocular↗
PubMed1992

Direct vasoconstrictor and vasodilator effects of propofol in isolated dog arteries.

We have measured the direct effects of propofol 10(-7)-10(-4) mol litre-1 on isolated canine cerebral, coronary, mesenteric, femoral and renal arteries. In arterial strips precontracted submaximally with potassium chloride or prostaglandin F2 alpha (PGF2 alpha), propofol induced further contractions at low concentrations (10(-6)-10(-5) mol litre-1) and relaxation at high concentrations (10(-4) mol litre-1). Intrafat, which contains soya bean oil, egg phosphatide and glycerol in similar concentration to the emulsion formulation of propofol, had a small relaxant effect at a concentration corresponding to propofol 10(-4) mol litre-1. In humans, clinically relevant plasma concentrations of propofol have been reported to be 1-5 x 10(-5) mol litre-1, 97-99% of which is bound to plasma proteins. Therefore, the results obtained in this study demonstrated that clinically relevant concentrations of propofol did not have direct vasodilator effects.

Animals↗
PubMed1992

Mechanism underlying mannitol-induced relaxation in isolated monkey cerebral arteries.

The addition of mannitol (25, 50, and 100 mM) increased osmotic pressures of the bathing media from 293 to 317, 340 and 383 mosmol, respectively, and elicited a dose-related relaxation in monkey cerebral artery strips precontracted with K+ or prostaglandin F2 alpha. This relaxation was attenuated by ouabain, amiloride, catalase and oxyhemoglobin but was not influenced by superoxide dismutase and indomethacin. Combined treatment of the strips exposed to ouabain and amiloride with catalase produced an additional inhibition. H2O2 produced a contraction, which was abolished by catalase. Replacement of entire NaCl with choline chloride markedly suppressed the mannitol-induced relaxation. Relaxations caused by the addition of hypertonic NaHCO3 (25 and 50 mM) were also attenuated by ouabain and amiloride but were unaffected by catalase and oxyhemoglobin. It may be concluded that the mannitol-induced cerebroarterial relaxation is associated with an activation of the electrogenic Na+ pump and the Na(+)-H+ exchange and probably with scavenging of hydroxyl radicals responsible for the arterial contraction. On the other hand, hypertonic NaHCO3 relaxes monkey cerebral arteries, possibly due to an activation of the Na+ pump and the Na(+)-H+ exchange.

Amiloride↗
PubMed1992

Halothane and isoflurane inhibit endothelium-dependent relaxation elicited by acetylcholine.

The purpose of this study was to determine whether volatile anesthetics modify the release of endothelium-derived relaxing factor. We examined the effects of halothane and isoflurane on endothelium-dependent relaxation and 3',5'-cyclic guanosine monophosphate formation elicited by acetylcholine and ionophore A23187 in isolated rat aorta. Halothane and isoflurane (1%-2%) significantly attenuated acetylcholine-induced relaxation of the phenylephrine-contracted aorta but had no significant effect on relaxation induced by A23187, nitroprusside, and nitroglycerin. Basal and A23187 (10(-7) M)-stimulated levels of 3',5'-cyclic guanosine monophosphate were slightly lowered by halothane and isoflurane (2%). In contrast, the increase of 3',5'-cyclic guanosine monophosphate elicited by acetylcholine (10(-5) M) was significantly attenuated by halothane (2%) and abolished by isoflurane (2%). These findings indicate that halothane and isoflurane strongly inhibit the release of endothelium-derived relaxing factor elicited by acetylcholine.

Acetylcholine↗
PubMed1992

Site-directed mutagenesis of catalytic active-site residues of Taka-amylase A.

The cDNA encoding Taka-amylase A (EC.3.2.1.1, TAA) was isolated to identify functional amino acid residues of TAA by protein engineering. The putative catalytic active-site residues and the substrate binding residue of TAA were altered by site-directed mutagenesis: aspartic acid-206, glutamic acid-230, aspartic acid-297, and lysine-209 were replaced with asparagine or glutamic acid, glutamine or aspartic acid, asparagine or glutamic acid, and phenylalanine or arginine, respectively. Saccharomyces cerevisiae strain YPH 250 was transformed with the expression plasmids containing the altered cDNA of the TAA gene. All the transformants with an expression vector containing the altered cDNA produced mutant TAAs that cross-reacted with the TAA antibody. The mutant TAA with alteration of Asp206, Glu230, or Asp297 in the putative catalytic site had no alpha-amylase activity, while that with alteration of Lys209 in the putative binding site to Arg or Phe had reduced activity.

Amylases↗
PubMed1992

Influence of left ventricular filling profile on the effect of atrioventricular synchronous pacing.

We correlated the percentage of atrial contribution to left ventricular filling (percent AC) assessed by Doppler echocardiography with the hemodynamic benefit from atrioventricular synchronous pacing assessed by direct hemodynamic measurements. Subjects comprised 40 patients who underwent electrophysiologic catheterization because of unexplained syncope or bradycardia (< 40 beats/min). Femoral arterial and pulmonary capillary wedge pressure were recorded by catheterization, and cardiac output was measured by thermodilution during temporary atrioventricular synchronous (DDD, 70 beats/min with 150 ms of atrioventricular delay) and ventricular (VVI, 70 beats/min) pacing. Mitral inflow velocity by pulsed-wave Doppler echocardiography was recorded during DDD pacing and percent AC was obtained by calculating the ratio of mitral inflow velocity area during atrial systole to total mitral inflow velocity area during early diastole and atrial systole. The mean arterial pressure and the cardiac output increased significantly (99 +/- 16 mm Hg vs 90 +/- 15 mm Hg, p < 0.001; 4.6 +/- 1.0 L/min vs 3.9 +/- 0.9 L/min, p < 0.001), and the mean pulmonary capillary wedge pressure decreased (7 +/- 4 mm Hg vs 10 +/- 4 mm Hg, p < 0.001) during DDD compared with VVI pacing. A significant positive correlation was observed between the percent AC and the increase in cardiac output (r = 0.58, n = 40, p < 0.01) or the increase in mean arterial pressure (r = 0.62, n = 38, p < 0.01) during DDD pacing. The percent AC did not significantly correlate with the decrease in pulmonary capillary wedge pressure. In conclusion, patients with larger percent AC may receive major benefit from atrioventricular synchronous pacing.

Adolescent↗