Search PubMed⌕ Search

Biomedical subjects

M Ohe

Publications and source records attributed to M Ohe.

At least 55 records · Page 3Linked to original sources
PubMed1989

Effects of verapamil and BAY K 8644 on the hypoxic contraction of the isolated human pulmonary artery.

To examine the effect of hypoxia on the human pulmonary artery (HPA), HPA segments (2 mm, o.d.) were suspended and changes in isometric force with hypoxia (PO2 = 44 +/- 3 mmHg, mean +/- S.E.) were measured. HPA contracted with hypoxia and the tension developed with 15 min of hypoxia was 127 +/- 36 (mean +/- S.E.) mg. Verapamil at 47 +/- 10% 10(-6) M inhibited and 10(-6) M BAY K 8644 enhanced the hypoxic response by (p less than 0.01) and 396 +/- 106% (p less than 0.05), respectively, compared with preceding values. These results show that activation of voltage-dependent Ca2+ channels also plays an important role in the mechanism of hypoxic pulmonary vasoconstriction in man.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

Oxygen exchange during the acto-subfragment-1 ATPase reaction: evidence for the two-route mechanism of the actomyosin ATPase reaction.

The oxygen exchange occurring during the acto-S-1 ATPase reaction was analyzed based on the distribution of 18O-labeled species of P1 using [gamma-18O]ATP as a substrate. Evidence was found for the two-route mechanism in which ATP is hydrolyzed via the dissociation of acto-S-1 into F-actin and the S-1-phosphate-ADP complex, S-1PADP, and their recombination, and also hydrolyzed without the dissociation of acto-S-1 (Inoue, A., Shigekawa, M., & Tonomura, Y. (1973) J. Biochem. 74, 923-934; Inoue, A., Ikebe, M., & Tonomura, Y. (1980) J. Biochem. 88, 1663-1677). When ATP was mainly hydrolyzed without the dissociation of acto-S-1, the extent of oxygen exchange was low. When ATP was hydrolyzed by both routes, the distribution of product P1 with 3, 2, 1, and 0 18O atoms showed a mixture resulting from low and high oxygen exchange. The rate of ATPase without the dissociation of acto-S-1 can be estimated from the rate of the overall reaction (v), the rate of recombination of S-1PADP with F-actin (vr), and the extent of dissociation of acto-S-1 (a). The distribution of the P1 species measured was almost equal to that calculated from the ratio of ATP hydrolysis via the two pathways as avr and v-avr, respectively. This result indicates that the rates of the dissociation of acto-S-1PADP into S-1PADP and F-actin and their recombination are much lower than the rate of decomposition of the acto-S-1PADP complex into acto-S-1 + ADP + Pi.

Adenosine Triphosphatases↗
PubMed1987

The degree of increment in plasma catecholamines in patients with mitral stenosis by mild exercise.

Although sympathetic excitation during mild exercise may readily occur in patients with mitral stenosis (MS), the degree of increment in plasma catecholamines has not been fully investigated. We imposed mild ergometric exercise (50 watts, 300 kg/min for 5 minutes) on five patients with mild MS (mitral valve area greater than or equal to 1.0 cm2) and eight with severe MS (mitral valve area less than 1.0 cm2) while they were undergoing cardiac catheterization. In patients with severe MS, total plasma catecholamine levels during exercise were remarkably higher (2821 +/- 783 [SEM] pg/ml) than in those with mild MS (957 +/- 113 pg/ml, p less than 0.05) and in seven control subjects (612 +/- 75 pg/ml, p less than 0.05). This marked increment could not be predicted by heart rate response, which did not differ between severe and mild MS (166 +/- 5 vs 153 +/- 10 bpm). In contrast with catecholamine change, the cardiac index in severe MS showed a very small increment. Results suggest that mild daily exercise can remarkably increase plasma catecholamine levels in severe MS, and this may accelerate various complications of this disorder.

Adult↗
PubMed1987

[Myocardial perfusion detected using digital subtraction angiography as compared with X-ray CT and Tl-201 myocardial imaging].

Forty-two patients who underwent aorto-coronary bypass surgery were examined with intra-aortic digital subtraction angiography (IADSA) to detect abnormalities of myocardial blood perfusion. Tl-201 myocardial imaging and cardiac X-ray CT were performed nearly simultaneously about one month postoperatively. Cardiac imaging using IADSA was performed at a rate of 30 frames/sec with matrix size of 512 x 256. Time density curves of each pixel in the region of the myocardium of the left ventricle were post-processed to obtain functional images. The maximal concentration (Cmax), integration of the time-density curve (Cinteg), mean transit time (MTT), Cmax/MTT and Cinteg/MTT were computed for each pixel. Cmax and Cinteg are parameters related to the volume of the coronary vascular bed. Cmax/MTT and Cinteg/MTT are parameters related to the regional myocardial blood flow. These functional images showed hypoperfusion areas in 35 of 37 ischemic segments confirmed by wall motion in digital subtraction left ventriculography, Tl-201 myocardial imaging and ECG. Normal perfusion areas of the functional images were observed in 18 of 54 infarcted segments. These results show the complexities of myocardial perfusion in old myocardial infarction.

Coronary Angiography↗
PubMed1986

Time course of pulmonary vasoconstriction with repeated hypoxia and glucose depletion.

To examine the effect of hypoxia on pulmonary vascular smooth muscle, rabbit lobar pulmonary artery was suspended in a glucose free solution and both chronologic changes in tension and ATP content were determined together at 30 min intervals after repeated hypoxic challenge (PO2 = 11 +/- 2 mm Hg). The pulmonary artery contracted and its ATP content decreased with hypoxia. This contraction was not inhibited by nifedipine, Ca++ -free EGTA, procaine, phentolamine, isoproterenol, diphenhydramine, prostaglandin E1, atropine or nitroglycerin. Upon reoxygenation (PO2 = 104 +/- 3 mm Hg), the elevated resting tension decreased in a biphasic fashion and the ATP content of the lobar pulmonary artery increased. When hypoxic challenges were repeated, the rate of constriction on hypoxia increased, while the relaxation rate on reoxygenation, tension developed by 30 min of hypoxia and the total amount of ATP decreased. These results suggest that the ATP content in the lobar pulmonary artery is very sensitive to in vitro acute hypoxia and that the Ca++ transport process is more easily impaired by reduction in ATP levels than is the contractile machinery.

Adenosine Triphosphate↗
PubMed1986

Laser Raman spectroscopy of lyophilized bacterial spores.

Laser-excited Raman spectra were examined in lyophilized spores of Bacillus cereus. In a comparison of the spectrum of the dormant spore with that of the germinated spore, we found several Raman bands which occurred in the former but not in the latter. Among these Raman bands, the 1,573, 1,395, 1,017, 822, and 662 cm-1 bands were assigned to the vibrational frequencies of calcium dipicolinate (CaDPA). No Raman bands and peaks due to dipicolinic acid (H2DPA) were observed. This Raman evidence indicates that CaDPA is the predominant DPA species in this spore. We also proposed a tentative assignment for other vibrational frequencies due to several components of the spore.

Bacillus cereus↗
PubMed1985

Myocardial perfusion assessed by digital subtraction angiography.

Perfusion of each myocardial portion in ischemic heart disease was assessed by digital subtraction angiography (DSA). There were 45 cases of ischemic heart disease and five normal controls. The contrast medium was 40 ml 76% Urografin which was injected into the central vein at a rate of 16 ml/sec using a 5F thin-wall catheter. A myocardial image was extracted, and a time-density curve for the corresponding portion was obtained. In the normal controls, the density was maximum in systole with a gradual decrease in diastole. In all myocardial infarction cases, the wave pattern disappeared. In the group whose infarcted areas were small (26 of the 45 cases), 22 (85% of of the 26 cases) exhibited slowly increasing pattern. In the group whose infarcted areas were large (19 of the 45 cases) 15 cases (79%) had plateau type pattern. Observations of the perfusion of the myocardium using DSA facilitated quantitative diagnoses of the infarcted areas and forecasts of myocardial viability.

Adult↗
PubMed1984

Effect of sodium saccharin on rat pancreatic enzyme secretion.

Intragastric administration of casein, oleic acid, or polyvinylpyrrolidone resulted in a marked increase in the pancreatic secretion of enzymes, and the administration of 0.03% sodium saccharin, at the concentration permitted in soft drinks, inhibited this increase with these substances. The stimulation of secretion of pancreatic juice-bile mixture by these substances was also inhibited by administration of sodium saccharin. Intravenous injection of CCK-PZ (cholecystokinin-pancreozymin) during inhibition by sodium saccharin, caused a rapid increase in amylase output, suggesting that sodium saccharin acts on the site(s) of CCK-PZ release to prevent its secretion even in the presence of a stimulant, but does not reduce the sensitivity of the pancreas to CCK-PZ. Sodium saccharin seemed to have an effect on secretin release similar to that on CCK-PZ release, judging from the results for the volume of juice-bile mixture.

Amylases↗
PubMed1983

Assessment of the magnitude of aortic regurgitation by dye injection into the descending aorta.

A technique simpler than the angiographic method for estimating aortic regurgitant volume was tried with 31 patients with aortic insufficiency. During cardiac catheterization, we injected dye into the descending aorta while recording the dye dilution curve in the left ear. The distance between the aortic arch and the tip of the catheter at the lowest point from which the injected dye could be detected in the left ear was rated in terms of the number of corresponding vertebral bodies. This "distance score" closely correlated with the regurgitant stroke volume and with the fraction to total stroke volume, which were measured by angiocardiography (r = 0.927, p less than 0.001; and r = 0.900, p less than 0.001, respectively). The correlation coefficients of the aortographic grade to those parameters were not as high as they were in the relationship of the score to the same parameters. Therefore, these results indicate that the "distance score" is a practical method for assessing the magnitude of aortic regurgitant volume.

Adolescent↗
PubMed1981

Ligand-dependent polymerization of tetrameric hemoglobin from the blood clam Anadara broughtonii.

Hemoglobin (Hb II) of the blood clam Anadara broughtonii has a alpha 2 beta 2 sub-unit structure in athe oxy form with a sedimentation constant of 4.8 S. When deoxygenated, Hb II polymerizes with a major component, S20,w = 11.5 (above 150 microM in heme). Deoxy polymerization was not observed in a highly diluted protein below 20 microM (in heme). Gel filtration of Hb II in the deoxygenated state indicated that the major component has an apparent molecular weight of 195 000, which corresponds to a dodecamer. However, the sedimentation pattern and the elution profile of gel filtration showed the polymerization to be somewhat asymmetric. These results suggest that deoxy Hb II may polymerize with different polymerization states. We examined oxygen equilibria of Hb II in a range of 3--180 microM (in heme). Influences of the polymerization on its oxygen affinity and cooperativity were found to be very small. We have also found that the deoxy polymerization was completely prevented when all the sulfhydryl groups of the hemoglobin molecule were modified with p-chloromercuribenzoate.

Animals↗
PubMed1980

Ligand-dependent allosteric transformation of hemoglobins from the blood clam, Anadara broughtonii.

1. Oligomeric Hb I and II of Anadara broughtonii, which are unusual with respect to having no Bohr effect, were shown to have a R-T transformation on ligand-binding on the basis of the following experimental results. (a) Iodoacetamide reacted preferentially with the oxyiforms of the hemoglobins. (b) CD spectra at the far-ultraviolet regions significantly changed on ligand-binding. (c) 1-Anilinonaphthalene-8-sulfonate bound to the hemoglobins with a preference for deoxyforms. From these results and previous findings [1], it is concluded that the absence of the Bohr effect in these hemoglobins is due to the lack of the Bohr proton ionizing groups in the molecules. 2. Hb I and II treated with p-chloromercuribenzoate, designated as PMB-I and PMB-II, showed greatly increased oxygen affinity and decreased cooperativity. CD spectra at the far-ultraviolet of the PMB-Hb in the oxygen liganded state gave similar patterns to those of native oxygenated Hb. However no changes in the spectra were observed on deoxygenation. These findings suggest that the PMB-I and PMB-II retain their native oxy conformation even in the deoxy states. The PMB-modification might prevent the initial ligand-induced conformational change within the protomers.

Allosteric Regulation↗
PubMed1980

Changes in pKa values of individual histidine residues of human hemoglobin upon reaction with carbon monoxide.

We performed the deuterium-exchange reaction on human hemoglobin in its carbon monoixy and deoxy forms at various pH values and 36.5 degrees C. Peptides containing only one histidine residue were separated from tryptic and chymotryptic digests of the deuterated hemoglobin, except for two peptides which contained the alpha-87 and alpha-89 and the beta-116 and beta-117 histidine residues, respectively. The pseudo-first-order rate constant for the exchange reaction of each histidin residue was measured by using the mass spectrometric method. We obtained the following results. The pKa values for the alpha-20, alpha-89, and beta-146 histidine residues in deoxyhemoglobin decreased significantly, while that for the beta-143 histidine residue increased significantly on ligation. The pseudo-first-order rate constants were virtually zero for the alpha-45, alpha-58, alpha-87, beta-63, and beta-92 histidine residues which are linked with a heme group, and also for the alpha-122 histidine residue which is buried at the alpha 1 beta 1 contact in the hemoglobin molecule. No change was detected in the pKa values on ligation for the other histidine residues in deoxyhemoglobin.

Amino Acid Sequence↗