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Biomedical subjects

S Yoshikawa

Publications and source records attributed to S Yoshikawa.

At least 163 records · Page 9Linked to original sources
PubMed1990

Observation of the Fe4+ = O stretching Raman band for cytochrome oxidase compound B at ambient temperature.

Resonance Raman and visible absorption spectra were simultaneously observed for cytochrome oxidase reaction intermediates at 5 degrees C by using the artificial cardiovascular system (Ogura, T., Yoshikawa, S., and Kitagawa, T. (1989) Biochemistry 28, 8022-8027) and a device for Raman/absorption simultaneous measurements (Ogura, T., and Kitagawa, T. (1988) Rev. Sci. Instrum. 59, 1316-1320). The Fe4+ = O stretching (nu FeO) Raman band was observed at 788 cm-1 for compound B for the first time. This band showed the 16O/18O isotopic frequency shift (delta nu FeO) by 40 cm-1, in agreement with that for horseradish peroxidase compound II (nu FeO = 787 cm-1 and delta nu FeO = 34 cm-1). In the time region when the FeII-O2 stretching band for compound A and the nu FeO band for compound B were coexistent, a Raman band assignable to the Fe3+-O-O-Cu2+ linkage was not recognized.

Animals↗
PubMed1990

Infrared evidence of cyanide binding to iron and copper sites in bovine heart cytochrome c oxidase. Implications regarding oxygen reduction.

Cyanide binding to bovine heart cytochrome c oxidase at five redox levels has been investigated by use of infrared and visible-Soret spectra. A C-N stretch band permits identification of the metal ion to which the CN- is bound and the oxidation state of the metal. Non-intrinsic Cu, if present, is detected as a cyanide complex. Bands can be assigned to Cu+CN at 2093 cm-1, Cu2+CN at 2151 or 2165 cm-1, Fe3+CN at 2131 cm-1, and Fe2+CN at 2058 cm-1. Fe2+CN is found only when the enzyme is fully reduced whereas the reduced Cu+CN occurs in 2-, 3-, and 4-electron reduced species. A band for Fe3+CN is not found for the complex of fully oxidized enzyme but is for all partially reduced species. Cu2+CN occurs in both fully oxidized and 1-electron-reduced oxidase. CO displaces the CN- at Fe2+ to give a C-O band at 1963.5 cm-1 but does not displace the CN- at Cu+. Another metal site, noted by a band at 2042 cm-1, is accessible only in fully reduced enzyme and may represent Zn2+ or another Cu+. Binding of either CN- or CO may induce electron redistribution among metal centers. The extraordinary narrowness of ligand infrared bands indicates very little mobility of the components that line the O2 reduction site, a property of potential advantage for enzyme catalysis. The infrared evidence that CN- can bind to both Fe and Cu supports the possibility of an O2 reduction mechanism in which an intermediate with a mu-peroxo bridge between Fe and Cu is formed. On the other hand, the apparent independence of Fe and Cu ligand-binding sites makes a heme hydroperoxide (Fe-O-O-H) intermediate an attractive alternative to the formation an Fe-O-O-Cu linkage.

Animals↗
PubMed1990

Effect of cyclic guanosine monophosphate on hypoxic and angiotensin-II-induced pulmonary vasoconstriction.

We examined, in isolated blood perfused rat lungs, the effect of the cell permeable 8-bromo derivative of cGMP on pulmonary vasoconstriction induced by either alveolar hypoxia or angiotensin II. 8-Bromo cGMP dose-dependently reduced both hypoxia-(IC50 = 2.2 X 10(-5) M) and angiotensin-II-induced pulmonary vasoconstriction (IC50 = 5.0 X 10(-5) M). This effect of 8-bromo cGMP on pulmonary vasoconstriction was not affected by cyclooxygenase blockade. M & B 22948 (0.1 mM), an inhibitor of cGMP-phosphodiesterase, reduced synergistically with 8-bromo cGMP the hypoxia or angiotensin-II-induced vasoconstriction. The cGMP-phosphodiesterase inhibitor M & B 22948, by itself, selectively reduced hypoxia-induced vasoconstriction, suggesting a modulating effect of endogenous cGMP during hypoxic vasoconstriction.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1990

[Arachidonic acid metabolites on peripheral blood plasma in patients with bronchial asthma].

To assess the role of arachidonic acid metabolites in pathogenesis of bronchial asthma, we measured thromboxane B2 (TxB2), 6-keto PGF1 alpha, leukotriene (LT) C4, and LTB4 in venous blood plasma in patients with bronchial asthma and in controls. The level of TxB2 was significantly higher in 18 asthmatics with attacks than that in 11 controls (77.3 +/- 48.8 pg/ml vs 48.8 +/- 9.4 pgml). The levels of 6-keto PGF1 alpha in both asthmatics with attacks (17.8 +/- 6.7 pg/ml) and without an attack (16.4 +/- 9.7) were significantly higher than that in controls (11.6 +/- 3.9 pg/ml). The levels of LTC4 in asthmatics with attacks (0.84 +/- 0.11 ng/ml, n = 11) were significantly higher than that in controls, furthermore the level of LTC4 in asthmatics without an attack. The level of LTB4 was significantly higher in asthmatics with attacks (295.0 +/- 160.7 pg/ml, n = 26) than that in controls (161.7 +/- 25.3 pg/ml, n = 12) and asthmatics without an attack (182.4 +/- 97.9 pg/ml, n = 22). These findings suggest that the arachidonic acid metabolites are related to the asthma attack and are associated with the pathogenesis of bronchial asthma.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Raman/absorption simultaneous measurements for cytochrome oxidase compound A at room temperature with a novel flow apparatus.

A novel flow apparatus for continuously producing reaction intermediates of cytochrome oxidase was constructed and applied successfully to observe the transient absorption and resonance Raman spectra in its reaction with oxygen. Time-resolved difference absorption spectra in 500-650-nm region clearly indicated the formation of compound A upon photolysis of the fully reduced CO-bound form at 5 degrees C, and at this stage electrons were not transferred from cytochrome c to cytochrome oxidase. However, at the stage of formation of compound B, cytochrome c was oxidized. Resonance Raman spectra of these intermediates measured simultaneously with the absorption spectra are also reported.

Absorption↗
PubMed1989

Plasma levels of atrial natriuretic peptide under acute hypoxia in normal subjects.

To investigate whether the acute hypoxia can be a stimulus for atrial natriuretic peptide (ANP) secretion, plasma levels of ANP were determined under three different hypoxic conditions in six normal subjects. During 15% O2 breathing for 10 min, no significant change in plasma ANP level was observed. Severe hypoxia induced by 10% O2 breathing increased the mean pulmonary arterial pressure (Ppa) by 11.6 mm Hg within 10 min (P less than 0.01), accompanying a slight but significant rise in plasma ANP level of pulmonary artery (PA) from 24.3 +/- 5.3 to 28.2 +/- 4.6 pg/ml (P less than 0.05). There was a tendency for the ANP level of PA to rise under hypoxic hypobaria at 515 Torr for 10 min, followed by a decrease of that level during 100% O2 breathing under hypobaric condition. These changes, however, still remained in the normal range. No significant changes were observed both in right atrial pressure and in pulmonary capillary wedge pressure under any of the three hypoxic conditions. From these results we conclude that ANP can be released in response to the elevation of Ppa caused by acute hypoxia in normal subjects, but the changes in plasma ANP level may be too small to play a significant physiological role in hemodynamic responses to acute hypoxia.

Acute Disease↗
PubMed1989

Morphological change and Raman spectrum of rabbit lens irradiated with ultraviolet laser beam.

The effect of ultraviolet rays on eyes was studied. An ultraviolet laser beam (XeCl 308 nm) was irradiated to rabbit eyes to investigate morphological changes of the lens fibers and molecular structural changes of the lens proteins at immediately, 15 days and 32 days after irradiation. 1. Scanning electron microscopic findings of the lens The lens fibers in the control eye were regularly and densely arranged in neat layers of hexahedrons. In the irradiated eye, the fibers at areas that seemed injured were disrupted and the disrupted ends were spherical-shaped. 2. Raman spectra of the lens 1) The relative intensity ratio (I825/I850) of the Raman scattering for the tyrosine residue and the relative intensity ratio (I3390/I2960) of the OH stretching mode (3390 cm-1) of water contained in the lens cortex showed slight changes in the irradiated eye compared to the control eye. 2) The relative intensity ratio (I2572/I2721) of the SH stretching mode (2572 cm-1) for the cysteine residue was 1.05 in the irradiated eye at 32 days after irradiation. It was lower than that in the control eye (1.22 +/- 0.08). This suggested the synthesis of S-S binding by oxidization.

Animals↗
PubMed1988

Crystalline cytochrome c oxidase of bovine heart mitochondrial membrane: composition and x-ray diffraction studies.

The integral mitochondrial membrane protein cytochrome c oxidase (ferrocytochrome-c:oxygen oxidoreductase, EC 1.9.3.1) was crystallized from solutions of the protein from bovine heart isolated as described earlier [Yoshikawa, S. & Caughey, W. S. (1982) J. Biol. Chem. 257, 412-420]. Crystallinity was demonstrated by x-ray diffraction. Microcrystals (tetragonal prisms, 0.02 mm in the largest dimension) were obtained in high yield with retention of activity and contained Fe, Cu, Zn, and Mg in approximate atom ratios of 1.0:1.25:0.5:0.5, respectively. Analysis of the amino acid residues and the tightly bound detergent support an apparent molecular mass of about 200 kDa, of which 150 kDa is protein (1316 +/- 66 amino acids) and 50 kDa is detergent (Brij 35). Seven major polypeptides are evident by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Adjustments in buffer concentration and other conditions have yielded much larger green crystals, hexagonal bipyramids; a crystal 0.3 X 0.5 X 0.7 mm gave x-ray diffractions as high as 8-A resolution and a space group of P6(2) or P6(4), and cell dimensions of a = b = 174.5 A, c = 282.2 A, alpha = beta = 90 degrees, and gamma = 120 degrees were obtained. A reasonable value of 3.1 A3/Da for Vm, the average space per dalton of protein in the crystal, was obtained for the asymmetric unit, which contains four irons and is a dimer of two minimal catalytic units. Cylindrical dimers (80 X 100 A) estimated from two-dimensional electron diffraction studies [Fuller, S. D., Capaldi, R. A. & Henderson, R. (1979) J. Mol. Biol. 134, 305-327] pack well in the crystal lattice with the symmetry of the space group of the crystal. The crystallization procedure developed is useful in purification of the enzyme and shows promise for the production of crystals of sufficiently high order to gain improved structural information from x-ray diffraction.

Amino Acids↗
PubMed1988

Specificity of action on neuropeptides of an endopeptidase from the synaptosomal membranes of guinea pig brain.

An endopeptidase was solubilized and highly purified from the synaptosomal membrane fraction of guinea pig brain, and its specificity of action on various neuropeptides was investigated. It hydrolyzed specifically the Pro10-Tyr11 bond of neurotensin and showed a marked specificity toward Pro-X bonds present in the interior parts of various neuropeptides and related peptides. No cleavage, however, was observed at the first and second peptide bonds from the NH2-termini or from the COOH-termini of the peptides examined, suggesting that the enzyme requires both NH2- and COOH-terminal extentions of at least 3 residues from the scissile bond for its action. In addition, a limited number of other peptide bonds were cleaved, indicating that the enzyme is not strictly specific to Pro-X bonds. These results suggest the possible implication of this enzyme in the specific degradation of neurotensin and other peptide neurotransmitters in the synaptic cleft.

Amino Acid Sequence↗
PubMed1988

[Effects of ultraviolet laser beam irradiation on rabbit cornea and lens].

Rabbit eyes were irradiated by an ultraviolet laser beam in with to investigate its effects on the corneal endothelium, thickness of the cornea, and lens. An Excimer laser beam (gas; XeCl) with wave length of 308 nm and with energy intensity of 0.02, 0.07, 0.2, 0.6, 1.7, 3.0, 4.0, or 5.1 J/cm2 was irradiated to the right eye using 3 rabbits for each energy intensity (24 rabbits in all) in order to examine changes occurring in the right eye compared with the left eye from immediately after irradiation to 32 days thereafter. The results obtained were as follows: 1. Corneal thickness UV laser beam irradiation at 0.02, 0.07, and 0.6 J/cm2 caused immediate thickening of the cornea (p less than 0.01). The cornea thickness returned to normal 14 days later. Irradiation at 3.0 and 4.0 J/cm2 resulted in remarkable thickening, which returned to normal 28 days after irradiation. By irradiation at 5.1 J/cm2, the corneal thickness increased markedly (0.333 +/- 0.019 mm in control eyes and 0.405 +/- 0.05 mm in irradiated eyes) immediately after irradiation. It tended to gradually return to normal and was reduced to the pre-irradiation thickness on the 32nd day after irradiation. 2. Corneal endothelial area and morphology (the number of angles) The area of the corneal endothelium increased after irradiation. However, no significant differences were noted at any energy intensity, because of the larger scattering of the values in the control eyes. The ratio of hexagonal cells tended to decrease even by energy intensities above 0.7 J/cm2. However, no significant differences were found at any energy intensity level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

[The efficacy of combined use of 1 alpha-hydroxyvitamin D3 with calcium supplements in the treatment of osteoporosis].

Synthetic analogue of active vitamin D metabolite, 1 alpha (OH) D3, has been widely used in the treatment of osteoporosis. However, the most effective method of treatment is yet to be established. Importance of calcium supplement to improve the calcium metabolism in osteoporosis is also reported by many authors. We have studied the combined effects of 1 alpha (OH)D3 with calcium supplement in preventing progressive decrease of bone mass in patients with osteoporosis. Sixty-six cases of postmenopausal and senile osteoporosis were divided into two groups: one treated with calcium alone 1,000 mg a day and the other treated with calcium 1,000 mg and 1 alpha (OH)D3 0.5 microgram a day, and both groups were followed for 24 months. Bone mass was evaluated by microdensitometry of the roentgenograms of the second metacarpal bone. The results revealed that the combined use of 1 alpha (OH)D3 with calcium has a significantly more favorable effect than the use of calcium alone in preventing bone loss. Therefore, 1 alpha (OH)D3 with calcium is useful in the treatment of osteoporosis. The conclusion would be further confirmed with longer term study and a more accurate method of measuring bone mass.

Aged↗
PubMed1988

[A histomorphometric study of normal iliac trabecular bones. Part I: Age related changes and the values of tissue-leveled static parameters].

Trans-iliac bone biopsies were performed on 142 normal Japanese subjects (55 males, 87 females, mean age: 44.8 years) and were evaluated particularly for the indices of tissue-leveled static parameters: volume and thickness of bone/osteoid, and surface measurement of formation, resorption and inert surface. The results were in general agreement with previous studies, but some discrepancies were found regarding osteoid indices: 1) The osteoid (formation) surface, especially osteoblastic osteoid surfaces, increased significantly at the ages from 50 to 60 years in females, 2) osteoid volume and relative osteoid volume were also found to have increased at this age range in females, 3) osteoid thickness decreased or had a rather constant value in females, and 4) the values of these 3 parameters decreased in males with the advance of age after young adulthood. From these results, at least at tissue level, the bone formation rate seemed to increase from the 6th to the 7th decade of life in women making a clear contrast to men in whom the formation rate appeared to decrease within the same age range.

Adolescent↗
PubMed1988

[A histomorphometric study of normal iliac trabecular bones. Part II: Age changes and the values of MWT and related parameters].

The Mean Wall Thickness (MWT) of the trabecular packet and other related indices: number of osteocytic lacunae (N-0) and maximum number of birefringent lamellae (N-1) in the packet were measured in 142 normal Japanese subjects (male 55, female 87, mean age 44.8 yrs). MWT was obtained by the equation MWT = 2S/L, where S and L designate area and perimeter, respectively. The MWT, S, and L of the packets all decreased significantly after young adulthood. N-0 and N-1 also decreased significantly with age. In contrast, S/(N-0), which is the measure of the volume of the matrix being formed by a single osteoblast, did not change with age. Therefore, it may be concluded that BMU-leveled bone formation decreases with age probably due to the decreased number of osteoblasts which participate in forming a trabecular packet.

Adolescent↗