Biomedical subjects
Publications and source records attributed to Y Miyake.
Description of a man with heredoataxia, presenting with an isolated primary atrophic maculopathy in which the participation of the posterior pole was disclosed by photopic and scotopic ERG irrespective of the localized appearance of this condition. Ophthalmoscopically, the patient's sister showed only fine pigment migrations at the macula, whereas local ERG revealed a macular lesion.
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This study elucidates the nature of melanogenesis in B16 and Harding-Passey (HP) mouse melanomas producing melanin and melanosomes of different color and fine structure, i.e., brown-black eumelanosome-like B16 granules and reddish brown pheomelanosome-like HP granules, and compares them with "typical" 3,4-dihydroxyphenylalanine (DOPA) and sepia eumelanins and sepia eumelanosomes. The melanin content of B16 melanosomes was more than three times higher than that of HP melanosomes. The content of free and protein-bound DOPA and 5-S-cysteinyldopa varied greatly in B16, HP, and sepia melanosomes and was unrelated to melanin content. Chemical analysis of the eumelanin: pheomelanin ratio in melanosomes and elemental analysis of isolated melanin showed that B16 and HP melanins are primarily eumelanic, with a higher ratio of pheomelanic component in HP melanin. The spectra of electron spin resonance and IR and X-ray small-angle scattering of B16 and HP melanins were basically similar to those of sepia and DOPA melanins. B16, HP, and DOPA melanins were dissolved in aqueous NH3, while sepia melanin was dissolved to a far lesser extent. It was concluded that both B16 and HP melanomas are primarily involved in eumelanogenesis, although the fine structure of their melanosomes is entirely different, and that the marked color difference in the two melanosomes is related to a difference in the absolute content of eumelanin, the presence of a small amount of pheomelanin, and the mode of chemical bindings of melanin to structural proteins. In contrast to normal skin and hair, melanosome morphogenesis may not directly correspond to melanogenesis type in malignant melanoma.
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The 3-D plot of the statokinesigram, together with X-Y histograms and discriminant function studies are proposed towards a better understanding of the righting reflexes which maintain the erect stable posture in humans. Ninety samples taken from 30 healthy persons were analysed using on-line digital processing system. 3-D plot is an expression of the distribution map of the cumulative frequency of the sway of the center of gravity and helps intuitive recognition of the patterns of the righting reflexes. Parameters representing the distribution map are developed showing as good discriminant ratios as in the analyses of the locus and the area of the statokinesigram.
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Conversion of cytochrome P-450 to P-420 was observed with the use of three isozymes of P-450, P-450PB, P-450MC and P-450B1. The last one, which was isolated and characterized in our laboratories, is the cytochrome P-450 with high affinity for cytochrome b5. Of these isozymes, cytochrome P-450B1 is predominantly fast in the rate of conversion from P-450 to P-420 in the reduced state under carbon monoxide. p-Nitroanisole, which is the substrate of P-450B1 for demethylation, accelerated the conversion, whereas the effects of the compound on the rate of conversion of the other P-450S were small. The effect of cholate on the conversion was distinct and rapid but not very selective among the isozymes. Stabilization with glycerol for prevention of the conversion was found to be effective, for any of these isozymes. No remarkable difference was observed in the stability of the oxidized state among these isozymes when detected in the CO-reduced form. The rates of the reaction from the oxidized to the CO-reduced form were measured with these isozymes. The rate of P-450B1 was the highest in both the medium with glycerol and that without glycerol. Circular dichroism was measured with respect to conversion of P-450 to P-420. The absorption at 450 nm was related to the significant circular dichroism, while the increased absorption at 420 nm due to the conversion was not accompanied by distinct circular dichroism. These data support the concept that the heme vicinity of cytochrome P-450B1 is more labile in the structure of the reduced form under carbon monoxide than those of the other isozymes.
Two neutrophil chemotactic factors were isolated from the culture filtrates of Streptococcus sanguis ATCC 10556 and were chemically characterized as N-terminal blocked peptides of low molecular weight. One of the factors consisted of proline, valine, methionine, isoleucine and leucine and the other of methionine, isoleucine, leucine and phenylalanine. In both factors, methionine was detected as the sole N-terminal amino acid, but the amino group was blocked. The removal of N-terminal methionine yielded several N-terminal amino acids, suggesting that S. sanguis produced several N-terminal blocked methionyl peptides, all of which could be chemotactically active.
When 18-hydroxy-11-deoxycorticosterone was incubated with adrenocortical mitochondria fortified by adding exogenously adrenodoxin reductase and adrenodoxin in the presence of an NADPH-generating system, the steroid was converted to two products which were separated by high performance liquid chromatography. The retention time of one product was identical with that of 18-hydroxycorticosterone, an expected product of 11 beta-hydroxylation, whereas the retention time of the other was not coincident with those of any other corticosteroids examined. Production of the unidentified substance was also shown when 18-hydroxy-11-deoxycorticosterone was incubated with purified cytochrome P-45011 beta and its electron transport system. The ratio of the two products was always constant, even when various incubation conditions were employed with regard to reaction time, the substrate concentration, and the cytochrome concentration. Structural determination of the unidentified product was conducted by mass spectrometry and 1H NMR spectrometry. The results of these analyses indicated that the substance was 18,19-dihydroxy-11-deoxycorticosterone, a hitherto unreported corticosteroid.
Resonance Raman (RR) spectra were measured for the purple intermediates of D-amino acid oxidase reconstituted with isotopically labelled FAD's, i.e., [4a-13C]-, [4,10a-13C2]-, [2-13C]-, [5-15N]-, and [1,3-15N2]flavin adenine dinucleotides, and compared with those with the native enzyme. The RR lines around 1605 cm-1 with D-alanine or D-proline as a substrate and at 1548 cm-1 with D-alanine undergo isotopic shifts upon [4a-13C]- and [4,10a-13C2]-labelling. These lines are assigned to the vibrational modes associated with C(10a) = C(4a) - C(4) = O moiety of reduced flavin, providing the first assignment of RR lines of reduced flavin and conclusive evidence that reduced flavin is involved in this intermediate.
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Binding of 8-fluoro-8-demethylriboflavin to riboflavin binding protein was studied 19F-NMR spectroscopically. The pH dependence of 19F chemical shift of this fluoro derivative both free and bound to the protein revealed a shift of pKa associated with N(3)-H to alkali when bound to the protein. 19F chemical shift of the fluoro derivative bound to the protein is in a higher magnetic field than that of the free derivative in the neutral to acidic pH region. These results are interpreted in terms of the environmental changes at the 8- and 3-positions of isoalloxazine, indicating the applicability of this derivative for probing flavin-protein interaction at these positions.
Vitreous fluorophotometry was performed on eyes with three kinds of congenital stationary nightblindness: Oguchi's disease (two cases), X-linked congenital stationary nightblindness (two cases), and fundus albipunctatus (one case). The results were compared with the electroretinogram (ERG) and the electro-oculogram (EOG). In spite of the variable degree of abnormality of the ERG and EOG, all eyes showed normal values on vitreous fluorophotometry. These results strongly suggest that the blood-retinal barrier in congenital stationary nightblindness is intact and that the electrophysiological results and the functioning of the blood-retinal barrier do not correlate in these diseases.
We conducted a prospective, double-masked, controlled study to determine the effects of indomethacin in preventing the development of cystoid macular edema after retinal detachment surgery. In addition to routine medication, topical indomethacin was applied to 63 eyes (52 with intact lenses and 11 aphakic) and a placebo was applied to 61 eyes (51 with intact lenses and ten aphakic) that underwent retinal detachment surgery. Indomethacin drops or placebo were instilled once an hour for five hours preoperatively and three times daily for four weeks postoperatively. Fluorescein angiography, done before surgery and four to six weeks after surgery to detect cystoid macular edema, showed that cystoid macular edema developed in 11 of 63 eyes (13%) in the indomethacin-treated group and in 20 of 61 eyes (33%) in the placebo group (P less than .01). Five of 28 eyes (18%) with cystoid macular edema in both groups and 38 of 96 eyes (40%) without cystoid macular edema in both groups had visual acuities of 20/40 or better (P less than .05).