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Biomedical subjects

T Yamano

Publications and source records attributed to T Yamano.

At least 253 records · Page 14Linked to original sources
PubMed1982

Interaction and electron transfer between cytochrome b5 and cytochrome P-450 in the reconstituted p-nitroanisole O-demethylase system.

The interaction and electron transfer between cytochrome b5 and cytochrome P-450B1 were investigated using the reconstituted p-nitroanisole O-demethylase system. Apocytochrome b5 was prepared from detergent-solubilized cytochrome b5 by the acid-butanone method. The apocytochrome b5 thus obtained has been substituted with several metalloporphyrin derivatives. The reconstituted system containing cytochrome b5 substituted with heme derivatives such as proto-, meso-, and deuteroheme exhibited demethylation activity at the maximum turnover rates of 94, 58, 30%, respectively, compared to that containing the native cytochrome b5, while neither apocytochrome b5 nor cobaltic protoporphyrin-cytochrome b5 displayed the activity. Kinetic analysis showed the formation of a 1:1 complex between cytochrome P-450B1 and each of these substituted cytochrome b5's, except for cobaltic protoporphyrin-cytochrome b5; the affinities differed with the cytochrome b5 species used. The synergistic effect with the addition of the NADH-linked electron transport system was more remarkable at the lower reduction levels of cytochrome b5 in the steady state. Interaction between the components involved in NADH- and NADPH-linked electron transport systems was modulated by the existence of Triton X-100. The optimal concentration in the reconstituted system for the demethylation was observed at around 0.03% of Triton X-100, where the reduction rates for cytochrome b5 and cytochrome P-450B1 by the respective reductases were maximal. These results indicate that the two electron transport systems are closely coupled and exhibit the demethylase activity.

Animals↗
PubMed1982

Studies on the reaction mechanism of NADPH-adrenodoxin reductase with NADPH.

The existence of a multi-component equilibrium involving a reversible reaction was demonstrated in the anaerobic reaction of NADPH-adrenodoxin reductase or ferredoxin-NADPH reductase; EC 1.18.1.2 (AdR) with NADPH or in the photoreduction of AdR in the presence of NADP+ and EDTA. After anaerobic reduction of AdR with excess NADPH, not only the fully reduced state but also other states of the enzyme were demonstrated as a mixture of characteristic absorption spectra of a flavin semiquinone with a peak at 575 nm and a shoulder around 625 nm and a charge transfer complex between NADP+ and the fully reduced AdR with a broad absorbance in a longer wavelength region. The amount of oxidized form in the reaction mixture was only a trace judging from the absorbance at 450 nm. The oxidized form was observed in addition to the other spectral species when the concentration of NADPH was limited. The spectrum of the AdR reduced with excess NADPH changed reversibly between 2 degrees C and 29 degrees C with isosbestic points at 427 nm and 667 nm; the semiquinone form increased at the expense of the charge transfer complex at lower temperatures, and vice versa at higher temperatures. The anaerobic photoreduction of AdR in the presence of NADP+ and EDTA produced the same spectral species as seen in the NADPH-reduced AdR, and the spectrum of the photoreduced AdR also changed reversibly between 1 degree C and 33 degrees C in a similar way to that of the NADPH-reduced AdR; the oxidized form changed in parallel with the semiquinone form. It was also found that NADPH was produced continuously during the photoirradiation even after the spectral changes had ceased. The results show that anaerobic reduction of AdR with NADPH or the photoreduction of AdR in the presence of NADP+ and EDTA produces a multi-component equilibrium and the equilibrium is dependent upon the concentration of NADPH and the temperature. Attainment of the equilibrium involves not only the forward reaction of AdR with NADPH but also the reverse reaction of the fully reduced AdR with NADP+.

Anaerobiosis↗
PubMed1982

Ultrastructural study of biopsy specimens of rectal mucosa. Its use in neuronal storage diseases.

Rectal mucosa biopsy specimens from patients with neuronal storage diseases were examined by electron microscopy. The diseases were Tay-Sachs disease, Sandhoff's disease, Niemann-Pick disease types B and C, late infantile metachromatic leukodystrophy, GM1 gangliosidosis type 1, beta-galactosidase-neuraminidase deficiency, I-cell disease, and mucopolysaccharidoses (Hunter's syndrome and Sanfilippo's syndrome type A). Unmyelinated nerve fibers, endothelial cells, fibroblasts, plasma cells, and histiocytes were seen in the specimens. Except for plasma cells, the results thus obtained for various cells were similar to those obtained from skin and conjunctival biopsy specimens, which have been already reported. There has been no report so far on ultrastructure of the plasma cell in these diseases. Storage materials, eg, dense bodies and membrane-bound vacuoles, were observed in the plasma cells in various storage diseases, with the exception of late infantile metachromatic leukodystrophy. Thus, electron microscopy of rectal mucosa is useful in making diagnoses and examining plasma cells in some neuronal storage diseases.

Adolescent↗
PubMed1981

Formation of omega- and (omega-1)-hydroxyfatty acids and plausible formation of ketofatty acid from microsomal phospholipids.

Rat liver microsomes labeled with spin-labeled phosphatidylcholine release the label into the aqueous phase during the aerobic incubation with NADPH (Biochem. Biophys. Res. Commun. (1979) 87, 300-307). To establish the chemical nature of the released moiety, microsomes were labeled with [14C]phosphatidylcholine. When the 14C-labeled microsomes were incubated with NADPH under aerobic conditions, a few percent of the radioactivity was liberated into the aqueous phase within 60 min. Thin-layer chromatographic analysis of the radioactive substance liberated showed the presence of hydroxylated fatty acids derived from the 2-position of glycerol moiety. About one-third of the fatty acids formed from [14C]phosphatidylcholine during the incubation were converted into hydroxy-derivatives. Gas chromatography/mass spectrometry analysis further confirmed an NADPH-dependent formation of 16-hydroxypalmitic acid, 15-hydroxypalmitic acid, and hydroxy-derivatives of other fatty acids from the phospholipids of the microsomal membrane. Evidence was also obtained indicating the formation of ketopalmitic acid.

Animals↗
PubMed1981

Circular dichroic studies on the interaction between reduced nicotinamide adenine dinucleotide phosphate-adrenodoxin reductase and adrenodoxin.

Circular dichroic spectra of NADPH-adrenodoxin reductase, adrenodoxin and the complex between oxidized adrenodoxin reductase and oxidized adrenodoxin were studied. A 1 : 1 complex formation between adrenodoxin reductase and adrenodoxin resulted in the appearance of a distinct difference CD spectrum, which was obtained by subtraction of the sum of their CD spectra from the CD spectrum of the mixture of the two proteins. The difference CD spectrum showed a broad trough between 500 and 600 nm and CD extrema at 452, 383, and 350 nm. This spectrum may reflect a change in the environment of either or both of the protein chromophores. By applying the curve-fitting method to analyze the ellipticity change at 452 nm of the difference CD spectrum obtained on titration of a fixed amount of adrenodoxin reductase with various amounts of adrenodoxin, we directly obtained a value of 4.56 x 10(-7) M (S.D. 9.58 x 10(-8) M) as the dissociation constant of the oxidized complex. We also studied the change of the difference ellipticity induced by the addition of salt and obtained dissociation constants for the oxidized complex at various concentrations of NaCl. These values were larger than those obtained previously by kinetic methods, measurements of NADPH-cytochrome c reductase and NADPH-DCIP reductase activities. Further, we examined the relationship between the change of these activities on the addition of salt and the complex concentration calculated using the dissociation constant obtained in this study and found that the change of these activities could not be attributed simply to dissociation of the oxidized complex.

Adrenodoxin↗
PubMed1981

Resonance Raman study of D-amino acid oxidase-inhibitor complexes.

The resonance Raman (RR) spectra of the complexes of D-amino acid oxidase (DAO) with benzoate derivatives were measured. The RR spectra of complexes of DAO with benzoate derivatives excited at 514.5 nm are similar to one another and also similar to that of oxidized flavin. In the cases of DAO-o-NH2-benzoate and DAO-o-OH-benzoate complexes, however, the line at 568 or 565 cm-1, derived from the benzoate derivative, was intensified. In the case of DAO-o-NH2-benzoate complex, which has an intense charge-transfer absorption band, the resonance enhancement of the Raman lines at 1583 and 568 cm-1 in the RR spectrum excited at 632.8 nm is striking. The former line is known to involve the vibrational displacements of the N(5) and C(4a) atoms of isoalloxazine and the latter is considered to be derived from a ring deformation mode of o-NH2-benzoate. This suggests that the o-NH2-benzoate molecule lies along the N(5)-C(4a) bond and parallel to the flavin face. A Raman line derived from o-OH-benzoate in the RR spectrum of DAO-o-OH-benzoate complex excited at 514.5 nm was detected. This result supports the view that the complex has a charge-transfer band, as has been pointed out by Massey and Ganther. Also, the spectrum of quasi-DAO-o-OH-benzoate complex is identical with that of the complex of DAO, suggesting that the active sites of these two enzymes have similar structures.

Aminobenzoates↗
PubMed1981

Electronmicroscopy of conjunctival biopsy in mannosidosis.

Electronmicroscopic examination was performed on conjunctival biopsies from two adolescent siblings with mannosidosis. Fibroblasts and endothelial cells contained membrane-bound vacuoles and vesicles that contained homogeneous osmiophilic globules. These vesicles seem to be pathognomonic of mannosidosis. Plasma cells also contained membrane-bound vacuoles, suggesting inhibition of the immunoglobulin production.

Adult↗
PubMed1980

Formation of heterotopic granule cell in mouse cerebellum after neonatal administration of cytosine arabinoside.

The mice, ICR-JCL strain, were injected s.c. with 30 mg/kg body weight of cytosine arabinoside at the age of 2, 3, and 4 days. The external granular layer of these mice was destructed selectively, and subsequently these mice developed abnormal cytoarchitecture in the cerebellum, such as disarrangement of Purkinje cells and heterotopic granule cells in the molecular layer. This study was undertaken to elucidate the mechanism in the formation of heterotopic granule cells. In the cerebellum of the treated mouse, some mossy fibers and glomerular collaterals of climbing fibers extended abnormally even into the molecular layer by the age of 10 days, since no granule cells migrated to the inner granular layer until about 10 days when granule cell production started again in the regenerated external granular layer. Subsequently, these fibers, i.e. axons which extended into the molecular layer, established synapses in the molecular layer with the dendrites of migrating granule cells. These granule cells had no need to migrate to the inner granular layer, and so they remained in the molecular layer as heterotopic granule cells.

Age Factors↗
PubMed1980

Neuronal depletion of cerebellum in late infantile metachromatic leukodystrophy.

The cerebellums of two children with late infantile metachromatic leukodystrophy were investigated by light and electron microscopy. These observations showed that the morphological abnormalities were comprised not only of severe demyelination and presence of metachromatic granules but also marked loss of Purkinje cells and granule cells. The depletion of Purkinje cells is considered to have resulted from demyelination of their myelinated axons. On the other hand, the reduction of granule cells is considered to be caused by the loss of Purkinje cells and presynaptic elements such as mossy fibers and glomerular collaterals of climbing fibers. The depletion of these neurons induced destruction of synaptic connection in the cerebellum.

Cerebellar Diseases↗
PubMed1980

A study of the absorption, circular dichroism and magnetic circular dichroism spectra of a flavin derivative. The pi-electronic structure of 8-amino-8-demethyl-D-riboflavin.

The absorption, CD and MCD spectra of 8-amino-8-demethyl-D-riboflavin, which showed novel spectral properties, were measured in the spectral region from 220 nm to 540 nm and the spectra obtained were analyzed in terms of Gaussian wave number curves (from band I to band X). Semi-empirical calculations of the Pariser-Parr-Pople Hamiltonian were performed to investigate the novel spectral properties and the reactivity at the 5-position. The theoretical results as well as the experimental results showed that the novel spectral properties were a result of amino substitution at the 8-position.

Chemical Phenomena↗