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Biomedical subjects

H Oyanagi

Publications and source records attributed to H Oyanagi.

At least 73 records · Page 4Linked to original sources
PubMed1990

Mn K-edge XANES spectroscopy of a photosynthetic O2-evolving complex. High-quality pre-edge features and distinct fine structures in the S1- and S2-states.

High-resolution XANES (X-ray Absorption Near Edge Structure) spectroscopy for Mn in the S1 and S2 states of the spinach photosynthetic O2-evolving complex revealed distinct features in K-edge spectra, when a high signal-to-noise (S/N) ratio of ca. 80 with a low and constant background-to-signal (B/S) ratio of 0.15 to 0.18 was attained. Six features resolved in each S-state spectrum involve a pre-edge feature due to 1s----3d transitions, a main-edge feature possibly due to 1s----4s transitions and four fine structures superimposed on the principal absorption bands due to 1s----4p* transitions. The high-quality pre-edge features were analyzed according to a parametric ligand-field theory in comparison with those of some typical authentic Mn complexes. It was deduced that i) all of the four Mn ions in the S1-state are octahedrally coordinated and two of them constitute a di-mu-oxo bridged Mn(III, III) dimeric subunit; ii) the bridged Mn(III) ions are further bridged by a deprotonated water dimer, (HOHOH)-, and coordinated by imidazole-N and carboxylate-O- on the opposite side of the Mn atom from the di-mu-oxo bridge; iii) the other two Mn ions exist in the form of Mn(III) monomeric subunits; and iv) upon the S1----S2 transition, only the bridged Mn(III,III) is oxidized to Mn(III,IV). The distinct change in the principal absorption band shape upon the S1----S2 transition is briefly discussed to obtain the XANES evidence for a tetrameric Mn-cluster.

Cell Membrane↗
PubMed1990

Paracoccus aminophilus sp. nov. and Paracoccus aminovorans sp. nov., which utilize N,N-dimethylformamide.

Two methylamine- and N,N-dimethylformamide-utilizing Paracoccus spp. are described. These bacteria are gram-negative, nonsporeforming, nonmotile, coccoid or short rod-shaped organisms. Their DNA base composition is 62 to 68 mol% G + C. Their cellular fatty acids include large amounts of C18:1 acid. Their major hydroxy acids are 3-OH C10:0 and 3-OH C14:0 acids. The major ubiquinone is Q-10. These bacteria are distinguished from Paracoccus denitrificans and Paracoccus alcaliphilus by physiological characteristics and by DNA-DNA-homology. Paracoccus aminophilus sp. nov. and Paracoccus aminovorans sp. nov. are proposed. The type strain of P. aminophilus is DM-15 (= JCM 7686), and the type strain of P. aminovorans is DM-82 (= JCM 7685). Paracoccus halodenitrificans is distinguished from other Paracoccus species on the basis of cellular fatty acid composition, hydroxy fatty acid composition, and DNA-DNA homology. It may not be a valid member of the genus Paracoccus.

Base Composition↗
PubMed1989

Detection of anti-rotavirus IgG, IgM, and IgA antibodies in healthy subjects, rotavirus infections, and immunodeficiencies by immunoblotting.

Immune responses to individual simian rotavirus (SA 11) structural polypeptides were studied with emphasis on specific IgG, IgM, and IgA in paired sera from four children with rotavirus infections. Responses to simian rotavirus (SA 11) were also studied in 103 healthy children, 10 patients with primary immunodeficiency who received intravenous immunoglobulin, and 11 human immunodeficiency virus antibody-positive patients. All samples were immunoblotted for two major polypeptides--VP2 and VP6--of IgG. Immunoblotted IgA and IgM were elevated 2-4 weeks after the onset of the disease (stage II) in patients with rotavirus infection. Immunoblotted IgG remained almost the same at the onset of the disease and stage II. The scores for primary and secondary immunodeficiency patients were lower than for healthy children. The score obtained by totaling all polypeptides found in each individual was compared with the optical density (OD) value obtained by enzyme immunoassay.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Evidence against the importance in the disease process of antibodies to bovine thyroid-stimulating hormone found in some patients with Graves' disease.

The antibody to TSH (TSH-Ab) found in some patients with Graves' disease may be either an antiidiotype (anti-id-Ab) to the TSH receptor antibody (TRAb) or the antigen (idiotype) for which the anti-id-Ab is in fact TRAb. Four groups have found antibodies to bovine TSH (bTSH-Ab) in Graves' disease patients in a TSH binding-inhibiting immunoglobulin (TBII) RRA that uses [125I]bTSH. In this assay serum samples containing bTSH-Ab give highly negative TBII values. The purpose of this study was to look for any clinical significance of potential idiotypic-antiidiotypic network regulation related to bTSH-Ab. Twenty-one (0.49%) of 4285 Graves' disease patients had TBII values less than the mean -4 SD of normal subjects. In all 21, bTSH-Ab was found by incubation of [125I]bTSH with the patient's serum, and significant inhibition of binding of bTSH-Ab to bTSH by human TSH was found in only 3 of these serum samples. We investigated next whether the binding site of the anti-TSH-Ab mimicked the TSH receptor-binding site. Binding of [125I]bTSH to bTSH-Ab-positive serum was not inhibited by bTSH-Ab-negative, thyroid-stimulating immunoglobulin-positive [(+)], and/or TBII(+) immunoglobulin G. In one patient with human TSH-Ab, TSH-Ab appeared and disappeared, and when TSH-Ab was negative, TBII was positive. Inhibition of [125I]bTSH binding to TSH-Ab by the same patient's serum when that patient was serum thyroid-stimulating immunoglobulin(+), TBII(+), and TSH-Ab-negative was sought but not found. Changes in serum TSH-Ab activity and disease activity were not correlated in this patient. In six untreated patients with Graves' hyperthyroidism with bTSH-Ab, the serum T3 and T4 concentrations and the time required to become euthyroid during antithyroid drug treatment were not significantly different from those in 52 such patients without bTSH-Ab. These data suggest that bTSH-Ab is not an anti-id-Ab to TRAb and that TSH-Ab does not directly modulate the activity of Graves' disease.

Animals↗
PubMed1987

High maintenance rate of sinus rhythm after cardioversion in post-thyrotoxic chronic atrial fibrillation.

We performed rhythm conversion on 33 euthyroid patients with post-thyrotoxic atrial fibrillation who do not revert spontaneously to sinus rhythm from atrial fibrillation. The duration of atrial fibrillation ranged from 9 to 59 months (mean 25 +/- 14). The protocol of rhythm conversion was to first attempt pharmacological conversion with disopyramide and then to perform electrical cardioversion on the non-converters. Of 33 patients, 25 were converted to sinus rhythm (6 by disopyramide and 19 by electrical cardioversion), resulting in 8 non-converters. However, it was later discovered that cardioversion had been applied to 4 of the 8 non-converters when these patients had had a recurrence of thyrotoxicosis. These 4 patients were subjected to a second electrical cardioversion after attaining the euthyroid state. Sinus rhythm was restored in all 4 patients, giving a cardioversion rate of 88%. The sinus rhythm was maintained in 25 of the total 29 converters (86%) at the time of follow-up (10-68 months, mean 35 +/- 19 months). Our studies suggest that cardioversion should be encouraged for thyrotoxic atrial fibrillation, even if the duration of atrial fibrillation is long-standing, since there is excellent maintenance of sinus rhythm and even delayed application of cardioversion may improve its success rate.

Adult↗
PubMed1986

Antithyroid drug therapy for Graves' disease during pregnancy. Optimal regimen for fetal thyroid status.

We compared fetal and maternal serum indexes of thyroid status at delivery in 70 patients with Graves' disease who required therapy with thionamides (such as propylthiouracil) during pregnancy. Forty-three mothers required thionamides until delivery (Group 1), whereas the drugs were discontinued during pregnancy after remission in 27 mothers (Group 2). Maternal free thyroxine levels were closely correlated with cord levels in both groups, being essentially identical in Group 2 but slightly lower in fetuses than in mothers in Group 1. Normal maternal free thyroxine levels did not preclude fetal hypothyroidism. The mothers and fetuses in Group 1 had a significantly higher incidence of antibodies that inhibit thyrotropin binding than did those of Group 2. However, a significant correlation between maternal levels of these antibodies and cord levels of free thyroxine or triiodothyronine was found only in Group 2, in which some maternal and cord thyroxine levels were in the thyrotoxic range at delivery, presumably because therapy was discontinued. These findings indicate that high free thyroxine levels and the presence of antibodies that inhibit binding of thyrotropin are useful indexes of the fetal need for antithyroid treatment, and that the thionamide dosage that maintains maternal free thyroxine levels in a mildly thyrotoxic range seems appropriate for maintaining euthyroid status in the fetus.

Antibodies↗
PubMed1986

Hypertrophic cardiomyopathy and thyroid diseases.

The incidence ratio of thyrotoxicosis among 14 patients with thyroid diseases associated with hypertrophic cardiomyopathy was compared with that in 7686 patients with thyroid diseases, to find the possible correlation between thyrotoxicosis and hypertrophic cardiomyopathy. Thyrotoxicosis did not predominate over other thyroid diseases in the 14 patients with hypertrophic cardiomyopathy. Thus, the occurrence of hypertrophic cardiomyopathy does not appear to be associated with thyrotoxicosis.

Adult↗