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S Hada

Publications and source records attributed to S Hada.

28 records · Page 2Linked to original sources
PubMed1985

Spin-state equilibrium in the model complexes of azide hemoprotein.

Addition of NaN3 to ferric protohemin biscoordinated with 1-methylimidazole (1-MeIm) or 2-methylimidazole (2-MeIm) in (CH3)2SO resulted in sizeable visible absorption changes, corresponding to the formation of the mixed ligand complexes, hemin X N-3 X 1-MeIm and hemin X N-3 X 2-MeIm. The visible absorption spectrum of the 1-MeIm complex was closely similar to those of azide hemoproteins, while the 2-MeIm derivative exhibited intensified 500 and 625 nm bands and depressed 540 and 570 nm peaks. The iron-bound N-3 of the model complexes exhibited two infrared stretching bands, which were assigned to the high- and low-spin peaks. The intensity of the high-spin infrared peaks increased at higher temperature. From the analyses of the infrared spectral changes, the thermodynamic values of the thermal spin equilibria were determined to be delta H = -3920 cal/mol and delta S = -11.1 e.u. for hemin X N-3 X 1-MeIm and delta H = -2150 cal/mol and delta S = 7.9 e.u. for hemin X N-3 X 2-MeIm. The thermodynamic values of the 1-MeIm complex are similar to the reported values for azide metmyoglobin, suggesting that the contribution from the nonbonded porphyrin-globin contacts to the spin equilibrium is small in azide metmyoglobin. Comparison of the delta H and delta S values among model systems indicates that delta H and delta S compensation similar to that observed in hemoprotein also holds in the models. This may suggest an underlying common denominator for the spin-equilibrium mechanisms in hemins and hemoproteins.

Azides↗
PubMed1984

Mercury exanthem.

Explore the source record for details and available documents.

Dermatitis, Contact↗
PubMed1983

Quaternary structure and spin-state transition in azide methemoglobin A.

The temperature-dependent ultraviolet and visible absorption changes of human azide methemoglobin with and without inositol hexaphosphate (IHP) were examined in a 4'-35 degrees C range. The 537-nm absorption change of IHP-free hemoglobin was about 1.2-fold larger than that of IHP-bound hemoglobin. The data were analyzed by considering the thermal spin equilibrium within the R and T conformers and the quaternary equilibrium between the two conformers. The spin equilibrium analysis suggested that the T conformer has a larger high-spin content than the R conformer. The quaternary equilibrium analysis, on the other hand, showed that the T conformer is more populated at lower temperature. The thermodynamic values for the quaternary equilibrium were determined to be delta H = -13.3 kcal/mol and delta S = -47.6 eu. The large negative delta H and delta S values were compensated for each other to give a small energy difference between the two quaternary states, e.g., delta G4 = 670 cal/mol of tetramer at 20 degrees C. The coincidence of the temperature-dependent IHP-induced changes in the visible and ultraviolet absorptions of heme and aromatic chromophores at the subunit boundaries suggested that the quaternary transition energy is not localized at heme moiety. The reverse temperature dependence of the T conformer fraction as compared with the high-spin fraction of heme iron was interpreted as indicating that the appearance of the T state is not directly coupled with an increase in the strain of Fe-N(F8 His) linkage in azide methemoglobin A.

Azides↗
PubMed1983

Quantitative structure--activity relationship of double alkyl chain drugs.

The quantitative structure--activity relationship of double alkyl chain drugs, including alkanols, aliphatic esters, ketones, barbiturates, amphetamines, butyrylcholinesterase inhibitors, antimalarials, and rifamycin amides, is investigated. A series of double-chain homologues, CnH2n+1XCmH2m+1, in which n changes, keeping m constant, is classified into three types: in type IIL, n greater than m; in type IIE, n = m; in type IIS, n less than m. When a linear relationship, vis., log (1/C) = an + b, holds, the slope a depends on the type; aI greater than or equal to aIIL greater than aIIE greater than aIIS. Here aI means the slope for single-chain homologues. The same order is observed for the equation, log hydrophobicity = an + b, where the hydrophobicity of drug denotes the water solubility, the critical micelle concentration, and the partition coefficient for the 1-octanol--water phases. Therefore, decreased biological activity of a double-chain drug relative to that of a single-chain isomer can be explained by a decreased hydrophobicity of the double-chain drug, due to the intramolecular association of these chains in water. When a parabolic relationship between log (1/C) and n holds, the optimum n depends on the type: nopI less than nopIIL less than nopIIE. This order is also explicable on the basis of a decreased hydrophobicity of double-chain drug. The N-dealklation rate of amphetamines in vivo appears to be affected by the steric factor as well as the hydrophobic factor. A decreased hydrophobicity of double-chain compounds should be taken into consideration for estimating their partition coefficients.

Alkylation↗
PubMed1983

Mercury exanthem.

We experienced 15 patients with generalized rash, mostly appearing a day or two after breaking a clinical thermometer or during dental treatment. Similar skin manifestations were revealed, suggestive at first glance of mercury exanthem, i.e. diffuse symmetrical erythema predominantly on major fluxural areas. An inverted triangular or V-shaped erythema on both upper antero-medial thighs was a common feature. Severe cases had miliary pustules and/or purpura on erythematous skin. Pruritus or burning sensation was relatively mild. Pyrexia or malaise was a complaint of more than half the patients. Most of the patients had a previous history of contact dermatitis to Mercurochrome, and by patch-testing were found to have contact allergy to several mercurials, especially inorganic ones. Until recently, Mercurochrome had been most widely used as a topical disinfectant in Japan. This seems to be a possible cause of the high incidence of contact allergy to mercurials in this country. From our findings we feel that our patients had developed systemic contact dermatitis due to inhalation of mercury vapor.

Adolescent↗
PubMedDate not supplied

Transient shrinkage of a uterine leiomyosarcoma treated with GnRH agonist for a presumed uterine leiomyoma: comparison of magnetic resonance imaging finding before and during GnRH agonist treatment.

We present a case of a premenopausal woman treated with GnRH agonist for a presumed uterine leiomyoma. This tumor reduced at first, but subsequent surgical specimens revealed a leiomyosarcoma. Magnetic resonance imaging (MRI), one of the most useful modalities for distinguishing between uterine leiomyoma and leiomyosarcoma, was undertaken twice, before GnRH agonist administration and then after 6 months of GnRH agonist administration. Apparent differences were observed between these MRI findings. Tumor-size reduction with GnRH agonist treatment does not always mean that the possibility of a leiomyosarcoma should be ruled out.

Antineoplastic Agents, Hormonal↗