Characterization of an NH-pi interaction in Co(III) ternary complexes with aromatic amino acids.

The NH-pi interaction has been detected in the crystal structures of Co(III) ternary complexes with N,N-bis(carboxymethyl)-(S)-phenylalanine (BCMPA) and aromatic amino acids including (S)-phenylalanine ((S)-Phe), (R)-phenylalanine ((R)-Phe), and (S)-tryptophan ((S)-Trp)). Additionally, this interaction has been studied in solution for Co(III) ternary complexes with BCMPA or NTA (NTA = nitrilotriacetic acid) and several amino acids (AA) by means of electronic absorption, circular dichroism (CD), and (1)H NMR spectroscopies. The CD intensities of the Co(III) complexes with aromatic amino acids measured in the d-d region ( approximately 20.5 x 10(3) cm(-)(1)) are significantly decreased in ethanol solutions relative to water. Analogous complexes with aliphatic amino acids do not exhibit this solvent effect. The (1)H NMR spectra of the Co(III) complexes with aromatic amino acids measured in DMSO-d(6) exhibit upfield shifts of the NH peaks compared with those with aliphatic amino acids, which suggest a shielding effect due to the aromaticity. The upshift values coincide with those experimentally evaluated from the crystal structures. The magnitude of the upfield shifts agrees well with Hammett's rule, indicating that the increase of pi-electron densities on the aromatic rings leads attractive NH-pi interaction that exerts a larger shielding effect for the NH protons. In ligand-substitution reactions of the carbonatocobalt(III) complexes with amino acids, the yields of those with aromatic amino acids are higher than the yields obtained for complexes with aliphatic amino acids. This observation is discussed in connection with the important contribution of the NH-pi interaction as one of the promotion factors in the reaction.

Syntheses, structures, and properties of tetrakis(mu-acetato)dirhodium(II) complexes with axial pyridine nitrogen donor ligands with or without assistance of hydrogen bonds.

Eight adducts of Rh2(O2CCH3)4 with axial pyridine derivatives that contain hydrogen-bonding amino and/or steric methyl substituents in the 2- and 6-positions have been prepared and examined by electronic absorption and 1H NMR spectroscopy in solution and by elemental, IR, thermogravimetric, and X-ray diffraction analyses in the solid state. The results indicated that strong hydrogen bonding interactions between Rh2(O2CCH3)4 and axially coordinated pyridine derivatives with a 2- or 6-amino group occur in both solution and the solid state and contribute to the higher thermal stability of the molecular assembly of dirhodium complexes. It was demonstrated that such a combination of coordinate and hydrogen bonds is useful as a building tool in designing and constructing new organic-inorganic hybridized compounds and supramolecular architectures.

A novel diiron complex as a functional model for hemerythrin.

Diiron(II) complexes with a novel dinucleating polypyridine ligand, N,N,N',N'-tetrakis(6-pivalamido-2-pyridylmethyl)-1,3-diaminopropan-2-ol (HTPPDO), were synthesized as functional models of hemerythrin. Structural characterization of the complexes, [Fe2II(Htppdo)(PhCOO)](ClO4)3 (1), [Fe2II(Htppdo)((p-Cl)PhCOO)](ClO4)3 (2), [Fe2II(Htppdo)((p-Cl)PhCOO)](BF4)3 (2') and [Fe2II(tppdo)((p-Cl)PhCOO)](ClO4)2 (3), were accomplished by electronic absorption, and IR spectroscopic, electrochemical, and X-ray diffraction methods. The crystal structures of 1 and 2' revealed that the two iron atoms are asymmetrically coordinated with HTPPDO and bridging benzoate. One of the iron centers (Fe(1)) has a seven-coordinate capped octahedral geometry comprised of an N3O4 donor set which includes the propanol oxygen of HTPPDO. The other iron center (Fe(2)) forms an octahedron with an N3O3 donor set and one vacant site. The two iron atoms are bridged by benzoate (1) or p-chlorobenzoate (2). On the other hand, both Fe atoms of complex 3 are both symmetrically coordinated with N3O4 donors and two bridging ligands; benzoate and the propanolate of TPPDO. Reactions of these complexes with dioxygen were followed by electronic absorption, resonance Raman and ESR spectroscopies. Reversible dioxygen-binding was demonstrated by observation of an intense LMCT band for O2(2-) to Fe(III) at 610 (1) and 606 nm (2) upon exposure of dioxygen to acetone solutions of 1 and 2 prepared under an anaerobic conditions at -50 degrees C. The resonance Raman spectra of the dioxygen adduct of 1 exhibited two peaks assignable to the nu(O-O) stretching mode at 873 and 887 cm(-1), which shifted to 825 and 839 cm(-1) upon binding of (18)O2. ESR spectra of all dioxygen adducts were silent. These findings suggest that dioxygen coordinates to the diiron atoms as a peroxo anion in a mu-1,2 mode. Complex 3 exhibited irreversible dioxygen binding. These results indicate that the reversible binding of dioxygen is governed by the hydrophobicity of the dioxygen-binding environment rather than the iron redox potentials.

Disseminated coccidioidomycosis.

We report a case of disseminated coccidioidomycosis in a 39-year-old Japanese male whose illness developed after returning from a trip to an endemic area. He showed positive coccidioidin skin reaction throughout the entire course of his illness. The primary lesion in the lung subsequently spread to the bone. While the patient was on treatment with 5-FC, he made another trip to the same endemic area. After this episode, he developed pulmonary symptoms and cutaneous nodules on his wrist. The possibility of reinfection with Coccidioides immitis is discussed. Electron microscopy of the cutaneous nodules revealed that the spherules examined maintained their structural integrity in the granulomatous lesion, suggesting the high viability of the organism. Host-parasitic interaction in coccidioidomycosis is discussed.

Muscle regeneration and cell-mediated cytotoxicity in the autologous muscle culture of dermatomyositis.

Muscle culture from a dermatomyositis patient was performed to investigate the muscle regeneration and cell-mediated cytotoxicity. In the primary culture, spindle-shaped mononuclear myoblasts exponentially increased in number. In the secondary culture, the myotubes fused with the myoblasts and/or other myotubes into large thick syncytia. The cell morphology and growth pattern of the cultured muscle cells in dermatomyositis were identical to those of normal healthy controls. The autologous mononuclear cells added in the secondary culture of day 14 adhered to the surface membrane of the myotubes. Three days after this treatment, the myotubes underwent degenerative changes. On the other hand, in two series of sister cultures, each added with the autologous serum and control medium, no remarkable morphological changes were observed. The results of the present study suggest that dermatomyositis could be precipitated by the associated abnormal cell-mediated cytotoxicity, but not by abnormalities in muscle fibers per se.

Segmented heterochromia in black scalp hair associated with iron-deficiency anemia. Canities segmentata sideropaenica.

A newly recognized disorder of black scalp hair is characterized by the irregularly alternating segmentation of hair into dark and light bands. A 15-year-old girl had segmented heterochromic scalp hair in association with iron-deficiency anemia. The clinical and laboratory investigations support the view that low serum iron levels play a critical role in reducing eumelanogenesis and in the possible failure of melanin transfer. The segmented heterochromic hair recovered completely after iron supplementation, which coincided with increased eumelanogenesis in the recovered hair. This clinical experience indicated participation of iron in the kinetics of melanogenesis within the follicular melanocytes.

Eccrine spiradenoma. An electron microscopic study.

Electron-microscopic studies of two typical lesions of eccrine spiradenoma were performed to correlate ultrastructure and histopathology. The salient ultramorphological features of the parenchyma were an adenoid cystic organization composed of epithelial, myoepithelial, and nonepithelial cell types, and the presence of intracytoplasmic luminae within the epithelial cells. There were no indications that the parenchyma was secretorily active. The stroma ramified through the parenchyma, occupying extensive areas and forming tenuous septa of the loose connective tissue in which blood vessels and nerve fibers were embedded. Profiles of cystoid spaces resulting from invagination of stroma into the parenchyma were frequently encountered. Based on our observations, eccrine spiradenoma appears to differentiate toward ductal structures of eccrine sweat apparatus.

Ultrastructural study of the histogenesis of membranocystic lesions (Nasu) in diabetics.

In order to clarify the histogenesis of membranocystic lesion (MCL) of the skin, 14 biopsies obtained from the shins and feet of diabetics were examined by light and electron microscopy. MCL was observed in 10 of 14 cases, including 7 pigmented pretibial patches (PPP), each a case of diabetic bulla, callus of the knee, and ordinary psoriasis. Ultrastructurally, MCL was characterized by 3 fundamental types of structure: tortuous thick bands composed of well-developed minute tubular structures; shrubbery-like structures in sectional profile consisting of accumulated tiny cysts and microprojections; and thin membranes without minute tubular structures. The small vessels in the dermis and subcutaneous tissue indicated the changes of microangiopathy. Present observations suggested that MCL was derived from subcutaneous fat cells and was displaced into the dermis to be disposed by histiocytes. Circulatory disturbance due to diabetic microangiopathy in the subcutaneous tissue could be one of the contributory factors in the formation of MCL.

Statistical survey of skin changes in Japanese neonates.

We observed 5387 infants over 10 years in weekly visits to a neonatal ward and obtained the following frequency data on these skin changes: erythema toxicum neonatorum, 40.8%; perianal dermatitis, 18.9%; scrotal pigmentation, 15.2%; miliaria, 8.5%; and adnexal polyp of neonatal skin, 4.1%. The frequencies of the types of birthmarks were: mongolian spots, 81.5%; salmon patches, 22.3%; nevocellular nevi, 2.7%; port-wine stains, 2.1%; strawberry marks, 1.7%; café au lait spots, 1.7% (including a case of von Recklinghausen's disease); epidermal and sebaceous nevi, 0.3%; accessory auricles, 0.3%; and smooth muscle hamartomas, 0.2%. A positive relationship was observed between infant maturity and the prevalence of erythema toxicum neonatorum. Apart from candidiasis, neonatal skin infections were extremely rare.

Chlorella photosensitization. New phytophotodermatosis.

Swelling followed by erythematopurpuric lesions on sun-exposed areas of the body developed in five patients. All patients were found to have ingested chlorella. The histopathologic changes consisted of swelling of endothelial cells and thrombosis of small blood vessels in the dermis and the subcutaneous fatty tissue. The photosensitizing agent contained in chlorella tablets was proved to be pheophorbide -a and its ester.