Structural Analysis of Crystalline R(+)-α-Lipoic Acid-α-cyclodextrin Complex Based on Microscopic and Spectroscopic Studies.

R(+)-α-lipoic acid (RALA) is a naturally-occurring substance, and its protein-bound form plays significant role in the energy metabolism in the mitochondria. RALA is vulnerable to a variety of physical stimuli, including heat and UV light, which prompted us to study the stability of its complexes with cyclodextrins (CDs). In this study, we have prepared and purified a crystalline RALA-αCD complex and evaluated its properties in the solid state. The results of ¹H NMR and PXRD analyses indicated that the crystalline RALA-αCD complex is a channel type complex with a molar ratio of 2:3 (RALA:α-CD). Attenuated total reflection/Fourier transform infrared analysis of the complex showed the shift of the C=O stretching vibration of RALA due to the formation of the RALA-αCD complex. Raman spectroscopic analysis revealed the significant weakness of the S-S and C-S stretching vibrations of RALA in the RALA-αCD complex implying that the dithiolane ring of RALA is almost enclosed in glucose ring of α-CD. Extent of this effect was dependent on the direction of the excitation laser to the hexagonal morphology of the crystal. Solid-state NMR analysis allowed for the chemical shift of the C=O peak to be precisely determined. These results suggested that RALA was positioned in the α-CD cavity with its 1,2-dithiolane ring orientated perpendicular to the plane of the α-CD ring.

Desorption of intrinsic cesium from smectite: inhibitive effects of clay particle organization on cesium desorption.

Fine clay particles have functioned as transport media for radiocesium in terrestrial environments after nuclear accidents. Because radiocesium is expected to be retained in clay minerals by a cation-exchange reaction, ascertaining trace cesium desorption behavior in response to changing solution conditions is crucially important. This study systematically investigated the desorption behavior of intrinsic Cs (13 nmol/g) in well-characterized Na-montmorillonite in electrolyte solutions (NaCl, KCl, CaCl2, and MgCl2) under widely differing cation concentrations (0.2 mM to 0.2 M). Batch desorption experiments demonstrated that Cs(+) desorption was inhibited significantly in the presence of the environmental relevant concentrations of Ca(2+) and Mg(2+) (>0.5 mM) and high concentrations of K(+). The order of ability for Cs desorption was Na(+) = K(+) > Ca(2+) = Mg(2+) at the highest cation concentration (0.2 M), which is opposite to the theoretical prediction based on the cation-exchange selectivity. Laser diffraction grain-size analyses revealed that the inhibition of Cs(+) desorption coincided with the increase of the clay tactoid size. Results suggest that radiocesium in the dispersed fine clay particles adheres on the solid phase when the organization of swelling clay particles occurs because of changes in solution conditions caused by both natural processes and artificial treatments.

Spectroscopic studies of R(+)-α-lipoic acid--cyclodextrin complexes.

α-Lipoic acid (ALA) has a chiral center at the C6 position, and exists as two enantiomers, R(+)-ALA (RALA) and S(-)-ALA (SALA). RALA is naturally occurring, and is a cofactor for mitochondrial enzymes, therefore playing a major role in energy metabolism. However, RALA cannot be used for pharmaceuticals or nutraceuticals because it readily polymerizes via a 1,2-dithiolane ring-opening when exposed to light or heat. So, it is highly desired to find out the method to stabilize RALA. The purpose of this study is to provide the spectroscopic information of stabilized RALA and SALA through complexation with cyclodextrins (CDs), α-CD, ß-CD and γ-CD and to examine the physical characteristics of the resultant complexes in the solid state. The RALA-CD structures were elucidated based on the micro fourier transform infrared (FT-IR) and Raman analyses. The FT-IR results showed that the C=O stretching vibration of RALA appeared at 1717 cm⁻¹ and then shifted on formation of the RALA-CD complexes. The Raman spectra showed that the S-S and C-S stretching vibrations for RALA at 511 cm⁻¹ (S-S), 631 cm⁻¹ (C-S) and 675 cm⁻¹ (C-S) drastically weakened and almost disappeared upon complexation with CDs. Several peaks indicative of O-H vibrations also shifted or changed in intensity. These results indicate that RALA and CDs form host-guest complexes by interacting with one another.

Sorption of Eu(III) on granite: EPMA, LA-ICP-MS, batch and modeling studies.

Eu(III) sorption on granite was assessed using combined microscopic and macroscopic approaches in neutral to acidic conditions where the mobility of Eu(III) is generally considered to be high. Polished thin sections of the granite were reacted with solutions containing 10 µM of Eu(III) and were analyzed using EPMA and LA-ICP-MS. On most of the biotite grains, Eu enrichment up to 6 wt % was observed. The Eu-enriched parts of biotite commonly lose K, which is the interlayer cation of biotite, indicating that the sorption mode of Eu(III) by the biotite is cation exchange in the interlayer. The distributions of Eu appeared along the original cracks of the biotite. Those occurrences indicate that the prior water-rock interaction along the cracks engendered modification of biotite to possess affinity to the Eu(III). Batch Eu(III) sorption experiments on granite and biotite powders were conducted as functions of pH, Eu(III) loading, and ionic strength. The macroscopic sorption behavior of biotite was consistent with that of granite. At pH > 4, there was little pH dependence but strong ionic strength dependence of Eu(III) sorption. At pH < 4, the sorption of Eu(III) abruptly decreased with decreased pH. The sorption behavior at pH > 4 was reproducible reasonably by the modeling considering single-site cation exchange reactions. The decrease of Eu(III) sorption at pH < 4 was explained by the occupation of exchangeable sites by dissolved cationic species such as Al and Fe from granite and biotite in low-pH conditions. Granites are complex mineral assemblages. However, the combined microscopic and macroscopic approaches revealed that elementary reactions by a single mineral phase can be representative of the bulk sorption reaction in complex mineral assemblages.

Microdiamond in a low-grade metapelite from a Cretaceous subduction complex, western Kyushu, Japan.

Microdiamonds in metamorphic rocks are a signature of ultrahigh-pressure (UHP) metamorphism that occurs mostly at continental collision zones. Most UHP minerals, except coesite and microdiamond, have been partially or completely retrogressed during exhumation; therefore, the discovery of coesite and microdiamond is crucial to identify UHP metamorphism and to understand the tectonic history of metamorphic rocks. Microdiamonds typically occur as inclusions in minerals such as garnet. Here we report the discovery of microdiamond aggregates in the matrix of a metapelite from the Nishisonogi unit, Nagasaki Metamorphic Complex, western Kyushu, Japan. The Nishisonogi unit represents a Cretaceous subduction complex which has been considered as an epidote-blueschist subfacies metamorphic unit, and the metapelite is a member of a serpentinite mélange in the Nishisonogi unit. The temperature condition for the Nishisonogi unit is 450 °C, based on the Raman micro-spectroscopy of graphite. The coexistence of microdiamond and Mg-carbonates suggests the precipitation of microdiamond from C-O-H fluid under pressures higher than 2.8 GPa. This is the first report of metamorphic microdiamond from Japan, which reveals the hidden UHP history of the Nishisonogi unit. The tectonic evolution of Kyushu in the Japanese Archipelago should be reconsidered based on this finding.

Cr-spinel records metasomatism not petrogenesis of mantle rocks.

Mantle melts provide a window on processes related to global plate tectonics. The composition of chromian spinel (Cr-spinel) from mafic-ultramafic rocks has been widely used for tracing the geotectonic environments, the degree of mantle melting and the rate of mid-ocean ridge spreading. The assumption is that Cr-spinel's core composition (Cr# = Cr/(Cr + Al)) is homogenous, insensitive to post-formation modification and therefore a robust petrogenetic indicator. However, we demonstrate that the composition of Cr-spinel can be modified by fluid/melt-rock interactions in both sub-arc and sub-mid oceanic mantle. Metasomatism can produce Al-Cr heterogeneity in Cr-spinel that lowers the Cr/Al ratio, and therefore modifies the Cr#, making Cr# ineffective as a geotectonic and mantle melting indicator. Our analysis also demonstrates that Cr-spinel is a potential sink for fluid-mobile elements, especially in subduction zone environments. The heterogeneity of Cr# in Cr-spinel can, therefore, be used as an excellent tracer for metasomatic processes.

Induction of inducible nitric oxide synthase and apoptosis by LPS and TNF-alpha in nasal microvascular endothelial cells.

CONCLUSION: This study demonstrates that the co-administration of lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha) (LPS/TNF-alpha) can induce the expression of inducible nitric oxide synthase (iNOS), which results in the generation of apoptosis in cultured human nasal microvascular endothelial cells (HNMECs). Since LPS and TNF-alpha have been suggested to play an important role in the pathophysiology of nasal disease, we conclude that microvascular leakage may therefore contribute to the inflammatory process in nasal disease, such as allergic rhinitis and asthma. MATERIALS AND METHODS: The HNMECs were obtained from the inferior turbinate and subsequently cultured. The expression of iNOS induced by both the LPS and TNF-alpha was investigated by fluorescent immunohistochemistry, using confocal laser microscopy. The DNA-binding dye, Hoechist 33342, was also used to analyze the apoptosis in the HNMECs. RESULTS: The fluorescent immunohistochemistory study demonstrated that LPS and TNF-alpha induced the expression of iNOS in HNMECs. LPS/TNF-alpha remarkably augmented the expression of iNOS in HNMECs in comparison to stimulation by either LPS or TNF-alpha alone. LPS/TNF-alpha also induced apoptosis in HNMECs. 1400W, a highly selective inhibitor of iNOS, inhibited both the expression of iNOS and the apoptosis induced by LPS/TNF-alpha.

Experimental otitis media with effusion induced by leukotriene D4.

OBJECTIVE: inflammatory mediators such as prostaglandins (PGs), leukotrienes (LTs), and platelet-activating factor (PAF) have been identified in human middle ear effusions (MEEs), as well as in the experimentally induced MEEs of animals. However, the exact function of LTs in the middle ear cavity is still unknown. In this study, the role of LTs was investigated using an experimental model in which OME was induced by LTD4. METHODS: to examine whether leukotrienes (LTs) induce otitis media with effusion (OME), 2x10(-6), 2x10(-5), 1x10(-4) and 2x10(-4) M of LTD4 was injected into the rat ear. The severity of OME was assessed based on the histological findings. The concentrations of IL1-beta, TNF-alpha, and GRO/CINC-1 in MEE were also measured. Additionally the therapeutic efficacy of a specific LTs antagonist, pranlukast on experimental OME was investigated. RESULTS: all ears developed middle ear effusion (MEE) within 24 h and about 50% of the animals continued to demonstrate MEE for 14 days in the 1x10(-4) and 2x10(-4) M groups. The cytokine levels seemed to correspond well with the persistence of OME. The oral administration of a specific LTs antagonist, pranlukast, was found to alleviate the experimental OME. CONCLUSION: these findings suggest that LTs appear to plays an important role in the pathogenesis of OME.

Earth's youngest exposed granite and its tectonic implications: the 10-0.8 Ma Kurobegawa Granite.

Although the quest for Earth's oldest rock is of great importance, identifying the youngest exposed pluton on Earth is also of interest. A pluton is a body of intrusive igneous rock that crystallized from slowly cooling magma at depths of several kilometers beneath the surface of the Earth. Therefore, the youngest exposed pluton represents the most recent tectonic uplift and highest exhumation. The youngest exposed pluton reported to date is the Takidani Granodiorite (~ 1.4 Ma) in the Hida Mountain Range of central Japan. Using LA-ICP-MS and SHRIMP U-Pb zircon dating methods, this study demonstrates that the Kurobegawa Granite, also situated in the Hida Mountain Range, is as young as ~ 0.8 Ma. In addition, data indicate multiple intrusion episodes in this pluton since 10 Ma with a ~ 2-million-year period of quiescence; hence, a future intrusion event is likely within 1 million years.