Stable cavitation induces increased cytoplasmic calcium in L929 fibroblasts exposed to 1-MHz pulsed ultrasound

An increase in cytoplasmic calcium (Ca²⁺ increase) is a second messenger that is often observed under ultrasound irradiation. We hypothesize that cavitation is a physical mechanism that underlies the increase in Ca²⁺ in these experiments. To control the presence of cavitation, the wave type was controlled in a sonication chamber. One wave type largely contained a traveling wave (wave type A) while the other wave type largely contained a standing wave (wave type B). Fast Fourier transform (FFT) analysis of a sound field produced by the wave types ascertained that stable cavitation was present only under wave type A ultrasound irradiation. Under the two controlled wave types, the increase in Ca²⁺ in L929 fibroblasts was observed with fluorescence imaging. Under wave type A ultrasound irradiation, an increase in Ca²⁺ was observed; however, no increase in Ca²⁺ was observed under wave type B ultrasound irradiation. We conclude that stable cavitation is involved in the increase of Ca²⁺ in cells subjected to pulsed ultrasound.     

Energy Transfer between Flavin and Cytochrome c

Energy transfer between photoexcited flavin and cytochrome c has been investigated in order to estimate intermolecular forces between flavin and cytochrome c. The quenching of the fluorescence of flavin by cytochrome c excited at 372 nm was found to be much greater than that excited at 465 nm. This dependence of the quenching on the exciting wavelength is considered to be due to the “prerelaxational” fast energy transfer. From the analysis of the quenching of the fluorescence of FMN and lumiflavin by cytochrome c excited at 465 nm, it was concluded that 1) the quenching is mainly controlled by resonance energy transfer, and 2) the heterogeneous dispersion state of molecules due to electrostatic forces makes the critical transfer distance, R ₀, of the resonance process longer than the real distance. For the quenching of the fluorescence of flavodoxin by cytochrome c, it was found that complex formation is a dominant process and is controlled to a great extent by electrostatic forces. Furthermore, fluorescence decay curves were measured by a single-photon counting method in order to estimate the dynamic processes of flavin fluorescence. The results also showed that the resonance process exists in the energy transfer between flavin and cytochrome c.     

Evaluation of gardenia yellow using crocetin from alkaline hydrolysis based on ultra high performance liquid chromatography and high‐speed countercurrent chromatography

Gardenia yellow is globally the most valuable spice and food color. It is generally a mixture of water‐soluble carotenoid glycosyl esters which consist of crocetin bis(gentiobiosyl) ester as the main component. Crocetin is a natural carotenoid dicarboxylic acid that may be a candidate drug for pharmaceutical development, however, it is either present in trace amounts or is absent in natural gardenia yellow products. We here propose that crocetin produced by alkaline hydrolysis can be used to qualitatively evaluate gardenia yellow products using an ultra high performance liquid chromatographic assay. A useful and efficient isolation technique for isolating high‐purity crocetin from gardenia yellow using high‐speed countercurrent chromatography is described. High‐speed countercurrent chromatographic fractionation followed by an ultra high performance liquid chromatographic assay showed that trans‐crocetin is easily converted to about 15% cis‐crocetin (85% trans‐crocetin). Crocetin in gardenia yellow was quantitatively evaluated. Our approach is based on the hydrolysis process for converting crocetin glycosyl esters to crocetin before evaluation and isolation using the ultra high performance liquid chromatographic and high‐speed countercurrent chromatographic methods. The combination of hydrolysis and chromatographic methods allows evaluation of the purity and quantity of crocetin in gardenia yellow.     

Cyclic single-molecule magnet in heterospin system

The 2:2 complex of Co-carbene is generated by photolysis of [Co(hfpip)2(D2py2(TBA))]2, 1, having a cyclic structure functioning as a single-molecule magnet with Ueff = 96 K and Hc = 10 kOe at 1.9 K after annealing at 70 K.     

Granulation of core particles suitable for film coating by agitation fluidized bed II. A proposal of a rapid dissolution test for evaluation of bitter taste of ibuprofen

To prepare powdered drugs that do not have a bitter taste, a film coating covering the surfaces of the core particles is required. The dissolution rate of ibuprofen from the coated particles changes according to the physical properties of the core particles. In this study, the effects of the physical properties of granules prepared by using several scales of agitation fluidized beds on the drug dissolution rate were investigated. The dissolution rate of ibuprofen decreased when the apparent density and shape factor of the granules increased. In contrast, the dissolution rate of the drug increased with the friablility of the granules increased. Thus, the structures of the granules appear to affect the dissolution rate of the drug to a large degree. A rapid dissolution test that can be used to investigate the early dissolution rate of ibuprofen in vitro was proposed to evaluate the taste-masking level of the coated particles. The bitter taste-masking level of the coated particles was successfully confirmed by using this novel test method.     

A lattice Monte Carlo simulation of the FePt alloy using a first-principles renormalized four-body interaction

Although a lattice Monte Carlo method provides an effective, simple, and fast way to study thermodynamic properties of substitutional alloys, it cannot treat by itself the off-lattice effects, such as thermal vibrations and local distortions. Therefore, even if the interaction among atoms at lattice points is calculated accurately by means of first-principles calculations, the lattice Monte Carlo simulation overestimates the order-disorder phase transition temperature. In this paper, we treat this problem in the investigation of the FePt alloy, which has recently attracted considerable interest in its magnetic properties. We apply a simple version of the potential renormalization theory to determine the interaction among atoms, including partly the off-lattice effects by means of first-principles calculations. Then, we use the interaction to perform a lattice Monte Carlo simulation of the FePt alloy on a fcc lattice. From the results, we find that the transition temperature obtained after the present renormalization procedure becomes closer to the experimental value.     

Concise preparation of 2,2-difluorohomopropargyl carbonyl derivatives. Application to the synthesis of 4,4-difluoroisoquinolinone congeners

A scalable synthesis of 2,2-difluorohomopropargyl esters was achieved using a magnesium-promoted Barbier reaction of substituted difluoropropargyl bromides with alkyl chloroformates. These 2,2-difluorohomopropargyl esters were effective precursors in the synthesis of homopropargylic amides-by aminolysis using AlMe3, as well as of ketones-through the reaction of the corresponding Weinreb amides with Grignard reagents. Ring closing metathesis using difluorinated 1,7-enyne carbonyl compounds furnished six-membered diene products, which were used as susbstrates in a Diels-Alder reaction to afford 4,4-difluoroisoquinolin-3-ones. The [2 + 2 + 2] cycloaddition of alkynes with fluorinated 1,7-diyne amides gave 4,4-difluoro-1,4-dihydro-3(2H)-isoquinolinone derivatives regioselectively.     

Involvement of electron transfer in the photoreaction of zebrafish Cryptochrome-DASH

Photoreaction of a blue-light photoreceptor Cryptochrome-DASH (Cry-DASH), a new member of the Cryptochrome family, from zebrafish was studied by UV-visible absorption spectroscopy in aqueous solutions at 293 K. Zebrafish Cry-DASH binds two chromophores, a flavin adenine dinucleotide (FAD) and a N5,N10-methenyl-5,6,7,8-tetrahydrofolate (MTHF) noncovalently. The bound FAD exists in the oxidized form (FAD(ox)) in the dark. Blue light converts FAD(ox) to the neutral radical form (FADH*). Formed FADH* is transformed to the fully reduced form FADH(2) (or FADH(-)) by successive light irradiation, or reverts to FAD(ox). FADH(2) (or FADH(-)) reverts to FADH* or possibly to FAD(ox) directly. The effect of dithiothreitol suggests a possible electron transfer between FAD in zebrafish Cry-DASH and reductants in the external medium. This is the first report on the photoreaction pathway and kinetics of a vertebrate Cry-DASH family protein.     

Water-proton relaxivities of DNA oligomers carrying TEMPO radicals

5-Uridine derivative carrying a TEMPO radical (UST) was prepared and its single strand (ssUST) and a double strand (dsUST) with its complementary strand were obtained. Similarly, single strands carrying two and five radicals (ssUST2 and ssUST5, respectively) and the corresponding double strands (dsUST2 and dsUST5) were prepared. Their electron paramagnetic resonance (EPR) spectra showed typical anisotropic broadening in the high field line. The rotational correlation times, tau(R), estimated by analyzing the EPR spectra are 1.1 x 10(-10), 5.9 x 10(-10), and 14 x 10(-10) s for UST, ssUSTm, and dsUSTm, respectively. The water-proton relaxivities, r(1) and r(2), at 25 MHz, 0.59 T, and 25 degrees C, also increased in the same order and the r(1) values were 0.26, 0.41, and 0.56 mM(-1) s(-1) for UST, ssUSTm, and dsUSTm, respectively. The r(1) values of 1.00 and 2.06 mM(-1) s(-1) for dsUST2 and dsUST5, respectively, were obtained.     

Formation of monometallic single-molecule magnets with an Stotal value of 3/2 in diluted frozen solution

A combination of cobalt(II) complexes and pyridine ligands carrying organic spins, aminoxyl and carbene, provided single-molecule magnets with Stotal = 3/2 in diluted frozen solutions.