Role of bis(monoacylglycero)phosphate in propranolol binding to phospholipid membranes under acidic conditions as measured by high‐performance frontal analysis/capillary electrophoresis

Bis(monoacylglycero)phosphate (BMP) is localized in acidic organelles such as late endosomes or lysosomes. It has been reported that BMP levels increase under phospholipidosis induced by cationic amphiphilic drugs. In the present study, the effect of BMP on the binding of propranolol (PRO) to phospholipid liposomes under acidic conditions was investigated. Binding experiments were conducted by high‐performance frontal analysis/capillary electrophoresis. PRO showed nonspecific binding to BMP‐containing liposomes (BMP:phosphatidylcholine = 1:4), when numbers of bound drug molecules per lipid molecule (r) ranged 0.01–0.06. Total binding affinity increased depending on the BMP content. Binding affinity was decreased by low ionic strength, or by substitution of BMP with diacylglycerol, suggesting that electrostatic interactions were involved. The binding‐enhancement effect of BMP was almost equivalent to that of phosphatidylglycerol, and slightly larger than that of phosphatidylserine. An acidic environment (pH 5.0) decreased total binding affinity to BMP‐containing liposomes. This could be explained by the pH‐partition theory (i.e., the loss in affinity was caused by a decrease in the neutral form of the drug accessible to the membrane core). These results suggest that PRO binding is enhanced by BMP in late endosomes or lysosomes, whereas an acidic environment weakens such binding.     

Gadolinium-based hybrid nanoparticles as a positive MR contrast agent

A new nanoparticulate inorganic-organic hybrid-type positive contrast agent (CA), PGP/dextran-K01, was synthesized based on a GdPO4 inorganic core as a relaxation-time-shortening moiety and a dextran-coating, which generates monodispersibility in water, a high relaxation-time-shortening effect by retaining a large number of water molecules in proximity of the core and toxicity reduction in in-vivo studies. This PGP/dextran-K01 nanoparticle has high r1 and r2 values and a significantly low r2/r1 value, 1.1, which is unprecedented and which is the lowest value among existing nanoparticulate CAs indicating that PGP/dextran-K01 is a positive contrast agent. Because of this low r2/r1 value and the nanoparticulate shape, PGP/dextran-K01 will be a useful clinical substitute for negative CAs based on iron oxides.     

Spin dynamics of charge carriers in the process of their localization in α’-(BEDT-TTF)<Subscript>2</Subscript>IBr<Subscript>2</Subscript> single crystals

Sharp changes in the integral intensity and linewidth of the ESR spectrum that accompany the localization of the charge carriers have been revealed in α’-(BEDT-TTF)₂IBr₂ crystals. It has been found that the types of localization in two compounds under investigation are different: charge carriers in β″-(BEDT-TTF)₄NH₄[Cr(C₂O₄)₃] are localized on irregular defects of the crystal lattice, whereas charge carriers in α’-(BEDT-TTF)₂IBr₂ are localized at the regular positions of the unit cell. The exchange narrowing of the ESR line and a sharp decrease in the dc and ac magnetic susceptibilities are observed in α’-(BEDT-TTF)₂IBr₂ at low temperatures T < 50 K. The dc and ac magnetic susceptibilities observed in α’-(BEDT-TTF)₂IBr₂ at high temperatures T > 50 K differ from each other, because the thermally activated hopping frequency of the charge carriers is higher than the frequency of the measuring UHF field of an ESR spectrometer.     

Spin dynamics in oriented ferromagnetic nanowires Ge<Subscript>0.99</Subscript>Co<Subscript>0.01</Subscript>

The magnetic properties of one-dimensional oriented nanowires Ge_0.99Co_0.01 grown in pores of anodized aluminum oxide membranes are investigate using ferromagnetic resonance spectroscopy. The electron spin resonance signals of the magnetically ordered cobalt subsystem and the charge-carrier subsystem are identified. It is revealed that the anisotropy field at 4 K is equal to 400 Oe and aligned parallel to the nanowire axis. The transverse relaxation time of spin waves at 4 K is estimated to be ～10^?10 s. It is shown that the magnetic properties of nanowires are predominantly determined by the ferromagnetism of Co and GeCo alloy clusters.     

Theory of the Bose particle representation for geminals

An electron pair in a molecule is a complex entity and is incompletely described by the independent particle picture. Electron pairs are treated as Bose particles to include correlation of intrapair interaction effectively by the use of the Dyson transformation. The use of a Bose-type Hamiltonian permits a straight forward interpretation for geminals and facilitates the calculation of electronic energies. A Bose-type representation method is applied to the calculation of electronic energies of a lithium hydride molecule.     

Symmetry realization of texture zeros

We show that it is possible to enforce texture zeros in arbitrary entries of the fermion mass matrices by means of Abelian symmetries; in this way, many popular mass-matrix textures find a symmetry justification. We propose two alternative methods which allow one to place zeros in any number of elements of the mass matrices that one wants. They are applicable simultaneously in the quark and lepton sectors. They are also applicable in grand unified theories. The number of scalar fields required by our methods may be large; still, in many interesting cases this number can be reduced considerably. The larger the desired number of texture zeros is, the simpler are the models which reproduce the texture.Received: 7 May 2004, Published online: 7 July 2004     

Lipase-catalyzed domino kinetic resolution of alpha-hydroxynitrones/intramolecular 1,3-dipolar cycloaddition: a concise asymmetric total synthesis of (-)-rosmarinecine

The title domino reactions were developed to directly provide tetrahydrofuro[3,4-c]isoxazole derivatives (5 and 9) in > or =90% ee from racemic alpha-hydroxynitrones (2 and 6), which were used in the concise asymmetric total synthesis of (-)-rosmarinecine .     

Evidence for a transition state model compound of in-plane vinylic SN2 reaction

[reaction: see text] To isolate a transition state model compound of an in-plane vinylic S(N)2 reaction, vinyl bromide 6 bearing a newly synthesized tridentate ligand derived from 1,8-dimethoxythioxanthen-9-one (5) was prepared as a precursor. Although irradiation of 6 gave demethylated benzofuran 12, a transient broad peak which indicates formation of the desired transition state model compound was observed in the laser flash photolytic study.     

Kinetics of transformation of Eu<Superscript>2+</Superscript> dimers in NaCl crystals in a static magnetic field of 15 T

A static magnetic field of up to 15 T is found to affect the photoluminescence excitation spectra of NaCl: Eu crystals. The magnetic field has an effect on the excitation spectra starting at the stage at which dimers are formed through diffusion in the crystals. At earlier stages of impurity aggregation, the magnetic field affects the kinetics of dimer accumulation. It is revealed that the dimer transformation stimulated by the magnetic field involves stages that last for 10–15 min at room temperature in a static magnetic field of 15 T and, hence, are shorter than the aggregation time. Luminescence studies of dimers, which are the main dislocation stoppers in NaCl: Eu crystals, make it possible to explain the specific features of the magnetoplastic effect observed previously in these crystals.