Single-particle light scattering study of polyethyleneglycol-grafted poly(ureaurethane) microcapsule in ethanol

Microcapsules having polyethyleneglycol-grafted poly(ureaurethane) (PUU) membrane and di-2ethylhexyl phthalate core have been prepared, and the structure when they were suspended in dispersing ethanol have been studied by means of single-particle light scattering method. The PUU membrane was synthesized from monomers with aromatic functional groups (microcapsule MC110) and hexamethylene functional groups (microcapsule MC160). Because the outer and inner solvent passed through the membrane easily, the outside and inside of the membrane were the same at the equilibrium state. The thickness of the wall membrane was significantly smaller than that calculated from the overall weight ratio of the wall-forming material and the core solvents. It was attributed to low affinity of PUU membranes and ethanol.     

Nakiterpiosin and nakiterpiosinone, novel cytotoxic C-nor-D-homosteroids from the Okinawan sponge Terpios hoshinota

Two new cytotoxic compounds, nakiterpiosin (1) and nakiterpiosinone (2), were isolated from the Okinawan sponge Terpios hoshinota. Their structures were determined by spectroscopic analysis. The absolute stereostructure of 1 was also determined by a modified Mosher's method. Nakiterpiosin (1) and nakiterpiosinone (2) showed potent cytotoxicity against mouse lymphocytic leukemia cell (P388).     

Comparison in fractal dimension between those obtained from structure factor and viscoelasticity of gel networks of 1,3:2,4-bis-O-(p-methylbenzylidene)-D-sorbitol in polystyrene melt at gel point

We investigated time evolution of shear moduli in the physical gelation process of 1,3:2,4-bis-O-(p-methylbenzylidene)-D-sorbitol in polystyrene melt. At the gel point, storage and loss shear moduli, G' and G", were described by the power law of frequency omega, G' approximately G" approximately omegan, with the critical exponent n being nearly equal to 2/3, in agreement with the value predicted by the percolation theory. We also investigated the structure factor over two decades in length scale at gel point by using ultra-small-angle X-ray scattering, and small-angle X-ray scattering. We found the power-law behavior in low-q region, indicating that the gel network forms the self-similar structure with mass-fractal dimension. Comparison between the exponent of mass-fractal dimension from structure factor and that from viscoelasticity indicates that hydrodynamic interactions are completely screened out and the excluded volume effects are dominant in the gel. The gel strength was found to increase with the decrease in the lower limit length scale of fractality.     

Electronic properties of CrF and CrCl in the X 6Sigma+ state: observation of the halogen hyperfine structure by Fourier transform microwave spectroscopy

The rotational spectra of the CrF and CrCl radicals in the X 6Sigma+ state were observed by employing a Fourier transform microwave spectrometer. The CrF and CrCl radicals were generated by the reaction of laser-ablated Cr with F2 and Cl2, respectively, diluted in Ar. A chromium rod made of chromium powder pasted with epoxy resin was ablated by a Nd:YAG laser. Rotational transitions were measured in the region between 8 and 26 GHz. Several hyperfine constants due to the halogen nuclei were determined by a least-squares analysis. The electronic properties of CrF and CrCl were derived from their hyperfine constants and were compared with those of other 3d transition metal monohalides: TiF, MnF, FeF, CoF, NiF, and FeCl.     

Development of a novel analytical method for determination of chondroitin sulfate using an in-capillary enzyme reaction

A novel analytical method for determination of total amount of chondroitin sulfate (CS) based on its conversion to desulfated chondro-disaccharide via an enzyme-catalyzed reaction, was developed. Using the in-capillary enzyme reaction, the method was also applied to the successful construction of an on-line analytical system. Within this system, electrophoretic migration was used to mix zones containing the enzyme mixture (chondroitinase ABC, chondro-4-sulfatase, chondro-6-sulfatase and 2-o-sulfatase) and the substrate (CS). The reaction was then allowed to proceed in the presence of a weak electric field and, finally, the product (desulfated chondro-disaccharide) of enzyme reaction migrated to the detector under the influence of an applied electric field. A polyvinyl alcohol-coated capillary was used to reduce protein adsorption. Desulfated chondro-disaccharide was successfully migrated toward the anode in 10 mM Tris-acetate buffer (pH 7.0) under reversed polarity and detected at 232 nm. The established method was validated and demonstrated to be applicable in the determination of total amount of CS in a commercial ophthalmic solution. No interference from the formulation excipients was observed. Good linearity was obtained, with correlation coefficients above 0.999. Recoveries and precisions ranged from 100.0 to 100.5%, and from 0.2 to 0.6% of the relative standard deviation, respectively. Good agreement was obtained between the established method and traditional photometric method based on carbazole reaction. In this study, application of the method to disaccharide compositional analysis was also performed.     

In vivo quantification of the metabolites in normal brain and brain tumors by proton MR spectroscopy using water as an internal standard

Metabolite concentrations in normal adult brains and in gliomas were quantitatively analyzed by in vivo proton magnetic resonance spectroscopy (MRS) using the fully relaxed water signal as an internal standard. Between January 1998 and October 2001, 28 healthy volunteers and 18 patients with gliomas were examined by in vivo proton MRS. Single-voxel spectra were acquired using the point-resolved spectroscopic (PRESS) pulse sequence with a 1.5 T scanner (TR/TE/Ave = 3000 ms/30 ms/64). The calculated concentrations of N-acetyl-aspartate (NAA), creatine (Cre), choline (Cho), and water(H(2)O) in the normal hemispheric white matter were 23.59 +/- 2.62 mM (mean +/- SD), 13.06 +/- 1.8 mM, 4.28 +/- 0.8 mM, and 47280.96 +/- 5414.85 mM, respectively. The metabolite concentrations were not necessarily uniform in different parts of the brain. The concentrations of NAA and Cre decreased in all gliomas (p < 0.001). The NAA/Cho and NAA/H(2)O ratios can distinguish the normal brain from gliomas and low-grade from high-grade astrocytoma (p < 0.001). The concentration of taurine (Tau) in medulloblastomas was 29.64 +/- 5.76 mM. This is the first quantitative analysis of Tau in medulloblastoma in vivo and confirms earlier in vitro findings.     

In vivo quantification of the metabolites in normal brain and brain tumors by proton MR spectroscopy using water as an internal standard

Metabolite concentrations in normal adult brains and in gliomas were quantitatively analyzed by in vivo proton magnetic resonance spectroscopy (MRS) using the fully relaxed water signal as an internal standard. Between January 1998 and October 2001, 28 healthy volunteers and 18 patients with gliomas were examined by in vivo proton MRS. Single voxel spectra were acquired using the point-resolved spectroscopic pulse sequence with a 1.5-T scanner (TR/TE/Ave = 3000 ms/30 ms/64). The calculated concentrations of N-acetyl-aspartate (NAA), creatine (Cre), choline (Cho), and water (H2O) in the normal hemispheric white matter were 23.59 +/- 2.62 mM (mean +/- SD), 13.06 +/- 1.8 mM, 4.28 +/- 0.8 mM, and 47280.96 +/- 5414.85 mM, respectively. The metabolite concentrations were not necessarily uniform in different parts of the brain. The concentrations of NAA and Cre decreased in all gliomas (p < 0.001). The NAA/Cho and NAA/H2O ratios can distinguish the normal brain from gliomas, and low-grade astrocytoma from high-grade group (p < 0.001). The concentration of taurine (Tau) in medulloblastomas was 29.64 +/- 5.76 mM. This is the first quantitative analysis of Tau in medulloblastoma in vivo and confirms earlier in vitro findings.     

Direct observations of freeze-etching processes of ice-embedded biomembranes by atomic force microscopy

We have fabricated a cryogenic atomic force microscope that is designed for structural investigation of freeze-fractured biological specimens. The apparatus is operated in liquid nitrogen gas at atmospheric pressure. Freeze-fracturing, freeze-etching and subsequent imaging are carried out in the same chamber, so that the surface topography of a fractured plane is easily visualized without ice contamination. A controlled superficial sublimation of volatile molecules allows us to obtain three-dimensional views of ultrastructures of biological membranes.     

Measurement Accuracy in Phase-Shifting Point Diffraction Interferometer with Two Optical Fibers

A phase-shifting point diffraction interferometer (PS/PDI) with point sources of two single mode optical fibers has been developed, which will be appropriate for the surface figure measurement of large aperture optics on a sub-nanometer scale. To reduce the measurement error factors, a fiber optic plate (FOP) is used as a projection plane for interference pattern. Errors caused by imperfection of optical alignment, such as position of point sources and tilt of FOP, are minimized by analyzing the measured phase data with an original method. Measurement accuracy in the PS/ PDI is estimated with the interference pattern produced by the two optical fiber sources. If inhomogeneity of the FOP and a systematic error of the PS/PDI are eliminated, the measurement accuracy of the present system is estimated to be less than 4nm P-V and 0.7nm rms, respectively, at a measurement wavelength of 632.8 nm.