Synthesis of colloidal dispersions of rhodium nanoparticles under high temperatures and high pressures

Colloidal dispersions of rhodium (Rh) nanoparticles have been synthesized by the reduction of Rh ions (III) in high-temperature and high-pressure water, ethanol, or water-ethanol mixture under the existence of the protective polymer of poly(N-vinyl-2-pyrrolidone). The possibility of the regulation of the particle size and size distribution has been tested under several solvents at various temperatures and pressures. At 473 K and 25 MPa, particularly, concentrated colloidal dispersions of Rh particles of 2.5+/-0.5 nm were synthesized from the ionic solution of ethanol ([Rh]=15 mM) within a few seconds. Dilute colloidal dispersions of Rh particles were also synthesized from the dilute ionic solution ([Rh]=1.5 mM) with a diameter of 2.0+/-0.4 nm. From the water solution, Rh particles tended to form aggregates, especially for the lower concentration solution. In the case of solutions in water and ethanol mixture, the average diameter of Rh particles tended to be larger than in ethanol solution, and their distribution became broad.     

Quantitative structure-activity relationship study of N-(3-oxo-3,4-dihydro-2H-benzo[1,4]thiazine-6-carbonyl)guanidines as potent Na/H exchange inhibitors

We have previously reported that N-(4-isopropyl-2,2-dimethyl-3-oxo-3,4-dihydro-2H-benzo[1,4]oxazine-6-car bonyl)guanidine (4b) methanesulfonate salt (KB-R9032) is a potent and highly water-soluble Na/H exchange inhibitor. In a series of studies on Na/H exchange inhibitors, we designed and synthesized N-(3-oxo-3,4-dihydro-2H-benzo[1,4]thiazine-6-carbonyl)guanidines (5) as more potent inhibitors with high water-solubility. The design strategy for 5 was based on a quantitative structure-activity relationship (QSAR) study, involving the proportional relationship between the biological activity and hydrophobicity of the ring structure of compounds 4. As expected, compounds 5 showed more potent activity than 4. It was found by using the QSAR analysis that 5 were about five-fold more potent than 4. The increase in potency of compounds 5 well agreed with our previous QSAR analysis result. The most potent derivative was the methanesulfonate salt 5d of the 4-isopropyl derivative (IC50=0.0091 microM). And in addition to the in vitro study, 5d showed significant protective activity against a rat acute myocardial infraction model.     

Complex macromolecular dynamics:: I. Estimation technique for time-resolved emission anisotropy ratio of chromophores incorporated into polymer chains

Time-resolved fluorescence emission anisotropy ratios of carbazolyl groups incorporated into polystyrene chains in polyethyleneoxide(PEO)/1,2-dichloroethane mixtures have been measured by the single photon counting method. The fluorescence depolarization method is very excellent to clarify various dynamical modes of polymer chains, and many theoretical and experimental researches have so far been reported in the field of polymer chain dynamics. However there are few reports about the dynamics on the polymer side chain, because the dynamical mechanism of the polymer side chain is very complicated. In this report we tried to analyze the dynamical modes of the polymer side chains by the fluorescence depolarization method. Five dynamical modes of a polymer chain based on the Wöessner model were estimated by our original analytical technique `χ²-map method'. The value of each mode of a polymer side chain was discussed above the overlap concentration (C^*) of PEO and the micro-environments were clarified in the vicinity of the chromophore attached to the polymer side chain.     

Factors influencing serum concentration of zonisamide in epileptic patients.

The relationship between daily dose and serum concentration of zonisamide (ZNS) and the effects of patient age on the serum level/dose (L/D) ratio for ZNS were studied in epileptic patients (mean age +/- S.D. = 10.6 +/- 6.2 years) who chronically received ZNS. The influence of phenytoin (PHT), phenobarbital (PB), carbamazepine (CBZ) and valproic acid (VPA) on the serum protein binding of ZNS in vitro and the correlation between total and unbound serum levels of ZNS in patients were also examined. Significant correlations were obtained between daily dose per body weight or per body surface area and serum level of ZNS. The correlation coefficient of the latter was higher than that of the former. There was no effect of age on the L/D ratio on the basis of body surface area, whereas that on the basis of body weight increased significantly with age. No significant increase in the free fraction of ZNS was observed in the presence of PHT, PB and CBZ except VPA in vitro. There were significant correlations between total and unbound serum levels of ZNS in the two patient groups coadministered with and without VPA. Although the free fraction of ZNS in the former was significantly higher than that of the latter, the increase was small. These results suggest that dosage regimens on the basis of body surface area would be more accurate than those on a body weight basis and that there is little effect of other antiepileptics on the serum protein binding of ZNS.     

Facile assignment of sequence ions of a peptide labelled with 18O at the carboxyl terminus.

The combination of collision-induced dissociation (CID) and linked-scan analysis was used for analysing the sequence ions from the precursor ion of a peptide, which had been labelled with 18O at its carboxyl terminus (C-terminus) using 40 atom % H2 18O. The CID and linked-scan mass spectrum of the labelled peptide gave two series of sequence-ion signals: the one, originating from the C-terminus of the labelled peptide, showed a doublet signal due to the part-incorporation of 18O into the carboxyl group at the C-terminus, while the other, originating from the amino terminus (N-terminus), has the natural isotopic ion distribution. From the distribution of the isotopic ions in a single CID spectrum, the sequence ions containing the C-terminus could be readily differentiated from those containing the N-terminus, allowing the facile assignment of sequence ions to the amino-acid sequence of a peptide by CID and linked-scan analysis. This method was successfully applied to determination of the amino-acid sequence of the light-chain of mouse anti-porphyrin monoclonal antibody.     

New phase separator for extraction-spectrophotometric determination of anionic surfactants with Malachite Green by flow injection analysis

A simple flow injection spectrophotometric method for the determination of anionic surfactants in river water was studied. A three-channel flow system was assembled. The distilled water as a carrier and 5x10(-5) mol l(-1) Malachite Green (MG) dissolved in 0.1 mol l(-1) CH(3)COONa-CH(3)COOH buffer solution (pH 5) were delivered at 1.94 ml min(-1). The mixed solvent (toluene+methylisobutyl ketone (MIBK)=1+1) was pumped at 0.78 ml min(-1). Other conditions were the extraction coil 0.5 mm i.d.x3 m, the reaction temperature 20 degrees C and the sample size 200 mul. The calibration graph was linear in the range 0.1-0.4 ppm at 626 nm. The detection limit (S/N=3) was 18 ppb and a sample frequency of 20 h(-1) was attained. The relative standard deviation (n=7) for 0.4 ppm standard sodium dodecylsulfate (SDS) solutions was 1.1%. And also, new phase separator with a convenient connector was designed. This Fl method was applied to the determination of anionic surfactants in river water.     

Rate and equilibrium constants for the epimerization of the endothelin receptor antagonist J-104,132 in aqueous solution

The degradation of [5S-[5alpha,6beta,7alpha(R*)]]-2-butyl-5-(1,3-benzodioxol-5-yl)-7-[(2-carboxypropyl)-4-methoxyphenyl]-6-dihydro-5H-cyclopenta[b]pyridine-6-carboxylic acid (J-104,132) was studied in aqueous solution as a function of temperature and pH. The degradation reaction does not proceed to completion; rather, a stable equilibrium is attained in which approximately 2% of the degradate is produced. Kinetic data for the formation of the degradate are analyzed using an integrated form of the rate law for a reversible first-order reaction, and the forward and reverse rate constants and overall equilibrium constants are presented. Isolation and spectroscopic structural determination indicate that the degradate is the C7 beta-epimer of the drug. A mechanism for the epimerization reaction involving a novel enamine-like intermediate is proposed and shown to be consistent with the kinetic data. The rate and equilibrium constants are used to predict the room temperature stability of an injectable formulation of J-104,132, and these predictions are compared to actual data from long-term stability studies. It is concluded that the preformulation kinetic studies provide essential data needed for optimum drug product development.     

ULTRAVIOLET RESONANCE RAMAN STUDY ON PURPLE AND BLUE MEMBRANES OF Halobacterium halobium

Abstract— Two hundred and forty and 213 nm excited resonance Raman spectra of purple membrane (PM) and blue membrane (BM) of Halobacterium halobiurn were studied. Generally intense Trp scattering and a strong relative intensity of the W3 band at 1553 cm^-1 in the 240 nm spectrum of PM indicate red-shifted B_b absorptions of some Trp sidechains. A high intensity ratio of Trp doublet at 1360 and 1340 cm^-1 suggests interactions with highly hydrophobic Trp environments. These Trp are not strongly H-bonded and their N₁ sites are located in positions easily reached by solvent water molecules. Tyrosines are also in very hydrophobic environments and H-bonded. The mainchain consists of normal and distorted α-helices whose amide NH are hardly deuterated in D₂O suspension, and some NH exchangeable irregular segments on the membrane surface. Upon acidification, the ratio of Trp doublet with 240 nm excitation decreases concomitant with increase in retinal absorbance at 600 nm, and the W3 relative intensity and overall Trp scattering also decrease. These observations strongly indicate that the counterpart of Trp interactions in PM is the retinal and that the interactions partly diminish upon acidification. The Tyr environment also changes with the color. Although the 240 nm amide I intensity is greater in acid BM than in PM, the change is not related to the color change because the amide I intensity of deionized BM is practically the same as that of PM. The amide I intensity increase in acid BM is ascribable to a structural change of the surface peptides due to acid induced aggregation.     

Novel benzamides as selective and potent gastrokinetic agents. III. Synthesis and structure-activity relationships of 4-amino-5-chloro-2-methoxy- and 2-ethoxy-N-[(4-substituted 2-morpholinyl)methyl]-benzamides.

A series of 4-amino-5-chloro-2-methoxy- and 2-ethoxy-N-[(4-substituted 2-morpholinyl)methyl]benzamides (11-64) were prepared and evaluated for gastrokinetic activity by determining their effects on the gastric emptying of phenol red semisolid meal in rats. The N-4 substituent includes alkyl, phenoxyalkyl, (4-fluorobenzoyl)alkyl, and heteroarylmethyl groups. The benzamide derivatives, having an isopropyl, isoamyl, neopentyl, 3-(4-chlorophenoxy)-propyl, or pyridylmethyl group at N-4, showed potent in vivo gastric emptying activity. In particular, 4-amino-5-chloro-2-ethoxy-N-[[4-(3-pyridylmethyl)-2- morpholinyl]methyl]benzamide (57b) was equipotent to the 4-fluorobenzyl analogue 1b (AS-4370 as its citrate) in the gastrokinetic activity on phenol red semisolid meal in rats and mice, and on resin pellet solid meal in rats. Moreover, compound 57b was free from dopamine D2 receptor antagonistic activity in both in vitro ([3H]spiperone binding) and in vivo (apomorphine-induced emesis in dogs) tests. Structure-activity relationships of compounds with various substituents at N-4 are also discussed.     

Chiral supramolecular polymers formed by host-guest interactions

alpha-Cyclodextrin with a p-t-butoxyaminocinnamoylamino group in the 3-position (3-p-(t)()BocCiNH-alpha-CD) has been found to form a supramolecular polymer in an aqueous solution. The degree of polymerization of the supramolecular polymer is higher than 15 at 20 mM, as proved by VPO (vapor pressure osmometry) measurements and turbo ion spray TOF MS measurements. The existence of substitution/substitution interactions between adjacent monomers of the supramolecular polymer have been confirmed by the observation of positive and negative Cotton bands in circular dichroism spectra. The mechanism for the induction of the chirality was confirmed using model compounds. The substituents were found to exist as a left-handed anti configuration in supramolecular polymers. The supramolecular polymer was found to take a helical structure. The structure of the supramolecular polymer was observed by STM measurements.