Characterization and determination of linear alkylbenzenesulfonates in environmental water samples by high-performance liquid chromatography with a hydrophilic polymer column and electrospray ionization mass spectrometric detection.

A liquid chromatography-mass spectrometry (LC/MS) method was developed for the separation and determination of linear alkylbenzenesulfonates (C10-C14 LAS) in environmental water samples using a hydrophilic polymer column (Shodex Mspak GF-310 4D). This method involves a solid-phase extraction of the LAS samples with a Sep-Pak PS-2 cartridge. The LAS components were separated on the column with a mobile phase of 29% (w/v) acetonitrile-water containing 0.8 mM di-n-butylammonium acetate and 0.2 M acetic acid, and were detected by mass spectrometry with electrospray ionization. Detection limits of the developed method based on selected ion monitoring (SIM) technique for the C10-C14 LAS standards were 13-47 ng L(-1). The concentrations of the C10-C14 LAS in the environmental water samples ranged between 5-317 microg L(-1) for a river water sample and 0.4-6.4 microg L(-1) for a seawater sample. Linear relationships between the logarithms of retention factors and the alkyl chain lengths for each phenyl positional isomer of LAS could successfully be used for the identification of the isomer peaks.     

PHOTORECEPTOR CELL TYPES IN THE RETINA OF VARIOUS VERTEBRATE SPECIES: IMMUNOCYTOCHEMISTRY WITH ANTIBODIES AGAINST RHODOPSIN AND IODOPSIN

Types of photoreceptor cells in the retinas of 36 species of vertebrates (5 classes, 14 orders) were investigated immunocytochemically with monoclonal antibodies against chicken iodopsin (Io-mAb) and antiserum against bovine rhodopsin (Rh-As). In mammals, Rh-As labeled the outer segments of some photoreceptor cells in striped squirrels (a diurnal mammal) and those of most photoreceptor cells in mice (a nocturnal mammal), while Io-mAb labeled any photoreceptor cells in either of them. In all species of birds studied, Io-mAb labeled the principal and accessory members of double cones and single cones with a red oil droplet. Rh-As labeled single cones with a yellow or clear oil droplet in addition to rods. In turtles, both Rh-As and Io-mAb labeled single cones with a red or clear oil droplet and the principal (with a yellow oil droplet) and accessory members of double cones. This suggests that the visual pigments in these cones of turtles have common epitopes with bovine rhodopsin and chicken iodopsin. In Japanese grass lizards, single cones with a yellow oil droplet and double cones were immunoreactive to both Rh-As and Io-mAb. In snakes, rods and cones could not be distinguished but both positively and negatively stained cells were observed by the use of each antibody. In geckos, however, all photoreceptor cells were immunonegative to Io-mAb. In all species studied in amphibians, Rh-As labeled rods but not cones. Neither rods nor cones reacted with Io-mAb. In fishes, almost all species studied had well developed cones, and some of these cones were labeled by Rh-As. However, Io-mAb labeled the outer segments of some cones only in loaches. Rh-As labeled photoreceptor cells in all species of fishes studied. Thus, Rh-As recognized the outer segments of rods in all species studied from fishes to mammals, whereas the epitope recognized by Io-mAb is conserved in some species of fishes, most species of reptiles and all species of birds studied.     

Determination of hexabromocyclododecane diastereoisomers and tetrabromobisphenol A in water and sediment by liquid chromatography/mass spectrometry.

A method to determine alpha-, beta- and gamma-hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) in water and sediments was presented using solid phase extraction (SPE) and/or solvent extraction. Recoveries from sediments were approximately 100% for all the chemicals, while recoveries of alpha-, beta- and gamma-HBCDs from water were dependent on the extraction method. In the case of dichloromethane (CH2Cl2) extraction, recoveries of alpha-, beta- and gamma-HBCD from landfill leachates were 77%, 88% and 92%, respectively. Technical difficulties in HBCD measurement are discussed in terms of the physico-chemical properties of HBCD isomers. The method was applied to landfill samples and marine sediment.     

Efficient synthesis of CCR5 antagonist, 2,3-dihydro-1-benzothiepine derivatives by improved intramolecular Claisen type reaction using dialkylcarbonate

The efficient synthesis of 2,3-dihydro-1-benzothiepine derivatives 4 has been developed. The intramolecular Claisen type reaction of the new products, 4-(o-formylphenylthio)butyrate 9, with alcoholate in dialkylcarbonate as a solvent afforded 4 in good yields. According to this new procedure, we have accomplished the practical preparation of CCR5 antagonist 1 as a candidate for oral HIV-1 therapy.     

Hundredfold productivity of genome analysis by introduction of microtemperature-gradient gel electrophoresis

Genome profiling, which employs temperature-gradient gel electrophoresis (TGGE) for DNA analysis, has recently been developed in identifying species by genotype. However, the performance of this technology like the general applications of TGGE was, though highly informative, limited in its ability due to methodological reasons. This study demonstrates that minimization of the gel for TGGE, to around one-tenth of its conventional size (approximately 2 cm), can be successfully introduced, resulting in a hundredfold higher performance (total evaluation of time, cost, and degree of parallel operations) than that of the conventional. Reproducibility was evaluated from the measures of the pattern similarity scores (PaSS) between band patterns (genome profiles) obtained with the conventional TGGE, and that with micro-TGGE (microTGGE) developed here, after extracting a set of featuring points from genome profiles. Size minimization, which leads to the reduction of the amount of samples required (cost-saving), is another great advantage, enhancing the employment of multicolor fluorescence technology. Since the further development of microbe-related fields such as epidemiology and microbial ecology inevitably require knowledge based on the identification of a great number of species and strains, microbe-related fields will receive the most optimal benefits from the technological improvements attained here.     

Study on the structures of 2-substituted iminothiazolidine derivatives

The reaction of 2-bromoethylamine 1 with methylisothiocyanate 2 under mild condition gave 2-methyl-amino-2-thiazoline 3 as the major product together with two kinds of byproducts, 3-(N-methylthiocar-bamoyl)-2-methyliminothiazolidine 4 and N,N′-dimethyl-N-(2-thiazolin-2-yl)thiourea 5. Thermal isomer-ization of 5 to 4 was observed. The structures of the byproducts were confirmed by X-ray crystallography.     

Synthesis of 21-nor-22-oxa-1α,25-dihydroxyvitamin D3 derivatives in quest of a drug with low calcemic activity

Two 21-nor-22-oxa-1α,25-dihydroxyvitamin D₃ derivatives have been synthesized in quest of a drug with lower calcemic activity than Maxacalcitol, 22-oxa-1α,25-dihydroxyvitamin D₃, being used as antihyperparathyroidism and antipsoriatic drug. Of two 21-nor products obtained, the product carrying one carbon elongated side chain with diethylcarbinol moiety has been found to exhibit comparable differentiation-inducing activity to Maxacalcitol with much lower exhibition of calcemic activity.     

Novel syntheses of 2,3-dihydro-5H-1,4-benzoxathiepins and 1,2,3,5-tetrahydro-4,1-benzothiazepines

2,3-Dihydro-5H-1,4-benzoxathiepins were prepared by intramolecular Friedel-Crafts reactions of ethyl α-[2-(aryloxy)ethylthio]-α-chloroacetates or by acid-catalyzed cyclizations of ethyl α-[2-(aryloxy)ethylsulfinyl]-acetate. 1,2,3,5-Tetrahydro-4,1-benzothiazepines were similarly prepared.     

The O(N) vector model in the large-N limit revisited: multicritical points and double scaling limit

The multicritical points of the O(N)-invariant N vector model in the large-N limit are re-examined. Of particular interest are the subtleties involved in the stability of the phase structure at critical dimensions. In the limit N → ∞ while the coupling g → g_c in a correlated manner (the double scaling limit) a massless bound state O(N) singlet is formed and powers of 1/N are compensated by IR singularities. The persistence of the N → ∞ results beyond the leading order is then studied with particular interest in the possible existence of a phase with propagating small mass vector fields and a massless singlet bound state. We point out that under certain conditions the double scaled theory of the singlet field is non-interacting in critical dimensions.