Shigenobu Watanabe

The acute toxicity of arsenobetaine

The acute toxicity of arsenobetaine was studied in male mice. No deaths were observed with oral administration of 10 g/kg of arsenobetaine. Therefore the LD50 value was higher than 10 g/kg. This compound was found in urine in the non-metabolized form. No particular toxic symptoms were observed following administration. These results suggest that arsenobetaine has low toxicity and is not metabolized in mice.

The study of organoarsenic compounds in fish and alga by exact mass measurement using fast atom bombardment mass spectrometry

Abstract The major water-soluble organoarsenic compounds isolated from blue pointer Isurus oxyrhincus , whitetip shark Carcharhinus longimanus and brown alga Hizikia fusiforme were examined by exact mass measurements using fast atom bombardment mass spectrometry (FAB/MS) along with amino acids as the reference standards. The major water-soluble organoarsenic compounds in I. oxyrhincus and C. longimanus were identified as arsenobetaine, and the major organoarsenic compound in H. fusiforme was considered to be a new water soluble organoarsenic compound inferring from the molecular weight and elemental composition.

Effects of free fatty acids on the binding of steroid hormones to bovine serum albumin

The effects of binding of free fatty acids (FFA) to bovine serum albumin (BSA) on steroid hormone binding to BSA were examined. The FFA studied included myristic, palmitic, stearic, oleic and linoleic acids. The binding coefficient K was estimated from the changes in the equilibrium partition coefficient between the aqueous and the hexane phase caused by the addition to BSA to the aqueous phase. A noticeable effect of FFA binding (molar ratio FFA/BSA, 2∶1) on the affinities of α-estradiol, ethynylestradiol and dehydroisoandrosterone to BSA was not observed: however, the affinities of progesterone, androsterone and testosterone were distinctly enhanced by FFA binding. Furthermore, the elution profiles of gel filtration chromatography clearly showed that progesterone and testosterone are easily liberated from the hormone/BSA complexes and that stronger binding of these hormones to BSA is caused by binding of FFA to BSA. The affinity of ethynylestradiol to BSA is stronger than that of progesterone and testosterone and is not affected by palmitic acid binding to BSA.

Transport of steroid hormones facilitated by serum proteins

The affinities with steroid hormones (alpha-estradiol, ethynylestradiol, progesterone, androsterone, dehydroisoandrosterone and testosterone) were observed for Cohns fraction IV-1 and V (albumin). It was estimated from the comparison with the binding coefficient K (protein-bound form/free form of hormone) in a 3.5% (w/v) bovine serum albumin (BSA) solution that 40-80% of bound hormone in bovine serum is the BSA-bound form. It becomes clear in a liquid membrane system consisting of a hexane source phase (I), a water phase and a hexane receiving phase (II) that the transport flux of hormone is governed primarily by the partition coefficients between the water/hexane phases. In the case of a hormone with a lower partition coefficient, the uptake process from the hexane phase (I) to the water phase is a rate-determining step in the transport system and the serum proteins accelerate the transport of hormones, while with an increase in the partition coefficient the rate-determining step changes from the uptake step to the release step from the water phase to the hexane phase (II) and the hormone transport is decelerated owing to the significant decrease of free hormone concentration in the aqueous phase by the associated with serum proteins for the system having the restricted amount of hormone in the hexane source phase.

Effect of gramicidin on the ion permeability of liposomes in the presence of mixed electrolytes

Abstract The membrane permeabilities of three anionic species (Cl - , Br - and NO 3 - ) and a cation (K + or Na + ) entrapped simultaneously within reverse-phase evaporation vesicles (REV) were measured with an ion chromatograph and an atomic absorption spectrophotometer. Anion and cation permeabilities of vesicle membranes conform to first-order kinetics. K + or Na + was scarcely detectable in the liposomes after removing the extravesicular electrolytes by means of a Sephadex column when gramicidin was added at a concentration exceeding 2 dimers of gramicidin per vesicle in the liposomal preparation, whereas the concentration of entrapped anions decreased by approximately first-order kinetics. When gramicidin was added to the liposome solution at an estimated level of 20 dimers per vesicle, only 30-40% of the entrapped K + or Na + permeated rapidly out of the vesicles. Measurement with a potassium ion electrode revealed that rapid release of K + occurs within five minutes after the addition of gramicidin. The K + efflux is partly compensated by H + influx. The membrane permeabilities of entrapped Cl - , Br - and NO 3 - were enhanced 2-3 times compared with those for liposomes without gramicidin.

Chemiluminescence detection of organotin compounds with bis(2,4,6-trichlorophenyl) oxalate by flow-injection analysis

Abstract The chemiluminescence (CL) reaction of bis(2,4,6-trichlorophenyl) oxalate with hydrogen peroxide was applied to the detection of fluorescent organotin-quinoline complexes using a flow-injection system. Four organotin compounds, i.e., di- n -butylin dichloride (DBTC), diphenyltin dichloride (DPTC), tri- n -butylin chloride (TBTC) and triphenyltin chloride (TPTC), were examined in conjunction with 2-methyl-8-hydroxyquinoline. Factors affecting the CL intensity such as solvents, reagent concentrations, pH and flow-rate were studied. The detection limits for DBTC, DPTC, TBTC and TPTC were 0.5 μM (3 ng), 1.25 μM (8.6 ng), 25 μM (162.7 ng) and 100 μM (770.9 ng), respectively, with a signal-to-noise ratio of 3.

Fluorescent substances derived from the reaction of 13-monohydroperoxylinoleic acid and methylamine.

Reaction of 13-monohydroperoxy linoleic acid and methylamine in the presence of ferric ions produced at least four fluorescent substances. They were separated by high performance liquid chromatography with a reverse phase column, and major fluorescent substances 1 and 3 were isolated. Fluorescent substances 1 and 3 showed the same fluorescence spectra with excitation maxima at 360 nm and emission maxima at 430 nm, and the same ultraviolet spectra with absorption maxima at 275 and 360 nm. Fluorescence of 1 and 3 was lost in alkaline media owing to the instability of the fluorophores. The fluorophores of 1 and 3 were destroyed on treatment with borohydride. The fluorescence characteristics of 1 and 3 were similar to those of the age-related fluorescent substances produced in tissues. They were different from those of the fluorescent substances derived from malonaldehyde and resembled those of the fluorescent substances derived from monofunctional aldehydes.

Determination of Polybrominated Biphenyls in Foods and Plastics

In USA, contamination of PBBs, which are used to increase the heat stability of plastics were reported. Following the incident, maximum allowable limits of PBBs for meat, milk fat, eggs and feed were set by FDA in 1974.From those, an analytical method concerning PBBs contaminations of food and plastics, was discussed. It was cleared that the determination for PCBs was successfully adapted for PBBs analysis, then contamination of fishes, dairy products and plastics were investigated. All samples were found to be free from PBBs contaminations.

Hygienic Study on Packaging or Vessel Made of Synthetic Resin (I)

The soluble components migrated from urea resin tablewares which had been used by children for long period have been studied.In this paper, the authors recognized that formaldehyde dissolved continuously and the concentration varied each time to use. And the formaldehyde translated to the solution from the resin, not only as free form but also as combined form from the surface of tableware with gradual degradation.Furthermore the appearances of the tablewares were observed by scanning electron micrographs and also they were compared with the amount of migrated formaldehyde. The results examined are as follow.1) The average amount of formaldehyde migrated from one tableware was 684μg from urea resin and 57μg from melamine resin.2) The amount of formaldehyde increased after irradiation with sterilizing light.3) Ammonia, urea and urea-formaldehyde compounds were found in the solution by liquid chromatography method.4) The urea-formaldehyde compounds run on T. L. C. were identified as monomethylolurea and dimethylolurea.5) Free formaldehyde and low molecular compounds in resin were evaporated by heating at 100°C for 3 hrs.6) The amount of soluble components were found to be correlated with the surface condition of tablewares.