Effects of phosphatidylserine and phosphatidylethanolamine content on partitioning of triflupromazine and chlorpromazine between phosphatidylcholine-aminophospholipid bilayer vesicles and water studied by second-derivative spectrophotometry

To assess the affinity of psychotropic phenothiazine drugs, triflupromazine (TFZ) and chlorpromazine (CPZ), for the membranes of central nervous system and the other organs in the body, the partition coefficients (Kps) of these drugs to phosphatidylcholine (PC)-phosphatidylserine (PS) and PC-phosphatidylethanolamine (PE) small and large unilamellar vesicles (SUV, LUV) were examined by a second-derivative spectrophotometric method, since PS is abundantly contained in the membranes of the central nervous system and PE is distributed widely in the membranes of the organs in the body. Size and preparation methods of the vesicles did not affect the Kp values at each aminophospholipid content suggesting that the partition of the phenothiazine drugs was not affected by the structural differences in the vesicles such as their curvature or asymmetric distribution of the phospholipids between the outer and inner layers of the bilayer membranes. However, the Kp values of both drugs increased remarkably according to the PS content in the bilayer membranes, i.e., the Kp values for the vesicles of 30 mol% PS content were about 3 times of that for the vesicles of PC alone, while both Kp values slightly reduced with the increase in the content of PE in the bilayer membranes of PC-PE vesicles. The results indicate that both drugs have higher affinity for the PC-PS bilayer membranes than for the PC and PC-PE membranes, which can offer an evidence for the fact that TFZ and CPZ are predominantly distributed and accumulated in the brain and nerve cell membranes that contain PS abundantly.     

Mössbauer spectroscopic study of γ-ray irradiated potassium borate glasses

Potassium borate glasses denoted by the formula xK₂O · (100 ? x)B₂O₃ · 7Fe₂O₃ were irradiated with ⁶⁰Co-γ-rays at room temperature. Mössbauer parameters for the irradiated glasses containing alkali equal to or higher than 20 mole% showed that the s-electron density at the iron nucleus increased without any change of the steric configuration of oxygen atoms around the iron nucleus. The increase of s-electron density was ascribed to electron transfer from the nonbridging oxygen to the iron nucleus. The presence of the nonbridging oxygen was also confirmed by the irradiation effect of the borate glass (x = 30) prepared using the enriched isotope of ⁵⁷Fe₂O₃. Mössbauer parameters for the irradiated glass suggest that the newly observed Fe²⁺ ions are in tetrahedral symmetry.     

Determination of99Tc in coastal seawater collected in Fukuoka,Japan

Concentrations of⁹⁹Tc were determined by inductively coupled plasma mass spectrometry (ICP-MS) on coastal seawater in the general environment in Japan. Technetium was enriched on iron hydroxide by repetitive co-precipitation method from a large volume of seawater and separated from impurities by solvent extraction and ion-exchange techniques. The concentrations of⁹⁹Tc were 1.0 to 7.4 Bq1^–1, which was one order of magnitude lower than the level reported on seawater from general environment by beta-ray counting. Concentrations of¹³⁷Cs determined on the same seawater were 3.7 and 3.9 mBq1^–1. The activity ratio of⁹⁹Tc/¹³⁷Cs was calculated to be 2.7×10^–4. This ratio was very close to the value expected for fallout from nuclear tests.     

HYDROGEN PEROXIDE MEDIATES UV-INDUCED IMPAIRMENT OF ANTIGEN PRESENTATION IN A MURINE EPIDERMAL-DERIVED DENDRITIC CELL LINE

Abstract— Ultraviolet-B (290–320 nm) radiation is known to impair the antigen-presenting cell (APC) function of Langerhans cells (LC), skin-specific members of the dendritic cell (DC) family. We sought to address mechanisms of this effect, focusing on the role played by hydrogen peroxide. For this purpose, we used a newly established murine DC line, XS52, which resembles epidermal LC in several respects. The APC capacity of XS52 cells, using two different CD4* T cell clones as responders, was inhibited significantly (>50%) by exposure to UV radiation (unfiltered FS20 sunlamps) at relatively small fluences (50–100 J/m²). Ultraviolet radiation also inhibited growth factor-dependent proliferation of XS52 cells. On the other hand, cell surface phenotype was relatively well preserved after irradiation; expression levels of B7-1 and B7-2 were reduced slightly, while other molecules ( e.g. Ia, CD54, CD1 la and CD18) were not affected. With respect to the role played by hydrogen peroxide, pretreatment with purified catalase (900 U/mL) prevented UV-induced inhibition of APC function. Short-term exposure to 3 miM H₂0₂ or f-butyl H₂0₂ mimicked UV radiation by inhibiting APC function. Finally, intrinsic catalase activity was substantially lower in XS52 cells compared with Pam 212 keratinocytes. These results indicate that the generation of hydrogen peroxide alone is sufficient to produce some, but not all, of the deleterious effects of UV radiation on DC derived from the skin.     

Preparation of manganese-53

The nuclide⁵³Mn was produced by the following three nuclear reactions,⁵²Cr(d, n)⁵³Mn,⁵¹V(³He n)⁵³Mn and⁵⁰Cr(α, n), (α, p)⁵³Mn. Enriched⁵²Cr and⁵⁰Cr metal targets were prepared on copper plate holder by electrodeposition. The commercially available natural vanadium foil was used for the⁵¹V(³He, n)⁵³Mn reaction. Each target was bombarded in a cyclotron. Manganese was extracted and purified without using carrier from the bombarded targets by anion and cation exchanges and solvent extraction. The isotopic ratio⁵³Mn/⁵⁵Mn was measured by mass spectrometry and the amount of⁵⁵Mn was determined by neutron activation analysis. The activity of⁵³Mn obtained was 7 dpm by 750 millicoulombs in³He bombardment (E³He=20 MeV). The activity due to by-product⁵⁴Mn was about several thousands times higher than that of⁵³Mn in³He and deuteron bombardments, which were produced through⁵¹V(³He, γ)⁵⁴Mn and⁵³Cr(d, n)⁵⁴Mn. In alpha bombardment (E_α=15 MeV), the activity of⁵³Mn produced was 8 dpm by 95 millicoulombs. The activity ratio, dpm⁵⁴Mn/dpm⁵³Mn, was about 3, and this ratio was the best one among the results so far obtained.     

Redox-responsive supramolecular polymeric networks having double-threaded inclusion complexes

Stimuli-responsive hydrogels have attracted attention as soft actuators that act similarly to muscles. In this work, hydrogel actuators controlled by host–guest interactions have been developed. The introduction of a 1:1 inclusion complex into a hydrogel is a popular design for achieving a change in cross-linking density. To realize faster and larger deformation properties, the introduction of a 1:2 inclusion complex is effective because the alteration in cross-linking density in a hydrogel with 1:2 complexes is larger than that in a hydrogel with 1:1 complexes. A redox-responsive hydrogel actuator cross-linked with 1:2 inclusion complexes is designed, where γ-cyclodextrin (γCD) and viologens modified with an alkyl chain derivative (VC11) were employed as the host and guest units, respectively. γCD includes two VC11 molecules in its cavity. The obtained γCD–VC11 hydrogel cross-linked with the 1:2 complex showed faster and larger deformation behaviour than the αCD–VC11 and the βCD–VC11 hydrogels cross-linked with a 1:1 complex. The deformation ratio and response speed of the γCD–VC11 hydrogel, which forms a supramolecular cross-linking structure by stimuli, are 3 and 11 times larger, respectively, than those of our previous hydrogel consisting of a βCD/ferrocene 1:1 inclusion complex.

A hydrogel actuator with a 1:2 host–guest complex controlled by redox stimuli has been developed to realize faster and larger deformation.     

Mössbauer spectroscopic study of gamma-ray irradiated potassium phosphate glasses

A Mössbauer spectroscopic study was performed to investigate the effect of γ-ray irradiation on the formation of non-bridging oxygens in the potassium phosphate glasses denoted by the formula x K₂O · (100 ? x)P₂O₅ · 7 Fe₂O₃ (0 ? x ? 50 mol.%). Mössbauer spectra for these glass samples consisted of two kinds of doublets due to Fe²⁺ and Fe³⁺ ions of octahedral symmetries. Only small changes occurred in the Mössbauer parameters as a result of irradiation at room temperature in a dry nitrogen atmosphere, except for the decrease in the absorption area for the Fe²⁺ ions. The decrease in the absorption area was attributed to the electron transfer from the Fe²⁺ ions to the neighboring oxygens. Thermal annealing experiments for a few non-irradiated glass samples indicated that the decrease in the absorption area was confirmed to be due to γ-rays rather than heating during the irradiation.     

Kinetic and mechanistic aspects for the tartaric acid oxidation by vanadium(V) in sulfuric acid medium

Tartaric acid oxidation by vanadium(V) in sulfuric acid medium was investigated spectrophotometrically at 760 nm and 30°C by appearance of the vanadium(IV), as vanadyl. The reaction rate was determined under pseudo-first-order conditions with an excess of hydroxyacid over the oxidant concentration. The oxidation showed a first-order dependence with respect to vanadium(V) concentration and fractional orders with respect to tartaric acid and sulfuric acid concentrations, with no control and with constant ionic strength. The reaction rate is enhanced by an increase of ionic strength, and slightly reduced by a decrease of the dielectric constant of the medium. The activation parameters were calculated based on the rate constants determined in the 293 to 313 K interval. The proposed oxidation mechanisms and the derived rate laws are consistent with the experimental rate laws. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 55–61, 1998.     

Determination of stable lead isotope ratios in environmental samples: Combination of microwave digestion and ICP-MS

Microwave digestion was applied as pretreatment of environmental samples for the determination of lead isotope ratios by ICP-MS. Microwave digestion decomposed the samples easily and rapidly without lead contamination. The lead isotope ratios could be measured directly by ICP-MS without tedious lead purification, because the influence of the matrix elements on measurements of lead isotope ratios is small enough to be ignored.