A potent and highly selective sulfotransferase inhibitor

In the present work, we have used a newly developed, fluorescence-based assay to screen a library of >30 000 compounds as potential beta-arylsulfotransferase-IV inhibitors. A total of 11 inhibitors were discovered. Most of the compounds discovered showed low micromolar inhibition, but one of the compounds showed potent inhibition (Ki = 96 nM). The most potent of these inhibitors was tested against a variety of other purine binding enzymes and showed remarkable specificity.     

DNA recognition interfaces: the influence of interfacial design on the efficiency and kinetics of hybridization

The effect of the surface chemistry of DNA recognition interfaces on DNA hybridization at a gold surface was investigated using both electrochemistry and the quartz crystal microbalance (QCM) technique. Different DNA recognition interfaces were prepared using a two-component self-assembled monolayer consisting of thiolated 20-mer probe single-stranded DNA (ss-DNA) containing either a 3'-mercaptopropyl or a 3'-mercaptohexyl linker group and an alcohol-terminated diluent layer with 2-, 6-, or 11-carbon length. The influence of the interfacial design on the hybridization efficiency, the affinity constant (Ka) describing hybridization, and the kinetics of hybridization was assessed. It was found that the further the DNA was above the surface defined by the diluent layer the higher the hybridization efficiency and Ka. The kinetics of DNA hybridization was assessed using both a QCM and an electrochemical approach to ascertain the influence of the interface on both the initial binding of target DNA to the surface and the formation of a complete duplex. These measurements showed that the length of the diluent layer has a large impact on the time taken to form a perfect duplex but no impact on the initial recognition of the target DNA by the immobilized probe DNA.     

Behavior of plutonium isotopes in the marine environment of Enewetak atoll

There continue to be reports in the literature that suggest a difference in the behavior of^239+240Pu and²³⁸Pu in some aquatic environments. Plutonium isotopes have been measured in marine samples collected over 3 decades from Enewetak atoll, one of the sites in the Marshall Islands used by the United States between 1946 and 1958 to test nuclear devices. The plutonium isotopes originated from a variety of complex sources and could possibly coexist in this environment as different physical-chemical species. However results indicate little difference in the mobility and biological availability of^239+240Pu and²³⁸Pu.     

ANALYSIS OF MICROSECOND FLUORESCENCE YIELD AND DELAYED LIGHT EMISSION CHANGES AFTER A SINGLE FLASH IN PEA CHLOROPLASTS: EFFECTS OF MONO- AND DIVALENT CATIONS

Abstract. New results are presented on the effects of mono- and divalent cations on concurrent changes in the microsecond yields and kinetics of chlorophyll a fluorescence and delayed light emission, and the light saturation curve for the latter at 100 μs, following a 10 ns flash at 337 nm. (1) The fluorescence yield increases exponentially from 3 to 30 μs (lifetime, τ, 6.4 ± 0.6/μs), and decays biphasically between 50 and 800μs. (2) The delayed light emission decays biphasically with two exponential phases: fast phase, T= 7–10μs, and slow phase, T= 33–40μs. (3) The light saturation curve for 100μs delayed light emission is satisfactorily represented by a one-hit Poisson saturation curve. (4) Addition of 5 mM NaCl to salt-depleted chloroplasts decreases (by as much as 40%) the yields of μs fluorescence and delayed light emission, and the subsequent addition of 5mM MgCl₂ increases the yields (≤2 × over samples with only NaCl). (5) The fluorescence yield rise and delayed light emission decay kinetics are independent of low concentrations of cations. The lifetime of the fast phase of fluorescence decay changes from ?90μs to ?160μs, when Na⁺ or Na⁺+ Mg²⁺ are added. Based on a detailed analysis presented in this paper, the following conclusions regarding the effects of low concentrations (few mM) of mono-and divalent cations in sucrose-washed chloroplasts at room temperature are made: (a) Na⁺ decreases (?6%) and Mg²⁺ increases (? 20% compared with the Na⁺ sample) the sensitization of photosystem II photochemistry: this effect is small, but significant. (b) Na⁺ increases and Mg²⁺ decreases the efficiency for radiationless transitions in singlet excited Chl a in the antenna and closed reaction center of PS II; this includes non-radiative energy transfer to PS I, intramolecular intersystem crossing and internal conversion. The ratio of the sum of the rate constants for radiationless transitions to that for fluorescence increases by ? 2-fold upon the addition of Na⁺, and is completely reversed by the addition of Mg²⁺. (c) The rate constant for the re-oxidation of Q^- decreases (about 50%) in the presence of Na⁺ or Na⁺+ Mg²⁺. These conclusions imply that cations produce multiple changes in the primary photoprocesses of PS II at physiological temperatures. It is proposed that these changes are mutually independent and can co-exist.     

Enumeration of total yeasts and molds in foods by the SimPlate Yeast and Mold-Color Indicator method and conventional culture methods: collaborative study

The relative effectiveness of the SimPlate Yeast and Mold-Color Indicator method (Y&M-CI) was compared to the U.S. Food and Drug Administration's (FDA) Bacteriological Analytical Manual (BAM) method and the proposed International Organization for Standardization (ISO) method, ISO/CD 21527, for enumerating yeasts and molds in foods. Test portions were prepared and incubated according to the conditions stated in both the BAM and ISO methods. Six food types were analyzed: frozen corn dogs, nut meats, frozen fruits, cake mix, cereal, and fresh cheese. Nut meats, frozen fruits, and fresh cheese were naturally contaminated. All other foods were artificially contaminated with either a yeast or mold. Seventeen laboratories throughout North America and Europe participated in the study. Three method comparisons were conducted. In general, there was <0.3 mean log count difference in recovery between the SimPlate method and the 2 corresponding reference methods. Moreover, mean log counts between the 2 reference methods were also very similar. The repeatability (Sr) and reproducibility (SR) standard deviations were comparable between the 3 method comparisons. These results indicate that the BAM method and the SimPlate method are equivalent for enumerating yeast and mold populations in foods. Similarly, the SimPlate method is comparable to the proposed ISO method when test portions are prepared and incubated as defined in the proposed ISO method.     

Aromatic polyethers,polysulfones, and polyketones as laminating resins. IV. Polymers with p-cyclophane units for crosslinking

1,3-Bis(p-phenoxybenzenesulfonyl)benzene, 4,4′-bis(p-phenoxybenzenesulfonyl)diphenyl ether, and 4,4′-diphenoxydiphenyl sulfone were polymerized with isophthaloyl or terephthaloyl chlorides in Friedel-Crafts type polymerizations. These polymers had [2,2]p-cyclophane units in the backbone, introduced by employing 3,9-bis(p-phenoxybenzoyl) [2.2]p-cyclophane as part of the polyaryl ether component. Thermolysis of the dimethylene bridge of the [2.2]p-cyclophane monomer produced diradicals which combined across polymer chains to provide crosslinks. p-Cyclophane polymers with 1,3-bis-(p-phenoxybenzenesulfonyl)benzene showed potential as high performance, thermally stable laminating resins.     

STUDIES OF SODIUM TAUROCHOLATE MICELLES USING FLUORESCENT PROBE MOLECULES

Abstract Micelles formed by sodium taurocholate (NaTC) and mixed micelles formed by NaTC with detergents (SDS, reduced Triton X-100 and CTAC) were studied with fluorescent probes. Pyrene was used as an indicator of the polarity of the micellar binding site by comparison of the fluorescence spectra and vibronic band intensity ratios of pyrene in the different systems. Perylene was used as a fluorescence polarization probe to study the rigidity of the NaTC and mixed micelles. The fluorescence lifetime of perylene in the different systems was also measured. Results of the studies were compared with measurements of the probes in cyclohexane, ethanol and aqueous beta-cyclodextrin. Perylene was found to be more rigidly bound in the NaTC micelles than in the detergent micelles. Insertion of small amounts of reduced Triton X-100 into the NaTC micelles appears to increase the rigidity. The binding sites of NaTC and CTAC have similar polarities, and are more polar than those of SDS and reduced Triton X-100. Insertion of any of the detergents into the NaTC micelle decreases the polarity of the binding site, possibly by reducing the penetration of water into the micelle.     

A peptide-derived strategy for specifically targeting the mitochondria and ER of cancer cells: a new approach in fighting cancer

An effective anti-cancer therapy should exclusively target cancer cells and trigger in them a broad spectrum of cell death pathways that will prevent avoidance. Here, we present a new approach in cancer therapy that specifically targets the mitochondria and ER of cancer cells. We developed a peptide derived from the flexible and transmembrane domains of the human protein NAF-1/CISD2. This peptide (NAF-1^44-67) specifically permeates through the plasma membranes of human epithelial breast cancer cells, abolishes their mitochondria and ER, and triggers cell death with characteristics of apoptosis, ferroptosis and necroptosis. In vivo analysis revealed that the peptide significantly decreases tumor growth in mice carrying xenograft human tumors. Computational simulations of cancer vs. normal cell membranes reveal that the specificity of the peptide to cancer cells is due to its selective recognition of their membrane composition. NAF-1^44-67 represents a promising anti-cancer lead compound that acts via a unique mechanism.

An effective anti-cancer therapy should exclusively target cancer cells and trigger in them a broad spectrum of cell death pathways that will prevent avoidance.     

Fumigant Activity of Bacterial Volatile Organic Compounds against the Nematodes Caenorhabditis elegans and Meloidogyne incognita

Plant-parasitic nematodes infect a diversity of crops, resulting in severe economic losses in agriculture. Microbial volatile organic compounds (VOCs) are potential agents to control plant-parasitic nematodes and other pests. In this study, VOCs emitted by a dozen bacterial strains were analyzed using solid-phase microextraction followed by gas chromatography–mass spectrometry. Fumigant toxicity of selected VOCs, including dimethyl disulfide (DMDS), 2-butanone, 2-pentanone, 2-nonanone, 2-undecanone, anisole, 2,5-dimethylfuran, glyoxylic acid, and S-methyl thioacetate (MTA) was then tested against Caenorhabditis elegans. DMDS and MTA exhibited much stronger fumigant toxicity than the others. Probit analysis suggested that the values of LC₅₀ were 8.57 and 1.43 μg/cm³ air for DMDS and MTA, respectively. MTA also showed stronger fumigant toxicity than DMDS against the root-knot nematode Meloidogyne incognita, suggesting the application potential of MTA.     

Pre-irradiation treatments for CR-39 detectors

The production of track-spots in CR-39 detectors for alpha particles and the subsequent optical counting of the detectors are often influenced by foreign substances deposited on the surface of the detectors. The removal of these substances can be achieved using chemicals for pre-irradiation treatment. Two methods of pre-irradiation treatment were studied in the present experiments. One of them involves the dipping of the detectors in ethanol. In the other method, the detectors were treated in 6N KOH etchant prior to exposure. It was found that prolonged treatment could only produce a reduction in the track density of less than 20%.