Synthesis of selenium-containing polyphenolic acid esters and evaluation of their effects on antioxidation and 5-lipoxygenase inhibition

Six novel selenium-containing polyphenolic acid esters were synthesized and evaluated as antioxidants and 5-lipoxygenase inhibitors. Synthesis of the title compounds involved the Mitsunobu reaction of polyphenolic acids with 2-phenylselenoethanol. Compounds and were found to be very effective antioxidants and 5-lipoxygenase inhibitors with activity comparable to or better than caffeic acid (3,4-dihydroxycinnamic acid) phenethyl ester (CAPE).     

Mössbauer Spectroscopic Studies of Chlorostannate(II) Complexes in Frozen Aqueous Solutions

Mössbauer parameters of frozen aqueous solutions of Sn(ClO₄)₂ in 0.5 M HClO₄ did not change with the concentration of NaClO₄, so that it was used to keep the ionic strength at the desired level. When NaCl was added into Sn(ClO₄)₂ solutions, isomer shift did not change, but quadrupole splitting did. Therefore, stability constants were calculated from the quadrupole splitting data, which were in good agreement with the published values. The observed spectra could be resolved into components.     

Parallel mixing of photolithographically defined nanoliter volumes using elastomeric microvalve arrays

Portable microfluidic systems provide simple and effective solutions for low-cost point-of-care diagnostics and high-throughput biomedical assays. Robust flow control and precise fluidic volumes are two critical requirements for these applications. We have developed a monolithic polydimethylsiloxane (PDMS) microdevice that allows for storing and mixing subnanoliter volumes of aqueous solutions at various mixing ratios. Filling and mixing is controlled via two integrated PDMS microvalve arrays. The volumes of the microchambers are entirely defined by photolithography, hence volumes from picoliter to nanoliter can be fabricated with high precision. Because the microvalves do not require an energy input to stay closed, fluid can be stored in a highly portable fashion for several days. We have confirmed the mixing precision and predictability using fluorescence microscopy. We also demonstrate the application of the device for calibrating fluorescent calcium indicators. Due to the biocompatibility of PDMS, the device will have broad applications in miniaturized diagnostic assays as well as basic biological studies.     

INDUCTION OF SKIN TUMORS IN HAIRLESS MICE BY A SINGLE EXPOSURE TO UV RADIATION*

Abstract— Skin tumors were induced in hairless mutant mice following a single exposure to ultraviolet radiation (UV). Tumors were first noted as early as 7 weeks following irradiation. The UV, emitted by FS20/40T12 fluorescent lamps, was principally in the 280–320 nm spectral region with a peak at 313 nm. Single (skin surface) doses of 3 times 10⁴ J/m² to 24 times 10⁴ J/m² were delivered in 3 h or less. The higher doses resulted in more severe acute damage as well as greater tumor yield. Most of the tumors were benign hyperplastic epithelial papillomas; 4 out of 96 tumors examined histologically proved to be squamous cell carcinomas. This appears to be the first report of experimental carcinogenesis due to a single UV exposure, not requiring exogenous chemical promotion.     

Characterization of N-terminal processing of group VIA phospholipase A<Subscript>2</Subscript> and of potential cleavage sites of amyloid precursor protein constructs by automated identification of signature peptides in LC/MS/MS analyses of proteolytic digests

Dysregulation of proteolytic processing of the amyloid precursor protein (APP) contributes to the pathogenesis of Alzheimer's Disease, and the Group VIA phospholipase A(2) (iPLA(2)beta) is the dominant PLA(2) enzyme in the central nervous system and is subject to regulatory proteolytic processing. We have identified novel N-terminal variants of iPLA(2)beta and previously unrecognized proteolysis sites in APP constructs with a C-terminal 6-myc tag by automated identification of signature peptides in LC/MS/MS analyses of proteolytic digests. We have developed a Signature-Discovery (SD) program to characterize protein isoforms by identifying signature peptides that arise from proteolytic processing in vivo. This program analyzes MS/MS data from LC analyses of proteolytic digests of protein mixtures that can include incompletely resolved components in biological samples. This reduces requirements for purification and thereby minimizes artifactual modifications during sample processing. A new algorithm to generate the theoretical signature peptide set and to calculate similarity scores between predicted and observed mass spectra has been tested and optimized with model proteins. The program has been applied to the identification of variants of proteins of biological interest, including APP cleavage products and iPLA(2)beta, and such applications demonstrate the utility of this approach.     

Identification of odor signature chemicals in cocaine using solid-phase microextraction-gas chromatography and detector-dog response to isolated compounds spiked on U.S. paper currency

Solid-phase microextraction (SPME) combined with gas chromatography (GC) is optimized and applied to the analysis of street-cocaine samples followed by the field-testing of isolated chemicals using certified detector dogs. SPME proves to be a very sensitive and rapid method for isolating odor chemicals from street-cocaine samples. SPME-GC and activated charcoal strip (ACS)-SPME-GC signature profile methods are developed for the detection and quantitation of cocaine-odor chemicals, including the optimization of controllable variables such as fiber chemistry, extraction time, and desorption time. The volatile odor chemicals in representative illicit cocaine samples are identified and quantitated by the ACS-SPME-GC signature profile method and direct injection. Field tests with drug detector dogs show methyl benzoate to be the dominant signature odor chemical along with cocaine on U.S. currency at a threshold level of approximately 1-10 microg when spiked or when 10 ng/s methyl benzoate is diffused from polymer bottles, which is required in order to initiate an alert. No other substance studied initiated consistent responses by the drug dogs. The results indicate that the microgram levels of cocaine that have been reported on circulated U.S. currency are insufficient to signal an alert from law-enforcement trained drug detector dogs.