Carbonate-Based Fluorescent Chemical Tool for Uncovering Carboxylesterase 1 (CES1) Activity Variations in Live Cells

Carboxylesterase 1 (CES1) plays a key role in the metabolism of endogenous biomolecules and xenobiotics including a variety of pharmaceuticals. Despite the established importance of CES1 in drug metabolism, methods to study factors that can vary CES1 activity are limited with only a few suitable for use in live cells. Herein, we report the development of FCP1, a new CES1 specific fluorescent probe with a unique carbonate substrate constructed from commercially available reagents. We show that FCP-1 can specifically report on endogenous CES1 activity with a robust fluorescence response in live HepG2 cells through studies with inhibitors and genetic knockdowns. Subsequently, we deployed FCP-1 to develop a live cell fluorescence microscopy-based approach to identify activity differences between CES1 isoforms. To the best of our knowledge, this is the first application of a fluorescent probe to measure the activity of CES1 sequence variants in live cells.     

Cyclic Adenosine Monophosphate Eliminates Sex Differences in Estradiol-Induced Elastin Production from Engineered Dermal Substitutes

Lack of adult cells’ ability to produce sufficient amounts of elastin and assemble functional elastic fibers is an issue for creating skin substitutes that closely match native skin properties. The effects of female sex hormones, primarily estrogen, have been studied due to the known effects on elastin post-menopause, thus have primarily included older mostly female populations. In this study, we examined the effects of female sex hormones on the synthesis of elastin by female and male human dermal fibroblasts in engineered dermal substitutes. Differences between the sexes were observed with 17β-estradiol treatment alone stimulating elastin synthesis in female substitutes but not male. TGF-β levels were significantly higher in male dermal substitutes than female dermal substitutes and the levels did not change with 17β-estradiol treatment. The male dermal substitutes had a 1.5-fold increase in cAMP concentration in the presence of 17β-estradiol compared to no hormone controls, while cAMP concentrations remained constant in the female substitutes. When cAMP was added in addition to 17β-estradiol and progesterone in the culture medium, the sex differences were eliminated, and elastin synthesis was upregulated by 2-fold in both male and female dermal substitutes. These conditions alone did not result in functionally significant amounts of elastin or complete elastic fibers. The findings presented provide insights into differences between male and female cells in response to female sex steroid hormones and the involvement of the cAMP pathway in elastin synthesis. Further explorations into the signaling pathways may identify better targets to promote elastic fiber synthesis in skin substitutes.     

High Dielectric Breakdown Strength Nanoplatelet-Based Multilayer Thin Films

Dielectric materials that can withstand high voltages are of great interest due to the growing need for high-performance insulation systems in electronics. Polymer nanocomposites have gained popularity as electrical insulators due to their processability, high operating voltage, and tortuous paths for current flow created by the nanoparticles in the polymer matrix. The dielectric breakdown strength of a relatively thick multilayer thin film containing polyethylenimine (PEI) and vermiculite clay (VMT), thickened with tris(hydroxymethyl)aminomethane (tris), is evaluated as a function of bilayers (BL) deposited. The resulting nanobrick wall structure of this clay-based assembly is ideal for protective insulation. An 8 BL PEI+tris/VMT film achieves a dielectric breakdown strength of 245 kV mm⁻¹, with a thickness of 5 µm. With increasing bilayers, the breakdown strength gradually decreases, but 20 BL of PEI+tris/VMT achieves a breakdown voltage of 2.36 kV. This nanoplatelet-based system is the first “thick growing” layer-by-layer deposited film to be used as an insulating layer. Its unusually high breakdown strength can be useful for the protection of various high voltage electronics.     

Experiencing CSCL: from motivation to the embodied experience and beyond

International Journal of Computer-Supported Collaborative Learning -     

Spatial and Ontogenetic Variability of Sea Lamprey Diets in Lake Superior

Invasive sea lamprey (Petromyzon marinus) remain an important source of fish mortality in the Laurentian Great Lakes, yet assessing their impact is hindered by lack of quantitative diet information. We examined nitrogen and carbon stable isotope ratios (δ¹⁵N and δ¹³C) of sea lamprey and host species in six ecoregions of Lake Superior, mainly in 2002–2004. Data implied that most sea lamprey fed primarily on upper trophic level species, including forms of lake trout (Salvelinus namaycush). However, in Ontario waters, particularly semi-enclosed Black Bay, sea lamprey relied heavily on lower trophic levels, such as coregonines (Coregonus spp.) and suckers (Catostomus spp.). Sea lamprey δ¹⁵N and δ¹³C generally increased with sea lamprey size, implying dependence on higher trophic levels later in life. Most parasitic sea lamprey that we captured were attached to either lean lake trout (35% of observed attachments), lake whitefish (Coregonus clupeaformis; 25%), or cisco (C. artedii; 25%); the latter sea lamprey were typically < 15 g. Survey- and fishery-dependent wounding rate data compiled from 1986–2005 suggest that lean and siscowet lake trout were selectively parasitized by sea lamprey, which is consistent with our stable isotope data. Our results largely support the notion that lake trout are the principal host species in Lake Superior. However, stable isotope evidence that sea lamprey feed at lower trophic levels in some regions argues for comprehensive monitoring of sea lamprey impacts throughout the fish community in systems that sea lamprey have invaded.     

Coordinate intracellular expression of Salmonella genes induced during infection

Salmonella typhimurium in vivo-induced (ivi) genes were grouped by their coordinate behavior in response to a wide variety of environmental and genetic signals, including pH, Mg2+, Fe2+, and PhoPQ. All of the seven ivi fusions that are induced by both low pH and low Mg2+ (e.g., iviVI-A) are activated by the PhoPQ regulatory system. Iron-responsive ivi fusions include those induced under iron limitation (e.g., entF) as well as one induced by iron excess but only in the absence of PhoP (pdu). Intracellular expression studies showed that each of the pH- and Mg2+-responsive fusions is induced upon entry into and growth within three distinct mammalian cell lines: RAW 264.7 murine macrophages and two cultured human epithelial cell lines: HEp-2 and Henle-407. Each ivi fusion has a characteristic level of induction consistent within all three cell types, suggesting that this class of coordinately expressed ivi genes responds to general intracellular signals that are present both in initial and in progressive stages of infection and may reflect their responses to similar vacuolar microenvironments in these cell types. Investigation of ivi expression patterns reveals not only the inherent versatility of pathogens to express a given gene(s) at various host sites but also the ability to modify their expression within the context of different animal hosts, tissues, cell types, or subcellular compartments.     

Personality differences in attempted suicide versus suicide in adults 50 years of age or older.

The authors tested hypotheses concerning personality differences in treatment-seeking suicide attempters (AT; n = 60) and a community sample of suicides (SU; n = 43) over age 50. On the basis of prior research, the authors hypothesized that SU would be lower in Neuroticism and Openness and higher in Conscientiousness. A 2-group (AT vs. SU) multivariate analysis of covariance with NEO Personality Inventory--Revised (Informant Version) domain scores as dependent variables revealed that SU were lower in Neuroticism and higher in Conscientiousness. The authors conclude that AT and SU in this age group can be distinguished on the basis of informant ratings of personality traits. These differences can inform risk detection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The heterogeneous character of the dilute acid hydrolysis of crystalline cellulose. II. Hydrolysis in sulfuric acid

Nine prehydrolyzed cellulose samples, including native, mercerized, and regenerated celluloses were hydrolyzed in 2% sulfuric acid at 150, 160, and 170°C. The first-order rate constants and the weight average degrees of polymerization (by size exclusion chromatography) were determined for each sample. The results indicate that Sharples' end-attack model [Trans. Faraday Soc., 53 , 1003 (1957)] is consistent with kinetic data for cellulose II samples, but is not appropriate for characterizing the reactions of cellulose I samples.