Hexabromocyclododecanes in indoor dust from Canada, the United Kingdom, and the United States

alpha-, beta-, and gamma-hexabromocyclododecane diastereomers (HBCDs) were measured in house dust from Birmingham, U.K. (n=31, median concentration=730 ng sigmaHBCDs g(-1)); Amarillo/Austin, TX (n=13, 390 ng g(-1)); and Toronto, Canada (n=8, 640 ng g(-1)). Concentrations in dust (n=6, 650 ng g(-1)) from U.K. offices were within the range for UK homes. Concentrations from each country were statistically indistinguishable. In one UK house dust sample, 110,000 ng g(-1) was recorded-the highest recorded in indoor dust to date. While upper bound average U.K. dietary exposures for adults and toddlers, respectively, are 413 and 240 ng sigmaHBCDs day(-1), U.K. adults and toddlers daily ingesting, respectively, 50 and 200 mg of dust contaminated at the 95th percentile concentration are exposed, respectively, to 1100 and 4400 ng sigmaHBCDs day(-1). Normalized to body weight, this high-end exposure scenario estimate for toddlers is within the range reported elsewhere for occupationally exposed adults. While in commercial formulations gamma-HBCD predominates (>80%), alpha-HBCD in dust constitutes 14-67% of sigmaHBCDs (average 32%). Hence the predominance of the alpha-diastereomer in humans may arise partly from dust ingestion, and not solely to in vivo metabolism (when alpha-HBCD is formed from bioisomerization of other diastereomers), or dietary exposure (where alpha-HBCD predominates in most foodstuffs).     

Total phenolic compounds and antioxidant capacities of major fruits from Ecuador

Seventeen fruits from Ecuador were analysed for total soluble phenolic compounds content and for antioxidant capacity, using three different methods (DPPH, FRAP and ABTS⁺). For the total phenolic content measured by the Folin–Ciocalteu method, three groups, having <100, 200–500 and >1000 mg GAE/100 g FW, were clearly distinguishable. Andean blackberry, capulí cherry peel and banana passion fruit were classified in the third group, with concentrations of 2167, 1494 and 1010 mg of GAE/100 g FW, respectively. Antioxidant capacity analyses revealed the same classes. FRAP and ABTS⁺ gave comparable results and were highly correlated (y = 0.691x + 6.78; r² = 0.908). Spectrophotometric measurements showed that the Andean blackberry and capulí peel but not banana passion fruit contained high levels of anthocyanins (λ_max = 520 nm).     

New mechanisms and therapeutic potential of curcumin for colorectal cancer

Curcumin is a polyphenol derived from Curcuma longa. Over the last few years, a number of studies have provided evidence of its main pharmacological properties including chemosensitizing, radiosensitizing, wound healing activities, antimicrobial, antiviral, antifungical, immunomodulatory, antioxidant and anti-inflammatory. More recent data provide interesting insights into the effect of this compound on cancer chemoprevention and chemotherapy. In fact, preclinical studies have shown its ability to inhibit carcinogenesis in various types of cancer including colorectal cancer (CRC). Curcumin has the capacity of interact with multiple molecular targets affecting the multistep process of carcinogenesis. Also, curcumin is able to arrest the cell cycle, to inhibit the inflammatory response and the oxidative stress and to induce apoptosis in cancer cells. Likewise, it has been shown to possess marked antiangiogenic properties. Furthermore, curcumin potentiates the growth inhibitory effect of cyclo-oxygenase (COX)-2 inhibitors and traditional chemotherapy agents implicating another promising therapy regimen in the future treatment of CRC. However, its clinical advance has been hindered by its short biological half-life and low bioavailability after oral administration. This review is intended to provide the reader an update of the bioavailability and pharmacokinetics of curcumin and describes the recently identified molecular pathways responsible of its anticancer potential in CRC.     

Optical fiber immunosensor based on a poly(pyrrole-benzophenone) film for the detection of antibodies to viral antigen

We describe herein a newly developed optical microbiosensor for the diagnosis of hepatitis C virus (HCV) by using a novel photoimmobilization methodology based on a photoactivable electrogenerated polymer film deposited upon surface-conductive fiber optics, which are then used to link a biological receptor to the fiber tip through light mediation. This fiber-optic electroconductive surface modification is done by the deposition of a thin layer of indium tin oxide on the silica surface of the fiber optics. Monomers are then electropolymerized onto the conductive metal oxide surface; thereafter, the fibers are immersed in a solution containing HCV-E2 envelope protein antigen and illuminated with UV light (wavelength approximately 345 nm). As a result of the photochemical reaction, a thin layer of the antigen becomes covalently bound to the benzophenone-modified surface. The photochemically modified fiber optics were tested as immunosensors for the detection of anti-E2 protein antibody analyte that was measured through chemiluminescence reaction. The biosensor was tested for sensitivity, specificity, and overall practicality. Our results suggest that the detection of anti-E2 antibodies with this microbiosensor may enhance significantly HCV serological standard testing especially among patients during dialysis, which were diagnosed as HCV negative, by standard immunological tests, but were known to carry the virus. If transformed into an easy to use procedure, this assay might be used in the future as an important clinical tool for HCV screening in blood banks.     

Protein flexibility and ligand rigidity: a thermodynamic and kinetic study of ITAM-based ligand binding to Syk tandem SH2

The Syk tandem Src homology 2 domain (Syk tSH2) constitutes a flexible protein module involved in the regulation of Syk kinase activity. The Syk tSH2 domain is assumed to function by adapting the distance between its two SH2 domains upon bivalent binding to diphosphotyrosine ligands. A thermodynamic and kinetic analysis of ligand binding was performed by using surface plasmon resonance (SPR). Furthermore, the effect of binding on the Syk tSH2 structural dynamics was probed by hydrogen/deuterium exchange and electrospray mass spectrometry (ESI-MS). Two ligands were studied: 1, a flexible peptide derived from the tSH2 recognition ITAM sequence at the gamma chain of the FcepsilonRI-receptor, and 2, a ligand in which the amino acids between the two SH2 binding motifs in ligand 1 have been replaced by a rigid linker of comparable length. Both ligands display comparable affinity for Syk tSH2 at 25 degrees C, yet a major difference in thermodynamics is observed. Upon binding of the rigid ligand, 2, the expected entropy advantage is not realized. On the contrary, 2 binds with a considerably higher entropy price of approximately 9 kcal mol-1, which is attributed to a further decrease in protein flexibility upon binding to this rigid ligand. The significant reduction in deuterium incorporation in the Syk tSH2 protein upon binding of either 1 or 2, as monitored by ESI-MS, indicates a major reduction in protein dynamics upon binding. The results are consistent with a two-step binding model: after an initial binding step, a rapid structural change of the protein occurs, followed by a second binding step. Such a bivalent binding model allows high affinity and fast dissociation kinetics, which are very important in transient signal-transduction processes.     

Metastable phase formation in laser-processed Al-Ge sputtered thin films

The formation of a metastable phase in Al₅₉Ge₄₁ thin films under microsecond laser irradiation is reported. Thin films prepared by co-sputtering are amorphous as-grown. Upon laser processing, amorphous and crystalline phases are detected and analysed using TEM and EDX. A metastable structure formed by laminar-textured aluminium alternating with an hexagonal metastable phase is observed.     

Polyphenols and human health: a prospectus

The lay press often heralds polyphenols as panacea for all sorts of diseases. The rationale is that their antioxidant activity would prevent free radical damage to macromolecules. However, basic and clinical science is showing that the reality is much more complex than this and that several issues, notably content in foodstuff, bioavailability, or in vivo antioxidant activity are yet to be resolved. We summarize the recent findings concerning the effects of polyphenols on human health, analyze the current limitations at pitfalls, and propose future directions for research.