Selenium and cadmium induced pulmonary functional impairment and cytotoxicity

Ovalbumin-sensitized (50 mg/kg, i.p.) male Hartley-guinea-pigs (550-610 g; n = 6) were treated 14 days later intratracheally with saline, cadmium (Cd 0.3 mg), selenium (Se 0.3 mg or 0.06 mg) or Se (0.06 mg) with Cd (0.3 mg). After 24 h, baseline dynamic-lung-compliance (Cdynl) and pulmonary-resistance (Rp), and percent change after ovalbumin-aerosol-challenge (10 mg/ml, 60 s) were assessed. Cadmium or Se (0.3 mg), Se (0.06 mg) and/or Cd (0.3 mg) decreased Cdynl (P < 0.05). Selenium (0.3 mg) increased Rp (P < 0.05). Ovalbumin-challenge decreased Cdynl and increased Rp in all groups. Analysis of bronchoalveolar-lavage-fluid (BALF) displayed increased activities of lactate-dehydrogenase (LDH), beta-glucuronidase (beta-G), alkaline-phosphatase (AP), and protein due to 0.3 mg Se, 0.3 mg Cd alone or with 0.06 mg Se (P < 0.05). Findings indicated that, 0.3 mg Se is more detrimental than 0.3 mg Cd to lung-dynamics despite a modest protection by 0.06 mg Se against Cd illustrated by an ameliorated Cdynl and lower protein in BALF.     

The power of “we”: Effects of psychological collectivism on team performance over time.

We examined the influences of different facets of psychological collectivism (Preference, Reliance, Concern, Norm Acceptance, and Goal Priority) on team functioning at 3 different performance depictions: initial team performance, end-state team performance, and team performance change over time. We also tested the extent to which team-member exchange moderated the relationships between facets of psychological collectivism and performance change over time. Results from multilevel growth modeling of 66 teams (N = 264) engaged in a business simulation revealed differential effects across facets of psychological collectivism and across different performance measurements. Whereas facets concerned with affiliation (Preference and Concern) were positively related to initial team performance, reliance was negatively related to initial team performance. Goal Priority was a strong predictor of end-state performance. Team-member exchange moderated the relationship between performance change and 3 of the 5 facets of psychological collectivism (Preference, Reliance, Norm Acceptance). Implications for team composition and team training are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The kinetics of CO2 hydrogenation on a Rh foil promoted by titania overlayers

Submonolayer deposits of titania on a Rh foil have been found to increase the rate of CO₂ hydrogenation. The primary product, methane, exhibits a maximum rate at a TiO _x coverage of 0.5 ML which is a factor of 15 higher than that over the clean Rh surface. The rate of ethane formation displays a maximum which is 70 times that over the unpromoted Rh foil; however, the selectivity for methane remains in excess of 99%. The apparent activation energy for methane formation and the dependence of the rate on H₂ and CO₂ partial pressure have been determined both for the bare Rh surface and the titania-promoted surface. These rate parameters show very small variations as titania is added to the Rh catalyst. The methanation of CO₂ is proposed to start with the dissociation of CO₂ into CO_(a) and O_(a), and then proceed through steps which are identical to those for the hydrogenation of CO. The increase in the rate of CO₂ hydrogenation in the presence of titania is attributed to an interaction between the adsorbed CO, released by CO₂ dissociation, and Ti³⁺ ions located at the edge of TiO _x islands covering the surface. Differences in the effects of titania promotion on the methanation of CO₂ and CO are discussed in terms of the mechanisms that have been proposed for these two reactions.     

Preparation and properties of imide–pyrrone copolymers

Two series of copolymers containing imidazopyrrolone (pyrrone) and imide groups were prepared by solution polymerization. Thin films of the copolymers showed a general increase in the tangent modulus and a decrease in elongation with increasing pyrrone content. The copolymers were more resistant to degradation by strong acids and bases than the corresponding polyimides. The thermal stabilities of the copolymers in air improved with increasing imide content, while the thermal stabilities in a vacuum improved with increasing pyrrone content. These copolymers represent a way to combine the desirable properties of both classes of homopolymers.     

Calcium phosphate substrates with emulsion-derived roughness: Processing,characterisation and interaction with human mesenchymal stem cells

Calcium phosphates (CaP) have been the subject of several studies that often lack a systematic approach to understanding how their properties affect biological response. CaP particles functionalised with a pH-responsive polymer (BCS) were used to prepare microporous substrates (porosity between 70 and 75% and pore sizes of 5–20 μm) through the aggregation of oil-in-water emulsions by controlling solid loading, emulsification energy, pH, drying and sintering conditions. The combined effect of surface roughness (roughness amplitude, R_a between 0.9–1.7 μm) and chemistry (varying Hydroxyapatite/β-Tricalcium phosphate ratio) on human mesenchymal stem cells was evaluated. HA substrates stimulated higher cell adhesion and proliferation (especially with lower R_a), but cell area increased with β-TCP content. The effect of surface roughness depended of chemistry: HA promoted higher mineralising activity when R_a ～ 1.5 μm, whereas β-TCP substrates stimulated a more osteogenic profile when R_a ～ 1.7 μm. A novel templating method to fabricate microporous CaP substrates was developed, opening possibilities for bone substitutes with controlled features.     

Vitamin C Enhances Vitamin E Status and Reduces Oxidative Stress Indicators in Sea Bass Larvae Fed High DHA Microdiets

Docosahexaenoic acid (DHA) is an essential fatty acid necessary for many biochemical, cellular and physiological functions in fish. However, high dietary levels of DHA increase free radical injury in sea bass (Dicentrarchus labrax) larvae muscle, even when vitamin E (α-tocopherol, α-TOH) is increased. Therefore, the inclusion of other nutrients with complementary antioxidant functions, such as vitamin C (ascorbic acid, vitC), could further contribute to prevent these lesions. The objective of the present study was to determine the effect of vitC inclusion (3,600?mg/kg) in high DHA (5?% DW) and α-TOH (3,000?mg/kg) microdiets (diets 5/3,000 and 5/3,000?+?vitC) in comparison to a control diet (1?% DHA DW and 1,500?mg/kg of α-TOH; diet 1/1,500) on sea bass larvae growth, survival, whole body biochemical composition and thiobarbituric acid reactive substances (TBARS) content, muscle morphology, skeletal deformities and antioxidant enzymes, insulin-like growth factors (IGFs) and myosin expression (MyHC). Larvae fed diet 1/1,500 showed the best performance in terms of total length, incidence of muscular lesions and ossification degree. IGFs gene expression was elevated in 5/3,000 diet larvae, suggesting an increased muscle mitogenesis that was confirmed by the increase in the mRNA copies of MyHC. vitC effectively controlled oxidative damages in muscle, increased α-TOH larval contents and reduced TBARS content and the occurrence of skull deformities. The results of the present study showed the antioxidant synergism between vitamins E and C when high contents of DHA are included in sea bass larvae diets.     

Investigation of the structure and activity of VOx/CeO2/SiO2 catalysts for methanol oxidation to formaldehyde

The effect of ceria on the partial oxidation of methanol to formaldehyde over VO_x/CeO₂/SiO₂ catalysts was investigated. A two-dimensional layer of ceria on silica was prepared by grafting cerium (IV) t-butoxide (Ce(OC₄H₉)₄) onto high surface area, mesoporous silica, SBA-15, and then calcining the resulting product in air at 773 K. Ce surface concentrations obtained this way ranged from 0.2 to 0.9 Ce nm^?2. Next, V was introduced by grafting VO(OⁱPr)₃ onto CeO₂/SiO₂ in order to achieve a surface concentration of 0.6 V nm^?2. XANES spectra indicate that all of the V is in the 5+ oxidation state and Raman spectra show that vanadia exist as pseudo-tetrahedra bonded to either silica or ceria. Data from Raman spectroscopy and temperature-programmed desorption of adsorbed methanol indicate that with increasing Ce surface density, most of the V becomes associated with the deposited ceria. The turnover frequency for methanol oxidation is nearly two orders of magnitude higher for VO_x/CeO₂/SiO₂ than for VO_x/SiO₂, whereas the apparent activation energy and apparent first-order pre-exponential factor are 17 kcal/mol and 1.4 × 10⁶ mol CH₂O (mol V atm s)^?1, respectively, for VO_x/CeO₂/SiO₂ and 23 kcal/mol and 2.3 × 10⁷ mol CH₂O (mol V atm s)^?1, respectively, for VO_x/SiO₂.     

The Oxidation of Hydrophobic Aromatic Substrates by Using a Variant of the P450 Monooxygenase CYP101B1

The cytochrome P450 monooxygenase CYP101B1, from a Novosphingobium bacterium is able to bind and oxidise aromatic substrates but at a lower activity and efficiency than norisoprenoids and monoterpenoid esters. Histidine 85 of CYP101B1 aligns with tyrosine 96 of CYP101A1, which, in the latter enzyme forms the only hydrophilic interaction with its substrate, camphor. The histidine residue of CYP101B1 was mutated to phenylalanine with the aim of improving the activity of the enzyme for hydrophobic substrates. The H85F mutant lowered the binding affinity and activity of the enzyme for β-ionone and altered the oxidation selectivity. This variant also showed enhanced affinity and activity towards alkylbenzenes, styrenes and methylnaphthalenes. For example the rate of product formation for acenaphthene oxidation was improved sixfold to 245 nmol per nmol CYP per min. Certain disubstituted naphthalenes and substrates, such as phenylcyclohexane and biphenyls, were oxidised with lower activity by the H85F variant. Variants at H85 (A and G) designed to introduce additional space into the active site so as to accommodate these larger substrates did not improve the oxidation activity. As the H85F mutant of CYP101B1 improved the oxidation of hydrophobic substrates, this residue is likely to be in the substrate binding pocket or the access channel of the enzyme. The side chain of the histidine might interact with the carbonyl groups of the favoured norisoprenoid substrates of CYP101B1.     

Validation of the MEDFICTS dietary questionnaire: A clinical tool to assess adherence to American Heart Association dietary fat intake guidelines

Background  

Dietary assessment tools are often too long, difficult to quantify, expensive to process, and largely used for research purposes. A rapid and accurate assessment of dietary fat intake is critically important in clinical decision-making regarding dietary advice for coronary risk reduction. We assessed the validity of the MEDFICTS (MF) questionnaire, a brief instrument developed to assess fat intake according to the American Heart Association (AHA) dietary "steps".     

Production of human normal adult and fetal hemoglobins in Escherichia coli

A hemoglobin expression system in Escherichia coli is described. In order to produce authentic human hemoglobin, we need to co-express both methionine aminopeptidase and globin genes under the control of a strong promoter. We have constructed three plasmids, pHE2, pHE4 and pHE7, for the expression of human normal adult hemoglobin and a plasmid, pHE9, for the expression of human fetal hemoglobin, in high yields. The globin genes can be derived from either synthetic genes or human globin cDNAs. The extra amino-terminal methionine residues of the expressed globins can be removed by the co-expressed methionine aminopeptidase. The heme is inserted correctly into the expressed alpha- globin from our expression plasmids. A fraction (approximately 25%) of the heme is not inserted correctly into the expressed beta- or gamma- globin. However, the incorrectly inserted hemes can be converted into the correct conformation by carrying out a simple oxidation-reduction process on the purified hemoglobin molecule. We have investigated the functional properties of the expressed hemoglobins by measuring their oxygen-binding properties and their structural features by obtaining their 1H-NMR spectra. Our results show that authentic human normal adult and fetal hemoglobins can be produced from our expression plasmids in E. coli and in high yields. Our expression system allows us to design and to produce any recombinant hemoglobins needed for our research on the structure-function relationship in hemoglobin.