Oxidative dehalogenation of trichlorophenol catalyzed by a promiscuous artificial heme-enzyme

The miniaturized metalloenzyme Fe(iii)-mimochrome VI*a (Fe(iii)-MC6*a) acts as an excellent biocatalyst in the H₂O₂-mediated oxidative dehalogenation of the well-known pesticide and biocide 2,4,6-trichlorophenol (TCP). The artificial enzyme can oxidize TCP with a catalytic efficiency (k_cat/K^TCP_m = 150 000 mM⁻¹ s⁻¹) up to 1500-fold higher than the most active natural metalloenzyme horseradish peroxidase (HRP). UV-visible and EPR spectroscopies were used to provide indications of the catalytic mechanism. One equivalent of H₂O₂ fully converts Fe(iii)-MC6*a into the oxoferryl-porphyrin radical cation intermediate [(Fe(iv) O)por˙⁺], similarly to peroxidase compound I (Cpd I). Addition of TCP to Cpd I rapidly leads to the formation of the corresponding quinone, while Cpd I decays back to the ferric resting state in the absence of substrate. EPR data suggest a catalytic mechanism involving two consecutive one-electron reactions. All results highlight the value of the miniaturization strategy for the development of chemically stable, highly efficient artificial metalloenzymes as powerful catalysts for the oxidative degradation of toxic pollutants.

The artificial metalloenzyme FeMC6*a is able to perform the H₂O₂-mediated dechlorination of 2,4,6-trichlorophenol with unrivalled catalytic efficiency, highlighting its potential application for the removal of toxic pollutants.     

Female teachers’ math anxiety affects girls’ math achievement

People’s fear and anxiety about doing math—over and above actual math ability—can be an impediment to their math achievement. We show that when the math-anxious individuals are female elementary school teachers, their math anxiety carries negative consequences for the math achievement of their female students. Early elementary school teachers in the United States are almost exclusively female (>90%), and we provide evidence that these female teachers’ anxieties relate to girls’ math achievement via girls’ beliefs about who is good at math. First- and second-grade female teachers completed measures of math anxiety. The math achievement of the students in these teachers’ classrooms was also assessed. There was no relation between a teacher’s math anxiety and her students’ math achievement at the beginning of the school year. By the school year’s end, however, the more anxious teachers were about math, the more likely girls (but not boys) were to endorse the commonly held stereotype that “boys are good at math, and girls are good at reading” and the lower these girls’ math achievement. Indeed, by the end of the school year, girls who endorsed this stereotype had significantly worse math achievement than girls who did not and than boys overall. In early elementary school, where the teachers are almost all female, teachers’ math anxiety carries consequences for girls’ math achievement by influencing girls’ beliefs about who is good at math.     

Facial porokeratosis: A series of six patients

Porokeratosis is a disorder of epidermal keratinization characterized by annular plaques with an atrophic centre and hyperkeratotic edges, and includes a heterogeneous group of disorders that are mostly inherited in an autosomal dominant fashion. Facial porokeratosis is rare and is not well documented. We present six cases of facial porokeratosis seen over a period of 15 years in a hospital in Lima, Peru. In most of the cases, porokeratosis was found in younger women without any significant past medical history. Oral isotretinoin showed moderate improvement in two of our patients.     

Fluorescent Magnetic Bioprobes by Surface Modification of Magnetite Nanoparticles

Bimodal nanoprobes comprising both magnetic and optical functionalities have been prepared via a sequential two-step process. Firstly, magnetite nanoparticles (MNPs) with well-defined cubic shape and an average dimension of 80 nm were produced by hydrolysis of iron sulfate and were then surface modified with silica shells by using the sol-gel method. The Fe₃O₄@SiO₂ particles were then functionalized with the fluorophore, fluorescein isothiocyanate (FITC), mediated by assembled shells of the cationic polyelectrolyte, polyethyleneimine (PEI). The Fe₃O₄ functionalized particles were then preliminary evaluated as fluorescent and magnetic probes by performing studies in which neuroblast cells have been contacted with these nanomaterials.     

Purified and highly aggregated chimeric protein DIIIC-2 induces a functional immune response in mice against dengue 2 virus

It was previously reported that DIIIC-2 (a fusion protein composed of domain III of the envelope protein and the capsid protein from dengue 2 virus), as an aggregate antigen from a partially purified preparation, induced a functional protective immune response against dengue 2 virus in the mouse encephalitis model. In the present work, a purification procedure was developed for DIIIC-2, and soluble and aggregated fractions of the purified protein were characterized and evaluated in mice. The purification process rendered a protein preparation of 91 % purity, and the remaining 9 % consisted of fragments and aggregates of the same recombinant protein. After the in vitro aggregation process, upon addition of oligodeoxynucleotides, 80 % of the protein formed aggregates, whereas 20 % remained as soluble protein. An immunological evaluation revealed the proper immunogenicity of the aggregated purified protein in terms of induction of antiviral and neutralizing antibodies, cell-mediated immunity and protection upon dengue 2 virus challenge in the mouse encephalitis model. Based on these results, we can assert that the purified protein DIIIC-2 is functional and could be used for further scalable steps and preclinical studies in non-human primates.     

Dermal exposure to jet fuel suppresses delayed-type hypersensitivity: a critical role for aromatic hydrocarbons.

Dermal exposure to military (JP-8) and/or commercial (Jet-A) jet fuel suppresses cell-mediated immune reactions. Immune regulatory cytokines and biological modifiers, including platelet activating factor (PAF), prostaglandin E(2), and interleukin-10, have been implicated in the pathway of events leading to immune suppression. It is estimated that approximately 260 different hydrocarbons are found in jet fuel, and the exact identity of the active immunotoxic agent(s) is unknown. The recent availability of synthetic jet fuel (S-8), which is refined from natural gas, and is devoid of aromatic hydrocarbons, made it feasible to design experiments to address this problem. Here we tested the hypothesis that the aromatic hydrocarbons present in jet fuel are responsible for immune suppression. We report that applying S-8 to the skin of mice does not upregulate the expression of epidermal cyclooxygenase-2 (COX-2) nor does it induce immune suppression. Adding back a cocktail of seven of the most prevalent aromatic hydrocarbons found in jet fuel (benzene, toluene, ethylbenzene, xylene, 1,2,4-trimethlybenzene, cyclohexylbenzene, and dimethylnaphthalene) to S-8 upregulated epidermal COX-2 expression and suppressed a delayed-type hypersensitivity (DTH) reaction. Injecting PAF receptor antagonists, or a selective cycloozygenase-2 inhibitor into mice treated with S-8 supplemented with the aromatic cocktail, blocked suppression of DTH, similar to data previously reported using JP-8. These findings identify the aromatic hydrocarbons found in jet fuel as the agents responsible for suppressing DTH, in part by the upregulation of COX-2, and the production of immune regulatory factors and cytokines.     

Operational studies with Valent VectoLex WDG,Bacillus sphaericus,in three Florida Mosquito Control Districts

VectoLex WDG, Bacillus sphaericus (Valent BioSciences Corporation), was evaluated in 3 Florida Mosquito Control Districts under operational conditions. Application rates were 0.5 and 1.0 lb/acre and an untreated control in each district. Study sites included woodland ponds, residential areas such as catch basins, and commercial business retention ponds. Pretreatment and posttreatment assessments were made with a standard dipper at designated dipping stations. The most prevalent mosquitoes included Culex quinquefasciatus, Culex nigripalpus, Culex erraticus, Ochlerotatus infirmatus, Anopheles crucians, Anopheles quadrimaculatus, and Psorophora spp. VectoLex WDG was effective for 24-35 days posttreatment with one application.