Cell targeting with hybrid Qβ virus-like particles displaying epidermal growth factor

Structurally uniform protein nanoparticles derived from the self-assembly of viral capsid proteins are attractive platforms for the multivalent display of cell-targeting motifs for use in nanomedicine. Virus-based nanoparticles are of particular interest because the scaffold can be manipulated both genetically and chemically to simultaneously display targeting groups and carry a functional payload. Here, we displayed the human epidermal growth factor (EGF) on the exterior surface of bacteriophage Qβ as a C-terminal genetic fusion to the Qβ capsid protein. The co-assembly of wild-type Qβ and EGF-modified subunits resulted in structurally homogeneous nanoparticles displaying between 5 and 12 copies of EGF on their exterior surface. The particles were found to be amenable to bioconjugation by standard methods as well as the high-fidelity copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC). Such chemical derivatization did not impair the ability of the particles to specifically interact with the EGF receptor. Additionally, the particle-displayed EGF remained biologically active promoting autophosphorylation of the EGF receptor and apoptosis of A431 cells. These results suggest that hybrid Qβ-EGF nanoparticles could be useful vehicles for targeted delivery of imaging and/or therapeutic agents.     

Why so impulsive? White matter alterations are associated with impulsivity in chronic marijuana smokers.

Difficulty monitoring and inhibiting impulsive behaviors has been reported in marijuana (MJ) smokers; neuroimaging studies, which examined frontal systems in chronic MJ smokers, have reported alterations during inhibitory tasks. Diffusion tensor imaging (DTI) provides a quantitative estimate of white matter integrity at the microstructural level. We applied DTI, clinical ratings, and impulsivity measures to explore the hypotheses that chronic, heavy MJ smokers would demonstrate alterations in white matter microstructure and a different association between white matter measures and impulsivity relative to nonsmoking control subjects (NS). Fractional anisotropy (FA), a measure of directional coherence, and trace, a measure of overall diffusivity, were calculated for 6 locations including bilateral frontal regions in 15 chronic MJ smokers and 15 NS. Subjects completed clinical rating scales, including the Barratt Impulsivity Scale (BIS). Analyses revealed significant reductions in left frontal FA in MJ smokers relative to NS and significantly higher levels of trace in the right genu. MJ smokers also had significantly higher BIS total and motor subscale scores relative to NS, which were positively correlated with left frontal FA values. Finally, age of onset of MJ use was positively correlated with frontal FA values and inversely related to trace. These data represent the first report of significant alterations in frontal white matter tracts associated with measures of impulsivity in chronic MJ smokers. Early MJ use may result in reduced FA and increased diffusivity, which may be associated with increased impulsivity, and ultimately contribute to the initiation of MJ use or the inability to discontinue use. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Hydrogels from silk fibroin metastable solution: Formation and characterization from a biomaterial perspective

Silk fibroin (SF) hydrogels were obtained from the dialysis of a SF metastable solution. Temperature and calcium concentration in SF solution/hydrogel were measured, as critical variables for SF gelation phenomenon. Gelation time of SF solution was increased by decreasing the dialysis temperature, whereas the residual calcium concentration was higher when higher dialysis temperatures were applied. Hydrogels obtained at 20 °C were characterized after freeze-drying. SEM micrographs showed porous structures, of ca. 20 μm (in cross-sectional area) and 5 μm (on surface). XRD indicated the presence of a β-sheet structure that is formed during SF gelation. In hydrogel formation, SF molecules in solution are dehydrated and interact by intra and intermolecular hydrogen bonds, forming a stable hydrogel. DSC measurements showed the decomposition peak for SF at 290 °C, characteristic of SF β-sheet structure, which is in accordance with the XRD results and demonstrate its high thermal resistance. SF hydrogels were found not to be toxic to cells using in vitro cytotoxicity tests. Results indicate that silk fibroin hydrogels hold promise for use in the biomaterial field.     

Quantitative risk assessment for human salmonellosis through the consumption of pork sausage in Porto Alegre, Brazil

A quantitative microbiology risk assessment was conducted to evaluate the risk of Salmonella infection to consumers of fresh pork sausages prepared at barbecues in Porto Alegre, Brazil. For the analysis, a prevalence of 24.4% positive pork sausages with a level of contamination between 0.03 and 460 CFU g(-1) was assumed. Data related to frequency and habits of consumption were obtained by a questionnaire survey given to 424 people. A second-order Monte Carlo simulation separating the uncertain parameter of cooking time from the variable parameters was run. Of the people interviewed, 87.5% consumed pork sausage, and 85.4% ate it at barbecues. The average risk of salmonellosis per barbecue at a minimum cooking time of 15.6 min (worst-case scenario) was 6.24 × 10(-4), and the risk assessed per month was 1.61 × 10(-3). Cooking for 19 min would fully inactivate Salmonella in 99.9% of the cases. At this cooking time, the sausage reached a mean internal temperature of 75.7°C. The results of the quantitative microbiology risk assessment revealed that the consumption of fresh pork sausage is safe when cooking time is approximately 19 min, whereas undercooked pork sausage may represent a nonnegligible health risk for consumers.     

Application of β-Cyclodextrin/2-Nonanone Inclusion Complex as Active Agent to Design of Antimicrobial Packaging Films for Control of <Emphasis Type="Italic">Botrytis cinerea</Emphasis>

The aim of this study was to develop, characterize and evaluate in vitro the efficacy of active films, based on an inclusion complex formed by β-cyclodextrin, 2-nonanone and two polymer matrices (polylactic acid and low density polyethylene). The different films were characterized by scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), themogravimetric analysis (TGA), optical properties and antimicrobial activity against B. cinerea. The results showed important differences in the parameters evaluated where the level of agglomerates of additives was a key to explain these changes. Finally, microbiological analysis showed high effectiveness in reducing the Botrytis cinerea growth. The active films developed in this study were able to inhibit the growth of phytopathogenic fungus B. cinerea at different experimental conditions. The studied films have potential use for packaging fresh fruit susceptible to biological attack by this fungus.     

Self-preservation strategies during bacterial biomineralization with reference to hydrozincite and implications for fossilization of bacteria

The induction of mineralization by microbes has been widely demonstrated but whether induced biomineralization leads to distinct morphologies indicative of microbial involvement remains an open question. For calcium carbonate, evidence suggests that microbial induction enhances sphere formation, but the mechanisms involved and the role of microbial surfaces are unknown. Here, we describe hydrozincite biominerals from Sardinia, Italy, which apparently start life as smooth globules on cyanobacterial filaments, and evolve to spheroidal aggregates consisting of nanoplates. Complementary laboratory experiments suggest that organic compounds are critical to produce this morphology, possibly by inducing aggregation of nanoscopic crystals or nucleation within organic globules produced by metabolizing cells. These observations suggest that production of extracellular polymeric substances by microbes may constitute an effective mechanism to enhance formation of porous spheroids that minimize cell entombment while also maintaining metabolite exchange. However, the high porosity arising from aggregation-based crystal growth probably facilitates rapid oxidation of entombed cells, reducing their potential to be fossilized.     

Evaluation of Different Conditions of Contact for Caprolactam Migration from Multilayer Polyamide Films into Food Simulants

Caprolactam, the polyamide 6 (PA‐6) monomer, can migrate during food processing. At cooking temperatures, migration is accelerated and plastic components could degrade, giving off low molecular mass compounds, which can migrate into food. In this work, caprolactam migration from multilayer films containing PA‐6 for meat foodstuffs and cheese packaging was performed at contact conditions of 40°C/10 days and 100°C/30 min. The migration into water ranged from 0.89 to 1.22 mg/dm² and 0.92 to 1.21 mg/dm², into 3% acetic acid from 1.29 to 1.74 mg/dm² and 1.13 to 1.62 mg/dm² and into olive oil from 1.18 to 1.98 mg/dm² and 0.50 to 0.80 mg/dm² for films intended for meat foodstuffs for 10 days at 40°C and 30 min at 100°C, respectively. Among PA‐6 films used for cheese, caprolactam migration into water ranged from 0.17 to 0.91 mg/dm² and 0.74 to 1.04 mg/dm², into 3% acetic acid from 1.15 to 1.26 mg/dm² and 1.11 to 1.37 mg/dm² and into olive oil from 0.23 to 0.83 mg/dm² and 0.37 to 0.56 mg/dm² for 10 days at 40°C and 30 min at 100°C, respectively. Caprolactam migration evaluation into water and 3% acetic acid at 100°C/30 min could replace the need to apply the test at 40°C/10 days, since similar results were obtained under both conditions. In the case of PA‐6 for meat foodstuffs, caprolactam migration into olive oil was highly affected by different conditions of contact, showing values two to three times higher at 40°C/10 days than at 100°C/30 min. For cheese films, caprolactam migration into olive oil was higher at 40°C for 10 days. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydrolysis of soya milk oligosaccharides by Bifidobacterium longum CRL 849

 The reduction of soya milk oligosaccharides by Bifidobacterium longum CRL 849 was studied. The utilization of stachyose was concomitant with the use of sucrose. Maximum hydrolysis of stachyose (49.3%) occurred during the first 7 h of incubation at 37  °C, while a 79.3% decrease in the concentration of sucrose was observed after 9 h. No raffinose was detected after hydrolysis of the stachyose. Cell population decreased after 8 h of incubation because of the low pH attained (pH 4.7). l(+)-Lactate concentration was higher than acetate (molar ratio 6.7 : 1) at 6 h followed by a slow increase in acetate formation. Ethanol was detected in small amounts at the end of the incubation time (24 h). Received: 29 December 1997     

An Online Measure of Thought Suppression.

An online thought-suppression paradigm was developed to test predictions of ironic process theory. Participants concentrated on or suppressed a particular semantic category. Semantic activation was indexed by the latency to name words from the category. In Experiments 1 and 2, an analog intrusion was introduced while participants were trying to suppress the information. Results consistent with ironic process theory were observed using words with polar opposites in Experiment 1 and words without polar opposites in Experiment 2. To determine whether these effects were dependent on the analog intrusion, Experiment 3 replicated Experiment 1 without the intrusion. Concentration generated semantic activation, but suppression exacerbated this activation. The data imply that hyperaccessibility results from efforts to suppress, whereas the processes of thought suppression identified by ironic process theory require the presence of material inconsistent with a desired cognitive state. (PsycINFO Database Record (c) 2010 APA, all rights reserved)