Inhibition of sickle beta-chain (betaS)-dependent polymerization by nonhuman alpha-chains. A superinhibitory mouse-horse chimeric alpha-chain

Horse alpha-chain inhibits sickle beta-chain-dependent polymerization; however, its inhibitory potential is not as high as that of mouse alpha-chain. Horse alpha-(1-30) and alpha-(31-141) segments make, respectively, minor and major contributions to the inhibitory potential of horse alpha-chain. The sum of the inhibitory potential of the two segments does not account for the inhibitory potential of the full-length horse alpha-chain. Although the polymerization inhibitory potential of horse alpha-chain is lower than mouse alpha-chain, the inhibitory potential of horse alpha-(31-141) is comparable to that of mouse alpha-(31-141). When mouse alpha-(1-30) is stitched to horse alpha-(31-141), the product is a chimeric alpha-chain with an inhibitory potential greater than mouse alpha-chain. In contrast, the stitching of horse alpha-(1-30) with mouse alpha-(31-141) had no additional inhibitory potential. Molecular modeling studies of HbS containing the mouse-horse chimeric alpha-chain indicate altered side-chain interactions at the alpha1beta1 interface when compared with HbS. In addition, the AB/GH corner perturbations facilitate a different stereochemistry for the interaction of the epsilon-amino group of Lys-16(alpha) with the beta-carboxyl group of Asp-116(alpha), resulting in a decrease in the accessibility of the side chain of Lys-16(alpha) to the solvent. Based on molecular modeling, we speculate that these perturbations by themselves, or in synergy with the altered conformational aspects of the alpha1beta1 interactions, represent the molecular basis of the superinhibitory potential of the mouse-horse chimeric alpha-chains.     

Carcinogenic polycyclic aromatic hydrocarbons increase intracellular Ca2+ and cell proliferation in primary human mammary epithelial cells

A method was developed to determine in eggs 2 components [4,6-dimethyl-2-hydroxypyrimidine and 1,3-bis(4-nitrophenyl)urea] of the anticoccidial drug nicarbazin, used to treat poultry. Samples were extracted with acetonitrile, and the extracts were washed with hexane and evaporated to dryness before analysis by liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization. By switching from positive to negative ion monitoring and using gradient elution, both components were measured within one run. The limit of quantitation of the assay was 10 ng/g for each component. The results of a preliminary feeding trial in which chickens were fed contamination levels of the drug are also reported.     

Predicting the Academic Performance of Construction Engineering Students by Teaching and Learning Approaches: Case Study

There are various teaching approaches that instructors may adopt in their quest to teach effectively, and students can choose from a range of learning approaches to help them achieve good grades. This study investigates the effectiveness of personal learning approaches adopted by undergraduates and the teaching approaches employed by instructors in the context of construction engineering courses. The research questions are as follows. (1)?What are the students’ learning approaches that lead to better academic achievement? (2)?What are the instructors’ teaching approaches that give rise to better academic achievement? The study also aims to construct a model to predict a student’s likely academic performance in a construction engineering course. The research design is a self-administered survey. Using a structured questionnaire consisting of questions relating to learning strategies and teaching approaches, data were collected from undergraduates who majored in construction engineering. Statistical analyses undertaken include Pearson correlation and multiple linear regression modeling. Pearson correlation analysis shows that both the Growing Teaching approach and the students’ Achieving Motive learning approach are significantly correlated with academic performance. A robust grade prediction model was developed, whereby a student’s grade in a construction engineering course may be predicted using one teaching approach (Growing Teaching) and three learning approaches (Achieving Motive, Achieving Strategy, and Deep Motive). To help students obtain higher grades in a construction engineering course, instructors should adopt the Growing Teaching approach, and students should adopt the Achieving Motive learning approach. Because students who adopt the Deep Motive learning approach are penalized with lower grades, it is recommended that instructors modify their teaching methods and approaches so that students do not take shortcuts in their learning without deeper regard for higher-order learning outcomes.     

Effect of zinc oxide on the viscosity and adhesion property of epoxidized natural rubber/acrylonitrile‐butadiene rubber‐based pressure‐sensitive adhesives

Viscosity, loop tack, peel strength, and shear strength of epoxidized natural rubber (ENR 50)/acrylonitrile‐butadiene rubber (NBR)–based pressure‐sensitive adhesive were studied in the presence of zinc oxide. The zinc oxide concentration was varied from 10 to 50 parts by weight per hundred parts of rubber (phr). Coumarone–indene resin with loading of 40 phr was chosen as the tackifier resin. Toluene and polyethylene terephthalate were used as the solvent and coating substrate, respectively, throughout the experiment. The adhesive was coated on the substrate by using a SHEEN hand coater. Viscosity of the adhesive was determined by a Brookfield Viscometer, whereas the loop tack, peel strength, and shear strength were measured by a Lloyd Adhesion Tester operating at 30 cm/min. Results indicate that viscosity increases with zinc oxide concentration owing to the concentration effect. Loop tack and peel strength pass through a maximum value at 20 phr of zinc oxide concentration. This observation is associated with the effect of varying degrees of wettability of the adhesive on the substrate. Shear strength, however, increases steadily with increasing zinc oxide loading owing to the steady increase in cohesive strength. In all cases, the adhesion properties of adhesives increase with increasing coating thicknesses. J. VINYL ADDIT. TECHNOL., 22:410–414, 2016. © 2015 Society of Plastics Engineers     

XR-C1, a new CHO cell mutant which is defective in DNA-PKcs, is impaired in both V(D)J coding and signal joint formation

DNA-dependent protein kinase (DNA-PK) plays an important role in DNA double-strand break (DSB) repair and V(D)J recombination. We have isolated a new X-ray-sensitive CHO cell line, XR-C1, which is impaired in DSB repair and which was assigned to complementation group 7, the group that is defective in the XRCC7 / SCID ( Prkdc ) gene encoding the catalytic subunit of DNA-PK (DNA-PKcs). Consistent with this complementation analysis, XR-C1 cells lackeddetectable DNA-PKcs protein, did not display DNA-PK catalytic activity and were complemented by the introduction of a single human chromosome 8 (providing the Prkdc gene). The impact of the XR-C1 mutation on V(D)J recombination was quite different from that found in most rodent cells defective in DNA-PKcs, which are preferentially blocked in coding joint formation, whereas XR-C1 cells were defective in forming both coding and signal joints. These results suggest that DNA-PKcs is required for both coding and signal joint formation during V(D)J recombination and that the XR-C1 mutant cell line may prove to be a useful tool in understanding this pathway.     

Toxicity of the styrene metabolite, phenylglyoxylic acid, in rats after three months' oral dosing

Male Wistar rats were dosed with 0, 1250, 3750 or 5000 mg/l of phenylglyoxylic acid (PGA) (CAS no. 611-73-4) in the drinking water ad libitum for 3 months. During the entire treatment period, there were no gross signs of toxicity related to PGA. No changes in neurobehavior were found after using a functional observational battery or radial arm maze. An increased relative kidney weight was seen in the highest dose-group (Controls: 0.504 +/- 0.031 g/100 g b.wt.; 5000 mg PGA/l: 0.579 +/- 0.033 g/100 g b.wt.; p<0.01). No other organ weights were affected. Histopathology revealed no change in kidney structure. No changes in clinical biochemistry. In the highest dose-group three animals out of ten showed reduction in peripheral nerve myelin sheath thickness. No such changes were seen in the control group. The study revealed no changes in auditory brain stem response but minor changes in electroretinography. The noradrenaline (NA) concentration decreased in pons and thalamus whereas it increased in medulla oblongata and whole brain. The dopamine (DA) concentration increased in cerebellum, hippocampus, pons, and whole brain. The most marked DA increase was seen in hippocampus (Controls: 0.56 +/- 0.10 nmol/g tissue; 5000 mg/l: 1.04 +/- 0.11 nmol/g tissue; p<0.001). The 5-hydroxytryptamine (5-HT) concentration decreased in cerebellum, cerebral cortex, hippocampus, and medulla oblongata, whereas it increased in thalamus. The yield of synaptosomal protein, synaptosomal NA, DA, and 5-HT concentrations, and DA uptake rate were not affected. When dosed males were mated with naive females, there were no differences between groups in the pregnancy rate, number of corpora luteae, implantations, live or dead fetuses, resorptions, preimplantation loss, or postimplantation loss. It is concluded that a part of the effects on kidney, peripheral nerves, and vision, which have previously been reported after exposure to styrene, might be induced by the styrene metabolite, PGA. If PGA has ototoxic effects in rats, the dosing in the present study is not sufficient to induce the necessary ototoxic concentration in blood. Alternatively, the ototoxicity of styrene, like toluene, may be caused the parent compound itself and not by a metabolite like PGA.