Novel Redox-Dependent Esterase Activity (EC 3.1.1.2) for DJ-1: Implications for Parkinson’s Disease

Mutations the in human DJ-1 (hDJ-1) gene are associated with early-onset autosomal recessive forms of Parkinson’s disease (PD). hDJ-1/parkinsonism associated deglycase (PARK7) is a cytoprotective multi-functional protein that contains a conserved cysteine-protease domain. Given that cysteine-proteases can act on both amide and ester substrates, we surmised that hDJ-1 possessed cysteine-mediated esterase activity. To test this hypothesis, hDJ-1 was overexpressed, purified and tested for activity towards 4-nitrophenyl acetate (pNPA) as µmol of pNPA hydrolyzed/min/mg·protein (U/mg protein). hDJ-1 showed maximum reaction velocity esterase activity (V_max = 235.10 ± 12.00 U/mg protein), with a sigmoidal fit (S_0.5 = 0.55 ± 0.040 mM) and apparent positive cooperativity (Hill coefficient of 2.05 ± 0.28). A PD-associated mutant of DJ-1 (M26I) lacked activity. Unlike its protease activity which is inactivated by reactive oxygen species (ROS), esterase activity of hDJ-1 is enhanced upon exposure to low concentrations of hydrogen peroxide (<10 µM) and plateaus at elevated concentrations (>100 µM) suggesting that its activity is resistant to oxidative stress. Esterase activity of DJ-1 requires oxidation of catalytic cysteines, as chemically protecting cysteines blocked its activity whereas an oxido-mimetic mutant of DJ-1 (C106D) exhibited robust esterase activity. Molecular docking studies suggest that C106 and L126 within its catalytic site interact with esterase substrates. Overall, our data show that hDJ-1 contains intrinsic redox-sensitive esterase activity that is abolished in a PD-associated mutant form of the hDJ-1 protein.     

Pentadecane functionalized graphite oxide sheets as a tool for the preparation of electrical conductive polyethylene/graphite oxide composites

Covalent functionalization of pentadecane-decorated thermally reduced graphite oxide (GO) sheets has been studied as a tool for the preparation of polyethylene/GO composites exhibiting rheological and electrical percolation thresholds. It was accomplished through pentadecane based radical addition onto unsaturated bonds located on the GO sheets' surface using dicumyl peroxide as hydrogen abstractor. This chemical functionalization influences the affinity of the formed pentadecane grafted GO sheets for various solvents. Then, the compounding of the composites pentadecane grafted GO/PE was performed at a processing temperature of 140 °C with 25, 20, 15, 10, 8 and 5 wt% loadings. Rheological and electrical percolation thresholds were found between 10 and 15 wt% for polyethylene/pentadecane functionalized graphene oxide composites while the composite graphite/PE at the same loading percentage did not reach any percolation threshold.     

Defect structure evolution and electrical properties of BaTiO3-based ferroelectric ceramics

Relaxor perovskite ferroelectric 0.1Bi(Zn_1/2Zr_1/2)O₃-0.9BaTiO₃(0.1BZZ-0.9BT) ceramics were successfully prepared, whose powders synthesized by the sol-gel process, with average grain size about 1.29 μm. 1.75 J/cm³ discharge energy density and good dielectric stability were obtained over a wide temperature range from 25°C to 140°C. The pulse discharge capability of 0.1BZZ-0.9BT ceramics was tested under different electric fields. The discharge time was 2.13 μs, which proved its ability to charge and discharge quickly. Complex impedance analysis and thermally stimulated depolarization current tests were applied to investigate the defect types and activation of 0.1BZZ-0.9BT ceramics. The evolution process of composite defects and oxygen vacancies profoundly affects the dielectric temperature stability of 0.1BZZ-0.9BT ceramics’ energy storage property.     

The Role of Testosterone in the Elderly: What Do We Know?

Testosterone is the most important hormone in male health. Aging is characterized by testosterone deficiency due to decreasing testosterone levels associated with low testicular production, genetic factors, adiposity, and illness. Low testosterone levels in men are associated with sexual dysfunction (low sexual desire, erectile dysfunction), reduced skeletal muscle mass and strength, decreased bone mineral density, increased cardiovascular risk and alterations of the glycometabolic profile. Testosterone replacement therapy (TRT) shows several therapeutic effects while maintaining a good safety profile in hypogonadal men. TRT restores normal levels of serum testosterone in men, increasing libido and energy level and producing beneficial effects on bone density, strength and muscle as well as yielding cardioprotective effects. Nevertheless, TRT could be contraindicated in men with untreated prostate cancer, although poor findings are reported in the literature. In addition, different potential side effects, such as polycythemia, cardiac events and obstructive sleep apnea, should be monitored. The aim of our review is to provide an updated background regarding the pros and cons of TRT, evaluating its role and its clinical applicability in different domains.     

Dietary effects on growth,plasma lipid and tissues of rats fed with non‐conventional oil of Telfairia occidentalis

The nutritional value of Telfairia occidentalis seed and seed oil available in local market was studied in rats. The average values of the proximate analysis on dry matter basis were 203 g kg^?1 crude protein, 536.3 g kg^?1 fat, 39 g kg^?1 ash, 95 g kg^?1 crude fibre and 43.7 g kg^?1 carbohydrate, while the moisture content was 75 g kg^?1. The mineral analyses showed that T occidentalis seeds contain potassium (3280 mg kg^?1), sodium (1230 mg kg^?1), magnesium (60.8 mg kg^?1), calcium (60.8 mg kg^?1) and iron (13.0 mg kg^?1). The oil extracted from the seed sample showed physicochemical properties that suggest its suitability for edible and industrial uses. The oil contained high levels of unsaturated fatty acids, oleic and linoleic, which accounted for 63.22% of total fatty acids recovered, while palmitic acid (27.4% of the oil by weight) was the most prevalent saturated fatty acid in the oil. No trace of eleostearic acid was detected in the oil. The effect on physical appearance, weight gain, organ weight, tissue and plasma cholesterol and triacylglycerol levels was determined in rats fed a diet containing 5% T occidentalis oil. These were compared with those of rats fed a control diet (0% T occidentalis oil) over an 8 week study period. Weekly monitoring of the rats showed good physical appearance and steady weight increase. The test rats were not anaemic and no mortality was recorded. While there was a significantly higher (p < 0.05) level of cholesterol in the heart of test rats compared with the control, there was a significantly lower (p < 0.05) plasma cholesterol level, suggesting that T occidentalis seed oil can be used to lower plasma levels of cholesterol. Histological examination of the sections of the heart, liver, kidney and spleen of the test rats revealed varying degrees of pathology. These include artherosclerotic changes in the walls of vasa vasori and lymphatics in the heart and hyaline degeneration of myofibrils, fatty infiltration of hepatocytes, and glomerular and tubular degeneration in the kidneys. These lesions may have been due to the effect of fatty acids, especially erucic acid, in the seed oil, which at 1.24% (less that the 5% conventional allowable limit for edible oils) may be intolerable for rats and may be unsuitable for human consumption. The seed oil may be used for industrial purposes such as soap making, lubrication and cosmetics for which it is well suited. Copyright © 2004 Society of Chemical Industry     

In-House Validation and Comparison of Two Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>) Taxon-Specific Real-Time PCR Methods for GMO Quantification Supported by Droplet Digital PCR

Common wheat is one of the most important staple food crops worldwide. However, unlike other important staple crops such as maize or soybean, genetically modified (GM) wheat is not yet present in the global food market. Nonetheless, in the recent past, the adventitious presence of GM glyphosate-tolerant volunteers was reported in open wheat fields in the USA. The European Union Reference Laboratory for GM Food and Feed (EURL-GMFF) was therefore called to develop a strategy to detect such unauthorised GM wheat in wheat samples by using both taxon-specific and screening tests. Two candidate common wheat taxon-specific real-time PCR methods were suggested, one targeting ssII-D gene coding for starch synthase and the other targeting waxy-D1 gene, coding for granule-bound starch synthase. In the present study, the two above-mentioned real-time PCR taxon-specific methods were in-house verified and compared, proposing droplet digital PCR (ddPCR) as a new tool for supporting the application of the European Network of GMO Laboratories (ENGL) established method performance criteria. Preliminary performance data of waxy-D1 and ssII-D methods in ddPCR format are shown too to give a contribution to the bridging process from the consolidated to the emerging quantitative PCR methodology.     

Polysilazane derived micro/nano Si3N4/SiC composites

The pyrolised polysilazanes poly(hydridomethyl)silazane NCP 200 and poly(urea)silazane CERASET derived Si–C–N amorphous powders were used for preparation of micro/nano Si₃N₄/SiC composites by hot pressing. Y₂O₃–Al₂O₃ and Y₂O₃–Yb₂O₃ were used, as sintering aids. The resulting ceramic composites of all compositions were dense and polycrystalline with fine microstructure of average grain size <1 μm of both Si₃N₄ and SiC phases. The fine SiC nano-inclusions were identified within the Si₃N₄ micrograins. Phase composition of both composites consist of , β modifications of Si₃N₄ and SiC. High weight loss was observed during the hot pressing cycle, 12 and 19 wt.% for NCP 200 and CERASET precursors, respectively. The fracture toughness of both nanocomposites (NCP 2000 and CERASET derived) was not different. Indentation method measured values are from 5 to 6 MPa m^1/2, with respect to the sintering additive system. Fracture toughness is slightly sensitive to the SiC content of the nanocomposite. Hardness increases with the content of SiC in the nanocomposite. The highest hardness was achieved for pyrolysed CERASET precursor with 2 wt.% Y₂O₃ and 6 wt.% Yb₂O₃, HV 23 GPa. This is a consequence of the highest SiC content as well as the chemical composition of additives.     

Extraction of oleic acid from soybean oil and jojoba oil-phase diagrams

Formamide,N-methylformamide,N-dimethylformamide, dimethylsulfoxide, 1,2-butanediol, and 2-butane-1,4-diol were considered as potential extractants of fatty acids from soybean and jojoba oils. Ternary liquid-liquid phase diagrams at 298.15 K, distribution, and selectivity coefficients of oleic acid are reported. Of the investigated solvents, onlyN-methylformamide and 1,2-butanediol have desirable extraction characteristics.     

Generation of spatio-temporal concentration profiles for cell culture systems: A case study in ammonia

Cellular behavior is influenced by micro-concentration gradients existing in their immediate spatio-environment. A practical real-time measurement system, composed of miniaturized long-lasting sensors placed within a two-dimensional bioreactor and a 32-channel data acquisition system for ammonia, is presented in this paper aiming to generate the spatio-temporal ammonia concentration profiles for the whole culture process. Our results demonstrate the feasibility of the system and its applicability in elucidating the cell growth micro-environment within a bioreactor, which can potentially facilitate the intelligent control of ammonia levels in cell culture systems. The presented system is flexible enough to interface other sensors for generating their spatio-temporal profiles of the sensed cell culture parameters.