Neuroprotective Role of Liver Growth Factor “LGF” in an Experimental Model of Cerebellar Ataxia

Cerebellar ataxias (CA) comprise a heterogeneous group of neurodegenerative diseases characterized by a lack of motor coordination. They are caused by disturbances in the cerebellum and its associated circuitries, so the major therapeutic goal is to correct cerebellar dysfunction. Neurotrophic factors enhance the survival and differentiation of selected types of neurons. Liver growth factor (LGF) is a hepatic mitogen that shows biological activity in neuroregenerative therapies. We investigate the potential therapeutic activity of LGF in the 3-acetylpiridine (3-AP) rat model of CA. This model of CA consists in the lesion of the inferior olive-induced by 3-AP (40 mg/kg). Ataxic rats were treated with 5 µg/rat LGF or vehicle during 3 weeks, analyzing: (a) motor coordination by using the rota-rod test; and (b) the immunohistochemical and biochemical evolution of several parameters related with the olivo-cerebellar function. Motor coordination improved in 3-AP-lesioned rats that received LGF treatment. LGF up-regulated NeuN and Bcl-2 protein levels in the brainstem, and increased calbindin expression and the number of neurons receiving calbindin-positive projections in the cerebellum. LGF also reduced extracellular glutamate and GABA concentrations and microglia activation in the cerebellum. In view of these results, we propose LGF as a potential therapeutic agent in cerebellar ataxias.     

Complementary Functions of Plant AP Endonucleases and AP Lyases during DNA Repair of Abasic Sites Arising from C:G Base Pairs

Abasic (apurinic/apyrimidinic, AP) sites are ubiquitous DNA lesions arising from spontaneous base loss and excision of damaged bases. They may be processed either by AP endonucleases or AP lyases, but the relative roles of these two classes of enzymes are not well understood. We hypothesized that endonucleases and lyases may be differentially influenced by the sequence surrounding the AP site and/or the identity of the orphan base. To test this idea, we analysed the activity of plant and human AP endonucleases and AP lyases on DNA substrates containing an abasic site opposite either G or C in different sequence contexts. AP sites opposite G are common intermediates during the repair of deaminated cytosines, whereas AP sites opposite C frequently arise from oxidized guanines. We found that the major Arabidopsis AP endonuclease (ARP) exhibited a higher efficiency on AP sites opposite G. In contrast, the main plant AP lyase (FPG) showed a greater preference for AP sites opposite C. The major human AP endonuclease (APE1) preferred G as the orphan base, but only in some sequence contexts. We propose that plant AP endonucleases and AP lyases play complementary DNA repair functions on abasic sites arising at C:G pairs, neutralizing the potential mutagenic consequences of C deamination and G oxidation, respectively.     

Bimodal polypropylene through binary metallocene catalytic systems: comparison between hybrid and mixed heterogeneous catalysts

Polypropylene with wider or bimodal molecular weight distribution is required for numerous applications since low molecular weight chains improve processability and high molecular weight fraction is required to get good mechanical properties. There are several routes to achieve a bimodal resin but the use of a binary catalytic system seems to be the most attractive, particularly with metallocenes combination. From a previous work two metallocenes were selected because they lead to polypropylenes with average molecular weights that differ in one order of magnitude. Two types of binary systems have been investigated, hybrid catalysts (two metallocenes loaded on the same support) and physical mixtures (two independent supported metallocenes that are introduced to the reactor and start the polymerization together), using different ratios, i.e., 25–75, 50–50, 75–25, at three reaction temperatures, i.e., 30, 50 and 70 °C. Most of the binary catalytic systems lead to bimodal molecular weight distributions. Polypropylenes produced by mixed catalysts are greatly influenced by the most active catalyst, while in PP coming from hybrid catalysts, as there is a strong interaction between both metallocenes, each one contributes according to its presence in the hybrid catalyst. Therefore, properties of obtained bimodal polypropylenes are quite influenced by the ratio between both metallocenes.     

Forest‐based resources as fillers in biobased polyurethane foams

Six fillers from forestry wastes (wood, bark, cones and needles from young pine trees, kraft lignin, and recycled paper sludge from industry wastes) were incorporated into polyurethane (PU)‐based foams prepared via free‐rise pouring method. Variable filler contents (1, 5, and 10 wt %) and NCO/OH ratios (0.6, 0.9, and 1.2) were investigated. A simple mixture (1:3) of castor oil and crude glycerin (byproduct from biodiesel production) was used as biobased polyol. The foam composites were investigated through spectroscopy, morphological, mechanical, and hygroscopic analyses. The addition of fillers decreased water uptake and yielded rigid PU systems with more homogenous cell structure. The 1% and 5% reinforcement wood were the most effective among the studied compositions, with better mechanical and hygroscopic performance, probably due the higher compatibility of the wood with the PU system, which promote urethanic bonds between filler and isocyanate, as indicated by wet chemical results and micrographs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45684.     

The effect of microstructure on the slow crack growth resistance in polyethylene resins

The slow crack growth (SCG) in high density polyethylene (HDPE) is a phenomenon dominated by crazing. In this work, the crazing was analyzed from a microstructural point of view. PENT (Pennsylvania Edge Notched Tensile) test was chosen to study the evolution of the craze with time for different resins from PE‐80 up to PE‐100 grades. Two different geometries, the standard and an alternative named CDNT (Circumferentially Deep Notched Tensile), were employed. Failure times were correlated with intercrystalline parameters like tie molecules and the molecular weight between entanglements. Experimental results showed good correlations using both direct SCG test (standard PENT and CDNT geometries). Finally, the strain hardening modulus was correlated with PENT failure times. The results disclosed an outstanding correlation for several polyethylene grades from blow molding up to PE‐80, PE‐100, and higher resistant to crack grades. These results permitted an easy‐classifying and ranking method as much to the old polyethylene grades as to the new generation of HDPE resins with a very high SCG resistance. POLYM. ENG. SCI., 55:1018–1023, 2015. © 2014 Society of Plastics Engineers     

Lipids from Wastewater-Activated Sludge Cultivated on Acetic Acid as Potential Alternatives to High-Value Oils and Fats

This study focuses on new interpretations of the published literature by statistically evaluating the potential of microbial lipids from activated sludge (AS) as alternatives to high-value oils and fats. There are two data analysis stages involved in this study after compilation and organization of fatty acid profiles from the literature databases: (1) comparison of fatty acid profiles of the cultivated AS lipids with that of oils and fats found in the literature databases, and (2) hierarchical cluster analysis of the fatty acids of the combined dataset of literature oils and fats, and the AS lipids. Results show that fatty acid profiles of lipids from cultivated AS were similar to the fatty acid profiles of some oils and fats of plant, animal, single-microbial cultures, and algal origins; hence, lipids from AS could be potential alternatives to specialty oils and fats. The cultivation conditions of AS during lipid content enhancement may influence lipid application.     

Characterization of a Modular,Scalable Millistructured Plate Reactor

Micro‐ and millistructured reactors offer significant advantages compared to conventional reactors, e.g., in terms of heat and mass transfer as well as safety. For the substitution of larger batch reactors by continuously operated millireactors a comprehensive reactor characterization is required. The heat transfer and hydrodynamics of the millistructured plate reactor PR37 are studied. The meandering of the process channel and its periodically changing cross‐sectional area increase the heat transfer significantly and lead to a dependency of the heat transfer coefficient on the Reynolds and Prandtl number that is not found in straight channels at Reynolds numbers below 2300.