Biochemical and Mutational Characterization of N-Succinyl-Amino Acid Racemase from Geobacillus stearothermophilus CECT49.

N-Succinyl-amino acid racemase (NSAAR), long referred to as N-acyl- or N-acetyl-amino acid racemase, is an enolase superfamily member whose biotechnological potential was discovered decades ago, due to its use in the industrial dynamic kinetic resolution methodology first known as “Acylase Process”. In previous works, an extended and enhanced substrate spectrum of the NSAAR from Geobacillus kaustophilus CECT4264 toward different N-substituted amino acids was reported. In this work, we describe the cloning, purification, and characterization of the NSAAR from Geobacillus stearothermophilus CECT49 (GstNSAAR). The enzyme has been extensively characterized, showing a higher preference toward N-formyl-amino acids than to N-acetyl-amino acids, thus confirming that the use of the former substrates is more appropriate for a biotechnological application of the enzyme. The enzyme showed an apparent thermal denaturation midpoint of 77.0 ± 0.1 °C and an apparent molecular mass of 184 ± 5 kDa, suggesting a tetrameric species. Optimal parameters for the enzyme activity were pH 8.0 and 55–65 °C, with Co2+ as the most effective cofactor. Mutagenesis and binding experiments confirmed K166, D191, E216, D241, and K265 as key residues in the activity of GstNSAAR, but not indispensable for substrate binding.pre-print784 K

Production of al foams using the SDP method: Processing parameters and introduction of a new sintering device

The processing of aluminum (Al) foams with maximum porosity of around 70 %, regular pore size and interconnected pores were successfully produced by means of the powder metallurgy method of Sintering Dissolution Process (SDP). The metal powder used for the present study was Al powder with 99.5 % of purity and diameters between 75 μ m and 200 μ m. The chosen Space Holder Particles (SHP) were spherical carbamide CH4N2O particles with diameters ranging from 1 to 2 mm. The optimum sinterization temperature was found at 620 °C, at this temperature, a number of necks between Al particles surfaces were observed; indicating a good cohesion between Al particles, while keeping the porous structure of the green compact. The level of porosity was dependent of the carbamide content and the voids formed within the Al particles after the sinterization process. The sample with 60 wt.% of carbamide showed the lowest yield stress value than those for the samples with 40 and 50 wt.%. The strain values significantly increased when the carbamide content increased from 40 to 60 wt.%. Finally, the results obtained from a new sintering device for producing metallic foams at temperatures below 900 °C are also discussed

Asociación entre las concentraciones circulantes de adipocitoquinas y las complicaciones microvasculares en pacientes con diabetes mellitus tipo 2: una revisión sistemática y un metanálisis de estudios transversales controlados

Background The adipocytokines leptin and adiponectin have been variously associated with diabetic microvascular complications. No comprehensive clinical data exist examining the association between adipocytokines and the presence of these complications. Methods This is a systematic review of cross-sectional studies comparing circulating adipocytokines in patients with type 2 diabetes mellitus (T2DM), with and without microvascular complications. Studies were retrieved from MEDLINE, EMBASE, Scopus and Cochrane databases. Study quality was evaluated using a modified Newcastle–Ottawa Scale. Meta-analysis was performed using an inverse-variance model, providing standardised mean differences (SMD) and 95% confidence intervals (CI). Heterogeneity was determined by I2 statistic. Results Amongst 554 identified studies, 28 were included in the review. Study quality range was 3.5–9 (maximum 11). Higher leptin levels were associated with microalbuminuria (SMD = 0.41; 95% CI = 0.14–0.67; n = 901; p = 0.0003), macroalbuminuria (SMD = 0.68; 95% CI = 0.30–1.06; n = 406; p = 0.0004), and neuropathy (SMD = 0.26; 95% CI = 0.07–0.44; n = 609; p = 0.008). Higher adiponectin levels were associated with microalbuminuria (SMD = 0.55; 95% CI = 0.29–0.81, n = 274; p < 0.001), macroalbuminuria (SMD = 1.37; 95% CI = 0.78–1.97, n = 246; p < 0.00001), neuropathy (SMD = 0.25; 95% CI = 0.14–0.36; n = 1516; p < 0.00001), and retinopathy (SMD = 0.38; 95% CI = 0.25–0.51; n = 1306; p < 0.00001). Meta-regression suggested no influence of body mass index and duration of diabetes on effect size, and a weak trend in terms of age on effect size. Discussion Our meta-analysis suggests leptin and adiponectin levels are higher in T2DM patients with microvascular complications. Studies were limited by cross-sectional design. Large prospective analyses are required to validate these findings

The Effect of Intercropping of Maize and Soybean on Microclimate

Part 1: GIS, GPS, RS and Precision FarmingInternational audienceIntercropping induces the diseases decreasing, and yield increasing, may partly due to the improvement of microclimate in fields. In order to understand the mechanism and efficiency of resource utilization in intercropping of maize (Zea mays) and soybean (Glycine max), a field experiment was conducted as factorial on the bases of randomized complete block design of three patterns with three replications. Three cropping patterns were maize monocropping (A), 2 rows maize and 2 rows soybean intercropping (C) and 2 rows maize and 4 rows soybean intercropping (D). Our studies showed that compared with monocropping, the temperature in intercropping was a little higher in the daytime, but in the nighttime, the contrary results were observed; the relative humidity in intercropping was lower in the daytime, but in the nighttime, the contrary results were observed; the light intensity in intercropping was markedly higher than that in monocropping. The yield components of maize in intercropping, including thousand kernel weight, yield per plant and leaf area were increased than that in monocropping. These results imply that microclimate variation of intercropping probably play important role to maize yield increasing