Two-state irreversible thermal denaturation of Euphorbia characias latex amine oxidase

Thermal denaturation of Euphorbia latex amine oxidase (ELAO) has been studied by enzymatic activity, circular dichroism and differential scanning calorimetry. Thermal denaturation of ELAO is shown to be an irreversible process. Checking the validity of two-state it really describes satisfactorily the thermal denaturation of ELAO. Based on this model we obtain the activation energy, parameter T(*) (the absolute temperature at which the rate constant of denaturation is equal to 1 min(-1)), and total enthalpy of ELAO denaturation. HPLC experiments show that the thermal denatured enzyme conserves its dimeric state. The N(2)-->kD(2) model for thermal denaturation of ELAO is proposed: where N(2) and D(2) are the native and denatured dimer, respectively.     

Chitosan–Sodium Lauryl Sulfate Nanoparticles as a Carrier System for the In Vivo Delivery of Oral Insulin

The present work explores the possibility of formulating an oral insulin delivery system using nanoparticulate complexes made from the interaction between biodegradable, natural polymer called chitosan and anionic surfactant called sodium lauryl sulfate (SLS). The interaction between chitosan and SLS was confirmed by Fourier transform infrared spectroscopy. The nanoparticles were prepared by simple gelation method under aqueous-based conditions. The nanoparticles were stable in simulated gastric fluids and could protect the encapsulated insulin from the GIT enzymes. Additionally, the in vivo results clearly indicated that the insulin-loaded nanoparticles could effectively reduce the blood glucose level in a diabetic rat model. However, additional formulation modifications are required to improve insulin oral bioavailability.KEY WORDS: chitosan, insulin, nanoparticles, oral delivery system, sodium lauryl sulfate     

Maternal embryonic leucine zipper kinase (MELK) regulates multipotent neural progenitor proliferation

Maternal embryonic leucine zipper kinase (MELK) was previously identified in a screen for genes enriched in neural progenitors. Here, we demonstrate expression of MELK by progenitors in developing and adult brain and that MELK serves as a marker for self-renewing multipotent neural progenitors (MNPs) in cultures derived from the developing forebrain and in transgenic mice. Overexpression of MELK enhances (whereas knockdown diminishes) the ability to generate neurospheres from MNPs, indicating a function in self-renewal. MELK down-regulation disrupts the production of neurogenic MNP from glial fibrillary acidic protein (GFAP)-positive progenitors in vitro. MELK expression in MNP is cell cycle regulated and inhibition of MELK expression down-regulates the expression of B-myb, which is shown to also mediate MNP proliferation. These findings indicate that MELK is necessary for proliferation of embryonic and postnatal MNP and suggest that it regulates the transition from GFAP-expressing progenitors to rapid amplifying progenitors in the postnatal brain.     

The Correlation of RNase A Enzymatic Activity with the Changes in the Distance between Nε2-His12 and Nδ1-His119 Upon Addition of Stabilizing and Destabilizing Salts

The effect of stabilizing and destabilizing salts on the catalytic behavior of ribonuclease A (RNase A) was investigated at pH 7.5 and 25°C, using spectrophotometric, viscometric and molecular dynamic methods. The changes in the distance between N_ε2 of His₁₂ and N_δ1 of His₁₁₉ at the catalytic center of RNase A upon the addition of sodium sulfate, sodium hydrogen sulfate and sodium thiocyanate were evaluated by molecular dynamic methods. The compactness and expansion in terms of Stokes radius of RNase A upon the addition of sulfate ions as kosmotropic salts, and thiocyanate ion as a chaotropic salt, were estimated by viscometric measurements. Enzyme activity was measured using cytidine 2′, 3′-cyclic monophosphate as a substrate. The results from the measurements of distances between N_ε2 of His₁₂ and N_δ1 of His₁₁₉ and Stokes radius suggest (i) that the presence of sulfate ions decreases the distance between the catalytic His residues and increases the globular compactness, and (ii) that there is an expansion of the enzyme surface as well as elongation of the catalytic center in the presence of thiocyanate ion. These findings are in agreement with activity measurements.     

An experiment on comb orientation by honey bees (Hymenoptera: Apidae) in traditional hives

The orientation of combs in traditional beehives is extremely important for obtaining a marketable honey product. However, the factors that could determine comb orientation in traditional hives and the possibilities of inducing honey bees, Apis mellifera (L.), to construct more desirable combs have not been investigated. The goal of this experiment was to determine whether guide marks in traditional hives can induce bees to build combs of a desired orientation. Thirty-two traditional hives of uniform dimensions were used in the experiment. In 24 hives, ridges were formed on the inner surfaces of the hives with fermented mud to obtain different orientations, circular, horizontal, and spiral, with eight replicates of each treatment. In the remaining eight control hives, the inner surface was left smooth. Thirty-two well-established honey bee colonies from other traditional hives were transferred to the prepared hives. The colonies were randomly assigned to the four treatment groups. The manner of comb construction in the donor and experimental hives was recorded. The results showed that 22 (91.66%) of the 24 colonies in the treated groups built combs along the ridges provided, whereas only 2 (8.33%) did not. Comb orientation was strongly associated with the type of guide marks provided. Moreover, of the 18 colonies that randomly fell to patterns different from those of their previous nests, 17 (94.4%) followed the guide marks provided, irrespective of the comb orientation type in their previous nest. Thus, comb orientation appears to be governed by the inner surface pattern of the nest cavity. The results suggest that even in fixed-comb hives, honey bees can be guided to build combs with orientations suitable to honey harvesting, without affecting the colonies.     

Decolorization of Fast red by metabolizing cells of <Emphasis Type="Italic">Oenococcus oeni</Emphasis> ML34

Three different azo dyes such as Fast red, metanil yellow and Fast orange were examined for their decolorization by O. oeni ML34. Fast red (FR) was decolorized by 68%, whereas the other dyes were removed by only about 30%. The effects of glucose addition, substrate (dye) concentration and environmental factors (temperature, pH) on decolorization were investigated by two-level factorial design. The statistical analyses revealed that glucose specifically increases the extent of FR decolorization. A glucose level of 5 g/l was the optimum concentration for removal of, FR reaching a decolorization percentage of up to 93%.     

Investigating the interaction of anticancer drug temsirolimus with human transferrin: Molecular docking and spectroscopic approach

In our present study, binding between an important anti renal cancer drug temsirolimus and human transferrin (hTF) was investigated employing spectroscopic and molecular docking approach. In the presence of temsirolimus, hyper chromaticity is observed in hTF in UV spectroscopy suggestive of complex formation between hTF and temsirolimus. Fluorescence spectroscopy revealed the occurrence of quenching in hTF in the presence of temsirolimus implying complex formation taking place between hTF and temsirolimus. Further, the mode of interaction between hTF and temsirolimus was revealed to be static by fluorescence quenching analysis at 3 different temperatures. Binding constant values obtained employing fluorescence spectroscopy depicts strong interaction between hTF and temsirolimus; temsirolimus binds to hTF at 298 K with a binding constant of .32 × 10⁴ M^?1 implying the strength of this interaction. The negative Gibbs free energy obtained through quenching experiments is evident of the fact that the binding is spontaneous. CD spectra of hTF also showed a downward shift in the presence of temsirolimus as compared with free hTF implying complex formation between hTF and temsirolimus. Molecular docking was performed with a view to find out which residues are key players in this interaction. The importance of our study stems from the fact it will provide an insight into binding pattern of commonly administered renal cancer drug with an important protein that plays a pivotal role in many physiological processes.     

Corrugation Architecture Enabled Ultraflexible Wafer‐Scale High‐Efficiency Monocrystalline Silicon Solar Cell

Advanced classes of modern application require new generation of versatile solar cells showcasing extreme mechanical resilience, large‐scale, low cost, and excellent power conversion efficiency. Conventional crystalline silicon‐based solar cells offer one of the most highly efficient power sources, but a key challenge remains to attain mechanical resilience while preserving electrical performance. A complementary metal oxide semiconductor‐based integration strategy where corrugation architecture enables ultraflexible and low‐cost solar cell modules from bulk monocrystalline large‐scale (127 × 127 cm²) silicon solar wafers with a 17% power conversion efficiency. This periodic corrugated array benefits from an interchangeable solar cell segmentation scheme which preserves the active silicon thickness of 240 µm and achieves flexibility via interdigitated back contacts. These cells can reversibly withstand high mechanical stress and can be deformed to zigzag and bifacial modules. These corrugation silicon‐based solar cells offer ultraflexibility with high stability over 1000 bending cycles including convex and concave bending to broaden the application spectrum. Finally, the smallest bending radius of curvature lower than 140 µm of the back contacts is shown that carries the solar cells segments.     

Associations of Spexin and cardiometabolic parameters among women with and without gestational diabetes mellitus

Spexin (SPX) is a novel biomarker abundantly expressed in several animal and human tissues implicated in food intake and glucose control, respectively. As new roles for SPX are emerging, the present study explored for the first time, the associations of SPX to several cardiometabolic indices and inflammatory markers in pregnant women, a demographic not yet investigated with respect to SPX. A total of 117 Saudi women subdivided to those with gestational diabetes mellitus (GDM) (N?=?63) and those without (N?=?54) were included in this cross-sectional study. Anthropometry, glycemic, lipid, vitamin D, adipocytokines and inflammatory markers were measured consecutively at baseline and after the 2nd and 3rd trimesters. Age- and BMI adjusted comparisons revealed that levels of SPX were not significantly different in pregnant women with and without GDM. In all subjects, circulating levels of SPX showed modest associations with glucose (R?=?0.18; p?=?.08) and HOMA β (R?=??0.19; p?=?.09) as well as significant positive associations with total cholesterol (R?=?0.25; p?=?.02), LDL-cholesterol (R?=?0.25; p?=?.02), 25(OH)D (R?=?0.22; p?=?.04), albumin (R?=?0.30; p?<?.01) and IL1β (R?=?0.41; p?<?.01). Stepwise regression analysis also suggested that IL1β, leptin and albumin were the significant predictors of SPX. In summary, SPX levels modestly affect glucose and insulin sensitivity in pregnant women but is not associated with GDM and obesity. The significant association of SPX to ILβ warrants further investigation as to the role of SPX in immune modulation.