Amperometric detection of insulin at renewable sol-gel derived carbon ceramic electrode modified with nickel powder and potassium octacyanomolybdate(IV)

A renewable three-dimensional chemically modified carbon ceramic electrode (CCE) containing nickel powder and K4[Mo(CN)8] was constructed by sol-gel technique. The electrochemical properties and stability of modified electrode was evaluated by cyclic voltammetry in pH range 4-10. The redox couple of [Mo(CN)8] (4-/3-) was shown both as a solute in electrolyte solution and as a component of a carbon based conducting composite electrode. The apparent electron transfer rate constant (ks) and transfer coefficient (alpha) were determined by cyclic voltammetry and they were about 17.1 and 0.57 s(-1), respectively. The catalytic activity of the modified CCE toward insulin oxidation was investigated at pH range of 3-8 by cyclic votammetry. The modified electrode showed excellent electrocatalytic activity toward insulin electroxidation at physiological pH value. The modified electrode was used for insulin detection chronoamperometrically at pH 7. Under optimized condition in amperometry method, the concentration calibration range, detection limit and sensitivity were 0.5-500 nM, 0.45 nM and 6140 nA/microM, respectively. Flow injection amperometric determination of insulin at pH 7.4, at this modified electrode yielded a calibration curve with the following characteristics, linear dynamic range 100-500 pM; sensitivity 8.1 nA/nM and detection limit 40 pM (based on S/N = 3). The inherent stability at wide pH range, high sensitivity, low detection limit, low cost and ease of preparation are of advantageous of this insulin sensor. This sensor indicates great promise for monitory insulin in chromatographic effluents.     

Evaluation of the effectiveness of conventional insecticides against the cowpea weevil, Callosobruchus maculatus (Coleoptera: Bruchidae), on four different substrata surfaces

在害虫治理中,在消费或贮藏粮食加工产品的建筑设施或场所进行害虫防治需要将杀虫剂施用在各种基质表面上.为了测定不同基质表面上杀虫剂的药效,将四纹豆象Callosobruchus maculatus(F.)成虫接触田间推荐剂量的阿维菌素、溴氰菊酯和毒死蜱.结果表明:施用在玻璃、瓷砖、塑料和纸盘表面上,阿维菌素对四纹豆象成虫的致死率分别为63.33％,22.41％,12.9％和11.9％,而溴氰菊酯在这4种基质表面上对四纹豆象成虫的致死率分别为55％,44.2％,41.3％和37.4％.在所有基质表面上接触毒死蜱,四纹豆象成虫的死亡率均为100％.对数据进行的Probit分析表明,毒死蜱制剂在玻璃、瓷砖、塑料和纸盘上对四纹豆象成虫的LC50值分别为8.66,13.6,29 16和56.5 μg/mL,阿维菌素制剂的相应数值分别为119.4,446.2,774.2和836.4μg/mL,溴氰菊酯制剂的相应数值分别为1008,1131,1210和1336 μg/mL.据此推断,毒死蜱对四纹豆象的毒性最强,且在玻璃、瓷砖、塑料和纸盘表面上的毒性依次降低.     

Serum Mercury Level and Multiple Sclerosis

Exposure to heavy metals has been associated to a higher incidence of multiple sclerosis. In this work, we present a possible relationship between serum mercury levels and development of multiple sclerosis in Isfahan, the third largest city in Iran. Seventy-four patients affected by multiple sclerosis were retrieved from multiple sclerosis (MS) clinic in Isfahan, Iran. By matching sex and age, 74 healthy volunteers were chosen as control group. Blood samples were collected and serum mercury content was determined. Serum mercury level in MS patients was significantly higher than controls (9.6 ± 10.17 vs. 5.7 ± 8.6, P = 0.037). Concerning all MS patients, serum mercury value was significantly higher than the mercury concentration founded in control subjects {odd ratio: 2.39 (CI, 1.96–2.94), P = 0.00}. Serum mercury level is higher in MS patients with odd ratio equal to 2.39 compared with healthy individuals. It may reveal that high mercury levels in serum might help MS development in susceptible individuals. More studies with larger sample size are needed to confirm this hypothesis.     

Binding of divalent metal ions to calcium-free peroxidase: thermodynamic and kinetic studies

Thermodynamics of binding of divalent metal ions including Ca(2+) , Mg(2+) , Ba(2+) , and Cd(2+) to Ca-free horseradish peroxidase (HRP) enzyme was investigated using UV/VIS spectrophotometry and molecular-mechanic (MM) calculations. According to the obtained binding and thermodynamic parameters, trend of the relative binding affinities of these divalent metal cations was found to be: Ca(2+) >Cd(2+) >Mg(2+) >Ba(2+) . Binding analysis based on Scatchard and Hill models showed positive cooperativity effect between the two distal and proximal binding sites. Furthermore, kinetics of binding and reconstitution process was examined (using relaxation-time method) for binding of Ca(2+) (as the typical metal ion) to Ca-free HRP, which was found a second-order type having a two-step mechanism involving fast formation of Ca-free HRP/1?Ca(2+) as the kinetic intermediate in step 1. Finally, by means of MM calculations, the comparative stability energies were evaluated for binding of M(2+) metal cations to Ca-free HRP. Based on MM calculations, preferential binding of Ca(2+) ion was occurred on distal and proximal binding sites of Ca-free HRP associated with higher stability energies (E(total) ). Indeed, among the divalent metal ions, Ca(2+) with the highest binding affinity (maximum value of K(bin) and minimum value of ΔG$\rm{{_{bin}^{0}}}$), maximum value of exothermic binding enthalpy, and stability energies stabilizes the HRP structure along with an optimized catalytic activity.     

Homology Modeling and Functional Characterization of PR-1a Protein of Hordeum vulgare subsp. Vulgare

Pathogenesis-related protein 1a of Hordeum vulgare subsp. Vulgare (HvPR-1a) is induced by various pathogens and stress related factors. It plays important roles in plant defense system. Since the discovery of HvPR-1a a great deal of research has been focused on its isolation and characterization. However, three dimensional structure of HvPR-1a is still unknown. 3D structure can be used for determining protein function, and identifying novel protein folds and potential targets for regulation. The protein model was developed using MODELLER 9v10. Physicochemical characterization and functional annotation of the model carried out with Expasy''s ProtParam server and three different conserved domain finding programs including InterProScan, Proteins Families Database (Pfam), and NCBI Conserved Domains Database (NCBI-CDD). Applying validation programs revealed that the model has good quality and the RMSD value is 0.7. The predicted model submitted in Protein Model Database, PMDB for public use. This model will be used in wide range of studies for functional analysis and improvement activity of the protein.     

Docosahexaenoic acid sensitizes Ramos cells to Gamma-irradiation-induced apoptosis through involvement of PPAR-γ activation and NF-κB suppression

The aim of the present study was to characterize the effects of chronic nitric oxide synthase (NOS) inhibition on the alterations of regulatory myocardial proteins of intracellular signaling pathways (mitogen-activated protein kinase (MAPK) and Akt kinase cascades) and matrix metalloproteinases (MMP). Chronic NO deficiency (NOD) was induced by N^G-nitro-L-arginine methyl ester (L-NAME, 40mg/kg/day, 4 weeks). Protein levels and activation of protein kinases were determined using specific antibodies, activities of MMP were analyzed by zymography in gels containing gelatin as a substrate. The development of NOD was associated with decreased activation of endothelial NOS (eNOS) and down-regulation of protein level of inducible NOS (iNOS). Investigation of kinase pathways revealed that the activation of extracellular signal-regulated kinases (ERK) and the levels of upstream activators of ERK (aFGF, H-Ras) were decreased after L-NAME treatment. Western blot analysis revealed that chronic application of L-NAME also decreased the activation of Akt kinase as compared with control hearts. Study of MMPs showed that in L-NAME-treated rat hearts activities of tissue MMP-2 were decreased. It is concluded that development of NOD resulted in inhibition of ERK and Akt kinase pathways and these changes suggest the involvement of these cascades in responses of myocardium to NOD. The results also point to the possible relationship between ERK and Akt kinase pathways and activation of eNOS and/or MMP-2. Anna Špániková and Petra Šimončíková have contributed equally to the study.     

Penconazole alleviates salt-induced damage in safflower (Carthamus tinctorius L.) plants

It has been shown that penconazole (PEN) acts as an endogenous signal molecule responsible for inducing stress tolerance in plants. The effect of PEN (15?mg?l^–1) and sodium chloride (0, 100, and 200 mM NaCl) on some biochemical and molecular responses of safflower was studied. Results revealed that chlorophylls and total soluble protein contents decreased under salinity, however total carotenoid, anthocyanin, flavonoid, and carbohydrate contents increased as well as SOS1 and NHX1 genes expression. The exogenous PEN had a positive effect on chlorophylls, carotenoid, anthocyanin, flavonoid, soluble protein and carbohydrate contents. In addition, RT-qPCR analysis showed that the exogenous PEN induced expression of SOS1 and NHX1 genes in both salt-treated and untreated plants. Our data indicate that PEN helps safflower plants to better cope with salt stress. The results can provide new insights to better realizing the responsible mechanisms to regulate salinity resistance in safflower. PEN can be considered in order to ameliorate salinity effects, due to the low price and their availability.     

Evaluation of the toxicity effects of silk fibroin on human lymphocytes and monocytes

Silk fibroin nanoparticles (SFNPs) as a natural polymer have been utilized in biomedical applications such as suture, tissue engineering‐based scaffolds, and drug delivery carriers. Since there is little data regarding the toxicity effects on different cells and tissues, we aimed to determine the toxicity mechanisms of SFNPs on human lymphocytes and monocytes based on reliable methods. Our results showed that SFNPs (0.5, 1, and 2 mg/mL) induced oxidative stress via increasing reactive oxygen species production, mitochondrial membrane potential (?Ψ) collapse, which was correlated to cytochrome c release and Adenosine diphosphate (ADP)/Adenosine tri phosphate (ATP) ratio increase as well as lysosomal as another toxicity mechanism, which led to cytosolic release of lysosomal digestive proteases, phosphor lipases, and apoptosis signaling. Taken together, these data suggested that SFNPs toxicity was associated with mutual mitochondrial/lysosomal cross‐talk and oxidative stress on human lymphocytes and monocytes with activated apoptosis signaling.