Glutaredoxin-1 overexpression enhances neovascularization and diminishes ventricular remodeling in chronic myocardial infarction

Oxidative stress plays a critical role in the pathophysiology of cardiac failure, including the modulation of neovascularization following myocardial infarction (MI). Redox molecules thioredoxin (Trx) and glutaredoxin (Grx) superfamilies actively maintain intracellular thiol-redox homeostasis by scavenging reactive oxygen species. Among these two superfamilies, the pro-angiogenic function of Trx-1 has been reported in chronic MI model whereas similar role of Grx-1 remains uncertain. The present study attempts to establish the role of Grx-1 in neovascularization and ventricular remodeling following MI. Wild-type (WT) and Grx-1 transgenic (Grx-1(Tg/+)) mice were randomized into wild-type sham (WTS), Grx-1(Tg/+) Sham (Grx-1(Tg/+)S), WTMI, Grx-1(Tg/+)MI. MI was induced by permanent occlusion of the LAD coronary artery. Sham groups underwent identical time-matched surgical procedures without LAD ligation. Significant increase in arteriolar density was observed 7 days (d) after surgical intervention in the Grx-1(Tg/+)MI group as compared to the WTMI animals. Further, improvement in myocardial functional parameters 30 d after MI was observed including decreased LVIDs, LVIDd, increased ejection fraction and, fractional shortening was also observed in the Grx-1(Tg/+)MI group as compared to the WTMI animals. Moreover, attenuation of oxidative stress and apoptotic cardiomyocytes was observed in the Grx-1(Tg/+)MI group as compared to the WTMI animals. Increased expression of p-Akt, VEGF, Ang-1, Bcl-2, survivin and DNA binding activity of NF-κB were observed in the Grx-1(Tg/+)MI group when compared to WTMI animals as revealed by Western blot analysis and Gel-shift analysis, respectively. These results are the first to demonstrate that Grx-1 induces angiogenesis and diminishes ventricular remodeling apparently through neovascularization mediated by Akt, VEGF, Ang-1 and NF-κB as well as Bcl-2 and survivin-mediated anti-apoptotic pathway in the infarcted myocardium.     

Effect of aluminium toxicity on growth responses and antioxidant activities in Gmelina arborea Roxb. inoculated with AM fungi

Arbuscular mycorrhizal fungi alleviating the adverse Aluminium effects on growth and antioxidant activity was tested in Gmelina plants. Under greenhouse and aluminium stress condition, the mycorrhizal Gmelina plants showed good growth as compared to non mycorrhizal Gmelina plants. Mycorrhizal colonization in Gmelina was found not to be significantly influenced by aluminium concentrations. Results also indicate that symbiotic association was successfully established between Glomus intraradices and Gmelina plants and mycorrhizal colonization consequently increased the biomass of Gmelina. The root proline accumulation was found to increase in mycorrhizal Gmelina plants for osmotic adjustment of stress tissues under first and second level of Aluminium stress. It was observed that Mycorrhizal colonization increased the shoot root Peroxidase and Superoxide dismutase activities in mycorrhizal Gmelina under second level of Aluminium stress. Mycorrhizal fungi play a major role in phytostabilization by secreting one of the glycoprotein, i.e., Glomalin, which stabilizes the Aluminium in soil as well as in the roots of Gmelina plants.     

Low plasma albumin levels are associated with increased plasma protein glycation and HbA1c in diabetes

Albumin is one of the most abundant plasma proteins and is heavily glycated in diabetes. In this study, we have addressed whether variation in the albumin levels influence glycation of plasma proteins and HbA1c. The study was performed in three systems: (1) streptozotocin (STZ)-induced diabetic mice plasma, (2) diabetic clinical plasma, and (3) in vitro glycated plasma. Diabetic mice and clinical plasma samples were categorized as diabetic high albumin plasma (DHAP) and diabetic low albumin plasma (DLAP) on the basis of their albumin levels. For the in vitro experiment, two albumin levels, high albumin plasma (HAP) and low albumin plasma (LAP), were created by differential depletion of plasma albumin. Protein glycation was studied by using a combination of two-dimensional electrophoresis (2DE), Western blotting, and LC-MS(E). In both mice and clinical experiments, an increased plasma protein glycation was observed in DLAP than in DHAP. Additionally, plasma albumin levels were negatively correlated with HbA1c. The in vitro experiment with differential depletion of albumin mechanistically showed that the low albumin levels are associated with increased plasma protein glycation and that albumin competes for glycation with other plasma proteins.     

Current advances in peptide and small molecule microarray technologies

Microarrays offer a compact solution for massively parallel screening. In recent years, microarrays have branched away from the exclusive pursuit of small molecule 'hits' in target centric screens, towards the sophisticated dissection of disease biology and comparative profiling of cellular states. This has led to innovative and instructive ways in which the platform may be deployed, providing new-found methods with which to harness the throughput achievable. Library design and diversity continues to drive success with peptide and small molecule microarrays. Newer synthesis and immobilization strategies extend the already wide repertoire of fabrication methods available. Herein we describe the latest advances in the small molecule and peptide microarray arena, which herald even more exciting breakthroughs in the coming decade.     

Novel levamisole derivative induces extrinsic pathway of apoptosis in cancer cells and inhibits tumor progression in mice

Background

Levamisole, an imidazo(2,1-b)thiazole derivative, has been reported to be a potential antitumor agent. In the present study, we have investigated the mechanism of action of one of the recently identified analogues, 4a (2-benzyl-6-(4′-fluorophenyl)-5-thiocyanato-imidazo[2,1-b][1], [3], [4]thiadiazole).

Materials and Methods

ROS production and expression of various apoptotic proteins were measured following 4a treatment in leukemia cell lines. Tumor animal models were used to evaluate the effect of 4a in comparison with Levamisole on progression of breast adenocarcinoma and survival. Immunohistochemistry and western blotting studies were performed to understand the mechanism of 4a action both ex vivo and in vivo.

Results

We have determined the IC₅₀ value of 4a in many leukemic and breast cancer cell lines and found CEM cells most sensitive (IC₅₀ 5 µM). Results showed that 4a treatment leads to the accumulation of ROS. Western blot analysis showed upregulation of pro-apoptotic proteins t-BID and BAX, upon treatment with 4a. Besides, dose-dependent activation of p53 along with FAS, FAS-L, and cleavage of CASPASE-8 suggest that it induces death receptor mediated apoptotic pathway in CEM cells. More importantly, we observed a reduction in tumor growth and significant increase in survival upon oral administration of 4a (20 mg/kg, six doses) in mice. In comparison, 4a was found to be more potent than its parental analogue Levamisole based on both ex vivo and in vivo studies. Further, immunohistochemistry and western blotting studies indicate that 4a treatment led to abrogation of tumor cell proliferation and activation of apoptosis by the extrinsic pathway even in animal models.

Conclusion

Thus, our results suggest that 4a could be used as a potent chemotherapeutic agent.     

Novel role of NADPH oxidase in ischemic myocardium: a study with Nox2 knockout mice

Several potential sources of reactive oxygen species (ROS) in cells exist. One source is NADPH oxidase, which is especially important for superoxide radical production. Nox2 is a primary regulatory subunit of NADPH oxidase. In the present study, we examined the role of ROS and NADPH oxidase in ischemic preconditioning (IP)-mediated cardioprotection by using Nox2(-/-) mice. Both wild-type (WT) and Nox2(-/-) mice were subjected to either 30?min of ischemia followed by 2?h of reperfusion (IR) or IP prior to 30?min ischemia and 2?h of reperfusion. Reduction in left ventricular developed pressure (60.1 versus 63?mmHg), dp/dt (max) (893 versus 1,027?mmHg/s), and aortic flow (0.9 versus 1.8?ml/min) was observed in Nox2(-/-)IPIR compared to WTIPIR along with increased infarct size (33% versus 22%) and apoptosis after 120?min of reperfusion. Differentially regulated genes were demonstrated by comparing gene expression in WTIPIR versus Nox2(-/-) IPIR hearts. Selected differentially regulated genes such as β-catenin, SRPK3, ERDR1, ACIN1, Syntaxin-8, and STC1 were validated by real-time PCR. Taken together, this is the first report identifying important, differentially expressed genes during ischemic preconditioning in Nox2(-/-) mice by using microarray analysis.     

Nutrient resorption patterns of plant functional groups in a tropical savanna: variation and functional significance

Green and senesced leaf nitrogen (N) and phosphorus (P) concentrations of different plant functional groups in savanna communities of Kruger National Park, South Africa were analyzed to determine if nutrient resorption was regulated by plant nutritional status and foliar N:P ratios. The N and P concentrations in green leaves and the N concentrations in senesced leaves differed significantly between the dominant plant functional groups in these savannas: fine-leaved trees, broad-leaved trees and grasses. However, all three functional groups reduced P to comparable and very low levels in senesced leaves, suggesting that P was tightly conserved in this tropical semi-arid savanna ecosystem. Across all functional groups, there was evidence for nutritional control of resorption in this system, with both N and P resorption efficiencies decreasing as green leaf nutrient concentrations increased. However, specific patterns of resorption and the functional relationships between nutrient concentrations in green and senesced leaves varied by nutrient and plant functional group. Functional relationships between N concentrations in green and senesced leaves were indistinguishable between the dominant groups, suggesting that variation in N resorption efficiency was largely the result of inter-life form differences in green leaf N concentrations. In contrast, observed differences in P resorption efficiencies between life forms appear to be the result of both differences in green leaf P concentrations as well as inherent differences between life forms in the fraction of green leaf P resorbed from senescing leaves. Our results indicate that foliar N:P ratios are poor predictors of resorption efficiency in this ecosystem, in contrast to N and P resorption proficiencies, which are more responsive to foliar N:P ratios.