Structural characterization of the large soluble oligomers of the GTPase effector domain of dynamin

Dynamin, a protein playing crucial roles in endocytosis, oligomerizes to form spirals around the necks of incipient vesicles and helps their scission from membranes. This oligomerization is known to be mediated by the GTPase effector domain (GED). Here we have characterized the structural features of recombinant GED using a variety of biophysical methods. Gel filtration and dynamic light scattering experiments indicate that in solution, the GED has an intrinsic tendency to oligomerize. It forms large soluble oligomers (molecular mass > 600 kDa). Interestingly, they exist in equilibrium with the monomer, the equilibrium being largely in favour of the oligomers. This equilibrium, observed for the first time for GED, may have regulatory implications for dynamin function. From the circular dichroism measurements the multimers are seen to have a high helical content. From multidimensional NMR analysis we have determined that about 30 residues in the monomeric units constituting the oligomers are flexible, and these include a 17 residue stretch near the N-terminal. This contains two short segments with helical propensities in an otherwise dynamic structure. Negatively charged SDS micelles cause dissociation of the oligomers into monomers, and interestingly, the helical characteristics of the oligomer are completely retained in the individual monomers. The segments along the chain that are likely to form helices have been predicted from five different algorithms, all of which identify two long stretches. Surface electrostatic potential calculation for these helices reveals that there is a distribution of neutral, positive and negative potentials, suggesting that both electrostatic and hydrophobic interactions could be playing important roles in the oligomer core formation. A single point mutation, I697A, in one of the helices inhibited oligomerization quite substantially, indicating firstly, a special role of this residue, and secondly, a decisive, though localized, contribution of hydrophobic interaction in the association process

New Code design for High Speed Optical Network:Multiple Access Interference(MAI), Multiple Service Code (MS), Optical code division multiple access (OCDMA), Random Diagonal Code (RD). Spectral Amplitude Coding(SAC)

ABSTRACT A new design of the code is proposed for optical code division multiple access system. This code is based on the in ideal in phase cross correlation method. The code follows the unit cross correlation. The simulation shows that the results are better than the existing methods while all parameters are considered during design. Simulation is performed at high data rates from 10Gbits/s to 20 Gbits/s. The obtained results show better performance than existing techniques RD and MS Code

Abstract 19808: Short term outcomes after use of bone marrow transplantation for management of heart failure: a meta-analysis

The role of bone marrow cell transplant in ischemic heart failure is being increasingly recognized. Multiple studies have been published evaluating their use with varying results. We aimed to perform a meta-analysis of the published literature. We searched Pubmed, EBSCO and Cochrane databases for terms “bone marrow transplant”, “stem cell transplant”, “heart failure”, “cardiac failure” and their combinations. Only studies comparing bone marrow cell transplantation via intracoronary route to placebo, and those with 6 month follow up data were included. Studies in language other than English were excluded. Results: Ejection fraction was significantly increased with the use of bone marrow cell transplant compared to placebo (mean difference 6.16% 95%CI 4.16 to 8.16, p \u3c 0.00001). No significant differences were observed in left ventricular (LV) end-systolic volume (mean difference -1.58 ml 95%CI -4.98 to 1.82, p = 0.36), LV end-diastolic volume (mean difference -0.77 ml 95%CI -3.75 to 2.22, p = 0.61) and mortality (odds ratio 1.08 95%CI 0.26 to 4.56, p = 0.92). Results of heterogeneity analysis showed significant heterogeneity only for ejection fraction endpoint (p = 0.01). Conclusion: As compared to placebo, intracoronary bone marrow cell transplant is associated with improved LV ejection fraction by 6% in ischemic heart failure patients at 6 month follow up

CD133+ Tumor Initiating Cells in a Syngenic Murine Model of Pancreatic Cancer Respond to Minnelide

PURPOSE: Pancreatic adenocarcinoma is the fourth leading cause for cancer-related mortality with a survival rate of less than 5%. Late diagnosis and lack of effective chemotherapeutic regimen contribute to these grim survival statistics. Relapse of any tumor is largely attributed to the presence of tumor-initiating cells (TIC) or cancer stem cells (CSC). These cells are considered as hurdles to cancer therapy as no known chemotherapeutic compound is reported to target them. Thus, there is an urgent need to develop a TIC-targeted therapy for pancreatic cancer. EXPERIMENTAL DESIGN: We isolated CD133+ cells from a spontaneous PDAC mouse model and studied both surface expression, molecular markers of pancreatic TICs. We also studied tumor initiation properties by implanting low numbers of CD133+ cells in immune competent mice. Effect of Minnelide, a drug currently under Phase I clinical trial, was studied on the tumors derived from the CD133+ cells. RESULTS: Our study showed for the first time that CD133(+) population demonstrated all the molecular markers for pancreatic TIC. These cells initiated tumors in immunocompetent mouse models and showed increased expression of pro-survival and pro-invasive proteins compared to the CD133− non-TIC population. Our study further showed that Minnelide, was very efficient in downregulating both CD133− and CD133+ population in the tumors, resulting in a 60% decrease in tumor volume compared to the untreated ones. CONCLUSION: As Minnelide is currently under Phase I clinical trial, its evaluation in reducing tumor burden by decreasing TIC as well as non-TIC population suggests its potential as an effective therapy