Bioinspired Glycopolymers: Models to Investigate the Effect of Saccharide Structure and Concentration on Amyloid Beta Aggregation

Aggregation and subsequent deposition of amyloid-β (Aβ) peptide on neuronal cell membranes have been implicated as a cause of Alzheimer’s disease. Gangliosides in their clustered form seed and promote the Aβ aggregation process. However, the effects of the structure and the concentration of ganglioside saccharides on Aβ aggregation are not well understood. We investigated how the specific structure of saccharides (β-D-galactose and β-D-glucose) affect the aggregation pathways, kinetics, and the aggregated structures of Aβ via in vitro experiments. The effects of the local concentration of saccharides on the Aβ aggregation were also investigated. To mimic the multivalent effect of the ganglioside saccharides, we designed and synthesized stereospecific bio-relevant saccharide containing model polymers, known as glycopolymers in solution and from surfaces. Acrylamide based glycopolymers of desired molecular weights were synthesized in solution via reversible addition-fragmentation chain transfer (RAFT) polymerization. Using thioflavin T fluorescence (ThT) and polyacrylamide gel electrophoresis (PAGE), we found that the Aβ formed small aggregates in the presence of high molecular weight (DP 350) glucose containing polymers, but large aggregates were formed in the presence of low (DP 35) molecular weight glucose containing polymers, low and high molecular weight galactose containing polymers, and non-saccharide control polymers. Glycopolymer films of high and low thickness were synthesized from silicon surfaces via photopolymerization and surface-initiated RAFT polymerization and the effect of the saccharides of grafted glycopolymers on Aβ aggregation were investigated. Quartz crystal microbalance (QCM)experiments established that the Aβ bound more strongly with the glucose polymer grafted surfaces than the galactose polymer grafted surfaces. AFM imaging revealed that the Aβ aggregated to form fibrils when incubated with the thin films of glucose or galactose polymers and control surfaces. These results suggest that the high molecular weight glucose-containing polymers strongly affect and alter the Aβ aggregation pathway and promote the formation of Aβ oligomers while other polymers do not affect the aggregation process

Fiber reinforced polymer composites characterization by differential scanning calorimeter

The conventional materials are nowadays not sufficient to cater to the variety of uses and exposure to various environments that may take place while they are put into use. Hence this leads to the development of composites, which nearly suffice the above two conditions. But they are always prone to detoriation and degradation of properties due to their extreme affinity for moisture absorption. Many complex reactions occur at the fibermatrix interface due to moisture absorption, but very little information is available regarding the deviation in physical and chemical behavior at the interface due to this. The present work focuses on the physical changes occurring at the fiber-matrix interface. In our case, the samples were divided into three parts. One was kept as dry sample; the others were hygrothermally aged for 50 hours and 100 hours respectively at 50o C and 95% humidity. Now a comparative study of all the three samples was done near the interface. The DSC technique was carried out to study the physical changes or deviation of the Glass transition temperature of the composite. From the nature of the curve obtained from the DSC measurements, we can infer about how the Glass transition temperature varies with the heat flow, and how it varies for different samples with different hygrothermal treatment. From these data, the changes occurring at the interface can be known

Path Planning of Mobile Robot in Unknown Environment

In this paper, we study the online path planning for khepera II mobile robot in an unknown environment. The well known heuristic A* algorithm is implemented to make the mobile robot navigate through static obstacles and find the shortest path from an initial position to a target position by avoiding the obstacles. The proposed path finding strategy is designed in a grid-map form of an unknown environment with static unknown obstacles. When the mission is executed, it is necessary to plan an optimal or feasible path for itself avoiding obstructions in its way and minimizing a cost such as time, energy, and distance. In our study we have considered the distance and time metric as the cost function

D* lite algorithm based path planning of mobile robot in static Environment

In this paper, we study the path planning for khepera II mobile robot in an unknown environment. The well known heuristic D* lite algorithm is implemented to make the mobile robot navigate through static obstacles and find the shortest path from an initial position to a target position by avoiding the obstacles. and to perform efficient re-planning during exploration. The proposed path finding strategy is designed in a grid-map form of an unknown environment with static unknown obstacles. The robot moves within the unknown environment by sensing and avoiding the obstacles coming across its way towards the target. When the mission is executed, it is necessary to plan an optimal or feasible path for itself avoiding obstructions in its way and minimizing a cost such as time, energy, and distance. In our study we have considered the distance metric as the cost functio

Repurposing of Glycine-Rich Proteins in Abiotic and Biotic Stresses in the Lone-Star Tick (\u3ci\u3eAmblyomma americanum\u3c/i\u3e)

Tick feeding requires the secretion of a huge number of pharmacologically dynamic proteins and other molecules which are vital for the formation of the cement cone, the establishment of the blood pool and to counter against the host immune response. Glycine-rich proteins (GRP) are found in many organisms and can function in a variety of cellular processes and structures. The functional characterization of the GRPs in the tick salivary glands has not been elucidated. GRPs have been found to play a role in the formation of the cement cone; however, new evidence suggests repurposing of GRPs in the tick physiology. In this study, an RNA interference approach was utilized to silence two glycine-rich protein genes expressed in early phase of tick feeding to determine their functional role in tick hematophagy, cement cone structure, and microbial homeostasis within the tick host. Additionally, the transcriptional regulation of GRPs was determined after exposure to biotic and abiotic stresses including cold and hot temperature, injury, and oxidative stress. This caused a significant up-regulation of AamerSigP-34358, Aam-40766, AamerSigP-39259, and Aam-36909. Our results suggest ticks repurpose these proteins and further functional characterization of GRPs may help to design novel molecular strategies to disrupt the homeostasis and the pathogen transmission

Extensional subsidence, inversion and volumetric contraction in the Bass Basin of Australia : a seismic study / Pradipta Kumar Das.

"August, 2001"Bibliography: leaves 173-183.xvi, 184, 12 leaves : ill. (some col.), maps, plates (some col.) ; 30 cm."The primary objective of the study was to gain a better understanding of the tectonostratigraphic evolutionary history of the Bass Basin. In particular, the study has focussed on mapping and analysing all the faults and fault patterns in the Bass Basin in relation to the subsidence history and its influence on sedimentation and hydrocarbon potential of the basin. The reason why the Durroon area and the Bass area behaved differently in response to extensional stresses was investigated. As a final outcome, it was thought important to clarify some of the existing disagreement about the broad tectonic and structural history of the basin and in particular to separate the influence of the Otway and Tasman Sea rifting episodes on the sedimentation history of the Bass and Durroon area. The study also aimed at investigating the occurence in the basin and nature of a recently recognised fault system, a polygonal fault system." --p. 2.Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology and Geophysics, 200

“Prevalence of intestinal-parasites and its association with sociodemographic, environmental and behavioral factors in children in Pokhara valley, Nepal”

No Abstract. African Journal of Clinical and Experimental Microbiology Vol. 7(2) 2006: 106-11