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Your search keyword '"Dhanuja D. Perera"' showing total 2 results
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2 results on '"Dhanuja D. Perera"'

1. Dielectric Analysis of Response Time in Electrorheological Fluids Developed for Medical Devices

Author

Alan T. Riga, Tobili Sam Yellowe, Manik Pavan Kumar Maheswaram, Dhanuja D. Perera, Dhruthiman Mantheni, Naullage Indika Perera, and M. Ellen Matthews

Subjects
Permittivity, Materials science, Correlation coefficient, Loss factor, Analytical chemistry, Response time, Dielectric, Electrorheological fluid, Psychiatry and Mental health, chemistry.chemical_compound, symbols.namesake, chemistry, Polyaniline, symbols, Debye
Abstract

Three electrorheological fluids (ERFs) of recently synthesized Polyaniline.HCl and Cellulose fluids as well as a commercial product from Fludicon® (Germany), were evaluated with a two-electrode probe unit and by Dielectric Analysis (DEA). The study was a part of an ongoing medical device development project. The dielectric response times were calculated using the critical peak frequency in a corresponding Debye plot of Tan Delta (loss factor/permittivity) vs. log frequency. The DEA revealed the response times (tau, τ) in ms. The Fludicon® ERF was DEA durable (repeat cycles produced same results) and the τ was temperature dependent: 16 ms at 25°C and 0.16 ms at 80°C. The Cellulose ERF was somewhat DEA durable and the τ was 5.5 ms at 25°C and 0.21 ms at 80°C. The response times were logarithmic with the temperature (°C) with a correlation coefficient of >0.98 for the Cellulose and Fludicon® ERFs. The Polyaniline ERF had a τ of 53 ms at 25°C in the 1st DEA run and there was no indication of a τ for the remaining DEA tests.

Published
2011
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2. Structural basis for the autoinhibition of talin in regulating integrin activation.

Author

Goksoy E, Ma YQ, Wang X, Kong X, Perera D, Plow EF, and Qin J

Subjects
Animals, Binding Sites, CHO Cells, Cell Membrane drug effects, Cell Membrane metabolism, Cricetinae, Cricetulus, Integrin beta Chains chemistry, Magnetic Resonance Spectroscopy, Mice, Models, Biological, Models, Molecular, Phosphatidylinositol 4,5-Diphosphate pharmacology, Protein Binding drug effects, Protein Structure, Tertiary, Structure-Activity Relationship, Integrin beta Chains metabolism, Talin antagonists & inhibitors, Talin chemistry
Abstract

Activation of heterodimeric (alpha/beta) integrin transmembrane receptors by the 270 kDa cytoskeletal protein talin is essential for many important cell adhesive and physiological responses. A key step in this process involves interaction of phosphotyrosine-binding (PTB) domain in the N-terminal head of talin (talin-H) with integrin beta membrane-proximal cytoplasmic tails (beta-MP-CTs). Compared to talin-H, intact talin exhibits low potency in inducing integrin activation. Using NMR spectroscopy, we show that the large C-terminal rod domain of talin (talin-R) interacts with talin-H and allosterically restrains talin in a closed conformation. We further demonstrate that talin-R specifically masks a region in talin-PTB where integrin beta-MP-CT binds and competes with it for binding to talin-PTB. The inhibitory interaction is disrupted by a constitutively activating mutation (M319A) or by phosphatidylinositol 4,5-bisphosphate, a known talin activator. These data define a distinct autoinhibition mechanism for talin and suggest how it controls integrin activation and cell adhesion.

Published
2008
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