Browsing by Author "Parameswaran, R"

Now showing 1 - 4 of 4
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    Does F-18 FDG-PET substantially alter the surgical decision-making in drug-resistant partial epilepsy?
    (EPILEPSY & BEHAVIOR, 2015) Menon, RN; Radhakrishnan, A; Parameswaran, R; Thomas, B; Kesayadas, C; Abraham, M; Vilanilam, G; Sarma, SP
    Objective: There is a dearth of information on the critical utility of positron emission tomography (PET) in choosing candidates for epilepsy surgery especially in resource-poor countries where it is not freely available. This study aimed to critically analyze the utility of FDG-PET in the presurgical evaluation and surgical selection of patients with DRE based on the results obtained through its use in our comprehensive epilepsy program. Methods: From 2008 to 2012, 117 patients with drug-resistant epilepsy underwent F-18 fluoro-deoxy-glucose (FDG) PET in our center. We utilized their data to audit the utility of PET in choosing/deferring patients for surgery. Results: Of the 117 patients (age: 5-42 years) who underwent F-18 FDG-PET, 64 had normal MRI, and 53 had lesions. Electroclinical data favored temporal ictal onset in 48 (41%), extratemporal in 60 (51.3%), and uncertain lobar localization in 9 (7.7%). The topography of PET hypometabolism was localizing in 53 (45.3%), lateralizing in 12 (10.3%), and 52 (44.4%) had either normal or discordant results. In the nonlesional group, focal hypometabolism was concordant to the area of ictal onset in 27 (41.5%) versus 38 (58.5%) in the lesional group (p = 0.002). Greater concordance was noted in temporal lobe epilepsy (TLE) (78.0%) as compared to extratemporal epilepsy (ETPE) (28.6%) (p < 0.001). Positron emission tomography was more concordant in patients with mesial temporal sclerosis than in those with other lesions (82.8% versus 50%) (p = 0.033). Positron emission tomography helped in surgical decision-making in 68.8% of TLE and 23.3% of ETPE cases. Overall, 37 patients (31.6%) were directly selected for resective surgery based on PET results. Conclusions: Positron emission tomography, when utilized judiciously, remained an ancillary tool in the surgical selection of one-third of patients with drug-resistant partial epilepsy, although its utility as an independent tool is not very promising. (C) 2015 Elsevier Inc. All rights reserved.
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    Mechanical characterization of high-performance graphene oxide incorporated aligned fibroporous poly(carbonate urethane) membrane for potential biomedical applications
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2015) Thampi, S; Muthuvijayan, V; Parameswaran, R
    In this article, we report the development of graphene oxide (GO) reinforced electrospun poly(carbonate urethane) (PCU) nanocomposite membranes intended for biomedical applications. In this study, we aimed to improve the mechanical properties of PCU fibroporous electrospun membranes through fiber alignment and GO incorporation. Membranes with 1, 1.5, and 3% loadings of GO were evaluated for their morphology, mechanical properties, crystallinity, biocompatibility, and hemocompatibitity. The mechanical properties were assessed under both static and dynamic conditions to explore the tensile characteristics and visco-elastic properties. The results show that GO presented a good dispersion and exfoliation in the PCU matrix, contributing to an increase in the mechanical performance. The static mechanical properties indicated a 55% increase in the tensile strength, a 127% increase in toughness for 1.5 wt % GO loading and the achievement of a maximum strength reinforcement efficiency value at the same loading. Crystallinity changes in membranes were examined by X-ray diffraction analysis. In vitro cytotoxicity tests with L-929 fibroblast cells and percentage hemolysis tests with fresh venous blood displayed the membranes to be cytocompatible with acceptable levels of hemolytic characteristics. Accordingly, these results highlight the potential of this mechanically improved composite membrane's application in the biomedical field. (C) 2013 Wiley Periodicals, Inc.
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    Silanization induced inherent strain in graphene based filler influencing mechanical properties of polycarbonate urethane nanocomposite membranes
    (RSC ADVANCES, 2016) Thampi, S; Muthuvijayan, V; Parameswaran, R
    Nanosheet type fillers apart from their size and surface functional groups may have numerous attributes affecting the mechanical properties of polymeric nanocomposites. To study these, silane-functionalized graphene based fillers were synthesized by chemically grafting N-[3-(trimethoxysilyl) propyl] diethylenetriamine (TMPT) onto graphene oxide (GO) and carboxylated GO (GOCO) using different chemistries. Their respective silanization yielded nano-fillers with amine (GOSAM) and alkoxy (GOCSAL) groups. Further, hydroiodic acid (HI) treatment led to synthesis of their reduced counterparts GRSAM and GRCSAL. The resulting TMPT-functionalized nanosheets were characterized by Fourier transform infrared spectroscopy (FT-IR) confirmed silane functionalization. A blue shift in Raman spectra indicated that during silanization with different terminal groups an inherent compressive strain has developed, while reduction with HI caused a red shift indicating a tensile strain, in these nanosheets. Polycarbonate urethane nanocomposite electrospun membranes (PCU) incorporated with these respective fillers at different loadings were analyzed. Morphology of the nanocomposite membranes was observed under SEM and membranes were characterized by static and dynamic mechanical analysis. The study indicated that the exfoliation and dispersion of graphene sheets in PCU has significantly improved due to surface functionalization while it also exhibited a novel aspect, variations in their mechanical properties in respect to the type of strain present in incorporated nanosheet fillers. The nanosheet fillers with compressive strain contributed more to the mechanical property enhancement of nanocomposite membranes, than the fillers with tensile strain. A spring and molecule model was thus proposed as possible explanation to relate inherent strain in filler to that of nanocomposite membrane mechanical properties. In vitro non-cytotoxic and hemocompatible nature of these fibroporous nanocomposite membranes provided their potential in biomedical applications.
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    Synthesis, Characterization, and Electrospinning of Calcium-Containing Polyurethane Urea
    (ADVANCES IN POLYMER TECHNOLOGY, 2016) Nair, PA; Parameswaran, R
    Calcium-containing segmented polyurethane urea was synthesized using a calcium salt of p-aminobenzoic acid, polytetramethylene glycol, and 4,4-methylene bis(cyclohexyl isocyanate) and thereafter fabricated into three-dimensional scaffolds for the use in biomedical applications. Biocompatibility evaluation of the polymer showed that this newly developed metal-containing polyurethane urea demonstrated good cytocompatibility and hemocompatibility. The fabricating ability of the metal-containing polymer was studied by the electrospinning process. The effect of various parameters such as polymer concentration, applied voltage, and flow rate on the electrospinning process, morphology, and diameter of the resultant fibers was investigated. The findings indicate that increasing the concentration and flow rate of the solution increases the fiber diameter. It was also demonstrated that increasing the applied voltage decreases the fiber diameter. Mechanical property evaluation of the scaffolds showed that the strength of the scaffold depends on both the diameter and morphology of the fibers. As the fiber diameter increases from 1.6 to 3.02 m, the tensile strength enhanced from 3 to 7MPa.