59 results on '"V. Chandrasekar"'
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2. Ferrofluid Droplet Chains in Thermotropic Nematic Liquid Crystals.
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Chandrasekar V, Lu JR, and Dierking I
- Abstract
Dispersing ferrofluids in liquid crystals (LCs) produces unique systems which possess magnetic functionality and novel phenomena such as droplet chaining. This work reports the formation of ferrofluid droplet chains facilitated by the topological defects within the LC director field, induced by the dispersed ferrofluid. The translational and rotational motion of these chains could be controlled via application of external magnetic fields. The process of the droplet chain formation in LCs can be stabilized by the addition of surfactants. The magnetic colloidal particles in the ferrofluid located at the interface between the ferrofluid and the LC are arranged so that a boundary layer was formed. The velocities and boundary layer thickness values of ferrofluid droplet chains in nematic 5CB (4-Cyano-4'-pentylbiphenyl) were investigated for varying average droplet sizes and number of droplets in a chain. The creation and behaviour of ferrofluid droplet chains in 5CB with the addition of the surfactant polysorbate 60 (Tween-60) and without, was comparatively investigated. The integration of liquid crystals and ferrofluids along with the incorporation of functional materials facilitates the innovative development of advanced materials for future applications., (© 2024 The Authors. ChemPhysChem published by Wiley-VCH GmbH.)
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- 2024
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3. Sustainable bioinspired materials for regenerative medicine: balancing toxicology, environmental impact, and ethical considerations.
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Singh AV, Chandrasekar V, Prabhu VM, Bhadra J, Laux P, Bhardwaj P, Al-Ansari AA, Aboumarzouk OM, Luch A, and Dakua SP
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- Humans, Animals, Toxicity Tests, Tissue Engineering methods, Tissue Engineering ethics, Environment, Biomimetic Materials chemistry, Regenerative Medicine ethics, Regenerative Medicine methods, Biocompatible Materials chemistry, Materials Testing
- Abstract
The pursuit of sustainable bioinspired materials for regenerative medicine demands a nuanced balance between scientific advancement, ethical considerations, and environmental consciousness. This abstract encapsulates a comprehensive perspective paper exploring the intricate dynamics of toxicology, environmental impact, and ethical concerns within the realm of bioinspired materials. As the landscape of regenerative medicine evolves, ensuring the biocompatibility and safety of these materials emerges as a pivotal challenge. Our paper delves into the multidimensional aspects of toxicity assessment, encompassing cytotoxicity, genotoxicity, and immunotoxicity analyses. Additionally, we shed light on the complexities of evaluating the environmental impact of bioinspired materials, discussing methodologies such as life cycle assessment, biodegradability testing, and sustainable design approaches. Amid these scientific endeavors, we emphasize the paramount importance of ethical considerations in bioinspired material development, navigating the intricate web of international regulations and ethical frameworks guiding medical materials. Furthermore, our abstract underscores the envisioned future directions and challenges in toxicology techniques, computational modeling, and holistic evaluation, aiming for a comprehensive understanding of the synergistic interplay between sustainable bioinspired materials, toxicity assessment, environmental stewardship, and ethical deliberation., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)
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- 2024
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4. Novel H-2D b -restricted CD8 epitope derived from mouse MAGE-type antigen P1A mediates antitumor immunity in C57BL/6 mice.
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McAuliffe J, Panetti S, Steffke E, Wicki A, Pereira-Almeida V, Noblecourt L, Hu Y, Guo SYW, Lesenfants J, Ramirez-Valdez RA, Chandrasekar V, Ahmad M, Stroobant V, Vigneron N, Van den Eynde BJ, and Leung CSK
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- Animals, Mice, Female, Antigens, Neoplasm immunology, Histocompatibility Antigen H-2D immunology, Cell Line, Tumor, H-2 Antigens immunology, Epitopes, T-Lymphocyte immunology, CD8-Positive T-Lymphocytes immunology, Mice, Inbred C57BL, Cancer Vaccines immunology
- Abstract
Background: Melanoma antigen gene (MAGE)-type antigens are promising targets for cancer immunotherapy as they are expressed in cancer cells but not in normal tissues, except for male germline cells. The mouse P1A antigen shares this MAGE-type expression pattern and has been used as a target antigen in preclinical tumor models aiming to induce antitumor CD8
+ T-cell responses. However, so far only one MHC I-restricted P1A epitope has been identified. It is presented by H-2Ld in mice of the H-2d genetic background such as DBA/2 and BALB/c. Given the availability of multiple genetically altered strains of mice in the C57BL/6 background, it would be useful to define P1A T-cell epitopes presented by the H-2b haplotype, to facilitate more refined mechanistic studies., Methods: We employed a heterologous prime-boost vaccination strategy based on a chimpanzee adenovirus (ChAdOx1) and a modified vaccinia Ankara (MVA) encoding P1A, to induce P1A-specific T-cell responses in C57BL/6 mice. Vaccine-induced responses were measured by intracellular cytokine staining and multiparameter flow cytometry. We mapped the immunogenic CD8 epitope and cloned the cognate T-cell receptor (TCR), which we used for adoptive cell therapy., Results: ChAdOx1/MVA-P1A vaccination induces a strong P1A-specific CD8+ T-cell response in C57BL/6 mice. This response is directed against a single 9-amino acid peptide with sequence FAVVTTSFL, corresponding to P1A amino acids 43-51. It is presented by H-2Db . P1A vaccination, especially with ChAdOx1 administered intramuscularly and MVA delivered intravenously, protected mice against P1A-expressing EL4 (EL4.P1A) tumor cell challenge. We identified and cloned four TCRs that are specific for the H-2Db -restricted P1A43-51 peptide. T cells transduced with these TCRs recognized EL4.P1A but not MC38.P1A and B16F10.P1A tumor cells, likely due to differences in the proteasome subtypes present in these cells. Adoptive transfer of these T cells in mice bearing EL4.P1A tumors reduced tumor growth and increased survival., Conclusions: We identified the first CD8+ T-cell epitope of the MAGE-type P1A tumor antigen presented in the H-2b background. This opens new perspectives for mechanistic studies dissecting MAGE-type specific antitumor immunity, making use of the wealth of genetically altered mouse strains available in the C57BL/6 background. This should facilitate the advancement of specific cancer immunotherapies., Competing Interests: Competing interests: BJVdE and CSKL are inventors on a patent that covers viral vectors and methods for the prevention and treatment of cancer. All other authors declare no conflict of interest., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)- Published
- 2024
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5. Multiplexed, image-based pooled screens in primary cells and tissues with PerturbView.
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Kudo T, Meireles AM, Moncada R, Chen Y, Wu P, Gould J, Hu X, Kornfeld O, Jesudason R, Foo C, Höckendorf B, Corrada Bravo H, Town JP, Wei R, Rios A, Chandrasekar V, Heinlein M, Chuong AS, Cai S, Lu CS, Coelho P, Mis M, Celen C, Kljavin N, Jiang J, Richmond D, Thakore P, Benito-Gutiérrez E, Geiger-Schuller K, Hleap JS, Kayagaki N, de Sousa E Melo F, McGinnis L, Li B, Singh A, Garraway L, Rozenblatt-Rosen O, Regev A, and Lubeck E
- Abstract
Optical pooled screening (OPS) is a scalable method for linking image-based phenotypes with cellular perturbations. However, it has thus far been restricted to relatively low-plex phenotypic readouts in cancer cell lines in culture due to limitations associated with in situ sequencing of perturbation barcodes. Here, we develop PerturbView, an OPS technology that leverages in vitro transcription to amplify barcodes before in situ sequencing, enabling screens with highly multiplexed phenotypic readouts across diverse systems, including primary cells and tissues. We demonstrate PerturbView in induced pluripotent stem cell-derived neurons, primary immune cells and tumor tissue sections from animal models. In a screen of immune signaling pathways in primary bone marrow-derived macrophages, PerturbView uncovered both known and novel regulators of NF-κB signaling. Furthermore, we combine PerturbView with spatial transcriptomics in tissue sections from a mouse xenograft model, paving the way to in situ screens with rich optical and transcriptomic phenotypes. PerturbView broadens the scope of OPS to a wide range of models and applications., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)
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- 2024
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6. Isoptericola haloaureus sp. nov., a dimorphic actinobacterium isolated from mangrove sediments of southeast India, implicating biosaline agricultural significance through nitrogen fixation and salt tolerance genes.
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Prathaban M, Prathiviraj R, Ravichandran M, Natarajan SD, Sobanaa M, Hari Krishna Kumar S, Chandrasekar V, and Selvin J
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- India, Wetlands, Fatty Acids metabolism, Fatty Acids analysis, Geologic Sediments microbiology, Bacterial Typing Techniques, Soil Microbiology, Phospholipids analysis, Sequence Analysis, DNA, Sodium Chloride metabolism, Actinobacteria genetics, Actinobacteria classification, Actinobacteria isolation & purification, Actinobacteria metabolism, Actinobacteria physiology, Phylogeny, RNA, Ribosomal, 16S genetics, Salt Tolerance, DNA, Bacterial genetics, Base Composition, Nitrogen Fixation
- Abstract
Strain MP-1014
T , an obligate halophilic actinobacterium, was isolated from the mangrove soil of Thandavarayancholanganpettai, Tamil Nadu, India. A polyphasic approach was utilized to explore its phylogenetic position completely. The isolate was Gram-positive, filamentous, non-motile, and coccoid in older cultures. Ideal growth conditions were seen at 30 °C and pH 7.0, with 5% NaCl (W/V), and the DNA G + C content was 73.3%. The phylogenic analysis of this strain based upon 16S rRNA gene sequence revealed 97-99.8% similarity to the recognized species of the genus Isoptericola. Strain MP-1014T exhibits the highest similarity to I. sediminis JC619T (99.7%), I. chiayiensis KCTC19740T (98.9%), and subsequently to I. halotolerans KCTC19646T (98.6%), when compared with other members within the Isoptericola genus (< 98%). ANI scores of strain MP-1014T are 86.4%, 84.2%, and 81.5% and dDDH values are 59.7%, 53.6%, and 34.8% with I. sediminis JC619T , I. chiayiensis KCTC19740T and I. halotolerans KCTC19646T respectively. The major polar lipids of the strain MP-1014T were phosphatidylinositol, phosphatidylglycerol, diphosphotidylglycerol, two unknown phospholipids, and glycolipids. The predominant respiratory menaquinones were MK9 (H4 ) and MK9 (H2 ). The major fatty acids were anteiso-C15:0 , anteiso-C17:0 , iso-C14:0 , C15:0, and C16:0 . Also, initial genome analysis of the organism suggests it as a biostimulant for enhancing agriculture in saline environments. Based on phenotypic and genetic distinctiveness, the strain MP-1014T represents the novel species of the genus Isoptericola assigned Isoptericola haloaureus sp. nov., is addressed by the strain MP-1014T , given its phenotypic, phylogenetic, and hereditary uniqueness. The type strain is MP-1014T [(NCBI = OP672482.1 = GCA_036689775.1) ATCC = BAA 2646T ; DSMZ = 29325T ; MTCC = 13246T ]., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)- Published
- 2024
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7. Synthesis and characterization of 3,4-dihydroxyphenyl acetic acid esters and study of their efficacy in bulk fish oil.
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Arunachalam SS, Chandrasekar V, and Belur PD
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- Esterification, Antioxidants, Fish Oils, Esters, Phthalic Acids
- Abstract
Lipophilization of natural antioxidants is a proven strategy to enhance the solubility in bulk oil systems, thereby increasing their efficacy against oxidative degradation. This study aims to synthesize esters of 3,4-dihydroxyphenylacetic acid (3,4-DHPA) using Amberlyst-15 and to study the application of these esters in refined fish oil. Lipophilic esters were synthesized by esterification and transesterification of 3,4-DHPA in various solvent systems. Esters of methanol, butanol and hexanol were obtained with percent conversion of 81.1, 69.3 and 78.8 respectively, and were subjected to molecular characterization and in vitro oxidant assays. The 3,4-DHPA and its methyl ester showed 36% reduction in the TOTOX value over 30 days of storage. The length of the acyl chain in the ester was found to exert a high influence on its efficacy and lipophilicity. This is the first report of 3,4-DHPA and its lipophilic esters studied for enhancing the oxidative stability of fish oil., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)
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- 2024
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8. In Vitro Wound Healing and Anticancer Effects of Ixora coccinea in Malignant Melanoma Cell Lines.
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R JS, Chandrasekar V, D C, Rajendran K, Kindo AJ, and Swaminathan J
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Background Ixora coccinea is a medicinal plant with many active constituents that are responsible for wound healing and have anticancer properties. Herbal extracts increase the mechanisms related to wound healing, like blood clotting, fighting infection, and epithelialization. The effect responsible for this property may be the presence of phytoconstituents like flavonoids, polyphenols, and alkaloids. Many researchers have evaluated the wound-healing effect of I. coccinea leaf extract in aqueous methanol. This study aimed to determine the in vitro wound healing and anticancer efficacy of I. coccinea leaf ethyl acetate extract and evaluate the in silico docking of the selected phytoconstituents of I. coccinea in the 2vcj protein . Materials and methods The human dermal fibroblast cell line was used to determine the rates of cell migration and proliferation for evaluating the wound-healing effect of the I. coccinea leaf ethyl acetate fraction. 4',6-diamidino-2-phenylindole (DAPI) fluorescence labeling was used to estimate the rate of cell migration. The one-step TUNEL (TdT-mediated dUTP Nick-End Labeling) in situ apoptosis kit and the annexin V-FITC/7-AAD apoptosis kit were used to perform DNA damage assays in the malignant melanoma cell line. The ethyl acetate fraction of I. coccinea leaves was analyzed for its impact on wound healing markers, including keratin-10, keratin-14, type IV collagen, and α-SMA. Results The wound-healing nature was interesting in the ethyl acetate fraction at doses of 50 µg/mL and 100 µg/mL. Both studies involved in the DNA damage study against malignant melanoma cell lines showed the cleavage of apoptotic cancer cells, which was detected using a fluorescence microscope. When compared with the control, a dose of 100 μg/ml of ethyl acetate fraction from the leaves of I. coccinea showed fibroblast migration of cells into the wound area. The statistical values were considered significant at the level of P < 0.05. An in silico docking study on the 2vcj protein revealed that selected phytoconstituents of I. coccinea resulted in good docking scores to inhibit Hsp90. Conclusion I. coccinea ethyl acetate leaf extract can inhibit the growth of malignant melanoma cell lines and promote wound healing, as shown by the study results. It might be a viable therapeutic modality for skin cancer., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, R et al.)
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- 2024
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9. Secure malicious node detection in flying ad-hoc networks using enhanced AODV algorithm.
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Chandrasekar V, Shanmugavalli V, Mahesh TR, Shashikumar R, Borah N, Kumar VV, and Guluwadi S
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In wireless networking, the security of flying ad hoc networks (FANETs) is a major issue, and the use of drones is growing every day. A distributed network is created by a drone network in which nodes can enter and exit the network at any time. Because malicious nodes generate bogus identifiers, FANET is unstable. In this research study, we proposed a threat detection method for detecting malicious nodes in the network. The proposed method is found to be most effective compared to other methods. Malicious nodes fill the network with false information, thereby reducing network performance. The secure ad hoc on-demand distance vector (AODV) that has been suggested algorithm is used for detecting and isolating a malicious node in FANET. In addition, because temporary flying nodes are vulnerable to attacks, trust models based on direct or indirect reliability similar to trusted neighbors have been incorporated to overcome the vulnerability of malicious/selfish harassment. A node belonging to the malicious node class is disconnected from the network and is not used to forward or forward another message. The FANET security performance is measured by throughput, packet loss and routing overhead with the conventional algorithms of AODV (TAODV) and reliable AODV secure AODV power consumption decreased by 16.5%, efficiency increased by 7.4%, and packet delivery rate decreased by 9.1% when compared to the second ranking method. Reduced packet losses and routing expenses by 9.4%. In general, the results demonstrate that, in terms of energy consumption, throughput, delivered packet rate, the number of lost packets, and routing overhead, the proposed secure AODV algorithm performs better than the most recent, cutting-edge algorithms., (© 2024. The Author(s).)
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- 2024
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10. In Vitro Evaluation of Extracts From Ixora Species for a Potential Phytosomal Formulation.
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Rajayan JS, Chandrasekar V, Duraipandian C, and Rajendran K
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Background Ixora species are perennial shrubs and flowering plants belonging to the family Rubiaceae . The leaf and flower parts of Ixora coccinea ( I. coccinea ) and Ixora alba ( I. alba ) were aimed at isolating their active fractions. The present study was to determine in vitro antitumor activity against malignant melanoma cell lines for phytosome formulation. Materials and methods Two species, I. coccinea (red flowers and leaves) and I. alba (white flowers and leaves), were selected, and this study focused on determining the active fraction by comparing the in vitro antimicrobial and antioxidant potentials of petroleum ether, chloroform, ethyl acetate, and hydroalcoholic (ethanol:water, 70:30 v/v) extracts. The identified potent extract was subjected to in vitro anticancer activity in malignant melanoma cell lines. Results A phytochemical study revealed phytosterols, flavonoids, proteins, amino acids, alkaloids, carbohydrates, phenols, tannins, and diterpenes. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to evaluate the antioxidant effect of I. coccinea and I. alba leaf and flower extracts. In the DPPH assay, I. coccinea flower hydroalcoholic extract (ICFHA) had an IC
50 value of 248.99 µg/mL, and I. coccinea leaf hydroalcoholic extract (ICLHA) had an IC50 value of 268.87 µg/mL. These two extracts had a lower value with a higher antioxidant effect. In the total antioxidant assay, I. coccinea leaf ethyl acetate extract (ICLEA) and I. coccinea leaf chloroform extract (ICLCE) have 77.4 ± 0.05 and 68.9 ± 0.03 mg of ascorbic acid equivalent per gm of extract, respectively. These two extracts exhibited a high antioxidant effect. The antimicrobial potential was evaluated using selected bacterial and fungal strains using the agar-well diffusion method. Petroleum ether and chloroform extracts of I. coccinea and I. alba leaves and flowers did not possess antimicrobial activity with any of the bacterial or fungal strains. An ethyl acetate extract and a hydroalcoholic extract of I. coccinea leaves and flowers showed antimicrobial activity against Enterococcus faecalis , Candida albicans , and Staphylococcus aureus . An ethyl acetate extract of I. coccinea flower and a hydroalcoholic extract of I. alba leaf showed a significant zone of inhibition when compared with standard chloramphenicol for all three selected strains, which may be due to the presence of active phytoconstituents. ICLHA showed a MIC of ≤300 µg/mL for Enterococcus faecalis and Staphylococcus aureus and ≤400 µg/mL for Candida albicans microbial strains. The high total flavonoid content was reported in ICLEA at 771.31 µg/mL and in I. coccinea flower ethyl acetate extract (ICFEA) at 694.69 µg/mL. High-performance thin layer chromatography (HPTLC) analysis showed a high quercetin (QCE) content in the ICLEA extract. To prove the in vitro skin anticancer activity, an MTT assay was performed for the ICLEA extract in a malignant melanoma cell line, and the IC50 value was reported as 7.96 µg/mL. Conclusion I. coccinea leaf ethyl acetate extract revealed a significant total flavonoid content in analysis through the aluminum chloride method, and the presence of a high QCE content was confirmed by HPTLC analysis. The in vitro skin anticancer activity of ICLEA was confirmed by the MTT assay; therefore, it was concluded that the ICLEA extract was a potent fraction and was selected to develop a phytosome., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Rajayan et al.)- Published
- 2024
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11. Green HPLC Method for Simultaneous Analysis of Three Natural Antioxidants by Analytical Quality by Design.
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Jonnalagadda R, Rathinam S, Nagappan K, and Chandrasekar V
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- Chromatography, High Pressure Liquid, Silybin, Glutathione, Solvents, Antioxidants, Curcumin
- Abstract
Background: Glutathione, silybin, and curcumin are well-known potential antioxidants that are recommended as adjuvant therapy in cancer treatment., Objective: Based on the principles of Analytical Quality by Design (AQbD) and green analytical chemistry, a simple, robust, and environmentally benign HPLC method for the simultaneous estimation of glutathione, silybin, and curcumin in bulk and formulation was performed., Method: Elution was achieved by an Agilent Eclipse XDB C18 (150 mm × 4.6 mm id, 3.5 μm) column using a gradient mobile phase composed of ethanol-water pH 6.7 (with 0.1%, v/v orthophosphoric acid) and 1.07 mL/min flow rate with PDA detection at 215 nm. Critical method variables were identified by risk assessment using an Ishikawa diagram, and multivariate optimization of the experimental conditions for the HPLC technique was accomplished by central composite design using design of experiments (DoE) software., Results: The separation was achieved within 15 min, where the retention time of glutathione, silybin, and curcumin were 3.3, 4.9, and 7.3 min, respectively. The standard curve was linear in the range of 3.75-26.25 µg/mL for glutathione, 62.50-437.50 µg/mL for silybin, and 12.5-87.50 µg/mL for curcumin. The developed method was validated as per ICH guidelines Q2 (R1), and all the parameters are within specified limits., Conclusions: The proposed method is simple, precise, and robust, which can be employed for routine analysis and also concluded to be a greener approach according to AGREE, Green Analytical Procedure Index, and analytical eco-scale tools., Highlights: The chosen antioxidants were evaluated for the very first time simultaneously using the chromatographic technique in bulk and dosage forms employing green solvents. The peak purity of all three compounds was studied using a PDA detector. Wastage was reduced in terms of time, cost, and solvents by employing AQbD elements and tools. Complete application of environmentally sustainable safe solvents were employed., (© The Author(s) 2023. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)
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- 2024
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12. Coherent Doppler LIDAR with long-duration frequency-modulated pulses for wind sensing.
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Yoshikawa E, Yamasuge H, Aoki M, Iwai H, Nakano T, Oikawa H, Ushio T, Ishii S, and Chandrasekar V
- Abstract
A coherent Doppler LIDAR (CDL) with long-duration frequency-modulated pulses was demonstrated and validated by analyzing the data observed by a prototype. In traditional CDL using short-duration single-frequency pulses (PCDL; pulsed CDL), there exists a trade-off relationship between distance and velocity resolution. Meanwhile, in earlier work, a theoretical framework of CDL using long-duration frequency-modulated pulses (FMCDL; frequency-modulated CDL) was put forth to eliminate the trade-off. We developed the prototype to be operated as both a PCDL and FMCDL. Analyses of data observed by the PCDL and FMCDL modes showed that the FMCDL worked in good agreement with the PCDL for wind ranging and velocimetry. Furthermore, the performance of the FMCDL in terms of received power and resolution of distance and velocity was quantitatively consistent with ones theoretically expected.
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- 2023
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13. Integrative toxicogenomics: Advancing precision medicine and toxicology through artificial intelligence and OMICs technology.
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Singh AV, Chandrasekar V, Paudel N, Laux P, Luch A, Gemmati D, Tisato V, Prabhu KS, Uddin S, and Dakua SP
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- Humans, Toxicogenetics, Algorithms, Technology, Artificial Intelligence, Precision Medicine
- Abstract
More information about a person's genetic makeup, drug response, multi-omics response, and genomic response is now available leading to a gradual shift towards personalized treatment. Additionally, the promotion of non-animal testing has fueled the computational toxicogenomics as a pivotal part of the next-gen risk assessment paradigm. Artificial Intelligence (AI) has the potential to provid new ways analyzing the patient data and making predictions about treatment outcomes or toxicity. As personalized medicine and toxicogenomics involve huge data processing, AI can expedite this process by providing powerful data processing, analysis, and interpretation algorithms. AI can process and integrate a multitude of data including genome data, patient records, clinical data and identify patterns to derive predictive models anticipating clinical outcomes and assessing the risk of any personalized medicine approaches. In this article, we have studied the current trends and future perspectives in personalized medicine & toxicology, the role of toxicogenomics in connecting the two fields, and the impact of AI on personalized medicine & toxicology. In this work, we also study the key challenges and limitations in personalized medicine, toxicogenomics, and AI in order to fully realize their potential., Competing Interests: Conflict of interest The authors declare no competing interest of interest at this point., (Copyright © 2023 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)
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- 2023
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14. Pneumomediastinum in COVID-19 disease: Clinical review with emphasis on emergency management.
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Ganessane E, Devendiran A, Ramesh S, Uthayakumar A, Chandrasekar V, Sadasivam AS, Nathan B, and Ayyan M
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Pneumomediastinum can be primary (spontaneous) or secondary to iatrogenic, traumatic, and non-traumatic causes. The incidence of spontaneous and secondary pneumomediastinum is higher in patients with coronavirus disease 2019 (COVID-19) compared to the general population. So, pneumomediastinum should be considered in the differential diagnosis of any patient with COVID-19 presenting with chest pain and breathlessness. A high level of suspicion is required to diagnose this condition promptly. Unlike in other disease conditions, pneumomediastinum in COVID-19 has a complicated course with higher mortality in intubated patients. No guidelines exist for managing pneumomediastinum patients with COVID-19. Therefore, emergency physicians should be aware of the various treatment modalities besides conservative management for pneumomediastinum and life-saving interventions for tension pneumomediastinum., (© 2023 The Authors. JACEP Open published by Wiley Periodicals LLC on behalf of American College of Emergency Physicians.)
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- 2023
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15. Probing the synergistic effects of rutin and rutin ester on the oxidative stability of sardine oil.
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Chandrasekar V, Arunachalam SS, Hari H, Shinkar A, Belur PD, and Iyyaswami R
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Multicomponent antioxidant mixture is proved to be highly effective in imparting oxidative stability to the edible oil. It is believed that the high efficacy of those mixtures is due to the synergistic effect exhibited by two or more components. The current study aims to analyse the synergistic effect of a flavonoid and its corresponding ester in improving the oxidative stability of n -3 PUFA rich sardine oil. The oxidative stability of rutin, esterified rutin and their combinations at three different concentrations was studied in sardine oil stored at 37 ºC for 12 days in contact with air under darkness. The combination of rutin and rutin ester showed maximum reduction of 54.2% in oxidation at 100 mg/kg and 150 mg/kg. Perhaps this is the first report on the synergistic effect of a flavonoid and its lipophilized ester for improving the oxidative stability of n -3 PUFA rich oil., Competing Interests: Conflicts of interestAuthors declare no conflict of interest., (© Association of Food Scientists & Technologists (India) 2022.)
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- 2022
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16. Micropatterned Neurovascular Interface to Mimic the Blood-Brain Barrier's Neurophysiology and Micromechanical Function: A BBB-on-CHIP Model.
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Singh AV, Chandrasekar V, Laux P, Luch A, Dakua SP, Zamboni P, Shelar A, Yang Y, Pandit V, Tisato V, and Gemmati D
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- Calcium metabolism, Claudins metabolism, Ligands, Neurophysiology, Tight Junction Proteins metabolism, Blood-Brain Barrier metabolism, Endothelial Cells metabolism
- Abstract
A hybrid blood-brain barrier (BBB)-on-chip cell culture device is proposed in this study by integrating microcontact printing and perfusion co-culture to facilitate the study of BBB function under high biological fidelity. This is achieved by crosslinking brain extracellular matrix (ECM) proteins to the transwell membrane at the luminal surface and adapting inlet-outlet perfusion on the porous transwell wall. While investigating the anatomical hallmarks of the BBB, tight junction proteins revealed tortuous zonula occludens (ZO-1), and claudin expressions with increased interdigitation in the presence of astrocytes were recorded. Enhanced adherent junctions were also observed. This junctional phenotype reflects in-vivo-like features related to the jamming of cell borders to prevent paracellular transport. Biochemical regulation of BBB function by astrocytes was noted by the transient intracellular calcium effluxes induced into endothelial cells. Geometry-force control of astrocyte-endothelial cell interactions was studied utilizing traction force microscopy (TFM) with fluorescent beads incorporated into a micropatterned polyacrylamide gel (PAG). We observed the directionality and enhanced magnitude in the traction forces in the presence of astrocytes. In the future, we envisage studying transendothelial electrical resistance (TEER) and the effect of chemomechanical stimulations on drug/ligand permeability and transport. The BBB-on-chip model presented in this proposal should serve as an in vitro surrogate to recapitulate the complexities of the native BBB cellular milieus.
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- 2022
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17. Cardiac tamponade due to right atrial rupture.
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Rajendran G, Babu GR, Chandrasekar V, Kagne R, and Nathan B
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Cardiac tamponade is a cardiac emergency that requires urgent intervention. Cardiac tamponade due to penetrating cardiac injury requires urgent thoracotomy. As per the guidelines, pericardiocentesis can be done as a bridge to thoracotomy. However, no clear guidelines exist on the management of cardiac tamponade due to blunt cardiac injury. In the following case report, we propose a management plan for blunt cardiac injury in the emergency department. In the following case report, we describe a patient with a road traffic accident who had a blunt cardiac injury and had cardiac tamponade for whom we did not do emergency pericardiocentesis. Instead, we managed the patient with iv fluids and blood transfusion and the patient was taken up for immediate emergency thoracotomy. Not all cardiac tamponade requires pericardiocentesis. Cardiac tamponade due to injury to the low-pressure system can be best managed by initial resuscitation followed by emergency thoracotomy. We also propose a management plan for managing a patient with cardiac tamponade due to blunt cardiac injury when the injury can be visible in the low-pressure chambers., Competing Interests: None declared., (Copyright: © 2022 Turkish Journal of Emergency Medicine.)
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- 2022
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18. Chemical Characterization and Non-targeted Analysis of Medical Device Extracts: A Review of Current Approaches, Gaps, and Emerging Practices.
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Sussman EM, Oktem B, Isayeva IS, Liu J, Wickramasekara S, Chandrasekar V, Nahan K, Shin HY, and Zheng J
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- Animals, Humans, Drug Contamination prevention & control, Risk Assessment
- Abstract
The developers of medical devices evaluate the biocompatibility of their device prior to FDA's review and subsequent introduction to the market. Chemical characterization, described in ISO 10993-18:2020, can generate information for toxicological risk assessment and is an alternative approach for addressing some biocompatibility end points (e.g., systemic toxicity, genotoxicity, carcinogenicity, reproductive/developmental toxicity) that can reduce the time and cost of testing and the need for animal testing. Additionally, chemical characterization can be used to determine whether modifications to the materials and manufacturing processes alter the chemistry of a patient-contacting device to an extent that could impact device safety. Extractables testing is one approach to chemical characterization that employs combinations of non-targeted analysis, non-targeted screening, and/or targeted analysis to establish the identities and quantities of the various chemical constituents that can be released from a device. Due to the difficulty in obtaining a priori information on all the constituents in finished devices, information generation strategies in the form of analytical chemistry testing are often used. Identified and quantified extractables are then assessed using toxicological risk assessment approaches to determine if reported quantities are sufficiently low to overcome the need for further chemical analysis, biological evaluation of select end points, or risk control. For extractables studies to be useful as a screening tool, comprehensive and reliable non-targeted methods are needed. Although non-targeted methods have been adopted by many laboratories, they are laboratory-specific and require expensive analytical instruments and advanced technical expertise to perform. In this Perspective, we describe the elements of extractables studies and provide an overview of the current practices, identified gaps, and emerging practices that may be adopted on a wider scale in the future. This Perspective is outlined according to the steps of an extractables study: information gathering, extraction, extract sample processing, system selection, qualification, quantification, and identification.
- Published
- 2022
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19. Impact of ER Stress and ER-Mitochondrial Crosstalk in Huntington's Disease.
- Author
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Maity S, Komal P, Kumar V, Saxena A, Tungekar A, and Chandrasekar V
- Subjects
- Animals, Biomarkers, Carrier Proteins metabolism, Disease Susceptibility, Drug Development, Humans, Huntington Disease pathology, Huntington Disease therapy, Membrane Proteins metabolism, Molecular Targeted Therapy, Protein Binding, Stress, Physiological, Endoplasmic Reticulum metabolism, Endoplasmic Reticulum Stress, Huntington Disease etiology, Huntington Disease metabolism, Mitochondria metabolism, Signal Transduction
- Abstract
Accumulation of misfolded proteins is a common phenomenon of several neurodegenerative diseases. The misfolding of proteins due to abnormal polyglutamine (PolyQ) expansions are linked to the development of PolyQ diseases including Huntington's disease (HD). Though the genetic basis of PolyQ repeats in HD remains prominent, the primary molecular basis mediated by PolyQ toxicity remains elusive. Accumulation of misfolded proteins in the ER or disruption of ER homeostasis causes ER stress and activates an evolutionarily conserved pathway called Unfolded protein response (UPR). Protein homeostasis disruption at organelle level involving UPR or ER stress response pathways are found to be linked to HD. Due to dynamic intricate connections between ER and mitochondria, proteins at ER-mitochondria contact sites (mitochondria associated ER membranes or MAMs) play a significant role in HD development. The current review aims at highlighting the most updated information about different UPR pathways and their involvement in HD disease progression. Moreover, the role of MAMs in HD progression has also been discussed. In the end, the review has focused on the therapeutic interventions responsible for ameliorating diseased states via modulating either ER stress response proteins or modulating the expression of ER-mitochondrial contact proteins.
- Published
- 2022
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20. Author Correction: Aberrant chromatin landscape following loss of the H3.3 chaperone Daxx in haematopoietic precursors leads to Pu.1-mediated neutrophilia and inflammation.
- Author
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Gerber JP, Russ J, Chandrasekar V, Offermann N, Lee HM, Spear S, Guzzi N, Maida S, Pattabiraman S, Zhang R, Kayvanjoo AH, Datta P, Kasturiarachchi J, Sposito T, Izotova N, Händler K, Adams PD, Marafioti T, Enver T, Wenzel J, Beyer M, Mass E, Bellodi C, Schultze JL, Capasso M, Nimmo R, and Salomoni P
- Published
- 2022
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21. Aberrant chromatin landscape following loss of the H3.3 chaperone Daxx in haematopoietic precursors leads to Pu.1-mediated neutrophilia and inflammation.
- Author
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Gerber JP, Russ J, Chandrasekar V, Offermann N, Lee HM, Spear S, Guzzi N, Maida S, Pattabiraman S, Zhang R, Kayvanjoo AH, Datta P, Kasturiarachchi J, Sposito T, Izotova N, Händler K, Adams PD, Marafioti T, Enver T, Wenzel J, Beyer M, Mass E, Bellodi C, Schultze JL, Capasso M, Nimmo R, and Salomoni P
- Subjects
- Animals, Autoimmune Diseases genetics, Autoimmune Diseases pathology, B-Lymphocytes cytology, Cell Line, Chromatin genetics, Hematopoietic Stem Cells cytology, Histones metabolism, Humans, Inflammation pathology, Leukocyte Disorders pathology, Mice, Mice, Inbred C57BL, Mice, Knockout, Retroelements genetics, Skin Diseases genetics, Skin Diseases immunology, Skin Diseases pathology, Chromatin pathology, Co-Repressor Proteins genetics, Leukocyte Disorders congenital, Molecular Chaperones genetics, Myelopoiesis genetics, Proto-Oncogene Proteins metabolism, Trans-Activators metabolism
- Abstract
Defective silencing of retrotransposable elements has been linked to inflammageing, cancer and autoimmune diseases. However, the underlying mechanisms are only partially understood. Here we implicate the histone H3.3 chaperone Daxx, a retrotransposable element repressor inactivated in myeloid leukaemia and other neoplasms, in protection from inflammatory disease. Loss of Daxx alters the chromatin landscape, H3.3 distribution and histone marks of haematopoietic progenitors, leading to engagement of a Pu.1-dependent transcriptional programme for myelopoiesis at the expense of B-cell differentiation. This causes neutrophilia and inflammation, predisposing mice to develop an autoinflammatory skin disease. While these molecular and phenotypic perturbations are in part reverted in animals lacking both Pu.1 and Daxx, haematopoietic progenitors in these mice show unique chromatin and transcriptome alterations, suggesting an interaction between these two pathways. Overall, our findings implicate retrotransposable element silencing in haematopoiesis and suggest a cross-talk between the H3.3 loading machinery and the pioneer transcription factor Pu.1., (© 2021. The Author(s).)
- Published
- 2021
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22. Advances in Smoking Related In Vitro Inhalation Toxicology: A Perspective Case of Challenges and Opportunities from Progresses in Lung-on-Chip Technologies.
- Author
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Singh AV, Maharjan RS, Kromer C, Laux P, Luch A, Vats T, Chandrasekar V, Dakua SP, and Park BW
- Subjects
- Cell Culture Techniques instrumentation, Cell Culture Techniques methods, Electronic Nicotine Delivery Systems, Humans, Lung cytology, Microfluidics instrumentation, Robotics, Lab-On-A-Chip Devices, Microfluidics methods, Particulate Matter toxicity, Tobacco Products toxicity, Volatile Organic Compounds toxicity
- Abstract
The inhalation toxicology of multifaceted particulate matter from the environment, cigarette smoke, and e-cigarette liquid vapes is a major research topic concerning the adverse effect of these items on lung tissue. In vitro air-liquid interface (ALI) culture models hold more potential in an inhalation toxicity assessment. Apropos to e-cigarette toxicity, the multiflavor components of the vapes pose a complex experimental bottleneck. While an appropriate ALI setup has been one part of the focus to overcome this, parallel attention towards the development of an ideal exposure system has pushed the field forward. With the advent of microfluidic devices, lung-on-chip (LOC) technologies show enormous opportunities in in vitro smoke-related inhalation toxicity. In this review, we provide a framework, establish a paradigm about smoke-related inhalation toxicity testing in vitro, and give a brief overview of breathing LOC experimental design concepts. The capabilities with optimized bioengineering approaches and microfluidics and their fundamental pros and cons are presented with specific case studies. The LOC model can imitate the structural, functional, and mechanical properties of human alveolar-capillary interface and are more reliable than conventional in vitro models. Finally, we outline current perspective challenges as well as opportunities of future development to smoking lungs-on-chip technologies based on advances in soft robotics, machine learning, and bioengineering.
- Published
- 2021
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23. Emerging Application of Nanorobotics and Artificial Intelligence To Cross the BBB: Advances in Design, Controlled Maneuvering, and Targeting of the Barriers.
- Author
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Singh AV, Chandrasekar V, Janapareddy P, Mathews DE, Laux P, Luch A, Yang Y, Garcia-Canibano B, Balakrishnan S, Abinahed J, Al Ansari A, and Dakua SP
- Subjects
- Artificial Intelligence, Biological Transport, Blood-Brain Barrier, Drug Delivery Systems, Humans, Alzheimer Disease, Nanoparticles
- Abstract
The blood-brain barrier (BBB) is a prime focus for clinicians to maintain the homeostatic function in health and deliver the theranostics in brain cancer and number of neurological diseases. The structural hierarchy and in situ biochemical signaling of BBB neurovascular unit have been primary targets to recapitulate into the in vitro modules. The microengineered perfusion systems and development in 3D cellular and organoid culture have given a major thrust to BBB research for neuropharmacology. In this review, we focus on revisiting the nanoparticles based bimolecular engineering to enable them to maneuver, control, target, and deliver the theranostic payloads across cellular BBB as nanorobots or nanobots. Subsequently we provide a brief outline of specific case studies addressing the payload delivery in brain tumor and neurological disorders (e.g., Alzheimer's disease, Parkinson's disease, multiple sclerosis, etc.). In addition, we also address the opportunities and challenges across the nanorobots' development and design. Finally, we address how computationally powered machine learning (ML) tools and artificial intelligence (AI) can be partnered with robotics to predict and design the next generation nanorobots to interact and deliver across the BBB without causing damage, toxicity, or malfunctions. The content of this review could be references to multidisciplinary science to clinicians, roboticists, chemists, and bioengineers involved in cutting-edge pharmaceutical design and BBB research.
- Published
- 2021
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24. Strategies for Rapid Risk Assessment of Color Additives Used in Medical Devices.
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Saylor DM, Chandrasekar V, Simon DD, Turner P, Markley LC, and Hood AM
- Abstract
Many polymeric medical devices contain color additives for differentiation or labeling. Although some additives can be toxic under certain conditions, the risk associated with the use of these additives in medical device applications is not well established, and evaluating their impact on device biocompatibility can be expensive and time consuming. Therefore, we have developed a framework to conduct screening-level risk assessments to aid in determining whether generating color additive exposure data and further risk evaluation are necessary. We first derive tolerable intake values that are protective for worst-case exposure to 8 commonly used color additives. Next, we establish a model to predict exposure limited only by the diffusive transport of the additive through the polymer matrix. The model is parameterized using a constitutive model for diffusion coefficient (D) as a function of molecular weight (Mw) of the color additive. After segmenting polymer matrices into 4 distinct categories, upper bounds on D(Mw) were determined based on available data for each category. The upper bounds and exposure predictions were validated independently to provide conservative estimates. Because both components (toxicity and exposure) are conservative, a ratio of tolerable intake to exposure in excess of one indicates acceptable risk. Application of this approach to typical colored polymeric materials used in medical devices suggests that additional color additive risk evaluation could be eliminated in a large percentage (≈90%) of scenarios., (Published by Oxford University Press on behalf of the Society of Toxicology 2019. This work is written by US Government employees and is in the public domain in the US.)
- Published
- 2019
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25. Targeting tumor phenotypic plasticity and metabolic remodeling in adaptive cross-drug tolerance.
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Goldman A, Khiste S, Freinkman E, Dhawan A, Majumder B, Mondal J, Pinkerton AB, Eton E, Medhi R, Chandrasekar V, Rahman MM, Ichimura T, Gopinath KS, Majumder P, Kohandel M, and Sengupta S
- Subjects
- Glucosephosphate Dehydrogenase metabolism, Humans, MCF-7 Cells, Neoplasm Metastasis, Neoplasm Proteins metabolism, Antineoplastic Agents pharmacology, Drug Delivery Systems, Enzyme Inhibitors pharmacology, Glucose metabolism, Glucosephosphate Dehydrogenase antagonists & inhibitors, Neoplasm Proteins antagonists & inhibitors, Neoplasms drug therapy, Neoplasms metabolism, Neoplasms pathology, Pentose Phosphate Pathway drug effects
- Abstract
Metastable phenotypic state transitions in cancer cells can lead to the development of transient adaptive resistance or tolerance to chemotherapy. Here, we report that the acquisition of a phenotype marked by increased abundance of CD44 (CD44
Hi ) by breast cancer cells as a tolerance response to routinely used cytotoxic drugs, such as taxanes, activated a metabolic switch that conferred tolerance against unrelated standard-of-care chemotherapeutic agents, such as anthracyclines. We characterized the sequence of molecular events that connected the induced CD44Hi phenotype to increased activity of both the glycolytic and oxidative pathways and glucose flux through the pentose phosphate pathway (PPP). When given in a specific order, a combination of taxanes, anthracyclines, and inhibitors of glucose-6-phosphate dehydrogenase (G6PD), an enzyme involved in glucose metabolism, improved survival in mouse models of breast cancer. The same sequence of the three-drug combination reduced the viability of patient breast tumor samples in an explant system. Our findings highlight a convergence between phenotypic and metabolic state transitions that confers a survival advantage to cancer cells against clinically used drug combinations. Pharmacologically targeting this convergence could overcome cross-drug tolerance and could emerge as a new paradigm in the treatment of cancer., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)- Published
- 2019
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26. A designer self-assembled supramolecule amplifies macrophage immune responses against aggressive cancer.
- Author
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Kulkarni A, Chandrasekar V, Natarajan SK, Ramesh A, Pandey P, Nirgud J, Bhatnagar H, Ashok D, Ajay AK, and Sengupta S
- Subjects
- Animals, Cell Line, Tumor, Cells, Cultured, Drug Design, Female, Macromolecular Substances chemistry, Macromolecular Substances pharmacology, Macrophage Colony-Stimulating Factor chemistry, Macrophage Colony-Stimulating Factor metabolism, Macrophages immunology, Male, Mice, Mice, Inbred BALB C, RAW 264.7 Cells, Receptors, Granulocyte-Macrophage Colony-Stimulating Factor chemistry, Receptors, Granulocyte-Macrophage Colony-Stimulating Factor metabolism, Receptors, Immunologic chemistry, Receptors, Immunologic metabolism, Antineoplastic Agents chemistry, Antineoplastic Agents pharmacology, Macrophages drug effects, Neoplasms therapy
- Abstract
Effectively activating macrophages that can 'eat' cancer cells is challenging. In particular, cancer cells secrete macrophage colony stimulating factor (MCSF), which polarizes tumour-associated macrophages from an antitumour M1 phenotype to a pro-tumourigenic M2 phenotype. Also, cancer cells can express CD47, an 'eat me not' signal that ligates with the signal regulatory protein alpha (SIRPα) receptor on macrophages to prevent phagocytosis. Here, we show that a supramolecular assembly consisting of amphiphiles inhibiting the colony stimulating factor 1 receptor (CSF-1R) and displaying SIRPα-blocking antibodies with a drug-to-antibody ratio of 17,000 can disable both mechanisms. The supramolecule homes onto SIRPα on macrophages, blocking the CD47-SIRPα signalling axis while sustainedly inhibiting CSF-1R. The supramolecule enhances the M2-to-M1 repolarization within the tumour microenvironment, and significantly improves antitumour and antimetastatic efficacies in two aggressive animal models of melanoma and breast cancer, with respect to clinically available small-molecule and biologic inhibitors of CSF-1R signalling. Simultaneously blocking the CD47-SIRPα and MCSF-CSF-1R signalling axes may constitute a promising immunotherapy., Competing Interests: Competing interests: SS is a cofounder and holds equity in Akamara Therapeutics Inc. which is developing supramolecular therapeutics.
- Published
- 2018
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27. Characterizing the free volume of ultrahigh molecular weight polyethylene to predict diffusion coefficients in orthopedic liners.
- Author
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Ludwig KB, Chandrasekar V, Saylor DM, Van Citters DW, Reinitz SD, Forrey C, McDermott MK, Wickramasekara S, and Janes DW
- Subjects
- Humans, Coated Materials, Biocompatible chemistry, Hip Prosthesis, Materials Testing, Polyethylenes chemistry
- Abstract
Liners used in orthopedic devices are often made from ultrahigh molecular weight polyethylene (UHMWPE). A general predictive capability for transport coefficients of small molecules in UHMWPE does not exist, making it difficult to assess properties associated with leaching or uptake of small molecules. To address this gap, we describe here how a form of the Vrentas-Duda free volume model can be used to predict upper-bound diffusion coefficients (D) of arbitrary molecules within UHMWPE on the basis of their size and shape. Within this framework, the free-volume microstructure of UHMWPE is defined by analysis of a curated set of model diffusants. We determined an upper limit on D for vitamin E, a common antioxidant added to UHMWPE, to be 7.1 × 10
-12 cm2 s-1 . This means that a liner that contains 0.1 wt % or less Vitamin E and has <120 cm2 patient contacting surface area would elute <100 µg/day of vitamin E. Additionally, the model predicts that squalene and cholesterol-two pro-oxidizing biological compounds-do not penetrate over 820 µm into UHMWPE liners over the course of 5 years because their D is ≤7.1 × 10-12 cm2 s-1 . © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2393-2402, 2018., (© 2017 Wiley Periodicals, Inc.)- Published
- 2018
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28. Predicting patient exposure to nickel released from cardiovascular devices using multi-scale modeling.
- Author
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Saylor DM, Craven BA, Chandrasekar V, Simon DD, Brown RP, and Sussman EM
- Subjects
- Animals, Swine, Alloys adverse effects, Alloys pharmacokinetics, Models, Biological, Myocardium metabolism, Myocardium pathology, Nickel adverse effects, Nickel pharmacokinetics, Septal Occluder Device adverse effects
- Abstract
Many cardiovascular device alloys contain nickel, which if released in sufficient quantities, can lead to adverse health effects. However, in-vivo nickel release from implanted devices and subsequent biodistribution of nickel ions to local tissues and systemic circulation are not well understood. To address this uncertainty, we have developed a multi-scale (material, tissue, and system) biokinetic model. The model links nickel release from an implanted cardiovascular device to concentrations in peri-implant tissue, as well as in serum and urine, which can be readily monitored. The model was parameterized for a specific cardiovascular implant, nitinol septal occluders, using in-vitro nickel release test results, studies of ex-vivo uptake into heart tissue, and in-vivo and clinical measurements from the literature. Our results show that the model accurately predicts nickel concentrations in peri-implant tissue in an animal model and in serum and urine of septal occluder patients. The congruity of the model with these data suggests it may provide useful insight to establish nickel exposure limits and interpret biomonitoring data. Finally, we use the model to predict local and systemic nickel exposure due to passive release from nitinol devices produced using a wide range of manufacturing processes, as well as general relationships between release rate and exposure. These relationships suggest that peri-implant tissue and serum levels of nickel will remain below 5 μg/g and 10 μg/l, respectively, in patients who have received implanted nitinol cardiovascular devices provided the rate of nickel release per device surface area does not exceed 0.074 μg/(cm
2 d) and is less than 32 μg/d in total., Statement of Significance: The uncertainty in whether in-vitro tests used to evaluate metal ion release from medical products are representative of clinical environments is one of the largest roadblocks to establishing the associated patient risk. We have developed and validated a multi-scale biokinetic model linking nickel release from cardiovascular devices in-vivo to both peri-implant and systemic levels. By providing clinically relevant exposure estimates, the model vastly improves the evaluation of risk posed to patients by the nickel contained within these devices. Our model is the first to address the potential for local and systemic metal ion exposure due to a medical device and can serve as a basis for future efforts aimed at other metal ions and biomedical products., (Published by Elsevier Ltd.)- Published
- 2018
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29. Improving risk assessment of color additives in medical device polymers.
- Author
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Chandrasekar V, Janes DW, Forrey C, Saylor DM, Bajaj A, Duncan TV, Zheng J, Riaz Ahmed KB, and Casey BJ
- Subjects
- Risk Assessment, Anthraquinones chemistry, Anthraquinones pharmacokinetics, Coloring Agents chemistry, Coloring Agents pharmacokinetics, Models, Chemical, Nylons chemistry
- Abstract
Many polymeric medical device materials contain color additives which could lead to adverse health effects. The potential health risk of color additives may be assessed by comparing the amount of color additive released over time to levels deemed to be safe based on available toxicity data. We propose a conservative model for exposure that requires only the diffusion coefficient of the additive in the polymer matrix, D, to be specified. The model is applied here using a model polymer (poly(ether-block-amide), PEBAX 2533) and color additive (quinizarin blue) system. Sorption experiments performed in an aqueous dispersion of quinizarin blue (QB) into neat PEBAX yielded a diffusivity D = 4.8 × 10
-10 cm2 s-1 , and solubility S = 0.32 wt %. On the basis of these measurements, we validated the model by comparing predictions to the leaching profile of QB from a PEBAX matrix into physiologically representative media. Toxicity data are not available to estimate a safe level of exposure to QB, as a result, we used a Threshold of Toxicological Concern (TTC) value for QB of 90 µg/adult/day. Because only 30% of the QB is released in the first day of leaching for our film thickness and calculated D, we demonstrate that a device may contain significantly more color additive than the TTC value without giving rise to a toxicological concern. The findings suggest that an initial screening-level risk assessment of color additives and other potentially toxic compounds found in device polymers can be improved. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 310-319, 2018., (© 2017 Wiley Periodicals, Inc.)- Published
- 2018
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30. Conservative Exposure Predictions for Rapid Risk Assessment of Phase-Separated Additives in Medical Device Polymers.
- Author
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Chandrasekar V, Janes DW, Saylor DM, Hood A, Bajaj A, Duncan TV, Zheng J, Isayeva IS, Forrey C, and Casey BJ
- Subjects
- Consumer Product Safety, Diffusion, Equipment and Supplies, Indoles chemistry, Isoindoles, Risk Assessment, Coloring Agents chemistry, Models, Theoretical, Polymers chemistry
- Abstract
A novel approach for rapid risk assessment of targeted leachables in medical device polymers is proposed and validated. Risk evaluation involves understanding the potential of these additives to migrate out of the polymer, and comparing their exposure to a toxicological threshold value. In this study, we propose that a simple diffusive transport model can be used to provide conservative exposure estimates for phase separated color additives in device polymers. This model has been illustrated using a representative phthalocyanine color additive (manganese phthalocyanine, MnPC) and polymer (PEBAX 2533) system. Sorption experiments of MnPC into PEBAX were conducted in order to experimentally determine the diffusion coefficient, D = (1.6 ± 0.5) × 10
-11 cm2 /s, and matrix solubility limit, Cs = 0.089 wt.%, and model predicted exposure values were validated by extraction experiments. Exposure values for the color additive were compared to a toxicological threshold for a sample risk assessment. Results from this study indicate that a diffusion model-based approach to predict exposure has considerable potential for use as a rapid, screening-level tool to assess the risk of color additives and other small molecule additives in medical device polymers.- Published
- 2018
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31. A microfluidic platform for drug screening in a 3D cancer microenvironment.
- Author
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Pandya HJ, Dhingra K, Prabhakar D, Chandrasekar V, Natarajan SK, Vasan AS, Kulkarni A, and Shafiee H
- Subjects
- Animals, Breast Neoplasms drug therapy, Breast Neoplasms pathology, Cell Culture Techniques, Drug Evaluation, Preclinical methods, Female, Humans, Male, Mice, Prostatic Neoplasms drug therapy, Prostatic Neoplasms pathology, Tumor Microenvironment genetics, Biosensing Techniques methods, Drug Resistance, Neoplasm genetics, Microfluidics methods, Tumor Microenvironment drug effects
- Abstract
Development of resistance to chemotherapy treatments is a major challenge in the battle against cancer. Although a vast repertoire of chemotherapeutics is currently available for treating cancer, a technique for rapidly identifying the right drug based on the chemo-resistivity of the cancer cells is not available and it currently takes weeks to months to evaluate the response of cancer patients to a drug. A sensitive, low-cost diagnostic assay capable of rapidly evaluating the effect of a series of drugs on cancer cells can significantly change the paradigm in cancer treatment management. Integration of microfluidics and electrical sensing modality in a 3D tumour microenvironment may provide a powerful platform to tackle this issue. Here, we report a 3D microfluidic platform that could be potentially used for a real-time deterministic analysis of the success rate of a chemotherapeutic drug in less than 12h. The platform (66mm×50mm; L×W) is integrated with the microsensors (interdigitated gold electrodes with width and spacing 10µm) that can measure the change in the electrical response of cancer cells seeded in a 3D extra cellular matrix when a chemotherapeutic drug is flown next to the matrix. B16-F10 mouse melanoma, 4T1 mouse breast cancer, and DU 145 human prostate cancer cells were used as clinical models. The change in impedance magnitude on flowing chemotherapeutics drugs measured at 12h for drug-susceptible and drug tolerant breast cancer cells compared to control were 50,552±144 Ω and 28,786±233 Ω, respectively, while that of drug-susceptible melanoma cells were 40,197±222 Ω and 4069±79 Ω, respectively. In case of prostate cancer the impedance change between susceptible and resistant cells were 8971±1515 Ω and 3281±429 Ω, respectively, which demonstrated that the microfluidic platform was capable of delineating drug susceptible cells, drug tolerant, and drug resistant cells in less than 12h., (Copyright © 2017 Elsevier B.V. All rights reserved.)
- Published
- 2017
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32. Numerical simulation of ozone concentration profile and flow characteristics in paddy bulks.
- Author
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Pandiselvam R, Chandrasekar V, and Thirupathi V
- Subjects
- Diffusion, Edible Grain metabolism, Models, Biological, Ozone metabolism
- Abstract
Background: Ozone has shown the potential to control stored product insect pests. The high reactivity of ozone leads to special problems when it passes though an organic medium such as stored grains. Thus, there is a need for a simulation study to understand the concentration profile and flow characteristics of ozone in stored paddy bulks as a function of time., Results: Simulation of ozone concentration through the paddy grain bulks was explained by applying the principle of the law of conservation along with a continuity equation. A higher ozone concentration value was observed at regions near the ozone diffuser whereas a lower concentration value was observed at regions away from the ozone diffuser. The relative error between the experimental and predicted ozone concentration values for the entire bin geometry was less than 42.8%., Conclusion: The simulation model described a non-linear change of ozone concentration in stored paddy bulks. Results of this study provide a valuable source for estimating the parameters needed for effectively designing a storage bin for fumigation of paddy grains in a commercial scale continuous-flow ozone fumigation system. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)
- Published
- 2017
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33. Multichannel intra-luminal impedance signals variability during gastro-oesophageal activities.
- Author
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Al-Sheikh B, Chandrasekar V, and Stuebe T
- Subjects
- Electric Impedance, Humans, Models, Theoretical, Gastroesophageal Reflux physiopathology
- Abstract
Multichannel intra-luminal impedance (MII) technique has been proven to be a successful diagnostic tool in detecting and displaying activities inside the oesophagus. It improves the diagnostic capability of oesophageal disorders since it gives accurate and more in-depth information about the activities inside the oesophagus, especially reflux episodes. A comparison is presented between normal and abnormal adults in terms of variability in MII signals during baselines and reflux episodes. A comparative study of episode duration for normal and abnormal subjects is presented. The characteristics of MII signals during gastro-oesophageal reflux episodes as well as during baselines are investigated. These characteristics show different responses between normal and abnormal individuals which help improving MII analysis capability in evaluating patients with gastro-oesophageal reflux disease and enhances the automatic detection of the oesophageal activities. Baselines from normal and abnormal samples were fitted to gamma distributions as a trial to distinguish between normal and abnormal samples.
- Published
- 2017
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34. Combining Immune Checkpoint Inhibitors and Kinase-Inhibiting Supramolecular Therapeutics for Enhanced Anticancer Efficacy.
- Author
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Kulkarni A, Natarajan SK, Chandrasekar V, Pandey PR, and Sengupta S
- Abstract
A major limitation of immune checkpoint inhibitors is that only a small subset of patients achieve durable clinical responses. This necessitates the development of combinatorial regimens with immunotherapy. However, some combinations, such as MEK- or PI3K-inhibitors with a PD1-PDL1 checkpoint inhibitor, are pharmacologically challenging to implement. We rationalized that such combinations can be enabled using nanoscale supramolecular targeted therapeutics, which spatially home into tumors and exert temporally sustained inhibition of the target. Here we describe two case studies where nanoscale MEK- and PI3K-targeting supramolecular therapeutics were engineered using a quantum mechanical all-atomistic simulation-based approach. The combinations of nanoscale MEK- and PI3K-targeting supramolecular therapeutics with checkpoint PDL1 and PD1 inhibitors exert enhanced antitumor outcome in melanoma and breast cancers in vivo, respectively. Additionally, the temporal sequence of administration impacts the outcome. The combination of supramolecular therapeutics and immunotherapy could emerge as a paradigm shift in the treatment of cancer.
- Published
- 2016
- Full Text
- View/download PDF
35. Release Kinetics of Nisin from Chitosan-Alginate Complex Films.
- Author
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Chandrasekar V, Coupland JN, and Anantheswaran RC
- Subjects
- Calorimetry, Chromatography, High Pressure Liquid, Diffusion, Food Packaging, Food Preservation, Glucuronic Acid chemistry, Hexuronic Acids chemistry, Kinetics, Materials Testing, Nephelometry and Turbidimetry, Polymers chemistry, Viscosity, Water chemistry, Alginates chemistry, Anti-Infective Agents chemistry, Chitosan chemistry, Nisin chemistry
- Abstract
Understanding the release kinetics of antimicrobials from polymer films is important in the design of effective antimicrobial packaging films. The release kinetics of nisin (30 mg/film) from chitosan-alginate polyelectric complex films prepared using various fractions of alginate (33%, 50%, and 66%) was investigated into an aqueous release medium. Films containing higher alginate fractions showed significantly lower (P < 0.05) degree of swelling in water. Total amount of nisin released from films into an aqueous system decreased significantly (P < 0.05) with an increase in alginate concentration. The mechanism of diffusion of nisin from all films was found to be Fickian, and diffusion coefficients varied from 0.872 × 10
-9 to 8.034 ×10-9 cm2 /s. Strong complexation was confirmed between chitosan and alginate polymers within the films using isothermal titration calorimetry and viscosity studies, which affects swelling of films and subsequent nisin release. Complexation was also confirmed between nisin and alginate, which limited the amount of free nisin available for diffusion from films. These low-swelling biopolymer complexes have potential to be used as antimicrobial packaging films with sustained nisin release characteristics., (© 2016 Institute of Food Technologists®.)- Published
- 2016
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36. Algorithm for Designing Nanoscale Supramolecular Therapeutics with Increased Anticancer Efficacy.
- Author
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Kulkarni A, Pandey P, Rao P, Mahmoud A, Goldman A, Sabbisetti V, Parcha S, Natarajan SK, Chandrasekar V, Dinulescu D, Roy S, and Sengupta S
- Subjects
- Molecular Dynamics Simulation, Nanostructures, Algorithms, Nanoparticles, Neoplasms therapy
- Abstract
In the chemical world, evolution is mirrored in the origin of nanoscale supramolecular structures from molecular subunits. The complexity of function acquired in a supramolecular system over a molecular subunit can be harnessed in the treatment of cancer. However, the design of supramolecular nanostructures is hindered by a limited atomistic level understanding of interactions between building blocks. Here, we report the development of a computational algorithm, which we term Volvox after the first multicellular organism, that sequentially integrates quantum mechanical energy-state- and force-field-based models with large-scale all-atomistic explicit water molecular dynamics simulations to design stable nanoscale lipidic supramolecular structures. In one example, we demonstrate that Volvox enables the design of a nanoscale taxane supramolecular therapeutic. In another example, we demonstrate that Volvox can be extended to optimizing the ratio of excipients to form a stable nanoscale supramolecular therapeutic. The nanoscale taxane supramolecular therapeutic exerts greater antitumor efficacy than a clinically used taxane in vivo. Volvox can emerge as a powerful tool in the design of nanoscale supramolecular therapeutics for effective treatment of cancer.
- Published
- 2016
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37. Reporter nanoparticle that monitors its anticancer efficacy in real time.
- Author
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Kulkarni A, Rao P, Natarajan S, Goldman A, Sabbisetti VS, Khater Y, Korimerla N, Chandrasekar V, Mashelkar RA, and Sengupta S
- Subjects
- Animals, Antineoplastic Agents chemistry, Antineoplastic Agents therapeutic use, Apoptosis drug effects, B7-H1 Antigen immunology, Caspase 3 chemistry, Caspase 3 metabolism, Cell Line, Tumor, Cell Survival drug effects, Drug Carriers chemistry, Drug Carriers therapeutic use, Drug Resistance, Neoplasm drug effects, Esterases chemistry, Esterases metabolism, Female, Fluorescent Dyes administration & dosage, Fluorescent Dyes chemistry, Fluorescent Dyes therapeutic use, Humans, Immunoglobulin G immunology, Male, Mice, Inbred BALB C, Mice, Inbred C57BL, Microscopy, Fluorescence, Nanoparticles chemistry, Nanoparticles therapeutic use, Neoplasms drug therapy, Neoplasms metabolism, Neoplasms pathology, Oligopeptides administration & dosage, Oligopeptides chemistry, Oligopeptides therapeutic use, Paclitaxel administration & dosage, Paclitaxel chemistry, Paclitaxel therapeutic use, Polymers administration & dosage, Polymers chemistry, Polymers therapeutic use, Treatment Outcome, Tumor Burden drug effects, Antineoplastic Agents administration & dosage, Drug Carriers administration & dosage, Drug Monitoring methods, Monitoring, Immunologic methods, Nanoparticles administration & dosage, Neoplasms diagnostic imaging
- Abstract
The ability to monitor the efficacy of an anticancer treatment in real time can have a critical effect on the outcome. Currently, clinical readouts of efficacy rely on indirect or anatomic measurements, which occur over prolonged time scales postchemotherapy or postimmunotherapy and may not be concordant with the actual effect. Here we describe the biology-inspired engineering of a simple 2-in-1 reporter nanoparticle that not only delivers a cytotoxic or an immunotherapy payload to the tumor but also reports back on the efficacy in real time. The reporter nanoparticles are engineered from a novel two-staged stimuli-responsive polymeric material with an optimal ratio of an enzyme-cleavable drug or immunotherapy (effector elements) and a drug function-activatable reporter element. The spatiotemporally constrained delivery of the effector and the reporter elements in a single nanoparticle produces maximum signal enhancement due to the availability of the reporter element in the same cell as the drug, thereby effectively capturing the temporal apoptosis process. Using chemotherapy-sensitive and chemotherapy-resistant tumors in vivo, we show that the reporter nanoparticles can provide a real-time noninvasive readout of tumor response to chemotherapy. The reporter nanoparticle can also monitor the efficacy of immune checkpoint inhibition in melanoma. The self-reporting capability, for the first time to our knowledge, captures an anticancer nanoparticle in action in vivo.
- Published
- 2016
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38. Astrocyte Depletion Impairs Redox Homeostasis and Triggers Neuronal Loss in the Adult CNS.
- Author
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Schreiner B, Romanelli E, Liberski P, Ingold-Heppner B, Sobottka-Brillout B, Hartwig T, Chandrasekar V, Johannssen H, Zeilhofer HU, Aguzzi A, Heppner F, Kerschensteiner M, and Becher B
- Subjects
- Animals, Antioxidants pharmacology, Brain cytology, Brain drug effects, Brain growth & development, Cell Death, Glial Fibrillary Acidic Protein genetics, Glial Fibrillary Acidic Protein metabolism, Mice, Reactive Nitrogen Species metabolism, Reactive Oxygen Species metabolism, Astrocytes metabolism, Brain metabolism, Motor Neurons metabolism, Oxidative Stress
- Abstract
Although the importance of reactive astrocytes during CNS pathology is well established, the function of astroglia in adult CNS homeostasis is less well understood. With the use of conditional, astrocyte-restricted protein synthesis termination, we found that selective paralysis of GFAP(+) astrocytes in vivo led to rapid neuronal cell loss and severe motor deficits. This occurred while structural astroglial support still persisted and in the absence of any major microvascular damage. Whereas loss of astrocyte function did lead to microglial activation, this had no impact on the neuronal loss and clinical decline. Neuronal injury was caused by oxidative stress resulting from the reduced redox scavenging capability of dysfunctional astrocytes and could be prevented by the in vivo treatment with scavengers of reactive oxygen and nitrogen species (ROS/RNS). Our results suggest that the subpopulation of GFAP(+) astrocytes maintain neuronal health by controlling redox homeostasis in the adult CNS., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2015
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39. Modeling development of inhibition zones in an agar diffusion bioassay.
- Author
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Chandrasekar V, Knabel SJ, and Anantheswaran RC
- Abstract
A two-temperature agar diffusion bioassay is commonly used to quantify the concentration of nisin using Micrococcus luteus as the indicator microorganism. A finite element computational model based on Fick's second law of diffusion was used to predict the radius of the inhibition zone in this diffusion bioassay. The model developed was used to calculate nisin concentration profiles as a function of time and position within the agar. The minimum inhibitory concentration (MIC) of nisin against M. luteus was determined experimentally. The critical time (T c) for growth of M. luteus within the agar diffusion bioassay was experimentally determined using incubation studies with nisin. The radius of the inhibition zone was predicted from the computational model as the location where the predicted nisin concentration at T c was equal to MIC. The MIC was experimentally determined to be 0.156 μg mL(-1), and T c was determined to be 7 h. Good agreement (R (2) = 0.984) was obtained between model-predicted and experimentally determined inhibition zone radii.
- Published
- 2015
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40. Selective lentiviral-mediated suppression of microRNA124a in the hippocampus evokes antidepressants-like effects in rats.
- Author
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Bahi A, Chandrasekar V, and Dreyer JL
- Subjects
- Anhedonia, Animals, Eating psychology, Genetic Vectors, Hippocampus virology, Male, Plasmids genetics, Rats, Rats, Wistar, Stress, Psychological metabolism, Swimming psychology, Brain-Derived Neurotrophic Factor metabolism, Depression metabolism, Depression psychology, Hippocampus metabolism, Lentivirus, MicroRNAs antagonists & inhibitors
- Abstract
Several lines of evidences suggest that the brain-derived neutrophic factor (BDNF) is implicated in the pathophysiology of depression. However, the molecular mechanisms are not fully understood. In the current study we aimed to investigate how genetic modulation of BDNF in the hippocampus using microRNa124a (miR124a)-expressing lentiviral vectors (LV) might affect depression-like behavior in adult rats. For this purpose, we assessed the expression level of miR124a and its direct target BDNF in the hippocampus and the cortex after 21-days exposure to social defeat stress. Results demonstrated that miR124a was up-regulated in the hippocampus but not in the cortex. In contrast, and as expected, BDNF transcripts were down-regulated. In a different set of experiments, male Wistar rats received bilateral intra-hippocampal or intra-cortical infusions of BDNF- and miR124a-expressing lentiviral vectors and depression-like behavior was assessed after 21-days social defeat stress using the novelty suppressed feeding, the sucrose preference and the forced swim tests. The results indicated that miR124a overexpression exacerbated depression-like behavior. However, an anti-depressant like effect was observed when BDNF or miR124a-silencers (siR124a) were injected into the hippocampus. Importantly, when expressed into the cortex, LV-miR124a, LV-siR124a and LV-BDNF had no effect on depression. Our findings indicate that hippocampal miR124a and its direct target BDNF play an important role in depression-like behavior. Taken together, the current results reveal, for the first time, a potential molecular regulation of miR124a on BDNF, and the pronounced behavioral consequences of this regulation shed light on the mechanisms underlying BDNF anti-depressant potential., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2014
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41. Spontaneous rupture of one slip of flexor digitorum superficialis causing triggering.
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Bhardwaj P, Chandrasekar V, and Sabapathy RS
- Published
- 2014
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42. Incidence of metabolic syndrome and its characteristics of patients attending a diabetic outpatient clinic in a tertiary care hospital.
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Kumar SV, Nagesh A, Leena M, Shravani G, and Chandrasekar V
- Abstract
Objective: We sought to evaluate the incidence of metabolic syndrome and non-metabolic syndrome among type 2 diabetic patients attending the diabetic outpatient clinic at tertiary care hospital, Warangal., Materials and Methods: A cross-sectional study was conducted in a period of 6 months from January 2011 to June 2011. The study group consisted of 75 type 2 diabetic patients. They were screened for hypertension, hyperlipidemia, obesity, and clinical characteristics, and other co-morbidities were recorded. Metabolic syndrome diagnosis was made as per ATP III guidelines., Results: The prevalence of metabolic syndrome was significant in men (54.8%) compared to women (45.2%). Incidence of metabolic syndrome was found to be more in normal weight patients (43.56%). Low high density lipoprotein (HDL) levels were observed in both rural (90.63%) and urban (95.65%) patients with metabolic syndrome, followed by increase in waist circumference. The mean HDL level was found to be 23.77 mg/dl. Patients in the age group 51-60 years were found to be more affected with metabolic syndrome. Sedentary household female patients (58.3%) and illiterates (41.8%) were suffering from metabolic syndrome. Patients with metabolic syndrome had been suffering with diabetes (duration of diabetes) from 1 to 5 years. In summary, this cross-sectional study characterizes the metabolic and non-metabolic syndromes of type 2 diabetes patients living in Telangana regions, using ATP III guidelines, and generates a biological resource that enables further investigation of numerous hypotheses related to genetic exposure of both in a population., Conclusion: These results suggest that higher prevalence of metabolic syndrome was observed in non-obese male patients and was significantly associated with aging. Nevertheless, further studies are required to confirm the metabolic syndrome in larger population.
- Published
- 2013
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43. Regulation of MiR-124, Let-7d, and MiR-181a in the accumbens affects the expression, extinction, and reinstatement of cocaine-induced conditioned place preference.
- Author
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Chandrasekar V and Dreyer JL
- Subjects
- Animals, Cocaine pharmacology, Cocaine-Related Disorders genetics, Cocaine-Related Disorders metabolism, Conditioning, Psychological physiology, Disease Models, Animal, Extinction, Psychological physiology, Gene Expression Regulation drug effects, Gene Expression Regulation physiology, Gene Regulatory Networks drug effects, Gene Regulatory Networks physiology, HEK293 Cells, Humans, Male, Nucleus Accumbens metabolism, Rats, Rats, Wistar, Conditioning, Psychological drug effects, Extinction, Psychological drug effects, Gene Silencing drug effects, Gene Silencing physiology, MicroRNAs biosynthesis, MicroRNAs metabolism, MicroRNAs physiology, Nucleus Accumbens drug effects
- Abstract
Molecular adaptations underlying drug seeking and relapse remain largely unknown. Studies highlight post-transcriptional modifications mediated by microRNAs (miRNAs) in addiction and other neurological disorders. We have previously shown that chronic cocaine suppresses miR-124 and let-7d and induces the expression of miR-181a in mesolimbic pathway. To further address the role and target gene regulation network of these miRNAs in vivo in cocaine addiction, we developed lentiviral vector (LV)-expressing miRNAs and their corresponding silencers for stable and regulatable miRNA expression. We tested in vivo miRNA gain and loss of function on cocaine-induced conditioned place preference (CPP) by localized LV-miRNA regulation in the nucleus accumbens (NAc). LV-miR-124 and let-7d expression in the NAc attenuates cocaine CPP, whereas LV-miR-181a enhances it. Silencing miRNAs by corresponding LV-miRNA silencers expressing perfect miRNA target sequences inversed this effect on cocaine CPP. Doxycycline treatment for switching off silencer expression abolished the observed behavioral changes. Behavioral changes mediated by LV-miRNA regulation resulted in dynamic alterations in transcription factors, receptors, and other effector genes involved in cocaine-induced plasticity. Our results describe a complex regulatory pathway mediated by miRNAs in cocaine-mediated neuronal adaptations.
- Published
- 2011
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44. The Brain-Specific Neural Zinc Finger Transcription Factor 2b (NZF-2b/7ZFMyt1) Suppresses Cocaine Self-Administration in Rats.
- Author
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Chandrasekar V and Dreyer JL
- Abstract
Brain-specific neural-zinc-finger transcription factor-2b (NZF2b/7ZFMyt1) is induced in the mesolimbic dopaminergic region after chronic cocaine exposure and lentiviral-mediated expression of NZF2b/7ZFMyt1 in the nucleus accumbens results in decreased locomotor activity (Chandrasekar and Dreyer, 2010). In this study the role of NZF2b/7ZFMyt1 in active cocaine seeking and of its interaction with histone deacetylase on the altered behavior has been observed. Localized expression of NZF2b/7ZFMyt1 in the nucleus accumbens resulted in attenuated cocaine self-administration, whereas silencing this transcription factor with lentiviruses expressing siRNAs increased the animal's motivation to self-infuse cocaine. Low doses of sodium butyrate, a potent inhibitor of histone deacetylase, were sufficient to reverse the NZF2b/7ZFMyt1-mediated decrease in cocaine self-administration. NZF2b/7ZFMyt1 expression resulted in strong induction of transcription factors REST1 and NAC1 and of the dopamine D2 receptor, with concomitant inhibition of BDNF and its receptor TrkB. We show that NZF2b/7ZFMyt1 colocalizes with histone deacetylase-2 (HDAC2), probably overcoming the suppression of transcriptional activity caused by Lingo1. These findings show that molecular adaptations mediated by NZF2b/7ZFMyt1 expression possibly lead to decreased responsiveness to the reinforcing properties of cocaine and play a prominent role in affecting the behavioral changes induced by the drug.
- Published
- 2010
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45. The brain-specific Neural Zinc Finger transcription factor 2b (NZF-2b/7ZFMyt1) causes suppression of cocaine-induced locomotor activity.
- Author
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Chandrasekar V and Dreyer JL
- Subjects
- Animals, Brain drug effects, Brain physiology, Brain-Derived Neurotrophic Factor metabolism, Gene Knockdown Techniques, Gene Transfer Techniques, Genetic Vectors, Inverted Repeat Sequences, Lentivirus genetics, Locomotion physiology, Male, Nerve Tissue Proteins genetics, Neurons drug effects, Neurons physiology, Nucleus Accumbens physiology, RNA metabolism, RNA, Messenger metabolism, Rats, Rats, Wistar, Repressor Proteins, Transcription Factors genetics, Cocaine pharmacology, Dopamine Uptake Inhibitors pharmacology, Locomotion drug effects, Nerve Tissue Proteins metabolism, Nucleus Accumbens drug effects, Transcription Factors metabolism
- Abstract
Chronic cocaine induces high expression of the brain-specific Neural-Zinc-Finger transcription factor-2b (NZF-2b/7ZFMyt1), particularly in the mesolimbic dopaminergic pathway, resulting in a 11-fold increase in NZF-2b/7ZFMyt1 expression in the Nucleus Accumbens (NAc). Overexpression of this gene in the NAc with a NZF-2b/7ZFMyt1-expressing lentivirus resulted in >55% decrease in locomotor activity upon chronic cocaine administration, compared to control animals. In contrast knocking-down the gene in the NAc with lentiviruses expressing shRNAs against NZF-2b/7ZFMyt1 induced strong hyperlocomotor activity upon cocaine. Strong inhibition of BDNF is observed upon NZF-2b/7ZFMyt1 expression, concomitant with strong induction of transcription factors REST1 (RE silencing transcription factor-1) and NAC1, probably leading to regulation of gene expression by interaction with histone deacetylases. These changes lead to decreased responsiveness of the animal to the locomotor-activating effects of cocaine, indicating that NZF-2b/7ZFMyt1 expression plays an important role in phenotypic changes induced by the drug.
- Published
- 2010
- Full Text
- View/download PDF
46. microRNAs miR-124, let-7d and miR-181a regulate cocaine-induced plasticity.
- Author
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Chandrasekar V and Dreyer JL
- Subjects
- Animals, Base Sequence, Brain anatomy & histology, Brain physiology, Brain-Derived Neurotrophic Factor genetics, Brain-Derived Neurotrophic Factor metabolism, Gene Expression Profiling, Gene Expression Regulation drug effects, Humans, In Situ Hybridization, Fluorescence, Male, MicroRNAs genetics, Molecular Sequence Data, Neuronal Plasticity drug effects, Neuronal Plasticity physiology, Oligonucleotide Array Sequence Analysis, RNA Precursors genetics, RNA Precursors metabolism, Rats, Rats, Wistar, Receptors, Dopamine D3 genetics, Receptors, Dopamine D3 metabolism, Repressor Proteins genetics, Repressor Proteins metabolism, Reproducibility of Results, Substance-Related Disorders physiopathology, Cocaine pharmacology, Dopamine Uptake Inhibitors pharmacology, MicroRNAs metabolism, Neuronal Plasticity genetics
- Abstract
MicroRNAs play key regulatory roles in cellular processes including neurogenesis, synapse development and plasticity in the brain. Psychostimulants induce strong neuroadaptive changes through a surfeit of gene regulatory mechanisms leading to addiction. MicroRNA profiling for identifying miRNAs regulating cocaine-induced, plasticity-related genes revealed significant regulation of a set of miRNAs upon cocaine administration, especially let-7d, miR-181a and the brain-specific miR-124. These miRNAs target many genes involved in cocaine addiction. Precursor and mature miRNA quantification by qRT-PCR showed that miR-124 and let-7d are significantly downregulated, whereas miR-181a is induced in the mesolimbic dopaminergic system under chronic cocaine administration. Results were confirmed by in situ hybridization, Northern blots, FISH analysis and RNase protection assay. Using lentiviral-mediated miRNA expression, we show a significant downregulation of BDNF and D3R both at mRNA and protein levels by miR-124 and let-7d, respectively. Our data suggest that miR-124, let-7d and miR-181a may be involved in a complex feedback loop with cocaine-responsive plasticity genes, highlighting the possibility that some miRNAs are key regulators of the reward circuit and may be implicated in addiction.
- Published
- 2009
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- View/download PDF
47. Surveillance of drug-resistant tuberculosis in the state of Gujarat, India.
- Author
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Ramachandran R, Nalini S, Chandrasekar V, Dave PV, Sanghvi AS, Wares F, Paramasivan CN, Narayanan PR, Sahu S, Parmar M, Chadha S, Dewan P, and Chauhan LS
- Subjects
- Antitubercular Agents, Bacteriological Techniques, Colony Count, Microbial, Ethionamide, Extensively Drug-Resistant Tuberculosis diagnosis, Extensively Drug-Resistant Tuberculosis microbiology, Female, Humans, India epidemiology, Isoniazid, Kanamycin, Male, Microscopy, Fluorescence, Mycobacterium tuberculosis drug effects, Mycobacterium tuberculosis isolation & purification, Ofloxacin, Population Surveillance, Prevalence, Rifampin, Sputum microbiology, Tuberculosis, Multidrug-Resistant diagnosis, Tuberculosis, Multidrug-Resistant microbiology, Drug Resistance, Multiple, Bacterial, Extensively Drug-Resistant Tuberculosis epidemiology, Tuberculosis, Multidrug-Resistant epidemiology
- Abstract
Background: Limited information about the prevalence of drug-resistant tuberculosis (TB) has been reported from India, the country with the world's highest burden of TB. We conducted a representative state-wide survey in the state of Gujarat (2005 population: 56 million)., Methods: Mycobacterium tuberculosis isolates from a representative sample of new and previously treated smear-positive pulmonary TB (PTB) cases were subjected to drug susceptibility testing (DST) against first-line drugs at a World Health Organization supranational reference laboratory. Isolates found to have at least both isoniazid (INH) and rifampicin (RMP) resistance (i.e., multidrug-resistant TB [MDR-TB]) were subjected to second-line DST., Results: Of 1571 isolates from new patients, 1236 (78.7%) were susceptible to all first-line drugs, 173 (11%) had any INH resistance and MDR-TB was found in 37 (2.4%, 95%CI 1.6-3.1). Of 1047 isolates from previously treated patients, 564 (54%) were susceptible to all first-line drugs, 387 (37%) had any INH resistance and MDR-TB was found in 182 (17.4%, 95%CI 15.0-19.7%). Among 216 MDR-TB isolates, 52 (24%) were ofloxacin (OFX) resistant; seven cases of extensively drug-resistant TB (XDR-TB) were found, all of whom were previously treated cases., Conclusion: MDR-TB prevalence remains low among new TB patients in Gujarat, but is more common among previously treated patients. Among MDR-TB isolates, the alarmingly high prevalence of OFX resistance may threaten the success of the expanding efforts to treat and control MDR-TB.
- Published
- 2009
48. Role of accumbens BDNF and TrkB in cocaine-induced psychomotor sensitization, conditioned-place preference, and reinstatement in rats.
- Author
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Bahi A, Boyer F, Chandrasekar V, and Dreyer JL
- Subjects
- Animals, Brain-Derived Neurotrophic Factor metabolism, Cell Line, Doxycycline pharmacology, Extinction, Psychological drug effects, Immunohistochemistry, Lentivirus genetics, Male, Nucleus Accumbens metabolism, RNA, Small Interfering, Rats, Rats, Wistar, Receptor, trkB metabolism, Reverse Transcriptase Polymerase Chain Reaction, Transfection, Brain-Derived Neurotrophic Factor physiology, Cocaine pharmacology, Conditioning, Operant drug effects, Dopamine Uptake Inhibitors pharmacology, Motor Activity drug effects, Nucleus Accumbens physiology, Receptor, trkB physiology
- Abstract
Background: Brain-derived neurotrophic factor (BDNF) is involved in the survival and function of midbrain DA neurons. BDNF action is mediated by the TrkB receptor-tyrosine kinase, and both BDNF and TrkB transcripts are widely expressed in the rat mesolimbic pathway, including the nucleus accumbens (NAc) and the ventral tegmentum area (VTA)., Objective: BDNF was previously shown to be involved in cocaine reward and relapse, as assessed in rat models. The goal of this study is to explore the role of BDNF and TrkB in the rat nucleus accumbens (NAc) in cocaine-induced psychomotor sensitization and in conditioned-place preference acquisition, expression, and reinstatement., Materials and Methods: In vivo genetic manipulations of BDNF and TrkB were performed using a lentiviral gene delivery approach to over-express these genes in the NAc and siRNA-based technology to locally knockdown gene expression. Behavioral experiments consisted of locomotor activity monitoring or cocaine-induced conditioned-place preference (CPP)., Results: BDNF and/or its receptor TrkB in the NAc enhance drug-induced locomotor activity and induce sensitization in rats. Furthermore, LV-BDNF- and LV-TrkB-treated rats display enhanced cocaine-induced CPP, delayed CPP-extinction upon repeated measurements, and increased CPP reinstatement. In contrast, expression of TrkT1 (truncated form of TrkB, acting as a dominant negative) inhibits these behavioral changes. This inhibition is also observed when rats are fed doxycycline (to block lentivirus-mediated gene expression) or when injected with siRNAs-expressing lentiviruses against TrkB. In addition, we investigate the establishment, maintenance, extinction, and reinstatement of cocaine-induced CPP. We show that BDNF and TrkB-induced CPP takes place during the learning period (conditioning), whereas extinction leads to the loss of CPP. Extinction is delayed when rats are injected LV-BDNF or LV-TrkB, and in turn, priming injections of 2 mg/kg of cocaine reinstates it., Conclusions: These results demonstrate the crucial function of BDNF-through its receptor TrkB-in the enhancement of locomotor activity, sensitization, conditioned-place preference, CPP-reinstatement, and rewarding effects of cocaine in the mesolimbic dopaminergic pathway.
- Published
- 2008
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49. Effect of esophagus status and catheter configuration on multiple intraluminal impedance measurements.
- Author
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Al-Zaben A and Chandrasekar V
- Subjects
- Computer Simulation, Computer-Aided Design, Equipment Design, Equipment Failure Analysis, Humans, Catheterization instrumentation, Catheterization methods, Diagnosis, Computer-Assisted methods, Electric Impedance, Esophagus physiology, Models, Biological, Plethysmography, Impedance instrumentation, Plethysmography, Impedance methods
- Abstract
Multiple intraluminal impedance measurement is used to investigate the esophagus condition. This procedure provides information about the esophagus status, reflux occurrence and clearance mechanism. This paper presents finite-element approximation of the forward problem of the catheter inside the esophagus, relating the real data obtained from multiple intraluminal impedance to the solution obtained from the finite-element approximation. Investigation of the effect of the esophagus status on the impedance, and the correlation between various factors that affect the impedance are presented. The results of this paper provide theoretical bases for relating the esophagus condition to the impedance waveforms.
- Published
- 2005
- Full Text
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50. Computation of intraluminal impedance.
- Author
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Al-Zaben A and Chandrasekar V
- Subjects
- Catheterization, Electrodes, Humans, Electric Impedance, Esophagus, Gastroesophageal Reflux diagnosis, Models, Biological
- Abstract
The measurement of the electrical impedance inside the esophagus provides information about its status, and is being explored in the study of the gastroesophageal reflux. This paper presents theoretical computation of impedance inside the esophagus. The results of the numerical solution for a simple geometry are compared against the solution formulated from the Green's function approach. The effect of the electrode configuration on the resulting impedance is studied as an application of the methodology developed in this paper. The results of this paper will be useful in the design of an intraluminal impedance catheter as well as in the interpretation of the resulting impedance signals.
- Published
- 2004
- Full Text
- View/download PDF
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