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Shyamasunder AH, Pai R, Ramamoorthy H, Sakhti D, Manipadam MT, Kapoor N, Paul TV, Jebasingh F, Thomas N, Abraham DT, Paul MJ, Chacko AG, Prabhu K, Rajaratnam S. Clinical Profile and Mutations Associated with Multiple Endocrine Neoplasia-Type1 (MEN1) and Their First-Degree Relatives at Risk of Developing MEN1: A Prospective Study. Horm Metab Res 2021; 53:245-256. [PMID: 33853118 DOI: 10.1055/a-1402-0183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Multiple Endocrine Neoplasia type-1 (MEN1) is an autosomal dominant disorder with a combined occurrence of tumours of parathyroid glands, pancreatic islets, and anterior pituitary. About 90% of these patients carry mutations in the MEN1 gene, though the spectrum is not well defined in India. Forty clinically suspected cases of MEN1 were enrolled prospectively over six years; 32 patients (23 index-cases and nine affected relatives) with≥2 classical endocrine tumours of MEN1 were considered definite, and eight were categorised as 'MEN1-like'. Details of their clinical presentation, treatment and mutational analysis including MEN1 gene, 3' and 5' untranslated regions (UTR) of MEN1, CDKN1B, and CaSR genes were collated. Asymptomatic first-degree relatives were also screened. Among the 32 definite MEN1 patients, all had primary hyperparathyroidism, 22 (68.7%) had gastroentero-pancreatic neuroendocrine tumours, and 21 (66%) had pituitary adenoma. Of the 23 definite index-cases, 13 (56.5%) carried mutations in the MEN1 gene. Five of nine affected first-degree relatives (55.5%), and four of 10 asymptomatic relatives (40%) also had MEN1 mutations. Seven of 10 MEN1 mutation-negative definite index-cases harboured p.V109G polymorphism in the CDKN1B gene. All eight MEN1-like cases were negative for mutations and large deletions in MEN1, mutations in 3' and 5' UTR of MEN1, CaSR and CDKN1B genes. The study has helped to clearly document the pattern of mutations among Indian MEN1 patients. However, the absence of MEN1 mutation in ~44% of cases and the presence of p.V109G polymorphism in CDKN1B gene raise the question whether such polymorphisms could independently contribute to pathogenesis.
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Affiliation(s)
| | - Rekha Pai
- Department of Pathology, Christian Medical College, Vellore, Tamil Nadu, India
| | | | - Dhananjayan Sakhti
- Department of Pathology, Christian Medical College, Vellore, Tamil Nadu, India
| | | | - Nitin Kapoor
- Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, Tamil Nadu, India
| | - Thomas Vizhalil Paul
- Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, Tamil Nadu, India
| | - Felix Jebasingh
- Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, Tamil Nadu, India
| | - Nihal Thomas
- Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, Tamil Nadu, India
| | - Deepak Thomas Abraham
- Department of Endocrine Surgery, Christian Medical College, Vellore, Tamil Nadu, India
| | | | - Ari George Chacko
- Department of Neurosurgery, Christian Medical College, Vellore, Tamil Nadu, India
| | - Krishna Prabhu
- Department of Neurosurgery, Christian Medical College, Vellore, Tamil Nadu, India
| | - Simon Rajaratnam
- Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, Tamil Nadu, India
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Arabchigavkani N, Somphonsane R, Ramamoorthy H, He G, Nathawat J, Yin S, Barut B, He K, Randle MD, Dixit R, Sakanashi K, Aoki N, Zhang K, Wang L, Mei WN, Dowben PA, Fransson J, Bird JP. Remote Mesoscopic Signatures of Induced Magnetic Texture in Graphene. Phys Rev Lett 2021; 126:086802. [PMID: 33709762 DOI: 10.1103/physrevlett.126.086802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 01/19/2021] [Indexed: 06/12/2023]
Abstract
Mesoscopic conductance fluctuations are a ubiquitous signature of phase-coherent transport in small conductors, exhibiting universal character independent of system details. In this Letter, however, we demonstrate a pronounced breakdown of this universality, due to the interplay of local and remote phenomena in transport. Our experiments are performed in a graphene-based interaction-detection geometry, in which an artificial magnetic texture is induced in the graphene layer by covering a portion of it with a micromagnet. When probing conduction at some distance from this region, the strong influence of remote factors is manifested through the appearance of giant conductance fluctuations, with amplitude much larger than e^{2}/h. This violation of one of the fundamental tenets of mesoscopic physics dramatically demonstrates how local considerations can be overwhelmed by remote signatures in phase-coherent conductors.
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Affiliation(s)
- N Arabchigavkani
- Department of Physics, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
| | - R Somphonsane
- Department of Physics, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
| | - H Ramamoorthy
- Department of Electronics Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
| | - G He
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
| | - J Nathawat
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
| | - S Yin
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
| | - B Barut
- Department of Physics, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
| | - K He
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
| | - M D Randle
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
| | - R Dixit
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
| | - K Sakanashi
- Department of Materials Science, Chiba University, Chiba 263-8522, Japan
| | - N Aoki
- Department of Materials Science, Chiba University, Chiba 263-8522, Japan
| | - K Zhang
- Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - L Wang
- Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - W-N Mei
- Department of Physics, University of Nebraska Omaha, Omaha, Nebraska 68182, USA
| | - P A Dowben
- Department of Physics and Astronomy, Theodore Jorgensen Hall, University of Nebraska Lincoln, Lincoln, Nebraska 68588-0299, USA
| | - J Fransson
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 21 Uppsala, Sweden
| | - J P Bird
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, New York 14260, USA
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Ramamoorthy H, Abraham P, Isaac B. Melatonin protects against tenofovir-induced nephrotoxicity in rats by targeting multiple cellular pathways. Hum Exp Toxicol 2020; 40:826-850. [PMID: 33146023 DOI: 10.1177/0960327120968860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection and chronic hepatitis B infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to its better tolerance, and a more effective treatment can be achieved. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats and to determine its cellular targets. Rats were divided into groups and treated as follows. Group I (control): Rats in this group (n = 6) received sterile water only by gavage for 35 days. Group II: Rats (n = 6) in this group received 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group III: Rats (n = 6) in this group received once daily 20 mg/kg bodyweight melatonin i.p. 2 h before the administration of 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group IV: Rats were pretreated daily with 20 mg/kg body weight melatonin i.p. 2 h before the administration of sterile water by gavage. All the rats were sacrificed on the 36th day, after overnight fast. Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced, oxidative stress, nitrosative stress, mitochondrial pathway of apoptosis, PARP overactivation and preserved proximal tubular function (p < 0.01). This suggests that melatonin may be useful in ameliorating TDF nephrotoxicity.
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Affiliation(s)
| | - Premila Abraham
- Department of Biochemistry, Christian Medical College, Vellore, Tamil Nadu, India
| | - Bina Isaac
- Department of Anatomy, Christian Medical College, Vellore, Tamil Nadu, India
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Somphonsane R, Ramamoorthy H, He G, Nathawat J, Yin S, Kwan CP, Arabchigavkani N, Barut B, Zhao M, Jin Z, Fransson J, Bird JP. Universal scaling of weak localization in graphene due to bias-induced dispersion decoherence. Sci Rep 2020; 10:5611. [PMID: 32221340 PMCID: PMC7101405 DOI: 10.1038/s41598-020-62313-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 03/11/2020] [Indexed: 11/29/2022] Open
Abstract
The differential conductance of graphene is shown to exhibit a zero-bias anomaly at low temperatures, arising from a suppression of the quantum corrections due to weak localization and electron interactions. A simple rescaling of these data, free of any adjustable parameters, shows that this anomaly exhibits a universal, temperature- (T) independent form. According to this, the differential conductance is approximately constant at small voltages (V < kBT/e), while at larger voltages it increases logarithmically with the applied bias. For theoretical insight into the origins of this behaviour, which is inconsistent with electron heating, we formulate a model for weak-localization in the presence of nonequilibrium transport. According to this model, the applied voltage causes unavoidable dispersion decoherence, which arises as diffusing electron partial waves, with a spread of energies defined by the value of the applied voltage, gradually decohere with one another as they diffuse through the system. The decoherence yields a universal scaling of the conductance as a function of eV/kBT, with a logarithmic variation for eV/kBT > 1, variations in accordance with the results of experiment. Our theoretical description of nonequilibrium transport in the presence of this source of decoherence exhibits strong similarities with the results of experiment, including the aforementioned rescaling of the conductance and its logarithmic variation as a function of the applied voltage.
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Affiliation(s)
- R Somphonsane
- Department of Physics, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand.
- Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok, 10400, Thailand.
| | - H Ramamoorthy
- Department of Electronic Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand
| | - G He
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260-1900, USA
| | - J Nathawat
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260-1900, USA
| | - S Yin
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260-1900, USA
| | - C-P Kwan
- Department of Physics, University at Buffalo, The State University of New York, Buffalo, NY, 14260-1500, USA
| | - N Arabchigavkani
- Department of Physics, University at Buffalo, The State University of New York, Buffalo, NY, 14260-1500, USA
| | - B Barut
- Department of Physics, University at Buffalo, The State University of New York, Buffalo, NY, 14260-1500, USA
| | - M Zhao
- High-Frequency High-Voltage Device and Integrated Circuits Center, Institute of Microelectronics of Chinese Academy of Sciences, 3 Beitucheng West Road, Chaoyang District, Beijing, PR China
| | - Z Jin
- High-Frequency High-Voltage Device and Integrated Circuits Center, Institute of Microelectronics of Chinese Academy of Sciences, 3 Beitucheng West Road, Chaoyang District, Beijing, PR China
| | - J Fransson
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 21, Uppsala, Sweden
| | - J P Bird
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260-1900, USA
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Ramamoorthy H, Abraham P, Isaac B, Selvakumar D. Mitochondrial pathway of apoptosis and necrosis contribute to tenofovir disoproxil fumarate-induced renal damage in rats. Hum Exp Toxicol 2018; 38:288-302. [PMID: 30326737 DOI: 10.1177/0960327118802619] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Tenofovir disoproxil fumarate (TDF) is currently the only nucleotide analogue reverse-transcriptase inhibitor that is approved by the Food and Drug administration (FDA), USA, for the treatment of human immunodeficiency virus (HIV) infection. In recent days, renal toxicity is becoming common i HIV patients treated with TDF. However, the mechanism of tenofovir nephrotoxicity is not clear. We hypothesized that mitochondrial pathway of apoptosis, poly [ADP-ribose] polymerase (PARP) overactivation and neutrophil infiltration may contribute to tenofovir-induced renal damage. Renal damage was induced in adult male Wistar rats by the oral administration of 600 mg/kg body weight daily for five consecutive weeks. Kidneys were removed and used for histological and biochemical analyses. Apoptosis was detected by terminal deoxynucleotidyl transferase biotin-deoxyuridine triphosphate nick end-labelling (TUNEL) assay and caspase 3 activity and protein expression; mitochondrial pathway of apoptosis by cyt c release; and PARP activation by immunofluorescence, immunohistochemistry and Western blot techniques. Myeloperoxidase (MPO) activity was measured as a marker of neutrophil infiltration. TDF administration resulted in increased number of TUNEL-positive cells, activation of caspase 3 and release of cyt c from mitochondria into the cytosol in the kidneys. There was increased nuclear localization of PARP as well as increase in its protein level in the TDF-treated rat kidneys. In addition, renal MPO activity was increased ninefold as compared to controls. The results of the present study show that mitochondrial apoptotic pathway, PARP overactivation and neutrophil infiltration contribute to tenofovir-induced renal damage in rats.
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Affiliation(s)
- H Ramamoorthy
- 1 Department of Biochemistry, Christian Medical College, Bagayam, Vellore, Tamil Nadu, India
| | - P Abraham
- 1 Department of Biochemistry, Christian Medical College, Bagayam, Vellore, Tamil Nadu, India
| | - B Isaac
- 2 Department of Anatomy, Christian Medical College, Bagayam, Vellore, Tamil Nadu, India
| | - D Selvakumar
- 1 Department of Biochemistry, Christian Medical College, Bagayam, Vellore, Tamil Nadu, India
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He G, Ramamoorthy H, Kwan CP, Lee YH, Nathawat J, Somphonsane R, Matsunaga M, Higuchi A, Yamanaka T, Aoki N, Gong Y, Zhang X, Vajtai R, Ajayan PM, Bird JP. Thermally Assisted Nonvolatile Memory in Monolayer MoS 2 Transistors. Nano Lett 2016; 16:6445-6451. [PMID: 27680095 DOI: 10.1021/acs.nanolett.6b02905] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate a novel form of thermally-assisted hysteresis in the transfer curves of monolayer MoS2 FETs, characterized by the appearance of a large gate-voltage window and distinct current levels that differ by a factor of ∼102. The hysteresis emerges for temperatures in excess of 400 K and, from studies in which the gate-voltage sweep parameters are varied, appears to be related to charge injection into the SiO2 gate dielectric. The thermally-assisted memory is strongly suppressed in equivalent measurements performed on bilayer transistors, suggesting that weak screening in the monolayer system plays a vital role in generating its strongly sensitive response to the charge-injection process. By exploiting the full features of the hysteretic transfer curves, programmable memory operation is demonstrated. The essential principles demonstrated here point the way to a new class of thermally assisted memories based on atomically thin two-dimensional semiconductors.
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Affiliation(s)
- G He
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - H Ramamoorthy
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - C-P Kwan
- Department of Physics, University at Buffalo, The State University of New York , Buffalo, New York 14260-1500, United States
| | - Y-H Lee
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - J Nathawat
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - R Somphonsane
- Department of Physics, King Mongkut's Institute of Technology Ladkrabang , Bangkok 10520, Thailand
| | - M Matsunaga
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - A Higuchi
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - T Yamanaka
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - N Aoki
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Y Gong
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - X Zhang
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - R Vajtai
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - P M Ajayan
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - J P Bird
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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Ramamoorthy H, Somphonsane R, Radice J, He G, Kwan CP, Bird JP. Correction to "Freeing" Graphene from Its Substrate: Observing Intrinsic Velocity Saturation with Rapid Electrical Pulsing. Nano Lett 2016; 16:1514. [PMID: 26807871 DOI: 10.1021/acs.nanolett.6b00287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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Ramamoorthy H, Somphonsane R, Radice J, He G, Kwan CP, Bird JP. "Freeing" Graphene from Its Substrate: Observing Intrinsic Velocity Saturation with Rapid Electrical Pulsing. Nano Lett 2016; 16:399-403. [PMID: 26649478 DOI: 10.1021/acs.nanolett.5b04003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Rapid (nanosecond-scale) electrical pulsing is used to study drift-velocity saturation in graphene field-effect devices. In these experiments, high-field pulses are utilized to drive graphene's carriers on time scales much faster than that on which energy loss to the underlying substrate can occur, thereby allowing the observation of the highest saturation velocities reported to date. In a dramatic departure from the behavior exhibited by conventional metals and semiconductors, as the electron or hole density is reduced toward the charge-neutrality point, the drift velocity is found to reach values comparable to the Fermi velocity itself. Corresponding current densities are as large as 10(9) A/cm(2), similar to the values reported for carbon nanotubes and for graphene-on-diamond transistors. In essence, our approach of rapid pulsing allows us to "free" graphene from the deleterious influence of its substrate, revealing a pathway to achieve the superior electrical performance promised by this material. The usefulness of this approach is not merely limited to graphene but should extend also to a broad variety of two-dimensional semiconductors.
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Affiliation(s)
- H Ramamoorthy
- Department of Electrical Engineering, University at Buffalo, the State University of New York , Buffalo, New York 14260-1900, United States
| | - R Somphonsane
- Department of Physics, King Mongkut's Institute of Technology Ladkrabang , Bangkok 10520, Thailand
| | - J Radice
- Department of Electrical Engineering, University at Buffalo, the State University of New York , Buffalo, New York 14260-1900, United States
| | - G He
- Department of Electrical Engineering, University at Buffalo, the State University of New York , Buffalo, New York 14260-1900, United States
| | - C-P Kwan
- Department of Physics, University at Buffalo, the State University of New York , Buffalo, New York 14260-1500, United States
| | - J P Bird
- Department of Electrical Engineering, University at Buffalo, the State University of New York , Buffalo, New York 14260-1900, United States
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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He G, Ghosh K, Singisetti U, Ramamoorthy H, Somphonsane R, Bohra G, Matsunaga M, Higuchi A, Aoki N, Najmaei S, Gong Y, Zhang X, Vajtai R, Ajayan PM, Bird JP. Conduction Mechanisms in CVD-Grown Monolayer MoS2 Transistors: From Variable-Range Hopping to Velocity Saturation. Nano Lett 2015; 15:5052-8. [PMID: 26121164 DOI: 10.1021/acs.nanolett.5b01159] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We fabricate transistors from chemical vapor deposition-grown monolayer MoS2 crystals and demonstrate excellent current saturation at large drain voltages (Vd). The low-field characteristics of these devices indicate that the electron mobility is likely limited by scattering from charged impurities. The current-voltage characteristics exhibit variable range hopping at low Vd and evidence of velocity saturation at higher Vd. This work confirms the excellent potential of MoS2 as a possible channel-replacement material and highlights the role of multiple transport phenomena in governing its transistor action.
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Affiliation(s)
- G He
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - K Ghosh
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - U Singisetti
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - H Ramamoorthy
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - R Somphonsane
- ‡Department of Physics, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
| | - G Bohra
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - M Matsunaga
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - A Higuchi
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - N Aoki
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - S Najmaei
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Y Gong
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - X Zhang
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - R Vajtai
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - P M Ajayan
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - J P Bird
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
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Ramamoorthy H, Isaac B, Abraham P. Tenofovir induced renal damage is associated with activation of NF-κB inflammatory signaling pathway and PARP overactivation. BMC Infect Dis 2014. [PMCID: PMC4080194 DOI: 10.1186/1471-2334-14-s3-e5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Ramamoorthy H, Abraham P, Isaac B. Mitochondrial Dysfunction and Electron Transport Chain Complex Defect in a Rat Model of Tenofovir Disoproxil Fumarate Nephrotoxicity. J Biochem Mol Toxicol 2014; 28:246-55. [DOI: 10.1002/jbt.21560] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/04/2014] [Accepted: 02/11/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Hemalatha Ramamoorthy
- Departments of Biochemistry; Christian Medical College, Bagayam; Vellore 632 002 India
| | - Premila Abraham
- Departments of Biochemistry; Christian Medical College, Bagayam; Vellore 632 002 India
| | - Bina Isaac
- Departments of Anatomy; Christian Medical College, Bagayam; Vellore 632 002 India
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Ramamoorthy H, Abraham P, Isaac B. Preclinical efficacy of melatonin in the amelioration of tenofovir nephrotoxicity by the attenuation of oxidative stress, nitrosative stress, and inflammation in rats. J Basic Clin Physiol Pharmacol 2014; 25:1-13. [PMID: 24468618 DOI: 10.1515/jbcpp-2013-0135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 12/09/2013] [Indexed: 01/27/2023]
Abstract
Abstract Background: Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of human immunodeficiency virus (HIV) infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to better tolerance to TDF, and a more effective treatment can be achieved in HIV infected patients. Recent studies show that oxidative stress, nitrosative stress, and inflammation play a role in TDF nephrotoxicity. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats. Methods: Adult male rats were used for the study. Some rats received 600 mg/kg body weight TDF by gavage for 35 days, while others received once daily 20 mg/kg body weight melatonin i.p. 2 h before TDF administration. All the rats were sacrificed on the 36th day, after overnight fast. Results: Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced renal oxidative stress, nitrosative stress, and inflammation and preserved proximal tubular function. Histologically, melatonin pretreatment prevented TDF-induced proximal tubular injury and mitochondrial injury such as swelling, disruption of cristae, and deposition of amorphous material in the matrix. It restored the lysosomal and mitochondrial numbers in the proximal tubules also. Conclusions: Melatonin pretreatment protects rats from tenofovir-induced damage to proximal tubular mitochondria by attenuating oxidative stress, nitrosative stress, and inflammation. This suggests that it may be useful in ameliorating TDF nephrotoxicity in humans.
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Somphonsane R, Ramamoorthy H, Bohra G, He G, Ferry DK, Ochiai Y, Aoki N, Bird JP. Fast energy relaxation of hot carriers near the Dirac point of graphene. Nano Lett 2013; 13:4305-4310. [PMID: 23965117 DOI: 10.1021/nl4020777] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We investigate energy relaxation of hot carriers in monolayer and bilayer graphene devices, demonstrating that the relaxation rate increases significantly as the Dirac point is approached from either the conduction or valence band. This counterintuitive behavior appears consistent with ideas of charge puddling under disorder, suggesting that it becomes very difficult to excite carriers out of these localized regions. These results therefore demonstrate how the peculiar properties of graphene extend also to the behavior of its nonequilibrium carriers.
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Affiliation(s)
- R Somphonsane
- Department of Physics, University at Buffalo , Buffalo, New York 14260-1500, United States
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Abraham P, Ramamoorthy H, Isaac B. Depletion of the cellular antioxidant system contributes to tenofovir disoproxil fumarate - induced mitochondrial damage and increased oxido-nitrosative stress in the kidney. J Biomed Sci 2013; 20:61. [PMID: 23957306 PMCID: PMC3765371 DOI: 10.1186/1423-0127-20-61] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/16/2013] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Nephrotoxicity is a dose limiting side effect of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection. The mechanism of tenofovir nephrotoxicity is not clear. Tenofovir is specifically toxic to the proximal convoluted tubules and proximal tubular mitochondria are the targets of tenofovir cytotoxicity. Damaged mitochondria are major sources of reactive oxygen species and cellular damage is reported to occur after the antioxidants are depleted. The purpose of the study is to investigate the alterations in cellular antioxidant system in tenofovir induced renal damage using a rat model. RESULTS Chronic tenofovir administration to adult Wistar rats resulted in proximal tubular damage (as evidenced by light microscopy), proximal tubular dysfunction (as shown by Fanconi syndrome and tubular proteinuria), and extensive proximal tubular mitochondrial injury (as revealed by electron microscopy). A 50% increase in protein carbonyl content was observed in the kidneys of TDF treated rats as compared with the control. Reduced glutathione was decreased by 50%. The activity of superoxide dismutase was decreased by 57%, glutathione peroxidase by 45%, and glutathione reductase by 150% as compared with control. Carbonic Anhydrase activity was decreased by 45% in the TDF treated rat kidneys as compared with control. Succinate dehydrogenase activity, an indicator of mitochondrial activity was decreased by 29% in the TDF treated rat kidneys as compared with controls, suggesting mitochondrial dysfunction. CONCLUSION Tenofovir- induced mitochondrial damage and increased oxidative stress in the rat kidneys may be due to depletion of the antioxidant system particularly, the glutathione dependent system and MnSOD.
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Affiliation(s)
- Premila Abraham
- Department of Biochemistry, Christian Medical College, Bagayam, Vellore 632002, Tamil Nadu, India
| | - Hemalatha Ramamoorthy
- Department of Biochemistry, Christian Medical College, Bagayam, Vellore 632002, Tamil Nadu, India
| | - Bina Isaac
- Department of Anatomy, Christian Medical College, Bagayam, Vellore 632002, Tamil Nadu India
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Ramamoorthy H, Issac B, Abraham P. Evidence for the roles of oxidative stress, nitrosative stress and Nf-Kb activation in Tenofovir Disoproxil Fumarate (TDF) induced renal damage in rats. BMC Infect Dis 2012. [PMCID: PMC3344745 DOI: 10.1186/1471-2334-12-s1-p6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Abraham P, Isaac B, Ramamoorthy H, Natarajan K. Oral glutamine attenuates cyclophosphamide-induced oxidative stress in the bladder but does not prevent hemorrhagic cystitis in rats. J Med Toxicol 2011; 7:118-24. [PMID: 20661687 DOI: 10.1007/s13181-010-0103-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Cyclophosphamide (CP) is widely used in the treatment of cancer and non-malignant disease states such as rheumatoid arthritis. Hemorrhagic cystitis is a major dose-limiting side effect of CP. The incidence of this side effect is related to the dosage and can be as high as 75%. Elimination of the side effects of CP can lead to better tolerance of the drug, and a more efficient therapy can be achieved for patients in need of CP treatment. Several studies have demonstrated that oxidative stress and neutrophil infiltration play important roles in CP-induced bladder damage. Glutamine is utilized under clinical conditions for preventing chemotherapeutic drug-induced side effects, based on its ability to attenuate oxidative stress. The aim of the study is to verify whether glutamine prevents CP-induced oxidative stress and bladder damage using a rat model. Adult male rats were administered 150 mg/kg body weight of CP intraperitoneally. Glutamine pretreated rats were administered 1 g/kg body weight of glutamine orally 2 h before the administration of CP. Vehicle/glutamine-treated rats served as controls. All the rats were killed 16 h after the dose of CP/vehicle. The urinary bladders were removed and used for light microscopic and biochemical studies. The markers of oxidative stress including malondialdehyde content, protein carbonyl content, protein thiol, and myeloperoxidase activity, a marker of neutrophil infiltration, were measured in bladder homogenates. CP treatment induced hemorrhagic cystitis in the rats. Pretreatment with glutamine significantly reduced CP-induced lipid peroxidation (p < 0.01), protein oxidation (p < 0.01), and increase in myeloperoxidase activity (p < 0.05). However, it did not prevent CP-induced bladder damage. The results of the present study show that glutamine pretreatment does not attenuate CP-induced hemorrhagic cystitis, although it prevents CP-induced oxidative stress and neutrophil infiltration significantly. It is therefore necessary to clarify the utility of glutamine as a chemoprotective agent before it is recommended in the market as a nutrient supplement.
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Affiliation(s)
- Premila Abraham
- Department of Biochemistry, Christian Medical College, Bagayam, Vellore, 632002, Tamil Nadu, India.
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Thomas R, Rignot E, Casassa G, Kanagaratnam P, Acuña C, Akins T, Brecher H, Frederick E, Gogineni P, Krabill W, Manizade S, Ramamoorthy H, Rivera A, Russell R, Sonntag J, Swift R, Yungel J, Zwally J. Accelerated sea-level rise from West Antarctica. Science 2004; 306:255-8. [PMID: 15388895 DOI: 10.1126/science.1099650] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recent aircraft and satellite laser altimeter surveys of the Amundsen Sea sector of West Antarctica show that local glaciers are discharging about 250 cubic kilometers of ice per year to the ocean, almost 60% more than is accumulated within their catchment basins. This discharge is sufficient to raise sea level by more than 0.2 millimeters per year. Glacier thinning rates near the coast during 2002-2003 are much larger than those observed during the 1990s. Most of these glaciers flow into floating ice shelves over bedrock up to hundreds of meters deeper than previous estimates, providing exit routes for ice from further inland if ice-sheet collapse is under way.
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Affiliation(s)
- R Thomas
- EG&G Inc., NASA Goddard Space Flight Center (GSFC)/Wallops Flight Facility (WFF), Building N-159, Wallops Island, VA 23337, USA.
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