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Shewade HD, Frederick A, Kalyanasundaram M, Chadwick J, Kiruthika G, Rajasekar TD, Gayathri K, Vijayaprabha R, Sabarinathan R, Shivakumar SVBY, Jeyashree K, Bhavani PK, Aarthi S, Suma KV, Pathinathan DP, Parthasarathy R, Nivetha MB, Thampi JG, Chidambaram D, Bhatnagar T, Lokesh S, Devika S, Laux TS, Viswanathan S, Sridhar R, Krishnamoorthy K, Sakthivel M, Karunakaran S, Rajkumar S, Ramachandran M, Kanagaraj KD, Kaleeswari M, Durai VP, Saravanan R, Sugantha A, Khan SZHM, Sangeetha P, Vasudevan R, Nedunchezhian R, Sankari M, Jeevanandam N, Ganapathy S, Rajasekaran V, Mathavi T, Rajaprakash AR, Murali L, Pugal U, Sundaralingam K, Savithri S, Vellasamy S, Dheenadayal D, Ashok P, Jayasree K, Sudhakar R, Rajan KP, Tharageshwari N, Chokkalingam D, Anandrajkumar SM, Selvavinayagam TS, Padmapriyadarsini C, Ramachandran R, Murhekar MV. --Eleven tips for operational researchers working with health programmes: our experience based on implementing differentiated tuberculosis care in south India. Glob Health Action 2023; 16:2161231. [PMID: 36621943 PMCID: PMC9833404 DOI: 10.1080/16549716.2022.2161231] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Due to the workload and lack of a critical mass of trained operational researchers within their ranks, health systems and programmes may not be able to dedicate sufficient time to conducting operational research (OR). Hence, they may need the technical support of operational researchers from research/academic organisations. Additionally, there is a knowledge gap regarding implementing differentiated tuberculosis (TB) care in programme settings. In this 'how we did it' paper, we share our experience of implementing a differentiated TB care model along with an inbuilt OR component in Tamil Nadu, a southern state in India. This was a health system initiative through a collaboration of the State TB cell with the Indian Council of Medical Research institutes and the World Health Organisation country office in India. The learnings are in the form of eleven tips: four broad principles (OR on priority areas and make it a health system initiative, implement simple and holistic ideas, embed OR within routine programme settings, aim for long-term engagement), four related to strategic planning (big team of investigators, joint leadership, decentralised decision-making, working in advance) and three about implementation planning (conducting pilots, smart use of e-tools and operational research publications at frequent intervals). These may act as a guide for other Indian states, high TB burden countries that want to implement differentiated care, and for operational researchers in providing technical assistance for strengthening implementation and conducting OR in health systems and programmes (TB or other health programmes). Following these tips may increase the chances of i) an enriching engagement, ii) policy/practice change, and iii) sustainable implementation.
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Affiliation(s)
- Hemant Deepak Shewade
- ICMR – National Institute of Epidemiology, Chennai, India,CONTACT Hemant Deepak Shewade ; Department of Health Research, Government of India, ICMR-National Institute of Epidemiology, R-127, Second Main Road, TNHB, Ayapakkam, Chennai600077, India
| | | | | | | | - G. Kiruthika
- ICMR – National Institute of Epidemiology, Chennai, India
| | | | - K. Gayathri
- ICMR – National Institute of Epidemiology, Chennai, India
| | | | | | | | | | - P. K. Bhavani
- ICMR – National Institute for Research in Tuberculosis, Chennai, India
| | - S. Aarthi
- State TB Cell, Government of Tamil Nadu, Chennai, India
| | - K. V. Suma
- The WHO Country Office for India, New Delhi, India
| | | | | | | | | | | | | | - S. Lokesh
- ICMR – National Institute of Epidemiology, Chennai, India
| | | | | | - Stalin Viswanathan
- Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India
| | - R. Sridhar
- Government Hospital of Thoracic Medicine, Tambaram, India
| | - K. Krishnamoorthy
- Department of Respiratory Medicine, Tirunelveli Medical College Hospital, Tirunelveli, India
| | - M. Sakthivel
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Karunakaran
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Rajkumar
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - M. Ramachandran
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - K. D. Kanagaraj
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - M. Kaleeswari
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - V. P. Durai
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - R. Saravanan
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - A. Sugantha
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | | | - P. Sangeetha
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - R. Vasudevan
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - R. Nedunchezhian
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - M. Sankari
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - N. Jeevanandam
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Ganapathy
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - V. Rajasekaran
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - T. Mathavi
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - A. R. Rajaprakash
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - Lakshmi Murali
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - U. Pugal
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - K. Sundaralingam
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Savithri
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Vellasamy
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - D. Dheenadayal
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - P. Ashok
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - K. Jayasree
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - R. Sudhakar
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - K. P. Rajan
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | | | | | | | - T. S. Selvavinayagam
- Directorate of Public Health and Preventive Medicine, Government of Tamil Nadu, Chennai, India
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Aldahish A, Vasudevan R, Salem H, Alqahtani A, AlQasim S, Alqhatani A, Al Shahrani M, Al Mohsen L, Hajla M, Calina D, Sharifi-Rad J. Telogen effluvium and COVID-19: a cross-sectional study. Eur Rev Med Pharmacol Sci 2023; 27:7823-7830. [PMID: 37667959 DOI: 10.26355/eurrev_202308_33437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
OBJECTIVE COVID-19 is a febrile infectious disease caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). This virus affects several organs, including the skin. Acute telogen effluvium (TE) is a non-scarring hair loss characterized by diffuse hair shedding that begins three months after a stressful event and can last up to six months. COVID-19 infection is one of these potential stressors. Recently, there has been a reported link between increased scalp hair shedding and post-infection patients during the COVID-19 outbreak. The present work aimed to study the possible effects of COVID-19 on hair and the relationship between COVID-19 and TE and to assess the level of awareness about TE in the Asir region of Saudi Arabia. SUBJECTS AND METHODS A questionnaire-based cross-sectional study was conducted using a pre-validated questionnaire. The study involved 561 participants from the Asir region of Saudi Arabia. Eligible participants were individuals from the Asir region who were 20 years of age or older, had previously contracted COVID-19 and had no history of TE before infection. All statistical methods used were two-tailed with an alpha level of 0.05, considering significance if the p-value was lower than or equal to 0.05. RESULTS A total of 1,000 eligible participants completed the study questionnaire. The mean age was 32.5 ± 13.9 years, and 494 (88.1%) participants were females. In addition, 558 (99.5%) of the study participants had received the COVID-19 vaccine. A total of 411 (73.3%) participants experienced an increase in hair loss after COVID-19 infection, and 171 (30.5%) began suffering from pain when combing their hair. In addition, 182 participants (32.4%) had a family history of TE. Only 109 (10.9%) participants had a good awareness level about TE, while 452 (80.6%) had an overall poor awareness level. There was a significant relationship between the level of awareness and age, where 23.9% of the participants aged 20-29 years had a good level of awareness vs. 16.1% of others aged 40 years or older (p = 0.041). Moreover, 26.9% of participants with a family history of TE had a good awareness of TE, vs. 15.8% of those with no family history of TE (p = 0.002). In addition, significant correlations were found between increased hair loss post-COVID-19 infection and female gender (77.3% vs. 43.3%; p = 0.001) as well as suffering from pain when combing hair (86.5% vs. 65.5%; p = 0.001). CONCLUSIONS In our study, the incidence of TE was highly related to COVID-19 infections among both sexes. However, the incidence was greater among the female population. The awareness level toward post-COVID-19 TE was poor among most of the participants in our study.
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Affiliation(s)
- A Aldahish
- Department of Pharmacology, King Khalid University, Abha, Kingdom of Saudi Arabia.
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Shewade HD, Frederick A, Kiruthika G, Kalyanasundaram M, Chadwick J, Rajasekar TD, Gayathri K, Vijayaprabha R, Sabarinathan R, Kathiresan J, Bhavani P, Aarthi S, Suma K, Pathinathan DP, Parthasarathy R, Nivetha MB, Thampi JG, Chidambaram D, Bhatnagar T, Lokesh S, Devika S, Laux TS, Viswanathan S, Sridhar R, Krishnamoorthy K, Sakthivel M, Karunakaran S, Rajkumar S, Ramachandran M, Kanagaraj K, Kaleeswari M, Durai V, Saravanan R, Sugantha A, Khan SZHM, Sangeetha P, Vasudevan R, Nedunchezhian R, Sankari M, Jeevanandam N, Ganapathy S, Rajasekaran V, Mathavi T, Rajaprakash A, Murali L, Pugal U, Sundaralingam K, Savithri S, Vellasamy S, Dheenadayal D, Ashok P, Jayasree K, Sudhakar R, Rajan K, Tharageshwari N, Chokkalingam D, Anandrajkumar S, Selvavinayagam T, Padmapriyadarshini C, Ramachandran R, Murhekar MV. The First Differentiated TB Care Model From India: Delays and Predictors of Losses in the Care Cascade. Glob Health Sci Pract 2023; 11:e2200505. [PMID: 37116929 PMCID: PMC10141439 DOI: 10.9745/ghsp-d-22-00505] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/07/2023] [Indexed: 04/03/2023]
Abstract
To reduce TB deaths in resource-limited settings, a differentiated care strategy can be used to triage patients with high risk of severe illness (i.e., those with very severe undernutrition, respiratory insufficiency, or inability to stand without support) at diagnosis and refer them for comprehensive assessment and inpatient care. Globally, there are few examples of implementing this type of strategy in routine program settings. Beginning in April 2022, the Indian state of Tamil Nadu implemented a differentiated care strategy called Tamil Nadu-Kasanoi Erappila Thittam (TN-KET) for all adults aged 15 years and older with drug-susceptible TB notified by public facilities. Before evaluating the impact on TB deaths, we sought to understand the retention and delays in the care cascade as well as predictors of losses. During April-June 2022, 14,961 TB patients were notified and 11,599 (78%) were triaged. Of those triaged, 1,509 (13%) were at high risk of severe illness; of these, 1,128 (75%) were comprehensively assessed at a nodal inpatient care facility. Of 993 confirmed as severely ill, 909 (92%) were admitted, with 8% unfavorable admission outcomes (4% deaths). Median admission duration was 4 days. From diagnosis, the median delay in triaging and admission of severely ill patients was 1 day each. Likelihood of triaging decreased for people with extrapulmonary TB, those diagnosed in high-notification districts or teaching hospitals, and those transferred out of district. Predictors of not being comprehensively assessed included: aged 25-34 years, able to stand without support, and diagnosis at a primary or secondary-level facility. Inability to stand without support was a predictor of unfavorable admission outcomes. To conclude, the first quarter of implementation suggests that TN-KET was feasible to implement but could be improved by addressing predictors of losses in the care cascade and increasing admission duration.
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Affiliation(s)
- Hemant Deepak Shewade
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | | | - G. Kiruthika
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | | | - Joshua Chadwick
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | - T. Daniel Rajasekar
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | - K. Gayathri
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | - R. Vijayaprabha
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | - R. Sabarinathan
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | - Jeyashree Kathiresan
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | - P.K. Bhavani
- Indian Council of Medical Research, National Institute for Research in Tuberculosis, Chennai, India
| | - S. Aarthi
- State TB Cell, Government of Tamil Nadu, Chennai, India
| | - K.V. Suma
- World Health Organization Country Office for India, New Delhi, India
| | | | | | | | - Jerome G. Thampi
- World Health Organization Country Office for India, New Delhi, India
| | | | - Tarun Bhatnagar
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | - S. Lokesh
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | | | | | - Stalin Viswanathan
- Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
| | - R. Sridhar
- Government Hospital of Thoracic Medicine, Tambaram, India
| | | | - M. Sakthivel
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Karunakaran
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Rajkumar
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - M. Ramachandran
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - K.D. Kanagaraj
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - M. Kaleeswari
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - V.P. Durai
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - R. Saravanan
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - A. Sugantha
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | | | - P. Sangeetha
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - R. Vasudevan
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - R. Nedunchezhian
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - M. Sankari
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - N. Jeevanandam
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Ganapathy
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - V. Rajasekaran
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - T. Mathavi
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - A.R. Rajaprakash
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - Lakshmi Murali
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - U. Pugal
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - K. Sundaralingam
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Savithri
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - S. Vellasamy
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - D. Dheenadayal
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - P. Ashok
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - K. Jayasree
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - R. Sudhakar
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | - K.P. Rajan
- Directorate of Medical and Rural Health Services, Government of Tamil Nadu, Chennai, India
| | | | - D. Chokkalingam
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
| | | | - T.S. Selvavinayagam
- Directorate of Public Health and Preventive Medicine, Government of Tamil Nadu, Chennai, India
| | - C. Padmapriyadarshini
- Indian Council of Medical Research, National Institute for Research in Tuberculosis, Chennai, India
| | | | - Manoj V. Murhekar
- Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India
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Solymosi D, Nikkanen L, Muth-Pawlak D, Fitzpatrick D, Vasudevan R, Howe CJ, Lea-Smith DJ, Allahverdiyeva Y. Cytochrome c M Decreases Photosynthesis under Photomixotrophy in Synechocystis sp. PCC 6803. Plant Physiol 2020; 183:700-716. [PMID: 32317358 PMCID: PMC7271781 DOI: 10.1104/pp.20.00284] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 03/23/2020] [Indexed: 05/26/2023]
Abstract
Photomixotrophy is a metabolic state that enables photosynthetic microorganisms to simultaneously perform photosynthesis and metabolism of imported organic carbon substrates. This process is complicated in cyanobacteria, since many, including Synechocystis sp. PCC 6803, conduct photosynthesis and respiration in an interlinked thylakoid membrane electron transport chain. Under photomixotrophy, the cell must therefore tightly regulate electron fluxes from photosynthetic and respiratory complexes. In this study, we demonstrate, via characterization of photosynthetic apparatus and the proteome, that photomixotrophic growth results in a gradual inhibition of QA - reoxidation in wild-type Synechocystis, which largely decreases photosynthesis over 3 d of growth. This process is circumvented by deleting the gene encoding cytochrome c M (CytM), a cryptic c-type heme protein widespread in cyanobacteria. The ΔCytM strain maintained active photosynthesis over the 3-d period, demonstrated by high photosynthetic O2 and CO2 fluxes and effective yields of PSI and PSII. Overall, this resulted in a higher growth rate compared to that of the wild type, which was maintained by accumulation of proteins involved in phosphate and metal uptake, and cofactor biosynthetic enzymes. While the exact role of CytM has not been determined, a mutant deficient in the thylakoid-localized respiratory terminal oxidases and CytM (ΔCox/Cyd/CytM) displayed a phenotype similar to that of ΔCytM under photomixotrophy. This, in combination with other physiological data, and in contrast to a previous hypothesis, suggests that CytM does not transfer electrons to these complexes. In summary, our data suggest that CytM may have a regulatory role in photomixotrophy by modulating the photosynthetic capacity of cells.
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Affiliation(s)
- Daniel Solymosi
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku FI-20014, Finland
| | - Lauri Nikkanen
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku FI-20014, Finland
| | - Dorota Muth-Pawlak
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku FI-20014, Finland
| | - Duncan Fitzpatrick
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku FI-20014, Finland
| | - Ravendran Vasudevan
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Christopher J Howe
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - David J Lea-Smith
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Yagut Allahverdiyeva
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku FI-20014, Finland
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Vasudevan R, Gale GAR, Schiavon AA, Puzorjov A, Malin J, Gillespie MD, Vavitsas K, Zulkower V, Wang B, Howe CJ, Lea-Smith DJ, McCormick AJ. CyanoGate: A Modular Cloning Suite for Engineering Cyanobacteria Based on the Plant MoClo Syntax. Plant Physiol 2019; 180:39-55. [PMID: 30819783 PMCID: PMC6501082 DOI: 10.1104/pp.18.01401] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 02/16/2019] [Indexed: 05/10/2023]
Abstract
Recent advances in synthetic biology research have been underpinned by an exponential increase in available genomic information and a proliferation of advanced DNA assembly tools. The adoption of plasmid vector assembly standards and parts libraries has greatly enhanced the reproducibility of research and the exchange of parts between different labs and biological systems. However, a standardized modular cloning (MoClo) system is not yet available for cyanobacteria, which lag behind other prokaryotes in synthetic biology despite their huge potential regarding biotechnological applications. By building on the assembly library and syntax of the Plant Golden Gate MoClo kit, we have developed a versatile system called CyanoGate that unites cyanobacteria with plant and algal systems. Here, we describe the generation of a suite of parts and acceptor vectors for making (1) marked/unmarked knock-outs or integrations using an integrative acceptor vector, and (2) transient multigene expression and repression systems using known and previously undescribed replicative vectors. We tested and compared the CyanoGate system in the established model cyanobacterium Synechocystis sp. PCC 6803 and the more recently described fast-growing strain Synechococcus elongatus UTEX 2973. The UTEX 2973 fast-growth phenotype was only evident under specific growth conditions; however, UTEX 2973 accumulated high levels of proteins with strong native or synthetic promoters. The system is publicly available and can be readily expanded to accommodate other standardized MoClo parts to accelerate the development of reliable synthetic biology tools for the cyanobacterial community.
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Affiliation(s)
- Ravendran Vasudevan
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Grant A R Gale
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, United Kingdom
| | - Alejandra A Schiavon
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Anton Puzorjov
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - John Malin
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Michael D Gillespie
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Konstantinos Vavitsas
- Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland 4072, Australia
- CSIRO, Synthetic Biology Future Science Platform, Brisbane, Queensland 4001, Australia
| | - Valentin Zulkower
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Baojun Wang
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, United Kingdom
| | - Christopher J Howe
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - David J Lea-Smith
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Alistair J McCormick
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
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Ching SM, Hamidin A, Vasudevan R, Sazlyna MSL, Wan Aliaa WS, Foo YL, Yee A, Hoo FK. Prevalence and factors associated with internet addiction among medical students - A cross-sectional study in Malaysia. Med J Malaysia 2017; 72:7-11. [PMID: 28255133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
INTRODUCTION Internet is important to university students, especially for medical students who use it to search for literature and relevant information. However, some of the users are experiencing a gradual loss of the ability to reduce the duration and frequency of their internet activities, despite the negative consequences. The literature on internet usage among Malaysian medical students is limited. This study aims to determine the prevalence and factors associated with internet usage among medical students in a public university in Malaysia. METHODS This cross-sectional study was performed among all the medical students (Year 1-5). Students were assessed on their internet activities using the internet addiction questionnaires (IAT). A Multiple Logistic Regression was used for data analysis. RESULTS The study was conducted among 426 students. The study population consisted of 156 males (36.6%) and 270 females (63.4%). The mean age was 21.6 ±1.5 years. Ethnicity distribution among the students was: Malays (55.6%), Chinese (34.7%), Indians (7.3%) and others (2.3%). According to the IAT, 36.9% of the study sample was addicted to the internet. Using the multivariate logistic regression analysis, we have found that the use of internet access for entertainment purposes (odds ratio [OR] 3.5, 95% confidence interval [CI] 1.05-12.00), male students (OR 1.8, 95% CI 1.01-3.21) and increasing frequency of internet usage were associated with internet addiction (OR 1.4, 95% CI 1.09- 1.67). CONCLUSION Internet addiction is a relatively frequent phenomenon among medical students. The predictors of internet addiction were male students using it for surfing and entertainment purposes.
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Affiliation(s)
- S M Ching
- Universiti Putra Malaysia, Faculty of Medicine and Health Sciences, Department of Family Medicine, Selangor, Malaysia.
| | - A Hamidin
- Universiti Putra Malaysia, Faculty of Medicine and Health Sciences, Department of Psychiatric, Selangor, Malaysia
| | - R Vasudevan
- Universiti Putra Malaysia, Malaysia Research Institute of Ageing, Selangor, Malaysia
| | - M S L Sazlyna
- Universiti Putra Malaysia, Faculty of Medicine and Health Sciences, Department of Medicine, Selangor, Malaysia
| | - W S Wan Aliaa
- Universiti Putra Malaysia, Faculty of Medicine and Health Sciences, Department of Medicine, Selangor, Malaysia
| | - Y L Foo
- Universiti Putra Malaysia, Faculty of Medicine and Health Sciences, Department of Medicine, Selangor, Malaysia
| | - A Yee
- University of Malaya, Faculty of Medicine, Department of Psychological Medicine, Kuala Lumpur, Malaysia
| | - F K Hoo
- Universiti Putra Malaysia, Faculty of Medicine and Health Sciences, Department of Medicine, Selangor, Malaysia
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Abstract
The object of this paper is to study the actual waiting time of a customer in a GI/G/1 queue. This is an important criterion from the viewpoint of both the customers and the efficient functioning of the counter. Suitable point processes in the product space of load and time parameters for any general inter-arrival and service time distributions are defined and integral equations governing the correlation functions are set up. Solutions of these equations are obtained and with the help of these, explicit expressions for the first two moments of the number of customers who have waited for a time longer than w in a given time interval (0, T) are calculated.
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Abstract
Cyanobacteria are ecologically important organisms and potential platforms for production of biofuels and useful industrial products. Genetic manipulation of cyanobacteria, especially model organisms such as Synechocystis sp. PCC6803 and Synechococcus sp. PCC7002, is a key tool for both basic and applied research. Generation of unmarked mutants, whereby chromosomal alterations are introduced into a strain via insertion of an antibiotic resistance cassette (a manipulatable fragment of DNA containing one or more genes), followed by subsequent removal of this cassette using a negative selectable marker, is a particularly powerful technique. Unmarked mutants can be repeatedly genetically manipulated, allowing as many alterations to be introduced into a strain as desired. In addition, the absence of genes encoding antibiotic resistance proteins in the mutated strain is desirable, as it avoids the possibility of 'escape' of antibiotic resistant organisms into the environment. However, detailed methods for repeated rounds of genetic manipulation of cyanobacteria are not well described in the scientific literature. Here we provide a comprehensive description of this technique, which we have successfully used to generate mutants with multiple deletions, single point mutations within a gene of interest and insertion of novel gene cassettes.
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Etemad A, Vasudevan R, Aziz A, Yusof A, Khazaei S, Fawzi N, Jamalpour S, Arkani M, Mohammad N, Ismail P. Analysis of selected glutathione S-transferase gene polymorphisms in Malaysian type 2 diabetes mellitus patients with and without cardiovascular disease. Genet Mol Res 2016; 15:gmr5845. [DOI: 10.4238/gmr.15025845] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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10
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Komara M, Vasudevan R, Ismail P, Bakar SA, Pishva SR, Heidari F. Association of beta 2 adrenoceptor gene polymorphisms in Malaysian hypertensive subjects. Genet Mol Res 2014; 13:2939-48. [PMID: 24782128 DOI: 10.4238/2014.april.16.2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The sympathetic nervous system plays a major role in blood pressure regulation. Beta 2 (β2) adrenoceptor gene polymorphisms have been associated with hypertension in different populations with conflicting results. We examined the association of three common polymorphisms, Arg16Gly, Gln27Glu, and Thr164Ile, of the β2 adrenoceptor gene in Malaysian hypertensive subjects. A total of 160 hypertensive and control subjects were recruited. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and anthropometric measurements were obtained from each subject. Biochemical analyses of lipid profiles were conducted with an autoanalyzer. DNA samples were extracted from blood and buccal cells. Genotyping was accomplished with polymerase chain reaction-restriction fragment length polymorphism. SBP, DBP, body mass index, and biochemical factors all differed significantly between case and control subjects (P < 0.05). The genotype frequencies of Arg16Arg, Arg16Gly, and Gly16Gly were 22.5, 70, and 7.5% among cases and 33.1, 63.1, and 3.8% among controls, respectively. The genotype frequencies of Gln27Gln, Gln27Glu, and Glu27Glu among cases were 41.1, 50, and 1.9% compared to 77.5, 20.6, and 1.9% among controls, respectively. In this study, the Gln27Glu polymorphism was significantly associated with Malaysian hypertensive subjects (P < 0.05). Therefore, the Gln27Glu polymorphism of the β2 adrenoceptor could be a risk factor associated with hypertension among Malaysians.
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Affiliation(s)
- M Komara
- Genetic Research Group, Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia
| | - R Vasudevan
- Institute of Gerontology, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - P Ismail
- Genetic Research Group, Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia
| | - S A Bakar
- Genetic Research Group, Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia
| | - S R Pishva
- Genetic Research Group, Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia
| | - F Heidari
- Genetic Research Group, Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia
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11
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Hussein AA, Vasudevan R, Patimah I, Prashant N, Nora FA. Association of azoospermia factor region deletions in infertile male subjects among Malaysians. Andrologia 2014; 47:168-77. [PMID: 24528375 DOI: 10.1111/and.12240] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2013] [Indexed: 11/29/2022] Open
Abstract
Azoospermia factor region (AZF) deletions (AZFa, AZFb, AZFc and AZFd) in the Y chromosome were analysed in male infertility subjects in various populations with conflicting results. This study comprised of 54 infertile males and 63 fertile controls, and the frequency of AZFa, AZFb, AZFc and AZFd deletions were determined using conventional polymerase chain reaction (PCR) as well as real-time PCR-high resolution melting analysis-based methods. The results of this study showed that, three of 54 cases (5.55%) had AZF (a, b and c) deletions (two had AZFc and one had AZFa deletions). Four cases were found to have AZFd deletions (7.4%) with two of them being associated with AZFc deletions (P = 0.028). The frequency of AZF (a, b and c) deletions in Malaysian infertile male subjects was found to be comparable with other populations. AZFd deletions were found to be significant (P < 0.05) in male infertility and it may be associated with other types of AZF deletions.
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Affiliation(s)
- A A Hussein
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
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12
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Affiliation(s)
- R P S Tomar
- Classified Specialist (Pediatrics & Neonatology), MH Jalandhar Cantt, Punjab 144005, India
| | - R Vasudevan
- Senior Advisor (Pediatrics), MH Jalandhar Cantt, Punjab, India
| | - Manoj Kumar
- Classified Specialist (ENT), MH Jalandhar Cantt, Jalandhar, Punjab, India
| | - D K Gupta
- Graded Specialist (ENT), MH Jalandhar Cantt, Jalandhar, Punjab, India
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Tomar RPS, Vasudevan R. Metabolic acidosis due to inhaled salbutamol toxicity: A hazardous side effect complicating management of suspected cases of acute severe asthma. Med J Armed Forces India 2012; 68:242-4. [PMID: 24532877 DOI: 10.1016/j.mjafi.2011.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2011] [Revised: 09/14/2011] [Accepted: 10/08/2011] [Indexed: 10/28/2022] Open
Abstract
Metabolic acidosis has seldom been reported during treatment of asthma with use of beta agonist but not with much clinical consequence. We report two cases of metabolic acidosis with hyperventilation as a direct effect of salbutamol that caused difficulty in assessment and management of their respiratory symptoms which resolved with appropriate tapering of beta agonist.
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Affiliation(s)
- R P S Tomar
- Classified Specialist, Dept of Paediatrics & Neonatology, MH Jalandhar Cant, Punjab 144005, India
| | - R Vasudevan
- Senior Advisor, Dept of Paediatrics & Neonatology, MH Jalandhar Cant, Punjab 144005, India
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Affiliation(s)
- Rps Tomar
- Classified Specialist (Paediatrics & Neonatology), Military Hospital, Jalandhar Cantt., Punjab - 144005
| | - D Vashisth
- Graded Specialist (Dermatology & Venereology), Military Hospital, Jalandhar Cantt., Punjab - 144005
| | - R Vasudevan
- Senior Advisor (Paediatrics), Military Hospital, Jalandhar Cantt., Punjab - 144005
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Vasudevan R, Norhasniza M, Patimah I. Association of variable number of tandem repeats polymorphism in the IL-4 gene with end-stage renal disease in Malaysian patients. Genet Mol Res 2011; 10:943-7. [DOI: 10.4238/vol10-2gmr1066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Vasudevan R, Ismail P, Stanslas J, Shamsudin N, Ali AB. Association of insertion/deletion polymorphism of alpha-adrenoceptor gene in essential hypertension with or without type 2 diabetes mellitus in Malaysian subjects. Int J Biol Sci 2008; 4:362-7. [PMID: 18953403 PMCID: PMC2567812 DOI: 10.7150/ijbs.4.362] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [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: 06/10/2008] [Accepted: 09/29/2008] [Indexed: 11/25/2022] Open
Abstract
An insertion/deletion (I/D) polymorphism of Alpha2B-Adrenoceptor (ADRA2B) gene located on chromosome 2 has been studied extensively in related to cardiovascular diseases. The main aim of the present study was to examine the potential association of D allele frequency of I/D polymorphism of ADRA2B gene in Malaysian essential hypertensive subjects with or without type 2 diabetes mellitus (T2DM). This study includes 70 hypertensive subjects without T2DM, 65 hypertensive subjects with T2DM and 75 healthy volunteers as control subjects. Genotyping of I/D polymorphism was performed by conventional PCR method. There was significant difference found in age, body mass index, systolic/diastolic blood pressure and high density lipoprotein cholesterol level between the case and control subjects. DD genotypic frequency of I/D polymorphism was significantly higher in hypertensive subjects (42.84% vs. 29.33%; P=0.029) and in hypertensive with T2DM subjects (46.15% vs. 29.33%; P=0.046) than control group. D allele frequency was higher in hypertensive group (67.41%) than control subjects (52.67%). However, no significant difference was found between the three genotypes of I/D polymorphism of ADRA2B gene and the clinical characteristics of the subjects. The result obtained in this study show D allele of ADRA2B gene was associated with essential hypertension with or without T2DM in Malaysian subjects.
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Affiliation(s)
- R Vasudevan
- Molecular Biology Lab, Department of Biomedical Science, Universiti Putra Malaysia, Serdang 43400, Malaysia
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Vasudevan R, Ismail P, Stanslas J, Shamsudin N. Association of G2350A Polymorphism of Angiotensin Converting Enzyme Gene with Essential Hypertension and Type 2 Diabetes Mellitus in Malaysian Subjects. ACTA ACUST UNITED AC 2008. [DOI: 10.3923/jbs.2008.1045.1050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Vasudevan R, Ismail P, Stanslas J, Shamsudin N. C-511T Polymorphism of Interleukin-1 β Gene is Not Associated in Type 2 Diabetes Mellitus-A Study in Malaysian Population. J of Medical Sciences 2008. [DOI: 10.3923/jms.2008.216.221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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20
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Affiliation(s)
- C Kumaravelu
- Department of Oral Surgery, Tamil Nadu Government Dental College, Chennai, India
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21
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Hill T, Vasudevan R. Loosening the ties. Interview by Maura Thompson. Health Serv J 2000; 110:34-5. [PMID: 11184499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
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Abstract
BACKGROUND Reports of patients with idiopathic thrombocytopenic purpura undergoing cardiac operations are scarce and no recommendations exist regarding their management. We report 3 patients with idiopathic thrombocytopenic purpura and severe coronary artery disease who underwent uncomplicated coronary bypass grafting. METHODS The case history of each patient with idiopathic thrombocytopenic purpura who underwent coronary artery bypass grafting and the literature were reviewed. RESULTS All 3 patients underwent uncomplicated coronary artery bypass grafting after preoperative treatment with intravenous immunoglobulin and intraoperative platelet transfusions if needed. Prophylactic splenectomy was not performed. There was no increased incidence of bleeding complications. CONCLUSIONS Coronary artery bypass grafting can be safely performed in patients with idiopathic thrombocytopenic purpura using conventional conduits after pretreating with immunoglobulin G and avoiding splenectomy.
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Affiliation(s)
- T C Mathew
- Department of Medicine, Saint Vincent Hospital and University of Massachusetts Medical School, Worcester 01604, USA
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23
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Prasad PBSNV, Ahila S, Vasudevan R, Seshadri SK. Fatigue strength of nickel electrodeposits prepared in ultrasonically agitated bath. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf02352906] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Sridhar R, Vasudevan R. Anyon superfluidity in the framework of nonrelativistic-current algebra. Phys Rev B Condens Matter 1994; 49:670-673. [PMID: 10009338 DOI: 10.1103/physrevb.49.670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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25
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Prasad PBSNVP, Ahila S, Vasudevan R, Seshadri SK. Corrosion resistance of zinc electrodeposits in an ultrasonically agitated bath. ACTA ACUST UNITED AC 1993. [DOI: 10.1007/bf00517601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Badrinath SS, Vasudevan R, Murugesan R, Basti S, Nicholson AD, Singh P, Gopal L, Sharma T, Rao SB, Abraham C. Intraoperative measurement of intraocular pressure in vitrectomized aphakic air-filled eyes using the Tono-Pen XL. Retina 1993; 13:307-11. [PMID: 8115731 DOI: 10.1097/00006982-199313040-00007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [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: 01/28/2023]
Abstract
The Tono-Pen XL (Bio-Rad, Santa Ana, CA) was compared with manometer readings for intraoperative measurement of intraocular pressure (IOP) in 40 eyes of 40 consecutive patients after vitrectomy, lensectomy, and fluid-air exchange. Tono-Pen readings corresponding to manometer readings of 10, 20, 30, 40, and 50 mmHg were obtained in a masked fashion with a randomized sequence of manometer readings. A correlation was obtained between the manometer and Tono-Pen readings (r = 0.96 in emmetropic eyes and r = 0.93 in myopic eyes). The regression curve that represents the calibration curve of Tono-Pen in terms of the manometer readings for air-filled vitrectomized eyes was obtained. Any Tono-Pen reading can be easily translated into the corresponding manometer reading by referring to the curve. The Tono-Pen can therefore be effectively used to accurately determine intraoperative IOP in eyes undergoing vitrectomy, lensectomy, and fluid-air exchange.
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Affiliation(s)
- S S Badrinath
- Vitreoretinal Department, Sankara Nethralaya, Medical Research Foundation, Madras, India
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Rajagopal AK, Vasudevan R. Linearized gap equation for a superconductor in a strong magnetic field. Phys Rev B Condens Matter 1991; 44:2807-2810. [PMID: 9999857 DOI: 10.1103/physrevb.44.2807] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ramesh R, Vasudevan R, Kolster BH, Pathiraj B. X-ray evidence for structural transformation in Ni3Al alloys at higher temperatures. Naturwissenschaften 1990. [DOI: 10.1007/bf01134474] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Anishetty R, Vasudevan R. Analysis of neural dynamics and memory organization. Neurol Res 1989; 11:233-7. [PMID: 2576107 DOI: 10.1080/01616412.1989.11739898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 01/01/2023]
Abstract
We analysed neural network dynamics by a Caianiello type of equation with special reference to memory organization and the corresponding synaptic connection matrix. Global analysis of the dynamics yielded only stable equilibrium configurations and no periodic solutions.
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Affiliation(s)
- R Anishetty
- Institute of Mathematical Sciences, Madras, India
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Balakrishnan R, Sridhar R, Vasudevan R. Hydrodynamics of superfluid 4He in a pseudospin model. Phys Rev B Condens Matter 1989; 39:174-182. [PMID: 9947136 DOI: 10.1103/physrevb.39.174] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Venugopal P, Venkatraman S, Vasudevan R, Padmanabhan K. Some failure studies in the Hooker extrusion of sintered iron powder metallurgical preforms. ACTA ACUST UNITED AC 1988. [DOI: 10.1016/0378-3804(88)90158-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Vittal P, Vasudevan R. 9. Queues, storage and inventories. Stoch Process Their Appl 1984. [DOI: 10.1016/0304-4149(84)90261-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract
To study the phenomenon of spike discharge in a single neuron, first-passage time density of the membrane potential to cross or reach the threshold value in different situations is analyzed. The neuron is taken as a leaky integrator and the inputs are due to Poisson events occurring independently. Closed solutions using the compensation method and imbedding techniques are arrived at. Using Keilson's limiting procedure, diffusion processes with boundaries are solved. To simulate the refractory period of the neuron, thresholds moving linearly or exponentially with time are considered. Very interesting Wald identities are obtained in the case of jump processes which go over to the corresponding identities for diffusion processes obtained by a limiting procedure.
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Abstract
Stochastic models for the spike discharge activity of neurons are analyzed. Model I treats only excitatory impulses occurring as Poisson events with exponential density of the jump magnitude, and, in the absence of these events, the subthreshold potential decays exponentially. A closed solution for the Laplace transform of the renewal density of the discharge is obtained by the imbedding method. Model III takes care of both excitatory and inhibitory impulses with exponential decay of the subthreshold potential between the jumps. Analytical closed solutions for the first passage problem are obtained in this care also. The mean interval time between the spikes and the stationary density of firing are obtained.
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Bellman R, Vasudevan R, Ueno S. Invariant imbedding and radiation dosimetry X. Intensity of finite order scattered gamma radiation emergent from a target slab with internal sources. Math Biosci 1975. [DOI: 10.1016/0025-5564(75)90116-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Bellman R, Fymat A, Ueno S, Vasudevan R. Invariant imbedding and radiation dosimetry: IX. inverse problem of determining a plane source in a finite isotropically scattering target slab. Math Biosci 1974. [DOI: 10.1016/0025-5564(74)90007-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Bellman R, Ueno S, Vasudevan R. Invariant imbedding and radiation dosimetry: VIII. reflection function from a double layer— finite order functions. Math Biosci 1974. [DOI: 10.1016/0025-5564(74)90006-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Bellman R, Ueno S, Vasudevan R. Invariant imbedding and radiation dosimetry VII: finite order scattering and transmission functions of the two radiation approximations in a target slab. Math Biosci 1973. [DOI: 10.1016/0025-5564(73)90003-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Ibáñez P, Vasudevan R, Vineberg E. A comparison of experimental methods for seismic testing of equipment. Nuclear Engineering and Design 1973. [DOI: 10.1016/0029-5493(73)90065-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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49
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Bellman R, Ueno S, Vasudevan R. Invariant imbedding and radiation dosimetry: IV. finite order scattering of gamma radiation by a target slab. Math Biosci 1973. [DOI: 10.1016/0025-5564(73)90063-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bellman R, Ueno S, Vasudevan R. Invariant imbedding and radiation dosimetry—III integral recurrence relations for finite order X and Y functions. Math Biosci 1972. [DOI: 10.1016/0025-5564(72)90035-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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