Publications by authors named "A Ramesh Kumar"

24,716 Publications

Sea ice variability and trends in the Indian Ocean sector of Antarctica: Interaction with ENSO and SAM.

Environ Res 2022 May 16:113481. Epub 2022 May 16.

National Centre for Polar and Ocean Research, Ministry of Earth Sciences (Govt. of India), Goa, India.

Antarctic sea ice variability is primarily associated with ocean-atmospheric forcing driven by anomalous conditions over the tropical regions of the Pacific and Indian Oceans. The ice-ocean-atmosphere dynamics in the Indian Ocean Sector (IOS) of Antarctica have been studied using monthly satellite and reanalysis observations over four decades (1979-2019). In this study, we revealed that the annual sea ice extent (SIE) in the IOS increases at a rate of 0.7 ± 0.9% decade, with a significant increase in austral summer (5.9 ± 3.7% decade). The wavelet approach was used to determine variability in IOS sea ice caused by the El Niño/Southern Oscillation (ENSO) and the southern annular mode (SAM). The SIE has a significant association with both indices during the summer and autumn. In comparison to ENSO, the sea ice variability associated with SAM is typically seasonal in nature and lacks distinct patterns. The wavelet coherence analysis revealed a relatively weak relationship between ENSO and SAM but a highly significant coherence between climatic indices and SIE. We observed that sea ice in the IOS is influenced significantly by climatic oscillations during their negative SAM/El Niño or positive SAM/La Niña phases. Furthermore, the study demonstrated a substantial impact of climatic disturbances in determining the sea ice variability in the IOS.
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http://dx.doi.org/10.1016/j.envres.2022.113481DOI Listing
May 2022

Predation of Aedes aegypti Eggs By Foraging Ants Solenopsis invicta, Myrmicaria brunnea, Diacamma rugosum, and Monomorium minimum.

J Am Mosq Control Assoc 2022 Jun;38(2):118-122

The diseases transmitted by Aedes mosquitoes, such as dengue, chikungunya, yellow fever, and Zika, are ever-increasing. Rapid and unplanned urbanization adversely impacts various endemic species such as ants and facilitates the breeding of Aedes mosquitoes. We have observed the predatory potential of ants over Aedes eggs in urban breeding habitats, and their impact on Aedes mosquito breeding was determined by a field experiment that mimicked the natural breeding habitats. It was found that 99.4% of eggs were removed from the experimental containers by foraging ants in 4 days. The present study demonstrates the role of ants as a natural regulator, limiting Aedes mosquito breeding.
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http://dx.doi.org/10.2987/22-7060DOI Listing
June 2022

Neuroprotective Effect of N-acetylcysteine Against Monocrotophos-Induced Oxidative Stress in Different Brain Regions of Rats.

Appl Biochem Biotechnol 2022 May 19. Epub 2022 May 19.

Department of Biochemistry, Maharshi Dayanand University, Rohtak, 124001, Haryana, India.

Monocrotophos (MCP) is systemic organophosphate insecticide used against crop pests. It is reported to cause mammalian toxicity through both acute and chronic exposure. In the present study, we have shown the protective role of N-acetylcysteine (NAC) against MCP-induced oxidative stress in frontal cortex, corpus striatum and hippocampus brain regions of rats. Male Albino Wistar rats were divided into control, NAC-treated, MCP and NAC + MCP-treated groups. An oral dose of MCP (0.9 mg/kg b.wt) and NAC (200 mg/kg b.wt) was administered for 28 days. Results showed an increase in lipid peroxidation (LPO) and protein oxidation followed by decreased antioxidant enzymes after 28 days of MCP exposure. Histopathological analysis showed that monocrotophos exposure caused neurodegenerative changes as evident by neurons with dystrophic changes in the form of shrunken hyperchromatic nuclei in all the regions of the rat brain. N-acetylcysteine supplementation to MCP-treated rats showed a reduction in oxidative stress and ameliorated cellular alterations in all of the three regions. The results of the study indicate that N-acetylcysteine offers neuroprotection by improving antioxidant response and decreasing oxidative stress in different regions of the rat brain.
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http://dx.doi.org/10.1007/s12010-022-03967-9DOI Listing
May 2022

Incidence, Predictors, and Outcomes of Acute and Sub-acute Stent Thrombosis after Emergency Percutaneous Coronary Revascularization with Drug-Eluting Stents: A Prospective Observational Study.

Glob Heart 2022 30;17(1):24. Epub 2022 Mar 30.

National Institute of Cardiovascular Diseases (NICVD), Karachi, PK.

Background: Stent thrombosis (ST) remains the most feared complication of percutaneous coronary intervention (PCI). Therefore, this study aimed to determine acute and sub-acute ST incidence, predictors, and outcomes after primary PCI.

Methods: This prospective observational study included patients who had undergone primary PCI at a tertiary care cardiac center. All the patients were followed at 30-days of index hospitalization for the incidence of acute or sub-acute ST. ST was further categorized as definite, probable, or possible per the Academic Research Consortium definition. All the survivors of ST were followed after 6-months for the incidence of major adverse cardiovascular events.

Results: An aggregate of 1756 patients were included with 79% (1388) male patients and mean age was 55.59 ± 11.23 years. The incidence of ST was 4.9% (86) with 1.3% (22) acute and 3.6% (64) sub-acute. ST was categorized as definite in 3.3% (58) and probable in 1.6% (28). Independent predictor of ST were observed to be male gender (odds ratio (OR); 2.51 [1.21-5.2]), left ventricular end-diastolic pressure ≥20 mmHg (OR; 2.55 [1.31-4.98]), and pre-procedure thrombolysis in myocardial infarction (TIMI) flow 0 (OR; 3.27 [1.61-6.65]). Cumulative all-cause mortality among patients with ST after 164.1 ± 76.2 days was 46.5% (40/86).

Conclusion: We observed a substantial number of patients vulnerable to the acute or sub-acute ST after primary PCI. Male gender, LVEDP, pre-procedure TIMI flow grade can be used to identify and efficiently manage highly vulnerable patients.
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http://dx.doi.org/10.5334/gh.1112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8973861PMC
March 2022

Refinements and considerations for trio whole-genome sequence analysis when investigating Mendelian diseases presenting in early childhood.

HGG Adv 2022 Jul 25;3(3):100113. Epub 2022 Apr 25.

School of Clinical Medicine, University of Cambridge, Cambridge CB2 1TN, UK.

To facilitate early deployment of whole-genome sequencing (WGS) for severely ill children, a standardized pipeline for WGS analysis with timely turnaround and primary care pediatric uptake is needed. We developed a bioinformatics pipeline for comprehensive gene-agnostic trio WGS analysis of children suspected of having an undiagnosed monogenic disease that included detection and interpretation of primary genetic mechanisms of disease, including SNVs/indels, CNVs/SVs, uniparental disomy (UPD), imprinted genes, short tandem repeat expansions, mobile element insertions, copy number calling, and mitochondrial genome variants. We assessed primary care practitioner experience and competence in a large cohort of 521 families (comprising 90% WGS trios). Children were identified by primary practitioners for recruitment, and we used the UK index of multiple deprivation to confirm lack of patient socio-economic status ascertainment bias. Of the 521 children sequenced, 176 (34%) received molecular diagnoses, with rates as high as 45% for neurology clinics. Twenty-three of the diagnosed cases (13%) required bespoke methods beyond routine SNV/CNV analysis. In our multidisciplinary clinician user experience assessment, both pediatricians and clinical geneticists expressed strong support for rapid WGS early in the care pathway, but requested further training in determining patient selection, consenting, and variant interpretation. Rapid trio WGS provides an efficacious single-pass screening test for children when deployed by primary practitioners in clinical settings that carry high risk for rare pediatric disease presentations.
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http://dx.doi.org/10.1016/j.xhgg.2022.100113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9108978PMC
July 2022
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