Publications by authors named "S Govindarajan"

392 Publications

Differentiation of COVID-19 conditions in planar chest radiographs using optimized convolutional neural networks.

Appl Intell (Dordr) 2020 Nov 6:1-12. Epub 2020 Nov 6.

Non-Invasive Imaging and Diagnostics Laboratory, Biomedical Engineering Group, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai, India.

In this study, an attempt has been made to differentiate Novel Coronavirus-2019 (COVID-19) conditions from healthy subjects in Chest radiographs using a simplified end-to-end Convolutional Neural Network (CNN) model and occlusion sensitivity maps. Early detection and faster automated screening of the COVID-19 patients is essential. For this, the images are considered from publicly available datasets. Significant biomarkers representing critical image features are extracted from CNN by experimentally investigating on cross-validation methods and hyperparameter settings. The performance of the network is evaluated using standard metrics. Perturbation based occlusion sensitivity maps are employed on the features obtained from the classification model to visualise the localization of abnormal areas. Results demonstrate that the simplified CNN model with optimised parameters is able to extract significant features with a sensitivity of 97.35% and F-measure of 96.71% to detect COVID-19 images. The algorithm achieves an Area Under the Curve-Receiver Operating Characteristic score of 99.4% with Matthews correlation coefficient of 0.93. High value of Diagnostic odds ratio is also obtained. Occlusion sensitivity maps provide precise localization of abnormal regions by identifying COVID-19 conditions. As early detection through chest radiographic images are useful for automated screening of the disease, this method appears to be clinically relevant in providing a visual diagnostic solution using a simplified and efficient model.
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November 2020

Prevalence and factors associated with diabetes mellitus among tuberculosis patients in South India-a cross-sectional analytical study.

BMJ Open 2021 10 22;11(10):e050542. Epub 2021 Oct 22.

Department of Preventive and Social Medicine, Jawaharlal Institute of Post Graduate Medical Education and Research, Puducherry, Puducherry, India.

Objective: To determine the prevalence and determinants of diabetes mellitus (DM) among tuberculosis (TB) patients and to assess the additional yield and number needed to screen (NNS) to obtain a newly diagnosed DM among TB patients.

Design: We undertook a cross-sectional analysis of the cohort data under Regional Prospective Observational Research for Tuberculosis-India consortium. Newly diagnosed TB patients recruited into the cohort between 2014 and 2018 were included. Pretested standardised questionnaires and tools were used for data collection. Prevalence of DM among TB patients was summarised as proportion with 95% CI. Type II DM was diagnosed if random blood sugar level was >200 mg/dL or if the participant had a documented history of DM. NNS by blood glucose testing to diagnose one new DM case among TB patients was also calculated.

Setting: Three districts of South India: Puducherry, Cuddalore and Villupuram SUBJECTS: Newly diagnosed sputum smear positive pulmonary TB patients aged ≥16 years RESULTS: In total, 1188 TB patients were included. Prevalence of DM among TB patients was 39% (95% CI: 36.2% to 41.8%). In unadjusted analysis, elderly TB, marital status, caste, gender, higher education level, household income and obesity had a significant association with DM. However, in adjusted analysis, only marital status (currently married aPR; 3.77 (95 CI: 2.20 to 6.49), widowed/separated/divorced aPR; 3.66 (95 CI: 1.96 to 6.83)) and body mass index category (normal weight aPR; 3.26 (95 CI: 2.55 to 4.16), overweight aPR; 3.86 (95 CI: 2.69 to 5.52), obesity aPR; 4.08 (95 CI: 2.81 to 5.94)) were found to be significant determinants. The number of TB patients needed to be screened to find a new DM case was 12.

Conclusion: We found that one in three TB patients had coexisting DM. The number of TB patients needed to be screened to obtain a newly diagnosed DM patients was also determined. The study supports and highlights the need of RNTCP's effort in bidirectional screening of TB and DM.
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October 2021

Aloe vera carbohydrates regulate glucose metabolism through improved glycogen synthesis and downregulation of hepatic gluconeogenesis in diabetic rats.

J Ethnopharmacol 2021 Dec 23;281:114556. Epub 2021 Aug 23.

Vellore Institute of Technology, Vellore, Tamil Nadu, India. Electronic address:

Ethnopharmacological Relevance: Aloe vera (L.) Burm.f. is an ancient medicinal plant that belongs to the family Asphodelaceae. It has a rich source of bioactive constituents such as carbohydrates, polyphenols, peptides, sterols and tannins, etc. Aloe vera has multiple biological activities such as anti-inflammatory, antioxidant and antidiabetic activity etc. AIM OF THE STUDY: The present study investigated the antidiabetic mechanism of Aloe vera carbohydrate fraction (AVCF) and aimed to provide insights into the regulation of carbohydrate metabolism enzymes in glucose homeostasis.

Materials And Methods: The antidiabetic effect of AVCF was evaluated using α-amylase, α-glucosidase inhibition, glucose diffusion and glucose uptake assay. The in vitro AVCF effect on insulin secretion, cell proliferation and inflammatory markers were determined using streptozotocin-induced oxidative stress on RIN-m5F cells. Streptozotocin-induced male Wistar diabetic rats were treated for 21 days with AVCF (54 mg/kg bw). The in vivo AVCF effect was measured on fasting plasma glucose, insulin, glucagon, hexokinase, glycogen synthase and glucose-6-phosphatase, levels in diabetic rats. Histopathological studies for organ-specific effects in the pancreas, liver and small intestine were also conducted.

Results: AVCF-treated RIN-m5F cells significantly increased BrdU levels, with insulin secretion, and decreased TNF-α, IL-6 and nitric oxide levels. AVCF treated streptozotocin-induced diabetic rats showed significantly decreased fasting plasma glucose, glucagon and glucose-6-phosphatase levels with a concomitant increase in insulin, hexokinase, and glycogen synthase levels and, glycogen content. These findings corroborate with the improved hepatic glycogen content in the PAS stained histological section of the liver of AVCF treated diabetic rats.

Conclusion: These results suggest that CF of Aloe vera improved glucose metabolism by activation of glycogenesis and down-regulation of gluconeogenesis thereby, maintaining glucose homeostasis. Hence, AVCF can be used as an alternative medicine in the alleviation of diabetes mellitus symptoms.
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December 2021

Numerical modelling of nitrate transport in fractured porous media under non-isothermal conditions.

Environ Sci Pollut Res Int 2021 Aug 7. Epub 2021 Aug 7.

Petroleum Engineering Program, Department of Ocean Engineering, Indian Institute of Technology-Madras, Chennai, Tamil Nadu, 600036, India.

Subsurface contamination is a frequent occurrence in fractured porous systems, posing a potential threat for the groundwater contamination. Tracking the movement of these contaminants is an inherent aspect of effective remediation strategy. The non-isothermal conditions prevailing in the subsurface environment further add to the complexity of the existing scenario. The current study focuses on simulating the concentration profiles of nitrogen species in a fracture-matrix system under non-isothermal conditions. The kinetics and biochemical thermodynamics of nitrogen transformation reactions were explicitly modelled in this study by adopting a finite differential numerical scheme. The numerical results clearly depicted the spatial-temporal profiles of the concentration of all the species in response to the observed peak values. Considering the sensitivity of the model parameters, an increase in flow velocity triggered the migration of all nitrogen species in the fracture, while an increase in matrix porosity reduced the concentration by enhancing the chemical reactions. An increase in fracture aperture also could trigger the denitrification process in the fracture to reduce the nitrate-nitrogen contamination in the fracture. The temperature variation between 25 °C and 45 °C in the fracture and the matrix essentially reduced the availability of nitrate-nitrogen and nitrogen gas in the fracture under non-isothermal conditions. Hence, an increase in the temperature coefficient can reduce the spike of nitrate-nitrogen and nitrogen gas in fracture by minimizing such transformation rates.
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August 2021

Aloe vera and its two bioactive constituents in alleviation of diabetes -proteomic & mechanistic insights.

J Ethnopharmacol 2021 Nov 22;280:114445. Epub 2021 Jul 22.

Centre for Bio Separation Technology (CBST), Vellore Institute of Technology (VIT), Vellore-632 014, Tamil Nadu, India. Electronic address:

Ethnopharmacological Relevance: Aloe barbadensis Miller, commonly known as Aloe vera has been used since time immemorial for treatment of various diseases such as cancer, inflammatory disorders, diabetes, wound healing etc. AIM: Diabetes mellitus is a complex disorder and understanding the molecular mechanisms involved is a key to identify different markers for early diagnosis of the disease. The proteomic approach offers a plethora of opportunities to identify markers and targets involved in pathogenesis of diabetes. The present study was undertaken to understand the mechanism of action of Aloe vera and its two constituents (Carbohydrates and Polypeptides) in the alleviation of diabetes in streptozotocin-induced diabetic rats through a proteomics approach.

Methods: Different groups of rats were fed with Aloe vera extract, carbohydrate fraction and peptide/polypeptide fraction for three weeks. The diabetic rats fed with Aloe vera and its two fractions restored the glucose and insulin levels to normal. The plasma of the rats was depleted with IgG and albumin and proteomic analysis was carried out. Apolipoproteins (dyslipidemia), complement factors (inflammatory pathways), zonulin (intestinal permeability), anti-oxidant related proteins were selected in this study as these are involved in the progression of diabetes.

Results: It was observed that Aloe vera extract is involved in the alleviation of diabetes through these pathways while the carbohydrate fraction alleviates diabetes through an anti-oxidant mechanism and glucose uptake while the polypeptide fraction alleviates diabetes through the restoration of intestinal permeability by reduced zonulin levels.

Conclusion: The constituents of Aloe vera works different pathways involved in diabetes and the synergistic effect of these constituents make Aloe vera extract a prospective candidate, which can alleviate diabetes through regulation of the pathways involved in the progression of diabetes.
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November 2021