Publications by authors named "Ashok Kumar Yadav"

57 Publications

The Indian Chronic Kidney Disease (ICKD) study: baseline characteristics.

Clin Kidney J 2022 Jan 13;15(1):60-69. Epub 2021 Aug 13.

George Institute for Global Health India, New Delhi, India.

Background: Chronic kidney disease (CKD) is an important cause of morbidity and mortality worldwide. There is a lack of information on epidemiology and progression of CKD in low-middle income countries. The Indian Chronic Kidney Disease (ICKD) study aims to identify factors that associate with CKD progression, and development of kidney failure and cardiovascular disease (CVD) in Indian patients with CKD.

Methods: ICKD study is prospective, multicentric cohort study enrolling patients with estimated glomerular filtration rate (eGFR) 15-60 mL/min/1.73 m, or >60 mL/min/1.73 m with proteinuria. Clinical details and biological samples are collected at annual visits. We analysed the baseline characteristics including socio-demographic details, risk factors, disease characteristics and laboratory measurements. In addition, we compared characteristics between urban and rural participants.

Results: A total of 4056 patients have been enrolled up to 31 March 2020. The mean ± SD age was 50.3 ± 11.8 years, 67.2% were males, two-thirds of patients lived in rural areas and the median eGFR was 40 mL/min/1.73 m. About 87% were hypertensive, 37% had diabetes, 22% had CVD, 6.7% had past history of acute kidney injury and 23% reported prior use of alternative drugs. Diabetic kidney disease, chronic interstitial nephritis (CIN) and CKD-cause unknown (CKDu) were the leading causes. Rural participants had more occupational exposure and tobacco use but lower educational status and income. CIN and unknown categories were leading causes in rural participants.

Conclusions: The ICKD study is the only large cohort study of patients with mild-to-moderate CKD in a lower middle income country. Baseline characteristics of study population reveal differences as compared with other cohorts from high-income countries.
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http://dx.doi.org/10.1093/ckj/sfab149DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8757418PMC
January 2022

Structural modification aimed for improving solubility of lead compounds in early phase drug discovery.

Bioorg Med Chem 2022 Jan 10;56:116614. Epub 2022 Jan 10.

Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (B.H.U.), Varanasi 221 005, U.P., India. Electronic address:

Many lead compounds fail to reach clinical trials despite being potent because of low bioavailability attributed to their insufficient solubility making solubility a primary and crucial factor in early phase drug discovery. Solubility improvement of poorly soluble lead compounds without losing potency is a challenging task for the medicinal chemist in a drug discovery setup. Solubility is an important factor not only to dissipate or liquefy a substance but also to attain an optimal concentration of drug in systemic circulation required for the desired therapeutic effect. It has been estimated that more than forty percent of newly developed molecules are practically insoluble in water. Molecules with poor solubility not only cause difficulty for in vitro and in vivo assays but also add significant burdens to drug development in the form of longer time taken and increased cost to optimize the solubility. To tackle this problem, different techniques are being used such as physical, chemical, and miscellaneous methods to enhance solubility. Among them, the medicinal chemistry approach focussed on structural modification is a versatile and unique approach in way that it can also improve other pharmacokinetic/physicochemical parameters simultaneously. In this review, we have begun with brief introduction of solubility and its role followed by recent successful examples of different structural modification tactics reported in the literature including synthesis of prodrugs, hydrophilic and ionizable group insertion, addition & removal of hydrogen bonding, bioisosterism, disruption of molecular symmetry and planarity. Moreover, we have included a section on the obstacles in the solubility optimization and also summarised different in silico tools with potential application in solubility prediction. Overall, this review encompasses various successfully used solubility optimization examples using structure modification.
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http://dx.doi.org/10.1016/j.bmc.2022.116614DOI Listing
January 2022

Insight of oral vaccines as an alternative approach to health and disease management: An innovative intuition and challenges.

Biotechnol Bioeng 2022 Feb 18;119(2):327-346. Epub 2021 Nov 18.

Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India.

Vaccination is the most suitable and persuasive healthcare program for the prohibition of various deadly diseases. However, the higher production cost and purification strategies are out of reach for the developing nations. In this scenario, development of edible vaccine turns out to be the most promising alternative for remodeling the pharmaceutical industry with reduced production and purification costs. Generally, oral route of vaccination is mostly preferred due to its safety, compliance, low manufacturing cost and most importantly the ability to induce immunity in both systemic and mucosal sites. Genetically modified microorganisms and plants could efficiently be used as vehicles for edible vaccines. Edible vaccines are supposed to reduce the risk associated with traditional vaccines. Currently, oral vaccines are available in the market for several viral and bacterial diseases like cholera, hepatitis B, malaria, rabies etc. Herein, the review focuses on the breakthrough events in the area of edible vaccines associated with dietary microbes and plants for better control over diseases.
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http://dx.doi.org/10.1002/bit.27987DOI Listing
February 2022

Gut-microbiota derived bioactive metabolites and their functions in host physiology.

Biotechnol Genet Eng Rev 2021 Oct 22;37(2):105-153. Epub 2021 Oct 22.

Centre for Molecular Biology, Central University of Jammu, Samba, Jammu & Kashmir, India.

Every individual harbours a complex, diverse and mutualistic microbial flora in their intestine and over the time it became an integral part of the body, affecting a plethora of activities of the host. Interaction between host and gut-microbiota affects several aspects of host physiology. Gut-microbiota affects host metabolism by fermenting unabsorbed/undigested carbohydrates in the large intestine. Not only the metabolic functions, any disturbances in the composition of the gut-microbiota during first 2-3 years of life may impact on the brain development and later affects cognition and behaviour. Thus, gut-dysbiosis causes certain serious pathological conditions in the host including metabolic disorders, inflammatory bowel disease and mood alterations, etc. Microbial-metabolites in recent times have emerged as key mediators and are responsible for microbiota induced beneficial effects on host. This review provides an overview of the mechanism of microbial-metabolite production, their respective physiological functions and the impact of gut-microbiome in health and diseases. Metabolites from dietary fibres, aromatic amino acids such as tryptophan, primary bile acids and others are the potential substances and link microbiota to host physiology. Many of these metabolites act as signalling molecules to a number of cells types and also help in the secretion of hormones. Moreover, interaction of microbiota derived metabolites with their host, immunity boosting mechanisms, protection against pathogens and modulation of metabolism is also highlighted here. Understanding all these functional attributes of metabolites produced from gut-microbiota may lead to the opening of a new avenue for preventing and developing potent therapies against several diseases.
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http://dx.doi.org/10.1080/02648725.2021.1989847DOI Listing
October 2021

Evolution of transition metal charge states in correlation with the structural and magnetic properties in disordered double perovskites CaLaFeRuO (0.5 ≤ ≤ 2).

Phys Chem Chem Phys 2021 Oct 6;23(38):21769-21783. Epub 2021 Oct 6.

Department of Chemistry, National Institute of Technology Kurukshetra, Kurukshetra-136119, India.

A series of disordered CaLaFeRuO, CaLaFeRuO and LaFeRuO double perovskites were prepared by the solid-state reaction method and investigated by neutron powder diffraction, X-ray absorption near-edge structure (XANES) analysis at the Ru-K edge, Mössbauer spectroscopy, DC magnetization and resistivity measurements. All compounds crystallize in the orthorhombic crystal structure with the space group down to 3 K, showing a random distribution of Fe and Ru at the B site. Thermogravimetric analysis indicates oxygen deficiency in the Ca-rich and formal oxygen hyperstoichiometry in the La-rich members of the present series. While Mössbauer spectra verify the Fe state for all compositions, the XANES study reveals a variable Ru oxidation state which decreases with increasing La content. The end member actually is a Ru/Ru compound with possibly some cation vacancies. From magnetic susceptibility and neutron diffraction measurements, the presence of a G-type antiferromagnetic ordering was observed with a drastic increase in transition temperature from 275 K (CaLaFeRuO) to 570 K (LaFeRuO). Mössbauer spectroscopy confirms the presence of long-range ordering but, due to local variations in the exchange interactions, the magnetic states are microscopically inhomogeneous. All the samples are variable range hopping semiconductors. A complex interplay between structural features, charge states, anion or cation defects, and atomic disorder determines the magnetic properties of the present disordered 3d/4d double perovskite series.
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http://dx.doi.org/10.1039/d1cp02318gDOI Listing
October 2021

Prescription Practices in Patients With Mild to Moderate CKD in India.

Kidney Int Rep 2021 Sep 26;6(9):2455-2462. Epub 2021 Jun 26.

George Institute for Global Health India, New Delhi, India.

Introduction: Patients with chronic kidney disease (CKD) require multiple medications. There is no information on prescription patterns or the use of evidence-based therapies for management of CKD from low-middle-income countries. Using baseline data from the Indian CKD (ICKD) cohort, we describe the drug prescription practices in patients with mild to moderate CKD.

Methods: The ICKD study is a prospective, observational cohort study of mild to moderate kidney disease across 11 centers in India. We analyzed all the prescriptions captured at enrollment in the ICKD study. Drugs were categorized into 11 different groups. We provide descriptive data on prescription details and evaluate the appropriateness of medication use.

Results: Complete prescription data were available in 3966 out of 4056 (97.8%) subjects enrolled in the ICKD database. Most patients had stage 3 CKD, 24.9% had diabetic kidney disease, 87% had hypertension, and 25.5% had moderate to severe proteinuria. Renin-angiotensin-aldosterone system blockers were prescribed in less than half (47.9%) and in 58.8% of patients with proteinuric CKD. Metformin was prescribed in 25.7% of diabetic subjects with CKD. Only 40.4% of patients were taking statins; 31.1% and 2.8% subjects with anemia were receiving iron and erythropoiesis-stimulating agents, respectively.

Conclusion: This study highlights the missed opportunities for improving outcomes through appropriate prescriptions of drugs in patients with CKD. There is need for dissemination of evidence-based guidelines and institution of sustainable implementation practices for improving the overall health of patients with CKD.
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http://dx.doi.org/10.1016/j.ekir.2021.06.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8418981PMC
September 2021

Local Structure Investigations of Sequential Sorption of U and Fe on Polyacrylamide Hydroxamic Acid Resins.

Inorg Chem 2021 Jul 1;60(14):10158-10166. Epub 2021 Jul 1.

Desalination and Membrane Technology Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400 085, India.

Uranium- and iron-containing waste simulated effluent has been treated sequentially with a novel resin, viz., polyacrylamide hydroxamic acid (PAAHA). The motivation is to investigate the competitive interactions with transition metals during the removal of radiologically and chemically toxic uranium. The sequential sorption results indicate that the resin is more Fe selective compared to U and it retains more iron. X-ray absorption fine structure measurements, which comprise of both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques, have been carried out on the PAAHA resin at the Fe K-edge and U L-edge to probe the change in the local coordination environment on sequential sorption of uranium and iron. EXAFS measurements conclude that the U-O distances and coordination are modified when the treatment sequences of U and Fe are interchanged, whereas the Fe local structure remains intact. The results obtained from EXAFS measurements have been verified by detail analysis of XANES data.
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http://dx.doi.org/10.1021/acs.inorgchem.1c00297DOI Listing
July 2021

Two-Dimensional Tungsten Oxide/Selenium Nanocomposite Fabricated for Flexible Supercapacitors with Higher Operational Voltage and Their Charge Storage Mechanism.

ACS Appl Mater Interfaces 2021 Feb 16;13(7):8102-8119. Epub 2021 Feb 16.

Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016, India.

The present work elaborates the high-energy-density, stable, and flexible supercapacitor devices (full-cell configuration with asymmetric setup) based on a two-dimensional tungsten oxide/selenium (2D WO/Se) nanocomposite. For this, the 2D WO/Se nanocomposite synthesized by a hydrothermal method followed by air annealing was coated on a flexible carbon cloth current collector and combined separately with both 0.1 M HSO and 1-butyl-3-methyl imidazolium tetrafluoroborate room temperature ionic liquid (BmimBF RTIL) as electrolyte. Different physicochemical characterization techniques, viz., transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, are utilized for phase confirmation and morphology identification of the obtained samples. The electrochemical analysis was used to evaluate charge storage mechanism. The half-cell configuration (three electrode system) in 0.1 M HSO shows a specific capacitance of 564 F g at 6 A g current density, whereas with ionic liquid as electrolyte, a higher specific capacitance of 1650 F g was obtained at a higher current of 40 mA and working potential of 4 V. Importantly, the asymmetric flexible supercapacitor device with PVA-HSO electrolyte shows a working voltage of 1.7 V. A specific capacitance of 858 mF g is obtained for the asymmetric electrode system with an energy density of 47 mWh kg and a power density of 345 mW kg at a current density of 0.2 A g.
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http://dx.doi.org/10.1021/acsami.0c15818DOI Listing
February 2021

Synthesis and studies of thiazolidinedione-isatin hybrids as α-glucosidase inhibitors for management of diabetes.

Future Med Chem 2021 03 28;13(5):457-485. Epub 2021 Jan 28.

University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh 160014, India.

Keeping in view the side effects associated with clinically used α-glucosidase inhibitors, novel thiazolidinedione-isatin hybrids were synthesized and evaluated by , and procedures. Biological evaluation, cytotoxicity assessment, molecular docking, binding free energy calculations and molecular dynamics studies were performed for hybrids. The most potent inhibitor (IC = 24.73 ± 0.93 μM) was competitive in manner and observed as non-cytotoxic. possessed higher efficacy than the standard drug (acarbose) during biological testing.  The enzyme inhibitory potential and safety profile of synthetic molecules was recognized after , , and cytotoxicity studies. Further structural optimization of can offer potential hit molecules suitable for future investigations.
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http://dx.doi.org/10.4155/fmc-2020-0022DOI Listing
March 2021

Stabilization of uranyl(v) by dipicolinic acid in aqueous medium.

Dalton Trans 2021 Feb 13;50(4):1486-1495. Epub 2021 Jan 13.

The Environmental research group, R&D, Tata Steel, Jamshedpur, Jharkhand 831001, India.

Preparation of a stable U(v) complex in an aqueous medium is a challenging task owing to its disproportionation nature (conversion into more stable U(vi) and U(iv) species) and sensitivity to atmospheric oxygen. The stable uranyl (UO)/dipicolinic acid (DPA) complex ([UO(DPA)(OH)(HO)]) was formed at pH 10.5-12.0, which was confirmed by potentiometric and spectrophotometric titrations, and NMR, ESI-MS and EXAFS spectroscopy. The complex [UO(DPA)(OH)(HO)] can be electrochemically reduced on the Pt electrode at -0.9 eV (vs. Ag/AgCl) to [UO(DPA)(OH)(HO)] in aqueous medium under an anaerobic environment. According to cyclic voltammetric analysis, a pair of oxidation and reduction waves at E' = -0.592 V corresponds to the [UO(DPA)(OH)(HO)]/[UO(DPA)(OH)(HO)] redox couple and the formation of [UO(DPA)(OH)(HO)] was confirmed by the electron stoichiometry (n = 0.97 ± 0.05) of the reduction reaction of [UO(DPA)(OH)(HO)]. The pentavalent uranyl complex [UO(DPA)(OH)(HO)] was further characterized via UV-vis-NIR absorption spectrophotometry and X-ray absorption (XANES and EXAFS) spectroscopy. The [UO(DPA)(OH)(HO)] complex is stable at pH 10.5-12.0 in anaerobic water for a few days. DFT calculation shows the strong complexing ability of DPA stabilizing the unstable oxidation state U(v) in aqueous medium.
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http://dx.doi.org/10.1039/d0dt03961fDOI Listing
February 2021

Proteinuria in Severe Hypothyroidism: A Prospective Study.

J Clin Endocrinol Metab 2021 01;106(2):e749-e756

Department of Nephrology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

Context: Hypothyroidism is associated with reversible decline in kidney function as measured by estimated glomerular filtration rate (eGFR). eGFR and proteinuria are the most important markers for clinical assessment of kidney function. Though hypothyroidism is associated with proteinuria in cross-sectional data, the impact of treatment on proteinuria is unknown.

Objective: This study explores the effect of thyroid hormone replacement therapy on eGFR and 24-hour urine protein excretion in patients with severe primary hypothyroidism.

Design And Participants: This study was a prospective, observational cohort study in adults with severe primary hypothyroidism (serum thyrotropin [TSH] > 50 µIU/mL). Individuals with preexisting or past kidney disease, kidney or urinary tract abnormalities, calculi or surgery, diabetes mellitus, or hypertension were excluded. The participants received thyroid hormone replacement therapy. Thyroid functions, eGFR, 24-hour urine protein excretion, and biochemical parameters were measured at baseline and 3 months.

Setting: This study took place at a single center, a tertiary care referral and teaching hospital.

Results: Of 44 enrolled participants, 43 completed 3 months of follow-up. At 3 months, serum TSH levels decreased and thyroxine levels increased (P < .001 for both). Significant increases in eGFR (mean difference, 18.25 ± 19.49 mL/min/1.73 m2; 95% CI, 12.25 to 24.25, P < .001) and declines in 24-hour urine protein excretion (mean difference, -68.39 ± 125.89 mg/day; 95% CI, -107.14 to -29.65, P = .001) were observed. Serum cholesterol and low-density lipoprotein levels also significantly decreased (P < .001).

Conclusions: Thyroid hormone replacement therapy in patients with severe primary hypothyroidism improves eGFR and decreases 24-hour urine protein excretion, thereby suggesting reversible alterations.
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http://dx.doi.org/10.1210/clinem/dgaa871DOI Listing
January 2021

Unravelling oxygen driven α to β phase transformation in tungsten.

Sci Rep 2020 Sep 7;10(1):14718. Epub 2020 Sep 7.

Department of Physics, School of Natural Sciences, Shiv Nadar University, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh, 201 314, India.

Thin films of β-W are the most interesting for manipulating magnetic moments using spin-orbit torques, and a clear understanding of α to β phase transition in W by doping impurity, especially oxygen, is needed. Here we present a combined experimental and theoretical study using grazing incidence X-ray diffraction, photoelectron spectroscopy, electron microscopy, and ab initio calculations to explore atomic structure, bonding, and oxygen content for understanding the formation of β-W. It is found that the W films on SiO/Si have 13-22 at.% oxygen in A15 β structure. Ab initio calculations show higher solution energy of oxygen in β-W, and a tendency to transform locally from α to β phase with increasing oxygen concentration. X-ray absorption spectroscopy also revealed local geometry of oxygen in β-W, in agreement with the simulated one. These results offer an opportunity for a fundamental understanding of the structural transition in α-W and further development of β-W phase for device applications.
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http://dx.doi.org/10.1038/s41598-020-71650-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477580PMC
September 2020

Self-Organized Single-Atom Tungsten Supported on the N-Doped Carbon Matrix for Durable Oxygen Reduction.

ACS Appl Mater Interfaces 2020 Sep 15;12(39):43586-43595. Epub 2020 Sep 15.

Material Research Centre, Indian Institute of Science, Bangalore 560012, India.

Rational engineering of atomically scaled metal-nitrogen-carbon (M-N-C) moieties has been the topic of recent research interest because of their potential application as an electrochemical oxygen reduction reaction (ORR) catalyst. Despite numerous efforts on M-N-Cs, attaining both adequate activity and a satisfactory stability simultaneously is a principal issue. Herein, we demonstrated the synthesis of a single-atom tungsten catalyst supported on the N-doped carbon matrix (W-N-C) and its application as an ORR catalyst. W-N-C was synthesized using the economically viable, simple, one-step pyrolysis of dicyandiamide and tungsten(VI) chloride at moderate temperature (700 °C). The synthesis of W-N-C avoids any post acid treatment as it does not require any subsidiary sacrificial metal like Zn and, hence, does not induce any burden associated with chemical waste management. The atomic dispersion of W atoms stabilized by N-doped porous carbon and the formation of WNC were confirmed by high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy. Interestingly, as-synthesized WNC exhibited unprecedented electrocatalytic activity with a half-wave potential of 764 mV vs reversible hydrogen electrode (RHE) as well as significantly enhanced stability (retaining >99% diffusion-limited current density and the loss in activity is 10.5% at 0.84 V after 10,000 potential cycles), which is much better than the stability limit set by the US Department of Energy in an alkaline medium. Overall, the activity of W-N-C surpasses that of Pt/C after 5000 cycles. The excellent stability is believed to be due to the symmetric coordination of the metal active site (WNC).
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http://dx.doi.org/10.1021/acsami.0c10234DOI Listing
September 2020

Patient Satisfaction with Nursing Care in Five Major Departments in a Tertiary Care Centre.

JNMA J Nepal Med Assoc 2019 Sep-Oct;57(219):367-370

Patan Academy of Health Sciences, Lagankhel, Lalitpur, Nepal.

Introduction: Patient satisfaction is an important component of quality nursing care and is often determined by the nursing care in any health institution. The aim of the study is to find the presence of satisfaction among in-ward patients of five major wards at a tertiary care hospital regarding the quality of care provided by nursing staff.

Methods: A descriptive cross-sectional study was conducted among 105 patients of Patan Hospital from 3rd July to 3rd August, 2015 after obtaining ethical clearance from Institutional Review Committee. Sample size was calculated and stratified random sampling was done. Data was collected in Microsoft Excel and analyzed in Sta 13.0. Point estimate at 95% Confidence Interval was calculated and frequency and percentage was calculated for binary data. Subgroup analysis was done on the basis of demographic variables.

Results: Among 105 patients, 99 (94.3%) [94.93-95.07 at 95%CI] were satisfied with the nursing care provided at a tertiary care center in Nepal. Among them, 60 (60.6%) were females and 39 (39.4%) were males. Age of the patients ranged from 1 year to 85 years. The length of the stay in the hospital ranged from 2 to 17 days (mean = 5.6 days).

Conclusions: Most of the patients were satisfied with the nursing care provided in a tertiary care centre. Routine nursing care surveys and immediate feedbacks would keep the authorities updated and deliver good health care.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7580428PMC
August 2020

Investigation of New -Site-Disordered Perovskite Oxide CaLaScRuO: An Efficient Oxygen Bifunctional Electrocatalyst in a Highly Alkaline Medium.

ACS Appl Mater Interfaces 2020 Feb 11;12(8):9190-9200. Epub 2020 Feb 11.

Department of Chemistry , National Institute of Technology Kurukshetra , Kurukshetra 136119 , India.

Energy storage and conversion driven by electro- or photocatalyst is a highly exciting field of research, and generations of effective and durable oxide catalysts have received much attention in this field. Here, we report -site lanthanum-doped oxygen-rich quinary oxide CaLaScRuO synthesized by adopting the solid-state reaction method and characterized by various techniques such as powder X-ray diffraction, neutron diffraction, energy-dispersive X-ray spectroscopy, inductively coupled plasma-atomic emission spectrometry, Raman spectroscopy, and temperature-programmed reduction in the presence of a hydrogen atmosphere (H-TPR). X-ray absorption study confirms the existence of mixed valent Ru ions in the structure, which enhances the oxygen stoichiometry for the partial balance of an extra cationic charge. Neutron powder diffraction and reduction of the material in a hydrogen atmosphere (H-TPR) can confirm the oxygen overstoichiometry of the catalyst. The present material works as an efficient and robust oxygen bifunctional electrocatalyst for ORR/OER (oxygen evolution reaction/oxygen reduction reaction) followed by four-electron transfer pathway in a strong (1 M KOH) alkaline medium. The catalytic nature of the designed structural and chemical flexible perovskite is a novel example of an electrocatalyst for the oxygen bifunctional activity.
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http://dx.doi.org/10.1021/acsami.9b20199DOI Listing
February 2020

Reversal of endothelial dysfunction post-immunosuppressive therapy in adult-onset podocytopathy and primary membranous nephropathy.

Atherosclerosis 2020 02 23;295:38-44. Epub 2019 Aug 23.

Department of Nephrology, Post Graduate Institute of Medical Education and Research, Chandigarh, India. Electronic address:

Background And Aims: The effect of nephrotic syndrome (NS) and its treatment on endothelial dysfunction is not evident. This study assessed endothelial dysfunction in adult-onset NS and its impact of immunosuppressive therapy.

Methods: Newly diagnosed patients with adult-onset NS (podocytopathy and primary membranous nephropathy (PMN)) and normal renal function were enrolled. Flow mediated vasodilatation (FMD) assessed endothelial function and CD4CD28null T cells, E-selectin and pulse wave velocities (PWV) were measured at baseline and after treatment to characterize this further. Monitoring included monthly proteinuria, serum albumin, creatinine and lipid profile at baseline and post-treatment. The healthy control (HC) included 25 voluntary kidney donors who were assessed for markers of endothelial dysfunction.

Results: Fifty participants with new-onset NS were studied. Amongst the NS group, 26 (52%) patients had PMN, while the remaining 24 (48%) had podocytopathy. Twenty-one (88%) patients in the podocytopathy and 18 (69%) patients in the PMN cohort were in either complete or partial remission at the end of 8 months. FMD at baseline in NS patients was significantly lower as compared to HC (p = 0.002) while PWV (p = 0.007), E-selectin (p < 0.001) and CD4CD28null T cells (p = 0.003) were significantly higher as compared with HC. Following treatment with immunosuppressive medication, FMD increased from 3 to 8% (p < 0.001). PWV also improved from a baseline of 7.70 to 6.65 m/s (p = 0.001). At the end of 8 months, E-selectin decreased significantly from 127 to 82 ng/ml (p = 0.002) while the CD4CD28null T cell population reduced from 5.20 to 3.70% (p = 0.032) of total CD4 cells. In the PMN cohort, despite significant reduction, E-selectin and CD4CD28null T cells at follow-up remained higher than in healthy controls.

Conclusion: Immunosuppressive treatment contributes substantially to the improvement of endothelial dysfunction present at baseline in NS patients. Persistent subtle endothelial dysfunction remains in the sub-group of patients with PMN.
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http://dx.doi.org/10.1016/j.atherosclerosis.2019.08.013DOI Listing
February 2020

Assessment of Endothelial Dysfunction in Acute and Convalescent Phases of Kawasaki Disease Using Automated Edge Detection Software: A Preliminary Study From North India.

J Clin Rheumatol 2021 Jun;27(4):143-149

From the Allergy Immunology Unit, Advanced Pediatrics Centre.

Objective: The aim of this study was to assess endothelial dysfunction in acute and convalescent phases of Kawasaki disease (KD) using automated edge detection software.

Methods: This was a case-control study to assess the flow-mediated dilatation (FMD) of brachial artery (BA) in patients with KD during acute phase and at least 3 months after diagnosis. A 10-MHz multifrequency linear array probe attached to a high-resolution ultrasound machine (PHILIPS Medical System-IU22) was used to acquire the images. Automated edge detection software was used to assess BA diameter.

Results: A total of 16 children with KD and 16 healthy children were enrolled in the study. Mean ± SD maximum BA diameter was found to be significantly low during the acute stage of KD (2.56 ± 0.36 mm) as compared with the convalescence phase (2.93 mm ± 0.31) and in healthy controls (2.95 mm ± 0.56). The mean ± SD percentage change in the FMD was found to be significantly low in the acute phase of KD (12.32 ± 6.2) as compared with the convalescence phase of KD (17.99 ± 8.13) and healthy controls (26.88 ± 12.76). The mean ± SD percentage change in the FMD was also found to be significantly low in the convalescence phase of KD as compared with healthy controls.

Conclusions: The FMD of the BA is significantly reduced in patients during the acute and convalescence phase of KD as compared with normal healthy children. The endothelial dysfunction was present even in patients who had no obvious coronary artery abnormalities during the acute stage.
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http://dx.doi.org/10.1097/RHU.0000000000001233DOI Listing
June 2021

Expression, purification, characterization and in silico analysis of newly isolated hydrocarbon degrading bleomycin resistance dioxygenase.

Mol Biol Rep 2020 Jan 13;47(1):533-544. Epub 2019 Nov 13.

Department of Biotechnology, Sri Guru Granth Sahib World University, Fatehgarh Sahib, Pb, India.

In the present investigation, we report cloning, expression, purification and characterization of a novel Bleomycin Resistance Dioxygenase (BRPD). His-tagged fusion protein was purified to homogeneity using Ni-NTA affinity chromatography, yielding 1.2 mg of BRPD with specific activity of 6.25 U mg from 600 ml of E. coli culture. Purified enzyme was a dimer with molecular weight ~ 26 kDa in SDS-PAGE and ~ 73 kDa in native PAGE analysis. The protein catalyzed breakdown of hydrocarbon substrates, including catechol and hydroquinone, in the presence of metal ions, as characterized via spectrophotometric analysis of the enzymatic reactions. Bleomycin binding was proven using the EMSA gel retardation assay, and the putative bleomycin binding site was further determined by in silico analysis. Molecular dynamic simulations revealed that BRPD attains octahedral configuration in the presence of Fe ion, forming six co-ordinate complexes to degrade hydroquinone-like molecules. In contrary, in the presence of Zn ion BRPD adopts tetrahedral configuration, which enables degradation of catechol-like molecules.
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http://dx.doi.org/10.1007/s11033-019-05159-xDOI Listing
January 2020

Exploring Burstein-Moss type effects in nickel doped hematite dendrite nanostructures for enhanced photo-electrochemical water splitting.

Phys Chem Chem Phys 2019 Sep;21(36):20463-20477

Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016, India.

The Burstein-Moss (B-M) effect, which suggests that the optical band gap of degenerately doped semiconductors increases when all states close to the conduction band get populated due to shifting of an absorption edge to higher energy, is important, as it gives a chance to obtain different optical properties for the same material. Here, we report our observations of the similar shift in the optical band gap in NixFe2-xO3 nanocomposites as a function of composition with the help of cyclic voltammetry (CV) and XPS valence band (VB) position measurements. The conduction band edge (CBE) position of the NixFe2-xO3 nanocomposites as determined using CV was noted to move towards more negative potential with increasing Ni-concentration. A similar shift is also noted in the CBE estimated using XPS measurements (by subtracting the VB position from the optical band gap values). The observed shift in the optical band gap along with the CBE position gives the corresponding shift in the Fermi level, which is found to move closer to the CBE position, suggesting the observation of an effect similar to the B-M shift. Also, the extent of band bending estimated from the deviation of the CBE from the flat band potential (measured through Mott-Schottky plots) is found to increase with increasing Ni-concentration. Moreover, the Ni-composition has been observed to enhance the current density as well as to facilitate water splitting at a much lower onset potential compared to pure hematite. The NixFe2-xO3 nanocomposite with an 11 mol% Ni-composition shows the highest photo-electrochemical response with an almost ten times enhancement in the current density at 1.9 V vs. RHE in alkaline medium, as compared to the dark current. This enhanced performance is attributed to the improved charge separation and higher charge carrier density as a result of the higher extent of band bending in the NixFe2-xO3 nanocomposites.
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http://dx.doi.org/10.1039/c9cp04132jDOI Listing
September 2019

Vitamin D deficiency, endothelial function and bone biomarkers in post-kidney transplantation patients from North India.

Int Urol Nephrol 2019 Jan 19;51(1):181-186. Epub 2018 Nov 19.

Cardiology Clinical Academic Group, Molecular and Clinical Sciences Research Institute, St Georges University of London, London, UK.

Purpose: CKD patients after kidney transplantation continue to suffer from elevated CV events which may be related to low vitamin D and its adverse impact on vascular function. The prevalence of vitamin D deficiency in North Indian kidney transplantation patients and its impact on vascular and bone biomarkers is unknown which this study investigated.

Methods: Non-diabetic, stable, > 6 months post-kidney transplantation patients, not on vitamin D supplementation, were recruited after informed consent. Data on demographics, anthropometrics and treatment were collected. Blood samples were stored at - 80 °C until analysis for bone and endothelial cell biomarkers using standard ELISA techniques.

Results: The clinical characteristics were: age 37.4 ± 9.9 years, 80% men, 27% ex-smokers, BP 125.5 ± 15.7/78.6 ± 9.7 mmHg, cholesterol 172.0 ± 47.8 mg/dL, hemoglobin 12.6 ± 2.3 g/dL, calcium 9.5 ± 0.6 mg/d and iPTH 58.4 ± 32.9 ng/mL and vitamin D 36.5 ± 39.8 nmol/L. Patients with vitamin D < 37.5 nmol/L (66%) had similar age, serum creatinine, serum phosphate, iPTH, blood pressure but lower calcium (9.3 ± 0.7 vs. 9.6 ± 0.5 mg/dL; p = 0.024), lower FGF23 (median 18.8 vs. 80.0 pg/mL; p = 0.013) and higher E-selectin (15.8 ± 7.9 vs. 13.0 ± 5.5 ng/mL; p = 0.047). On Univariate analysis, E-selectin (r = - 0.292; p = 0.005), FGF23 (r = 0.217; p = 0.036) and calcium (r = 0.238; p = 0.022) were significantly correlated with vitamin D levels. On stepwise multiple regression analysis, only E-selectin was associated with vitamin D levels (β = - 0.324; p = 0.002).

Conclusion: Vitamin D deficiency was common in kidney transplant recipients in North India, associated with low FGF23 and high E-selectin. These findings suggest further investigations to assess the role of vitamin D deficiency-associated endothelial dysfunction, its implications and reversibility in kidney transplantation recipients.
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http://dx.doi.org/10.1007/s11255-018-2014-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6327006PMC
January 2019

Utilization of high FFA landfill waste (leachates) as a feedstock for sustainable biodiesel production: its characterization and engine performance evaluation.

Environ Sci Pollut Res Int 2018 Nov 18;25(32):32312-32320. Epub 2018 Sep 18.

Department of Mechanical Engineering, F/O Engineering and Technology, Jamia Millia Islamia, New Delhi, 110025, India.

In present study, biodiesel was produced from landfill waste-derived oil by chemical transesterification process, to evaluate its potential as a renewable energy source for the first time. The free fatty acid percentage (FFA) in landfill waste oil is considered to be high, which was reduced by treating it with two different acids as catalyst, muriatic acid and phosphoric acid, in order to build a comparison between fatty acid methyl ester (FAME) contents. Further, it was treated with a base catalyst potassium hydroxide (KOH) to produce the final product. The FAME value of landfill oil when treated with muriatic acid was found to be 92.59%. The quality of biodiesel produced was analyzed by gas chromatography (GC), which indicated above 25.7% of conversion of oil into biodiesel when muriatic acid was used as a catalyst. The properties of the produced biodiesel were found to be in good agreement with ASTM D 6751 and EN 14214 standards. Various test fuels were prepared for the engine test by blending 10%, 20%, and 100% of landfill waste biodiesel in diesel on volumetric basis and designated as B10, B20, and B100, respectively. The brake thermal efficiency (BTE) of the engine was more while the exhaust emission was less except NOx with biodiesel and its blend (B10 and B20). Thus, landfill waste is a potential source of biodiesel, and blends of landfill waste up to 20% can be used for realizing better performance from the engine.
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http://dx.doi.org/10.1007/s11356-018-3199-0DOI Listing
November 2018

An Approach for Measuring the Dielectric Strength of OLED Materials.

Materials (Basel) 2018 Jun 9;11(6). Epub 2018 Jun 9.

Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.

Surface roughness of electrodes plays a key role in the dielectric breakdown of thin-film organic devices. The rate of breakdown will increase when there are stochastic sharp spikes on the surface of electrodes. Additionally, surface having spiking morphology makes the determination of dielectric strength very challenging, specifically when the layer is relatively thin. We demonstrate here a new approach to investigate the dielectric strength of organic thin films for organic light-emitting diodes (OLEDs). The thin films were deposited on a substrate using physical vapor deposition (PVD) under high vacuum. The device architectures used were glass substrate/indium tin oxide (ITO)/organic material/aluminum (Al) and glass substrate/Al/organic material/Al. The dielectric strength of the OLED materials was evaluated from the measured breakdown voltage and layer thickness.
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http://dx.doi.org/10.3390/ma11060979DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6025577PMC
June 2018

Uromodulin rs4293393 T>C variation is associated with kidney disease in patients with type 2 diabetes.

Indian J Med Res 2017 11;146(Suppol):S15-S21

Department of Nephrology, Postgraduate Institute of Medical Education & Research, Chandigarh; George Institute for Global Health, New Delhi, India; James Martin Fellow, University of Oxford, Oxford, UK.

Background & Objectives: Uromodulin, a UMOD gene encoded glycoprotein is synthesized exclusively in renal tubular cells and released into urine. Mutations lead to uromodulin misfolding and retention in the kidney, where it might stimulate cells of immune system to cause inflammation and progression of kidney disease. Genome-wide association studies (GWAS) have identified UMOD locus to be associated with hypertension and diabetic nephropathy (DN). In this study, we investigated the association between rs4293393 variation in UMOD gene and susceptibility to kidney disease in individuals with type 2 diabetes mellitus (T2DM).

Methods: A total of 646 individuals, 208 with T2DM without evidence of kidney disease (DM), 221 with DN and 217 healthy controls (HC) were genotyped for UMOD variant rs4293393T>C by restriction fragment length polymorphism. Serum uromodulin levels were quantified by enzyme-linked immunosorbent assay.

Results: A significant difference was found in genotype and allelic frequency among DM, DN and HC. TC+CC genotype and C allele were found more frequently in DN compared to HC (33.9 vs 23.0%, P=0.011 and 20.1 vs 12.9%, P=0.004, respectively). Compared to DM, C allele was found to be more frequent in individuals with DN (20.1 vs 14.7%, P=0.034). Those with DN had higher serum uromodulin levels compared to those with DM (P=0.001). Serum uromodulin levels showed a positive correlation with serum creatinine (r=0.431; P<0.001) and negative correlation with estimated glomerular filtration rate (r=-0.423; P<0.001).

Interpretation & Conclusions: The frequency of UMOD rs4293393 variant with C allele was significantly higher in individuals with DN. UMOD rs4293393 T>C variation might have a bearing on susceptibility to nephropathy in north Indian individuals with type 2 diabetes.
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http://dx.doi.org/10.4103/ijmr.IJMR_919_16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5890591PMC
November 2017

Exploring Defect-Induced Emission in ZnAlO: An Exceptional Color-Tunable Phosphor Material with Diverse Lifetimes.

Inorg Chem 2018 Apr 16;57(7):3963-3982. Epub 2018 Mar 16.

Radiochemistry Division , Bhabha Atomic Research Centre , Mumbai 400085 , India.

Activator-free zinc aluminate (ZA) nanophosphor was synthesized through a sol-gel combustion route, which can be used both as a blue-emitting phosphor material and a white-emitting phosphor material, depending on the annealing temperature during synthesis. The material also has the potential to be used in optical thermometry. These fascinating color-tunable emission characteristics can be linked with the various defect centers present inside the matrix and their changes upon thermal annealing. Various defect centers, such as anionic vacancy, cationic vacancy, antisite defect, etc., create different electronic states inside the band gap, which are responsible for the multicolor emission. The color components are isolated from the complex emission spectra using time-resolved emission spectroscopy (TRES) study. Interestingly, the lifetime values of the various defect centers were found to change significantly from milliseconds to microseconds upon thermal annealing, which makes the phosphors more diverse (i.e., either long-persistent blue-emitting phosphors or short-persistent white-emitting phosphors). Fourier transform infrared (FTIR) and diffuse reflectance spectroscopy (DRS) confirmed the presence of antisite defect centers such as Al or Zn in the matrix. X-ray absorption fine structure (EXAFS) study showed that the spinel structure was more disordered in nature for low-temperature-annealed compounds. Electron paramagnetic resonance (EPR) and positron annihilation lifetime spectroscopy (PALS) studies were also carried out in order to characterize various anionic and cationic vacancies and their clusters present in the compounds. Antisite defect centers such as Al or Zn, which act as an electron or hole trap, were found to be responsible for the diverse lifetime behavior. To gain insight about the electronic states inside the band gap, density functional theory (DFT)-based calculations were performed for both pure and various vacancy-introduced spinel structures. Finally, based on the theoretical and experimental results, for the first time, a detailed investigation of various defect-induced emission behavior in ZA is presented, which also explains the mechanism of color tunability and dynamic lifetimes.
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http://dx.doi.org/10.1021/acs.inorgchem.8b00172DOI Listing
April 2018

Existing creatinine-based equations overestimate glomerular filtration rate in Indians.

BMC Nephrol 2018 02 1;19(1):22. Epub 2018 Feb 1.

Department of Nephrology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

Background: Accurate estimation of glomerular filtration rate (GFR) is important for diagnosis and risk stratification in chronic kidney disease and for selection of living donors. Ethnic differences have required correction factors in the originally developed creatinine-based GFR estimation equations for populations around the world. Existing equations have not been validated in the vegetarian Indian population. We examined the performance of creatinine and cystatin-based GFR estimating equations in Indians.

Methods: GFR was measured by urinary clearance of inulin. Serum creatinine was measured using IDMS-traceable Jaffe's and enzymatic assays, and cystatin C by colloidal gold immunoassay. Dietary protein intake was calculated by measuring urinary nitrogen appearance. Bias, precision and accuracy were calculated for the eGFR equations.

Results: A total of 130 participants (63 healthy kidney donors and 67 with CKD) were studied. About 50% were vegetarians, and the remainder ate meat 3.8 times every month. The average creatinine excretion were 14.7 mg/kg/day (95% CI: 13.5 to 15.9 mg/kg/day) and 12.4 mg/kg/day (95% CI: 11.2 to 13.6 mg/kg/day) in males and females, respectively. The average daily protein intake was 46.1 g/day (95% CI: 43.2 to 48.8 g/day). The mean mGFR in the study population was 51.66 ± 31.68 ml/min/1.73m. All creatinine-based eGFR equations overestimated GFR (p < 0.01 for each creatinine based eGFR equation). However, eGFR by CKD-EPI was not significantly different from mGFR (p = 0.38). The CKD-EPI exhibited lowest bias [mean bias: -3.53 ± 14.70 ml/min/1.73m (95% CI: -0.608 to -0.98)] and highest accuracy (P: 74.6%). The GFR in the healthy population was 79.44 ± 20.19 (range: 41.90-134.50) ml/min/1.73m.

Conclusion: Existing creatinine-based GFR estimating equations overestimate GFR in Indians. An appropriately powered study is needed to develop either a correction factor or a new equation for accurate assessment of kidney function in the Indian population.
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http://dx.doi.org/10.1186/s12882-018-0813-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5796440PMC
February 2018

Effect of vitamin D supplementation on serum sclerostin levels in chronic kidney disease.

J Steroid Biochem Mol Biol 2018 06 10;180:15-18. Epub 2018 Jan 10.

Department of Nephrology, Postgraduate Institute of Medical Education and Research, Chandigarh, India; The George Institute for Global Health, New Delhi, India; University of Oxford, Oxford, England, United Kingdom.

Vitamin D deficiency, cardiovascular disease and abnormal bone mineral metabolism are common in chronic kidney disease (CKD). Abnormal bone mineral metabolism has been linked to vascular calcification in CKD. Sclerostin has emerged as an important messenger in cross talk between bone-vascular axis. We analyzed sclerostin in subjects who participated in the randomized, double blind, placebo controlled trial investigating the effect of cholecalciferol supplementation on vascular function in non-diabetic CKD stage G3-4 and vitamin D ≤ 20 ng/ml [CTRI/2013/05/003648]. Patients were randomized (1:1) to receive either two directly observed oral doses of 300,000 IU of cholecalciferol or matching placebo at baseline and 8 weeks. Of the 120 subjects enrolled, 58 in the cholecalciferol group and 59 in the placebo group completed the study. At baseline, serum levels of sclerostin were similar in both groups (cholecalciferol - median;190pg/ml, IQR;140-260 pg/ml and placebo - median;180 pg/ml, IQR; 140-240 pg/ml, p = 0.67). 16 weeks after cholecalciferol supplementation, there was no change in level of sclerostin (mean change;1.10 pg/ml, 95%CI; -27.34 to 29.34 pg/ml, p = 0.25). However, a significant decrease in sclerostin level was noted in the placebo group (mean change; -31.94 pg/ml, 95%CI; -54.76 to -9.13 pg/ml, p = 0.002). Change (Δ) in sclerostin level at 16 weeks correlated negatively with Δ eGFR (r = -0.20, p = 0.03) and positively with Δuric acid (r = 0.37, p < 0.001) but not with Δ25(OH) D (r = 0.06, p = 0.54), Δ iPTH (r = - 0.03, p = 0.78) ΔFGF23 (r = - 0.08, p = 0.38) and Δ125 (OH) D (r = - 0.04, p = 0.65). In conclusion, high dose cholecalciferol supplementation did not change sclerostin levels in non-diabetic stage 3-4 CKD subjects.
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http://dx.doi.org/10.1016/j.jsbmb.2018.01.007DOI Listing
June 2018

Vascular function and cholecalciferol supplementation in CKD: A self-controlled case series.

J Steroid Biochem Mol Biol 2018 06 5;180:19-22. Epub 2018 Jan 5.

Department of Nephrology, Postgraduate Institute of Medical Education and Research, Chandigarh, India; George Institute for Global Health, New Delhi, India; George Institute for Global Health, University of Oxford, Oxford, UK.

Vitamin D deficiency is common and associated with mortality in chronic kidney disease (CKD) patients. Cardiovascular disease (CVD) is the commonest cause of mortality in CKD patients. In a randomized, double blind, placebo controlled trial, we have recently reported favorable effects of vitamin D supplementation on vascular & endothelial function and inflammatory biomarkers in vitamin D deficient patients with non-diabetic stage 3-4 CKD (J Am Soc Nephrol 28: 3100-3108, 2017). Subjects in the placebo group who had still not received vitamin D after completion of the trial received two oral doses 300,000 IU of oral cholecalciferol at 8 weeks interval followed by flow mediated dilatation (FMD), pulse wave velocity (PWV), circulating endothelial and inflammatory markers (E-Selectin, vWF, hsCRP and IL-6), 125 (OH)D, iPTH and iFGF-23 assessment at 16 weeks. 31 subjects completed this phase of the study. Last values recorded in the preceding clinical trial were taken as baseline values. Serum 25(OH)D and 1,25(OH)D increased and FMD significantly improved after cholecalciferol supplementation [mean change in FMD%: 5.8% (95% CI: 4.0-7.5%, p < 0.001]. Endothelium independent nitroglycerine mediated dilatation, PWV, iPTH, iFGF-23 and IL-6 also showed favorable changes. The data further cement the findings of beneficial effects of correction of vitamin D deficiency on vascular function.
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http://dx.doi.org/10.1016/j.jsbmb.2018.01.001DOI Listing
June 2018

Deciphering the Role of Charge Compensator in Optical Properties of SrWO:Eu:A (A = Li, Na, K): Spectroscopic Insight Using Photoluminescence, Positron Annihilation, and X-ray Absorption.

Inorg Chem 2018 Jan 2;57(2):821-832. Epub 2018 Jan 2.

Radiochemistry Division, ‡Atomic and Molecular Physics Division, and §Fuel Chemistry Division, Bhabha Atomic Research Centre , Trombay, Mumbai 400085, India.

Studies have been carried out to understand the specific role of the alkali charge compensator on the luminescence properties of an alkali ion (Li, Na, and K) codoped SrWO:Eu phosphor. The oxidation state of the europium ion was found to be +3 on the basis of X-ray absorption near edge structure (XANES) measurements. This is the first report of its kind where opposite effects of Li ion and Na/K ions on photoluminescence intensity have been observed. Li ion codoping enhanced the photoluminescence intensity from SrWO:Eu phosphor while Na/K ion codoping did not. On the other hand, the luminescence lifetime is maximum for the Na ion codoped sample and minimum for the Li ion codoped sample. The results could be explained successfully using time-resolved luminescence, positron annihilation lifetime spectroscopy (PALS), and extended X-ray absorption fine structure (EXAFS) spectroscopy measurements. Changes in the Eu-O bond length and Debye-Waller Factor (σ) upon Li/Na/K codoping were monitored through EXAFS measurements. PALS also highlighted the fact that Li codoping is not contributing to reduction in the cation vacancies and might be occupying interstitial sites rather than lattice positions due to its very small size. On europium doping there is lowering in symmetry of SrO polyhedra from S to C, which is reflected in an intense electric dipole transition in comparison to the magnetic dipole transition. This is also corroborated using trends in Judd-Ofelt parameters. The results have shown that the luminescence lifetime is better when the vacancy concentration is lower as induced by Na and K codoping, while the emission intensity is higher in the samples when distortion around Eu is reduced as induced by Li codoping.
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http://dx.doi.org/10.1021/acs.inorgchem.7b02780DOI Listing
January 2018
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