Browsing by Author "Rakesh Kumar Tyagi"

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Advances in analytical methods for BPA detection in commercial milk: Current techniques and future prospects
(Academic Press Inc., 2025) Hagera Dilnashin; Dheer Singh; Partha Pratim Roy; Rakesh Kumar Tyagi; Surya Pratap Singh
Bisphenol A (BPA) is a widely produced chemical, primarily used in the manufacture of polycarbonate plastics and epoxy resins. It is commonly found in food and beverage packaging, such as milk, water, and infant bottles, as well as in dental sealants and food can coatings. The primary source of BPA exposure in humans is dietary intake, with milk and dairy products contributing significantly, particularly among younger populations. Other exposure pathways include air, water, and dust. This review provides an overview of the analytical methods developed in recent years for detecting BPA. It examines the advantages and limitations of various sample preparation techniques, including microextraction, molecularly imprinted polymer solid-phase extraction, and solid-phase extraction. Furthermore, we discuss the advancements in analytical techniques, such as immunoassays, liquid and gas chromatography–mass spectrometry, and emerging biosensors. The review highlights recent progress in BPA detection methodologies and outlines potential future developments in this field. © 2024 Elsevier Inc.
Organochlorine pesticide dieldrin upregulate proximal promoter (PII) driven CYP19A1 gene expression and increases estrogen production in granulosa cells
(Elsevier Inc., 2021) Deeksha Sharma; Suman Kumari; Payal Rani; Suneel Kumar Onteru; Partha Roy; Rakesh Kumar Tyagi; Surya Pratap Singh; Dheer Singh
Organochlorine pesticides are highly persistent environmental pollutants, generally shown to act through estrogen receptor alpha and alter estrogen biosynthesis. However, the molecular mechanism of regulation of estrogen biosynthesis by these pesticides is not clear. Estrogen is main female fertility hormone regulated by rate-limiting enzyme aromatase. It is encoded by the CYP19A1 gene, which is expressed using specific promoters. In the present study, the attempt has been made to elucidate the effect of dieldrin on the promoter-specific CYP19A1 gene expression and estrogen hormone production in buffalo granulosa cells. The buffalo granulosa cells were cultured and treated with dieldrin in a dose (100,150 and 200 ng/mL) and time (6, 12, and 24 h) dependent manner, followed by analysis of CYP19A1, promoter-specific CYP19A1 transcript expression, and estrogen production. Results showed that dieldrin significantly increased the expression of the CYP19A1 gene after 6 and 12 h while its expression was decreased after 24 h. To understand the upregulation of CYP19A1 gene, promoters’ specific CYP19A1 transcript analysis was done. The finding showed that dieldrin significantly increased the proximal promoter specific CYP19A1 transcript while there was no effect on distal promoter specific CYP19A1 transcripts. This specific-promoter activity was quantified by chromatin immunoprecipitation assay (ChIP). Results confirmed the involvement of the proximal promoter in the overexpression of CYP19A1 gene. Furthermore, a significant increase in estradiol-17β level was also observed. Overall, the present study demonstrated the stimulatory effect of dieldrin on the CYP19A1 gene and will help to understand the toxicological role of dieldrin on the reproductive system. © 2021