Bromuconazole-induced hepatotoxicity is accompanied by upregulation of PXR/CYP3A1 and downregulation of CAR/CYP2B1 gene expression

Despite widespread use of bromuconazole as a pesticide for food crops and fruits, limited studies have been done to evaluate its toxic effects. Here, we evaluated the hepatotoxic effect of bromuconazole using classical toxicological (biochemical analysis and histopathological examination) and gene-based molecular methods. Male rats were treated either orally or topically with bromuconazole at doses equal to no observed adverse effect level (NOAEL) and 1/10 LD50 for 90?d. Bromuconazole increased activities of liver enzymes (ALT, AST, ALP, and ACP), and levels of bilirubin. It also induced hepatic oxidative stress as evidenced by significant decrease in the activities of superoxide dismutase (SOD), and significant increase in levels of malondialdehyde (MDA) in liver. In addition, bromuconazole caused an increase in liver weights and necrobiotic changes (vacuolation and hepatocellular hypertrophy). It also strongly induced the expression of PXR and its downstream target CYP3A1 gene as well as the activity of CYP3A1. However, it inhibited the expression of CAR and its downstream target CYP2B1 gene without significant changing in CYP2B1 activity. Overall, the oral route showed higher hepatotoxic effect and molecular changes than the dermal route and all changes were dose dependent. This is the first investigation to report that bromuconazole-induced liver oxidative damage is accompanied by upregulation of PXR/CYP3A1 and downregulation of CAR/CYP2B1.     

Biallelic Pathogenic GFRA1 Variants Cause Autosomal Recessive Bilateral Renal Agenesis

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Molecular Docking Studies of Phytocompounds from the Phyllanthus Species as Potential Chronic Pain Modulators

The study of inflammatory pain has been one of the most rapidly advancing and expanding areas of pain research in recent years. Studies from our lab have demonstrated the chronic pain-modulating potential of the Phyllanthus species and their probable interaction with various inflammatory mediators involving enzymes like COX-2 and PGE synthase, cytokines like TNF-alpha and IL-1 beta, and with the NMDA receptor. Inflammatory mediators which play a crucial role in chronic inflammatory hyperalgesia and its subsequent modulation were selected for their interactions with 86 structurally diverse phytoconstituents identified from the Phyllanthus species.The docking analysis of the target proteins with the phytochemical ligands was performed using VLifeMDS software. The docking scores and analysis of the interactions of the phytocompounds with target proteins suggest that important molecules like lupeol, phyllanthin, hypopyllanthin, corilagin, epicatechin, and most of the other compounds have the ability to bind to multiple targets involved in inflammatory hyperalgesia.Our study strongly suggests that the findings of the present study could be exploited in the future for designing ligands in order to obtain novel molecules for the treatment and management of chronic pain.     

Photoaffinity Labeling of Nicotinic Receptors: Diversity of Drug Binding Sites!

For almost 30 years, photoaffinity labeling and protein microsequencing techniques have been providing novel insights about the structure of nicotinic acetylcholine receptors (nAChR) and the diversity of nAChR drug binding sites. Photoaffinity labeling allows direct identification of amino acid residues contributing to a drug binding site without prior knowledge of the location of the binding site within the nAChR or the orientation of the ligand within the binding site. It also distinguishes amino acids that contribute to allosteric binding sites from those involved in allosteric modulation of gating. While photoaffinity labeling was used initially to identify amino acids contributing to the agonist binding sites and the ion channel, it has been used recently to identify binding sites for allosteric modulators at subunit interfaces in the extracellular and the transmembrane domains, and within a subunit's transmembrane helix bundle. In this article, we review the different types of photoaffinity probes that have been used and the various binding sites that have been identified within the structure of nAChR, with emphasis on our recent studies of allosteric modulator binding sites.     

The role of epoxide hydrolases in health and disease

Epoxide hydrolases (EH) are ubiquitously expressed in all living organisms and in almost all organs and tissues. They are mainly subdivided into microsomal and soluble EH and catalyze the hydration of epoxides, three-membered-cyclic ethers, to their corresponding dihydrodiols. Owning to the high chemical reactivity of xenobiotic epoxides, microsomal EH is considered protective enzyme against mutagenic and carcinogenic initiation. Nevertheless, several endogenously produced epoxides of fatty acids function as important regulatory mediators. By mediating the formation of cytotoxic dihydrodiol fatty acids on the expense of cytoprotective epoxides of fatty acids, soluble EH is considered to have cytotoxic activity. Indeed, the attenuation of microsomal EH, achieved by chemical inhibitors or preexists due to specific genetic polymorphisms, is linked to the aggravation of the toxicity of xenobiotics, as well as the risk of cancer and inflammatory diseases, whereas soluble EH inhibition has been emerged as a promising intervention against several diseases, most importantly cardiovascular, lung and metabolic diseases. However, there is reportedly a significant overlap in substrate selectivity between microsomal and soluble EH. In addition, microsomal and soluble EH were found to have the same catalytic triad and identical molecular mechanism. Consequently, the physiological functions of microsomal and soluble EH are also overlapped. Thus, studying the biological effects of microsomal or soluble EH alterations needs to include the effects on both the metabolism of reactive metabolites, as well as epoxides of fatty acids. This review focuses on the multifaceted role of EH in the metabolism of xenobiotic and endogenous epoxides and the impact of EH modulations.     

Cellular proliferation in the nasal septal cartilage of juvenile minipigs

The growth of the nasal septal cartilage is believed to be a driving force of midfacial growth. Cellular proliferation is an important contributor to growth of the cartilage, but this factor has been rarely investigated. The current study was undertaken to assess the proliferation and cellular density in the septal cartilage of fast-growing juvenile minipigs. Six minipigs averaging 4.4 ± 1 months old were injected with 5′-bromo-2′-deoxyuridine (BrdU), a thymidine analog, 24 h before death. The septal cartilage was sectioned in the coronal plane and reacted for BrdU. The proliferative index (number of BrdU-positive chondrocytes/total number of chondrocytes) and cellular density (number of cells mm⁻²) of various locations of the septum were measured and compared in order to determine overall proliferation rate and whether regional variations in proliferative activity and cellular density are present. To provide a time perspective to the problem of midfacial growth, the lengths of the nasal bone and the palate were measured in a collection of 61 dry skulls of minipigs aged 1–8 months. Results showed that the septal chondrocytes were proliferating at a surprisingly high rate (∼21%). The proliferative index was higher in the ventral and middle compared with the dorsal locations, and in the central cartilage compared with the perichondrium. No difference in proliferative index was found between the anterior and posterior parts of the septum. Cellular density was higher in the perichondrium than in the central cartilage. Within the central cartilage there was a trend for higher cellular density anteriorly. In conclusion, the rapidly growing midface of juvenile minipigs is associated with a high rate of septal proliferation, especially in the ventral half of the cartilage.