Microplastic Pollution in the Gastrointestinal Tract and Gills of Some Teleost and Sturgeon Fish from the Caspian Sea, Northern Iran.

The increasing microplastic pollution in the marine environment has raised global concern. The main risk of microplastics in aquatic ecosystem is their bioaccumulation in aquatic organisms. A few studies have reported microplastic pollution in the digestive system of Caspian Sea fish species, but there is no research on sturgeon species, nor on fish gills. We investigated the occurrence of microplastics in the gastrointestinal tract (GIT) and gills of 62 specimens belonging to four species including three teleosts (Cyprinus carpio, Rutilus kutum, and Chelon aurata) and one sturgeon (Acipenser persicus, a valuable endangered species) from the Caspian Sea between January and March 2022. Fish tissues were removed, exposed for 24 h to 10% KOH, and then dried on filter paper. Particles were observed under a stereomicroscope and analyzed by Raman microspectrometry, scanning electron microscopy, and energy-dispersive spectroscopy. A total of 91 microplastics were detected in the GIT (average of 1.46 ± 1.17 items/individual) and 63 microplastics in the gills (average of 1.01 ± 0.62 items/individual). A significant correlation was not found between the number of microplastics found in both tissues and fish body length, body weight, GIT weight, and gill weight (p > 0.05), except between microplastics isolated from gills and gill weight in C. carpio (rs = 0.707, p = 0.022). The abundance of microplastics in fish followed the order of A. persicus > C. aurata > R. kutum > C. carpio. The microplastics were in the size range of 45 to 5000 µm, with particles of 300 to 1000 µm being the most prevalent; 74.68% of the particles were shaped like fibers, 30.53% were red, and 70.6% were composed of nylon polymer. Environ Toxicol Chem 2023;42:2453-2465. © 2023 SETAC.

High-performance strategy for the construction of electrochemical biosensor for simultaneous detection of miRNA-141 and miRNA-21 as lung cancer biomarkers.

In this study, the dual signal-labeled hairpin-structured DNA (dhDNA)-based probes have been developed to construct a novel nano-biosensor. This one hairpin-structured probe consists of a thiolated methylene blue-labeled hairpin capture probe (MB-HCP) as an inner reference probe and a ferrocene-modified anti-miRNA-21 DNA probe (Fc-AP-21). This novel integrated structure of MB-HCP and Fc-AP-21 was designed on one sensing interface for sensitive and simultaneous detection of the miRNA-141 and miRNA-21 in one single assay. The proposed strategy has a good ability to reduce the interference of environmental factors and it was designed to control the initial responses of Fc-AP to MB-HCP ((IFc/IMB)0) at a 1:1 ratio, which is desirable for further increase in the sensitivity and signal-to-noise ratio of the biosensor operation. Besides, the biosensor was first prepared by immobilizing the dhDNA (Fc-AP-21/MB-HCP) onto the modified glassy carbon electrode. After hybridization with the anti-miRNA-141 complementary sequence (ACP-141), the dhDNA structure was compelled to open and form the final structure of the biosensor. Also, the miRNA-141 and miRNA-21 dissociate duplex structures due to the highly matched sequences between the miRNA-141 and ACP-141 and the miRNA-21 and Fc-AP-21. A linear relationship was found between the logarithm of miRNA-141 and miRNA-21 concentrations and the signal changes. This feature was used to detect the two miRNAs. This sensitive biosensor provided low detection limits of 0.89 and 1.24 fM for the miRNA-141 and miRNA-21, respectively. Also, it has wide linear ranges of 2.0 to 105 fM, with highly selective and accurate results for its application in plasma samples. Therefore, this strategy can be promising as a suitable platform for simultaneous and early detection of various cancer biomarkers.

A ratiometric electrochemical DNA-biosensor for detection of miR-141.

A sensitive biosensor for the detection of miR-141 has been constructed. The DNA-biosensor is prepared by first immobilizing the thiolated methylene blue-labeled hairpin capture probe (MB-HCP) on two-layer nanocomposite film graphene oxide-chitosan@ polyvinylpyrrolidone-gold nanourchin modified glassy carbon electrode. We used the hematoxylin as an electrochemical auxiliary indicator in the second stage to recognize DNA hybridization via the square wave voltammetry (SWV) responses that record the accumulated hematoxylin on electrode surfaces. The morphology and chemical composition of nanocomposite was characterized using TEM, FE-SEM, and FT-IR techniques. The preparation stages of the DNA-biosensor were screened by electrochemical impedance spectroscopy and cyclic voltammetry. The proposed DNA-biosensor can distinguish miR-141 from a non-complementary and mismatch sequence. A detection limit of 0.94 fM and a linear range of 2.0 -5.0 × 105 fM were obtained using SWV for miR-141 detection. The working potential for methylene blue and hematoxylin was -0.28 and + 0.15 V vs. Ag/AgCl, respectively. The developed biosensor can be successfully used in the early detection of non-small cell lung cancer (NSCLC) by directly measuring miR-141 in human plasma samples. This novel DNA-biosensor is of promise in early sensitive clinical diagnosis of cancers with miR-141 as its biomarker.

Microsurgical approach to the conjunctival flap.

OBJECTIVES: To describe a microsurgical approach to a selective pedunculated conjunctival flap for the treatment of chronic corneal ulceration with or without corneal perforation, and to present the results of 50 consecutive cases. DESIGN: Retrospective, noncomparative case series and case reports. Patients All patients who had microsurgical conjunctival flap procedures for the treatment of chronic corneal ulcers between 1982 and 1996 at the Connecticut Eyecare Center, New Haven. INTERVENTIONS: Partial pedunculated conjunctival flap surgery. METHODS: Review of the initial ocular diagnoses and characteristics as well as retrospective study of the postoperative course. MAIN OUTCOME MEASURES: Resolution of the corneal ulcer and postoperative stability of the conjunctival flap. RESULTS: Sixty-two percent of the corneal ulcers treated were nonperforated, and 38% were perforated. The diagnoses included herpes simplex virus (14 patients), bacterial ulcer (11 patients), rheumatoid arthritis (8 patients), aphakic bullous keratopathy (6 patients), graft rejection (4 patients), herpes zoster virus (5 patients), and other (2 patients). Postoperatively, 94% of the conjunctival flaps were stable, and 3% had failed. The procedures were definitive in 64% of cases and temporary in 36%; 61% of patients received a corneal transplant 6 to 24 months postoperatively, and in 38% the flaps were removed 6 to 12 months after the original lesion had healed. CONCLUSION: A selective pedunculated conjunctival flap is an effective and practical surgical approach to the treatment of perforated and nonperforated corneal ulcers that have not responded to other types of medical therapy.