Oxytetracycline (OTC) is a broad-spectrum tetracycline antibiotic widely used in domestic animals. In South Korea, OTC was not approved as a veterinary medicinal product (VMP) for use in laying hens at the time of this study, although residues may occur in eggs through misuse, off-label use, or feed cross-contamination. Oxytetracycline residue depletion was evaluated in individual whole eggs to provide reference data for residue management in laying hens. Korean Hy-Line Brown laying hens were administered OTC in feed for 14 consecutive days at 402 mg/kg of feed (1×, estimated intake, 18.6 mg/kg bw/day, the feed concentration stated on the feed additive product label for chickens) or 804 mg/kg of feed (2×, 43.0 mg/kg bw/day, a conservative overexposure scenario). Eggs were collected over 35 days (14-day administration and 21-day withdrawal) and analyzed individually as whole eggs by a validated LC–MS/MS method. The coefficient of determination (R2) of the matrix-matched calibration curves (3.125–100 µg/kg) ranged from 0.9882 to 0.9998. The mean recovery at the lower limit of quantification (LLOQ) level was 112.6
Toxoplasma gondii is a globally prevalent zoonotic apicomplexan parasite. Its reversible transition between fast-replicating tachyzoites and dormant, cyst-encased bradyzoites underpins latent infection, disease recurrence and poor therapeutic outcomes. Immunocompetent hosts usually show no symptoms after primary infection, whereas bradyzoite reactivation in immunocompromised people causes fatal cerebral toxoplasmosis; congenital infection and neuropsychiatric complications also greatly increase the disease burden. Conventional drugs only act on tachyzoites and cannot eliminate metabolically inactive bradyzoites shielded by cyst walls. This review outlines the morphological, metabolic and molecular differences between the two stages, and summarizes diverse triggers for stage conversion including environmental stress, host immune pressure and parasite-intrinsic programs. We also elaborate multi-layered regulatory mechanisms, host adaptation and immune evasion strategies. Moreover, we discuss promising therapeutic targets, advanced research models, current limitations and future research priorities. Unravelling stage conversion mechanisms will facilitate the development of curative treatments for chronic toxoplasmosis.
Global aquaculture is rapidly developing as a production system for aquatic animal-derived foods. Sustainable production in the marine industry is not only hindered by disease challenges but also limited by the use of synthetic drugs against these disease outbreaks because of their tissue accumulation, which leads to resistant pathogens. As an alternative, medicinal herbs are mentioned in aquaculture as eco-friendly and safe products for preventing pathogens, enhancing growth, and improving the immune system. Moreover, medicinal herbs protect aquatic animals from stressful stimuli, including overcrowding, high temperatures, and poor water quality. Given the increased need of the aquaculture industry for phytoconstituents and their potential sources, this review mainly focuses on providing information on the nutritional, biochemical, and physiological impacts and the action mechanisms of herbal medicines from the Lamiaceae, Fabaceae, and Asteraceae families on aquatic species. Recent studies indicate that nano-enabled delivery systems can substantially improve the performance of herbal compounds, and this review therefore highlights the growing potential of integrating nanotechnology with phytobiotics to enhance their stability, bioavailability, and functional outcomes in aquaculture. Emerging nanotechnological delivery systems, including encapsulation in polymeric nanoparticles, liposomes, and metal-based nanoparticles synthesized using plant extracts, offer significant advantages for improving the stability, bioavailability, and targeted delivery of phytobiotic compounds. Nanoencapsulation of essential oils and bioactive phytochemicals (e.g., thymol, curcumin, rosmarinic acid) has shown particular promise in enhancing their solubility, protecting them from degradation in the gastrointestinal tract, and enabling controlled release, thereby maximizing their immunostimulatory, antioxidant, and antimicrobial effects in aquatic species. Essential information is presented about phytobiotics from these plant families and their mode of action, mode of administration and dosage, and other vital issues for phytobiotic research in aquaculture. Importantly, the review suggests that the practical use of these green drugs requires further investigation to uncover the biological functions of active compounds responsible for growth, immune, and pathogen resistance across diverse species of aquatic animals. With analysing 162 peer-reviewed studies, this review provides, for the first time, a comprehensive comparative analysis of phytobiotics from the Lamiaceae, Fabaceae, and Asteraceae families, integrating their mechanisms of action, dose-dependent effects, nanotechnology-based delivery systems and emerging nanotechnological applications, while identifying critical research gaps and future directions for sustainable aquaculture. The knowledge derived from the current discussion provides an exciting opportunity for the practical use of natural drugs in aquaculture.
Bovine respiratory disease (BRD) is a health and economic problem in intensive beef production. Antimicrobial (ATM) therapy requires adequate ATM concentrations at the pulmonary infection site. This study determined pulmonary concentrations of tilmicosin (TIL) and gamithromycin (GAM) in cattle that died from BRD under field conditions and characterized the ATM susceptibility of isolates recovered from affected lungs. Lung samples from 41 cattle were analyzed by liquid chromatography–tandem mass spectrometry. TIL was detected in 56.1
