Characterization of L-amino Acid Oxidase Derived from Crotalus adamanteus Venom: Procoagulant and Anticoagulant Activities

Pulmonary involvement from animal toxins: the cellular mechanisms

Venomous animals and their venom have always been of human interest because, despite species differences, coevolution has made them capable of targeting key physiological components of our bodies. Respiratory failure from lung injury is one of the serious consequences of envenomation, and the underlying mechanisms are rarely discussed. This review aims to demonstrate how toxins affect the pulmonary system through various biological pathways. Herein, we propose the common underlying cellular mechanisms of toxin-induced lung injury: interference with normal cell function and integrity, disruption of normal vascular function, and provocation of excessive inflammation. Viperid snakebites are the leading cause of envenomation-induced lung injury, followed by other terrestrial venomous animals such as scorpions, spiders, and centipedes. Marine species, particularly jellyfish, can also inflict such injury. Common pulmonary manifestations include pulmonary edema, pulmonary hemorrhage, and exudative infiltration. Severe envenomation can result in acute respiratory distress syndrome. Pulmonary involvement suggests severe envenomation, thus recognizing these mechanisms and manifestations can aid physicians in providing appropriate treatment.

Direct Fluorescence Evaluation of d-Amino Acid Oxidase Activity Using a Synthetic d-Kynurenine Derivative

d-Amino acid oxidase (DAO) has been suggested to be associated with the central nervous system diseases, such as schizophrenia. We newly synthesized a nonfluorescent 5-methylthio-d-kynurenine (MeS-d-KYN), which was converted to blue-fluorescent 6-MeS-kynurenic acid (MeS-KYNA, λ_ex = 364 nm, λ_em = 450 nm) through a one-step reaction by incubation with DAO. It was revealed that fluorescence intensity increased accompanied by commercial porcine kidney DAO activity (unit) with a good correlation (R² = 0.9972), suggesting that the fluorometric evaluation of DAO activity using MeS-d-KYN is feasible. MeS-d-KYN was applied to fluorescent DAO imaging in cultured LLC-PK1 cells, and the blue fluorescence of MeS-KYNA overlapped considerably with the location of peroxisomes, which was suggested to be the location of DAO in the cells. Because fluorescence was diminished in the presence of 6-chloro-1,2-benzisoxazol-3(2H)-one (CBIO), a DAO inhibitor, it was considered that DAO activity in cells could be directly evaluated using MeS-d-KYN as the substrate.