Investigating the impact of chlorine dioxide in shrimp-rearing water on the stomach microbiome, gill transcriptome, and infection-related mortality in shrimp.

AIMS: This study aimed to assess the effects of chlorine dioxide (ClO2) in water on whiteleg shrimp Penaeus vannamei, evaluating its impact on the stomach microbiota, gill transcriptome, and pathogens. METHODS AND RESULTS: ClO2 was added to the aquarium tanks containing the shrimp. The application of ClO2 to rearing water was lethal to shrimp at concentrations above 1.2 ppm. On the other hand, most of the shrimp survived at 1.0 ppm of ClO2. Microbiome analysis showed that ClO2 administration at 1.0 ppm significantly reduced the α-diversity of bacterial community composition in the shrimp stomach, and this condition persisted for at least 7 days. Transcriptome analysis of shrimp gill revealed that ClO2 treatment caused massive change of the gene expression profile, including stress response genes. However, after 7 days of the treatment, the gene expression profile was similar to that of shrimp in the untreated control group, suggesting a recovery to the normal state. This 1.0-ppm ClO2 significantly reduced shrimp mortality in artificial challenges with an acute hepatopancreatic necrosis disease-causing Vibrio parahaemolyticus and white spot syndrome virus, which were added to rearing water. CONCLUSIONS: The use of ClO2 at appropriate concentrations effectively eliminates a significant portion of the bacteria in the shrimp stomach and pathogens in the water. The results of this study provide fundamental knowledge on the disinfection of pathogens in water using ClO2 and the creation of semi germ-free shrimp, which has significantly decreased microbiome in the stomach.

The Inhibitory Effect of Wood Creosote on the Movement of Anisakis Larvae: An Implication for the Treatment of Acute Anisakiasis.

INTRODUCTION: Anisakiasis is a common disease in countries such as Japan, where raw or undercooked marine fish are frequently consumed. The disease is caused by accidental ingestion of a live larva of Anisakis in raw or undercooked marine fish. In typical cases, it causes abrupt gastrointestinal symptoms, such as epigastric pain, nausea, and vomiting. According to a published report, the disease was alleviated by oral ingestion of an over-the-counter drug containing wood creosote. METHODS: We performed an in vitro experiment to elucidate whether wood creosote can inhibit the motor activity of Anisakis larvae, using infrared locomotion tracking and agarose gel penetration techniques. RESULTS: Our results clearly demonstrate that wood creosote inhibits the motor activity of Anisakis larvae. The concentration of wood creosote used in our experiment is similar to that found in stomach juice when a usual oral dose is taken of the medicine containing wood creosote. DISCUSSION/CONCLUSION: Our results suggest the potential usefulness of the medicine containing wood creosote in the treatment of acute Anisakis infection of the gastrointestinal tract.

Inhibition of Acetylcholinesterase by Wood Creosote and Simple Phenolic Compounds.

Anisakiasis is common in countries where raw or incompletely cooked marine fish are consumed. Currently, effective therapeutic methods to treat anisakiasis are unavailable. A recent study found that wood creosote inactivates the movement of Anisakis species. Essential oil of Origanum compactum containing carvacrol and thymol, which are similar to the constituents of wood creosote, was reported to inactivate Anisakis by inhibiting its acetylcholinesterase. We examined whether wood creosote can also inhibit acetylcholinesterase. We examined the effect of components of wood creosote using the same experimental method. A computer simulation experiment (molecular docking) was also performed. Here, we demonstrate that wood creosote inactivated acetylcholinesterase in a dose-dependent manner with an IC50 of 0.25 mg/mL. Components of wood creosote were also tested individually: 5-methylguaiacol, p-cresol, guaiacol, o-cresol, 2,4-dimethylphenol, m-cresol, phenol and 4-methylguaiacol inactivated the enzyme with an IC50 of 14.0, 5.6, 17.0, 6.3, 3.9, 10.0, 15.2 and 27.2 mM, respectively. The mechanism of acetylcholinesterase inactivation was analyzed using a computer-based molecular docking simulation, which employed a three-dimensional structure of acetylcholinesterase and above phenolic compounds as docking ligands. The simulation indicated that the phenolic compounds bind to the active site of the enzyme, thereby competitively blocking entry of the substrate acetylcholine. These findings suggest that the mechanism for the inactivation of Anisakis movement by wood creosote is due to inhibition of acetylcholinesterase needed for motor neuron activity.

Evaluation of highly branched cyclic dextrin in inhalable particles of combined antibiotics for the pulmonary delivery of anti-tuberculosis drugs.

This work aims to identify a suitable formulation for the pulmonary delivery of combinations of inhalational drugs using highly branched cyclic dextrin (HBCD) macromolecules. We compared the effectiveness between powders prepared from HBCD with those prepared from five alternative excipients (lactose, maltose, sucrose, ß-cyclodextrin and methyl ß-cyclodextrin) in the pulmonary delivery of a single-dosage form of two anti-tuberculosis drugs (isoniazid and rifampicin). Fine particles of untreated active pharmaceutical ingredients (APIs) and combination products using excipients were prepared by spray drying. Rifampicin, a hydrophobic compound, was dissolved in ethanol, whereas isoniazid, a hydrophilic compound combined with either HBCD or an alternative excipient was dissolved in water. This was followed by the preparation of the spray-dried particle formulations (SDPs). The SDPs were characterised in terms of particle size, surface morphology, drug content, specific surface area, powder X-ray diffraction and inhalational properties. The addition of either an excipient or HBCD decreased API particle sizes, producing submicron-size particles. Surface morphology examination using scanning electron microscopy revealed API SDPs to be cylindrical and non-wrinkled. However, API-excipient SDPs were wrinkled and rough. Only HBCD SDPs were porous and non-aggregating, thereby suggesting superior aerodynamic properties and suitability for pulmonary delivery of these particles. HBCD formulations had the highest drug content in terms of both isoniazid (97.5%) and rifampicin (92.3%). Larger surface areas were obtained for SDPs of HBCD than those of other sugars. Regarding inhalational properties, HBCD formulations had higher emitted dose and fine-particle fractions than formulations of all other sugars tested. Our results confirm the feasibility of the formulation of hydrophilic and hydrophobic drug substances into a single-dosage preparation for pulmonary delivery using HBCD as an excipient.