Ketamine disrupts locomotion and electrolocation in a novel model of schizophrenia, Gnathonemus petersii fish.

The present study aimed to examine a weakly electric fish Gnathonemus petersii (G. petersii) as a candidate model organism of glutamatergic theory of schizophrenia. The idea of G. petersii elevating the modeling of schizophrenia symptoms is based on the fish's electrolocation and electrocommunication abilities. Fish were exposed to the NMDA antagonist ketamine in two distinct series differing in the dose of ketamine. The main finding revealed ketamine-induced disruption of the relationship between electric signaling and behavior indicating impairment of fish navigation. Moreover, lower doses of ketamine significantly increased locomotion and erratic movement and higher doses of ketamine reduced the number of electric organ discharges indicating successful induction of positive schizophrenia-like symptoms and disruption of fish navigation. Additionally, a low dose of haloperidol was used to test the normalization of the positive symptoms to suggest a predictive validity of the model. However, although successfully induced, positive symptoms were not normalized using the low dose of haloperidol; hence, more doses of the typical antipsychotic haloperidol and probably also of a representative of atypical antipsychotic drugs need to be examined to confirm the predictive validity of the model.

The driving factors of per- and polyfluorinated alkyl substance (PFAS) accumulation in selected fish species: The influence of position in river continuum, fish feed composition, and pollutant properties.

Per- and polyfluorinated alkyl substances (PFASs) represent a group of highly recalcitrant micropollutants, that continuously endanger the environment. The present work describes the geographical trends of fish contamination by individual PFASs (including new compounds, e.g., Gen-X) assessed by analyzing the muscle tissues of 5 separate freshwater fish species from 10 locations on the Czech section of the Elbe River and its largest tributary, the Vltava River. The data of this study also showed that the majority of the detected PFASs consisted of long-chain representatives (perfluorooctane sulfonate (PFOS), perfluorononanoic acid, perfluorodecanoic acid, and perfluoroundecanoic acid), whereas short-chain PFASs as well as other compounds such as Gen-X were detected in relatively small quantities. The maximum concentrations of the targeted 32 PFASs in fish were detected in the lower stretches of the Vltava and Elbe Rivers, reaching 289.9 ng/g dw, 140.5 ng/g dw, and 162.7 ng/g dw for chub, roach, and nase, respectively. Moreover, the relationships between the PFAS (PFOS) concentrations in fish muscle tissue and isotopic ratios (δ15N and δ13C) were studied to understand the effect of feed composition and position in the river continuum as a proxy for anthropogenic activity. Redundancy analysis and variation partitioning showed that the largest part of the data variability was explained by the interaction of position in the river continuum and δ15N (δ13C) of the fish. The PFAS concentrations increased downstream and were positively correlated with δ15N and negatively correlated with δ13C. A detailed study at one location also demonstrated the significant relationship between δ15N (estimated trophic position) and PFASs (PFOS) concentrations. From the tested physicochemical properties, the molecular mass and number of fluorine substituents seem to play crucial roles in PFAS bioaccumulation.

STUDY OF DUAL MATRIX TABLETS CONTAINING HYPROMELLOSE OF DIFFERENT VISCOSITY DEGREE AND GLYCERYL DIBEHENATE.

Studies are described on the compressibility of directly compressible tableting materials containing two viscosity types of hypromellose in two concentrations and tableting materials containing additional glyceryl dibehenate, also in two concentrations. Compressibility is evaluated by means of the energy profile of the compression process and determination of tensile strength of tablets. Dissolution test examines the rate of release of the active ingredient from matrix tablets, which is subsequently evaluated mathematically. Increased concentrations of both hypromelloses and an addition of glyceryl dibehenate into tablets with both types of hypromellose improved compressibility. The rate of drug release was decreased with increasing viscosity degree of hypromellose and its increasing concentration. An addition of glyceryl dibehenate exerted the same influence on release as increased concentrations of the pertinent hypromellose.