Stability of Important Veterinary Antibiotics Amoxicillin, Sulfadiazine, and Trimethoprim in Practice-Relevant Model Solutions.

Due to the frequent use of veterinary drugs in animal husbandry, it is important to know their environmental behavior. In this context, little attention has been paid to the stability of the active ingredients in solutions prepared for administration. This is particularly problematic for antibiotics that trigger resistance when administered subtherapeutically. In order to investigate a possible influence of the preparation and storage of veterinary drugs on compound stability, three widely used antibiotics (amoxicillin, sulfadiazine, trimethoprim) were prepared in different model solutions. Depending on their individual stabilities, the incubation period lasted up to 70 days. Samples were analyzed at regular intervals by high-performance liquid chromatography-diode array detection and ultraviolet spectrophotometry. Following official recommendations, the investigations covered various parameters, e.g., pH, buffer substances, influence of light, and temperature. Sulfadiazine was incubated together with trimethoprim at concentrations of 120 mg L-1 and 80 mg L-1 for 70 days. Both compounds proved to be very stable under all experimental conditions and between 92 and 100% of the active ingredients remained. In 0.1% formic acid, a transformation product was found with less than 5% of the parent substance. In contrast, amoxicillin (500 mg L-1) was instable in almost all solutions under investigation. Within 17 days, the concentration of AMO decreased to 72% in ultrapure water. With the exception of a physiological saline solution, the amount of amoxicillin dropped below 10% or even below the detection limit. Thus, a physiological saline solution is best suited for the storage of dissolved amoxicillin for later administration.

Chitosan-based hybrid immobilization in bienzymatic reactions and its application to the production of laminaribiose.

A hybrid-immobilization method was developed to improve the long-term stability of laminaribiose phosphorylase immobilized on epoxy supports Sepabeads EC-EP/S. Entrapment in chitosan retained all of the enzyme activity depending on the amount of entrapped solid materials and increased half-life by a factor of 10-94.4 h. No enzyme activity loss was determined during 12 times reuse. The immobilization method is also applicable to sucrose phosphorylase immobilized on Sepabeads EC-EP/S. Up to 31.9 g/L laminaribiose were produced in bienzymatic batch experiments with reaction-integrated product separation by adsorption on zeolites.

Immobilization and Characterization of E. gracilis Extract with Enriched Laminaribiose Phosphorylase Activity for Bienzymatic Production of Laminaribiose.

Immobilization methods and carriers were screened for immobilization of Euglena gracilis extract with laminaribiose phosphorylase activity. The extract was successfully immobilized on three different carriers via covalent linkage. Suitable immobilization carriers were Sepabeads EC-EP/S and ECR 8209M with epoxy groups and ECR 8309M with amino groups as functional units. Immobilization on Sepabeads EC-EP/S resulted in highest retained activity (65%). The immobilizates were characterized for pH, temperature, and buffer molarity preferences. The immobilized enzyme lost 48% of its activity when used seven times. Together with sucrose phosphorylase, laminaribiose phosphorylase was successfully applied for bienzymatic production of laminaribiose from sucrose and glucose with a final laminaribiose concentration of 14.3 ± 2.1 g/L (20% yield).

How to choose a seat in theatres: always sit on the right side?

Right seat-side preference in a cinema has been explained by suggesting that it allows for emotional information processing by the right hemisphere (Karev, 2000). In order to determine seat-side preferences, participants in our experiments had to choose seats on cinema, theatre, and restaurant maps. The maps varied with respect to cinema screen, theatre stage, and restaurant entrance positions as viewed by the participants: on top, to the right, to the left, and at the bottom. Seat-side preference was found to be modified by the map's arrangement: With screen, stage, or entrance on top, participants preferred seats to the right of the screen, stage, or entrance, while for the other positions the results were not conclusive. Based on these results it cannot be concluded that the preference for a cinema seat is solely mediated by the preparation for an upcoming event to optimise emotional processing by the right hemisphere. Rather, seat choice seems to be determined by basic behavioural tendencies, such as which side to turn to when entering a room, or by visual attentional orientation.