Biogenesis of acetylcholinesterase is impaired, although its mRNA level remains normal, in the glucocorticoid-treated rat skeletal muscle

Acetylcholinesterase (AChE) is responsible for the hydrolysis of acetylcholine in the neuromuscular junction and other cholinergic synapses. Insight into the mechanisms controlling AChE expression in skeletal muscle is important for understanding formation, plasticity, and various dysfunctions of the neuromuscular junction. We have investigated the mechanisms responsible for the decreased AChE activity in the fast rat sternomastoideus muscle after chronic glucocorticoid treatment. Under such conditions fast skeletal muscles become atrophic and loose 30-40% of their AChE activity. In order to establish at which level synthesis of AChE is affected by glucocorticoids, we studied the effects of chronic dexamethasone treatment at both AChE mRNA and mature enzyme levels. Reduced rate of AChE recovery after subtotal irreversible AChE inhibition was observed during the first week of dexamethasone treatment, but not later. Statistical analyses of four independent northern blots revealed unchanged AChE mRNA levels. At the same time, we observed more than 60% decrease in the (G1+G2)/A12 ratio of molecular forms at the expense of G forms. It has been generally accepted that globular G1 and G2 molecular forms are synthesized in the rough endoplasmic reticulum as precursors of asymmetric (A) AChE forms, assembled in the Golgi apparatus. Reduced levels of G1 and G2 AChE forms, in combination with unchanged AChE mRNA, are therefore consistent with the reports demonstrating that glucocorticoids downregulate muscle protein synthesis at the translational level. Our findings support but not entirely prove the concept that impaired translation and/or posttranslational control are the primary cause of decreased AChE activity in the glucocorticoid-treated muscle.     

Adherence of Staphylococcus aureus isolated in peritoneal dialysis-related exit-site infections to HEp-2 cells and silicone peritoneal catheter materials

BACKGROUND: Peritoneal catheter exit-site infections cause a relevant morbidity in peritoneal dialysis patients and are frequently caused by Staphylococcus aureus. We tested the hypothesis that adherence of exit-site-derived S. aureus to epithelial cells and peritoneal catheter silicone tubes discriminates virulent and less virulent strains. METHODS: The binding of isolated S. aureus to an epithelial cell line (HEp-2) and to silicone tubes was analyzed using light-microscopy or radioactive labeling of bacteria. RESULTS: Of 378 exit-site swabs, 99 (26%) were positive for microbial growth. S. aureus was cultured in 25 of 99 positive swabs; three of 13 swabs taken in exit-site infections grade 3 and 4 that had tested positive for S. aureus. Adherence of S. aureus from exit-site infections grade 2, 3 and 4 to Hep-2 cells did not differ from adherence of bacteria isolated from asymptomatic or moderately inflamed catheter exit sites (grade 0-2). However, binding of S. aureus to silicone tubes was enhanced in grade 0/1 compared with grade 2-4 exit-site isolates. CONCLUSIONS: Staphylococcus aureus is an important pathogen in CAPD-related exit-site infection being isolated in about 6.6% of all exit-site swabs (and in 25% of all positive swabs). Silicone-adhesive strains may be of more clinical significance in peritoneal dialysis patients since adhesion to silicone was increased in S. aureus strains isolated in more severe exit-site infections.     

Individual-based modelling of growth and migration of Salmonella enteritidis in hens' eggs

An individual-based model (IbM) was developed to describe the growth and migration of Salmonella enteritidis in hens' eggs. The Bacteria Simulator (BacSim) environment was used to implement the model; the bacteria are represented by spheres that grow by nutrient uptake and divide in two daughter cells upon exceeding a certain threshold volume. Motility of the Salmonella bacteria was described by a run and tumble mechanism. For the sake of simplicity, the bacteria were assumed to grow exponentially, an appropriate assumption for the initial phase of growth relevant for shelf-life predictions. Both albumen and yolk were assumed to be homogeneous. The impact of several model parameters (chemotaxis, growth rate, initial contamination numbers and bacterial swimming speed) was assessed by a sensitivity analysis. The results show that chemotaxis towards the yolk would have a strong effect on the time needed to reach the vitelline membrane, an aspect that future research should focus on. The contamination position had less impact on the time to reach the vitelline membrane. The simulation results illustrate the need for more detailed knowledge on the subject of bacterial migration in hens' eggs. Our model can easily incorporate this knowledge when it becomes available.     

Closed‐loop recycling of autoclaved aerated concrete / Geschlossener Recyclingkreislauf für Porenbeton

In einer gemeinsam mit dem Hamburger Entsorgungsunternehmen Otto Dörner GmbH und dem Ytong‐Werk Wedel durchgeführten Pilotstudie überprüft die Xella Technologie‐ und Forschungsgesellschaft seit 2013, wie und in welchen Mengen sich Porenbetonreste aus Abbruchhäusern oder von Deponien für die erneute Porenbetonproduktion wiederverwenden lassen. Hier werden z. B. die Korngrößen oder der Gehalt an Feuchtigkeit, Schwermetallen, Bitumen, Sulfat oder sonstigen Fremd‐ und Störstoffen analysiert. Die Aufbereitung des Altmaterials soll dem derzeitigen technischen Standard entsprechen: Rücknahme von gemischtem Bauschutt, Abtrennung von Fremdstoffen (Metallabscheidung, Windsichtung, Sink‐Schwimm‐Trennung, manuelle Nachsortierung), Vorzerkleinerung im Brecher und Sieben für festgelegte Körnungsbänder. Es zeigte sich, dass die bei Otto Dörner erzielte Sortenreinheit für eine Wiederverwertung durch Rückführung in die Produktion ausreichend ist. Derartig aufbereiteter Altporenbeton kann ohne Mühe zu bis zu 15 % in der Produktion eingesetzt werden. Eine Probeproduktion von Porenbeton der Güteklasse P4‐0,55 mit granuliertem Altporenbeton im Ytong‐Werk Wedel verlief erfolgreich.     

Pattern recognition-based supervision of indirect adaptation for better disturbance handling

An advanced pattern recognition-based supervision algorithm for an indirect adaptive controller is proposed. The aim is to improve performance under certain conditions that are common in the industrial environment, in which indirect adaptive controllers with simple supervision are known to perform poorly or unreliably. Specifically, the problem of large invasive unmeasured disturbances of short or longer duration is addressed. The supervisor is designed to recognize such events as quickly as possible by analysis of recent control signals, without additional measurements. It applies appropriate strategies to prevent model degradation by learning from misleading data and to maintain acceptable performance under unfavorable conditions. As an illustration, it has been applied to the control of a model of a semi-cleanroom HVAC installation subsystem.     

Voltammetric measurements of aminosalicylate drugs using bismuth film electrode

A bismuth film electrode (BiFE) prepared ex-situ on a supporting glassy carbon electrode exhibited convenient electroanalytical performance for voltammetric measurement of selected aminosalycilate drugs. The reduction behaviour of aminosalycilate drugs was studied in aqueous solutions within the pH range of 4–6. The voltammetric responses were compared with those obtained at the bare glassy carbon electrode under identical conditions. In the square-wave voltammetric operation mode the BiFE showed a linear response in the concentration range of 5 × 10⁻⁶ to 3.5 × 10⁻⁴ and 1 × 10⁻⁶ to 5 × 10⁻⁴ M for sulfasalazine and olsalazine, respectively. Its electrode surface revealed auspiciously high stability and remarkable reproducibility in the rapid analysis of aminosalycilate drugs. Finally, the BiFE was satisfactorily applied for direct quantitation of azo prodrugs in real pharmaceutical samples.