Two-photon imaging of spatially extended neuronal network dynamics with high temporal resolution

We describe a simple two-photon fluorescence imaging strategy, called targeted path scanning (TPS), to monitor the dynamics of spatially extended neuronal networks with high spatiotemporal resolution. Our strategy combines the advantages of mirror-based scanning, minimized dead time, ease of implementation, and compatibility with high-resolution low-magnification objectives. To demonstrate the performance of TPS, we monitor the calcium dynamics distributed across an entire juvenile rat hippocampus (>1.5mm), at scan rates of 100 Hz, with single cell resolution and single action potential sensitivity. Our strategy for fast, efficient two-photon microscopy over spatially extended regions provides a particularly attractive solution for monitoring neuronal population activity in thick tissue, without sacrificing the signal-to-noise ratio or high spatial resolution associated with standard two-photon microscopy. Finally, we provide the code to make our technique generally available.     

Occlusive dressings. Does dressing type influence the growth of common bacterial pathogens?

We studied the effect of different occlusive dressings and of air exposure on the growth of four pathogenic bacteria in wounds. Partial-thickness wounds on domestic pigs were inoculated with Staphylococcus aureus, Clostridium perfringens, Bacteroides fragilis, or Pseudomonas aeruginosa. Each wound was covered with three dressings (DuoDERM, Opsite, or Vigilon), or left exposed to air. Groups of wounds were sampled at 24, 48, and 72 hours. Staphylococcus aureus reached high levels beneath all of the dressings and in the air-exposed wounds. The numbers of C perfringens and B fragilis were greatly reduced in the air-exposed wounds and slightly reduced in the Opsite-covered wounds. The numbers of P aeruginosa were greatest in the Opsite- and Vigilon-covered wounds. The results indicate that occlusive dressings are not indicated in wounds that clinically appear to be grossly contaminated or that may contain anaerobic organisms.     

Assessment of ex vivo pharmacodynamic markers during inhibition of thrombosis by CI-1031 (ZK-807834), a novel direct factor Xa inhibitor.

CI-1031 (ZK-807834) is a novel, synthetic factor Xa (FXa) inhibitor with a Ki of 0.11 nM against human FXa. In human plasma in vitro, CI-1031 doubled PT and aPTT at 0.23 and 0.49 microM, respectively. The in vivo antithrombotic effect of CI-1031 was evaluated in a veno-venous shunt model of thrombosis in anesthetized rabbits. After thrombus formation was verified in the first shunts, rabbits received either vehicle or CI-1031 intravenously (bolus injection of 60, 240, or 480 microg/kg followed by an infusion of 2, 8, or 16 microg/kg/min for 140 min, respectively). The second shunts were inserted after 20 min of infusion of CI-1031 or vehicle. CI-1031 dose-dependently prolonged time to occlusion (TTO) in the second shunts (35 +/- 21, 62 +/- 24, and 120 +/- 0 min for the three dose groups, respectively, vs. 10 +/- 1 min for vehicle). Thrombus mass (TM) was reduced in a dose-dependent manner by CI-1031 (42 +/- 7, 27 +/- 6, and 18 +/- 4 mg vs. 50 +/- 4 mg for vehicle). Maximal TM reduction was 70% with an IC(50) of 0.6 microg/ml. Among all the coagulation parameters tested, PT had the best correlation with plasma CI- 1031 concentration (r = 0.97). Ex vivo plasma anti-FXa activity was also well correlated with plasma concentration of CI-1031 and with PT (r = 0.96 and 0.98, respectively). These results indicate that CI-1031, which is currently undergoing clinical evaluation, is an effective antithrombotic compound with a favorable efficacy-to-bleeding ratio. In addition, CI-1031 concentration in plasma can be monitored using PT or anti-Xa assays, thereby providing reliable methods to ensure safe and accurate dose titration of CI-1031.     

Synthesis and antiarrhythmic activity of cis-2,6-dimethyl-alpha,alpha-diaryl-1-piperidinebutanols

A series of alpha,alpha-diaryl-1-piperidinebutanols was evaluated for antiarrhythmic activity in the coronary ligated dog model. Structure-activity relationship studies indicated that the 2,6-dimethylpiperidine group yielded compounds with the best antiarrhythmic profiles in this series. The length of the methylene chain separating the diarylcarbinol and the amino group was not crucial. Substitution of a hydrogen or a number of functional groups for the hydroxyl group had little effect on efficacy or duration but yielded compounds that produced severe tachycardias. Replacement of one of the aryl groups by hydrogen or a pyridinyl or cyclohexyl group had little effect on efficacy but decreased the duration of action. Compound 18 (pirmenol) was ultimately chosen for further studies and is now being investigated in man.