Crystal structure of nucleotide-free dynamin

Dynamin is a mechanochemical GTPase that oligomerizes around the neck of clathrin-coated pits and catalyses vesicle scission in a GTP-hydrolysis-dependent manner. The molecular details of oligomerization and the mechanism of the mechanochemical coupling are currently unknown. Here we present the crystal structure of human dynamin 1 in the nucleotide-free state with a four-domain architecture comprising the GTPase domain, the bundle signalling element, the stalk and the pleckstrin homology domain. Dynamin 1 oligomerized in the crystals via the stalks, which assemble in a criss-cross fashion. The stalks further interact via conserved surfaces with the pleckstrin homology domain and the bundle signalling element of the neighbouring dynamin molecule. This intricate domain interaction rationalizes a number of disease-related mutations in dynamin 2 and suggests a structural model for the mechanochemical coupling that reconciles previous models of dynamin function

Electro-optic modulation of 1.5μm light in an active InGaAsP/InP quantum well waveguide

We report an InGaAsP/InP phase modulator operating in the 1.5μm wavelength band. Phase modulation of 7.5°/mA and 1.7°/mA of injected current have been measured for TE and TM polarised light respectively at a signal wavelength of 1.52 μm

An Evaluation of Emergency Medical Services Stroke Protocols and Scene Times

BACKGROUND: Acute stroke patients require immediate medical attention. Therefore, American Stroke Association guidelines recommend that for suspected stroke cases, emergency medical services (EMS) personnel spend less than 15 minutes (min) on-scene at least 90% of the time. However, not all EMS providers include specific scene time limits in their stroke patient care protocols. OBJECTIVE: We sought to determine whether having a protocol with a specific scene time limit was associated with less time EMS spent on scene. METHODS: Stroke protocols from the 100 EMS systems in North Carolina (NC) were collected and abstracted for scene time instructions. Suspected stroke events occurring in 2009 were analyzed using data from the NC Prehospital Medical Information System. Scene time was defined as the time from EMS arrival at the scene to departure with the patient. Quantile regression was used to estimate how the 90(th) percentile of the scene time distribution varied by systems with protocol instructions limiting scene time, adjusting for system patient volume and metropolitan status. RESULTS: In 2009, 23 EMS systems in NC had no instructions regarding scene time; 73 had general instructions to minimize scene time; and 4 had a specific limit for scene time (i.e. 10 or 15 min). Among 9,723 eligible suspected stroke events, mean scene time was 15.9 min (standard deviation 6.9 min) and median scene time was 15.0 min (90th percentile 24.3 min). In adjusted quantile regression models, the estimated reduction in the 90(th) percentile scene time, comparing protocols with a specific time limit to no instructions, was 2.2 min (95% confidence interval 1.3, 3.1 min). The difference in 90(th) percentile scene time between general and absent instructions was not statistically different (0.7 min (95% confidence interval -0.1, 1.4 min)). CONCLUSION: Protocols with specific scene time limits were associated with EMS crews spending less time at the scene while general instructions were not. These findings suggest EMS systems can modestly improve scene times for stroke by specifying a time limit in their protocols