Geometry Matters for Cargos Navigating 3D Microtubule Intersections

Eukaryotic cells transport cargos along microtubules to control their distribution within the cell and deliver them to distant locations. While we understand how molecular motors can transport cargos along individual microtubules, the cell's microtubules are usually arranged in a complex 3D network. While traversing this network, cargos need to navigate intersections where microtubules cross at a wide variety of separation distances and angles. To gain insight into how cargos navigate these intersections, we have used a recently established 3D construction technique based on holographic optical trapping to build single 3D microtubule intersections in vitro with relevant nanoscale precision. We then used these fully suspended microtubule structures to perform motility assays on kinesin-1 coated cargos. We find that some intersection geometries influence cargos to pass along their current microtubule, while other geometries influence them to switch to the intersecting one. To understand how, we use a 3D Brownian dynamics simulation of cargo transport to investigate the mechanisms which give rise to the observed switching probabilities. Using these stochastic simulations, we find that switching probability is often determined by a competition between a stronger motor team on the primary microtubule and the intersecting microtubule sterically hindering that team's progress. This understanding of the basic mechanisms of switching at single intersections in 3D helps lay a foundation for understanding how the cell may regulate switching to control how cargos navigate the MT network and ultimately their spatial organization

Fracture of a Tempofilter II: an Initial Case Report

Tempofilter II is a device that is used for pulmonary embolism prophylaxis. Since the appearance of the Tempofilter II following withdrawal of the Tempofilter I, it has been reported that the Tempofilter II is safe, effective and useful. Here we report on the first case of a fracture of one leg of the filter and this leg was embedded in the inferior vena cava wall in a 62-year-old man with deep vein thrombosis

Methane and Nitrogen Abundances On Pluto and Eris

We present spectra of Eris from the MMT 6.5 meter telescope and Red Channel Spectrograph (5700-9800 angstroms; 5 angstroms per pix) on Mt. Hopkins, AZ, and of Pluto from the Steward Observatory 2.3 meter telescope and Boller and Chivens spectrograph (7100-9400 angstroms; 2 angstroms per pix) on Kitt Peak, AZ. In addition, we present laboratory transmission spectra of methane-nitrogen and methane-argon ice mixtures. By anchoring our analysis in methane and nitrogen solubilities in one another as expressed in the phase diagram of Prokhvatilov and Yantsevich (1983), and comparing methane bands in our Eris and Pluto spectra and methane bands in our laboratory spectra of methane and nitrogen ice mixtures, we find Eris' bulk methane and nitrogen abundances are about 10% and about 90%, and Pluto's bulk methane and nitrogen abundances are about 3% and about 97%. Such abundances for Pluto are consistent with values reported in the literature. It appears that the bulk volatile composition of Eris is similar to the bulk volatile composition of Pluto. Both objects appear to be dominated by nitrogen ice. Our analysis also suggests, unlike previous work reported in the literature, that the methane and nitrogen stoichiometry is constant with depth into the surface of Eris. Finally, we point out that our Eris spectrum is also consistent with a laboratory ice mixture consisting of 40% methane and 60% argon. Although we cannot rule out an argon rich surface, it seems more likely that nitrogen is the dominant species on Eris because the nitrogen ice 2.15 micron band is seen in spectra of Pluto and Triton.Comment: The manuscript has 44 pages, 15 figures, and four tables. It will appear in the Astrophysical Journa

Retrograde Tempofilter II™ Placement within the Superior Vena Cava in a Patient with Acute Upper Extremity Deep Venous Thrombosis: the Filter Stands on Its Head

The Tempofilter II is a widely used temporary vena cava filter. Its unique design, which includes a long tethering catheter with a subcutaneous anchor, facilitates the deployment and retrieval of the device. Despite this, the Tempofilter II has been used only in the inferior vena cava of patients with lower extremity deep venous thrombosis. In this article, we present a case of superior vena cava filtering using the Tempofilter II in patients with upper extremity deep venous thrombosis

Remote Sensing D/H Ratios in Methane Ice: Temperature-Dependent Absorption Coefficients of CH3D in Methane Ice and in Nitrogen Ice

The existence of strong absorption bands of singly deuterated methane (CH3D) at wavelengths where normal methane (CH4) absorbs comparatively weakly could enable remote measurement of D/H ratios in methane ice on outer solar system bodies. We performed laboratory transmission spectroscopy experiments, recording spectra at wavelengths from 1 to 6 \mum to study CH3D bands at 2.47, 2.87, and 4.56 \mum, wavelengths where ordinary methane absorption is weak. We report temperature-dependent absorption coefficients of these bands when the CH3D is diluted in CH4 ice and also when it is dissolved in N2 ice, and describe how these absorption coefficients can be combined with data from the literature to simulate arbitrary D/H ratio absorption coefficients for CH4 ice and for CH4 in N2 ice. We anticipate these results motivating new telescopic observations to measure D/H ratios in CH4 ice on Triton, Pluto, Eris, and Makemake.Comment: 17 pages, 7 figure

Complications related to deep venous thrombosis prophylaxis in trauma: a systematic review of the literature

Deep venous thrombosis prophylaxis is essential to the appropriate management of multisystem trauma patients. Without thromboprophylaxis, the rate of venous thrombosis and subsequent pulmonary embolism is substantial. Three prophylactic modalities are common: pharmacologic anticoagulation, mechanical compression devices, and inferior vena cava filtration. A systematic review was completed using PRISMA guidelines to evaluate the potential complications of DVT prophylactic options. Level one evidence currently supports the use of low molecular weight heparins for thromboprophylaxis in the trauma patient. Unfortunately, multiple techniques are not infrequently required for complex multisystem trauma patients. Each modality has potential complications. The risks of heparin include bleeding and heparin induced thrombocytopenia. Mechanical compression devices can result in local soft tissue injury, bleeding and patient non-compliance. Inferior vena cava filters migrate, cause inferior vena cava occlusion, and penetrate the vessel wall. While the use of these techniques can be life saving, they must be appropriately utilized