Ultrasound-guided subsartorial saphenous nerve block is commonly used to provide complete surgical anesthesia of the foot and ankle in combination with a popliteal sciatic nerve block. However, in ...part owing to its small caliber and absence of a prominent vascular landmark in the subsartorial plane distal to the adductor canal, the saphenous nerve is more difficult to reliably block than the sciatic nerve in the popliteal fossa. Although the saphenous nerve is a sensory nerve only, neurostimulation can be used to elicit a "tapping" sensation on the anteromedial aspect of the lower leg extending toward the medial malleolus. Our objective was to test the hypothesis that the addition of nerve stimulation use to an ultrasound (US)-guided technique will increase the success rate of subsartorial saphenous nerve block.
With institutional human ethics board approval and participants' written informed consent, we enrolled 80 patients undergoing foot and ankle surgery in a randomized, single-blinded, parallel-group clinical trial. Patients were randomly assigned to receive US-guided subsartorial saphenous nerve block either alone (US group) or with the use of additional nerve stimulation (NS group; time limit, 5 minutes). For saphenous nerve blockade, all patients received 10 mL of 0.5% ropivacaine. The primary end point was complete absence of sensation to pinprick at 30 minutes at two different anatomic areas in the distribution of the saphenous nerve (2 cm proximal to the medial malleolus and 10 cm distal to the medial tibial condyle). Secondary end points included decreased sensation at 30 minutes and block failure (normal sensation) at 30 minutes. This trial was registered at ClinicalTrials.gov: NCT02382744.
All 80 patients completed the trial (40 patients in each group). Twenty-two patients (55%) in the NS group versus 18 (45%) in the US group had complete absence of sensation to pinprick at 30 minutes at both anatomic areas of assessment (Fisher exact test, P = 0.25 one sided; 95% confidence interval of difference in proportions, -11.9% to 31.9%). The percentages of patients with any evidence of block (decreased or complete absence of sensation) at both areas at 30 minutes were 92.5% (NS) and 97.5% (US), respectively (P = 0.62 two sided); corresponding failure rates (normal sensation) were 7.5% (NS) and 2.5% (US). In the NS group, no response in the saphenous nerve distribution was elicited within 5 minutes of stimulation time limit in 20% of patients (n = 8). All of the patients in the NS group with normal sensation at 30 minutes (n = 3) were among this subcohort.
The addition of the use of nerve stimulation did not improve the success rate of US-guided subsartorial saphenous nerve block. However, in the NS group, an inability to elicit a "tapping" sensation in the saphenous nerve distribution was associated with block failure.
TRPV5 is a transient receptor potential channel involved in calcium reabsorption. Here we investigate the interaction of two endogenous modulators with TRPV5. Both phosphatidylinositol ...4,5-bisphosphate (PI(4,5)P
) and calmodulin (CaM) have been shown to directly bind to TRPV5 and activate or inactivate the channel, respectively. Using cryo-electron microscopy (cryo-EM), we determined TRPV5 structures in the presence of dioctanoyl PI(4,5)P
and CaM. The PI(4,5)P
structure reveals a binding site between the N-linker, S4-S5 linker and S6 helix of TRPV5. These interactions with PI(4,5)P
induce conformational rearrangements in the lower gate, opening the channel. The CaM structure reveals two TRPV5 C-terminal peptides anchoring a single CaM molecule and that calcium inhibition is mediated through a cation-π interaction between Lys116 on the C-lobe of calcium-activated CaM and Trp583 at the intracellular gate of TRPV5. Overall, this investigation provides insight into the endogenous modulation of TRPV5, which has the potential to guide drug discovery.
Mutations in human SOX9 are associated with campomelic dysplasia (CD), characterised by skeletal malformation and XY sex reversal. During chondrogenesis in the mouse, Sox9 is co-expressed with ...Col2a1, the gene encoding type-II collagen, the major cartilage matrix protein. Col2a1 is therefore a candidate regulatory target of SOX9. Regulatory sequences required for chondrocyte-specific expression of the type-II collagen gene have been localized to conserved sequences in the first intron in rats, mice and humans. We show here that SOX9 protein binds specifically to sequences in the first intron of human COL2A1. Mutation of these sequences abolishes SOX9 binding and chondrocyte-specific expression of a COL2A1-driven reporter gene (COL2A1-lacZ) in transgenic mice. Furthermore, ectopic expression of Sox9 trans-activates both a COL2A1-driven reporter gene and the endogenous Col2a1 gene in transgenic mice. These results demonstrate that COL2A1 expression is directly regulated by SOX9 protein in vivo and implicate abnormal regulation of COL2A1 during, chondrogenesis as a cause of the skeletal abnormalities associated with campomelic dysplasia.
To examine, in the Veterans Health Administration (VHA), the relation between surgical volume and outcome in eight commonly performed operations of intermediate complexity.
In multihospital health ...care systems such as VHA, consideration is often given to closing low-volume surgical services, with the assumption that better surgical outcomes are achieved in hospitals with larger surgical volumes. Literature data to support this assumption in intermediate-complexity operations are either limited or controversial.
The VHA National Surgical Quality Improvement Program data on nonruptured abdominal aortic aneurysmectomy, vascular infrainguinal reconstruction, carotid endarterectomy (CEA), lung lobectomy/pneumonectomy, open and laparoscopic cholecystectomy, partial colectomy, and total hip arthroplasty were used. Pearson correlation, analysis of variance, mixed effects hierarchical logistic regression, and automatic interaction detection analysis were used to assess the association of annual procedure/specialty volume with risk-adjusted 30-day death (and stroke in CEA).
Eight major surgical procedures (68,631 operations) were analyzed. No statistically significant associations between procedure or specialty volume and 30-day mortality rate (or 30-day stroke rate in CEA) were found.
In VHA hospitals, the procedure and surgical specialty volume in eight prevalent operations of intermediate complexity are not associated with risk-adjusted 30-day mortality rate from these operations, or with the risk-adjusted 30-day stroke rate from CEA. Volume of surgery in these operations should not be used as a surrogate for quality of surgical care.
From late‐summer 2013 to late‐summer 2014, a total of 20 moorings were maintained on the eastern Chukchi Sea shelf as part of five independent field programs. This provided the opportunity to analyze ...an extensive set of timeseries to obtain a broad view of the mean and seasonally varying hydrography and circulation over the course of the year. Year‐long mean bottom temperatures reflected the presence of the strong coastal circulation pathway, while mean bottom salinities were influenced by polynya/lead activity along the coast. The timing of the warm water appearance in spring/summer is linked to advection along the various flow pathways. The timing of the cold water appearance in fall/winter was not reflective of advection nor related to the time of freeze‐up. Near the latitude of Barrow Canyon, the cold water was accompanied by freshening. A one‐dimensional mixed‐layer model demonstrates that wind mixing, due to synoptic storms, overturns the water column resulting in the appearance of the cold water. The loitering pack ice in the region, together with warm southerly winds, melted ice and provided an intermittent source of fresh water that was mixed to depth according to the model. Farther north, the ambient stratification prohibits wind‐driven overturning, hence the cold water arrives from the south. The circulation during the warm and cold months of the year is different in both strength and pattern. Our study highlights the multitude of factors involved in setting the seasonal cycle of hydrography and circulation on the Chukchi shelf.
Plain Language Summary
From late‐summer 2013 to 2014, a total of 20 moorings were maintained on the eastern Chukchi Sea shelf, north of Bering Strait, as part of five independent field programs. We analyze these data to obtain a broad view of the mean water conditions and circulation, as well as the dominant variability over the course of the year. The year‐long mean bottom temperatures reflected the presence of the strong current adjacent to the Alaskan coast, while the mean bottom salinities were influenced by the frequent presence of persistent openings in the sea ice, which result in the formation of salty water when the ice re‐freezes. The appearance of warm water across the shelf in spring/summer was mainly dictated by the speed of the water from south to north. However, the appearance of cold water in fall/winter was not reflective of this. Using a simple model, it is demonstrated that storm events mixed cold and fresh surface water to the bottom on the mid‐shelf. Farther to the northeast, this does not happen because the water is more stratified, and this prohibits such wind mixing. Finally, it is shown that the circulation during the warm and cold months of the year is different in both strength and pattern.
Key Points
The appearance of warm water across the Chukchi shelf in spring is dictated by advection, but the appearance of cold water in the fall is not
Wind mixing from autumn storms brings cold, fresh water to depth on the mid‐shelf, but strong stratification prohibits this farther north
The circulation during the warm and cold months of the year is different in both strength and pattern
A fast-switching, high-repetition-rate magnet and power supply have been developed for and operated at TRIUMF, to deliver a proton beam to the new ultracold neutron (UCN) facility. The facility ...possesses unique operational requirements: a time-averaged beam current of40μAwith the ability to switch the beam on or off for several minutes. These requirements are in conflict with the typical operation mode of the TRIUMF cyclotron which delivers nearly continuous beam to multiple users. To enable the creation of the UCN facility, a beam-sharing arrangement with another facility was made. The beam sharing is accomplished by the fast-switching (kicker) magnet which is ramped in50μsto a current of 193 A, held there for approximately 1 ms, then ramped down in the same short period of time. This achieves a 12 mrad deflection which is sufficient to switch the proton beam between the two facilities. The kicker magnet relies on a high-current, low-inductance coil connected to a fast-switching power supply that is based on insulated-gate bipolar transistors (IGBTs). The design and performance of the kicker magnet system and initial beam delivery results are reported.
Abstract
We report the discovery of an unusual stellar system SMSS J130522.47−293113.0. The optical spectrum is dominated by a blue continuum together with emission lines of hydrogen, neutral, and ...ionized helium, and the N iii, C iii blend at ∼4640–4650 Å. The emission-line profiles vary in strength and position on time-scales as short as 1 d, while optical photometry reveals fluctuations of as much as ∼0.2 mag in g on time-scales as short as 10–15 min. The system is a weak X-ray source (f0.3–10 = (1.2 ± 0.1) × 10−13 ergs cm2 s−1 in the 0.3–10 keV band) but is not detected at radio wavelengths (3σ upper limit of 50 $\mu$Jy at 5.5 GHz). The most intriguing property of the system, however, is the existence of two ‘blobs’, a few arcsec in size, that are symmetrically located 3${^{\prime}_{.}}$8 (2.2 pc for our preferred system distance of ∼2 kpc) each side of the central object. The blobs are detected in optical and near-IR broad-band images but do not show any excess emission in H α images. We discuss the interpretation of the system, suggesting that the central object is most likely a nova-like CV, and that the blobs are relics of a pc-scale accretion-powered collimated outflow.
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