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The motor protein dynein undergoes coordinated conformational changes of its domains during motility along microtubules. Previous single-molecule studies analyzed the motion of the AAA rings of the dynein homodimer, but not the distal microtubule-binding domains (MTBDs) that step along the track. Here, we simultaneously tracked with nanometer precision two MTBDs and one AAA ring of a single dynein as it underwent hundreds of steps using three-color imaging. We show that the AAA ring and the MTBDs do not always step simultaneously and can take differently sized steps. This variability in the movement between the AAA ring and MTBDs results in an unexpectedly large number of conformational states of dynein during motility. Extracting data on conformational transition biases, we could accurately model dynein stepping in silico. Our results reveal that the flexibility between major dynein domains is critical for dynein motility.

Photobleaching limits extended imaging of fluorescent biological samples. We developed DNA-based 'FluoroCubes' that are similar in size to the green fluorescent protein, have single-point attachment to proteins, have a ~54-fold higher photobleaching lifetime and emit ~43-fold more photons than single organic dyes. We demonstrate that DNA FluoroCubes provide outstanding tools for single-molecule imaging, allowing the tracking of single motor proteins for >800 steps with nanometer precision.

The movement of a molecular motor protein along a cytoskeletal track requires communication between enzymatic, polymer-binding, and mechanical elements. Such communication is particularly complex and not well understood in the dynein motor, an ATPase that is comprised of a ring of six AAA domains, a large mechanical element (linker) spanning over the ring, and a microtubule-binding domain (MTBD) that is separated from the AAA ring by a ~ 135 Å coiled-coil stalk. We identified mutations in the stalk that disrupt directional motion, have microtubule-independent hyperactive ATPase activity, and nucleotide-independent low affinity for microtubules. Cryo-electron microscopy structures of a mutant that uncouples ATPase activity from directional movement reveal that nucleotide-dependent conformational changes occur normally in one-half of the AAA ring, but are disrupted in the other half. The large-scale linker conformational change observed in the wild-type protein is also inhibited, revealing that this conformational change is not required for ATP hydrolysis. These results demonstrate an essential role of the stalk in regulating motor activity and coupling conformational changes across the two halves of the AAA ring.

Light microscopy is a powerful tool for probing the conformations of molecular machines at the single-molecule level. Single-molecule Förster resonance energy transfer can measure intramolecular distance changes of single molecules in the range of 2 to 8 nm. However, current superresolution measurements become error-prone below 25 nm. Thus, new single-molecule methods are needed for measuring distances in the 8- to 25-nm range. Here, we describe methods that utilize information about localization and imaging errors to measure distances between two different color fluorophores with ∼1-nm accuracy at distances >2 nm. These techniques can be implemented in high throughput using a standard total internal reflection fluorescence microscope and open-source software. We applied our two-color localization method to uncover an unexpected ∼4-nm nucleotide-dependent conformational change in the coiled-coil "stalk" of the motor protein dynein. We anticipate that these methods will be useful for high-accuracy distance measurements of single molecules over a wide range of length scales.

Mortality associated with acute trauma remains high, and death rates up to 30% to 40% after pelvic injuries and 20% to 60% with abdominal vascular injuries have been reported even in large tertiary care trauma centers [1],[2]. To address this, we established a quality improvement (QI) process to meet the ACS-COT recommendation on the availability of IR services within 30 min to perform angiography and embolization for trauma patients at our tertiary care academic hospital. For urgent trauma cases, the trauma resident would page the IR resident through the page operator. If any of these indications was present, the trauma team would activate the IR team (attending, resident, nurse, and technologist) and the anesthesia team through a group page. [Extracted from the article]

The authors sought to elucidate factors utilized by medical students over a 2-year period that determine their program application preferences and match rank list development in regard to the integrated interventional radiology (IR) residency. DePietro et al ([2]) studied the factors that medical students found to be most important in the interview process and compared these to what program directors considered to be most important in obtaining residency interviews and successfully matching at a program. [Extracted from the article]

Describes a study using ocular photography to examine factors which affect the visual weights of significant elements in a picture. Results indicating that the upper half of the visual fields has greatest weight are discussed, as are results showing insufficient support for side preferences. Included are 27 references. (Author/BK)

Assesses dietary adequacy in competitive endurance athletes. Measurements of total energy, macronutrient and micronutrient intake of cross-country runners; Timing and composition of pre- and post-training intake; Body composition measures and biochemical indices of protein and energy status.

Objective: To investigate prognostic impact of postoperative complications for colorectal liver metastases (CLM) in the era of RAS mutation analysis. Background: Postoperative complications have been associated with cancer-specific outcomes in multiple malignancies. Methods: We identified 575 patients with known RAS mutation status who underwent hepatic resection for CLM during 2008 to 2014. Postoperative complications were scored with the comprehensive complication index (CCI), and the neutrophil-to-lymphocyte ratio (NLR) was used as an indicator of systemic inflammation before and after surgery. Survival after resection of CLM was stratified by CCI (high, ≥26.2; low, <26.2). Results: Eighty-eight patients had high and 487 low CCI. Recurrence-free survival (RFS) and cancer-specific survival (CSS) after hepatic resection were worse in patients with high CCI than in patients with low CCI (RFS at 3 yrs 26% vs. 41%, P = 0.003; CSS at 5 yrs 46% vs. 64%, P = 0.003). High CCI (odds ratio 3.99, P <0.001) was associated with high NLR (>5) 3 months after hepatic resection. Five factors were associated with worse CSS: high CCI [hazard ratio (HR) 1.61, P = 0.022], primary positive node (HR 1.70, P = 0.003), multiple CLM (HR 1.72, P = 0.001), CLM ≥3 cm (HR 1.73, P <0.001), and mutant RAS (HR 2.04, P <0.001). Receiver operating characteristic and area under receiver operating characteristic curves revealed CCI to be a more sensitive, specific, and accurate predictor of RFS and CSS than NLR. Conclusions: High CCI is a potent predictor of worse RFS and CSS after resection of CLM. The ramifications of postsurgical complications extend beyond direct influence on patient outcomes to impact cancer-related survival. [ABSTRACT FROM AUTHOR]

While it seems likely that a crop production system designed for bioenergy production would differ from one designed for production of grain, there has been little research to validate this. In a study conducted over 2 yr at two Illinois sites, we found that full-season corn (Zea mays L.) both yielded more grain and produced a larger amount of biomass energy (GJ ha-1) than other systems, though the systems in which rye (Secale cereale L.) or wheat (Triticum aestivum L.) harvested as forage or field pennycress (Thlaspi arvense L.) harvested as seed followed by doublecropped corn did not yield significantly less energy; these four corn-based systems produced an average of 351 GJ ha-1 of biomass energy. Winter wheat or rye harvested as forage followed by double-cropped soybean [Glycine max (L.) Merr.] produced 35% less energy that did the corn-based systems, and systems in which wheat was harvested as grain followed by double-cropped soybean produced 38% less energy than the corn-based systems. Systems with canola (Brassica napus L.) or field pennycress harvested for seed followed by double-cropped soybean and fullseason soybean produced an average of only 198 GJ ha-1 or 44% less energy than the corn-based systems. Despite the higher energy content of oil-rich seeds such as canola and pennycress, higher biomass production by corn-based systems leads to higher energy yields, despite the lower energy content of this biomass. [ABSTRACT FROM AUTHOR]