A systematic survey identifies prions and illuminates sequence features of prionogenic proteins.

Prions are proteins that convert between structurally and functionally distinct states, one or more of which is transmissible. In yeast, this ability allows them to act as non-Mendelian elements of phenotypic inheritance. To further our understanding of prion biology, we conducted a bioinformatic proteome-wide survey for prionogenic proteins in S. cerevisiae, followed by experimental investigations of 100 prion candidates. We found an unexpected amino acid bias in aggregation-prone candidates and discovered that 19 of these could also form prions. At least one of these prion proteins, Mot3, produces a bona fide prion in its natural context that increases population-level phenotypic heterogeneity. The self-perpetuating states of these proteins present a vast source of heritable phenotypic variation that increases the adaptability of yeast populations to diverse environments.

Remote ischemic preconditioning for cardioprotection in elective inpatient abdominal surgery - a randomized controlled trial.

BACKGROUND: Perioperative myocardial injury (PMI) is common in elective inpatient abdominal surgery and correlates with mortality risk. Simple measures for reducing PMI in this cohort are needed. This study evaluated whether remote ischemic preconditioning (RIPC) could reduce PMI in elective inpatient abdominal surgery. METHODS: This was a double-blind, sham-controlled trial with 1:1 parallel randomization. PMI was defined as any post-operative serum troponin T (hs-TNT) > 14 ng/L. Eighty-four participants were randomized to receiving RIPC (5 min of upper arm ischemia followed by 5 min reperfusion, for three cycles) or a sham-treatment immediately prior to surgery. The primary outcome was mean peak post-operative troponin in patients with PMI, and secondary outcomes included mean hs-TnT at individual timepoints, post-operative hs-TnT area under the curve (AUC), cardiovascular events and mortality. Predictors of PMI were also collected. Follow up was to 1 year. RESULTS: PMI was observed in 21% of participants. RIPC did not significantly influence the mean peak post-operative hs-TnT concentration in these patients (RIPC 25.65 ng/L [SD 9.33], sham-RIPC 23.91 [SD 13.2], mean difference 1.73 ng/L, 95% confidence interval - 9.7 to 13.1 ng/L, P = 0.753). The treatment did not influence any secondary outcome with the pre-determined definition of PMI. Redefining PMI as > 5 ng/L in line with recent data revealed a non-significant lower incidence in the RIPC cohort (68% vs 81%, P = 0.211), and significantly lower early hs-TnT release (12 h time-point, RIPC 5.5 ng/L [SD 5.5] vs sham 9.1 ng/L [SD 8.2], P = 0.03). CONCLUSIONS: RIPC did not at reduce the incidence or severity of PMI in these general surgical patients using pre-determined definitions. PMI is nonetheless common and effective cardioprotective strategies are required. TRIAL REGISTRATION: This trial was registered with Clinicaltrials.gov, NCT01850927 , 5th July 2013.

Direct cost analysis of intensive care unit stay in four European countries: applying a standardized costing methodology.

OBJECTIVES: The objective of the present study was to measure and compare the direct costs of intensive care unit (ICU) days at seven ICU departments in Germany, Italy, the Netherlands, and the United Kingdom by means of a standardized costing methodology. METHODS: A retrospective cost analysis of ICU patients was performed from the hospital's perspective. The standardized costing methodology was developed on the basis of the availability of data at the seven ICU departments. It entailed the application of the bottom-up approach for "hotel and nutrition" and the top-down approach for "diagnostics," "consumables," and "labor." RESULTS: Direct costs per ICU day ranged from €1168 to €2025. Even though the distribution of costs varied by cost component, labor was the most important cost driver at all departments. The costs for "labor" amounted to €1629 at department G but were fairly similar at the other departments (€711 ± 115). CONCLUSIONS: Direct costs of ICU days vary widely between the seven departments. Our standardized costing methodology could serve as a valuable instrument to compare actual cost differences, such as those resulting from differences in patient case-mix.

Evolution of an interloop disulfide bond in high-affinity antibody mimics based on fibronectin type III domain and selected by yeast surface display: molecular convergence with single-domain camelid and shark antibodies.

The 10th human fibronectin type III domain ((10)Fn3) is one of several protein scaffolds used to design and select families of proteins that bind with high affinity and specificity to macromolecular targets. To date, the highest affinity (10)Fn3 variants have been selected by mRNA display of libraries generated by randomizing all three complementarity-determining region -like loops of the (10)Fn3 scaffold. The sub-nanomolar affinities of such antibody mimics have been attributed to the extremely large size of the library accessible by mRNA display (10(12) unique sequences). Here we describe the selection and affinity maturation of (10)Fn3-based antibody mimics with dissociation constants as low as 350 pM selected from significantly smaller libraries (10(7)-10(9) different sequences), which were constructed by randomizing only 14 (10)Fn3 residues. The finding that two adjacent loops in human (10)Fn3 provide a large enough variable surface area to select high-affinity antibody mimics is significant because a smaller deviation from wild-type (10)Fn3 sequence is associated with a higher stability of selected antibody mimics. Our results also demonstrate the utility of an affinity-maturation strategy that led to a 340-fold improvement in affinity by maximizing sampling of sequence space close to the original selected antibody mimic. A striking feature of the highest affinity antibody mimics selected against lysozyme is a pair of cysteines on adjacent loops, in positions 28 and 77, which are critical for the affinity of the (10)Fn3 variant for its target and are close enough to form a disulfide bond. The selection of this cysteine pair is structurally analogous to the natural evolution of disulfide bonds found in new antigen receptors of cartilaginous fish and in camelid heavy-chain variable domains. We propose that future library designs incorporating such an interloop disulfide will further facilitate the selection of high-affinity, highly stable antibody mimics from libraries accessible to phage and yeast surface display methods.

Sedation practice in the intensive care unit: a UK national survey.

INTRODUCTION: The purpose of this study was to evaluate sedation practice in UK intensive care units (ICUs), particularly the implementation of daily sedation holding, written sedation guidelines, sedation scoring tools and choice of agents. METHODS: A national postal survey was conducted in all UK ICUs. RESULTS: A total of 192 responses out of 302 addressed units were received (63.5%). Of the responding ICUs, 88% used a sedation scoring tool, most frequently the Ramsey Sedation Scale score (66.4%). The majority of units have a written sedation guideline (80%), and 78% state that daily sedation holding is practiced. A wide variety of sedating agents is used, with the choice of agent largely determined by the duration of action rather than cost. The most frequently used agents were propofol and alfentanil for short-term sedation; propofol, midazolam and morphine for longer sedation; and propofol for weaning purposes. CONCLUSIONS: Most UK ICUs use a sedation guideline and sedation scoring tool. The concept of sedation holding has been implemented in the majority of units, and most ICUs have a written sedation guideline.

"Wet diapers--dry patients": an effective dressing for patients undergoing arthroscopic shoulder surgery.

Shoulder arthroscopy is very commonly associated with postoperative leakage of irrigation fluid. This causes apprehension to patients and their relatives and leads to frequent change of dressings. We describe a simple and effective diaper dressing for patients undergoing arthroscopic shoulder surgery. It is highly absorbent, cost-effective, and easy to apply. We have used this dressing successfully in more than 1,500 shoulder arthroscopies over the last 3 years with no adverse reaction.

Tracheal ring fracture and early tracheomalacia following percutaneous dilatational tracheostomy.

BACKGROUND: Percutaneous dilatational tracheostomy (PDT) is increasingly popular within intensive care units for patients who need prolonged ventilatory support. Significant complications are rare. CASE PRESENTATION: Our patient suffered tracheal ring fracture and early tracheomalacia following this procedure. These complications are demonstrated in our accompanying video. CONCLUSION: Contrary to common beliefs, tracheal rings are commonly fractured during the PDT procedure. The consequent granulation can lead to tracheal stenosis and tracheomalacia.

Reliability of diagnostic criteria for bronchiolitis obliterans syndrome after lung transplantation: a survey.

BACKGROUND: Long-term outcomes after lung transplantation are limited due to chronic lung allograft dysfunction (CLAD). Bronchiolitis obliterans syndrome (BOS) is the most common form of obstructive CLAD and its definition derives from spirometric measurements. Given the importance of this diagnosis, both the accuracy and reliability of the definition of CLAD are crucial in understanding the pathophysiology of this disease to develop therapeutic options and influence outcome after lung transplantation. METHODS: A web-based survey was designed and distributed to members of the Pulmonary Council of the International Society for Heart and Lung Transplantation (ISHLT) to better understand the accuracy and reliability of pulmonary function criteria in diagnosing BOS. Spirometric data from five patient scenarios that were discordant among reviewers regarding BOS determination from the Assessment of Immunosuppressive Regimen in Suppressing Acute and Chronic Rejection (AIRSAC) trial were randomly selected and summarized in this survey. Survey questions included the respondent's general understanding of the BOS definition, the determination of BOS, and difficulties with the current BOS definition. RESULTS: Eighty-seven respondents from the Pulmonary Council of the ISHLT responded to this survey. There was an overall 70% interobserver agreement regarding the presence or absence of BOS. Among those who agreed upon the presence of BOS, there was a 41% interobserver agreement regarding its time of onset. Despite this variability, the majority of respondents were not only familiar and agreed with the BOS criteria, they also felt confident in applying these criteria. CONCLUSIONS: Our survey identified potential limitations with the current criteria for diagnosing BOS. With recognition of the various CLAD phenotypes, further refinements of these diagnostic criteria will allow for an improved ability to identify and characterize patients who develop or are at risk for BOS, prognosticate outcomes, and, most importantly, marshal in future strategies directed at treating and preventing chronic lung dysfunction after lung transplantation.

Picomolar affinity fibronectin domains engineered utilizing loop length diversity, recursive mutagenesis, and loop shuffling.

The 10th type III domain of human fibronectin (Fn3) has been validated as an effective scaffold for molecular recognition. In the current work, it was desired to improve the robustness of selection of stable, high-affinity Fn3 domains. A yeast surface display library of Fn3 was created in which three solvent-exposed loops were diversified in terms of amino acid composition and loop length. The library was screened by fluorescence-activated cell sorting to isolate binders to lysozyme. An affinity maturation scheme was developed to rapidly and broadly diversify populations of clones by random mutagenesis as well as homologous recombination-driven shuffling of mutagenized loops. The novel library and affinity maturation scheme combined to yield stable, monomeric Fn3 domains with 3 pM affinity for lysozyme. A secondary affinity maturation identified a stable 1.1 pM binder, the highest affinity yet reported for an Fn3 domain. In addition to extension of the affinity limit for this scaffold, the results demonstrate the ability to achieve high-affinity binding while preserving stability and the monomeric state. This library design and affinity maturation scheme is highly efficient, utilizing an initial diversity of 2x10(7) clones and screening only 1x10(8) mutants (totaled over all affinity maturation libraries). Analysis of intermediate populations revealed that loop length diversity, loop shuffling, and recursive mutagenesis of diverse populations are all critical components.