Shifting Perspectives: Equal Blunt Cerebrovascular Risk in Low-Versus High-Energy Cervical Fracture.

INTRODUCTION: Clinical implications of screening for blunt cerebrovascular injury (BCVI) after low-energy mechanisms of injury (LEMI) remain unclear. We assessed BCVI incidence and outcomes in LEMI versus high-energy mechanisms of injury (HEMI) patients. METHODS: In this retrospective cohort study, blunt trauma adults admitted between July 2015 and June 2021 with cervical spine fractures, excluding single spinous process, osteophyte, and chronic fractures were included. Demographics, comorbidities, injuries, screening and treatment data, iatrogenic complications, and mortality were collected. Our primary end point was to compare BCVI rates between LEMI and HEMI patients. RESULTS: Eight hundred sixty patients (78%) were screened for BCVI; 120 were positive for BCVI. LEMI and HEMI groups presented similar BCVI rates (12.6% versus 14.4%; P = 0.640). Compared to HEMI patients (n = 95), LEMI patients (n = 25) were significantly older (79 ± 14.9 versus 54.3 ± 17.4, P < 0.001), more likely to be on anticoagulants before admission (64% versus 23.2%, P < 0.001), and less severely injured (LEMI injury severity score 10.9 ± 6.6 versus HEMI injury severity score 18.7 ± 11.4, P = 0.001). All but one LEMI and 90.5% of the HEMI patients had vertebral artery injuries with no significant difference in BCVI grades. One HEMI patient developed acute kidney injury because of BCVI screening. Eleven HEMI patients developed BCVI-related stroke with two related mortalities. One LEMI patient died of a BCVI-related stroke. CONCLUSIONS: BCVI rates were similar between HEMI and LEMI groups when screening based on cervical spine fractures. The LEMI group exhibited no screening or treatment complications, suggesting that benefits may outweigh the risks of screening and potential bleeding complications from treatment.

Membrane topology and identification of critical amino acid residues in the Wzx O-antigen translocase from Escherichia coli O157:H4.

Wzx belongs to a family of membrane proteins involved in the translocation of isoprenoid lipid-linked glycans, which is loosely related to members of the major facilitator superfamily. Despite Wzx homologs performing a conserved function, it has been difficult to pinpoint specific motifs of functional significance in their amino acid sequences. Here, we elucidate the topology of the Escherichia coli O157 Wzx (Wzx(EcO157)) by a combination of bioinformatics and substituted cysteine scanning mutagenesis, as well as targeted deletion-fusions to green fluorescent protein and alkaline phosphatase. We conclude that Wzx(EcO157) consists of 12 transmembrane (TM) helices and six periplasmic and five cytosolic loops, with N and C termini facing the cytoplasm. Four TM helices (II, IV, X, and XI) contain polar residues (aspartic acid or lysine), and they may form part of a relatively hydrophilic core. Thirty-five amino acid replacements to alanine or serine were targeted to five native cysteines and most of the aspartic acid, arginine, and lysine residues. From these, only replacements of aspartic acid-85, aspartic acid-326, arginine-298, and lysine-419 resulted in a protein unable to support O-antigen production. Aspartic acid-85 and lysine-419 are located in TM helices II and XI, while arginine-298 and aspartic acid-326 are located in periplasmic and cytosolic loops 4, respectively. Further analysis revealed that the charge at these positions is required for Wzx function since conservative substitutions maintaining the same charge polarity resulted in a functional protein, whereas those reversing or eliminating polarity abolished function. We propose that the functional requirement of charged residues at both sides of the membrane and in two TM helices could be important to allow the passage of the Und-PP-linked saccharide substrate across the membrane.

Diacylglycerol kinase epsilon is selective for both acyl chains of phosphatidic acid or diacylglycerol.

The phosphatidylinositol (PI) cycle mediates many cellular events by controlling the metabolism of many lipid second messengers. Diacylglycerol kinase epsilon (DGK epsilon) has an important role in this cycle. DGK epsilon is the only DGK isoform to show inhibition by its product phosphatidic acid (PA) as well as substrate specificity for sn-2 arachidonoyl-diacylglycerol (DAG). Here, we show that this inhibition and substrate specificity are both determined by selectivity for a combination of the sn-1 and sn-2 acyl chains of PA or DAG, respectively, preferring the most prevalent acyl chain composition of lipids involved specifically in the PI cycle, 1-stearoyl-2-arachidonoyl. Although the difference in rate for closely related lipid species is small, there is a significant enrichment of 1-stearoyl-2-arachidonoyl PI because of the cyclical nature of PI turnover. We also show that the inhibition of DGK epsilon by PA is competitive and that the deletion of the hydrophobic segment and cationic cluster of DGK epsilon does not affect its selectivity for the acyl chains of PA or DAG. Thus, this active site not only recognizes the lipid headgroup but also a combination of the two acyl chains in PA or DAG. We propose a mechanism of DGK epsilon regulation where its dual acyl chain selectivity is used to negatively regulate its enzymatic activity in a manner that ensures DGK epsilon remains committed to the PI turnover cycle. This novel mechanism of enzyme regulation within a signaling pathway could serve as a template for the regulation of enzymes in other pathways in the cell.

Functional analysis of predicted coiled-coil regions in the Escherichia coli K-12 O-antigen polysaccharide chain length determinant Wzz.

Wzz is a membrane protein that determines the chain length distribution of the O-antigen lipopolysaccharide by an unknown mechanism. Wzz proteins consist of two transmembrane helices separated by a large periplasmic loop. The periplasmic loop of Escherichia coli K-12 Wzz (244 amino acids from K65 to A308) was purified and found to be a monomer with an extended conformation, as determined by gel filtration chromatography and analytical ultracentrifugation. Circular dichroism showed that the loop has a 60% helical content. The Wzz periplasmic loop also contains three regions with predicted coiled coils. To probe the function of the predicted coiled coils, we constructed amino acid replacement mutants of the E. coli K-12 Wzz protein, which were designed so that the coiled coils could be separate without compromising the helicity of the individual molecules. Mutations in one of the regions, spanning amino acids 108 to 130 (region I), were associated with a partial defect in O-antigen chain length distribution, while mutants with mutations in the region spanning amino acids 209 to 223 (region III) did not have an apparent functional defect. In contrast, mutations in the region spanning amino acids 153 to 173 (region II) eliminated the Wzz function. This phenotype was associated with protein instability, most likely due to conformational changes caused by the amino acid replacements, which was confirmed by limited trypsin proteolysis. Additional mutagenesis based on a three-dimensional model of region I demonstrated that the amino acids implicated in function are all located at the same face of a predicted alpha-helix, suggesting that a coiled coil actually does not exist in this region. Together, our results suggest that the regions predicted to be coiled coils are important for Wzz function because they maintain the native conformation of the protein, although the existence of coiled coils could not be demonstrated experimentally.

General principles of asthma management: symptom monitoring.

The first step in optimal asthma care is identifying and properly diagnosing patients who have asthma then classifying asthma severity carefully and accurately to ensure proper treatment. Objective monitoring of pulmonary function using spirometry and peak flow monitoring, subjective assessment using symptom identification, and physicians' acceptance of National Asthma Education Program's Expert Panel guidelines are needed to diminish the consequences of undertreatment of asthma. Persistent asthma requires continuous long-term controller therapy. Erratic and insufficient use of medication must be addressed. Clinicians should encourage patients to manage their asthma using routine peak flow monitoring and symptom assessment then intervene according to their asthma action plan. These efforts allow patients to take charge of their asthma instead of the asthma taking charge of them.

Planning and resource allocation in NHS colleges of health studies: 2.

In the second of two articles on the funding of nurse education, the strengths and weaknesses of current funding arrangements for nurse education are explored. The highly regulated health education market is examined and an analysis is offered on the degree to which colleges are able to plan effectively in a competitive and highly unstable market place.

A prospective study on esophageal Doppler hemodynamic assessment in the ED.

We sought to determine whether physicians' estimates of critically ill patients' hemodynamics are accurate as compared with esophageal Doppler probe (EDP) measurements and whether provision of measured hemodynamic profiles produces treatment changes and changes in physician confidence. At an urban county ED, we enrolled 55 critically ill adults with pulmonary edema of unclear etiology, sustained hypotension, or lactic acidosis. Physicians estimated cardiac output (CO) and systemic vascular resistance (SVR), categorized shock, stated treatment plans, and rated confidence in assessment and treatment plans. Physicians were informed of EDP hemodynamic measurements (CO, SVR, stroke volume, and contractility), and they repeated their assessments and plans. Weighted kappa values between physician estimates and EDP measurements of CO and SVR were 0.57 (95% confidence interval [CI] = 0.77-0.36) and 0.40 (95% CI = 0.64-0.16), respectively. Shock characterization changed in 52%, confidence increased significantly (pre-EDP mean = 3.3 +/- 0.9; post-EDP mean = 4.0 +/- 0.6; P = .0001), and stated treatment plans changed in 68% of the patients. Chart review demonstrated that similar proportions of control subjects had treatment changes, with a mean difference of 20% (95% CI = -2 to 42). Physician assessments of hemodynamic variables were moderately accurate. We conclude that EDP hemodynamic profiles change assessments and increase confidence in assessments but may not alter treatment.