The Impact of Flame Burn Injuries on Patients Who Sustain Mild Injuries From Motor Vehicle Crashes.

BACKGROUND: The purpose of this study was to determine the differences in patient outcomes between motor vehicle crash (MVC) victims with an ISS < 15 and those with a similar ISS and a flame burn injury. METHODS: Data for patients involved in a MVC with a GCS ≥12 and an ISS < 15 with and without flame burn injury were reviewed from the American College of Surgeons National Trauma Data Bank between 2007 and 2017. International Classification of Diseases-9 and -10 revisions and External Injury Codes were used to identify patients who were divided into MVC only (Group 1) and MVC with additional flame burn injury (Group 2). In-hospital mortality was the primary outcome whereas secondary outcomes included ICU admission, ICU length of stay (LOS), hospital LOS, sepsis, deep vein thrombosis, acute respiratory distress syndrome, and pneumonia. Simple linear regression was used in the form of odds ratios to investigate risk factors for mortality and secondary outcomes. RESULTS: The mean LOS and ICU LOS were longer in Group 2 (5.9 vs 4.0 days, p-value <0.001, and 1.2 vs 0.6 days, p-value <0.001, respectively), with more patients being admitted to the ICU as well (22.9% vs 17.3%, p-value <0.001). Also, there were significantly higher rates of pneumonia (0.8% vs 0.5%, p-value 0.0014), deep vein thrombosis (0.6% vs 0.4%, p-value 0.028), and acute respiratory distress syndrome (0.5% vs 0.3%, p-value 0.004) in Group 2. Patients in Group 1 were older and more likely had hypertension, congestive heart failure, and COPD. There was no significant difference in mortality between Groups by odds ratios (OR 0.85, p-value 0.743) or raw percentages (0.3% vs 0.3%, p-value = 0.874). CONCLUSION: MVC victims with mild injuries who also sustain a burn injury are more likely to require admission to the ICU regardless of their comorbidities and more likely to develop respiratory complications, especially pneumonia and an increase in ICU and hospital LOS.

Direct Comparison of Amino Acid and Salt Interactions with Double-Stranded and Single-Stranded DNA from Explicit-Solvent Molecular Dynamics Simulations.

Given the ubiquitous nature of protein-DNA interactions, it is important to understand the interaction thermodynamics of individual amino acid side chains for DNA. One way to assess these preferences is to perform molecular dynamics (MD) simulations. Here we report MD simulations of 20 amino acid side chain analogs interacting simultaneously with both a 70-base-pair double-stranded DNA and with a 70-nucleotide single-stranded DNA. The relative preferences of the amino acid side chains for dsDNA and ssDNA match well with values deduced from crystallographic analyses of protein-DNA complexes. The estimated apparent free energies of interaction for ssDNA, on the other hand, correlate well with previous simulation values reported for interactions with isolated nucleobases, and with experimental values reported for interactions with guanosine. Comparisons of the interactions with dsDNA and ssDNA indicate that, with the exception of the positively charged side chains, all types of amino acid side chain interact more favorably with ssDNA, with intercalation of aromatic and aliphatic side chains being especially notable. Analysis of the data on a base-by-base basis indicates that positively charged side chains, as well as sodium ions, preferentially bind to cytosine in ssDNA, and that negatively charged side chains, and chloride ions, preferentially bind to guanine in ssDNA. These latter observations provide a novel explanation for the lower salt dependence of DNA duplex stability in GC-rich sequences relative to AT-rich sequences.

Molecular Dynamics Simulations of 441 Two-Residue Peptides in Aqueous Solution: Conformational Preferences and Neighboring Residue Effects with the Amber ff99SB-ildn-NMR Force Field.

Understanding the intrinsic conformational preferences of amino acids and the extent to which they are modulated by neighboring residues is a key issue for developing predictive models of protein folding and stability. Here we present the results of 441 independent explicit-solvent MD simulations of all possible two-residue peptides that contain the 20 standard amino acids with histidine modeled in both its neutral and protonated states. (3)J(HNHα) coupling constants and δ(Hα) chemical shifts calculated from the MD simulations correlate quite well with recently published experimental measurements for a corresponding set of two-residue peptides. Neighboring residue effects (NREs) on the average (3)J(HNHα) and δ(Hα) values of adjacent residues are also reasonably well reproduced, with the large NREs exerted experimentally by aromatic residues, in particular, being accurately captured. NREs on the secondary structure preferences of adjacent amino acids have been computed and compared with corresponding effects observed in a coil library and the average ß-turn preferences of all amino acid types have been determined. Finally, the intrinsic conformational preferences of histidine, and its NREs on the conformational preferences of adjacent residues, are both shown to be strongly affected by the protonation state of the imidazole ring.