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A thorough exploration of traumatic wound is critical to accurately assess the severity of the injury. When it comes to glass-related injuries, the diagnosis of a glass foreign body is often prioritized over identifying any underlying damage. The authors report a case of peroneus longus tendon rupture caused by plate-glass accident that was misdiagnosed in the emergency department (ED) as a superficial laceration.
ABSTRACT
LEVELS OF EVIDENCE: Level V.
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The original Guidelines for Biosafety in Teaching Laboratories were developed in 2012 in response to an outbreak of Salmonella Typhimurium tracked by the Centers for Disease Control and Prevention (CDC) that originated from clinical and teaching microbiology laboratories. In the 7 years since the publication of the guidelines, there have been two subsequent CDC-reported Salmonella outbreaks originating from clinical and teaching microbiology laboratories. Use of and issues with the guidelines by ASM members have been tracked by various means since publication, and in 2018 it became apparent that an update of the guidelines was necessary. The Education Board of the American Society for Microbiology charged this task force with updating the guidelines based on the accumulated information. While the guidelines should look familiar, users will find that the originally separate BSL1 and BSL2 guidelines have been rolled into one document, to help eliminate redundancy and confusion. In addition, sections on risk assessment and service animals in the teaching laboratory have been added. These updated guidelines should help clarify many of the issues for which users expressed problems with the original guidelines.
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BACKGROUND: Acid tolerance in Escherichia coli O157:H7 contributes to persistence in its bovine host and is thought to promote passage through the gastric barrier of humans. Dps (DNA-binding protein in starved cells) mutants of E. coli have reduced acid tolerance when compared to the parent strain although the role of Dps in acid tolerance is unclear. This study investigated the mechanism by which Dps contributes to acid tolerance in E. coli O157:H7. RESULTS: The results from this study showed that acid stress lead to damage of chromosomal DNA, which was accentuated in dps and recA mutants. The use of Bal31, which cleaves DNA at nicks and single-stranded regions, to analyze chromosomal DNA extracted from cells challenged at pH 2.0 provided in vivo evidence of acid damage to DNA. The DNA damage in a recA mutant further corroborated the hypothesis that acid stress leads to DNA strand breaks. Under in vitro assay conditions, Dps was shown to bind plasmid DNA directly and protect it from acid-induced strand breaks. Furthermore, the extraction of DNA from Dps-DNA complexes required a denaturing agent at low pH (2.2 and 3.6) but not at higher pH (>pH4.6). Low pH also restored the DNA-binding activity of heat-denatured Dps. Circular dichroism spectra revealed that at pH 3.6 and pH 2.2 Dps maintains or forms alpha-helices that are important for Dps-DNA complex formation. CONCLUSION: Results from the present work showed that acid stress results in DNA damage that is more pronounced in dps and recA mutants. The contribution of RecA to acid tolerance indicated that DNA repair was important even when Dps was present. Dps protected DNA from acid damage by binding to DNA. Low pH appeared to strengthen the Dps-DNA association and the secondary structure of Dps retained or formed alpha-helices at low pH. Further investigation into the precise interplay between DNA protection and damage repair pathways during acid stress are underway to gain additional insight.
Subject(s)
Acids/pharmacology , Bacterial Outer Membrane Proteins/metabolism , DNA Damage/drug effects , DNA, Bacterial/metabolism , Escherichia coli O157/genetics , Escherichia coli Proteins/metabolism , Bacterial Outer Membrane Proteins/genetics , Chromosomes, Bacterial/metabolism , Circular Dichroism , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Escherichia coli O157/metabolism , Escherichia coli Proteins/genetics , Genes, Bacterial , Hydrogen-Ion Concentration , Mutation , Plasmids , Rec A Recombinases/genetics , Rec A Recombinases/metabolismABSTRACT
Effects of incorrect or partial implementation (poor treatment integrity) on response cost are largely unknown. We evaluated reduced treatment integrity during response cost on rates of 2 concurrently available responses. College students earned points by clicking on either a black circle or a red circle on a computer screen. Experiment 1 compared 2 types of treatment-integrity failures (omission and commission errors) across 2 levels of integrity (20% and 50%). Compared to 100% integrity conditions, omission errors did not suppress responding to the same extent, and commission errors reduced target responding but also decreased rates of alternative behavior. Experiment 2 compared the effects of 20% and 50% omission errors within subjects. Implementation at 50% integrity adequately suppressed responding, but treatment effects were lost at 20% integrity. There may be a critical level at which response cost must be implemented to suppress responding, which has important implications for application.
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Attention/physiology , Conditioning, Operant , Extinction, Psychological , Reinforcement, Psychology , Adolescent , Female , Humans , Male , Photic Stimulation , Punishment , Reinforcement Schedule , Young AdultABSTRACT
When tetracycline was present, tetA(C) reduced acid tolerance, suppressed rpoS expression, and increased the concentration of total soluble proteins in stationary-phase Escherichia coli. The suppression of acid tolerance was reversed by 85 mM sodium, potassium, magnesium, and calcium ions but not by 85 mM sucrose. Implications for using TetA(C) are discussed.