A Distance-Weighted Interaction Map Reveals a Previously Uncharacterized Layer of the Bacillus subtilis Spore Coat

SummaryBacillus subtilis spores are encased in a protein assembly called the spore coat that is made up of at least 70 different proteins. Conventional electron microscopy shows the coat to be organized into two distinct layers. Because the coat is about as wide as the theoretical limit of light microscopy, quantitatively measuring the localization of individual coat proteins within the coat is challenging. We used fusions of coat proteins to green fluorescent protein to map genetic dependencies for coat assembly and to define three independent subnetworks of coat proteins. To complement the genetic data, we measured coat protein localization at subpixel resolution and integrated these two data sets to produce a distance-weighted genetic interaction map. Using these data, we predict that the coat comprises at least four spatially distinct layers, including a previously uncharacterized glycoprotein outermost layer that we name the spore crust. We found that crust assembly depends on proteins we predicted to localize to the crust. The crust may be conserved in all Bacillus spores and may play critical functions in the environment

Topoisomerase Inhibitors Addressing Fluoroquinolone Resistance in Gram-Negative Bacteria.

Since their discovery over 5 decades ago, quinolone antibiotics have found enormous success as broad spectrum agents that exert their activity through dual inhibition of bacterial DNA gyrase and topoisomerase IV. Increasing rates of resistance, driven largely by target-based mutations in the GyrA/ParC quinolone resistance determining region, have eroded the utility and threaten the future use of this vital class of antibiotics. Herein we describe the discovery and optimization of a series of 4-(aminomethyl)quinolin-2(1H)-ones, exemplified by 34, that inhibit bacterial DNA gyrase and topoisomerase IV and display potent activity against ciprofloxacin-resistant Gram-negative pathogens. X-ray crystallography reveals that 34 occupies the classical quinolone binding site in the topoisomerase IV-DNA cleavage complex but does not form significant contacts with residues in the quinolone resistance determining region

From Prebiotics to Probiotics: The Evolution and Functions of tRNA Modifications

All nucleic acids in cells are subject to post-transcriptional chemical modifications. These are catalyzed by a myriad of enzymes with exquisite specificity and that utilize an often-exotic array of chemical substrates. In no molecule are modifications more prevalent than in transfer RNAs. In the present document, we will attempt to take a chemical rollercoaster ride from prebiotic times to the present, with nucleoside modifications as key players and tRNA as the centerpiece that drove the evolution of biological systems to where we are today. These ideas will be put forth while touching on several examples of tRNA modification enzymes and their modus operandi in cells. In passing, we submit that the choice of tRNA is not a whimsical one but rather highlights its critical function as an essential invention for the evolution of protein enzymes

Assessing the Impact of Teaching Patient Safety Principles to Medical Students During Surgical Clerkships

A critical aspect of enhancing patient safety is modifying the healthcare safety culture. We hypothesize that students who participate in safety curricula are knowledgeable regarding patient safety and likely to intervene to avoid patient errors. A two-part patient safety curriculum was taught: introductory theories (first year) and a clinically oriented course during surgery rotations (third year). All students participated in the first year introduction and a random cohort of students (62.6%, N = 67) participated in the third year program. Multiple choice tests and web-based surveys were administered. Statistical analysis was carried out using Student's t-test for comparisons of test mean scores and z-test for comparison of the survey data. Students who participated in both years' curricula scored higher on didactic test than those who participated in only the first year course (82.9% versus 75.5%, P < 0.001). More students participating in both portions of the curricula intervened during at least one clinical encounter to avoid a patient error (77% versus 61%, P < 0.05). Students rated junior house-staff more receptive to patient safety suggestions than surgical fellows and faculty (84% versus 66%, P < 0.05); 75% of students rated their surgical clerkship exposure to patient safety somewhat/extremely valuable compared with 54% students who rated the first year exposure as somewhat/extremely valuable ( P < 0.05). Medical students who have practical applications of patient safety education reinforced during surgery rotations are knowledgeable and willing to intervene in patient safety concerns. Teaching clinically relevant patient safety skills influences positive behavioral changes in medical students' performance on surgical teams

Enhancing patient safety in the trauma/surgical intensive care unit

Preventable deaths due to errors in trauma patients with otherwise survivable injuries account for up to 10% of fatalities in Level I trauma centers, 50% of these errors occur in the intensive care unit (ICU). The root cause of 67% of the Joint Commission sentinel events is communication errors. The objective is (1) to study how critical information degrades and how it is lost over 24 hours and (2) to determine whether a structured checklist for ICU handoffs prevents information loss. Prospective cohort study of trauma and surgical ICU teams observed with and without use of the checklist. An observational period (control group) was followed by a didactic session on the science and use of a checklist (study group), which was used for patient management and handoffs. Information was tracked for a 24-hour period and all handoffs. Comparisons use chi or Fisher's exact test and a p value <0.05 was defined as significant. Three hundred and thirty-two patient ICU days were observed (119 control, 213 study) and 689 patient care items (303 control, 386 study) were followed. Seventy-five (10.9%) items were lost over 24 hours; 61 of 303 (20.1%) without checklist and 14 of 386 (3.6%) with checklist (p < 0.0001). Critical laboratory values and test results were the most frequent lost items (36.1% control vs. 4.5% study p < 0.0001). Six of 75 (8.1%) items were correctly ordered but not carried out by ICU nursing staff--all caught and corrected with checklist use. Critical information is degraded over 24 hours in the ICU. A structured checklist significantly reduces patient errors due to lost information and communication lapses between trauma ICU team members at handoffs of care