👤 H P Dym

Situation awareness has been defined as the perception of the elements in the environment within volumes of time and space, the comprehension of their meaning, and the projection of their status in the near future. Intensivists often make time-sensitive critical decisions, and loss of situation awareness can lead to errors. It has been shown that simulation-based training is superior to lecture-based training for some critical scenarios. Because the methods of training to improve situation awareness have not been well studied in the medical field, we compared the impact of simulation vs. lecture training using the Situation Awareness Global Assessment Technique (SAGAT) score. To identify an effective method for teaching situation awareness. We randomly assigned 17 critical care fellows to simulation vs. lecture training. Training consisted of eight cases on airway management, including topics such as elevated intracranial pressure, difficult airway, arrhythmia, and shock. During the testing scenario, at random times between 4 and 6 minutes into the simulation, the scenario was frozen, and the screens were blanked. Respondents then completed the 28 questions on the SAGAT scale. Sample items were categorized as Perception, Projection, and Comprehension of the situation. Results were analyzed using SPSS Version 21. Eight fellows from the simulation group and nine from the lecture group underwent simulation testing. Sixty-four SAGAT scores were recorded for the simulation group and 48 scores were recorded for the lecture group. The mean simulation vs. lecture group SAGAT score was 64.3 ± 10.1 (SD) vs. 59.7 ± 10.8 (SD) (P = 0.02). There was also a difference in the median Perception ability between the simulation vs. lecture groups (61.1 vs. 55.5, P = 0.01). There was no difference in the median Projection and Comprehension scores between the two groups (50.0 vs. 50.0, P = 0.92, and 83.3 vs. 83.3, P = 0.27). We found a significant, albeit modest, difference between simulation training and lecture training on the total SAGAT score of situation awareness mainly because of the improvement in perception ability. Simulation may be a superior method of teaching situation awareness. Show less

Protein complexes often represent an ensemble of different assemblies with distinct functions and regulation. This increased complexity is enabled by the variety of protein diversification mechanisms that exist at every step of the protein biosynthesis pathway, such as alternative splicing and post transcriptional and translational modifications. The resulting variation in subunits can generate compositionally distinct protein assemblies. These different forms of a single protein complex may comprise functional variances that enable response and adaptation to varying cellular conditions. Despite the biological importance of this layer of complexity, relatively little is known about the compositional heterogeneity of protein complexes, mostly due to technical barriers of studying such closely related species. Here, we show that native mass spectrometry (MS) offers a way to unravel this inherent heterogeneity of protein assemblies. Our approach relies on the advanced Orbitrap mass spectrometer capable of multistage MS analysis across all levels of protein organization. Specifically, we have implemented a two-step fragmentation process in the inject flatapole device, which was converted to a linear ion trap, and can now probe the intact protein complex assembly, through its constituent subunits, to the primary sequence of each protein. We demonstrate our approach on the yeast homotetrameric FBP1 complex, the rate-limiting enzyme in gluconeogenesis. We show that the complex responds differently to changes in growth conditions by tuning phosphorylation dynamics. Our methodology deciphers, on a single instrument and in a single measurement, the stoichiometry, kinetics, and exact position of modifications, contributing to the exposure of the multilevel diversity of protein complexes. Show less

The goal of an infection control program is to provide a safe working environment for dental health care personnel and their patients. Practitioners can achieve this by adopting measures that reduce health care-associated infections among patients and occupational exposures among dental health care personnel. It is crucial for all dental practitioners to be up to date on current Centers for Disease Control and Prevention guidelines, equipment, and techniques for proper infection control. Continuous evaluation of infection control practices is important. Patients and dental providers should be confident that oral health care can be delivered and received in a safe manner. Show less

Osteomyelitis is an inflammation of bone marrow with a tendency for progression, involving the cortical plates and often periosteal tissues, with most cases occurring after trauma to bone or bone surgery or secondary to vascular insufficiency. Antimicrobial therapy and surgical débridement are the primary modalities of osteomyelitis treatment, although often it is associated with a prolonged course, requiring a large commitment between patient and clinician as well as sizable health care costs. Despite surgical and chemotherapeutic advancements, osteomyelitis remains difficult to treat, and no universally accepted protocol for treatment exists. Show less

Upon heterologous overexpression, many proteins misfold or aggregate, thus resulting in low functional yields. Human acetylcholinesterase (hAChE), an enzyme mediating synaptic transmission, is a typical case of a human protein that necessitates mammalian systems to obtain functional expression. We developed a computational strategy and designed an AChE variant bearing 51 mutations that improved core packing, surface polarity, and backbone rigidity. This variant expressed at ∼2,000-fold higher levels in E. coli compared to wild-type hAChE and exhibited 20°C higher thermostability with no change in enzymatic properties or in the active-site configuration as determined by crystallography. To demonstrate broad utility, we similarly designed four other human and bacterial proteins. Testing at most three designs per protein, we obtained enhanced stability and/or higher yields of soluble and active protein in E. coli. Our algorithm requires only a 3D structure and several dozen sequences of naturally occurring homologs, and is available at http://pross.weizmann.ac.il. Show less

The ability to tune the light-absorption properties of chlorophylls by their protein environment is the key to the robustness and high efficiency of photosynthetic light-harvesting proteins. Unfortunately, the intricacy of the natural complexes makes it very difficult to identify and isolate specific protein-pigment interactions that underlie the spectral-tuning mechanisms. Herein we identify and demonstrate the tuning mechanism of chlorophyll spectra in type II water-soluble chlorophyll binding proteins from Brassicaceae (WSCPs). By comparing the molecular structures of two natural WSCPs we correlate a shift in the chlorophyll red absorption band with deformation of its tetrapyrrole macrocycle that is induced by changing the position of a nearby tryptophan residue. We show by a set of reciprocal point mutations that this change accounts for up to 2/3 of the observed spectral shift between the two natural variants. Show less

Post-transcriptional regulatory processes may change transcript levels and affect cell-to-cell variability or noise. We study small-RNA downregulation to elucidate its effects on noise in the iron homeostasis network of Escherichia coli In this network, the small-RNA RyhB undergoes stoichiometric degradation with the transcripts of target genes in response to iron stress. Using single-molecule fluorescence in situ hybridization, we measured transcript numbers of the RyhB-regulated genes sodB and fumA in individual cells as a function of iron deprivation. We observed a monotonic increase of noise with iron stress but no evidence of theoretically predicted, enhanced stoichiometric fluctuations in transcript numbers, nor of bistable behavior in transcript distributions. Direct detection of RyhB in individual cells shows that its noise is much smaller than that of these two targets, when RyhB production is significant. A generalized two-state model of bursty transcription that neglects RyhB fluctuations describes quantitatively the dependence of noise and transcript distributions on iron deprivation, enabling extraction of in vivo RyhB-mediated transcript degradation rates. The transcripts' threshold-linear behavior indicates that the effective in vivo interaction strength between RyhB and its two target transcripts is comparable. Strikingly, the bacterial cell response exhibits Fur-dependent, switch-like activation instead of a graded response to iron deprivation. Show less

Pharmacologic agents play an integral role in the overall management of temporomandibular joint disorder. The general dentist should be familiar with the different classes of drugs currently in use for dealing with this often complex medical/dental problem. Show less

This article highlights the commonly used medications used in dentistry and oral surgery. General dentists and specialists must be knowledgeable about the pharmacology of the drugs currently available along with their risks and benefits. Enteral sedation is a useful adjunct for the treatment of anxious adult and pediatric patients. When enteral sedation is used within the standards of care, the interests of the public and the dental profession are served through a cost-effective, effective service that can be widely available. Oral sedation enables dentists to provide dental care to millions of individuals who otherwise would have unmet dental needs. Show less

Any dental office can face a variety of medical emergencies; therefore, the health care professional and the staff should always be prepared to deal with these emergencies in their office. Preparedness of the dental office staff and their prompt recognition of these emergencies will be the most important factor in dealing with the emergencies in any dental office. Health care professionals should follow the recommendations in this article to maintain a guideline for their staff and office and conduct regular emergency drills to examine the equipment and preparedness of their staff. Show less

Structure-based drug design utilizes apoprotein or complex structures retrieved from the PDB. >57% of crystallographic PDB entries were obtained with polyethylene glycols (PEGs) as precipitant and/or as cryoprotectant, but <6% of these report presence of individual ethyleneglycol oligomers. We report a case in which ethyleneglycol oligomers' presence in a crystal structure markedly affected the bound ligand's position. Specifically, we compared the positions of methylene blue and decamethonium in acetylcholinesterase complexes obtained using isomorphous crystals precipitated with PEG200 or ammonium sulfate. The ligands' positions within the active-site gorge in complexes obtained using PEG200 are influenced by presence of ethyleneglycol oligomers in both cases bound to W84 at the gorge's bottom, preventing interaction of the ligand's proximal quaternary group with its indole. Consequently, both ligands are ∼3.0Å further up the gorge than in complexes obtained using crystals precipitated with ammonium sulfate, in which the quaternary groups make direct π-cation interactions with the indole. These findings have implications for structure-based drug design, since data for ligand-protein complexes with polyethylene glycol as precipitant may not reflect the ligand's position in its absence, and could result in selecting incorrect drug discovery leads. Docking methylene blue into the structure obtained with PEG200, but omitting the ethyleneglycols, yields results agreeing poorly with the crystal structure; excellent agreement is obtained if they are included. Many proteins display features in which precipitants might lodge. It will be important to investigate presence of precipitants in published crystal structures, and whether it has resulted in misinterpreting electron density maps, adversely affecting drug design. Show less

Molecular evolution has focused on the divergence of molecular functions, yet we know little about how structurally distinct protein folds emerge de novo. We characterized the evolutionary trajectories and selection forces underlying emergence of β-propeller proteins, a globular and symmetric fold group with diverse functions. The identification of short propeller-like motifs (<50 amino acids) in natural genomes indicated that they expanded via tandem duplications to form extant propellers. We phylogenetically reconstructed 47-residue ancestral motifs that form five-bladed lectin propellers via oligomeric assembly. We demonstrate a functional trajectory of tandem duplications of these motifs leading to monomeric lectins. Foldability, i.e., higher efficiency of folding, was the main parameter leading to improved functionality along the entire evolutionary trajectory. However, folding constraints changed along the trajectory: initially, conflicts between monomer folding and oligomer assembly dominated, whereas subsequently, upon tandem duplication, tradeoffs between monomer stability and foldability took precedence. Show less

Low back pain (LBP) is responsible for more than 2.5 million visits to US emergency departments (EDs) annually. These patients are usually treated with nonsteroidal anti-inflammatory drugs, acetaminophen, opioids, or skeletal muscle relaxants, often in combination. To compare functional outcomes and pain at 1 week and 3 months after an ED visit for acute LBP among patients randomized to a 10-day course of (1) naproxen + placebo; (2) naproxen + cyclobenzaprine; or (3) naproxen + oxycodone/acetaminophen. This randomized, double-blind, 3-group study was conducted at one urban ED in the Bronx, New York City. Patients who presented with nontraumatic, nonradicular LBP of 2 weeks' duration or less were eligible for enrollment upon ED discharge if they had a score greater than 5 on the Roland-Morris Disability Questionnaire (RMDQ). The RMDQ is a 24-item questionnaire commonly used to measure LBP and related functional impairment on which 0 indicates no functional impairment and 24 indicates maximum impairment. Beginning in April 2012, a total of 2588 patients were approached for enrollment. Of the 323 deemed eligible for participation, 107 were randomized to receive placebo and 108 each to cyclobenzaprine and to oxycodone/acetaminophen. Follow-up was completed in December 2014. All participants were given 20 tablets of naproxen, 500 mg, to be taken twice a day. They were randomized to receive either 60 tablets of placebo; cyclobenzaprine, 5 mg; or oxycodone, 5 mg/acetaminophen, 325 mg. Participants were instructed to take 1 or 2 of these tablets every 8 hours, as needed for LBP. They also received a standardized 10-minute LBP educational session prior to discharge. The primary outcome was improvement in RMDQ between ED discharge and 1 week later. Demographic characteristics were comparable among the 3 groups. At baseline, median RMDQ score in the placebo group was 20 (interquartile range [IQR],17-21), in the cyclobenzaprine group 19 (IQR,17-21), and in the oxycodone/acetaminophen group 20 (IQR,17-22). At 1-week follow-up, the mean RMDQ improvement was 9.8 in the placebo group, 10.1 in the cyclobenzaprine group, and 11.1 in the oxycodone/acetaminophen group. Between-group difference in mean RMDQ improvement for cyclobenzaprine vs placebo was 0.3 (98.3% CI, -2.6 to 3.2; P = .77), for oxycodone/acetaminophen vs placebo, 1.3 (98.3% CI, -1.5 to 4.1; P = .28), and for oxycodone/acetaminophen vs cyclobenzaprine, 0.9 (98.3% CI, -2.1 to 3.9; P = .45). Among patients with acute, nontraumatic, nonradicular LBP presenting to the ED, adding cyclobenzaprine or oxycodone/acetaminophen to naproxen alone did not improve functional outcomes or pain at 1-week follow-up. These findings do not support use of these additional medications in this setting. clinicaltrials.gov Identifier: NCT01587274. Show less

Alveolar bone that is insufficient to support implant placement due to lack of height or width may be augmented with grafting materials including bone morphogenic protein to create sites that are adequate for implant placement and long-term stability of implant-supported prosthesis. Bone morphogenic protein can be used alone or in concert with other bone graft materials as an alternative to invasive allograft bone harvesting procedures. Show less

Pneumatization of the maxillary sinus secondary to posterior maxillary tooth loss is an extremely common finding. Significant atrophy of the maxilla prevents implant placement in this region. For several decades, sinus augmentation has been used to develop these sites for dental implant placement. The main techniques for increasing the vertical bone height of the posterior maxilla are the transalveolar and lateral antrostomy approaches. The clinical and radiographic examinations dictate the appropriate method for each clinical situation. Both techniques have been shown to have high success rates. However, practitioners must be aware of potential complications and how to address them. Show less

Modification of acyl carrier proteins (ACP) or domains by the covalent binding of a 4'-phosphopantetheine (4'-PP) moiety is a fundamental condition for activation of fatty acid synthases (FASes) and polyketide synthases (PKSes). Binding of 4'-PP is mediated by 4' phosphopantetheinyl transfersases (PPTases). Mycobacterium tuberculosis (Mtb) possesses two essential PPTases: acyl carrier protein synthase (Mtb AcpS), which activates the multidomain fatty acid synthase I (FAS I), and Mtb PptT, an Sfp-type broad spectrum PPTase that activates PKSes. To date, it has not been determined which of the two Mtb PPTases, AcpS or PptT, activates the meromycolate extension ACP, Mtb AcpM, en route to the production of mycolic acids, the main components of the mycobacterial cell wall. In this study, we tested the enzymatic activation of a highly purified Mtb apo-AcpM to Mtb holo-AcpM by either Mtb PptT or Mtb AcpS. By using SDS-PAGE band shift assay and mass spectrometry analysis, we found that Mtb PptT is the PPTase that activates Mtb AcpM. We measured the catalytic activity of Mtb PptT toward CoA, using an activation assay of a blue pigment synthase, BpsA (a nonribosomal peptide synthase, NRPS). BpsA activation by Mtb PptT was inhibited by Mtb apo-AcpM through competition for CoA, in accord with Mtb AcpM activation. A structural model of the putative interaction between Mtb PptT and Mtb AcpM suggests that both hydrophobic and electrostatic interactions stabilize this complex. To conclude, activation of Mtb AcpM by Mtb PptT reveals a potential target of the multistep mycolic acid biosynthesis. Show less

Correct recognition, description, and classification of acetabular fractures is essential for efficient patient triage and treatment. Acetabular fractures may result from high-energy trauma or low-energy trauma in the elderly. The most widely used acetabular fracture classification system among radiologists and orthopedic surgeons is the system of Judet and Letournel, which includes five elementary (or elemental) and five associated fractures. The elementary fractures are anterior wall, posterior wall, anterior column, posterior column, and transverse. The associated fractures are all combinations or partial combinations of the elementary fractures and include transverse with posterior wall, T-shaped, associated both column, anterior column or wall with posterior hemitransverse, and posterior column with posterior wall. The most unique fracture is the associated both column fracture, which completely dissociates the acetabular articular surface from the sciatic buttress. Accurate categorization of acetabular fractures is challenging because of the complex three-dimensional (3D) anatomy of the pelvis, the rarity of certain acetabular fracture variants, and confusing nomenclature. Comparing a 3D image of the fractured acetabulum with a standard diagram containing the 10 Judet and Letournel categories of acetabular fracture and using a flowchart algorithm are effective ways of arriving at the correct fracture classification. Online supplemental material is available for this article. Show less

Membrane type 1 metalloprotease (MT1-MMP) is a membrane-anchored, zinc-dependent protease. MT1-MMP is an important mediator of cell migration and invasion, and overexpression of this enzyme has been correlated with the malignancy of various tumor types. Therefore, modulators of MT1-MMP activity are proposed to possess therapeutic potential in numerous invasive diseases. Here we report the inhibition mode of MT1-MMP by LEM-2/15 antibody, which targets a surface epitope of MT1-MMP. Specifically, the crystal structures of Fab LEM-2/15 in complex with the MT1-MMP surface antigen suggest that conformational swiveling of the enzyme surface loop is required for effective binding and consequent inhibition of MT1-MMP activity on the cell membrane. This inhibition mechanism appears to be effective in controlling active MT1-MMP in endothelial cells and at the leading edge of migratory cancer cells. Show less

A variety of renal and ureteral pathologies are encountered on computed tomographic scans performed in the emergency department. Although these are often suspected based on the patient's clinical presentation, they may also be fortuitous or incidental findings. Stone disease is the most common genitourinary condition seen in the acute setting; however, other conditions such as infection, hemorrhage, acute ischemic disease, and iatrogenic and traumatic injuries may also occur. We review the computed tomographic features of the spectrum of these conditions. Show less

Transesophageal echocardiography (TEE) is routinely used to assess for thrombus in the left atrium (LA) and left atrial appendage (LAA) in patients undergoing atrial fibrillation (AF) ablation. However, little is known about the outcome of AF ablation in patients with documented LAA sludge. We hypothesize that AF ablation can be performed safely in a proportion of patients with sludge in the LAA and may have a significant benefit for these patients. We performed a retrospective analysis of all patients undergoing AF ablation at New York University Langone Medical Center (NYULMC) from January 1st 2011 to June 30, 2013. Patients with sludge found on their TEE immediately prior to AF ablation were identified and followed for stroke, AF recurrence, procedural complications, major bleeding, or death. Among 1,076 patients who underwent AF ablation, 8 patients (mean age 69 ± 13 years; 75 % men) with sludge were identified. Patients with sludge in their LAA had no incidence of early or late occurrence of stroke during mean follow-up of 10 months. One patient had a left groin hematoma, and two patients had atrial tachycardias that needed a repeat ablation. TEE at the time of repeat ablation demonstrated the presence of spontaneous echo contrast (smoke) and resolution of sludge. There were no deaths. In a cohort of eight patients with LAA sludge who underwent AF ablation, no significant thromboembolic events occurred during or after the procedure. AF ablation can be performed safely and may be beneficial in these patients. Larger studies are warranted to better determine the most appropriate management route. Show less

Although ultrasound is the primary modality used in the diagnosis of ectopic pregnancy, various forms of this condition and their complications may occasionally be further evaluated with MRI or may be incidentally detected on CT or MRI when an alternative diagnosis is suspected. Various types of ectopic pregnancy have characteristic imaging features. Radiologists should be familiar with these features and should always consider the possibility of ectopic pregnancy in the setting of hemoperitoneum or a pelvic mass in a woman of child-bearing age. Familiarity with the typical CT and MRI appearances of various forms of ectopic pregnancy facilitates prompt and accurate diagnosis and treatment. Show less

To determine the sensitivity of portal venous phase contrast-enhanced CT for the detection of renal stones. This retrospective study included 97 CT examinations of the abdomen without and with intravenous contrast, including 85 (87.6%) examinations with at least one renal stone on the "gold standard" noncontrast images, as scored by a single radiologist. Three other radiologists each independently reviewed only the contrast-enhanced images from all 97 examinations and recorded all renal stones. Reviewer sensitivity for stones was categorized by stone diameter. Reviewer sensitivity and specificity for stone disease were also calculated on a per-kidney basis. The 97 cases included a total of 238 stones ≥1 mm, with a mean (±SD) of 1.2 ± 1.9 stones per kidney and a stone diameter of 3.5 ± 3.0 mm. Pooling data for the three reviewers, sensitivity for all stones was 81%; sensitivity for stones ≥2, ≥3, ≥4, and ≥5 mm was 88%, 95%, 99%, and 98%, respectively. Sensitivity for stone disease on a per-kidney basis was 94% when considering all stones; when considering only stones ≥2, ≥3, and ≥4 mm, sensitivity was 96%, 99%, and 100%, respectively. Specificity for stone disease on a per-kidney basis was 98% overall, 99% when considering only stones ≥2 mm, and 100% when considering only stones ≥3 mm. Contrast-enhanced CT is highly sensitive for the detection of renal stones ≥3 mm in diameter and less sensitive for smaller stones. In cases where the clinical diagnosis is uncertain and performance of a CT examination is being contemplated, intravenous contrast utilization would allow assessment for stone disease while also optimizing evaluation for other conditions. Show less

We propose a 3-layer composite closure technique for an oral antral communication (OAC) while avoiding secondary donor site morbidity. A patient had developed a 1-cm OAC after extraction of right maxillary first molar. The patient subsequently developed acute maxillary sinusitis. The patient was taken to the operating room, and a Caldwell-Luc procedure was performed. The bony window from the Caldwell-Luc was "press fit" over the bony OAC defect. Soft tissue closure was then achieved with a buccal fat pad flap and a buccal mucosal advancement flap. The patient was examined on postoperative day 5 and 1, 2, 3, 6, and 10 months postoperatively. The acute sinusitis had resolved. The soft tissue closure was successful. The bone graft remained intact, prevented sinus pneumatization, and restored continuity to the floor of the maxillary sinus. The presented technique for 3-layer closure of OACs allows for the stability of a double-layer closure of OAC with the added benefit of bone grafting from single operative site, achieving stable oral antral closure, bone grafting, and the avoidance of secondary donor site morbidity. Show less