1H, 13C, and 15N backbone and methyl group resonance assignments of ricin toxin A subunit

Ricin is a potent plant toxin that targets the eukaryotic ribosome by depurinating an adenine from the sarcin-ricin loop (SRL), a highly conserved stem-loop of the rRNA. As a category-B agent for bioterrorism it is a prime target for therapeutic intervention with antibodies and enzyme blocking inhibitors since no effective therapy exists for ricin. Ricin toxin A subunit (RTA) depurinates the SRL by binding to the P-stalk proteins at a remote site. Stimulation of the N-glycosidase activity of RTA by the P-stalk proteins has been studied extensively by biochemical methods and by X-ray crystallography. The current understanding of RTA's depurination mechanism relies exclusively on X-ray structures of the enzyme in the free state and complexed with transition state analogues. To date we have sparse evidence of conformational dynamics and allosteric regulation of RTA activity that can be exploited in the rational design of inhibitors. Thus, our primary goal here is to apply solution NMR techniques to probe the residue specific structural and dynamic coupling active in RTA as a prerequisite to understand the functional implications of an allosteric network. In this report we present de novo sequence specific amide and sidechain methyl chemical shift assignments of the 267 residue RTA in the free state and in complex with an 11-residue peptide (P11) representing the identical C-terminal sequence of the ribosomal P-stalk proteins. These assignments will facilitate future studies detailing the propagation of binding induced conformational changes in RTA complexed with inhibitors, antibodies, and biologically relevant targets.

Structure of a human monoclonal antibody in complex with Outer surface protein C (OspC) of the Lyme disease spirochete, Borreliella burgdorferi

Lyme disease is a tick-borne, multisystem infection caused by the spirochete, Borreliella burgdorferi . Although antibodies have been implicated in the resolution of Lyme disease, the specific B cell epitopes targeted during human infections remain largely unknown. In this study, we characterized and defined the structural epitope of a patient-derived bactericidal monoclonal IgG ("B11") against Outer surface protein C (OspC), a homodimeric lipoprotein necessary for B. burgdorferi tick-mediated transmission and early-stage colonization of vertebrate hosts. High-resolution epitope mapping was accomplished through hydrogen deuterium exchange-mass spectrometry (HDX-MS) and X-ray crystallography. Structural analysis of B11 Fab-OspC A complexes revealed the B11 Fabs associated in a 1:1 stoichiometry with the lateral faces of OspC A homodimers such that the antibodies are essentially positioned perpendicular to the spirochete's outer surface. B11's primary contacts reside within the membrane proximal regions of α-helices 1 and 6 and adjacent loops 5 and 6 in one OspC A monomer. In addition, B11 spans the OspC A dimer interface, engaging opposing α-helix 1', α-helix 2', and loop 2-3' in the second OspC A monomer. The B11-OspC A structure is reminiscent of the recently solved mouse transmission blocking monoclonal IgG B5 in complex with OspC A , indicating a mode of engagement with OspC that is conserved across species. In conclusion, we provide the first detailed insight into the interaction between a functional human antibody and an immunodominant Lyme disease antigen long considered an important vaccine target.

Single-domain antibodies reveal unique borrelicidal epitopes on the Lyme disease vaccine antigen, outer surface protein A (OspA)

Camelid-derived, single-domain antibodies (VHHs) have proven to be extremely powerful tools in defining the antigenic landscape of immunologically heterogeneous surface proteins. In this report, we generated a phage-displayed VHH library directed against the candidate Lyme disease vaccine antigen, outer surface protein A (OspA). Two alpacas were immunized with recombinant OspA serotype 1 from Borrelia burgdorferi sensu stricto strain B31, in combination with the canine vaccine RECOMBITEK Lyme containing lipidated OspA. The phage library was subjected to two rounds of affinity enrichment ("panning") against recombinant OspA, yielding 21 unique VHHs within two epitope bins, as determined through competition enzyme linked immunosorbent assays (ELISAs) with a panel of OspA-specific human monoclonal antibodies. Epitope refinement was conducted by hydrogen exchange-mass spectrometry. Six of the monovalent VHHs were expressed as human IgG1-Fc fusion proteins and shown to have functional properties associated with protective human monoclonal antibodies, including B. burgdorferi agglutination, outer membrane damage, and complement-dependent borreliacidal activity. The VHHs displayed unique reactivity profiles with the seven OspA serotypes associated with B. burgdorferi genospecies in the United States and Europe consistent with there being unique epitopes across OspA serotypes that should be considered when designing and evaluating multivalent Lyme disease vaccines.

Structure-Function Analysis of the A1 Subunit of Shiga Toxin 2 with Peptides That Target the P-Stalk Binding Site and Inhibit Activity

Shiga toxin 2a (Stx2a) is the virulence factor of Escherichia coli (STEC), which is associated with hemolytic uremic syndrome, the leading cause of pediatric kidney failure. The A1 subunit of Stx2a (Stx2A1) binds to the conserved C-terminal domain (CTD) of the ribosomal P-stalk proteins to remove an adenine from the sarcin-ricin loop (SRL) in the 28S rRNA, inhibiting protein synthesis. There are no antidotes against Stx2a or any other ribosome-inactivating protein (RIP). The structural and functional details of the binding of Stx2A1 to the P-stalk CTD are not known. Here, we carry out a deletion analysis of the conserved P-stalk CTD and show that the last eight amino acids (P8) of the P-stalk proteins are the minimal sequence required for optimal affinity and maximal inhibitory activity against Stx2A1. We determined the first X-ray crystal structure of Stx2A1 alone and in complex with P8 and identified the exact binding site. The C-terminal aspartic acid of the P-stalk CTD serves as an anchor, forming key contacts with the conserved arginine residues at the P-stalk binding pocket of Stx2A1. Although the ricin A subunit (RTA) binds to the P-stalk CTD, the last aspartic acid is more critical for the interaction with Stx2A1, indicating that RIPs differ in their requirements for the P-stalk. These results demonstrate that the catalytic activity of Stx2A1 is inhibited by blocking its interactions with the P-stalk, providing evidence that P-stalk binding is an essential first step in the recruitment of Stx2A1 to the SRL for depurination.

Structure-based design and optimization of a new class of small molecule inhibitors targeting the P-stalk binding pocket of ricin

Ricin, a category-B agent for bioterrorism, and Shiga toxins (Stxs), which cause food poisoning bind to the ribosomal P-stalk to depurinate the sarcin/ricin loop. No effective therapy exists for ricin or Stx intoxication. Ribosome binding sites of the toxins have not been targeted by small molecules. We previously identified CC10501, which inhibits toxin activity by binding the P-stalk pocket of ricin toxin A subunit (RTA) remote from the catalytic site. Here, we developed a fluorescence polarization assay and identified a new class of compounds, which bind P-stalk pocket of RTA with higher affinity and inhibit catalytic activity with submicromolar potency. A lead compound, RU-NT-206, bound P-stalk pocket of RTA with similar affinity as a five-fold larger P-stalk peptide and protected cells against ricin and Stx2 holotoxins for the first time. These results validate the P-stalk binding site of RTA as a critical target for allosteric inhibition of the active site.

Structural Basis of Antibody-Mediated Inhibition of Ricin Toxin Attachment to Host Cells

Monoclonal antibodies, JB4 and SylH3, neutralize ricin toxin (RT) by inhibiting the galactose-specific lectin activity of the B subunit of the toxin (RTB), which is required for cell attachment and entry. It is not immediately apparent how the antibodies accomplish this feat, considering that RTB consists of two globular domains (D1, D2) each divided into three homologous subdomains (α, β, γ) with the two functional galactosyl-specific carbohydrate recognition domains (CRDs) situated on opposite poles (subdomains 1α and 2γ). Here, we report the X-ray crystal structures of JB4 and SylH3 Fab fragments bound to RTB in the context of RT. The structures revealed that neither Fab obstructed nor induced detectable conformational alterations in subdomains 1α or 2γ. Rather, JB4 and SylH3 Fabs recognize nearly identical epitopes within an ancillary carbohydrate recognition pocket located in subdomain 1β. Despite limited amino acid sequence similarity between SylH3 and JB4 Fabs, each paratope inserts a Phe side chain from the heavy (H) chain complementarity determining region (CDR3) into the 1β CRD pocket, resulting in local aromatic stacking interactions that potentially mimic a ligand interaction. Reconciling the fact that stoichiometric amounts of SylH3 and JB4 are sufficient to disarm RTB's lectin activity without evidence of allostery, we propose that subdomain 1β functions as a "coreceptor" required to stabilize glycan interactions principally mediated by subdomains 1α and 2γ. Further investigation into subdomain 1β will yield fundamental insights into the large family of R-type lectins and open novel avenues for countermeasures aimed at preventing toxin uptake into vulnerable tissues and cells.

Structure of a transmission blocking antibody in complex with Outer surface protein A from the Lyme disease spirochete, Borreliella burgdorferi

319-44 is a human monoclonal antibody capable of passively protecting mice against tick-mediated infection with Borreliella burgdorferi, the bacterial genospecies responsible for Lyme disease in North America. In vitro, 319-44 has complement-dependent borreliacidal activity and spirochete agglutinating properties. Here, we report the 2.2 Å-resolution crystal structure of 319-44 Fab fragments in complex with Outer surface protein A (OspA), the ~30 kDa lipoprotein that was the basis of the first-generation Lyme disease vaccine approved in the United States. The 319-44 epitope is focused on OspA β-strands 19, 20, and 21, and the loops between β-strands 16-17, 18-19, and 20-21. Contact with loop 20-21 explains competition with LA-2, the murine monoclonal antibody used to estimate serum borreliacidal activities in the first-generation Lyme disease vaccine clinical trials. A high-resolution B-cell epitope map of OspA will accelerate structure-based design of second generation OspA-based vaccines.

Structural Elucidation of a Protective B Cell Epitope on Outer Surface Protein C (OspC) of the Lyme Disease Spirochete, Borreliella burgdorferi

Outer surface protein C (OspC) plays a pivotal role in mediating tick-to-host transmission and infectivity of the Lyme disease spirochete, Borreliella burgdorferi. OspC is a helical-rich homodimer that interacts with tick salivary proteins, as well as components of the mammalian immune system. Several decades ago, it was shown that the OspC-specific monoclonal antibody, B5, was able to passively protect mice from experimental tick-transmitted infection by B. burgdorferi strain B31. However, B5's epitope has never been elucidated, despite widespread interest in OspC as a possible Lyme disease vaccine antigen. Here, we report the crystal structure of B5 antigen-binding fragments (Fabs) in complex with recombinant OspC type A (OspC_A). Each OspC monomer within the homodimer was bound by a single B5 Fab in a side-on orientation, with contact points along OspC's α-helix 1 and α-helix 6, as well as interactions with the loop between α-helices 5 and 6. In addition, B5's complementarity-determining region (CDR) H3 bridged the OspC-OspC' homodimer interface, revealing the quaternary nature of the protective epitope. To provide insight into the molecular basis of B5 serotype specificity, we solved the crystal structures of recombinant OspC types B and K and compared them to OspC_A. This study represents the first structure of a protective B cell epitope on OspC and will aid in the rational design of OspC-based vaccines and therapeutics for Lyme disease. IMPORTANCE The spirochete Borreliella burgdorferi is a causative agent of Lyme disease, the most common tickborne disease in the United States. The spirochete is transmitted to humans during the course of a tick taking a bloodmeal. After B. burgdorferi is deposited into the skin of a human host, it replicates locally and spreads systemically, often resulting in clinical manifestations involving the central nervous system, joints, and/or heart. Antibodies directed against B. burgdorferi's outer surface protein C (OspC) are known to block tick-to-host transmission, as well as dissemination of the spirochete within a mammalian host. In this report, we reveal the first atomic structure of one such antibody in complex with OspC. Our results have implications for the design of a Lyme disease vaccine capable of interfering with multiple stages in B. burgdorferi infection.

Human B Cell Epitope Map of the Lyme Disease Vaccine Antigen, OspA

The Lyme disease (LD) vaccine formerly approved for use in the United States consisted of recombinant outer surface protein A (OspA) from Borrelia burgdorferi sensu stricto (ss), the bacterial genospecies responsible for the vast majority of LD in North America. OspA is an ∼30 kDa lipoprotein made up of 21 antiparallel β-strands and a C-terminal α-helix. In clinical trials, protection against LD following vaccination correlated with serum antibody titers against a single epitope near the C-terminus of OspA, as defined by the mouse monoclonal antibody (MAb), LA-2. However, the breadth of the human antibody response to OspA following vaccination remains undefined even as next-generation multivalent OspA-based vaccines are under development. In this report, we employed hydrogen exchange-mass spectrometry (HX-MS) to localize the epitopes recognized by a unique panel of OspA human MAbs, including four shown to passively protect mice against experimental B. burgdorferi infection and one isolated from a patient with antibiotic refractory Lyme arthritis. The epitopes grouped into three spatially distinct bins that, together, encompass more than half the surface-exposed area of OspA. The bins corresponded to OspA β-strands 8-10 (bin 1), 11-13 (bin 2), and 16-20 plus the C-terminal α-helix (bin 3). Bin 3 was further divided into sub-bins relative to LA-2's epitope. MAbs with complement-dependent borreliacidal activity, as well as B. burgdorferi transmission-blocking activity in the mouse model were found within each bin. Therefore, the resulting B cell epitope map encompasses functionally important targets on OspA that likely contribute to immunity to B. burgdorferi.

Assessment Structure, Culture, and Resources at US AAVMC-Accredited Colleges of Veterinary Medicine

While outcomes assessment is commonplace in colleges of veterinary medicine, no information is published on how veterinary colleges resource, administer, and view assessment. Consequently, this article has the following objectives: (a) to determine the current level of resources (personnel, committees, software) allocated toward education assessment and program evaluation in colleges of veterinary medicine, (b) to characterize any common organizational structures within colleges of veterinary medicine for assessment, (c) to determine assessment personnel (faculty and staff) perceptions regarding whether existing assessment resources and structures are sufficient, and (d) to examine the perceived strength of the culture of assessment. Our survey found that most assessment professionals had been in their position for 4 years or less and over 50% did not have formal assessment training. A majority of respondents agreed that assessment was encouraged and supported at their institution, but there was much less agreement on items related to formal plans and structures. For example, only one quarter of respondents reported that assessment was connected to planning and budgeting, and only one third reported having a formal assessment plan. We hope that our survey will be a resource tracking the development of assessment resources and climate at American colleges of veterinary medicine.

Single-domain antibodies neutralize ricin toxin intracellularly by blocking access to ribosomal P-stalk proteins

During ricin intoxication in mammalian cells, ricin's enzymatic (RTA) and binding (RTB) subunits disassociate in the endoplasmic reticulum. RTA is then translocated into the cytoplasm where, by virtue of its ability to depurinate a conserved residue within the sarcin-ricin loop (SRL) of 28S rRNA, it functions as a ribosome-inactivating protein. It has been proposed that recruitment of RTA to the SRL is facilitated by ribosomal P-stalk proteins, whose C-terminal domains interact with a cavity on RTA normally masked by RTB; however, evidence that this interaction is critical for RTA activity within cells is lacking. Here, we characterized a collection of single-domain antibodies (V_HHs) whose epitopes overlap with the P-stalk binding pocket on RTA. The crystal structures of three such V_HHs (V9E1, V9F9, and V9B2) in complex with RTA revealed not only occlusion of the ribosomal P-stalk binding pocket but also structural mimicry of C-terminal domain peptides by complementarity-determining region 3. In vitro assays confirmed that these V_HHs block RTA-P-stalk peptide interactions and protect ribosomes from depurination. Moreover, when expressed as "intrabodies," these V_HHs rendered cells resistant to ricin intoxication. One V_HH (V9F6), whose epitope was structurally determined to be immediately adjacent to the P-stalk binding pocket, was unable to neutralize ricin within cells or protect ribosomes from RTA in vitro. These findings are consistent with the recruitment of RTA to the SRL by ribosomal P-stalk proteins as a requisite event in ricin-induced ribosome inactivation.

Structural Analysis of Toxin-Neutralizing, Single-Domain Antibodies that Bridge Ricin's A-B Subunit Interface

Ricin toxin kills mammalian cells with notorious efficiency. The toxin's B subunit (RTB) is a Gal/GalNAc-specific lectin that attaches to cell surfaces and promotes retrograde transport of ricin's A subunit (RTA) to the trans Golgi network (TGN) and endoplasmic reticulum (ER). RTA is liberated from RTB in the ER and translocated into the cell cytoplasm, where it functions as a ribosome-inactivating protein. While antibodies against ricin's individual subunits have been reported, we now describe seven alpaca-derived, single-domain antibodies (V_HHs) that span the RTA-RTB interface, including four Tier 1 V_HHs with IC₅₀ values <1 nM. Crystal structures of each V_HH bound to native ricin holotoxin revealed three different binding modes, based on contact with RTA's F-G loop (mode 1), RTB's subdomain 2γ (mode 2) or both (mode 3). V_HHs in modes 2 and 3 were highly effective at blocking ricin attachment to HeLa cells and immobilized asialofetuin, due to framework residues (FR3) that occupied the 2γ Gal/GalNAc-binding pocket and mimic ligand. The four Tier 1 V_HHs also interfered with intracellular functions of RTB, as they neutralized ricin in a post-attachment cytotoxicity assay (e.g., the toxin was bound to cell surfaces before antibody addition) and reduced the efficiency of toxin transport to the TGN. We conclude that the RTA-RTB interface is a target of potent toxin-neutralizing antibodies that interfere with both extracellular and intracellular events in ricin's cytotoxic pathway.

Blocking Borrelia burgdorferi transmission from infected ticks to nonhuman primates with a human monoclonal antibody

Disrupting transmission of Borrelia burgdorferi sensu lato complex (B. burgdorferi) from infected ticks to humans is one strategy to prevent the significant morbidity from Lyme disease. We have previously shown that an anti-OspA human mAb, 2217, prevents transmission of B. burgdorferi from infected ticks in animal models. Maintenance of a protective plasma concentration of a human mAb for tick season presents a significant challenge for a preexposure prophylaxis strategy. Here, we describe the optimization of mAb 2217 by amino acid substitutions (2217LS: M428L and N434S) in the Fc domain. The LS mutation led to a 2-fold increase in half-life in cynomolgus monkeys. In a rhesus macaque model, 2217LS protected animals from tick transmission of spirochetes at a dose of 3 mg/kg. Crystallographic analysis of Fab in complex with OspA revealed that 2217 bound an epitope that was highly conserved among the B. burgdorferi, B. garinii, and B. afzelii species. Unlike most vaccines that may require boosters to achieve protection, our work supports the development of 2217LS as an effective preexposure prophylaxis in Lyme-endemic regions, with a single dose at the beginning of tick season offering immediate protection that remains for the duration of exposure risk.

Challenges to Implementation of the Co-Curriculum in Accredited Pharmacy Programs

Objective. To determine areas of concern, and challenges to implementing and assessing the co-curriculum in accredited Doctor of Pharmacy programs, along with how confident programs are in their ability to meet the co-curriculum requirement as mandated by the Accreditation Council for Pharmacy Education (ACPE).Methods. A survey was administered to all ACPE-accredited pharmacy programs to collect information regarding areas of concern, challenges, and confidence in their ability to meet the co-curriculum requirement. The frequency of responses to items are presented along with comparisons based on characteristics, including institution type, cohort size, most recent ACPE accreditation review, and supporting offices.Results. The most common concerns centered on the documentation and assessment process. The most commonly reported challenges were lack of enthusiasm or buy-in from faculty, staff, and students; lack of a clear definition of co-curriculum; and faculty time and insufficient staff. Overall, programs had a high level of confidence in their ability to meet the requirements for co-curriculum. The only differences found were related to supporting offices and cohort size.Conclusion. The results suggest that having supporting offices may reduce the co-curriculum burden. Similarly, student cohort size may have an impact on the challenges for some programs, particularly those with moderate-sized cohorts reporting challenges related to faculty and staff. Further research is needed to determine how programs address these critical issues, and to explore whether programs report differently on these areas after completing an accreditation review. The study results may be useful to members of the Academy when evaluating co-curriculum.

Structural basis for the interaction of Shiga toxin 2a with a C-terminal peptide of ribosomal P stalk proteins

The principal virulence factor of human pathogenic enterohemorrhagic Escherichia coli is Shiga toxin (Stx). Shiga toxin 2a (Stx2a) is the subtype most commonly associated with severe disease outcomes such as hemorrhagic colitis and hemolytic uremic syndrome. The catalytic A1 subunit (Stx2A1) binds to the conserved elongation factor binding C-terminal domain (CTD) of ribosomal P stalk proteins to inhibit translation. Stx2a holotoxin also binds to the CTD of P stalk proteins because the ribosome-binding site is exposed. We show here that Stx2a binds to an 11-mer peptide (P11) mimicking the CTD of P stalk proteins with low micromolar affinity. We cocrystallized Stx2a with P11 and defined their interactions by X-ray crystallography. We found that the last six residues of P11 inserted into a shallow pocket on Stx2A1 and interacted with Arg-172, Arg-176, and Arg-179, which were previously shown to be critical for binding of Stx2A1 to the ribosome. Stx2a formed a distinct P11-binding mode within a different surface pocket relative to ricin toxin A subunit and trichosanthin, suggesting different ribosome recognition mechanisms for each ribosome inactivating protein (RIP). The binding mode of Stx2a to P11 is also conserved among the different Stx subtypes. Furthermore, the P stalk protein CTD is flexible and adopts distinct orientations and interaction modes depending on the structural differences between the RIPs. Structural characterization of the Stx2a-ribosome complex is important for understanding the role of the stalk in toxin recruitment to the sarcin/ricin loop and may provide a new target for inhibitor discovery.

Co-Curriculum Implementation and Assessment in Accredited Doctor of Pharmacy Programs

Objective. To determine how accredited Doctor of Pharmacy programs implement and evaluate the co-curriculum requirement as mandated by the Accreditation Council for Pharmacy Education (ACPE). Methods. A survey was administered to all ACPE-accredited pharmacy programs to collect information regarding how co-curriculum models were being implemented, including types of activities, structure, learning outcomes, oversight, and assessment. The frequency of responses to items were presented to describe the general features of co-curriculum models. Results. The types of co-curricular activities reported by programs were generally consistent, with the majority of programs categorizing these activities and allowing students to choose which they would engage in. Most respondents reported that the program mapped co-curricular activities to learning outcomes, primarily ACPE Standards 1-4. The structural oversight of the co-curriculum typically included a co-curriculum committee, subcommittee, or task force, and supporting offices. The most common offices/departments involved in the co-curriculum were assessment, student affairs/services, experiential education, and academic/curricular affairs. The most common assessments were reflections, self-assessment surveys, and checklists. Conclusion. In most programs, implementation of the co-curriculum was a joint effort among various individuals, committees, and offices. Given the developing nature of programs, descriptive studies should be repeated to identify how programs develop and enhance co-curriculum models. The study results may be useful to members of the Academy when evaluating the current state of co-curriculum implementation and potential areas for program development.

Intracellular Neutralization of Ricin Toxin by Single-domain Antibodies Targeting the Active Site

The extreme potency of the plant toxin, ricin, is due to its enzymatic subunit, RTA, which inactivates mammalian ribosomes with near-perfect efficiency. Here we characterized, at the functional and structural levels, seven alpaca single-domain antibodies (VHHs) previously reported to recognize epitopes in proximity to RTA's active site. Three of the VHHs, V2A11, V8E6, and V2G10, were potent inhibitors of RTA in vitro and protected Vero cells from ricin when expressed as intracellular antibodies ("intrabodies"). Crystal structure analysis revealed that the complementarity-determining region 3 (CDR3) elements of V2A11 and V8E6 penetrate RTA's active site and interact with key catalytic residues. V2G10, by contrast, sits atop the enzymatic pocket and occludes substrate accessibility. The other four VHHs also penetrated/occluded RTA's active site, but lacked sufficient binding affinities to outcompete RTA-ribosome interactions. Intracellular delivery of high-affinity, single-domain antibodies may offer a new avenue in the development of countermeasures against ricin toxin.toxin, antibody, structure, intracellular.

Best Practices Related to Examination Item Construction and Post-hoc Review

Objective. To provide a practical guide to examination item writing, item statistics, and score adjustment for use by pharmacy and other health professions educators. Findings. Each examination item type possesses advantages and disadvantages. Whereas selected response items allow for efficient assessment of student recall and understanding of content, constructed response items appear better suited for assessment of higher levels of Bloom's taxonomy. Although clear criteria have not been established, accepted ranges for item statistics and examination reliability have been identified. Existing literature provides guidance on when instructors should consider revising or removing items from future examinations based on item statistics and review, but limited information is available on performing score adjustments. Summary. Instructors should select item types that align with the intended learning objectives to be measured on the examination. Ideally, an examination will consist of multiple item types to capitalize on the advantages and limit the effects of any disadvantages associated with a specific item format. Score adjustments should be performed judiciously and by considering all available item information. Colleges and schools should consider developing item writing and score adjustment guidelines to promote consistency.

National Trends in the Adoption of Pharmacy Curriculum Outcomes Assessment for Student Assessment and Remediation

Objective. To determine and describe the current uses of the Pharmacy Curriculum Outcomes Assessment (PCOA) by US schools and colleges of pharmacy. Methods. Assessment professionals from 135 US schools and colleges of pharmacy were invited to complete a 38-item electronic survey. Survey items were designed to investigate common uses of the PCOA, cut points, and "stakes" assigned to the PCOA, identification of at-risk students, and remediation approaches. Results. The school response rate was 68%. The most common uses of the PCOA included curricular assessment (76%), individual student performance assessment (74%), and cohort performance assessment (71%). The PCOA was most frequently administered to third-year pharmacy (P3) students. The approach for assigning "stakes" to PCOA performance varied among programs depending on the student's professional year in the curriculum. Programs used a variety of approaches to establish the benchmark (or cut point) for PCOA performance. Remediation for at risk students was required by less than 25% of programs. Remediation was most commonly required for P3 students (22%). Conclusion. Survey results indicate wide variability between programs regarding PCOA cut points (benchmarks), stakes, and remediation approaches. In the future, it will be important for pharmacy educators to identify and study best practices for use of PCOA within student assessment and remediation plans.

A Study of the Relationship Between the PCOA and NAPLEX Using a Multi-institutional Sample

Objective. To examine the relationship between the Pharmacy Curriculum Outcomes Assessment (PCOA) and the North American Pharmacist Licensure Examination (NAPLEX) using a large, multi-institutional sample of student scores. Methods. A matched dataset was obtained from the National Association of Boards of Pharmacy (NABP) consisting of examination scores for the 1,460 students who completed both the PCOA and the NAPLEX between 2012 and 2015 at six schools/colleges of pharmacy (S/COPs). Bivariate correlations were estimated for total and content area scores on both examinations. Students' total NAPLEX scores were predicted using linear regression models containing total and content area scores on PCOA and dummy variables for S/COP and year. Results. Students' PCOA total score and NAPLEX total score were significantly and moderately correlated (r=0.54). All correlations between PCOA and NAPLEX total and content area scores were significant. and ranged from r=0.22 to 0.56. Regression results showed pharmaceutical and clinical sciences PCOA content scores were significant predictors of NAPLEX total score while basic biomedical sciences and social/behavioral/administrative sciences were not. The PCOA total and content scores accounted for 30%-33% of the variance in total NAPLEX score. Conclusion. Student PCOA and NAPLEX total and content area scores were significantly correlated, which is consistent with the findings of previous research. The somewhat modest proportion of variance in NAPLEX scores accounted for by PCOA scores illustrates the need for use of additional performance measures when evaluating student preparedness for the NAPLEX. This study provides important baseline data that can be used by S/COPs for comparison with their own student data as well as by researchers seeking to conduct additional analyses following recent changes in the PCOA and NAPLEX blueprints.

Factors associated with cultures of assessment at US schools and colleges of pharmacy

INTRODUCTION

Pharmacy education has standards for assessment that must be met, prompting many programs to develop cultures of assessment. This study assesses the extent to which assessment personnel perceive that a culture of assessment has been established within their schools/colleges of pharmacy (S/COPs) and determines whether a relationship exists between assessment structure and the perceived strength of the culture of assessment.

METHODS

An electronic survey was administered to assessment personnel at 134 S/COPs. Respondents were asked about changes within the past five years pertaining to assessment personnel/committees and factors prompting these changes. They were also asked to rate items related to support for institutional assessment (SIA scale) and faculty engagement with assessment (FEA scale). The reliability of each scale was estimated using Cronbach alpha and bivariate correlations were conducted to estimate the relationships among the two scales and other survey items.

RESULTS

The S/COP response rate was 84% (113/134). Most (58%) noted the formation or re-structuring of the assessment office, with 26% creating one or more new assessment positions. The most common source of change was new accreditation standards (55%) followed by a new leadership position created in assessment (40%). Cronbach alpha for the SIA scale was 0.79 and 0.84 for the FEA scale. Program size was strongly negatively correlated with school age (r_s = -0.58) and the FEA scale (r = -0.21).

CONCLUSIONS

There was a strong relationship between SIA and FEA. Future studies are warranted to determine the interdependency of support for assessment and faculty engagement with assessment.

Surveying the current landscape of assessment structures and resources in US schools and colleges of pharmacy

INTRODUCTION

Expectations for assessment in higher education have increased in recent decades, prompting institutions to invest additional resources in this area. This study aimed to determine the resources, structure, and perception of assessment resources in United States schools and colleges of pharmacy (S/COPs).

METHODS

Assessment personnel in S/COPs were surveyed electronically. Information collected included S/COP demographics, composition of assessment positions, experience and training of assessment personnel, and structure and responsibilities of committees engaged in assessment. Respondents' perception of their S/COPs having sufficient assessment personnel, recent changes in assessment, and the factors that prompted assessment changes were also surveyed.

RESULTS

Respondents included individuals from 113 S/COPs (84% response rate). Most S/COPs had 1-2 assessment positions and 1-2 assessment-related committees. The most common assessment position titles were assistant/associate dean, director, coordinator/specialist, and administrative assistant. Dean-level administrators typically had worked in assessment the longest, whereas directors were more likely to have formal assessment training. Most respondents (75%) agreed they had sufficient assessment personnel to meet the 2007 Accreditation Council for Pharmacy Education Standards. Nearly two-thirds of respondents agreed they had sufficient personnel to meet the 2016 Standards and support their current assessment plan/process. Most S/COPs had a formal assessment committee (93%) and an average of two committees overseeing assessment.

CONCLUSION

Most S/COPs reported having sufficient resources to support assessment activities. Although there were some consistent themes, there does not appear to be a single model for structuring assessment resources or committees. Effectiveness of various assessment structures represents an area for future research.

Best Practices on Examination Construction, Administration, and Feedback

Examinations are typically used in higher education to objectively assess student learning, and they are also used as a frequent assessment tool in the Doctor of Pharmacy curriculum. This paper describes best practices and provides examples for faculty to build reliable and valid examinations, ensure examination security and deter academic misconduct, and enhance student learning and achievement of course objectives. Colleges and schools of pharmacy can incorporate these concepts into comprehensive examination policies and focus faculty development efforts on improving the examination purpose, design, and experience for both faculty and students.

Contribution of an unusual CDR2 element of a single domain antibody in ricin toxin binding affinity and neutralizing activity

Ricin toxin's enzymatic subunit (RTA) has been subjected to intensive B cell epitope mapping studies using a combination of competition ELISAs, hydrogen exchange-mass spectrometry and X-ray crystallography. Those studies identified four spatially distinct clusters (I-IV) of toxin-neutralizing epitopes on the surface of RTA. Here we describe A9, a new single domain camelid antibody (VHH) that was proposed to recognize a novel epitope on RTA that straddles clusters I and III. The X-ray crystal structure of A9 bound to RTA (2.6 Å resolution) revealed extensive antibody contact with RTA's β-strand h (732 Å2 buried surface area; BSA), along with limited engagement with α-helix D (90 Å2) and α-helix C (138 Å2). Collectively, these contacts explain the overlap between epitope clusters I and III, as identified by competition ELISA. However, considerable binding affinity, and, consequently, toxin-neutralizing activity of A9 is mediated by an unusual CDR2 containing five consecutive Gly residues that interact with α-helix B (82 Å2), a known neutralizing hotspot on RTA. Removal of a single Gly residue from the penta-glycine stretch in CDR2 reduced A9's binding affinity by 10-fold and eliminated toxin-neutralizing activity. Computational modeling indicates that removal of a Gly from CDR2 does not perturb contact with RTA per se, but results in the loss of an intramolecular hydrogen bond network involved in stabilizing CDR2 in the unbound state. These results reveal a novel configuration of a CDR2 element involved in neutralizing ricin toxin.

Faculty motivations to use active learning among pharmacy educators

INTRODUCTION

Faculty motivations to use active learning have been limited to surveys evaluating faculty perceptions within active learning studies. Our objective in this study was to evaluate the relationship between faculty intrinsic motivation, extrinsic motivation, and demographic variables and the extent of active learning use in the classroom.

METHODS

An online survey was administered to individual faculty members at 137 colleges and schools of pharmacy across the United States. The survey assessed intrinsic and extrinsic motivations, active learning strategies, classroom time dedicated to active learning, and faculty development resources. Bivariate associations and multivariable stepwise linear regression were used to analyze the results.

RESULTS

In total, 979 faculty members completed the questionnaire (23.6% response rate). All motivation variables were significantly correlated with percent active learning use (p < 0.001). Intrinsic motivation demonstrated the highest correlation (r = 0.447) followed by current extrinsic motivations (r = 0.245) and ideal extrinsic motivations (r = 0.291). Variables associated with higher intrinsic motivation included the number of resources used (r = 0.233, p < 0.001) and the number of active learning methods used in the last year (r = 0.259, p < 0.001). Years of teaching experience was negatively associated with intrinsic motivation (r = -0.177, p < 0.001). Regression analyses confirmed the importance of intrinsic and extrinsic motivations in predicting active learning use.

DISCUSSION AND CONCLUSIONS

Our results suggest that faculty members who are intrinsically motivated to use active learning are more likely to dedicate additional class time to active learning. Furthermore, intrinsic motivation may be positively associated with encouraging faculty members to attend active learning workshops and supporting faculty to use various active learning strategies in the classroom.

Creating an Arms Race? Examining School Costs and Motivations for Providing NAPLEX and PCOA Preparation

Objective. To examine the extent of financial and faculty resources dedicated to preparing students for NAPLEX and PCOA examinations, and how these investments compare with NAPLEX pass rates. Methods. A 23-item survey was administered to assessment professionals in U.S. colleges and schools of pharmacy (C/SOPs). Institutions were compared by type, age, and student cohort size. Institutional differences were explored according to the costs and types of NAPLEX and PCOA preparation provided, if any, and mean NAPLEX pass rates. Results. Of 134 C/SOPs that received the survey invitation, 91 responded. Nearly 80% of these respondents reported providing some form of NAPLEX preparation. Significantly higher 2015 mean NAPLEX pass rates were found in public institutions, schools that do not provide NAPLEX prep, and schools spending less than $10,000 annually on NAPLEX prep. Only 18 schools reported providing PCOA preparation. Conclusion. Investment in NAPLEX and PCOA preparation resources vary widely across C/SOPs but may increase in the next few years, due to dropping NAPLEX pass rates and depending upon how PCOA data are used.

Using homology modeling to interrogate binding affinity in neutralization of ricin toxin by a family of single domain antibodies

In this report we investigated, within a group of closely related single domain camelid antibodies (V_H Hs), the relationship between binding affinity and neutralizing activity as it pertains to ricin, a fast-acting toxin and biothreat agent. The V1C7-like V_H Hs (V1C7, V2B9, V2E8, and V5C1) are similar in amino acid sequence, but differ in their binding affinities and toxin-neutralizing activities. Using the X-ray crystal structure of V1C7 in complex with ricin's enzymatic subunit (RTA) as a template, Rosetta-based homology modeling coupled with energetic decomposition led us to predict that a single pairwise interaction between Arg29 on V5C1 and Glu67 on RTA was responsible for the difference in ricin toxin binding affinity between V1C7, a weak neutralizer, and V5C1, a moderate neutralizer. This prediction was borne out experimentally: substitution of Arg for Gly at position 29 enhanced V1C7's binding affinity for ricin, whereas the reverse (ie, Gly for Arg at position 29) diminished V5C1's binding affinity by >10 fold. As expected, the V5C1_R29G mutant was largely devoid of toxin-neutralizing activity (TNA). However, the TNA of the V1C7_G29R mutant was not correspondingly improved, indicating that in the V1C7 family binding affinity alone does not account for differences in antibody function. V1C7 and V5C1, as well as their respective point mutants, recognized indistinguishable epitopes on RTA, at least at the level of sensitivity afforded by hydrogen-deuterium mass spectrometry. The results of this study have implications for engineering therapeutic antibodies because they demonstrate that even subtle differences in epitope specificity can account for important differences in antibody function.

Structural Analysis of Single Domain Antibodies Bound to a Second Neutralizing Hot Spot on Ricin Toxin's Enzymatic Subunit

Ricin toxin is a heterodimer consisting of RTA, a ribosome-inactivating protein, and RTB, a lectin that facilitates receptor-mediated uptake into mammalian cells. In previous studies, we demonstrated that toxin-neutralizing antibodies target four spatially distinct hot spots on RTA, which we refer to as epitope clusters I-IV. In this report, we identified and characterized three single domain camelid antibodies (VHH) against cluster II. One of these VHHs, V5E1, ranks as one of the most potent ricin-neutralizing antibodies described to date. We solved the X-ray crystal structures of each of the three VHHs (E1, V1C7, and V5E1) in complex with RTA. V5E1 buries a total of 1,133 Å2 of surface area on RTA and makes primary contacts with α-helix A (residues 18-32), α-helix F (182-194), as well as the F-G loop. V5E1, by virtue of complementarity determining region 3 (CDR3), may also engage with RTB and potentially interfere with the high affinity galactose-recognition element that plays a critical role in toxin attachment to cell surfaces and intracellular trafficking. The two other VHHs, E1 and V1C7, bind epitopes adjacent to V5E1 but display only weak toxin neutralizing activity, thereby providing structural insights into specific residues within cluster II that may be critical contact points for toxin inactivation.

Structural analysis of nested neutralizing and non-neutralizing B cell epitopes on ricin toxin's enzymatic subunit

In this report, we describe the X-ray crystal structures of two single domain camelid antibodies (VH H), F5 and F8, each in complex with ricin toxin's enzymatic subunit (RTA). F5 has potent toxin-neutralizing activity, while F8 has weak neutralizing activity. F5 buried a total of 1760 Å(2) in complex with RTA and made contact with three prominent secondary structural elements: α-helix B (Residues 98-106), β-strand h (Residues 113-117), and the C-terminus of α-helix D (Residues 154-156). F8 buried 1103 Å(2) in complex with RTA that was centered primarily on β-strand h. As such, the structural epitope of F8 is essentially nested within that of F5. All three of the F5 complementarity determining regions CDRs were involved in RTA contact, whereas F8 interactions were almost entirely mediated by CDR3, which essentially formed a seventh β-strand within RTA's centrally located β-sheet. A comparison of the two structures reported here to several previously reported (RTA-VH H) structures identifies putative contact sites on RTA, particularly α-helix B, associated with potent toxin-neutralizing activity. This information has implications for rational design of RTA-based subunit vaccines for biodefense. Proteins 2016; 84:1162-1172. © 2016 Wiley Periodicals, Inc.

Structures of paraoxon-inhibited human acetylcholinesterase reveal perturbations of the acyl loop and the dimer interface

Irreversible inhibition of the essential nervous system enzyme acetylcholinesterase by organophosphate nerve agents and pesticides may quickly lead to death. Oxime reactivators currently used as antidotes are generally less effective against pesticide exposure than nerve agent exposure, and pesticide exposure constitutes the majority of cases of organophosphate poisoning in the world. The current lack of published structural data specific to human acetylcholinesterase organophosphate-inhibited and oxime-bound states hinders development of effective medical treatments. We have solved structures of human acetylcholinesterase in different states in complex with the organophosphate insecticide, paraoxon, and oximes. Reaction with paraoxon results in a highly perturbed acyl loop that causes a narrowing of the gorge in the peripheral site that may impede entry of reactivators. This appears characteristic of acetylcholinesterase inhibition by organophosphate insecticides but not nerve agents. Additional changes seen at the dimer interface are novel and provide further examples of the disruptive effect of paraoxon. Ternary structures of paraoxon-inhibited human acetylcholinesterase in complex with the oximes HI6 and 2-PAM reveals relatively poor positioning for reactivation. This study provides a structural foundation for improved reactivator design for the treatment of organophosphate intoxication. Proteins 2016; 84:1246-1256. © 2016 Wiley Periodicals, Inc.

Structural genomics for drug design against the pathogen Coxiella burnetii

Coxiella burnetii is a highly infectious bacterium and potential agent of bioterrorism. However, it has not been studied as extensively as other biological agents, and very few of its proteins have been structurally characterized. To address this situation, we undertook a study of critical metabolic enzymes in C. burnetii that have great potential as drug targets. We used high-throughput techniques to produce novel crystal structures of 48 of these proteins. We selected one protein, C. burnetii dihydrofolate reductase (CbDHFR), for additional work to demonstrate the value of these structures for structure-based drug design. This enzyme's structure reveals a feature in the substrate binding groove that is different between CbDHFR and human dihydrofolate reductase (hDHFR). We then identified a compound by in silico screening that exploits this binding groove difference, and demonstrated that this compound inhibits CbDHFR with at least 25-fold greater potency than hDHFR. Since this binding groove feature is shared by many other prokaryotes, the compound identified could form the basis of a novel antibacterial agent effective against a broad spectrum of pathogenic bacteria.

Crystal structures of ricin toxin's enzymatic subunit (RTA) in complex with neutralizing and non-neutralizing single-chain antibodies

Ricin is a select agent toxin and a member of the RNA N-glycosidase family of medically important plant and bacterial ribosome-inactivating proteins. In this study, we determined X-ray crystal structures of the enzymatic subunit of ricin (RTA) in complex with the antigen binding domains (VHH) of five unique single-chain monoclonal antibodies that differ in their respective toxin-neutralizing activities. None of the VHHs made direct contact with residues involved in RTA's RNA N-glycosidase activity or induced notable allosteric changes in the toxin's subunit. Rather, the five VHHs had overlapping structural epitopes on the surface of the toxin and differed in the degree to which they made contact with prominent structural elements in two folding domains of the RTA. In general, RTA interactions were influenced most by the VHH CDR3 (CDR, complementarity-determining region) elements, with the most potent neutralizing antibody having the shortest and most conformationally constrained CDR3. These structures provide unique insights into the mechanisms underlying toxin neutralization and provide critically important information required for the rational design of ricin toxin subunit vaccines.

Rapid countermeasure discovery against Francisella tularensis based on a metabolic network reconstruction

In the future, we may be faced with the need to provide treatment for an emergent biological threat against which existing vaccines and drugs have limited efficacy or availability. To prepare for this eventuality, our objective was to use a metabolic network-based approach to rapidly identify potential drug targets and prospectively screen and validate novel small-molecule antimicrobials. Our target organism was the fully virulent Francisella tularensis subspecies tularensis Schu S4 strain, a highly infectious intracellular pathogen that is the causative agent of tularemia and is classified as a category A biological agent by the Centers for Disease Control and Prevention. We proceeded with a staggered computational and experimental workflow that used a strain-specific metabolic network model, homology modeling and X-ray crystallography of protein targets, and ligand- and structure-based drug design. Selected compounds were subsequently filtered based on physiological-based pharmacokinetic modeling, and we selected a final set of 40 compounds for experimental validation of antimicrobial activity. We began screening these compounds in whole bacterial cell-based assays in biosafety level 3 facilities in the 20th week of the study and completed the screens within 12 weeks. Six compounds showed significant growth inhibition of F. tularensis, and we determined their respective minimum inhibitory concentrations and mammalian cell cytotoxicities. The most promising compound had a low molecular weight, was non-toxic, and abolished bacterial growth at 13 µM, with putative activity against pantetheine-phosphate adenylyltransferase, an enzyme involved in the biosynthesis of coenzyme A, encoded by gene coaD. The novel antimicrobial compounds identified in this study serve as starting points for lead optimization, animal testing, and drug development against tularemia. Our integrated in silico/in vitro approach had an overall 15% success rate in terms of active versus tested compounds over an elapsed time period of 32 weeks, from pathogen strain identification to selection and validation of novel antimicrobial compounds.

Structures of human acetylcholinesterase in complex with pharmacologically important ligands

Human acetylcholinesterase (AChE) is a significant target for therapeutic drugs. Here we present high resolution crystal structures of human AChE, alone and in complexes with drug ligands; donepezil, an Alzheimer's disease drug, binds differently to human AChE than it does to Torpedo AChE. These crystals of human AChE provide a more accurate platform for further drug development than previously available.

Dental caries prevalence in children attending special needs schools in Johannesburg, Gauteng Province, South Africa

INTRODUCTION

Anecdotal evidence from clinical data in Johannesburg suggests that there is a high burden of dental caries among children with special health care needs (CSHCN) in Johannesburg.

OBJECTIVES

To determine the prevalence of dental caries and Unmet Treatment Needs in children with cerebral palsy, hearing, learning and mental disabilities attending special needs schools in Johannesburg and to compare these with data from the National Children's Oral Health Survey (NCOHS) METHODS: This cross-sectional analytical study comprised of 882 children attending five special needs schools in Johannesburg. Stratified randomised sampling of the participating schools was done and the schools were stratified by disability. Caries status was recorded via the dmft/DMFT index using WHO criteria and guidelines.

RESULTS

The mean age of the participants was 10.5 years; with a caries prevalence of 27.55% and 33.56% in the primary and permanent dentition respectively. The highest unmet treatment need of 100% was found in the permanent dentition of the hearing impaired group followed by 90.77% in the primary dentition of the cerebral palsy group. In general no significant difference was found when the dmft/DMFT for CSHCN and NCOHS were compared except in the hearing impaired age groups four to five and six (both primary dentition) where significantly higher dmft scores (3.58 vs. 2.4; 3.85 vs. 2.9; p < 0.05) were found.

CONCLUSION

Children with special health care needs had lower caries prevalence compared with the general population and higher unmet treatment needs regardless of the type of disability.

Caries status among children in the West Rand District of Gauteng Province, South Africa

INTRODUCTION

There is a lack of data about the prevalence and clinical consequences of dental caries in the West Rand. However dental caries does appear to be a substantial public health problem in Gauteng.

OBJECTIVE

This study set out to determine the prevalence and clinical consequences of dental caries among school children in the West Rand district of Gauteng.

METHODOLOGY

This was a cross-sectional study comprised of 800 pre-school and primary school children six to eight years old. Cluster sampling was used to select the participating schools. The oral health status was determined by using the DMFT/dmft and PUFA/pufa indices.

RESULTS

Of the 800 children, 282 were in the four to five year old age group and 518 were six to eight years old. For four to five year olds the mean dmft score was 2.24 and the prevalence of caries 49%. The clinical consequence of caries was scored with a mean pufa index of 2.9 and the percentage of untreated decay was 47%. For six to eight year olds the mean DMFT/dmft scores were 0.1 and 2.4 respectively and the prevalence of caries 46%. The clinical consequence of caries scored with the PUFA/pufa index was 0.0 and 3.4 respectively and the percentage of untreated decay was 44%.

CONCLUSION

There are high levels of untreated caries in children in this district. The pufa scores ndicate that children suffer serious consequences of untreated decay.

The impact of service-learning on two groups of South African dental students

Service-learning has become an important component in the education of medical and dental students around the world. Dental students at the University of Witwatersrand, South Africa, provide dental services to rural communities via the Phelophepa train or a Public Oral Health Facility (POHF). The Phelophepa train is a mobile primary health care facility offering dental, pharmacy, nursing, and medical services provided by health professions students. The objective of this study was to determine the impact this experience with service-learning has had on dental students. Final-year dental students in 2008 and 2009 participated in the study by completing a self-administered questionnaire. There was a 100 percent response rate (N=55) on the demographic questions and a 98 percent response rate (N=54) on the opinion questions. Students on the Phelophepa train performed more extractions and examinations than those at the POHFs. Most students (95 percent), both on the train and at the clinics, reported that their clinical skills and efficiency had improved, and 96 percent felt more aware of the communities' needs. Almost all the students (96 percent) reported that the experience had helped them define their personal strengths and weaknesses. Complaints they mentioned included large numbers of patients (87 percent), long working hours (60 percent), and equipment being inadequate (48 percent) or not working (40 percent). This program positively impacted these students and enhanced their personal growth and social responsibility by exposing them to the needs of rural and urban communities in South Africa.

Teachers' knowledge of emergency management of traumatised teeth in preschools

Dental trauma remains one of the major oral health problems in childhood and is the cause of much pain and distress. It may occur as a result of a sports mishap, an altercation or a fall while playing inside the school premises. Prompt and appropriate management of traumatised teeth is essential for a good prognosis of an injured tooth.

AIM AND OBJECTIVE

The aim of the study was to assess teachers' knowledge of emergency management of traumatized teeth in early childhood developmental centres (ECDCs).

METHOD

A cross sectional self-administered questionnaire was used to collect data among teachers in ECDCs in Hillbrow and Berea suburbs, Johannesburg, South Africa.

RESULTS AND CONCLUSION

Almost all respondents (98.1%) were female; 59.6% were between 20 and 29 years of age. Almost a quarter of the centres were not registered and 39.1% of the school teachers were not formally qualified as ECDCs teachers. A small percentage (11.5%) received dental emergency training as a part of their school health education programs. Knowledge of ECDCs teachers on the emergency management of traumatized teeth appeared inadequate; in the event of emergency dental trauma, substantial number of teachers would not be able to respond appropriately. All teachers should have training on basic management of dental trauma.

An inhibited conformation for the protein kinase domain of the Saccharomyces cerevisiae AMPK homolog Snf1

AMP-activated protein kinase (AMPK) is a master metabolic regulator for controlling cellular energy homeostasis. Its homolog in yeast, SNF1, is activated in response to glucose depletion and other stresses. The catalytic (alpha) subunit of AMPK/SNF1 in yeast (Snf1) contains a protein Ser/Thr kinase domain (KD), an auto-inhibitory domain (AID) and a region that mediates interactions with the two regulatory (beta and gamma) subunits. Here, the crystal structure of residues 41-440 of Snf1, which include the KD and AID, is reported at 2.4 A resolution. The AID is completely disordered in the crystal. A new inhibited conformation of the KD is observed in a DFG-out conformation and with the glycine-rich loop adopting a structure that blocks ATP binding to the active site.

Predicting HIV in a public dental facility using group I oral lesions

Group I oral lesions have been strongly associated with HIV and in resource-poor settings could be useful predictors of HIV. No study has evaluated the predictability of these lesions in diagnosing HIV/AIDS in patients who attend dental public facilities in South Africa.

OBJECTIVES

To determine the HIV status, prevalence of Group I oral lesions and their predictive value amongst patients attending a dental clinic in Soweto, South Africa.

METHODS

This cross sectional analytical study comprised of adult patients attending a dental facility over one week in 2006. All patients underwent a clinical examination by calibrated dentists.

RESULTS

A total of 165 patients (100% response) were screened of which 87 (53%) were female. The HIV prevalence was 28% (n = 46) and of those who tested positive, 15% (7) manifested with Necrotizing Ulcerative Gingivitis (NUG). This proved to be highly predictive for HIV (positive predictive value = 93.8%, specificity = 99.6% and likelihood ratio = 40).

CONCLUSION

The high prevalence rate of HIV in dental facilities confirms the heavy burden of the HIV epidemic. NUG proved to be a good predictor of HIV in this setting.

Attitudes of South African dental therapy students toward compulsory community service

Compulsory community service (CCS) was introduced into the health service by the South African government to address the shortage and maldistribution of health professionals within the public sector. The aim of this study was to determine the attitudes of dental therapy students regarding CCS. A self-administered questionnaire was delivered to the two dental schools that train dental therapists in South Africa. There was a 64 percent response rate; 56 percent of the respondents were female. The average age was 20.3 years. There was no difference in the variables between the two dental schools, so the results were combined. The majority (81 percent) supported the introduction of CCS and preferred to carry it out in Kwa-Zulu Natal. Most students opted to perform oral health promotional (64 percent) and clinical (15 percent) activities. By aligning these requirements with the current dental needs and priority strategies of the South African Department of Health, this support would add much value to the delivery of oral health services.

Management of the oral manifestations of HIV/AIDS by traditional healers and care givers

In many communities of South Africa, traditional healers are often the only means of health care delivery available. The level of knowledge and ability to recognize oral lesions of 32 traditional healers and 17 care-givers were assessed after a two-day workshop. The data collection instrument was a structured questionnaire, complimented by enlarged clinical photographs of the common oral manifestations of HIV/AIDS. Prior to the workshop, 46 (93.9%) of the 49 respondents had never had any formal information on oral health and 43 (87.8%) were unfamiliar with the symptoms of oral diseases. Thirty-five (71.4%) recognized bleeding gums from A4-size photographs and 11 (22.4%) recognized oral thrush. The recognition of other oral manifestations of HIV/AIDS were; oral hairy leukoplakia (41.0%), angular cheilitis (43.6%), herpes virus infection (56.4%), oral ulcerations (56.8%), and in children, parotid enlargement (27.3%), and moluscum contagiosum (56.8%). Traditional healers and caregivers constitute an untapped resource with enormous potential. A positive bridge should be built to link traditional healing with modem medicine in the struggle against HIV/AIDS.

Crystal structure of the heterotrimer core of Saccharomyces cerevisiae AMPK homologue SNF1

AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis in mammals and is an attractive target for drug discovery against diabetes, obesity and other diseases. The AMPK homologue in Saccharomyces cerevisiae, known as SNF1, is essential for responses to glucose starvation as well as for other cellular processes, although SNF1 seems to be activated by a ligand other than AMP. Here we report the crystal structure at 2.6 A resolution of the heterotrimer core of SNF1. The ligand-binding site in the gamma-subunit (Snf4) has clear structural differences from that of the Schizosaccharomyces pombe enzyme, although our crystallographic data indicate that AMP can also bind to Snf4. The glycogen-binding domain in the beta-subunit (Sip2) interacts with Snf4 in the heterotrimer but should still be able to bind carbohydrates. Our structure is supported by a large body of biochemical and genetic data on this complex. Most significantly, the structure reveals that part of the regulatory sequence in the alpha-subunit (Snf1) is sequestered by Snf4, demonstrating a direct interaction between the alpha- and gamma-subunits and indicating that our structure may represent the heterotrimer core of SNF1 in its activated state.

Occupational exposures among dental assistants in public health care facilities, Limpopo Province

The risk of dental assistants acquiring injury and infections from the dental clinics has received little attention, especially in South Africa.

OBJECTIVES

To determine the prevalence of occupational exposures among dental assistants working in public health care facilities in Limpopo Province.

METHODS

A cross-section study on infection control practice and occupational exposures was conducted among 73 dental assistants.

RESULTS

The sample was predominantly female (95%) with a mean age of 40.2 years (age range 23-54 years). Almost half the respondents (49.1%) had no formal training for their occupation, 22% were nursing assistants and only 10.2% had qualified at a technical college (Technicon). The mean number of clinicians assisted by each participant was 3.8 (SD +/- 1.9). Nearly half of the dental assistants (n = 26) reported an occupational exposure, half of which in turn occurred while handling instruments and 42.3% while assisting. The most common type of injury was a direct puncture (65.3%). Treatment included antiretroviral therapy (19.2%) and wound-cleaning (38.4%), while 42.3% reported that they had had no treatment at all. About 23% of incidents were not reported. Eighty percent changed gloves routinely between patients but 67% did not use protective eye glasses; 62.7% were not vaccinated against HBV.

CONCLUSION

Occupational exposure was found to be unacceptably high and compliance of infection control guidelines was low.

Structure of the Bateman2 domain of yeast Snf4: dimeric association and relevance for AMP binding

AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis in mammals. AMP is believed to control the activity of AMPK by binding to the gamma subunit of this heterotrimeric enzyme. This subunit contains two Bateman domains, each of which is composed of a tandem pair of cystathionine beta-synthase (CBS) motifs. No structural information is currently available on this subunit, and the molecular basis for its interactions with AMP is not well understood. We report here the crystal structure at 1.9 Angstrom resolution of the Bateman2 domain of Snf4, the gamma subunit of the yeast ortholog of AMPK. The structure revealed a dimer of the Bateman2 domain, and this dimerization is supported by our light-scattering, mutagenesis, and biochemical studies. There is a prominent pocket at the center of this dimer, and most of the disease-causing mutations are located in or near this pocket.