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.