1012 A Close Loop Audit of Acute Food Bolus Obstruction at a District General Hospital

Aim

The British Society of Gastroenterology (BSG) recommends biopsies from two different regions in the oesophagus. A close loop audit was undertaken to assess performance at a district general hospital, against these guidelines and following newly agreed trust guidelines after the first audit cycle of a follow up OGD within 6 weeks of the presentation.

Method

Data was collected of patients admitted with a food bolus over the first cycle (March2019 to February 2021) and the second cycle (1/10/21 to 14/10/21). Exclusion criteria were age of less than 18 and sharp food bolus.

Results

69 patients were identified. Average age was 60 years. There were 67% male patients and 33% female. 20% of patients underwent a follow up OGD in the first cycle and 45%underwent a follow up OGD within six weeks. 7% had two regions biopsy in the first cycle and21% in the second cycle. Average OGD follow up time was 92 days in the first cycle and 59days in the second cycle. Commonest findings on histology results were eosinophilic oesophagitis and Barrett's oesophagus (22% each), GORD (15%) and carcinoma (7%).

Discussion

Food bolus obstruction indicates the presence of pathology of the oesophagus and should be investigated as so, even despite spontaneous recovery from the acute event. Number of patients undergoing OGD within six weeks and a two regions biopsy improved through this audit by implementing the new trust guidelines.

Scintillation light detection in the 6-m drift-length ProtoDUNE Dual Phase liquid argon TPC

DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6  ×  6  ×  6 m 3 liquid argon time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019-2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties.

Demonstrating the processes and outcomes of a rural Community Mental Health Rehabilitation Service: A realist evaluation

BACKGROUND

As part of significant mental health reform, the Community Mental Health Rehabilitation Service (CMHRS) was implemented in rural South Australia. The CMHRS is a 10-bed mental health residential program offering rehabilitative mental health support to rural residents.

AIM

To analyse the CMHRS service delivery model and its impact on recovery outcomes for consumers.

METHODS

A mixed method, realist evaluation approach was utilised. A purposive sample of CMHRS staff (n = 6) and consumers (n = 8) were recruited. Consumer recovery was measured using the RAS-DS (on admission and discharge). Participants' perspectives of the service were gained via one staff focus group (n = 6) and individual semi-structured interviews (consumers n = 6; staff n = 2). Pre-post RAS-DS scores were analysed using paired t-tests/Wilcoxon paired-signed rank test, with qualitative data analysed thematically.

RESULTS

Significant positive increases in RAS-DS total scores were observed at discharge, supported by the qualitative themes of (re)building relationships and social connections and recovering health and wellbeing. Contextual factors (e.g. staffing) and program mechanisms (e.g. scheduling) impacting on service implementation were identified.

CONCLUSION

Maintaining a rehabilitation recovery-focused approach, balanced with an appropriately trained multi-disciplinary team, are vital for maximising positive consumer outcomes.

SIGNIFICANCE

This realist evaluation identifies critical factors impacting rural mental health rehabilitation service delivery.

Prospects for beyond the Standard Model physics searches at the Deep Underground Neutrino Experiment: DUNE Collaboration

The Deep Underground Neutrino Experiment (DUNE) will be a powerful tool for a variety of physics topics. The high-intensity proton beams provide a large neutrino flux, sampled by a near detector system consisting of a combination of capable precision detectors, and by the massive far detector system located deep underground. This configuration sets up DUNE as a machine for discovery, as it enables opportunities not only to perform precision neutrino measurements that may uncover deviations from the present three-flavor mixing paradigm, but also to discover new particles and unveil new interactions and symmetries beyond those predicted in the Standard Model (SM). Of the many potential beyond the Standard Model (BSM) topics DUNE will probe, this paper presents a selection of studies quantifying DUNE's sensitivities to sterile neutrino mixing, heavy neutral leptons, non-standard interactions, CPT symmetry violation, Lorentz invariance violation, neutrino trident production, dark matter from both beam induced and cosmogenic sources, baryon number violation, and other new physics topics that complement those at high-energy colliders and significantly extend the present reach.

Core surgical field camps: a new deanery-based model for enhancing advanced skills in core surgical trainees through simulation

Hands-on wet lab simulation training is a vital part of modern surgical training. Since 2010, surgical 'boot camps' have been run by many UK deaneries to teach core surgical trainees basic entry level skills. Training in advanced skills often requires attendance at national fee-paying courses. In the Wessex Deanery, multiple, free of charge, core surgical 'field camps' were developed to provide more advanced level teaching in the particular specialty preference of each core surgical trainee. After the COVID-19 pandemic, national hands-on courses will be challenging to provide and deanery-based advanced skills training may be the way forward for craft-based specialties. The experiences over 2 years of delivering the Wessex core surgical field camps are shared, giving a guide and advice for other trainers on how to run a field camp.

Breed does not affect the association between murmur intensity and disease severity in dogs with pulmonic or subaortic stenosis

OBJECTIVES

To determine whether breed affects the ability of murmur intensity to predict the severity of stenosis in dogs with pulmonic stenosis or subaortic stenosis.

MATERIALS AND METHODS

Retrospective multi-investigator study of dogs with pulmonic stenosis or subaortic stenosis. Murmur intensity, assessed by a four-level classification scheme, was compared with echocardiographically-determined pressure gradient across the affected valve. Breeds represented by at least 10 dogs at any murmur intensity were compared to determine the effect, if any, of breed.

RESULTS

A total of 1088 dogs (520 with pulmonic stenosis and 568 with subaortic stenosis, representing 106 breeds and the mixed breed group) were included; 208 dogs had soft, 210 had moderate, 283 had loud and 387 had palpable murmurs. Fifteen breeds were represented by at least 10 dogs: five breeds with at least 10 dogs had soft murmurs (132 dogs), nine breeds had moderate murmurs (149 dogs), 10 breeds had loud murmurs (188 dogs), and 11 breeds had palpable murmurs (286 dogs). No breeds differed in stenosis severity from any other breeds within any murmur grade. Post hoc power calculations suggested that we would have been able to detect at least a moderate or large effect size, had one existed. Several dogs with soft murmurs had more-than-mild disease severity.

CLINICAL SIGNIFICANCE

Despite anecdotally perceived differences in the detection of heart murmurs between breeds, which have been proposed to potentially affect the interpretation of stenosis severity, we found no obvious breed effect in the ability to predict severity of stenosis.

New data, strategies, and insights for Listeria monocytogenes dose-response models: summary of an interagency workshop, 2011

Listeria monocytogenes is a leading cause of hospitalization, fetal loss, and death due to foodborne illnesses in the United States. A quantitative assessment of the relative risk of listeriosis associated with the consumption of 23 selected categories of ready-to-eat foods, published by the U.S. Department of Health and Human Services and the U.S. Department of Agriculture in 2003, has been instrumental in identifying the food products and practices that pose the greatest listeriosis risk and has guided the evaluation of potential intervention strategies. Dose-response models, which quantify the relationship between an exposure dose and the probability of adverse health outcomes, were essential components of the risk assessment. However, because of data gaps and limitations in the available data and modeling approaches, considerable uncertainty existed. Since publication of the risk assessment, new data have become available for modeling L. monocytogenes dose-response. At the same time, recent advances in the understanding of L. monocytogenes pathophysiology and strain diversity have warranted a critical reevaluation of the published dose-response models. To discuss strategies for modeling L. monocytogenes dose-response, the Interagency Risk Assessment Consortium (IRAC) and the Joint Institute for Food Safety and Applied Nutrition (JIFSAN) held a scientific workshop in 2011 (details available at http://foodrisk.org/irac/events/). The main findings of the workshop and the most current and relevant data identified during the workshop are summarized and presented in the context of L. monocytogenes dose-response. This article also discusses new insights on dose-response modeling for L. monocytogenes and research opportunities to meet future needs.

Virus inactivation on hard surfaces or in suspension by chemical disinfectants: systematic review and meta-analysis of norovirus surrogates

Norovirus (NoV) infections are the leading cause of foodborne illness in the United States. Effective disinfection is important for controlling outbreaks caused by this highly infectious virus but can be difficult to achieve because NoV is very resistant to many common disinfection protocols. The inability of human NoV to replicate in tissue culture complicates NoV research, generally necessitating genome copy quantification, the use of surrogate viruses, or the use of other substitutes such as virus-like particles. To date, comprehensive comparisons among NoV surrogates and between surrogates and human NoV are missing, and it is not clear how best to extrapolate information from surrogate data. We conducted a systematic review and meta-analysis of comparisons of NoV surrogates with regard to their susceptibility to disinfection on hard surfaces or in suspension. Restricting our analysis to those studies in which two or more virus surrogates were compared allowed us to improve the signal-to-noise ratio in our analysis, similar to the epidemiological concept of matching. Using meta-analysis methods, our results indicate that hepatitis A virus, murine norovirus 1, and phage MS2 are significantly more resistant to disinfection than is feline calicivirus, but average differences in viral titer reduction appeared to be modest, 1.5 log PFU or less in all cases. None of the studies that compared surrogates and human NoV met our inclusion criteria, precluding a direct comparison between human NoV and NoV surrogates in this study. For all surrogates with sufficient data available to permit subgroup analyses, we detected strong evidence that the type of disinfectant impacted the relative susceptibility of the surrogates. Therefore, extrapolation of results between surrogates or from surrogates to human NoV must consider the type of disinfectant studied.

Towards an ontology for data quality in integrated chronic disease management: a realist review of the literature

PURPOSE

Effective use of routine data to support integrated chronic disease management (CDM) and population health is dependent on underlying data quality (DQ) and, for cross system use of data, semantic interoperability. An ontological approach to DQ is a potential solution but research in this area is limited and fragmented.

OBJECTIVE

Identify mechanisms, including ontologies, to manage DQ in integrated CDM and whether improved DQ will better measure health outcomes.

METHODS

A realist review of English language studies (January 2001-March 2011) which addressed data quality, used ontology-based approaches and is relevant to CDM.

RESULTS

We screened 245 papers, excluded 26 duplicates, 135 on abstract review and 31 on full-text review; leaving 61 papers for critical appraisal. Of the 33 papers that examined ontologies in chronic disease management, 13 defined data quality and 15 used ontologies for DQ. Most saw DQ as a multidimensional construct, the most used dimensions being completeness, accuracy, correctness, consistency and timeliness. The majority of studies reported tool design and development (80%), implementation (23%), and descriptive evaluations (15%). Ontological approaches were used to address semantic interoperability, decision support, flexibility of information management and integration/linkage, and complexity of information models.

CONCLUSION

DQ lacks a consensus conceptual framework and definition. DQ and ontological research is relatively immature with little rigorous evaluation studies published. Ontology-based applications could support automated processes to address DQ and semantic interoperability in repositories of routinely collected data to deliver integrated CDM. We advocate moving to ontology-based design of information systems to enable more reliable use of routine data to measure health mechanisms and impacts.

Human umbilical cord blood mononuclear cells activate the survival protein Akt in cardiac myocytes and endothelial cells that limits apoptosis and necrosis during hypoxia

We have previously reported that human umbilical cord blood mononuclear cells (HUCBC), which contain hematopoietic, mesenchymal, and endothelial stem cells, can significantly reduce acute myocardial infarction size. To determine the mechanism whereby HUCBC increase myocyte and vascular endothelial cell survival, we treated cardiac myocytes and coronary artery endothelial cells in separate experiments with HUCBC plus culture media or culture media alone and subjected the cells to 24 h of hypoxia or normoxia. We then determined in myocytes and endothelial cells activation of the cell survival protein Akt by Western blots. We also determined in these cells apoptosis by annexin V staining and necrosis by propidium iodide staining. Thereafter, we inhibited with API, a specific and sensitive Akt inhibitor, Akt activation in myocytes and endothelial cells cultured with HUCBC during hypoxia and determined cell apoptosis and necrosis. In cells cultured without HUCBC, hypoxia only slightly activated Akt. Moreover, hypoxia increased myocyte apoptosis by ≥ 226% and necrosis by 58% in comparison with myocytes in normoxia. Hypoxic treatment of endothelial cells without HUCBC increased apoptosis by 94% and necrosis by 59%. In contrast, hypoxia did not significantly affect HUCBC. Moreover, in myocyte + HUCBC cultures in hypoxia, HUCBC induced a ≥ 135% increase in myocyte phospho-Akt. Akt activation decreased myocyte apoptosis by 76% and necrosis by 35%. In endothelial cells, HUCBC increased phospho-Akt by 116%. HUCBC also decreased endothelial cell apoptosis by 58% and necrosis by 42%. Inhibition of Akt with API in myocytes and endothelial cells cultured with HUCBC during hypoxia nearly totally prevented the HUCBC-induced decrease in apoptosis and necrosis. We conclude that HUCBC can significantly decrease hypoxia-induced myocyte and endothelial cell apoptosis and necrosis by activating Akt in these cells and in this manner HUCBC can limit myocardial ischemia and injury.

Produce consumption in the United States: an analysis of consumption frequencies, serving sizes, processing forms, and high-consuming population subgroups for microbial risk assessments

A great variety of fruits and vegetables are available in the United States. These items are produced in various geographic regions by a diverse industry. Produce has been increasingly identified as a vehicle for disease outbreaks. Changes in consumption may explain this increase, but analyses of produce consumption are limited. Comprehensive assessments of the public health risks associated with produce depend on quantitative consumption data, including the population fractions and subgroups of consumers, the quantities consumed by these individuals, and the processing that occurs before consumption. Here, we provide an analysis of nationally representative consumption estimates by estimating consumption frequencies, serving sizes, and processing forms for a variety of produce commodities based on 1999 through 2006 data from "What We Eat in America," the dietary interview component of the National Health and Nutrition Examination Survey performed by the National Center for Health Statistics. Consumption patterns for fresh and heat-treated produce were assessed, compared with U.S. food availability estimates from the U.S. Department of Agriculture Economic Research Service (ERS), and combined with ERS data on temporal trends in food availability and nondomestic produce origins. To identify high-consuming population subgroups, we explored consumer habits and demographic predictors of fresh produce consumption (data available at www.foodrisk.org). Our analysis of common outbreak vehicles revealed limited temporal changes in food availability but frequent consumption as fresh commodities. In addition to providing quantitative consumption estimates for risk assessments, our data clearly show that produce consumption differs among fruits and vegetables, fresh and heat-treated foods, and demographic subgroups. These results are valuable for risk assessments and outbreak investigations and allow targeting of risk communication or interventions to those individuals at greatest risk.

The University of NSW electronic practice based research network: disease registers, data quality and utility

INTRODUCTION

Accurate well-maintained registers are a prerequisite to co-ordinated care of patients with chronic diseases. Their effectiveness in enabling improved management is dependent on the quality of the information captured. This paper provides an overview into the methodology and data quality of the electronic Practice Based Research Network.

METHODS

Clinical records with no identifying information are routinely extracted from four general practices. The data are linked in the data warehouse. Data quality is assessed for completeness, correctness and consistency. Reports on data quality are given back to practices and semi-structured interviews provide information to interpret the results and discuss how data quality could be improved.

FINDINGS

Data quality is mostly complete for sex and date of birth but indigenous status, smoking and weight were incomplete. There are generally high levels of correctness and internal consistency. Completeness of records in assisting the management of diabetes patients using the annual cycle of care was poor. GPs often use the progress notes to enter information during the consultation and coding diagnoses was considered onerous.

DISCUSSION

The routine capture of electronic clinical health records from primary health care and health services can be used to monitor performance and improve the quality of clinical records. There is a need for accurate and comprehensive clinical records to ensure the safety and quality of clinical practice. Understanding the true reasons for poor data quality is complex. Having a community-based research network may assist in answering some of these questions.

CONCLUSION

Electronic health records are increasingly being used for secondary research and evaluation, beyond the primary purpose of supporting clinical care. The data must be of sufficient quality to support these purposes.

Observational study of food safety practices in retail deli departments

In order to improve the safety of refrigerated ready-to-eat food products prepared at retail deli departments, a better understanding of current practices in these establishments is needed. Food employees in deli departments at six chain and three independent retail establishments in Maryland and Virginia were observed, using notational analysis, as they prepared deli products for sale. The frequency of contact with objects and deli products before sale, hand washing and glove changing during preparation, and equipment, utensil, and surface cleaning and sanitizing was determined. Compliance with the U.S. Food and Drug Administration's 2005 model Food Code recommendations, which must be adopted by the individual state and local jurisdictions that are responsible for directly regulating retail establishments, was also assessed. Observations indicated there were a large number of actions for which hand washing was recommended at independent and chain stores (273 recommended of 1,098 total actions and 439 recommended of 3,073 total actions, respectively). Moreover, 67% (295 of 439) of the actions for which hand washing was recommended at the chain stores and 86% (235 of 273) of those at the independent stores resulted from employees touching non-food contact surfaces prior to handling ready-to-eat food. Compliance with hand washing recommendations was generally low and varied depending on store type with independent stores exhibiting lower compliance than chain stores (5 instances of compliance for 273 recommended actions and 73 instances of compliance for 439 recommended actions, respectively). Potential risk mitigation measures that may reduce the frequency of hand washing actions needed during ready-to-eat food preparation in retail deli departments are discussed. More research is needed to determine the impact of such measures on food safety.

Integrating risk management into working practice

The aim of this article, the third in this series on the Seven Steps to Patient Safety (National Patient Safety Agency (NPSA) 2004), is to explore how risk management can be integrated into the culture of a healthcare organisation and the working practices of clinicians, managers and their immediate teams.

Building a safety culture

This is the first article in a series of seven based on the Seven Steps to Patient Safety (National Patient Safety Agency (NPSA) 2004a). It is aimed at enhancing nurses' and midwives' knowledge about patient safety, including strategies and tools that are available to improve the quality of health care. This article outlines the patient safety agenda and emphasises the importance of creating an open and fair culture in the NHS.

pDNA bioparticles: comparative heterogeneity, surface, binding, and activity analyses

New applications for nucleic acid-bound micro/nanoparticles are emerging in drug delivery, biocatalysis, diagnostics, and toxicology. Bioactivity of viral or liposomal based technologies is limited by heterogeneity, partitioning, aggregation, and protein binding in physiological fluids, underlying immunotoxicity, and poor in vitro and cell-culture corollaries. Here we have systematically investigated novel pDNA bioparticles formed through complexation to model non-viral/non-lipid materials, peptides, aminoglycans, and small molecules (polybrene, chitosan, butirosin, protamine, Lys10, RGDS, bupivacaine, and chlorpromazine). On the basis of characterization by heterogeneity, kinetics, partitioning in physiological fluid and serum protein-binding, surface, size and electrophoretic behavior, transfection, and immunotoxicity, notably protamine, and chitosan DNA particles gave a long lifetime (12-18h), low protein-binding (<10microg/ml), good transfection activity (10(2)-10(4)RLU/mg cell protein), and low immunotoxicity. Our results support further evaluation of these materials as potential alternatives to viral or liposomal approaches, in combination with pDNA as binding, expression or therapeutic agents.

Transparency, swelling and scarring in the corneal stroma

PURPOSE

This paper briefly reviews current explanations for corneal transparency and uses a well-developed model to try to explain the increased light scattering either accompanying corneal swelling or following phototherapeutic keratectomy (PTK).

METHODS

The direct summation of fields (DSF) method was used to compute light transmission as a function of wavelength. The method requires input of a number of structural parameters. Some of these were obtained from electron micrographs and others were calculated from X-ray diffraction data.

RESULTS

By swelling sections of stroma cut from different depths in the tissue, we have shown that fluid entering the cornea causes more swelling in the posterior lamellae than in the anterior lamellae. Furthermore, posterior lamellae can reach a higher final hydration than anterior lamellae. Collagen-free regions ('lakes') exist in corneas swollen in vitro and in Fuch's dystrophy corneas, many of which may be caused by the death of cells. The DSF method shows that local fibril disordering, increased refractive index mismatch, and increased corneal thickness together can account for a 20% increase in light scattering in a Fuch's dystrophy cornea at H=5.8 compared to the normal cornea. Additional scattering is probably caused by 'lakes'. The DSF method applied to PTK rabbit stroma with high levels of haze suggests that the newly deposited collagen is not the cause of the increased light scattering.

CONCLUSIONS

Fluid is not uniformly distributed within the corneal stroma when the cornea swells. Increased hydration of posterior lamellae may be because of known differences in the glycosaminoglycans between the anterior and posterior stroma. Lamellar interweave in the anterior stroma probably limits the extent to which the constituent lamellae can swell. The DSF method can be used to account for increased light scattering in oedematous corneas but cannot account for haze following PTK.

Hepatoprotection by the farnesoid X receptor agonist GW4064 in rat models of intra- and extrahepatic cholestasis

Farnesoid X receptor (FXR) is a bile acid-activated transcription factor that is a member of the nuclear hormone receptor superfamily. Fxr-null mice exhibit a phenotype similar to Byler disease, an inherited cholestatic liver disorder. In the liver, activation of FXR induces transcription of transporter genes involved in promoting bile acid clearance and represses genes involved in bile acid biosynthesis. We investigated whether the synthetic FXR agonist GW4064 could protect against cholestatic liver damage in rat models of extrahepatic and intrahepatic cholestasis. In the bile duct-ligation and alpha-naphthylisothiocyanate models of cholestasis, GW4064 treatment resulted in significant reductions in serum alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase, as well as other markers of liver damage. Rats that received GW4064 treatment also had decreased incidence and extent of necrosis, decreased inflammatory cell infiltration, and decreased bile duct proliferation. Analysis of gene expression in livers from GW4064-treated cholestatic rats revealed decreased expression of bile acid biosynthetic genes and increased expression of genes involved in bile acid transport, including the phospholipid flippase MDR2. The hepatoprotection seen in these animal models by the synthetic FXR agonist suggests FXR agonists may be useful in the treatment of cholestatic liver disease.

Hepatoprotection by the farnesoid X receptor agonist GW4064 in rat models of intra- and extrahepatic cholestasis

Farnesoid X receptor (FXR) is a bile acid-activated transcription factor that is a member of the nuclear hormone receptor superfamily. Fxr-null mice exhibit a phenotype similar to Byler disease, an inherited cholestatic liver disorder. In the liver, activation of FXR induces transcription of transporter genes involved in promoting bile acid clearance and represses genes involved in bile acid biosynthesis. We investigated whether the synthetic FXR agonist GW4064 could protect against cholestatic liver damage in rat models of extrahepatic and intrahepatic cholestasis. In the bile duct-ligation and alpha-naphthylisothiocyanate models of cholestasis, GW4064 treatment resulted in significant reductions in serum alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase, as well as other markers of liver damage. Rats that received GW4064 treatment also had decreased incidence and extent of necrosis, decreased inflammatory cell infiltration, and decreased bile duct proliferation. Analysis of gene expression in livers from GW4064-treated cholestatic rats revealed decreased expression of bile acid biosynthetic genes and increased expression of genes involved in bile acid transport, including the phospholipid flippase MDR2. The hepatoprotection seen in these animal models by the synthetic FXR agonist suggests FXR agonists may be useful in the treatment of cholestatic liver disease.

EMG amplitude in maximal and submaximal exercise is dependent on signal capture rate

This study analysed the effect of different electromyographic (EMG) capture rates during maximal voluntary contraction, submaximal and maximal dynamic cycling activity on EMG amplitude and signal characteristics. Ten healthy subjects participated in this study. Peak power output (PPO) and maximal isometric force output (MVC) were measured, followed by a progressive cycle ride on a cycle ergometer. Electromyographic (EMG) data were simultaneously captured during the MVC and cycling activities at frequencies of 32, 64, 128, 256, 512, 1024 and 1984 Hz. Significant differences in amplitude were found (p < 0.01) between MVC, submaximal (SUB) and maximal cycling activities (PWATT) for all capture rates. Asymptote values for IEMG amplitude occurred at EMG capture rates of 1604 +/- 235.6 Hz during MVC, 503.1 +/- 236.2 Hz during PWATT and 326.2 +/- 105.4 Hz during SUB cycling activity and were significantly different (p < 0.01). No significant differences were found for force/EMG ratios between PWATT and MVC at 1984 Hz capture rates (3.8 +/- 1.7 N/V vs 2.5 +/- 0.9 N/V) while significant differences occurred at 32 Hz capture rate (6.2 +/- 3.8 vs 16.0 +/- 8.0; p < 0.01). Low correlations were found between EMG activity captured at 1984 Hz during PWATT and lean thigh volume (r = 0.36) and MVC (r = 0.32). Asymptote values found on this study suggest that data captured below 326 Hz for SUB, 503 Hz for PWATT and 1604 Hz for MVC are not reliable. Therefore apparatus capturing EMG data at low frequencies from these values cannot be used for quantitative data analyses.

Semiglobal simplex optimization and its application to determining the preferred solvation sites of proteins

The classical simplex method is extended into the Semiglobal Simplex (SGS) algorithm. Although SGS does not guarantee finding the global minimum, it affords a much more thorough exploration of the local minima than any traditional minimization method. The basic idea of SGS is to perform a local minimization in each step of the simplex algorithm, and thus, similarly to the Convex Global Underestimator (CGU) method, the search is carried out on a surface spanned by local minima. The SGS and CGU methods are compared by minimizing a set of test functions of increasing complexity, each with a known global minimum and many local minima. Although CGU delivers substantially better success rates in simple problems, the two methods become comparable as the complexity of the problems increases. Because SGS is generally faster than CGU, it is the method of choice for solving optimization problems in which function evaluation is computationally inexpensive and the search region is large. The extreme simplicity of the method is also a factor. The SGS method is applied here to the problem of finding the most preferred (i.e., minimum free energy) solvation sites on a streptavidin monomer. It is shown that the SGS method locates the same lowest free energy positions as an exhaustive multistart Simplex search of the protein surface, with less than one-tenth the number of minizations. The combination of the two methods, i.e.. multistart simplex and SGS, provides a reliable procedure for predicting all potential solvation sites of a protein.

A context noise model of episodic word recognition

Item noise models of recognition assert that interference at retrieval is generated by the words from the study list. Context noise models of recognition assert that interference at retrieval is generated by the contexts in which the test word has appeared. The authors introduce the bind cue decide model of episodic memory, a Bayesian context noise model, and demonstrate how it can account for data from the item noise and dual-processing approaches to recognition memory. From the item noise perspective, list strength and list length effects, the mirror effect for word frequency and concreteness, and the effects of the similarity of other words in a list are considered. From the dual-processing perspective, process dissociation data on the effects of length, temporal separation of lists, strength, and diagnosticity of context are examined. The authors conclude that the context noise approach to recognition is a viable alternative to existing approaches.

Discrimination of near-native protein structures from misfolded models by empirical free energy functions

Free energy potentials, combining molecular mechanics with empirical solvation and entropic terms, are used to discriminate native and near-native protein conformations from slightly misfolded decoys. Since the functional forms of these potentials vary within the field, it is of interest to determine the contributions of individual free energy terms and their combinations to the discriminative power of the potential. This is achieved in terms of quantitative measures of discrimination that include the correlation coefficient between RMSD and free energy, and a new measure labeled the minimum discriminatory slope (MDS). In terms of these criteria, the internal energy is shown to be a good discriminator on its own, which implies that even well-constructed decoys are substantially more strained than the native protein structure. The discrimination improves if, in addition to the internal energy, the free energy expression includes the electrostatic energy, calculated by assuming non-ionized side chains, and an empirical solvation term, with the classical atomic solvation parameter model providing slightly better discrimination than a structure-based atomic contact potential. Finally, the inclusion of a term representing the side chain entropy change, and calculated by an established empirical scale, is so inaccurate that it makes the discrimination worse. It is shown that both the correlation coefficient and the MDS value (or its dimensionless form) are needed for an objective assessment of a potential, and that together they provide much more information on the origins of discrimination than simple inspection of the RMSD-free energy plots.

Dual processes in recognition: does a focus on measurement operations provide a sufficient foundation?

Current theoretical thinking about dual processes in recognition relies heavily on the measurement operations embodied within the process dissociation procedure. We critically evaluate the ability of this procedure to support this theoretical enterprise. We show that there are alternative processes that would produce a rough invariance in familiarity (a key prediction of the dual-processing approach) and that the process dissociation procedure does not have the power to differentiate between these alternative possibilities. We also show that attempts to relate parameters estimated by the process dissociation procedure to subjective reports (remember-know judgments) cannot differentiate between alternative dual-processing models and that there are problems with some of the historical evidence and with obtaining converging evidence. Our conclusion is that more specific theories incorporating ideas about representation and process are required.

What is free association and what does it measure?

This paper reports the results of a study of free association in which participants were asked to produce the first two words to come to mind. The findings were used to estimate the reliability of indices of strength and set size for different types of items and to model free association as a retrieval task. When confined to first responses, reliability was generally high for both indices, particularly for words with smaller sets of associates and stronger primaries. When second responses were included, reliability declined. A second response added new but weak items to the set, and, when the primary associate was not produced on the first opportunity, it tended not to be produced on the second. Relative to when multiple responses are requested, first-response free association provides more reliable indices of the relative strength and set size for a word's strongest associates. A model of free association assuming that a strength distribution underlies each response provided a good fit to the data.

Impact of postoperative gait analysis on orthopaedic care

The impact of postoperative gait analysis on the ongoing orthopaedic care of 38 consecutive patients with a static encephalopathy was evaluated. Of the 38 postoperative gait analyses, 32 (84%) resulted in recommendations of a change in patient care. Surgery was recommended in 16 of 38 (42%) cases, bracing in 20 (53%) cases, and specific physical therapy regimens in eight (21%) cases. Eleven of the 38 (29%) patients had changes recommended in at least two of the three areas (surgery, bracing, and therapy). The results of this study suggest that postoperative gait analysis serves not only as a measure of treatment outcome, but also as a useful tool in planning ongoing care for these patients.

The effect of preoperative gait analysis on orthopaedic decision making

The impact of preoperative gait analysis on the orthopaedic care of 97 patients (101 gait analyses) at the authors' institution was evaluated. For the 70 patients for whom a specific treatment plan had been outlined before the preoperative gait study, the treatment plan was altered in 62 (89%) after the gait analysis study. In 10 of the 70 patients with specific treatment plans before the gait study, the referring physician also served as the physician in the gait laboratory; ultimate treatment was changed in nine of these 10 patients. Of the 273 surgical procedures recommended before the gait study in the 70 patients, 106 (39%) of these procedures were not done when the gait laboratory data were considered. An average of 1.5 procedures per patient that were planned before the gait study ultimately were not deemed necessary by the treating physician after the addition of the gait data. An additional 110 procedures (1.6 per patient) that had not been recommended before the gait study ultimately were performed after addition of the gait laboratory data. This study shows that ultimate surgical intervention frequently is altered by the addition of gait laboratory data.

Continuum electrostatic analysis of preferred solvation sites around proteins in solution

To understand water-protein interactions in solution, the electrostatic field is calculated by solving the Poisson-Boltzmann equation, and the free energy surface of water is mapped by translating and rotating an explicit water molecule around the protein. The calculation is applied to T4 lysozyme with data available on the conservation of solvent binding sites in 18 crystallographically independent molecules. The free energy maps around the ordered water sites provide information on the relationship between water positions in crystal structure and in solution. Results show that almost all conserved sites and the majority of nonconserved sites are within 1.3 A of local free energy minima. This finding is in sharp contrast to the behavior of randomly placed water molecules in the boundary layer, which, on the average, must travel more than 3 A to the nearest free energy minimum. Thus, the solvation sites are at least partially determined by protein-water interactions rather than by crystal packing alone. The characteristic water residence times, obtained from the free energies at the local minima, are in good agreement with nuclear magnetic resonance experiments. Only about half of the potential sites show up as ordered water in the 1.7 A resolution X-ray structure. Crystal packing interactions can stabilize weak or mobile potential sites (in fact, some ordered water positions are not close to free energy minima) or can prevent water from occupying certain sites. Apart from a few buried water molecules that are strong binders, the free energies are not very different for conserved and nonconserved sites. We show that conservation of a water site between two crystals occurs if the positions of protein atoms, primarily contributing to the free energy at the local minimum, do not substantially change from one structure to the other. This requirement can be correlated with the nature of the side chain contacting the water molecule in the site.