Study protocol for a type III hybrid effectiveness-implementation trial to evaluate scaling interoperable clinical decision support for patient-centered chronic pain management in primary care

Background

The US continues to face public health crises related to both chronic pain and opioid overdoses. Thirty percent of Americans suffer from chronic noncancer pain at an estimated yearly cost of over $600 billion. Most patients with chronic pain turn to primary care clinicians who must choose from myriad treatment options based on relative risks and benefits, patient history, available resources, symptoms, and goals. Recently, with attention to opioid-related risks, prescribing has declined. However, clinical experts have countered with concerns that some patients for whom opioid-related benefits outweigh risks may be inappropriately discontinued from opioids. Unfortunately, primary care clinicians lack usable tools to help them partner with their patients in choosing pain treatment options that best balance risks and benefits in the context of patient history, resources, symptoms, and goals. Thus, primary care clinicians and patients would benefit from patient-centered clinical decision support (CDS) for this shared decision-making process.

Methods

The objective of this 3-year project is to study the adaptation and implementation of an existing interoperable CDS tool for pain treatment shared decision making, with tailored implementation support, in new clinical settings in the OneFlorida Clinical Research Consortium. Our central hypothesis is that tailored implementation support will increase CDS adoption and shared decision making. We further hypothesize that increases in shared decision making will lead to improved patient outcomes, specifically pain and physical function. The CDS implementation will be guided by the Exploration, Preparation, Implementation, Sustainment (EPIS) framework. The evaluation will be organized by the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework. We will adapt and tailor PainManager, an open source interoperable CDS tool, for implementation in primary care clinics affiliated with the OneFlorida Clinical Research Consortium. We will evaluate the effect of tailored implementation support on PainManager’s adoption for pain treatment shared decision making. This evaluation will establish the feasibility and obtain preliminary data in preparation for a multi-site pragmatic trial targeting the effectiveness of PainManager and tailored implementation support on shared decision making and patient-reported pain and physical function.

Discussion

This research will generate evidence on strategies for implementing interoperable CDS in new clinical settings across different types of electronic health records (EHRs). The study will also inform tailored implementation strategies to be further tested in a subsequent hybrid effectiveness-implementation trial. Together, these efforts will lead to important new technology and evidence that patients, clinicians, and health systems can use to improve care for millions of Americans who suffer from pain and other chronic conditions.

Trial registration

ClinicalTrials.gov, NCT05256394, Registered 25 February 2022.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13012-022-01217-4.

Computational Study of the Structure and Transport in Pyrrolidinium-Li-TFSI-Silica Ionogels

Ionogels (IGs) are a unique class of composite materials with attributes that make them promising materials for applications in electrochemical energy storage. Due to the solid porous matrix that confines the ionic liquid (IL) in the IG, they can be used as self-supporting electrolytes. Furthermore, interactions of the IL with the porous matrix can have beneficial effects on transport, such as lowering the freezing/glass transition temperature of the conducting IL. In this work, we employ molecular dynamics simulations to investigate the influence of the porous morphology and solid volume fraction on ionic conductivity and Li⁺ diffusivity using a representative 0.5 M Li-bis(trifluoromethane)sulfonimide (TFSI)-pyrrolidinium (Pyr1.3) IL confined in a nanoporous silica matrix. The effect of the morphology of the confining matrix is compared using the pure IL as a baseline. We find that the tracer and collective Li⁺ diffusion and ionic conductivity of all the model IGs have significantly lower temperature dependence than the corresponding pure IL. In general, low-silica IGs with wide pores displayed the best transport properties at high temperatures, but the trends with the morphology for the nested set of transport coefficients we examined changed as the collective behavior of the Li⁺ ions and the molecular IL components were considered. Remarkably, some of the model IGs displayed better transport properties on a volume of fluid basis at low temperatures than the constituent IL. These trends were tied to structural changes revealed by the radial distribution functions of the IL components and the silica surface, including a decreasing Li⁺ adsorption peak of the surface silica indicating a change in the relative contributions of bulk-like and surface-like transport in the confined IL.

The direct and indirect effect of the COVID-19 pandemic on patients with cardiomyopathy

Background

The disease-specific impact of COVID-19 on different cardiac conditions requires further investigation. Whilst direct effects are observed for those infected with SARS-CoV-2, the indirect effects of the pandemic arising from interruption to clinical care may represent a further source of morbidity and mortality.

Purpose

To evaluate the direct and indirect effects of the COVID-19 pandemic on patients with dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM).

Methods

(i) Patients with DCM or HCM previously recruited to a single centre registry were studied using NHS Spine Summary Care Records, hospital records and patient questionnaires. The primary outcome was test-proven COVID-19 infection. Secondary outcomes were the proportion of COVID-19 cases requiring hospitalisation and the proportion of subjects advised to shield. Outcomes were compared with published UK COVID-19 statistics.

(ii) The Heart Hive COVID-19 study is an international online prospective observational cohort study. Subjects registered on an online platform with cardiomyopathy or without heart disease (controls) were invited to enrol. Enrolled subjects complete online surveys, adapted from a WHO Survey tool for behavioural insights on COVID-19.

Results

(i) Of 1236 eligible patients in our registry (703 DCM, 533 HCM), 13 (1.1%) had tested positive for COVID-19 compared to 1.6% in the UK population (p=0.14) up to 2nd November 2020, a higher proportion of whom required hospitalisation compared with the UK population (53.8% vs 16.5%, p=0.002). More patients with cardiomyopathy in our registry were advised to shield than in the UK population (21.9% vs 6.8%, p<0.ehab724.17361, Fig. 1).

(ii) Of 207 subjects enrolled in the Heart Hive COVID-19 study (131 cardiomyopathy, 76 controls), more patients with cardiomyopathy felt their physical health had deteriorated due to the pandemic than controls (32.3% vs 13.2%, p=0.0042) despite only 4.6% reporting COVID-19 symptoms. Of those with cardiomyopathy, 38 (29.0%) reported a rescheduled clinic visit, 21 (16.0%) a cancelled clinic visit, 51 (38.9%) had missed investigations, 10 (7.6%) had cancelled/postponed procedures, 7 (5.3%) had missed medication doses due to the pandemic and 53 (40.4%) felt their health needs could not be met by telemedicine (Fig. 2). The psychological impact of the pandemic was comparable between cardiomyopathy patients and controls.

Conclusions

Patients with cardiomyopathy in our registry were not at a greater risk of testing positive for COVID-19 than the UK population, but a higher proportion of those that tested positive required hospitalisation. Many more patients with cardiomyopathy reported a subjective deterioration in physical health than had experienced COVID-19 symptoms, inferring a significant contribution of the indirect effects of the pandemic. Our findings have implications for both the health needs of these patients and the reorganisation of clinical services to meet these.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The Wellcome Trust, Medical Research Council (UK) Figure 1Figure 2

Effects of Strain Rate and Temperature on the Mechanical Properties of Simulated Silica Ionogels

Ionogels are hybrid materials formed by impregnating the pore space of a solid matrix with a conducting ionic liquid. By combining the properties of both component materials, ionogels can act as self-supporting electrolytes in Li batteries. In this study, molecular dynamics simulations are used to investigate the dependence of mechanical properties of silica ionogels on solid fraction, temperature, and pore width. Comparisons are made with corresponding aerogels. We find that the solid matrix fraction increases the moduli and strength of the ionogel. This varies nonlinearly with temperature and strain rate, according to the contribution of the viscous ionic liquid to resisting deformation. Owing to the temperature and strain sensitivity of the ionic liquid viscosity, the mechanical properties approach a linear mixing law at high temperature and low strain rates. The median pore width of the solid matrix plays a complex role, with its influence varying qualitatively with deformation mode. Narrower pores increase the relevant elastic modulus under shear and uniaxial compression but reduce the modulus obtained under uniaxial tension. Conversely, shear and tensile strength are increased by narrowing the pore width. All of these pore size effects become more pronounced as the silica fraction increases. Pore size effects, similar to the effects of temperature and strain rate, are linked to the ease of fluid redistribution within the pore space during deformation-induced changes in the geometry of the pores.

Insight into hydrogen production through molecular simulation of an electrode-ionomer electrolyte system

In this work, we examine metal electrode-ionomer electrolyte systems at high voltage (negative surface charge) and at high pH to assess factors that influence hydrogen production efficiency. We simulate the hydrogen evolution electrode interface investigated experimentally in the work of Bates et al. [J. Phys. Chem. C 119, 5467 (2015)] using a combination of first principles calculations and classical molecular dynamics. With this detailed molecular information, we explore the hypotheses posed in the work of Bates et al. In particular, we examine the response of the system to increased bias voltage and oxide coverage in terms of the potential profile, changes in solvation and species concentrations away from the electrode, surface concentrations, and orientation of water at reactive surface sites. We discuss this response in the context of hydrogen production.

An atomic-scale evaluation of the fracture toughness of silica glass

Using an atomistic technique consistent with continuum balance laws and drawing on classical fracture mechanics theory, we estimate the resistance to fracture propagation of amorphous silica. We discuss correspondence and deviations from classical linear elastic fracture mechanics theory including size dependence, rigid/floppy modes of deformation, and the effects of surface energy and stress.

Telomere length heterogeneity in placenta revealed with high-resolution telomere length analysis

INTRODUCTION

Telomeres, are composed of tandem repeat sequences located at the ends of chromosomes and are required to maintain genomic stability. Telomeres can become shorter due to cell division and specific lifestyle factors. Critically shortened telomeres are linked to cellular dysfunction, senescence and aging. A number of studies have used low resolution techniques to assess telomere length in the placenta. In this study, we applied Single Telomere Length Analysis (STELA) which provides high-resolution chromosome specific telomere length profiles to ask whether we could obtain more detailed information on the length of individual telomeres in the placenta.

METHODS

Term placentas (37-42 weeks) were collected from women delivering at University Hospital of Wales or Royal Gwent Hospital within 2 h of delivery. Multiple telomere-length distributions were determined using STELA. Intraplacental variation of telomere length was analysed (N = 5). Telomere length distributions were compared between labouring (N = 10) and non-labouring (N = 11) participants. Finally, telomere length was compared between female (N = 17) and male (N = 20) placenta.

RESULTS

There were no significant influences of sampling site, mode of delivery or foetal sex on the telomere-length distributions obtained. The mean telomere length was 7.7 kb ranging from 5.0 kb to 11.7 kb across all samples (N = 42) and longer compared with other human tissues at birth. STELA also revealed considerable telomere length heterogeneity within samples.

CONCLUSIONS

We have shown that STELA can be used to study telomere length homeostasis in the placenta regardless of sampling site, mode of delivery and foetal sex. Moreover, as each amplicon is derived from a single telomeric molecule, from a single cell, STELA can reveal the full detail of telomere-length distributions, including telomeres within the length ranges observed in senescent cells. STELA thus provides a new tool to interrogate the relationship between telomere length and pregnancy complications linked to placental dysfunction.

Meta-analysis of the association between peripheral artery disease and growth of abdominal aortic aneurysms

Background

The role of atherosclerosis in the pathogenesis of abdominal aortic aneurysm (AAA) is controversial. Atherosclerosis-associated peripheral artery disease (PAD) has been reported to be a risk factor for AAA in population screening studies; its relationship with AAA growth is controversial.

Methods

A systematic search of MEDLINE, Scopus, CINAHL and the Cochrane Central Register of Controlled Trials was conducted in April 2016 and repeated in January 2017. Databases were screened for studies reporting AAA growth rates in patients with, and without PAD. The included studies underwent quality assessment and, where possible, were included in the meta-analysis. A subgroup analysis was performed, including only studies that adjusted for confounding factors.

Results

Seventeen studies, including a total of 4873 patients, met the review entry criteria. Data from 15 studies were included in the meta-analysis. There was marked heterogeneity in study design, methodology and statistical analyses used. In the main analysis, PAD was associated with reduced AAA growth (mean difference – 0·13, 95 per cent c.i. –0·27 to –0·00; P = 0·04). However, statistical significance was not maintained in sensitivity analysis. In a subanalysis that included only data adjusted for other risk factors, no significant association between PAD and AAA growth was found (mean difference –0·11, –0·23 to 0·00; P = 0·05).

Conclusion

This systematic review suggests that currently reported studies demonstrate no robust and consistent association between PAD and reduced AAA growth.

Molecular dynamics studies of defect formation during heteroepitaxial growth of InGaN alloys on (0001) GaN surfaces

We investigate the formation of extended defects during molecular-dynamics (MD) simulations of GaN and InGaN growth on (0001) and ([Formula: see text]) wurtzite-GaN surfaces. The simulated growths are conducted on an atypically large scale by sequentially injecting nearly a million individual vapor-phase atoms towards a fixed GaN surface; we apply time-and-position-dependent boundary constraints that vary the ensemble treatments of the vapor-phase, the near-surface solid-phase, and the bulk-like regions of the growing layer. The simulations employ newly optimized Stillinger-Weber In-Ga-N-system potentials, wherein multiple binary and ternary structures are included in the underlying density-functional-theory training sets, allowing improved treatment of In-Ga-related atomic interactions. To examine the effect of growth conditions, we study a matrix of >30 different MD-growth simulations for a range of In _x Ga _1-x N-alloy compositions (0 ≤ x ≤ 0.4) and homologous growth temperatures [0.50 ≤ T/T^*_m (x) ≤ 0.90], where T^*_m (x) is the simulated melting point. Growths conducted on polar (0001) GaN substrates exhibit the formation of various extended defects including stacking faults/polymorphism, associated domain boundaries, surface roughness, dislocations, and voids. In contrast, selected growths conducted on semi-polar ([Formula: see text]) GaN, where the wurtzite-phase stacking sequence is revealed at the surface, exhibit the formation of far fewer stacking faults. We discuss variations in the defect formation with the MD growth conditions, and we compare the resulting simulated films to existing experimental observations in InGaN/GaN. While the palette of defects observed by MD closely resembles those observed in the past experiments, further work is needed to achieve truly predictive large-scale simulations of InGaN/GaN crystal growth using MD methodologies.

Surface Structure and Stability of Partially Hydroxylated Silica Surfaces

Surface energies of silicates influence crack propagation during brittle fracture and decrease with surface relaxation caused by annealing and hydroxylation. Molecular-level simulations are particularly suited for the investigation of surface processes. In this work, classical MD simulations of silica surfaces are performed with two force fields (ClayFF and ReaxFF) to investigate the effect of force field reactivity on surface structure and energy as a function of surface hydroxylation. An unhydroxylated fracture surface energy of 5.1 J/m² is calculated with the ClayFF force field, and 2.0 J/m² is calculated for the ReaxFF force field. The ClayFF surface energies are consistent with the experimental results from double cantilever beam fracture tests (4.5 J/m²), whereas ReaxFF underestimated these surface energies. Surface relaxation via annealing and hydroxylation was performed by creating a low-energy equilibrium surface. Annealing condensed neighboring siloxane bonds increased the surface connectivity, and decreased the surface energies by 0.2 J/m² for ClayFF and 0.8 J/m² for ReaxFF. Posthydroxylation surface energies decreased further to 4.6 J/m² with the ClayFF force field and to 0.2 J/m² with the ReaxFF force field. Experimental equilibrium surface energies are ∼0.35 J/m², consistent with the ReaxFF force field. Although neither force field was capable of replicating both the fracture and equilibrium surface energies reported from experiment, each was consistent with one of these conditions. Therefore, future computational investigations that rely on accurate surface energy values should consider the surface state of the system and select the appropriate force field.

Assessment and validation of a novel angiographic scoring system for peripheral artery disease

BACKGROUND

Angiography is used routinely in the assessment of lower-limb arteries, but there are few well validated angiographic scoring systems. The aim of this study was to develop and validate a novel angiographic scoring system for peripheral artery disease.

METHODS

An angiographic scoring system (the ANGIO score) was developed and applied to a sample of patients from a single vascular surgical department who underwent CT angiography of the lower limbs. The reproducibility of the ANGIO score was compared with those of the Bollinger and Trans-Atlantic inter-Society Consensus (TASC) IIb systems in a series of randomly selected patients. Associations between the ANGIO score and lower-limb ischaemia, as measured by the ankle : brachial pressure index (ABPI), and outcome events (major lower-limb amputations and cardiovascular events - myocardial infarction, stroke and cardiovascular death) were assessed.

RESULTS

Some 256 patients undergoing CT angiography were included. The interobserver reproducibility of the ANGIO score was better than that of the other scoring systems examined (κ = 0·90, P = 0·002). There was a negative correlation between the ANGIO score and ABPI (ρ = -0·33, P = 0·008). A higher ANGIO score was associated with an increased risk of major lower-limb amputation (hazard ratio (HR) for highest versus lowest tertile 9·30, 95 per cent c.i. 1·95 to 44·38; P = 0·005) and cardiovascular events (HR 2·73, 1·31 to 5·70; P = 0·007) following adjustment for established risk factors.

CONCLUSION

The ANGIO score provided a reproducible and valid assessment of the severity of lower-limb ischaemia and risk of major amputation and cardiovascular events in these patients with peripheral artery disease.

Reported Amount of Salt Added to Food Is Associated with Increased All-Cause and Cancer-Related Mortality in Older Men in a Prospective Cohort Study

BACKGROUND

The effect of dietary salt intake on important population outcomes such as mortality is controversial. The aim of this study was to examine the association between the dietary habit of adding salt to food and mortality in older men. Design, participants, setting and measurements: A risk factor questionnaire which contained a question about the dietary habit of adding salt to food was completed by 11742 community recruited older men between 1996 and 1999. The men were followed by means of the Western Australia Data Linkage System until November 30th 2010. Deaths due to cardiovascular diseases and cancers were identified using ICD-10 codes in the ranges I00-I99 and C00-D48, respectively. The association between the frequencies of adding salt to food and mortality was assessed using Kaplan Meier estimates and Cox proportional hazard analysis.

RESULTS

Median follow-up for survivors was 12.5 years (inter-quartile range 8.3-13.2 years). A total of 5399 deaths occurred of which the primary cause registered was cancer and cardiovascular disease in 1962 (36.3%) and 1835 (34.0%) men, respectively. The reported frequency of adding salt to food was strongly positively associated with all-cause (p<0.001), cancer-related (p<0.001) but not cardiovascular-related (p=0.649) mortality. Men reporting adding salt to their food always had a 1.12-fold (95% CI 1.05-1.20, p<0.001) and a 1.20-fold (95% CI 1.07-1.34, p=0.001) increased risk of all-cause and cancer-related mortality, respectively, after adjusting for other risk factors. Men reporting adding salt to their food sometimes had a 1.16-fold (95% CI 1.04-1.29, p=0.007) increased risk of cancer-related mortality after adjusting for other risk factors.

CONCLUSION

A history of adding salt to food is associated with increased cancer-related mortality in older men.

Effect of premature stimulation on fast and slow excitation channels in cultured myocardial cells

Myocardial cells from chick embryos were cultured using a method which results in cell morphology and action potentials showing greater similarity to that of adult cells than to cells grown with standard methods of culture. The cells were paced by means of rectangular field stimuli (2 msec 2-5 times diastolic threshold). When the stimulus was given during the descending branch of the previous action potential, the action potential developed dissociation between a fast-rise component with short duration and a slow-rise component with longer duration. This dissociation was best in cells with an intermediate rate of rise of the spontaneous action potential and may be caused by different rates of reactivation of the slow and fast membrane excitation channels.

Local potential gradients as a unifying measure for thresholds of stimulation, standstill, tachyarrhythmia and fibrillation appearing after strong capacitor discharges

The pattern of arrhythmias following capacitor discharges of increasing amplitude, which have been observed by the authors in cultured myocardial cells from chick embryos, was compared to the arrhythmia patterns caused by similar discharges in experimental animals and humans, as reported in the literature. While the absolute voltages and currents causing each type of arrhythmia showed great variation, the scatter decreased considerably when the stimulus level was recalculated on the basis of peak current density in myocardial tissue, and was reduced further when the peak potential gradient at the cell level was used as the common basis of comparison. The similarity in the arrhythmia patterns and in the voltage gradients at which they occur indicates that the mechanism of these arrhythmias may be similar in cultured cells and intact animals and humans.

Telomere fusion threshold identifies a poor prognostic subset of breast cancer patients

Telomere dysfunction and fusion can drive genomic instability and clonal evolution in human tumours, including breast cancer. Telomere length is a critical determinant of telomere function and has been evaluated as a prognostic marker in several tumour types, but it has yet to be used in the clinical setting. Here we show that high‐resolution telomere length analysis, together with a specific telomere fusion threshold, is highly prognostic for overall survival in a cohort of patients diagnosed with invasive ductal carcinoma of the breast (n = 120). The telomere fusion threshold defined a small subset of patients with an extremely poor clinical outcome, with a median survival of less than 12 months (HR = 21.4 (7.9–57.6), P < 0.0001). Furthermore, this telomere length threshold was independent of ER, PGR, HER2 status, NPI, or grade and was the dominant variable in multivariate analysis. We conclude that the fusogenic telomere length threshold provides a powerful, independent prognostic marker with clinical utility in breast cancer. Larger prospective studies are now required to determine the optimal way to incorporate high‐resolution telomere length analysis into multivariate prognostic algorithms for patients diagnosed with breast cancer.

High‐resolution telomere length analysis is highly prognostic for overall survival.

Independent of ER, PGR, HER2 status, NPI and grade.

Dominant variable in multivariate analysis.

Spatial resolution of the electrical conductance of ionic fluids using a Green-Kubo method

We present a Green-Kubo method to spatially resolve transport coefficients in compositionally heterogeneous mixtures. We develop the underlying theory based on well-known results from mixture theory, Irving-Kirkwood field estimation, and linear response theory. Then, using standard molecular dynamics techniques, we apply the methodology to representative systems. With a homogeneous salt water system, where the expectation of the distribution of conductivity is clear, we demonstrate the sensitivities of the method to system size, and other physical and algorithmic parameters. Then we present a simple model of an electrochemical double layer where we explore the resolution limit of the method. In this system, we observe significant anisotropy in the wall-normal vs. transverse ionic conductances, as well as near wall effects. Finally, we discuss extensions and applications to more realistic systems such as batteries where detailed understanding of the transport properties in the vicinity of the electrodes is of technological importance.

Wound healing in total joint replacement

Satisfactory primary wound healing following total joint replacement is essential. Wound healing problems can have devastating consequences for patients. Assessment of their healing capacity is useful in predicting complications. Local factors that influence wound healing include multiple previous incisions, extensive scarring, lymphoedema, and poor vascular perfusion. Systemic factors include diabetes mellitus, inflammatory arthropathy, renal or liver disease, immune compromise, corticosteroid therapy, smoking, and poor nutrition. Modifications in the surgical technique are necessary in selected cases to minimise potential wound complications. Prompt and systematic intervention is necessary to address any wound healing problems to reduce the risks of infection and other potential complications.

Uncertainty quantification in MD simulations of concentration driven ionic flow through a silica nanopore. I. Sensitivity to physical parameters of the pore

In this article, uncertainty quantification is applied to molecular dynamics (MD) simulations of concentration driven ionic flow through a silica nanopore. We consider a silica pore model connecting two reservoirs containing a solution of sodium (Na(+)) and chloride (Cl(-)) ions in water. An ad hoc concentration control algorithm is developed to simulate a concentration driven counter flow of ions through the pore, with the ionic flux being the main observable extracted from the MD system. We explore the sensitivity of the system to two physical parameters of the pore, namely, the pore diameter and the gating charge. First we conduct a quantitative analysis of the impact of the pore diameter on the ionic flux, and interpret the results in terms of the interplay between size effects and ion mobility. Second, we analyze the effect of gating charge by treating the charge density over the pore surface as an uncertain parameter in a forward propagation study. Polynomial chaos expansions and Bayesian inference are exploited to isolate the effect of intrinsic noise and quantify the impact of parametric uncertainty on the MD predictions. We highlight the challenges arising from the heterogeneous nature of the system, given the several components involved, and from the substantial effect of the intrinsic thermal noise.

What would you do?: challenges in hip surgery

A moderator and panel of five experts led an interactive session in discussing five challenging and interesting patient case presentations involving surgery of the hip. The hip pathologies reviewed included failed open reduction internal fixation of subcapital femoral neck fracture, bilateral hip disease, evaluation of pain after metal-on-metal hip arthroplasty, avascular necrosis, aseptic loosening secondary to osteolysis and polyethylene wear, and management of ceramic femoral head fracture.

Effects of nano-void density, size and spatial population on thermal conductivity: a case study of GaN crystal

The thermal conductivity of a crystal is sensitive to the presence of surfaces and nanoscale defects. While this opens tremendous opportunities to tailor thermal conductivity, true 'phonon engineering' of nanocrystals for a specific electronic or thermoelectric application can only be achieved when the dependence of thermal conductivity on the defect density, size and spatial population is understood and quantified. Unfortunately, experimental studies of the effects of nanoscale defects are quite challenging. While molecular dynamics simulations are effective in calculating thermal conductivity, the defect density range that can be explored with feasible computing resources is unrealistically high. As a result, previous work has not generated a fully detailed understanding of the dependence of thermal conductivity on nanoscale defects. Using GaN as an example, we have combined a physically motivated analytical model and highly converged large-scale molecular dynamics simulations to study the effects of defects on thermal conductivity. An analytical expression for thermal conductivity as a function of void density, size, and population has been derived and corroborated with the model, simulations, and experiments.

Meteorological effects on the daily activity patterns of tabanid biting flies in northern Queensland, Australia

Information on the daily activity patterns of tabanid flies is important in the development of strategies that decrease the risk of pathogens transmitted by them. In addition, this information is useful to maximize numbers of tabanids trapped during short-term studies and to target feeding behavior studies of certain tabanid species to their times of peak activity. The current study examined the effects of various meteorological factors on the daily activity patterns of common tropical species of tabanids in north Queensland. Each species studied responded differently to weather factors. Tabanus townsvilli Ricardo (Diptera: Tabanidae) was most active during late morning and early afternoon, whereas Pseudotabanus silvester (Bergroth) and Tabanus pallipennis Macquart were most active in the late afternoon. Tabanus dorsobimaculatus Macquart was most active in the morning and early afternoon. Data on daily activity patterns of tabanid flies indicates that in an area such as Townsville, North Queensland, where several species of tabanid are present concurrently in high numbers, the overlapping periods of high activity for these species indicate a high risk of pathogen transmission for most of the day (10.00-19.00 hours). Similarly, because each species responds differently to weather variables, only extreme weather conditions are likely to inhibit activity of all species. These data also indicate that for maximal results, trapping and feeding behavior studies should be tailored to the preferred activity period of the species under investigation.

An atomistic J-integral at finite temperature based on Hardy estimates of continuum fields

In this work we apply a material-frame, kernel-based estimator of continuum fields to atomic data in order to estimate the J-integral for the analysis of an atomically sharp crack at finite temperatures. Instead of the potential energy appropriate for zero temperature calculations, we employ the quasi-harmonic free energy as an estimator of the Helmholtz free energy required by the Eshelby stress in isothermal conditions. We employ the simplest of the quasi-harmonic models, the local harmonic model of LeSar and co-workers, and verify that it is adequate for correction of the zero temperature J-integral expression for various deformation states for our Lennard-Jones test material. We show that this method has the properties of: consistency among the energy, stress and deformation fields; path independence of the contour integrals of the Eshelby stress; and excellent correlation with linear elastic fracture mechanics theory.

A nonlinear anisotropic viscoelastic model for the tensile behavior of the corneal stroma

Tensile strip experiments of bovine corneas have shown that the tissue exhibits a nonlinear rate-dependent stress-strain response and a highly nonlinear creep response that depends on the applied hold stress. In this paper, we present a constitutive model for the finite deformation, anisotropic, nonlinear viscoelastic behavior of the corneal stroma. The model formulates the elastic and viscous response of the stroma as the average of the elastic and viscous response of the individual lamellae weighted by a probability density function of the preferred in-plane lamellar orientations. The result is a microstructure-based model that incorporates the viscoelastic properties of the matrix and lamellae and the lamellar architecture in the response of the stroma. In addition, the model includes a fully nonlinear description of the viscoelastic response of the lamellar(fiber) level. This is in contrast to previous microstructure-based models of fibrous soft tissues, which relied on quasilinear viscoelastic formulations of the fiber viscoelasticity. Simulations of recent tensile strip experiments show that the model is able to predict, well within the bounds of experimental error and natural variations, the cyclic stress-strain behavior and nonlinear creep behavior observed in uniaxial tensile experiments of excised strips of bovine cornea.

A comparison of trapping methods for Tabanidae (Diptera) in North Queensland, Australia

The ability to monitor the abundance and diversity of tabanid flies over wide areas requires effective and low-cost surveillance methods. Such monitoring activities help to quantify the risk of transmission of pathogens by tabanids. Here we examine the effectiveness and practicality of two types of trap (canopy traps and Nzi traps) and two types of attractant (octenol and carbon dioxide) for monitoring tabanid flies in tropical Australia. The Nzi trap consistently caught more tabanids and more species of tabanids than the canopy trap. It was also more robust and therefore required less maintenance in remote locations. The use of attractants substantially increased capture rates, both of individuals and species, and traps using both attractants were consistently the most effective. However, in remote locations, where it is not possible to check traps frequently, the use of attractants may not be feasible. When attractants were not used, the canopy trap caught very few tabanids, but the Nzi trap remained effective enough to be useful as a monitoring device. In addition, the number of tabanid species caught by the Nzi traps remained high, and included those that were most abundant. We therefore conclude that, in this region, Nzi traps are preferable for tabanid monitoring and that attractants greatly improve their effectiveness. However, for longterm monitoring, especially in remote locations, Nzi traps without attractants are a satisfactory option.

Stress-controlled viscoelastic tensile response of bovine cornea

The viscoelastic response of bovine corneas was characterized using in vitro load-controlled uniaxial tension experiments. Specifically, two types of tests were employed: cycled ramp tests over a range of loading rates and creep tests over a range of hold stresses. Multiple replicates of each were used to quantify natural variability as well as mean trends. A preconditioning protocol was used to obtain a unique reference state before testing and to overcome the effects of non-physiological loading. A quasi-linear viscoelastic model incorporating a representation of the microstructure of the cornea was compared to the experimental results. For low stresses and moderate durations this model compares favorably, but overall the material displays non-linearities that cannot be represented within the quasi-linear framework.

Complex hydrological controls on wet dune slacks: the importance of local variability

Dune slacks are a species-rich habitat controlled largely by water chemistry and fluctuations in groundwater. Changes in water chemistry and water table level were analysed in 8 piezometers and 15 ephemeral surface water locations at a large UK dune system over a 12-month period. Total nitrogen concentrations in groundwater varied from 0.27-8.21 mg N L(-1), where dissolved organic nitrogen was dominant at the low nitrogen locations and nitrate was dominant at the high nitrogen locations. Principal components analysis of the water chemistry suggests at least four chemically distinct groundwater signatures. Water levels showed strong temporal heterogeneity. Comparisons of water levels with antecedent rainfall identified a component of year-round groundwater feed and differing seasonal responses overlain by a complex series of lags. In summer, there were lags of four, six and seven months with an additional rapid peaky response to daily rainfall with a one-day lag. In winter, water levels were strongly influenced by exogenous groundwater supply, but again exhibited multiple lags. This study shows that local variations in water chemistry and in hydrological regime can be more complicated than previously thought, with clear implications for optimum management of these high priority habitats for conservation.

Evidence for p-type doping of InN

The first evidence of successful p-type doping of InN is presented. It is shown that InN:Mg films consist of a p-type bulk region with a thin n-type inversion layer at the surface that prevents electrical contact to the bulk. Capacitance-voltage measurements indicate a net concentration of ionized acceptors below the -type surface. Irradiation with 2 MeV He+ ions is used to convert the bulk of InN:Mg from p to n-type, at which point photoluminescence is recovered. The conversion is well explained by a model assuming two parallel conducting layers (the surface and the bulk) in the films.

Rhizome phyllosphere oxygenation in Phragmites and other species in relation to redox potential, convective gas flow, submergence and aeration pathways

Underground rhizomes of emergent aquatic macrophytes are important for perennation, vegetative spread, competition and anchorage. In four species we examined the potential for the development of oxidized phyllospheres around rhizome apical buds, similar to the protective oxygenated rhizospheres around roots. Redox potentials and polarographic measurements of radial oxygen loss were recorded using platinum cathodes around the apical buds. The aeration pathway from atmosphere to phyllosphere was investigated anatomically and by applied pressurized gas flow. Redox potentials increased by +400, +45, +200 and +340 mV around rhizome apices of Phragmites australis, Oryza rhizomatis, Carex rostrata and Glyceria maxima, respectively. Radial oxygen loss from rhizome apices of Phragmites was increased by convective gas flow through the rhizome and by shoot de-submergence, and decreased by resistances applied within the aeration pathway and by shoot submergence. We conclude that oxygen passes via internal gas-space connections between aerial shoot, rhizome and underground buds and into the phyllosphere regions via scale-leaf stomata and surfaces on the buds. We suggest that oxidized phyllospheres may protect rhizome apices against phytotoxins in waterlogged soils, just as oxidized rhizospheres protect roots.

Changes in vegetation and soil characteristics in coastal sand dunes along a gradient of atmospheric nitrogen deposition

A field survey was conducted to detect signals of atmospheric nitrogen (N) in 11 dune systems along a nitrogen deposition gradient in the United Kingdom. In the mobile and semi-fixed dunes, above-ground biomass was positively related to N inputs. This increase was largely due to increased height and cover of Ammophila arenaria. In the long term, this increased biomass may lead to increased organic matter accumulation and consequently accelerated soil development. In the fixed dunes, above ground biomass also showed a positive relationship with N inputs as did soil C : N ratio while soil available N was negatively related to N inputs. Plant species richness was negatively related to N inputs. In the dune slacks, while soil and bulk vegetation parameters showed no relationship with N inputs, cover of Carex arenaria and Hypochaeris radicata increased. Site mean Ellenberg N numbers showed no relationship with N deposition either within habitats or across the whole dataset. Neither abundance-weighting nor inclusion of the Siebel numbers for bryophytes improved the relationship. The survey reveals that the relationships of soil and vegetation with atmospheric N deposition vary between sand dune habitats but, despite this variability, clear correlations with N inputs exist. While this survey cannot establish causality, on the basis of the relationships observed we suggest a critical load range of 10 - 20 kg N ha(-1) yr(-1) for coastal sand dunes in the UK.

Stem cell differentiation and the effects of deficiency

Stem cells have several unique attributes, the key features being their potency and plasticity. They have the ability to give rise to multiple cell lineages and to transdifferentiate into totally different cell type(s) when relocated to a novel stem cell niche. Most self-renewing tissues are served by stem cells. At the ocular surface, the corneo-scleral limbus is believed to provide the niche for corneal epithelial stem cells. A large body of circumstantial evidence, both clinical and basic, supports this view. However, specific identification of limbal stem cells has proved elusive. Cytokeratin markers, vimentin, epidermal growth factor receptors, p63, and others have been used to identify epithelial cell populations at the limbus, which could harbour putative stem cells. In contrast, none of the known haematopoietic stem cell markers namely, CD34 and CD133, stain any specific subset of corneal or limbal epithelial cells. Singly or collectively, none of these markers point to any unique cell(s) that could be regarded as stem cells, supporting the notion that the corneal epithelium is served by 'committed progenitors' rather than by stem cells. Disease or destruction of the corneo-scleral limbus is associated with consequential events that eventually lead to visual impairment or blindness. Conjunctivalisation and vascularisation of the corneal surface and persistent or recurring epithelial defects are hallmarks of limbal deficiency.

The synthesis of a prodrug of doxorubicin designed to provide reduced systemic toxicity and greater target efficacy

Doxorubicin (Dox) can provide some stabilization in prostate cancer; however, its use is limited because of systemic toxicities, primarily cardiotoxicity and immunosuppression. The administration of a prodrug of doxorubicin, designed to permit selective activation by the tumor, would reduce general systemic exposure to the active drug and would thereby increase the therapeutic index. Prostate specific antigen (PSA) is a serine protease with chymotrypsin-like activity that is a member of the kallikrein gene family. PSA's putative physiological role is the liquefaction of semen by virtue of its ability to cleave the seminal fluid proteins semenogelins I and II. Serum PSA levels have been found to correlate well with the number of malignant prostate cells. The use of a prodrug which is cleaved by the enzyme PSA in the prostate should in principle produce high localized concentrations of the cytotoxic agent at the tumor site while limiting systemic exposure to the active drug. Cleavage maps following PSA treatment of human semenogelin were constructed. Systematic modification of the amino acid residues flanking the primary cleavage site led to the synthesis of a series of short peptides which were efficiently hydrolyzed by PSA. Subsequent coupling of selected peptides to doxorubicin provided a series of doxorubicin-peptide conjugates which were evaluated in vitro and in vivo as targeted prodrugs for PSA-secreting tumor cells. From these studies we selected Glutaryl-Hyp-Ala-Ser-Chg-Gln-Ser-Leu-Dox, 27, as the peptide-doxorubicin conjugate with the best profile of physical and biological properties. Compound 27 has a greater than 20-fold selectivity against human prostate PSA-secreting LNCaP cells relative to the non-PSA-secreting DuPRO cell line. In nude mouse xenograft studies, 27 reduced PSA levels by 95% and tumor weight by 87% at a dose below its MTD. Both doxorubicin and Leu-Dox (13) were ineffective in reducing circulating PSA and tumor burden at their maximum tolerated doses. On the basis of these results, we selected 27 for further study to assess its ability to inhibit human prostate cancer cell growth and tumorigenesis.

Modular, mobile-bearing hinge total knee arthroplasty

Early reports of hinge total knee arthroplasty showed high rates of complications and implant failure. Third-generation modular, mobile-bearing, hinge knee arthroplasty systems have evolved to decrease the deleterious stresses that contributed to the failures of earlier designs. The combined series of Barrack et al and Jones et al documents midterm results using the S-ROM Hinge Knee System for patients with significant soft and hard tissue deficiencies not suitable for standard, less constrained, revision knee systems. The combined series included 30 knees with a mean followup of 49 months. Knee Society clinical scores improved from 52 to 134 points. There were no mechanical failures of the implants. The knee system used provides press-fit diaphyseal stems and metaphyseal filling and loading sleeves, all of which showed apposition and positive remodeling of bone at followup radiographic analysis. The excellent midterm results of this modular, mobile-bearing, linked knee system suggest the orthopaedic surgeon can display increasing confidence in the selection of such a knee system when confronted with catastrophic, salvage knee arthroplasty.

Computerized medical records in the Department of Veterans Affairs

The VA Medical Center in Washington, DC, was the nexus for a number of computerization projects that were initiated by the Department of Veterans Affairs. The culmination of these initiatives is a software package that presents the complete electronic patient record in an easy-to-use graphic user interface. This record combines text data from the legacy data base, diagnostic images from patient procedures, electrocardiograms from a commercial server, an Internet connection, and a hospital web site with pertinent reference information. The information is available in over 1000 places in the hospital and can be accessed remotely using a remote access server. The computerization of the medical record has improved hospital efficiency, has made physician access to patient information more reliable, has opened new opportunities for patient education, and has given healthcare providers more time to care for patients.

Total knee arthroplasty using the S-ROM mobile-bearing hinge prosthesis

A retrospective study was performed on 15 patients receiving 16 S-ROM mobile-bearing hinge total knee prostheses that were evaluated with at least a 2-year follow-up (range, 27-71 months). Indications for its use included severe instability and bone loss. The average patient age was 63 years (range, 33-83 years). There were 15 revision arthroplasties and 1 primary arthroplasty. Knee Society scores showed notable improvement in pain, motion, and stability (33.6 preoperatively vs 76.5 postoperatively; P <.0001) and approached significant improvement in function (29.2 preoperatively vs 43.5 postoperatively; P =.11). After excluding a patient with a traumatically ruptured patellar tendon, the probability of the latter comparison improved (P <.01). There was no evidence of loosening, and complete bone apposition was seen in nearly all cases. A high percentage of satisfactory results can be achieved when using this mobile-bearing hinge knee prosthesis for these indications.

PSA-specific and non-PSA-specific conversion of a PSA-targeted peptide conjugate of doxorubicin to its active metabolites

Tumor-selective delivery of doxorubicin by a prostate-specific antigen (PSA)-targeted peptide conjugate prodrug of doxorubicin was demonstrated in a nude mouse xenograft model of human prostate cancer. The prodrug (referred to as doxorubicin conjugate) contains doxorubicin linked to a seven-amino acid peptide conjugate that was designed to increase delivery of doxorubicin to tumor sites through the hydrolytic properties of PSA, which prostate tumors express in high amounts. Following i.p. administration of the doxorubicin conjugate to mice, tumor exposure to doxorubicin was increased 2.5-fold as compared with that achieved after an equimolar dose of doxorubicin itself. However, in heart tissue, the site of clinical dose-limiting toxicity, doxorubicin concentrations observed after administration of doxorubicin conjugate were substantially lower than those in mice that received doxorubicin itself. While the prodrug provided selective delivery of doxorubicin to tumor tissue, there was substantial non-PSA-specific formation of doxorubicin in laboratory animals, a factor that would limit the extent of therapeutic gain of the prodrug. Following i.v. administration to mice, rats, dogs, and monkeys, about one-third of the dose was metabolized to doxorubicin. In tumor-bearing mice, the fraction of the dose metabolized to doxorubicin appeared even higher. This is likely the result of conjugate conversion to doxorubicin by both PSA-specific (in tumor) and non-PSA-specific proteolytic activities. In vitro studies provided further support for the PSA specificity of metabolism; LNCaP cells mediated rapid metabolism of the conjugate, while DuPRO-1 cells, which are deficient in PSA, were incapable of metabolism.

T lymphocytes promote the development of bone marrow-derived APC in the central nervous system

Certain cells within the CNS, microglial cells and perivascular macrophages, develop from hemopoietic myelomonocytic lineage progenitors in the bone marrow (BM). Such BM-derived cells function as CNS APC during the development of T cell-mediated paralytic inflammation in diseases such as experimental autoimmune encephalomyelitis and multiple sclerosis. We used a novel, interspecies, rat-into-mouse T cell and/or BM cell-transfer method to examine the development and function of BM-derived APC in the CNS. Activated rat T cells, specific for either myelin or nonmyelin Ag, entered the SCID mouse CNS within 3-5 days of cell transfer and caused an accelerated recruitment of BM-derived APC into the CNS. Rat APC in the mouse CNS developed from transferred rat BM within an 8-day period and were entirely sufficient for induction of CNS inflammation and paralysis mediated by myelin-specific rat T cells. The results demonstrate that T cells modulate the development of BM-derived CNS APC in an Ag-independent fashion. This previously unrecognized regulatory pathway, governing the presence of functional APC in the CNS, may be relevant to pathogenesis in experimental autoimmune encephalomyelitis, multiple sclerosis, and/or other CNS diseases involving myelomonocytic lineage cells.

A peptide-doxorubicin 'prodrug' activated by prostate-specific antigen selectively kills prostate tumor cells positive for prostate-specific antigen in vivo

We covalently linked doxorubicin with a peptide that is hydrolyzable by prostate-specific antigen. In the presence of prostate tumor cells secreting prostate-specific antigen, the peptide moiety of this conjugate, L-377,202, was hydrolyzed, resulting in the release of leucine-doxorubicin and doxorubicin, which are both very cytotoxic to cancer cells. However, L-377,202 was much less cytotoxic than conventional doxorubicin to cells in culture that do not secrete prostate-specific antigen. L-377,202 was approximately 15 times more effective than was conventional doxorubicin at inhibiting the growth of human prostate cancer tumors in nude mice when both drugs were used at their maximally tolerated doses. Nude mice inoculated with human prostate tumor cells secreting prostate-specific antigen showed considerable reductions in tumor burden with minimal total body weight loss when treated with L-377, 202. This improvement in therapeutic index correlated with the selective localization of leucine-doxorubicin and free doxorubicin in tissues secreting prostate-specific antigen after exposure to L-377,202.

Osteonecrosis in HIV: a case-control study

BACKGROUND

Osteonecrosis (avascular necrosis) has been infrequently reported in HIV-infected patients. It is not known whether HIV itself is an independent risk factor for osteonecrosis.

METHODS

We identified 25 patients with osteonecrosis from 1984 to 1999 from a large county teaching hospital and two large practices in Dallas County that specialize in HIV-disease related therapy. A retrospective chart review was performed to evaluate potential risk factors for osteonecrosis. Each case was matched with two controls for HIV positive status and date of osteonecrosis diagnosis.

RESULTS

In the study, 22 of 25 (88%) case patients had at least one osteonecrosis risk factor compared with 24 of 50 (48%) controls, p =.003. The most common osteonecrosis risk factors were hyperlipidemia (32%), alcoholism (28%), pancreatitis (16%), corticosteroids (12%), and hypercoaguability (12%). Of the cases, 12% were idiopathic. Multiple joints were involved in 72% of cases. Four of the case patients compared with none of the controls received megesterol acetate before the diagnosis of osteonecrosis, p =.01. No significant differences were found between cases and controls with respect to liver function tests, testosterone levels, triglyceride levels, cholesterol levels, or CD4 cell counts. Saquinavir was independently associated with osteonecrosis, p <.05. However, no differences in overall use of protease inhibitors among cases and controls were noted: 79% versus 76%, respectively.

CONCLUSIONS

The increased incidence of osteonecrosis in HIV/AIDS may be due to an increased frequency of risk factors previously associated with osteonecrosis such as hyperlipidemia, corticosteroid use, alcohol abuse, and hypercoaguability. Use of protease inhibitors was not independently associated with osteonecrosis.

Elevation of plasma cortisol during the spawning migration of landlocked kokanee salmon (Oncorhynchus nerka kennerlyi)

Kokanee salmon (Oncorhynchus nerka kennerlyi ), a landlocked subspecies of sockeye salmon, exhibited hypothalamic-pituitary interrenal (HPI, adrenal homologue) axis activation and an increase in plasma cortisol concentration up to 639 +/- 55.9 ng/ml in association with upstream migration in the upper Colorado River even though they were not exposed to a change in salinity and lengthy migration. Kokanee salmon were collected at various stages of migration and concomitant sexual maturation. The pattern of cortisol elevation in kokanee is similar to that in ocean-run sockeye salmon (O. nerka nerka). The presence of plasma cortisol elevation in an upstream migrating, landlocked Pacific salmon suggests that stressors previously considered to cause the cortisol increase, such as long-distance migration and changes in salinity, may not be primary causes of the HPI axis activation.

UCR1 and UCR2 domains unique to the cAMP-specific phosphodiesterase family form a discrete module via electrostatic interactions

The cAMP-specific phosphodiesterases (PDE4) enzymes contain unique "signature" regions of amino acid sequence, called upstream conserved regions 1 and 2 (UCR1 and UCR2). UCR1 and UCR2 are located between the extreme amino-terminal region and the catalytic region of the PDE4 enzymes. The UCR1 of the PDE4D3 isoform was used as a "bait" in a two-hybrid screen, which identified a PDE4D cDNA clone containing UCR2 and the catalytic region but not UCR1. Two-hybrid and "pull down" analysis of constructs incorporating various regions of the PDE4D3 cDNA demonstrated that the carboxyl-terminal region of UCR1 interacted specifically with the amino-terminal region of UCR2. The interaction was blocked by mutations of two positively charged amino acids (Arg-98 and Arg-101 to alanine) located within an otherwise largely hydrophobic region of UCR1. Mutation of three negatively charged amino acids in UCR2 (Glu-146, Glu-147, and Asp-149, all to alanine) also blocked the interaction. The phosphorylation of UCR1 by cAMP-dependent protein kinase (PKA) in vitro attenuated the ability of UCR1 to interact with UCR2. Mutation of the PKA substrate site in UCR1 (Ser-54) to aspartic acid, which mimics the activation of PDE4D3 by PKA, profoundly reduced the interaction between UCR1 and UCR2. Our data are consistent with a model in which UCR1 and UCR2 act as independent domains whose interaction is determined by electrostatic interactions and which may be disrupted by PKA phosphorylation. We suggest that the UCR1 and UCR2 domains may form a module that interacts with and regulates the PDE4 catalytic region.

Distribution of beta-amyloid and amyloid precursor protein in the brain of spawning (senescent) salmon: a natural, brain-aging model

Brain amyloid precursor protein (APP), a normal constituent of neurons, glial cells and cerebrospinal fluid, has several proposed functions (e.g., in neuronal growth and survival). It appears, however, that altered processing of APP is an initial or downstream step in the neuropathology of brain aging, Alzheimer's disease (AD), and Down's syndrome (DS). Some studies suggest that proteolytic cleavage of APP, producing beta-amyloid (Abeta(1-42)), could have neurotoxic or neuroprotective effects. In this study, we utilized antibodies to human APP(695) and Abeta(1-42,) and Congo red staining, to search for amyloid deposition in the brain of semelparous spawning kokanee salmon (Oncorhynchus nerka kennerlyi). Intracellular APP(695) immunoreactivity (APP-ir) was observed in brain regions involved in gustation (glomerulosus complex), olfaction (putative hippocampus, olfactory bulb), vision (optic tectum), the stress response (nucleus preopticus and nucleus lateralis tuberis), reproductive behavior (nucleus preopticus magnocellularis, nucleus preopticus periventricularis, ventral telencephalon), and coordination (cerebellum). Intra- and extra-neuronal Abeta(1-42) immunoreactivity (Abeta-ir) were present in all APP-ir regions except the nucleus lateralis tuberis and Purkinje cells of the cerebellum (coordination). Thus, the relationship between APP and Abeta deposition during brain aging could shed light on the processing of APP into Abeta, neurodegeneration, and possible protection of neurons that are functioning in spawning but senescent salmon. Pacific salmon, with their predictable and synchronized life history, could provide research options not available with the existing models for studies of brain aging and amyloidosis.

Cell density and intracellular translocation of glucocorticoid receptor-immunoreactive neurons in the kokanee salmon (Oncorhynchus nerka kennerlyi) brain, with an emphasis on the olfactory system

This study tested the hypothesis that neurons in olfactory regions of the kokanee salmon brain contain glucocorticoid receptors. Distribution and neuronal number of glucocorticoid receptor-like immunoreactive (GRir) neurons were identified in the kokanee salmon brain using immunohistochemistry with an antibody to GR (polyclonal rabbit anti-human, dilution 1:1500; and monoclonal mouse, dilution 5 micrograms/ml). Distribution of GRir neurons similar to the mammalian pattern was observed in the brains of sexually immature (n = 8; 4 female and 4 male) as well as spawning (n = 8; 4 female and 4 male) salmon. Olfactory-related areas containing GRir positive neuronal bodies included the internal cell layer of the olfactory bulb, ventral-lateral and lateral parts of the dorsal telencephalon (homologue of the mammalian hippocampus), ventral area of the telencephalon (homologue of the mammalian amygdala), glomerulosus complex of the thalamus, the preoptic area, and inferior lobe of the hypothalamus. The pattern of GRir neuronal distribution in sexually immature and spawning fish was similar. However, spawning fish brains, compared to sexually immature brains, exhibited a significantly greater GRir neuronal number in several olfactory regions in paired immunohistochemical runs. There also were differences in intraneuronal location of GRir in olfactory regions, with staining being predominantly cytoplasmic in sexually immature fish but nuclear in spawning fish. These results are consistent with a role for cortisol in olfactory-mediated homing in kokanee salmon. Although GRir were identified in many nonolfactory regions, the focus of this study is on GRir present in brain regions involved in olfaction.

Primary total hip arthroplasty with use of the modular S-ROM prosthesis. Four to seven-year clinical and radiographic results

BACKGROUND

A multicenter retrospective study was conducted to determine the clinical and radiographic results of primary total hip arthroplasty with insertion of the S-ROM modular femoral stem without cement in a series of patients who had been followed for four to seven years. Four centers participated in the study, with one contributing surgeon at each center.

METHODS

Two hundred and eight consecutive patients who had a total hip arthroplasty with implantation of the S-ROM femoral prosthesis at one of the four centers during the study period were identified. Twenty-nine patients were lost to follow-up or had incomplete radiographic data, and twenty patients died from causes unrelated to the index arthroplasty. The remaining 159 patients formed the basis of this study. Sixteen of these patients had a bilateral procedure, resulting in 175 hips with complete clinical and radiographic data. The average age of the patients at the time of the index operation was fifty-nine years (range, twenty-two to ninety-three years). The duration of clinical follow-up averaged 5.3 years (range, four to 7.8 years), and the duration of radiographic follow-up averaged 4.9 years (range, four to 7.3 years).

RESULTS

One patient (0.6 percent) had a failed femoral component, which was evidenced by progressive subsidence and lack of bone ingrowth. In addition, two patients (1 percent) had a revision of the acetabular component. The average Harris hip score increased from 35 points (range, 10 to 76 points) preoperatively to 91 points (range, 52 to 100 points) at the most recent follow-up examination. The radiographic evaluation revealed that 172 hips (98 percent) had stable bone ingrowth, two hips (1 percent) had stable fibrous ingrowth, and one hip (0.6 percent) had unstable fibrous ingrowth. Periprosthetic osteolytic lesions were noted in twelve hips (7 percent). The lesions were observed in the femur in eight hips, in the acetabulum in two hips, and in both the femur and the acetabulum in two hips. All femoral osteolytic lesions were localized within the greater trochanter or the proximal-medial portion of the femoral neck. No osteolytic lesions were evident distal to the stem-sleeve junction.

CONCLUSIONS

Use of the modular S-ROM femoral prosthesis yielded excellent intermediate-term outcomes with respect to standard radiographic and clinical criteria. The issue regarding the theoretical increase in the rate of osteolysis due to metal debris generated at the modular femoral stem-sleeve junction was specifically addressed. We found that the rate of osteolysis in this series was not notably higher than that in other series reported in the orthopaedic literature. Although many possible factors may influence the rate of osteolysis in total hip arthroplasty, this finding suggests that the potential increase in osteolysis theoretically associated with this modular femoral implant was not observed at intermediate-term follow-up. Although longer follow-up is warranted so that the potential for osteolysis can be evaluated fully, no osteolytic lesions were evident distal to the stem-sleeve interface at the time of intermediate-term follow-up. This finding suggests that there is a circumferential seal at the modular junction of the stem that prevents the distal egress of wear debris.