Risk analysis of patients with an osteolytic acetabular defect after total hip arthroplasty using subject-specific finite-element modelling.

AIMS: Osteolysis, secondary to local and systemic physiological effects, is a major challenge in total hip arthroplasty (THA). While osteolytic defects are commonly observed in long-term follow-up, how such lesions alter the distribution of stress is unclear. The aim of this study was to quantitatively describe the biomechanical implication of such lesions by performing subject-specific finite-element (FE) analysis on patients with osteolysis after THA. PATIENTS AND METHODS: A total of 22 hemipelvis FE models were constructed in order to assess the transfer of load in 11 patients with osteolysis around the acetabular component of a THA during slow walking and a fall onto the side. There were nine men and two women. Their mean age was 69 years (55 to 81) at final follow-up. Changes in peak stress values and loads to fracture in the presence of the osteolytic defects were measured. RESULTS: The von Mises stresses were increased in models of those with and those without defects for both loading scenarios. Although some regions showed increases in stress values of up to 100%, there was only a moderate 11.2% increase in von Mises stress in the series as a whole. The site of fracture changed in some models with lowering of the load to fracture by 500 N. The most common site of fracture was the pubic ramus. This was more frequent in models with larger defects. CONCLUSION: We conclude that cancellous defects cause increases in stress within cortical structures. However, these are likely to lead to a modest decrease in the load to fracture if the defect is large (> 20cm3) or if the patient is small with thin cortical structures and low bone mineral density. Cite this article: Bone Joint J 2018;100-B:1455-62.

Responses of endoparasites in red-backed voles (Myodes gapperi) to natural forest fires.

We investigated the responses of endoparasites in red-backed voles (Myodes gapperi) to fire in a boreal forest ecosystem. Because fire affects the environmental conditions and biodiversity of the forest ecosystem, the life cycle of parasites may also be affected because of the absence of intermediate hosts in the environment. We hypothesized that the prevalence of endoparasites would be influenced by the parasites' life cycle and habitat characteristics (forest vs. burned). We found that prevalence of endoparasites was different between forested and burned habitats (chi(2)=37.49, P<0.001). Cestodes, nematodes, and coccidia showed different responses to habitat alteration (chi(2)=37.43, P<0.001). There was a higher prevalence of cestodes in forested (53.5%) than burned habitats (35.0%). However, there was higher prevalence of coccidia in burned (55.0%) than forested (42.9%) habitats. Furthermore, although prevalence of cestode infection was lower in burned than forested habitat, individuals in both habitats had similar intensities of cestodes. Our study showed that habitat can significantly affect the parasite communities, depending on specific parasite life cycles.

The UKNG database: a simple audit tool for interventional neuroradiology.

INTRODUCTION: The UK Neurointerventional Group (UKNG) has developed a unified database for the purposes of recording, analysis and clinical audit of neuroangiography and neurointerventional procedures. It has been in use since January 2002. METHODS: The database utilizes an Access platform (Microsoft) comprising separate but linked programs for data collection and analysis. The program that analyses aneurysm therapy has been designed to mirror the criteria used in the International Subarachnoid Aneurysm Trial (ISAT). RESULTS: Data entered into the main database immediately update the analysis program producing clinical outcome scores in the form of a report. Our local database (Wessex) now contains records on more than 1,750 patients including nearly 350 aneurysm coilings and a total of approximately 500 neurointerventional, vascular procedures. Every time a new piece of information is added to the main database the reporting database is automatically updated which allows 'real-time' audit and analysis of one's clinical practice. The clinical outcome scores for aneurysm treatment are presented in such a way that we can directly compare our results with the 'Clinical Standard' set by ISAT. CONCLUSION: This database provides a unique opportunity to monitor and review practice at national level. The UKNG wishes to share this database with the wider neurointerventional community and a copy of the software can be obtained free of charge from the authors.

Microgeographic genetic structure in the yellow-pine chipmunk (Tamias amoenus).

While there is evidence for broad-scale genetic structure in small mammals, few studies have used variable DNA-based genetic markers to examine genetic differentiation at microgeographic (tens of kilometres) scales. Yellow-pine chipmunks (Tamias amoenus) live in the heterogeneous landscape of the Rockies in southwest Alberta and are generally restricted to areas of low elevation. We used seven microsatellite loci to determine whether chipmunks show evidence of population genetic structure among three closely situated sites (< 15 km) in the Kananaskis Valley, Alberta. We found evidence for genetic structure in the form of significant differences in allele frequencies among populations and significantly nonzero values of FST for both overall and pairwise population comparisons. However, FIS values for each population were not significantly different from zero, suggesting little evidence for inbreeding within populations. Genetic differentiation probably occurs as a result of the strong effect of drift in very small (N(e) approximately 25) populations of these animals even in the face of substantial immigration rates.

Early and periodic screening, diagnosis, and treatment examination completion rates for Oklahoma Medicaid managed care: 1995-1998.

Although quality medical care is a goal of all health care providers, finding a means by which to take that idea from the abstract to the measurable is often an arduous task. The Oklahoma Health Care Authority and the Oklahoma Foundation for Medical Quality confronted that challenge when examining the state of Oklahoma's Early and Periodic Screening, Diagnosis, and Treatment (EPSDT) examination completion rates. Focused on measuring processes of care, the Oklahoma Health Care Authority (OHCA) and the Oklahoma Foundation for Medical Quality (OFMQ) used chart abstraction to track EPSDT examination rates for SoonerCare Plus Medicaid managed care recipients from 1995 through 1998. During the abstractions, an examination was interpreted as an EPSDT screen if a comprehensive health and development history plus a comprehensive unclothed physical examination were recorded. Examination rates have improved from 1995 when there was a documented 17.6% completion rate. The 1998 documented rate of completion was 60.0%. Trend analysis shows significant improvement over the four-year period. The results also suggest the necessity for continued improvement in the provision of documented EPSDT examinations to individuals in Medicaid managed care plans in Oklahoma.

Human triglyceride-rich lipoprotein apo E kinetics and its relationship to LDL apo B-100 metabolism.

Apolipoprotein (apo) E is a multifunctional protein that can act as a ligand for lipoprotein receptors. The receptor-mediated clearance of the triglyceride-rich lipoproteins (TRL) chylomicrons and VLDL from plasma is, in part, dependent on apo E. Enrichment of VLDL with apo E is thought to enhance receptor-mediated clearance of VLDL resulting in a low rate of conversion of VLDL to LDL. However, the kinetic mechanism controlling the concentration of apo E in VLDL is not known. We conducted kinetic studies on apo E in the TRL fraction (d < 1.006 g/ml) and apo B-100 in the TRL and LDL (d = 1.019-1.063 g/ml) fractions to assess the kinetic determinants of apo E concentration in TRL and to determine the effects that TRL apo E production and clearance rates have on the production rate of LDL apo B-100. Nineteen males between the ages of 24 and 73 underwent a primed-constant infusion with deuterated leucine tracer in the constantly-fed state. Apo B-100 from TRL and LDL, and apo E from TRL were isolated and their tracer incorporation measured by gas chromatography/mass spectrometry. The residence time and production rates of each protein were determined from the kinetic data using the SAAM II modeling program. The residence time and production rate of TRL apo E were about one-half that of TRL apo B-100 (1.8 +/- 1.0 vs. 2.9 +/- 2.1 h and 14.5 +/- 11.0 vs. 27.6 +/- 17.3 mg/kg per day, respectively). The production rate of TRL apo E was weakly correlated with the production rate of TRL apo B-100 (r = 0.424, P = 0.07). Multiple regression analysis showed that the residence time of TRL apo B-100 and the relative TRL apo E production rate (relative to the TRL apo B100 production rate) were negatively associated with LDL apo B-100 production rate, accounting for 68% of its variability. We conclude that (1) the concentration of apo E in TRL is highly correlated to its production rate, suggesting that production rate regulates the TRL apo E concentration, and (2) individuals with a relatively short TRL apo B-100 residence time and those producing TRL with a relatively low apo E content have the highest LDL apo B-100 production rates.

Consultations owing to adverse drug reactions in a single practice.

Data was collected over a six-month period on all patients presenting with a suspected adverse drug reaction. Analysis showed that this was a frequent reason for doctor-patient contact and that a large proportion of adverse reactions were owing to a small group of drugs.

The sialylation of plasma lipoproteins.

Sialic acids are a family of amino sugars that are commonly found as terminal oligosaccharide residues on glycoproteins and glycolipids. Plasma lipoproteins are sialylated on their apolipoprotein and glycolipid constituents. The function of sialic acid on apolipoproteins is not completely understood but has been associated with secretion, lipid-binding, and plasma clearance for some apolipoproteins. The sialic acid content of individual apolipoproteins can vary in response to physiological conditions while the sialic acid content of individual sialylated glycolipids (gangliosides) is constant. Thus, the sialic acid content of plasma lipoproteins can differ considerably as a result of (1) variations in the sialylation of their apolipoprotein constituents, (2) variations in their content of sialylated apolipoproteins and gangliosides, and (3) modifications of the sialic acid on lipoprotein constituents while circulating in plasma. The significance of sialic acid on lipoproteins is not fully understood although associations have been made between sialic acid and charge (very low density lipoprotein), lipoprotein solubility, receptor binding and uptake, and interactions with vascular matrix (low density lipoprotein and Lp(a)) and with cholesterol efflux (high density lipoprotein). Further studies identifying sites of sialylation on apolipoproteins and characterizing the structures of sialylated oligosaccharides will aid in determining the enzymes responsible for their sialylation. Manipulations of the sialylation of apolipoproteins and of the quantity of apolipoproteins and gangliosides on lipoproteins will be useful methods in determining the role of lipoprotein sialic acid in the development of atherosclerosis.

Spontaneous dissection of the anterior inferior cerebellar artery.

A patient presented with the clinical features of a brain stem infarct. MRI confirmed changes of infarction but also revealed an unusual lesion in the left cerebellopontine angle cistern. The evolution of this lesion on MRI, together with angiographic changes, indicated a dissecting aneurysm of the left anterior inferior cerebellar artery, a previously unreported phenomenon. The presentation, causes and diagnosis of intracranial dissection are discussed.

Consumer Assessment of Health Plans Survey (CAHPS) results for Oklahoma managed care Medicaid, 1997, 1998, and 1999.

Consumer satisfaction surveys have become an important source of information for purchasers and consumers of health care and health care organizations themselves. Individuals receiving health care provide valuable information regarding access, use of services, and satisfaction with care that can be used for multiple evaluative purposes. The Oklahoma Health Care Authority has adopted the Consumer Assessment of Health Plans Survey (CAHPS) to measure patient satisfaction for the SoonerCare managed care programs. The Oklahoma Foundation for Medical Quality administered the surveys. The adult and child CAHPS core questionnaires served as the basis for the general surveys in 1997 and 1998. The CAHPS for Children with Special Needs survey results and the Pediatric Adaptation of the CAHPS Behavioral Health Survey results were administered in 1999 for baseline measures. Results indicated an overall increase in consumer satisfaction levels across the two CAHPS core questionnaires. Baseline measures for special needs populations were also established.

Immunization rate comparison for Oklahoma Medicaid managed care population by age two: 1995-1998.

Processes of care are used as one measure for the quality of care rendered by providers. One example is the immunization of children by the age of two. The Oklahoma Health Care Authority, with the Oklahoma Foundation for Medical Quality, has been tracking childhood immunization rates from 1995 through 1998. The rate calculated included the medical record data and the Oklahoma Statewide Immunization Information System (OSIIS) data set. The standards were based on Advisory Committee on Immunization Practices recommendations and Quality Assurance Reform Initiative standards. The rate of provision of documented immunizations in the Medicaid managed care population under the age of two has improved markedly from 1995 to 1998. The trend analysis suggests there might be areas for continued improvement in the provision of immunization to individuals in Oklahoma's Medicaid managed care population. Further, the OSIIS data is critical for maintaining a uniform data set for immunization information.

Sialic acid-containing components of lipoproteins influence lipoprotein-proteoglycan interactions.

Sialic acid is a negatively charged sugar associated with the protein and lipid portions of lipoproteins. Sialic acid has been hypothesised to play an anti-atherogenic role in lipoprotein metabolism through the electrostatic inhibition of lipoprotein interactions with chondroitin-6-sulphate-rich arterial proteoglycans (APG). We conducted a series of studies using native and modified lipoproteins (VLDL1 Sf 60-400, VLDL2 Sf 20-60, IDL1 Sf 16-20, IDL2 Sf 12-16, LDL(A) Sf 8-12, and LDL(B) Sf0-8) that vary in their sialic acid content to examine the relationship between lipoprotein sialic acid content and its interaction with APG. Lipoprotein sialic acid was greatest in VLDL1 and decreased progressively with particle density until the IDL2 fraction (VLDL1 > VLDL2 > IDL1 > IDL2 = LDL(A) = LDL(B)). The pattern of reactivity of each fraction with APG was different from the pattern observed for lipoprotein sialic acid content (IDL2 > LDL(A) > LDL(B) > IDL1 > VLDL2 > VLDL1). Levels of sialic acid were lower in subjects with CHD as compared to control subjects but the presence of CHD had no effect on lipoprotein-APG complex formation when sex and plasma triglyceride levels were taken into account. There was also no significant relationship between the lipoprotein sialic acid content and the reactivity with APG within each lipoprotein fraction. Treatment of hypertriglyceridaemic subjects with ciprofibrate decreased lipoprotein-APG complex formation in all lipoprotein fractions. This was associated with a decrease in the total sialic acid content of apo B100-containing lipoproteins suggesting that the total sialic acid content of apo B100-containing lipoproteins has no influence on lipoprotein-APG complex formation. We next conducted in vitro experiments to manipulate LDL sialic acid content. Enzymatic removal of sialic acid from LDL with neuraminidase resulted in an increase in LDL-APG complex formation. This was accompanied by an increase in the exposure of free amino groups on LDL possibly due to disruption of interactions between free amino groups and sialic acid-containing components on LDL. Increasing LDL sialic acid content through incubation with ganglioside resulted in a decrease in lipoprotein-APG complex formation without any changes in the exposure of free amino groups on LDL. We conclude that total sialic acid content of lipoproteins is not a major determinant of their binding to APG. However, specific sialic acid-containing components on lipoproteins can affect their interaction with APG.

Comparison of influenza immunization rates for Oklahoma Medicare patients: 1995, 1996 and 1997.

The Health Care Financing Administration has reported influenza immunization rates since 1994. The Department of Health and Human Services has set a minimum national target rate for the annual immunization of the elderly population at 60 percent, as published in Healthy People 2000. The Oklahoma Foundation for Medical Quality analyzed the Medicare claims data for Oklahoma for the 1995, 1996, and 1997 influenza seasons. Additionally, we reviewed the Behavioral Risk Factor Surveillance System influenza immunization data for 1995. Claims data for the 1997 influenza season show the immunization rate for the Medicare population of Oklahoma is 41.4 percent. The immunization rate for the African-American Medicare population was 22.3 percent for 1997, compared with 42.2 percent for the Caucasian population. The ten most populous counties in the state had a 9-percent higher rate of immunization than the other 67 counties. The Medicare population in Oklahoma is not receiving the influenza vaccination at the target rate. Especially underserved are the African-American and non-urban populations. There appear to be opportunities for improvement in the provision of the influenza vaccination for the Medicare population of Oklahoma.

Proposal of a multicompartmental model for use in the study of apolipoprotein E metabolism.

Apolipoprotein (apo) E is a 299-amino acid glycoprotein that serves a number of functions in lipoprotein metabolism. Apo E binds to the triglyceride-rich lipoproteins (TRL), very-low-density lipoprotein (VLDL), and chylomicrons, as they are lipolyzed, mediating their removal from plasma via lipoprotein receptors. Apo E is also found associated with high-density lipoprotein (HDL) and has been suggested to play a role in reverse cholesterol transport. Studies on the kinetic behavior of apo E from the TRL and HDL fractions provide insights into the metabolic relationships between TRL and HDL in vivo. We sought to develop a compartmental model that can be used for analysis of kinetic data in studies on the metabolism of TRL and HDL apo E. Using radioactive tracers, it has been previously observed that, in some instances, a portion of VLDL apo E that is removed from plasma subsequently reappears in VLDL. Four multicompartmental models were considered that could account for this type of behavior: model A, in which there is transfer of apo E from HDL to VLDL; model B, in which there is a bidirectional extravascular exchange; model C, in which there is removal and subsequent reintroduction of TRL apo E into plasma; and model D, in which there is secretion of TRL apo E into plasma directly and via an extravascular pathway. Models C and D provided the best fit to the experimental data. While no physiologically plausible analog to model C could be found, an extravascular delay, analogous to newly secreted apo E that enters the lymphatic system before appearing in plasma, was postulated for model D. It was this model that was used to analyze kinetic data from metabolic studies of apo E. The model was able to provide a satisfactory fit to kinetic data in studies in which subjects were given a primed-constant infusion of 2H3-leucine. It was determined that TRL apo E from the six subjects studied had a mean residence time of 0.11 +/- 0.05 days and a mean production rate of 10.6 +/- 7.2 mg/kg/d, while HDL apo E had a mean residence time of 2.96 +/- 0.99 days and a mean production rate of 0.07 +/- 0.07 mg/kg/d. We conclude that this model describes a potential pathway for the metabolism of a portion of apo E in plasma and can be used to calculate the residence time and production rate of TRL and HDL apo E under a variety of conditions.