EVOLVE: The Australian Rheumatology Association's 'top five' list of investigations and interventions doctors and patients should question.

BACKGROUND: The EVOLVE (evaluating evidence, enhancing efficiencies) initiative aims to drive safer, higher-quality patient care through identifying and reducing low-value practices. AIMS: To determine the Australian Rheumatology Association's (ARA) 'top five' list of low-value practices. METHODS: A working group comprising 19 rheumatologists and three trainees compiled a preliminary list. Items were retained if there was strong evidence of low value and there was high or increasing clinical use and/or increasing cost. All ARA members (356 rheumatologists and 72 trainees) were invited to indicate their 'top five' list from a list of 12-items through SurveyMonkey in December 2015 (reminder February 2016). RESULTS: A total of 179 rheumatologists (50.3%) and 19 trainees (26.4%) responded. The top five list (percentage of rheumatologists, including item in their top five list) was: Do not perform arthroscopy with lavage and/or debridement for symptomatic osteoarthritis of the knee nor partial meniscectomy for a degenerate meniscal tear (73.2%); Do not order anti-nuclear antibody (ANA) testing without symptoms and/or signs suggestive of a systemic rheumatic disease (56.4%); Do not undertake imaging for low back pain for patients without indications of an underlying serious condition (50.8%); Do not use ultrasound guidance to perform injections into the subacromial space as it provides no additional benefit in comparison to landmark-guided injection (50.3%) and Do not order anti-double-stranded DNA antibodies in ANA negative patients unless the clinical suspicion of systemic lupus erythematosus remains high (45.3%). CONCLUSIONS: This list is intended to increase awareness among rheumatologists, other clinicians and patients about commonly used low-value practices that should be questioned.

Early and progressive circadian abnormalities in Huntington's disease sheep are unmasked by social environment.

Insidious changes in behaviour herald the onset of progressive neurodegenerative disorders such as Huntington's disease (HD), sometimes years before overt symptoms are seen. Sleep and circadian disturbances are particularly disruptive symptoms in patients with neurological disorders, but they are difficult to measure in humans. Here we studied circadian behaviour in transgenic HD sheep expressing the full-length human huntingtin protein with an expanded CAG repeat mutation in the juvenile range. Young HD sheep with no other symptoms exhibited circadian behavioural abnormalities that worsened with age. The most obvious change was a disturbed evening behaviour reminiscent of 'sundowning' that is seen in some patients with dementia. There were no structural abnormalities seen with magnetic resonance imaging, even in 5-year-old HD sheep. Interestingly, detection of the circadian abnormalities depended upon their social grouping. Abnormalities emerged in sheep kept in an 'HD-only' flock, whereas the behaviour of HD sheep kept mixed with normal sheep was relatively normal. Sleep-wake abnormalities in HD patients are also likely to be hidden, and may precede overt symptoms by many years. Sleep disruption has deleterious effects, even in normal people. The knock-on effects of sleep-wake disturbance may exacerbate, or even cause symptoms such as irritability and depression that are common in early stage HD patients. HD sheep will be useful models for probing the mechanisms underlying circadian behavioural disorder in HD.

Initial findings and potential applicability of computational simulation of the aorta in acute type B dissection.

OBJECTIVE: Type B aortic dissection can be acutely complicated by rapid expansion, rupture, and malperfusion syndromes. Short-term adverse outcomes are associated with failure of the false lumen to thrombose. The reasons behind false lumen patency are poorly understood, and the objective of this pilot study was to use computational fluid dynamics reconstructions of aortic dissection cases to analyze the effect of aortic and primary tear morphology on flow characteristics and clinical outcomes in patients with acute type B dissections. METHODS: Three-dimensional patient-specific aortic dissection geometry was reconstructed from computed tomography scans of four patients presenting with acute type B aortic dissection and a further patient with sequential follow-up scans. The cases were selected based on their clinical presentation. Two were complicated by acute malperfusion that required emergency intervention. Three patients were uncomplicated and were managed conservatively. The patient-specific aortic models were used in computational simulations to assess the effect of aortic tear morphology on various parameters including flow, velocity, shear stress, and turbulence. RESULTS: Pulsatile flow simulation results showed that flow rate into the false lumen was dependent on both the size and position of the primary tear. Linear regression analysis demonstrated a significant relationship between percentage flow entering the false lumen and the size of the primary entry tear and an inverse relationship between false lumen flow and the site of the entry tear. Subjects complicated by malperfusion had larger-dimension entry tears than the uncomplicated cases (93% and 82% compared with 32% and 55%, respectively). Blood flow, wall shear stress, and turbulence levels varied significantly between subjects depending on aortic geometry. Highest wall shear stress (>7 Pa) was located at the tear edge, and progression of false lumen thrombosis was associated with prolonged particle residence times. CONCLUSIONS: Results obtained from this preliminary work suggest that aortic morphology and primary entry tear size and position exert significant effects on flow and other hemodynamic parameters in the dissected aorta in this preliminary work. Blood flow into the false lumen increases with increasing tear size and proximal location. Morphologic analysis coupled with computational fluid dynamic modeling may be useful in predicting acute type B dissection behavior allowing for selection of proper treatment modalities, and further confirmatory studies are warranted.

Disruption of peripheral circadian timekeeping in a mouse model of Huntington's disease and its restoration by temporally scheduled feeding.

Behavioral circadian rhythms disintegrate progressively in the R6/2 mouse model of Huntington's disease (HD), recapitulating the sleep-wake disturbance seen in HD patients. Here we show that disturbances in circadian pacemaking are not restricted to the brain, but also encompass peripheral metabolic pathways in R6/2 mice. Notably, circadian rhythms of clock-driven genes that are key metabolic outputs in the liver are abolished in vivo. This deficiency is accompanied by arrhythmic expression of the clock genes Cry1 and Dbp, and a phase-advanced Per2 cycle. Compromised circadian metabolic cycles are not, however, a consequence of deficient pacemaking intrinsic to the liver, because when cultured in vitro, R6/2 liver slices exhibit self-sustained circadian bioluminescence rhythms. We therefore propose that compromised metabolic cycles arise from an internal desynchronization secondary to altered feeding patterns and impaired circadian signaling from the central pacemaker of the suprachiasmatic nucleus (SCN). Importantly, the SCN-independent food-entrainable oscillator remains intact in R6/2 mice and, when invoked, can restore daily behavioral cycles and reverse some of the metabolic abnormalities seen in the liver. Disturbances of metabolism have long been thought to be an important feature of HD. Uncoupling liver metabolism from circadian drives will reduce metabolic efficiency and cause imbalances in metabolites known to be deleterious to brain function. Thus, even subtle imbalances in liver function may exacerbate symptoms of HD, where neurological function is already compromised.

"Brain training" improves cognitive performance and survival in a transgenic mouse model of Huntington's disease.

Environmental enrichment (EE) has been shown to improve neurological function and cognitive performance in animal models of Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). We have shown recently that even when they are already living in an enriched environment, additional EE had beneficial effects in R6/2 mice. Here we examined the effects of three different enrichment paradigms on cognitive dysfunction in R6/2 mice in a longitudinal study. The EE consisted of either enforced physical exercise on the Rotarod (predominantly motor stimulation), training in a novel type of maze, the 'noughts and crosses' (OX) maze (mainly cognitive stimulation), or access to a playground, that gave the mice the opportunity for increased, self-motivated activity using running wheels and other toys in a social context (mixed EE). We designed the OX maze to test spatial memory in the R6/2 mouse while minimizing motor demands. Control mice remained in their home cages during the training period. Mice were given enrichment between 6 and 8 weeks of age, followed by cognitive (Lashley maze) and motor testing (Rotarod) between 8 and 10 weeks. Mice were then given a further period of enrichment between 10 and 12 weeks, and their behavior was re-tested between 12 and 14 weeks of age. We also collected body weights and age at death from all mice. The OX maze was as sensitive for detecting learning deficits in the R6/2 mice as other types of mazes (such as the Morris water maze). Interestingly, providing cognitive stimulation via training in the OX maze produced significant improvements in subsequent cognitive performance by male, but not female, R6/2 mice in the Lashley maze task. OX maze training also significantly improved loss of body weight and survival in male R6/2 mice. These effects became apparent after as little as 2 weeks of training in the OX maze. These data suggest that there is a cognitive reserve that may be exploited in neurodegenerative disease. While brain training was not beneficial for all mice, it produced no deleterious effects, and so warrants further study in rodent models of HD.

Recommendations for measuring whisker movements and locomotion in mice with sensory, motor and cognitive deficits.

BACKGROUND: Previous studies have measured whisker movements and locomotion to characterise mouse models of neurodegenerative disease. However, these studies have always been completed in isolation, and do not involve standardized procedures for comparisons across multiple mouse models and background strains. NEW METHOD: We present a standard method for conducting whisker movement and locomotion studies, by carrying out qualitative scoring and quantitative measurement of whisker movements from high-speed video footage of mouse models of Amyotrophic Lateral Sclerosis, Huntington's disease, Parkinson's disease, Alzheimer's disease, Cerebellar Ataxia, Somatosensory Cortex Development and Ischemic stroke. RESULTS: Sex, background strain, source breeder and genotype all affected whisker movements. All mouse models, apart from Parkinson's disease, revealed differences in whisker movements during locomotion. R6/2 CAG250 Huntington's disease mice had the strongest behavioural phenotype. Robo3R3-5-CKO and RIM-DKOSert mouse models have abnormal somatosensory cortex development and revealed significant changes in whisker movements during object exploration. COMPARISON WITH EXISTING METHOD(S): Our results have good agreement with past studies, which indicates the robustness and reliability of measuring whisking. We recommend that differences in whisker movements of mice with motor deficits can be captured in open field arenas, but that mice with impairments to sensory or cognitive functioning should also be filmed investigating objects. Scoring clips qualitatively before tracking will help to structure later analyses. CONCLUSIONS: Studying whisker movements provides a quantitative measure of sensing, motor control and exploration. However, the effect of background strain, sex and age on whisker movements needs to be better understood.

Characterisation of progressive motor deficits in whisker movements in R6/2, Q175 and Hdh knock-in mouse models of Huntington's disease.

BACKGROUND: Motor dysfunction is a major component of the Huntington's disease (HD) phenotype, both in patients and animal models. Motor function in mice is usually measured using tests that involve a novel environment, or require a degree of learning, which creates potential confounds in animals, such as anxiety and/or learning. NEW METHOD: We propose that studying whisker control provides a more naturalistic way to measure motor function in HD mice. To this end we tested three strains of HD mice; R6/2 (CAG250), zQ175 and Hdh (CAG50, 150 and 250) mice. RESULTS: We discovered a clear and progressive whisking deficit in the most severe model, the R6/2 CAG250 mouse. At 10 weeks, R6/2 mice showed an increase in whisking movements, which may be a correlate of the hyperkinesia seen in HD patients. By 18 weeks the R6/2 mice showed a reduction in whisking movements. Hdh Q250 mice showed a hyperkinetic profile at 10 weeks, approximately 4 months before other motor deficits have previously been reported in these mice. Q175 mice showed very little change in whisking behaviour, apart from a transient increase in retraction velocity at 10 weeks. COMPARISONS WITH EXISTING METHODS: Our findings suggest that whisking may be a more sensitive test of motor function in HD mice than more commonly used methods, such as the rotarod. CONCLUSIONS: Our data suggest that whisking deficits represent a novel way of assessing the progression of the motor phenotype, and are early indicators for reversal of phenotype studies, such as drug trials.

XJB-5-131-mediated improvement in physiology and behaviour of the R6/2 mouse model of Huntington's disease is age- and sex- dependent.

We have reported that the radical scavenger XJB-5-131 attenuates or reverses progression of the disease phenotype in the HdhQ(150/150) mouse, a slow onset model of HD. Here, we tested whether XJB-5-131 has beneficial effects in R6/2 mice, a severe early onset model of HD. We found that XJB-5-131 has beneficial effects in R6/2 mice, by delaying features of the motor and histological phenotype. The impact was sex-dependent, with a stronger effect in male mice. XJB-5-131 treatment improved some locomotor deficits in female R6/2 mice, but the effects were, in general, greater in male mice. Chronic treatment of male R6/2 mice with XJB-5-1-131 reduced weight loss, and improved the motor and temperature regulation deficits, especially in male mice. Treatment with XJB-5-131 had no effect on the lifespan of R6/2 mice. Nevertheless, it significantly slowed somatic expansion at 90 days, and reduced the density of inclusions. Our data show that while treatment with XJB-5-131 had complex effects on the phenotype of R6/2 mice, it produced a number of significant improvements in this severe model of HD.

A computational study on the influence of catheter-delivered intravascular probes on blood flow in a coronary artery model.

Catheter-delivered intravascular probes are widely used in clinical practice to measure coronary arterial velocity and pressure, but the artefactual effect of the probe on the variables being measured is not well characterised. A coronary artery was simulated with a 180 degrees curved tube 3mm in diameter and the effect of catheters of different diameters was modelled numerically under pulsatile flow conditions. The presence of a catheter increased pressure by 1.3-4.3 mmHg depending on its diameter, and reduced velocity-pressure phase-lag. For an ultrasound sample volume 5mm downstream from the probe tip, the underestimation in velocity measurement attributed to catheter blockage is approximately 15-21% for an average inlet velocity of 0.1m/s. The velocity measurement error is lower at higher mean flow velocity. Accuracy of clinical velocity measurements could be improved by moving the sample volume farther downstream from the probe tip, because the centrifugal pressure gradient intrinsic to the curvature promotes re-development of flow.

Disintegration of the sleep-wake cycle and circadian timing in Huntington's disease.

Sleep disturbances in neurological disorders have a devastating impact on patient and carer alike. However, their pathological origin is unknown. Here we show that patients with Huntington's disease (HD) have disrupted night-day activity patterns. This disruption was mirrored in a transgenic model of HD (R6/2 mice) in which daytime activity increased and nocturnal activity fell, eventually leading to the complete disintegration of circadian behavior. The behavioral disturbance was accompanied by marked disruption of expression of the circadian clock genes mPer2 and mBmal1 in the suprachiasmatic nuclei (SCN), the principal circadian pacemaker in the brain. The circadian peak of expression of mPer2 was prematurely truncated, and the mRNA levels of mBmal1 were attenuated and failed to exhibit a significant circadian oscillation. Circadian cycles of gene expression in the motor cortex and striatum, markers of behavioral activation in wild-type mice, were also suppressed in the R6/2 mice, providing a neural correlate of the disturbed activity cycles. Increased daytime activity was also associated with reduced SCN expression of prokineticin 2, a transcriptional target of mBmal1 encoding a neuropeptide that normally suppresses daytime activity in nocturnal mammals. Together, these molecular abnormalities could explain the pathophysiological changes in circadian behavior. We propose that circadian sleep disturbances are an important pathological feature of HD, that they arise from pathology within the SCN molecular oscillation, and that their treatment will bring appreciable benefits to HD patients.

3D geometric reconstruction of thoracic aortic aneurysms.

BACKGROUND: The thoracic aortic aneurysm (TAA) is a pathology that involves an expansion of the aortic diameter in the thoracic aorta, leading to risk of rupture. Recent studies have suggested that internal wall stress, which is affected by TAA geometry and the presence or absence of thrombus, is a more reliable predictor of rupture than the maximum diameter, the current clinical criterion. Accurate reconstruction of TAA geometry is a crucial step in patient-specific stress calculations. METHODS: In this work, a novel methodology was developed, which combines data from several sets of magnetic resonance (MR) images with different levels of detail and different resolutions. Two sets of images were employed to create the final model, which has the highest level of detail for each component of the aneurysm (lumen, thrombus, and wall). A reference model was built by using a single set of images for comparison. This approach was applied to two patient-specific TAAs in the descending thoracic aorta. RESULTS: The results of finite element simulations showed differences in stress pattern between the coarse and fine models: higher stress values were found with the coarse model and the differences in predicted maximum wall stress were 30% for patient A and 11% for patient B. CONCLUSION: This paper presents a new approach to the reconstruction of an aneurysm model based on the use of several sets of MR images. This enables more accurate representation of not only the lumen but also the wall surface of a TAA taking account of intraluminal thrombus.

Similar Progression of Morphological and Metabolic Phenotype in R6/2 Mice with Different CAG Repeats Revealed by In Vivo Magnetic Resonance Imaging and Spectroscopy.

BACKGROUND: Huntington's disease (HD) is caused by an unstable polyglutamine (CAG) repeat in the HD gene, whereby a CAG repeat length greater than ∼36 leads to the disease. In HD patients, longer repeats correlate with more severe disease and earlier death. This is also seen in R6/2 mice carrying repeat lengths up to ∼200. Paradoxically, R6/2 mice with repeat lengths >300 have a less aggressive phenotype and longer lifespan than those with shorter repeats. The mechanism underlying this phenomenon is unknown. OBJECTIVE: To investigate the consequences of longer repeat lengths on structural changes in the brains of R6/2 mice, especially with regard to progressive atrophy. METHODS: We used longitudinal in vivo magnetic resonance imaging (MRI) and spectroscopy (MRS) to compare pathological changes in two strains of R6/2 mice, one with a rapidly progressing disease (250 CAG repeats), and the other with a less aggressive phenotype (350 CAG repeats). RESULTS: We found significant progressive brain atrophy in both 250 and 350 CAG repeat mice, as well as changes in metabolites (glutamine/glutamate, choline and aspartate). Although similar in magnitude, atrophy in the brains of 350 CAG R6/2 mice progressed more slowly than that seen in 250 CAG mice, in line with the milder phenotype and longer lifespan. Interestingly, significant atrophy was detectable in 350 CAG mice as early as 8-12 weeks of age, although behavioural abnormalities in these mice are not apparent before 25-30 weeks. This finding fits well with human data from the PREDICT-HD and TRACK-HD project, where reductions in brain volume were found 10 years in advance of the onset of symptoms. CONCLUSIONS: The similar brain atrophy with a mismatch between onset of brain atrophy and behavioural phenotype in HD mice with 350 repeats will make this mouse particularly useful for modelling early stages of HD pathology.

Plasma Decontamination: A Case Study on Kill Efficacy of Geobacillus stearothermophilus Spores on Different Carrier Materials.

A new technology to the pharmaceutical field is presented: surface decontamination by plasmas The technology is comparable to established barrier systems like e-beam, volatile hydrogen peroxide, or radiation inactivation of microbiological contaminations. This plasma technology is part of a fully automated and validated syringe filling line at a major pharmaceutical company and is in production operation. Incoming pre-sterilized syringe containers ("tubs") are processed by plasma, solely on the outside, and passed into the aseptic filling isolator upon successful decontamination. The objective of this article is to present the operating principles and develop and establish a validation routine on the basis of standard commercial biological indicators. Their decontamination efficacies are determined and correlated to the actual inactivation efficacy on the pharmaceutical packaging material.The reference setup is explained in detail and a short presentation of the cycle development and the relevant plasma control parameters is given, with a special focus on the in-process monitor determining the cycle validity. Different microbial inactivation mechanisms are also discussed and evaluated for their contribution and interaction to enhance plasma decontamination. A material-dependent inactivation behavior was observed. In order to be able to correlate the tub surface inactivation of Geobacillus stearothermophilus endospores to metallic biological indicators, a comparative study was performed. Through consistently demonstrating the linear inactivation behavior between the different materials, it becomes possible to develop an effective and time-saving validation scheme. LAY ABSTRACT: The challenge in new decontamination systems lies in a thorough validation of the inactivation efficacy under different operating regimes. With plasma, as an ionized gas, a new barrier concept is introduced into pharmaceutical aseptic processing of syringes. The presented system operates in vacuum and only decontaminates the outer surface of pre-sterilized syringe containers ("tubs"), before they are transferred into the aseptic area. The plasma does not penetrate into the tub. This article discusses the phase from development and test germ selection, across the identified sporicidal mechanisms, to a proposal for a validation scheme on the basis of commercially available biological indicators. A special focus is placed on an extensive investigation to establish a link between the tub surface microbial kill (polystyrene and Tyvek(and (2)) ) and biological indicator inactivation (stainless steel). Additionally, a rationale is developed on how an optical in-process monitor can be applied to establish a validatable limit on the base of the predetermined inactivation data of Geobacillus stearothermophilus endospores.

Assessment of Hemodynamic Conditions in the Aorta Following Root Replacement with Composite Valve-Conduit Graft.

This paper presents the analysis of detailed hemodynamics in the aortas of four patients following replacement with a composite bio-prosthetic valve-conduit. Magnetic resonance image-based computational models were set up for each patient with boundary conditions comprising subject-specific three-dimensional inflow velocity profiles at the aortic root and central pressure waveform at the model outlet. Two normal subjects were also included for comparison. The purpose of the study was to investigate the effects of the valve-conduit on flow in the proximal and distal aorta. The results suggested that following the composite valve-conduit implantation, the vortical flow structure and hemodynamic parameters in the aorta were altered, with slightly reduced helical flow index, elevated wall shear stress and higher non-uniformity in wall shear compared to normal aortas. Inter-individual analysis revealed different hemodynamic conditions among the patients depending on the conduit configuration in the ascending aorta, which is a key factor in determining post-operative aortic flow. Introducing a natural curvature in the conduit to create a smooth transition between the conduit and native aorta may help prevent the occurrence of retrograde and recirculating flow in the aortic arch, which is particularly important when a large portion or the entire ascending aorta needs to be replaced.

Social Behaviour is Impaired in the R6/2 Mouse Model of Huntington's Disease.

BACKGROUND: Huntington's disease (HD) is characterised by a combination of motor, cognitive and psychiatric symptoms. HD patients also exhibit deficits in social behaviour. While motor and cognitive dysfunction in the R6/2 transgenic mouse model of HD has been well described, social disorders have not been reported. OBJECTIVE: To compare social behaviour in R6/2 and wildtype (WT) mice, using two different measures of sociability. METHODS: R6/2 mice were tested in the habituation/dishabituation test as a measure of social recognition, and the resident-intruder paradigm, as a measure of social interaction. RESULTS: In the social recognition test, WT mice remained interested in female mice throughout the testing period. Male R6/2 mice showed reduced interest in female mice from 14 weeks of age, while still recognising novel female mice. In the resident intruder test, R6/2 residents showed a lack of interest in the intruder. Interestingly, WT resident mice showed more aggressive behaviour towards R6/2 than WT intruders. This aggressive behaviour stopped once the barrier was removed, but WT mice showed increased risk assessment and escape behaviours while interacting with R6/2 intruders. CONCLUSIONS: R6/2 mice have deficits in social behaviours. Phenotypic male R6/2 mice show a decreased interest in females,mirroring the hyposexuality seen in HD patients. Furthermore, R6/2 mice show a lack of interest in intruder mice, suggesting social apathy. The abnormal response of WT mice to R6/2 mice suggests that R6/2 mice do not generate appropriate social cues.Our data suggest that R6/2 mice have deficits in social behaviour that replicate the disrupted social behaviours seen in HD.

A viscoelastic fluid-structure interaction model for carotid arteries under pulsatile flow.

In this study, a fluid-structure interaction model (FSI) incorporating viscoelastic wall behaviour is developed and applied to an idealized model of the carotid artery under pulsatile flow. The shear and bulk moduli of the arterial wall are described by Prony series, where the parameters can be derived from in vivo measurements. The aim is to develop a fully coupled FSI model that can be applied to realistic arterial geometries with normal or pathological viscoelastic wall behaviour. Comparisons between the numerical and analytical solutions for wall displacements demonstrate that the coupled model is capable of predicting the viscoelastic behaviour of carotid arteries. Comparisons are also made between the solid only and FSI viscoelastic models, and the results suggest that the difference in radial displacement between the two models is negligible.

Geometric and flow features of type B aortic dissection: initial findings and comparison of medically treated and stented cases.

Uncomplicated acute type B aortic dissections are usually treated medically, but they can become acutely complicated by rapid expansion, rupture and malperfusion syndromes and in the longer term by chronic dilatation and aortic aneurysm formation. The objective of this study is to use computational fluid dynamics reconstructions of type B aortic dissections to compare geometric and haemodynamic factors between the cases selected for medical treatment and the cases selected for thoracic endovascular aortic repair (TEVAR), and to examine whether any of these factors are associated with the outcome of the medically treated group. This study includes eight type B dissection cases, with four in each group. Aortic flow analyses were carried out based on patient-specific anatomy at initial presentation before treatment. Comparisons between the two groups show that the false lumen to true lumen volume ratio is considerably higher in patients selected for TEVAR. Results from the four medically treated cases indicate that the size of the primary entry tear is the key determinant of the false lumen flow rate, which may influence the long-term outcome of medically treated patients. Potential relations between flow related parameters based on initial anatomy and subsequent anatomical changes in the medically treatment group were examined. Our initial findings based on the limited cases are that high relative residence time is a strong predictor of subsequent false lumen thrombosis, whereas pressure difference between the true and false lumen as well as the location of the largest pressure difference may be associated with the likelihood of subsequent aortic expansion.

Flow pattern analysis in a highly stenotic patient-specific carotid bifurcation model using a turbulence model.

The aim of this study is to investigate the blood flow pattern in carotid bifurcation with a high degree of luminal stenosis, combining in vivo magnetic resonance imaging (MRI) and computational fluid dynamics (CFD). A newly developed two-equation transitional model was employed to evaluate wall shear stress (WSS) distribution and pressure drop across the stenosis, which are closely related to plaque vulnerability. A patient with an 80% left carotid stenosis was imaged using high resolution MRI, from which a patient-specific geometry was reconstructed and flow boundary conditions were acquired for CFD simulation. A transitional model was implemented to investigate the flow velocity and WSS distribution in the patient-specific model. The peak time-averaged WSS value of approximately 73 Pa was predicted by the transitional flow model, and the regions of high WSS occurred at the throat of the stenosis. High oscillatory shear index values up to 0.50 were present in a helical flow pattern from the outer wall of the internal carotid artery immediately after the throat. This study shows the potential suitability of a transitional turbulent flow model in capturing the flow phenomena in severely stenosed carotid arteries using patient-specific MRI data and provides the basis for further investigation of the links between haemodynamic variables and plaque vulnerability. It may be useful in the future for risk assessment of patients with carotid disease.

RT-PCR permits simultaneous genotyping of thiopurine S-methyltransferase allelic variants by multiplex induced heteroduplex analysis.

Thiopurine-based drugs are a widely prescribed group of medications. Their tolerance and effectiveness is dependent on an individual's ability to metabolize these compounds. An essential enzyme for the metabolism of these drugs is thiopurine S-methyltransferase (TPMT), whose activity is subject to genetic variation. Genotyping of the most frequent allelic variants in TPMT affords an extremely accurate prediction of the three clinical phenotypes: high, intermediate, and low enzyme activity. One constraint of most genotyping methods is the inability to demonstrate physical linkage between two sequence variants that occur in different exons, e.g., c.460G>A and c.719A>G, which give rise to TPMT*3, the most common defective allele in Caucasian populations. Using mRNA/cDNA as a template enables analysis of both sequence variants in a single assay. This approach could be applicable to other genes where allelic variation (in-cis and in-trans) is due to alterations in different exons. Induced heteroduplex generator analysis has previously been shown to discriminate in-cis and has also been suitable for multiplexing. In this method we have exploited both these features and for the first time have applied them to a RT-PCR analysis. The primary reagent developed allows unequivocal resolution of TPMT*3A and the alleles carrying the c.719A>G allelic variant, TPMT*3C, as well as the silent alteration c.474T>C. The TPMT*3B variant has not been observed. A secondary reagent, which can be multiplexed, identifies the TPMT*2 allele.

Homocysteine and cerebral infarction in finnish male smokers.

BACKGROUND AND PURPOSE: Homocysteine is associated with stroke, but it is not clear whether this relationship is causal. We examined the association between total serum homocysteine concentration (tHcy) and cerebral infarction in a cohort of Finnish male smokers. METHODS: This is a matched case-control study of 201 cases of cerebral infarction and 201 concurrently sampled age-matched controls nested in a cohort of 13 840 male smokers free of cardiovascular disease at the completion of the Alpha-Tocopherol and Beta-Carotene (ATBC) Cancer Prevention study. Conditional logistic regression was used to calculate odds ratios (ORs) and to adjust for confounding variables. An unmatched analysis was also performed. RESULTS: The geometric mean tHcy was 13.3 micromol/L (95% CI, 12.6 to 13.9) in cases and 12.6 micromol/L (95% CI, 12.0 to 13.2) in controls (P=0.09). There was a graded increase in the OR of cerebral infarction per quartile increase in tHcy (OR, 1.0, 1.7, 1.9, 2.1; trend P=0.02; 201 case-control pairs) when adjusted for traditional risk factors. There was a similar trend in a subgroup of 120 case-control pairs for which further adjustment for lifestyle factors was possible (OR, 1.0, 1.9, 2.5, 2.2; trend P=0.07 in the matched analyses; OR, 1.0, 1.2, 1.9, 2.0; trend P=0.02 in the unmatched analyses). The adjusted OR per 1-SD increase in log-transformed tHcy (equivalent to 4.7 micromol) was 1.4 (95% CI, 1.1 to 1.7; P=0.01). CONCLUSIONS: tHcy appears to predict cerebral infarction in Finnish male smokers.