Correlation Tracking: Using simulations to interpolate highly correlated particle tracks

Despite significant advances in particle imaging technologies over the past two decades, few advances have been made in particle tracking, i.e., linking individual particle positions across time series data. The state-of-the-art tracking algorithm is highly effective for systems in which the particles behave mostly independently. However, these algorithms become inaccurate when particle motion is highly correlated, such as in dense or strongly interacting systems. Accurate particle tracking is essential in the study of the physics of dense colloids, such as the study of dislocation formation, nucleation, and shear transformations. Here, we present a method for particle tracking that incorporates information about the correlated motion of the particles. We demonstrate significant improvement over the state-of-the-art tracking algorithm in simulated data on highly correlated systems.

Impact of Rigidity on Molecular Self-Assembly

Rigid, cage-like molecules, like diamondoids, show unique self-assembly behavior, such as templating 1-D nanomaterial assembly via pathways that are typically blocked for such bulky substituents. We investigate molecular forces between diamondoids to explore why molecules with high structural rigidity exhibit these novel assembly pathways. The rigid nature of diamondoids significantly lowers configurational entropy, and we hypothesize that this influences molecular interaction forces. To test this concept, we calculated the distance-dependent impact of entropy on assembly using molecular dynamics simulations. To isolate pairwise entropic and enthalpic contributions to assembly, we considered pairs of molecules in a thermal bath, fixed at set intermolecular separations but otherwise allowed to freely move. By comparing diamondoids to linear alkanes, we draw out the impact of rigidity on the entropy and enthalpy of pairwise interactions. We find that linear alkanes actually exhibit stronger van der Waals interactions than diamondoids at contact, because the bulky structure of diamondoids induces larger net atomic separations. Yet, we also find that diamondoids pay lower entropic penalties when assembling into contact pairs. Thus, the cage-like shape of diamondoids introduces an enthalpic penalty at contact, but the penalty is counterbalanced by entropic effects. Investigating the distance dependence of entropic forces provides a mechanism to explore how rigidity influences molecular assembly. Our results show that low entropic penalties paid by diamondoids can explain the effectiveness of diamondoids in templating nanomaterial assembly. Hence, tuning molecular rigidity can be an effective strategy for controlling the assembly of functional materials, such as biomimetic surfaces and nanoscale materials.

Myelin status is associated with change in functional mobility following slope walking in people with multiple sclerosis

Background

The level of myelin disruption in multiple sclerosis patients may impact the capacity for training-induced neuroplasticity and the magnitude of therapeutic response to rehabilitation interventions. Downslope walking has been shown to increase functional mobility in individuals with multiple sclerosis, but it is unclear if myelin status influences therapeutic response.

Objective

The current study aimed to examine the relationship between baseline myelin status and change in functional mobility after a walking intervention.

Methods

The Timed Up and Go test was used to measure functional mobility before and after completion of a repeated, six-session slope walking intervention in 16 participants with relapsing–remitting multiple sclerosis. Multi-component T₂ relaxation imaging was used to index myelin water fraction of overall water content in brain tissue compartments.

Results

Results demonstrated that the ratio of the myelin water fraction in lesion to normal-appearing white matter (myelin water fraction ratio) significantly predicted 31% of the variance in change in Timed Up and Go score after the downslope walking intervention, where less myelin disruption was associated with greater intervention response.

Conclusions

Myelin water content fraction ratio may offer a neural biomarker of myelin to identify potential responders to interventions targeting functional impairments in multiple sclerosis.

The cross-over to magnetostrophic convection in planetary dynamo systems

Global scale magnetostrophic balance, in which Lorentz and Coriolis forces comprise the leading-order force balance, has long been thought to describe the natural state of planetary dynamo systems. This argument arises from consideration of the linear theory of rotating magnetoconvection. Here we test this long-held tenet by directly comparing linear predictions against dynamo modelling results. This comparison shows that dynamo modelling results are not typically in the global magnetostrophic state predicted by linear theory. Then, in order to estimate at what scale (if any) magnetostrophic balance will arise in nonlinear dynamo systems, we carry out a simple scaling analysis of the Elsasser number Λ, yielding an improved estimate of the ratio of Lorentz and Coriolis forces. From this, we deduce that there is a magnetostrophic cross-over length scale, [Formula: see text], where Λ_o is the linear (or traditional) Elsasser number, Rm_o is the system scale magnetic Reynolds number and D is the length scale of the system. On scales well above [Formula: see text], magnetostrophic convection dynamics should not be possible. Only on scales smaller than [Formula: see text] should it be possible for the convective behaviours to follow the predictions for the magnetostrophic branch of convection. Because [Formula: see text] is significantly smaller than the system scale in most dynamo models, their large-scale flows should be quasi-geostrophic, as is confirmed in many dynamo simulations. Estimating Λ_o ≃1 and Rm_o ≃10³ in Earth's core, the cross-over scale is approximately 1/1000 that of the system scale, suggesting that magnetostrophic convection dynamics exists in the core only on small scales below those that can be characterized by geomagnetic observations.

A systematic review of animal based indicators of sheep welfare on farm, at market and during transport, and qualitative appraisal of their validity and feasibility for use in UK abattoirs

In the UK, it has been suggested that abattoirs are ideal locations to assess the welfare of sheep as most are slaughtered at abattoirs either as finished lambs or cull ewes. Data from abattoirs could provide benchmarks for welfare indicators at a national level, as well as demonstrating how these change over time. Additionally, feedback could be provided to farmers and regulatory authorities to help improve welfare and identify high or low standards for quality assurance or risk-based inspections. A systematic review of the scientific literature was conducted, which identified 48 animal-based indicators of sheep welfare that were categorised by the Five Freedoms. Their validity as measures of welfare and feasibility for use in abattoirs were evaluated as potential measures of prior sheep welfare on the farm of origin, at market, or during transportation to the abattoir. A total of 19 indicators were considered valid, of which nine were considered theoretically feasible for assessing sheep welfare at abattoirs; these were body cleanliness, carcass bruising, diarrhoea, skin lesions, skin irritation, castration, ear notching, tail docking and animals recorded as 'obviously sick'. Further investigation of these indicators is required to test their reliability and repeatability in abattoirs. Novel welfare indicators are needed to assess short-term hunger and thirst, prior normal behaviour and long-term fear and distress.

Human papillomavirus DNA in men who have sex with men: type-specific prevalence, risk factors and implications for vaccination strategies

Background:

Human papillomavirus (HPV) vaccination of girls will have relatively little effect on HPV-related disease in men who have sex with men (MSM). We determined HPV prevalence and risk factors in MSM to inform the potential effectiveness of vaccinating MSM.

Methods:

Cross-sectional study of 522 MSM aged 18–40 attending a London sexual health clinic who completed a computer-assisted self-interview. Urine and two swabs (anal and penile/scrotal/perianal) were collected and tested using an in-house Luminex-based HPV genotyping system.

Results:

Prevalence of DNA of the vaccine-preventable HPV types in ano-genital specimens of men was 87/511 (17.0%), 166/511 (32.5%) and 232/511 (45.4%) for the bivalent (HPV16/18), quadrivalent (HPV6/11/16/18) and nonavalent (HPV6/11/16/18/31/33/45/52/58) vaccine types, respectively. A total of 25.1% had one of the quadrivalent types, and 7.4% had 2+ types. Median age at first anal sex was 19 (IQR 17–23) and at first clinic attendance was 24 (IQR 20–27). The increase in the odds of any HPV infection per year of age was 4.7% (95% CI 1.2–8.4).

Conclusions:

On the basis of the current infection status, most MSM, even among a high-risk population attending a sexual health clinic, are not currently infected with the vaccine-type HPV. A targeted vaccination strategy for MSM in the UK could have substantial benefits.

Approaching the asymptotic regime of rapidly rotating convection: boundary layers versus interior dynamics

Rapidly rotating Rayleigh-Bénard convection is studied by combining results from direct numerical simulations (DNS), laboratory experiments, and asymptotic modeling. The asymptotic theory is shown to provide a good description of the bulk dynamics at low, but finite Rossby number. However, large deviations from the asymptotically predicted heat transfer scaling are found, with laboratory experiments and DNS consistently yielding much larger Nusselt numbers than expected. These deviations are traced down to dynamically active Ekman boundary layers, which are shown to play an integral part in controlling heat transfer even for Ekman numbers as small as 10^{-7}. By adding an analytical parametrization of the Ekman transport to simulations using stress-free boundary conditions, we demonstrate that the heat transfer jumps from values broadly compatible with the asymptotic theory to states of strongly increased heat transfer, in good quantitative agreement with no-slip DNS and compatible with the experimental data. Finally, similarly to nonrotating convection, we find no single scaling behavior, but instead that multiple well-defined dynamical regimes exist in rapidly rotating convection systems.

Corticosteroids and β₂-agonists upregulate mitogen-activated protein kinase phosphatase 1: in vitro mechanisms

BACKGROUND AND PURPOSE

Airway remodelling is a consequence of long-term inflammation and MAPKs are key signalling molecules that drive pro-inflammatory pathways. The endogenous MAPK deactivator--MAPK phosphatase 1 (MKP-1)--is a critical negative regulator of the myriad pro-inflammatory pathways activated by MAPKs in the airway.

EXPERIMENTAL APPROACH

Herein we investigated the molecular mechanisms responsible for the upregulation of MKP-1 in airway smooth muscle (ASM) by the corticosteroid dexamethasone and the β₂-agonist formoterol, added alone and in combination.

KEY RESULTS

MKP-1 is a corticosteroid-inducible gene whose expression is enhanced by long-acting β₂-agonists in an additive manner. Formoterol induced MKP-1 expression via the β₂-adrenoceptor and we provide the first direct evidence (utilizing overexpression of PKIα, a highly selective PKA inhibitor) to show that PKA mediates β₂-agonist-induced MKP-1 upregulation. Dexamethasone activated MKP-1 transcription in ASM cells via a cis-acting corticosteroid-responsive region located between -1380 and -1266 bp of the MKP-1 promoter. While the 3'-untranslated region of MKP-1 contains adenylate + uridylate elements responsible for regulation at the post-transcriptional level, actinomycin D chase experiments revealed that there was no increase in MKP-1 mRNA stability in the presence of dexamethasone, formoterol, alone or in combination. Rather, there was an additive effect of the asthma therapeutics on MKP-1 transcription.

CONCLUSIONS AND IMPLICATIONS

Taken together, these studies allow us a greater understanding of the molecular basis of MKP-1 regulation by corticosteroids and β₂-agonists and this new knowledge may lead to elucidation of optimized corticosteroid-sparing therapies in the future.

Regulation of glucose kinetics during exercise by the glucagon-like peptide-1 receptor

In response to oral glucose, glucagon-like peptide-1 receptor (Glp1r) knockout (Glp1r−/−) mice become hyperglycaemic due to impaired insulin secretion. Exercise also induces hyperglycaemia in Glp1r−/− mice. In contrast to oral glucose, exercise decreases insulin secretion. This implies that exercise-induced hyperglycaemia in Glp1r−/− mice results from the loss of a non-insulinotropic effect mediated by the Glp1r. Muscle glucose uptake (MGU) is normal in exercising Glp1r−/− mice. Thus, we hypothesize that exercise-induced hyperglycaemia in Glp1r−/− mice is due to excessive hepatic glucose production (HGP). Wild-type (Glp1r+/+) and Glp1r−/− mice implanted with venous and arterial catheters underwent treadmill exercise or remained sedentary for 30 min. [3-3H]glucose was used to estimate rates of glucose appearance (Ra), an index of HGP, and disappearance (Rd). 2[14C]deoxyglucose was used to assess MGU. Glp1r−/− mice displayed exercise-induced hyperglycaemia due to an excessive increase in Ra but normal Rd and MGU. Exercise-induced glucagon levels were ∼2-fold higher in Glp1r−/− mice, resulting in a ∼2-fold higher glucagon:insulin ratio. Since inhibition of the central Glp1r stimulates HGP, we tested whether intracerebroventricular (ICV) infusion of the Glp1r antagonist exendin(9–39) (Ex9) in Glp1r+/+ mice would result in exercise-induced hyperglycaemia. ICV Ex9 did not enhance glucose levels or HGP during exercise, suggesting that glucoregulatory effects of Glp1 during exercise are mediated via the pancreatic Glp1r. In conclusion, functional disruption of the Glp1r results in exercise-induced hyperglycaemia associated with an excessive increase in glucagon secretion and HGP. These results suggest an essential role for basal Glp1r signalling in the suppression of alpha cell secretion during exercise.

Corticosteroid-induced gene expression in allergen-challenged asthmatic subjects taking inhaled budesonide

BACKGROUND AND PURPOSE

Inhaled corticosteroids (ICS) are the cornerstone of asthma pharmacotherapy and, acting via the glucocorticoid receptor (GR), reduce inflammatory gene expression. While this is often attributed to a direct inhibitory effect of the GR on inflammatory gene transcription, corticosteroids also induce the expression of anti-inflammatory genes in vitro. As there are no data to support this effect in asthmatic subjects taking ICS, we have assessed whether ICS induce anti-inflammatory gene expression in subjects with atopic asthma.

EXPERIMENTAL APPROACH

Bronchial biopsies from allergen-challenged atopic asthmatic subjects taking inhaled budesonide or placebo were subjected to gene expression analysis using real-time reverse transcriptase-PCR for the corticosteroid-inducible genes (official gene symbols with aliases in parentheses): TSC22D3 [glucocorticoid-induced leucine zipper (GILZ)], dual-specificity phosphatase-1 (MAPK phosphatase-1), both anti-inflammatory effectors, and FKBP5 [FK506-binding protein 51 (FKBP51)], a regulator of GR function. Cultured pulmonary epithelial and smooth muscle cells were also treated with corticosteroids before gene expression analysis.

KEY RESULTS

Compared with placebo, GILZ and FKBP51 mRNA expression was significantly elevated in budesonide-treated subjects. Budesonide also increased GILZ expression in human epithelial and smooth muscle cells in culture. Immunostaining of bronchial biopsies revealed GILZ expression in the airways epithelium and smooth muscle of asthmatic subjects.

CONCLUSIONS AND IMPLICATIONS

Expression of the corticosteroid-induced genes, GILZ and FKBP51, is up-regulated in the airways of allergen-challenged asthmatic subjects taking inhaled budesonide. Consequently, the biological effects of corticosteroid-induced genes should be considered when assessing the actions of ICS. Treatment modalities that increase or decrease GR-dependent transcription may correspondingly affect corticosteroid efficacy.

A multi-allergen standard for the calibration of immunoassays: CREATE principles applied to eight purified allergens

BACKGROUND

Allergen measurements are widely used for environmental exposure assessments and for determining the potency of allergen vaccines, yet few purified allergen standards have been developed. The aim of the study was to develop a single standard containing multiple purified allergens that could be used in enzyme immunoassays and in multiplex arrays for the standardization of allergen measurements.

METHODS

Eight purified allergens were formulated into a single multi-allergen, or 'universal', standard based on amino acid analysis. Dose-response curves were compared with previous individual ELISA standards and allergen measurements of house dust extracts to obtain correction factors. Measured allergen concentrations were also modeled using linear regression, and the predictive accuracy was determined.

RESULTS

Parallel dose-response curves were obtained between the universal allergen standard and the individual ELISA standards, with close agreement between curves for 5/8 allergens. Quantitative differences of greater than twofold were observed for Fel d 1, Can f 1, and Der f 1, which were confirmed by the analysis of house dust extracts. Correction factors were developed that allowed ELISA data to be expressed in terms of the universal standard. Linear regression data confirmed the predictive accuracy of the universal standard.

CONCLUSION

This study shows that a single standard of eight purified allergens can be used to compare allergen measurements by immunoassay. This approach will improve the continuity of environmental exposure assessments and provide improved standardization of allergy diagnostics and vaccines used for immunotherapy.

Factors associated with changes of state of foot conformation and lameness in a flock of sheep

The aim of this research was to investigate transitions between foot conformation, lameness and footrot in sheep. Data came from one lowland flock of approximately 700 ewes studied for 18 months. Multilevel multistate analyses of transitions between good and poor foot conformation states in ewes, and lame and non-lame states in ewes and lambs were conducted. Key results were that the longer sheep had feet in good conformation, the more likely they were to stay in this state; similarly, the longer a ewe was not lame the more likely she was not to become lame. Ewes with poor foot conformation were more likely to become lame (OR: 1.83 (1.24-2.67)) and to be >4 years (OR: 1.50 (1.09-2.05)). Ewes with footrot were less likely to move to good foot conformation (OR: 0.48 (0.31-0.75)) and were more likely to become lame (OR: 3.81 (2.60-5.59)). Ewes lame for >4 days and not treated with parenteral antibacterials had a higher risk of developing (OR: 2.00 (1-3.61)), or remaining in (OR: 0.49 (0.29-0.95)), poor foot conformation compared with ewes never lame. Treatment of ewes lame with footrot with parenteral antibacterials increased the probability of transition from a lame to a non-lame state (OR: 1.46 (1.05-2.02)) and these ewes, even if lame for >4 days, were not more likely to develop poor foot conformation. The risk of a ewe becoming lame increased when at least one of her offspring was lame (OR: 2.03 (1.42-2.92)) and when the prevalence of lameness in the group was ≥5% (OR: 1.42 (1.06-1.92)). Lambs were at increased risk of becoming lame when they were male (OR: 1.42 (1.01-2.01)), single (OR: 1.86 (1.34-2.59)) or had a lame dam or sibling (OR: 3.10 (1.81-5.32)). There were no explanatory variables associated with lambs recovering from lameness. We conclude that poor foot conformation in ewes increases the susceptibility of ewes to become lame and that this can arise from untreated footrot. Treatment of ewes lame with footrot with parenteral antibacterials leads to recovery from lameness and prevents or resolves poor foot conformation which then reduces the susceptibility to further lameness with footrot.

Effect of improved home ventilation on asthma control and house dust mite allergen levels

BACKGROUND

The warm, humid environment in modern homes favours the dust mite population, but the effect of improved home ventilation on asthma control has not been established. We tested the hypothesis that a domestic mechanical heat recovery ventilation system (MHRV), in addition to allergen avoidance measures, can improve asthma control by attenuating re-colonization rates.

METHODS

We conducted a randomized double-blind placebo-controlled parallel group trial of the installation of MHRV activated in half the homes of 120 adults with asthma, allergic to Dermatophagoides pteronyssinus. All homes had carpets steam cleaned and new bedding and mattress covers at baseline. The primary outcome was morning peak expiratory flow (PEF) at 12 months.

RESULTS

At 12 months, the primary end-point; change in mean morning PEF as compared with baseline, did not differ between the MHRV group and the control group (mean difference 13.5 l/min, 95% CI: -2.6 to 29.8, P = 0.10). However, a secondary end-point; evening mean PEF, was significantly improved in the MHRV group (mean difference 24.5 l/min, 95% CI: 8.9-40.1, P = 0.002). Indoor relative humidity was reduced in MHRV homes, but there was no difference between the groups in Der p 1 levels, compared with baseline.

CONCLUSIONS

The addition of MHRV to house dust mite eradication strategies did not achieve a reduction in mite allergen levels, but did improve evening PEF.

Potentiation of NF-kappaB-dependent transcription and inflammatory mediator release by histamine in human airway epithelial cells

BACKGROUND AND PURPOSE

In asthma, histamine contributes to bronchoconstriction, vasodilatation and oedema, and is associated with the late phase response. The current study investigates possible inflammatory effects of histamine acting on nuclear factor kappaB (NF-kappaB)-dependent transcription and cytokine release.

EXPERIMENTAL APPROACH

Using BEAS-2B bronchial epithelial cells, NF-kappaB-dependent transcription and both release and mRNA expression of IL-6 and IL-8 were examined by reporter assay, ELISA and quantitative RT-PCR. Histamine receptors were detected using qualitative RT-PCR and function examined using selective agonists and antagonists.

KEY RESULTS

Addition of histamine to TNFalpha-stimulated BEAS-2B cells maximally potentiated NF-kappaB-dependent transcription 1.8 fold, whereas IL-6 and IL-8 protein release were enhanced 7.3- and 2.7-fold respectively. These responses were, in part, NF-kappaB-dependent and were associated with 2.6- and 1.7-fold enhancements of IL-6 and IL-8 mRNA expression. The H(1) receptor antagonist, mepyramine, caused a rightward shift in the concentration-response curves of TNFalpha-induced NF-kappaB-dependent transcription (pA(2)=9.91) and release of IL-6 (pA(2)=8.78) and IL-8 (pA(2)=8.99). Antagonists of histamine H(2), H(3) and H(4) receptors were without effect. Similarly, H(3) and H(4) receptor agonists did not affect TNFalpha-induced NF-kappaB-dependent transcription, or IL-6 and IL-8 release at concentrations below 10 microM. The anti-inflammatory glucocorticoid, dexamethasone, inhibited the histamine enhanced NF-kappaB-dependent transcription and IL-6 and IL-8 release.

CONCLUSIONS AND IMPLICATIONS

Potentiation of NF-kappaB-dependent transcription and inflammatory cytokine release by histamine predominantly involves receptors of the H(1) receptor subtype. These data support an anti-inflammatory role for H(1) receptor antagonists by preventing the transcription and release of pro-inflammatory cytokines.

Coexisting pathologies in the brain: influence of vascular disease and Parkinson's disease on Alzheimer's pathology in the hippocampus

The finding of more than one coexisting brain pathology in dementia sufferers is not unusual. However, it is unclear how these different diseases may interact or influence the evolution of one another. In this study we analyse the hippocampal expression patterns of hyperphosphorylated tau, paired helical filament (PHF)-related protein, beta-amyloid and synaptophysin in a group of Alzheimer's disease (AD) sufferers with and without additional pathology. Compared to cases with only AD-type pathology we found that the presence of additional vascular disease augmented the accumulation of hyperphosphorylated tau in the CA1 region of the hippocampus without affecting PHF formation in cases with mild AD changes and reduced the extent of PHF formation in the CA2/3 and CA4 regions of the hippocampus in cases with severe AD pathology. We also found that synaptophysin immunoreactivity in the CA4 and dentate gyrus in pure AD was inversely related to the extent of amyloid accumulation but not to neurofibrillary pathology in the same regions. These relationships were lost when additional pathology was present. Memory scores obtained during life correlated closely with hyperphosphorylated tau and PHF-related protein expression in CA1 in pure AD but not in AD with additional pathology. Total amyloid and synaptophysin expression in the hippocampus did not correlate with memory scores in any patient group. Our findings suggest that the interactions of two pathologies in the hippocampus are complex and may differ depending on the stage reached in the evolution of a progressive disease such as AD.

The progression of Alzheimer's disease from limbic regions to the neocortex: clinical, radiological and pathological relationships

Alzheimer's disease (AD) is characterised by the gradual accumulation of neurofibrillary pathology in selected regions of the brain. Earlier studies indicate that the accumulation of neurofibrillary tangles is associated both with decline in patient's cognitive performance as well as with medial temporal lobe atrophy on CT scans. There are also indications that progression through the pathological stages of AD is associated with decline in cognitive functions. The results of this study indicate that progression of disease, especially beyond the boundaries of the limbic regions, is associated with marked decline in the cognitive performance of patients suffering from AD. However the clinical manifestations of early pathological stages are not so well defined. We also found that the atrophy of the medial temporal lobe on CT scans is related to the progression of pathology. Atrophy is most apparent when the disease reaches its isocortical stages and is not marked in the limbic stages of the disease. The additive effect of pathologies co-existing with AD is apparent in reduced cognitive scores, while the atrophy of limbic structures, as measured on CT scans, seems to be mainly attributable to AD-related pathology.

Comparison of pathological diagnostic criteria for Alzheimer disease

Because the clinical picture of Alzheimer disease (AD) is often difficult to discriminate from other dementing illnesses, the diagnosis of AD requires neuropathological confirmation. However, for the pathological diagnosis of AD, there are no unanimously accepted criteria. The three currently used sets of pathological criteria (Khachaturian: Khachaturian, Arch Neurol 1985;42:1097-105; Tiemy: Tierney et al., Can J Neurol Sci 1986; 13:424-6; CERAD: Mirra et al., Neurology 1991;41:479-86) for the disease differ from each other considerably. We applied these criteria to the first 43 consecutive subjects (37 demented) with no neuropathology other than AD-type pathology from autopsies after longitudinal prospective clinical study in the Oxford Project to Investigate Memory and Ageing (OPTIMA). The results show that the CERAD category of definite AD corresponds closely with the cases that fulfill Tierney A3 inclusion criteria for AD. The combined CERAD categories of possible, probable, and definite AD correspond closely to cases fulfilling Khachaturian criteria forAD. The influence of a clinical diagnosis of dementia when Khachaturian and CERAD criteria were applied was considerable because between 9.3% and 90.7% of patients would have been categorized differently depending on whether clinical dementia was present or absent.

Longitudinal study of inflammatory factors in serum, cerebrospinal fluid, and brain tissue in Alzheimer disease: interleukin-1beta, interleukin-6, interleukin-1 receptor antagonist, tumor necrosis factor-alpha, the soluble tumor necrosis factor receptors I and II, and alpha1-antichymotrypsin

There is evidence consistent with the hypothesis that inflammatory and immune mechanisms are involved in the pathogenesis of Alzheimer disease (AD). We have investigated whether the levels of inflammatory associated proteins in serum or lumbar cerebrospinal fluid (CSF) reflect the progressive cognitive decline and brain atrophy of AD-patients. Levels of interleukin-1beta(IL-1beta), IL-1 receptor antagonist (IL-1ra), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), the soluble TNF receptors type I and II (sTNFR I and II), and the acute phase protein alpha1-antichymotrypsin (x1-ACT) were determined in paired serum and CSF samples taken yearly over a period of 2-5 years from pathologically confirmed AD patients (n = 8) and normal controls or non-AD subjects with other CNS pathology (n = 9). No significant differences were found between AD subjects and controls in the mean levels of the above mediators. There was also no correlation in either subject group between the levels of these inflammatory mediators in serum or CSF, and the change in cognitive status or the progression of the atrophy of the medial temporal lobe measured by X-ray computed tomography (CT). The concentrations of IL-1beta, IL-6, and TNF-alpha were determined in brain tissue specimens of five to nine different brain regions in six of the AD patients and four of the non-AD subjects. The levels of IL-1beta and IL-6 in the various brain regions were not significantly different in the AD and the non-AD group. However, in AD patients the level of TNF-alpha was significantly lower in the frontal cortex (32%, p = 0.024), the superior temporal gyrus (57%, p = 0.021), and the entorhinal cortex (49%, p = 0.009) compared with non-AD subjects. Low levels of TNF-alpha in the brain areas that showed neuropathology in AD may indicate a dysregulation of the inflammatory process in AD. Despite this finding, this study does not support the use of measurements of any of the inflammatory mediators investigated here as a diagnostic parameter for AD, due the large overlap in the levels of these factors between AD patients and other subjects, and the poor relation to clinical signs of AD.

Accuracy of clinical operational diagnostic criteria for Alzheimer's disease in relation to different pathological diagnostic protocols

In this study we analysed the accuracy of two sets of clinical diagnostic criteria, the NINCDS/ADRDA and DSM-III-R, in relation to the currently used pathological diagnostic criteria for Alzheimer's disease (AD), the Khachaturian criteria, the Tierney A3 criteria and the CERAD protocol. The sensitivity of the individual clinical diagnostic criteria, NINCDS/ADRDA and DSM-III-R, is poor (34-58%) irrespective of the pathological diagnostic criteria applied for the definite diagnosis of AD. The combination of the NINCDS/ ADRDA 'possible' and 'probable dementia of the Alzheimer type' (DAT) categories has a high sensitivity (91-98%). However the combination resulted in very poor specificity (40-61 %). Thus, none of the clinical diagnostic criteria is satisfactory. We found similar results when we analysed the predictive value of these clinical diagnostic criteria. The positive predictive value of NINCDS 'probable DAT' category and that of the DAT diagnosis by DSM-III-R is very high (89-100%). This makes the use of these categories suitable for research purposes. However, the negative predictive value of both diagnoses is poor (33-63%), making these criteria unsuitable for diagnostic purposes in clinical practice.

The effects of additional pathology on the cognitive deficit in Alzheimer disease

The diagnosis of Alzheimer disease (AD) according to current criteria is a combined clinical and pathological exercise. The clinical discrimination of AD from other types of dementia may be complicated when the patient suffers from more than one disease. In particular the concomitant presence of other neurological conditions may significantly influence the severity of cognitive deficit. In this study we analyze the extent of the influence of vascular and other neurodegenerative pathology on the cognitive deficit in a consecutive series of 88 prospectively assessed elderly subjects. We find that, for any given level of cognitive deficit, the densities of either all plaques or neuritic plaques alone in the neocortex are significantly lower in cases of AD mixed with other CNS pathology than in cases of AD with no other CNS pathology. In AD combined with cerebrovascular disease, the total plaque density makes a significant contribution to cognitive deficit, while neurofibrillary tangle (NFT) densities do not. In contrast, in pure AD tangle density is the major determinant of cognitive deficit. Our findings draw attention to the influence of coexisting brain pathologies on the clinical manifestation of dementia in subjects with AD. These findings indicate that pathological diagnostic criteria for AD should take into account such additional pathology in demented subjects. They also improve understanding of the circumstances in which the amyloid component of AD can play a decisive role in precipitating clinical dementia.

Clustering of pathological features in Alzheimer's disease: clinical and neuroanatomical aspects

We have analyzed the tendency of amyloid load, neuritic plaques and neurofibrillary tangles (NFT) in the hippocampus and neocortex to occur in clusters in 49 consecutive cases of Alzheimer's disease (AD). This clustering tendency of the pathology was analysed in relation to severity of clinical disease assessed within 6 months before death, duration and age at onset of disease and at death. Amyloid plaques showed only a slight tendency to cluster together while neuritic plaques and, even more, NFT were clearly clustered. A greater clustering tendency was associated with more severe clinical impairment with particularly strong correlations being found between the clustering tendency of NFT in the hippocampus and clinical memory deficit, and between the clustering tendency of NFT in the parietal neocortex and overall cognitive deficit. Neuritic plaques showed similar but less pronounced and robust correlations between clustering and cognitive status. In the hippocampus NFT clustering was also negatively correlated with age at death, but not duration of disease nor age of disease onset. We conclude that clustering characterises neuritic pathology but not diffuse amyloid deposits and significantly affects cognition. The discrepancies between the group diagnosed as AD-only and the patient group that contained all patients, including the ones with mixed pathology, lead us to believe that any additional pathology might have a significant effect on the cognitive status of AD patients.

Testing and evaluation of a hip extensor tricycle for children with cerebral palsy

The design and testing of a modified tricycle (hip extensor tricycle) designed to isolate and exercise the hip extensor muscles in children with cerebral palsy is presented. Initial laboratory tests involved stability evaluation and EMG studies of two normal children. Field evaluation involved five children diagnosed with cerebral palsy who were given hip extensor tricycles for home use during an 8-week test period. The hip extensor strength and gait pattern of the subjects were recorded at 2-week intervals. The clinical tests indicated that the hip extensor tricycle was more stable, and resulted in more hip extensor muscle activity, than the traditional therapeutic/exercise tricycle. A panel of experts judged that the gait patterns of four of the five subjects improved during the course of the study. Parent evaluations indicated that the use of the hip extensor tricycle improved the subjects' physical condition, coordination, sense of accomplishment, and self-esteem.

Hippocampal pathology reflects memory deficit and brain imaging measurements in Alzheimer's disease: clinicopathologic correlations using three sets of pathologic diagnostic criteria

Neurofibrillary tangles (NFT), neuritic plaques and amyloid load were quantified in sections of the hippocampus at the level of the lateral geniculate body in 41 consecutive cases fulfilling pathological criteria for diagnosis of Alzheimer's disease (AD) and coming to autopsy after longitudinal study during life. A strong correlation was found between NFT density in the hippocampus and cognitive impairment scores obtained shortly before death, particularly with scores of memory impairment. Weaker and less consistent correlations were found for hippocampal neuritic plaques and amyloid load with cognitive/memory deficits. No significant correlations were found between hippocampal pathology and either age of onset or disease duration. All three measures of hippocampal pathology were inversely correlated with the minimum medial temporal lobe (MTL) width, a measure of the MTL atrophy made from temporal-lobe-oriented X-ray computed tomography scans performed during life; the strongest correlation being between atrophy of the MTL and NFT density in the hippocampus.

A survey of antimicrobial susceptibility of clinical isolates of Enterococcus spp. from Irish hospitals

Nosocomial enterococcal infections are increasing. In order to establish the species distribution and antibiotic resistance patterns of enterococci in clinical specimens from hospitalized patients, we undertook a survey of 23 Irish hospitals. One thousand and five viable enterococcal strains were studied. Nine different species of enterococci were identified, including Enterococcus faecalis (84%); Enterococcus faecium (9%); and Enterococcus hirae (3%). The most common sites of isolation were the urinary tract (66%), wound and soft tissues (23%) and blood stream (3%). Many of the isolates were multiply antibiotic resistant. Ampicillin resistance was detected in 16%. Neither beta-lactamase production, nor high level penicillin resistance was detected. High level gentamicin resistance was evident in 7% of isolates and varied among species, e.g. 4% E. faecalis, 24% E. faecium, and 34% E. hirae. A number of isolates (23%) were also highly resistant to streptomycin. No clinically significant glycopeptide resistance was detected. The species distribution and incidence of multiple resistance was geographically widespread. This emphasizes the need for detailed speciation and in-vitro susceptibility testing along with the evaluation of alternative combination chemotherapeutic regimens for the management of serious enterococcal infection.

Relative roles of plaques and tangles in the dementia of Alzheimer's disease: correlations using three sets of neuropathological criteria

We have performed a quantitative analysis of the amyloid load (plaques), neuritic plaques and neurofibrillary tangles (NFT) in the frontal, temporal and parietal association cortices of autopsied brains from 49 prospectively evaluated patients with Alzheimer's disease (AD) diagnosed according to three sets of published pathological criteria. These patients had been assessed clinically with psychological testing of cognitive abilities within 6 months of death. Correlations were sought between severity of pathological change and cognitive status before death, duration of disease and age at death. Using Khachaturian and CERAD criteria highly positive correlations were obtained between the extent of cognitive deficit and the density of NFT in frontal and parietal lobes. The percentage area of cortex occupied by amyloid in the parietal lobe was correlated to the cognitive deficit only in the CERAD-diagnosed cases. The density of all amyloid plaques (AP) showed no correlation with the extent of cognitive deficit, but the densities of neuritic plaques did correlate with cognitive deficit. Both amyloid load and tangle densities were positively correlated with disease duration. All these correlations were reduced or absent in a subgroup of cases fulfilling the Tierney et al. A3 diagnostic criteria for AD. We found no pathological measure that correlated with the age of patients at death. Amyloid loads and NFT densities showed highly significant but selective positive correlations, the most striking being between temporal lobe NFT density and frontal and parietal lobe amyloid load and between temporal lobe NFT density and frontal and parietal lobe NFT densities. Correlations involving AP density as a measure of amyloid load were almost always less significant than those involving the percentage area of cortex occupied by amyloid, suggesting that the latter measures amyloid load more accurately. However, the highest correlations of NFT densities were with neuritic plaque densities. Overall this study highlights the relevance of neuritic changes (revealed by NFT and neuritic plaques) and the irrelevance of amyloid plaques to the dementia of AD.

Evaluation of a device to exercise hip extensor muscles in children with cerebral palsy: a clinical and field study

This research includes the effectiveness of a tricycle (hip extensor tricycle) designed to isolate and exercise the hip extensor muscles in children with cerebral palsy. Five children diagnosed with cerebral palsy were given hip extensor tricycles for home use during an 8-week test period. The hip extensor strength and gait pattern of the subjects were recorded at 2-week intervals. Additional recorded information included the time and duration of subject use and a parent evaluation that noted subjective physical and psychological improvements. A panel of experts judged that the gait patterns of four subjects improved during the course of the study. There was an assignable cause for the lack of improvement in the fifth subject. The results of the strength testing were found to be inconclusive. The subjects used the device on a regular basis and enjoyed doing so. Parent evaluations indicated that the use of the hip extensor tricycle improved the subjects' physical condition, coordination, sense of accomplishment, and self esteem. It is recommended that future research implement a longer test period along with improved hip extensor strength measurement methods and focus on improvements in evaluation of gait and physical condition.

Evaluation of the hip-extensor tricycle in improving gait in children with cerebral palsy

Weakness of the hip extensor muscles contributes to the walking impairment of children with cerebral palsy, but it is difficult to strengthen these muscles. This study demonstrates greater activation of the hip extensor muscles when using a tricycle developed for this purpose than when using a traditional tricycle. The hip-extensor tricycle was also found to be more stable than a traditional tricycle. A 10-week field trial of the hip-extensor tricycle showed that visually analysed gait improved, but hip extensor strength did not. However, children used and enjoyed the tricycle, and parental reports were positive. This tricycle could be used to supplement other means of improving gait in children with CP.

Autopsy: consent, completion and communication in Alzheimer's disease research

The definitive diagnosis of Alzheimer's disease remains histopathological. To date many published studies have been limited by being based on clinical diagnosis alone, which has a significant false positive rate. In a prospective, longitudinal, clinicopathological study which aims to develop an antemortem diagnostic test for Alzheimer's disease, we have achieved 96% (250/260) consent and 97% (59/61) completion rates. We here describe some of the factors we believe are responsible for these high rates and which may be relevant to other studies requiring autopsy to verify clinical diagnoses.

Association of atrophy of the medial temporal lobe with reduced blood flow in the posterior parietotemporal cortex in patients with a clinical and pathological diagnosis of Alzheimer's disease

A combination of medial temporal lobe atrophy, shown by computed tomography, and reduced blood flow in the parietotemporal cortex, shown by single photon emission tomography, was found in 86% (44/51) of patients with a clinical diagnosis of senile dementia of the Alzheimer type (SDAT). The same combination of changes was found in four out of 10 patients with other clinical types of dementia and in two out of 18 with no evidence of cognitive deficit. Of the 12 patients who died, 10 fulfilled histopathological criteria for Alzheimer's disease, nine of them having a clinical diagnosis of SDAT, and one a clinical diagnosis of multi-infarct dementia. All 10 patients with histopathologically diagnosed Alzheimer's disease had shown a combination of hippocampal atrophy and reduced parietotemporal blood flow in life. In 10 patients (nine with SDAT) out of 12 in whom the hippocampal atrophy was more noticeable on one side of the brain than on the other the parietotemporal perfusion deficit was also asymmetrical, being greater on the side showing more hippocampal atrophy. These results suggest that the combination of atrophy of the hippocampal formation and reduced blood flow in the parietotemporal region is a feature of dementia of the Alzheimer type and that the functional change in the parietotemporal region might be related to the loss of the projection neurons in the parahippocampal gyrus that innervate this region of the neocortex.