Internal femoral component rotation adversely influences load transfer in total knee arthroplasty: a cadaveric navigated study using the Verasense device.

PURPOSE AND HYPOTHESIS: Correct femoral component rotation at knee arthroplasty influences patellar tracking and may determine function at extremes of movement. Additionally, such malrotation may deleteriously influence flexion/extension gap geometry and soft tissue balancing kinematics. Little is known about the effect of subtle rotational change upon load transfer across the tibiofemoral articulation. Our null hypothesis was that femoral component rotation would not influence load across this joint in predictable manner. METHODS: A cadaveric study was performed to examine load transfer using the orthosensor device, respecting laxity patterns in 6° of motion, to examine load across the medial and lateral compartments across a full arc of motion. Mixed-effect modelling allowed for quantification of the effect upon load with internal and external femoral component rotation in relation to a datum in a modern single-radius cruciate-retaining primary knee design. RESULTS: No significant change in maximal laxity was found between different femoral rotational states. Internal rotation of the femoral component resulted in significant increase in medial compartment load transfer for knee flexion including and beyond 60°. External rotation of the femoral component within the limits studied did not influence tibiofemoral load transfer. CONCLUSIONS: Internal rotation of the femoral component will adversely influence medial compartment load transfer and could lead to premature polyethylene wear on the medial side.

Does Maximal External Tibial Component Rotation Influence Tibiofemoral Load Distribution in the Primary Knee Arthroplasty Setting: A Comparison of Neutral vs Maximal Anatomical External Rotatory States.

BACKGROUND: Tibial component rotation at time of knee arthroplasty can influence conformity, load transmission across the polyethylene surface, and perhaps ultimately determined survivorship. Optimal tibial component rotation on the cut surface is reliant on standard per operative manual stressing. This subjective assessment aims to balance constraint and stability of the articulation through a full arc of movement. METHODS: Using a cadaveric model, computer navigation and under defined, previously validated loaded conditions mimicking the in vivo setting, the influence of maximal tibial component external rotation compared with the neutral state was examined for changes in laxity and tibiofemoral continuous load using 3D displacement measurement and an orthosensor continuous load sensor implanted within the polyethylene spacer in a simulated single radius total knee arthroplasty. RESULTS: No significant difference was found throughout arc of motion (0-115 degrees of flexion) for maximal varus and/or valgus or rotatory laxity between the 2 states. The neutral state achieved equivalence for mediolateral load distribution at each point of flexion. We have found that external rotation of the tibial component increased medial compartment load in comparison with the neutral position. Compared with the neutral state, external rotation consistently effected a marginal, but not significant reduction in lateral load under similar loading conditions. The effects were most pronounced in midflexion. CONCLUSION: On the basis of these findings, we would advocate for the midtibial tubercle point to determine tibial component rotation and caution against component external rotation.

Clustering, persistence and control of a pollinator brood disease: epidemiology of American foulbrood.

American foulbrood (AFB), caused by Paenibacillus larvae, is the most damaging bacterial brood disease of the honeybee (Apis mellifera), causing colony deaths on all continents where honeybees are managed. AFB has been a persistent problem in the UK for over 70 years, with a fluctuating number of cases discovered annually. Once diseased colonies are identified, they are destroyed to reduce pathogen spread. We investigated the pattern of AFB cases recorded over the period 1994 to 2012 using spatial-statistical approaches, with a view to identifying the nature of spread across England and Wales. Our results indicated that AFB exhibits significant spatial aggregation at distances from 10 to 30 km, with aggregations lasting between 1 and 5 years. Kernel smoothing indicated areas of elevated relative risk in different years, and these were further detailed by spatial-scan statistics. We identified disease clusters and successfully estimated their size, location and duration. The majority of clusters did not persist in all years, indicating that management measures may lead to localized extinction of the disease. Whilst less common, persistent clusters likely indicate potential endemic or exotic risk points. The application of robust epidemiological approaches to improve the control of AFB is discussed.

PAH contamination in shellfish: modelling to estimate exposure.

Polycyclic aromatic hydrocarbons (PAH) are known carcinogens and are abundant in the environment and foodstuffs. Currently the majority of PAH research focuses on benzo[a]pyrene (BaP), although a much greater range of PAH are known to have detrimental effects to human health. Monitoring a large number of PAH is expensive, time consuming and analytically demanding, yet there is currently no clear basis for determining which PAH should be monitored to give an indication of overall exposure. A thorough statistical examination of the relationships between different PAH in different foodstuffs has not previously been carried out. Using a test dataset of homogenised edible flesh from shellfish samples as a case study a modelling process using principal components analysis regression is proposed to determine which PAH subset (from a total of 27 monitored PAH) should be assessed as indicators for general PAH exposure. Multivariate ordination and clustering show that PAH concentrations of compounds of similar chemical structure can be highly correlated in the samples, e.g. the five ringed isomers PAHs benzo[b]fluoranthene, benzo[j]fluoranthene and benzo[k]fluoranthene. The model selection process determined which subsets of PAH can be used to predict the presence and abundance of other PAHs in shellfish samples. Models were more accurate in predicating PAHs concentrations of PAH where concentrations were measured above the limit of detection (LoD). PAH with values below the LoD were harder to predict accurately. The current analysis highlights that laboratories should focus on the following PAHs BaP, benzo[a]anthracene, benzo[g,h,i]perylene, phenanthrene, benzo[g,h,i]fluoranthene, chrysene, benzo[k]fluoranthene, benzo[b]fluoranthene and fluoranthene when analysing shellfish samples. Focussing monitoring on this group of PAH may give a better indication of overall PAH content of samples that the summed PAH indicator methods currently adopted.

Campylobacter Contamination at Retail of Halal Chicken Produced in the United Kingdom.

ABSTRACT: Campylobacter is the leading cause of human bacterial diarrheal disease worldwide, and poultry meat products account for the majority of human cases. Based on recent surveys, the Food Standards Agency has estimated the Campylobacter prevalence in fresh retail chicken in the United Kingdom to be 41.2%. However, such surveys have not distinguished between broiler chickens produced for different consumer demographic groups, such as the Halal market. Campylobacter colonization of broilers is difficult to prevent, especially during routine partial depopulation of flocks. Broilers produced for the Halal market may undergo multiple depopulation events, which may increase the risk of Campylobacter colonization and subsequent contamination of chicken meat. This study was conducted to determine the prevalence and levels of Campylobacter contamination in chicken meat produced for the Halal market in the United Kingdom. Campylobacter was identified and enumerated from the neck skin and outer packaging of 405 Halal chickens. Culture isolates were assigned to species via PCR assays, and disk diffusion assays were used to determine antimicrobial susceptibility. Logistic regression analysis was used to assess risk factors for Campylobacter contamination, the level of Campylobacter contamination among positive carcasses, and antimicrobial resistance. Campylobacter spp. were confirmed in 65.4% of neck skin samples and 17.1% of packaging samples. Neck skin samples had the highest level of contamination; 13.8% of samples had >1,000 CFU/g. Large birds had a significantly higher number of samples with >1,000 CFU/g (P < 0.001). and as chicken carcass weight increased, birds were more likely to be Campylobacter positive (P < 0.05). A high prevalence of resistance was seen to ciprofloxacin (42.0% of samples), and 38.5% of samples contained at least one multidrug-resistant Campylobacter isolate. This study revealed that Halal chicken has a higher Campylobacter prevalence than does non-Halal chicken. Interventions should be introduced to reduce this public health risk.

Hierarchical drivers of reef-fish metacommunity structure.

Coral reefs are highly complex ecological systems, where multiple processes interact across scales in space and time to create assemblages of exceptionally high biodiversity. Despite the increasing frequency of hierarchically structured sampling programs used in coral-reef science, little progress has been made in quantifying the relative importance of processes operating across multiple scales. The vast majority of reef studies are conducted, or at least analyzed, at a single spatial scale, ignoring the implicitly hierarchical structure of the overall system in favor of small-scale experiments or large-scale observations. Here we demonstrate how alpha (mean local number of species), beta diversity (degree of species dissimilarity among local sites), and gamma diversity (overall species richness) vary with spatial scale, and using a hierarchical, information-theoretic approach, we evaluate the relative importance of site-, reef-, and atoll-level processes driving the fish metacommunity structure among 10 atolls in French Polynesia. Process-based models, representing well-established hypotheses about drivers of reef-fish community structure, were assembled into a candidate set of 12 hierarchical linear models. Variation in fish abundance, biomass, and species richness were unevenly distributed among transect, reef, and atoll levels, establishing the relative contribution of variation at these spatial scales to the structure of the metacommunity. Reef-fish biomass, species richness, and the abundance of most functional-groups corresponded primarily with transect-level habitat diversity and atoll-lagoon size, whereas detritivore and grazer abundances were largely correlated with potential covariates of larval dispersal. Our findings show that (1) within-transect and among-atoll factors primarily drive the relationship between alpha and gamma diversity in this reef-fish metacommunity; (2) habitat is the primary correlate with reef-fish metacommunity structure at multiple spatial scales; and (3) inter-atoll connectedness was poorly correlated with the nonrandom clustering of reef-fish species. These results demonstrate the importance of modeling hierarchical data and processes in understanding reef-fish metacommunity structure.

Actinobacterial community dynamics in long term managed grasslands.

Palace Leas, a long-term experiment at Cockle Park Farm, Northumberland, UK was established in winter 1896-1897 since when the 13 plots have received regular and virtually unchanged mineral fertiliser and farm yard manure inputs. Fertilisers have had a profound impact on soil pH with the organically fertilised plots showing a significantly higher pH than those receiving mineral fertiliser where ammonium sulphate has led to soil acidification. Here, we investigate the impact of organic and mineral fertilisers on the actinobacterial community structure of these soils using terminal restriction fragment length polymorphism (T-RFLP) and 16S rRNA gene analysis. To differentiate fertiliser effects from seasonal variation, soils were sampled three times over one growing season between May and September 2004 and January 2005. Community profiles obtained using T-RFLP were analysed using multivariate statistics to investigate the relationship between community structure, seasonality and fertiliser management. Soil pH was shown to be the most significant edaphic factor influencing actinobacterial communities. Canonical correspondence analysis, used to investigate the relationship between the 16S rRNA gene community profiles and the environmental parameters, showed that actinobacterial communities also responded to soil water content with major changes evident over the summer months between May and September. Quantitative PCR of the actinobacterial and fungal 16S and 18S rRNA genes, respectively suggested that fungal rRNA gene copy numbers were negatively correlated (P = 0.0131) with increasing actinobacterial signals. A similar relationship (P = 0.000365) was also evident when fatty acid methyl esters indicative of actinobacterial biomass (10-methyloctadecanoic acid) were compared with the amounts of fungal octadecadienoic acid (18:2omega9,12). These results show clearly that soil pH is a major driver of change in actinobacterial communities and that genera such as Arthrobacter and Micrococcus are particularly abundant in soils receiving organic inputs whilst others such as Streptomyces, Acidimicrobium and Actinospica are more prevalent in acid soils. The importance of these findings in terms of fungal abundance and potential disease suppression are discussed.

Degeneration of dopaminergic circuitry influences depressive symptoms in Lewy body disorders.

AIMS: Depression is commonly observed even in prodromal stages of Lewy body disorders (LBD), and is associated with cognitive impairment and a faster rate of cognitive decline. Given the role of dopamine in the development of movement disorders, but also in motivation and reward, we investigated neurodegenerative pathology in dopaminergic circuitry in Parkinson's disease (PD), PD with dementia (PDD) and dementia with Lewy bodies (DLB) patients in relation to depressive symptoms. METHODS: α-synuclein, hyperphosphorylated tau and amyloid-beta pathology was assessed in 17 DLB, 14 PDD and 8 PD cases within striatal and midbrain subregions, with neuronal cell density assessed in substantia nigra and ventral tegmental area. Additionally, we used a structural equation modeling (SEM) approach to investigate the extent to which brain connectivity might influence the deposition of pathological proteins within dopaminergic pathways. RESULTS: A significantly higher α-synuclein burden was observed in the substantia nigra (P = 0.006), ventral tegmental area (P = 0.011) and nucleus accumbens (P = 0.031) in LBD patients with depression. Significant negative correlations were observed between cell density in substantia nigra with Lewy body (LB) Braak stage (P = 0.013), whereas cell density in ventral tegmental area showed negative correlations with LB Braak stage (P = 0.026) and neurofibrillary tangle Braak stage (P = 0.007). CONCLUSIONS: Dopaminergic α-synuclein pathology appears to drive depression. Selective targeting of dopaminergic pathways may therefore provide symptomatic relief for depressive symptoms in LBD patients.

Soil bacterial diversity is positively associated with air temperature in the maritime Antarctic.

Terrestrial ecosystems in the maritime Antarctic experienced rapid warming during the latter half of the 20th century. While warming ceased at the turn of the millennium, significant increases in air temperature are expected later this century, with predicted positive effects on soil fungal diversity, plant growth and ecosystem productivity. Here, by sequencing 16S ribosomal RNA genes in 40 soils sampled from along a 1,650 km climatic gradient through the maritime Antarctic, we determine whether rising air temperatures might similarly influence the diversity of soil bacteria. Of 22 environmental factors, mean annual surface air temperature was the strongest and most consistent predictor of soil bacterial diversity. Significant, but weaker, associations between bacterial diversity and soil moisture content, C:N ratio, and Ca, Mg, PO43- and dissolved organic C concentrations were also detected. These findings indicate that further rises in air temperature in the maritime Antarctic may enhance terrestrial ecosystem productivity through positive effects on soil bacterial diversity.

Oropharyngeal Microbiota in Frail Older Patients Unaffected by Time in Hospital.

Respiratory tract infections are the commonest nosocomial infections, and occur predominantly in frailer, older patients with multiple comorbidities. The oropharyngeal microbiota is the major reservoir of infection. This study explored the relative contributions of time in hospital and patient demographics to the community structure of the oropharyngeal microbiota in older patients with lower limb fracture. We collected 167 throat swabs from 53 patients (mean age 83) over 14 days after hospitalization, and analyzed these using 16S rRNA gene sequencing. We calculated frailty/comorbidity indices, undertook dental examinations and collected data on respiratory tract infections. We analyzed microbial community composition using correspondence (CA) and canonical correspondence analysis. Ten patients were treated for respiratory tract infection. Microbial community structure was related to frailty, number of teeth and comorbidity on admission, with comorbidity exerting the largest effect. Time in hospital neither significantly changed alpha (t = -0.910, p = 0.365) nor beta diversity (CA1 t = 0.022, p = 0.982; CA2 t = -0.513, p = 0.609) of microbial communities in patient samples. Incidence of respiratory pathogens were not associated with time in hospital (t = -0.207, p = 0.837), nor with alpha diversity of the oral microbiota (t = -1.599, p = 0.113). Patient characteristics at admission, rather than time in hospital, influenced the community structure of the oral microbiota.

Ancient landscapes and the relationship with microbial nitrification.

Ammonia oxidizing archaea (AOA) and bacteria (AOB) drive nitrification and their population dynamics impact directly on the global nitrogen cycle. AOA predominate in the majority of soils but an increasing number of studies have found that nitrification is largely attributed to AOB. The reasons for this remain poorly understood. Here, amoA gene abundance was used to study the distribution of AOA and AOB in agricultural soils on different parent materials and in contrasting geologic landscapes across Australia (n = 135 sites). AOA and AOB abundances separated according to the geologic age of the parent rock with AOB higher in the more weathered, semi-arid soils of Western Australia. AOA dominated the younger, higher pH soils of Eastern Australia, independent of any effect of land management and fertilization. This differentiation reflects the age of the underlying parent material and has implications for our understanding of global patterns of nitrification and soil microbial diversity. Western Australian soils are derived from weathered archaean laterite and are acidic and copper deficient. Copper is a co-factor in the oxidation of ammonia by AOA but not AOB. Thus, copper deficiency could explain the unexpectedly low populations of AOA in Western Australian soils.

Factors influencing length of stay and mortality after first and second hip fractures: an event modeling analysis.

OBJECTIVE: The aim of this study was to investigate factors influencing length of stay and mortality in first and second hip fractures. DESIGN: This was a retrospective study with data analysis. SETTING: The study was conducted at a level 1 trauma center. PATIENTS: Six hundred and seventy-two patients treated for hip fractures (OTA 31-A, 31-B, 32-A1.1) over 30 months were split into 2 groups. 1FG: Six hundred and ten patients (90.8%) suffered a fracture for the first time. 2FG: Sixty-two patients (9.2%) had previously sustained contralateral fractures. INTERVENTION: Dynamic hip screws or cephalomedullary nails (31-A fractures); cephalomedullary nails (32-A1.1); dynamic hip screws or cannulated screws (undisplaced 31-B fractures); and hemiarthroplasty (displaced 31-B fractures) were used. MAIN OUTCOME MEASURES: Postoperative lengths of stay on trauma ward (LOS-T) on the rehabilitation unit (LOS-R) and in hospital (LOS-H) were calculated. Dates of death were recorded. Event analysis and structural equation modeling were used to assess the impact of second fractures, fracture types, age, gender, and ASA grades on these. RESULTS: : The 2 groups were comparable in gender distribution, ASA grades, fracture types, LOS, and mortality at 120 days. 2FG patients were older than 1FG (mean 83.3 vs 80.2 years) with a higher proportion being discharged to institutional care (35.5% vs 18.5%). Event modeling analysis showed that LOS-T was dependent on ASA grade, whereas mortality was dependent on ASA grade, age, and gender. Second fractures were not related to the risks of increased LOS-T, LOS-R, and mortality. CONCLUSIONS: Second fractures per se do not increase the risk of longer postoperative stay or higher mortality. Any observed effect on these outcomes in second fractures represents the influence of increasing age. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Sex differences in effects of low level domoic acid exposure.

Consumption of seafood containing the phytoplankton-derived toxin domoic acid (DOM) causes neurotoxicity in humans and in animals. It has been reported that DOM-induced symptoms may be more severe in men than women, but to date the effect of sex on DOM-induced effects in adults is not known. We investigated sex differences in DOM-induced effects in adult rats. Since low level exposure is of greatest relevance to human health (due to DOM regulatory limit), we examined the effects of low level exposure. Adult male and female Sprague Dawley rats were administered a single intraperitoneal injection of DOM (0, 1.0, 1.8 mg/kg). Behaviour was monitored for 3h and immunohistochemistry in the dorsal hippocampus and olfactory bulb was also examined. DOM increased locomotor and grooming activity, compared to vehicle group. DOM exposure also significantly increased stereotypic behaviours and decreased phosphorylated cAMP response element-binding protein immunoreactivity (pCREB-IR). There was no effect of sex on the magnitude of the behavioural responses, but the onset of DOM-induced locomotor activity and ear scratches was quicker in females than in males. Mixed effect modelling revealed the predicted peak in locomotor activity in response to DOM was also quicker in females than in males. Severe toxicity was evident in 2/7 male rats and 0/8 female rats dosed with 1.8 mg/kg DOM. These data suggest that males exposed to low level DOM may be more susceptible to severe neurotoxicity, whereas females are affected more quickly. Understanding sex differences in DOM-induced neurotoxicity may contribute to future protective strategies and treatments.

Visualization, modelling and prediction in soil microbiology.

The introduction of new approaches for characterizing microbial communities and imaging soil environments has benefited soil microbiology by providing new ways of detecting and locating microorganisms. Consequently, soil microbiology is poised to progress from simply cataloguing microbial complexity to becoming a systems science. A systems approach will enable the structures of microbial communities to be characterized and will inform how microbial communities affect soil function. Systems approaches require accurate analyses of the spatio-temporal properties of the different microenvironments present in soil. In this Review we advocate the need for the convergence of the experimental and theoretical approaches that are used to characterize and model the development of microbial communities in soils.