Mating system induced lags in rates of range expansion for different simulated mating systems and dispersal strategies: a modelling study.

Mismatches between current and potential species distributions are commonplace due to lags in the response of populations to changing environmental conditions. The prevailing mating system may contribute to such lags where it leads to mating failure at the range edge, but how active dispersers might mitigate these lags using social information to inform dispersal strategies warrants greater exploration. We used an individual-based model to explore how different mating systems for species that actively search for habitat can impose a filter on the ability to colonise empty, fragmented landscapes, and explored how using social information during dispersal can mitigate the lags caused by more constrained mating systems. The mate-finding requirements implemented in two-sex models consistently led to slower range expansion compared to those that were not mate limited (i.e., female only models), even when mating was polygynous. A mate-search settlement strategy reduced the proportion of unmated females at the range edge but had little impact on rate of spread. In contrast, a negative density-dependent settlement strategy resulted in much faster spread, which could be explained by a greater number of long-distance dispersal events. Our findings suggest that even low rates of mating failure at the range edge can lead to considerable lags in range expansion, though dispersal strategies that favour colonising more distant, sparsely occupied habitat patches may effectively mitigate these lags.

Improving the forecast for biodiversity under climate change.

New biological models are incorporating the realistic processes underlying biological responses to climate change and other human-caused disturbances. However, these more realistic models require detailed information, which is lacking for most species on Earth. Current monitoring efforts mainly document changes in biodiversity, rather than collecting the mechanistic data needed to predict future changes. We describe and prioritize the biological information needed to inform more realistic projections of species' responses to climate change. We also highlight how trait-based approaches and adaptive modeling can leverage sparse data to make broader predictions. We outline a global effort to collect the data necessary to better understand, anticipate, and reduce the damaging effects of climate change on biodiversity.

A stochastic movement simulator improves estimates of landscape connectivity.

Conservation actions often focus on restoration or creation of natural areas designed to facilitate the movements of organisms among populations. To be efficient, these actions need to be based on reliable estimates or predictions of landscape connectivity. While circuit theory and least-cost paths (LCPs) are increasingly being used to estimate connectivity, these methods also have proven limitations. We compared their performance in predicting genetic connectivity with that of an alternative approach based on a simple, individual-based "stochastic movement simulator" (SMS). SMS predicts dispersal of organisms using the same landscape representation as LCPs and circuit theory-based estimates (i.e., a cost surface), while relaxing key LCP assumptions, namely individual omniscience of the landscape (by incorporating perceptual range) and the optimality of individual movements (by including stochasticity in simulated movements). The performance of the three estimators was assessed by the degree to which they correlated with genetic estimates of connectivity in two species with contrasting movement abilities (Cabanis's Greenbul, an Afrotropical forest bird species, and natterjack toad, an amphibian restricted to European sandy and heathland areas). For both species, the correlation between dispersal model and genetic data was substantially higher when SMS was used. Importantly, the results also demonstrate that the improvement gained by using SMS is robust both to variation in spatial resolution of the landscape and to uncertainty in the perceptual range model parameter. Integration of this individual-based approach with other developing methods in the field of connectivity research, such as graph theory, can yield rapid progress towards more robust connectivity indices and more effective recommendations for land management.

The effect of host movement on viral transmission dynamics in a vector-borne disease system.

Many vector-borne pathogens whose primary vectors are generalists, such as Ixodid ticks, can infect a wide range of host species and are often zoonotic. Understanding their transmission dynamics is important for the development of disease management programmes. Models exist to describe the transmission dynamics of such diseases, but are necessarily simplistic and generally limited by knowledge of vector population dynamics. They are typically deterministic SIR-type models, which predict disease dynamics in a single, non-spatial, closed patch. Here we explore the limitations of such a model of louping-ill virus dynamics by challenging it with novel field data. The model was only partially successful in predicting Ixodes ricinus density and louping-ill virus prevalence at 6 Scottish sites. We extend the existing multi-host model by forming a two-patch model, incorporating the impact of roaming hosts. This demonstrates that host movement may account for some of the discrepancies between the original model and empirical data. We conclude that insights into the dynamics of multi-host vector-borne pathogens can be gained by using a simple two-patch model. Potential improvements to the model, incorporating aspects of spatial and temporal heterogeneity, are outlined.

Is breeding of farmland wading birds depressed by a combination of predator abundance and grazing?

Agri-environment schemes have been implemented across Europe to counter biodiversity loss in agricultural landscapes and halt the continual decline of farmland birds, including waders. Such schemes provide financial compensation for changes in agricultural practice, including livestock grazing regimes. Scheme uptake has been variable, partly because farmers believe that other factors, notably predation, are key to wader population declines. On the basis of wader breeding surveys across Shetland, UK, we show that predator density and livestock grazing, through reducing sward height, interact to influence territoriality and thereby are likely to affect wader breeding success. Our results appear to reflect views of both farmers and government agencies, which indicates that future agri-environment schemes would benefit from genuine stakeholder participation to maximize scheme uptake, implementation and beneficial effects on biodiversity. Our findings also imply that agri-environment schemes will reap the greatest benefits for waders through reducing stocking rate where avian predators are abundant.

Interventions for minimal change disease in adults with nephrotic syndrome.

BACKGROUND: Steroids have been used widely since the early 1970s for the treatment of adult-onset minimal change disease. The response rates to immunosuppressive agents in adult minimal change disease, especially steroids, are more variable than in children. The optimal agent, dose, and duration of treatment for the first episode of nephrotic syndrome, or for disease relapse(s) has not been determined. OBJECTIVES: To determine the benefits and harms of interventions for the nephrotic syndrome in adults caused by minimal change disease. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, reference articles and abstracts from conference proceedings, without language restriction. Search date: January 2007. SELECTION CRITERIA: Randomised controlled trials (RCTs) and quasi-RCTs of any intervention for minimal change disease in adults over 18 years with the nephrotic syndrome were included. Studies comparing different routes, frequencies, and duration of immunosuppressive agents were selected. Studies comparing non-immunosuppressive agents were also assessed. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study quality and extracted data. Statistical analyses were performed using the random effects model and results were expressed as a relative risk (RR) for dichotomous outcomes, or mean difference (WMD) for continuous data with 95% confidence intervals (CI). MAIN RESULTS: Three RCTs (68 participants) were identified. All treatment comparisons contained only one study. No significant difference was found between prednisone compared with placebo for complete (RR 1.44, CI 0.95 to 2.19) and partial remission (RR 1.00, CI 0.07 to 14.45) of the nephrotic syndrome due to minimal change disease. There was no difference between intravenous methylprednisolone plus oral prednisone compared with oral prednisone alone for complete remission (RR 0.74, CI 0.50 to 1.08). Prednisone, compared with short-course intravenous methylprednisolone, increased the number of subjects who achieved complete remission (RR 4.95, CI 1.15 to 21.26). The lack of statistical evidence of efficacy associated with prednisone therapy was based on data derived from a single study that compared 'alternate-day prednisone' to no immunosuppression' with only a small number of participants in each group. No RCTs were identified comparing regimens in adults with a steroid-dependent or relapsing disease course or comparing treatments comprising alkylating agents, cyclosporine, tacrolimus, levamisole, or mycophenolate mofetil. AUTHORS' CONCLUSIONS: Further comparative studies are required to examine the efficacy of immunosuppressive agents for achievement of sustained remission of nephrotic syndrome caused by minimal change disease. Studies are also needed to evaluate treatments for adults with steroid-dependent or relapsing disease.

Interventions for preventing bone disease in kidney transplant recipients.

BACKGROUND: Patients with chronic kidney disease have significant abnormalities of bone remodeling and mineral homeostasis and are at increased risk of fracture. The fracture risk for a kidney transplant recipient is four times that of the general population and higher than for a patient on dialysis. Randomised controlled trials (RCTs) report the use of bisphosphonates, vitamin D sterols, calcitonin, and hormone replacement therapy to treat bone disease following transplantation. OBJECTIVES: To evaluate the use of interventions for treating bone disease following kidney transplantation. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL in The Cochrane Library), Cochrane Renal Group's specialised register, MEDLINE, EMBASE, reference lists, and conference proceedings abstracts without language restriction. Date of last search: May 2006 SELECTION CRITERIA: RCTs and quasi-RCTs comparing different treatments for kidney transplant recipients of any age were selected. We excluded all other transplant recipients, including kidney-pancreas transplant recipients. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) with 95% confidence intervals (CI) for dichotomous variables and mean difference (MD) for continuous outcomes. MAIN RESULTS: Twenty-four trials (1,299 patients) were included. No individual intervention (bisphosphonates, vitamin D sterol or calcitonin) was associated with a reduction in fracture risk compared with placebo. Combining results for all active interventions against placebo demonstrated any treatment of bone disease was associated with a reduction in the RR of fracture (RR 0.51, 95% CI 0.27 to 0.99). Bisphosphonates (any route), vitamin D sterol, and calcitonin all had a beneficial effect on the bone mineral density at the lumbar spine. Bisphosphonates and vitamin D sterol also had a beneficial effect on the bone mineral density at the femoral neck. Bisphosphonates had greater efficacy for preventing bone mineral density loss when compared head-to-head with vitamin D sterols. Few or no data were available for combined hormone replacement, testosterone, selective oestrogen receptor modulators, fluoride or anabolic steroids. Other outcomes including all-cause mortality and drug-related toxicity were reported infrequently. AUTHORS' CONCLUSIONS: Treatment with a bisphosphonate, vitamin D sterol or calcitonin after kidney transplantation may protect against immunosuppression-induced reductions in bone mineral density and prevent fracture. Adequately powered trials are required to determine whether bisphosphonates are better than vitamin D sterols for fracture prevention in this population. The optimal route, timing, and duration of administration of these interventions remains unknown.

Calcimimetics for secondary hyperparathyroidism in chronic kidney disease patients.

BACKGROUND: Calcimimetic agents have recently been evaluated in the treatment of secondary hyperparathyroidism (SHPT) as add-on therapy to calcitriol and vitamin D analogues and dietary phosphate binders. OBJECTIVES: To evaluate the benefits and harms of calcimimetics for the prevention of secondary hyperparathyroid bone disease (including osteitis fibrosa cystica and adynamic bone disease) in dialysis patients with chronic kidney disease (CKD). SEARCH STRATEGY: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and conference proceedings were searched for randomised controlled trials (RCTs) evaluating any calcimimetic against placebo or another agent in pre-dialysis or dialysis patients with CKD. SELECTION CRITERIA: We included all RCTs of any calcimimetic agent, cinacalcet HCl (AMG-073, Sensipar), NPS R-467 or NPS R-568 administered to patients with CKD for the treatment of SHPT. DATA COLLECTION AND ANALYSIS: Data were extracted on all relevant patient-centred and surrogate outcomes. Analysis was by a random effects model and results expressed as relative risk (RR) or weighted mean difference (MD) with 95% confidence intervals. MAIN RESULTS: Eight studies (1429 patients) were identified, which compared a calcimimetic agent plus standard therapy to placebo plus standard therapy. The end of treatment values of parathyroid hormone (pg/mL) (MD -290.79, 95% CI -360.23 to -221.34), serum calcium (mg/dL) (MD -0.85, 95% CI -1.14 to -0.56), serum phosphorus (mg/dL) (MD -0.29, 95% CI -0.50 to -0.08) and the calcium by phosphorus product (mg(2)/dL(2))(MD -7.90, 95% CI -10.25 to -5.54) were significantly lower with calcimimetics compared to placebo. No significant effects on patient-based endpoints were demonstrated except for the risk of hypotension which was significantly reduced with calcimimetics compared to placebo (RR 0.53, 95%CI 0.36 to 0.79). AUTHORS' CONCLUSIONS: Calcimimetic treatment of SHPT leads to significant improvements in biochemical parameters that observational studies have shown to be associated with increased mortality, cardiovascular risk and osteitis fibrosa, but patient-based benefits have not yet been demonstrated in trials. For patients with SHPT, the benefits of calcimimetics over standard therapy remain uncertain until further RCTs become available.

Vegetation composition of roadside verges in Scotland: the effects of nitrogen deposition, disturbance and management.

Vehicular emissions of NO(x) and NH(3) result in elevated concentrations of nitrogen at roadside verges. To determine the extent that vehicular nitrogen emissions, disturbance and management affect the vegetation composition of road verges, a survey of 92 verges in Scotland was carried out with sites stratified by background nitrogen deposition and road type. NO(x) and NH(3) concentrations were monitored at 15 key sites for a year, and showed a decreasing gradient with increasing distance from the road. Ellenberg fertility indices of the vegetation communities also showed a general decrease with increasing distance from the road, but there was no straightforward correlation with NO(x) and NH(3) air concentrations between sites. Cover of bare ground, ruderal species and salt-tolerant species were highest at the verge edge. The proximity of the verge to traffic is important both in terms of NO(x) and NH(3) gradients, but also for deposited salt, grit and physical disturbance.

Spatial processes can determine the relationship between prey encounter rate and prey density.

Theoretical models frequently assume that the rate at which a searching predator encounters prey increases linearly with prey density. In a recent experiment using great tits searching for winter moth caterpillars, the time to find the first prey item did not decline as quickly with density as the standard theory assumes. Using a spatial simulation model, we show that prey aggregation and/or spatially correlated searching behaviour by the predator can generate a range of relationships, including results that are qualitatively similar to those found in the great tit experiment. We suggest that further experiments are required to determine whether the explanation proposed here is correct, and that theoretical work is needed to determine how this behaviour is likely to influence the ecological and evolutionary dynamics of predator-prey communities.

Concentrations of ammonia and nitrogen dioxide at roadside verges, and their contribution to nitrogen deposition.

Bimonthly integrated measurements of NO2 and NH3 have been made over one year at distances up to 10 m away from the edges of roads across Scotland, using a stratified sampling scheme in terms of road traffic density and background N deposition. The rate of decrease in gas concentrations away from the edge of the roads was rapid, with concentrations falling by 90% within the first 10 m for NH3 and the first 15 m for NO2. The longer transport distance for NO2 reflects the production of secondary NO2 from reaction of emitted NO and O3. Concentrations above the background, estimated at the edge of the traffic lane, were linearly proportional to traffic density for NH3 (microg NH3 m(-3) = 1 x 10(-4) x numbers of cars per day), reflecting emissions from three-way catalysts. For NO2, where emissions depend strongly on vehicle type and fuel, traffic density was calculated in terms of 'car equivalents'; NO2 concentrations at the edge of the traffic lane were proportional to the number of car equivalents (microg NO2 m(-3) = 1 x 10(-4) x numbers of car equivalents per day). Although absolute concentrations (microg m(-3)) of NH3 were five times smaller than for NO2, the greater deposition velocity for NH3 to vegetation means that approximately equivalent amounts of dry N deposition to road side vegetation from vehicle emissions comes from NH3 and NO2. Depending on traffic density, the additional N deposition attributable to vehicle exhaust gases is between 1 and 15 kg N ha(-1) y(-1) at the edge of the vehicle lane, falling to 0.2-10 kg N ha(-1) y(-1) at 10 m from the edge of the road.

Clinical features and revised diagnostic criteria in Joubert syndrome.

The clinical presentation of children with Joubert syndrome can include nonspecific features such as hypotonia, ataxia, and developmental delay. Careful examination of the face shows a characteristic appearance, and a neuro-ophthalmologic examination shows the presence of oculomotor apraxia. In the neonatal period, most children have hyperpnea intermixed with central apnea. Neuroimaging of the head in the axial plane demonstrates the "molar tooth sign"--deep posterior interpeduncular fossa, thick and elongated superior cerebellar peduncles, and hypoplastic or aplastic superior cerebellar vermis. The central nervous system malformation spectrum observed in radiologic and neuropathologic studies accounts for many clinical features of Joubert syndrome. The developmental delay and cognitive impairment cannot be fully explained by the hindbrain malformation and probably result from dysfunction of the cerebral hemispheres. Although related conditions with vermian hypoplasia or aplasia (including Arima; Senior-Loken; and cerebellar vermian hypoplasia, oligophrenia, congenital ataxia, coloboma, and hepatic fibrosis syndromes) can mimic Joubert syndrome, detailed imaging data are lacking in such cases. We propose a revision in diagnostic criteria for Joubert syndrome.

Behavioral self-regulation in adolescents with type I diabetes: negative affectivity and blood glucose symptom perception.

The hypothesis that negative affectivity (NA) is associated with accuracy of blood glucose (BG) symptom perceptions and diabetes control was assessed. After completing measures of BG symptom beliefs and NA-related constructs (i.e., attentional focus and trait anxiety), 35 adolescents with insulin-dependent diabetes monitored their physical symptoms and their actual BG levels 3 times daily for 2 weeks. Each subject's actual BG symptoms were determined by correlating symptom ratings with BG levels and were then compared with symptom beliefs. Those who were more internally focused were more able to discern which symptoms actually covaried with BG fluctuations; those with higher trait anxiety tended to misattribute non-diabetes-related symptoms to BG levels. Finally, interactions suggested that those who both attend to internal physical sensations and experience-heightened anxiety display poorer metabolic control.