When Space and Time Matter in Environmental Injustice: A Bayesian Analysis of the Association between Socio-economic Disadvantage and Air Pollution in Greater Mexico City.

Environmental injustice refers to the unequal burden of pollutants on groups with lower socioeconomic status. An increasing number of studies have identified associations between high levels of pollution and socioeconomic disadvantage. However, few studies have controlled adequately for spatio-temporal variations in pollution. This study uses a Bayesian approach to explore the association between socioeconomic disadvantage and pollution in Mexico City Metropolitan Area. We quantify the association of socioeconomic disadvantage with PM10 and ozone and evaluate the impact of accounting for spatio-temporal structure of the pollution data. We find a significant positive association between socio-economic disadvantage and pollution for levels of PM10, but not ozone. The inclusion of the spatio-temporal element in the modeling results in improved weaker estimates of this association but this does not alter results substantially. These findings confirm the robustness of previous studies that found signs of environmental injustice where spatio-temporal variations have not been explicitly considered, confirming that targeted policies to reduce pollution in socio-economically disadvantaged areas are required.

Engineering alginate hydrogel films with poly(3-hydroxybutyrate-co-3-valerate) and graphene nanoplatelets: Enhancement of antiviral activity, cell adhesion and electroactive properties.

A new biodegradable semi-interpenetrated polymer network (semi-IPN) of two US Food and Drug Administration approved materials, poly(3-hydroxybutyrate-co-3-valerate) (PHBV) and calcium alginate (CA) was engineered to provide an alternative strategy to enhance the poor adhesion properties of CA. The synthesis procedure allows the additional incorporation of 10 % w/w of graphene nanoplatelets (GNPs), which have no cytotoxic effect on human keratinocytes. This quantity of multilayer graphene provides superior antiviral activity to the novel semi-IPN against a surrogate virus of SARS-CoV-2. Adding GNPs hardly affects the water absorption or electrical conductivity of the pure components of CA and PHBV. However, the semi-IPN's electrical conductivity increases dramatically after adding GNP due to molecular rearrangements of the intertwined polymer chains that continuously distribute the GNP nanosheets, This new hydrophilic composite biomaterial film shows great promise for skin biomedical applications, especially those that require antiviral and/or biodegradable electroconductive materials.

Alginate: Enhancement Strategies for Advanced Applications.

Alginate is an excellent biodegradable and renewable material that is already used for a broad range of industrial applications, including advanced fields, such as biomedicine and bioengineering, due to its excellent biodegradable and biocompatible properties. This biopolymer can be produced from brown algae or a microorganism culture. This review presents the principles, chemical structures, gelation properties, chemical interactions, production, sterilization, purification, types, and alginate-based hydrogels developed so far. We present all of the advanced strategies used to remarkably enhance this biopolymer's physicochemical and biological characteristics in various forms, such as injectable gels, fibers, films, hydrogels, and scaffolds. Thus, we present here all of the material engineering enhancement approaches achieved so far in this biopolymer in terms of mechanical reinforcement, thermal and electrical performance, wettability, water sorption and diffusion, antimicrobial activity, in vivo and in vitro biological behavior, including toxicity, cell adhesion, proliferation, and differentiation, immunological response, biodegradation, porosity, and its use as scaffolds for tissue engineering applications. These improvements to overcome the drawbacks of the alginate biopolymer could exponentially increase the significant number of alginate applications that go from the paper industry to the bioprinting of organs.

Spondyloarthritis: Characterization of a cohort. Pablo Tobón Uribe Hospital. Medellín, Colombia / Espondiloartritis: caracterización de la cohorte del Hospital Pablo Tobón Uribe, Medellín, Colombia

ABSTRACT Introduction: Spondyloarthritis is a group of chronic inflammatory diseases. Several factors of the disease remain unknown, including clinical and radiological behavior, the demographic characteristics and burden of disease in Colombian patients. Objective: To characterize the demographic aspects, the clinical and paraclinical behaviour, and the therapeutic requirements of a cohort of patients with spondyloarthritis followed-up in the Hospital Pablo Tobón Uribe from January 1, 2005 to December 31, 2017. Methodology: Cohort study. The population was characteriszed using descriptive statistics, qualitative variables using simple and relative frequencies, and quantitative variables using means and standard deviation or medians with their interquartile ranges. Results: The cohort consisted of 181 patients, 100 men (54.9%) and 81 women (44.5%). Just under one half (45.1%) had ankylosing spondylitis, 18.1% undifferentiated spondyloarthritis, 17.1% psoriatic arthropathy, 14.8% reactive arthritis, and 4.4% inflammatory bowel disease. More than two-thirds (69.8%) of the patients had peripheral manifestations, and 67% had axial. A positive HLAB27 was observed in 55.6% of patients. The MRI showed acute and chronic changes in the sacroiliac in 69% and 37%, respectively, with radiological sacroiliitis being observed in 59.5% of cases. The large majority (91.1%) of the patients were treated with PII of original article: S0121-8123(21)00018-9 NSAIDs, 60.1% with sulfasalazine, 43.4% with COX2 inhibitors, and 33.7% with methotrexate. TNFa inhibitors were required by 56.6% of the subjects 3 years after the onset of symptoms. The most commonly used biological drugs were Adalimumab (31.1%), etanercept (21.7%), infliximab (13.1%), golimumab 6.1%, and certolizumab 0.5%. Conclusions: Ourpopulation was characterized by a high activity and functional compromise demonstrated by the high scores of BASDAI and BASFI, and because 56.6% of the patients required anti-TNFa agents.

RESUMEN Introducción: Las espondiloartritis son un grupo de enfermedades inflamatorias crónicas. Se desconoce su comportamiento en nuestro medio, al igual que el comportamiento clínico y radiológico, las características demográficas y la carga de enfermedad en los pacientes colombianos. Objetivos: Caracterizar los aspectos demográficos, el comportamiento clínico y paraclínico y los requerimientos terapéuticos de la cohorte de pacientes con espondiloartritis seguidos en el Hospital Pablo Tobón Uribe desde el 1.° de enero del 2005 hasta el día 31 de diciembre del 2017. Metodología: Estudio de cohorte. La población se caracterizó mediante estadística descrip tiva, las variables cualitativas mediante frecuencias simples y relativas, en tanto que para las cuantitativas se emplearon medias y desviación estándar o medianas con sus rangos intercuartílicos. Resultados: La cohorte está constituida por 181 pacientes, 100 hombres (54,9%) y 81 mujeres (44,5%). El 45,1% tenía espondilitis anquilosante, el 18,1% espondiloartritis indiferenciada, el 17,1% artropatía psoriásica, el 14,8% artritis reactiva y el 4,4% enfermedad inflamatoria intestinal. El 69,8% de los pacientes tenía manifestaciones periféricas y el 67% axiales. El 55,6% de los pacientes tuvo HLAB27 positivo. La RMN mostró cambios agudos y crónicos en las sacroilíacas en el 69% y 37%, respectivamente; en el 59,5% de los casos se observó sacroileítis radiológica. el 91,1% de los pacientes se trató con AINE, el 60,1% con sulfasa lazina, el 43,4% con inhibidores COX2 y el 33,7% con metotrexato. El 56,6% de los sujetos requirió inhibidores-TNFa 3 arios después del inicio de los síntomas. Los biológicos más uti lizados fueron adalimumab (31,1%), etanercept (21,7%), infliximab (13,1%), golumimab (6,1%) y certolizumab (0,5%). Conclusiones: Nuestra población se caracterizó por una alta actividad y gran compromiso funcional, lo que se refleja en altos puntajes de Basdai y Basfi y en que el 56,6% de los pacientes requirió agentes anti-TNFa.

Factores asociados con el uso de inhibidores del factor de necrosis tumoral alfa en una población de pacientes colombianos con espondiloartritis / Factors associated with the use of tumor necrosis factor alpha inhibitors in a population of Colombian patients with spondyloarthritis

RESUMEN Introducción: El uso de TNFi es cada vez más frecuente en los pacientes con espondiloartritis. Identificar tempranamente aquellos que los requerirán o poder predecir su uso puede ayudar a hacer un tratamiento más efectivo y oportuno racionalizando su uso. Objetivo: Determinar los factores qué mejor explican la indicación de TNFi en la población en estudio. Material y métodos: La asociación entre el uso de medicamentos anti-TNFα y las variables categóricas demográficas, clínicas, de laboratorio, radiológicas y de tratamiento se exploró por prueba exacta de Fisher. La asociación con las variables cuantitativas fue evaluada con t de Student o U de Mann Withney, de acuerdo con su distribución. Aquellas variables con p < 0,25 fueron ingresadas a modelos univariante de regresión logística explicativa para construir los OR crudos; aquellas con p < 0,25 se incluyeron en el modelo multivariante para construir OR ajustados. Resultados y discusión: La población está constituida por 181 pacientes. Modelo univariante: la artritis reactiva, uretritis y compromiso periférico fueron factores protectores para el uso de TNFi. Espondiloartritis axial, lumbalgia inflamatoria, dolor glúteo alternante, rigidez matinal sacroilitis demostrada por cualquier método, tratamiento con inhibidores COX-2, tiempo de evolución de tres arios o más y los puntajes de BASDAI y BASFI se asociaron con el uso de TNFi. Modelo multivariante: artritis reactiva (OR 0,1, IC 95% 0,012-0,86, p = 0,036), lumbalgia inflamatoria (OR 13,63, IC 95% 1,36-136, p = 0,026), sacroilitis (OR 7,71, IC 95% 1,04-57, p = 0,045, uso de coxib (OR 10,1, IC 95% 2,71-37,62, p = 0,001) y el puntaje máximo de BASDAI (4-6: OR 6,1, IC 95% 1,3-28,7, p = 0,022, mayor de 6: OR 15,8, IC 95% 2,2-113, p = 0,006) se asociaron independientemente con el uso de TNFi. El uso de coxib se asoció con la indicación de usar TNFi tanto en los pacientes con espondiloartritis axial (OR 4,2, IC 95% 1,74-10,11, p = 0,001) como periférica (OR 4, IC 95% 1,85-8,62, p < 0,001). Conclusiones: El inicio de la enfermedad en la forma de artritis reactiva se comportó como un factor protector para la necesidad posterior de usar TNFi, mientras que presentar lumbalgia inflamatoria, sacroilitis demostrada por cualquier método, el tratamiento con coxib y el puntaje máximo de BASDAI mayor de 4 se asociaron con el uso de estos medicamentos.

ABSTRACT Introduction: The use of tumor necrosis factor (TNF) alpha inhibitors is increasing in patients with spondyloarthritis. Early identification of those that would require them, or the ability to predict their use, could lead to a more effective and timely treatment by rationalizing their use. Objective: To determine factors that better explain the indication of TNFi in the study population. Material and methods: The association between anti-TNFα use and categorical demographic, clinical, laboratory, radiological and treatment variables was explored using Pearson's Chi2 or Fisher's exact test. The association with the quantitative variables was evaluated using Student's t test or Mann Whitney U test, depending on their distribution. Those variables with P < 0.25 were entered into univariate models of explanatory logistic regression to cons truct crude ORs, and those with P < 0.25 were included in the multivariate model to construct adjusted ORs. Results and discussion: The study population includes 181 patients. In the univariate model: reactive arthritis, urethritis, and peripheral involvement were protective factors for the use of TNFi. Axial spondyloarthritis, inflammatory lumbalgia, alternating gluteal pain, morning stiffness, sacroiliitis demonstrated by any method, treatment with COX-2 inhibitors, evolu tion time of three years or more, and BASDAI and BASFI scores were associated with the use of TNFi. Multivariate model: reactive arthritis (P = 0.036), inflammatory back pain (P = 0.026), sacroiliitis (P = 0.045), use of coxibs (P = 0.001) and the maximum score of BASDAI (P = 0.022, P = 0.006) were independently associated with the use of TNFi. The use of coxibs was associa ted with the indication of using TNFi in both patients with axial spondyloarthritis (P = 0.001) and peripheral (P < 0.001). Conclusions: The onset of the disease in the form of reactive arthritis behaved as a protective factor for the subsequent need to use TNFi, while presenting with inflammatory back pain, sacroiliitis, demonstrated by any method, treatment with coxibs, and the maximum score of BASDAI greater than 4 associated with the use of these medications.

Modelling local patterns of child mortality risk: a Bayesian Spatio-temporal analysis.

BACKGROUND: Globally, child mortality rate has remained high over the years, but the figure can be reduced through proper implementation of spatially-targeted public health policies. Due to its alarming rate in comparison to North American standards, child mortality is particularly a health concern in Mexico. Despite this fact, there remains a dearth of studies that address its spatio-temporal identification in the country. The aims of this study are i) to model the evolution of child mortality risk at the municipality level in Greater Mexico City, (ii) to identify municipalities with high, medium, and low risk over time, and (iii) using municipality trends, to ascertain potential high-risk municipalities. METHODS: In order to control for the space-time patterns of data, the study performs a Bayesian spatio-temporal analysis. This methodology permits the modelling of the geographical variation of child mortality risk across municipalities, within the studied time span. RESULTS: The analysis shows that most of the high-risk municipalities were in the east, along with a few in the north and west areas of Greater Mexico City. In some of them, it is possible to distinguish an increasing trend in child mortality risk. The outcomes highlight municipalities currently presenting a medium risk but liable to become high risk, given their trend, after the studied period. Finally, the likelihood of child mortality risk illustrates an overall decreasing tendency throughout the 7-year studied period. CONCLUSIONS: The identification of high-risk municipalities and risk trends may provide a useful input for policymakers seeking to reduce the incidence of child mortality. The results provide evidence that supports the use of geographical targeting in policy interventions.

Association of insularity and body condition to cloacal bacteria prevalence in a small shorebird.

Do islands harbour less diverse disease communities than mainland? The island biogeography theory predicts more diverse communities on mainland than on islands due to more niches, more diverse habitats and availability of greater range of hosts. We compared bacteria prevalences of Campylobacter, Chlamydia and Salmonella in cloacal samples of a small shorebird, the Kentish plover (Charadrius alexandrinus) between two island populations of Macaronesia and two mainland locations in the Iberian Peninsula. Bacteria were found in all populations but, contrary to the expectations, prevalences did not differ between islands and mainland. Females had higher prevalences than males for Salmonella and when three bacteria genera were pooled together. Bacteria infection was unrelated to bird's body condition but females from mainland were heavier than males and birds from mainland were heavier than those from islands. Abiotic variables consistent throughout breeding sites, like high salinity that is known to inhibit bacteria growth, could explain the lack of differences in the bacteria prevalence between areas. We argue about the possible drivers and implications of sex differences in bacteria prevalence in Kentish plovers.

Does the use of nest materials in a ground-nesting bird result from a compromise between the risk of egg overheating and camouflage?

Many studies addressing the use of nest materials by animals have focused on only one factor to explain its function. However, the consideration of more than one factor could explain the apparently maladaptive choice of nest materials that make nests conspicuous to predators. We experimentally tested whether there is a trade-off in the use of nest materials between the risks of egg predation versus protection from overheating. We studied the ground-nesting Kentish plover, Charadrius alexandrinus, in southern Spain. We added materials differing in thermal properties and coloration to the nests, thus affecting rates of egg heating, nest temperature and camouflage. Before these manipulations, adults selected materials that were lighter than the microhabitat, probably to buffer the risk of egg overheating. However, the adults did not keep the lightest experimental materials, probably because they reduced camouflage, and this could make the nests even more easily detectable to predators. In all nests, adults removed most of the experimental materials independently of their properties, so that egg camouflage returned to the original situation within a week of the experimental treatments. Although the thermal environment may affect the choice of nest materials by plovers, ambient temperatures were not so high at our study site as to determine the acceptance of the lightest experimental materials.

Targeting the neuronal calcium sensor DREAM with small-molecules for Huntington's disease treatment.

DREAM, a neuronal calcium sensor protein, has multiple cellular roles including the regulation of Ca2+ and protein homeostasis. We recently showed that reduced DREAM expression or blockade of DREAM activity by repaglinide is neuroprotective in Huntington's disease (HD). Here we used structure-based drug design to guide the identification of IQM-PC330, which was more potent and had longer lasting effects than repaglinide to inhibit DREAM in cellular and in vivo HD models. We disclosed and validated an unexplored ligand binding site, showing Tyr118 and Tyr130 as critical residues for binding and modulation of DREAM activity. IQM-PC330 binding de-repressed c-fos gene expression, silenced the DREAM effect on KV4.3 channel gating and blocked the ATF6/DREAM interaction. Our results validate DREAM as a valuable target and propose more effective molecules for HD treatment.

Identification of IQM-266, a Novel DREAM Ligand That Modulates KV4 Currents.

Downstream Regulatory Element Antagonist Modulator (DREAM)/KChIP3/calsenilin is a neuronal calcium sensor (NCS) with multiple functions, including the regulation of A-type outward potassium currents (I A). This effect is mediated by the interaction between DREAM and KV4 potassium channels and it has been shown that small molecules that bind to DREAM modify channel function. A-type outward potassium current (I A) is responsible of the fast repolarization of neuron action potentials and frequency of firing. Using surface plasmon resonance (SPR) assays and electrophysiological recordings of KV4.3/DREAM channels, we have identified IQM-266 as a DREAM ligand. IQM-266 inhibited the KV4.3/DREAM current in a concentration-, voltage-, and time-dependent-manner. By decreasing the peak current and slowing the inactivation kinetics, IQM-266 led to an increase in the transmembrane charge ( Q K V 4.3 / DREAM ) at a certain range of concentrations. The slowing of the recovery process and the increase of the inactivation from the closed-state inactivation degree are consistent with a preferential binding of IQM-266 to a pre-activated closed state of KV4.3/DREAM channels. Finally, in rat dorsal root ganglion neurons, IQM-266 inhibited the peak amplitude and slowed the inactivation of I A. Overall, the results presented here identify IQM-266 as a new chemical tool that might allow a better understanding of DREAM physiological role as well as modulation of neuronal I A in pathological processes.

Inhibition of the Neuronal Calcium Sensor DREAM Modulates Presenilin-2 Endoproteolysis.

Deregulated intracellular Ca2+ and protein homeostasis underlie synaptic dysfunction and are common features in neurodegenerative diseases. DREAM, also known as calsenilin or KChIP-3, is a multifunctional Ca2+ binding protein of the neuronal calcium sensor superfamily with specific functions through protein-DNA and protein-protein interactions. Small-molecules able to bind DREAM, like the anti-diabetic drug repaglinide, disrupt some of the interactions with other proteins and modulate DREAM activity on Kv4 channels or on the processing of activating transcription factor 6 (ATF6). Here, we show the interaction of endogenous DREAM and presenilin-2 (PS2) in mouse brain and, using DREAM deficient mice or transgenic mice overexpressing a dominant active DREAM (daDREAM) mutant in the brain, we provide genetic evidence of the role of DREAM in the endoproteolysis of endogenous PS2. We show that repaglinide disrupts the interaction between DREAM and the C-terminal PS2 fragment (Ct-PS2) by coimmunoprecipitation assays. Exposure to sub-micromolar concentrations of repaglinide reduces the levels of Ct-PS2 fragment in N2a neuroblastoma cells. These results suggest that the interaction between DREAM and PS2 may represent a new target for modulation of PS2 processing, which could have therapeutic potential in Alzheimer's disease (AD) treatment.

Inhibition of DREAM-ATF6 interaction delays onset of cognition deficit in a mouse model of Huntington's disease.

The transcriptional repressor DREAM (downstream regulatory element antagonist modulator) is a multifunctional neuronal calcium sensor (NCS) that controls Ca2+ and protein homeostasis through gene regulation and protein-protein interactions. Downregulation of DREAM is part of an endogenous neuroprotective mechanism that improves ATF6 (activating transcription factor 6) processing, neuronal survival in the striatum, and motor coordination in R6/2 mice, a model of Huntington's disease (HD). Whether modulation of DREAM activity can also ameliorate cognition deficits in HD mice has not been studied. Moreover, it is not known whether DREAM downregulation in HD is unique, or also occurs for other NCS family members. Using the novel object recognition test, we show that chronic administration of the DREAM-binding molecule repaglinide, or induced DREAM haplodeficiency delays onset of cognitive impairment in R6/1 mice, another HD model. The mechanism involves a notable rise in the levels of transcriptionally active ATF6 protein in the hippocampus after repaglinide administration. In addition, we show that reduction in DREAM protein in the hippocampus of HD patients was not accompanied by downregulation of other NCS family members. Our results indicate that DREAM inhibition markedly improves ATF6 processing in the hippocampus and that it might contribute to a delay in memory decline in HD mice. The mechanism of neuroprotection through DREAM silencing in HD does not apply to other NCS family members.

Theoretically informed Monte Carlo simulation of liquid crystals by sampling of alignment-tensor fields.

A theoretically informed coarse-grained Monte Carlo method is proposed for studying liquid crystals. The free energy functional of the system is described in the framework of the Landau-de Gennes formalism. The alignment field and its gradients are approximated by finite differences, and the free energy is minimized through a stochastic sampling technique. The validity of the proposed method is established by comparing the results of the proposed approach to those of traditional free energy minimization techniques. Its usefulness is illustrated in the context of three systems, namely, a nematic liquid crystal confined in a slit channel, a nematic liquid crystal droplet, and a chiral liquid crystal in the bulk. It is found that for systems that exhibit multiple metastable morphologies, the proposed Monte Carlo method is generally able to identify lower free energy states that are often missed by traditional approaches. Importantly, the Monte Carlo method identifies such states from random initial configurations, thereby obviating the need for educated initial guesses that can be difficult to formulate.

Homeotropic nano-particle assembly on degenerate planar nematic interfaces: films and droplets.

A continuum theory is used to study the effects of homeotropic nano-particles on degenerate planar liquid crystal interfaces. Particle self-assembly mechanisms are obtained from careful examination of particle configurations on a planar film and on a spherical droplet. The free energy functional that describes the system is minimized according to Ginzburg-Landau and stochastic relaxations. The interplay between elastic and surface distortions and the desire to minimize defect volumes (boojums and half-Saturn rings) is shown to be responsible for the formation of intriguing ordered structures. As a general trend, the particles prefer to localize at defects to minimize the overall free energy. However, multiple metastable configurations corresponding to local minima can be easily observed due to the high energy barriers that separate distinct particle arrangements. We also show that by controlling anchoring strength and temperature one can direct liquid-crystal mediated nanoparticle self-assembly along well defined pathways.

Interannual variations in feeding frequencies and food quality of greater flamingo chicks (Phoenicopterus roseus): evidence from plasma chemistry and effects on body condition.

Greater flamingos in southern Spain foraged in areas distant from a breeding site, spending 4-6 days in foraging areas between successive visits to the colony to feed their chicks. During four years, we took blood samples from chicks to ascertain whether there were interannual variations in several blood parameters, indicative of food quality and feeding frequencies. When the chicks were captured, 20-31% of them had their crops empty, indicating that not all chicks were fed daily. Additional evidence of variations in feeding frequencies was obtained from a principal component analysis (PCA) on plasma chemistry values, which also indicated that there were annual variations in the quality of food received by chicks. The association of cholesterol and glucose with some PC axes indicated that some chicks were experiencing fasting periods. Of all plasma metabolites considered, cholesterol was the best one to predict body condition. Greater flamingo chicks experiencing longer fasting intervals, as suggested by higher plasma levels of cholesterol, were in lower body condition.

Intake rates and the functional response in shorebirds (Charadriiformes) eating macro-invertebrates.

As field determinations take much effort, it would be useful to be able to predict easily the coefficients describing the functional response of free-living predators, the function relating food intake rate to the abundance of food organisms in the environment. As a means easily to parameterise an individual-based model of shorebird Charadriiformes populations, we attempted this for shorebirds eating macro-invertebrates. Intake rate is measured as the ash-free dry mass (AFDM) per second of active foraging; i.e. excluding time spent on digestive pauses and other activities, such as preening. The present and previous studies show that the general shape of the functional response in shorebirds eating approximately the same size of prey across the full range of prey density is a decelerating rise to a plateau, thus approximating the Holling type II ('disc equation') formulation. But field studies confirmed that the asymptote was not set by handling time, as assumed by the disc equation, because only about half the foraging time was spent in successfully or unsuccessfully attacking and handling prey, the rest being devoted to searching.A review of 30 functional responses showed that intake rate in free-living shorebirds varied independently of prey density over a wide range, with the asymptote being reached at very low prey densities (<150/m-2). Accordingly, most of the many studies of shorebird intake rate have probably been conducted at or near the asymptote of the functional response, suggesting that equations that predict intake rate should also predict the asymptote.A multivariate analysis of 468 'spot' estimates of intake rates from 26 shorebirds identified ten variables, representing prey and shorebird characteristics, that accounted for 81% of the variance in logarithm-transformed intake rate. But four-variables accounted for almost as much (77.3%), these being bird size, prey size, whether the bird was an oystercatcher Haematopus ostralegus eating mussels Mytilus edulis, or breeding. The four variable equation under-predicted, on average, the observed 30 estimates of the asymptote by 11.6%, but this discrepancy was reduced to 0.2% when two suspect estimates from one early study in the 1960s were removed. The equation therefore predicted the observed asymptote very successfully in 93% of cases. We conclude that the asymptote can be reliably predicted from just four easily measured variables. Indeed, if the birds are not breeding and are not oystercatchers eating mussels, reliable predictions can be obtained using just two variables, bird and prey sizes. A multivariate analysis of 23 estimates of the half-asymptote constant suggested they were smaller when prey were small but greater when the birds were large, especially in oystercatchers. The resulting equation could be used to predict the half-asymptote constant, but its predictive power has yet to be tested. As well as predicting the asymptote of the functional response, the equations will enable research workers engaged in many areas of shorebird ecology and behaviour to estimate intake rate without the need for conventional time-consuming field studies, including species for which it has not yet proved possible to measure intake rate in the field.