Little evidence of inbreeding depression for birth mass, survival and growth in Antarctic fur seal pups.

Inbreeding depression, the loss of offspring fitness due to consanguineous mating, is generally detrimental for individual performance and population viability. We investigated inbreeding effects in a declining population of Antarctic fur seals (Arctocephalus gazella) at Bird Island, South Georgia. Here, localised warming has reduced the availability of the seal's staple diet, Antarctic krill, leading to a temporal increase in the strength of selection against inbred offspring, which are increasingly failing to recruit into the adult breeding population. However, it remains unclear whether selection operates before or after nutritional independence at weaning. We therefore used microsatellite data from 885 pups and their mothers, and SNP array data from 98 mother-offspring pairs, to quantify the effects of individual and maternal inbreeding on three important neonatal fitness traits: birth mass, survival and growth. We did not find any clear or consistent effects of offspring or maternal inbreeding on any of these traits. This suggests that selection filters inbred individuals out of the population as juveniles during the time window between weaning and recruitment. Our study brings into focus a poorly understood life-history stage and emphasises the importance of understanding the ecology and threats facing juvenile pinnipeds.

Time-Dependent Mechanical Properties in Polyetherimide 3D-Printed Parts Are Dictated by Isotropic Performance Being Accurately Predicted by the Generalized Time Hardening Model.

The Fused-Deposition Modelling (FDM) technique has transformed the manufacturing discipline by simplifying operational processes and costs associated with conventional technologies, with polymeric materials being indispensable for the development of this technology. A lack of quantification of viscoelastic/plastic behavior has been noted when addressing FDM parts with Polyetherimide (PEI), which is currently being investigated as a potential material to produce functional end-products for the aerospace and health industry. Primary and secondary creep along with stress relaxation tests have been conducted on FDM PEI specimens by applying stresses from 10 to 40 MPa for 100 to 1000 min. Specimens were 3D printed by varying the part build orientation, namely XY, YZ, and XZ. Creep results were fitted to the Generalized Time Hardening equation (GTH), and then this model was used to predict stress relaxation behavior. FDM PEI parts presented an isotropic creep and stress relaxation performance. The GTH model was proven to have a significant capacity to fit viscoelastic/plastic performances for each single build orientation (r > 0.907, p < 0.001), as well as a tight prediction of the stress relaxation behavior (r > 0.998, p < 0.001). Averaged-orientation coefficients for GTH were also closely correlated with experimental creep data (r > 0.958, p < 0.001) and relaxation results data (r > 0.999, p < 0.001). FDM PEI parts showed an isotropic time-dependent behavior, which contrasts with previous publications arguing the significant effect of part build orientation on the mechanical properties of FDM parts. These findings are strengthened by the high correlation obtained between the experimental data and the averaged-coefficient GTH model, which has been proven to be a reliable tool to predict time-dependent performance in FDM parts.

A global cline in a colour polymorphism suggests a limited contribution of gene flow towards the recovery of a heavily exploited marine mammal.

Evaluating how populations are connected by migration is important for understanding species resilience because gene flow can facilitate recovery from demographic declines. We therefore investigated the extent to which migration may have contributed to the global recovery of the Antarctic fur seal (Arctocephalus gazella), a circumpolar distributed marine mammal that was brought to the brink of extinction by the sealing industry in the eighteenth and nineteenth centuries. It is widely believed that animals emigrating from South Georgia, where a relict population escaped sealing, contributed to the re-establishment of formerly occupied breeding colonies across the geographical range of the species. To investigate this, we interrogated a genetic polymorphism (S291F) in the melanocortin 1 receptor gene, which is responsible for a cream-coloured phenotype that is relatively abundant at South Georgia and which appears to have recently spread to localities as far afield as Marion Island in the sub-Antarctic Indian Ocean. By sequencing a short region of this gene in 1492 pups from eight breeding colonies, we showed that S291F frequency rapidly declines with increasing geographical distance from South Georgia, consistent with locally restricted gene flow from South Georgia mainly to the South Shetland Islands and Bouvetøya. The S291F allele was not detected farther afield, suggesting that although emigrants from South Georgia may have been locally important, they are unlikely to have played a major role in the recovery of geographically more distant populations.

Binarity and Accretion in AGB Stars: HST/STIS Observations of UV Flickering in Y Gem.

Binarity is believed to dramatically affect the history and geometry of mass loss in AGB and post-AGB stars, but observational evidence of binarity is sorely lacking. As part of a project to search for hot binary companions to cool AGB stars using the GALEX archive, we discovered a late-M star, Y Gem, to be a source of strong and variable UV and X-ray emission. Here we report UV spectroscopic observations of Y Gem obtained with the Hubble Space Telescope that show strong flickering in the UV continuum on time-scales of ≲ 20 s, characteristic of an active accretion disk. Several UV lines with P-Cygni-type profiles from species such as Si IV and C IV are also observed, with emission and absorption features that are red- and blue-shifted by velocities of ~500 km s-1 from the systemic velocity. Our model for these (and previous) observations is that material from the primary star is gravitationally captured by a companion, producing a hot accretion disk. The latter powers a fast outflow that produces blue-shifted features due to absorption of UV continuum emited by the disk, whereas the red-shifted emission features arise in heated infalling material from the primary. The outflow velocities support a previous inference by Sahai et al. (2015) that Y Gem's companion is a low-mass main-sequence star. Blackbody fitting of the UV continuum implies an accretion luminosity of about 13 L⊙, and thus a mass-accretion rate > 5 × 10-7M⊙ yr-1; we infer that Roche lobe overflow is the most likely binary accretion mode for Y Gem.

A draft fur seal genome provides insights into factors affecting SNP validation and how to mitigate them.

Custom genotyping arrays provide a flexible and accurate means of genotyping single nucleotide polymorphisms (SNPs) in a large number of individuals of essentially any organism. However, validation rates, defined as the proportion of putative SNPs that are verified to be polymorphic in a population, are often very low. A number of potential causes of assay failure have been identified, but none have been explored systematically. In particular, as SNPs are often developed from transcriptomes, parameters relating to the genomic context are rarely taken into account. Here, we assembled a draft Antarctic fur seal (Arctocephalus gazella) genome (assembly size: 2.41 Gb; scaffold/contig N50 : 3.1 Mb/27.5 kb). We then used this resource to map the probe sequences of 144 putative SNPs genotyped in 480 individuals. The number of probe-to-genome mappings and alignment length together explained almost a third of the variation in validation success, indicating that sequence uniqueness and proximity to intron-exon boundaries play an important role. The same pattern was found after mapping the probe sequences to the Walrus and Weddell seal genomes, suggesting that the genomes of species divergent by as much as 23 million years can hold information relevant to SNP validation outcomes. Additionally, reanalysis of genotyping data from seven previous studies found the same two variables to be significantly associated with SNP validation success across a variety of taxa. Finally, our study reveals considerable scope for validation rates to be improved, either by simply filtering for SNPs whose flanking sequences align uniquely and completely to a reference genome, or through predictive modelling.

On the scattered light by dilute aqueous dispersions of nanogel particles.

This work deals with the scattered light by nanoparticles formed by a temperature sensitive polymer networks, namely nanogel particles. The scattered light is measured as a function of the scattering angle at temperatures below and above the volume phase transition temperature (VPTT) of nanogel particles. Our experimental results indicate that nanogel particles have a core-shell structure, formed by a uniform highly cross-linked core surrounded by a fuzzy shell where the polymer density decays to zero gradually for swollen configurations and sharply for shrunken states. The theoretical fitting of the experimental curves shows that the scattered light at low angle obeys a decreasing power law with the scattering vector, q(-α). The value of exponent α provides information about the radial dependence of the polymer density at the external shell of the particles for swollen nanogels, and about the degree of roughness of the surface for the case of shrunken nanogels. On the one hand, at low temperatures (below the VPPT), the nanogel particle is in the swollen state and the light scattering data show that its shell structure follows a fractal behaviour, with a polymer density that decays as r(α-3), where r is the distance to the particle centre. On the other hand, above the VPPT the results indicate that nanogel collapses into a core of uniform polymer density and a rough shell, with a fractal surface dimension of 2.5.

Rates of assay success and genotyping error when single nucleotide polymorphism genotyping in non-model organisms: a case study in the Antarctic fur seal.

Although single nucleotide polymorphisms (SNPs) are increasingly being recognized as powerful molecular markers, their application to non-model organisms can bring significant challenges. Among these are imperfect conversion rates of assays designed from in silico resources and the enhanced potential for genotyping error relative to pre-validated, highly optimized human SNPs. To explore these issues, we used Illumina's GoldenGate assay to genotype 480 Antarctic fur seal (Arctocephalus gazella) individuals at 144 putative SNPs derived from a 454 transcriptome assembly. One hundred and thirty-five polymorphic SNPs (93.8%) were automatically validated by the program GenomeStudio, and the initial genotyping error rate, estimated from nine replicate samples, was 0.004 per reaction. However, an almost tenfold further reduction in the error rate was achieved by excluding 31 loci (21.5%) that exhibited unclear clustering patterns, manually editing clusters to allow rescoring of ambiguous or incorrect genotypes, and excluding 18 samples (3.8%) with unreliable genotypes. After stringent quality filtering, we also found a counter-intuitive negative relationship between in silico minor allele frequency and the conversion rate, suggesting that some of our assays may have been designed from paralogous loci. Nevertheless, we obtained over 45 000 individual SNP genotypes with a final error rate of 0.0005, indicating that the GoldenGate assay is eminently capable of generating large, high-quality data sets for non-model organisms. This has positive implications for future studies of the evolutionary, behavioural and conservation genetics of natural populations.

Bayesian inference of a historical bottleneck in a heavily exploited marine mammal.

Emerging Bayesian analytical approaches offer increasingly sophisticated means of reconstructing historical population dynamics from genetic data, but have been little applied to scenarios involving demographic bottlenecks. Consequently, we analysed a large mitochondrial and microsatellite dataset from the Antarctic fur seal Arctocephalus gazella, a species subjected to one of the most extreme examples of uncontrolled exploitation in history when it was reduced to the brink of extinction by the sealing industry during the late eighteenth and nineteenth centuries. Classical bottleneck tests, which exploit the fact that rare alleles are rapidly lost during demographic reduction, yielded ambiguous results. In contrast, a strong signal of recent demographic decline was detected using both Bayesian skyline plots and Approximate Bayesian Computation, the latter also allowing derivation of posterior parameter estimates that were remarkably consistent with historical observations. This was achieved using only contemporary samples, further emphasizing the potential of Bayesian approaches to address important problems in conservation and evolutionary biology.

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Use of hydrophobically modified inulin for the preparation of polymethyl methacrylate/polybutyl acrylate latex particles using a semicontinuous reactor.

The seeded semicontinuous emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BuA) stabilized with a graft polymeric surfactant based on inulin, INUTEC SP1, as well as its mixture with sodium lauryl sulfate (SLS) is described. The mixture of SLS and Brij58 (alcohol ethoxylated) and the mixture of SLS and Pluronic P85 (block copolymer PEO-PPO-PEO) are also used as surfactant systems. The addition of methacrylic acid (MAA) or acrylic acid (AA) as comonomers is also studied. Previous results proved this inulin-derivative surfactant, INUTEC SP1, to be very effective on synthesizing latexes using a very low surfactant concentration. The kinetic features of the emulsion polymerization (instantaneous conversion and total conversion) were gravimetrically determined along the reactions. Latex dispersions were characterized by photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) to obtain the average particle size, the particle size distributions (PSDs) as well as the polydispersity index (PdI). The stability was determined by turbidimetry measurements and expressed in terms of critical coagulation concentration. The results showed that the use of the graft polymeric surfactant allowed obtaining highly stable nanoparticles, at low surfactant concentrations and high solid contents (up to 37 wt %). This is an improvement with respect to previous works, in which a mixture of the graft polymeric surfactant with another surfactant was required to obtain stable nanoparticles with low polydispersity, at high solid content. In the present work, low polydispersity was achieved using INUTEC as the only emulsifier, which was related to the absence of secondary nucleations. When a mixture of INUTEC SP1 and SLS is used, a wider PSD is obtained due to secondary nucleations. Replacing INUTEC SP1 by other nonionic surfactants such as Brij58 or Pluronic P85 leads to an increase of average particle size and wider PSD.

[Initial series of radical prostatectomy in a general hospital: review and comparative of national and international series]. / Serie inicial de prostatectomía radical laparoscópica en un hospital general: revisión y comparativa de series nacionales e internacionales.

INTRODUCTION AND OBJECTIVES: The radical prostatectomy is a technique that has shown competitive oncological and functional results, that is why it has become to be a routine procedure in many leading centers. Nevertheless, the difficulty of learning and its initial cost, could question its implantation as a routine technique in centers that are not a point of reference. We have carried out a descriptive study of our initial series analyzing the surgical technique, post surgical immediate results, and oncological and functional short-term outcomes, comparing them with other series in national and international centers. METHODS: From February, 2006 to August, 2007 we performed 69 laparoscopical procedures in our center, of which 34 were radical prostatectomies. The average age of the series were 63 years (50-72), with a prostate average weight by transrectal ultrasound of 35 gr. (17-72), and a median PSA of 6ng/ml (4-35). The clinical stages were: T1c 59%, T2a 12%, T2b 17%, T2c 12%; with Gleason combined of: 2+2 in 3%, 3+3 in 35%, 3+4 in 15%, 4+3 in 44%, 4+5 in 3%. RESULTS: Out of the 34 cases initiated by laparoscopy, 30 were concluded laparoscopically, with a surgical average time of 261 minutes (150-380). The pathological stages were: pT2a 3%, pT2b 18%, pT2c 41%, pT3a 32%, pT3b 6%. With Gleason of: 3+3 in 26%, 3+4 in 14%, 4+3 in 47%, 4+4 in 9%, 4+5 in 3%. We obtained 29% of positive margins (50% pT3a, 20% pT3b, 20% pT2b, 10% pT2c). Four cases were converted to open surgery, one due to subcutaneous emphysema, one to enlarged surgical time, one bleeding, and one rectal injury. The continence (0-1 pads) at the first month was 62%, reaching 84% at 6 months. The erection, remained in 50% of the patients at the first month, in the four cases of intrafascial dissection. CONCLUSIONS: Laparoscopic radical prostatectomy is a technique of difficult learning, and initially requires higher surgical time than open surgery. Nevertheless, we prove that it is a reliable technique with competitive oncological and functional results, early recovery and little bleeding even in the initial series. Therefore, it should be considered an option for the treatment of prostate cancer also in not leading centers.

Serie inicial de prostatectomía radical laparoscópica en un hospital general: revisión y comparativa de series nacionales e internacionales / Initial series of radical prostatectomy in a general hospital: review and comparative of national and international series

Serie inicial de prostatectomía radical laparoscópica en un hospital general: revisión y comparativa de series nacionales e internacionales. Introducción y objetivos: La prostatectomía radical laparoscópica es una técnica que ha demostrado unos resultados oncológicos y funcionales competitivos, por lo que se ha convertido en un procedimiento rutinario en muchos centros punteros. No obstante, la dificultad de aprendizaje y su coste inicial, pueden cuestionar su implantación como técnica rutinaria, en centros que no sean de referencia. Realizamos un estudio descriptivo de nuestra serie inicial analizando la técnica quirúrgica, resultados posquirúrgicos inmediatos, y oncológicos y funcionales a corto plazo, comparándolos con otras series en centros nacionales e internacionales. Métodos: De febrero 2006 a agosto 2007 realizamos 69 procedimientos laparoscópicos en nuestro centro, de los cuales 34 fueron prostatectomías radicales. La edad media de la serie fue de 63 años (50-72), con un peso prostático medio por ecografía transrectal de 35 gr.(17-72), y una mediana de PSA de 6 ng/ml (4-35). Los estadios clínicos fueron: T1c 59%, T2a 12%, T2b 17%, T2c 12%; con Gleason: 2+2en 3%, 3+3 en 35%, 3+4 en 15%, 4+3 en 44%, 4+5 en 3%.Resultados: De los 34 casos iniciados por laparoscopia, se terminaron 30, con un tiempo quirúrgico medio de 261 minutos (150-380).Se convirtieron 4 casos a cirugía abierta, 1 por enfisema subcutáneo, 1 por prolongación del tiempo quirúrgico, 1 por sangrado, 1 por lesión rectal. Los estadios patológicos fueron: pT2a 3%, pT2b 18%, pT2c 41%, pT3a 32%, pT3b 6%. Con Gleason de: 3+3 en 26%, 3+4 en 14%, 4+3en 47%, 4+4 en 9%, 4+5 en 3%. Obtuvimos un 29% de márgenes positivos (50% pT3a, 20% pT3b, 20% pT2b, 10% pT2c). La continencia (0-1 compresas) al mes, fue del 62%, llegando al 84% a los 6 meses. La erección al mes, se conservó en un 50% de los pacientes, en los cuatro casos de disección intrafascial. Conclusiones: la prostatectomía radical laparoscópica es una técnica de difícil aprendizaje, y exige un tiempo quirúrgico inicial superiora la cirugía abierta. No obstante, comprobamos que se trata de una técnica segura, con unos resultados oncológicos y funcionales competitivos, una recuperación temprana y un escaso sangrado, incluso en series iniciales. Por ello, también debería considerarse una opción para el tratamiento del cáncer de próstata en centros de segundo nivel (AU)

Introduction and objectives: The radical prostatectomy is a technique that has shown competitive oncological and functional results, that is why it has become to be a routine procedure in many leading centers. Nevertheless, the difficulty of learning and its initial cost, could question its implantation as a routine technique in centers that are not a point of reference. We have carried out a descriptive study of our initial series analyzing the surgical technique, post surgical immediate results, and oncological and functional short-term outcomes, comparing them with other series in national and international centers. Methods: From February, 2006 to August, 2007 we performed 69 laparoscopical procedures in our center, of which 34 were radical prostatectomies. The average age of the series were 63 years (50-72), with a prostate average weight by transrectal ultrasound of 35 gr.(17-72), and a median PSA of 6ng/ml (4-35). The clinical stages were: T1c 59%, T2a 12%, T2b 17%, T2c 12%; with Gleason combined of:2+2 in 3%, 3+3 in 35%, 3+4 in 15%, 4+3 in 44%, 4+5 in 3%.Results: Out of the 34 cases initiated by laparoscopy, 30 were concluded laparoscopically, with a surgical average time of 261 minutes (150-380). The pathological stages were: pT2a 3%, pT2b 18%, pT2c 41%, pT3a 32 %, pT3b 6%. With Gleason of: 3+3 in 26%, 3+4 in 14%, 4+3 in47%, 4+4 in 9%, 4+5 in 3%. We obtained 29 % of positive margins (50% pT3a, 20% pT3b, 20% pT2b, 10% pT2c). Four cases were converted to open surgery, one due to subcutaneous emphysema, one to enlarged surgical time, one bleeding, and one rectal injury. The continence (0-1 pads) at the first month was 62%, reaching 84% at 6 months. The erection, remained in 50% of the patients at the first month, in the four cases of intrafascial dissection. Conclusions: Laparoscopic radical prostatectomy is a technique of difficult learning, and initially requires higher surgical time than open surgery. Nevertheless, we prove that it is a reliable technique with competitive oncological and functional results, early recovery and little bleeding even in the initial series. Therefore, it should be considered an option for the treatment of prostate cancer also in not leading centers (AU)

Environmental forcing and Southern Ocean marine predator populations: effects of climate change and variability.

The Southern Ocean is a major component within the global ocean and climate system and potentially the location where the most rapid climate change is most likely to happen, particularly in the high-latitude polar regions. In these regions, even small temperature changes can potentially lead to major environmental perturbations. Climate change is likely to be regional and may be expressed in various ways, including alterations to climate and weather patterns across a variety of time-scales that include changes to the long interdecadal background signals such as the development of the El Niño-Southern Oscillation (ENSO). Oscillating climate signals such as ENSO potentially provide a unique opportunity to explore how biological communities respond to change. This approach is based on the premise that biological responses to shorter-term sub-decadal climate variability signals are potentially the best predictor of biological responses over longer time-scales. Around the Southern Ocean, marine predator populations show periodicity in breeding performance and productivity, with relationships with the environment driven by physical forcing from the ENSO region in the Pacific. Wherever examined, these relationships are congruent with mid-trophic-level processes that are also correlated with environmental variability. The short-term changes to ecosystem structure and function observed during ENSO events herald potential long-term changes that may ensue following regional climate change. For example, in the South Atlantic, failure of Antarctic krill recruitment will inevitably foreshadow recruitment failures in a range of higher trophic-level marine predators. Where predator species are not able to accommodate by switching to other prey species, population-level changes will follow. The Southern Ocean, though oceanographically interconnected, is not a single ecosystem and different areas are dominated by different food webs. Where species occupy different positions in different regional food webs, there is the potential to make predictions about future change scenarios.

Spatial and temporal operation of the Scotia Sea ecosystem: a review of large-scale links in a krill centred food web.

The Scotia Sea ecosystem is a major component of the circumpolar Southern Ocean system, where productivity and predator demand for prey are high. The eastward-flowing Antarctic Circumpolar Current (ACC) and waters from the Weddell-Scotia Confluence dominate the physics of the Scotia Sea, leading to a strong advective flow, intense eddy activity and mixing. There is also strong seasonality, manifest by the changing irradiance and sea ice cover, which leads to shorter summers in the south. Summer phytoplankton blooms, which at times can cover an area of more than 0.5 million km2, probably result from the mixing of micronutrients into surface waters through the flow of the ACC over the Scotia Arc. This production is consumed by a range of species including Antarctic krill, which are the major prey item of large seabird and marine mammal populations. The flow of the ACC is steered north by the Scotia Arc, pushing polar water to lower latitudes, carrying with it krill during spring and summer, which subsidize food webs around South Georgia and the northern Scotia Arc. There is also marked interannual variability in winter sea ice distribution and sea surface temperatures that is linked to southern hemisphere-scale climate processes such as the El Niño-Southern Oscillation. This variation affects regional primary and secondary production and influences biogeochemical cycles. It also affects krill population dynamics and dispersal, which in turn impacts higher trophic level predator foraging, breeding performance and population dynamics. The ecosystem has also been highly perturbed as a result of harvesting over the last two centuries and significant ecological changes have also occurred in response to rapid regional warming during the second half of the twentieth century. This combination of historical perturbation and rapid regional change highlights that the Scotia Sea ecosystem is likely to show significant change over the next two to three decades, which may result in major ecological shifts.

Female fur seals show active choice for males that are heterozygous and unrelated.

Much debate surrounds the exact rules that influence mating behaviour, and in particular the selective forces that explain the evolution of female preferences. A key example is the lek paradox, in which female choice is expected rapidly to become ineffective owing to loss of additive genetic variability for the preferred traits. Here we exploit a remarkable system in which female fur seals exert choice by moving across a crowded breeding colony to visit largely static males. We show that females move further to maximize the balance between male high multilocus heterozygosity and low relatedness. Such a system shows that female choice can be important even in a strongly polygynous species, and at the same time may help to resolve the lek paradox because heterozygosity has low heritability and inbreeding avoidance means there is no single 'best' male for all females.

No relationship between microsatellite variation and neonatal fitness in Antarctic fur seals, Arctocephalus gazella.

Published studies of wild vertebrate populations have almost universally reported positive associations between genetic variation measured at microsatellite loci and fitness, creating the impression of ubiquity both in terms of the species and the traits involved. However, there is concern that this picture may be misleading because negative results frequently go unpublished. Here, we analyse the relationship between genotypic variation at nine highly variable microsatellite loci and neonatal fitness in 1070 Antarctic fur seal pups born at Bird Island, South Georgia. Despite our relatively large sample size, we find no significant association between three different measures of heterozygosity and two fitness traits, birth weight and survival. Furthermore, increasing genetic resolution by calculating parental relatedness also yields no association between genetic variation and fitness. Our findings are consistent with necropsy data showing that most pups die from starvation or trauma, conditions that are unlikely to be influenced strongly by genetic factors, particularly if the benefits of high heterozygosity are linked to immune-related genes.

Amino, chloromethyl and acetal-functionalized latex particles for immunoassays: a comparative study.

Latex particles with different functionalized surface groups (amino, acetal and chloromethyl) for the covalent linking of protein molecules were synthesized and characterized. Immunopurified anti-ferritin antibodies were then covalently coupled with a mean efficiency rate (protein covalently bound to latex particles with respect to the total amount of protein added) of 60%. The reagents developed were applied to the measurement of serum ferritin concentration in a turbidimetric procedure, showing a good measuring range and a lowest detection limit of 3.5 ng/ml in the case of the amino-modified particles. These immunological reagents were compared with a commercial nephelometric method, showing a good linear correlation in all cases but no transferability in the acetal and chloromethyl latex with additional carboxyl groups, probably due to interference with other serum components. The differences among latex found in this study indicate that it would be necessary to optimize the assay conditions for each type of particle, in order to achieve a maximum immunoreactivity.

Association of systemic lupus erythematosus and hypermobility.

OBJECTIVE: To investigate joint laxity in patients with systemic lupus erythematosus (SLE). SETTING: University Hospital. METHODS: 81 patients with SLE (1999 American College of Rheumatology criteria; 72 (89%) women and nine (11%) men, mean age 42.9 (SD 16.1) years), who regularly attended a specialist SLE clinic were examined. The control group comprised 280 patients attending a general practitioner (193 (69%) women and 87 (31%) men, mean age 44.7 (SD 11.2) years). Joint laxity was measured according to the criteria of Beighton et al (total score 4 or more). A regression analysis was performed. RESULTS: Thirty nine (48%) patients with SLE and 42 (15%) of the control group were hypermobile. A logistic regression model was developed. The odds ratio of the association between laxity and SLE after adjustment for age and sex was 2.31 in the group younger than 49 years, and 17.99 in the group aged 49 years or older. Neither the clinical and analytical profile nor the use of corticosteroids was related to joint laxity. CONCLUSION: Patients with SLE showed more hypermobility than controls. Hypermobility was more profound in older patients with SLE (> or =49 years). Joint laxity was not associated with any clinical or analytical pattern. Treatment with corticosteroids was not related to joint laxity.