Ammonium acetate as a novel buffer for highly selective robust urinary HPLC-ICP-MS arsenic speciation methodology.

Ammonium acetate is employed in order to develop a novel HPLC-ICP-MS arsenic speciation methodology applicable to six arsenic species, i.e, AC, AB, AsIII, AsV, DMA and MMA. The most predominant species in the toxicological field are covered in a 30-min chromatogram with reproducible and repeatability peak area ratio. Moreover, typical problems from traditional methods are sorted out by using a robust, high-selective and 75ArCl+ interference-free methodology. Chromatographic and detector optimization ensures low LOQs for each species with acceptable precision and accuracy values obtained using four urinary arsenic speciation PTS enabling to be useful for sub ng mL-1 arsenic exposure assessments.

The effect of arm-crank exercise training on power output, spirometric and cardiac function and level of autonomy in persons with tetraplegia.

Studies on the effects of exercise training in persons with cervical spinal cord injury (CSCI) are scarce. The aim of this study was to determine the effect of an 8-week stationary arm-crank exercise (ACE) training programme on the level of autonomy, exercise performance, pulmonary functional parameters and resting heart rate variability (HRV) in persons with CSCI. Quadriplegia Index of Function (QIF), arm-crank peak power output (Ppeak), spirometric variables, and HRV indices were measured before and after the training programme in a group of 11 persons with CSCI. ACE training increased Ppeak in both groups (p < 0.05), whereas maximum voluntary ventilation (MVV) and low frequency HRV (LF) improved only in the lower CSCI group (p < 0.05). Moreover, QIF and Ppeak were significantly correlated before (r = 0.88; p < 0.01) and after (r = 0.86; p < 0.01) the training period. However, no significant changes were found in the level of autonomy (QIF) as a result of the intervention. Therefore, stationary ACE training appears to be a feasible and effective method for aerobic exercise in persons with tetraplegia and a short-term intervention is able to significantly improve exercise capacity, cardiac autonomic regulation and respiratory muscle endurance, regardless of the absence of significant immediate changes in the level of autonomy.

A heat-stable microparticle platform for oral micronutrient delivery.

Micronutrient deficiencies affect up to 2 billion people and are the leading cause of cognitive and physical disorders in the developing world. Food fortification is effective in treating micronutrient deficiencies; however, its global implementation has been limited by technical challenges in maintaining micronutrient stability during cooking and storage. We hypothesized that polymer-based encapsulation could address this and facilitate micronutrient absorption. We identified poly(butylmethacrylate-co-(2-dimethylaminoethyl)methacrylate-co-methylmethacrylate) (1:2:1) (BMC) as a material with proven safety, offering stability in boiling water, rapid dissolution in gastric acid, and the ability to encapsulate distinct micronutrients. We encapsulated 11 micronutrients (iron; iodine; zinc; and vitamins A, B2, niacin, biotin, folic acid, B12, C, and D) and co-encapsulated up to 4 micronutrients. Encapsulation improved micronutrient stability against heat, light, moisture, and oxidation. Rodent studies confirmed rapid micronutrient release in the stomach and intestinal absorption. Bioavailability of iron from microparticles, compared to free iron, was lower in an initial human study. An organotypic human intestinal model revealed that increased iron loading and decreased polymer content would improve absorption. Using process development approaches capable of kilogram-scale synthesis, we increased iron loading more than 30-fold. Scaled batches tested in a follow-up human study exhibited up to 89% relative iron bioavailability compared to free iron. Collectively, these studies describe a broad approach for clinical translation of a heat-stable ingestible micronutrient delivery platform with the potential to improve micronutrient deficiency in the developing world. These approaches could potentially be applied toward clinical translation of other materials, such as natural polymers, for encapsulation and oral delivery of micronutrients.

Impacto de la rehabilitación vestibular en el riesgo de caída y la confianza del paciente / Impact of vestibular rehabilitation on the risk of falling and patient confidence

RESUMEN Introducción: Las alteraciones del sistema vestibular como la hipofunción vestibular unilateral, predisponen al usuario a sufrir caídas alterando así su confianza. Objetivo: Determinar el impacto de la rehabilitación vestibular en el riesgo de caídas y el grado de confianza en mujeres con hipofunción vestibular unilateral. Material y método: Se realiza estudio prospectivo en 20 pacientes de género femenino mayores de 60 años con diagnóstico de patología vestibular periférica. Se evalúa el riesgo de caídas con escala Tinetti y el grado de confianza al realizar actividades de la vida diaria por medio de la escala ABC (Activities-specific Balance Confidence), antes y después de realizar terapia de rehabilitación vestibular (RV). Resultados: Las dos variables estudiadas Tinetti y escala ABC demostraron mejoras significativas en la mayoría de las pacientes, demostrando que a medida que aumenta el grado de confianza disminuye el riesgo de caídas. Conclusión: Los resultados obtenidos de este estudio sugieren que la terapia de RV es eficiente en mejorar el riesgo de caídas y favorecer el aumento de confianza en las actividades de la vida diaria en el grupo de pacientes estudiadas.

ABSTRACT Introduction: Changes in the vestibular system, such as unilateral vestibular hypo-function, predispose the user to suffer falls, thus altering his confidence. Aim: To determine the impact of vestibular rehabilitation on the risk of falls and the degree of confidence in women with unilateral vestibular hypofunction. Material and method: A prospective study was conducted in 20 female patients over 60 years of age with a diagnosis of peripheral vestibular pathology. The risk of falls with a Tinetti scale and the degree of confidence in carrying out activities of daily living are evaluated through the ABC scale (Activities-specific Balance Confidence), before and after performing vestibular rehabilitation therapy (VRT). Results: The two variables studied, Tinetti and ABC scale showed significant improvements in most of the patients, demonstrating that as the degree of confidence increases the risk of falls decreases. Conclusion: The results obtained from this study suggest that VRT is efficient in improving the risk of falls and favoring an increase in confidence in the activities of daily life in the group of patients studied.

New distribution record of Epipompilus aztecus (Cresson, 1869) (Hymenoptera: Pompilidae) in the Brazilian Pantanal / Expansão da distribuição de registros de Epipompilus aztecus (Cresson, 1869) (Pompilidae) para o Pantanal brasileiro

Abstract Epipompilus aztecus (Cresson, 1869) was registered in South America in 2010. The aim of this paper is to report the first record of E. aztecus in the Brazilian Pantanal. Two female individuals of E. aztecus were collected in the northern portion of the Brazilian Pantanal in Mato Grosso State during November 2015. This new record of E. aztecus represents a range extension for the species.

Resumo Epipompilus aztecus (Cresson, 1869) foi registrado para a América do Sul em 2010. O objetivo deste estudo é relatar o primeiro registro de E. aztecus para o Pantanal brasileiro. Duas fêmeas de E. aztecus foram coletadas na parte norte do Pantanal brasileiro no estado de Mato Grosso, em novembro de 2015. O novo registro de E. aztecus representa uma extensão da distribuição de ocorrência para esta espécie.

New distribution record of Epipompilus aztecus (Cresson, 1869) (Hymenoptera: Pompilidae) in the Brazilian Pantanal.

Epipompilus aztecus (Cresson, 1869) was registered in South America in 2010. The aim of this paper is to report the first record of E. aztecus in the Brazilian Pantanal. Two female individuals of E. aztecus were collected in the northern portion of the Brazilian Pantanal in Mato Grosso State during November 2015. This new record of E. aztecus represents a range extension for the species.

Measuring Tau-microtubule affinity through cosedimentation assays.

Microtubule cosedimentation assays have long been used to study the affinity of interactions between Tau protein and microtubules. While these assays are very useful for characterizing and comparing the effects of alterations to either Tau or the microtubule filaments, they can also be problematic. We provide a set of straightforward instructions for performing these assays and point out a number of challenges and pitfalls that can complicate their interpretation.

Interactions between Tau and Different Conformations of Tubulin: Implications for Tau Function and Mechanism.

Tau is a multifaceted neuronal protein that stabilizes microtubules (MTs), but the mechanism of this activity remains poorly understood. Questions include whether Tau binds MTs laterally or longitudinally and whether Tau's binding affinity depends on the nucleotide state of tubulin. We observed that Tau binds tightly to Dolastatin-10 tubulin rings and promotes the formation of Dolastatin-10 ring stacks, implying that Tau can crosslink MT protofilaments laterally. In addition, we found that Tau prefers GDP-like tubulin conformations, which implies that Tau binding to the MT surface is biased away from the dynamic GTP-rich MT tip. To investigate the potential impact of these Tau activities on MT stabilization, we incorporated them into our previously developed dimer-scale computational model of MT dynamics. We found that lateral crosslinking activities have a much greater effect on MT stability than do longitudinal crosslinking activities, and that introducing a bias toward GDP tubulin has little impact on the observed MT stabilization. To address the question of why Tau is GDP-tubulin-biased, we tested whether Tau might affect MT binding of the +TIP EB1. We confirmed recent reports that Tau binds directly to EB1 and that Tau competes with EB1 for MT binding. Our results lead to a conceptual model where Tau stabilizes the MT lattice by strengthening lateral interactions between protofilaments. We propose that Tau's GDP preference allows the cell to independently regulate the dynamics of the MT tip and the stability of the lattice.

Comparison of conventional hamstring/quadriceps ratio between genders in level-matched soccer players / Comparación del ratio de fuerza convencional isquiotibial/cuádriceps entre jugadores de fútbol de niveles similares de ambos sexos / Comparação da relação de força convencional entre isquiotibiais/quadríceps entre jogadores de futebol com níveis semelhantes, de ambos os sexos

Objectives. The main goal of our study is to compare the hamstring/quadriceps (H/Q) ratio at different knee angles between level-matched male and female soccer players and to determine whether differences in the H/Q ratio exist between the dominant and the non-dominant leg. Methods. A cross-sectional study design was used to compare an isometric H/Q ratio and functional isokinetic ratio (between hamstring in eccentric contraction and quadriceps in concentric contraction) between males (n=14) and females (n=14). These ratios were studied at two different speeds of movement (60°s−1 and 180°s−1) and in five different positions (40°, 50°, 60°, 70° and 80° degrees of knee flexion). Results. Our results showed no differences in the H/Q ratio between genders. The ratio in the dominant leg showed an average of 9% higher values. The ratios were an average of 53.4% lower in positions near flexion than in positions near extension. Conclusions. For both men and women, the results showed lower ratios in the non-dominant leg compared to the dominant leg. At higher velocities, the force ratios were higher, while in more knee-flexed positions, the ratios were lower. Finally, we did not find differences in ratios between men and women (AU)

Objetivos. El objetivo principal del estudio es comparar el ratio de fuerza isquiotibial/cuádriceps (ratio H/Q) en diferentes ángulos de rodilla entre jugadores de fútbol de niveles similares y determinar si existen diferencias en dicho ratio entre la pierna dominante y la no dominante. Métodos. Se utilizó un diseño transversal para comparar el ratio isométrico H/Q y el ratio funcional isocinético (ratio entre la fuerza durante una contracción excéntrica de isquiotibial y la fuerza durante una contracción concéntrica de cuádriceps) entre hombres (n=14) y mujeres (n=14). Estos ratios se estudiaron en dos velocidades (60° s−1 y 180° s−1) y en 5 posiciones diferentes (40, 50, 60, 70 y 80 grados de flexión de rodilla). Resultados. Nuestros resultados no mostraron diferencias significativas en el ratio H/Q entre sexos. El ratio en la pierna dominante mostró valores un 9% más altos que en la pierna no dominante. Los ratios fueron de media un 53.4% más bajos en posiciones cercanas a la flexión que en posiciones cercanas a la extensión. Conclusiones. Para ambos sexos los resultados mostraron ratios más bajos en la pierna no dominante comparado con la pierna dominante. A velocidades superiores, los ratios de fuerza fueron mayores, mientras que en posiciones de mayor flexión de rodilla los ratios fueron menores. Por último, no se encontraron diferencias significativas en los ratios entre hombres y mujeres (AU)

Objetivos. O principal objetivo do nosso estudo é comparar a relação de força entre Isquiotibiais/Quadríceps (H/Q) em diferentes ângulos do joelho entre jogadores de futebol (masculino e feminino) de níveis semelhantes para determinar se existem diferenças na relação entre H/Q entre o membro dominante e a não-dominante. Método. U estudo de delineamento transversal foi utilizado para comparar a relação isométrica entre H/Q e isocinética funcional (razão entre a força dos isquiotibiais em contração excêntrica e do quadríceps em contração concêntrica, durante a extensão do joelho) entre homens (n=14) e mulheres (n=14). Estas razões foram estudadas em duas velocidades diferentes de movimento (60°/s e 180°/s) e em cinco posições diferentes (por exemplo 40, 50, 60, 70, e 80 graus de flexão do joelho). Resultados. Os resultados não mostraram diferenças significativas na relação H/Q entre os sexos. A relação da perna dominante mostrou valores médios de 9% mais elevados em relação a perna não dominante. As proporções foram, em média, 53,4% menor em posições próximas a flexão do que em posições perto da extensão. Conclusões. Para ambos os sexos, os resultados mostram razões mais baixas no membro não dominante em comparação com a dominante. À velocidade mais elevadas, as relações de força foram superiores, enquanto que em maiores flexões de joelho as relações foram menores. Finalmente, não foram encontradas diferenças significativas nas proporções entre homens e mulheres (AU)

New distribution record of Epipompilus aztecus (Cresson, 1869) (Hymenoptera: Pompilidae) in the Brazilian Pantanal

Abstract Epipompilus aztecus (Cresson, 1869) was registered in South America in 2010. The aim of this paper is to report the first record of E. aztecus in the Brazilian Pantanal. Two female individuals of E. aztecus were collected in the northern portion of the Brazilian Pantanal in Mato Grosso State during November 2015. This new record of E. aztecus represents a range extension for the species.

Resumo Epipompilus aztecus (Cresson, 1869) foi registrado para a América do Sul em 2010. O objetivo deste estudo é relatar o primeiro registro de E. aztecus para o Pantanal brasileiro. Duas fêmeas de E. aztecus foram coletadas na parte norte do Pantanal brasileiro no estado de Mato Grosso, em novembro de 2015. O novo registro de E. aztecus representa uma extensão da distribuição de ocorrência para esta espécie.

DNA purification using dynamic solid-phase extraction on a rotationally-driven polyethylene-terephthalate microdevice.

We report the development of a disposable polyester toner centrifugal device for semi-automated, dynamic solid phase DNA extraction (dSPE) from whole blood samples. The integration of a novel adhesive and hydrophobic valving with a simple and low cost microfabrication method allowed for sequential addition of reagents without the need for external equipment for fluid flow control. The spin-dSPE method yielded an average extraction efficiency of ∼45% from 0.6 µL of whole blood. The device performed single sample extractions or accommodate up to four samples for simultaneous DNA extraction, with PCR-readiness DNA confirmed by effective amplification of a ß-globin gene. The purity of the DNA was challenged by a multiplex amplification with 16 targeted amplification sites. Successful multiplexed amplification could routinely be obtained using the purified DNA collected post an on-chip extraction, with the results comparable to those obtained with commercial DNA extraction methods. This proof-of-principle work represents a significant step towards a fully-automated low cost DNA extraction device.

Environmental Heterogeneity in Parasitoid-Host Interaction for Mutillidae (Hymenoptera: Apocrita).

Environmental heterogeneity is a major factor influencing the spatial distribution of organisms. Due to intimate relationships with their hosts, parasitic insects are inclined to be even more sensitive to variations. This study aimed to verify the relationship between spatial distribution of Mutillidae, potential hosts, and the effect of heterogeneity in the distribution of both, testing the hypotheses: i) the spatial distribution of mutillids depends on the distribution of hosts and ii) variation in environmental heterogeneity affects the distribution of both. Sampling was conducted in four fragments of the Cerrado. We collected Hymenopteran specimens from 25 plots of one hectare using 18 Malaise traps throughout one year, totalizing 32,400 trap-hours. Female Mutillidae were hand collected at all sampling points, for a total of 450 man-hours. At each hectare plot, we obtained the environmental variables from nine plots of 25 m2 A total of 1,089 individuals were collected (Apidae: 311; Crabronidae: 165; Shpecidae: 84; Vespidae: 229) belonging to 127 species of potential hosts (bees and wasps) and 300 individuals (42 species) of Mutillidae. Leaf-litter depths showed significant relation in host-parasitoid distribution. The spatiotemporal distribution followed the predator-prey model for Mutillidae, and environmental heterogeneity was a factor that determined the structure of the host-parasitoid community. The results suggest an intense relationship between the Mutillidae and Crabronidae, as well as Sphecidae and two Apidae subfamilies (Halictinae and Colletinae). These families and subfamilies present behavior in which they build nests in aggregations even each female being solitary. Crabronidae is considered the best potential host for Mutillidae.

Prospective assessment of serum periostin as a biomarker for diagnosis and monitoring of eosinophilic oesophagitis.

BACKGROUND: Periostin is highly expressed in eosinophilic oesophagitis (EoE), but has not been extensively studied as a non-invasive biomarker. AIM: To assess whether serum periostin distinguished EoE from controls at baseline, had utility for monitoring treatment response, or was associated with IL-13 levels. METHODS: This was a sub-analysis of a prospective cohort study of adults undergoing out-patient upper endoscopy. Incident cases of EoE were diagnosed per consensus guidelines. Controls were subjects with either GERD or dysphagia without EoE. EoE patients were treated with swallowed/topical steroids and had repeat endoscopy/biopsy. Serum periostin levels for cases and controls were compared at baseline, and pre/post-treatment levels were compared for cases. Serum IL-13 and tissue expression of periostin were also assessed. RESULTS: A total of 61 incident EoE cases and 87 controls were analysed. Despite a marked increase in tissue periostin expression in cases, the median baseline serum periostin level was only slightly higher in cases than controls (22.1 ng/mL vs. 20.7; P = 0.04); there was no change in post-treatment levels. There was also no difference in serum periostin for cases by histologic response or atopic status. There was a strong trend towards higher serum IL-13 levels in cases in the highest periostin quartile (57.1 pg/mL vs. 2.6; P = 0.07). CONCLUSIONS: Serum periostin levels were similar in cases and controls, and there were no changes post-treatment. Given elevated IL-13 levels in the EoE patients with the highest periostin levels, future studies could explore periostin as a biomarker in EoE, perhaps in the setting of anti-IL-13 therapy.

Delta frequency optogenetic stimulation of the thalamic nucleus reuniens is sufficient to produce working memory deficits: relevance to schizophrenia.

BACKGROUND: Low-frequency (delta/theta) oscillations in the thalamocortical system are elevated in schizophrenia during wakefulness and are also induced in the N-methyl-D-asparate receptor hypofunction rat model. To determine whether abnormal delta oscillations might produce functional deficits, we used optogenetic methods in awake rats. We illuminated channelrhodopsin-2 in the thalamic nucleus reuniens (RE) at delta frequency and measured the effect on working memory (WM) performance (the RE is involved in WM, a process affected in schizophrenia [SZ]). METHODS: We injected RE with adeno-associated virus to transduce cells with channelrhodopsin-2. An optical fiber was implanted just dorsal to the hippocampus in order to illuminate RE axon terminals. RESULTS: During optogenetic delta frequency stimulation, rats displayed a strong WM deficit. On the following day, performance was normal if illumination was omitted. CONCLUSIONS: The optogenetic experiments show that delta frequency stimulation of a thalamic nucleus is sufficient to produce deficits in WM. This result supports the hypothesis that delta frequency bursting in particular thalamic nuclei has a causal role in producing WM deficits in SZ. The action potentials in these bursts may "jam" communication through the thalamus, thereby interfering with behaviors dependent on WM. Studies in thalamic slices using the N-methyl-D-asparate receptor hypofunction model show that delta frequency bursting is dependent on T-type Ca(2+) channels, a result that we confirmed here in vivo. These channels, which are strongly implicated in SZ by genome-wide association studies, may thus be a therapeutic target for treatment of SZ.

Beta-blocker therapy and prognosis of heart failure patients with new-onset diabetes mellitus.

BACKGROUND: The influence of beta-blocker therapy (bisoprolol or carvedilol) (bB) on the prognosis of heart failure (HF) patients with diabetes mellitus (DM) is uncertain. AIMS: To assess the effect of bB on the prognosis of HF patients with new-onset DM treated with a contemporary medical regime. METHODS: Prospective study of 5314 HF patients with previously unknown DM. Mean age was 71.8±7.9 years, 53.0% were women, and 50.2% had HF with preserved ejection fraction (HFpEF). During a median follow-up of 56.9±18.2 months, 68.9% of the patients died, 88.6% were hospitalised for HF, and 1519 (27.3%) developed DM (62.3% of them received bB, 947 patients). We propensity-matched 572 HF patients with DM on bB, with 572 HF patients with DM non-treated with bB. RESULTS: Beta-blocker therapy was associated with a decreased hazard risk (HR) of all-cause death [HR: 0.68, CI 95% (0.61-0.75)], mainly because of a reduced risk of death from cardiovascular causes [HR: 0.70 (0.64-0.77)] (p<0.001). Similarly, bB was associated with a decreased HR of hospitalisation [HR: 0.82 (0.72-0.92)] (p<0.001). Nevertheless, the 30-day re-admission rate and the number of visits were not significantly associated with bB. These relationships of bB with prognosis were maintained, independently of the gender, the type of HF (HFpEF ot HFdEF), the comorbidities and the medication used (p<0.01). CONCLUSION: Therapy with bB, bisoprolol or carvedilol, is associated with a reduced mortality and morbidity of HF patients with new-onset DM, not only in men but also in women, as well as in patients with HFpEF or HFdEF.

Fluctuations of the anthropometric indices and mortality of patients with incident heart failure: a prospective study in the community.

BACKGROUND: The relationship between the fluctuations of the anthropometric indices (AIs) and the prognosis of patients with incident heart failure (HF) in a population-based cohort is unknown. AIMS: To assess the relationship between the fluctuations of the AIs, body mass index (BMI), waist hip ratio (WHR), and weight height ratio (WHeR) and the prognosis of patients with incident HF. METHODS: Anthropometric indices were prospectively measured in a 10-year population-based study of 6492 patients with incident HF (GAMIC cohort). 4530 patients (66.7%) died, during a mean follow-up of 72.7 ± 14.2 months. A time-updated analysis of the changes of the AIs was performed to assess their association with mortality and morbidity (hospitalisations and visits). RESULTS: Patients with incident HF presenting ≥ 5% decrease or ≥ 7% increase of the AIs have an increased mortality [HR ≥ 1.65 (1.52-2.34) or HR ≥ 1.71 (1.58-1.85), respectively, p < 0.001]. Mortality risk increased ≥ 1.43-fold (p = -0.0003) for each 10% change in the AIs. There was an accelerated pattern of reduction in the AIs in the 6 months prior to death, and an accelerated increase in the AIs in the 3 months prior to hospitalisation. These observations were independent of the aetiology (ischaemic vs. non-ischaemic), the type of HF (systolic vs. non-systolic), and other predictors of mortality. CONCLUSIONS: Time-updated changes (increase or decrease) of the AIs, BMI, WHR and weight height ratio are independently associated with the mortality of patients with incident HF.

Using MTBindingSim as a tool for experimental planning and interpretation.

MTBindingSim is a program that enables users to simulate experiments in which proteins or other ligands (e.g., drugs) bind to microtubules or other polymers under various binding models. The purpose of MTBindingSim is to help researchers and students gain an intuitive understanding of binding behavior and design experiments to distinguish between different binding mechanisms. MTBindingSim is open-source, freely available software and can be found at bindingtutor.org/mtbindingsim. This chapter first describes the capabilities of MTBindingSim, including the experimental designs and protein-binding models that it simulates, and then discusses two examples in which MTBindingSim is utilized in an experimental context. In the first, MTBindingSim is used to investigate potential explanations for unusual behavior observed in the binding of the neuronal protein Tau to microtubules, demonstrating that some potential explanations are incompatible with the experimental data. In the second example, MTBindingSim is used to design experiments to examine the question of whether the plus-end tracking protein EB1 binds preferentially to the microtubule seam.

Biochemical evidence that human EB1 does not bind preferentially to the microtubule seam.

EB1 is a highly conserved microtubule (MT) plus end tracking protein (+TIP) involved in regulating MT dynamics, but the mechanisms of its effects on MT polymerization remain undefined. Resolving this question requires understanding how EB1 interacts with MTs. Previous electron microscopy of the S. pombe EB1 homolog Mal3p suggested that Mal3p binds specifically to the MT seam, implying that EB1 family members promote MT polymerization by stabilizing the seam. However, more recent electron microscopy indicates that Mal3p binds everywhere except the seam. Neither set of experiments investigated the behavior of human EB1, or provided an explanation for why these studies arrived at different answers. To resolve these questions, we have used a combination of MT-binding assays and theoretical modeling with MTBindingSim. Our results indicate that human EB1 binds to the lattice, consistent with the recent Mal3p results, and show that Mal3p-binding assays that were previously interpreted as evidence for preferential seam binding are equally consistent with weak lattice binding. In addition, we used analytical ultracentrifugation to investigate the possibility that the EB1 monomer-dimer equilibrium might contribute to EB1 binding behavior, and determined that the EB1 dimerization dissociation constant is approximately 90 nM. We and others find that the cellular concentration of EB1 is on the order of 200 nM, suggesting that a portion of EB1 may be monomeric at physiological concentrations. These observations lead us to suggest that regulation of EB1 dimerization might play a role in controlling EB1 function.

Taxol-stabilized microtubules promote the formation of filaments from unmodified full-length Tau in vitro.

Tau is a neuronal protein that stabilizes the microtubule (MT) network, but it also forms filaments associated with Alzheimer's disease. Understanding Tau-MT and Tau-Tau interactions would help to establish Tau function in health and disease. For many years, literature reports on Tau-MT binding behavior and affinity have remained surprisingly contradictory (e.g., 10-fold variation in Tau-MT affinity). Tau-Tau interactions have also been investigated, but whether MTs might affect Tau filament formation is unknown. We have addressed these issues through binding assays and microscopy. We assessed Tau-MT interactions via cosedimentation and found that the measured affinity of Tau varies greatly, depending on the experimental design and the protein concentrations used. To investigate this dependence, we used fluorescence microscopy to examine Tau-MT binding. Strikingly, we found that Taxol-stabilized MTs promote Tau filament formation without characterized Tau-filament inducers. We propose that these novel Tau filaments account for the incongruence in Tau-MT affinity measurements. Moreover, electron microscopy reveals that these filaments appear similar to the heparin-induced Alzheimer's model. These observations suggest that the MT-induced Tau filaments provide a new model for Alzheimer's studies and that MTs might play a role in the formation of Alzheimer's-associated neurofibrillary tangles.

Artroplastia total tras fractura intracapsular de cadera en paciente con parálisis cerebral infantil / A case of intracapsular hip fracture in a patient with infantile cerebral palsy

Objetivo: Presentamos el caso de un paciente de 36 años con una fractura intracapsular de extremidad proximal de fémur de larga evolución que fue sometido a una artroplastia de sustitución total con un resultado funcional excelente. La tasa de aflojamiento del implante es baja a pesar de la juventud de estos pacientes, pues tienen un nivel de actividad bajo y precisan de ayuda de bastones. Hay que considerar la espasticidad, los movimientos involuntarios y la realización de tenotomías que merman la estabilidad del implante (AU)

Objective: We present the case of a 36 year-old patient with an intracapsular fracture of the proximal femur who underwent a total replacement arthroplasty with an excellent functional outcome. The loosening rate of the implant is low despite youth of these patients, as they have a low level of activity and require the aid of crutches. It should be considered that spasticity, involuntary movements and the performance of tenotomies decrease the stability of the implant (AU)