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1.
Talanta ; 221: 121494, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33076099

RESUMO

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.


Assuntos
Arsênio , Arsenicais , Acetatos , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas
2.
Eur J Sport Sci ; 20(7): 926-934, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31566476

RESUMO

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.


Assuntos
Terapia por Exercício/métodos , Frequência Cardíaca/fisiologia , Quadriplegia/fisiopatologia , Respiração , Traumatismos da Medula Espinal/fisiopatologia , Adulto , Vértebras Cervicais , Exercício Físico/fisiologia , Terapia por Exercício/instrumentação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Resistência Física , Testes de Função Respiratória , Músculos Respiratórios/fisiologia , Espirometria , Adulto Jovem
3.
Sci Transl Med ; 11(518)2019 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-31723037

RESUMO

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.


Assuntos
Temperatura Alta , Micronutrientes/administração & dosagem , Microesferas , Administração Oral , Animais , Disponibilidade Biológica , Transporte Biológico , Preparações de Ação Retardada , Liberação Controlada de Fármacos , Feminino , Humanos , Ácido Hialurônico/química , Absorção Intestinal , Intestinos/fisiologia , Ferro/metabolismo , Metacrilatos/química , Camundongos , Oxirredução , Raios Ultravioleta , Vitamina A/metabolismo , Água
4.
Rev. otorrinolaringol. cir. cabeza cuello ; 79(3): 307-314, set. 2019. graf
Artigo em Espanhol | LILACS | ID: biblio-1058701

RESUMO

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.


Assuntos
Humanos , Feminino , Pessoa de Meia-Idade , Acidentes por Quedas/prevenção & controle , Doenças Vestibulares/psicologia , Doenças Vestibulares/reabilitação , Medição de Risco , Atividades Cotidianas , Estudos Prospectivos , Confiança , Equilíbrio Postural
5.
Braz. j. biol ; 79(3): 466-469, July-Sept. 2019. graf
Artigo em Inglês | LILACS | ID: biblio-1001459

RESUMO

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.


Assuntos
Animais , Feminino , Vespas/anatomia & histologia , Vespas/fisiologia , Distribuição Animal , Brasil
6.
Braz J Biol ; 79(3): 466-469, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30231139

RESUMO

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.


Assuntos
Distribuição Animal , Vespas/anatomia & histologia , Vespas/fisiologia , Animais , Brasil , Feminino
7.
Methods Cell Biol ; 141: 115-134, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28882298

RESUMO

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.


Assuntos
Citoesqueleto/metabolismo , Microtúbulos/metabolismo , Proteínas tau/metabolismo , Centrifugação com Gradiente de Concentração , Humanos , Ligação Proteica
8.
J Mol Biol ; 429(9): 1424-1438, 2017 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-28322917

RESUMO

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.


Assuntos
Guanosina Difosfato/metabolismo , Tubulina (Proteína)/química , Tubulina (Proteína)/metabolismo , Proteínas tau/metabolismo , Animais , Humanos , Modelos Biológicos , Modelos Moleculares , Simulação de Dinâmica Molecular , Ligação Proteica , Conformação Proteica , Suínos
9.
Artigo em Inglês | LILACS-Express | LILACS, VETINDEX | ID: biblio-1467204

RESUMO

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.

10.
Anal Chim Acta ; 937: 1-10, 2016 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-27590539

RESUMO

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.


Assuntos
DNA/isolamento & purificação , Dispositivos Lab-On-A-Chip , Polietilenotereftalatos/química , Rotação , Extração em Fase Sólida/instrumentação , DNA/química , DNA/genética , Desenho de Equipamento , Interações Hidrofóbicas e Hidrofílicas , Campos Magnéticos , Reação em Cadeia da Polimerase
11.
Environ Entomol ; 45(5): 1146-1153, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27555643

RESUMO

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.


Assuntos
Distribuição Animal , Interações Hospedeiro-Parasita , Vespas/fisiologia , Vespas/parasitologia , Animais , Brasil , Meio Ambiente , Feminino , Densidade Demográfica
12.
Aliment Pharmacol Ther ; 44(2): 189-97, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27193351

RESUMO

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.


Assuntos
Moléculas de Adesão Celular/sangue , Esofagite Eosinofílica/diagnóstico , Interleucina-13/sangue , Adulto , Biomarcadores/sangue , Biópsia , Transtornos de Deglutição/diagnóstico , Endoscopia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pacientes Ambulatoriais , Estudos Prospectivos
13.
Biol Psychiatry ; 77(12): 1098-107, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25891221

RESUMO

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.


Assuntos
Ritmo Delta/fisiologia , Transtornos da Memória/fisiopatologia , Memória de Curto Prazo/fisiologia , Núcleos da Linha Média do Tálamo/fisiologia , Esquizofrenia/fisiopatologia , Psicologia do Esquizofrênico , Animais , Hipocampo/fisiologia , Masculino , Transtornos da Memória/etiologia , Optogenética , Ratos , Ratos Long-Evans , Esquizofrenia/etiologia
14.
Int J Clin Pract ; 69(5): 550-9, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25707623

RESUMO

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.


Assuntos
Antagonistas de Receptores Adrenérgicos alfa 1/uso terapêutico , Bisoprolol/uso terapêutico , Carbazóis/uso terapêutico , Diabetes Mellitus Tipo 2/complicações , Insuficiência Cardíaca/tratamento farmacológico , Propanolaminas/uso terapêutico , Idoso , Carvedilol , Estudos de Casos e Controles , Feminino , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/mortalidade , Humanos , Masculino , Prognóstico , Estudos Prospectivos , Índice de Gravidade de Doença , Espanha
15.
Int J Clin Pract ; 69(2): 169-79, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25040352

RESUMO

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.


Assuntos
Antropometria , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/mortalidade , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Estudos de Coortes , Feminino , Insuficiência Cardíaca/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Fatores de Risco , Espanha/epidemiologia , Relação Cintura-Quadril/estatística & dados numéricos
16.
Methods Cell Biol ; 115: 375-84, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23973084

RESUMO

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.


Assuntos
Simulação por Computador , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Proteínas tau/metabolismo , Sítios de Ligação , Humanos , Polímeros/metabolismo , Ligação Proteica , Software
17.
Cytoskeleton (Hoboken) ; 70(6): 317-27, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23864329

RESUMO

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.


Assuntos
Interleucinas/metabolismo , Microtúbulos/metabolismo , Modelos Teóricos , Sítios de Ligação , Bioensaio , Dimerização , Humanos , Antígenos de Histocompatibilidade Menor , Modelos Biológicos , Ligação Proteica
18.
Mol Biol Cell ; 23(24): 4796-806, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23087208

RESUMO

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.


Assuntos
Microtúbulos/efeitos dos fármacos , Emaranhados Neurofibrilares/efeitos dos fármacos , Paclitaxel/farmacologia , Proteínas tau/metabolismo , Doença de Alzheimer/metabolismo , Ligação Competitiva , Western Blotting , Heparina/farmacologia , Humanos , Cinética , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Microtúbulos/metabolismo , Microtúbulos/ultraestrutura , Emaranhados Neurofibrilares/metabolismo , Emaranhados Neurofibrilares/ultraestrutura , Ligação Proteica , Moduladores de Tubulina/farmacologia , Proteínas tau/química
19.
Arthritis Rheum ; 63(10): 2854-64, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21618201

RESUMO

OBJECTIVE: To compare the efficacy and safety of subcutaneous (SC) and intravenous (IV) abatacept. METHODS: In this phase IIIb double-blind, double-dummy, 6-month study, patients with rheumatoid arthritis (RA) and inadequate responses to methotrexate were randomized to receive 125 mg SC abatacept on days 1 and 8 and weekly thereafter (plus an IV loading dose [∼10 mg/kg] on day 1) or IV abatacept (∼10 mg/kg) on days 1, 15, and 29 and every 4 weeks thereafter. The primary end point for determining the noninferiority of SC abatacept to IV abatacept was the proportion of patients in each group meeting the American College of Rheumatology 20% improvement criteria (achieving an ACR20 response) at month 6. Other efficacy end points, immunogenicity, and safety were also assessed. RESULTS: Of 1,457 patients, 693 of 736 (94.2%) treated with SC abatacept and 676 of 721 (93.8%) treated with IV abatacept completed 6 months. At month 6, 76.0% (95% confidence interval 72.9, 79.2) of SC abatacept-treated patients versus 75.8% (95% confidence interval 72.6, 79.0) of IV abatacept-treated patients achieved an ACR20 response (estimated difference between groups 0.3% [95% confidence interval -4.2, 4.8]), confirming noninferiority of SC abatacept to IV abatacept. Onset and magnitude of ACR responses and disease activity and physical function improvements were comparable between the SC and IV abatacept-treated groups. The proportions of adverse events (AEs) and serious AEs over 6 months were 67.0% and 4.2%, respectively, in the SC abatacept-treated group and 65.2% and 4.9%, respectively, in the IV abatacept-treated group, with comparable frequencies of serious infections, malignancies, and autoimmune events between groups. SC injection site reactions (mostly mild) occurred in 19 SC abatacept (IV placebo)-treated patients (2.6%) and 18 IV abatacept (SC placebo)-treated patients (2.5%). Abatacept-induced antibodies occurred in 1.1% of SC abatacept-treated patients and 2.3% of IV abatacept-treated patients. CONCLUSION: SC abatacept provides efficacy and safety comparable with that of IV abatacept, with low immunogenicity and high retention rates, consistent with the established IV abatacept profile. Rates of injection site reactions were low. SC abatacept will provide additional treatment options, such as an alternative route of administration, for patients with RA.


Assuntos
Antirreumáticos/administração & dosagem , Artrite Reumatoide/tratamento farmacológico , Imunoconjugados/administração & dosagem , Abatacepte , Adulto , Idoso , Antirreumáticos/uso terapêutico , Método Duplo-Cego , Feminino , Humanos , Imunoconjugados/uso terapêutico , Injeções Intravenosas , Injeções Subcutâneas , Masculino , Metotrexato/uso terapêutico , Pessoa de Meia-Idade , Resultado do Tratamento
20.
J Appl Microbiol ; 109(6): 1886-96, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20666869

RESUMO

AIMS: To evaluate six commercial DNA extraction kits for their ability to isolate PCR-quality DNA from Bacillus spores in various soil samples. METHODS AND RESULTS: Three soils were inoculated with various amounts of Bacillus cereus spores to simulate an outbreak or intentional release of the threat agent Bacillus anthracis. DNA was isolated from soil samples using six commercial DNA extraction kits. Extraction and purification efficiencies were assessed using a duplex real-time PCR assay that included an internal positive control. The FastDNA(®) SPIN kit for Soil showed the highest DNA extraction yield, while the E.Z.N.A.(®) Soil DNA and PowerSoil(®) DNA Isolation kits showed the highest efficiencies in removing PCR inhibitors from loam soil extracts. CONCLUSIONS: The results of this study suggest that commercially available extraction kits can be used to extract PCR-quality DNA from bacterial spores in soil. The selection of an appropriate extraction kit should depend on the characteristics of the soil sample and the intended downstream application. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study aid in the selection of an appropriate DNA extraction kit for a given soil sample. Its application could expedite sample processing for real-time PCR detection of a pathogen in soil.


Assuntos
Bacillus cereus/isolamento & purificação , DNA Bacteriano/isolamento & purificação , Kit de Reagentes para Diagnóstico/microbiologia , Microbiologia do Solo , Bacillus anthracis/isolamento & purificação , Viabilidade Microbiana , Reação em Cadeia da Polimerase/métodos , Solo/análise , Esporos Bacterianos/isolamento & purificação
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