Tail length and E525K dilated cardiomyopathy mutant alter human ß-cardiac myosin super-relaxed state.

Dilated cardiomyopathy (DCM) is a condition characterized by impaired cardiac function, due to myocardial hypo-contractility, and is associated with point mutations in ß-cardiac myosin, the molecular motor that powers cardiac contraction. Myocardial function can be modulated through sequestration of myosin motors into an auto-inhibited "super-relaxed" state (SRX), which may be further stabilized by a structural state known as the "interacting heads motif" (IHM). Here, we sought to determine whether hypo-contractility of DCM myocardium results from reduced function of individual myosin molecules or from decreased myosin availability to interact with actin due to increased IHM/SRX stabilization. We used an established DCM myosin mutation, E525K, and characterized the biochemical and mechanical activity of wild-type and mutant human ß-cardiac myosin constructs that differed in the length of their coiled-coil tail, which dictates their ability to form the IHM/SRX state. We found that short-tailed myosin constructs exhibited low IHM/SRX content, elevated actin-activated ATPase activity, and fast velocities in unloaded motility assays. Conversely, longer-tailed constructs exhibited higher IHM/SRX content and reduced actomyosin ATPase and velocity. Our modeling suggests that reduced velocities may be attributed to IHM/SRX-dependent sequestration of myosin heads. Interestingly, longer-tailed E525K mutants showed no apparent impact on velocity or actomyosin ATPase at low ionic strength but stabilized IHM/SRX state at higher ionic strength. Therefore, the hypo-contractility observed in DCM may be attributable to reduced myosin head availability caused by enhanced IHM/SRX stability in E525K mutants.

Tail Length and E525K Dilated Cardiomyopathy Mutant Alter Human ß-Cardiac Myosin Super-Relaxed State.

Dilated cardiomyopathy (DCM) is characterized by impaired cardiac function due to myocardial hypo-contractility and is associated with point mutations in ß-cardiac myosin, the molecular motor that powers cardiac contraction. Myocardial function can be modulated through sequestration of myosin motors into an auto-inhibited "super relaxed" state (SRX), which is further stabilized by a structural state known as the "Interacting Heads Motif" (IHM). Therefore, hypo-contractility of DCM myocardium may result from: 1) reduced function of individual myosin, and/or; 2) decreased myosin availability due to increased IHM/SRX stabilization. To define the molecular impact of an established DCM myosin mutation, E525K, we characterized the biochemical and mechanical activity of wild-type (WT) and E525K human ß-cardiac myosin constructs that differed in the length of their coiled-coil tail, which dictates their ability to form the IHM/SRX state. Single-headed (S1) and a short-tailed, double-headed (2HEP) myosin constructs exhibited low (~10%) IHM/SRX content, actin-activated ATPase activity of ~5s-1 and fast velocities in unloaded motility assays (~2000nm/s). Double-headed, longer-tailed (15HEP, 25HEP) constructs exhibited higher IHM/SRX content (~90%), and reduced actomyosin ATPase (<1s-1) and velocity (~800nm/s). A simple analytical model suggests that reduced velocities may be attributed to IHM/SRXdependent sequestration of myosin heads. Interestingly, the E525K 15HEP and 25HEP mutants showed no apparent impact on velocity or actomyosin ATPase at low ionic strength. However, at higher ionic strength, the E525K mutation stabilized the IHM/SRX state. Therefore, the E525K-associated DCM human cardiac hypo-contractility may be attributable to reduced myosin head availability caused by enhanced IHM/SRX stability.

School Choice, Teachers' Work, and Professional Identity.

Teacher professional identity, or what it means to be a teacher, informs the types of schools teachers seek for work. With the marketization of schools in the US and abroad, teachers' professional identities are changing. However, we know little about how teachers negotiate-and renegotiate-their professional identities during the job search in contexts with school choice, such as charter schools. This study uses qualitative interview data from 46 teachers in San Antonio, Texas, where over 25% of students attend charter schools. Our findings illuminate the job search as a critical juncture where teachers evaluate their professional identity as they make choices about the sector-charter or traditional public school-and/or school organization they prefer. In particular, the choice context legitimated flexibility and fluidity in teachers' professional identity as teachers moved between sectors to find jobs, even if the school did not align with their personal or professional values. We also found that employability and teachers' perception of the job market played an important role in how teachers strategically presented their professional identity on the job search. Findings offer implications for teacher education and teacher workforce policies.

La identidad profesional docente, o lo que significa ser docente, informa los tipos de escuelas que los docentes buscan para trabajar. Con la mercantilización de las escuelas en los EEUU y en el extranjero, las identidades profesionales de los docentes están cambiando. Sin embargo, sabemos poco acerca de cómo los docentes negocian y renegocian sus identidades profesionales durante la búsqueda de empleo en contextos de elección de escuela, como las escuelas chárter. Este estudio utiliza datos de entrevistas cualitativas de 46 maestros en San Antonio, Texas, donde más del 25 % de los estudiantes asisten a escuelas chárter. Nuestros hallazgos iluminan la búsqueda de empleo como un momento crítico en el que los docentes evalúan su identidad profesional al tomar decisiones sobre el sector (escuela pública autónoma o tradicional) y/o la organización escolar que prefieren. En particular, el contexto de elección legitimó la flexibilidad y la fluidez en la identidad profesional de los docentes a medida que los docentes se movían entre sectores para encontrar trabajo, incluso si la escuela no se alineaba con sus valores personales o profesionales. También encontramos que la empleabilidad y la percepción de los docentes sobre el mercado laboral jugaron un papel importante en la forma en que los docentes presentaron estratégicamente su identidad profesional en la búsqueda de empleo. Los hallazgos ofrecen implicaciones para la formación docente y las políticas de fuerza laboral docente.

A identidade profissional do professor, ou o que significa ser professor, informa os tipos de escolas que os professores procuram para trabalhar. Com o marketing das escolas nos EUA e no exterior, as identidades profissionais dos professores estão mudando. No entanto, sabemos pouco sobre como os professores negociam ­ e renegociam ­ suas identidades profissionais durante a busca de emprego em contextos de escolha escolar, como as escolas charter. Este estudo usa dados de entrevistas qualitativas de 46 professores em San Antonio, Texas, onde mais de 25% dos alunos frequentam escolas charter. Nossas descobertas iluminam a busca de emprego como um momento crítico em que os professores avaliam sua identidade profissional ao fazerem escolhas sobre o setor ­ escola charter ou escola pública tradicional ­ e/ou organização escolar de sua preferência. Em particular, o contexto de escolha legitimou flexibilidade e fluidez na identidade profissional dos professores à medida que os professores se desloc avam entre os setores para encontrar emprego, mesmo que a escola não se alinhasse com seus valores pessoais ou profissionais. Constatamos também que a empregabilidade e a percepção dos professores sobre o mercado de trabalho desempenharam um papel importante na forma como os professores apresentaram estrategicamente sua identidade profissional na busca de emprego. Os resultados oferecem implicações para as políticas de formação de professores e força de trabalho de professores.

Relaxed tarantula skeletal muscle has two ATP energy-saving mechanisms.

Myosin molecules in the relaxed thick filaments of striated muscle have a helical arrangement in which the heads of each molecule interact with each other, forming the interacting-heads motif (IHM). In relaxed mammalian skeletal muscle, this helical ordering occurs only at temperatures >20°C and is disrupted when temperature is decreased. Recent x-ray diffraction studies of live tarantula skeletal muscle have suggested that the two myosin heads of the IHM (blocked heads [BHs] and free heads [FHs]) have very different roles and dynamics during contraction. Here, we explore temperature-induced changes in the BHs and FHs in relaxed tarantula skeletal muscle. We find a change with decreasing temperature that is similar to that in mammals, while increasing temperature induces a different behavior in the heads. At 22.5°C, the BHs and FHs containing ADP.Pi are fully helically organized, but they become progressively disordered as temperature is lowered or raised. Our interpretation suggests that at low temperature, while the BHs remain ordered the FHs become disordered due to transition of the heads to a straight conformation containing Mg.ATP. Above 27.5°C, the nucleotide remains as ADP.Pi, but while BHs remain ordered, half of the FHs become progressively disordered, released semipermanently at a midway distance to the thin filaments while the remaining FHs are docked as swaying heads. We propose a thermosensing mechanism for tarantula skeletal muscle to explain these changes. Our results suggest that tarantula skeletal muscle thick filaments, in addition to having a superrelaxation-based ATP energy-saving mechanism in the range of 8.5-40°C, also exhibit energy saving at lower temperatures (<22.5°C), similar to the proposed refractory state in mammals.

The myosin interacting-heads motif present in live tarantula muscle explains tetanic and posttetanic phosphorylation mechanisms.

Striated muscle contraction involves sliding of actin thin filaments along myosin thick filaments, controlled by calcium through thin filament activation. In relaxed muscle, the two heads of myosin interact with each other on the filament surface to form the interacting-heads motif (IHM). A key question is how both heads are released from the surface to approach actin and produce force. We used time-resolved synchrotron X-ray diffraction to study tarantula muscle before and after tetani. The patterns showed that the IHM is present in live relaxed muscle. Tetanic contraction produced only a very small backbone elongation, implying that mechanosensing-proposed in vertebrate muscle-is not of primary importance in tarantula. Rather, thick filament activation results from increases in myosin phosphorylation that release a fraction of heads to produce force, with the remainder staying in the ordered IHM configuration. After the tetanus, the released heads slowly recover toward the resting, helically ordered state. During this time the released heads remain close to actin and can quickly rebind, enhancing the force produced by posttetanic twitches, structurally explaining posttetanic potentiation. Taken together, these results suggest that, in addition to stretch activation in insects, two other mechanisms for thick filament activation have evolved to disrupt the interactions that establish the relaxed helices of IHMs: one in invertebrates, by either regulatory light-chain phosphorylation (as in arthropods) or Ca2+-binding (in mollusks, lacking phosphorylation), and another in vertebrates, by mechanosensing.

[Encephalitis caused by type B influenza virus in an adult. Report of one case]. / Encefalitis por virus influenza B en un paciente adulto. Reporte de caso.

Neurological manifestations associated with influenza virus infection include encephalitis, encephalopathy, acute necrotizing encephalitis, transverse myelitis, acute disseminated encephalomyelitis, mild encephalitis with reversible splenial syndrome (MERS), and Guillaín Barré syndrome. We report a 16-year-old female who was admitted at our emergency department with seizures, confusion, nystagmus and motor clumsiness five days after an upper a respiratory tract infection. Influenza type B virus infection was confirmed by chain polymerase reaction analysis. The initial electroencephalogram demonstrated a pattern of global slowness without epileptic discharges. One week later, it showed a progression to slow-wave focal bilateral discharges at both temporal and occipital lobes. The patient had a favorable evolution and was discharged 19 days after admission with phenytoin to prevent seizures.

Encefalitis por virus influenza B en un paciente adulto: reporte de caso / Encephalitis caused by type B influenza virus in an adult: report of one case

Neurological manifestations associated with influenza virus infection include encephalitis, encephalopathy, acute necrotizing encephalitis, transverse myelitis, acute disseminated encephalomyelitis, mild encephalitis with reversible splenial syndrome (MERS), and Guillaín Barré syndrome. We report a 16-year-old female who was admitted at our emergency department with seizures, confusion, nystagmus and motor clumsiness five days after an upper a respiratory tract infection. Influenza type B virus infection was confirmed by chain polymerase reaction analysis. The initial electroencephalogram demonstrated a pattern of global slowness without epileptic discharges. One week later, it showed a progression to slow-wave focal bilateral discharges at both temporal and occipital lobes. The patient had a favorable evolution and was discharged 19 days after admission with phenytoin to prevent seizures.

The influence of the metal cations and microhydration on the reaction trajectory of the N3 ↔ O2 thymine proton transfer: Quantum mechanical study.

This study involves the intramolecular proton transfer (PT) process on a thymine nucleobase between N3 and O2 atoms. We explore a mechanism for the PT assisted by hexacoordinated divalent metals cations, namely Mg2+ , Zn2+ , and Hg2+ . Our results point out that this reaction corresponds to a two-stage process. The first involves the PT from one of the aqua ligands toward O2. The implications of this stage are the formation of a hydroxo anion bound to the metal center and a positively charged thymine. To proceed to the second stage, a structural change is needed to allow the negatively charged hydroxo ligand to abstract the N3 proton, which represents the final product of the PT reaction. In the presence of the selected hexaaqua cations, the activation barrier is at most 8 kcal/mol. © 2017 Wiley Periodicals, Inc.

Prevalence of neuropathic symptoms in patients referred for temporomandibular disorder in a Chilean hospital, 2014-2015 / Prevalencia de síntomas neuropáticos en pacientes derivados por trastorno témporomandibular en un hospital chileno, 2014-2015

To determine the prevalence of neuropathic symptoms in the orofacial region in patients referred for painful temporomandibular disorder at Hospital Base Valdivia in 2014 and 2015. Materials and method: An observational study was conducted on patients referred for painful temporomandibular disorder by general dentists working in primary dental health care at Hospital Base Valdivia, during October 2014 and March and April 2015. Patients were asked to complete the LANSS pain scale by one of the examiners. The variables age, sex and location of pain were measured and registered. Results: Of the 84 patients surveyed, 88.1 percent were women, with a mean age of 38.2 years. The median score obtained with the LANSS scale was 3.0 [0-8.75]. A 20.2 percent had neuropathic pain symptoms. They were all women with an average age of 36.7. The most recurrent painful area was the right mandibular dermatome of the trigeminal nerve in patients with neuropathic pain symptoms. Conclusion: The prevalence of symptoms of neuropathic pain was 20 percent in patients referred for painful temporomandibular disorders. Dentists should evaluate neuropathic symptoms to provide a proper management of the condition...

Determinar la prevalencia de síntomas neuropáticos orofaciales en pacientes derivados por trastorno témporomandibular doloroso al Hospital Base Valdivia en 2014 y 2015. Material y métodos: Se desarrolló un estudio observacional incluyendo pacientes derivados por trastorno témporomandibular doloroso por odontólogos generales de atención primaria en salud, al servicio dental del Hospital, durante octubre del 2014, marzo y abril del 2015. Un examinador les aplicó la escala de dolor LANSS. Se midieron las variables edad, sexo y localización del dolor. Resultados: De los 84 pacientes encuestados, el 88.1 por ciento fueron mujeres, edad promedio de 38.2 años. La mediana del puntaje obtenido en la escala fue de 3.0 [0-8.75]. Un 20.2 por ciento presentó síntomas de dolor neuropático, todos mujeres, promedio de edad de 36.7 años. El dermatoma de la rama mandibular del nervio trigémino del lado derecho fue la zona dolorosa más frecuente en pacientes con síntomas de dolor neuropático. Conclusión: La prevalencia de síntomas de dolor neuropático es de un 20 por ciento en pacientes derivados por trastornos témporomandibulares dolorosos. Odontólogos deben considerar evaluar la presencia de síntomas neuropáticos para brindar un manejo adecuado...

Spectroscopic characterization of the inclusion complexes of luteolin with native and derivatized beta-cyclodextrin.

The inclusion complexes of Luteolin (LU) with cyclodextrins (CDs) including beta-cyclodextrin (betaCD), hydroxypropyl-beta-cyclodextrin (HPbetaCD) and dimethyl-beta-cyclodextrin (DMbetaCD), Scheme 1, have been investigated using the method of steady-state fluorescence. The stoichiometric ratio of the three complexes was found to be 1:1 and the stability constants (K) were estimated from spectrofluorometric titrations, as well as the thermodynamic parameters. Maximum inclusion ability was obtained in the case of HPbetaCD followed by DMbetaCD and betaCD. Moreover, 1H NMR and 2D NMR were carried out, revealing that LU has different form of inclusion which is in agreement with molecular modeling studies. These models confirm that when LU-betaCD and LU-DMbetaCD complexes are formed, the B-ring is oriented toward the primary rim; however, for LU-HPbetaCD complex this ring is oriented toward the secondary rim. The ESR results showed that the antioxidant activity of luteolin was the order LU-HPbetaCD>LU-DMbetaCD>LU-betaCD>LU, hence the LU-complexes behave are better antioxidants than luteolin free.

Studies of inclusion complexes of natural and modified cyclodextrin with (+)catechin by NMR and molecular modeling.

The aim of this paper is to describe the inclusion properties and the factors affecting the complexation selectivity and stabilization of catechin (CA) into beta-cyclodextrin (beta-CD) and two of its derivatives, namely Heptakis 2,6-di-O-methyl-beta-cyclodextrin (DM-beta-CD) and 2 hydroxypropyl-beta-cyclodextrin (HP-beta-CD). Analysis of the proton shift change using the continuous variation method confirm the formation of a 1:1 stoichiometric complex for catechin and the different CDs in aqueous medium. The formations constant obtained by diffusion-ordered spectroscopy (DOSY) techniques indicated the following trend upon complex formation: beta-CD>HP-beta-CD>DM-beta-CD. The detailed spatial configuration is proposed based on 2D NMR methods. These results are further interpreted using molecular modeling studies. The latter results are in good agreement with the experimental data. The models confirm that when CA-beta-CD is formed, the catechol moiety in the complex is oriented toward the primary rim; however when CD is derivatized to HP-beta-CD and DM-beta-CD this ring is oriented toward the secondary rim.