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1.
Artículo en Inglés | MEDLINE | ID: mdl-39453428

RESUMEN

The second-generation myosin activator danicamtiv (DN) has shown improved function compared to the first generation myosin activator omecamtiv mecarbil (OM) in non-failing myocardium by enhancing cardiac force generation but attenuating slowed relaxation. However, whether the functional improvement with DN compared to OM persists in remodeled failing myocardium remain unknown. Therefore, this study aimed to investigate the differential contractile response to myosin activators in non-failing and failing myocardium. Mechanical measurements were performed in detergent-skinned myocardium isolated from donor and failing human hearts. Steady-state force, stretch activation responses, and loaded shortening velocity were analyzed at submaximal [Ca2+] in the absence or presence of 0.5 µmol/L OM or 2 µmol/L DN. The effects of DN and OM on Ca2+-sensitivity of force generation were determined by incubating myocardial preparations at various [Ca2+]. The inherent impairment in force generation and cross-bridge behavior sensitized failing myocardium to the effects of myosin activators. Specifically, increased Ca2+-sensitivity of force generation, slowed rates of cross-bridge recruitment and detachment following acute stretch, slowed loaded shortening velocity, and diminished power output were more prominent following treatment with OM or DN in failing myocardium compared to donor myocardium. Although these effects were less pronounced with DN compared to OM in failing myocardium, DN impaired contractile properties in failing myocardium that were not affected in donor myocardium. Our results indicate that similar to first-generation myosin activators, the DN-induced slowing of cross-bridge kinetics may result in a prolongation of systolic ejection and delayed diastolic relaxation in the heart failure setting.

2.
Artículo en Inglés | MEDLINE | ID: mdl-38773048

RESUMEN

The decision to receive a cardiac implantable electronic device (CIED) represents a challenging experience for patients. However, the majority of previous research has only considered retrospective accounts of patient experiences. This study aimed to use social media data to characterize the information sought by people anticipating or considering CIED implantation and factors that influence their decision-making experiences. A Python-based script was used to collect posts made to a community intended for discussions concerning CIEDs on the social media platform Reddit. Reflexive content analysis was used to analyze the collected data. From 799 posts collected, 101 made by 86 participants were analyzed. The reported median (range) age of participants was 34 (16-67), and most were anticipating or considering a pacemaker. Three overarching categories classified the data: "Use of social media to meet informational and other needs"; "Factors influencing acceptance of the need for implantation"; and "Specific concerns considered during decision-making." Participants anticipating or considering a CIED predominantly sought experiential information. Among asymptomatic participants, doubts were prevalent, with acceptance being an influential factor in decision-making. Healthcare professionals should recognize the informational and emotional needs of prospective CIED patients and tailor support mechanisms to better facilitate their decision-making.

3.
Am J Physiol Heart Circ Physiol ; 325(3): H449-H467, 2023 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-37417875

RESUMEN

Detailed assessments of whole heart mechanics are crucial for understanding the consequences of sarcomere perturbations that lead to cardiomyopathy in mice. Echocardiography offers an accessible and cost-effective method of obtaining metrics of cardiac function, but the most routine imaging and analysis protocols might not identify subtle mechanical deficiencies. This study aims to use advanced echocardiography imaging and analysis techniques to identify previously unappreciated mechanical deficiencies in a mouse model of dilated cardiomyopathy (DCM) before the onset of overt systolic heart failure (HF). Mice lacking muscle LIM protein expression (MLP-/-) were used to model DCM-linked HF pathogenesis. Left ventricular (LV) function of MLP-/- and wild-type (WT) controls were studied at 3, 6, and 10 wk of age using conventional and four-dimensional (4-D) echocardiography, followed by speckle-tracking analysis to assess torsional and strain mechanics. Mice were also studied with RNA-seq. Although 3-wk-old MLP-/- mice showed normal LV ejection fraction (LVEF), these mice displayed abnormal torsional and strain mechanics alongside reduced ß-adrenergic reserve. Transcriptome analysis showed that these defects preceded most molecular markers of HF. However, these markers became upregulated as MLP-/- mice aged and developed overt systolic dysfunction. These findings indicate that subtle deficiencies in LV mechanics, undetected by LVEF and conventional molecular markers, may act as pathogenic stimuli in DCM-linked HF. Using these analyses in future studies will further help connect in vitro measurements of the sarcomere function to whole heart function.NEW & NOTEWORTHY A detailed study of how perturbations to sarcomere proteins impact whole heart mechanics in mouse models is a major yet challenging step in furthering our understanding of cardiovascular pathophysiology. This study uses advanced echocardiographic imaging and analysis techniques to reveal previously unappreciated subclinical whole heart mechanical defects in a mouse model of cardiomyopathy. In doing so, it offers an accessible set of measurements for future studies to use when connecting sarcomere and whole heart function.


Asunto(s)
Cardiomiopatía Dilatada , Insuficiencia Cardíaca , Disfunción Ventricular Izquierda , Ratones , Animales , Cardiomiopatía Dilatada/etiología , Cardiomiopatía Dilatada/genética , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/genética , Ecocardiografía/métodos , Función Ventricular Izquierda/fisiología , Volumen Sistólico/fisiología , Disfunción Ventricular Izquierda/etiología , Disfunción Ventricular Izquierda/genética
4.
J Struct Biol ; 214(2): 107856, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35427781

RESUMEN

INTRODUCTION: The central C4 and C5 domains (C4C5) of cardiac myosin binding protein C (cMyBPC) contain a flexible interdomain linker and a cardiac-isoform specific loop. However, their importance in the functional regulation of cMyBPC has not been extensively studied. METHODS AND RESULTS: We expressed recombinant C4C5 proteins with deleted linker and loop regions and performed biophysical experiments to determine each of their structural and dynamic roles. We show that the linker and C5 loop regions modulate the secondary structure and thermal stability of C4C5. Furthermore, we provide evidence through extended molecular dynamics simulations and principle component analyses that C4C5 can adopt a completely bent or latched conformation. The simulation trajectory and interaction network analyses reveal that the completely bent conformation of C4C5 exhibits a specific pattern of residue-level interactions. Therefore, we propose a "hinge-and-latch" mechanism where the linker allows a great degree of flexibility and bending, while the loop aids in achieving a completely bent and latched conformation. Although this may be one of many bent positions that C4C5 can adopt, we illustrate for the first time in molecular detail that this type of large scale conformational change can occur in the central domains of cMyBPC. CONCLUSIONS: Our hinge-and-latch mechanism demonstrates that the linker and loop regions participate in dynamic modulation of cMyBPC's motion and global conformation. These structural and dynamic features may contribute to muscle isoform-specific regulation of actomyosin activity, and have potential implications regarding its ability to propagate or retract cMyBPC's regulatory N-terminal domains.


Asunto(s)
Citoesqueleto de Actina , Simulación de Dinámica Molecular , Citoesqueleto de Actina/química , Conformación Proteica , Estructura Secundaria de Proteína
5.
Eur Respir J ; 60(6)2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-35777770

RESUMEN

BACKGROUND: The relationship between objectively measured cough and type 2 (T2) biomarkers and other measures of asthma control and severity is poorly understood. The objective of this study was to assess the relationship between objective and subjective cough measurement tools and clinical biomarkers of asthma. METHODS: Patients with severe asthma and mild-to-moderate asthma completed validated asthma and cough-related measurement tools (including ambulatory cough monitoring) and measurement of spirometry and T2 biomarkers (exhaled nitric oxide fraction (F ENO) and peripheral blood eosinophil count). Patients were classified according to T2 status based on T2-low (F ENO <20 ppb and peripheral blood eosinophils <150 cells·µL-1), T2-intermediate (F ENO ≥20 ppb or peripheral blood eosinophils ≥150 cells·µL-1) or T2-high (F ENO ≥20 ppb and peripheral blood eosinophils ≥150 cells·µL-1). RESULTS: 61 patients completed the study measurements (42 severe asthma and 19 mild-to-moderate asthma). Patients with severe asthma had higher rates of cough than those with mild-to-moderate asthma in terms of total 24-h cough counts (geometric mean±sd 170.3±2.7 versus 60.8±4.1; p=0.002) and cough frequency (geometric mean±sd 7.1±2.7 versus 2.5±4.1 coughs·h-1; p=0.002). T2-low patients with severe asthma had significantly lower 24-h cough frequency compared with T2-intermediate and T2-high patients. CONCLUSIONS: In patients with low biomarkers of T2 inflammation, cough frequency measurements were not elevated, suggesting that the mechanism for cough in asthma is underlying T2 eosinophilic inflammation and the logical first step for treating cough in asthma may be to achieve adequate suppression of T2 inflammation with currently available therapies.


Asunto(s)
Asma , Tos , Humanos , Asma/complicaciones , Asma/diagnóstico , Eosinófilos , Inflamación , Biomarcadores
6.
Lung ; 200(2): 169-178, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35416544

RESUMEN

BACKGROUND: The extent to which objective and subjective tools has been used to measure the characteristics and burden of cough in patients with asthma has not been reported. OBJECTIVE: To review the large and extensive body of literature in asthma with the specific hypothesis that the characteristics of cough and clinical impact in this disease has only occasionally been studied. METHODS: For this systematic review, we searched EMBASE and MEDLINE databases using a combination of MeSH terms for "cough" and "asthma" for studies published up to and including end of August 2021. Studies included for analysis were confined to those undertaken in adult patients (≥ 18 years) with asthma of any severity where any tool or method to specifically measure cough was employed. RESULTS: Of 12,090 citations identified after our initial search, 112 full-text articles met criteria for inclusion in our analysis. We found that a broad range of objective and subjective measures have been used albeit with a lack of consistency between studies. Clinically important levels of cough associated with impaired health status were identified in patients with asthma. CONCLUSION: Although cough is a common symptom in asthma, the clinical features and accompanying healthcare burden have been studied infrequently. In studies where cough was measured, the methods employed varied considerably. A more consistent use of cough-specific measurement tools is required to better determine the nature and burden of cough in asthma.


Asunto(s)
Asma , Tos , Adulto , Asma/complicaciones , Asma/diagnóstico , Tos/complicaciones , Tos/etiología , Servicios de Salud , Estado de Salud , Humanos
7.
PLoS Pathog ; 15(6): e1007848, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-31181121

RESUMEN

Streptococcus agalactiae (Group B Streptococcus, GBS) normally colonizes healthy adults but can cause invasive disease, such as meningitis, in the newborn. To gain access to the central nervous system, GBS must interact with and penetrate brain or meningeal blood vessels; however, the exact mechanisms are still being elucidated. Here, we investigate the contribution of BspC, an antigen I/II family adhesin, to the pathogenesis of GBS meningitis. Disruption of the bspC gene reduced GBS adherence to human cerebral microvascular endothelial cells (hCMEC), while heterologous expression of BspC in non-adherent Lactococcus lactis conferred bacterial attachment. In a murine model of hematogenous meningitis, mice infected with ΔbspC mutants exhibited lower mortality as well as decreased brain bacterial counts and inflammatory infiltrate compared to mice infected with WT GBS strains. Further, BspC was both necessary and sufficient to induce neutrophil chemokine expression. We determined that BspC interacts with the host cytoskeleton component vimentin and confirmed this interaction using a bacterial two-hybrid assay, microscale thermophoresis, immunofluorescent staining, and imaging flow cytometry. Vimentin null mice were protected from WT GBS infection and also exhibited less inflammatory cytokine production in brain tissue. These results suggest that BspC and the vimentin interaction is critical for the pathogenesis of GBS meningitis.


Asunto(s)
Antígenos Bacterianos/metabolismo , Proteínas Bacterianas/metabolismo , Encéfalo/metabolismo , Meningitis Bacterianas/metabolismo , Infecciones Estreptocócicas/metabolismo , Streptococcus agalactiae/metabolismo , Vimentina/metabolismo , Animales , Antígenos Bacterianos/genética , Proteínas Bacterianas/genética , Encéfalo/irrigación sanguínea , Encéfalo/microbiología , Encéfalo/patología , Endotelio Vascular , Células HeLa , Humanos , Masculino , Meningitis Bacterianas/genética , Meningitis Bacterianas/patología , Ratones , Ratones Mutantes , Ovinos , Infecciones Estreptocócicas/genética , Infecciones Estreptocócicas/patología , Streptococcus agalactiae/genética , Streptococcus agalactiae/patogenicidad , Vimentina/genética
8.
Arch Biochem Biophys ; 662: 213-218, 2019 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-30576628

RESUMEN

Current inotropic therapies improve systolic function in heart failure patients but also elicit undesirable side effects such as arrhythmias and increased intracellular Ca2+ transients. In order to maintain myocyte Ca2+ homeostasis, the increased cytosolic Ca2+ needs to be actively transported back to sarcoplasmic reticulum leading to depleted ATP reserves. Thus, an emerging approach is to design sarcomere-based treatments to correct impaired contractility via a direct and allosteric modulation of myosin's intrinsic force-generating behavior -a concept that potentially avoids the "off-target" effects. To achieve this goal, various biophysical approaches are utilized to investigate the mechanistic impact of sarcomeric modulators but information derived from diverse approaches is not fully integrated into therapeutic applications. This is in part due to the lack of information that provides a coherent connecting link between biophysical data to in vivo function. Hence, our ability to clearly discern the drug-mediated impact on whole-heart function is diminished. Reducing this translational barrier can significantly accelerate clinical progress related to sarcomere-based therapies by optimizing drug-dosing and treatment duration protocols based on information obtained from biophysical studies. Therefore, we attempt to link biophysical mechanical measurements obtained in isolated cardiac muscle and in vivo contractile function.


Asunto(s)
Contracción Miocárdica/fisiología , Miocardio , Investigación Biomédica Traslacional , Animales , Cardiotónicos/farmacología , Cardiotónicos/uso terapéutico , Insuficiencia Cardíaca/tratamiento farmacológico , Insuficiencia Cardíaca/fisiopatología , Humanos , Contracción Miocárdica/efectos de los fármacos , Sarcómeros/fisiología
9.
MMWR Morb Mortal Wkly Rep ; 68(47): 1089-1095, 2019 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-31774743

RESUMEN

Human immunodeficiency virus (HIV) case-based surveillance (CBS) systematically and continuously collects available demographic and health event data (sentinel events*) about persons with HIV infection from diagnosis and, if available, throughout routine clinical care until death, to characterize HIV epidemics and guide program improvement (1,2). Surveillance signals such as high viral load, mortality, or recent HIV infection can be used for rapid public health action. To date, few standardized assessments have been conducted to describe HIV CBS systems globally (3,4). For this assessment, a survey was disseminated during May-July 2019 to all U.S. President's Emergency Plan for AIDS Relief (PEPFAR)-supported countries with CDC presence† (46) to describe CBS implementation and identify facilitators and barriers. Among the 39 (85%) countries that responded,§ 20 (51%) have implemented CBS, 15 (38%) were planning implementation, and four (10%)¶ had no plans for implementation. All countries with CBS reported capturing information at the point of diagnosis, and 85% captured sentinel event data. The most common characteristic (75% of implementation countries) that facilitated implementation was using a health information system for CBS. Barriers to CBS implementation included lack of country policies/guidance on mandated reporting of HIV and on CBS, lack of unique identifiers to match and deduplicate patient-level data, and lack of data security standards. Although most surveyed countries reported implementing or planning for implementation of CBS, these barriers need to be addressed to implement effective HIV CBS that can inform the national response to the HIV epidemic.


Asunto(s)
Salud Global/economía , Infecciones por VIH/epidemiología , Vigilancia de la Población , Países en Desarrollo , Humanos , Cooperación Internacional , Estados Unidos
10.
Proc Natl Acad Sci U S A ; 113(44): 12490-12495, 2016 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-27791060

RESUMEN

Despite their relative simplicity, bacteria have complex anatomy at the subcellular level. At the cell poles of Caulobacter crescentus, a 177-amino acid (aa) protein called PopZ self-assembles into 3D polymeric superstructures. Remarkably, we find that this assemblage interacts directly with at least eight different proteins, which are involved in cell cycle regulation and chromosome segregation. The binding determinants within PopZ include 24 aa at the N terminus, a 32-aa region near the C-terminal homo-oligomeric assembly domain, and portions of an intervening linker region. Together, the N-terminal 133 aa of PopZ are sufficient for interacting with all binding partners, even in the absence of homo-oligomeric assembly. Structural analysis of this region revealed that it is intrinsically disordered, similar to p53 and other hub proteins that organize complex signaling networks in eukaryotic cells. Through live-cell photobleaching, we find rapid binding kinetics between PopZ and its partners, suggesting many pole-localized proteins become concentrated at cell poles through rapid cycles of binding and unbinding within the PopZ scaffold. We conclude that some bacteria, similar to their eukaryotic counterparts, use intrinsically disordered hub proteins for network assembly and subcellular organization.


Asunto(s)
Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Caulobacter crescentus/metabolismo , Proteínas Intrínsecamente Desordenadas/metabolismo , Multimerización de Proteína , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Caulobacter crescentus/genética , División Celular , Proteínas Intrínsecamente Desordenadas/genética , Cinética , Espectroscopía de Resonancia Magnética , Microscopía Fluorescente , Unión Proteica
11.
Brain Behav Immun ; 64: 124-139, 2017 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-28412141

RESUMEN

A history of repeated concussion has been linked to the later development of neurodegeneration, which is associated with the accumulation of hyperphosphorylated tau and the development of behavioral deficits. However, the role that exogenous factors, such as immune activation, may play in the development of neurodegeneration following repeated mild traumatic brain injury (rmTBI) has not yet been explored. To investigate, male Sprague-Dawley rats were administered three mTBIs 5days apart using the diffuse impact-acceleration model to generate ∼100G. Sham animals underwent surgery only. At 1 or 5days following the last injury rats were given the TLR4 agonist, lipopolysaccharide (LPS, 0.1mg/kg), or saline. TLR4 activation had differential effects following rmTBI depending on the timing of activation. When given at 1day post-injury, LPS acutely activated microglia, but decreased production of pro-inflammatory cytokines like IL-6. This was associated with a reduction in neuronal injury, both acutely, with a restoration of levels of myelin basic protein (MBP), and chronically, preventing a loss of both MBP and PSD-95. Furthermore, these animals did not develop behavioral deficits with no changes in locomotion, anxiety, depressive-like behavior or cognition at 3months post-injury. Conversely, when LPS was given at 5days post-injury, it was associated acutely with an increase in pro-inflammatory cytokine production, with an exacerbation of neuronal damage and increased levels of aggregated and phosphorylated tau. At 3months post-injury, there was a slight exacerbation of functional deficits, particularly in cognition and depressive-like behavior. This highlights the complexity of the immune response following rmTBI and the need to understand how a history of rmTBI interacts with environmental factors to influence the potential to develop later neurodegeneration.


Asunto(s)
Conmoción Encefálica/inmunología , Encefalitis/inmunología , Receptor Toll-Like 4/inmunología , Animales , Conmoción Encefálica/complicaciones , Conmoción Encefálica/metabolismo , Encefalitis/complicaciones , Encefalitis/metabolismo , Conducta de Enfermedad , Mediadores de Inflamación/inmunología , Mediadores de Inflamación/metabolismo , Lipopolisacáridos/administración & dosificación , Masculino , Microglía/efectos de los fármacos , Microglía/metabolismo , Actividad Motora/efectos de los fármacos , Fosforilación , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacos , Receptor Toll-Like 4/agonistas , Receptor Toll-Like 4/metabolismo , Proteínas tau/metabolismo
12.
Eur Child Adolesc Psychiatry ; 26(1): 25-34, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27207089

RESUMEN

The causal beliefs which adults have regarding their mental health difficulties have been linked to help-seeking behaviour, treatment preferences, and the outcome of therapy; yet, the topic remains a relatively unexplored one in the adolescent literature. This exploratory study aims to explore the causal beliefs regarding depression among a sample of clinically referred adolescents. Seventy seven adolescents, aged between 11 and 17, all diagnosed with moderate to severe depression, were interviewed using a semi-structured interview schedule, at the beginning of their participation in a randomised controlled trial. Data were analysed qualitatively using framework analysis. The study identified three themes related to causal beliefs: (1) bewilderment about why they were depressed; (2) depression as a result of rejection, victimisation, and stress; and (3) something inside is to blame. Although some adolescents struggled to identify the causes of their depression, many identified stressful life experiences as the cause of their current depression. They also tended to emphasise their own negative ways of interpreting those events, and some believed that their depression was caused by something inside them. Adolescents' causal beliefs are likely to have implications for the way they seek help and engage in treatment, making it important to understand how adolescents understand their difficulties.


Asunto(s)
Conducta del Adolescente/psicología , Cultura , Depresión/diagnóstico , Depresión/psicología , Servicios de Salud Mental , Derivación y Consulta , Adolescente , Niño , Depresión/terapia , Femenino , Humanos , Entrevista Psicológica/métodos , Masculino , Estrés Psicológico/psicología
13.
Psychother Res ; 26(1): 11-21, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-25372575

RESUMEN

OBJECTIVE: To explore hopes and expectations for therapy among a clinical population of depressed adolescents. METHOD: As part of a randomized clinical trial, 77 adolescents aged 11-17, with moderate to severe depression, were interviewed using a semi-structured interview schedule. The interviews were analysed qualitatively using framework analysis. RESULTS: The findings are reported around five themes: "the difficulty of imagining what will happen in therapy," "the 'talking cure,'" "the therapist as doctor," "therapy as a relationship," and "regaining the old self or developing new capacities." CONCLUSIONS: Differing expectations are likely to have implications for the way young people engage with treatment, and failure to identify these expectations may lead to a risk of treatment breakdown.


Asunto(s)
Conducta del Adolescente/psicología , Depresión/psicología , Trastorno Depresivo/psicología , Entrevista Psicológica , Aceptación de la Atención de Salud/psicología , Adolescente , Niño , Femenino , Humanos , Masculino , Psicoterapia , Investigación Cualitativa , Ensayos Clínicos Controlados Aleatorios como Asunto
14.
Hippocampus ; 23(12): 1162-78, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23749378

RESUMEN

Three cohorts of rats with extensive hippocampal lesions received multiple tests to examine the relationships between particular forms of associative learning and an influential account of hippocampal function (the cognitive map hypothesis). Hippocampal lesions spared both the ability to discriminate two different digging media and to discriminate two different room locations in a go/no-go task when each location was approached from a single direction. Hippocampal lesions had, however, differential effects on a more complex task (biconditional discrimination) where the correct response was signaled by the presence or absence of specific cues. For all biconditional tasks, digging in one medium (A) was rewarded in the presence of cue C, while digging in medium B was rewarded in the presences of cue D. Such biconditional tasks are "configural" as no individual cue or element predicts the solution (AC+, AD-, BD+, and BC-). When proximal context cues signaled the correct digging choice, biconditional learning was seemingly unaffected by hippocampal lesions. Severe deficits occurred, however, when the correct digging choice was signaled by distal room cues. Also, impaired was the ability to discriminate two locations when each location was approached from two directions. A task demand that predicted those tasks impaired by hippocampal damage was the need to combine specific cues with their relative spatial positions ("structural learning"). This ability makes it possible to distinguish the same cues set in different spatial arrays. Thus, the hippocampus appears necessary for configural discriminations involving structure, discriminations that potentially underlie the creation of cognitive maps.


Asunto(s)
Aprendizaje por Asociación/fisiología , Discriminación en Psicología , Hipocampo/fisiología , Inhibición Psicológica , Percepción Espacial/fisiología , Análisis de Varianza , Animales , Conducta de Elección/fisiología , Estudios de Cohortes , Señales (Psicología) , Hipocampo/lesiones , Masculino , Aprendizaje por Laberinto , Pruebas Neuropsicológicas , Ratas
15.
J Phys Chem A ; 117(19): 4035-43, 2013 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-23594255

RESUMEN

Combined high-resolution spectroscopic, electron-diffraction, and quantum theoretical methods are particularly advantageous for small molecules of high symmetry and can yield accurate structures that reveal subtle effects of electron delocalization on molecular bonds. The smallest of the radialene compounds, trimethylenecyclopropane, [3]-radialene, has been synthesized and examined by these methods. The first high-resolution infrared spectra have been obtained for this molecule of D3h symmetry, leading to an accurate B0 rotational constant value of 0.1378629(8) cm(-1), within 0.5% of the value obtained from electronic structure calculations (density functional theory (DFT) B3LYP/cc-pVTZ). This result is employed in an analysis of electron-diffraction data to obtain the rz bond lengths (in Å): C-H = 1.072(17), C-C = 1.437(4), and C═C = 1.330(4). The results indicate that the effects of rehybridization and π-electron delocalization affects each result in a shortening of about 0.05 Å for the C-C bond in radialene compared to ethane. The analysis does not lead to an accurate value of the HCH angle; however, from comparisons of theoretical and experimental angles for similar compounds, the theoretical prediction of 117.5° is believed to be reliable to within 2°.

17.
J Am Heart Assoc ; 12(20): e030682, 2023 10 17.
Artículo en Inglés | MEDLINE | ID: mdl-37804193

RESUMEN

Background Omecamtiv mecarbil (OM) and danicamtiv both increase myocardial force output by selectively activating myosin within the cardiac sarcomere. Enhanced force generation is presumably due to an increase in the total number of myosin heads bound to the actin filament; however, detailed comparisons of the molecular mechanisms of OM and danicamtiv are lacking. Methods and Results The effect of OM and danicamtiv on Ca2+ sensitivity of force generation was analyzed by exposing chemically skinned myocardial samples to a series of increasing Ca2+ solutions. The results showed that OM significantly increased Ca2+ sensitivity of force generation, whereas danicamtiv showed similar Ca2+ sensitivity of force generation to untreated preparations. A direct comparison of OM and danicamtiv on dynamic cross-bridge behavior was performed at a concentration that produced a similar force increase when normalized to predrug levels at submaximal force (pCa 6.1). Both OM and danicamtiv-treated groups slowed the rates of cross-bridge detachment from the strongly bound state and cross-bridge recruitment into the force-producing state. Notably, the significant OM-induced prolongation in the time to reach force relaxation and subsequent commencement of force generation following rapid stretch was dramatically reduced in danicamtiv-treated myocardium. Conclusions This is the first study to directly compare the effects of OM and danicamtiv on cross-bridge kinetics. At a similar level of force enhancement, danicamtiv had a less pronounced effect on the slowing of cross-bridge kinetics and, therefore, may provide a similar improvement in systolic function as OM without excessively prolonging systolic ejection time and slowing cardiac relaxation facilitating diastolic filling at the whole-organ level.


Asunto(s)
Contracción Miocárdica , Miocardio , Humanos , Miocardio/metabolismo , Cardiotónicos/farmacología , Corazón , Miosinas/metabolismo , Calcio/metabolismo
18.
ERJ Open Res ; 9(1)2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36605903

RESUMEN

Background: Asthma symptoms adversely impact quality of life in particular in those with poor disease control. Commonly used patient-reported measures for asthma used to assess asthma control often inadequately capture the impact of cough, despite evidence that cough is one of the most bothersome symptoms for patients with asthma. This study aims to improve our understanding of how patients with asthma perceive cough to better understand its clinical impact. Methods: A discrete choice experiment (DCE) was performed in two distinct adult asthma populations; those with severe asthma as defined by Global Initiative for Asthma (GINA) step 4/5 classification and those with moderate asthma (a GINA steps 2 or 3 classification of asthma severity). Results: Choices were highly dominated by the cough attribute in the symptoms complexes; 48.4% of patients with severe asthma and 31.3% with moderate asthma consistently chose the alternative with the lowest level of cough. Furthermore, cough predominance was found to be significantly associated with severity of asthma (p=0.047). Patients with moderate asthma were not willing to accept any additional symptoms to reduce cough from severe to mild. However, these patients were willing to accept mild breathlessness, mild sleep disturbance, severe chest tightness and severe wheezing to remove coughing altogether. Conclusions: Patients with asthma prefer to have less cough and are willing to accept greater levels of other symptoms to achieve this. Additionally, asthma severity may influence an individual's perception of their symptoms; cough is a more important symptom for patients with severe asthma than those with a milder disease.

19.
J Gen Physiol ; 155(6)2023 06 05.
Artículo en Inglés | MEDLINE | ID: mdl-37067542

RESUMEN

Cardiac myosin binding protein C (cMyBPC) is an 11-domain sarcomeric protein (C0-C10) integral to cardiac muscle regulation. In vitro studies have demonstrated potential functional roles for regions beyond the N-terminus. However, the in vivo contributions of these domains are mostly unknown. Therefore, we examined the in vivo consequences of expression of N-terminal truncated cMyBPC (C3C10). Neonatal cMyBPC-/- mice were injected with AAV9-full length (FL), C3C10 cMyBPC, or saline, and echocardiography was performed 6 wk after injection. We then isolated skinned myocardium from virus-treated hearts and performed mechanical experiments. Our results show that expression of C3C10 cMyBPC in cMyBPC-/- mice resulted in a 28% increase in systolic ejection fraction compared to saline-injected cMyBPC-/- mice and a 25% decrease in left ventricle mass-to-body weight ratio. However, unlike expression of FL cMyBPC, there was no prolongation of ejection time compared to saline-injected mice. In vitro mechanical experiments demonstrated that functional improvements in cMyBPC-/- mice expressing C3C10 were primarily due to a 35% reduction in the rate of cross-bridge recruitment at submaximal Ca2+ concentrations when compared to hearts from saline-injected cMyBPC-/- mice. However, unlike the expression of FL cMyBPC, there was no change in the rate of cross-bridge detachment when compared to saline-injected mice. Our data demonstrate that regions of cMyBPC beyond the N-terminus are important for in vivo cardiac function, and have divergent effects on cross-bridge behavior. Elucidating the molecular mechanisms of cMyBPC region-specific function could allow for development of targeted approaches to manipulate specific aspects of cardiac contractile function.


Asunto(s)
Proteínas Portadoras , Miocardio , Ratones , Animales , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Miocardio/metabolismo , Corazón , Sarcómeros/metabolismo , Contracción Miocárdica
20.
ERJ Open Res ; 9(3)2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37260457

RESUMEN

Introduction: Severe asthma is a complex, multidimensional disease. Optimal treatment, adherence and outcomes require shared decision-making, rooted in mutual understanding between patient and clinician. This study used a novel, patient-centred approach to examine the most bothersome aspects of severe asthma to patients, as seen from both perspectives in asthma registries. Methods: Across seven countries, 126 patients with severe asthma completed an open-ended survey regarding most the bothersome aspect(s) of their asthma. Patients' responses were linked with their treating clinician who also completed a free-text survey about each patient's most bothersome aspect(s). Responses were coded using content analysis, and patient and clinician responses were compared. Finally, asthma registries that are part of the SHARP (Severe Heterogeneous Asthma Research collaboration, Patient-centred) Clinical Research Collaboration were examined to see the extent to which they reflected the most bothersome aspects reported by patients. Results: 88 codes and 10 themes were identified. Clinicians were more focused on direct physical symptoms and were less focused on "holistic" aspects such as the effort required to self-manage the disease. Clinicians accurately identified a most bothersome symptom for 29% of patients. Agreement was particularly low with younger patients and those using oral corticosteroids infrequently. In asthma registries, patient aspects were predominantly represented in questionnaires. Conclusions: Results demonstrated different perspectives and priorities between patients and clinicians, with clinicians more focused on physical aspects. These differences must be considered when treating individual patients, and within multidisciplinary treatment teams. The use of questionnaires that include multifaceted aspects of disease may result in improved asthma research.

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