Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 290
Filtrar
Más filtros

Banco de datos
Tipo del documento
Intervalo de año de publicación
1.
J Mol Cell Cardiol ; 193: 11-24, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38797242

RESUMEN

Atrial fibrillation (AF) is the most common cardiac rhythm disorder, often occurring in the setting of atrial distension and elevated myocardialstretch. While various mechano-electrochemical signal transduction pathways have been linked to AF development and progression, the underlying molecular mechanisms remain poorly understood, hampering AF therapies. In this review, we describe different aspects of stretch-induced electro-anatomical remodeling as seen in animal models and in patients with AF. Specifically, we focus on cellular and molecular mechanisms that are responsible for mechano-electrochemical signal transduction and the development of ectopic beats triggering AF from pulmonary veins, the most common source of paroxysmal AF. Furthermore, we describe structural changes caused by stretch occurring before and shortly after the onset of AF as well as during AF progression, contributing to longstanding forms of AF. We also propose mechanical stretch as a new dimension to the concept "AF begets AF", in addition to underlying diseases. Finally, we discuss the mechanisms of these electro-anatomical alterations in a search for potential therapeutic strategies and the development of novel antiarrhythmic drugs targeted at the components of mechano-electrochemical signal transduction not only in cardiac myocytes, but also in cardiac non-myocyte cells.


Asunto(s)
Fibrilación Atrial , Humanos , Animales , Fibrilación Atrial/fisiopatología , Fibrilación Atrial/metabolismo , Fibrilación Atrial/patología , Remodelación Atrial , Atrios Cardíacos/fisiopatología , Atrios Cardíacos/patología , Atrios Cardíacos/metabolismo , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Transducción de Señal , Venas Pulmonares/patología , Venas Pulmonares/metabolismo , Venas Pulmonares/fisiopatología , Fenómenos Electrofisiológicos
2.
Opt Lett ; 49(8): 2065-2068, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38621077

RESUMEN

We report ultrabroadband two-dimensional electronic spectroscopy (2D ES) measurements obtained in the pump-probe geometry using conventional optics. A phase-stabilized Michelson interferometer provides the pump-pulse delay interval, τ1, necessary to obtain the excitation-frequency dimension. Spectral resolution of the probe beam provides the detection-frequency dimension, ω3. The interferometer incorporates active phase stabilization via a piezo stage and feedback from interference of a continuous-wave reference laser detected in quadrature. To demonstrate the method, we measured a well-characterized laser dye sample and obtained the known peak structure. The vibronic peaks are modulated as a function of the waiting time, τ2, by vibrational wave packets. The interferometer simplifies ultrabroadband 2D ES measurements and analysis.

3.
FASEB J ; 37(1): e22720, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36542473

RESUMEN

Cancer survivors suffer impairments in skeletal muscle in terms of reduced mass and function. Interestingly, human skeletal muscle possesses an epigenetic memory of earlier stimuli, such as exercise. Long-term retention of epigenetic changes in skeletal muscle following cancer survival and/or exercise training has not yet been studied. We, therefore, investigated genome-wide DNA methylation (methylome) in skeletal muscle following a 5-month, 3/week aerobic-training intervention in breast cancer survivors 10-14 years after diagnosis and treatment. These results were compared to breast cancer survivors who remained untrained and to age-matched controls with no history of cancer, who undertook the same training intervention. Skeletal muscle biopsies were obtained from 23 females before(pre) and after(post) the 5-month training period. InfiniumEPIC 850K DNA methylation arrays and RT-PCR for gene expression were performed. The breast cancer survivors displayed a significant retention of increased DNA methylation (i.e., hypermethylation) at a larger number of differentially methylated positions (DMPs) compared with healthy age-matched controls pre training. Training in cancer survivors led to an exaggerated number of DMPs with a hypermethylated signature occurring at non-regulatory regions compared with training in healthy age-matched controls. However, the opposite occurred in important gene regulatory regions, where training in cancer survivors elicited a considerable reduction in methylation (i.e., hypomethylation) in 99% of the DMPs located in CpG islands within promoter regions. Importantly, training was able to reverse the hypermethylation identified in cancer survivors back toward a hypomethylated signature that was observed pre training in healthy age-matched controls at 300 (out of 881) of these island/promoter-associated CpGs. Pathway enrichment analysis identified training in cancer survivors evoked a predominantly hypomethylated signature in pathways associated with cell cycle, DNA replication/repair, transcription, translation, mTOR signaling, and the proteosome. Differentially methylated region (DMR) analysis also identified genes: BAG1, BTG2, CHP1, KIFC1, MKL2, MTR, PEX11B, POLD2, S100A6, SNORD104, and SPG7 as hypermethylated in breast cancer survivors, with training reversing these CpG island/promoter-associated DMRs toward a hypomethylated signature. Training also elicited a largely different epigenetic response in healthy individuals than that observed in cancer survivors, with very few overlapping changes. Only one gene, SIRT2, was identified as having altered methylation in cancer survivors at baseline and after training in both the cancer survivors and healthy controls. Overall, human skeletal muscle may retain a hypermethylated signature as long as 10-14 years after breast cancer treatment/survival. Five months of aerobic training reset the skeletal muscle methylome toward signatures identified in healthy age-matched individuals in gene regulatory regions.


Asunto(s)
Neoplasias de la Mama , Proteínas Inmediatas-Precoces , Femenino , Humanos , Epigenoma , Neoplasias de la Mama/genética , Neoplasias de la Mama/terapia , Metilación de ADN , Epigénesis Genética , Ejercicio Físico/fisiología , Músculo Esquelético/fisiología , Islas de CpG/genética , Proteínas Inmediatas-Precoces/genética , Proteínas Supresoras de Tumor/genética
4.
J Chem Phys ; 160(16)2024 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-38647298

RESUMEN

When used as pump pulses in transient absorption spectroscopy measurements, femtosecond laser pulses can produce oscillatory signals known as quantum beats. The quantum beats arise from coherent superpositions of the states of the sample and are best studied in the Fourier domain using Femtosecond Coherence Spectroscopy (FCS), which consists of one-dimensional amplitude and phase plots of a specified oscillation frequency as a function of the detection frequency. Prior works have shown ubiquitous amplitude nodes and π phase shifts in FCS from excited-state vibrational wavepackets in monomer samples. However, the FCS arising from vibronic-exciton states in molecular aggregates have not been studied theoretically. Here, we use a model of vibronic-exciton states in molecular dimers based on displaced harmonic oscillators to simulate FCS for dimers in two important cases. Simulations reveal distinct spectral signatures of excited-state vibronic-exciton coherences in molecular dimers that may be used to distinguish them from monomer vibrational coherences. A salient result is that, for certain relative orientations of the transition dipoles, the key resonance condition between the electronic coupling and the frequency of the vibrational mode may yield strong enhancement of the quantum-beat amplitude and, perhaps, also cause a significant decrease of the oscillation frequency to a value far lower than the vibrational frequency. Future studies using these results will lead to new insights into the excited-state coherences generated in photosynthetic pigment-protein complexes.

5.
J Mol Cell Cardiol ; 184: 75-87, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37805125

RESUMEN

Caveolae are tiny invaginations in the sarcolemma that buffer extra membrane and contribute to mechanical regulation of cellular function. While the role of caveolae in membrane mechanosensation has been studied predominantly in non-cardiomyocyte cells, caveolae contribution to cardiac mechanotransduction remains elusive. Here, we studied the role of caveolae in the regulation of Ca2+ signaling in atrial cardiomyocytes. In Langendorff-perfused mouse hearts, atrial pressure/volume overload stretched atrial myocytes and decreased caveolae density. In isolated cells, caveolae were disrupted through hypotonic challenge that induced a temporal (<10 min) augmentation of Ca2+ transients and caused a rise in Ca2+ spark activity. Similar changes in Ca2+ signaling were observed after chemical (methyl-ß-cyclodextrin) and genetic ablation of caveolae in cardiac-specific conditional caveolin-3 knock-out mice. Acute disruption of caveolae, both mechanical and chemical, led to the elevation of cAMP level in the cell interior, and cAMP-mediated augmentation of protein kinase A (PKA)-phosphorylated ryanodine receptors (at Ser2030 and Ser2808). Caveolae-mediated stimulatory effects on Ca2+ signaling were abolished via inhibition of cAMP production by adenyl cyclase antagonists MDL12330 and SQ22536, or reduction of PKA activity by H-89. A compartmentalized mathematical model of mouse atrial myocytes linked the observed changes to a microdomain-specific decrease in phosphodiesterase activity, which disrupted cAMP signaling and augmented PKA activity. Our findings add a new dimension to cardiac mechanobiology and highlight caveolae-associated cAMP/PKA-mediated phosphorylation of Ca2+ handling proteins as a novel component of mechano-chemical feedback in atrial myocytes.


Asunto(s)
Fibrilación Atrial , Miocitos Cardíacos , Ratones , Animales , Miocitos Cardíacos/metabolismo , Caveolas/metabolismo , Mecanotransducción Celular , Fibrilación Atrial/metabolismo , AMP Cíclico/metabolismo , Transducción de Señal/fisiología
6.
Am J Physiol Cell Physiol ; 324(6): C1274-C1294, 2023 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-37154489

RESUMEN

Skeletal muscle memory is an exciting phenomenon gaining significant traction across several scientific communities, among exercise practitioners, and the public. Research has demonstrated that skeletal muscle tissue can be "primed" by earlier positive encounters with exercise training that can enhance adaptation to later retraining, even following significant periods of exercise cessation or detraining. This review will describe and discuss the most recent research investigating the underlying mechanisms of skeletal muscle memory: 1) "cellular" muscle memory and, 2) "epigenetic" muscle memory, as well as emerging evidence of how these theories may work in synergy. We will discuss both "positive" and "negative" muscle memory and highlight the importance of investigating muscle memory for optimizing exercise interventions and training programs as well as the development of therapeutic strategies for counteracting muscle wasting conditions and age-related muscle loss. Finally, important directions emerging in the field will be highlighted to advance the next generation of studies in skeletal muscle memory research into the future.


Asunto(s)
Ejercicio Físico , Músculo Esquelético , Humanos , Músculo Esquelético/fisiología , Ejercicio Físico/fisiología , Atrofia Muscular , Adaptación Fisiológica , Células Musculares
7.
J Physiol ; 2023 Oct 27.
Artículo en Inglés | MEDLINE | ID: mdl-37889115

RESUMEN

Cardiovascular disease is the leading cause of death in the USA and is known to be exacerbated by elevated mechanical stress from hypertension. Caveolae are plasma membrane structures that buffer mechanical stress but have been found to be reduced in pathological conditions associated with chronically stretched myocardium. To explore the physiological implications of the loss of caveolae, we used human engineered cardiac tissue (ECT) constructs, composed of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes and hiPSC-derived cardiac fibroblasts, to develop a long-term cyclic stretch protocol that recapitulates the effects of hypertension on caveolae expression, membrane tension, and the ß-adrenergic response. Leveraging this new stretch protocol, we identified neutral sphingomyelinases (nSMase) as mechanoregulated mediators of caveolae loss, ceramide production and the blunted ß-adrenergic response in this human cardiac model. Specifically, in our ECT model, nSMase inhibition via GW4869 prevented stretch-induced loss of caveolae-like structures, mitigated nSMase-dependent ceramide production, and maintained the ECT contractile kinetic response to isoprenaline. These findings are correlated with a blood lipidomic analysis in middle-aged and older adults, which revealed an increase of the circulating levels of ceramides in adults with hypertension. Furthermore, we found that conduction slowing from increased pressure loading in mouse left ventricle was abolished in the context of nSMase inhibition. Collectively, these findings identify nSMase as a potent drug target for mitigating stretch-induced effects on cardiac function. KEY POINTS: We have developed a new stretch protocol for human engineered cardiac tissue that recapitulates changes in plasma membrane morphology observed in animal models of pressure/volume overload. Stretch of engineered cardiac tissue induces activation of neutral sphingomyelinase (nSMase), generation of ceramide, and disassembly of caveolae. Activation of nSMase blunts cardiac ß-adrenergic contractile kinetics and mediates stretch-induced slowing of conduction and upstroke velocity. Circulating ceramides are increased in adults with hypertension, highlighting the clinical relevance of stretch-induced nSMase activity.

8.
Am J Physiol Endocrinol Metab ; 324(5): E437-E448, 2023 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-37018654

RESUMEN

We aimed to investigate the human skeletal muscle (SkM) DNA methylome after exercise in low-carbohydrate (CHO) energy-balance (with high-fat) conditions compared with exercise in low-CHO energy-deficit (with low-fat) conditions. The objective was to identify novel epigenetically regulated genes and pathways associated with "train-low sleep-low" paradigms. The sleep-low conditions included nine males that cycled to deplete muscle glycogen while reaching a set energy expenditure. Postexercise, low-CHO meals (protein matched) completely replaced (using high fat) or only partially replaced (low fat) the energy expended. The following morning, resting baseline biopsies were taken and the participants then undertook 75 minutes of cycling exercise, with skeletal muscle biopsies collected 30 minutes and 3.5 hours postexercise. Discovery of genome-wide DNA methylation was undertaken using Illumina EPIC arrays, and targeted gene expression analysis was conducted by quantitative RT-PCR. At baseline, participants under energy balance (high fat) demonstrated a predominantly hypermethylated (60%) profile across the genome compared to energy-deficit low-fat conditions. However, postexercise performed in energy balance (with high fat) elicited a more prominent hypomethylation signature 30 minutes postexercise in gene regulatory regions important for transcription (CpG islands within promoter regions) compared with exercise in energy-deficit (with low-fat) conditions. Such hypomethylation was enriched within pathways related to IL6-JAK-STAT signaling, metabolic processes, p53/cell cycle, and oxidative/fatty acid metabolism. Hypomethylation within the promoter regions of the genes; histone deacetylase 2 (HDAC2), MECR, IGF2, and c13orf16 were associated with significant increases in gene expression in the postexercise period in energy balance compared with an energy deficit. Furthermore, HDAC11 was oppositely regulated at the gene expression level compared with family member HDAC2, where HDAC11 was hypomethylated yet increased in energy-deficit compared with energy-balance conditions. Overall, we identify some novel epigenetically regulated genes associated with train-low sleep-low paradigms.NEW & NOTEWORTHY We identify novel epigenetically regulated genes associated with train-low sleep-low paradigms. Exercise under low-carbohydrate (CHO) energy-balance (high-fat) conditions elicited a more prominent DNA hypomethylation signature 30 minutes postexercise compared with low-CHO energy-deficit (low-fat) conditions. This was enriched within IL6-JAK-STAT signaling, metabolic processes, p53, cell cycle, oxidative phosphorylation, and fatty acid metabolism. Histone deacetylase (HDAC) family members 2, 4, 10, and 11 demonstrated hypomethylation, with HDAC2 and HDAC11 possessing alternative regulation of gene expression in energy balance versus deficit conditions.


Asunto(s)
Epigenoma , Interleucina-6 , Masculino , Humanos , Interleucina-6/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Músculo Esquelético/metabolismo , Glucógeno/metabolismo , Ácidos Grasos/metabolismo
9.
Genome Res ; 30(3): 437-446, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32075851

RESUMEN

Viruses are the most abundant biological entities on Earth and play key roles in host ecology, evolution, and horizontal gene transfer. Despite recent progress in viral metagenomics, the inherent genetic complexity of virus populations still poses technical difficulties for recovering complete virus genomes from natural assemblages. To address these challenges, we developed an assembly-free, single-molecule nanopore sequencing approach, enabling direct recovery of complete virus genome sequences from environmental samples. Our method yielded thousands of full-length, high-quality draft virus genome sequences that were not recovered using standard short-read assembly approaches. Additionally, our analyses discriminated between populations whose genomes had identical direct terminal repeats versus those with circularly permuted repeats at their termini, thus providing new insight into native virus reproduction and genome packaging. Novel DNA sequences were discovered, whose repeat structures, gene contents, and concatemer lengths suggest they are phage-inducible chromosomal islands, which are packaged as concatemers in phage particles, with lengths that match the size ranges of co-occurring phage genomes. Our new virus sequencing strategy can provide previously unavailable information about the genome structures, population biology, and ecology of naturally occurring viruses and viral parasites.


Asunto(s)
Genoma Viral , Secuenciación de Nanoporos/métodos , Bacteriófagos/genética , Empaquetamiento del ADN , Metagenómica , Agua de Mar/virología
10.
Plant Cell Environ ; 46(5): 1472-1488, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36624682

RESUMEN

Succulence is found across the world as an adaptation to water-limited niches. The fleshy organs of succulent plants develop via enlarged photosynthetic chlorenchyma and/or achlorophyllous water storage hydrenchyma cells. The precise mechanism by which anatomical traits contribute to drought tolerance is unclear, as the effect of succulence is multifaceted. Large cells are believed to provide space for nocturnal storage of malic acid fixed by crassulacean acid metabolism (CAM), whilst also buffering water potentials by elevating hydraulic capacitance (CFT ). The effect of CAM and elevated CFT on growth and water conservation have not been compared, despite the assumption that these adaptations often occur together. We assessed the relationship between succulent anatomical adaptations, CAM, and CFT , across the genus Clusia. We also simulated the effects of CAM and CFT on growth and water conservation during drought using the Photo3 model. Within Clusia leaves, CAM and CFT are independent traits: CAM requires large palisade chlorenchyma cells, whereas hydrenchyma tissue governs interspecific differences in CFT . In addition, our model suggests that CAM supersedes CFT as a means to maximise CO2 assimilation and minimise transpiration during drought. Our study challenges the assumption that CAM and CFT are mutually dependent traits within succulent leaves.


Asunto(s)
Clusia , Metabolismo Ácido de las Crasuláceas , Clusia/metabolismo , Hojas de la Planta/metabolismo , Fotosíntesis , Agua/metabolismo
11.
J Neural Transm (Vienna) ; 130(3): 313-323, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36617378

RESUMEN

Attention deficit hyperactivity disorder (ADHD) is still a neglected disorder in older adults. The aim of the present study was to examine the prevalence and symptomatology of ADHD and associated psychopathology in adults aged 40-80 years in a German community sample. We examined 539 participants in two age groups: (1) 40-59 years old (n = 256) and (2) 60-80 years old (n = 283). To assess ADHD in both childhood and adulthood as well as current psychopathological impairments, we used self-report instruments and corresponding observer reports. We examined group differences between age groups and between ADHD and non-ADHD groups. The prevalence of ADHD in the total sample was 2.6% with no significant differences between the two age groups (40-59 years: 3.1% vs. 60-80 years: 2.1%). Although differences emerged in impulsivity/emotional lability and self-concept problems, overall ADHD symptom ratings did not differ between the age groups. The ADHD group showed more psychopathological peculiarities compared to individuals without ADHD with medium-to-large effect sizes. Self-reports and observer reports showed good concordance in the assessment of ADHD and comorbid psychopathological symptoms. Regarding current ADHD symptomatology, in 92.1%, self-report was corroborated by observer's information. Our findings underline that ADHD symptoms are relevant across the lifespan. Augmenting self-reports with observer reports could increase the assessment quality of ADHD. For successful treatment, clinicians should also focus on additional psychopathological impairments and comorbidities in older adults with ADHD.


Asunto(s)
Trastorno por Déficit de Atención con Hiperactividad , Humanos , Anciano , Niño , Adulto , Persona de Mediana Edad , Anciano de 80 o más Años , Trastorno por Déficit de Atención con Hiperactividad/psicología , Comorbilidad , Síntomas Afectivos/psicología , Autoinforme , Conducta Impulsiva
12.
J Sex Med ; 20(4): 549-558, 2023 03 31.
Artículo en Inglés | MEDLINE | ID: mdl-36861326

RESUMEN

BACKGROUND: Individuals convicted of a sexual offense (ICSO) can be treated with testosterone-lowering medication (TLM) in order to support the control of paraphilic sexual fantasies and to decrease the risk of sexual recidivism. However, due to partly severe side effects, TLM should not be a lifelong treatment. AIM: The aim of the current study was to further evaluate the Change or Stop Testosterone-Lowering Medication (COSTLow)-R Scale in forensic outpatient aftercare practice. The scale was developed to assist forensic professionals in deciding on whether to change or stop TLM treatment in ICSO. METHODS: The COSTLow-R Scale was applied retrospectively in a forensic-psychiatric outpatient institution in Hesse, Germany, on 60 ICSO. TLM was terminated in 24 patients (40%). Moreover, 10 forensic professionals of the institution as well as an experienced working group within the institution focusing on the treatment of ICSO, qualitatively evaluated the COSTLow-R Scale by participating in an open designed survey. OUTCOMES: The COSTLow-R Scale ratings as assessed by forensic professionals were collected. In addition, a survey was performed among these professionals about the usefulness of the scale and their practical experiences with it. RESULTS: A binary logistic regression analysis was conducted to ascertain the predictive power of the scale regarding the stopping of TLM. Three items of the COSTLow-R Scale significantly predicted stopping decisions: the possibility of psychotherapy before TLM treatment, psychopathic traits, and a substantial decrease of paraphilic severity. Thus, a decision towards stopping TLM was more likely for patients who showed greater treatment readiness before starting TLM, lower psychopathy scores, and a higher decrease of paraphilic severity. The forensic professionals described the scale as a good and structured tool that displays which aspects are important to consider during TLM treatment decisions. CLINICAL IMPLICATIONS: The COSTLow-R Scale provides structure to the decision of whether to change or stop TLM and should thus be implemented in the forensic treatment process of patients with TLM more frequently. STRENGTHS AND LIMITATIONS: Although the small sample size limits generalizability of the findings, the present study was conducted directly in a forensic outpatient practice and, therefore, has high external validity and a strong impact on the life and health of patients treated with TLM. CONCLUSION: The results indicate that the COSTLow-R Scale can be a useful instrument facilitating the TLM decision-making process by providing a structured compendium of criteria. Further research is still needed to evaluate the scale and to provide additional evidence for the results of the current study.


Asunto(s)
Delitos Sexuales , Testosterona , Masculino , Humanos , Testosterona/uso terapéutico , Estudios Retrospectivos , Delitos Sexuales/psicología , Conducta Sexual/psicología , Psicoterapia/métodos
13.
Acta Psychiatr Scand ; 148(1): 6-18, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-36932913

RESUMEN

INTRODUCTION: In offending populations, prevalence rates of mental disorders are much higher than in the general population. Nevertheless, it is unclear whether mental disorders can improve the prediction of recidivism beyond actuarial risk assessment tools. METHODS: The present prospective-longitudinal study was conducted between 2001 and 2021 and included 1066 men convicted of sexual offenses in Austria. All participants were evaluated with actuarial risk assessment tools for the prediction of sexual and violent recidivism and the Structured Clinical Interview for Axis I and Axis II disorders. Sexual and violent reconvictions were assessed. RESULTS: Exhibitionism and an exclusive pedophilia showed the strongest correlations with sexual recidivism in the total sample. In the child related offense subsample additionally a narcissistic personality disorder was correlated with sexual recidivism. The strongest correlation with violent recidivism was found for an antisocial and borderline personality disorder. None of the mental disorders could improve the prediction of recidivism beyond actuarial risk assessment tools. CONCLUSION: Common current actuarial risk assessment tools revealed good predictive accuracy in men convicted of sexual offenses. With few exceptions mental disorders were only weakly associated with recidivism, suggesting that there is no direct link between mental disorders and violent and sexual reoffending. Mental disorders should nevertheless be considered in treatment issues.


Asunto(s)
Reincidencia , Delitos Sexuales , Masculino , Niño , Humanos , Femenino , Estudios Prospectivos , Estudios Longitudinales , Medición de Riesgo , Trastornos de la Personalidad/epidemiología
14.
Phys Chem Chem Phys ; 25(41): 28437-28451, 2023 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-37843877

RESUMEN

A bacteriochlorophyll a (Bchla) dimer is a basic functional unit in the LH1 and LH2 photosynthetic pigment-protein antenna complexes of purple bacteria, where an ordered, close arrangement of Bchla pigments-secured by noncovalent bonding to a protein template-enables exciton delocalization at room temperature. Stable and tunable synthetic analogs of this key photosynthetic subunit could lead to facile engineering of exciton-based systems such as in artificial photosynthesis, organic optoelectronics, and molecular quantum computing. Here, using a combination of synthesis and theory, we demonstrate that exciton delocalization can be achieved in a dimer of a synthetic bacteriochlorin (BC) featuring stability, high structural modularity, and spectral properties advantageous for exciton-based devices. The BC dimer was covalently templated by DNA, a stable and highly programmable scaffold. To achieve exciton delocalization in the absence of pigment-protein interactions critical for the Bchla dimer, we relied on the strong transition dipole moment in BC enabled by two auxochromes along the Qy transition, and omitting the central metal and isocyclic ring. The spectral properties of the synthetic "free" BC closely resembled those of Bchla in an organic solvent. Applying spectroscopic modeling, the exciton delocalization in the DNA-templated BC dimer was evaluated by extracting the excitonic hopping parameter, J to be 214 cm-1 (26.6 meV). For comparison, the same method applied to the natural protein-templated Bchla dimer yielded J of 286 cm-1 (35.5 meV). The smaller value of J in the BC dimer likely arose from the partial bacteriochlorin intercalation and the difference in medium effect between DNA and protein.


Asunto(s)
Complejos de Proteína Captadores de Luz , Proteínas del Complejo del Centro de Reacción Fotosintética , Complejos de Proteína Captadores de Luz/química , Metodologías Computacionales , Teoría Cuántica , Proteínas del Complejo del Centro de Reacción Fotosintética/química , ADN
15.
J Phys Chem A ; 127(23): 4901-4918, 2023 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-37261888

RESUMEN

Aggregates of conjugated organic molecules (i.e., dyes) may exhibit relatively large one- and two-exciton interaction energies, which has motivated theoretical studies on their potential use in quantum information science (QIS). In practice, one way of realizing large one- and two-exciton interaction energies is by maximizing the transition dipole moment (µ) and difference static dipole moment (Δd) of the constituent dyes. In this work, we characterized the electronic structure and excited-state dynamics of monomers and aggregates of four asymmetric polymethine dyes templated via DNA. Using steady-state and time-resolved absorption and fluorescence spectroscopy along with quantum-chemical calculations, we found the asymmetric polymethine dye monomers exhibited a large µ, an appreciable Δd, and a long excited-state lifetime (τp). We formed dimers of all four dyes and observed that one dye, Dy 754, displayed the strongest propensity for aggregation and exciton delocalization. Motivated by these results, we undertook a more comprehensive survey of Dy 754 dimer and tetramer aggregates using steady-state absorption and circular dichroism spectroscopy. Modeling these spectra revealed an appreciable excitonic hopping parameter (J). Lastly, we used femtosecond transient absorption spectroscopy to characterize τp of the dimer and tetramer, which we observed to be exceedingly short. This work revealed that asymmetric polymethine dyes exhibited µ, Δd, monomer τp, and J values promising for QIS; however, further work is needed to overcome excited-state quenching and achieve long aggregate τp.

16.
J Phys Chem A ; 127(5): 1141-1157, 2023 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-36705555

RESUMEN

Molecular (dye) aggregates are a materials platform of interest in light harvesting, organic optoelectronics, and nanoscale computing, including quantum information science (QIS). Strong excitonic interactions between dyes are key to their use in QIS; critically, properties of the individual dyes govern the extent of these interactions. In this work, the electronic structure and excited-state dynamics of a series of indolenine-based squaraine dyes incorporating dimethylamino (electron donating) and/or nitro (electron withdrawing) substituents, so-called asymmetric dyes, were characterized. The dyes were covalently tethered to DNA Holliday junctions to suppress aggregation and permit characterization of their monomer photophysics. A combination of density functional theory and steady-state absorption spectroscopy shows that the difference static dipole moment (Δd) successively increases with the addition of these substituents while simultaneously maintaining a large transition dipole moment (µ). Steady-state fluorescence and time-resolved absorption and fluorescence spectroscopies uncover a significant nonradiative decay pathway in the asymmetrically substituted dyes that drastically reduces their excited-state lifetime (τ). This work indicates that Δd can indeed be increased by functionalizing dyes with electron donating and withdrawing substituents and that, in certain classes of dyes such as these asymmetric squaraines, strategies may be needed to ensure long τ, e.g., by rigidifying the π-conjugated network.

17.
CNS Spectr ; 28(6): 719-725, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-37130812

RESUMEN

OBJECTIVE: Despite the growing body of research on individuals convicted of child sexual exploitation material (CSEM), relatively little is known about the prevalence of mental disorders in this population. The aim of the present study was to describe the prevalence of mental disorders among individuals convicted of CSEM offenses. METHODS: This cross-sectional study examined data from 66 individuals serving a sentence for CSEM offenses in the Austrian prison system who underwent a clinical assessment between 2002 and 2020. Diagnoses were based on the German version of the Structured Clinical Interview for Axis I and Axis II disorders. RESULTS: In the total sample, n = 53 individuals (80.3%) were diagnosed with a mental disorder. Twenty-seven individuals (40.9%) had an Axis I disorder and n = 47 (71.2%) had an Axis II disorder. More than two-thirds of the sample, n = 47 (71.2%), had a personality disorder diagnosis, with cluster B personality disorders being the most frequent mental disorders. More than half of the sample, n = 43 (65.2%), had a diagnosis of pedophilic disorder, of which n = 9 (13.6%) were of the exclusive type. Twenty-eight persons (42.4%) showed evidence of a hypersexual disorder. CONCLUSIONS: In line with previous research, the present sample of convicted CSEM offenders showed a comparatively high prevalence of personality disorders and paraphilic disorders, particularly pedophilic disorders. Additionally, the rate of hypersexual disorder symptoms was considerably high. These findings should be considered for the development of successful risk management strategies for this population.


Asunto(s)
Trastornos Mentales , Prisioneros , Delitos Sexuales , Adulto , Masculino , Niño , Humanos , Femenino , Prevalencia , Estudios Transversales , Trastornos Mentales/epidemiología , Trastornos Mentales/diagnóstico
18.
J Chem Phys ; 158(3): 035101, 2023 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-36681650

RESUMEN

DNA is a re-configurable, biological information-storage unit, and much remains to be learned about its heterogeneous structural dynamics. For example, while it is known that molecular dyes templated onto DNA exhibit increased photostability, the mechanism by which the structural dynamics of DNA affect the dye photophysics remains unknown. Here, we use femtosecond, two-dimensional electronic spectroscopy measurements of a cyanine dye, Cy5, to probe local conformations in samples of single-stranded DNA (ssDNA-Cy5), double-stranded DNA (dsDNA-Cy5), and Holliday junction DNA (HJ-DNA-Cy5). A line shape analysis of the 2D spectra reveals a strong excitation-emission correlation present in only the dsDNA-Cy5 complex, which is a signature of inhomogeneous broadening. Molecular dynamics simulations support the conclusion that this inhomogeneous broadening arises from a nearly degenerate conformer found only in the dsDNA-Cy5 complex. These insights will support future studies on DNA's structural heterogeneity.


Asunto(s)
Colorantes Fluorescentes , Quinolinas , Colorantes Fluorescentes/química , ADN/química , Carbocianinas/química , ADN de Cadena Simple
19.
Biophys J ; 121(9): 1643-1659, 2022 05 03.
Artículo en Inglés | MEDLINE | ID: mdl-35378081

RESUMEN

Caveola membrane structures harbor mechanosensitive chloride channels (MCCs; including chloride channel 2, chloride channel 3, and SWELL1, also known as LRRC8A) that form a swelling-activated chloride current (ICl,swell) and play an important role in cell volume regulation and mechanoelectrical signal transduction. However, the role of the muscle-specific caveolar scaffolding protein caveolin-3 (Cav3) in regulation of MCC expression, activity, and contribution to membrane integrity in response to mechanical stress remains unclear. Here we showed that Cav3-transfected (Cav3-positive) HEK293 cells were significantly resistant to extreme (<20 milliosmole) hypotonic swelling compared with native (Cav3-negative) HEK293 cells; the percentage of cells with membrane damage decreased from 45% in Cav3-negative cells to 17% in Cav3-positive cells (p < 0.05). This mechanoprotection was significantly reduced (p < 0.05) when cells were exposed to the ICl,swell-selective inhibitor 4-[(2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid (10 µM). These results were recapitulated in isolated mouse ventricular myocytes, where the percentage of cardiomyocytes with membrane damage increased from 47% in control cells to 78% in 4-[(2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid-treated cells (p < 0.05). A higher resistance to hypotonic swelling in Cav3-positive HEK293 cells was accompanied by a significant twofold increase of ICl,swell current density and SWELL1 protein expression, whereas ClC-2/3 protein levels remained unchanged. Förster resonance energy transfer analysis showed a less than 10-nm membrane and intracellular association between Cav3 and SWELL1. Cav3/SWELL1 membrane Förster resonance energy transfer efficiency was halved in mild (220 milliosmole) hypotonic solution as well as after disruption of caveola structures via cholesterol depletion by 1-h treatment with 10 mM methyl-ß-cyclodextrin. A close association between Cav3 and SWELL1 was confirmed by co-immunoprecipitation analysis. Our findings indicate that, in the MCCs tested, SWELL1 abundance and activity are regulated by Cav3 and that their association relies on membrane tension and caveola integrity. This study highlights the mechanoprotective role of Cav3, which is facilitated by complimentary SWELL1 expression and activity.


Asunto(s)
Caveolina 3/metabolismo , Cloruros , Animales , Ácido Butírico , Tamaño de la Célula , Canales de Cloruro/metabolismo , Cloruros/metabolismo , Células HEK293 , Humanos , Proteínas de la Membrana/metabolismo , Ratones
20.
J Sex Med ; 19(7): 1147-1155, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35624071

RESUMEN

BACKGROUND: The number of individuals who sexually offended, and who are continued to be treated with pharmacological agents to reduce sex drive after their release from prison or forensic psychiatry, are not known. Furthermore, figures on the number of those who stop their sexdrive supressing antiandrogen treatment in the outpatient setting are unknown as well. This is of central importance though as it might be associated with an increased risk of recidivism. AIM: To assess prescription patterns as well as adherence to pharmacological treatment in outpatient clinics in Germany for individuals who have sexually offended and were released from prison or forensic psychiatric hospital. METHODS: A self-constructed online survey assessing the pharmacological treatment modalities was sent by e-mail to n = 103 forensic outpatient clinics in Germany. Thirty-three (32.0%) completed the questionnaire and reported about 834 patients. OUTCOMES: Prevalence of the use of different pharmacological agents in the treatment of individuals convicted for sexual offenses as well as the number of patients who have discontinued testosterone-lowering medication (TLM). RESULTS: Among all institutions, 22.4% (n = 187) of individuals received pharmacological treatment, with 40.1% receiving gonadotropin-releasing-hormone-agonists, 26.2% antipsychotics, 24.6% selective serotonin reuptake inhibitors, 6.4% cyproterone acetate, and 2.7% a combination of gonadotropin-releasing-hormone-agonists and cyproterone acetate. A significant positive correlation was found between the number of patients released from a forensic-psychiatric hospital and the number of patients treated with TLM. Within 1 year 8.6% (n = 16) stopped their TLM during or at the end of the supervision period, most of them against treatment providers advice. CLINICAL IMPLICATIONS: Substantial regional differences indicate uncertainties regarding the prescription of pharmacological agents for outpatients who have committed sexual offences in Germany. The discontinuiation of TLM within the first year of treatment against treatment providers advise in a substantial proportion of patients could be associated with a serious risk for reoffending. STRENGTHS & LIMITATIONS: The present survey captures prevalences of the pharmacotherapy in forensic aftercare facilities for individuals who have offended sexually, and is the first to record the number of discontinuations. This is a cross-sectional survey covering only 1 country, but includes a large number of individuals. CONCLUSION: Even though the number of treated individuals has increased in prisons, the majority of pharmacological treatment is still provided by forensic hospitals, which then translates into the outpatient setting. The number of those who stop taking such medication is a highly relevant topic for both forensic treatment providers and legal decision makers Sauter J, Rettenberger M, Briken P, et al. Survey on the Prescription Patterns of Pharmacological Agents in Individuals Who Have Committed Sexual Offenses During Forensic Outpatient Treatment in Germany: How Many Discontinue Testosterone Lowering Medication Under Parole?. J Sex Med 2022;19:1147-1155.


Asunto(s)
Pacientes Ambulatorios , Delitos Sexuales , Estudios Transversales , Acetato de Ciproterona/uso terapéutico , Alemania , Gonadotropinas , Humanos , Prescripciones , Delitos Sexuales/psicología , Encuestas y Cuestionarios , Testosterona/uso terapéutico
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA