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1.
Proc Natl Acad Sci U S A ; 120(19): e2301047120, 2023 05 09.
Artículo en Inglés | MEDLINE | ID: mdl-37126705

RESUMEN

The mitochondrial electron transport chain (ETC) of Plasmodium malaria parasites is a major antimalarial drug target, but critical cytochrome (cyt) functions remain unstudied and enigmatic. Parasites express two distinct cyt c homologs (c and c-2) with unusually sparse sequence identity and uncertain fitness contributions. P. falciparum cyt c-2 is the most divergent eukaryotic cyt c homolog currently known and has sequence features predicted to be incompatible with canonical ETC function. We tagged both cyt c homologs and the related cyt c1 for inducible knockdown. Translational repression of cyt c and cyt c1 was lethal to parasites, which died from ETC dysfunction and impaired ubiquinone recycling. In contrast, cyt c-2 knockdown or knockout had little impact on blood-stage growth, indicating that parasites rely fully on the more conserved cyt c for ETC function. Biochemical and structural studies revealed that both cyt c and c-2 are hemylated by holocytochrome c synthase, but UV-vis absorbance and EPR spectra strongly suggest that cyt c-2 has an unusually open active site in which heme is stably coordinated by only a single axial amino acid ligand and can bind exogenous small molecules. These studies provide a direct dissection of cytochrome functions in the ETC of malaria parasites and identify a highly divergent Plasmodium cytochrome c with molecular adaptations that defy a conserved role in eukaryotic evolution.


Asunto(s)
Antimaláricos , Malaria Falciparum , Parásitos , Animales , Citocromos c , Transporte de Electrón , Eucariontes , Citocromos c1
2.
Mol Cell ; 68(4): 673-685.e6, 2017 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-29149595

RESUMEN

Vms1 translocates to damaged mitochondria in response to stress, whereupon its binding partner, Cdc48, contributes to mitochondrial protein homeostasis. Mitochondrial targeting of Vms1 is mediated by its conserved mitochondrial targeting domain (MTD), which, in unstressed conditions, is inhibited by intramolecular binding to the Vms1 leucine-rich sequence (LRS). Here, we report a 2.7 Å crystal structure of Vms1 that reveals that the LRS lies in a hydrophobic groove in the autoinhibited MTD. We also demonstrate that the oxidized sterol, ergosterol peroxide, is necessary and sufficient for Vms1 localization to mitochondria, through binding the MTD in an interaction that is competitive with binding to the LRS. These data support a model in which stressed mitochondria generate an oxidized sterol receptor that recruits Vms1 to support mitochondrial protein homeostasis.


Asunto(s)
Ergosterol/análogos & derivados , Mitocondrias , Transporte de Proteínas , Saccharomyces cerevisiae , Proteínas Portadoras/química , Proteínas Portadoras/metabolismo , Cristalografía por Rayos X , Ergosterol/metabolismo , Mitocondrias/química , Mitocondrias/genética , Mitocondrias/metabolismo , Oxidación-Reducción , Dominios Proteicos , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo
3.
Proc Natl Acad Sci U S A ; 119(41): e2206504119, 2022 10 11.
Artículo en Inglés | MEDLINE | ID: mdl-36191202

RESUMEN

The expansive gyres of the subtropical ocean account for a significant fraction of global organic carbon export from the upper ocean. In the gyre interior, vertical mixing and the heaving of nutrient-rich waters into the euphotic layer sustain local productivity, in turn depleting the layers below. However, the nutrient pathways by which these subeuphotic layers are themselves replenished remain unclear. Using a global, eddy-permitting simulation of ocean physics and biogeochemistry, we quantify nutrient resupply mechanisms along and across density surfaces, including the contribution of eddy-scale motions that are challenging to observe. We find that mesoscale eddies (10 to 100 km) flux nutrients from the shallow flanks of the gyre into the recirculating interior, through time-varying motions along density surfaces. The subeuphotic layers are ultimately replenished in approximately equal contributions by this mesoscale eddy transport and the remineralization of sinking particles. The mesoscale eddy resupply is most important in the lower thermocline for the whole subtropical region but is dominant at all depths within the gyre interior. Subtropical gyre productivity may therefore be sustained by a nutrient relay, where the lateral transport resupplies nutrients to the thermocline and allows vertical exchanges to maintain surface biological production and carbon export.


Asunto(s)
Carbono , Agua de Mar , Nutrientes , Océanos y Mares
4.
Int J Cancer ; 155(4): 666-674, 2024 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-38554127

RESUMEN

Pre-clinical evidence suggests that 5-alpha reductase inhibitors (5ARi's), prescribed in the treatment of benign prostatic hyperplasia, reduce colorectal and gastro-oesophageal cancer incidence via action on the male hormonal pathway. However, few studies to date have investigated this association at the population level. Our study aimed to investigate the risk of colorectal and gastro-oesophageal cancers with the use of 5ARi's. We conducted a retrospective cohort study of new users of 5ARi's and alpha-blockers among patients with benign prostatic hyperplasia in the UK Clinical Practice Research Datalink. Patients were followed until a first ever diagnosis of colorectal or gastro-oesophageal cancer, death from any cause or end of registration with the general practice or 31st of December 2017. Cox proportional hazards models with inverse probability of treatment weights were used to calculate weighted hazard ratios (HR) and 95% confidence intervals (CIs) of incident colorectal cancer or gastro-oesophageal cancer associated with the use of 5ARi's compared to alpha-blockers. During a mean follow-up of 6.6 years, we found no association between the use of 5ARi's and colorectal (HR: 1.13, 95% CI 0.91-1.41) or gastro-oesophageal (HR 1.14, 95% CI 0.76-1.63) cancer risk compared to alpha-blockers. Sensitivity analysis showed largely consistent results when varying lag periods, using multiple imputations, and accounting for competing risk of death. Our study found no association between the use of 5ARi's and risk of colorectal or gastro-oesophageal cancer in men with benign prostatic hyperplasia.


Asunto(s)
Inhibidores de 5-alfa-Reductasa , Hiperplasia Prostática , Humanos , Masculino , Hiperplasia Prostática/tratamiento farmacológico , Hiperplasia Prostática/epidemiología , Inhibidores de 5-alfa-Reductasa/uso terapéutico , Inhibidores de 5-alfa-Reductasa/efectos adversos , Anciano , Estudios Retrospectivos , Persona de Mediana Edad , Incidencia , Neoplasias Gastrointestinales/epidemiología , Reino Unido/epidemiología , Antagonistas Adrenérgicos alfa/uso terapéutico , Antagonistas Adrenérgicos alfa/efectos adversos , Anciano de 80 o más Años , Neoplasias Colorrectales/epidemiología , Modelos de Riesgos Proporcionales , Factores de Riesgo , Neoplasias Esofágicas/epidemiología
5.
Bioinformatics ; 39(39 Suppl 1): i377-i385, 2023 06 30.
Artículo en Inglés | MEDLINE | ID: mdl-37387183

RESUMEN

MOTIVATION: Predicting the regulatory function of non-coding DNA using only the DNA sequence continues to be a major challenge in genomics. With the advent of improved optimization algorithms, faster GPU speeds, and more intricate machine-learning libraries, hybrid convolutional and recurrent neural network architectures can be constructed and applied to extract crucial information from non-coding DNA. RESULTS: Using a comparative analysis of the performance of thousands of Deep Learning architectures, we developed ChromDL, a neural network architecture combining bidirectional gated recurrent units, convolutional neural networks, and bidirectional long short-term memory units, which significantly improves upon a range of prediction metrics compared to its predecessors in transcription factor binding site, histone modification, and DNase-I hyper-sensitive site detection. Combined with a secondary model, it can be utilized for accurate classification of gene regulatory elements. The model can also detect weak transcription factor binding as compared to previously developed methods and has the potential to help delineate transcription factor binding motif specificities. AVAILABILITY AND IMPLEMENTATION: The ChromDL source code can be found at https://github.com/chrishil1/ChromDL.


Asunto(s)
Algoritmos , Benchmarking , ADN , Desoxirribonucleasa I , Factores de Transcripción
6.
Nat Chem Biol ; 18(5): 511-519, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35289328

RESUMEN

Cone snail venoms contain a wide variety of bioactive peptides, including insulin-like molecules with distinct structural features, binding modes and biochemical properties. Here, we report an active humanized cone snail venom insulin with an elongated A chain and a truncated B chain, and use cryo-electron microscopy (cryo-EM) and protein engineering to elucidate its interactions with the human insulin receptor (IR) ectodomain. We reveal how an extended A chain can compensate for deletion of B-chain residues, which are essential for activity of human insulin but also compromise therapeutic utility by delaying dissolution from the site of subcutaneous injection. This finding suggests approaches to developing improved therapeutic insulins. Curiously, the receptor displays a continuum of conformations from the symmetric state to a highly asymmetric low-abundance structure that displays coordination of a single humanized venom insulin using elements from both of the previously characterized site 1 and site 2 interactions.


Asunto(s)
Insulina , Venenos de Moluscos , Microscopía por Crioelectrón , Humanos , Insulina/metabolismo , Venenos de Moluscos/química , Venenos de Moluscos/metabolismo , Péptidos , Conformación Proteica
7.
Cell ; 137(7): 1282-92, 2009 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-19523676

RESUMEN

The mature capsids of HIV and other retroviruses organize and package the viral genome and its associated enzymes for delivery into host cells. The HIV capsid is a fullerene cone: a variably curved, closed shell composed of approximately 250 hexamers and exactly 12 pentamers of the viral CA protein. We devised methods for isolating soluble, assembly-competent CA hexamers and derived four crystallographically independent models that define the structure of this capsid assembly unit at atomic resolution. A ring of six CA N-terminal domains form an apparently rigid core, surrounded by an outer ring of C-terminal domains. Mobility of the outer ring appears to be an underlying mechanism for generating the variably curved lattice in authentic capsids. Hexamer-stabilizing interfaces are highly hydrated, and this property may be key to the formation of quasi-equivalent interactions within hexamers and pentamers. The structures also clarify the molecular basis for capsid assembly inhibition and should facilitate structure-based drug design strategies.


Asunto(s)
Proteínas de la Cápside/química , VIH-1/química , Proteínas de la Cápside/metabolismo , Cristalografía por Rayos X , VIH-1/metabolismo , Modelos Moleculares , Polímeros/metabolismo , Estructura Terciaria de Proteína
8.
Nucleic Acids Res ; 50(2): 784-802, 2022 01 25.
Artículo en Inglés | MEDLINE | ID: mdl-34967414

RESUMEN

The conserved transcription elongation factor Spt6 makes several contacts with the RNA Polymerase II (RNAPII) complex, including a high-affinity interaction between the Spt6 tandem SH2 domain (Spt6-tSH2) and phosphorylated residues of the Rpb1 subunit in the linker between the catalytic core and the C-terminal domain (CTD) heptad repeats. This interaction contributes to generic localization of Spt6, but we show here that it also has gene-specific roles. Disrupting the interface affected transcription start site selection at a subset of genes whose expression is regulated by this choice, and this was accompanied by changes in a distinct pattern of Spt6 accumulation at these sites. Splicing efficiency was also diminished, as was apparent progression through introns that encode snoRNAs. Chromatin-mediated repression was impaired, and a distinct role in maintaining +1 nucleosomes was identified, especially at ribosomal protein genes. The Spt6-tSH2:Rpb1 interface therefore has both genome-wide functions and local roles at subsets of genes where dynamic decisions regarding initiation, transcript processing, or termination are made. We propose that the interaction modulates the availability or activity of the core elongation and histone chaperone functions of Spt6, contributing to coordination between RNAPII and its accessory factors as varying local conditions call for dynamic responses.


Asunto(s)
Chaperonas de Histonas/metabolismo , ARN Polimerasa II/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Factores de Elongación Transcripcional/metabolismo , Dominios Homologos src , Sitios de Unión , Regulación de la Expresión Génica , Chaperonas de Histonas/química , Chaperonas de Histonas/genética , Humanos , IMP Deshidrogenasa/metabolismo , Modelos Biológicos , Modelos Moleculares , Mutación , Unión Proteica , Conformación Proteica , ARN Polimerasa II/química , ARN Polimerasa II/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Relación Estructura-Actividad , Sitio de Iniciación de la Transcripción , Transcripción Genética , Factores de Elongación Transcripcional/química , Factores de Elongación Transcripcional/genética
9.
J Aging Phys Act ; 32(3): 416-427, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38340712

RESUMEN

Physical function is regarded as the cornerstone of healthy aging, and exercise is an important determinant of healthy aging. This study examined the feasibility and physiological (heart rate, blood pressure, blood lactate, and rate of perceived exertion) and psychological (enjoyment) response resulting from an acute progressive sled-push (SLP) exercise session using the novel XPO Sled Trainer in older adults and compared that with walking (WKC) condition. The exercise session comprised six exercise bouts at 75%, 85%, 100% (2×), and 125% (2×) of normal velocity with a 2-min rest between bouts. Thirty-six older adults were randomly allocated into either the SLP or WKC conditions. No adverse events were observed during the exercise session, and all participants completed the exercise protocol as prescribed. One-third of the participants in the SLP group reported minimal body discomfort. Significantly higher responses were observed for all physiological variables as the intensity of the exercise increased in the SLP group compared with the WKC group (p < .001). The SLP group presented a decline in enjoyment as the intensity of the exercise increased (during), but similar enjoyment level than the WKC group for the overall exercise session (p = .711). Our findings support the viability and safety of SLP exercise using the XPO Sled Trainer in older adults. Such exercise demonstrated an intensity-driven modality that may have potential to elucidate positive adaptations in the cardiovascular system of older adults with acceptable levels of enjoyment.


Asunto(s)
Frecuencia Cardíaca , Humanos , Anciano , Masculino , Femenino , Frecuencia Cardíaca/fisiología , Ejercicio Físico/fisiología , Presión Sanguínea/fisiología , Caminata/fisiología , Esfuerzo Físico/fisiología , Envejecimiento Saludable/fisiología , Ácido Láctico/sangre , Estudios de Factibilidad
10.
Entropy (Basel) ; 26(2)2024 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-38392401

RESUMEN

We give a bilocal field theory description of a composite scalar with an extended binding potential that reduces to the Nambu-Jona-Lasinio (NJL) model in the pointlike limit. This provides a description of the internal dynamics of the bound state and features a static internal wave function, ϕ(r→), in the center-of-mass frame that satisfies a Schrödinger-Klein-Gordon equation with eigenvalues m2. We analyze the "coloron" model (single perturbative massive gluon exchange) which yields a UV completion of the NJL model. This has a BCS-like enhancement of its interaction, ∝Nc the number of colors, and is classically critical with gcritical remarkably close to the NJL quantum critical coupling. Negative eigenvalues for m2 lead to spontaneous symmetry breaking, and the Yukawa coupling of the bound state to constituent fermions is emergent.

11.
J Infect Dis ; 228(5): 542-554, 2023 08 31.
Artículo en Inglés | MEDLINE | ID: mdl-37166076

RESUMEN

BACKGROUND: Mechanisms underlying persistent cardiopulmonary symptoms after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (postacute sequelae of coronavirus disease 2019 [COVID-19; PASC] or "long COVID") remain unclear. This study sought to elucidate mechanisms of cardiopulmonary symptoms and reduced exercise capacity. METHODS: We conducted cardiopulmonary exercise testing (CPET), cardiac magnetic resonance imaging (CMR) and ambulatory rhythm monitoring among adults >1 year after SARS-CoV-2 infection, compared those with and those without symptoms, and correlated findings with previously measured biomarkers. RESULTS: Sixty participants (median age, 53 years; 42% female; 87% nonhospitalized; median 17.6 months after infection) were studied. At CPET, 18/37 (49%) with symptoms had reduced exercise capacity (<85% predicted), compared with 3/19 (16%) without symptoms (P = .02). The adjusted peak oxygen consumption (VO2) was 5.2 mL/kg/min lower (95% confidence interval, 2.1-8.3; P = .001) or 16.9% lower percent predicted (4.3%-29.6%; P = .02) among those with symptoms. Chronotropic incompetence was common. Inflammatory markers and antibody levels early in PASC were negatively correlated with peak VO2. Late-gadolinium enhancement on CMR and arrhythmias were absent. CONCLUSIONS: Cardiopulmonary symptoms >1 year after COVID-19 were associated with reduced exercise capacity, which was associated with earlier inflammatory markers. Chronotropic incompetence may explain exercise intolerance among some with "long COVID."


Asunto(s)
COVID-19 , Tolerancia al Ejercicio , Femenino , Masculino , Humanos , Medios de Contraste , Frecuencia Cardíaca , SARS-CoV-2 , Gadolinio , Inflamación , Fenotipo
12.
Appl Environ Microbiol ; 89(9): e0103323, 2023 09 28.
Artículo en Inglés | MEDLINE | ID: mdl-37695043

RESUMEN

All nitrogen-fixing bacteria and archaea (diazotrophs) use molybdenum (Mo) nitrogenase to reduce dinitrogen (N2) to ammonia, with some also containing vanadium (V) and iron-only (Fe) nitrogenases that lack Mo. Among diazotrophs, the regulation and usage of the alternative V-nitrogenase and Fe-nitrogenase in methanogens are largely unknown. Methanosarcina acetivorans contains nif, vnf, and anf gene clusters encoding putative Mo-nitrogenase, V-nitrogenase, and Fe-nitrogenase, respectively. This study investigated nitrogenase expression and growth by M. acetivorans in response to fixed nitrogen, Mo/V availability, and CRISPRi repression of the nif, vnf, and/or anf gene clusters. The availability of Mo and V significantly affected growth of M. acetivorans with N2 but not with NH4Cl. M. acetivorans exhibited the fastest growth rate and highest cell yield during growth with N2 in medium containing Mo, and the slowest growth in medium lacking Mo and V. qPCR analysis revealed the transcription of the nif operon is only moderately affected by depletion of fixed nitrogen and Mo, whereas vnf and anf transcription increased significantly when fixed nitrogen and Mo were depleted, with removal of Mo being key. Immunoblot analysis revealed Mo-nitrogenase is detected when fixed nitrogen is depleted regardless of Mo availability, while V-nitrogenase and Fe-nitrogenase are detected only in the absence of fixed nitrogen and Mo. CRISPRi repression studies revealed that V-nitrogenase and/or Fe-nitrogenase are required for Mo-independent diazotrophy, and unexpectedly that the expression of Mo-nitrogenase is also required. These results reveal that alternative nitrogenase production in M. acetivorans is tightly controlled and dependent on Mo-nitrogenase expression. IMPORTANCE Methanogens and closely related methanotrophs are the only archaea known or predicted to possess nitrogenase. Methanogens play critical roles in both the global biological nitrogen and carbon cycles. Moreover, methanogens are an ancient microbial lineage and nitrogenase likely originated in methanogens. An understanding of the usage and properties of nitrogenases in methanogens can provide new insight into the evolution of nitrogen fixation and aid in the development nitrogenase-based biotechnology. This study provides the first evidence that a methanogen can produce all three forms of nitrogenases, including simultaneously. The results reveal components of Mo-nitrogenase regulate or are needed to produce V-nitrogenase and Fe-nitrogenase in methanogens, a result not seen in bacteria. Overall, this study provides a foundation to understand the assembly, regulation, and activity of the alternative nitrogenases in methanogens.


Asunto(s)
Molibdeno , Nitrogenasa , Nitrogenasa/genética , Nitrogenasa/metabolismo , Molibdeno/metabolismo , Methanosarcina/genética , Methanosarcina/metabolismo , Nitrógeno/metabolismo , Fijación del Nitrógeno/genética , Archaea/metabolismo
13.
Mol Cell ; 60(2): 294-306, 2015 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-26455391

RESUMEN

FACT, a heterodimer of Spt16 and Pob3, is an essential histone chaperone. We show that the H2A-H2B binding activity that is central to FACT function resides in short acidic regions near the C termini of each subunit. Mutations throughout these regions affect binding and cause correlated phenotypes that range from mild to lethal, with the largest individual contributions unexpectedly coming from an aromatic residue and a nearby carboxylate residue within each domain. Spt16 and Pob3 bind overlapping sites on H2A-H2B, and Spt16-Pob3 heterodimers simultaneously bind two H2A-H2B dimers, the same stoichiometry as the components of a nucleosome. An Spt16:H2A-H2B crystal structure explains the biochemical and genetic data, provides a model for Pob3 binding, and implies a mechanism for FACT reorganization that we confirm biochemically. Moreover, unexpected similarity to binding of ANP32E and Swr1 with H2A.Z-H2B reveals that diverse H2A-H2B chaperones use common mechanisms of histone binding and regulating nucleosome functions.


Asunto(s)
Proteínas de Unión al ADN/metabolismo , Proteínas del Grupo de Alta Movilidad/metabolismo , Histonas/metabolismo , Nucleosomas/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Factores de Transcripción/metabolismo , Factores de Elongación Transcripcional/metabolismo , Secuencias de Aminoácidos , Secuencia Conservada , Cristalografía por Rayos X , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Regulación Fúngica de la Expresión Génica , Proteínas del Grupo de Alta Movilidad/química , Proteínas del Grupo de Alta Movilidad/genética , Histonas/química , Histonas/genética , Modelos Moleculares , Datos de Secuencia Molecular , Nucleosomas/metabolismo , Unión Proteica , Multimerización de Proteína , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Alineación de Secuencia , Factores de Transcripción/química , Factores de Transcripción/genética , Factores de Elongación Transcripcional/química , Factores de Elongación Transcripcional/genética
14.
Mol Cell ; 57(5): 901-911, 2015 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-25702872

RESUMEN

The UCH37 deubiquitylase functions in two large and very different complexes, the 26S proteasome and the INO80 chromatin remodeler. We have performed biochemical characterization and determined crystal structures of UCH37 in complexes with RPN13 and NFRKB, which mediate its recruitment to the proteasome and INO80, respectively. RPN13 and NFRKB make similar contacts to the UCH37 C-terminal domain but quite different contacts to the catalytic UCH domain. RPN13 can activate UCH37 by disrupting dimerization, although physiologically relevant activation likely results from stabilization of a surface competent for ubiquitin binding and modulation of the active-site crossover loop. In contrast, NFRKB inhibits UCH37 by blocking the ubiquitin-binding site and by disrupting the enzyme active site. These findings reveal remarkable commonality in mechanisms of recruitment, yet very different mechanisms of regulating enzyme activity, and provide a foundation for understanding the roles of UCH37 in the unrelated proteasome and INO80 complexes.


Asunto(s)
Modelos Moleculares , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Ubiquitina Tiolesterasa/química , Secuencia de Aminoácidos , Sitios de Unión/genética , Dominio Catalítico , Cristalografía por Rayos X , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Activación Enzimática , Humanos , Péptidos y Proteínas de Señalización Intracelular , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Datos de Secuencia Molecular , Complejos Multiproteicos/química , Complejos Multiproteicos/metabolismo , Complejo de la Endopetidasa Proteasomal/química , Complejo de la Endopetidasa Proteasomal/metabolismo , Unión Proteica , Multimerización de Proteína , Homología de Secuencia de Aminoácido , Ubiquitina/química , Ubiquitina/metabolismo , Ubiquitina Tiolesterasa/genética , Ubiquitina Tiolesterasa/metabolismo
15.
J Craniofac Surg ; 33(5): 1352-1357, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35758507

RESUMEN

ABSTRACT: Vascularized composite allotransplantation of the face is an exceedingly complex procedure, requiring extensive planning and surgical precision in order to successfully manage patients with facial disfigurements. This review aims to present an overview of the salient anatomic considerations in facial transplantation, as well as give attention to unique patient populations and special considerations.A literature review was performed in search of articles pertaining to considerations in facial transplantation using the databases PubMed, Web of Science, and Cochrane. Articles selected for further review included full-text articles with an emphasis on specific anatomic defects and how they were addressed in the transplant process, as well as management of special patient populations undergoing facial transplantation. In total, 19 articles were deemed appropriate for inclusion.The use of computer-assisted technologies for the planning portion of the procedure, as well as intraoperative efficiency, has yielded favorable results and can be considered as part of the operative plan. The ultimate outcome is dependent upon the synchronization of subunits of the allograft and the desired functional outcomes, including osseous, ocular, oral, and otologic considerations. Management of specific pathology and subgroups of patients are critical aspects. Although pediatric face transplantation has not yet been performed, it is a likely a future step in the evolution of this procedure.When performing a face transplantation, many components must be considered pre-, intra-, and post-operatively. This systematic review presents specific anatomic considerations, as well as information about special patient populations within this crosssection of multidisciplinary microsurgery, psychiatry, and transplant immunology.


Asunto(s)
Trasplante Facial , Alotrasplante Compuesto Vascularizado , Niño , Trasplante Facial/métodos , Humanos , Microcirugia , Trasplante Homólogo , Alotrasplante Compuesto Vascularizado/métodos
16.
High Educ Policy ; 35(3): 568-590, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35310366

RESUMEN

The impact of COVID-19 on higher education and quality assurance (QA) has already elicited global attention and discussion. QA agencies and networks quickly learned to adapt in order to carry out assessments, accreditations, recognitions, and reviews in a full virtual mode. These practices include using shared folders for virtual desk review, video conferencing platforms for interviews, and virtual site visits. In order to respond to the 2020 pandemic, The International Network for Quality Assurance Agencies in Higher Education (INQAAHE) swiftly adopted a virtual mode of the GGP review exercise for the GGP alignment applicants. The Higher Education Evaluation and Accreditation Council of Taiwan (HEEACT) was the first case that underwent a thorough virtual review process of GGP alignment during the 2020 pandemic. Therefore, this study aims to outline the impact of the pandemic in Taiwan higher education as well as provide the meta-analysis of the virtual review process of the INQAAHE GGP alignment by using HEEACT as a case study.

17.
J Biol Chem ; 295(2): 435-443, 2020 01 10.
Artículo en Inglés | MEDLINE | ID: mdl-31767681

RESUMEN

Many members of the AAA+ ATPase family function as hexamers that unfold their protein substrates. These AAA unfoldases include spastin, which plays a critical role in the architecture of eukaryotic cells by driving the remodeling and severing of microtubules, which are cytoskeletal polymers of tubulin subunits. Here, we demonstrate that a human spastin binds weakly to unmodified peptides from the C-terminal segment of human tubulin α1A/B. A peptide comprising alternating glutamate and tyrosine residues binds more tightly, which is consistent with the known importance of glutamylation for spastin microtubule severing activity. A cryo-EM structure of the spastin-peptide complex at 4.2 Å resolution revealed an asymmetric hexamer in which five spastin subunits adopt a helical, spiral staircase configuration that binds the peptide within the central pore, whereas the sixth subunit of the hexamer is displaced from the peptide/substrate, as if transitioning from one end of the helix to the other. This configuration differs from a recently published structure of spastin from Drosophila melanogaster, which forms a six-subunit spiral without a transitioning subunit. Our structure resembles other recently reported AAA unfoldases, including the meiotic clade relative Vps4, and supports a model in which spastin utilizes a hand-over-hand mechanism of tubulin translocation and microtubule remodeling.


Asunto(s)
Espastina/metabolismo , Tubulina (Proteína)/metabolismo , Sitios de Unión , Ácido Glutámico/química , Ácido Glutámico/metabolismo , Humanos , Modelos Moleculares , Fragmentos de Péptidos/química , Fragmentos de Péptidos/metabolismo , Unión Proteica , Conformación Proteica , Multimerización de Proteína , Espastina/química , Tubulina (Proteína)/química
18.
J Am Chem Soc ; 143(1): 359-368, 2021 01 13.
Artículo en Inglés | MEDLINE | ID: mdl-33356181

RESUMEN

Hydroamination of alkenes catalyzed by transition-metal complexes is an atom-economical method for the synthesis of amines, but reactions of unactivated alkenes remain inefficient. Additions of N-H bonds to such alkenes catalyzed by iridium, gold, and lanthanide catalysts are known, but they have required a large excess of the alkene. New mechanisms for such processes involving metals rarely used previously for hydroamination could enable these reactions to occur with greater efficiency. We report ruthenium-catalyzed intermolecular hydroaminations of a variety of unactivated terminal alkenes without the need for an excess of alkene and with 2-aminopyridine as an ammonia surrogate to give the Markovnikov addition product. Ruthenium complexes have rarely been used for hydroaminations and have not previously catalyzed such reactions with unactivated alkenes. Identification of the catalyst resting state, kinetic measurements, deuterium labeling studies, and DFT computations were conducted and, together, strongly suggest that this process occurs by a new mechanism for hydroamination occurring by oxidative amination in concert with reduction of the resulting imine.


Asunto(s)
Alquenos/química , Aminopiridinas/síntesis química , Complejos de Coordinación/química , Aminación , Catálisis , Teoría Funcional de la Densidad , Modelos Químicos , Oxidación-Reducción , Rutenio/química
19.
J Am Chem Soc ; 143(29): 10910-10919, 2021 07 28.
Artículo en Inglés | MEDLINE | ID: mdl-34255504

RESUMEN

As the only ribosomally encoded N-substituted amino acid, proline promotes distinct secondary protein structures. The high proline content in collagen, the most abundant protein in the human body, is crucial to forming its hallmark structure: the triple-helix. For over five decades, proline has been considered compulsory for synthetic designs aimed at recapitulating collagen's structure and properties. Here we describe that N-substituted glycines (N-glys), also known as peptoid residues, exhibit a general triple-helical propensity similar to or greater than proline, enabling synthesis of stable triple-helical collagen mimetic peptides (CMPs) with unprecedented side chain diversity. Supported by atomic-resolution crystal structures as well as circular dichroism and computational characterizations spanning over 30 N-gly-containing CMPs, we discovered that N-glys stabilize the triple-helix primarily by sterically preorganizing individual chains into the polyproline-II helix. We demonstrated that N-glys with exotic side chains including a "click"-able alkyne and a photosensitive side chain enable CMPs for functional applications including the spatiotemporal control of cell adhesion and migration. The structural principles uncovered in this study open up opportunities for a new generation of collagen-mimetic therapeutics and materials.


Asunto(s)
Colágeno/síntesis química , Glicina/química , Péptidos/síntesis química , Colágeno/química , Estructura Molecular , Péptidos/química
20.
Am Heart J ; 240: 81-88, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34147462

RESUMEN

BACKGROUND: The Fifty-Fifty trial demonstrated that a peer-group-based intervention was able to improve healthy behaviors in individuals with cardiovascular (CV) risk factors immediately post-intervention. OBJECTIVES: To determine the long-term sustainability of a one-year peer-group-based intervention focused on CV health and behavior. METHODS: A total of 543 adults aged 25 to 50 years with at least 1 CV risk factor were screened and recruited, received initial training through workshops, and were then randomized 1:1 to a peer-group-based intervention group (IG) or a self-management control group (CG) for 12 months. At a median of 52 months from baseline, 321 participants were re-assessed (~60% retention). The primary outcome was the mean change in a composite health score related to blood pressure, exercise, weight, alimentation, and tobacco use (Fuster-BEWAT score [FBS], range 0-15). Intervention effects were assessed using linear-mixed effects models. RESULTS: The mean age of retained participants was 48.0 years (SD: 5.4), and 73% were female. Consistent with previous results, the change of overall FBS was significantly greater in the IG than in the CG at 12-month follow-up (between-group difference, 0.60 points; 95% CI, 0.08-1.12; P = .025). Assessment of long-term sustainability (52-month follow-up) showed that there were no between-group differences in the mean overall FBS (IG mean score, 8.52; 95% CI, 7.97-9.07 vs CG mean score, 8.51; 95% CI, 7.93-9.10; P = .972) or in the change of overall FBS from screening (IG mean change, 0.64; 95% CI, 0.00-1.28; CG mean change, 0.46; 95% CI, -0.20-1.12; P = .497). CONCLUSIONS: A one-year peer-group-based intervention showed favorable results at immediate post-intervention but did not demonstrate significant differences between the IG and CG at 52 months. Combination of an initial training period (workshops) with the maintenance of peer-support groups or other re-intervention strategies may be required to achieve sustained effects on healthy behaviors. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02367963. Registered (https://clinicaltrials.gov/show/NCT02367963).


Asunto(s)
Enfermedades Cardiovasculares/prevención & control , Conductas Relacionadas con la Salud , Factores de Riesgo de Enfermedad Cardiaca , Influencia de los Compañeros , Apoyo Social , Adulto , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Automanejo
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