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1.
J Invasive Cardiol ; 2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38814903

RESUMO

A 57-year-old woman with good past health was admitted to the accident and emergency department at an outside hospital for sudden onset chest pain. Electrocardiogram revealed ST-segment elevation at inferior leads.

2.
Nutr Cancer ; 76(6): 463-468, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38591931

RESUMO

Methionine is an essential amino acid critical for cell growth and survival. Preclinical evidence suggests a methionine restricted diet (MRD) sensitizes cancer to radiation therapy (RT), without significant adverse effects. However, this has never been evaluated in humans. The purpose of this pilot study was to evaluate the safety and feasibility of concurrent MRD with standard-of-care definitive RT in adults with any non-skin cancer malignancy. The MRD extended from 2 wk before RT initiation, through 2 wk beyond RT completion. The primary endpoint of safety was assessed as rate of grade 3 or higher acute and late toxicities. Feasibility was assessed with quantitative plasma amino acid panel every 2 wk during the MRD (target plasma methionine 13 µM). Nine patients were accrued over a two-year period, with five able to complete the treatment course. The trial was closed due to slow accrual and subjects' difficulty maintaining the diet. No grade 3 or higher adverse events were observed. Subjects' average methionine level was 18.8 µM during treatment, with average nadir 16.8 µM. These findings suggest the safety of concurrent MRD with RT, with toxicities comparable to those expected with RT alone. However, the diet was challenging, and unacceptable to most patients.


Assuntos
Metionina , Humanos , Metionina/sangue , Masculino , Pessoa de Meia-Idade , Feminino , Projetos Piloto , Idoso , Adulto , Neoplasias/radioterapia , Neoplasias/dietoterapia , Dieta
4.
Clin Res Cardiol ; 112(10): 1463-1474, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37540240

RESUMO

BACKGROUND: The nonuniform benefit of tricuspid annuloplasty may be explained by the proportionality of tricuspid regurgitation (TR) severity to right ventricular (RV) area. The purpose of this study was to delineate distinct morphological phenotypes of functional TR and investigate their prognostic implications in patients undergoing tricuspid annuloplasty during left-sided valvular surgery. METHODS: The ratios of pre-procedural effective regurgitant orifice area (EROA) with right ventricular end-diastolic area (RVDA) were retrospectively assessed in 290 patients undergoing tricuspid annuloplasty. Based on optimal thresholds derived from penalized splines and maximally selected rank statistics, patients were stratified into proportionate (EROA/RVDA ratio ≤ 1.74) and disproportionate TR (EROA/RVDA ratio > 1.74). RESULTS: Overall, 59 (20%) and 231 (80%) patients had proportionate and disproportionate TR, respectively. Compared to those with proportionate TR, patients with disproportionate TR were older, had a higher prevalence of atrial fibrillation, lower pulmonary pressures, more impaired RV function, and larger tricuspid leaflet tenting area. Over a median follow-up of 4.1 years, 79 adverse events (47 heart failure hospitalizations and 32 deaths) occurred. Patients with disproportionate TR had higher rates of adverse events than those with proportionate TR (32% vs 10%; P = 0.001) and were independently associated with poor outcomes on multivariate analysis. TR proportionality outperformed guideline-based classification of TR severity in outcome prediction and provided incremental prognostic value to both the EuroSCORE II and STS score (incremental χ2 = 6.757 and 9.094 respectively; both P < 0.05). CONCLUSIONS: Disproportionate TR is strongly associated with adverse prognosis and may aid patient selection and risk stratification for tricuspid annuloplasty with left-sided valvular surgery.


Assuntos
Anuloplastia da Valva Cardíaca , Insuficiência da Valva Tricúspide , Humanos , Insuficiência da Valva Tricúspide/diagnóstico , Insuficiência da Valva Tricúspide/cirurgia , Prognóstico , Estudos Retrospectivos , Valva Tricúspide/diagnóstico por imagem , Valva Tricúspide/cirurgia , Análise Multivariada , Anuloplastia da Valva Cardíaca/efeitos adversos
5.
J Cardiovasc Transl Res ; 16(5): 1166-1176, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36991293

RESUMO

The utilization of FFR remains low. Our study evaluated the per-vessel prognostic value of computational pressure-flow dynamics-derived FFR (caFFR) among patients with stable coronary artery disease. A total of 3329 vessels from 1308 patients were included and analysed. They were stratified into ischaemic (caFFR ≤ 0.8) and non-ischaemic (caFFR > 0.8) cohorts, and the associations between PCI and outcomes were evaluated. The third cohort comprised all included vessels, and the associations between treatment adherent-to-caFFR (PCI in vessels with caFFR ≤ 0.8 and no PCI in vessels with caFFR > 0.8) and outcomes were evaluated. The primary outcome was VOCE, defined as a composite of vessel-related cardiovascular mortality, non-fatal myocardial infarction, and repeat revascularization. PCI was associated with a lower 3-year risk of VOCE in the ischaemic cohort (HR, 0.44; 95% CI, 0.26-0.74; P = 0.002) but not in the non-ischaemic cohort. The risk of VOCE was lower in the adherent-to-caFFR group (n = 2649) (HR, 0.69; 95% CI, 0.48-0.98; P = 0.039). A novel index that uses coronary angiography images to estimate FFR may have substantial clinical value in guiding management among patients with stable coronary artery disease.


Assuntos
Doença da Artéria Coronariana , Reserva Fracionada de Fluxo Miocárdico , Intervenção Coronária Percutânea , Humanos , Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/terapia , Resultado do Tratamento , Angiografia Coronária/métodos , Valor Preditivo dos Testes
6.
Clin J Am Soc Nephrol ; 18(3): 315-326, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36787125

RESUMO

BACKGROUND: Up to 14% of patients in the United States undergoing cardiac catheterization each year experience AKI. Consistent use of risk minimization preventive strategies may improve outcomes. We hypothesized that team-based coaching in a Virtual Learning Collaborative (Collaborative) would reduce postprocedural AKI compared with Technical Assistance (Assistance), both with and without Automated Surveillance Reporting (Surveillance). METHODS: The IMPROVE AKI trial was a 2×2 factorial cluster-randomized trial across 20 Veterans Affairs medical centers (VAMCs). Participating VAMCs received Assistance, Assistance with Surveillance, Collaborative, or Collaborative with Surveillance for 18 months to implement AKI prevention strategies. The Assistance and Collaborative approaches promoted hydration and limited NPO and contrast dye dosing. We fit logistic regression models for AKI with site-level random effects accounting for the clustering of patients within medical centers with a prespecified interest in exploring differences across the four intervention arms. RESULTS: Among VAMCs' 4517 patients, 510 experienced AKI (235 AKI events among 1314 patients with preexisting CKD). AKI events in each intervention cluster were 110 (13%) in Assistance, 122 (11%) in Assistance with Surveillance, 190 (13%) in Collaborative, and 88 (8%) in Collaborative with Surveillance. Compared with sites receiving Assistance alone, case-mix-adjusted differences in AKI event proportions were -3% (95% confidence interval [CI], -4 to -3) for Assistance with Surveillance, -3% (95% CI, -3 to -2) for Collaborative, and -5% (95% CI, -6 to -5) for Collaborative with Surveillance. The Collaborative with Surveillance intervention cluster had a substantial 46% reduction in AKI compared with Assistance alone (adjusted odds ratio=0.54; 0.40-0.74). CONCLUSIONS: This implementation trial estimates that the combination of Collaborative with Surveillance reduced the odds of AKI by 46% at VAMCs and is suggestive of a reduction among patients with CKD. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: IMPROVE AKI Cluster-Randomized Trial (IMPROVE-AKI), NCT03556293.


Assuntos
Injúria Renal Aguda , Tutoria , Insuficiência Renal Crônica , Humanos , Estados Unidos , Meios de Contraste/efeitos adversos , United States Department of Veterans Affairs , Insuficiência Renal Crônica/induzido quimicamente , Injúria Renal Aguda/induzido quimicamente , Injúria Renal Aguda/prevenção & controle
7.
Hum Mol Genet ; 32(10): 1634-1646, 2023 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-36621967

RESUMO

Autism spectrum disorder (ASD) affects 1 in 44 children. Chromatin regulatory proteins are overrepresented among genes that contain high risk variants in ASD. Disruption of the chromatin environment leads to widespread dysregulation of gene expression, which is traditionally thought of as a mechanism of disease pathogenesis associated with ASD. Alternatively, alterations in chromatin dynamics could also lead to dysregulation of alternative splicing, which is understudied as a mechanism of ASD pathogenesis. The anticonvulsant valproic acid (VPA) is a well-known environmental risk factor for ASD that acts as a class I histone deacetylase inhibitor. However, the precise molecular mechanisms underlying defects in human neuronal development associated with exposure to VPA are understudied. To dissect how VPA exposure and subsequent chromatin hyperacetylation influence molecular signatures involved in ASD pathogenesis, we conducted RNA sequencing (RNA-seq) in human cortical neurons that were treated with VPA. We observed that differentially expressed genes (DEGs) were enriched for mRNA splicing, mRNA processing, histone modification and metabolism related gene sets. Furthermore, we observed widespread increases in the number and the type of alternative splicing events. Analysis of differential transcript usage (DTU) showed that exposure to VPA induces extensive alterations in transcript isoform usage across neurodevelopmentally important genes. Finally, we find that DEGs and genes that display DTU overlap with known ASD-risk genes. Altogether, these findings suggest that, in addition to differential gene expression, changes in alternative splicing correlated with alterations in the chromatin environment could act as an additional mechanism of disease in ASD.


Assuntos
Transtorno do Espectro Autista , Efeitos Tardios da Exposição Pré-Natal , Criança , Humanos , Animais , Feminino , Transtorno do Espectro Autista/etiologia , Cromatina/genética , Processamento Alternativo/genética , Ácido Valproico/efeitos adversos , RNA Mensageiro/metabolismo , Modelos Animais de Doenças
8.
iScience ; 25(9): 104960, 2022 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-36065188

RESUMO

Chronic environmental stress can profoundly impact cell and body function. Although the underlying mechanisms are poorly understood, epigenetics has emerged as a key link between environment and health. The genomic effects of stress are thought to be mediated by the action of glucocorticoid stress hormones, primarily cortisol in humans, which act via the glucocorticoid receptor (GR). To dissect how chronic stress-driven GR activation influences epigenetic and cell states, human fibroblasts underwent prolonged exposure to physiological stress levels of cortisol and/or a selective GR antagonist. Cortisol was found to drive robust changes in cell proliferation, migration, and morphology, which were abrogated by concomitant GR blockade. The GR-driven cell phenotypes were accompanied by widespread, yet genomic context-dependent, changes in DNA methylation and mRNA expression, including gene loci with known roles in cell proliferation and migration. These findings provide insights into how chronic stress-driven functional epigenomic patterns become established to shape key cell phenotypes.

9.
Nature ; 607(7918): 256-259, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35831603

RESUMO

Fast radio bursts (FRBs) are millisecond-duration flashes of radio waves that are visible at distances of billions of light years1. The nature of their progenitors and their emission mechanism remain open astrophysical questions2. Here we report the detection of the multicomponent FRB 20191221A and the identification of a periodic separation of 216.8(1) ms between its components, with a significance of 6.5σ. The long (roughly 3 s) duration and nine or more components forming the pulse profile make this source an outlier in the FRB population. Such short periodicity provides strong evidence for a neutron-star origin of the event. Moreover, our detection favours emission arising from the neutron-star magnetosphere3,4, as opposed to emission regions located further away from the star, as predicted by some models5.

10.
Phys Rev Lett ; 128(16): 163201, 2022 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-35522508

RESUMO

Optical precision spectroscopy of isotope shifts can be used to test for new forces beyond the standard model, and to determine basic properties of atomic nuclei. We measure isotope shifts on the highly forbidden ^{2}S_{1/2}→^{2}F_{7/2} octupole transition of trapped ^{168,170,172,174,176}Yb ions. When combined with previous measurements in Yb^{+} and very recent measurements in Yb, the data reveal a King plot nonlinearity of up to 240σ. The trends exhibited by experimental data are explained by nuclear density functional theory calculations with the Fayans functional. We also find, with 4.3σ confidence, that there is a second distinct source of nonlinearity, and discuss its possible origin.

11.
Disabil Rehabil ; 44(17): 4681-4688, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-33989108

RESUMO

PURPOSE: To describe and categorize difficulties in daily activities of older adults with subjective cognitive decline (SCD) compared to individuals with mild cognitive impairment (MCI). METHODS: Deductive quantitative content analysis was used to classify reported issues in the performance of meaningful daily activities, in older adults with SCD (n = 67; age= 70 ± 6.3) or MCI (n = 42; age= 72 ± 6.6). The occupational performance issues were identified using the Canadian Occupational Performance Measure, a semi-structured interview, and categorised using the International Classification of Functioning, Disability and Health (ICF). RESULTS: Both groups identified issues in all nine ICF "Activities and Participation" domains, with no significant group effects on seven of them. The most frequently affected "Activities and Participation" domains in both groups were "Self-care" (e.g. exercise and diet); "Community, social and civic life" (e.g. social-leisure activities); and "General tasks and demands" (e.g. time management). Over 90% of the issues in both groups were described in the context of difficulties in "Mental functions" (e.g. memory and higher-level cognitive functions). CONCLUSIONS: Older adults with SCD, although independent, identified a variety of daily activities that they are not performing satisfactorily, remarkably similar in nature to the occupational performance issues described by older adults with MCI.Implications for RehabilitationOlder adults with SCD identified difficulties in performing social and leisure activities, maintaining healthy lifestyle behaviours, and managing multiple daily tasks.The daily challenges described by older adults with SCD are similar in nature to those identified by those with MCI.Older adults with SCD and MCI describe their daily challenges are related not only to memory problems, but also to executive dysfunction.Interventions for older adults with SCD should aim to improve self-identified problems in everyday functioning.


Assuntos
Disfunção Cognitiva , Pessoas com Deficiência , Atividades Cotidianas/psicologia , Idoso , Canadá , Disfunção Cognitiva/psicologia , Humanos , Pessoa de Meia-Idade , Testes Neuropsicológicos , Autocuidado
12.
Int J Radiat Biol ; 97(10): 1417-1424, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34264175

RESUMO

RATIONALE: Natural killer (NK) cells play an important role in both the innate and adaptive arms of the immune system. While previous studies have demonstrated the effects of ionizing radiation on cytotoxic function of NK cells, little is known about how a chronic exposure to high LET alpha particles emitted by radionuclides will affect both NK population size and function. This study was conducted to determine the effects of 223RaCl2 on splenic NK cell population size and function in Swiss Webster mice. METHODS: Swiss Webster mice were administered intravenously with 0, 50, or 600 kBq/kg 223RaCl2. Spleens were harvested at 5, 12, and 19 days post-administration. The numbers of splenocytes per spleen were enumerated and flow cytometry was used to assess changes in the distribution of splenocyte subpopulations of B, CD4 and CD8 T lymphocytes, and NK cells. NK functional activity was quantified using YAC-1 target cells and the 51Cr-release assay. RESULTS: The total number of splenocytes was unaffected by 223RaCl2. However, significant changes in the distribution of splenocyte subpopulations were observed for NK cells and CD8 T lymphocytes. NK functional activity was enhanced substantially relative to controls at 12 days post-administration, but decreased markedly by day 19. CONCLUSION: NK functional activity is both diminished and enhanced by 223RaCl2 depending on both administered activity and time post-administration. These results suggest that there may be an optimum window of time to combine the 223RaCl2-induced antitumor NK cell response with other cancer therapies that elicit immune activation.


Assuntos
Células Matadoras Naturais , Animais , Linfócitos T CD8-Positivos , Citometria de Fluxo , Camundongos , Rádio (Elemento) , Baço
13.
Int J Radiat Biol ; 97(9): 1217-1228, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34232830

RESUMO

RATIONALE: The role of radiation-induced bystander effects in cancer therapy with alpha-particle emitting radiopharmaceuticals remains unclear. With renewed interest in using alpha-particle emitters to sterilize disseminated tumor cells, micrometastases, and tumors, a better understanding of the direct effects of alpha particles and the contribution of the bystander responses they induce is needed to refine dosimetric models that help predict clinical benefit. Accordingly, this work models and quantifies the relative importance of direct effects (DE) and bystander effects (BE) in the growth delay of human breast cancer xenografts observed previously in the tibiae of mice treated with 223RaCl2. METHODS: A computational model of MDA-MB-231 and MCF-7 human breast cancer xenografts in the tibial bone marrow of mice administered 223RaCl2 was created. A Monte Carlo radiation transport simulation was performed to assess individual cell absorbed doses. The responses of the breast cancer cells to direct alpha particle irradiation and gamma irradiation were needed as input data for the model and were determined experimentally using a colony-forming assay and compared to the responses of preosteoblast MC3T3-E1 and osteocyte-like MLO-Y4 bone cells. Using these data, a scheme was devised to simulate the dynamic proliferation of the tumors in vivo, including DE and BE propagated from the irradiated cells. The parameters of the scheme were estimated semi-empirically to fit experimental tumor growth. RESULTS: A robust BE component, in addition to a much smaller DE component, was required to simulate the in vivo tumor proliferation. We also found that the relative biological effectiveness (RBE) for cell killing by alpha particle radiation was greater for the bone cells than the tumor cells. CONCLUSION: This modeling study demonstrates that DE of radiation alone cannot explain experimental observations of 223RaCl2-induced growth delay of human breast cancer xenografts. Furthermore, while the mechanisms underlying BE remain unclear, the addition of a BE component to the model is necessary to provide an accurate prediction of the growth delay. More complex models are needed to further comprehend the extent and complexity of 223RaCl2-induced BE.


Assuntos
Medula Óssea/efeitos da radiação , Neoplasias da Mama/patologia , Neoplasias da Mama/radioterapia , Transformação Celular Neoplásica , Modelos Biológicos , Rádio (Elemento)/uso terapêutico , Partículas alfa/uso terapêutico , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos da radiação , Feminino , Camundongos , Método de Monte Carlo , Eficiência Biológica Relativa
14.
Mol Cancer Res ; 19(10): 1739-1750, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34039648

RESUMO

Radiation-induced bystander effects have been implicated in contributing to the growth delay of disseminated tumor cells (DTC) caused by 223RaCl2, an alpha particle-emitting radiopharmaceutical. To understand how 223RaCl2 affects the growth, we have quantified biological changes caused by direct effects of radiation and bystander effects caused by the emitted radiations on DTC and osteocytes. Characterizing these effects contribute to understanding the efficacy of alpha particle-emitting radiopharmaceuticals and guide expansion of their use clinically. MDA-MB-231 or MCF-7 human breast cancer cells were inoculated intratibially into nude mice that were previously injected intravenously with 50 or 600 kBq/kg 223RaCl2. At 1-day and 3-days postinoculation, tibiae were harvested and examined for DNA damage (γ-H2AX foci) and apoptosis in osteocytes and cancer cells located within and beyond the range (70 µm) of alpha particles emitted from the bone surface. Irradiated and bystander MDA-MB-231 and MCF-7 cells harbored DNA damage. Bystander MDA-MB-231 cells expressed DNA damage at both treatment levels while bystander MCF-7 cells required the higher administered activity. Osteocytes also had DNA damage regardless of inoculated cancer cell line. The extent of DNA damage was quantified by increases in low (1-2 foci), medium (3-5 foci), and high (5+ foci) damage. MDA-MB-231 but not MCF-7 bystander cells showed increases in apoptosis in 223RaCl2-treated animals, as did irradiated osteocytes. In summary, radiation-induced bystander effects contribute to DTC cytotoxicity caused by 223RaCl2. IMPLICATIONS: This observation supports clinical investigation of the efficacy of 223RaCl2 to prevent breast cancer DTC from progressing to oligometastases.


Assuntos
Apoptose/efeitos da radiação , Medula Óssea/efeitos da radiação , Efeito Espectador/efeitos da radiação , Dano ao DNA/efeitos da radiação , Rádio (Elemento)/farmacologia , Partículas alfa/uso terapêutico , Animais , Neoplasias da Mama/radioterapia , Linhagem Celular Tumoral , Proliferação de Células/efeitos da radiação , Feminino , Humanos , Células MCF-7 , Camundongos , Camundongos Nus , Osteócitos/efeitos da radiação
15.
Hepatology ; 73(6): 2441-2454, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33006772

RESUMO

BACKGROUND AND AIMS: Previous recommendations suggested living donor liver transplantation (LDLT) should not be considered for patients with Model for End-Stage Liver Disease (MELD) > 25 and hepatorenal syndrome (HRS). APPROACH AND RESULTS: Patients who were listed with MELD > 25 from 2008 to 2017 were analyzed with intention-to-treat (ITT) basis retrospectively. Patients who had a potential live donor were analyzed as ITT-LDLT, whereas those who had none belonged to ITT-deceased donor liver transplantation (DDLT) group. ITT-overall survival (OS) was analyzed from the time of listing. Three hundred twenty-five patients were listed (ITT-LDLT n = 212, ITT-DDLT n = 113). The risk of delist/death was lower in the ITT-LDLT group (43.4% vs. 19.8%, P < 0.001), whereas the transplant rate was higher in the ITT-LDLT group (78.3% vs. 52.2%, P < 0.001). The 5-year ITT-OS was superior in the ITT-LDLT group (72.6% vs. 49.5%, P < 0.001) for patients with MELD > 25 and patients with both MELD > 25 and HRS (56% vs. 33.8%, P < 0.001). Waitlist mortality was the highest early after listing, and the distinct alteration of slope at survival curve showed that the benefits of ITT-LDLT occurred within the first month after listing. Perioperative outcomes and 5-year patient survival were comparable for patients with MELD > 25 (88% vs. 85.4%, P = 0.279) and patients with both MELD > 25 and HRS (77% vs. 76.4%, P = 0.701) after LDLT and DDLT, respectively. The LDLT group has a higher rate of renal recovery by 1 month (77.4% vs. 59.1%, P = 0.003) and 3 months (86.1% vs, 74.5%, P = 0.029), whereas the long-term estimated glomerular filtration rate (eGFR) was similar between the 2 groups. ITT-LDLT reduced the hazard of mortality (hazard ratio = 0.387-0.552) across all MELD strata. CONCLUSIONS: The ITT-LDLT reduced waitlist mortality and allowed an earlier access to transplant. LDLT in patients with high MELD/HRS was feasible, and they had similar perioperative outcomes and better renal recovery, whereas the long-term survival and eGFR were comparable with DDLT. LDLT should be considered for patients with high MELD/HRS, and the application of LDLT should not be restricted with a MELD cutoff.


Assuntos
Doença Hepática Terminal , Síndrome Hepatorrenal , Transplante de Fígado , Doadores Vivos/estatística & dados numéricos , China/epidemiologia , Doença Hepática Terminal/epidemiologia , Doença Hepática Terminal/cirurgia , Feminino , Acessibilidade aos Serviços de Saúde/organização & administração , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Síndrome Hepatorrenal/epidemiologia , Síndrome Hepatorrenal/cirurgia , Humanos , Análise de Intenção de Tratamento , Testes de Função Renal/métodos , Testes de Função Renal/estatística & dados numéricos , Transplante de Fígado/efeitos adversos , Transplante de Fígado/métodos , Transplante de Fígado/mortalidade , Masculino , Pessoa de Meia-Idade , Período Perioperatório/efeitos adversos , Recuperação de Função Fisiológica , Estudos Retrospectivos , Medição de Risco , Análise de Sobrevida , Listas de Espera/mortalidade
16.
RNA ; 27(1): 40-53, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33008838

RESUMO

A recent crystal structure of a ribosome complex undergoing partial translocation in the absence of elongation factor EF-G showed disruption of codon-anticodon pairing and slippage of the reading frame by -1, directly implicating EF-G in preservation of the translational reading frame. Among mutations identified in a random screen for dominant-lethal mutations of EF-G were a cluster of six that map to the tip of domain IV, which has been shown to contact the codon-anticodon duplex in trapped translocation intermediates. In vitro synthesis of a full-length protein using these mutant EF-Gs revealed dramatically increased -1 frameshifting, providing new evidence for a role for domain IV of EF-G in maintaining the reading frame. These mutations also caused decreased rates of mRNA translocation and rotational movement of the head and body domains of the 30S ribosomal subunit during translocation. Our results are in general agreement with recent findings from Rodnina and coworkers based on in vitro translation of an oligopeptide using EF-Gs containing mutations at two positions in domain IV, who found an inverse correlation between the degree of frameshifting and rates of translocation. Four of our six mutations are substitutions at positions that interact with the translocating tRNA, in each case contacting the RNA backbone of the anticodon loop. We suggest that EF-G helps to preserve the translational reading frame by preventing uncoupled movement of the tRNA through these contacts; a further possibility is that these interactions may stabilize a conformation of the anticodon that favors base-pairing with its codon.


Assuntos
Escherichia coli/genética , Mudança da Fase de Leitura do Gene Ribossômico , Mutação , Elongação Traducional da Cadeia Peptídica , Fator G para Elongação de Peptídeos/genética , Ribossomos/genética , Anticódon/química , Anticódon/metabolismo , Sítios de Ligação , Códon/química , Códon/metabolismo , Escherichia coli/metabolismo , Histidina/genética , Histidina/metabolismo , Oligopeptídeos/genética , Oligopeptídeos/metabolismo , Fator G para Elongação de Peptídeos/química , Fator G para Elongação de Peptídeos/metabolismo , Ligação Proteica , Domínios Proteicos , Domínios e Motivos de Interação entre Proteínas , Estrutura Secundária de Proteína , RNA Mensageiro , RNA de Transferência , Fases de Leitura , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Ribossomos/metabolismo
17.
Genes (Basel) ; 11(12)2020 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-33261163

RESUMO

Psychosocial stress, especially when chronic or excessive, can increase disease risk and accelerate biological aging. Although the underlying mechanisms are unclear, in vivo studies have associated exposure to stress and glucocorticoid stress hormones with shorter telomere length. However, the extent to which prolonged glucocorticoid exposure can shorten telomeres in controlled experimental settings remains unknown. Using a well-characterized cell line of human fibroblasts that undergo gradual telomere shortening during serial passaging in culture, we show that prolonged exposure (up to 51 days) to either naturalistic levels of the human endogenous glucocorticoid cortisol or the more potent synthetic glucocorticoid dexamethasone is not sufficient to accelerate telomere shortening. While our findings await extension in other cell types and biological contexts, they indicate that the in vivo association of psychosocial stress with telomere shortening is unlikely to be mediated by a direct and universal glucocorticoid effect on telomere length.


Assuntos
Dexametasona/farmacologia , Fibroblastos/efeitos dos fármacos , Hidrocortisona/farmacologia , Encurtamento do Telômero/efeitos dos fármacos , Linhagem Celular , Senescência Celular/efeitos dos fármacos , Fibroblastos/ultraestrutura , Humanos , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Estresse Psicológico , Proteínas de Ligação a Tacrolimo/biossíntese , Proteínas de Ligação a Tacrolimo/genética , Telômero/efeitos dos fármacos , Telômero/ultraestrutura , Regulação para Cima/efeitos dos fármacos
18.
Phys Rev Lett ; 125(12): 123002, 2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-33016768

RESUMO

We measure isotope shifts for five Yb^{+} isotopes with zero nuclear spin on two narrow optical quadrupole transitions ^{2}S_{1/2}→^{2}D_{3/2}, ^{2}S_{1/2}→^{2}D_{5/2} with an accuracy of ∼300 Hz. The corresponding King plot shows a 3×10^{-7} deviation from linearity at the 3σ uncertainty level. Such a nonlinearity can indicate physics beyond the Standard Model (SM) in the form of a new bosonic force carrier, or arise from higher-order nuclear effects within the SM. We identify the quadratic field shift as a possible nuclear contributor to the nonlinearity at the observed scale, and show how the nonlinearity pattern can be used in future, more accurate measurements to separate a new-boson signal from nuclear effects.

19.
J Nucl Med ; 61(1): 89-95, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31519805

RESUMO

The role of radiation-induced bystander effects in radiation therapy remains unclear. With renewed interest in therapy with α-particle emitters, and their potential for sterilizing disseminated tumor cells (DTCs), it is critical to determine the contribution of bystander effects to the overall response so they can be leveraged for maximum clinical benefit. Methods: Female Foxn1nu athymic nude mice were administered 0, 50, or 600 kBq/kg 223RaCl2 to create bystander conditions. At 24 hours after administration, MDA-MB-231 or MCF-7 human breast cancer cells expressing luciferase were injected into the tibial marrow compartment. Tumor burden was tracked weekly via bioluminescence. Results: The MDA-MB-231 xenografts were observed to have a 10-day growth delay in the 600 kBq/kg treatment group only. In contrast, MCF-7 cells had 7- and 65-day growth delays in the 50 and 600 kBq/kg groups, respectively. Histologic imaging of the tibial marrow compartment, α-camera imaging, and Monte Carlo dosimetry modeling revealed DTCs both within and beyond the range of the α-particles emitted from 223Ra in bone for both MCF-7 and MDA-MB-231 cells. Conclusion: Taken together, these results support the participation of 223Ra-induced antiproliferative/cytotoxic bystander effects in delayed growth of DTC xenografts. They indicate that the delay depends on the injected activity and therefore is dose-dependent. They suggest using 223RaCl2 as an adjuvant treatment for select patients at early stages of breast cancer.


Assuntos
Medula Óssea/efeitos da radiação , Neoplasias da Mama/radioterapia , Efeito Espectador/efeitos da radiação , Rádio (Elemento)/uso terapêutico , Partículas alfa , Animais , Medula Óssea/patologia , Linhagem Celular Tumoral , Proliferação de Células , Relação Dose-Resposta à Radiação , Feminino , Fatores de Transcrição Forkhead/metabolismo , Humanos , Imageamento Tridimensional , Células MCF-7 , Camundongos , Camundongos Nus , Método de Monte Carlo , Transplante de Neoplasias , Radiometria , Tíbia/diagnóstico por imagem , Tíbia/patologia , Tomografia Computadorizada por Raios X , Resultado do Tratamento
20.
Curr Cardiol Rep ; 21(9): 98, 2019 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-31352531

RESUMO

PURPOSE OF REVIEW: Heart failure (HF) remains a significant burden to our healthcare system and a leading cause of hospitalizations. Current reactive strategies to treat and manage HF have failed to reduce hospitalizations and improve survival. The CardioMEMS device has recently been demonstrated to improve quality of life in HF and reduce HF-related hospitalizations. Current HF management strategies are reviewed with a particular emphasis on the current role of the CardioMEMS device. RECENT FINDINGS: The CHAMPION trial is the only randomized trial looking at the CardioMEMS device. Patients managed with targeted pulmonary artery pressures resulted in 28% reduction in the primary end-point of HF-related hospitalization at 6 months (HR 0.72, 95% CI 0.60-0.85, p = 0.0002) and 37% reduction during the entire follow-up period, which averaged 15 months (HR 0.63, 95% CI 0.52-0.77, p < 0.0001). The prospective open-label post-approval study recently presented a 58% reduction in HF hospitalizations per patient year (HR 0.42, 95% CI 0.38-0.47, p < 0.0001). Management of HF using the CardioMEMS device has been shown to reduce HF hospitalizations and improve quality of life regardless of ejection fraction. Patients best suited for this device are those with recurrent congestive symptoms despite optimal medical therapy.


Assuntos
Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/terapia , Monitorização Hemodinâmica , Artéria Pulmonar , Monitorização Ambulatorial da Pressão Arterial , Cateterismo de Swan-Ganz , Cateteres de Demora , Insuficiência Cardíaca/cirurgia , Humanos , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto
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