RESUMO
Human APOBEC3H and homologous single-stranded DNA cytosine deaminases are unique to mammals. These DNA-editing enzymes function in innate immunity by restricting the replication of viruses and transposons. APOBEC3H also contributes to cancer mutagenesis. Here, we address the fundamental nature of RNA in regulating human APOBEC3H activities. APOBEC3H co-purifies with RNA as an inactive protein, and RNase A treatment enables strong DNA deaminase activity. RNA-binding-defective mutants demonstrate clear separation of function by becoming DNA hypermutators. Biochemical and crystallographic data demonstrate a mechanism in which double-stranded RNA mediates enzyme dimerization. Additionally, APOBEC3H separation-of-function mutants show that RNA binding is required for cytoplasmic localization, packaging into HIV-1 particles, and antiviral activity. Overall, these results support a model in which structured RNA negatively regulates the potentially harmful DNA deamination activity of APOBEC3H while, at the same time, positively regulating its antiviral activity.
Assuntos
Aminoidrolases/metabolismo , Dimerização , HIV-1/crescimento & desenvolvimento , Montagem de Vírus/genética , Aminoidrolases/genética , Linhagem Celular Tumoral , Cristalografia por Raios X , Citosina Desaminase/metabolismo , Células HEK293 , Células HeLa , Humanos , Estrutura Secundária de Proteína , RNA/genética , RNA/metabolismo , Proteínas de Ligação a RNA/genética , Ribonuclease Pancreático/metabolismoRESUMO
INTRODUCTION: Weight loss after bariatric surgery is impacted by several factors, and social support is one of them. Our objective was to characterize patient and provider perceptions about social support after bariatric surgery. METHODS: We reported a secondary analysis of qualitative data acquired from semi-structured interviews conducted from January-November 2020 with bariatric surgery patients and providers. Participants included primary care providers, health psychologists, registered dietitians, bariatric surgeons, and patients with at least 1 y of follow-up after their bariatric procedure. Interview guides were designed using a hybrid of Andersen's Behavioral Model of Health Services and Torain's Framework for Surgical Disparities. Using directed content analysis, study team members generated codes, which were categorized into themes about social support pertaining to dietary habits, physical activity, and follow-up care. RESULTS: Forty-five participants were interviewed, including 24 patients (83% female; 79% White; mean age 50.6 ± 10.7 y) and 21 providers (six primary care providers, four health psychologists, five registered dieticians, and six bariatric surgeons). We identified four themes relating to social support affecting weight loss after surgery: (1) family involvement in helping patients adjust to the bariatric diet, (2) engagement in activities with partners/friends, (3) help with transportation to appointments, and (4) life stressors experienced by patients within their social relationships. CONCLUSIONS: Continued assessment of interpersonal factors after bariatric surgery is essential for weight loss maintenance. Providers can contribute by reinforcing the facilitators of social support and making referrals that may help patients overcome barriers to social support for sustained weight loss after surgery.
Assuntos
Cirurgia Bariátrica , Apoio Social , Redução de Peso , Humanos , Cirurgia Bariátrica/psicologia , Feminino , Masculino , Pessoa de Meia-Idade , Adulto , Pesquisa Qualitativa , Entrevistas como AssuntoRESUMO
BACKGROUND: Careful patient selection is critical when considering cytoreductive nephrectomy (CN) for metastatic renal cell carcinoma (mRCC) but few studies have investigated the prognostic value of radiologic features that measure tumor burden. OBJECTIVE: To develop a prognostic model to improve CN selection with integration of common radiologic features with known prognostic factors associated with mortality in the first year following surgery. DESIGN, SETTINGS, AND PARTICIPANTS: Data were analyzed for consecutive patients with mRCC treated with upfront CN at five institutions from 2006 to 2017. Univariable and multivariable models were used to evaluate radiographic features and known risk factors for associations with overall survival. Relevant factors were used to create the SCREEN model and compared to the International mRCC Database Consortium (IMDC) model for predictive accuracy and clinical usefulness. RESULTS AND LIMITATIONS: A total of 914 patients with mRCC were treated with upfront CN during the study period. Seven independently predictive variables were used in the SCREEN score: three or more metastatic sites, total metastatic tumor burden ≥5 cm, bone metastasis, systemic symptoms, low serum hemoglobin, low serum albumin, and neutrophil/lymphocyte ratio ≥4. Predictive accuracy measured as the area under the receiver operating characteristic curves was 0.76 for the SCREEN score and 0.55 for the IMDC model. Decision curve analysis showed that the SCREEN model was useful beyond the IMDC classifier for threshold first-year mortality probabilities between 15% and 70%. CONCLUSIONS: The SCREEN score had higher predictive accuracy for first-year mortality compared to the IMDC scheme in a multi-institutional cohort and may be used to improve CN selection. PATIENT SUMMARY: This study provides a model to improve selection of patients with metastatic kidney cancer who may benefit from surgical removal of the primary kidney tumor. We found that radiographic measurements of the tumor burden predicted the risk of death in the first year after surgery. The model can be used to improve decision-making by these patients and their physicians.
Assuntos
Carcinoma de Células Renais , Neoplasias Renais , Humanos , Carcinoma de Células Renais/diagnóstico por imagem , Carcinoma de Células Renais/cirurgia , Carcinoma de Células Renais/tratamento farmacológico , Neoplasias Renais/diagnóstico por imagem , Neoplasias Renais/cirurgia , Procedimentos Cirúrgicos de Citorredução/métodos , Estudos Retrospectivos , Nefrectomia/métodos , Medição de RiscoRESUMO
OBJECTIVE: The resident-attending dyad influences the intraoperative training of surgery residents. To better understand the role of trainees within the dyad, we hypothesized there is a measurable concept of "teachability," a combination of the trainee's observed skills and behaviors with their performance. This study aims to define teachability and identify discrete intraoperative behaviors that contribute to this concept. We posit that residents who are active learners as demonstrated by asking questions, proposing next steps, and initiating purposeful actions have higher teachability. DESIGN, SETTING, PARTICIPANTS: Previously recorded videos from 26 laparoscopic inguinal hernia repairs performed by two PGY-5 general surgery residents at a Midwest tertiary care center were qualitatively reviewed for intraoperative behaviors. A summative content analysis identified behaviors associated with increased teachability and improved operative performance assessment scores. RESULTS: Average frequencies of intraoperative behaviors for resident 1 and 2 (R1 and R2) were not significantly different, although R2 asked more medical knowledge and technical questions. While the rate of attending feedback was similar for both residents (x=3.82 vs 3.40, p=0.646), R1 consistently incorporated feedback (x=2.27 vs 0.40, p=0.001) whereas R2 needed frequent prompting (x=2.45 vs 1.55, p=0.239). R1 scored higher in all but one operative performance assessment category, including overall performance (x=4.17 vs 2.93, p=0.007), but R2 had a larger magnitude of overall improvement (+1 vs +2). CONCLUSIONS: Teachability is a dynamic component of the resident-attending dyad. While intraoperative active learning behaviors do not appear to be associated with teachability, asking questions may increase the magnitude of improvement in performance. Most importantly, the ability to incorporate intraoperative feedback in real time seems to be a critical aspect of teachability and warrants further research.
Assuntos
Cirurgia Geral , Internato e Residência , Centros de Atenção Terciária , Competência Clínica , Cirurgia Geral/educaçãoRESUMO
As many as five members of the APOBEC3 family of DNA cytosine deaminases are capable of inhibiting HIV-1 replication by deaminating viral cDNA cytosines and interfering with reverse transcription. HIV-1 counteracts restriction with the virally encoded Vif protein, which forms a hybrid ubiquitin ligase complex that directly binds APOBEC3 enzymes and targets them for proteasomal degradation. APOBEC3H (A3H) is unique among family members by dimerization through cellular and viral duplex RNA species. RNA binding is required for localization of A3H to the cytoplasmic compartment, for efficient packaging into nascent HIV-1 particles and ultimately for effective virus restriction activity. Here we compared wild-type human A3H and RNA binding-defective mutants to ask whether RNA may be a factor in the functional interaction with HIV-1 Vif. We used structural modeling, immunoblotting, live cell imaging, and split green fluorescence protein (GFP) reconstitution approaches to assess the capability of HIV-1 Vif to promote the degradation of wild-type A3H in comparison to RNA binding-defective mutants. The results combined to show that RNA is not strictly required for Vif-mediated degradation of A3H, and that RNA and Vif are likely to bind this single-domain DNA cytosine deaminase on physically distinct surfaces. However, a subset of the results also indicated that the A3H degradation process may be affected by A3H protein structure, subcellular localization, and differences in the constellation of A3H interaction partners, suggesting additional factors may also influence the fate and functionality of this host-pathogen interaction.