Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 52
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Breast Cancer Res Treat ; 200(2): 237-245, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37209183

RESUMO

PURPOSE: Deep learning techniques, including convolutional neural networks (CNN), have the potential to improve breast cancer risk prediction compared to traditional risk models. We assessed whether combining a CNN-based mammographic evaluation with clinical factors in the Breast Cancer Surveillance Consortium (BCSC) model improved risk prediction. METHODS: We conducted a retrospective cohort study among 23,467 women, age 35-74, undergoing screening mammography (2014-2018). We extracted electronic health record (EHR) data on risk factors. We identified 121 women who subsequently developed invasive breast cancer at least 1 year after the baseline mammogram. Mammograms were analyzed with a pixel-wise mammographic evaluation using CNN architecture. We used logistic regression models with breast cancer incidence as the outcome and predictors including clinical factors only (BCSC model) or combined with CNN risk score (hybrid model). We compared model prediction performance via area under the receiver operating characteristics curves (AUCs). RESULTS: Mean age was 55.9 years (SD, 9.5) with 9.3% non-Hispanic Black and 36% Hispanic. Our hybrid model did not significantly improve risk prediction compared to the BCSC model (AUC of 0.654 vs 0.624, respectively, p = 0.063). In subgroup analyses, the hybrid model outperformed the BCSC model among non-Hispanic Blacks (AUC 0.845 vs. 0.589; p = 0.026) and Hispanics (AUC 0.650 vs 0.595; p = 0.049). CONCLUSION: We aimed to develop an efficient breast cancer risk assessment method using CNN risk score and clinical factors from the EHR. With future validation in a larger cohort, our CNN model combined with clinical factors may help predict breast cancer risk in a cohort of racially/ethnically diverse women undergoing screening.


Assuntos
Neoplasias da Mama , Feminino , Humanos , Pessoa de Meia-Idade , Adulto , Idoso , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/epidemiologia , Mamografia/métodos , Estudos Retrospectivos , Detecção Precoce de Câncer , Redes Neurais de Computação
2.
J Pediatr ; 252: 208-212.e3, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36115623

RESUMO

This study shows that only 12.5% of laboratory reports (2/16) included age-appropriate pediatric reference ranges for all lipid and lipoproteins. The use of erroneous reference range(s) could lead to missed alerts of dyslipidemia in up to 97.3% (total cholesterol), 93.6% (high-density lipoprotein cholesterol), 94.8% (low-density lipoprotein cholesterol), and 87.8% (triglycerides) of youth in the population-based National Health and Nutrition Examination Survey cohort. These findings highlight the potential missed opportunities for reinforcing lifestyle counseling for dyslipidemia in addition to obesity in youth.


Assuntos
Dislipidemias , Adolescente , Criança , Humanos , Inquéritos Nutricionais , Dislipidemias/diagnóstico , HDL-Colesterol , Triglicerídeos , LDL-Colesterol
3.
J Minim Invasive Gynecol ; 30(7): 562-568, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-36921892

RESUMO

STUDY OBJECTIVE: To analyze hysterectomy trends and vaginal cuff dehiscence (VCD) rates by mode of surgery at a tertiary care medical center and to describe characteristics of VCD cases. DESIGN: Observational retrospective cohort study. SETTING: Large academic hospital and affiliated community hospital. PATIENTS: 4722 patients who underwent hysterectomy at Columbia University Irving Medical Center between January 2010 and August 2021. INTERVENTIONS: Current Procedural Terminology and International Classification of Diseases codes identified hysterectomies and VCD cases. Hysterectomy trends and VCD rates were calculated by mode of surgery. Relative risks of VCD for each mode were compared with total abdominal hysterectomy (TAH). Clinical characteristics of VCDs were reviewed. MEASUREMENTS AND MAIN RESULTS: There were 4059 total hysterectomies. Laparoscopic hysterectomies, including total laparoscopic hysterectomies (TLHs), laparoscopic-assisted vaginal hysterectomies, and robot-assisted TLHs (RA-TLHs), increased from 41.9% in 2010 to 65.9% in 2021 (p <.001). RA-TLH increased from 5.7% in 2010 to 40.2% in 2021. Supracervical hysterectomies followed similar trends and were excluded from VCD analysis. There were 15 VCDs (overall rate 0.37%). VCD was highest after RA-TLH (0.66%), followed by TLH (0.32%) and TAH (0.27%), with no VCDs after laparoscopic-assisted vaginal hysterectomy or total vaginal hysterectomy. Compared with TAH, the relative risk for VCD after RA-TLH was 2.44 (95% confidence interval 0.66-9.00) and after TLH was 1.18 (95% confidence interval 0.24-5.83), which were not statistically significant. The mean time to dehiscence was 39 days (range 8-145 days). The most common trigger event was coitus (41%). CONCLUSION: VCD rates were low (<1%) for all modes of hysterectomy, and rates after robotic and laparoscopic hysterectomy were much lower than previously reported. Although VCD rates trended higher after robotic and laparoscopic hysterectomy compared with abdominal hysterectomy, the difference was not significant. It is difficult to determine whether this finding represents true lack of difference vs a lack of power to detect a significant difference given the rarity of VCD.


Assuntos
Laparoscopia , Feminino , Humanos , Estudos Retrospectivos , Laparoscopia/efeitos adversos , Histerectomia/efeitos adversos , Histerectomia Vaginal/efeitos adversos , Vagina/cirurgia
4.
J Gastroenterol Hepatol ; 37(6): 973-982, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35384041

RESUMO

BACKGROUND AND AIM: Humans with inborn errors of immunity (IEI), or primary immunodeficiencies, may be associated with a potential risk factor for early-onset gastrointestinal (GI) cancer. METHODS: We systematically reviewed all cases with clinical diagnoses of both an IEI and a GI cancer in three databases (MEDLINE, SCOPUS, and EMBASE). In total, 76 publications satisfying our inclusion criteria were identified, and data for 149 cases were analyzed. We also searched our institutional cancer registry for such cases. RESULTS: We identified 149 patients with both an IEI and a GI cancer, 95 presented gastric cancer, 13 small bowel cancer, 35 colorectal cancer, and 6 had an unspecified cancer or cancer at another site. Gastric and colon adenocarcinomas were the most common. For both gastric and colorectal cancers, age at onset was significantly earlier in patients with IEIs than in the general population, based on the SEER database. Common variable immunodeficiency (CVID) was the most common IEI associated with gastrointestinal cancer. About 12% of patients had molecular genetic diagnoses, the three most frequently implicated genes being ATM, CARMIL2, and CTLA4. Impaired humoral immunity and Epstein-Barr virus (EBV) infection were frequently reported as factors potentially underlying early-onset GI cancers in patients with IEIs. We identified one patient with CVID and early-onset gastric adenocarcinoma, recurrent diarrhea, and gastrointestinal CMV infection from a retrospective survey. CONCLUSION: Patients with IEIs should be considered at risk of early-onset GI cancers and should therefore undergo cancer screening at an earlier age.


Assuntos
Infecções por Vírus Epstein-Barr , Neoplasias Gastrointestinais , Neoplasias Gástricas , Infecções por Vírus Epstein-Barr/complicações , Neoplasias Gastrointestinais/epidemiologia , Herpesvirus Humano 4 , Humanos , Imunogenética , Estudos Retrospectivos , Neoplasias Gástricas/epidemiologia
5.
J Biomed Inform ; 131: 104095, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35598881

RESUMO

The multi-modal and unstructured nature of observational data in Electronic Health Records (EHR) is currently a significant obstacle for the application of machine learning towards risk stratification. In this study, we develop a deep learning framework for incorporating longitudinal clinical data from EHR to infer risk for pancreatic cancer (PC). This framework includes a novel training protocol, which enforces an emphasis on early detection by applying an independent Poisson-random mask on proximal-time measurements for each variable. Data fusion for irregular multivariate time-series features is enabled by a "grouped" neural network (GrpNN) architecture, which uses representation learning to generate a dimensionally reduced vector for each measurement set before making a final prediction. These models were evaluated using EHR data from Columbia University Irving Medical Center-New York Presbyterian Hospital. Our framework demonstrated better performance on early detection (AUROC 0.671, CI 95% 0.667 - 0.675, p < 0.001) at 12 months prior to diagnosis compared to a logistic regression, xgboost, and a feedforward neural network baseline. We demonstrate that our masking strategy results greater improvements at distal times prior to diagnosis, and that our GrpNN model improves generalizability by reducing overfitting relative to the feedforward baseline. The results were consistent across reported race. Our proposed algorithm is potentially generalizable to other diseases including but not limited to cancer where early detection can improve survival.


Assuntos
Aprendizado Profundo , Neoplasias Pancreáticas , Detecção Precoce de Câncer , Registros Eletrônicos de Saúde , Humanos , Neoplasias Pancreáticas/diagnóstico , Fatores de Tempo , Neoplasias Pancreáticas
6.
Perfusion ; 37(3): 229-234, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-33637027

RESUMO

OBJECTIVE: The COVID-19 pandemic requires thinking about alternatives to establish ECMO when often-limited hardware resources are exhausted. Heart-lung-machines may potentially be used for ECMO but contain roller pumps as compared to centrifugal pumps in ECMO-circuits. We here tested roller pumps as rescue pump for ECMO-establishment. METHODS: We set up in vitro circuits on roller pumps from C5 heart-lung-machine with 5 l/minutes flow. In two series, we placed either PVC or silicon tubing for an ECMO circuit into the roller pump. We assessed the mechanical stress on the tubing (aiming to run the pump for at least 1 week), measured the temperature increase generated by the friction and assessed flow characteristics and its measurement in simulated situations resembling tube kinking and suction. RESULTS: The roller pumps led to expected and unexpected adverse events. PVC tubing burst between 36 and 78 hours, while silicon tubing lasted for at least 7 days. At 7 days, the silicone tubing showed significant signs of roller pump wear visible on the outside. The inside, however, was free of surface irregularities. Using these tubings in a roller pump led to a remarkable increase in circuit temperature (PVC: +12.0°C, silicone +2.9°C). Kinking or suction on the device caused the expected dramatic flow reduction (as assessed by direct measurement) while the roller pump display continued to show the preset flow. The roller pump is therefore not able to reliably determine the true flow rate. CONCLUSION: Roller pumps with silicone tubing but not PVC tubing may be used for running ECMO circuits. Silicone tubing may endure the roller pump shear forces for up to 1 week. Thus, repeated tubing repositioning may be a solution. Circuit heating and substantial limitations in flow detection should increase attention if clinical use in situations of crisis is considered.


Assuntos
COVID-19 , Oxigenação por Membrana Extracorpórea , Oxigenação por Membrana Extracorpórea/efeitos adversos , Humanos , Pulmão , Pandemias , Cloreto de Polivinila , Silício , Silicones
7.
Mol Microbiol ; 113(1): 68-88, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31637787

RESUMO

Chlamydia trachomatis is an obligate intracellular bacteria that undergo dynamic morphologic and physiologic conversions upon gaining an access to a eukaryotic cell. These conversions likely require the detection of key environmental conditions and regulation of metabolic activity. Chlamydia encodes homologs to proteins in the Rsb phosphoregulatory partner-switching pathway, best described in Bacillus subtilis. ORF CT588 has a strong sequence similarity to RsbU cytoplasmic phosphatase domain but also contains a unique periplasmic sensor domain that is expected to control the phosphatase activity. A 1.7 Å crystal structure of the periplasmic domain of the RsbU protein from C. trachomatis (PDB 6MAB) displays close structural similarity to DctB from Vibrio and Sinorhizobium. DctB has been shown, both structurally and functionally, to specifically bind to the tricarboxylic acid (TCA) cycle intermediate succinate. Surface plasmon resonance and differential scanning fluorimetry of TCA intermediates and potential metabolites from a virtual screen of RsbU revealed that alpha-ketoglutarate, malate and oxaloacetate bound to the RsbU periplasmic domain. Substitutions in the putative binding site resulted in reduced binding capabilities. An RsbU null mutant showed severe growth defects which could be restored through genetic complementation. Chemical inhibition of ATP synthesis by oxidative phosphorylation phenocopied the growth defect observed in the RsbU null strain. Altogether, these data support a model with the Rsb system responding differentially to TCA cycle intermediates to regulate metabolism and key differentiation processes.


Assuntos
Proteínas de Bactérias/química , Chlamydia trachomatis/metabolismo , Ciclo do Ácido Cítrico , Monoéster Fosfórico Hidrolases/química , Proteínas de Bactérias/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Domínios Proteicos
8.
Clin Gastroenterol Hepatol ; 19(7): 1402-1409.e1, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33007514

RESUMO

BACKGROUND & AIMS: Our understanding of outcomes and disease time course of COVID-19 in patients with gastrointestinal (GI) symptoms remains limited. In this study we characterize the disease course and severity of COVID-19 among hospitalized patients with gastrointestinal manifestations in a large, diverse cohort from the Unites States. METHODS: This retrospective study evaluated hospitalized individuals with COVID-19 between March 11 and April 28, 2020 at two affiliated hospitals in New York City. We evaluated the association between GI symptoms and death, and also explored disease duration, from symptom onset to death or discharge. RESULTS: Of 2804 patients hospitalized with COVID-19, the 1,084 (38.7%) patients with GI symptoms were younger (aOR for age ≥75, 0.59; 95% CI, 0.45-0.77) and had more co-morbidities (aOR for modified Charlson comorbidity score ≥2, 1.22; 95% CI, 1.01-1.48) compared to those without GI symptoms. Individuals with GI symptoms had better outcomes, with a lower likelihood of intubation (aHR, 0.66; 95% CI, 0.55-0.79) and death (aHR, 0.71; 95% CI, 0.59-0.87), after adjusting for clinical factors. These patients had a longer median disease course from symptom onset to discharge (13.8 vs 10.8 days, log-rank p = .048; among 769 survivors with available symptom onset time), which was driven by longer time from symptom onset to hospitalization (7.4 vs 5.4 days, log-rank P < .01). CONCLUSION: Hospitalized patients with GI manifestations of COVID-19 have a reduced risk of intubation and death, but may have a longer overall disease course driven by duration of symptoms prior to hospitalization.


Assuntos
COVID-19 , Gastroenteropatias/virologia , COVID-19/complicações , COVID-19/diagnóstico , COVID-19/mortalidade , Comorbidade , Feminino , Hospitalização , Humanos , Masculino , Cidade de Nova Iorque , Estudos Retrospectivos
9.
Dig Dis Sci ; 66(12): 4398-4405, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-33479861

RESUMO

BACKGROUND: Gastrointestinal symptoms are common in patients with COVID-19, but prevalence of co-infection with enteric pathogens is unknown. AIMS: This study assessed the prevalence of enteric infections among hospitalized patients with COVID-19. METHODS: We evaluated 4973 hospitalized patients ≥ 18 years of age tested for COVID-19 from March 11 through April 28, 2020, at two academic hospitals. The primary exposure was a positive COVID-19 test. The primary outcome was detection of a gastrointestinal pathogen by PCR stool testing. RESULTS: Among 4973 hospitalized individuals, 311 were tested for gastrointestinal infections (204 COVID-19 positive, 107 COVID-19 negative). Patients with COVID-19 were less likely to test positive compared to patients without COVID-19 (10% vs 22%, p < 0.01). This trend was driven by lower rates of non-C.difficile infections (11% vs 22% in COVID-19 positive vs. negative, respectively, p = 0.04), but not C. difficile infection (5.1% vs. 8.2%, p = 0.33). On multivariable analysis, infection with COVID-19 remained significantly associated with lower odds of concurrent GI infection (aOR 0.49, 95% CI 0.24-0.97), again driven by reduced non-C.difficile infection. Testing for both C.difficile and non-C.difficile enteric infection decreased dramatically during the pandemic. CONCLUSIONS: Pathogens aside from C.difficile do not appear to be a significant contributor to diarrhea in COVID-19 positive patients.


Assuntos
COVID-19/epidemiologia , Clostridioides difficile/isolamento & purificação , Infecções por Clostridium/epidemiologia , Coinfecção , Diarreia/epidemiologia , Adolescente , Adulto , Idoso , COVID-19/diagnóstico , Infecções por Clostridium/diagnóstico , Infecções por Clostridium/microbiologia , Diarreia/diagnóstico , Diarreia/microbiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cidade de Nova Iorque/epidemiologia , Prevalência , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Fatores de Tempo , Adulto Jovem
10.
Thorac Cardiovasc Surg ; 69(8): 703-709, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33882611

RESUMO

BACKGROUND: Heater-cooler devices (HCD) have been implicated in a cardiosurgical contamination scenario causing prosthetic valve endocarditis. AIM: We characterized contamination of new HCDs and assessed the risk of intraoperative microorganism transmission from the HCD to the operating field. METHODS: We initially acquired four new FlexTherm and then four new Maquet HCU40 HCDs and assessed occurrence and speed of microbial contamination (including mycobacteria) assessing swab and water samples from the device. In parallel, we collected repeated samples from different sites in the operating room either by swab sticks or by exposing different sample plates to room air. We also reviewed microbiological results from the hospital and compared them to cardiosurgical wound infections and endocarditis cases. Finally, we simulated cardiosurgical conditions and assessed the devices' ability to expel air to the operative field. RESULTS: All new HCDs were clean before first use. Despite authority-mandated decontamination procedures, microbial growth (Fusarium solani, Sphingomonas paucimobilis, Pseudomonas aeruginosa, Mycobacterium chelonae, and gordonae) was identified in all HCDs over time and could not be permanently eliminated. Four of these mircoorganisms were also found in tap water. However, none of the HCD-organisms were found inside the laminar airflow operating area. Importantly, except for P. aeruginosa, none of the HCD organisms were found in patients with surgical wound infections or endocarditis. HCD-expelled air did not rise more than 40 cm above ground. CONCLUSION: HCDs cannot be expected to remain sterile despite extensive decontamination procedures. However, airborne transmission of microorganisms directly from the HCD to the operating field appears unlikely.


Assuntos
Procedimentos Cirúrgicos Cardíacos , Endocardite Bacteriana , Próteses Valvulares Cardíacas , Procedimentos Cirúrgicos Cardíacos/efeitos adversos , Contaminação de Equipamentos , Humanos , Resultado do Tratamento
11.
J Minim Invasive Gynecol ; 28(7): 1411-1419.e1, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33248312

RESUMO

STUDY OBJECTIVE: The purpose of this study was to assess the impact of the coronavirus disease 2019 (COVID-19) pandemic on surgical volume and emergency department (ED) consults across obstetrics-gynecology (OB-GYN) services at a New York City hospital. DESIGN: Retrospective cohort study. SETTING: Tertiary care academic medical center in New York City. PATIENTS: Women undergoing OB-GYN ED consults or surgeries between February 1, 2020 and April 15, 2020. INTERVENTIONS: March 16 institutional moratorium on elective surgeries. MEASUREMENTS AND MAIN RESULTS: The volume and types of surgeries and ED consults were compared before and after the COVID-19 moratorium. During the pandemic, the average weekly volume of ED consults and gynecology (GYN) surgeries decreased, whereas obstetric (OB) surgeries remained stable. The proportions of OB-GYN ED consults, GYN surgeries, and OB surgeries relative to all ED consults, all surgeries, and all labor and delivery patients were 1.87%, 13.8%, 54.6% in the pre-COVID-19 time frame (February 1-March 15) vs 1.53%, 21.3%, 79.7% in the COVID-19 time frame (March 16-April 15), representing no significant difference in proportions of OB-GYN ED consults (p = .464) and GYN surgeries (p = .310) before and during COVID-19, with a proportionate increase in OB surgeries (p <.002). The distribution of GYN surgical case types changed significantly during the pandemic with higher proportions of emergent surgeries for ectopic pregnancies, miscarriages, and concern for cancer (p <.001). Alternatively, the OB surgery distribution of case types remained relatively constant. CONCLUSION: This study highlights how the pandemic has affected the ways that patients in OB-GYN access and receive care. Institutional policies suspending elective surgeries during the pandemic decreased GYN surgical volume and affected the types of cases performed. This decrease was not appreciated for OB surgical volume, reflecting the nonelective and time-sensitive nature of obstetric care. A decrease in ED consults was noted during the pandemic begging the question "Where have all the emergencies gone?" Although the moratorium on elective procedures was necessary, "elective" GYN surgeries remain medically indicated to address symptoms such as pain and bleeding and to prevent serious medical sequelae such as severe anemia requiring transfusion. As we continue to battle COVID-19, we must not lose sight of those patients whose care has been deferred.


Assuntos
COVID-19 , Emergências/epidemiologia , Procedimentos Cirúrgicos em Ginecologia/estatística & dados numéricos , Procedimentos Cirúrgicos Obstétricos/estatística & dados numéricos , Unidade Hospitalar de Ginecologia e Obstetrícia/estatística & dados numéricos , Adulto , COVID-19/epidemiologia , COVID-19/prevenção & controle , Serviço Hospitalar de Emergência/estatística & dados numéricos , Feminino , Humanos , Cidade de Nova Iorque/epidemiologia , Avaliação de Processos e Resultados em Cuidados de Saúde , Gravidez , Encaminhamento e Consulta/estatística & dados numéricos , Estudos Retrospectivos , SARS-CoV-2
12.
FASEB J ; 33(11): 13002-13013, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31525300

RESUMO

African trypanosomiasis, sleeping sickness in humans or nagana in animals, is a potentially fatal neglected tropical disease and a threat to 65 million human lives and 100 million small and large livestock animals in sub-Saharan Africa. Available treatments for this devastating disease are few and have limited efficacy, prompting the search for new drug candidates. Simultaneous inhibition of the trypanosomal glycerol kinase (TGK) and trypanosomal alternative oxidase (TAO) is considered a validated strategy toward the development of new drugs. Our goal is to develop a TGK-specific inhibitor for coadministration with ascofuranone (AF), the most potent TAO inhibitor. Here, we report on the identification of novel compounds with inhibitory potency against TGK. Importantly, one of these compounds (compound 17) and its derivatives (17a and 17b) killed trypanosomes even in the absence of AF. Inhibition kinetics revealed that derivative 17b is a mixed-type and competitive inhibitor for TGK and TAO, respectively. Structural data revealed the molecular basis of this dual inhibitory action, which, in our opinion, will aid in the successful development of a promising drug to treat trypanosomiasis. Although the EC50 of compound 17b against trypanosome cells was 1.77 µM, it had no effect on cultured human cells, even at 50 µM.-Balogun, E. O., Inaoka, D. K., Shiba, T., Tsuge, C., May, B., Sato, T., Kido, Y., Nara, T., Aoki, T., Honma, T., Tanaka, A., Inoue, M., Matsuoka, S., Michels, P. A. M., Watanabe, Y.-I., Moore, A. L., Harada, S., Kita, K. Discovery of trypanocidal coumarins with dual inhibition of both the glycerol kinase and alternative oxidase of Trypanosoma brucei brucei.


Assuntos
Cumarínicos/farmacologia , Descoberta de Drogas , Glicerol Quinase/antagonistas & inibidores , Proteínas Mitocondriais/antagonistas & inibidores , Oxirredutases/antagonistas & inibidores , Proteínas de Plantas/antagonistas & inibidores , Tripanossomicidas/farmacologia , Trypanosoma brucei brucei/efeitos dos fármacos , Animais , Cumarínicos/química , Glicerol Quinase/metabolismo , Proteínas Mitocondriais/metabolismo , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Trypanosoma brucei brucei/enzimologia
13.
Phys Chem Chem Phys ; 20(18): 12929-12938, 2018 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-29701209

RESUMO

Various amounts of the ionic liquids (ILs) [C1C1Im][Tf2N] and [C8C1Im][Tf2N] were deposited in vacuo by physical vapour deposition (PVD) on single crystalline Ag(111) at room temperature and subsequently monitored by angle-resolved X-ray photoelectron spectroscopy (ARXPS) as a function of time. For very low coverages of up to one closed molecular layer, an initial wetting layer was rapidly formed for both ILs. Deposition of higher amounts of [C1C1Im][Tf2N] revealed an initial three-dimensional film morphology. On the time scale of hours, characteristic changes of the XPS signals were observed. These are interpreted as island spreading and a transformation towards a nearly two dimensional [C1C1Im][Tf2N] film as the final state. In contrast, a film morphology close to 2D was found from the very beginning for [C8C1Im][Tf2N] deposited on Ag(111) demonstrating the influence of the alkyl chain length on the growth kinetics. These studies also highlight the suitability of time-resolved ARXPS for the investigation of IL/solid interfaces, which play a crucial role in IL thin film applications such as in catalysis, sensor, lubrication, and coating technologies.

14.
Biochem Soc Trans ; 45(3): 731-740, 2017 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-28620034

RESUMO

The alternative oxidases (AOXs) are ubiquinol-oxidoreductases that are members of the diiron carboxylate superfamily. They are not only ubiquitously distributed within the plant kingdom but also found in increasing numbers within the fungal, protist, animal and prokaryotic kingdoms. Although functions of AOXs are highly diverse in general, they tend to play key roles in thermogenesis, stress tolerance (through the management of radical oxygen species) and the maintenance of mitochondrial and cellular energy homeostasis. The best structurally characterised AOX is from Trypanosoma brucei In this review, we compare the structure of AOXs, created using homology modelling, from many important species in an attempt to explain differences in activity and sensitivity to AOX inhibitors. We discuss the implications of these findings not only for future structure-based drug design but also for the design of novel AOXs for gene therapy.


Assuntos
Proteínas Mitocondriais/metabolismo , Modelos Moleculares , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Bactérias/metabolismo , Eucariotos/metabolismo , Terapia Genética , Humanos , Proteínas Mitocondriais/antagonistas & inibidores , Proteínas Mitocondriais/química , Oxirredutases/antagonistas & inibidores , Oxirredutases/química , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/química , Estrutura Terciária de Proteína
16.
Angew Chem Int Ed Engl ; 55(2): 728-31, 2016 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-26592861

RESUMO

Complex I is a crucial respiratory enzyme that conserves the energy from NADH oxidation by ubiquinone-10 (Q10) in proton transport across a membrane. Studies of its energy transduction mechanism are hindered by the extreme hydrophobicity of Q10, and they have so far relied on native membranes with many components or on hydrophilic Q10 analogues that partition into membranes and undergo side reactions. Herein, we present a self-assembled system without these limitations: proteoliposomes containing mammalian complex I, Q10, and a quinol oxidase (the alternative oxidase, AOX) to recycle Q10H2 to Q10. AOX is present in excess, so complex I is completely rate determining and the Q10 pool is kept oxidized under steady-state catalysis. The system was used to measure a fully-defined K(M) value for Q10. The strategy is suitable for any enzyme with a hydrophobic quinone/quinol substrate, and could be used to characterize hydrophobic inhibitors with potential applications as pharmaceuticals, pesticides, or fungicides.


Assuntos
Complexo I de Transporte de Elétrons/química , Proteínas Mitocondriais/química , NAD/química , Oxirredutases/química , Proteínas de Plantas/química , Ubiquinona/química , Catálise , Transporte de Elétrons , Oxirredução
17.
Biochim Biophys Acta ; 1837(7): 1219-25, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24530866

RESUMO

In the present paper we have investigated the effect of mutagenesis of a number of highly conserved residues (R159, D163, L177 and L267) which we have recently shown to line the hydrophobic inhibitor/substrate cavity in the alternative oxidases (AOXs). Measurements of respiratory activity in rSgAOX expressed in Escherichia coli FN102 membranes indicate that all mutants result in a decrease in maximum activity of AOX and in some cases (D163 and L177) a decrease in the apparent Km (O2). Of particular importance was the finding that when the L177 and L267 residues, which appear to cause a bottleneck in the hydrophobic cavity, are mutated to alanine the sensitivity to AOX antagonists is reduced. When non-AOX anti-malarial inhibitors were also tested against these mutants widening the bottleneck through removal of isobutyl side chain allowed access of these bulkier inhibitors to the active-site and resulted in inhibition. Results are discussed in terms of how these mutations have altered the way in which the AOX's catalytic cycle is controlled and since maximum activity is decreased we predict that such mutations result in an increase in the steady state level of at least one O2-derived AOX intermediate. Such mutations should therefore prove to be useful in future stopped-flow and electron paramagnetic resonance experiments in attempts to understand the catalytic cycle of the alternative oxidase which may prove to be important in future rational drug design to treat diseases such as trypanosomiasis. Furthermore since single amino acid mutations in inhibitor/substrate pockets have been found to be the cause of multi-drug resistant strains of malaria, the decrease in sensitivity to main AOX antagonists observed in the L-mutants studied in this report suggests that an emergence of drug resistance to trypanosomiasis may also be possible. Therefore we suggest that the design of future AOX inhibitors should have structures that are less reliant on the orientation by the two-leucine residues. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.


Assuntos
Araceae/enzimologia , Proteínas Mitocondriais/metabolismo , Mutação de Sentido Incorreto , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Ubiquinona/análogos & derivados , Sequência de Aminoácidos , Sítios de Ligação , Membrana Celular/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Mitocondriais/antagonistas & inibidores , Proteínas Mitocondriais/química , Proteínas Mitocondriais/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oxirredutases/antagonistas & inibidores , Oxirredutases/química , Oxirredutases/genética , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Terpenos/farmacologia , Ubiquinona/metabolismo
18.
Acad Radiol ; 31(3): 1141-1147, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37863781

RESUMO

RATIONALE AND OBJECTIVES: Given the immense time and energy radiologists dedicate to their profession, the experience at work should be a major contributor to a meaningful and fulfilling life. In pursuit of this vision, our department launched a novel faculty development workshop entitled "Thriving In and Out of the Reading Room: What They Didn't Teach Us in Training." We report on the design, implementation and initial outcomes of this faculty development workshop. MATERIALS AND METHODS: The workshop drew upon positive psychology research and the PERMA model of well-being, which encompasses five key elements: Positive emotion, Engagement, Relationships, Meaning, and Achievement. These elements have been shown to enhance work satisfaction and foster resilience. Using interactive, small group exercises, the workshop provided strategies for incorporating PERMA elements into daily life. At the conclusion of each workshop, an anonymous voluntary electronic survey was distributed to participants. RESULTS: The final version of the workshop was offered to 58 faculty over eight sessions between September 2022 and May 2023. Survey results indicate that participants found the workshop to be highly valuable and practical. They also found the workshop to promote camaraderie and peer learning. Developing the workshop internally allowed us to customize it to our faculty's unique experiences and engage a large number of participants. CONCLUSION: The workshop shows promise in improving job satisfaction and addressing burnout among academic radiologists.


Assuntos
Esgotamento Profissional , Docentes , Humanos , Radiologistas , Esgotamento Profissional/prevenção & controle , Satisfação no Emprego , Inquéritos e Questionários
19.
bioRxiv ; 2024 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-38464108

RESUMO

HELB is a human helicase involved in initiation of DNA replication, the replication stress response, and regulation of double-strand DNA break repair. rs75770066 is a rare SNP in the HELB gene that affects age at natural menopause. rs75770066 results in a D506G substitution in an acidic patch within the 1A domain of the helicase that is known to interact with RPA. We found that this amino acid change dramatically impairs the cellular function of HELB. D506G-HELB exhibits impaired interaction with RPA, which likely results in the effects of rs75770066 as this reduces recruitment of HELB to sites of DNA damage. Reduced recruitment of D506G-HELB to double-strand DNA breaks and the concomitant increase in homologous recombination likely alters the levels of meiotic recombination, which affects the viability of gametes. Because menopause occurs when oocyte levels drop below a minimum threshold, altered repair of meiotic double-stranded DNA breaks has the potential to directly affect the age at natural menopause.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA