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1.
J Nucl Med ; 2024 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-38664014

RESUMEN

Prostate-specific membrane antigen (PSMA) is frequently overexpressed in nonprostate malignancies. This preclinical study investigated the molecular basis of the application of PMSA-targeting radiopharmaceuticals in breast cancer subtypes. Methods: The somatic copy number status and the transcriptomic and protein expressions of FOLH1 (gene name of PSMA) were analyzed across breast cancer subtypes in 998 patients from The Cancer Genome Atlas dataset. Results: FOLH1 was frequently amplified in basallike breast cancer (BLBC) (32%) compared with luminal and human epidermal growth factor receptor 2-positive subtypes (16% and 17%, respectively; P < 0.01). FOLH1 expression was higher in BLBC (P < 0.001) and was negatively correlated with estrogen-receptor and progesterone-receptor expressions. Consistently, the PSMA protein level was higher in BLBC (P < 0.05). Interestingly, FOLH1 expression was associated with relapse-free and distant metastasis-free survival in patients with BLBC. Conclusion: The BLBC subtype exhibited frequent amplification and overexpression of PSMA, supporting the exploration of PSMA-targeting radiopharmaceuticals in this aggressive breast cancer subtype.

2.
J Am Coll Radiol ; 19(2 Pt A): 281-287, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-35094940

RESUMEN

Learn Serve Lead (LSL) is the signature annual conference of the Association of American Medical Colleges (AAMC), which focuses on the most pressing issues facing American medical practice and education. Unsurprisingly, the recent AAMC LSL conference at the end of 2020 centered on the multifaceted impacts of the COVID-19 pandemic and racial inequity upon the medical community. At the LSL meeting, national leaders, practicing physicians from diverse specialties, and medical trainees discussed the impact of these challenges and ongoing strategies to overcome them. These efforts paralleled the AAMC mission areas of community collaborations, medical education, clinical care, and research. Additionally, this focus aligns with the ACR's core purpose: to serve patients and society by empowering members to advance the practice, science, and professions of radiological care. ACR is a member of the AAMC Council of Faculty and Academic Society and seeks to collaborate with other medical specialties to promote interdisciplinary collaboration, contribute to medical education, and voice the value of medical imaging for patient care. We summarize the major insights of this interdisciplinary conference and present tailored recommendations for applying these insights specifically within the radiology community. In addition, we review the parallels between the ACR and the AAMC strategic plans.


Asunto(s)
Educación Médica , Equidad en Salud , COVID-19/epidemiología , Humanos , Pandemias , Estados Unidos/epidemiología
3.
J Vasc Interv Radiol ; 32(4): 544-547, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-33795074

RESUMEN

This report evaluates the techniques and complications of microwave ablation of cystic renal cell carcinoma. Five patients with cystic renal cell carcinoma were treated with microwave ablation between October 2015 and June 2020. Medical records were reviewed to evaluate technique and complications. Technical success and primary technique efficacy both were 100%. There were no complications. Mean follow-up time was 18 months (range, 6-36 months). No local recurrence was identified during the follow-up period. Renal function remained stable at 1 month and the last follow-up. Percutaneous microwave ablation is promising for the nonsurgical management of cystic renal cell carcinoma.


Asunto(s)
Técnicas de Ablación , Carcinoma de Células Renales/cirugía , Neoplasias Renales/cirugía , Microondas/uso terapéutico , Neoplasias Quísticas, Mucinosas y Serosas/cirugía , Radiografía Intervencional , Cirugía Asistida por Computador , Tomografía Computarizada por Rayos X , Técnicas de Ablación/efectos adversos , Anciano , Anciano de 80 o más Años , Carcinoma de Células Renales/diagnóstico por imagen , Carcinoma de Células Renales/patología , Femenino , Humanos , Neoplasias Renales/diagnóstico por imagen , Neoplasias Renales/patología , Masculino , Microondas/efectos adversos , Neoplasias Quísticas, Mucinosas y Serosas/diagnóstico por imagen , Neoplasias Quísticas, Mucinosas y Serosas/patología , Valor Predictivo de las Pruebas , Radiografía Intervencional/efectos adversos , Estudios Retrospectivos , Cirugía Asistida por Computador/efectos adversos , Factores de Tiempo , Resultado del Tratamiento
5.
AJR Am J Roentgenol ; 216(4): 989-996, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-32755206

RESUMEN

BACKGROUND. Obesity is a worldwide problem that impacts patient health as well as the morbidity associated with surgical procedures. Thus, patients with morbid obesity may not be suitable candidates for curative surgery. For this patient population, thermal ablation may be an effective alternative to nephrectomy. OBJECTIVE. The purpose of this study was to determine the feasibility, oncologic outcomes, and survival of patients with morbid obesity and renal cell carcinoma treated with thermal ablation. MATERIALS AND METHODS. A retrospective analysis was performed of 107 patients treated with CT-guided renal ablation for clinical T1 renal cell carcinoma between February 2005 and December 2017. Patients were stratified into two cohorts on body mass index of ≥ 40 kg/m2 (morbidly obese) and body mass index (weight in kilograms divided by the square of height in meters) of ≥ 40 (morbidly obese) and 18.5-24.9 (normal weight). Anesthetic and radiation dosages, procedure time, residual disease, and local recurrence, and adverse events were analyzed between the two groups. Kaplan-Meier statistics were used to evaluate cancer-related outcomes for each group. RESULTS. Thirty-four patients were morbidly obese, and 73 patients had normal weight. Morbid obesity was associated with longer procedural duration (p = .001), sedative doses (p = .002) and radiation exposure (p = .001) than normal weight. Hematomas were more prevalent in patients with morbid obesity than in those of normal weight (p = .01), but treatment efficacy and local recurrences were comparable with those for normal-weight individuals (p = .81 and p = .12, respectively). Cancer-related outcomes were equivalent between the two groups based on 5 years of imaging observation data. CONCLUSION. CT-guided thermal ablation remains technically feasible, well-tolerated, and effective in patients with morbid obesity and renal cell carcinoma, with the caveat of increased risk of perinephric hematoma, anesthesia dose, and radiation exposure. CLINICAL IMPACT. CT-guided thermal ablation can be considered a safe and effective treatment for renal cell carcinoma in patients with morbid obesity.


Asunto(s)
Técnicas de Ablación/métodos , Carcinoma de Células Renales/cirugía , Neoplasias Renales/cirugía , Obesidad Mórbida/complicaciones , Anciano , Índice de Masa Corporal , Carcinoma de Células Renales/complicaciones , Femenino , Humanos , Estimación de Kaplan-Meier , Neoplasias Renales/complicaciones , Masculino , Estudios Retrospectivos , Resultado del Tratamiento
6.
J Vasc Interv Radiol ; 32(1): 33-38, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33308948

RESUMEN

PURPOSE: To determine effect of body mass index (BMI) on safety and cancer-related outcomes of thermal ablation for renal cell carcinoma (RRC). MATERIALS AND METHODS: This retrospective study evaluated 427 patients (287 men and 140 women; mean [SD] age, 72 [12] y) who were treated with thermal ablation for RCC between October 2006 and December 2017. Patients were stratified by BMI into 3 categories: normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (≥ 30 kg/m2). Of 427 patients, 71 (16%) were normal weight, 157 (37%) were overweight, and 199 (47%) were obese. Complication rates, local recurrence, and residual disease were compared in the 3 cohorts. RESULTS: No differences in technical success between normal-weight, overweight, and obese patients were identified (P = .72). Primary technique efficacy rates for normal-weight, overweight, and obese patients were 91%, 94%, and 93% (P = .71). There was no significant difference in RCC specific-free survival, disease-free survival, and metastasis-free survival between obese, overweight, and normal-weight groups (P = .72, P = .43, P = .99). Complication rates between the 3 cohorts were similar (normal weight 4%, overweight 2%, obese 3%; P = .71). CONCLUSIONS: CT-guided renal ablation is safe, feasible, and effective regardless of BMI.


Asunto(s)
Índice de Masa Corporal , Carcinoma de Células Renales/cirugía , Criocirugía , Neoplasias Renales/cirugía , Microondas/uso terapéutico , Obesidad/diagnóstico , Ablación por Radiofrecuencia , Anciano , Anciano de 80 o más Años , Carcinoma de Células Renales/mortalidad , Carcinoma de Células Renales/secundario , Criocirugía/efectos adversos , Criocirugía/mortalidad , Progresión de la Enfermedad , Supervivencia sin Enfermedad , Femenino , Humanos , Neoplasias Renales/mortalidad , Neoplasias Renales/patología , Masculino , Microondas/efectos adversos , Persona de Mediana Edad , Recurrencia Local de Neoplasia , Obesidad/mortalidad , Seguridad del Paciente , Ablación por Radiofrecuencia/efectos adversos , Ablación por Radiofrecuencia/mortalidad , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Factores de Tiempo , Resultado del Tratamiento
7.
J Vasc Interv Radiol ; 30(7): 1035-1042, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-30956075

RESUMEN

PURPOSE: To compare the therapeutic and renal function outcomes of radiofrequency (RF) ablation, cryoablation, and microwave (MW) ablation for treatment of T1a renal cell carcinoma (RCC). MATERIALS AND METHODS: A retrospective assessment of 297 patients (mean age 72 years range 24-90 years) with biopsy-proven RCC treated with image-guided percutaneous thermal ablation was performed between October 2006 and December 2016. Mean tumor size was 2.4 cm; mean radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, hilar tumor touching the main renal artery or vein, and location relative to polar lines; Preoperative Aspects and Dimensions Used for an Anatomical; and c-centrality scores were 6.0, 7.0, and 2.8, respectively. Assessments of adverse events, treatment efficacy, and therapeutic outcomes were performed among RF ablation, cryoablation, and MW ablation. The 2-year disease-free, metastatic-free, and cancer-specific survival rates were tabulated. Estimated glomerular filtration rate was used to assess for treatment related changes in renal function. RESULTS: A total of 297 T1aN0M0 biopsy-proven RCCs measuring 1.2-3.9 cm were treated with computed tomography-guided RF ablation (n = 244, 82%), cryoablation (n = 26, 9%), and MW ablation (n = 27, 9%). There were no significant differences in patient demographics among the 3 groups (P = .09). Technical success rates were similar among the 3 treatments (P = .33). Primary efficacy at 1 month postablation was more likely to be achieved with RF ablation and MW ablation than with cryoablation. At 2 years' follow-up, there was no local recurrence, metastatic progression, or RCC-related death observed in the 3 groups. There was no significant change in estimated glomerular filtration rate among the 3 ablation groups compared with baseline at 2-year follow-up (P = .71). CONCLUSION: RF ablation, cryoablation, and MW ablation are equivalent at 2 years for treatment of T1a RCC for therapeutic outcome, stability of renal function, and low adverse event rate.


Asunto(s)
Carcinoma de Células Renales/cirugía , Criocirugía , Tasa de Filtración Glomerular , Neoplasias Renales/cirugía , Microondas/uso terapéutico , Ablación por Radiofrecuencia , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Células Renales/diagnóstico por imagen , Carcinoma de Células Renales/mortalidad , Carcinoma de Células Renales/secundario , Criocirugía/efectos adversos , Criocirugía/mortalidad , Supervivencia sin Enfermedad , Femenino , Humanos , Neoplasias Renales/diagnóstico por imagen , Neoplasias Renales/mortalidad , Neoplasias Renales/patología , Masculino , Microondas/efectos adversos , Persona de Mediana Edad , Ablación por Radiofrecuencia/efectos adversos , Ablación por Radiofrecuencia/mortalidad , Estudios Retrospectivos , Factores de Riesgo , Factores de Tiempo , Carga Tumoral , Adulto Joven
8.
J Vasc Interv Radiol ; 29(12): 1685-1691, 2018 12.
Artículo en Inglés | MEDLINE | ID: mdl-30297311

RESUMEN

PURPOSE: To assess safety and renal-function outcomes after microwave (MW) ablation of localized stage T1 renal cell carcinoma (RCC). MATERIALS AND METHODS: A retrospective review was conducted of 38 patients (28 men; mean age, 69 y; range, 51-88 y) who underwent computed tomography (CT)-guided MW ablation for stage T1N0M0 RCC. Baseline and follow-up renal function surrogates including creatinine level and estimated glomerular filtration rate (eGFR) were statistically compared. Peri- and postoperative complication rates, technical success, and treatment response were also assessed. RESULTS: A total of 44 biopsy-proven stage T1N0M0 RCCs measuring 1.2-6.9 cm (mean, 2.5 cm) were treated, and renal function was measured 1 mo after treatment. Mean eGFRs were 60 mL/min/1.73 m2 at baseline and 59 mL/min/1.73 m2 at 1 month after ablation. At 1-year and last follow-ups, the means of difference were 3.3% (95% confidence interval, -4.4 to 4.3; P = .99) and 3.3% (95% confidence interval, -4.3 to 4.8; P = .91), respectively. The 2-years freedom from eGFR decrease to < 60 mL/min/1.73 m2 was 2% (P = .91). Among the 5 patients (13%) with preexisting stage 4 chronic kidney disease (CKD; eGFR < 30 mL/min/1.73 m2) before ablation, there was no significant postablative onset of decline or CKD upstaging (P = .001). There were no major complications, and 5 patients (13%) had small asymptomatic perinephric hematomas (Society of Interventional Radiology minor complication, class A/B) that were managed conservatively. CONCLUSIONS: At 2-year follow-up, CT-guided percutaneous MW ablation is safe and well-tolerated and achieves nephron preservation similar to existing ablative modalities.


Asunto(s)
Técnicas de Ablación/efectos adversos , Carcinoma de Células Renales/cirugía , Neoplasias Renales/cirugía , Microondas/efectos adversos , Insuficiencia Renal Crónica/etiología , Anciano , Anciano de 80 o más Años , Biomarcadores/sangre , Carcinoma de Células Renales/diagnóstico por imagen , Carcinoma de Células Renales/patología , Creatinina/sangre , Femenino , Tasa de Filtración Glomerular , Humanos , Neoplasias Renales/diagnóstico por imagen , Neoplasias Renales/patología , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Supervivencia sin Progresión , Radiografía Intervencional/efectos adversos , Insuficiencia Renal Crónica/diagnóstico , Insuficiencia Renal Crónica/fisiopatología , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Factores de Tiempo , Tomografía Computarizada por Rayos X/efectos adversos
9.
Cardiovasc Intervent Radiol ; 41(11): 1743-1750, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-29721615

RESUMEN

PURPOSE: To assess the feasibility, safety and clinical outcomes of image-guided percutaneous thermal ablation as salvage therapy for local recurrence of renal cell carcinoma (RCC) in patients initially treated surgically with curative intent. MATERIALS AND METHODS: A retrospective review of 11 consecutive patients (M/F = 8:3, mean age = 76 years) who underwent computed tomography (CT)-guided thermal ablation for locally recurrent RCC after partial (72%, 8/11) or radical nephrectomy (28%, 3/11) with a mean time to recurrence of 48 months (range 2-156). Assessment of technical success, complication (peri- and post-procedural), oncological outcome and survival analysis were performed. Patient baseline and follow-up renal function surrogates including creatinine level (Cr) and estimated glomerular filtration rate (eGFR) were statistically compared. RESULTS: Eleven biopsy-proven recurrent RCC measuring 1.4-3.9 cm (mean = 2.8 cm) were treated with CT-guided thermal ablation. Technical success was achieved in 100% (11/11) of the cases. There were no major complications except for one (9%) asymptomatic hemorrhage (Clavien-Dindo grade I complication). Complete response, local progression-free and overall survival rate were 91, 91 and 82% during the mean follow-up time of 2.5 years (range 0.1-7.1). Renal function was overall stable without significant change at 1 month and last follow-up (p = 0.21; GFR, p = 0.10; creatinine). CONCLUSIONS: Image-guided percutaneous thermal ablation is a feasible, safe and effective for local recurrence after nephrectomy, representing a non-surgical alternative for unresectable disease.


Asunto(s)
Carcinoma de Células Renales/cirugía , Ablación por Catéter/métodos , Neoplasias Renales/cirugía , Recurrencia Local de Neoplasia/cirugía , Nefrectomía , Cirugía Asistida por Computador/métodos , Tomografía Computarizada por Rayos X/métodos , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Células Renales/mortalidad , Carcinoma de Células Renales/patología , Estudios de Factibilidad , Femenino , Humanos , Pruebas de Función Renal , Neoplasias Renales/mortalidad , Neoplasias Renales/patología , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/mortalidad , Recurrencia Local de Neoplasia/patología , Nefrectomía/métodos , Reoperación , Estudios Retrospectivos , Terapia Recuperativa , Análisis de Supervivencia , Resultado del Tratamiento
10.
Biochem Biophys Res Commun ; 488(1): 153-158, 2017 06 17.
Artículo en Inglés | MEDLINE | ID: mdl-28483525

RESUMEN

The opportunistic pathogen Candida albicans forms invasive filaments that grow into host tissues during disease. The glycosylated, integral plasma membrane protein Dfi1 is important for invasive filamentation in a laboratory model, and for lethality in murine disseminated candidiasis. However, Dfi1 topology and essential domains for Dfi1 biogenesis were undefined. Sequence analysis predicted that Dfi1 contains two transmembrane regions, located near the N- and C-termini. In this communication, we show that Dfi1 remains an integral membrane protein despite deletion of either predicted transmembrane region, whereas deletion of both regions results in a soluble protein. Additionally, Dfi1 that was properly oriented in the membrane, as indicated by N-linked glycosylation, was observed when either transmembrane region was deleted, but was absent when both transmembrane regions were deleted. Interestingly, deletion of the N-terminal transmembrane region resulted in production of two forms of Dfi1. Most of the protein molecules acquired normal N-linked glycosylation and a smaller population failed to become normally N-linked glycosylated. This defect was reversed by replacement of the N-terminal hydrophobic sequence with one synthetic transmembrane sequence but not another. Finally, microscopy studies revealed that Dfi1 lacking the N-terminal transmembrane region was observed at the cell periphery, where full-length Dfi1 normally localizes, whereas the double-truncation mutant was diffusely intracellular. Therefore, mature Dfi1 protein contains two transmembrane domains which contribute to its biogenesis.


Asunto(s)
Candida albicans/metabolismo , Proteínas Fúngicas/biosíntesis , Proteínas Fúngicas/química , Proteínas de la Membrana/biosíntesis , Proteínas de la Membrana/química , Candida albicans/química , Candida albicans/genética , Proteínas Fúngicas/genética , Proteínas de la Membrana/genética
11.
J Am Coll Radiol ; 14(2): 242-246, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28161025

RESUMEN

PURPOSE: The first participants in the independent interventional radiology (IR) residency match will begin prerequisite diagnostic radiology (DR) residencies before the anticipated launch of the independent IR programs in 2020. The aim of this study was to estimate the competitiveness level of the first independent IR residency matches before these applicants have already committed to DR residencies and possibly early specialization in IR (ESIR) programs. METHODS: The Society of Chairs of Academic Radiology Departments (SCARD) Task Force on the IR Residency distributed a survey to all active SCARD members using SurveyMonkey. The survey requested the number of planned IR residency and ESIR positions. The average, minimum, and maximum of the range of planned independent IR residency positions were compared with the average, maximum, and minimum, respectively, of the range of planned ESIR positions, to model matches of average, high, and low competitiveness. RESULTS: Seventy-four active SCARD members (56%) answered at least one survey question. The respondents' programs planned to fill, in total, 98 to 102 positions in integrated IR residency programs, 61 to 76 positions in independent IR residency programs, and 50 to 77 positions in ESIR DR residency programs each year. The ranges indicate the uncertainty of some programs regarding the number of positions. CONCLUSIONS: The survey suggests that participating programs will fill sufficient independent IR residency positions to accommodate all ESIR applicants in a match year of average or low competitiveness, but not in a match year of high competitiveness. This suggestion does not account for certain difficult-to-predict factors that may affect the independent IR residency match.


Asunto(s)
Internado y Residencia/estadística & datos numéricos , Evaluación de Necesidades , Admisión y Programación de Personal/estadística & datos numéricos , Servicio de Radiología en Hospital/estadística & datos numéricos , Radiología Intervencionista/educación , Encuestas y Cuestionarios , Estados Unidos , Recursos Humanos
13.
BMC Syst Biol ; 10: 20, 2016 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-26927448

RESUMEN

BACKGROUND: The fungal pathogen Candida albicans colonizes the gastrointestinal (GI) tract of mammalian hosts as a benign commensal. However, in an immunocompromised host, the fungus is capable of causing life-threatening infection. We previously showed that the major transcription factor Efg1p is differentially expressed in GI-colonizing C. albicans cells dependent on the host immune status. To understand the mechanisms that underlie this host-dependent differential gene expression, we utilized mathematical modeling to dissect host-pathogen interactions. Specifically, we used principles of evolutionary game theory to study the mechanism that governs dynamics of EFG1 expression during C. albicans colonization. RESULTS: Mathematical modeling predicted that down-regulation of EFG1 expression within individual fungal cells occurred at different average rates in different hosts. Rather than using relatively transient signaling pathways to adapt to a new environment, we demonstrate that C. albicans overcomes the host defense strategy by modulating the activity of diverse fungal histone modifying enzymes that control EFG1 expression. CONCLUSION: Based on our modeling and experimental results we conclude that C. albicans cells sense the local environment of the GI tract and respond to differences by altering EFG1 expression to establish optimal survival strategies. We show that the overall process is governed via modulation of epigenetic regulators of chromatin structure.


Asunto(s)
Candida albicans/genética , Candida albicans/fisiología , Teoría del Juego , Regulación Fúngica de la Expresión Génica , Interacciones Huésped-Patógeno , Modelos Biológicos , Candida albicans/citología , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Evolución Molecular , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Tracto Gastrointestinal/microbiología , Histonas/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Tuberculosis Gastrointestinal
14.
Curr Fungal Infect Rep ; 8(2): 179-184, 2014 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-24839528

RESUMEN

The fungus Candida albicans is a frequent commensal colonizer of the human gastrointestinal (GI) tract, but is also an opportunistic pathogen. This review explores features that distinguish the colonizing and pathogenic forms of C. albicans. Candida albicans in a biofilm is used as an example of a pathogenic form of the organism, because biofilms are a common feature of device-associated C. albicans infections. Biofilms (complex, sessile communities of cells) have been the subject of several large-scale gene expression studies. Biofilms and commensal C. albicans colonizing the murine GI tract show a variety of differentially expressed genes. Cell surface proteins encoded by these differentially expressed genes are especially attractive as targets for new clinical prevention, diagnosis, or treatment tools that are specific for C. albicans in its pathogenic biofilm state.

15.
Biochemistry ; 52(16): 2764-73, 2013 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-23530771

RESUMEN

FAD and NAD(P)H-dependent coenzyme A disulfide reductases/polysulfide reductases (CoADR/Psr) have been proposed to be important for the reduction of sulfur and disulfides in the sulfur-reducing anaerobic hyperthermophiles Pyrococcus horikoshii and Pyrococcus furiosus; however, the form(s) of sulfur that the enzyme actually reduces are not clear. Here we determined the structure for the FAD- and coenzyme A-containing holoenzyme from P. horikoshii to 2.7 Å resolution and characterized its substrate specificity. The enzyme is relatively promiscuous and reduces a range of disulfide, persulfide, and polysulfide compounds. These results indicate that the likely in vivo substrates are NAD(P)H and di-, poly-, and persulfide derivatives of coenzyme A, although polysulfide itself is also efficiently reduced. The role of the enzyme in the reduction of elemental sulfur (S(8)) in situ is not, however, ruled out by these results, and the possible roles of this substrate are discussed. During aerobic persulfide reduction, rapid recycling of the persulfide substrate was observed, which is proposed to occur via sulfide oxidation by O(2) and/or H(2)O(2). As expected, this reaction disappears under anaerobic conditions and may explain observations by others that CoADR is not essential for S(0) respiration in Pyrococcus or Thermococcus but appears to participate in oxidative defense in the presence of S(0). When compared to the homologous Npsr enzyme from Shewanella loihica PV-4 and homologous enzymes known to reduce CoA disulfide, the phCoADR structure shows a relatively restricted substrate channel leading into the sulfur-reducing side of the FAD isoalloxazine ring, suggesting how this enzyme class may select for specific disulfide substrates.


Asunto(s)
NADH NADPH Oxidorreductasas/química , NADH NADPH Oxidorreductasas/metabolismo , Pyrococcus horikoshii/enzimología , Cristalografía por Rayos X , Cinética , Modelos Moleculares , NADP/metabolismo , Oxidación-Reducción , Oxidorreductasas/química , Oxidorreductasas/metabolismo , Conformación Proteica , Especificidad por Sustrato , Sulfuros/metabolismo
16.
Protein Expr Purif ; 74(1): 116-21, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20600936

RESUMEN

Lysyl oxidase is a highly insoluble enzyme requiring high concentrations of urea to solubilize. A method to obtain lysyl oxidase in high yields directly from an Escherichia coli culture without the need for refolding of inclusion bodies has been developed using nutrient rich media. pET21b was used to overexpress the lysyl oxidase enzyme and to introduce a C-terminal 6X histidine tag for purification. Lysyl oxidase yields of 10 mg of active and properly folded enzyme per liter of media have been obtained. Purification was achieved via affinity chromatography using a Ni-NTA column. Copper content was found to be 19%. LTQ cofactor formation in LOX is a self-processing event in the presence of copper. LTQ content was determined to be 24% based on reaction with phenylhydrazine to form a phenylhydrazone adduct. Quantification of this adduct was attained using the previously reported extinction coefficient of 15.4 mM(-1)cm(-1). LTQ presence was also verified by redox cycling. Specific enzymatic activity was measured to be 0.31 U/mg, one of the highest activities reported.


Asunto(s)
Escherichia coli/genética , Proteína-Lisina 6-Oxidasa/genética , Proteína-Lisina 6-Oxidasa/aislamiento & purificación , Secuencia de Aminoácidos , Cobre/metabolismo , Expresión Génica , Humanos , Datos de Secuencia Molecular , Oxidación-Reducción , Fenilhidrazinas/antagonistas & inhibidores , Proteína-Lisina 6-Oxidasa/metabolismo , Quinonas/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Alineación de Secuencia
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