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1.
Antimicrob Agents Chemother ; 66(12): e0111322, 2022 12 20.
Artículo en Inglés | MEDLINE | ID: mdl-36377940

RESUMEN

Candida bloodstream infections are associated with high attributable mortality, where early initiation of adequate antifungal therapy is important to increase survival in critically ill patients. The exposure variability of micafungin, a first-line agent used for the treatment of invasive candidiasis, in critically ill patients is significant, potentially resulting in underexposure in a substantial portion of these patients. The objective of this study was to develop a population pharmacokinetic model including appropriate sampling strategies for assessing micafungin drug exposure in critically ill patients to support adequate area under the concentration-time curve (AUC) determination. A two-compartment pharmacokinetic model was developed using data from intensive care unit (ICU) patients (n = 19), with the following parameters: total body clearance (CL), volume of distribution of the central compartment (V1), inter-compartmental clearance (CL12), and volume of distribution of the peripheral compartment (V2). The final model was evaluated with bootstrap analysis and the goodness-of-fit plots for the population and individual predicted micafungin plasma concentrations. Optimal sampling strategies (with sampling every hour, 24 h per day) were developed with 1- and 2-point sampling schemes. Final model parameters (±SD) were: CL = 1.03 (0.37) (L/h/1.85 m2), V1 = 0.17 (0.07) (L/kg LBMc), CL12 = 1.80 (4.07) (L/h/1.85 m2), and V2 = 0.12 (0.06) (L/kg LBMc). Sampling strategies with acceptable accuracy and precision were developed to determine the micafungin AUC. The developed model with optimal sampling procedures provides the opportunity to achieve quick optimization of the micafungin exposure from a single blood sample using Bayesian software and may be helpful in guiding early dose decision-making.


Asunto(s)
Antifúngicos , Candidiasis Invasiva , Humanos , Micafungina/uso terapéutico , Micafungina/farmacocinética , Antifúngicos/farmacocinética , Enfermedad Crítica , Teorema de Bayes , Candidiasis Invasiva/tratamiento farmacológico
2.
BMC Gastroenterol ; 22(1): 516, 2022 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-36513968

RESUMEN

BACKGROUND: T1 colorectal cancer (CRC) without histological high-risk factors for lymph node metastasis (LNM) can potentially be cured by endoscopic resection, which is associated with significantly lower morbidity, mortality and costs compared to radical surgery. An important prerequisite for endoscopic resection as definite treatment is the histological confirmation of tumour-free resection margins. Incomplete resection with involved (R1) or indeterminate (Rx) margins is considered a strong risk factor for residual disease and local recurrence. Therefore, international guidelines recommend additional surgery in case of R1/Rx resection, even in absence of high-risk factors for LNM. Endoscopic full-thickness resection (eFTR) is a relatively new technique that allows transmural resection of colorectal lesions. Local scar excision after prior R1/Rx resection of low-risk T1 CRC could offer an attractive minimal invasive strategy to achieve confirmation about radicality of the previous resection or a second attempt for radical resection of residual luminal cancer. However, oncologic safety has not been established and long-term data are lacking. Besides, surveillance varies widely and requires standardization. METHODS/DESIGN: In this nationwide, multicenter, prospective cohort study we aim to assess feasibility and oncological safety of completion eFTR following incomplete resection of low-risk T1 CRC. The primary endpoint is to assess the 2 and 5 year luminal local tumor recurrence rate. Secondary study endpoints are to assess feasibility, percentage of curative eFTR-resections, presence of scar tissue and/or complete scar excision at histopathology, safety of eFTR compared to surgery, 2 and 5 year nodal and/or distant tumor recurrence rate and 5-year disease-specific and overall-survival rate. DISCUSSION: Since the implementation of CRC screening programs, the diagnostic rate of T1 CRC is steadily increasing. A significant proportion is not recognized as cancer before endoscopic resection and is therefore resected through conventional techniques primarily reserved for benign polyps. As such, precise histological assessment is often hampered due to cauterization and fragmentation and frequently leads to treatment dilemmas. This first prospective trial will potentially demonstrate the effectiveness and oncological safety of completion eFTR for patients who have undergone a previous incomplete T1 CRC resection. Hereby, substantial surgical overtreatment may be avoided, leading to treatment optimization and organ preservation. Trial registration Nederlands Trial Register, NL 7879, 16 July 2019 ( https://trialregister.nl/trial/7879 ).


Asunto(s)
Neoplasias Colorrectales , Recurrencia Local de Neoplasia , Humanos , Cicatriz/complicaciones , Cicatriz/patología , Neoplasias Colorrectales/patología , Metástasis Linfática , Estudios Multicéntricos como Asunto , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Neoplasia Residual/patología , Estudios Prospectivos , Estudios Retrospectivos , Resultado del Tratamiento
3.
Artículo en Inglés | MEDLINE | ID: mdl-33361296

RESUMEN

The efficacy of fluconazole is related to the area under the plasma concentration-time curve (AUC) over the MIC of the microorganism. Physiological changes in critically ill patients may affect the exposure of fluconazole, and therefore dosing adjustments might be needed. The aim of this study was to evaluate variability in fluconazole drug concentration in intensive care unit (ICU) patients and to develop a pharmacokinetic model to support personalized fluconazole dosing. A prospective observational pharmacokinetic study was performed in critically ill patients receiving fluconazole either as prophylaxis or as treatment. The association between fluconazole exposure and patient variables was studied. Pharmacokinetic modeling was performed with a nonparametric adaptive grid (NPAG) algorithm using R package Pmetrics. Data from 33 patients were available for pharmacokinetic analysis. Patients on dialysis and solid organ transplant patients had a significantly lower exposure to fluconazole. The population was best described with a one-compartment model, where the mean volume of distribution was 51.52 liters (standard deviation [SD], 19.81) and the mean clearance was 0.767 liters/h (SD, 0.46). Creatinine clearance was tested as a potential covariate in the model, but was not included in the final population model. A significant positive correlation was found between the fluconazole exposure (AUC) and the trough concentration (Cmin). Substantial variability in fluconazole plasma concentrations in critically ill adults was observed, where the majority of patients were underexposed. Fluconazole Cmin therapeutic drug monitoring (TDM)-guided dosing can be used to optimize therapy in critically ill patients. (This study has been registered at ClinicalTrials.gov under identifier NCT02491151.).


Asunto(s)
Candidiasis Invasiva , Fluconazol , Adulto , Antibacterianos , Candidiasis Invasiva/tratamiento farmacológico , Candidiasis Invasiva/prevención & control , Enfermedad Crítica , Fluconazol/uso terapéutico , Humanos , Pruebas de Sensibilidad Microbiana , Diálisis Renal
4.
Artículo en Inglés | MEDLINE | ID: mdl-28971861

RESUMEN

The estimated attributable mortality rate for invasive candidiasis (IC) in the intensive care unit (ICU) setting varies from 30 to 40%. Physiological changes in critically ill patients may affect the distribution and elimination of micafungin, and therefore, dosing adjustments might be mandatory. The objective of this study was to determine the pharmacokinetic parameters of micafungin in critically ill patients and assess the probability of target attainment. Micafungin plasma concentrations were measured to estimate the pharmacokinetic properties of micafungin. MIC values for Candida isolates were determined to assess the probability of target attainment for patients. Data from 19 patients with suspected or proven invasive candidiasis were available for analysis. The median area under the concentration-time curve from 0 to 24 h at steady state (AUC0-24) was 89.6 mg · h/liter (interquartile range [IQR], 75.4 to 113.6 mg · h/liter); this was significantly lower than the median micafungin AUC0-24 values of 152.0 mg · h/liter (IQR, 136.0 to 162.0 mg · h/liter) and 134.0 mg · h/liter (IQR, 118.0 to 148.6 mg · h/liter) in healthy volunteers (P = <0.0001 and P = <0.001, respectively). All Candida isolates were susceptible to micafungin, with a median MIC of 0.016 mg/liter (IQR, 0.012 to 0.023 mg/liter). The median AUC0-24/MIC ratio was 5,684 (IQR, 4,325 to 7,578), and 3 of the 17 evaluable patients (17.6%) diagnosed with proven invasive candidiasis did not meet the AUC/MIC ratio target of 5,000. Micafungin exposure was lower in critically ill patients than in healthy volunteers. The variability in micafungin exposure in this ICU population could be explained by the patients' body weight. Our findings suggest that healthier patients (sequential organ failure assessment [SOFA] score of <10) weighing more than 100 kg and receiving 100 mg micafungin daily are at risk for inappropriate micafungin exposure and potentially inadequate antifungal treatment. (This study has been registered at ClinicalTrials.gov under identifier NCT01716988.).


Asunto(s)
Antifúngicos/farmacocinética , Candida albicans/efectos de los fármacos , Candida glabrata/efectos de los fármacos , Candidiasis Invasiva/tratamiento farmacológico , Equinocandinas/farmacocinética , Lipopéptidos/farmacocinética , Anciano , Antifúngicos/sangre , Área Bajo la Curva , Disponibilidad Biológica , Peso Corporal , Candida albicans/crecimiento & desarrollo , Candida glabrata/crecimiento & desarrollo , Candidiasis Invasiva/sangre , Candidiasis Invasiva/microbiología , Candidiasis Invasiva/patología , Estudios de Casos y Controles , Enfermedad Crítica , Cálculo de Dosificación de Drogas , Equinocandinas/sangre , Femenino , Humanos , Unidades de Cuidados Intensivos , Lipopéptidos/sangre , Masculino , Micafungina , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad
5.
Int J Colorectal Dis ; 32(12): 1711-1717, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28884225

RESUMEN

BACKGROUND: Endoscopic mucosal resection (EMR) has been proven to be safe and effective for the treatment of colorectal adenomas. However, data are limited on the safety of this technique for large polyps and in elderly patients. Aims of our study were to examine the bleeding and perforation rates in patients with large non-pedunculated adenomas (≥20mm) and to evaluate the influence of size (≥40mm) and age (≥75 years) on the complication rates. METHODS: In this multicenter retrospective study, patients who underwent EMR of non-pedunculated adenomas ≥20mm between January 2012 and March 2016 were included. The demographics of the patients, the use of antithrombotic drugs, size of the polyps, type of resection, pathology report, occurrence of post-polypectomy bleeding, and perforation- and recurrence rate were collected. RESULTS: In 343 patients, 412 adenomas were removed. Eighty patients (23.3%) were ≥75 years of age, 138 polyps (33.5%) were ≥40mm. Bleeding complications were observed in 28 cases (6.8%) and were found significantly more frequent in adenomas ≥40mm, independent of the use of antithrombotic therapy. Five perforations (1.2%) were described, not related to the size of the polyp. There was no significant difference in complication rates between patients <75 years and patients ≥75 years. Bleeding complications rates were significantly higher in patients receiving double antithrombotic therapy. CONCLUSION: EMR is safe in elderly patients. EMR of adenomas of ≥40mm was associated with more bleeding complications. Future studies should address how the bleeding rates can be reduced in these patients, especially in those who use double antithrombotic treatment.


Asunto(s)
Pólipos Adenomatosos/cirugía , Pólipos del Colon/cirugía , Neoplasias Colorrectales/cirugía , Pólipos Adenomatosos/patología , Factores de Edad , Anciano , Pérdida de Sangre Quirúrgica , Pólipos del Colon/patología , Neoplasias Colorrectales/patología , Esquema de Medicación , Resección Endoscópica de la Mucosa/efectos adversos , Femenino , Fibrinolíticos/administración & dosificación , Fibrinolíticos/efectos adversos , Humanos , Perforación Intestinal/etiología , Masculino , Persona de Mediana Edad , Países Bajos , Hemorragia Posoperatoria/etiología , Estudios Retrospectivos , Factores de Riesgo , Factores de Tiempo , Resultado del Tratamiento , Carga Tumoral
7.
Ann Surg Oncol ; 22(5): 1555-63, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25564156

RESUMEN

BACKGROUND: Perioperative epirubicin, cisplatin, and capecitabine (ECC) chemotherapy was evaluated in patients who underwent esophageal resection for adenocarcinoma of the esophagus or gastroesophageal junction (GEJ). METHODS: A cohort of 93 consecutive patients was analyzed. The median follow-up period was 60 months. Source data verification of adverse events was performed by two independent observers. RESULTS: All three planned preoperative chemotherapy cycles were administered to 65 patients (69.9 %). Only 27 % of the patients completed both pre- and postoperative chemotherapy. The reasons for not receiving postoperative adjuvant chemotherapy could be separated in two main problems: toxicity of the preoperative chemotherapy and postoperative problems involving difficulty in recovery and postoperative complications. Finally, 25 patients (27 %), completed three preoperative and three postoperative cycles. Grades 3 and 4 nonhematologic adverse events of preoperative chemotherapy mainly consisted of thromboembolic events (16.2 %) and cardiac complications (7.5 %). A history of cardiac and vascular disease was independently associated with discontinuation of preoperative chemotherapy and the occurrence of grade 3 or higher adverse events. Surgery was performed for 94 % of all the patients who started with ECC chemotherapy. A radical resection (R0) was achieved in 93 % of the patients. A complete pathologic response was observed in 8 % of the patients. During a median follow-up period of 60 months, the median disease-free survival time was 28 months, and the median overall survival time was 36 months. The 3-year overall survival rate was 50 %, and the 5-year overall survival rate was 42 %. CONCLUSION: For patients with adenocarcinoma of the esophagus or GEJ, six cycles of ECC-based perioperative chemotherapy is associated with a relatively high number of adverse events. Although this toxicity did not affect the esophageal resectability rate, this regimen should be used with caution in this patient population.


Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Esofágicas/tratamiento farmacológico , Unión Esofagogástrica/efectos de los fármacos , Atención Perioperativa , Neoplasias Gástricas/tratamiento farmacológico , Adenocarcinoma/mortalidad , Adenocarcinoma/patología , Adenocarcinoma/cirugía , Adulto , Anciano , Capecitabina/administración & dosificación , Cisplatino/administración & dosificación , Terapia Combinada , Epirrubicina/administración & dosificación , Neoplasias Esofágicas/mortalidad , Neoplasias Esofágicas/patología , Neoplasias Esofágicas/cirugía , Unión Esofagogástrica/patología , Unión Esofagogástrica/cirugía , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Pronóstico , Estudios Retrospectivos , Seguridad , Neoplasias Gástricas/mortalidad , Neoplasias Gástricas/patología , Neoplasias Gástricas/cirugía , Tasa de Supervivencia , Factores de Tiempo
8.
Dis Esophagus ; 28(1): 90-6, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23795680

RESUMEN

Human esophageal adenocarcinoma (EAC) cell lines have made a substantial contribution to elucidating mechanisms of carcinogenesis and drug discovery. Model research on EAC relies almost entirely on a relatively small set of established tumor cell lines because appropriate animal models are lacking. Nowadays, more than 20% of all fundamental translational research studies regarding EAC are partially or entirely based on these cell lines. The ready availability of these cell lines to investigators worldwide have resulted in more than 250 publications, including many examples of important biomedical discoveries. The high genomic similarities (but certainly not completely identical) between the EAC cell lines and their original tumors provide rational for their use. Recently, in a collaborative effort all available EAC cell lines have been verified resulting in the establishment of a reliable panel of 10 EAC cell lines. It could be expected that the value of these cell lines increases as unlimited source of tumor material because new biomedical techniques require more tumor cells and the supply of viable tumor cells is diminishing because of neoadjuvant chemo(radio)therapy of patients with EAC. Here, we review the history of the EAC cell lines and their utility in translational research and biomedical discovery.


Asunto(s)
Adenocarcinoma/patología , Neoplasias Esofágicas/patología , Investigación Biomédica Traslacional , Animales , Línea Celular Tumoral , Humanos
10.
Cell Mol Life Sci ; 68(1): 27-44, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20799050

RESUMEN

Even though every cell in a multicellular organism contains the same genes, the differing spatiotemporal expression of these genes determines the eventual phenotype of a cell. This means that each cell type contains a specific epigenetic program that needs to be replicated through cell divisions, along with the genome, in order to maintain cell identity. The stable inheritance of these programs throughout the cell cycle relies on several epigenetic mechanisms. In this review, DNA methylation and histone methylation by specific histone lysine methyltransferases (KMT) and the Polycomb/Trithorax proteins are considered as the primary mediators of epigenetic inheritance. In addition, non-coding RNAs and nuclear organization are implicated in the stable transfer of epigenetic information. Although most epigenetic modifications are reversible in nature, they can be stably maintained by self-recruitment of modifying protein complexes or maintenance of these complexes or structures through the cell cycle.


Asunto(s)
Ciclo Celular/genética , Metilación de ADN , Epigénesis Genética , Histonas/metabolismo , Ensamble y Desensamble de Cromatina , ADN/química , ADN/metabolismo , Epigenómica , Silenciador del Gen , N-Metiltransferasa de Histona-Lisina/metabolismo , N-Metiltransferasa de Histona-Lisina/fisiología , Proteínas del Grupo Polycomb , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Proteínas Represoras/fisiología
11.
Clin Transl Radiat Oncol ; 20: 39-44, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31886418

RESUMEN

BACKGROUND AND PURPOSE: With currently available techniques, the prediction of pathologic complete response after neoadjuvant chemoradiotherapy is insufficient. The tumor-stroma ratio (TSR) has proven to be a predictor of survival for several types of cancer, including esophageal. The aim of this study was to investigate the value of TSR in predicting pathologic response after neoadjuvant chemoradiotherapy in esophageal cancer patients. MATERIALS AND METHODS: Patients with esophageal adenocarcinoma or squamous cell carcinoma who received neoadjuvant chemoradiotherapy followed by a resection were selected. Haematoxylin and eosin (H&E) stained sections of diagnostic biopsies were collected and TSR was independently assessed by two investigators. Patients were categorized in stroma-low (≤50% stroma) and stroma-high (>50% stroma) groups for further analyses. The tumor regression grade (TRG) was assessed on H&E stained sections of the resected primary tumor to determine pathologic response. RESULTS: A total of 94 patients were included in this study, of which 76 patients were categorized as stroma-low and 18 as stroma-high. Forty-two (45%) patients had a major pathologic response (TRG 1-2), whereas 52 (55%) were considered non-responders. After adjustment for gender, tumor type, cT-status and differentiation grade, patients with a stroma-high tumor showed a higher chance of no response compared to patients with a stroma-low tumor (OR 3.57, 95%CI 1.03-12.31, P = 0.04). CONCLUSION: TSR showed to have the potential to aid in the prediction of pathologic response in esophageal cancer patients receiving neoadjuvant chemoradiotherapy. Larger validation studies are necessary before implementing this method in daily practice.

12.
J Cell Biol ; 108(3): 1115-25, 1989 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-2537833

RESUMEN

High levels of the neuron-specific protein kinase C substrate, B-50 (= GAP43), are present in neurites and growth cones during neuronal development and regeneration. This suggests a hitherto nonelucidated role of this protein in neurite outgrowth. Comparable high levels of B-50 arise in the pheochromocytoma PC12 cell line during neurite formation. To get insight in the putative growth-associated function of B-50, we compared its ultrastructural localization in naive PC12 cells with its distribution in nerve growth factor (NGF)- or dibutyryl cyclic AMP (dbcAMP)-treated PC12 cells. B-50 immunogold labeling of cryosections of untreated PC12 cells is mainly associated with lysosomal structures, including multivesicular bodies, secondary lysosomes, and Golgi apparatus. The plasma membrane is virtually devoid of label. However, after 48-h NGF treatment of the cells, B-50 immunoreactivity is most pronounced on the plasma membrane. Highest B-50 immunoreactivity is observed on plasma membranes surrounding sprouting microvilli, lamellipodia, and filopodia. Outgrowing neurites are scattered with B-50 labeling, which is partially associated with chromaffin granules. In NGF-differentiated PC12 cells, B-50 immunoreactivity is, as in untreated cells, also associated with organelles of the lysosomal family and Golgi stacks. B-50 distribution in dbcAMP-differentiated cells closely resembles that in NGF-treated cells. The altered distribution of B-50 immunoreactivity induced by differentiating agents indicates a shift of the B-50 protein towards the plasma membrane. This translocation accompanies the acquisition of neuronal features of PC12 cells and points to a neurite growth-associated role for B-50, performed at the plasma membrane at the site of protrusion.


Asunto(s)
Proteínas de la Membrana/análisis , Factores de Crecimiento Nervioso/farmacología , Proteínas del Tejido Nervioso/análisis , Neuronas/análisis , Feocromocitoma/análisis , Animales , Axones/análisis , Bucladesina/farmacología , Diferenciación Celular , Línea Celular , Membrana Celular/análisis , Sistema Cromafín/análisis , Sistema Cromafín/citología , Sistema Cromafín/ultraestructura , Proteína GAP-43 , Aparato de Golgi/análisis , Inmunohistoquímica , Lisosomas/análisis , Microscopía Electrónica , Microvellosidades/análisis , Neuronas/ultraestructura , Feocromocitoma/ultraestructura , Seudópodos/análisis
13.
J Cell Biol ; 97(1): 92-8, 1983 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-6306015

RESUMEN

Rat pheochromocytoma cells (clone PC12) respond to nerve growth factor (NGF) by the acquirement of a phenotype resembling neuronal cells. In an earlier study we showed that NGF causes an increase in Na+,K+ pump activity, as monitored by ouabain-sensitive Rb+ influx. Here we show that addition of epidermal growth factor (EGF) to PC12 cells resulted in a stimulation of Na+,K+ pump activity as well. The increase of Na+,K+ pump activity by NGF or EGF was due to increased Na+ influx. This increased Na+ influx was sensitive to amiloride, an inhibitor of Na+,H+ exchange. Furthermore, no changes in membrane potential were observed upon addition of NGF or EGF. Amiloride-sensitive Na+,H+ exchange in PC12 cells was demonstrated by H+ efflux measurements and the effects of weak acids on Na+ influx. These observations suggest that both NGF and EGF activate an amiloride-sensitive, electroneutral Na+,H+ exchange mechanism in PC12 cells. These findings were surprising in view of the opposite ultimate biological effects of NGF and EGF, e.g., growth arrest vs. growth stimulation. However, within 24 h after addition, NGF was found to stimulate growth of PC12 cells, comparable to EGF. In the presence of amiloride, this stimulated growth by NGF and EGF was abolished. In contrast, amiloride did not affect NGF-induced neurite outgrowth of PC12 cells. From these observations it is concluded that in PC12 cells: (a) NGF has an initial growth stimulating effect; (b) neurite outgrowth is independent of increased amiloride-sensitive Na+ influx; and (c) growth stimulation by NGF and EGF is associated with increased amiloride-sensitive Na+ influx.


Asunto(s)
Factor de Crecimiento Epidérmico/farmacología , Factores de Crecimiento Nervioso/farmacología , Neuronas/citología , Potasio/metabolismo , Sodio/metabolismo , Amilorida/farmacología , Animales , Diferenciación Celular/efectos de los fármacos , División Celular/efectos de los fármacos , Línea Celular , Canales Iónicos/efectos de los fármacos , Feocromocitoma , Ratas
14.
J Cell Biol ; 119(2): 349-55, 1992 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1383230

RESUMEN

In a number of recent studies it has been shown that in vivo part of the EGF receptor (EGFR) population is associated to the actin filament system. In this paper we demonstrate that the purified EGFR can be cosedimented with purified filamentous actin (F-actin) indicating a direct association between EGFR and actin. A truncated EGFR, previously shown not to be associated to the cytoskeleton, was used as a control and this receptor did not cosediment with actin filaments. Determination of the actin-binding domain of the EGFR was done by measuring competition of either a polyclonal antibody or synthetic peptides on EGFR cosedimentation with F-actin. A synthetic peptide was made homologous to amino acid residues 984-996 (HL-33) of the EGFR which shows high homology with the actin-binding domain of Acanthamoeba profilin. A polyclonal antibody raised against HL-33 was found to prevent cosedimentation of EGFR with F-actin. This peptide HL-33 was shown to bind directly to actin in contrast with a synthetic peptide homologous to residues 1001-1013 (HL-34). During cosedimentation, HL-33 competed for actin binding of the EGFR and HL-34 did not, indicating that the EGFR contains one actin-binding site. These results demonstrate that the EGFR is an actin-binding protein which binds to actin via a domain containing amino acids residues 984-996.


Asunto(s)
Actinas/metabolismo , Receptores ErbB/metabolismo , Secuencia de Aminoácidos , Sitios de Unión , Unión Competitiva , Proteínas Contráctiles/genética , Epítopos , Receptores ErbB/genética , Receptores ErbB/inmunología , Receptores ErbB/aislamiento & purificación , Proteínas de Microfilamentos/genética , Datos de Secuencia Molecular , Oligopéptidos/síntesis química , Oligopéptidos/inmunología , Profilinas , Unión Proteica , Homología de Secuencia de Aminoácido , Células Tumorales Cultivadas
15.
J Cell Biol ; 103(1): 87-94, 1986 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-3013901

RESUMEN

The structural interaction of the epidermal growth factor (EGF) receptor and the cytoskeleton of A431 cells has been studied using a monoclonal anti-EGF receptor antibody. This has been done with immunogold labeling using a variety of electron microscopical preparation procedures and EGF binding studies. By providing an image of the membrane-associated cytoskeleton, the dry cleavage method reveals a preferential localization of EGF receptors superimposed upon cytoskeletal filaments. The colocalization of gold particles with cytoskeletal filaments is not affected when pre-labeled cells are extracted with the non-ionic detergent Triton X-100, as visualized by dry cleavage. Using surface replication, this treatment results in visualization of the cytoskeleton. In these latter preparations, it is also observed that EGF receptor-coupled gold particles remain associated with cytoskeletal elements. Moreover, Triton extraction performed before immunogold labeling of EGF receptors demonstrates that isolated cytoskeletons contained binding sites for anti-EGF receptor antibodies. Using stereo micrographs of replica's obtained from these isolated cytoskeletons, it is shown that gold-labeled EGF receptors are exclusively present on the cortical membrane-associated region of the cytoskeleton and not on more intracellular-located filaments. Scatchard analysis of EGF binding to cells fixed with glutaraldehyde and treated with Triton X-100 before and after EGF binding indicates that a high affinity EGF binding site is associated with the Triton X-100 insoluble cytoskeleton.


Asunto(s)
Carcinoma de Células Escamosas/metabolismo , Citoesqueleto/metabolismo , Receptores de Superficie Celular/metabolismo , Anticuerpos Monoclonales , Carcinoma de Células Escamosas/ultraestructura , Línea Celular , Receptores ErbB , Fijadores , Humanos , Microscopía Electrónica/métodos , Polietilenglicoles
16.
J Cell Biol ; 107(3): 939-49, 1988 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-2458364

RESUMEN

The epidermal growth factor receptor (EGF-R) of human A431 cells bears an antigenic determinant that is closely related to the human blood group A carbohydrate structure. Labeling studies with blood group A reactive anti-EGF-R monoclonal antibodies and various lectins revealed that A431 cultures are heterogeneous with respect to blood group A expression. We have isolated clonal variants of these cells that either express (A431A+ cells) or completely lack (A431A- cells) the blood group A specific N-acetyl-D-galactosamine (GalNAc) residue. We show that this difference is due to the absence of a UDP-GalNAc:Gal transferase activity in A431A- cells. Subsequently, we have compared EGF-R functioning in these cell lines. Scatchard analysis of EGF-binding shows that in A431A- cells 6.3% of the EGF-R belongs to a high affinity subclass (Kd = 0.4 nM) while in A431A+ this subclass represents only 3.2% of the total receptor pool. The elevated level of high affinity receptors in A431A- cells is accompanied by a parallel increase in receptor protein- tyrosine kinase activity. In membrane preparations of A431A- cells, receptor autophosphorylation as well as phosphorylation of a tyrosine-containing peptide substrate is 2-3-fold higher as compared with A431A+ cells. In intact A431A-cells, the difference in receptor activity is measured as a 2-3-fold elevated level of receptor phosphorylation and a 2-3-fold higher abundance of phosphotyrosine in total cellular protein in A431A- cells. In addition, [35S]methionine pulse-chase experiments showed a ligand-independent increase in turnover of EGF-R in A431A- cells: the receptor's half life in these cells is 10 h as compared with 17 h in A431A+ cells. Our results suggest a possible involvement of GalNAc residue(s) in determining EGF-R affinity, protein-tyrosine kinase activity and turnover in A431 cells. Furthermore, our results indicate that high affinity EGF-R are the biologically active species with respect to protein-tyrosine kinase activity.


Asunto(s)
Sistema del Grupo Sanguíneo ABO/inmunología , Receptores ErbB/análisis , Proteínas Tirosina Quinasas/metabolismo , Anticuerpos Monoclonales/inmunología , Autorradiografía , Carcinoma de Células Escamosas , Membrana Celular/enzimología , Membrana Celular/metabolismo , Células Clonales , Epítopos/inmunología , Receptores ErbB/metabolismo , Técnica del Anticuerpo Fluorescente , Glicosilación , Semivida , Humanos , Lectinas , Fosforilación , Células Tumorales Cultivadas
17.
J Cell Biol ; 109(5): 2495-507, 1989 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-2553748

RESUMEN

Many cell types display two classes of epidermal growth factor receptor (EGFR) as judged from EGF binding studies; i.e., a major class of low affinity EGFR and a minor class of high affinity EGFR. We have studied their respective contribution to the cascade of events elicited by EGF in human A431 carcinoma cells, using anti-EGFR mAb 2E9. This antibody specifically blocks EGF binding to low affinity EGFR, without activating receptors in intact cells, and thus enables us to study the effects of exclusive EGF binding to high affinity EGFR. We show that blocking of low affinity EGFR by mAb 2E9 has almost no effect on the activation of the receptor protein-tyrosine kinase by EGF, suggesting that EGFR kinase activation occurs exclusively through the subclass of high affinity EGFR (5-10%). In addition, we provide evidence that high affinity EGFR exists both in monomeric and dimeric forms, and that cross-phosphorylation of low affinity EGFR by high affinity EGFR may take place in dimers of both receptor types. We demonstrate that the following early cellular response to EGF are also unimpaired in the presence of mAb 2E9: (a) inositol phosphate production, (b) release of Ca2+ from intracellular stores, (c) rise in intracellular pH, (d) phosphorylation of EGF on threonine residue 654, (e) induction of c-fos gene expression, and (f) alteration in cell morphology. As possible nonspecific side effects, we observed that the EGF induced Ca2+ influx and fluid-phase pinocytosis were inhibited in A431 cells in the presence of mAb 2E9. We conclude, therefore, that the activation of the EGFR signal transduction cascade can occur completely through exclusive binding of EGF to the subclass of high affinity EGFR.


Asunto(s)
Factor de Crecimiento Epidérmico/farmacología , Receptores ErbB/fisiología , Transducción de Señal , Línea Celular , Factor de Crecimiento Epidérmico/metabolismo , Factor de Crecimiento Epidérmico/fisiología , Receptores ErbB/metabolismo , Humanos , Cinética , Fosforilación , Proteínas Tirosina Quinasas/metabolismo , Células Tumorales Cultivadas/citología , Células Tumorales Cultivadas/efectos de los fármacos , Células Tumorales Cultivadas/fisiología
18.
J Cell Biol ; 115(1): 121-8, 1991 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1655800

RESUMEN

In this paper we demonstrate that cytoskeletons isolated from A431 cells have associated with them high activities of several kinases involved in inositol lipid metabolism, such as phosphatidylinositol kinase, phosphatidylinositol phosphate kinase, and diacylglycerol kinase. In addition also phospholipase C activity was detected on isolated cytoskeletons. Controlled extraction of the cytoskeletons followed by in vitro polymerization of actin demonstrated an association of the kinases to the actin filament system consisting of actin and a number of actin-binding proteins. The cytoskeleton-associated lipid kinase activities were significantly increased upon treatment of intact cells with EGF. These data suggest that the association of the phosphoinositide kinases, diacylglycerol kinase, phospholipase C, and also the EGF receptor to the cytoskeleton may play a role in the efficient signal transduction induced by EGF, by providing a matrix for the various components involved in signal transduction.


Asunto(s)
Citoesqueleto/enzimología , Factor de Crecimiento Epidérmico/farmacología , Receptores ErbB/metabolismo , Fosfatidilinositoles/metabolismo , Fosfotransferasas/metabolismo , Fosfolipasas de Tipo C/metabolismo , 1-Fosfatidilinositol 4-Quinasa , Actinas/fisiología , Animales , Compartimento Celular/efectos de los fármacos , Línea Celular , Citoesqueleto/ultraestructura , Diacilglicerol Quinasa , Humanos , Técnicas In Vitro , Ratones , Ratas
19.
J Surg Oncol ; 100(5): 407-13, 2009 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-19653239

RESUMEN

BACKGROUND: Patients with carcinoma of the distal esophagus and metastatic celiac lymph nodes (M1a) have a poor prognosis and are often denied surgery. In this study, we evaluated our treatment strategy of chemotherapy followed by surgery in patients with M1a disease. METHODS: Thirty-eight patients who received chemotherapy for carcinoma of the distal esophagus with celiac lymph node involvement between 2000 and 2007 were identified from a prospective database. Clinical and histopathological responses to chemotherapy were analyzed and follow-up comprised review of medical charts. RESULTS: Twelve non-responding patients were not eligible for surgery. Twenty-six patients with partial responses or stable disease were operated on. The resectability rate was 96% (25/26) and tumor-free resection margins (R0) were achieved in 68% (17/25). The overall survival of patients with M1a disease was 16 months. Patients who received chemotherapy alone had a median survival of 10 months; patients who underwent additional surgery had a median survival of 26 months (log-rank P < 0.001). CONCLUSION: The overall survival of patients with carcinoma of the distal esophagus and clinical celiac lymph node involvement is poor. Tumor-free resection margins (R0) in M1a patients with clinical response to chemotherapy are likely to be achieved and contributes to prolonged survival.


Asunto(s)
Plexo Celíaco/patología , Neoplasias Esofágicas/mortalidad , Neoplasias Esofágicas/terapia , Metástasis Linfática , Adenocarcinoma/mortalidad , Adenocarcinoma/patología , Adenocarcinoma/terapia , Adulto , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Biopsia con Aguja Fina , Carboplatino/administración & dosificación , Carcinoma de Células Escamosas/mortalidad , Carcinoma de Células Escamosas/patología , Carcinoma de Células Escamosas/terapia , Plexo Celíaco/cirugía , Cisplatino/administración & dosificación , Bases de Datos Factuales , Neoplasias Esofágicas/patología , Esofagectomía , Femenino , Humanos , Estimación de Kaplan-Meier , Laparoscopía , Escisión del Ganglio Linfático , Ganglios Linfáticos/patología , Masculino , Persona de Mediana Edad , Paclitaxel/administración & dosificación , Estudios Retrospectivos
20.
J Virol Methods ; 259: 50-53, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-29906491

RESUMEN

Since February 1st 2011, rinderpest (RP) has been officially declared eradicated worldwide. National authorities have been requested to destroy all their RP related materials. Nonetheless, their national reference laboratories performing real time reverse transcription polymerase chain reaction assays (PCR diagnostics) need RP positive control samples, since some countries still prefer to maintain diagnostic capability for RP for several reasons. In the future, a similar situation will arise for peste des petits ruminants (PPR) as the ambition has been expressed to eradicate PPR. Anticipating on this, we intended to perform qualified PCR diagnostics without use of infectious RPV or PPRV. Therefore, Newcastle disease virus (NDV) with small RNA inserts based on RPV or PPRV sequences were generated and used as positive control material. Recombinant NDVs (recNDVs) were differentially detected by previously established PCR diagnostics for RPV or PPRV. Both recNDVs contain a second PCR target showing that additional targets in NDV are feasible and would increase the diagnostic sensitivity by use of two PCR assays. RecNDV with small PCR targets is not classified as RPV or PPRV containing material, and can be used to mimic RPV or PPRV. Using these recNDVs as virus positive material contributes to the ambition of worldwide eradication, while qualified PCR diagnostics for these OIE-listed diseases remains operational.


Asunto(s)
Técnicas de Diagnóstico Molecular/métodos , Virus de la Enfermedad de Newcastle/genética , Peste de los Pequeños Rumiantes/diagnóstico , Reacción en Cadena de la Polimerasa/métodos , Estándares de Referencia , Peste Bovina/diagnóstico , Animales , Morbillivirus/genética , Virus de la Peste de los Pequeños Rumiantes/genética , ARN Viral/genética , Recombinación Genética , Sensibilidad y Especificidad
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