RESUMEN
BACKGROUND: Retransplantation candidates are disadvantaged owing to lack of good-quality liver grafts. Strategies that can facilitate transplantation of suboptimal grafts into retransplant candidates require investigation. The aim was to determine whether late liver retransplantation can be performed safely with suboptimal grafts, following normothermic machine perfusion. METHODS: A prospectively enrolled group of patients who required liver retransplantation received a suboptimal graft preserved via normothermic machine perfusion. This group was compared with both historical and contemporaneous cohorts of patient who received grafts preserved by cold storage. The primary outcome was 6-month graft and patient survival. RESULTS: The normothermic machine perfusion group comprised 26 patients. The historical (cold storage 1) and contemporaneous (cold storage 2) groups comprised 31 and 25 patients respectively. The 6-month graft survival rate did not differ between groups (cold storage 1, 27 of 31, cold storage 2, 22 of 25; normothermic machine perfusion, 22 of 26; P = 0.934). This was despite the normothermic machine perfusion group having significantly more steatotic grafts (8 of 31, 7 of 25, and 14 of 26 respectively; P = 0.006) and grafts previously declined by at least one other transplant centre (5 of 31, 9 of 25, and 21 of 26; P < 0.001). CONCLUSION: In liver retransplantation, normothermic machine perfusion can safely expand graft options without compromising short-term outcomes.
Liver transplantation is a life-saving procedure for many different diseases. In the UK, one in 10 patients awaiting transplant have had a previous liver transplant. These retransplant operations are complex, and the general belief is that a good-quality donor liver graft is required for best outcomes. However, there is a significant shortage of good-quality organs for liver transplantation, so many patients awaiting retransplantation spend longer on the waiting list. This study investigated whether a new technology, called normothermic machine perfusion, could be used to preserve lower-quality donor livers and have successful outcomes for patients undergoing retransplantation. Traditionally, good-quality livers are preserved in an ice box and the study compared the outcomes of these two different approaches. The aim was to prove that normothermic machine perfusion improves access to transplantation for this group of patients, without compromising outcomes. A group of patients who underwent retransplantation and received a lesser-quality liver preserved with normothermic machine perfusion was compared with two groups of patients who had received a transplant with traditional ice-box preservation. The complications, graft, and patient survival of the former group was compared with those in the latter two groups who underwent liver retransplantation with better-quality liver grafts. The rate of survival and adverse surgical outcomes were comparable between the groups of patients who received a liver preserved via traditional ice-box preservation, and those who received a lesser-quality liver preserved via normothermic machine perfusion. Normothermic machine perfusion can potentially expand the number of suitable donor livers available for retransplant candidates.
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Trasplante de Hígado , Supervivencia de Injerto , Humanos , Hígado , Preservación de Órganos , PerfusiónRESUMEN
The prevalence of cirrhosis due to nonalcoholic steatohepatitis (NASH) has increased 2.5-fold in the United States in the last decade. These patients pose new challenges to hepatologists given their older age and higher frequency of coexisting metabolic diseases such as obesity and diabetes compared with other etiologies of liver disease. Patients with NASH cirrhosis are at higher risk for renal and cardiovascular disease, and the presence of these extrahepatic comorbidities has a significant impact on outcomes and survival. This review outlines how NASH cirrhosis differs from other etiologies of cirrhosis including natural history, noninvasive assessment, and the challenges in the management of the complications of cirrhosis including hepatic encephalopathy and hepatocellular carcinoma. Nutritional assessment and the impact of sarcopenic obesity and frailty in this population, and strategies to address the latter, are discussed. This review also addresses liver transplantation in patients with NASH cirrhosis in relation to assessment and posttransplant care.
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Cirrosis Hepática/etiología , Enfermedad del Hígado Graso no Alcohólico/complicaciones , Factores de Riesgo Cardiometabólico , Ejercicio Físico , Humanos , Hipertensión Portal/etiología , Cirrosis Hepática/diagnóstico , Cirrosis Hepática/fisiopatología , Cirrosis Hepática/terapia , Trasplante de Hígado/efectos adversos , Neoplasias/etiología , Obesidad/etiología , Insuficiencia Renal Crónica/etiologíaRESUMEN
BACKGROUND: Systemic insulin resistance (IR) is a primary feature in non-alcoholic steatohepatitis (NASH), however, there remain limited data on tissue-specific insulin sensitivity in vivo. METHODS: We examined tissue-specific (adipose, muscle and liver) insulin sensitivity and inflammation in 16 European Caucasian patients with biopsy-confirmed NASH and in 15 healthy controls. All underwent a two-step hyperinsulinaemic euglycaemic clamp incorporating stable isotope measurements of carbohydrate and lipid metabolism with concomitant subcutaneous adipose tissue (SAT) microdialysis. RESULTS: Hepatic and muscle insulin sensitivity were decreased in patients with NASH compared with controls, as demonstrated by reduced suppression of hepatic glucose production and glucose disposal (Gd) rates following insulin infusion. In addition, rates of lipolysis were higher in NASH patients with impaired insulin-mediated suppression of free fatty acid levels. At a tissue specific level, abdominal SAT in patients with NASH was severely insulin resistant, requiring >sixfold more insulin to cause ½-maximal suppression of glycerol release when compared with healthy controls. Furthermore, patients with NASH had significantly higher circulating levels of pro-inflammatory adipocytokines than controls. CONCLUSION: NASH patients have profound IR in the liver, muscle and in particular adipose tissues. This study represents the first in vivo description of dysfunctional SAT in patients with NASH.
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Glicerol/metabolismo , Resistencia a la Insulina , Lipólisis , Hígado/metabolismo , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Grasa Subcutánea Abdominal/metabolismo , Adipoquinas/sangre , Adolescente , Adulto , Anciano , Índice de Masa Corporal , Estudios de Casos y Controles , Femenino , Gluconeogénesis , Glucosa/metabolismo , Técnica de Clampeo de la Glucosa , Hemoglobina Glucada/metabolismo , Humanos , Hipoglucemiantes/administración & dosificación , Inflamación/metabolismo , Insulina/administración & dosificación , Insulina/metabolismo , Masculino , Persona de Mediana Edad , Músculo Esquelético/metabolismoRESUMEN
BACKGROUND: Fibroscan is a quick, non-invasive technique used to measure liver stiffness (kPa), which correlates with fibrosis. To achieve a valid liver stiffness evaluation (LSE) the operator must obtain all the following three criteria: (1) ≥10 successful liver stiffness measurements; (2) IQR/median ratio <0.30 and (3) ≥60% measurement success rate. OBJECTIVES: To assess the operator training requirements and the importance of adhering to the LSE validity criteria in routine clinical practice. METHODS: We retrospectively analysed the LSE validity rates of 2311 Fibroscans performed (1 August 2008 to 31 July 2011) in our tertiary liver outpatients department at the University Hospital Birmingham, UK. The diagnostic accuracy of Fibroscan was assessed in 153 patients, by comparing LSE (valid and invalid) with the modified Ishak fibrosis stage on liver biopsy. RESULTS: Learning curve analysis highlighted that the greatest improvement in validity of LSE rates occurs in the operator's first 10 Fibroscans, reaching 64.7% validity by the 50th Fibroscan. The correlation between LSE and the fibrosis stage on liver biopsy was superior in patients with a valid LSE (n=97) compared with those with an invalid LSE (n=56) (rs 0.577 vs 0.259; p=0.022). Area under receiving operating characteristics for significant fibrosis was greater when LSE was valid (0.83 vs 0.66; p=0.048). Using an LSE cut-off of 8 kPa, the negative predictive value of valid LSE was superior to invalid LSE for the detection of significant (84% vs 71%) and advanced fibrosis (100% vs 93%). CONCLUSIONS: Fibroscan requires minimal operator training (≥10 observed on patients), and when a valid LSE is obtained, it is an accurate tool for excluding advanced liver fibrosis. To ensure the diagnostic accuracy of Fibroscan it is essential that the recommended LSE validity criteria are adhered to in routine clinical practice.
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Competencia Clínica , Diagnóstico por Imagen de Elasticidad , Adhesión a Directriz , Personal de Salud/educación , Cirrosis Hepática/diagnóstico , Hígado/patología , Área Bajo la Curva , Biopsia , Competencia Clínica/normas , Diagnóstico por Imagen de Elasticidad/métodos , Diagnóstico por Imagen de Elasticidad/normas , Inglaterra , Femenino , Humanos , Cirrosis Hepática/patología , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto , Valor Predictivo de las Pruebas , Curva ROC , Reproducibilidad de los Resultados , Estudios Retrospectivos , Sensibilidad y Especificidad , Índice de Severidad de la Enfermedad , Medicina EstatalRESUMEN
Following from similar initiatives worldwide, the U.K.'s Fisheries Science Partnership (FSP) was established in 2003 to provide the fishing industry with opportunities to propose and participate in scientific studies in collaboration with fishery scientists. Key concepts were that most of the available funding would support industry participation, that industry, not scientists, would come up with the ideas for projects, and that commercial fishing vessels and fishing methods would be used to address specific concerns of the fishing industry in a scientifically controlled manner. Nearly 100 projects had been commissioned by March 2012, covering annual time-series surveys of stocks subject to traditional assessment, and ad hoc projects on, e.g. gear selectivity, discard survival, tagging and migration and fishery development. The extent to which the results of the projects have been used by stakeholders, fishery scientists and fishery managers at a national and E.U. level is evaluated, along with the degree of industry interest and involvement, and reasons are identified for successes or failures in the uptake of the results into management and policy. Finally, the question is posed whether the programme has been successful in improving the engagement of the fishing community in the science-management process and in fostering communication and greater trust between fishers, scientists and managers.
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Conservación de los Recursos Naturales/métodos , Explotaciones Pesqueras/métodos , Proyectos de Investigación , Animales , Conducta Cooperativa , Unión Europea , Explotaciones Pesqueras/economía , Agencias Gubernamentales , Industrias , Reino UnidoAsunto(s)
Fructosa , Ácido Úrico , Adolescente , Niño , Humanos , Enfermedad del Hígado Graso no AlcohólicoRESUMEN
Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disease ranging from simple steatosis through steatohepatitis (NASH) to increasing fibrosis and eventual cirrhosis. NAFLD is the hepatic manifestation of the metabolic syndrome and has now become the most common cause of liver disease in Western countries, with the more advanced stages of disease being associated with an increased risk of liver-related morbidity and mortality. The optimal management of patients with NAFLD remains a clinical challenge. The aim of this study is to describe established and emerging strategies for the treatment of NAFLD. Relevant research and review articles were identified by searching PubMed. Selected articles referenced in these publications were also examined. Good quality randomized controlled studies have demonstrated the need for multifaceted lifestyle interventions in patients with NAFLD including the need for diet, exercise and behavioural counselling. Despite several trials of pharmacological agents, no highly effective treatment yet exists, with surgery representing the mainstay for advanced disease. A multidisciplinary approach, with a major focus on lifestyle change, represents best treatment pending the development of new therapeutic options.
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Terapia por Ejercicio/métodos , Hígado Graso/terapia , Cirrosis Hepática/terapia , Terapia Combinada , Dieta Reductora , Progresión de la Enfermedad , Hígado Graso/genética , Hígado Graso/cirugía , Humanos , Resistencia a la Insulina/genética , Cirrosis Hepática/genética , Cirrosis Hepática/cirugía , Enfermedad del Hígado Graso no AlcohólicoRESUMEN
INTRODUCTION: Tremor-dominant (TD), indeterminate/mixed (ID/M) and postural instability gait difficulty/akinetic-rigid (PIGD/AR) are commonly used subtypes to categorize Parkinson's disease (PD) patients based on their most prominent motor signs. Three different algorithms to determine these motor subtypes are used. Here, we examined if PD subtypes are consistent among algorithms and if subtype stability over time depends on the applied algorithm. METHODS: Using a large longitudinal PD database, we applied 3 published algorithms of PD motor subtype classification in two sets of analyses: 1) cross-sectional analysis in 1185 patients, determining the prevalence of subtypes in 5-year intervals of disease duration; 2) longitudinal analysis of 178 patients, comparing subtypes of individual patients at baseline (within 5 years of diagnosis) and at follow-up ≥ 5 years after baseline. RESULTS: Cross-sectionally, prevalence of subtypes varied widely among the 3 algorithms: 5-32% TD, 9-31% ID/M, and 59-75% PIGD/AR. For all 3 algorithms, cross-sectional analysis showed a marked decline of TD prevalence with disease duration and a corresponding increase in PIGD/AR prevalence, driven by increasing gait/balance scores over time. Longitudinally, only 15-36% of baseline TD patients were still categorized as TD at 6.2 ± 1.0 years of follow-up. In 15-39% of baseline TD patients, the subtype changed to ID/M, and 46-50% changed to PIGD/AR. This shift was observed using all 3 algorithms. CONCLUSION: PD motor subtypes determined by different established algorithms are inconsistent and unstable over time. Lack of subtype fidelity should be considered when interpreting biomarker-subtype correlation and highlights the need for better definition of PD subtypes.
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Algoritmos , Trastornos Neurológicos de la Marcha/fisiopatología , Enfermedad de Parkinson/clasificación , Enfermedad de Parkinson/fisiopatología , Equilibrio Postural/fisiología , Temblor/fisiopatología , Anciano , Estudios Transversales , Bases de Datos Factuales , Femenino , Trastornos Neurológicos de la Marcha/etiología , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/complicaciones , Prevalencia , Temblor/etiologíaRESUMEN
Primary nonfunction (PNF) in the early postoperative period following liver transplantation is fatal if not managed appropriately with early retransplantation. Severe early allograft dysfunction can mimic PNF. The identification of treatable causative factors such as sepsis, hepatic artery, or portal vein thrombosis is essential to distinguish it from PNF, and their early management may avoid the need for retransplantation. In this article, we describe a case of sepsis-induced severe liver dysfunction from a contaminated graft perfused with normothermic machine perfusion (NMP), which presented in a manner similar to PNF. The implications of graft contamination are poorly described. To our knowledge, this is the first report of bacterial contamination of a graft that underwent NMP and subsequently caused severe sepsis in the recipient. The conditions created with NMP may be optimal for certain micro-organisms to thrive. The role of the liver in the immune system is complex as it provides an essential barrier to enterically derived portal venous pathogens and produces numerous acute phase proteins that augment the systemic immune response. Additionally, the liver is also known to restrain harmful and excessive systemic immune responses such as those that occur with the sepsis syndrome. The relationship between bacterial graft contamination, sepsis, and graft dysfunction may be multidirectional.
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Contaminación de Medicamentos , Trasplante de Hígado/efectos adversos , Soluciones Preservantes de Órganos/efectos adversos , Preservación de Órganos/efectos adversos , Complicaciones Posoperatorias/etiología , Sepsis/etiología , Femenino , Humanos , Persona de Mediana Edad , Perfusión , Donantes de TejidosRESUMEN
Interferon (IFN) regulatory factor-1 (IRF-1) is a transcription factor that has apoptotic anti-tumor activity. In breast cancer cell types, IRF-1 is implicated in mediating apoptosis by both novel and established anti-tumor agents, including the anti-estrogens tamoxifen and faslodex. Here we demonstrate that in MDA468 breast cancer cells, apoptosis by IFN-gamma is mediated by IRF-1 and IFN-gamma, and IRF-1-induced apoptosis is caspase-mediated. IRF-1 induction results in cleavage of caspase-8, -3 and -7, and application of caspase inhibitors attenuate activated cleavage products. IRF-1-induced apoptosis involves caspase-8 since apoptosis is significantly decreased by the caspase-8-specific inhibitor IETD, c-FLIP expression and in caspase-8-deficient cancer cells. Furthermore, we demonstrate that IRF-1-induced apoptosis requires fas-associated death domain (FADD) since dominant-negative FADD expressing cells resist IRF-1-induced apoptosis and activated downstream products. Immunofluorescent studies demonstrate perinuclear colocalization of FADD and caspase-8. Despite the known role of FADD in mediating death-ligand induced apoptosis, neutralizing antibodies against classical death receptors do not inhibit IRF-1 induced apoptosis, and no secreted ligand appears to be involved since MDA468 coincubated with IRF-1 transfected cells do not apoptose. Therefore, we demonstrate that IRF-1 induces a ligand-independent FADD/caspase-8-mediated apoptosis in breast cancer cells.
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Apoptosis/efectos de los fármacos , Neoplasias de la Mama/patología , Proteína de Dominio de Muerte Asociada a Fas/metabolismo , Factor 1 Regulador del Interferón/metabolismo , Interferón gamma/farmacología , Transducción de Señal , Receptor fas/metabolismo , Neoplasias de la Mama/metabolismo , Caspasa 3/metabolismo , Caspasa 8/metabolismo , Caspasa 9/metabolismo , Caspasas/metabolismo , Proteína de Dominio de Muerte Asociada a Fas/antagonistas & inhibidores , Proteína de Dominio de Muerte Asociada a Fas/genética , Técnica del Anticuerpo Fluorescente , Genes Dominantes , Humanos , Immunoblotting , Ligandos , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF , Receptores del Factor de Necrosis Tumoral/metabolismo , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Fracciones Subcelulares , Ligando Inductor de Apoptosis Relacionado con TNF/metabolismo , Células Tumorales CultivadasRESUMEN
Platelet-derived growth factor (PDGF) is an important serum regulator of erythropoiesis in vitro. We have now obtained evidence suggesting that PDGF-like molecules may also modulate erythropoiesis in vivo. Western blot analysis of cytoplasmic extracts from Rauscher murine erythroleukemia cells and phenylhydrazine-treated mouse splenic erythroid cells revealed the presence of several PDGF-like proteins. The presence of PDGF-like proteins in the cytoplasm of these two erythroid cell types was confirmed by immunohistochemical staining. Using a serum-free biologic assay, PDGF-like biological activity was found in cell lysates and conditioned medium of both Rauscher cells and phenylhydrazine-treated mouse erythroid cells. Subcellular localization experiments revealed the biological activity to be concentrated in the cytosolic fraction. Using a series of antibodies to hematopoietic growth factors we demonstrated that PDGF-like biological activity was specifically immunoprecipitated by both monoclonal and polyclonal anti-human PDGF antibodies but not by antibodies to burst-promoting activity, granulocyte-macrophage colony-stimulating factor, IL-3, or erythropoietin. Taken together, the data are consistent with the hypothesis that PDGF-like molecules play a role in the regulation of mammalian erythropoiesis in vivo.
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Células Madre Hematopoyéticas/citología , Linfocitos/metabolismo , Factor de Crecimiento Derivado de Plaquetas/biosíntesis , Células Tumorales Cultivadas/metabolismo , Animales , Western Blotting , Línea Celular , Células Cultivadas , Células Clonales , Citosol/metabolismo , Electroforesis en Gel de Poliacrilamida , Células Madre Hematopoyéticas/efectos de los fármacos , Humanos , Inmunohistoquímica , Leucemia Eritroblástica Aguda , Leucemia Mielógena Crónica BCR-ABL Positiva , Ratones , Factor de Crecimiento Derivado de Plaquetas/aislamiento & purificación , Factor de Crecimiento Derivado de Plaquetas/farmacología , Fracciones Subcelulares/metabolismoRESUMEN
AIMS: To audit the safety of differing protocol-driven early-discharge policies, from two sites, for low-risk acute upper gastrointestinal (GI) bleeding and determine if default early (<24 h) in-patient endoscopy is necessary. METHODS: All patients with low-risk acute upper GI bleeding presenting to two separate hospital sites in Leeds from August 2002 to March 2005 were identified. Both hospitals operate nurse-led process-driven protocols for discharge within 24 h, but only one includes default endoscopy. Relevant information was obtained from patients' notes, patient administration systems, discharge letters and endoscopy records. RESULTS: 120 patients were admitted to site A and 74 to site B. Median length of stay on the clinical decisions unit was 12.6 h at site A and 9.4 h at site B (p = 0.045). Oesophagogastroduodenoscopy was performed on 89/120 (74%) patients at site A compared with only 7/74 (9%) at site B (p<0.001). Six of 120 (5%) patients from site A were admitted to hospital for further observation compared with 6/74 (8%) from site B (p = 0.38). Of the remaining patients, all were discharged within 24 h, and 8/114 (7%) at site A vs 17/68 (25%) at site B were given hospital clinic follow-up (p<0.001). None of the 194 patients had further bleeding or complications within 30 days. CONCLUSIONS: Patients admitted with a low-risk acute upper GI bleeding can be managed safely by a nurse-led process-driven protocol, based on readily available clinical and laboratory variables, with early discharge <24 h. Avoiding in-patient endoscopy appears to be safe but at the price of greater clinic follow-up.
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Endoscopía del Sistema Digestivo/normas , Hemorragia Gastrointestinal/diagnóstico , Alta del Paciente , Enfermedad Aguda , Adolescente , Adulto , Anciano , Endoscopía del Sistema Digestivo/enfermería , Femenino , Hemorragia Gastrointestinal/etiología , Humanos , Tiempo de Internación , Masculino , Persona de Mediana Edad , Selección de Paciente , Medición de Riesgo , Factores de RiesgoRESUMEN
We conducted a case-control study of nasopharyngeal carcinoma among Malaysian Chinese to test inhalants, salted fish consumption, and use of tobacco, alcohol, and nasal ointments as risk factors for the disease. Interviews with 100 cases and 100 controls indicated that salted fish consumption during childhood was a significant risk factor (relative risk, 3.0; p = 0.04); childhood daily consumption of this food item compared to nonconsumption carried a relative risk of 17.4 [95% confidence interval = (2.7, 111.1)]. Occupational exposure to smokes (relative risk, 6.0; p = 0.006) and to dusts (relative risk, 4.0; p less than 0.001) was also significantly associated with nasopharyngeal carcinoma. The two risk factors (consumption of salted fish and exposure to smoke and/or dust) were independent of each other. There was no association between nasopharyngeal carcinoma and tobacco, alcohol, or nasal ointments.
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Consumo de Bebidas Alcohólicas , Productos Pesqueros/efectos adversos , Neoplasias Nasofaríngeas/etiología , Fumar , Administración Intranasal/efectos adversos , Adulto , Carcinoma de Células Escamosas/etiología , China/etnología , Conducta Alimentaria , Femenino , Humanos , Malasia , Masculino , Persona de Mediana Edad , RiesgoRESUMEN
Good cell culture practice and characterization of the cell lines used are of critical importance in in vitro genotoxicity testing. The objective of this initiative was to make continuously available stocks of the characterized isolates of the most frequently used mammalian cell lines in genotoxicity testing anywhere in the world ('IVGT' cell lines). This project was organized under the auspices of the International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute (HESI) Project Committee on the Relevance and Follow-up of Positive Results in In Vitro Genetic Toxicity (IVGT) Testing. First, cell isolates were identified that are as close as possible to the isolate described in the initial publications reporting their use in genotoxicity testing. The depositors of these cell lines managed their characterization and their expansion for preparing continuously available stocks of these cells that are stored at the European Collection of Cell Cultures (ECACC, UK) and the Japanese Collection of Research Bioresources (JCRB, Japan). This publication describes how the four 'IVGT' cell lines, i.e. L5178Y TK+/- 3.7.2C, TK6, CHO-WBL and CHL/IU, were prepared for deposit at the ECACC and JCRB cell banks. Recommendations for handling these cell lines and monitoring their characteristics are also described. The growth characteristics of these cell lines (growth rates and cell cycles), their identity (karyotypes and genetic status) and ranges of background frequencies of select endpoints are also reported to help in the routine practice of genotoxicity testing using these cell lines.
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Técnicas de Cultivo de Célula/normas , Daño del ADN/efectos de los fármacos , Linfocitos/efectos de los fármacos , Linfoma/tratamiento farmacológico , Pruebas de Mutagenicidad/normas , Mutágenos/toxicidad , Estándares de Referencia , Animales , Células CHO , Células Cultivadas , Cricetulus , Relación Dosis-Respuesta a Droga , Humanos , Linfocitos/citología , Linfocitos/metabolismo , Linfoma/metabolismo , Linfoma/patología , Ratones , Cariotipificación Espectral , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Shedding of extracellular membranes from the cell surface may be one of the means through which cells communicate with one another. In an attempt to elucidate whether cell surface exfoliation is a directed or random process, we investigated the membrane lipid and protein composition and membrane lipid order of shed extracellular membranes and of plasma membranes from which they arose in normal circulating lymphocytes and in the B-lymphoblastoid cell lines Raji, WI HF2 729 and the T-lymphoblastoid cell line Jurkat. Extracellular membranes derived from transformed cell lines were more rigid as assessed by steady state polarization of 1,6-diphenylhexatriene (DPH) and were highly enriched in cholesterol when compared with the corresponding plasma membrane. The extracellular membranes from normal lymphocytes, on the other hand, were more fluid and contained more polyunsaturated acyl chains than did the plasma membranes from these cells. Our results suggest that extracellular membranes are shed from specialized regions of the lymphocyte plasma membrane and that membrane exfoliation is likely to be a directed event.
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Membrana Celular/ultraestructura , Activación de Linfocitos , Linfocitos/ultraestructura , Animales , Línea Celular , Difenilhexatrieno , Polarización de Fluorescencia , Fluidez de la Membrana , Lípidos de la Membrana/análisis , Proteínas de la Membrana/análisisRESUMEN
We have previously reported that neurotensin (NT) is released from the small intestine and elevated in the hepatic-portal circulation in response to the perfusion of the small intestine with a micellar solution of oleic acid. In order to determine the minimum acyl chain length and whether the presence of a carboxylic acid is necessary for the stimulation of NT release, the small intestine of anesthetized rats was perfused with test solutions of fatty acids of 2-, 4-, 8-, or 18-carbons or fatty alcohols of 2-, 4-, or 8-carbons at a concentration of 1 mM prepared in 2.4 mM taurodeoxycholate in 0.9% NaCl. Blood samples, collected from the superior mesenteric vein immediately before the start of the test perfusion and at 15-min intervals thereafter, were extracted immediately and radioimmunoassayed for NT-like immunoreactivity (NTLI) with a C-terminal-directed antiserum. Perfusions of fatty acids with 4 or more carbons and alcohols of 2 or more carbons resulted in a significant elevation (P less than 0.05) in plasma levels of NTLI above the values obtained before the onset of perfusion. Perfusions with ethanol resulted in a value of 4.3 +/- 0.03 mg/dl (SEM) in blood from the superior mesenteric vein while there was no increase in ethanol levels in the peripheral circulation. Perfusion with taurodeoxycholate and 0.9% NaCl alone had no significant effect on plasma levels of the NTLI. In order to characterize the chemical nature of the elevated NTLI, plasma samples from animals perfused with test solution were collected, extracted, pooled, and subjected to HPLC. NT and its N-terminal metabolite, NT(1-8), were quantitated. NT was defined as material having the same retention time as synthetic NT standard and having comparable measurements using N- and C-terminal-directed antisera. Perfusions of fatty acids of four or more carbons and alcohols of two or more carbons resulted in a 2- to 4-fold increase of both NT and NT(1-8) levels in plasma. It is particularly interesting that perfusion with ethanol (2-carbons) causes an elevation in plasma NT, because perfusion with acetic acid (2-carbons) does not increase NTLI. The fact that perfusion of ethanol is effective in releasing intestinal NT suggests that NT may mediate some of the biological effects observed after the consumption of alcohol.
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Alcoholes/farmacología , Ácidos Grasos/farmacología , Intestino Delgado/metabolismo , Neurotensina/metabolismo , Acetatos/farmacología , Ácido Acético , Animales , Butanoles/farmacología , Butiratos/farmacología , Ácido Butírico , Caprilatos/farmacología , Cromatografía , Etanol/farmacología , Masculino , Neurotensina/sangre , Octanoles/farmacología , Ácidos Oléicos/farmacología , Ratas , Ratas Endogámicas , Estimulación Química , Ácido Taurodesoxicólico/farmacologíaRESUMEN
The separate effects contributed by dietary cholesterol and dietary fat on several parameters of biliary lipid metabolism thought to be important in the genesis of cholesterol gallstones were examined in squirrel and cebus monkeys fed diets containing either corn or coconut oil from birth. Half the monkeys were also fed cholesterol. In gallstone-susceptible squirrel monkeys, corn oil tended to decrease the bile acid pool size and decrease the percentage of taurochenodeoxycholic acid. Dietary cholesterol effected major changes in gallbladder bile molar percent lipid composition with significantly increased cholesterol saturation indices that exceeded the metastable-labile limits. The supersaturated biles notwithstanding, none of the monkeys developed gallstones and only one had cholesterol crystals in its bile. By contrast, the gallstone-resistant cebus monkeys experienced less remarkable shifts in biliary lipid composition during dietary challenges of cholesterol and fat. The data are consistent with the hypothesis that neither a diminished bile acid pool size nor bile supersaturated with cholesterol are sufficient in themselves to result in gallstone formation in immature monkeys.