RESUMEN
Co-transplantation of hematopoietic stem cells with those engineered to express leukemia-reactive T-cell receptors (TCRs) and differentiated ex vivo into precursor T cells (preTs) may reduce the risk of leukemia relapse. As expression of potentially self-(leukemia-) reactive TCRs will lead to negative selection or provoke autoimmunity upon thymic maturation, we investigated a novel concept whereby TCR expression set under the control of an inducible promoter would allow timely controlled TCR expression. After in vivo maturation and gene induction, preTs developed potent anti-leukemia effects. Engineered preTs provided protection even after repeated leukemia challenges by giving rise to effector and central memory cells. Importantly, adoptive transfer of TCR-transduced allogeneic preTs mediated anti-leukemia effect without evoking graft-versus-host disease (GVHD). Earlier transgene induction forced CD8(+) T-cell development was required to obtain a mature T-cell subset of targeted specificity, allowed engineered T cells to efficiently pass positive selection and abrogated the endogenous T-cell repertoire. Later induction favored CD4 differentiation and failed to produce a leukemia-reactive population emphasizing the dominant role of positive selection. Taken together, we provide new functional insights for the employment of TCR-engineered precursor cells as a controllable immunotherapeutic modality with significant anti-leukemia activity.
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Enfermedad Injerto contra Huésped/prevención & control , Efecto Injerto vs Leucemia/inmunología , Leucemia Mieloide/inmunología , Células Precursoras de Linfocitos T/inmunología , Receptores de Antígenos de Linfocitos T/genética , Traslado Adoptivo , Animales , Citometría de Flujo , Ingeniería Genética , Enfermedad Injerto contra Huésped/mortalidad , Trasplante de Células Madre Hematopoyéticas , Humanos , Leucemia Mieloide/mortalidad , Leucemia Mieloide/terapia , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Transgénicos , Ovalbúmina/genética , Regiones Promotoras Genéticas/genética , Receptores de Antígenos de Linfocitos T/inmunología , Trasplante HomólogoRESUMEN
The currently highest-performance Fe-Nd-B magnets show limited cost-effectiveness and lifetime due to their rare-earth (RE) content. The demand for novel hard magnetic phases with more widely available RE metals, reduced RE content or, even better, completely free of RE metals is therefore tremendous. The chances are that such materials still exist given the large number of as yet unexplored alloy systems. To discover such phases, an elaborate concept is necessary which can restrict and prioritize the search field while making use of efficient synthesis and analysis methods. It is shown that an efficient synthesis of new phases using heterogeneous non-equilibrium diffusion couples and reaction sintering is possible. Quantitative microstructure analysis of the domain pattern of the hard magnetic phases can be used to estimate the intrinsic magnetic parameters (saturation polarization from the domain contrast, anisotropy constant from the domain width, Curie temperature from the temperature dependence of the domain contrast). The probability of detecting TM-rich phases for a given system is high, therefore the approach enables one to scan through even higher component systems with one single sample. The visualization of newly occurring hard magnetic phases via their typical domain structure and the correlation existing between domain structure and intrinsic magnetic properties allows an evaluation of the industrial relevance of these novel phases.
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Imanes/química , Anisotropía , Metales de Tierras Raras/química , TemperaturaRESUMEN
The hydrogen storage properties of Li(7)VN(4) and Li(7)MnN(4) were investigated both by experiment and by density functional theory calculations. Li(7)VN(4) did not sorb hydrogen under our experimental conditions. Li(7)MnN(4) was observed to sorb 7 hydrogen atoms through the formation of LiH, Mn(4)N, and ammonia gas. An applied pressurized mixture of H(2)/Ar and H(2)/N(2) gases was helpful to mitigate the release of NH(3) but could not prevent its formation. The introduction of N(2) also caused weight gain of the sample by re-nitriding the absorbed products LiH and Mn(4)N, which correlated with the presence of Li(2)NH, LiNH(2), and Mn(2)N detected by X-ray diffraction. While our observed results for Li(7)VN(4) and Li(7)MnN(4) differ in detail, they are in overall qualitative agreement with our theoretical work, which strongly suggests that both compounds are unlikely to form quaternary hydrides.
RESUMEN
When we ask people what they value most, health is usually top of the list. While effective care is available for many chronic diseases, the fact remains that for the patient, the tax payer and the whole of society: prevention is better than cure. Diabetes and its complications are a serious threat to the survival and well-being of an increasing number of people. It is predicted that one in ten Europeans aged 20-79 will have developed diabetes by 2030. Once a disease of old age, diabetes is now common among adults of all ages and is beginning to affect adolescents and even children. Diabetes accounts for up to 18 % of total healthcare expenditure in Europe. The good news is that diabetes is preventable. Compelling evidence shows that the onset of diabetes can be prevented or delayed greatly in individuals at high risk (people with impaired glucose regulation). Clinical research has shown a reduction in risk of developing diabetes of over 50 % following relatively modest changes in lifestyle that include adopting a healthy diet, increasing physical activity, and maintaining a healthy body weight. These results have since been reproduced in real-world prevention programmes. Even a delay of a few years in the progression to diabetes is expected to reduce diabetes-related complications, such as heart, kidney and eye disease and, consequently, to reduce the cost to society. A comprehensive approach to diabetes prevention should combine population based primary prevention with programmes targeted at those who are at high risk. This approach should take account of the local circumstances and diversity within modern society (e.g. social inequalities). The challenge goes beyond the healthcare system. We need to encourage collaboration across many different sectors: education providers, non-governmental organisations, the food industry, the media, urban planners and politicians all have a very important role to play. Small changes in lifestyle will bring big changes in health. Through joint efforts, more people will be reached. The time to act is now.
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Diabetes Mellitus Tipo 2/prevención & control , Implementación de Plan de Salud/normas , Directrices para la Planificación en Salud , Conducta , Presupuestos , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/economía , Dieta , Europa (Continente) , Humanos , Actividad Motora , Garantía de la Calidad de Atención de Salud , Factores de RiesgoRESUMEN
BACKGROUND: The marked increase of type 2 diabetes necessitates active development and implementation of efficient prevention programs. A European level action has been taken by launching the IMAGE project to unify and improve the various prevention management concepts, which currently exist within the EU. This report describes the background and the methods used in the development of the IMAGE project quality indicators for diabetes primary prevention programs. It is targeted to the persons responsible for diabetes prevention at different levels of the health care systems. METHODS: Development of the quality indicators was conducted by a group of specialists representing different professional groups from several European countries. Indicators and measurement recommendations were produced by the expert group in consensus meetings and further developed by combining evidence and expert opinion. RESULTS: The quality indicators were developed for different prevention strategies: population level prevention strategy, screening for high risk, and high risk prevention strategy. Totally, 22 quality indicators were generated. They constitute the minimum level of quality assurance recommended for diabetes prevention programs. In addition, 20 scientific evaluation indicators with measurement standards were produced. These micro level indicators describe measurements, which should be used if evaluation, reporting, and scientific analysis are planned. CONCLUSIONS: We hope that these quality tools together with the IMAGE guidelines will provide a useful tool for improving the quality of diabetes prevention in Europe and make different prevention approaches comparable.
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Diabetes Mellitus Tipo 2/prevención & control , Implementación de Plan de Salud/normas , Directrices para la Planificación en Salud , Indicadores de Calidad de la Atención de Salud , Europa (Continente) , Encuestas Epidemiológicas , HumanosRESUMEN
FKBP12 is best known as the target of the widely used immunosuppressive drug FK506 but may also play a role in neuronal survival. Nonimmunosuppressive ligands of FKBP12 have been shown to have neuroprotective and neuroregenerative activity both in vitro and in vivo, stimulating interest in the development of high-throughput screens to rapidly identify novel ligands. FKBP12 was expressed as a His(6)-fusion in bacteria and purified by metal ion affinity and gel filtration chromatography. A high-throughput fluorescence polarization assay was developed to identify novel ligands of FKBP12. Dissociation constant values of known FKBP12 ligands measured by the new method agreed closely with K(i) values obtained by assaying inhibition of the rotamase activity of the enzyme. The fluorescence polarization assay is rapid, robust, and inexpensive and does not generate radioactive waste. It is very well suited for high-throughput screening efforts.
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Polarización de Fluorescencia/métodos , Ligandos , Proteína 1A de Unión a Tacrolimus/metabolismo , Evaluación Preclínica de Medicamentos/métodos , Histidina/genética , Humanos , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Reproducibilidad de los Resultados , Proteína 1A de Unión a Tacrolimus/genética , Proteína 1A de Unión a Tacrolimus/aislamiento & purificaciónRESUMEN
The present study examined the short-term stability of personality trait scores from the Revised NEO Personality Inventory (NEO-PI-R) among 230 opioid-dependent outpatients. The NEO-PI-R is a 240-item empirically developed measure of the five-factor model of personality (Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness). Participants completed the NEO-PI-R at admission and again approximately 19 weeks later. Results indicated fair to good stability for all NEO-PI-R factor domain scores, with coefficients ranging from .68 to .74. Stability of NEO-PI-R scores was decreased among potentially invalid response patterns but was not significantly affected by drug-positive versus drug-negative status at follow-up.
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Trastornos Relacionados con Opioides/diagnóstico , Inventario de Personalidad , Adulto , Análisis de Varianza , Baltimore , Femenino , Estudios de Seguimiento , Humanos , Masculino , Antagonistas de Narcóticos/uso terapéutico , Trastornos Relacionados con Opioides/psicología , Trastornos Relacionados con Opioides/rehabilitación , Reproducibilidad de los ResultadosRESUMEN
Studies of personality and problem behaviors may begin with analyses of the problem and develop hypotheses about personality traits that might be relevant; or they may begin with models of personality and explore links to behavior. Because it is well validated and relatively comprehensive, the Five-Factor Model (FFM) of personality lends itself to systematic exploratory studies that may sometimes lead to unanticipated findings. In this article, we review a program of research in a high-risk, disadvantaged population that illustrates the utility of the FFM in understanding health risk behavior. Previous analyses showed that behavior associated with the risk of HIV infection can be predicted from the personality dispositions of Neuroticism and (low) Conscientiousness.
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Infecciones por VIH/psicología , Trastornos Mentales/psicología , Trastornos de la Personalidad/psicología , Asunción de Riesgos , Adolescente , Adulto , Femenino , Infecciones por VIH/transmisión , Conocimientos, Actitudes y Práctica en Salud , Humanos , Masculino , Persona de Mediana Edad , Determinación de la Personalidad , Trastornos de la Personalidad/diagnóstico , Sexo SeguroRESUMEN
OBJECTIVE: It has been reported that the human temperament dimensions of novelty seeking and harm avoidance are associated with polymorphisms in the D(4) dopamine receptor gene (D4DR) and the serotonin-transporter-linked promoter region (5-HTTLPR), respectively. Although these findings are consistent with Cloninger's hypothesized psychobiological model of temperament and character, many studies failed to replicate these findings. In the present study the authors tested whether the psychobiological model taps the genetic architecture of personality by exploring associations between these candidate genes and the dimensions of the Temperament and Character Inventory and by examining its phenotypic structure. METHOD: Of the 946 male and female participants in the Baltimore Longitudinal Study of Aging to whom the Temperament and Character Inventory was administered, 587 were genotyped for a polymorphism with a 48-base-pair repeat in the D4DR gene and 425 were genotyped for a 44-base-pair insertion or deletion in the 5-HTTLPR polymorphism. RESULTS: There was no significant association between D4DR polymorphisms and novelty seeking. The authors also failed to find an association between 5-HTTLPR polymorphisms and harm avoidance. The factor structure of the Temperament and Character Inventory did not reveal the hypothesized phenotypic structure. CONCLUSIONS: This investigation produced no support for the temperament-character model at either the biological or psychological level.
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Proteínas Portadoras/genética , Carácter , Glicoproteínas de Membrana/genética , Proteínas de Transporte de Membrana , Proteínas del Tejido Nervioso , Inventario de Personalidad/estadística & datos numéricos , Personalidad/genética , Receptores de Dopamina D2/genética , Serotonina/genética , Temperamento , Adulto , Anciano , Anciano de 80 o más Años , Análisis Factorial , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Modelos Genéticos , Modelos Psicológicos , Personalidad/clasificación , Determinación de la Personalidad/estadística & datos numéricos , Fenotipo , Polimorfismo Genético , Regiones Promotoras Genéticas/genética , Receptores de Dopamina D4 , Proteínas de Transporte de Serotonina en la Membrana PlasmáticaRESUMEN
Several fluoresceinated FKBP12 ligands have been prepared for a high-throughput fluorescence polarization assay. K(i)s for FKBP12 rotamase inhibition by these ligands range from 1.3 microM to 32 nM, and their design is based on X-ray crystal structures of FKBP12 complexed with known immunophilin ligands.
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Colorantes Fluorescentes/síntesis química , Inmunofilinas/química , Cristalografía por Rayos X , Fluoresceína/química , Inmunoensayo de Polarización Fluorescente , Colorantes Fluorescentes/farmacología , Ligandos , Unión Proteica , Tacrolimus/metabolismo , Proteínas de Unión a TacrolimusRESUMEN
Although developmental theories and popular accounts suggest that midlife is a time of turmoil and change, longitudinal studies of personality traits have generally found stability of rank order and little or no change in mean levels. Using data from 2,274 men and women in their 40s retested after 6 to 9 years, the present study examined two hypotheses: (a) that retest correlations should be no higher than about .60 and (b) that there should be small decreases in Neuroticism, Extraversion, and Openness, and small increases in Agreeableness and Conscientiousness. The study also explored the effects of recalled life events on subsequent personality scores. Results did not support the first hypothesis; uncorrected retest correlations uniformly exceeded .60. This was true for all personality traits, including facets of Agreeableness and Conscientiousness not previously included in longitudinal studies. The hypothesized decreases in Neuroticism, Extraversion, and Openness were found, but Conscientiousness showed a small decrease instead of the predicted increase. Life events in general showed very little influence on the levels of personality traits, although some effects were seen for changes in job and marital status that warrant further research.
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Envejecimiento/psicología , Desarrollo Humano , Acontecimientos que Cambian la Vida , Inventario de Personalidad , Personalidad , Femenino , Estudios de Seguimiento , Humanos , Masculino , Estado Civil , Persona de Mediana Edad , North Carolina , Reproducibilidad de los ResultadosRESUMEN
The finding of personality stability in adulthood may be counterintuitive to people who perceive a great deal of change in their own personality. The purpose of this study is to determine whether self-reported perceived changes in personality are associated with actual changes based on a 6- to 9-year follow-up of 2,242 middle-aged male and female participants of the UNC Alumni Heart Study (UNCAHS). Respondents completed the Revised NEO Personality Inventory on two occasions and were asked to reflect back over a 6-year period and assess changes in their personality. The majority of respondents (n = 1,177; 52.5%) reported they had "stayed the same," while 863 (38.5%) reported they had "changed a little" and 202 (9%) reported they had "changed a good deal." Coefficients of personality profile agreement computed to evaluate global personality change for the three perceived change groups were essentially equivalent. Further, directional analyses of domain-specific changes in personality showed that perceived changes were weak predictors of residual gain scores. In an absolute sense, perceptions of stability or change were discordant in 8 of 15 (53%) comparisons. Self-perceptions of change are not an adequate substitute for objective assessments.
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Envejecimiento/psicología , Personalidad , Autoimagen , Análisis de Varianza , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , North CarolinaRESUMEN
OBJECTIVE: To investigate the relationship between anxiety and depression and reporting of knee pain in the community. METHODS: Subjects (n = 374) were community volunteers aged 40 years and above who are participants in the Baltimore Longitudinal Study of Aging, a prospective multidisciplinary research study of normative aging. Knee pain was defined by the First National Health and Nutrition Examination Survey question "have you ever had pain in or around your knee on most days for at least one month?"; anxiety and depression were measured by the relevant subscales of the Arthritis Impact Measurement Scales questionnaire. All subjects had standing anteroposterior radiographs, read for Kellgren and Lawrence (K + L) grade. RESULTS: After adjustment for age, women reporting "ever" knee pain had significantly higher anxiety scores than those reporting "never" pain (3.06 +/- 0.26 versus 2.35 +/- 0.17; P = 0.025). Pain reporting was related neither to anxiety scores in men, nor to depression in either sex. Analysis stratified by radiographic severity, adjusted for age and gender, showed that differences in anxiety were confined to those reporting knee pain in the absence of radiographic change (i.e., K + L grade 0). CONCLUSIONS: In the community, women reporting knee pain in the absence of radiographic osteoarthritis have higher anxiety scores than those without pain. Depression was not significantly related to knee pain in this population. Psychosocial factors may explain some of the discrepancy between reported knee pain and structural change as seen on x-ray.
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Envejecimiento , Ansiedad/complicaciones , Depresión/complicaciones , Articulación de la Rodilla , Dolor/etiología , Dolor/psicología , Anciano , Ansiedad/diagnóstico , Baltimore , Depresión/diagnóstico , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Encuestas y CuestionariosRESUMEN
The objective of this study was to determine if maintenance of systolic blood pressure (BP) within a high range or low range among treated hypertensive patients increases the risk of memory decline. Biennial neuropsychological evaluations were performed on 158 hypertensive subjects. Decline/year was measured on the Cued Selective Reminding test (total free recall and delayed recall) in three systolic BP groups (low-i.e., mean systolic BP during the follow-up period < 135 mm Hg; intermediate-i.e., 135 mm Hg < or = mean systolic BP < or = 150 mm Hg; high-i.e., mean systolic BP > 150 mm Hg). In total free recall, the three systolic BP groups had significantly different declines per year (P = .02), with patients in the high subgroup showing the greatest decline. In delayed recall, the three systolic BP groups also showed significantly different declines per year (P = .04), with patients in the low subgroup having the greatest decline. Chronically elevated systolic BP > 150 mm Hg is associated with accelerated memory decline compared to older treated hypertensive patients with systolic BP in an intermediate range. Chronically maintained systolic BP within a low normal range < 135 mm Hg in older treated hypertensive subjects may be associated with accelerated memory decline, specifically in a test of delayed memory recall, compared to patients with systolic BP in an intermediate range. Optimal regulation of systolic BP may be a potential modifiable risk factor to prevent or minimize memory loss in older hypertensive patients.
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Presión Sanguínea/fisiología , Hipertensión/complicaciones , Trastornos de la Memoria/etiología , Trastornos de la Memoria/prevención & control , Anciano , Antihipertensivos/uso terapéutico , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Hipertensión/tratamiento farmacológico , Masculino , Trastornos de la Memoria/diagnóstico , Persona de Mediana Edad , Pruebas Neuropsicológicas , Estudios Retrospectivos , Índice de Severidad de la EnfermedadRESUMEN
A 28-year-old man stabbed both his wife and his 3-year-old son to death, before unsuccessfully attempting to commit suicide. The incident occurred against a background of marital conflict. The child's body exhibited six tentative wounds to the skin in the area of the heart, with no corresponding defects in the overlying clothing, a pattern normally seen only in suicide. Their presence can be explained by the fact that this can be considered an extended suicide, the father's motivation for the killing being comparable to that for true suicide. However, wounds of this nature can be produced in such cases only if the victim is severely limited in his ability to defend himself, here due to the superior physical strength of the father.
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Autopsia , Padre/psicología , Homicidio/psicología , Traumatismos del Cuello/patología , Piel/lesiones , Intento de Suicidio/psicología , Heridas Punzantes/patología , Adulto , Preescolar , Femenino , Humanos , Masculino , MotivaciónRESUMEN
The purpose of this study was to determine whether treatments for life-threatening ventricular arrhythmias are associated with quality-of-life (QOL) and psychological distress. Multidimensional measures of QOL and psychological distress were used to cross-sectionally compare patients with ICDs to patients treated with antiarrhythmic drugs and patients without serious cardiac conditions. The sample consisted of 157 patients: 35 patients treated with antiarrhythmic medication only, 24 patients treated with ICD only, 25 patients treated with ICD and antiarrhythmic medication, and 73 controls. Patients completed the Medical Outcomes Study SF-36 health survey, the Brief Symptom Inventory, and background questionnaires. There were no significant differences in self-reported QOL and psychological distress between patients with or without ICD, and the occurrence of defibrillator shocks was unrelated to QOL and psychological distress. However, patients treated with antiarrhythmic drugs reported greater QOL impairment in physical functioning, vitality, emotional role limitations, and sleep, as well as greater psychological distress than patients not treated with antiarrhythmics. These limitations may be attributed to adverse effects arising from antiarrhythmic pharmacotherapy. Results of the present investigation suggest that QOL and psychological distress are maintained among ICD patients, whereas treatment with antiarrhythmic drugs are associated with a diminished QOL and greater psychological distress. These findings may assist cardiologists to select the optimal treatment for life-threatening ventricular arrhythmias that minimizes disturbances in health-related QOL and psychological distress and increases patient compliance.
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Desfibriladores Implantables/psicología , Calidad de Vida , Rol del Enfermo , Taquicardia Ventricular/psicología , Actividades Cotidianas/psicología , Adaptación Psicológica , Anciano , Anciano de 80 o más Años , Antiarrítmicos/administración & dosificación , Terapia Combinada , Femenino , Humanos , Masculino , Persona de Mediana Edad , Inventario de Personalidad , Perfil de Impacto de Enfermedad , Taquicardia Ventricular/terapia , Resultado del TratamientoRESUMEN
The renal accumulation of alpha2u-globulin has been implicated in the tumorigenicity of many nongenotoxic chemicals to the kidney of the male rat. Several chemicals inducing renal tumors in the male rat were shown to bind to alpha2u-globulin. This binding impairs the renal degradation of alpha2u-globulin, resulting in lysosomal overload, cell death, increased cell proliferation, and, presumably, renal tumor formation. To support the role of alpha2u-globulin accumulation in the renal toxicity of a chemical, a demonstration of the accumulation of this protein in the kidney of the male rat is one prerequisite. Monoclonal antibodies to alpha2u-globulin are available for quantifying alpha2u-globulin content; however, the procedure is time-consuming and complicated. We developed a method for the quantitation of alpha2u-globulin in renal cytosol using capillary electrophoresis. Renal cytosol fractions were analyzed by capillary electrophoresis as protein-SDS complexes. Using alpha2u-globulin purified from urine of male rats, the limit of detection was 10 microg/ml sample in routine analyses. Excellent run to run reproducibility in migration time (CV = 4%) and peak areas corresponding to alpha2u-globulin (CV = 3%) after normalization to the internal standard was observed. Significant increases in renal alpha2u-globulin content (up to 85% of total protein content) compared to controls (approx 15%) were observed in kidney cytosol of rats treated with alpha2u-globulin nephropathy-inducing agents such as trimethylpentane or the alkylphosphonates dimethyl methylphosphonate and diethyl ethylphosphonate, but not in kidney cytosol of male rats treated with tris-(2-chloroethyl)phosphate or the nephrotoxic agent hexachlorobutadiene. A good correlation of the alpha2u-globulin contents determined by capillary electrophoresis and immunoblotting with an alpha2u-globulin-specific antibody (r2 = 0.997) was obtained. Capillary electrophoresis provides a simple, rapid, and highly reproducible quantitation of alpha2u-globulin accumulation for renal tumorigens and may assist in the risk assessment process for these chemicals.
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alfa-Globulinas/análisis , Electroforesis Capilar/métodos , Riñón/química , alfa-Globulinas/metabolismo , Animales , Western Blotting , Citosol/química , Femenino , Riñón/efectos de los fármacos , Riñón/metabolismo , Enfermedades Renales/inducido químicamente , Enfermedades Renales/metabolismo , Masculino , Octanos/toxicidad , Compuestos Organofosforados/toxicidad , Ratas , Ratas Endogámicas F344RESUMEN
In fat and muscle cells insulin causes the marked translocation of the glucose transporter GLUT4 from its intracellular location to the plasma membrane. We and others have discovered an insulin-regulated membrane aminopeptidase (designated IRAP) that colocalizes with intracellular GLUT4 and also translocates markedly in response to insulin. This study describes the trafficking kinetics of IRAP in 3T3-L1 adipocytes. By means of a surface biotinylation method, the half-time for the increase in IRAP at the plasma membrane in response to insulin was found to be 2 min. The increase was completely blocked by the phosphatidylinositol 3-kinase inhibitor, wortmannin. In insulin-treated cells, biotinylated IRAP, initially at the plasma membrane, equilibrated with the intracellular pool with a half-time of 2 min. Thus, IRAP continuously recycles. Finally, vesicles isolated from the intracellular membranes with antibodies against IRAP and GLUT4 showed the same protein composition. In conjunction with results in the literature, these findings indicate that IRAP and GLUT4 traffic through the same intracellular compartments.
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Adipocitos/enzimología , Aminopeptidasas/metabolismo , Proteínas Musculares , Células 3T3 , Androstadienos/farmacología , Animales , Transporte Biológico , Biotinilación , Membrana Celular , Cistinil Aminopeptidasa , Inhibidores Enzimáticos/farmacología , Transportador de Glucosa de Tipo 4 , Insulina/metabolismo , Antagonistas de Insulina/farmacología , Cinética , Ratones , Peso Molecular , Proteínas de Transporte de Monosacáridos/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Propiedades de Superficie , WortmaninaRESUMEN
The orientation of the central proton-binding site, the protonated Schiff base, away from the proton release side to the proton uptake side is crucial for the directionality of the proton pump bacteriorhodopsin. It has been proposed that this movement, called the reprotonation switch, takes place in the M1 to M2 transition. To resolve the molecular events in this M1 to M2 transition, we performed double-flash experiments. In these experiments a first pulse initiates the photocycle and a second pulse selectively drives bR molecules in the M intermediate back into the BR ground state. For short delay times between initiating and resetting pulses, most of the M molecules being reset are in the M1 intermediate, and for longer delay times most of the reset M molecules are in the M2 intermediate. The BR-M1 and BR-M2 difference spectra are monitored with nanosecond step-scan Fourier transform infrared spectroscopy. Because the Schiff base reprotonation rate is kM1 = 0.8 x 10(7) s(-1) in the light-induced M1 back-reaction and kM2 = 0.36 x 10(7) s(-1) in the M2 back-reaction, the two different M intermediates represent two different proton accessibility configurations of the Schiff base. The results show only a minute movement of one or two peptide bonds in the M1 to M2 transition that changes the interaction of the Schiff base with Y185. This backbone movement is distinct from the larger one in the subsequent M to N transition. No evidence of a chromophore isomerization is seen in the M1 to M2 transition. Furthermore, the results show time-resolved reprotonation of the Schiff base from D85 in the M photo-back-reaction, instead of from D96, as in the conventional cycle.