Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 493
Filtrar
1.
World J Surg ; 46(3): 486-496, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-34839375

RESUMEN

BACKGROUND: Any health care system that strives to deliver good health and well-being to its population relies on a trained workforce. The aim of this study was to enumerate surgical provider density, describe operative productivity and assess the association between key surgical system characteristics and surgical provider productivity in Liberia. METHODS: A nationwide survey of operation theatre logbooks, available human resources and facility infrastructure was conducted in 2018. Surgical providers were counted, and their productivity was calculated based on operative numbers and full-time equivalent positions. RESULTS: A total of 286 surgical providers were counted, of whom 67 were accredited specialists. This translated into a national density of 1.6 specialist providers per 100,000 population. Non-specialist physicians performed 58.3 percent (3607 of 6188) of all operations. Overall, surgical providers performed a median of 1.0 (IQR 0.5-2.7) operation per week, and there were large disparities in operative productivity within the workforce. Most operations (5483 of 6188) were categorized as essential, and each surgical provider performed a median of 2.0 (IQR 1.0-5.0) different types of essential procedures. Surgical providers who performed 7-14 different types of essential procedures were more than eight times as productive as providers who performed 0-1 essential procedure (operative productivity ratio = 8.66, 95% CI 6.27-11.97, P < 0.001). CONCLUSION: The Liberian health care system struggles with an alarming combination of few surgical providers and low provider productivity. Disaggregated data can provide a high-resolution picture of local challenges that can lead to local solutions.


Asunto(s)
Eficiencia , Procedimientos Quirúrgicos Operativos , Atención a la Salud , Humanos , Liberia , Especialización , Recursos Humanos
2.
Mikrochim Acta ; 188(2): 36, 2021 01 09.
Artículo en Inglés | MEDLINE | ID: mdl-33420843

RESUMEN

An amperometric sensor based on an inkjet-printed graphene electrode (IPGE) modified with amine-functionalized montmorillonite (Mt-NH2) for the electroanalysis and quantification of gentisic acid (GA) has been developed. The organoclay used as IPGE modifier was prepared and characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy, CHN elemental analysis, and thermogravimetry. The electrochemical features of the Mt-NH2/IPGE sensor were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The sensor exhibited charge selectivity ability which was exploited for the electrochemical oxidation of GA. The GA amperometric response was high in acidic medium (Brinton-Robinson buffer, pH 2) due to favorable interactions between the protonated amine groups and the negatively charged GA. Kinetic studies were also performed by cyclic voltammetry, and the obtained electron transfer rate constant of 11.3 s-1 indicated a fast direct electron transfer rate of GA to the electrode. An approach using differential pulse voltammetry was then developed for the determination of GA (at + 0.233 V vs. a pseudo Ag/Ag+ reference electrode), and under optimized conditions, the sensor showed high sensitivity, a wide working linear range from 1 to 21 µM (R2 = 0.999), and a low detection limit of 0.33 µM (0.051 ± 0.01 mg L-1). The proposed sensor was applied to quantify GA in a commercial red wine sample. The simple and rapid method developed using a cheap clay material could be employed for the determination of various phenolic acids.


Asunto(s)
Bentonita/química , Gentisatos/análisis , Grafito/química , Técnicas Electroquímicas/métodos , Electrodos , Gentisatos/química , Límite de Detección , Oxidación-Reducción , Impresión , Vino/análisis
3.
Mol Psychiatry ; 22(8): 1134-1139, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-27843152

RESUMEN

Several common alleles in the oxytocin receptor gene (OXTR) are associated with altered brain function in reward circuitry in neurotypical adults and may increase risk for autism spectrum disorders (ASD). Yet, it is currently unknown how variation in the OXTR relates to brain functioning in individuals with ASD, and, critically, whether neural endophenotypes vary as a function of aggregate genetic risk. Here, for we believe the first time, we use a multi-locus approach to examine how genetic variation across several OXTR single-nucleotide polymorphisms (SNPs) affect functional connectivity of the brain's reward network. Using data from 41 children with ASD and 41 neurotypical children, we examined functional connectivity of the nucleus accumbens (NAcc) - a hub of the reward network - focusing on how connectivity varies with OXTR risk-allele dosage. Youth with ASD showed reduced NAcc connectivity with other areas in the reward circuit as a function of increased OXTR risk-allele dosage, as well as a positive association between risk-allele dosage and symptom severity, whereas neurotypical youth showed increased NAcc connectivity with frontal brain regions involved in mentalizing. In addition, we found that increased NAcc-frontal cortex connectivity in typically developing youth was related to better scores on a standardized measure of social functioning. Our results indicate that cumulative genetic variation on the OXTR impacts reward system connectivity in both youth with ASD and neurotypical controls. By showing differential genetic effects on neuroendophenotypes, these pathways elucidate mechanisms of vulnerability versus resilience in carriers of disease-associated risk alleles.


Asunto(s)
Trastorno del Espectro Autista/genética , Receptores de Oxitocina/genética , Adolescente , Alelos , Trastorno Autístico/genética , Encéfalo , Estudios de Casos y Controles , Niño , Femenino , Lóbulo Frontal , Dosificación de Gen/genética , Frecuencia de los Genes/genética , Variación Genética , Humanos , Masculino , Neuroimagen/métodos , Núcleo Accumbens/fisiopatología , Oxitocina/metabolismo , Polimorfismo de Nucleótido Simple/genética , Receptores de Oxitocina/metabolismo , Recompensa , Conducta Social
4.
Am J Transplant ; 17(11): 2803-2809, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-28744966

RESUMEN

As the organ shortage continues to grow, the creation of social media communities by transplant hospitals and the public is rapidly expanding to increase the number of living donors. Social media communities are arranged in myriad ways and without standardization, raising concerns about transplant candidates' and potential donors' autonomy and quality of care. Social media communities magnify and modify extant ethical issues in deceased and living donation related to privacy, confidentiality, professionalism, and informed consent, and increase the potential for undue influence and coercion for potential donors and transplant candidates. Currently, no national ethical guidelines have been developed in the United States regarding the use of social media to foster organ transplantation. We provide an ethical framework to guide transplant stakeholders in using social media for public and patient communication about transplantation and living donation, and offer recommendations for transplant clinical practice and future research.


Asunto(s)
Consentimiento Informado/ética , Donadores Vivos , Trasplante de Órganos , Educación del Paciente como Asunto , Guías de Práctica Clínica como Asunto/normas , Medios de Comunicación Sociales , Obtención de Tejidos y Órganos/ética , Humanos , Estados Unidos
5.
Am J Transplant ; 15(1): 265-73, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25425398

RESUMEN

The potential use of financial compensation to increase living kidney donation rates remains controversial in potentially introducing undue inducement of vulnerable populations to donate. This cross-sectional study assessed amounts of financial compensation that would generate motivation and an undue inducement to donate to family/friends or strangers. Individuals leaving six Departments of Motor Vehicles were surveyed. Of the 210 participants who provided verbal consent (94% participation rate), respondents' willingness to donate would not change (70%), or would increase (29%) with compensation. Median lowest amounts of financial compensation for which participants would begin to consider donating a kidney were $5000 for family/friends, and $10,000 for strangers; respondents reporting $0 for family/friends (52%) or strangers (26%) were excluded from analysis. Median lowest amounts of financial compensation for which participants could no longer decline (perceive an undue inducement) were $50,000 for family/friends, and $100,000 for strangers; respondents reporting $0 for family/friends (44%) or strangers (23%) were excluded from analysis. The two most preferred forms of compensation included: direct payment of money (61%) and paid leave (21%). The two most preferred uses of compensation included: paying off debt (38%) and paying nonmedical expenses associated with the transplant (29%). Findings suggest tolerance for, but little practical impact of, financial compensation. Certain compensation amounts could motivate the public to donate without being perceived as an undue inducement.


Asunto(s)
Compensación y Reparación , Trasplante de Riñón/economía , Donadores Vivos , Motivación , Recolección de Tejidos y Órganos/economía , Recolección de Tejidos y Órganos/psicología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Estudios Transversales , Femenino , Estudios de Seguimiento , Humanos , Donadores Vivos/psicología , Masculino , Persona de Mediana Edad , Recolección de Tejidos y Órganos/métodos , Adulto Joven
6.
Am J Transplant ; 15(5): 1180-6, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25833728

RESUMEN

New approaches to address the kidney scarcity in the United States are urgently needed. The greatest potential source of kidneys is from living donors. Proposals to offer financial incentives to increase living kidney donation rates remain highly controversial. Despite repeated calls for a pilot study to assess the impact of financial compensation on living kidney donation rates, many fear that financial incentives will exploit vulnerable individuals and cast the field of transplantation in a negative public light, ultimately reducing donation rates. This paper provides an ethical justification for conducting a pilot study of a federally regulated approach to providing financial incentives to living kidney donors, with the goal of assessing donors' perceptions.


Asunto(s)
Trasplante de Riñón/métodos , Donadores Vivos/ética , Motivación , Nefrectomía/economía , Insuficiencia Renal/cirugía , Obtención de Tejidos y Órganos/economía , Ética Médica , Humanos , Trasplante de Riñón/economía , Trasplante de Riñón/ética , Relaciones Médico-Paciente , Proyectos Piloto , Proyectos de Investigación , Recolección de Tejidos y Órganos/economía , Recolección de Tejidos y Órganos/ética , Obtención de Tejidos y Órganos/ética , Estados Unidos , Poblaciones Vulnerables
7.
Child Care Health Dev ; 41(6): 963-9, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26331351

RESUMEN

OBJECTIVE: The aim of this paper was to examine sexual knowledge, concerns and needs of youth with spina bifida (SB) to inform the medical community on ways to better support their sexual health. METHODS: As part of the Video Intervention/Prevention Assessment (VIA) - transitions, a prospective cohort study, 309 h of video data were collected from 14 participants (13-28 years old) with SB. Participants were loaned a video camcorder for 8-12 weeks to shoot visual narratives about any aspects of their lives. V/A visual narratives were analysed with grounded theory using NVivo. RESULTS: Out of 14 participants, 11 (six women) addressed issues surrounding romantic relationships and sexuality in their video clips. Analysis revealed shared concerns, questions and challenges regarding sexuality gathered under four main themes: romantic relationships, sexuality, fertility and parenthood, and need for more talk on sexuality. CONCLUSIONS: Youth with SB reported difficulties in finding answers to questions regarding their sexuality, romantic relationships and fertility. This study revealed a need for help from the medical community to inform and empower youth with SB in the area of sexual health. Through sexual and reproductive health education with patients and parents starting at an early age, medical providers can further encourage healthy emotional and physical development in adolescents transitioning into adulthood.


Asunto(s)
Sexualidad , Disrafia Espinal/fisiopatología , Disrafia Espinal/psicología , Adolescente , Adulto , Femenino , Humanos , Masculino , Estudios Prospectivos , Grabación en Video
8.
Ann Oncol ; 25(3): 700-706, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24504441

RESUMEN

BACKGROUND: In a randomized phase III study, trametinib prolonged progression-free survival and improved overall survival versus chemotherapy in patients with BRAF V600 mutation-positive melanoma. PATIENTS AND METHODS: Patients' quality of life (QOL) was assessed at baseline and follow-up visits using the European Organisation for Research and Treatment of Cancer Core QOL questionnaire. RESULTS: In the primary efficacy population (BRAF V600E+, no brain metastases) from baseline to weeks 6 and 12, patients' global health status scores worsened by 4-5 points with chemotherapy but improved by 2-3 points with trametinib. Rapid and substantive reductions in QOL functionality (e.g. role functioning, 8-11 points at weeks 6 and 12) and symptom exacerbation (e.g. fatigue, 4-8 points; nausea and vomiting, 5 points, both at weeks 6 and 12) were observed in chemotherapy-treated patients. In contrast, trametinib-treated patients reported small improvements or slight worsening from baseline at week 12, depending on the functional dimension and symptom. The mean symptom-scale scores for chemotherapy-treated patients increased from baseline (symptoms worsened) for seven of eight symptoms at week 6 (except insomnia) and six of eight symptoms at week 12 (except dyspnea and insomnia). In contrast, at weeks 6 and 12, the mean symptom-scale scores for trametinib decreased from baseline (symptoms improved) for pain (11-12 points), insomnia (10-12 points), and appetite loss (1-5 points), whereas those for diarrhea worsened (15-16 points). Mixed-model repeated-measures analyses showed significant (P < 0.05) and/or clinically meaningful improvements (small to moderate) from baseline in favor of trametinib for global health; physical, role, and social functioning; fatigue; pain; insomnia; nausea and vomiting; constipation; dyspnea; and appetite at weeks 6 and/or 12. QOL results for the intent-to-treat population were consistent. CONCLUSIONS: This first QOL assessment for a MEK inhibitor in metastatic melanoma demonstrated that trametinib was associated with less functional impairment, smaller declines in health status, and less exacerbation of symptoms versus chemotherapy.


Asunto(s)
Melanoma/tratamiento farmacológico , Melanoma/genética , Proteínas Proto-Oncogénicas B-raf/genética , Piridonas/uso terapéutico , Pirimidinonas/uso terapéutico , Antineoplásicos/efectos adversos , Antineoplásicos/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Dacarbazina/efectos adversos , Dacarbazina/uso terapéutico , Supervivencia sin Enfermedad , Estado de Salud , Humanos , Quinasas Quinasa Quinasa PAM/antagonistas & inhibidores , Melanoma/mortalidad , Persona de Mediana Edad , Mutación , Paclitaxel/efectos adversos , Paclitaxel/uso terapéutico , Inhibidores de Proteínas Quinasas/efectos adversos , Inhibidores de Proteínas Quinasas/uso terapéutico , Piridonas/efectos adversos , Pirimidinonas/efectos adversos , Calidad de Vida , Encuestas y Cuestionarios
9.
Am J Transplant ; 13(5): 1149-58, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23489435

RESUMEN

Health researchers and policy-makers increasingly urge both patient and clinician engagement in shared decision making (SDM) to promote patient-centered care. Although SDM has been examined in numerous clinical settings, it has received little attention in solid organ transplantation. This paper describes the application of SDM to the kidney transplantation context. Several distinctive features of kidney transplantation present challenges to SDM including fragmented patient-provider relationships, the time-sensitive and unpredictable nature of deceased organ offers, decision-making processes by transplant providers serving as both organ guardians (given the organ scarcity) versus advocates for specific patients seeking transplantation, variable clinical practices and policies among transplant centers, and patients' potentially compromised cognitive status and literacy levels. We describe potential barriers to and opportunities for SDM, and posit that SDM is feasible, warranting encouragement in kidney transplantation. We propose strategies to promote and overcome obstacles to SDM in kidney transplantation. We contend that engagement in SDM can be facilitated by re-organization of clinical care, communication and education of providers and patients.


Asunto(s)
Actitud del Personal de Salud , Toma de Decisiones , Trasplante de Riñón , Participación del Paciente/estadística & datos numéricos , Atención Dirigida al Paciente/métodos , Técnicas de Apoyo para la Decisión , Humanos , Relaciones Médico-Paciente
11.
Mar Pollut Bull ; 175: 113377, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-35123270

RESUMEN

Trace metals in sediments from the Chester River, a tidal tributary of the upper Chesapeake Bay with a predominantly rural, agricultural watershed, were investigated to better understand distributions and potential sources of metals. Sediments were analyzed for Al, Fe, Ni, Cr, Cu, Zn, As, Ag, Cd and organic C. Concentrations exceeded sediment toxicity guidelines in 44% of samples for Pb, and >20% for As, Ni, Cr, and Cu. Median enrichment factors (EF) for Cd, Ag, Pb, As and Zn were elevated above natural background levels. Nickel, Cu, Zn, and Cd exhibited significant differences in EF medians between the upper, middle, and lower segments of the river. Cadmium and As enrichments are presumably from application of inorganic and organic fertilizers in the watershed. Active marinas are likely an important source of metal enrichment, especially for Cu. The data underscore how land use in rural watersheds contributes to metals loading in aquatic systems.


Asunto(s)
Metales Pesados , Contaminantes Químicos del Agua , Bahías , Monitoreo del Ambiente , Sedimentos Geológicos , Metales Pesados/análisis , Ríos , Contaminantes Químicos del Agua/análisis
12.
Am J Transplant ; 11(12): 2569-74, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22051226

RESUMEN

The Organ Procurement and Transplantation Network (OPTN) mandates that organ recipients provide "specific informed consent" before accepting organs that the OPTN defines as "increased risk". However, the OPTN does not provide specific guidelines for what information should be disclosed to potential recipients. Such vagueness opens the door to inadequate informed consent. This paper examines the ethical dimensions of informed consent when the prospective living donor has self-reported behaviors associated with increased risk for infection transmission. Donor privacy is a primary ethical concern that conflicts with recipients' informed consent for use of increased risk organs. We propose that both the increased risk status and the specific behavior be disclosed to the recipient. Because the actual risk posed is linked to the type of risk behavior, disclosure is therefore needed to make an informed decision. The donor's risk behavior is material to recipients' decision making because it may impact the donor-recipient relationship. This relationship is the foundation of the donation and acceptance transaction, and thus comprises a critical feature of the recipient's informed consent. Optimizing a recipient's informed consent is essential to protecting patient safety and autonomy.


Asunto(s)
Consentimiento Informado/ética , Consentimiento Informado/psicología , Donadores Vivos/ética , Donadores Vivos/psicología , Trasplante de Órganos , Obtención de Tejidos y Órganos/ética , Toma de Decisiones , Humanos , Factores de Riesgo
13.
Curr Opin Cell Biol ; 6(5): 726-33, 1994 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-7530464

RESUMEN

Hyaluronate (HA) is an abundant component of extracellular matrix that is believed to be crucial in many cellular processes, including tissue remodeling, the creation of cell-free spaces, inflammation and tumorigenesis. Although several well characterized proteins within the extracellular matrix associate with HA, it is now clear that cells can also bind and respond to HA directly, via cell-surface HA-binding proteins. The cDNAs coding for two families of such proteins, CD44 and RHAMM, have been cloned and characterized. These proteins have been implicated in a number of physiological processes, including cell migration, lymphocyte activation and tumor progression. Although many of these processes depend on an association with HA, some are apparently HA-independent, suggesting that other ligands for these receptors may be involved.


Asunto(s)
Proteínas Portadoras/fisiología , Ácido Hialurónico/fisiología , Receptores de Superficie Celular/fisiología , Receptores Mensajeros de Linfocitos/fisiología , Animales , Proteínas Portadoras/genética , Proteínas Portadoras/inmunología , Adhesión Celular/fisiología , Movimiento Celular/fisiología , Variación Genética , Crecimiento/fisiología , Humanos , Receptores de Hialuranos , Activación de Linfocitos , Metástasis de la Neoplasia , Neoplasias/fisiopatología , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/inmunología , Receptores Mensajeros de Linfocitos/genética , Receptores Mensajeros de Linfocitos/inmunología
14.
J Exp Med ; 151(6): 1386-97, 1980 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-6155421

RESUMEN

The B10.D2 cytolytic T lymphocyte (CTL) receptor repertoire specific for the H-2Kb alloantigen has been studied by determining the reactivity patterns of monoclonal CTL against a panel of seven different H-2Kb mutants. The repertoire is extremely diverse and contains a minimum of approximately 50 different specificities against unique antigenic determinants on the H-2Kb molecule. Each specificity appears at a maximum frequency of 1 in 18,000 CTL precursors. These studies have also served to dissect the antigenic composition of the H-2Kb molecule. Very few CTL clonotypes share recognition of all the mutants, thereby indicating the lack of conservation of a b-type antigenic region. In addition, the degree to which each mutant shares antigenic determinants with the standard H-2Kb molecule has been determined.


Asunto(s)
Citotoxicidad Inmunológica , Antígenos H-2 , Receptores Inmunológicos/inmunología , Linfocitos T/inmunología , Animales , Células Clonales/inmunología , Epítopos , Antígenos H-2/genética , Ratones , Ratones Endogámicos , Mutación
15.
J Exp Med ; 155(2): 380-9, 1982 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-6173455

RESUMEN

Superimposed on the heterogeneous anti-H-2Kb cytolytic T lymphocyte (CTL) receptor repertoire of allogeneic murine strains are reactivities that recur with high frequency amongst individuals of any given strain. These receptor specificities represent phenotypic markers of the CTL repertoire and, as such, have been used to compare receptor repertoires of genetically disparate strains. The results demonstrate that congenic strains differing only in the MHC (B10.D2 and B10.BR) differ significantly in their H-2Kb-specific CTL repertoires. This finding clearly demonstrates a role for the MHC in determination of the CTL precursor repertoire. The mechanism by which MHC influences CTL specificity was explored through analysis of the anti-H-2Kb repertoire of (B10.BR X B10.D2)F1 hybrids. Because at least one recurrent parental specificity has found to be recurrent in F1 progeny as well, the findings indicate that MHC-specific tolerance cannot be solely responsible for repertiore differences between MHC-disparate strains. In addition, the F1 repertoire is characterized by the emergence of several nonparental recurrent specificities.


Asunto(s)
Epítopos , Complejo Mayor de Histocompatibilidad , Receptores de Antígenos de Linfocitos T/genética , Linfocitos T/inmunología , Animales , Cruzamientos Genéticos , Citotoxicidad Inmunológica , Femenino , Antígenos H-2/genética , Antígenos H-2/inmunología , Ratones , Ratones Endogámicos C57BL , Ratas , Ratas Endogámicas Lew , Receptores de Antígenos de Linfocitos T/inmunología
16.
J Exp Med ; 156(1): 294-9, 1982 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-6177825

RESUMEN

The specificity repertoire of H-2Kb-specific cytolytic T lymphocytes (CTL) has been examined in B10.D2,BALB/c, and the allotype congenic line CB-20. Comparing their expression of recurrent specificities that serve as markers for the repertoire of each strain indicates that the CTL repertoire of B10.D2 (Ighb) and BALB/c (Igha) differ extensively. In contrast, the repertoires expressed by B10.D2 and CB-20 (Ighb) are essentially identical with respect to their expression of the same recurrent specificities. Taken together with results previously obtained, it is concluded that both major histocompatibility complex and Igh-linked genes affect the CTL specificity repertoire.


Asunto(s)
Citotoxicidad Inmunológica , Ligamiento Genético , Cadenas Pesadas de Inmunoglobulina/genética , Receptores de Antígenos de Linfocitos T/genética , Animales , Mapeo Cromosómico , Epítopos/genética , Genes , Antígenos H-2/genética , Antígenos H-2/inmunología , Cadenas Pesadas de Inmunoglobulina/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Mutantes
17.
J Exp Med ; 145(1): 76-85, 1977 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-830791

RESUMEN

Guinea pig peritoneal macrophages were demonstrated to bind selectively soluble 125I-fibrin and fibrin/fibrinogen complexes as compared with fibrinogen, fibrinogen degradation products, and fibrin degradation products. Cellular uptake was considered to be surface receptor binding on the basis of removal of bound 125I-fibrin by trypsin and because uptake occurred in the presence of metabolic inhibitors. 125I-fibrin uptake could be blocked by nonradioactive fibrin but not by IgG or immune complexes. Binding was uneffected by prior treatment with plasmin or trypsin but was calcium dependent. Only limited reversibility of binding could be demonstrated after prolonged incubation. Scatchard plots permitted an estimate of the number of bound molecules. At saturation 6.92 X 10(6) 125I-fibrin molecules were bound per cell. Similar binding of fibrin was noted in polymorphonuclear leukocytes, but not lymphocytes or fibroblasts. Soluble fibrin binding may be a host defense mechanism whereby the reticuloendothelial system can remove fibrin from the blood before the development of microthrombi.


Asunto(s)
Productos de Degradación de Fibrina-Fibrinógeno/metabolismo , Fibrina/metabolismo , Fibrinógeno/metabolismo , Macrófagos/metabolismo , Animales , Complejo Antígeno-Anticuerpo , Líquido Ascítico/citología , Sitios de Unión , Células Sanguíneas/metabolismo , Calcio/farmacología , Cobayas , Inmunoglobulina G/metabolismo , Cinética , Magnesio/farmacología , Proteínas de la Membrana/metabolismo , Neutrófilos/metabolismo , Solubilidad
18.
J Exp Med ; 147(3): 946-51, 1978 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-305464

RESUMEN

Membrane-bound antigens responsible for induction of a secondary allogeneic murine cytolytic T-cell (CTL) response have been obtained in a soluble, biologically active form by deoxycholate solubilization of tumor cell plasma membranes. The active proteins are soluble by the criteria of both ultracentrifugation and gel filtration. The immunological specificity of the induced CTL and removal of the activity from solution by treatment with B6 anti-P815 (anti-H-2d) antiserum and Protein A-Sepharose demonstrate that the CTL-inducing activity is dependent upon solubilized major histocompatibility complex antigens.


Asunto(s)
Citotoxicidad Inmunológica , Antígenos H-2 , Proteínas de la Membrana/inmunología , Linfocitos T/inmunología , Animales , Antígenos de Neoplasias , Línea Celular , Ácido Desoxicólico , Memoria Inmunológica , Ratones , Neoplasias Experimentales/inmunología , Solubilidad
19.
J Exp Med ; 175(5): 1221-6, 1992 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-1314884

RESUMEN

One problem associated with the use of synthetic peptides as antigens in vivo is their susceptibility to inactivation by proteolytic degradation. A situation is described in which a serum protease, angiotensin-converting enzyme (ACE), is actually responsible for the class I binding activity of a commonly used influenza antigen, nucleoprotein (NP)(147-158R-). This peptide has been reported to be a highly efficient class I antigen. Evidence is presented that demonstrates that the peptide is inactive until cleaved by ACE, which is a normal constituent of serum. The enzyme removes a COOH-terminal dipeptide resulting in the sequence NP(147-155), which is identical to the naturally processed peptide. Such extracellular processing of peptides and proteins may occur for a variety of antigens both in vitro and in vivo, and could have important implications for the design of proteolytically resistant vaccines.


Asunto(s)
Antígenos/metabolismo , Antígenos de Histocompatibilidad Clase I/metabolismo , Animales , Antígenos/inmunología , Línea Celular , Cromatografía Líquida de Alta Presión , Cromatografía por Intercambio Iónico , Cinética , Ratones , Ratones Endogámicos C57BL , Nucleoproteínas/metabolismo , Péptidos/inmunología , Péptidos/metabolismo , Peptidil-Dipeptidasa A/metabolismo , Microglobulina beta-2/metabolismo
20.
J Exp Med ; 194(6): 707-17, 2001 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-11560988

RESUMEN

Not all T cells specific for autoantigens are eliminated in the thymus, and therefore alternate mechanisms are required to prevent potentially autoreactive T cells from developing into effectors. Adoptive transfer of CD8(+) T cells from influenza hemagglutinin-specific Clone 4 TCR transgenic mice into mice that express hemagluttinin in the pancreatic islets results in tolerance. This is preceded by activation of Clone 4 T cells that encounter antigen cross-presented in the draining lymph nodes of the pancreas. In this report we compare the phenotype, function, and costimulatory requirements of Clone 4 T cells activated by endogenous self-antigen, with Clone 4 T cells stimulated by influenza virus. The cells undergoing tolerance upregulate both CD69 and CD44, yet only partially downregulate CD62L, and do not express CD49d or CD25. Most importantly, they lack the ability to produce interferon-gamma in response to antigen and show no cytolytic activity. Clone 4 T cells disappear after several cycles of division, apparently without leaving the site of initial activation. Surprisingly, despite the fact that such stimulation occurs through recognition of antigen that is cross-presented by a professional antigen-presenting cell, we find this activation is not dependent on costimulation through CD28. These data demonstrate that the recognition by naive CD8(+) T cells of cross-presented self-antigen results in localized proliferation and deletion, without the production of effector cells.


Asunto(s)
Presentación de Antígeno/inmunología , Autoantígenos/inmunología , Linfocitos T CD8-positivos/inmunología , Animales , Antígenos CD/inmunología , Antígeno B7-1/inmunología , Antígeno B7-2 , Linfocitos T CD8-positivos/citología , Diferenciación Celular , División Celular , Supresión Clonal , Reacciones Cruzadas , Inmunofenotipificación , Ganglios Linfáticos/inmunología , Glicoproteínas de Membrana/inmunología , Ratones , Ratones Endogámicos BALB C , Páncreas/inmunología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA