Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 52
Filtrar
Más filtros

Banco de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Indoor Air ; 27(2): 478-486, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27317363

RESUMEN

Alaska Native children experience high rates of respiratory infections and conditions. Household crowding, indoor smoke, lack of piped water, and poverty have been associated with respiratory infections. We describe the baseline household characteristics of children with severe or chronic lung disease participating in a 2012-2015 indoor air study. We monitored indoor PM2.5, CO2 , relative humidity %, temperature, and VOCs and interviewed caregivers about children's respiratory symptoms. We evaluated the association between reported children's respiratory symptoms and indoor air quality indicators using multiple logistic regression analysis. Compared with general US households, study households were more likely overcrowded 73% (62%-82%) vs 3.2% (3.1%-3.3%); had higher woodstove use as primary heat source 16% (9%-25%) vs 2.1% (2.0%-2.2%); and higher proportion of children in a household with a smoker 49% (38%-60%) vs 26.2% (25.5%-26.8%). Median PM2.5 was 33 µg/m3 . Median CO2 was 1401 ppm. VOCs were detectable in all homes. VOCs, smoker, primary wood heat, and PM2.5>25 µg/m3 were associated with higher risk for cough between colds; VOCs were associated with higher risk for wheeze between colds and asthma diagnosis. High indoor air pollutant levels were associated with respiratory symptoms in household children, likely related to overcrowding, poor ventilation, woodstove use, and tobacco smoke.


Asunto(s)
Contaminación del Aire Interior/análisis , Exposición a Riesgos Ambientales/análisis , Vivienda/estadística & datos numéricos , Enfermedades Pulmonares/epidemiología , Contaminación del Aire Interior/efectos adversos , Alaska/epidemiología , Niño , Preescolar , Enfermedad Crónica , Culinaria/métodos , Exposición a Riesgos Ambientales/efectos adversos , Monitoreo del Ambiente , Femenino , Calefacción/métodos , Humanos , Lactante , Modelos Logísticos , Enfermedades Pulmonares/etiología , Masculino
2.
Health Promot J Austr ; 28(2): 132-138, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-27545287

RESUMEN

Issue addressed Aboriginal youth in Australia often experience high rates of intimate partner violence (family violence) and poorer reproductive and sexual health than their non-Aboriginal counterparts. To address some of the disparities, the Strong Family Program was developed to deliver reproductive and sexual health education to Aboriginal communities in New South Wales. Methods Development of the program was based on an extensive consultation process with Aboriginal communities. It was implemented in three communities, with two groups from each hosting Aboriginal youth and Elders in a yarning circle within the culturally respectful frameworks of 'men and boys'' and 'women and girls'' business. An evaluation was conducted to measure reproductive and sexual health knowledge and attitude changes upon program completion, using pre- and post-program surveys and yarning (focus group discussions). Results Program participants comprised 48 females and 28 males. Overall, mean knowledge and attitude scores improved upon completion of the program (from 77% to 82% and from 4.15 to 4.32 out of 5, respectively). Among participants aged 20 years and under (the youngest participant was 13 years), there was an increase in knowledge (P=0.034); among participants aged over 20 years (the oldest participant was 78 years), there was an increase in positive attitudes (P=0.001). Participants perceived the information provided to be useful and relevant, with many reporting improved knowledge and attitudes around rights and respectful relationships. Conclusions Reproductive and sexual health education in Aboriginal communities should be based on community consultations and carried out within a culturally appropriate framework to promote greater success. Continued implementation of the Strong Family Program will promote increased understanding of respectful relationships and improved health outcomes for Aboriginal young people. So what? The Strong Family Program was based on an extensive consultative process that ensured leadership and involvement from Aboriginal communities, with program content and delivery based on Aboriginal pedagogy and reflecting Aboriginal cultural values. Reproductive and sexual health promotion in Aboriginal communities should be based on community consultations and carried out within a culturally appropriate framework to promote greatest success.


Asunto(s)
Promoción de la Salud , Nativos de Hawái y Otras Islas del Pacífico , Salud Sexual , Adolescente , Adulto , Australia , Femenino , Humanos , Masculino , Nueva Gales del Sur , Adulto Joven
3.
Osteoarthritis Cartilage ; 24(3): 521-33, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26493330

RESUMEN

OBJECTIVE: Allogeneic cell therapies, such as mesenchymal stromal cells (MSC), which have potent regenerative and anti-inflammatory potential are being investigated as a therapy for osteoarthritis (OA) and cartilage injury. Here we describe another potential source of regenerative and anti-inflammatory allogeneic cells, culture expanded primary chondrocytes (CEPC). In direct comparison to allogeneic MSC, we extensively assess the immunological interactions of CEPC in an allogeneic setting. METHODS: Chondrocytes were isolated from rat articular cartilage and cultured in normoxic or hypoxic conditions. In vitro co-culture assays with allogeneic lymphocytes and macrophages were used to assess the immunomodulatory capacities of the chondrocytes, followed by immune response analysis by flow cytometry, ELISA and qPCR. RESULTS: CEPC showed reduced induction of proliferation, activation and cytotoxic granzyme B expression in allogeneic T cells. Importantly, exposure to pro-inflammatory cytokines did not increase CEPC immunogenicity despite increases in MHC-I. Furthermore, CEPC had a potent ability to suppress allogeneic T cell proliferation, which was dependent on nitric oxide production. This suppression was contact independent in hypoxia cultured CEPC. Finally, chondrocytes were shown to have the capacity to modulate pro-inflammatory macrophage activity by reducing MHC-II expression and TNF-α secretion. CONCLUSION: These data indicate the potential use of allogeneic chondrocytes in OA and cartilage defects. The lack of evident immunogenicity, despite exposure to a pro-inflammatory environment, coupled with the immunomodulatory ability indicates that these cells have the potential to evade the host immune system and suppress inflammation, thus potentially facilitating the resolution of OA induced inflammation and cartilage regeneration.


Asunto(s)
Cartílago Articular/citología , Condrocitos/inmunología , Tolerancia Inmunológica/inmunología , Animales , Cartílago Articular/inmunología , Hipoxia de la Célula/inmunología , Proliferación Celular , Células Cultivadas , Condrocitos/trasplante , Técnicas de Cocultivo , Citocinas/inmunología , Citotoxicidad Inmunológica/inmunología , Inmunofenotipificación , Mediadores de Inflamación/inmunología , Activación de Linfocitos/inmunología , Macrófagos/inmunología , Osteoartritis/terapia , Ratas Endogámicas Lew , Linfocitos T/inmunología
4.
J Water Health ; 14(1): 132-41, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26837837

RESUMEN

Approximately 20% of rural Alaskan homes lack in-home piped water; residents haul water to their homes. The limited quantity of water impacts the ability to meet basic hygiene needs. We assessed rates of infections impacted by water quality (waterborne, e.g. gastrointestinal infections) and quantity (water-washed, e.g. skin and respiratory infections) in communities transitioning to in-home piped water. Residents of four communities consented to a review of medical records 3 years before and after their community received piped water. We selected health encounters with ICD-9CM codes for respiratory, skin and gastrointestinal infections. We calculated annual illness episodes for each infection category after adjusting for age. We obtained 5,477 person-years of observation from 1032 individuals. There were 9,840 illness episodes with at least one ICD-9CM code of interest; 8,155 (83%) respiratory, 1,666 (17%) skin, 241 (2%) gastrointestinal. Water use increased from an average 1.5 gallons/capita/day (g/c/d) to 25.7 g/c/d. There were significant (P-value < 0.05) declines in respiratory (16, 95% confidence interval (CI): 11-21%), skin (20, 95%CI: 10-30%), and gastrointestinal infections (38, 95%CI: 13-55%). We demonstrated significant declines in respiratory, skin and gastrointestinal infections among individuals who received in-home piped water. This study reinforces the importance of adequate quantities of water for health.


Asunto(s)
Enfermedades Gastrointestinales/epidemiología , Higiene/educación , Infecciones del Sistema Respiratorio/epidemiología , Enfermedades de la Piel/epidemiología , Abastecimiento de Agua , Enfermedad Aguda/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Alaska/epidemiología , Niño , Preescolar , Enfermedades Gastrointestinales/etiología , Humanos , Lactante , Recién Nacido , Persona de Mediana Edad , Estudios Prospectivos , Infecciones del Sistema Respiratorio/etiología , Población Rural , Enfermedades de la Piel/etiología , Adulto Joven
5.
Am J Transplant ; 14(9): 2023-36, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25307035

RESUMEN

Mesenchymal stem cells (MSCs) are being investigated extensively due to their ability to dampen immune responses. Here, we tested the ability of MSCs from three distinct sources to prolong rat corneal allograft survival. A fully allogeneic rat cornea transplant model (DA to LEW) was used. Recipient rats received 1 × 10(6) MSCs (syn [LEW], allo [DA] or third-party [Wistar Furth]) intravenously 7 days before transplantation and again on the day of transplantation (day 0). A high percentage of untreated and syn-MSC treated allografts were rejected (80% and 100%, respectively). Preactivation of syn-MSCs with interferon gamma also failed to prolong allograft survival. Conversely, corneal allograft survival was significantly prolonged in allo-MSC treated (90%) and third-party MSC treated (80%) allograft recipients. Flow cytometric analysis revealed less infiltrating natural killer T cells in corneas of both allo- and third-party MSC treated animals, coupled with a higher proportion of splenic CD4+Foxp3+ regulatory T cells, compared to controls. In the case of allo- and third-party MSCs, results from a delayed-type hypersensitivity assay clearly showed that hypo-responsiveness was specific for corneal donor-associated allo-antigens. Thus, allo- and third-party MSC treatment prolongs corneal allograft survival by suppressing peripheral immune responses and promoting an intragraft immunoregulatory milieu.


Asunto(s)
Adyuvantes Inmunológicos/administración & dosificación , Enfermedades de la Córnea/cirugía , Trasplante de Células Madre Mesenquimatosas , Animales , Secuencia de Bases , Cartilla de ADN , Ratas , Reacción en Cadena en Tiempo Real de la Polimerasa , Trasplante Homólogo
6.
Am J Transplant ; 12(5): 1313-22, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22300371

RESUMEN

To investigate the role of lentivirus-mediated overexpression of programmed death-ligand 1 (PD-L1) on rat corneal allograft survival. A fully allogeneic rat cornea transplant model was used for in vivo studies. Lentiviral (LV) vectors are efficient tools for ex vivo genetic modification of cultured corneas. LV vector encoding for PD-L1 (LV.PD-L1) and LV vector encoding for eGFP (LV.eGFP, as control) were constructed and tested. PD-L1 or eGFP expression was increased on corneal cells upon LV.PD-L1 and LV.eGFP transduction, respectively. Both allogeneic controls and allogeneic LV.eGFP transduced corneas were uniformly rejected (MST: 13.8 ± 1.7 days and 12.3 ± 1.9 days, respectively). In contrast, allogeneic LV.PD-L1 transduced corneas showed a high percentage (83%) of graft survival (MST > 30 days, n = 5, 15 days, n = 1). Graft opacity of PD-L1 transduced corneas was present but was significantly reduced compared to control or eGFP expressing corneas. Flow cytometric analysis revealed that percentages of CD3(+) CD8(+) CD161(+) and CD3(+) CD8(+) CD161(-) lymphocytes were decreased in animals receiving LV.PD-L1 transduced corneas compared to animals grafted with LV.eGFP transduced corneas. Moreover, reduced expression of proinflammatory cytokines (IFN-γ and IL-6) in PD-L1 transduced corneas compared to allogeneic controls was also observed. Local PD-L1 gene transfer in cultured corneas is a promising approach for the prolongation of corneal allograft survival and attenuation of graft rejection.


Asunto(s)
Antígeno B7-H1/genética , Córnea/metabolismo , Trasplante de Córnea , Terapia Genética , Rechazo de Injerto/prevención & control , Supervivencia de Injerto , Lentivirus/genética , Animales , Antígeno B7-H1/inmunología , Citocinas/metabolismo , Técnicas de Transferencia de Gen , Vectores Genéticos , Masculino , Ratas , Ratas Endogámicas Lew , Trasplante Homólogo
7.
J Clin Invest ; 104(11): 1631-9, 1999 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-10587527

RESUMEN

We examined the effects of upregulation of heme oxygenase-1 (HO-1) in steatotic rat liver models of ex vivo cold ischemia/reperfusion (I/R) injury. In the model of ischemia/isolated perfusion, treatment of genetically obese Zucker rats with the HO-1 inducer cobalt protoporphyrin (CoPP) or with adenoviral HO-1 (Ad-HO-1) significantly improved portal venous blood flow, increased bile production, and decreased hepatocyte injury. Unlike in untreated rats or those pretreated with the HO-1 inhibitor zinc protoporphyrin (ZnPP), upregulation of HO-1 by Western blots correlated with amelioration of histologic features of I/R injury. Adjunctive infusion of ZnPP abrogated the beneficial effects of Ad-HO-1 gene transfer, documenting the direct involvement of HO-1 in protection against I/R injury. Following cold ischemia/isotransplantation, HO-1 overexpression extended animal survival from 40% in untreated controls to about 80% after CoPP or Ad-HO-1 therapy. This effect correlated with preserved hepatic architecture, improved liver function, and depressed infiltration by T cells and macrophages. Hence, CoPP- or gene therapy-induced HO-1 prevented I/R injury in steatotic rat livers. These findings provide the rationale for refined new treatments that should increase the supply of usable donor livers and ultimately improve the overall success of liver transplantation.


Asunto(s)
Hemo Oxigenasa (Desciclizante)/biosíntesis , Isquemia/patología , Trasplante de Hígado/patología , Hígado/patología , Obesidad/genética , Daño por Reperfusión/patología , Adenoviridae/genética , Animales , Aspartato Aminotransferasas/metabolismo , Terapia Genética , Hemo Oxigenasa (Desciclizante)/genética , Hemo-Oxigenasa 1 , Inmunohistoquímica , Hígado/efectos de los fármacos , Masculino , Protoporfirinas , Ratas , Ratas Zucker , Regulación hacia Arriba/efectos de los fármacos
8.
Med Phys ; 43(8): 4789, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27487896

RESUMEN

PURPOSE: To develop a comprehensive peripheral dose (PD) dataset for the two unflattened beams of nominal energy 6 and 10 MV for use in clinical care. METHODS: Measurements were made in a 40 × 120 × 20 cm(3) (width × length × depth) stack of solid water using an ionization chamber at varying depths (dmax, 5, and 10 cm), field sizes (3 × 3 to 30 × 30 cm(2)), and distances from the field edge (5-40 cm). The effects of the multileaf collimator (MLC) and collimator rotation were also evaluated for a 10 × 10 cm(2) field. Using the same phantom geometry, the accuracy of the analytic anisotropic algorithm (AAA) and Acuros dose calculation algorithm was assessed and compared to the measured values. RESULTS: The PDs for both the 6 flattening filter free (FFF) and 10 FFF photon beams were found to decrease with increasing distance from the radiation field edge and the decreasing field size. The measured PD was observed to be higher for the 6 FFF than for the 10 FFF for all field sizes and depths. The impact of collimator rotation was not found to be clinically significant when used in conjunction with MLCs. AAA and Acuros algorithms both underestimated the PD with average errors of -13.6% and -7.8%, respectively, for all field sizes and depths at distances of 5 and 10 cm from the field edge, but the average error was found to increase to nearly -69% at greater distances. CONCLUSIONS: Given the known inaccuracies of peripheral dose calculations, this comprehensive dataset can be used to estimate the out-of-field dose to regions of interest such as organs at risk, electronic implantable devices, and a fetus. While the impact of collimator rotation was not found to significantly decrease PD when used in conjunction with MLCs, results are expected to be machine model and beam energy dependent. It is not recommended to use a treatment planning system to estimate PD due to the underestimation of the out-of-field dose and the inability to calculate dose at extended distances due to the limits of the dose calculation matrix.


Asunto(s)
Fotones/uso terapéutico , Dosis de Radiación , Planificación de la Radioterapia Asistida por Computador/métodos , Algoritmos , Humanos , Dosificación Radioterapéutica
9.
Curr Gene Ther ; 5(1): 101-9, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15638714

RESUMEN

Introduction of gene therapy into molecular medicine has been gaining increasing interest. Although treatment of various diseases e.g. monogenetic defects or cancer by using gene transfer technologies has been extensively probed, the clinical success has been limited. However, recent experimental data suggest that gene therapy may represent an attractive and powerful approach in preventing ischemia/reperfusion injury as well as organ rejection in transplant recipients. Easy and selective access to the donor organ facilitates the reduction of potentially harmful systemic side effects of gene therapy vectors. By introducing anti-apoptotic or cytoprotective genes, these studies focused on the protection of the transplant from the apoptotic cell death. In addition, down-regulation of adhesion molecules and/or blockade of gene expression in the graft itself also ameliorated ischemia/reperfusion injury. This review summarizes the current progress on gene therapy application in combating ischemia-reperfusion injury in organ transplantation. Although the use of viral vectors is emphasized, non-viral gene transfer techniques are also discussed. Future development of novel, low-immunogenic vectors should further contribute to the minimization of ischemia/reperfusion injury, and thus to the overall success of organ transplantation.


Asunto(s)
Terapia Genética , Daño por Reperfusión/prevención & control , Adenoviridae/genética , Animales , Citocinas/genética , Vectores Genéticos , Humanos , Trasplante de Órganos
10.
Hum Gene Ther ; 11(9): 1303-11, 2000 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-10890740

RESUMEN

T lymphocytes, regardless of their specificity, are considered key targets for genetic modification in the treatment of inherited or acquired human diseases. In this study, we generated Lewis T cell lines specific for Dark Agouti rat alloantigens and tested the potential of allospecific T lymphocytes as carriers of genes encoding therapeutic proteins in transplantation gene therapy. These allospecific T lymphocytes were successfully, stably transduced with enhanced green fluorescent protein (EGFP) by an Mo-MuLV-based retrovirus vector. A novel gene delivery protocol was utilized, resulting in nearly 100% EGFP-expressing T cells. This approach enabled tracking of allospecific transduced T cells in vivo and illustrates their transgene production by fluorometric determination after ex vivo isolation. Quantitation of EGFP transgene expression was used to determine the influence of T cell receptor-specific activation on transgene regulation. A strict positive correlation between activation state and expression level was detected in vitro and in vivo. The activation-induced increase in transgene expression could be blocked by interference with T cell activation signaling pathways by cyclosporin A, anti-CD4 MAb, or CTLA4-Ig. These data provide strong evidence that direct or indirect effects caused by activation-induced transcription factors are crucial in transgene upregulation. Allospecific activation in spleens, lymph nodes, and transplanted grafts can be considered as antigen-specific targeting strategy. This activation might be useful in expressing therapeutic proteins such as TGF-beta or IL-10 specific to these sites. T lymphocyte priming and activation might be prevented or altered by modification of the local microenvironments, thereby exerting a therapeutic influence on acute and chronic graft rejection processes.


Asunto(s)
Trasplante de Células , Inmunoconjugados , Isoantígenos/inmunología , Linfocitos T/inmunología , Linfocitos T/trasplante , Abatacept , Traslado Adoptivo , Animales , Anticuerpos/farmacología , Antígenos CD , Antígenos de Diferenciación/inmunología , Antígenos CD4/inmunología , Antígeno CTLA-4 , Células Clonales/inmunología , Ciclosporina/farmacología , Expresión Génica/efectos de los fármacos , Terapia Genética , Vectores Genéticos/genética , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/genética , Ganglios Linfáticos/metabolismo , Activación de Linfocitos/efectos de los fármacos , Virus de la Leucemia Murina de Moloney/genética , Ratas , Bazo/metabolismo , Linfocitos T/efectos de los fármacos , Transducción Genética
11.
Transplantation ; 70(1): 191-8, 2000 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-10919599

RESUMEN

BACKGROUND: E1-deleted adenoviral vectors are frequently used for in vivo gene therapy. However, gene expression after adenovirus-(ad) mediated gene transfer is known to be transient due to the generation of an immune response against virus-infected cells. In this study, we asked whether an anti-CD4 mAb (RIB 5/2) treatment may improve the gene transfer into rat cardiac grafts. METHODS: We injected recombinant ad-constructs encoding for Escherichia coli beta-gal into syngeneic rat heart transplants via the proximal aorta. One-half of the recipients of genetically modified grafts received the anti-CD4 mAb RIB 5/2, whereas the other half received no monoclonal antibody treatment. Genetically unmodified isografts without any treatment of the recipients were used as additional controls. At different time points hearts were harvested and analyzed for reporter gene expression, intragraft cellular infiltration, and cytokine gene expression (quantitative "real time" reverse transcriptase polymerase chain reaction). Serum samples were analyzed for anti-ad-Ig using enzyme-linked-immunosorbent-assay. RESULTS: In control animals the beta-gal reporter gene expression slowly increased until day 7 and then declined. The immunohistological and reverse transcriptase polymerase chain reaction intragraft analyses revealed a strong inflammatory response (cellular infiltration, cytokine expression) in ad-transfected grafts that may explain the delayed expression and fast down-regulation of the transgene. Treatment with RIB 5/2 mAb resulted in a faster and prolonged reporter gene expression, reduced graft infiltration, reduced anti-ad-Ig titers and less interferon-gamma up-regulation. CONCLUSIONS: Our results indicate that modulation of the anti-ad immune response using a nondepleting anti-CD4 mAb may increase the efficiency of ad-vectors for gene therapy in the transplant setting.


Asunto(s)
Adenoviridae/genética , Adenoviridae/inmunología , Anticuerpos Monoclonales/uso terapéutico , Antígenos CD4/inmunología , Técnicas de Transferencia de Gen , Trasplante de Corazón , Animales , Anticuerpos Antivirales/sangre , Interferón gamma/genética , Masculino , Ratones , ARN Mensajero/análisis , Ratas , Ratas Endogámicas Lew , Transgenes
12.
Transplantation ; 68(9): 1427-31, 1999 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-10573088

RESUMEN

BACKGROUND: Recently we have demonstrated that the nondepleting anti-CD4 monoclonal antibody (mAb) RIB5/2 induces long-term acceptance of kidney and heart allografts in all rat strain combinations tested. Cytokine gene expression studies by reverse transcriptase-polymerase chain reaction revealed a reversed intragraft interleukin (IL)-4/interferon-gamma ratio. Whether IL-4 mediated immune deviation contributes to transplantation tolerance is not clear so far. METHODS: To learn more about the functional relevance of the relative IL-4 up-regulation, IL-4 was overexpressed in rat heart allografts by using ex vivo adenoviral gene transfer. The efficiency of gene transfer was analyzed by reporter gene assays as well by reverse transcriptase-polymerase chain reaction analysis of IL-4 mRNA expression. RESULTS: The intragraft overexpression of IL-4 did not prolong the allograft survival compared with controls. Moreover, neutralization of IL-4 by OX81 mAb did not prevent tolerance induction by RIB5/2 treatment. CONCLUSIONS: Anti-CD4 mAb-induced tolerance is associated with an intragraft type1/type2 shift, however, the up-regulation of IL-4 alone is neither sufficient nor essential to induce tolerance to cardiac allografts in a high-responder strain combination.


Asunto(s)
Trasplante de Corazón/inmunología , Tolerancia Inmunológica , Interleucina-4/fisiología , Animales , Anticuerpos Monoclonales/uso terapéutico , Técnicas de Transferencia de Gen , Supervivencia de Injerto , Interleucina-4/genética , Interleucina-4/inmunología , Ratas , Ratas Endogámicas Lew , Trasplante Homólogo
13.
Transplantation ; 68(2): 288-93, 1999 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-10440403

RESUMEN

BACKGROUND: CD4-targeted therapy or blocking of CD28-B7 T-cell costimulation may produce indefinite cardiac allograft survival in presensitized rats. This study analyzes the immune events associated with tolerance pathways after the blockade of activation signal 1 (CD4 monoclonal antibody [mAb]) or signal 2 (CTLA4Ig). METHODS AND RESULTS: Lewis rats sensitized with Brown Norway skin grafts reject LBNF1 cardiac allografts in <36 hr. Animals were treated with RIB-5/2, a nondepleting CD4 mAb, or with CTLA4Ig + LBNF1 spleen cells. RIB-5/2 monotherapy uniformly produced permanent cardiac graft acceptance, whereas CTLA4Ig produced indefinite graft survival in about 50% of sensitized rats. Spleen cells (100 x 10(6)) from CD4 mAb-treated rats conferred donor-specific tolerance after transfer into new sets of recipients. This tolerant state could be then transferred with regulatory cells in an infectious manner into new cohorts of engrafted rats. In contrast, features of infectious tolerance could be detected in CTLA4Ig-treated hosts after infusion of >300 x 10(6) of splenocytes. CD4 mAb therapy abolished the transcription of both T helper (Th)1 and Th2 cytokines compared with rejecting controls. In contrast, CTLA4Ig treatment resulted in a selective sparing of Th2-type cytokines. Surviving grafts in both groups were largely protected from signs of chronic rejection. CONCLUSIONS: CD4 mAb-induced blockage of activation signal 1 or CTLA4Ig-mediated blockage of costimulatory signal 2 may induce a true transplantation tolerance in sensitized rats, as documented by permanent graft acceptance and attenuation of chronic injury. The infectious pathway operates in a cell dose-dependent manner. Th2-type deviation in the graft itself is not required for tolerance maintenance, and it does not necessarily lead to chronic injury.


Asunto(s)
Antígenos CD4/inmunología , Trasplante de Corazón/inmunología , Inmunoconjugados , Abatacept , Animales , Anticuerpos Bloqueadores/fisiología , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/uso terapéutico , Antígenos CD , Antígenos de Diferenciación/fisiología , Antígenos de Diferenciación/uso terapéutico , Arteriosclerosis/prevención & control , Antígeno CTLA-4 , Citocinas/fisiología , Relación Dosis-Respuesta Inmunológica , Supervivencia de Injerto/inmunología , Tolerancia Inmunológica/efectos de los fármacos , Tolerancia Inmunológica/inmunología , Tolerancia Inmunológica/fisiología , Inmunosupresores/farmacología , Masculino , Ratas , Ratas Endogámicas BN , Ratas Endogámicas Lew , Ratas Endogámicas WF , Células Th2/fisiología , Trasplante Homólogo/inmunología
14.
Artículo en Inglés | MEDLINE | ID: mdl-11367809

RESUMEN

The acoustic properties of passive materials for ultrasonic transducers have been measured at room temperature in the frequency range from 25 to 65 MHz using ultrasonic spectroscopy. These materials include alumina/EPO-TEK 301 composites and tungsten/EPO-TEK 301 composites. Experimental results showed that the acoustic impedance of the composites monotonically increased with the volume fraction of the particle filler, which is in agreement with the Denavey model. The attenuation, however, peaked between 7 and 9% volume fraction of particle filler. For comparison, several other passive materials were also fabricated and measured. The results suggest that materials that possess a higher attenuation also appear to have a larger velocity dispersion.


Asunto(s)
Ultrasonografía/instrumentación , Óxido de Aluminio/química , Compuestos Epoxi/química , Lentes , Transductores , Tungsteno/química , Ultrasonografía/métodos
15.
Artículo en Inglés | MEDLINE | ID: mdl-11370362

RESUMEN

Miniature lead titanate (PT) hollow spheres with diameters in the 1 to 10 mm range and wall thicknesses of 20 to 120 microns have been fabricated. Shell sections were used as components of pre-focused transducers. Spheres are produced using a new sacrificial core technique that produces hundreds of spheres with a more uniform wall thickness than those produced by earlier methods. Shells produced from these spheres were found to have a wall thickness variation of about 10%. Despite this variation, bulk properties were estimated from capacitance and impedance data. Shells tested in this work had dielectric constants (1 kHz) near 280 with loss factor of < 2% and d33 values of 68 pC/N. Thickness coupling coefficients averaged 0.51 with mechanical quality factors of < 15. A transducer fabricated from these sections of spheres had a round-trip insertion loss of -20.1 dB at the center frequency of 39.8 MHz and a 6 dB bandwidth of 33%.


Asunto(s)
Ultrasonografía/instrumentación , Ingeniería Biomédica , Diseño de Equipo , Humanos , Plomo , Microscopía Electrónica de Rastreo , Titanio , Transductores
16.
Artículo en Inglés | MEDLINE | ID: mdl-18238611

RESUMEN

Single crystal relaxor ferroelectrics of PZN-8%PT were investigated for potential application in ultrasound transducers. The full set of electromechanical properties was determined using combined resonance and laser interferometry techniques. Ultra-high length extensional coupling (k(33)) of 0.94 was observed, a 25% increase over Navy Type VI PZT ceramics. The thickness extensional coupling (k(t)) of 0.48 was comparable to PZT compositions, and the compliance S(33)(E) was a factor of six greater. To maximize height extensional coupling (k'(33)), while minimizing length extensional coupling k(31) in array elements, it was necessary to align the elements along the 100 crystallographic direction in the x-y plane. Mode coupling plots and test samples for array elements determined that width-to-height ratios of less than 0.5 were desired, similar to the requirement for polycrystalline PZT ceramics. Modeling of 1-3 composites and experimental results demonstrated that thickness coupling greater than 0.80 could be achieved with a 40% to 70% volume fraction of PZN-PT. Although this is a substantial increase over PZT 1-3 composites, with a thickness coupling coefficient of 0.66, it represents a smaller fraction of the length extensional coupling k(33). This reduction may be a consequence of the increased compliance of PZN-PT, which results in significant clamping by the polymer matrix. Ultrasonic transducers fabricated using PZN-8%PT 1-3 composites achieved experimental bandwidths as high as 141%. The pulse-echo responses displayed good agreement with modeled results using the Redwood equivalent circuit.

17.
Z Psychol Z Angew Psychol ; 198(4): 417-29, 1990.
Artículo en Alemán | MEDLINE | ID: mdl-1982699

RESUMEN

In psychophysiology all procedures used are accompanied with changes of general activation level (GAL) of the subjects. In our study these changes are characterized by self-assessment of the internal state and by the mean heart rate (HR) of each period. On the basis of these data group mean auditory evoked potentials (AEPs) were computed. The influence of the GAL on the N 110- and P 190-amplitudes of the AEPs was analysed. There was no effect on the P 190-amplitude whereas the N 110-amplitude shows distinct responses on changes in GAL. These amplitudes diminished when the subjects reported a change of internal state. The diminishing of N 110-amplitudes took place as well at an increase as at a decrease of the internal state factors. Comparing the HR and the N 110 of the AEPs we found an inverse U-shaped dependence. These results are discussed in comparison to the literature. Furthermore a model which could elucidate the observed findings is presented for a critical discussion.


Asunto(s)
Nivel de Alerta/fisiología , Atención/fisiología , Potenciales Evocados Auditivos/fisiología , Adulto , Corteza Cerebral/fisiología , Electroencefalografía/instrumentación , Femenino , Humanos , Masculino , Procesamiento de Señales Asistido por Computador/instrumentación
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA