RESUMEN

An emerging treatment modality for reducing damage caused by ischaemia-reperfusion injury is ischaemic conditioning. This technique induces short periods of ischaemia that have been found to protect against a more significant ischaemic insult. Remote ischaemic conditioning (RIC) can be administered more conveniently and safely, by inflation of a pneumatic blood pressure cuff to a suprasystolic pressure on a limb. Protection is then transferred to a remote organ via humoral and neural pathways. The diabetic state is particularly vulnerable to ischaemia-reperfusion injury, and ischaemia is a significant cause of many diabetic complications, including the diabetic foot. Despite this, studies utilising ischaemic conditioning and RIC in type 2 diabetes have often been disappointing. A newer strategy, repeat RIC, involves the repeated application of short periods of limb ischaemia over days or weeks. It has been demonstrated that this improves endothelial function, skin microcirculation, and modulates the systemic inflammatory response. Repeat RIC was recently shown to be beneficial for healing in lower extremity diabetic ulcers. This article summarises the mechanisms of RIC, and the impact that type 2 diabetes may have upon these, with the role of neural mechanisms in the context of diabetic neuropathy a focus. Repeat RIC may show more promise than RIC in type 2 diabetes, and its potential mechanisms and applications will also be explored. Considering the high costs, rates of chronicity and serious complications resulting from diabetic lower extremity ulceration, repeat RIC has the potential to be an effective novel advanced therapy for this condition.

Asunto(s)

Diabetes Mellitus Tipo 2/complicaciones , Angiopatías Diabéticas/terapia , Neuropatías Diabéticas/etiología , Precondicionamiento Isquémico/métodos , Extremidad Inferior/irrigación sanguínea , Animales , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/fisiopatología , Angiopatías Diabéticas/diagnóstico , Angiopatías Diabéticas/etiología , Angiopatías Diabéticas/fisiopatología , Neuropatías Diabéticas/diagnóstico , Neuropatías Diabéticas/fisiopatología , Humanos , Flujo Sanguíneo Regional , Factores de Riesgo , Resultado del Tratamiento , Cicatrización de Heridas

RESUMEN

BACKGROUND: Single exposure to remote ischaemic pre-conditioning (RIPC) has been shown to be effective in reducing major adverse events during cardiac surgery. We evaluated the efficacy of repeated exposure RIPC to elicit improvements in cardiovascular function. METHODS: A systematic search was conducted up until May 1st, 2015, using the following databases: EMBASE, PubMed (Medline), Web of Science and the Cochrane Central Registry of Controlled Trials (CENTRAL). Data was extracted and synthesized from published studies of repeat RIPC. RESULTS: Data from seven studies showed evidence of improvements in vascular function and anti-hypertensive effects of systolic, diastolic and mean arterial blood pressure following repeat RIPC. Currently existing work justifies a systematic review but not data pooling of individual study data. Repeat RIPC has also produced evidence of improvements in endothelial dependent vasodilation, but not non-endothelial dependent vasodilation, cutaneous vascular conductance or cardiorespiratory fitness. CONCLUSION: Repeated RIPC exposure has produced evidence of improvements in endothelial dependent vasodilation, ulcer healing and blood pressure but no benefit in non-endothelial dependent vasodilation, cutaneous vascular conductance or cardiorespiratory fitness. The optimal delivery of RIPC remains unclear, but at least 3 or preferably 4, 5 min exposures appears to be most beneficial, at least for reducing blood pressure. Aside from those undertaking cardiac surgery, other study populations with endothelial dysfunction may benefit from repeat exposure to RIPC.

RESUMEN

OBJECTIVES: The objective was to describe the early academic career activities of emergency physician (EP) scientists with recent Research Project Grant Program (R01) grant funding from the National Institutes of Health (NIH). METHODS: The curricula vitae of all EP scientists in the United States currently funded by the NIH were analyzed for evidence of advanced research training and frequency and type of publication and grant writing. Each investigator was surveyed for demographic features and estimation of protected time during their early career development. RESULTS: Eighteen investigators were identified. The median length of time from completion of residency to receipt of their first R01 grant was 11 years (interquartile range [IQR] = 11 to 15 years), and the median age of investigators at the time of this award was 43 years (IQR = 39 to 47 years). At the time of their award, researchers were publishing five peer-reviewed manuscripts a year (IQR = 1 to 8 manuscripts) and had already received considerable external funding. Ninety-four percent of those studied had pursued a research fellowship, an advanced degree, or an NIH K-award following residency. CONCLUSIONS: For EPs, receipt of an R01 from the NIH requires more than a decade of work following the completion of training. This period is characterized by pursuit of advanced research training, active and accelerating publication and collaboration, and acquisition of smaller extramural grants.

Asunto(s)

Autoria , Medicina de Emergencia/economía , National Institutes of Health (U.S.) , Apoyo a la Investigación como Asunto , Adulto , Investigación Biomédica/economía , Docentes Médicos/estadística & datos numéricos , Femenino , Humanos , Masculino , Persona de Mediana Edad , National Institutes of Health (U.S.)/economía , Estados Unidos

RESUMEN

Certain arteries (e.g., coronary, femoral, etc.) are exposed to cyclic flexure due to their tethering to surrounding tissue beds. It is believed that such stimuli result in a spatially variable biomechanical stress distribution, which has been implicated as a key modulator of remodeling associated with atherosclerotic lesion localization. In this study we utilized a combined ex vivo experimental/computational methodology to address the hypothesis that local variations in shear and mural stress associated with cyclic flexure influence the distribution of early markers of atherogenesis. Bilateral porcine femoral arteries were surgically harvested and perfused ex vivo under pulsatile arterial conditions. One of the paired vessels was exposed to cyclic flexure (0-0.7 cm(-1)) at 1 Hz for 12 h. During the last hour, the perfusate was supplemented with Evan's blue dye-labeled albumin. A custom tissue processing protocol was used to determine the spatial distribution of endothelial permeability, apoptosis, and proliferation. Finite element and computational fluid dynamics techniques were used to determine the mural and shear stress distributions, respectively, for each perfused segment. Biological data obtained experimentally and mechanical stress data estimated computationally were combined in an experiment-specific manner using multiple linear regression analyses. Arterial segments exposed to cyclic flexure had significant increases in intimal and medial apoptosis (3.42+/-1.02 fold, p=0.029) with concomitant increases in permeability (1.14+/-0.04 fold, p=0.026). Regression analyses revealed specific mural stress measures including circumferential stress at systole, and longitudinal pulse stress were quantitatively correlated with the distribution of permeability and apoptosis. The results demonstrated that local variation in mechanical stress in arterial segments subjected to cyclic flexure indeed influence the extent and spatial distribution of the early atherogenic markers. In addition, the importance of including mural stresses in the investigation of vascular mechanopathobiology was highlighted. Specific example results were used to describe a potential mechanism by which systemic risk factors can lead to a heterogeneous disease.

Asunto(s)

Albúminas/metabolismo , Apoptosis/fisiología , Endotelio Vascular/fisiología , Arteria Femoral/fisiología , Animales , Aterosclerosis , Biomarcadores , Bisbenzimidazol/metabolismo , Núcleo Celular/metabolismo , Colorantes/metabolismo , Biología Computacional/métodos , Simulación por Computador , Endotelio Vascular/citología , Azul de Evans/metabolismo , Análisis de Elementos Finitos , Técnica del Anticuerpo Fluorescente Directa , Colorantes Fluorescentes/metabolismo , Inmunohistoquímica , Etiquetado Corte-Fin in Situ , Modelos Lineales , Perfusión/métodos , Permeabilidad , Antígeno Nuclear de Célula en Proliferación/metabolismo , Flujo Pulsátil , Resistencia al Corte , Estrés Mecánico , Porcinos , Túnica Íntima/citología , Túnica Íntima/fisiología , Túnica Media/citología , Túnica Media/fisiología

RESUMEN

The biomechanical milieu of the coronary arteries is unique in that they experience mechanical deformations of twisting, bending, and stretching due to their tethering to the epicardial surface. Spatial variations in stresses caused by these deformations could account for the heterogeneity of atherosclerotic plaques within the coronary tree. The goal of this work was to utilize previously reported shear moduli to calculate a shear strain parameter for a Fung-type exponential model of the arterial wall and determine if this single constant can account for the observed behavior of arterial segments under torsion. A Fung-type exponential strain-energy function was adapted to include a torsional shear strain term. The material parameter for this term was determined from previously published data describing the relationship between shear modulus and circumferential stress and longitudinal stretch ratio. Values for the shear strain parameter were determined for three geometries representing the mean porcine left anterior descending coronary artery dimensions plus or minus one standard deviation. Finite element simulation of triaxial biomechanical testing was then used to validate the model. The mean value calculated for the shear strain parameter was 0.0759+/-0.0009 (N=3 geometries). In silico triaxial experiments demonstrated that the shear modulus is directly proportional to the applied pressure at a constant longitudinal stretch ratio and to the stretch ratio at a constant pressure. Shear moduli determined from these simulations showed excellent agreement to shear moduli reported in literature. Previously published models describing the torsional shear behavior of porcine coronary arteries require a total of six independent constants. We have reduced that description into a single parameter in a Fung-type exponential strain-energy model. This model will aid in the estimation of wall stress distributions of vascular segments undergoing torsion, as such information could provide insight into the role of mechanical stimuli in the localization of atherosclerotic plaque formation.

Asunto(s)

Presión Sanguínea/fisiología , Vasos Coronarios/fisiología , Modelos Cardiovasculares , Animales , Fuerza Compresiva/fisiología , Simulación por Computador , Módulo de Elasticidad/fisiología , Resistencia al Corte/fisiología , Porcinos , Resistencia a la Tracción/fisiología , Torsión Mecánica

RESUMEN

The maternal transcript of the anterior segmentation gene bicoid (bcd) is localized at the anterior pole of the Drosophila egg and translated to form a gradient in the nuclei of the syncytial blastoderm embryo after fertilization [1-3]. The nuclear gradient of Bcd protein - a transcription factor - leads to differential expression of zygotic segmentation genes. The rapid nuclear division during this stage [4] requires that Bcd quickly enters the nuclei after each mitosis using an active nuclear import system. Nuclear transport depends on the asymmetrical distribution of two forms of the small GTPase Ran: Ran-GTP is concentrated in the nucleus and Ran-GDP in the cytoplasm [5-8]. Ran requires RanGTPase-activating protein-1 (RanGAP1) on the cytoplasmic side of nuclear pore complexes to convert Ran-GTP to Ran-GDP. In vitro studies with vertebrate proteins demonstrate that the RanGAP1 associated with the nuclear pore complex is modified with small ubiquitin related modifier-1 (SUMO-1) by a ubiquitin-conjugating enzyme (E2 enzyme) [9-15]. Here, we show that mutation of the Drosophila semushi (semi) gene, which encodes an E2 enzyme, blocks nuclear import of Bcd during early embryogenesis and results in misregulation of the segmentation genes that are Bcd targets. Consequently, semi embryos have multiple defects in anterior segmentation. This study demonstrates that an E2 enzyme is required for nuclear transport during Drosophila embryogenesis.

Asunto(s)

Núcleo Celular/metabolismo , Drosophila/genética , Proteínas de Homeodominio/metabolismo , Ligasas/metabolismo , Mutación , Transactivadores/metabolismo , Enzimas Ubiquitina-Conjugadoras , Animales , Transporte Biológico , Drosophila/embriología , Proteínas de Drosophila , Proteínas de Insectos/metabolismo , Ligasas/genética

RESUMEN

Research using the balanced placebo design seeks to differentiate the physiological and psychological effects of drinking alcohol. Questions regarding the validity of the design center about experimenter instructions, particularly in the antiplacebo cell at higher blood alcohol content (BAC) levels. This study tested the plausibility of two misattribution strategies designed to reduce the conflict between experimenter instructions and internal cues of drunkenness. Forty-two participants (BAC = .055) were told that they received no alcohol, with internal cues of drunkenness said to be produced by a (sham) second drug, a (placebo) tachistoscopic display, or no misattribution given. The placebo drug group reported less alcohol intoxication without reporting less physical impairment than the control or tachistoscopic groups. Doubt of instructions was expressed more frequently in the control group than in the placebo drug group. Mean time to first reported doubt of experimenter instructions was longer for the placebo drug group. A manipulation check designed to account for demand effects indicated that instituting the pharmacologic misattribution increased the success of the manipulation over the control group. Providing a credible attribution for internal symptoms of drunkenness makes experimenter's instructions more credible, improving the validity of the antiplacebo cell of the balanced placebo design.

Asunto(s)

Consumo de Bebidas Alcohólicas/psicología , Intoxicación Alcohólica/psicología , Control Interno-Externo , Efecto Placebo , Disposición en Psicología , Adulto , Consumo de Bebidas Alcohólicas/sangre , Intoxicación Alcohólica/sangre , Decepción , Relación Dosis-Respuesta a Droga , Etanol/farmacocinética , Femenino , Humanos , Masculino

RESUMEN

Here we describe a new segment polarity gene of Drosophila melanogaster, oroshigane (oro). Identified as a dominant enhancer of Bar (B), oro is also recessive embryonic lethal, and homozygous oro embryos show variable substitution of naked cuticle with denticles. These patterns are distinctly similar to those of hedgehog (hh) and wingless (wg) embryos, which indicates that oro functions in determining embryonic segment polarity. Evidence that oro function is involved in Hh signal transduction during embryogenesis is provided by its genetic interactions with the segment polarity genes patched (ptc) and fused (fu). Furthermore, ptcIN is a dominant suppressor of the oro embryonic lethal phenotype, suggesting a close and dose-dependent relationship between oro and ptc in Hh signal transduction. oro function is also required in imaginal development. The oroI allele significantly reduces decapentaplegic (dpp), but not hh, expression in the eye imaginal disc. Furthermore, oro enhances the fui wing phenotype in a dominant manner. Based upon the interactions of oro with hh, ptc, and fu, we propose that the oro gene plays important roles in Hh signal transduction.

Asunto(s)

Proteínas de Drosophila , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica , Genes de Insecto , Genes Reguladores , Proteínas de Insectos/genética , Factores de Transcripción , Animales , Drosophila melanogaster/embriología , Embrión no Mamífero/ultraestructura , Desarrollo Embrionario , Epistasis Genética , Ojo/embriología , Ojo/ultraestructura , Proteínas del Ojo/biosíntesis , Proteínas del Ojo/genética , Femenino , Genes Letales , Genes Supresores , Proteínas Hedgehog , Proteínas de Homeodominio , Proteínas de Insectos/fisiología , Masculino , Proteínas de la Membrana/fisiología , Morfogénesis , Fenotipo , Proteínas Serina-Treonina Quinasas/fisiología , Receptores de Superficie Celular , Transducción de Señal/fisiología , Alas de Animales/embriología , Alas de Animales/ultraestructura

RESUMEN

The clinical outcome of patients following subarachnoid hemorrhage is complicated by delayed cerebral ischemia and contributing factors such as hypertension. To observe the impact of hypertension and delayed cerebral ischemia on the outcome of a predominantly African-American cohort following subarachnoid hemorrhage, both retrospective (n = 42) and prospective (n = 21) studies were conducted. In the total pool (n = 63), the mean age was 49.7 years (range: 17 to 80) with a preponderance of female patients (70%). Aneurysm formation was significant in the region of the posterior communicating artery. Of the patients reviewed, 73.8% had preexisting hypertension and 45.9% developed delayed cerebral ischemia. Approximately 89% of the patients who suffered from delayed cerebral ischemia had hypertension. Results failed to display any significant beneficial association between the use of the calcium channel blocker nimodipine and delayed cerebral ischemia. Use of the antifibrinolytic drug aminocaproic acid demonstrated a worse patient outcome. It is not recommended that aminocaproic acid be used in this population. Subsequently, due to the proportional occurrence of delayed cerebral ischemia in hypertensive patients following subarachnoid hemorrhage, it is suggested that prophylactic surgical management of unruptured intracranial aneurysms be considered in hypertensive patients. Further study is needed to discern the association between hypertension, delayed cerebral ischemia, and stroke in patients following subarachnoid hemorrhage.

Asunto(s)

Hemorragia Subaracnoidea/etnología , Aminocaproatos/uso terapéutico , Antifibrinolíticos/uso terapéutico , Población Negra , Isquemia Encefálica/etnología , Isquemia Encefálica/prevención & control , Bloqueadores de los Canales de Calcio/uso terapéutico , Estudios de Cohortes , Femenino , Humanos , Hipertensión/etnología , Masculino , Persona de Mediana Edad , Nimodipina/uso terapéutico , Estudios Prospectivos , Estudios Retrospectivos , Hemorragia Subaracnoidea/tratamiento farmacológico , Resultado del Tratamiento

RESUMEN

PROBLEM: There is a lack of information about the bereavement experiences of adolescents living in poverty in the inner city. SUBJECTS: Eight bereaved adolescents (mean age = 13.5 girls, 3 boys), from poverty-level families, attending an inner city junior high school. METHODS: A descriptive design, using participant-observation in a semi-structured group setting, data were gathered using audiotape recordings of the eight group discussions. FINDINGS: Chaos and stress were major themes pervading each discussion session. Lack of family and social support, fear for their future, and avoidance as the major coping strategy were also themes of the study. CONCLUSIONS: Inner city adolescents need to be assessed for loss of significant others. Provision of mental health services in schools could provide intervention services to current and future problems.

Asunto(s)

Aflicción , Muerte , Pobreza , Psicología del Adolescente , Estrés Psicológico/psicología , Salud Urbana , Adolescente , Niño , Familia , Femenino , Humanos , Masculino , Investigación Metodológica en Enfermería , Psicoterapia de Grupo , Apoyo Social

RESUMEN

We report a case of an oral intubation in a facial trauma patient that required exchanging the oral tube to a nasal endotracheal tube. This was accomplished by utilizing the fiberoptic bronchoscope to introduce a nasal tracheal tube beside the oral tube prior to removal of the oral tube from the trachea. This allowed continuation of oxygenation and ventilation until the airway was subsequently secured with the nasal tracheal tube. This approach may help avoid the loss of the airway and subsequent intervention with a surgical airway under poor conditions.

Asunto(s)

Traumatismos Faciales/cirugía , Tecnología de Fibra Óptica , Intubación Intratraqueal/métodos , Administración Intranasal , Administración Oral , Adulto , Humanos , Masculino , Factores de Tiempo

RESUMEN

Losing loved ones through death is a common experience for children. Children living in urban centers may be at greater risk for death of family members as a result of increased daily stress and poverty. Children who experience permanent loss of family members without support to grieve are at greater risk for mental health problems. Manifestations of grief that frequently occur in children are psychosomatic complaints and affective distress. This study investigates the prevalence of loss by death among two groups of inner city youths, and the impact of a bereavement group experience on subjects' affective distress and somatic complaints. A significant difference was found between pretest and post-test scores on somatic complaints for the elementary school aged group.

Asunto(s)

Aflicción , Psicología del Adolescente , Psicología Infantil , Psicoterapia de Grupo/normas , Estrés Psicológico/prevención & control , Adolescente , Niño , Femenino , Humanos , Masculino , Proyectos Piloto , Estrés Psicológico/diagnóstico

RESUMEN

Increasing concern about the safety of transfusions and a desire to balance blood supply and blood needs stimulated a regional blood center to study the utilization of blood, rather than simply looking at distribution. A comprehensive survey of transfusion use, including packed red cells (RBCs), fresh-frozen plasma (FFP), and platelets (PLTs), was conducted in 12 Central Virginia hospitals. The medical records of 2579 transfused patients showed that the principal diagnoses in 23 percent of patients involved diseases of the circulatory system and those in 16 percent involved neoplasms, as classified under the diagnosis-related groups. Sixty-six percent (n = 1691) of patients had some type of surgery, with surgical patients overall using 1.9 times as many units of blood (RBCs, FFP, and PLTs) as nonsurgical patients. Mean patient age was 61 years, and the male:female ratio was 48:52 percent. This descriptive analysis of regional blood utilization has facilitated planning for local blood needs, provided indicators for areas of largest blood use, and given this region and others baseline data for future comparison.

Asunto(s)

Transfusión Sanguínea/estadística & datos numéricos , Adolescente , Adulto , Anciano , Niño , Preescolar , Grupos Diagnósticos Relacionados , Transfusión de Eritrocitos , Femenino , Hospitales , Humanos , Lactante , Masculino , Persona de Mediana Edad , Plasma , Transfusión de Plaquetas , Procedimientos Quirúrgicos Operativos , Virginia

Asunto(s)

Exposición a Riesgos Ambientales , Eliminación de Residuos , Residuos , Humanos , Ontario

RESUMEN

The development and isotype distribution of Moloney murine leukemia virus (M-MuLV)-specific serum antibodies following primary inoculation with Moloney murine sarcoma/leukemia virus (M-MuSV/M-MuLV) in adult BALB/c mice have been investigated using an enzyme-linked immunosorbent assay (ELISA). The primary antibody responses to M-MuSV/M-MuLV consisted of the IgM, IgG2a, IgG2b, and IgG3 isotypes; no M-MuLV-specific serum IgG1 or IgA antibodies were detected. The detectable antibody response was biphasic, with an early peak of virus-specific titers seen between 10 and 15 days after inoculation and a second peak seen in regressor sera. Pooled regressor sera contained IgM, IgG2a, and IgG2b antibodies which bound to M-MuLV-expressing lymphoma cells. Immunoelectron microscopy with regressor sera showed IgG bound both to infected cell surfaces and to mature viral particles, while IgM bound only to infected cell surfaces. These findings were supported by immunoprecipitation analyses which demonstrated binding of the M-MuLV-specific antibodies to both virion-associated and cell-associated antigens encoded by the gag and env genes.

Asunto(s)

Anticuerpos Antivirales/biosíntesis , Isotipos de Inmunoglobulinas/biosíntesis , Leucemia Experimental/inmunología , Animales , Anticuerpos Antivirales/inmunología , Especificidad de Anticuerpos , Ensayo de Inmunoadsorción Enzimática , Femenino , Isotipos de Inmunoglobulinas/inmunología , Inmunohistoquímica , Técnicas de Inmunoadsorción , Linfoma/inmunología , Ratones , Ratones Endogámicos BALB C , Microscopía Electrónica , Virus de la Leucemia Murina de Moloney/inmunología , Pruebas de Precipitina , Factores de Tiempo

RESUMEN

The fate of intravascular IgA which is produced in large quantities in humans and many animal species was investigated in vivo and in vitro with emphasis on the monomeric form of IgA. The site(s) of the catabolism of intravenously injected mouse monomeric IgA labeled with a residualizing tracer (dilactitol - 125I tyramine) was studied in mice. The greatest in vivo uptake of monomeric IgA was observed in the liver. In contrast to identically labeled IgG, liver accounted for more internal catabolism of monomeric IgA than all other tissues (spleen, muscle, skin, and kidney) combined. Although both parenchymal and nonparenchymal liver cells internalized monomeric IgA, hepatocytes were far more active. The uptake of monomeric IgA was primarily mediated by the asialoglycoprotein receptor. In humans, the particulate fraction of liver homogenates and a human hepatoma cell line (Hep G2) bound human IgA proteins of various molecular forms. Inhibition of the binding by desialylated glycoproteins, requirement for the presence of calcium, and the molecular properties of the IgA-binding protein from the plasma membrane of Hep G2 cells indicated that the binding was primarily mediated by the asialoglycoprotein receptor. IgA proteins bound by Hep/G2 cells were internalized and catabolized to low molecular weight fragments.

Asunto(s)

Inmunoglobulina A/metabolismo , Hígado/inmunología , Animales , Receptor de Asialoglicoproteína , Transporte Biológico Activo , Humanos , Hígado/metabolismo , Ratones , Receptores Inmunológicos/inmunología , Células Tumorales Cultivadas/inmunología

RESUMEN

The role of parenchymal and nonparenchymal mouse liver cells in the uptake of polymeric IgA (pIgA) and pIgA-containing immune complexes (IC) of low mol. wt (less than 1 x 10(6)) was studied. As detected by immunofluorescence and immunoelectron microscopy, pIgA were bound on the surface of isolated hepatocytes. Following the injection of radiolabeled pIgA or pIgA-IC into mice, the total radioactivity recovered from isolated liver cells was preferentially associated with parenchymal cells. The ability to inhibit the transport of pIgA and pIgA-IC by pIgA of an irrelevant specificity suggests that pIgA-IC and pIgA are bound and transported by the same mechanism. These results indicate that mouse hepatocytes are involved in the uptake and hepatobiliary transport of pIgA and pIgA-IC of low mol. wt.

Asunto(s)

Complejo Antígeno-Anticuerpo/metabolismo , Inmunoglobulina A/metabolismo , Hígado/inmunología , Muridae/inmunología , Animales , Bilis/inmunología , Transporte Biológico/efectos de los fármacos , Centrifugación por Gradiente de Densidad , Cicloheximida/farmacología , Técnica del Anticuerpo Fluorescente , Microscopía Electrónica

RESUMEN

Dinitrophenylated human serum albumin (DNP-HSA) with various DNP:HSA ratios was prepared by direct conjugation with dinitrobenzene sulfate or with a caproic acid spacer group (DNP-cap-HSA) using DNP-epsilon-amino-caproic acid N-hydroxy-succinimide ester. The substitution ratio and chemical linkage (presence of a spacer group) were shown to affect the degree of murine anti-DNP antibody binding to antigen, and hence the tissue deposition and efficiency of hepatobiliary transport. DNP-HSA (4.5:1), which poorly binds to IgA anti-DNP antibody, is inefficiently transported into mouse bile. In contrast, 9:1 DNP-cap-HSA readily forms complexes and is more effectively cleared by the hepatobiliary route. The IgA-mediated increase in liver deposition of DNP-cap-HSA (9:1) was found to be associated with an increase in antigen uptake by hepatocytes. In contrast, large complexes formed between DNP-HSA (49:1) and IgA anti-DNP antibody are taken up by nonparenchymal cells of the liver and thus are inefficiently transported into bile. These results suggest that the IgA-mediated uptake by phagocytic cells or hepatocytes of haptenated protein strongly depends on the degree of haptenation.

Asunto(s)

Dinitrofenoles/metabolismo , Inmunoglobulina A/inmunología , Albúmina Sérica/metabolismo , Animales , Complejo Antígeno-Anticuerpo/metabolismo , Bilis/inmunología , Dinitrofenoles/inmunología , Humanos , Hígado/inmunología , Ratones , Bazo/inmunología

RESUMEN

The tissue sites of monomeric IgA (mIgA) catabolism were determined in a BALB/c mouse model. Mouse mIgA myeloma proteins were labeled either by direct iodination or by coupling the residualizing label, dilactitol-125I-tyramine (125I-DLT) to the proteins; catabolites from protein labeled with 125I-DLT accumulate at the site of protein degradation, allowing identification of the tissue and cellular sites involved in catabolism of the protein. The circulating half-lives of 125I- and 125I-DLT-mIgA were the same. The distribution of radioactivity in tissues was measured at 1, 3, 24, and 96 h after iv. injection of 125I-DLT-labeled mIgA, dimeric IgA (dIgA), IgG, or mouse serum albumin. The greatest uptake of 125I-DLT-mIgA was attributable to the liver. This organ accounted for more internal catabolism of mIgA than all other tissues combined. In contrast, 125I-DLT-IgG was catabolized equally in skin, muscle, and liver. These data indicate that, in mice, the liver is the major site of mIgA catabolism. To determine the cell types involved, collagenase digestion was used to isolate parenchymal and non-parenchymal cells from perfused liver of animals injected with 125-DLT-mIgA. Most of the radioactivity was associated with the hepatocyte fraction, even though both cell types showed uptake of 125I-DLT-mIgA. Inhibition studies, with asialofetuin and mouse IgA demonstrated that the uptake of mIgA by liver cells was mediated primarily by the asialoglycoprotein receptor.

Asunto(s)

Asialoglicoproteínas , Inmunoglobulina A/metabolismo , Hígado/metabolismo , Receptores Fc , Animales , Receptor de Asialoglicoproteína , Femenino , Fetuínas , Radioisótopos de Yodo/metabolismo , Hígado/citología , Masculino , Ratones , Ratones Endogámicos BALB C , Músculos/metabolismo , Receptores Inmunológicos/análisis , Piel/metabolismo , Tiramina/análogos & derivados , Tiramina/metabolismo , alfa-Fetoproteínas/metabolismo

Asunto(s)

Trastornos de Ansiedad/terapia , Terapia Conductista/métodos , Cognición , Trastornos de Ansiedad/psicología , Niño , Humanos