RESUMEN
In the adult, the peptide hormone angiotensin II (AII) is primarily known as a regulator of circulatory homeostasis, but recent evidence also suggests a role in cell growth. This study of AII in late gestation rat fetuses revealed the unexpected presence of receptors in skeletal muscle and connective tissue, in addition to those in recognized adult target tissues. The AII receptors in this novel location decreased by 80 percent 1 day after birth and were almost undetectable in the adult. Studies in fetal skin fibroblasts showed that the receptors were coupled to phospholipid breakdown, with concomitant increases in inositol phosphate and cytosolic calcium. The abundance, timing of expression, and unique localization of functional AII receptors in the fetus suggest a role for AII in fetal development.
Asunto(s)
Angiotensina II/metabolismo , Feto/metabolismo , Receptores de Angiotensina/biosíntesis , Angiotensina II/fisiología , Animales , Calcio/metabolismo , Fibroblastos/metabolismo , Fosfatos de Inositol/metabolismo , Ratas , Ratas EndogámicasRESUMEN
Angiotensin II (AII) stimulates rapid increases in the concentration of cytosolic calcium in follicular oocytes from Xenopus laevis. This calcium response was not present in denuded oocytes, indicating that it is mediated by AII receptors on the adherent follicular cells. The endogenous AII receptors differed in their binding properties from mammalian AII receptors expressed on the oocyte surface after injection of rat adrenal messenger RNA. Also, the calcium responses to activation of the amphibian AII receptor, but not the expressed mammalian AII receptor, were blocked reversibly by octanol and intracellular acidification, treatments that inhibit cell coupling through gap junctions. In addition, AII increased the rate of progesterone-induced maturation. Thus, an AII-induced calcium-mobilizing signal is transferred from follicle cells to the oocyte through gap junctions and may play a physiological role in oocyte maturation.
Asunto(s)
Angiotensina II/análogos & derivados , Angiotensina II/farmacología , Calcio/metabolismo , Uniones Intercelulares/fisiología , Oocitos/fisiología , Transducción de Señal , Aequorina , Angiotensina II/metabolismo , Animales , Citosol/efectos de los fármacos , Citosol/metabolismo , Femenino , Uniones Intercelulares/efectos de los fármacos , Cinética , Luminiscencia , Oocitos/efectos de los fármacos , Progesterona/farmacología , Receptores de Angiotensina/metabolismo , Transducción de Señal/efectos de los fármacos , Relación Estructura-Actividad , Xenopus laevisRESUMEN
Liver transplantation has evolved from an experimental treatment to be considered as the most effective therapy for end-stage liver disease and selected cases of hepatocellular carcinoma. Transplant hepatologists must have specific knowledge and abilities to treat those patients who receive a liver transplant. In Spain, approximately 1100 liver transplants are performed each year, and most centers assume both postoperative care and long-term follow-up, which has led to a significant work load in liver transplant units. Despite previous attempts to establish an official training program in hepatology, the Spanish health system does not presently have a specific liver transplant training program to guarantee that future needs of physicians are covered. Collaboration between health authorities and scientific societies is required to guarantee adequate assistance to liver transplant recipients in the future.
Asunto(s)
Gastroenterólogos/educación , Gastroenterología/educación , Trasplante de Hígado , Gastroenterólogos/provisión & distribución , Humanos , Trasplante de Hígado/tendencias , Persona de Mediana Edad , EspañaRESUMEN
OBJECTIVES: To assess the effect of high doses of corticosteroids in patients hospitalised for exacerbation of chronic obstructive pulmonary disease (COPD). PATIENTS AND METHODS: A prospective cohort study was conducted on patients hospitalized with COPD between January and March 2015, grouped according to the glucocorticoid dosage administered (cutoff, 40mg of prednisone/day). We compared the results of hospital stay, readmission and mortality at 3 months of discharge. RESULTS: We analysed 87 patients. The median daily dose was 60mg of prednisone (interquartile range, 46.67-82.33mg/day), and the administration route was intravenous in 96.6% of the cases. We established a relative risk (RR) for hospital stays longer than 8 days of 1.095 (95% CI 0.597-2.007; P=.765) when steroid dosages greater than 40mg/day were employed. In these patients, the hazard ratio (HR) for readmission in the 3 months after discharge was 0.903 (95% CI 0.392-2.082; P=.811), and the mortality was 1.832 (95% CI 0.229-16.645; P=.568). Neither the RR nor the HR varied in a statistically significant manner after adjusting for confounding factors. CONCLUSIONS: A daily dose greater than 40mg of prednisone in patients hospitalised for COPD exacerbation was not associated with a shorter hospital stay or a reduction in readmissions or mortality at 3 months.
RESUMEN
The presence of MICA antibodies was examined in eleven patients diagnosed with AHR. MICA typing was performed in both recipients and donors. Sera were collected sequentially: pre-transplant, at the AHR episode and at follow-up. Sera from 30 patients with functioning graft were also analysed. A stable MICA()008 transfected cell line was used as target to identify MICA antibodies. MICA antibodies were not detected pre-transplant nor post-transplant in patients receiving a compatible graft. MICA antibodies were detected post-transplant AHR in patients receiving an incompatible graft. The persistence of MICA antibodies was associated with chronic graft dysfunction in 3 of 4 patients in this series; although it was not always associated with the graft loss in treated AHR. None of the 30 patients in the control group with long-term functioning grafts showed antibodies to MICA()008. This report provides some insights of the relevance of MICA antibodies in AHR.
Asunto(s)
Rechazo de Injerto/etiología , Rechazo de Injerto/inmunología , Antígenos de Histocompatibilidad Clase I , Isoanticuerpos/sangre , Trasplante de Riñón/efectos adversos , Trasplante de Riñón/inmunología , Enfermedad Aguda , Línea Celular , Enfermedad Crónica , Antígenos de Histocompatibilidad Clase I/genética , Humanos , Estudios Prospectivos , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , TransfecciónRESUMEN
Receptors for angiotensin II (AII) were identified and characterized in testes of rats and several primate species. Autoradiographic analysis of the binding of 125I-labeled [Sar1,Ile8]AII to rat, rhesus monkey, cebus monkey, and human testicular slide-mounted frozen sections indicated specific binding to Leydig cells in the interstitium. In rat collagenase-dispersed interstitial cells fractionated by Percoll gradient, AII receptor content was parallel to that of hCG receptors, confirming that the AII receptors are in the Leydig cells. In rat dispersed Leydig cells, binding was specific for AII and its analogs and of high affinity (Kd, 4.8 nM), with a receptor concentration of 15 fmol/10(6) cells. Studies of AII receptors in rat testes during development reveals the presence of high receptor density in newborn rats which decreases toward the adult age (4934 +/- 309, 1460 +/- 228, 772 +/- 169, and 82 +/- 12 fmol/mg protein at 5, 15, 20, and 30 days of age, respectively) with no change in affinity. At all ages receptors were located in the interstitium, and the decrease in binding was parallel to the decrease in the interstitial to tubular ratio observed with age. AII receptor properties in membrane-rich fractions from prepuberal testes were similar in the rat and rhesus monkey. Binding was time and temperature dependent, reaching a plateau at 60 min at 37 C, and was increased by divalent cations, EGTA, and dithiothreitol up to 0.5 mM. In membranes from prepuberal monkey testes, AII receptors were specific for AII analogs and of high affinity (Kd, 4.2 nM) with a receptor concentration of 7599 +/- 1342 fmol/mg protein. The presence of AII receptors in Leydig cells in rat and primate testes in conjunction with reports of the presence of other components of the renin-angiotensin system in the testes suggests that the peptide has a physiological role in testicular function.
Asunto(s)
Angiotensina II/metabolismo , Receptores de Angiotensina/metabolismo , Testículo/metabolismo , Envejecimiento , Animales , Autorradiografía , Radioisótopos de Yodo , Cinética , Células Intersticiales del Testículo/metabolismo , Masculino , Ratas , Ratas Endogámicas , Testículo/crecimiento & desarrolloRESUMEN
To investigate the ontogeny of the renin-angiotensin system we studied the characteristics and location of angiotensin II (AII) receptors in mouse fetuses and examined sites of renin mRNA expression by in situ hybridization and Northern blot analysis. Autoradiographic analysis of the binding of 125I-[Sar1,Ala8]AII to slide-mounted frozen sections of 17-day-old DBA/2N mice revealed abundant AII receptors widely distributed throughout the body. High receptor density was found in primitive mesenchymal tissue under the epidermis and surrounding muscle and cartilage, in skeletal and smooth muscle, and in all layers of the adrenal cortex. Lower receptor density was seen in the kidney, liver, and lungs. The autoradiographic staining was abolished by incubation of the sections with excess unlabeled AII. Scatchard analysis of the binding of 125I-[Sar1,Ala8,]AII to membrane-rich fractions of eviscerated fetuses showed a single type of high affinity receptors with a Kd of 2.9 x 10(-9) M and a receptor concentration of 3300 fmol/mg protein. Localization of renin mRNA was analyzed by in situ hybridization using an antisense 35S-labeled riboprobe transcribed from a mouse renin2 cDNA clone. Hybridization to fetal tissue sections showed high intensity staining in the kidney and adrenal cortex. Northern blot analysis confirmed the high expression of renin mRNA in the fetal kidney. The presence of an active renin-angiotensin system in the fetus was confirmed by the demonstration of renin-like activity and bioactive AII in fetal extracts. The widespread distribution of AII receptors in the fetus, compared to the discrete localization to specialized tissues in the adult, may indicate a unique role for the peptide during development.
Asunto(s)
Feto/análisis , Receptores de Angiotensina/análisis , Renina/análisis , Angiotensina II/análisis , Angiotensina II/genética , Angiotensina II/metabolismo , Animales , Autorradiografía , Femenino , Feto/metabolismo , Feto/ultraestructura , Regulación de la Expresión Génica , Ratones , Embarazo , ARN Mensajero/análisis , Receptores de Angiotensina/metabolismo , Receptores de Angiotensina/fisiología , Renina/genética , Renina/metabolismoRESUMEN
The regulatory actions of CRF during the neuroendocrine response to stress are mediated by specific receptors within the nervous system and the anterior pituitary gland. Glucocorticoids exert negative feedback inhibition on ACTH secretion by interacting at the pituitary corticotrophs and the central nervous system. To determine whether glucocorticoids influence ACTH secretion by regulating the concentration of CRF receptor sites, binding of [125I]Tyr-oCRF to pituitary and brain membrane-rich particles was studied after glucocorticoid treatment. Corticosterone administration (0.5-150 mg/day) for 1-4 days in adult male rats caused a dose-dependent decrease in the number of CRF receptors in the anterior pituitary in parallel with the reduction in ACTH secretion. In the brain, binding studies in membrane-rich fractions or by autoradiography in slide-mounted frozen sections revealed no changes in CRF receptors in the cortex, hippocampus, amygdala, septal area, and olfactory bulb, although circulating corticosterone levels were higher than during stress. The selective down-regulation of anterior pituitary CRF receptors after corticosterone administration, without alterations in brain CRF receptors, is similar to the change in CRF receptors previously reported after adrenalectomy and indicates that receptor regulatory mechanisms in secretory cells differ from those in neural tissue. Furthermore, the decrease in pituitary CRF receptors after physiological increases in circulating glucocorticoids may contribute to the inhibitory effects of adrenal steroids on ACTH secretion.
Asunto(s)
Encéfalo/metabolismo , Corticosterona/farmacología , Adenohipófisis/metabolismo , Receptores de Neurotransmisores/metabolismo , Hormona Adrenocorticotrópica/metabolismo , Animales , Membrana Celular/metabolismo , Corticosterona/sangre , Hormona Liberadora de Corticotropina/metabolismo , Masculino , Ratas , Receptores de Hormona Liberadora de Corticotropina , Receptores de Neurotransmisores/efectos de los fármacos , Estrés Fisiológico/metabolismoRESUMEN
The regulation of pituitary and brain CRF receptors and corticotroph responses during stress were studied in rats subjected to prolonged immobilization. Plasma ACTH levels showed the characteristic biphasic changes, with a rapid 23-fold increase in 15 min, followed by a decrease to about twice the basal levels after 6-h immobilization. In contrast, plasma corticosterone levels were markedly elevated throughout the duration of the stress. Pituitary CRF receptor content, measured by binding of [125I]Tyr-ovine CRF to pituitary membrane-rich fractions, was unchanged after 2.5 h, but was reduced by 28 +/- 2.7% (+/- SE) and 47.6 +/- 1.1% after 18 and 48 h of immobilization, respectively. These results were confirmed by autoradiography in slide-mounted frozen pituitary sections. In contrast, no changes in CRF receptor content were observed in brain areas, including olfactory bulb, frontoparietal cortex, hippocampus, amygdala, and lateral septum. A concomitant decrease in immunoreactive (ir) CRF content in the median eminence of rats immobilized for 48 h is consistent with the hypothesis that increased release of CRF into the portal circulation occurs during chronic stress. Despite pituitary CRF receptor loss and reduced in vitro responses to CRF, the increases in plasma ACTH and corticosterone in vivo after ether exposure or CRF injection were greater and more prolonged in rats immobilized for 48 h than in nonimmobilized controls. The decrease in pituitary CRF receptors was accompanied by decreased CRF-stimulated cAMP and ACTH release in cultured pituitary cells from 48-h restrained rats. However, concomitant incubation of cells with CRF and vasopressin restored cAMP and ACTH responses to control levels, suggesting that the simultaneous release of both regulators from the hypothalamus determines the plasma ACTH level. These findings indicate that the decrease in plasma ACTH during the adaptation phase to stress is accompanied by decreases in pituitary CRF receptors. However, the enhanced pituitary response to a superimposed stress or CRF injection implies that the decrease in plasma ACTH levels during prolonged stress may be due to adaptive changes at the central level. These findings emphasize the importance of the integrated actions of CRF and other regulators in the control of the pituitary adrenal-axis during stress.
Asunto(s)
Glándulas Suprarrenales/metabolismo , Hormona Adrenocorticotrópica/metabolismo , Arginina Vasopresina/metabolismo , Hormona Liberadora de Corticotropina/metabolismo , Adenohipófisis/metabolismo , Prolactina/metabolismo , Receptores de Neurotransmisores/metabolismo , Estrés Psicológico/fisiopatología , Hormona Adrenocorticotrópica/sangre , Animales , Encéfalo/metabolismo , Células Cultivadas , Cinética , Masculino , Eminencia Media/metabolismo , Prolactina/sangre , Ratas , Ratas Endogámicas , Receptores de Hormona Liberadora de Corticotropina , Restricción FísicaRESUMEN
The binding characteristics and distribution of angiotensin-II (AII) receptors were studied in Cynomolgus monkey fetuses and one second trimester human fetus. In contrast to the adult monkey, in which binding was confined to the adrenal gland, kidney, and smooth muscle, autoradiographic studies in the monkey fetus revealed the presence of high density binding in mesenchymal tissue throughout the body, especially in skeletal muscle and dermis. In the kidney at 11 weeks, binding was mainly associated with connective tissue surrounding primitive nephrons, while at 17 weeks, binding distribution was similar to that in the adult primate kidney, being confined to the glomeruli and smooth muscle of blood vessels, with low binding in the tubules. In fetal monkey adrenal, binding was high in the medulla and connective tissue of the capsule, and low in the zona glomerulosa, while in the adult, binding was high in the zona glomerulosa and medulla. In membrane preparations from fetal monkey skin and skeletal muscle, binding was specific for AII analogs, but in contrast to the adult adrenal, it was not affected by guanyl nucleotides. Scatchard analysis showed a single class of sites with a Kd of 0.6 +/- 0.1 nM and a capacity of 3060 +/- 8.3 fmol/mg, higher than that of the adult adrenal glomerulosa (605 +/- 30 fmol/mg). Specific binding for AII analogs was also present in human fetal skin and skeletal muscle membranes, where Scatchard analysis indicated a Kd of 0.8 nM and a binding capacity of 640 fmol/mg. The transient expression of abundant AII receptors during the phase of rapid growth in the fetus in conjunction with the known effects of AII on cellular growth suggest a role for AII during fetal development in the primate.
Asunto(s)
Feto/metabolismo , Receptores de Angiotensina/metabolismo , Glándulas Suprarrenales/metabolismo , Animales , Autorradiografía , Tejido Conectivo/metabolismo , Femenino , Humanos , Riñón/metabolismo , Macaca fascicularis , Músculo Liso Vascular/metabolismo , Músculos/metabolismo , Embarazo , Segundo Trimestre del Embarazo , Piel/metabolismoRESUMEN
Receptors for CRH were identified in the pituitary gland of several primate species, and their binding characteristics were compared to the ability of CRH to elicit ACTH and cAMP responses in vitro. Autoradiographic analysis of the binding of [125I]Tyr-ovine CRH to frozen pituitary sections revealed CRH receptors in the intermediate and anterior lobes of human, marmoset, and cynomolgus monkey pituitaries. In the cynomolgus monkey, a high density of CRH receptors was present throughout the anterior and intermediate lobes. In the human pituitary, binding was concentrated in the anteromedial portion of the gland, whereas in the marmoset, binding was dense in the intermediate lobe and scattered as clusters throughout the anterior lobe. In membrane-rich fractions from the cynomolgus pituitary binding of [125I]Tyr-ovine CRH was time and temperature dependent, and was specific for CRH-related peptides; specific binding was increased by divalent cations and inhibited by guanyl nucleotides. Scatchard analyses of the binding data revealed a single class of high affinity sites [Kd, 1.93 +/- 0.23 (+/- SEM) nM], with a receptor concentration of 605 +/- 121 fmol/mg. In marmoset pituitary membranes, there were fewer receptors (200 +/- 15 fmol/mg), in agreement with the lower autoradiographic density of CRH binding. In anterior pituitary cell cultures from cynomolgus monkeys, CRH caused a dose-dependent stimulation of cAMP production and ACTH release, with half-maximum effective concentrations in the range of the CRH receptor affinity. Vasopressin and norepinephrine stimulated ACTH release to a much lesser extent, but both potentiated the stimulatory effect of CRH. Angiotensin II had no effect alone, but it also potentiated the effect of CRH. These data demonstrate the presence of CRH receptors in the primate pituitary, with characteristics similar to those in other species in their binding properties, coupling to adenylate cyclase, and functional interactions with other regulators of ACTH secretion that mediate the stimulatory effect of the peptide in the corticotroph.
Asunto(s)
Hormona Liberadora de Corticotropina/farmacología , Hipófisis/metabolismo , Receptores de Neurotransmisores/metabolismo , Hormona Adrenocorticotrópica/metabolismo , Animales , Autorradiografía , Callitrichinae , Membrana Celular/metabolismo , Células Cultivadas , Hormona Liberadora de Corticotropina/metabolismo , AMP Cíclico/biosíntesis , Sinergismo Farmacológico , Nucleótidos de Guanina/farmacología , Humanos , Cinética , Macaca fascicularis , Norepinefrina/farmacología , Adenohipófisis/metabolismo , Receptores de Hormona Liberadora de Corticotropina , Receptores de Neurotransmisores/efectos de los fármacos , Vasopresinas/farmacologíaRESUMEN
High-affinity receptors for angiotensin II were identified on Xenopus laevis cardiac membranes and characterized by binding-inhibition studies with peptide and non-peptide AII antagonists. Scatchard analysis of the binding data identified a high-affinity site with Kd1 = 1.6 nM and Bmax1 = 3.7 pmol/mg protein and a low-affinity site with Kd2 = 22 nM and Bmax 2 = 9.5 pmol/mg protein. Treatment with dithiothreitol reduced the number of binding sites by greater than 70%. The rank order of potency for ALL analogs was (agent, IC50) [Sar1,Ile8]AII, 0.91 nM greater than AII, 2.0 nM greater than AI, 5.3 nM greater than [Sar1, Ala8]AII, 19 nM much greater than CGP42112A, 1.2 microM much much greater than DuP 753 approximately PD-123177, greater than 100 microM. The relative potencies of these compounds differ markedly from their activities on the two known mammalian AII receptor subtypes, AT1 and AT2. These results indicate that amphibian AII receptors are pharmacologically distinct from both the AT1 and AT2 receptors characterized in mammalian tissues.
Asunto(s)
Angiotensina II/metabolismo , Miocardio/metabolismo , Receptores de Angiotensina/metabolismo , Xenopus laevis/metabolismo , 1-Sarcosina-8-Isoleucina Angiotensina II/metabolismo , Angiotensina I/metabolismo , Animales , Unión Competitiva , Membrana Celular/metabolismo , Ditiotreitol/farmacología , Cinética , Oocitos/metabolismo , Saralasina/metabolismoRESUMEN
The presence of components of the renin-angiotensin system in ovaries and testes suggests that angiotensin II (AII) is involved in gonadal function, and thus we sought to characterize receptors for AII in rat and primate gonads. In the testes, autoradiographic studies showed receptors in the interstitium in all species. In rat interstitial cells fractionated by Percoll gradient, AII receptors coincided with hCG receptors indicating that AII receptors are located on the Leydig cells. In Leydig cells and membranes from rat and rhesus monkey prepuberal testes, AII receptors were specific for AII analogues and of high affinity (Kd=nM). During development, AII receptor content in rat testes decreases with age parallel to a fall in the ratio of interstitial to tubular tissue. In the ovary, the distribution of AII receptors was dependent on the stage of development, being high in the germinal epithelium and stromal tissue between five and 15 days, and becoming localized in secondary follicles in 20-and 40-day-old rats. No binding was found in primordial or primary follicles. In rhesus monkey ovary, AII receptors were higher in stromal tissue and lower in granulosa and luteal cells of the follicles. Characterization of the binding in rat and monkey ovarian membranes showed a single class of sites with a Kd in the nmol/L range and specificity similar to that of the adrenal glomerulosa and testicular AII receptors. Receptors for AII were also present in membrane fractions from PMSG/hCG primed rat ovaries. Infusion of AII (25 ng/min) or captopril (1.4 micrograms/min) during the PMSG/hCG induction period had no effect on ovarian weight or AII receptor concentration in the ovaries.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Angiotensina II/metabolismo , Gónadas/ultraestructura , Receptores de Angiotensina/análisis , Animales , Autorradiografía , Cebus , Gonadotropina Coriónica/farmacología , Femenino , Gonadotropinas Equinas/farmacología , Gónadas/metabolismo , Humanos , Radioisótopos de Yodo , Macaca mulatta , Masculino , Ovario/metabolismo , Ovario/ultraestructura , Ratas , Ratas Endogámicas , Receptores de Angiotensina/metabolismo , Testículo/metabolismo , Testículo/ultraestructuraRESUMEN
AII binding and distribution were measured in rat brain during development by autoradiographic techniques using radioiodinated [Sar1,Ile8]AII. At all ages, from 2 days to 7 weeks, binding was present in the circumventricular organs, and areas related to pituitary hormone secretion and modulation of sympathetic activity. At early stages of development, AII binding was transiently expressed in a number of motor- and sensory-related areas. These findings support a role for AII in the control of water intake and autonomic activity at all stages of development, and suggest that the peptide may be involved in the maturation of neuronal function during development.
Asunto(s)
Angiotensina II/metabolismo , Encéfalo/crecimiento & desarrollo , Receptores de Angiotensina/metabolismo , Animales , Autorradiografía , Encéfalo/metabolismo , Ratas , Ratas Endogámicas , Distribución TisularRESUMEN
Angiotensin II binding sites were demonstrated at discrete nuclei in the brain of three nonhuman primate species by autoradiography, using the agonist ligand, [Sar1]AII. Although there were some differences in location of the binding sites, all three species exhibited a characteristic pattern of distribution in areas related to water intake, vasopressin secretion, and blood pressure regulation through modulation of sympathetic activity. Studies in the cynomolgus monkey with the antagonist ligand, [Sar1,Ile8]AII, which localizes in pathways as well as nuclei, revealed novel regions of binding including the habenular-interpeduncular pathway, ventral bundle, and XII nerve, in addition to the X nerve. These data indicated that AII, as in other species, has a role in the central homeostatic control mechanisms in the primate.
Asunto(s)
Angiotensina II/metabolismo , Química Encefálica , Receptores de Angiotensina/análisis , Angiotensina II/análogos & derivados , Animales , Autorradiografía , Callitrichinae , Macaca fascicularis , Membranas/análisis , Receptores de Angiotensina/metabolismo , SaimiriRESUMEN
The presence of AII receptors during early and late embryonic development was studied by binding of 125I[Sar1, Ile8] AII to whole mouse blastocysts and membrane-rich fractions from rat conceptuses, 7 to 21 days in gestation. In early mouse embryos there was no detectable binding under a variety of experimental conditions. However, in late gestation rat fetuses, specific and high affinity binding was observed, with a concentration of sites similar in membranes from whole and eviscerated fetuses. Using less than 100 micrograms of membrane protein, binding was time and temperature dependent, maintaining equilibrium from 30 to 120 min at 23 degrees C and it was enhanced by addition of Mg+2 up to 5 mM, EGTA 2 mM and dithiothreitol up to 2.5 mM. Scatchard analysis of the binding data indicated Kd values ranging between 0.7 and 0.9 nM. Binding was first detectable at day 10 (14.3 +/- 2.3 fmol/mg), increasing to 104 +/- 16, 2,625 +/- 168, 5,993 +/- 152 and 5,902 +/- 92 by days 12, 15, 18, and 21 of gestational age, respectively. Since the functional significance of these binding sites depends on the availability of the agonist ligand, acid extracts from eviscerated 10-day-old fetuses were analyzed for the presence of AII. Measurement of AII by radioimmunoassay revealed immunoreactive AII-like material (845 pg/g of tissue), with an elution pattern identical to that of AII standard in a Sephadex G-50 column. This material was bioactive, as demonstrated by its ability to displace 125I[Sar1, Ile8]AII from adrenal glomerulosa membranes, an effect which was abolished by pretreatment of the extract with AII antibody.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Angiotensina II/metabolismo , Feto/metabolismo , Receptores de Angiotensina/metabolismo , Angiotensina II/análogos & derivados , Animales , Blastocisto/metabolismo , Membrana Celular/metabolismo , Desarrollo Embrionario y Fetal , Inhibidores Enzimáticos/metabolismo , Femenino , Cinética , Embarazo , RatasRESUMEN
Specific receptors for corticotropin releasing factor (CRF) were identified in two functionally distinct systems within the brain, the cortex and the limbic system. Autoradiographic mapping of the CRF receptors in the brain revealed high binding density throughout the neocortex and cerebellar cortex, subiculum, lateral septum, olfactory tract, bed nucleus of the stria terminalis, interpeduncular nucleus and superior colliculus. Moderate to low binding was found in the hippocampus, nucleus accumbens, claustrum, nucleus periventricularis thalamus, mammillary bodies, subthalamic nucleus, periaqueductal grey, locus coeruleus and nucleus of the spinal trigeminal tract. As in the anterior pituitary gland, CRF receptors in the brain were shown to be coupled to adenylate cyclase. However, in contrast to the marked decrease in CRF receptors observed after adrenalectomy in the anterior pituitary gland, CRF receptor concentration in the brain and pars intermedia of the pituitary was unchanged. The presence of CRF receptors in areas involved in the control of hypothalamic and autonomic nervous system functions is consistent with the major role of CRF in the integrated response to stress.
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Encéfalo/metabolismo , Hormona Liberadora de Corticotropina/metabolismo , Hipófisis/metabolismo , Receptores de Superficie Celular/metabolismo , Adenilil Ciclasas/metabolismo , Glándulas Suprarrenales/fisiología , Adrenalectomía , Animales , Autorradiografía , Masculino , Ratas , Receptores de Hormona Liberadora de Corticotropina , Estrés Fisiológico/fisiopatología , Distribución TisularRESUMEN
Angiotensin II (AII) receptor subtypes were studied in the 18-day gestation fetal rat, using two non-peptide AII antagonists: (2-n-butyl-4-chloro-5-hydroxymethyl-1-(2'-(1H-tetrazol-5-yl) biphenyl-4-yl)methyl)imidazol (DuP 753; type 1 (AT1) specific), and 1-(4-amino-3-methylphenyl)methyl-5-diphenacetyl -4,5,6,7-tetrahydro-1-H-imidazo[4,5-c]pyridine-6-carboxylic acid (PD 123177; type 2 (AT2) specific). Autoradiography using 125I(-)[Sar1,Ile8]AII showed that 10 microM PD 123177 decreased binding to near-nonspecific levels in skin, skeletal muscle and adrenal medulla, whereas 10 microM DuP 753 blocked binding in the liver and lung. Studies in skin and liver membranes confirmed the autoradiographic data: AT1 receptors were predominant in the liver (95%), and AT2 in the skin (97%). There was no cross-reactivity between receptor subtype and the heterologous antagonist up to a concentration of 10 microM. In both skin and liver, 2 mM dithiothreitol enhanced the binding of AT2 receptors by increasing receptor affinity, but inhibited binding of AT1 by decreasing the receptor number. In the absence of antagonists, guanyl nucleotides, added at equilibrium, caused marked dissociation of 125I-AII binding in liver membranes, but had minimal effect in skin. However, dissociation occurred in the skin when AT2 sites were blocked with 10 microM PD 123177, and in liver, dissociation was not observed when AT1 sites were blocked with DuP 753. Hence, in contrast to classical AII target tissues, which contain predominantly AT1, most of the sites in fetal skin and skeletal muscle are AT2. The demonstration that the effects of guanyl nucleotides are selective for receptor subtype suggests that the AT1 receptor, but not the AT2, is coupled to cell function via guanyl nucleotide binding proteins. The functional importance of the AT2 receptors and their role in fetal physiology is under current investigation.
Asunto(s)
Feto/metabolismo , Receptores de Angiotensina/metabolismo , Glándulas Suprarrenales/efectos de los fármacos , Glándulas Suprarrenales/embriología , Glándulas Suprarrenales/metabolismo , Animales , Autorradiografía , Sitios de Unión , Compuestos de Bifenilo/farmacología , Ditiotreitol/farmacología , Feto/efectos de los fármacos , Guanosina 5'-O-(3-Tiotrifosfato)/farmacología , Procesamiento de Imagen Asistido por Computador , Imidazoles/farmacología , Hígado/efectos de los fármacos , Hígado/embriología , Hígado/metabolismo , Losartán , Músculos/efectos de los fármacos , Músculos/embriología , Músculos/metabolismo , Piridinas/farmacología , Ratas , Ratas Sprague-Dawley , Piel/efectos de los fármacos , Piel/embriología , Piel/metabolismo , Tetrazoles/farmacologíaRESUMEN
Several techniques of patent ductus arteriosus occlusion primarily by thoracotomy have been practiced. They have shown to be more reliable than nonsurgical procedures. Videothoracoscopy has been useful in several intrathoracic surgical procedures with faster recovery and minimal mortality and morbidity. We report 2 patients with clipping and ligation of a patent ductus arteriosus by a thoracoscopic approach. This technique may be useful in children with a noncomplicated patent ductus arteriosus. It allows an easier recovery and causes less pain.
Asunto(s)
Conducto Arterioso Permeable/cirugía , Toracoscopía , Niño , Preescolar , Constricción , Femenino , Humanos , Ligadura/métodos , MasculinoRESUMEN
Thirty-nine patients (29 children and ten adults) underwent OLT for liver disease associated with A1AD from March 1980 to March 1986. Thirty of thirty-six patients (83%) with available data were homozygous phenotype PiZZ. The other six were Pi heterozygotes, being either PiMZ or PiSZ. The mean A1A activity in homozygous and heterozygous patients was 38.8 mg/dL and 114.3 mg/dL respectively. Eight patients died during the first 3 months after OLT (20%). The 5-year actuarial survival is 83% and 60% in pediatric and adult recipients respectively. Today 30 (76%) of the recipients are alive, with follow-ups of 8 to 64 months (average 27 months). The quality of life in the surviving patients is excellent.