RESUMEN
BACKGROUND: The pathogenesis of morbidity and mortality associated with intervention of the biliary system in patients with obstructive jaundice is unknown. Mechanical jaundice initiates the development of morphological changes in hepatocytes with concomitant disturbances in metabolism. These are followed by changes in enzyme activity in hepatocytes and peripheral blood. MATERIAL AND METHODS: Wistar rats were divided into three groups: group 1, sham-operated controls; group 2, rats with permanent jaundice; and group 3, rats with temporary mechanical jaundice. The animals were examined at 2 weeks (groups A), 4 weeks (groups B) and 6 weeks (groups C) after surgery. We explored the impact of induced mechanical jaundice on the activity of selected urea cycle enzymes (arginase [E.C.3.5.3.1] and ornithine transcarbamoylase (OTC) [E.C.2.1.3.3]). RESULTS: Mechanical jaundice was found to induce changes in hepatocytic metabolism, which in turn led to disturbances in the urea cycle and the process of transamination. After relief of the mechanical jaundice (recanalization of the common bile duct), the urea cycle activity in the liver was greatly increased despite the normalization of the basic biochemical indices. CONCLUSION: The results of the experiment confirmed the hypothesis that long-term mechanical jaundice causes lasting disturbances in hepatocytic metabolism. We conclude that the rate of nitrogen metabolism is higher after recanalization of the bile duct.
Asunto(s)
Arginasa/metabolismo , Ictericia Obstructiva/enzimología , Ornitina Carbamoiltransferasa/metabolismo , Fosfatasa Alcalina/sangre , Animales , Bilirrubina/sangre , Modelos Animales de Enfermedad , Ictericia Obstructiva/sangre , Masculino , Ratas , Ratas Wistar , Urea/metabolismoRESUMEN
Tissue levels of nineteen amino acids and total free amino acids, were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular muscle cardiomyocytes. The tissues were assayed after the rats had been administered IP with the three cardioactive drugs, exerting a significant effect on their heart action: propranolol, pentylenetetrazol and reserpine. It was demonstrated that while in the atrial and ventricular cardiac muscle cytosols of control rats, arginine, glutamine and cysteine were detected in high levels (35.1% and 17.6%; 14.8% and 51.6%; 9.9% and 0.25% of the total free amino acids, respectively), all three drugs significantly reduced the total amounts of cytosolic free amino acids in both atrial and ventricular heart muscles. All three drugs (with reserpine in particular) modified the levels of arginine, cysteine, phenylalanine, tryptophan, isoleucine and tyrosine. The role of these amino acids in the heart muscle cytosol, and their involvement in the mechanism of action of these three cardioactive drugs, is discussed.
Asunto(s)
Aminoácidos/metabolismo , Corazón/efectos de los fármacos , Miocardio/metabolismo , Pentilenotetrazol/farmacología , Propranolol/farmacología , Reserpina/farmacología , Animales , Citosol/metabolismo , Atrios Cardíacos/efectos de los fármacos , Atrios Cardíacos/metabolismo , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Masculino , Ratas , Ratas WistarRESUMEN
Levels of the 19 proteinous amino acids and total free amino acids were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular muscle cardiomyocytes. The tissues were assayed after the rats had been exposed to the cardioactive drugs digoxin, caffeine, and isoproterenol, each having different mechanisms of action. We demonstrated that, in the atrial and ventricular cardiac muscle cytosol of control (untreated) rats, arginine, glutamine, and cysteine existed in their highest levels: 35.1% and 17.6%; 14.8% and 51.6%; 9.9% and 0.25% of the total free amino acids, respectively. The levels of the other amino acids in the atrial and ventricular cardiac muscle cytosols ranged between 0.1% and 10.0% of the total free amino acids. Digoxin, caffeine, and isoproterenol significantly reduced the total amount of cytosolic free amino acids in the atrial heart muscle cytosol to 7.6%, 9.0%, and 9.2% of the control value (100%), and in the ventricular heart muscle cytosol to 31.1%, 43.2%, and 28.3% of the control. The three drugs tested changed the cytosols' levels of arginine, cysteine, tryptophane, asparagine, and tyrosine in atrial and ventricular heart muscle cytosol, as compared to the control groups (calculated as a percent of the total free amino acids in the experimental groups). The role of proteinous amino acids in the function of the heart muscle and in the mechanism of action of these drugs on the mammalian heart is discussed.
Asunto(s)
Aminoácidos/metabolismo , Cafeína/farmacología , Digoxina/farmacología , Corazón/efectos de los fármacos , Isoproterenol/farmacología , Miocardio/metabolismo , Animales , Citosol/metabolismo , Atrios Cardíacos/efectos de los fármacos , Atrios Cardíacos/metabolismo , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Masculino , Ratas , Ratas WistarRESUMEN
To date experimental in vivo pheochromocytoma (PC) models have not been available. A major in vitro PC model consists of PC12 cells that respond to nerve growth factor (NGF) by differentiation, mediated by the trkA receptor. We report the establishment of PC12 tumor models expressing low and high levels of trkA receptor in CD1 nude mice. The tumors are characterized by their responsiveness to NGF, karyotype, presence of enolase, and chromaffin granules, as well as dopamine release. These novel PC models facilitate research on the role of the trkA receptor in cancer and the development of trkA-selective anti-cancer agents.
Asunto(s)
Modelos Animales de Enfermedad , Células PC12/metabolismo , Feocromocitoma/metabolismo , Receptor trkA/metabolismo , Animales , Técnicas de Cultivo de Célula , Ratones , Ratones Desnudos , Trasplante de Neoplasias , Feocromocitoma/patología , Ratas , Trasplante HeterólogoRESUMEN
Snake venoms are a very abundant source of nerve growth factors (NGF). NGFs of Elapidae showing 65% sequence homology with mouse or human NGF, while the Viperidae NGF shows N-glycosylation (Asn-21) typical of these mammalian NGFs. Snake NGF-induced neurite outgrowth (neurotropic activity) was measured in the past by using PC12 cell or dorsal root ganglion bioassays. The present study was aimed at comparing, by dose-response experiments, the neurotropic activity of cobra and vipera versus mammalian NGFs, by using a novel bioassay involving PC12 cells genetically engineered to overexpress NGF-trkA receptors of human origin. These cells respond to NGF by differentiation (morphologically expressed as neurite outgrowth) by a process mediated by NGF-trkA receptors. This process was evaluated by two different criteria: (1) elongation of neurites (E), and (2) Percentage of responsive cells (PRC) determined by digital acquisition of data and computer analysis. We found that snake venom NGFs were less potent than mouse NGF, and that cobra NGF was more potent than vipera NGF. These data indicate the following order of NGF activity towards recombinant human trkA receptors: recombinant human NGF>mouse NGF>cobra NGF>vipera NGF. The neurotropic efficacy of these NGFs was found to be similar, reaching 80-90% of maximal activity obtained with all NGF forms. Interestingly, cobra (but not vipera) NGF demonstrated prolonged neurotropic activity compared with mouse NGF. The results of the present study indicate that cobra and vipera venom NGFs represent natural agonists of human trkA-receptor of a lower potency, but of similar efficacy, compared with mammalian NGFs. These compounds are important pharmacological tools to characterize the trkA receptor structure-function relationship, and to develop novel neurotropic drugs.
Asunto(s)
Bioensayo/métodos , Venenos Elapídicos/farmacología , Factores de Crecimiento Nervioso/efectos de los fármacos , Receptor trkA/metabolismo , Venenos de Víboras/farmacología , Animales , Relación Dosis-Respuesta a Droga , Humanos , Ratones , Factores de Crecimiento Nervioso/aislamiento & purificación , Neuritas/efectos de los fármacos , Células PC12 , Ratas , Receptor trkA/genética , Proteínas Recombinantes/efectos de los fármacosRESUMEN
Levels of 19 proteinous amino acids and of total free amino acids were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular heart muscle cardiomyocytes. These amino acids were assayed after the rats had been exposed to either exercise (swimming) or hypoxia (hypobaric pressure of 686 hectoPascals). Out of the total free amino acids levels of arginine, glutamine and cysteine in atrial and ventricular cardiac muscle cytosols of control rats were the highest of all amino acids assayed. The control levels of all other amino acids assayed in atrial or ventricular cardiac muscles ranged from 0.1% to 10.6% of the total free amino acids in the control rats. Physical stress (exercise and hypoxia) significantly reduced the total amount of cytosolic free amino acids in both heart muscles. While hypoxia decreased the levels of arginine in both heart muscles, exercise abolished the level of cysteine in the atrial heart muscle. Decrease in arginine levels, and elimination of cysteine from the heart's atrial muscle after physical stress, may be attributed to its utilization of nitric oxide and to its synthesis of atriopeptin and/or endothelin during stress. No change was recorded in either experimental group in the level of glutamine in heart muscle cytosol. Exercise and hypoxia affect, in different modes, the levels of all other amino acids assayed, except for tryptophan, tyrosine, and histidine, which are precursors of endogenous neurotransmitters. The impact of proteinous amino acids on some bodily functions is discussed.
Asunto(s)
Aminoácidos/metabolismo , Hipoxia/metabolismo , Miocardio/metabolismo , Condicionamiento Físico Animal , Animales , Citosol/metabolismo , Atrios Cardíacos/metabolismo , Frecuencia Cardíaca , Ventrículos Cardíacos/metabolismo , Masculino , RatasRESUMEN
The purpose of this study was to investigate how ethanol pretreatment and storage temperatures of brain striatum affect levels of biogenic amines in this tissue. Adult Wistar male rats were injected with 25% ethanol (5.0 g/kg i.p.) while the control rats were administered i.p. with the same volume of saline. Two hours later the rats were decapitated, their brains removed, and the striatum separated. Each striatum was divided into three parts: one part was immediately frozen on dry ice and kept at -70 degrees C; a second fragment was kept in a household refrigerator (+4 degrees C); and the third fragment was kept at +22 degrees C. Twenty-four hours later, levels of DA, DOPAC, HVA, 3-MT, 5-HT, and 5-HIAA in the striatum were assayed by HPLC/ED. Immediately after decapitation; ethanol levels were assayed in the serum of ethanol-pretreated and saline-pretreated rats using gas chromatography. Our results indicate that levels of striatal DA, DOPAC, and HVA in saline-pretreated rats decreased significantly when the storage temperature of the striatum was raised from -70 degrees C, through +4 degrees C, to +22 degrees C, while levels of striatal 5-HT and 5-HIAA remained constant within the temperature range tested and levels of 3-MT fluctuated. In ethanol-pretreated rats, striatal levels of DOPAC, HVA, and 5-HIAA were increased in all three storage temperatures, while levels of DA, 5-HT, and 3-MT were decreased in those temperatures. Those decreases were most profound in striatal samples kept at +22 degrees C. We conclude that concern about possible interactions between drugs and biogenic amines should be exercised.
Asunto(s)
Aminas Biogénicas/metabolismo , Depresores del Sistema Nervioso Central/farmacología , Cuerpo Estriado/efectos de los fármacos , Etanol/farmacología , Animales , Etanol/sangre , Masculino , Ratas , Ratas WistarRESUMEN
Luminol-amplified chemiluminescence was generated by alveolar macrophages, harvested from the bronchoalveolar lavages of 16 patients with different radiological stages of non-invasive (asymptomatic) sarcoidosis. None of the patients received any steroid therapy during this study. The mean duration of the disease in these patients was 8 months, with a duration time range of 6-14 months. Six patients were in radiological stage 1, five in radiological stage 2 and five in radiological stage 3. Alveolar macrophages from bronchoalveolar lavages of eight healthy non-smoking volunteers were used as controls. All alveolar macrophages were stimulated by phorbol myristate acetate. A significant decrease was recorded in the intensity of chemiluminescence generated by the phorbol-ester-stimulated alveolar macrophages obtained from patients with sarcoidosis of radiological stages 1 and 2, as compared to the cells collected from healthy individuals (controls). No decrease was recorded in the chemiluminescence generated by stimulated alveolar macrophages collected from patients with radiological stage 3, or from unstimulated alveolar macrophages of any patient. These results provide us with an indicative tool, which might enable us to differentiate, on a functional basis, between the activities of alveolar macrophages in non-active sarcoidosis.
Asunto(s)
Macrófagos Alveolares/química , Sarcoidosis/metabolismo , Adulto , Líquido del Lavado Bronquioalveolar/citología , Supervivencia Celular , Femenino , Humanos , Indicadores y Reactivos , Cinética , Mediciones Luminiscentes , Luminol , Masculino , Persona de Mediana Edad , Radiografía , Sarcoidosis/diagnóstico por imagen , Estimulación Química , Acetato de TetradecanoilforbolRESUMEN
Nerve growth factor (NGF) is a neurotrophin required for differentiation, development, and survival of the sympathetic nervous system, with many of its biological effects being mediated via trkA receptors. There is a need for a standard quantitative bioassay for NGF, to be used in basic research and in pharmaceutical studies. The objective of the present research was to develop a selective, quantitative, and reliable bioassay for NGF, using a morphological criterion: neurite cell outgrowth. In addition, we aimed to apply the aforementioned bioassay to measure NGF administered to mice. Pheochromocytoma PC12 cell variants including wild-type cultures, and a trkA-overexpressing stable transfectant PC12-6.24-I, PC12nnr5, and PC12EN lacking trkA receptors, were used. Dose-response curves were generated with NGF beta-subunit (2.5S) purified from mouse submaxillary glands. Our results demonstrated that the bioassay was sensitive to 0.3-20 ng/mL, and selective, as neurite outgrowth was not seen by any other growth factor other than NGF. In addition, variant clones PC12nnr5 and PC12EN, lacking trkA receptors, did not respond to NGF. The bioassay detected NGF in serum of mice injected with NGF. This novel developed bioassay can serve as a model system for various neuroscience purposes.