RESUMEN
BACKGROUND: The purpose of this study was to test whether continuous hemofiltration eliminates cytokines and eicosanoids, or stimulates granulocyte function. METHODS: Nineteen pigs were divided into a control group (n = 7), a hemofiltration group (n = 7), and an extracorporeal circuit only group (n = 5). All animals received the same amount of intravenous endotoxin and resuscitation fluid. Zero-balanced hemofiltration was started 30 minutes after initiation of endotoxemia and continued throughout the experiment. Plasma endotoxin, tumor necrosis factor-alpha, eicosanoids, superoxide production, and other physiologic parameters were measured before challenge and at scheduled intervals thereafter. RESULTS: Eicosanoids were filtered but plasma concentrations were not reduced. Tumor necrosis factor-alpha was not filtered or adsorbed. There were no significant differences between groups in any measured parameters. CONCLUSION: Continuous hemofiltration could not efficiently remove tumor necrosis factor-alpha or eicosanoids. Also, continuous hemofiltration did not stimulate production of the proinflammatory mediators measured, nor improve respiratory distress.
Asunto(s)
Endotoxinas/administración & dosificación , Hemofiltración , Mediadores de Inflamación/sangre , Sepsis/metabolismo , Superóxidos/metabolismo , 6-Cetoprostaglandina F1 alfa/sangre , Animales , Escherichia coli , Femenino , Granulocitos/metabolismo , Peróxido de Hidrógeno/metabolismo , Infusiones Intravenosas , Lipopolisacáridos/administración & dosificación , Pulmón/patología , Mecánica Respiratoria , Sepsis/patología , Sepsis/fisiopatología , Sepsis/terapia , Porcinos , Tromboxano B2/sangre , Factores de Tiempo , Factor de Necrosis Tumoral alfa/análisisRESUMEN
The free tetraiodothyronine index (FT4I) and free triiodothyronine index (FT3I) in burn patients represented the serum levels of free (dialyzable) T4 and free T3, respectively. FT4I and FT3I were lower with greater burn size and were lower in nonsurvivors than expected for the burn size. there was no compensatory elevation of basal or releasing hormone-stimulated thyrotrophin (TSH) concentrations. Reverse T3 was higher with greater burn size. T3 treatment restored FT3I but did not affect mortality or resting metabolic rate (MR) measured in survivors, compared with placebo therapy. Whereas the hypermetabolic response to burn injury appeared t be independent of thyroid hormones, MR was correlated positively with burn size and with elevated plasma norepinephrine and epinephrine concentrations for several weeks after injury. Lack of augmented TSH concentrations, absence of low plasma reverse T3, and presence of hypermetabolism suggest that the reduced plasma free T3 does not indicate functional hypothyroidism, but may represent an adaptation to the assumption of metabolic control by the sympathetic nervous system.
Asunto(s)
Quemaduras/metabolismo , Tiroxina/metabolismo , Triyodotironina/metabolismo , Adolescente , Adulto , Quemaduras/complicaciones , Femenino , Humanos , Hipotiroidismo/etiología , Masculino , Persona de Mediana Edad , Análisis de RegresiónRESUMEN
Blinding resulted in gonadal and prostatic atrophy and reduced plasma thyroxine (T4), free T4 index (FT4I) and reverse triiodothyronine (rT3) levels in adult male hamsters housed in light-to-dark, 14:10 h. Similar effects were seen after daily evening injections of 25 microgram melatonin. Pinealectomy prevented the effects of blinding or melatonin injections. There were no pineal- or melatonin-induced decrements in T3 or thyrotrophin (TSH) concentrations. TSH was elevated by blinding in one experiment but not in another, despite suppression of T4 and FT4I in both. Orally administered melatonin (approximately 245 microgram daily in drinking water through the evening and night) reduced the weight of testes and prostates and slightly lowered plasma T4 and FT4I, indicating the effectiveness of melatonin by this route. The capability of the pineal and of melatonin to suppress plasma T4 is not a result of sex-steroid-induced alteration of plasma binding but is most likely a result of variable suppression of the pituitary-thyroid axis at the level of TSH regulation and also at the level of T4 secretion and/or metabolism. Reduced rT3, but not T3 levels after blinding, may reflect the pineal-induced deficit in T4 as a substrate for rT3 formation, altered peripheral conversion of T4 or altered disposal of thyroid hormones.