RESUMEN
A method for measuring the retention of orally administered 47Ca using a whole-body counter (WBC) is described. One microcurie 47Ca in 90 ml of lowfat milk was given along with 5 microCi 51Cr as a stool marker. The retention of 47Ca was determined at 7 days if less than 2% of the administered 51Cr was present in the body. Correlation between calcium retention by the whole-body-counting and the excreta-recovery methods was highly significant (r = 0.835, P less than 0.0001; N = 17). In 5 subjects, each studied twice while on constant self-selected diets, calcium retention was measured by the WBC method with a precision (standard deviation) of +/- 2.6% of the administered dose or +/- 13.9% of the mean retained fraction. Whole-body measurement of 47Ca retention has the advantages over other techniques that no collections of blood or stool are needed, no residency on a metabolic ward is required, and the radiation exposure (13 mrem) is so low that multiple studies may be performed in the same subject.
Asunto(s)
Radioisótopos de Calcio , Calcio/farmacocinética , Recuento Corporal Total/métodos , Absorción , Administración Oral , Adulto , Anciano , Calcio/metabolismo , Femenino , Humanos , Tasa de Depuración Metabólica , Persona de Mediana EdadRESUMEN
The effect of chronic inflammation, corticosteroid therapy, and nutritional supplementation on whole body protein metabolism and growth was determined in adolescent males with Crohn disease and growth failure. Body protein status was characterized in six patients and in five healthy, age-matched controls by nitrogen balance, whole body potassium (measured as 40K), urinary creatinine excretion, and [15N]glycine turnover studies. The patients subsequently received an intragastric nutritional supplement that increased dietary protein and energy intakes by 40% for seven months. Follow-up anthropometric measurements were obtained in both groups of adolescents. Our results demonstrated that lean body mass (40K) and muscle mass (creatinine) were significantly reduced in the patients compared to the controls, despite similar nitrogen balances between both groups. Whole body nitrogen flux, rates of protein synthesis and breakdown, and net protein retention were no different between those patients with chronic inflammation, while receiving corticosteroid therapy, and their controls. Long-term nutritional supplementation significantly improved linear and ponderal growth velocities in the patients such that growth rates were commensurate with those of the healthy controls. We conclude that chronic inflammation and corticosteroid therapy are not associated with detectable alterations in protein metabolic processes at the whole body level. Rather, dietary insufficiency appears to be primarily responsible for growth failure in adolescents with Crohn disease.
Asunto(s)
Enfermedad de Crohn/metabolismo , Trastornos del Crecimiento/metabolismo , Proteínas/metabolismo , Adolescente , Corticoesteroides/uso terapéutico , Niño , Enfermedad de Crohn/complicaciones , Enfermedad de Crohn/dietoterapia , Enfermedad de Crohn/tratamiento farmacológico , Proteínas en la Dieta/administración & dosificación , Ingestión de Energía , Nutrición Enteral , Trastornos del Crecimiento/etiología , Humanos , Masculino , Nitrógeno/metabolismoRESUMEN
The adaptive response of whole body leucine metabolism to nutritional supplementation was determined in 6 adolescents with Crohn's disease and growth failure. Five healthy adolescents served as controls for body composition studies. In the first study period, all subjects received a constant diet comparable to usual intakes. In the second period, the patients were given overnight intragastric supplemental feedings that increased dietary protein and energy intakes approximately 40% (to 3.2 g/kg . day and 96 kcal/kg . day, respectively). During each dietary period, O2 consumption, nitrogen balance, whole body potassium (40K), and urinary creatinine measurements were obtained on all adolescents, and the patients received a primed, constant, intravenous infusion of [13C]leucine for 4 h in the fed state. Plasma leucine and expired carbon dioxide 13C-enrichments were determined by mass spectrometric techniques. In the first study, O2 consumption and nitrogen balances were similar between groups; in patients, 40K and urinary creatinine were reduced by 30% and 36%, respectively. With nutritional supplementation, nitrogen balance increased fourfold; O2 consumption and 40K increased by 32% and 10%, respectively. Similarly, whole body leucine flux increased from 166.9 +/- 5.9 to 201.3 +/- 11.2 mumol/kg . h (p less than 0.05) due to a 66% increase in leucine incorporation into body protein (p less than 0.01) and a 41% decrease in leucine oxidation (p less than 0.05). Thus, these studies demonstrate that the mechanisms responsible for lean body mass accretion during nutritional supplementation in adolescents with Crohn's disease and growth failure are increased rates of amino acid incorporation into body protein (via protein synthesis) and decreased rates of amino acid oxidation.
Asunto(s)
Enfermedad de Crohn/metabolismo , Dieta , Proteínas en la Dieta/administración & dosificación , Ingestión de Energía , Trastornos del Crecimiento/etiología , Leucina/metabolismo , Adolescente , Estatura , Peso Corporal , Niño , Enfermedad de Crohn/complicaciones , Enfermedad de Crohn/diagnóstico , Nutrición Enteral , Femenino , Alimentos Formulados , Humanos , MasculinoAsunto(s)
Peso Corporal , Obesidad/terapia , Tejido Adiposo , Adulto , Composición Corporal , Creatinina/orina , Femenino , Humanos , Masculino , Persona de Mediana Edad , Periodo PosoperatorioRESUMEN
We have developed a simple novel column technique for the removal of sodium-24 and potassium-42 based on a heterogeneous isotopic exchange reaction between an organic eluting solution (acetone-hydrochloric acid) and fine crystals of sodium chloride or potassium chloride or their analogs. The technique is fast, efficient, and highly selective; it has been successfully applied to irradiated human tissues prior to gamma-ray spectrometry with lithium-drifted germanium detectors.