Predictors of a positive oral food challenge to cow's milk in children sensitized to cow's milk

INTRODUCTION AND OBJECTIVES: The diagnosis of IgE-mediated cow's milk allergy (CMA) is often based on clinical history and on specific IgE levels and/or skin-prick tests (SPT), both of which are sensitive but not specific. The gold standard, oral food challenge (OFC), is expensive and time-consuming and involves a risk of severe allergic reactions. This study aimed to determine the value of specific IgEs, ratios of specific IgEs for cow's milk and its components to total IgE, and wheal size on SPT for predicting a positive OFC for CMA. MATERIAL AND METHODS: We retrospectively studied 72 patients [median age, four years; age range 0.75-15 years] sensitized to cow's milk who underwent OFCs to milk. predictive variables between patients with positive and negative OFCs were compared. Receiver operator characteristic (ROC) curves were uses to assess variables' discriminatory capacity and Youden's index to determine the best cut-offs for predicting CMA. RESULTS: The OFC was positive in 39 (54%) patients. Wheal size on SPT and all specific IgEs and specific-to-total IgE ratios were significantly different between patients with positive OFCs and those with negative OFCs (p < 0.001). The variable with the greatest area under the ROC curve was casein-specific IgE (0.98), followed by β-lactoglobulin-specific IgE (0.923), casein-specific-to-total-IgE ratio (0.919), and α-lactalbumin-specific IgE (0.908). Casein-specific IgE ≥ 0.95kU/L yielded 88.9% sensitivity and 90.9% specificity. CONCLUSIONS: In our center, casein-specific IgE > 0.95kU/L can obviate an OFC to cow's milk for the diagnosis of CMA in patients sensitized to cow's milk with a compatible history

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Hepatic phenylalanine-hydroxylase and tyrosine-aminotransferase mRNA levels in rats adapted to diets with different concentrations of protein

Se estudió el efecto de la concentración de la proteína de la dieta sobre concentraciones de ARNm de la tirosina aminotransferasa (TAT) y la fenilalanina hidroxilasa (PAH) hepáticas en ratas adaptadas a consumir dietas con 18 ó 50 por ciento de caseína en un horario restringido de 7 horas (9 a 16 h) durante 5 días. Las concentraciones de ARNm de TAT de ratas adaptadas a una dieta de 18 por ciento de caseína y alimentadas en forma aguda con dietas que contenían 6, 18 ó 50 por ciento de caseína, fueron 0.15, 0.84 y 5.08 veces más altas a las 6 horas en comparación con las concentraciones de ARNm antes de la administración de la dieta. Las concentraciones de ARNm de TAT después de 17 horas de ayuno en las ratas alimentadas con 6, 18 ó 50 por ciento de caseína fueron respectivamente -0.45, 1.76 y 9.11 veces mayores en comparación con el valor basal. Las concentraciones ARNm de PAH mostraron un patrón similar; en las ratas adaptadas a 18 por ciento de caseína se observó un aumento de -.68, 1.63 y 2.5 veces en las concentraciones de ARNm de PAH en las ratas alimentadas en forma aguda con 6, 18 y 50 por ciento de casína respectivmanete y un aumento de -0.86, 2.32 y 9.33 veces después de 17 horas de ayuno. La concentraciones de ARNm de TAT y PAH en ratas adaptadas a consumir 50 por ciento de caseína y luego alimentadas con 6 ó 50 por ciento de caseína mostraron un pico máximo a las 6 horas de ayuno. Estos resultados sugieren que las concentraciones crecientes de proteína en la dieta son capaces de producir aumentos en la concentración de los ARNm de las dos enzimas, posiblemente para eliminar el exceso de aminoácidos consumidos, ya que la concentración de los ARNm dependió más del contenido de proteína de la dieta de adaptación

Differential effects of protein restriction on gamma-glutamyltranspeptidase [EC 2.3.2.2] activity in young and mature rats

Gamma-glutamyltranspeptidase (GGT, EC 2.3.2.2) activity was determined in the plasma and liver of 40 young (50 days old) and 40 mature (300 days old) male Wistar rats, after a protein restriction period of 28 days. Casein protein levels used were: 1 percent, 3 percent, 5 percent, 7 percent and 28 percent (control). Weanling rats submitted to protein-free diet and adult rats submitted to that and other low-protein diets (1 percent, 3 percent or 5 percent casein) presented weight reductions (-0.38 +/- 0.07 g/day and -0.98 +/- 0.19 g/day, respectively). Only in young animals did these weight reductions parallel those of food consumption (37 +/- 12 percent of control), plasma protein (52 +/- 11 percent of control), plasma albumin (70 +/- 12 percent of control), hepatic RNA (68 +/- 7 percent of control) and protein (71 +/- 8 percent of control). A marked effect of the protein restriction, increasing the GGT activity, was also observed only in young rats. A significant (P<0.05) rise was promoted by the protein-free diet in the plasma GGT (2.83 +/- 1.39 vs 0.69 +/- 0.50 mU/ml for control) and by both the protein-free and 3 percent casein diets, in the liver GGT (respectively, 16.00 +/- 6.72 and 7.75 +/- 3.49 vs 0.94 +/- 0.57 U/g protein for control). The different results obtained for young in relation to mature animals could be explained by the reduction of both protein and sulfur-containing amino acid requirements with aging.

Determinaçäo dos valores normais de alfa-1-antitripsina no soro humano / Determination of normal values of alpha-1-antitrypsin in human serum

A alfa-1-antitripsina é uma anti-proteose responsável por aproximadamente 90% da inibiçäo sérica, sendo importante a sua determinaçäo tanto nos casos de deficiência genética como do aumento em processos neoplásicos, inflamatórios e infecciosos. No presente trabalho estuda-se uma metodologia adaptada às condiçöes de nosso país, utilizando reagentes acessíveis com obtençäo de resultados satisfatórios de 1,33 + ou - 0,24mg de tripsina inibidos por ml ou 306 + ou - 55 mg% de alfa-1-antitripsina, em indivíduos normais, concordantes com a maior parte dos investigadores neste campo de trabalho