Low serum concentrations of 25-hydroxyvitamin D in children and adolescents with systemic lupus erythematosus

We evaluated the concentrations of 25-hydroxyvitamin D [25(OH)D] in children and adolescents with juvenile systemic lupus erythematosus (JSLE) and associated them with disease duration and activity, use of medication (chloroquine and glucocorticoids), vitamin D intake, calcium and alkaline phosphatase levels, and bone mineral density. Thirty patients with JSLE were evaluated and compared to 30 healthy individuals, who were age and gender matched. Assessment was performed of clinical status, disease activity, anthropometry, laboratory markers, and bone mineral density. The 30 patients included 25 (83.3%) females and 16 (53.3%) Caucasians, with a mean age of 13.7 years. The mean age at diagnosis was 10.5 years and mean disease duration was 3.4 years. Mean levels of calcium, albumin, and alkaline phosphatase were significantly lower in patients with JSLE compared with controls (P<0.001, P=0.006, and P<0.001, respectively). Twenty-nine patients (97%) and 23 controls (77%) had 25(OH)D concentrations lower than 32 ng/mL, with significant differences between them (P<0.001). Fifteen patients (50%) had vitamin D levels <20 ng/mL and 14 had vitamin D levels between 20 and 32 ng/mL. However, these values were not associated with greater disease activity, higher levels of parathormone, medication intake, or bone mineral density. Vitamin D concentrations were similar with regard to ethnic group, body mass index, height for age, and pubertal stage. Significantly more frequently than in controls, we observed insufficient serum concentrations of 25(OH)D in patients with JSLE; however, we did not observe any association with disease activity, higher levels of parathormone, lower levels of alkaline phosphatase, use of medications, or bone mineral density alterations.

Serum 25-hydroxyvitamin D and biochemical markers of bone metabolism in patients with juvenile idiopathic arthritis

Our objective was to evaluate the concentrations of serum 25-hydroxyvitamin D [25(OH)D], serum calcium, serum phosphorus, alkaline phosphatase, and parathormone (PTH) in patients with polyarticular juvenile idiopathic arthritis (JIA) and to associate them with disease duration and activity, bone mineral density and use of medications. In a cross-sectional and controlled study, 30 patients with polyarticular JIA were evaluated and compared to 30 healthy individuals matched for age and gender. Clinical status, anthropometry, laboratory markers in both patients and controls, and bone mineral density, only in the patients, were measured. Of the 30 patients included in the study, 23 (76.7%) were female and 16 (53.3%) non-Caucasian; mean age was 14 years (range = 4 to 20 years). Mean disease duration was 5 years (range = 1 to 12 years). The mean concentrations of serum albumin-corrected calcium (9.04 ± 0.41 mg/dL) and alkaline phosphatase (153.3 ± 100.1 IU) were significantly lower in patients with JIA than in controls (P < 0.0001 and P = 0.001, respectively). No differences in 25(OH)D, PTH or serum phosphorus were observed between JIA and control subjects. Regarding 25(OH)D concentration, 8 patients (26.7%) and 5 controls (16.7%) had 25(OH)D concentrations compatible with deficiency (lower than 20 ng/mL) and 14 patients (46.7%) and 18 controls (60%) had concentrations compatible with insufficiency (20-32 ng/mL). These values were not associated with disease activity, use of medications or bone mineral density. We observed a high frequency of 25(OH)D insufficiency and deficiency in the study sample. The compromised bone metabolism emphasizes the importance of follow-up of JIA patients.

Inmovilización covalente de ß-galactosidasa de A. fonsecaeus sobre sílice aminada / Covalent immobilization on aminated silica of ß-galactosidase from A. fonsecaeus

La ß-galactosidasa semipurificada del A. fonsecaus fue inmovilizada covalentemente sobre sílice aminada activada con glutaraldehído. Se estudió la influencia del área específica del soporte, de la concentración de proteínas y del PH de inmovilización sobre los rendimientos del proceso. Se demostró que el área específica más efectiva fue de 122 m2 (aproximadamente 250A) y que la concentración de proteínas y el PH óptimo de inmovilización fueron de 1,6 g/l y 8,6 respectivamente. La enzima inmovilizada tiene una zona de PH óptimo para la hidrólisis del orto-nitrofenil ß-D-galactopiranósido (ONPG) semejante a la enzima libre. Los resultados obtenidos utilizando la ß-galactosidasa purificada de A. oryzae son comparables a los resultados obtenidos con los preparados semipurificados de ß-galactosidasa de A. fonsecaus. Este estudio crea las premisas para el empleo de la ß-galactosidasa de esta nueva fuente microbiana, en la inmovilización covalente sobre otros soportes utilizables en procesos industriales, para los que las propiedades de esta enzima sean relevantes

Inmovilización covalente de ß-galactosidasa de A. fonsecaeus sobre derivados celulósicos del maíz: comparación con la ß-galactosidasa del A. oryzae / Covalent immobilization on corn cellulose derivative of ß-galactosidase from A. fonsecaeus: comparison with ß-galactosidase from A. oryzae

La ß-galactosidasa del A. fonsecaeus con actividad específica entre 19-24 U/mg, a concentraciones de 1,6-3,3 g/l y PH 8,6 fue inmovilizada covalentemente sobre derivados celulósicos del maíz (DCM), con altos rendimientos (667 U/g de DCM). El mayor porcentaje de enzima inmovilizada y los valores superiores de actividad enzimática por gramo de soporte, se obtuvieron con el empleo de DCM de 0,8 mm. Fueron determinadas algunas características cinéticas de la ß-galactosidasa inmovilizada de A. fonsecaeus y A. oryzae en reactor antidifusional utilizando ortonitrofenil-ß-D-galactopiranósido (ONPG) y lactosa como sustrato. La enzima de A. fonsecaeus presenta valores de Km aparente inferiores a la de A. oryzae en forma inmovilizada, contrario a lo que ocurre en forma libre. La hidrólisis continua de soluciones de lactosa en reactores de columna empacada con DCM ß-galactosidasa de ambos microorganismos, produjo resultados similares y comparables a los obtenidos en otros sistemas reportados. La enzima inmovilizada del A. fonsecaeus fue muy estable; los tiempos de vida media a 35-C y 50-C, fueron de 240 y 80 días respectivamente. La enzima inmovilizada puede ser empleada para la hidrólisis continua de la lactosa del suero lácteo a 50-C y PH 4,5 con una productividad de 0,9 g de lactosa/g de DCM-enzima/hora.