RESUMEN
AIM: Hypocalcaemia evaluation of the clinical, biochemical and radiological features of 91 infants with rickets who presented as hypocalcaemic convulsions. SUBJECTS AND METHODS: Ninety-one hypocalcaemic infants who were brought to hospital with convulsion and diag-nosed with rickets related to vitamin D deficiency according to their clinical, biochemical and radio-logical features were retrospectively reviewed. RESULTS: Mean values of the laboratory data were as follows: calcium 5.55 ± 0.79 mg/dL, phosphorus 4.77 ± 1.66 mg/dL, alkaline phosphatase 1525.5 ± 925.4 U/L and parathormone 256.8 ± 158.3 pg/mL. Serum 25-OH vitamin D levels were below normal (< 20 ng/mL) in 37 infants. CONCLUSION: Vitamin D deficiency should be considered in infants presenting with hypocalcaemia. To avoid complications such as convulsions, clinicians should give vitamin D supplementation to such infants.
OBJETIVO: Evaluación hipocalcémica de los aspectos clínicos, bioquímicos y radiológicos de 91 lactantes con raquitismo, que presentaron convulsiones por hipocalcemia. PACIENTES Y MÉTODOS: Noventa y un lactantes hipocalcémicos llevados al hospital con convulsiones y a quienes se les diagnosticó raquitismo asociado a la deficiencia de vitamina D de acuerdo con sus características, bioquímicas y radiológicas, fueron revisados retrospectivamente. RESULTADOS: Los valores medios de los datos de laboratorio fueron los siguientes: calcio 5.55 ± 0.79 mg/dL, fósforo 4.77 ± 1.66 mg/dL, fosfatasa alcalina 1525.5 ± 925.4 U/L, y paratohormona 256.8± 158.3 pg/mL. Los niveles séricos de la vitamina 25 (OH) D estuvieron por debajo de lo normal en 37 lactantes (< 20 ng/mL). CONCLUSIÓN: La deficiencia de vitamina D debe considerarse en los infantes que se presentan con hipocalcemia. A fin de evitar complicaciones tales como convulsiones, se les debe dar suplementos de vitamina D.
Asunto(s)
Humanos , Masculino , Femenino , Recién Nacido , Lactante , Preescolar , Raquitismo/etiología , Convulsiones/etiología , Deficiencia de Vitamina D/complicaciones , Hipocalcemia/etiología , Hormona Paratiroidea/sangre , Fósforo/sangre , Convulsiones/sangre , Vitamina D/sangre , Biomarcadores/sangre , Calcio/sangre , Estudios Retrospectivos , Fosfatasa Alcalina/sangreRESUMEN
AIM: Hypocalcaemia evaluation of the clinical, biochemical and radiologicalfeatures of 91 infants with rickets who presented as hypocalcaemic convulsions. SUBJECTS AND METHODS: Ninety-one hypocalcaemic infants who were brought to hospital with convulsion and diag-nosed with rickets related to vitamin D deficiency according to their clinical, biochemical and radio-logicalfeatures were retrospectively reviewed. RESULTS: Mean values of the laboratory data were as follows: calcium 5.55 +/- 0.79 mg/dL, phosphorus 4.77 +/- 1.66 mg/dL, alkaline phosphatase 1525.5 +/- 925.4 U/L and parathormone 256.8 +/- 158.3 pg/mL. Serum 25-OH vitamin D levels were below normal (< 20 ng/mL) in 37 infants. CONCLUSION: Vitamin D deficiency should be considered in infants presenting with hypocalcaemia. To avoid complications such as convulsions, clinicians should give vitamin D supplementation to such infants.
Asunto(s)
Hipocalcemia/etiología , Raquitismo/complicaciones , Convulsiones/etiología , Fosfatasa Alcalina/sangre , Calcio/sangre , Preescolar , Femenino , Humanos , Hipocalcemia/sangre , Lactante , Recién Nacido , Masculino , Hormona Paratiroidea/sangre , Fósforo/sangre , Estudios Retrospectivos , Raquitismo/sangre , Convulsiones/sangre , Vitamina D/análogos & derivados , Vitamina D/sangre , Deficiencia de Vitamina D/sangre , Deficiencia de Vitamina D/complicacionesRESUMEN
AIM: After exocytosis, neuroendocrine cells and neurones keep constant the plasma membrane and the releasable vesicle pools by performing endocytosis and vesicular cycling. Patch-clamp capacitance measurements on chromaffin cells showed that strong Ca(+2) entry activates excess retrieval: a rapid endocytosis process that retrieves more membrane than the one fused by preceding exocytosis. The main purpose of the present experiments was to study the recycling pathway that follows excess retrieval, which is unknown. METHODS: Membrane recycling after exocytosis-endocytosis can be studied by fluorescence imaging assays with FM1-43 (Perez Bay et al. Am J Physiol Cell Physiol 2007; 293, C1509). In this work, we used this assay in combination with fluorescent dextrans and specific organelle-targeted antibodies to study the membrane recycling after excess retrieval in mouse chromaffin cells. RESULTS: Excess retrieval was observed after the application of high-K(+) or cholinergic agonists during 15 or 30 s in the presence of FM1-43. We found that the excess retrieval membrane pool (defined as endocytosis-exocytosis) was associated with the generation of a non-releasable fraction of membrane (up to 30% of plasma membrane surface) colocalizing with the lysosomal compartment. The excess retrieval membrane pool followed a saturable cytosolic Ca(2+) dependency, and it was suppressed by inhibitors of L-type Ca(2+) channels, endoplasmic reticulum Ca(2+) release and PKC. CONCLUSION: Excess retrieval is not associated with the cycling of releasable vesicles, but it is related to the formation of non-releasable endosomes. This process is activated by a concerted contribution of Ca(2+) entry through L-channels and Ca(2+) release from endoplasmic reticulum.