Efeito combinado do ácido zoledrônico e do alfacalcidol no tratamento da osteoporose por desuso em ratos / Additive effect of zoledronic acid and alfacalcidol in the treatment of disuse osteoporosis in rats

Objetivos: O desuso pelo repouso no leito, pela imobilização de membros ou por missões espaciais provoca a perda óssea rápida. Fez-se este estudo para investigar os efeitos terapêuticos do ácido zoledrônico (ZOL), isoladamente e em combinação ao alfacalcidol (ALF), em um modelo de rato com osteoporose por desuso. Métodos: Ratos Wistar machos de três meses foram submetidos à imobilização da pata traseira direita (IPTD) por 10 semanas para induzir a osteopenia; em seguida, foram divididos em quatro grupos: 1 – IPTD para controle positivo; 2 – IPTD mais ZOL (50 µg/kg, dose única intravenosa); 3 – IPTD mais ALF (0,5 µg/kg, via oral diariamente); 4 – IPTD mais ALF (0,5 µg/kg, via oral diariamente) mais ZOL (50 µg/kg, dose única intravenosa) por outras 10 semanas. Um grupo de ratos não imobilizados foi usado como controle negativo. No fim do tratamento, os fêmures foram removidos e testaram-se a porosidade do osso e suas propriedades mecânicas, além do peso seco e das cinzas do osso. Resultados: A terapia combinada com ZOL mais ALF foi mais eficaz em reduzir a porosidade do osso do que a monoterapia com um dos fármacos administrado isoladamente em ratos submetidos à IPTD. No que diz respeito à melhoria da resistência mecânica da diáfise femoral média, o tratamento combinado com ZOL mais ALF foi mais eficaz do que a monoterapia com um dos fármacos administrado isoladamente. Além disso, a terapia combinada com ZOL mais ALF foi mais eficaz na melhoria do peso seco e das cinzas do osso do que a monoterapia com ZOL ou ALF em ratos submetidos à IPTD. Conclusões: Esses dados sugerem que a terapia combinada com ZOL mais ALF representa uma opção terapêutica potencialmente útil para o tratamento da osteoporose por desuso. .

Objectives: Disuse by bed rest, limb immobilization or space flight causes rapid bone loss. We conducted the present study to investigate the therapeutic effects of zoledronic acid (ZOL), alone and in combination with alfacalcidol (ALF) in a rat model of disuse osteoporosis. Methods: In the present study, 3-month-old male Wistar rats had their right hind-limb immobilized (RHLI) for 10 weeks to induce osteopenia, then were divided into four groups: 1 – RHLI positive control; 2 – RHLI plus ZOL (50 µg/kg, i.v. single dose); 3 – RHLI plus ALF (0.5 µg/kg, oral gauge daily); 4 – RHLI plus ALF (0.5 µg/kg, oral gauge daily) plus ZOL (50 µg/kg, i.v. single dose) for another 10 weeks. One group of non-immobilized rats was used as negative control. At the end of the treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and bone dry and ash weight. Results: Combination therapy with ZOL plus ALF was more effective in decreasing bone porosity than each drug administered as monotherapy in RHLI rats. With respect to improvement in the mechanical strength of the femoral mid-shaft, the combination treatment of ZOL plus ALF was more effective than each drug administered as a monotherapy. Moreover, combination therapy using ZOL plus ALF was more effective in improving dry bone and ash weight, than single-drug therapy using ZOL or ALF in RHLI rats. Conclusions: These data suggest that combination therapy with ZOL plus ALF represents a potentially useful therapeutic option for the treatment of disuse osteoporosis. .

Autosomal Dominant Hypocalcemia Caused by an Activating Mutation of the Calcium-Sensing Receptor Gene: The First Case Report in Korea

Hypoparathyroidism is an abnormality of calcium metabolism characterized by low serum levels of parathyroid hormone in spite of hypocalcemia. The causes of hypoparathyroidism are numerous. Activating mutations in the calcium-sensing receptor (CaSR) gene are well-known causes of familial isolated hypoparathyroidism, also known as autosomal dominant hypocalcemia (ADH). Here we describe members of a Korean family with a heterozygous Pro221Leu mutation causing ADH. This case is the first report in Korea.

Calcium imbalance in hypoparathyroidism.

Extracellular fluid calcium is a tightly controlled variable. Hypoparathyroid state may result in profound calcium imbalance and moderate to severe hypocalcaemia. During 1974-89, 108 cases of hypoparathyroidism (97 post-surgical and 11 idiopathic) were seen. In the post-thyroidectomy group, 83 cases (85%) presented with acute transient hypocalcaemia with spontaneous recovery within 7-10 days. Chronic hypoparathyroidism was seen in 25 cases (14 post-surgical and 11 idiopathic). Convulsions resembling epileptic fits were seen in 9 cases (36%). Pseudopapilloedema was seen in three cases presenting with fits. The administration of phenobarbitone and dilantin aggravated convulsions in 9 patients. The other manifestations were psychiatric illness, cataract and calcification of basal ganglion. Biochemical findings included persistent hypocalcaemia with normal or raised serum phosphorus and lowered daily urinary excretion of calcium. Twenty three of 25 chronic hypoparathyroid cases were treated with vitamin D3 (1-3 mg/day) and calcium supplements (600-1000 mg/day)while 1 alfa-calcidol or calcitriol was used in two patients. Four patients receiving treatment with vitamin D3 developed transient hypercalcaemia with raised plasma levels of 25 hydroxy-vitamin D3. They responded to a reduction in dosage of vitamin D3. One patient was later changed over to 1-alfa-calcidol and another to calcitriol.

Niveles séricos de 25-hidroxi-vitamina D en la población normal de Buenos Aires: su variación estacional / Serum levels of 25-hydroxyvitamin D in the normal population of Buenos Aires: its seasonal variation

Los niveles plasmáticos de 25(-)hidroxivitamina D (25(OH)D), son representativos del nivel endogéno de vitamina D y provienen de la síntesis en piel de esta vitamina durante la exposición a los rayos solares y, en menor medida, de su aporte nutricional. Se ha desarrollado un método para la cuantificación de 25(OH)D sérico, que consta de una primera purificación por elución en columnas de Sephadex LH 20 y una posterior cuantificación por ensayo de competición proteica. Los niveles séricos de 25(OH)D en 30 hombres y mujeres normales de la población de Buenos Aires, no muestran diferencias entre sexos y presentan un nivel promedio de 20,7ñ1,9ng/ml (xñ1ES). No se encontró correlacicón entre los niveles séricos de 25(OH)D, Ca, P y PTH. En 12 sujetos normales que fueron estudiados secuencialmente en invierno y verano, los valores de 25(OH)D sérico fueron de 18,7ñ1,7 y 23,5ñ1,9ng/ml, respectivamente (p<0,01). En diversas patologías fue posible detectar niveles de 25 (OH)D disminuidos o elevados en relación a los valores normales, demonstrando la utilidad de la medición para efectuar diagnósticos diferenciales. Los niveles normales de 25(OH)D sérico en la población de Buenos Aires fueron comparables a los encontrados en países con alta exposición solar, indicando que no existe en la población estudiada una deficiencia subclínica de vitamina D