OBJECTIVES 1,25-Dihydroxycholecalciferol (calcitriol, vitamin D3) has immunosuppressive properties. This study evaluates the effect of calcitriol in combination with either cyclosporine A or tacrolimus on acute lung allograft rejection in a rat model of unilateral left lung allotransplantation. METHODS Unilateral left lung transplantation was performed in male rats (Brown-Norway to Fischer F3...

BACKGROUND Asthma severity and eosinophilia correlate with a deficiency in vitamin D and its active metabolite calcitriol. Calcitriol modulates numerous leukocyte functions, but its effect on eosinophils is not fully understood. We postulated that calcitriol exerts a direct effect on eosinophil biology by modulating cell survival. METHODS Purified peripheral blood eosinophils from atopic dono...

BACKGROUND Pseudo-vitamin D deficiency rickets (PDDR; OMIM 264700) is a rare autosomal recessive disorder caused by mutations in the CYP27B1 gene, leading to an inability to synthesize 1α,25-dihydroxyvitamin D(3) (calcitriol). The long-term (>1 yr) effects of calcitriol replacement treatment have not been reported. MATERIALS AND METHODS Thirty-nine patients (20 females) with PDDR received cal...

1, 25-Dihydroxycholechalciferol (calcitriol) and 19-nor-1, 25-dihydroxyvitamin D2 (paricalcitol) are vitamin D receptor (VDR) agonists. Previous data suggest VDR agonists may actually increase renin-angiotensin activity, and this has always been assumed to be mediated by hypercalcemia. We hypothesized that calcitriol and paricalcitol would increase plasma renin activity (PRA) independently of p...

Atchison DK, Harding P, Beierwaltes WH. Vitamin D increases plasma renin activity independently of plasma Ca via hypovolemia and -adrenergic activity. Am J Physiol Renal Physiol 305: F1109 –F1117, 2013. First published August 7, 2013; doi:10.1152/ajprenal.00010.2013.—1, 25-Dihydroxycholechalciferol (calcitriol) and 19-nor-1, 25-dihydroxyvitamin D2 (paricalcitol) are vitamin D receptor (VDR) ago...

Calcitriol (1,25-dihydroxyvitamin D(3)) inhibits the growth and stimulates the differentiation of prostate cancer (PCa) cells. The effects of calcitriol are varied, appear to be cell-specific and result in growth arrest and stimulation of apoptosis. Our goal was to define the genes involved in the multiple pathways mediating the anti-proliferative effects of calcitriol in PCa. We used cDNA micr...

Accumulation of aluminum in bone is a frequent finding in patients requiring chronic dialysis and is associated with considerable morbidity and/or mortality. Until now, evidence seemed to point to relatively low circulating levels of parathyroid hormone as a contributing factor, but because levels of parathyroid hormone and calcitriol are interrelated, calcitriol might be also involved. In this...

In mammals, phosphocalcic and bone metabolisms are mainly regulated by parathyroid hormone, parathyroid hormone-related peptide (PTHrP) and 1α,25-dihydroxyvitamin D or calcitriol. In camels, circulating levels of calcitriol are 10 times higher than those determined in other ruminants and further increase during early lactation. Calcitriol and parathyroid-related peptide stimulate intestinal abs...

Several inflammatory mediators increase calcitriol production by epidermal keratinocytes. In turn calcitriol attenuates the keratinocyte inflammatory response. Since the effect of the in-situ generated calcitriol depends also on the sensitivity to the hormone we studied the effect of inflammatory cytokines on the response of HaCaT human keratinocytes to calcitriol by examining the expression an...

We have previously reported that in tumorigenic pancreatic beta-cells, calcitriol exerts a potent antitumorigenic effect by inducing apoptosis, cell growth inhibition, and reduction of solid beta-cell tumors. Here we have studied the molecular pathways involved in the antineoplastic activity of calcitriol on mouse insulinoma beta TC(3) cells, mouse insulinoma beta TC expressing or not expressin...