[Multicenter Survey on Phantom Entrance Surface Air Kerma of Angiography and IVR in Japan].

Purpose: In DRLs 2020, the entrance surface air kerma (Ka,e) was set to 17 mGy/min as the reference dose rate in fluoroscopy. But, Ka,e in fluoroscopy for different regions and Ka,e in exposure was not set. A multicenter survey was conducted to evaluate Ka,e by each area.

Syntheses of 25-Adamantyl-25-alkyl-2-methylidene-1α,25-dihydroxyvitamin D Derivatives with Structure-Function Studies of Antagonistic and Agonistic Active Vitamin D Analogs.

The active form of vitamin D, 1α,25-dihydroxyvitamin D [1,25(OH)D], is a major regulator of calcium homeostasis through activation of the vitamin D receptor (VDR). We have previously synthesized vitamin D derivatives with large adamantane (AD) rings at position 24, 25, or 26 of the side chain to study VDR agonist and/or antagonist properties. One of them-ADTK1, with an AD ring and 23,24-triple bond-shows a high VDR affinity and cell-selective VDR activity.

Combination of triple bond and adamantane ring on the vitamin D side chain produced partial agonists for vitamin D receptor.

Vitamin D receptor (VDR) ligands are therapeutic agents that are used for the treatment of psoriasis, osteoporosis, and secondary hyperparathyroidism and have immense potential as therapeutic agents for autoimmune diseases, cancers, and cardiovascular diseases. However, the major side effect of VDR ligands, the development of hypercalcemia, limits their expanded use. To develop tissue-selective VDR modulators, we have designed vitamin D analogues with an adamantane ring at the side chain terminal, which would interfere with helix 12, the activation function 2, and modulate the VDR potency.