“Quantification of endogenous retinoic acid in limited biological samples by LC/MS/MS” by Kane MA, Chen N, Sparks, S et al. Biochem J 2005; 388: 363–369 (Univ Calif Berkeley, Dept Nutr Sci & Toxicol, Berkeley, CA 94720, USA. E-mail: firstname.lastname@example.org) This reports a sensitive assay to quantify RA (retinoic acid) which is applicable to biological samples of limited size (10–20 mg of tissue wet weight). Details of the method are provided. By this technique the first analytically robust quantification of all-trans-RA in animal brain and in CRBP-null mice was provided. Direct measurements of endogenous RA are made possible. “Morphology of ferret subcutaneous tissue after 6-month daily supplementation with oral β-carotene” by Murano I, Morroni M, Zingaretti I et al. Biochim Biophys Acta – Mol Basis Dis 2005; 1740: 305–312 (Univ Ancona, 1st Mortol Umana Normale, Ancona, Italy. Email: email@example.com) Adipose tissue is an important retinoid depot. Retinoids are known to affect the biological activity of white and brown adipocyte metabolism. Two dosing regimes were used: 0.8 or 3.2 mg/kg/day. The higher dosing induced significantly higher body weight and significantly higher inguinal fat. There was a dosedependent hypertrophy of white adipocytes and increased neoangioneogenesis in subcutaneous white adipose tissue. Focal areas of liver steatosis occurred in animals given the higher dose. “Cellular RBP type 111 is needed for retinoid incorporation into milk” by Piantedosi R, Ghyselinck N, Blaner WS et al. J Biol Chem 2005; 280: 24286–24292 (Columbia Univ, Div Prev Med & Nutr, Dept Med, Coll Phys & Surg, 630 W 168th St P&S 9–510, New York, NY 10032, USA. E-mail: firstname.lastname@example.org) CRBP-111 is an intracellularretinol binding protein expressed solely in heart, muscle, adipose and mammary tissue. Mice lacking CRBP-111 were generated. They were viable but showed impaired incorporation of retinoids into milk. Milk contained less retiny lester, especially retinyl palmitate. It was shown that diminished milk retinyl ester levels arise from impaired utilization of retinol by lecithin-retinol-acyltransferase in CRBP-111-/- mice. It was also shown that CRBP-1 and CRBP-111 share some physiological actions and can each compensate for the absence of the other to help maintain retinoid homeostasis. Under conditions of high demand, as during lactation, this compensation is incomplete.
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