doi:10.1093/brain/awy119 BRAIN 2018: 141; 1 | e52 LETTER TOTHE EDITOR Reply: Measurement of regional rates of protein synthesis in human brain in vivo with L-[1- C]-leucine PET Joey S. J. Smeets and Luc J. C. van Loon Department of Human Biology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands Correspondence to: Joey S. J. Smeets Maastricht University Medical Centre + P.O. Box 616, 6200 MD Maastricht, The Netherlands E-mail: email@example.com and PET: methods, model, and results in animals and humans. J Cereb Sir, Blood Flow Metab 1989; 9: 446–60. We are pleased that researchers in the ﬁeld of brain me- Libby WF, Berger R, Mead JF, Alexander GV, Ross JF. Replacement tabolism have taken notice of our work (Smith and Schmidt, rates for human tissue from atmospheric radiocarbon. Science 1964; 2018). As described in our introduction, we acknowledge 146: 1170–2. the work using atmospheric tracer incorporation (Libby Schmidt KC, Cook MP, Qin M, Kang J, Burlin TV, Smith CB. et al., 1964) as well as the L-[1- C]-leucine PET method Measurement of regional rates of cerebral protein synthesis with L-[1-11C]leucine and PET with correction for recycling of tissue (Hawkins et al., 1989; Sundaram et al., 2006) to estimate amino acids: I. Kinetic modeling approach. J Cereb Blood Flow brain protein synthesis rates. Though the latter method has Metab 2005; 25: 617–28. been further developed by Dr Smith and Ms Schmidt and Smeets JSJ, Horstman AMH, Schijns OEMG, Dings JTA, Hoogland validated against autoradiographic methods in rhesus mon- G, Gijsen AP, et al. Brain tissue plasticity: protein synthesis rates of keys (Schmidt et al., 2005; Smith et al., 2005), no studies the human brain. Brain 2018; 141: 1122–29. Smith CB and Schmidt KC. Measurement of regional rates of protein have directly assessed incorporation of labelled amino acids synthesis in human brain in vivo with L-[1- C]-leucine PET. Brain in brain tissue protein in vivo in humans. In our study we 2018; 141: e51. applied contemporary stable isotope methodology with con- Smith CB, Schmidt KC, Qin M, Burlin TV, Cook MP, Kang J, et al. tinuous tracer infusion and blood and tissue sampling to Measurement of regional rates of cerebral protein synthesis with L- directly assess fractional brain protein synthesis rates [1-11C]leucine and PET with correction for recycling of tissue in vivo in humans (Smeets et al., 2018). The main limitation amino acids: II. Validation in rhesus monkeys. J Cereb Blood Flow Metab 2005; 25: 629–40. of this direct method is indeed the need for tissue sampling. Sundaram SK, Muzik O, Chugani DC, Mu F, Mangner TJ, Chugani As such, non-invasive methods as referred to by Dr Smith HT. Quantiﬁcation of protein synthesis in the human brain using L- and Ms Schmidt will be required to elucidate many aspects [1-11C]-leucine PET: incorporation of factors for large neutral of brain protein synthesis rates in both health and disease. amino acids in plasma and for amino acids recycled from tissue. J Nucl Med 2006; 47: 1787–95. References Hawkins RA, Huang SC, Barrio JR,Keen RE,FengD, Mazziotta JC,et al. Estimation of local cerebral protein synthesis rates with L-[1-11C]leucine Advance Access publication May 3, 2018 The Author(s) (2018). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please email: firstname.lastname@example.org Downloaded from https://academic.oup.com/brain/article-abstract/141/7/e52/4992171 by Ed 'DeepDyve' Gillespie user on 03 July 2018
Brain – Oxford University Press
Published: May 3, 2018
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