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Authors’ Response: Melanin-Concentrating Hormone and Energy Balance

Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Joslin Diabetes Center, and Harvard Medical School Boston, Massachusetts 02215

Address correspondence to: Christos Mantzoros, M.D., D.Sc., FACP, FACE, Clinical Research Overseer, Endocrinology Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Joslin Diabetes Center, Associate Professor of Medicine, Harvard Medical School, ST 816, 330 Brookline Avenue, Boston, Massachusetts 02215. E-mail: cmantzor{at}bidmc.harvard.edu.

To the editor:

I would like to thank Drs. Waters and Krause (1) for pointing out the typographical error in our xpaper (2) related to the sensitivity of the assay used. The sensitivity of the assay is 17 pg/tube, as stated by the manufacturer; and because each tube contains 1 ml, this represents 17 pg/ml. Thus, the levels that we reported are above the assay’s sensitivity and in the linear part of its binding curve. We have checked the assay’s parallelism of standards, and data on cross-reactivity and specificity can be found online at http://www.phoenixpeptide.com/qcdata/RIK/QCK7047.html.

We have not attempted to assay sera from MCH knockout mice because we do not have access to such samples; but even if they contained an immunoreactive substance, as suggested in the letter, it would not necessarily indicate that the antisera is not specific for MCH. It is well known, for example, that sera from ob/ob mice with a certain leptin gene mutation contain an immunoreactive substance (i.e. a truncated leptin molecule) that cross-reacts with specific antisera commonly used to assay mouse leptin levels. Thus, "leptin" appears to be detectable in these ob/ob mice, which are leptin deficient.

I encourage the authors to investigate the questions they raise in their letter, complete relevant experiments with the valuable reagents at their disposal, and report any data supporting their claims.

Received August 5, 2005.

References

1. Waters SM, Krause JE 2005 Letter re: circulating melanin-concentrating hormone, agouti-related protein, and -melanocyte-stimulating hormone levels in relation to body composition: alterations in response to food deprivation and recombinant human leptin administration. J Clin Endocrinol Metab 90:6337
2. Gavrila A, Chan JL, Miller LC, Heist K, Yiannakouris N, Mantzoros CS 2005 Circulating melanin-concentrating hormone, agouti-related protein, and -melanocyte-stimulating hormone levels in relation to body composition: alterations in response to food deprivation and recombinant human leptin administration. J Clin Endocrinol Metab 90:1047–1054[Abstract/Free Full Text]

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