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Modeling of Hypertrophy and Hyperplasia in Porcine Adipose Tissue
Author(s) -
Testroet E,
Sherman P,
Testroet A,
Yoder C,
Lei S,
Reynolds C,
O'Neil M,
Baas T,
Beitz D
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.254.5
Subject(s) - bin , adipose tissue , adipocyte , mathematics , bimodality , medicine , metric (unit) , statistics , combinatorics , endocrinology , biology , physics , algorithm , operations management , economics , quantum mechanics , galaxy
Adipocyte sizes from adult adipose tissue are distributed bimodally. Thus, the standard metric reported, mean cell size, could be misleading. The objectives of this study were to develop a novel method for testing bimodality of adipocytes in porcine adipose tissue, describe the size distribution with a more informative metric, and statistically test hypertrophy and hyperplasia. Testing distribution bimodality was done by describing two bins with bin 1 (adipocytes 25.0 ‐ 40.1 µm in diameter) containing the suspected minor mode and bin 2 (adipocytes 50.2 ‐ 65.4 µm in diameter) containing a region assumed to separate major and minor modes. For the k th cell, we defined the event [ X k = 1] with probability p = Pr[ X k = 1] if that cell's diameter falls in bin 1, and the event [ X k = 0] with probability 1 ‐ p = Pr[ X k = 0] if it falls in bin 2. The following natural estimator of ( p ) was used:Bins 1 and 2 were chosen to have approximately the same width and bin 2 was scaled to match the width of bin 1 so the hypothesis test for distribution bimodality was: H 0 : p = 0.5 versus H 1 : p > 0.5. Because the sample size, N , associated with the number of cells falling in either bin was on average 6,600 adipocytes counted for a given test, the Central Limit Theorem applies and results in the following standard normal test statistic:Increased adiposity is correlated positively with an adipocyte being found in the minor mode ( r = .46) and correlated negatively with an adipocyte being found in the major mode (adipocytes larger than 65.4 µm ( r = ‐.22)), providing evidence of hyperplasia. Additionally, as adiposity increases, the mode of the major distribution of cells occurs at a larger diameter of adipocyte, indicating hypertrophy.