11 research outputs found
Sex Differences in Body Composition But Not Neuromuscular Function Following Long-Term, Doxycycline-induced Reduction in Circulating Levels of Myostatin in Mice
© 2019 Tavoian et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Age-related declines in muscle function result from changes in muscle structure and contractile properties, as well as from neural adaptations. Blocking myostatin to drive muscle growth is one potential therapeutic approach. While the effects of myostatin depletion on muscle characteristics are well established, we have very little understanding of its effects on the neural system. Here we assess the effects of long-term, post-developmental myostatin reduction on electrophysiological motor unit characteristics and body composition in aging mice. We used male (N = 21) and female (N = 26) mice containing a tetracycline-inducible system to delete the myostatin gene in skeletal muscle. Starting at 12 months of age, half of the mice were administered doxycycline (tetracycline) through their chow for one year. During that time we measured food intake, body composition, and hindlimb electromyographic responses. Doxycycline-induced myostatin reduction had no effect on motor unit properties for either sex, though significant age-dependent declines in motor unit number occurred in all mice. However, treatment with doxycycline induced different changes in body composition between sexes. All female mice increased in total, lean and fat mass, but doxycycline-treated female mice experienced a significantly larger increase in lean mass than controls. All male mice also increased total and lean mass, but administration of doxycycline had no effect. Additionally, doxycycline-treated male mice maintained their fat mass at baseline levels, while the control group experienced a significant increase from baseline and compared to the doxycycline treated group. Our results show that long-term administration of doxycycline results in body composition adaptations that are distinctive between male and female mice, and that the effects of myostatin reduction are most pronounced during the first three months of treatment. We also report that age-related changes in motor unit number are not offset by reduced myostatin levels, despite increased lean mass exhibited by female mice
Combining Spectral Amplitude and Phase Improves Terahertz Hyperspectral Imaging
We developed a method to analyze
sample composition via hyperspectral
imaging with terahertz time-domain spectroscopy (THz-TDS). Historically,
THz spectral amplitude data alone have been most often used for hyperspectral
analysis. We show advantages of simultaneously using both the amplitude
and phase angle components of the THz transmission data in the analysis.
Use of the complex transmission data improves the integrity of the
sample component differentiation with respect to the sample composition.
We incorporate principal component analysis and other simple machine
learning algorithms into our data analysis methodology to automate
the process of interpreting hyperspectral data and isolating unique
components. As a demonstration, we automatically distinguish the structure
of both a split-ring resonator and a sugar pellet sample