Publications

The underlying mutations that cause human limb malformations are often difficult to determine, particularly for limb malformations that occur as isolated traits. Evidence from a variety of studies shows that cis-regulatory mutations, specifically in enhancers, can lead to some of these isolated limb malformations. Here, we provide a review of human limb malformations that have been shown to be caused by enhancer mutations and propose that cis-regulatory mutations will continue to be identified as the cause of additional human malformations as our understanding of regulatory sequences improves.

Although spiral trajectories have multiple attractive features such as their isotropic resolution, acquisition efficiency, and robustness to motion, there has been limited application of these techniques to first-pass perfusion imaging because of potential off-resonance and inconsistent data artifacts. Spiral trajectories may also be less sensitive to dark-rim artifacts that are caused, at least in part, by cardiac motion. By careful consideration of the spiral trajectory readout duration, flip angle strategy, and image reconstruction strategy, spiral artifacts can be abated to create high-quality first-pass myocardial perfusion images with high signal-to-noise ratio. The goal of this article was to design interleaved spiral pulse sequences for first-pass myocardial perfusion imaging and to evaluate them clinically for image quality and the presence of dark-rim, blurring, and dropout artifacts.

Lipid accumulation in the heart is associated with obesity and diabetes mellitus and may play an important role in the pathogenesis of heart failure seen in this patient population. Stored triglycerides are synthesized by the enzyme diacylglycerol acyl transferase (DGAT). We hypothesized that forced expression of DGAT1 in the cardiac myocyte would result in increased lipid accumulation and heart dysfunction. A cardiac myocyte-selective DGAT1 transgenic mouse was created and demonstrated increased lipid accumulation in the absence of hyperglycemia, plasma dyslipidemia or differences in body weight. Over time, expression of DGAT1 in the heart resulted in the development of a significant cardiomyopathy. Echocardiography revealed diastolic dysfunction with increased early mitral inflow velocity to late mitral inflow velocity ratio and decreased deceleration time, suggesting a restrictive pattern in the transgenic mice. Moderate systolic dysfunction was also seen at 52 weeks. Histological analysis showed increased cardiac fibrosis and increased expression of procollagen type 1A, matrix metalloproteinase 2, and tissue inhibitor of matrix metalloproteinase 2 in the transgenic mice. Mitochondrial biogenesis was reduced in the transgenic hearts, as was expression of cytochrome c oxidase 1 and cytochrome c. Expression of key transcription factors important in the regulation of mitochondrial biogenesis were reduced. These findings suggest that triglyceride accumulation, in the absence of systemic metabolic derangement, results in cardiac dysfunction and decreased mitochondrial biogenesis.