Image-based Quantification of 3D Morphology for Bifurcations in the Left Coronary Artery: Application to Stent Design

Background Improved strategies for stent‐based treatment of coronary artery disease at bifurcations require a greater understanding of artery morphology. Objective We developed a workflow to quantify morphology in the left main coronary (LMCA), left anterior descending (LAD), and left circumflex (LCX) artery bifurcations. Methods Computational models of each bifurcation were created for 55 patients using computed tomography images in 3D segmentation software. Metrics including cross‐sectional area, length, eccentricity, taper, curvature, planarity, branching law parameters, and bifurcation angles were assessed using open‐sources software and custom applications. Geometric characterization was performed by comparison of means, correlation, and linear discriminant analysis (LDA). Results Differences between metrics suggest dedicated or multistent approaches should be tailored for each bifurcation. For example, the side branch of the LCX (i.e., obtuse marginal; OM) was longer than that of the LMCA (i.e., LCXprox) and LAD (i.e., first diagonal; D1). Bifurcation metrics for some locations (e.g., LMCA Finet ratio) provide results and confidence intervals agreeing with prior findings, while revised metric values are presented for others (e.g., LAD and LCX). LDA revealed several metrics that differentiate between artery locations (e.g., LMCA vs. D1, LMCA vs. OM, LADprox vs. D1, and LCXprox vs. D1). Conclusions These results provide a foundation for elucidating common parameters from healthy coronary arteries and could be leveraged in the future for treating diseased arteries. Collectively the current results may ultimately be used for design iterations that improve outcomes following implantation of future dedicated bifurcation stents

Effect of GPS Feedback on Lactate Threshold Pacing in Intercollegiate Distance Runners

International Journal of Exercise Science 6(1) : 74-80, 2013. In their roles as coaches, the authors have observed that first-year collegiate distance runners often have difficulty running at prescribed training paces during lactate threshold (LT) training runs. Previous research has validated the accuracy of global positioning system (GPS) devices in providing distance and velocity feedback during running. The purpose of this study was to determine the efficacy of using the Garmin Forerunner 305 GPS watch (Garmin) to reduce deviations from prescribed training paces during LT runs with first-year collegiate runners. Participants were two groups of varsity cross country runners who completed a three-week LT training intervention either with (n = 5) or without (n = 6) a Garmin device. Prescribed training paces were based off an initial time-trial. In both the pre- and post-test runs, in which all runners ran without a Garmin device, differences were calculated between the prescribed pace and actual pace. The comparisons revealed a significant difference between the training groups in the post-test. Those runners who trained with the Garmin device had a significant decrease in pacing variability. This suggests that GPS pacing feedback appears to be an effective tool at improving LT pacing in first-year collegiate distance runners

Two-Legged Hopping in Autism Spectrum Disorders

Sensory processing deficits are common within autism spectrum disorders (ASD). Deficits have a heterogeneous dispersion across the spectrum and multimodal processing tasks are thought to magnify integration difficulties. Two-legged hopping in place in sync with an auditory cue (2.3, 3.0 Hz) was studied in a group of six individuals with expressive language impaired ASD (ELI-ASD) and an age-matched control group. Vertical ground reaction force data were collected and discrete Fourier transforms were utilized to determine dominant hopping cadence. Effective leg stiffness was computed through a mass-spring model representation. The ELI-ASD group were unsuccessful in matching their hopping cadence (2.21 ± 0.30 hops·s−1, 2.35 ± 0.41 hops·s−1) to either auditory cue with greater deviations at the 3.0 Hz cue. In contrast, the control group was able to match hopping cadence (2.35 ± 0.06 hops·s−1, 3.02 ± 0.10 hops·s−1) to either cue via an adjustment of effective leg stiffness. The ELI-ASD group demonstrated a varied response with an interquartile range (IQR) in excess of 0.5 hops·s−1 as compared to the control group with an IQR \u3c 0.03 hops·s−1. Several sensorimotor mechanisms could explain the inability of participants with ELI-ASD to modulate motor output to match an external auditory cue. These results suggest that a multimodal gross motor task can (1) discriminate performance among a group of individuals with severe autism, and (2) could be a useful quantitative tool for evaluating motor performance in individuals with ASD individuals

Gait Analysis of Teenagers and Young Adults Diagnosed with Autism & Severe Verbal Communication Disorders

Both movement differences and disorders are common within autism spectrum disorders (ASD). These differences have wide and heterogeneous variability among different ages and sub-groups all diagnosed with ASD. Gait was studied in a more homogeneously identified group of nine teenagers and young adults who scored as “severe” in both measures of verbal communication and overall rating of Autism on the Childhood Autism Rating Scales (CARS). The ASD individuals were compared to a group of typically developing university undergraduates of similar ages. All participants walked a distance of 6-meters across a GAITRite (GR) electronic walkway for six trials. The ASD and comparison groups differed widely on many spatiotemporal aspects of gait including: step and stride length, foot positioning, cadence, velocity, step time, gait cycle time, swing time, stance time, and single and double support time. Moreover, the two groups differed in the percentage of the total gait cycle in each of these phases. The qualitative rating of “Body Use” on the CARS also indicated severe levels of unusual body movement for all of the ASD participants. These findings demonstrate that older teens and young adults with “severe” forms of Verbal Communication Impairments and Autism differ widely in their gait from typically developing individuals. The differences found in the current investigation are far more pronounced compared to previous findings with younger and/or less severely involved individuals diagnosed with ASD as compared to typically developing controls. As such, these data may be a useful anchor-point in understanding the trajectory of development of gait specifically and motor functions generally.

Corticosteroids Are Essential for Maintaining Cardiovascular Function in Male Mice

Activation of the hypothalamic-pituitary-adrenal axis results in the release of hormones from the adrenal glands, including glucocorticoids and mineralocorticoids. The physiological association between corticosteroids and cardiac disease is becoming increasingly recognized; however, the mechanisms underlying this association are not well understood. To determine the biological effects of corticosteroids on the heart, we investigated the impact of adrenalectomy in C57BL/6 male mice. Animals were adrenalectomized (ADX) at 1 month of age and maintained for 3–6 months after surgery to evaluate the effects of long-term adrenalectomy on cardiac function. Morphological evaluation suggested that ADX mice showed significantly enlarged hearts compared with age-matched intact controls. These changes in morphology correlated with deficits in left ventricular (LV) function and electrocardiogram (ECG) abnormalities in ADX mice. Correlating with these functional defects, gene expression analysis of ADX hearts revealed aberrant expression of a large cohort of genes associated with cardiac hypertrophy and arrhythmia. Combined corticosterone and aldosterone replacement treatment prevented the emergence of cardiac abnormalities in ADX mice, whereas corticosterone replacement prevented the effects of adrenalectomy on LV function but did not block the emergence of ECG alterations. Aldosterone replacement did not preserve the LV function but prevented ECG abnormalities. Together, the data indicate that adrenal glucocorticoids and mineralocorticoids either directly or indirectly have selective effects in the heart and their signaling pathways are essential in maintaining normal cardiac function

Virtual synchronous-machine control of voltage-source converters in a low-voltage microgrid

In order to facilitate the further integration of distributed renewable generation into existing power systems, enhanced control schemes for grid-tied power electronic converters are necessary to ensure non-synchronous power sources can provide power and support to the grid. The virtual-synchronous-machine concept proposes the use of control schemes to enable static generators to operate with the dynamics of rotating synchronous generators. In this paper, a control scheme is presented based on the principle of active-power synchronization to regulate the active power of a grid-tied voltage-source converter based on an emulation of the synchronous-machine swing equation. Design of a cascaded inner-loop voltage and resonant current control is presented to regulate the output voltage as specified via the outer-loop virtual-machine control scheme responsible for power regulation. The performance of this control scheme is investigated within the context of microgrid operation for the provision of active and reactive power to the system, and microgrid frequency support. Experimental validation is provided via the use of a 15 kVA three-phase VSC in a 90 kVA 400V microgrid

Expansion of specialized epidermis induced by hormonal state and mechanical strain

In mammals, some sites of specialized skin such as the palms, soles, and lips grow proportionally with the animal. However, other types of specialized skin such as the nipple and anal/genital region are dramatically altered with changes of reproductive status. The specific cell types that mediate the growth of these sites have not been identified. In the mouse, we observed a dramatic expansion of the specialized epidermis of the nipple, coupled to changes in connective tissue and hair shaft density, which we designate as areola formation. During this process thymidine analog uptake was elevated in the epidermis and hair follicles. Although there were no changes in connective tissue cell proliferation, we did observe an altered expression of extracellular matrix genes. In addition, the fibroblasts of the virgin nipple areola and region showed increased transcript and protein levels for estrogen, progesterone, relaxin, and oxytocin relative to those of ventral skin. To determine the role of pregnancy, lactation hormonal milieu, and localized mechanical strain on areola formation, we created models that separated these stimuli and evaluated changes in gross structure, proliferation and protein expression. While modest increases of epidermal proliferation and remodeling of connective tissue occurred as a result of individual stimuli, areola formation required exposure to pregnancy hormones, as well as mechanical strain

Estrous cycle influences excitatory amino acid transport and visceral pain sensitivity in the rat: Effects of early-life stress

Background: Early-life stress (ELS) is a recognized risk factor for chronic pain disorders, and females appear to be more sensitive to the negative effects of stress. Moreover, estrous cycle-related fluctuations in estrogen levels have been linked with alternating pain sensitivity. Aberrant central circuitry involving both the anterior cingulate cortex (ACC) and the lumbosacral spinal cord has also been implicated in the modulation of visceral pain in clinical and preclinical studies. Here we further investigate changes in visceral pain sensitivity and central glutamatergic systems in rats with respect to estrous cycle and ELS. Methods: We investigated visceral sensitivity in adult female Sprague-Dawley rats, which had undergone maternal separation (MS) in early life or remained non-separated (NS), by performing colorectal distension (CRD). We also assessed excitatory amino acid uptake through excitatory amino acid transporters (EAATs) in the lumbosacral spinal cord and ACC. Results: NS animals in proestrus and estrus exhibited reduced EAAT uptake and decreased threshold to CRD. Moreover, total pain behaviors were increased in these stages. MS rats exhibited lower pain thresholds and higher total pain behaviors to CRD across all stages of the estrous cycle. Interestingly, cortical EAAT function in MS rats was inhibited in the low estrogen state—an effect completely opposite to that seen in NS rats. Conclusions: This data confirms that estrous cycle and ELS are significant factors in visceral sensitivity and fluctuations in EAAT function may be a perpetuating factor mediating central sensitization