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BACKGROUND: Hypermobile Ehlers-Danlos Syndrome (hEDS) is a connective tissue disorder characterized by joint hypermobility and other systemic manifestations, such as cardiovascular symptoms, musculoskeletal pain, and joint instability. Cardiovascular symptoms, such as lightheadedness and palpitations, and types of dysautonomia, including postural orthostatic tachycardia syndrome (POTS), are frequently reported in adults with hEDS and have been shown to negatively impact quality of life (QoL). OBJECTIVE: This brief review will be an overview of co-occurring symptoms in POTS and hEDS to inform potential cardiovascular screening procedures. RESULTS: While many patients with hEDS report cardiovascular symptoms, few have structural abnormalities, suggesting that dysautonomia is likely responsible for these symptoms. One validated screening measure for dysautonomia symptom burden is the Composite Autonomic Symptom Scale (COMPASS-31). Studies have found that adults with POTS, hEDS, and both POTS and hEDS have higher COMPASS-31 scores than the general population, suggesting a high symptom burden due to dysautonomia, which leads to impaired QoL. CONCLUSION: While studies have examined cardiovascular symptoms and the impact of dysautonomia in adults with and without hEDS, there is scant literature on dysautonomia in pediatric patients with hEDS. Therefore, more studies on cardiovascular symptoms and dysautonomia, as they relate to the quality of life in pediatric patients with hEDS, are needed. This brief review summarizes the current literature on dysautonomia and cardiovascular symptoms in pediatric and adult populations with hEDS.

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Understanding interactions between inhaled nanoparticles and lung surfactants (LS) present at the air-water interface in the lung, is critical to assessing the toxicity of these nanoparticles. Specifically, in this work, we assess the impact of engineered carbon nanoparticles (ECN) on the ability of healthy LS to undergo reversible collapse, which is essential for proper functioning of LS. Using a Langmuir trough, multiple compression-expansion cycles are performed to assess changes in the surface pressure vs. area isotherms with time and continuous cyclic compression-expansion. Further, theoretical analysis of the isotherms is used to calculate the ability of these lipid systems to retain material during monolayer collapse, due to interactions with ECNs. These results are complemented with fluorescence images of alterations in collapse mechanisms in these monolayer films. Four different model phospholipid systems, that mimic the major compositions of LS, are used in this study. Together, our results show that the ECN does not impact the mechanism of collapse. However, the ability to retain material at the interface during monolayer collapse, as well as re-incorporation of material after a compression-expansion cycle is altered to varying extent by ECNs and depends on the composition of the lipid mixtures.

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While feeding is rewarding, the feeling of satiation has been theorized to have a mixed affect. Using a food restriction model of overeating we examined whether bingeing was capable of supporting conditioned taste avoidance (CTA). Adult male Sprague-Dawley rats were maintained on either an ad lib (n=8) or restricted (50% of regular consumption; n=24) food access for 20 days. On Days 9, 14, and 19 all rats were given access to a novel saccharin solution in place of water, and two groups of food restricted rats were given access to either 100% of regular food consumption or ad lib food. Ad lib access in the restricted rats induced significant overeating on all three exposures. After all rats were returned to ad lib feeding, a 24h two-bottle saccharin/water choice test displayed significantly reduced saccharin consumption in the overeating rats, compared to those in the other 3 groups. To determine whether this avoidance was due to a learned association, a second experiment used a latent inhibition paradigm, familiarizing half the rats with the saccharin for 8 days prior to pairing it with overeating. Using the design of Experiment 1, with only the continuously ad lib and the restricted to ad lib feeding groups, it was found that the overeating-induced saccharin avoidance was attenuated by the pre-exposure. These results suggest that self-induced overeating is capable of supporting a learned avoidance of a novel solution suggestive of a conditioned satiety or taste avoidance.

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Adult male rats given ad lib access to food and a running wheel show an initial feeding and weight suppression. Over 6-10 days feeding recovers, but body weight remains low. It is not clear which effect is primary, the wheel-induced feeding or weight change. To test this, rats were first restricted to 15g of food a day for 8 or 16 days to reduce their weight relative to control non-restricted rats. They were then returned to ad lib feeding and half the restricted and non-restricted control rats were introduced to the wheel either immediately (Experiment 1) or 4 days later (Experiment 2). Food intake, body weight, and wheel running were monitored throughout the experiments. At the return to ad lib feeding, prior food restriction elevated feeding. Both immediate and delayed wheel access suppressed feeding in both groups of wheel access rats compared to the appropriate control rats. Feeding history did not have a significant effect on wheel running. The wheel-induced reductions in feeding from baseline were similar in the weight reduced and normal weight animals suggesting that prior weight restriction did not prevent the onset of the wheel-induced feeding suppression. It is therefore suggested that the feeding suppression is not driven by a reduced weight set point.

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