For individuals with Down syndrome (DS), obstructive sleep apnea (OSA) is a complex disorder with significant clinical consequences. OSA is seen frequently in DS, and when present, it tends to be more severe. This increased prevalence is likely related to common anatomic abnormalities and a greater risk of additional comorbidities such as hypotonia and obesity. Because signs and symptoms do not often correlate with disease, all children and adults with DS should receive routine screening for OSA. Similar to the general population, polysomnography remains the gold standard for diagnosis. Because individuals with DS may be more susceptible to cardiovascular and neurocognitive sequelae, early diagnosis and treatment of OSA is becoming increasingly important. Treatment options generally involve upper airway surgery (primarily adenotonsillectomy) and continuous positive airway pressure (CPAP); however, various adjunctive therapies including intranasal steroids, palatal expansion, and oropharyngeal exercises are also available. Residual disease status post adenotonsillectomy is common, and further evaluation (eg, drug-induced sleep endoscopy [DISE]) is often needed. More advanced and directed airway surgery can be performed if additional sites of obstruction are observed. Novel therapies including hypoglossal nerve stimulation are emerging as effective treatments for refractory OSA. Due to the diversity among individuals with DS, personalized treatment plans should be developed. Within this arena, opportunities for research remain abundant and should include areas involving patient risk factors, alternative diagnostic methods, and outcome analysis.

Study Objectives: Obstructive sleep apnea (OSA) is common in children with Down syndrome (DS) and associated with significant morbidity. In the current study we examined polysomnographic outcomes of children with DS who underwent tonsillectomy. Methods: A retrospective chart review of children with DS who underwent a tonsillectomy between 2009-2015 was performed. All children had either a concurrent adenoidectomy or had previously underwent an adenoidectomy. Children with preoperative and postoperative polysomnograms within 6 months of surgery were included in the analysis. Preoperative OSA severity was categorized by obstructive apnea-hypopnea index (OAHI) as follows: mild = 1.5-4.9 events/h; moderate = 5-9.9 events/h; severe ≥ 10 events/h. Results: Seventy-five children with DS met inclusion criteria. The cohort included 41 males and 34 females with mean age of 5.1 years (± 3.6 years), range of 0.51-16.60 years. Preoperative OSA severity was as follows, mild = 8/75; moderate = 16/75; severe = 51/75. Cure rates varied depending on definition: 12% for OAHI < 1 event/h and 21% for OAHI < 2 events/h. 48% had residual OAHI < 5 events/h. On postoperative PSG 16/75 saw resolution (OAHI < 2) in OSA; mild = 21/75; moderate = 20/75; severe = 18/75. 48% moderate/severe patients saw conversion to mild or cure. Overall, tonsillectomy resulted in significant improvements in multiple respiratory parameters, including OAHI (OAHI; 21.3 ± 19.7 to 8.0 ± 8.1, P < .001), percent sleep time with oxygen saturations < 90% (19.0 ± 25.0 to 6.1 ± 10.1, P < .001), and percent sleep time with end-tidal carbon dioxide above 50 mmHg (7.7 ± 18.0 to 1.8 ± 6.6, P = .001). Average asleep oxygen saturation was associated with postoperative OSA severity. Conclusions: Children with DS and OSA who undergo tonsillectomy experience improvements in both respiratory event frequency and gas exchange but approximately half still have moderate to severe residual OSA. Keywords: child, Down syndrome, gas exchange, obstructive sleep apnea, polysomnography, tonsillectomy

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Increases in blood flow capacity produced in Gr and Gw by ET appear to be due in part to increased arteriolar density. In contrast, increased arteriolar density does not contribute to increased blood flow capacity of Gw in IST rats.

The purpose of the present study was to determine which behavioral and physical phenotypes would be most likely to divide the ASD population into discrete subgroups. The taxometric methods of Maximum Covariance (MAXCOV) and Minus Mean Below A Cut (MAMBAC) were employed to test for categorical versus continuous variation of each phenotype across the ASD population. Data was retrieved from the Autism Genetic Resource Exchange and the University of Missouri Autism Database. The results of our analyses support subgrouping subjects based on variation in social interaction/communication, intelligence, and essential/complex phenotype; in contrast, subjects varied continuously in insistence on sameness, repetitive sensory motor actions, language acquisition, and, tentatively, adaptive functioning. Stratifying ASD samples based on taxometric results should increase power in gene-finding studies and aid in treatment efficacy research.

Our findings indicate that there are significant seasonal trends for both snoring and sleep apnea internet search engine queries, with a peak in the winter and early spring. Further research is indicated to determine the mechanisms underlying these findings, whether they have clinical impact, and if they are associated with other comorbid medical conditions that have similar patterns of seasonal exacerbation.

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Current literature suggests that chronic nitric oxide synthase (NOS) inhibition has differential effects on endothelium-dependent dilation (EDD) of conduit arteries vs. arterioles. Therefore, we hypothesized that chronic inhibition of NOS would impair EDD of porcine left anterior descending (LAD) coronary arteries but not coronary arterioles. Thirty-nine female Yucatan miniature swine were included in the study. Animals drank either tap water or water with N G -nitro-L-arginine methyl ester (L-NAME; 100 mg/l), resulting in control and chronic NOS inhibition (CNI) groups, respectively. Treatment was continued for 1-3 mo (8.3 ± 0.6 mg · kg −1 · day −1 ). In vitro EDD of coronary LADs and arterioles was assessed via responses to ADP (LADs only) and bradykinin (BK), and endothelium-independent function was assessed via responses to sodium nitroprusside (SNP). Chronic NOS inhibition diminished coronary artery EDD to ADP and BK. Incubating LAD rings with L-NAME decreased relaxation responses of LADs from control pigs but not from CNI pigs such that between-group differences were abolished. Neither indomethacin (Indo) nor sulfaphenazole incubation significantly affected relaxation responses of LAD rings to ADP or BK. Coronary arteries from CNI pigs showed enhanced relaxation responses to SNP. In contrast to coronary arteries, coronary arterioles from CNI pigs demonstrated preserved EDD to BK and no increase in dilation responses to SNP. L-NAME, Indo, and L-NAME + Indo incubation did not result in significant between-group differences in arteriole dilation responses to BK. These results suggest that although chronic NOS inhibition diminishes EDD of LAD rings, most likely via a NOS-dependent mechanism, it does not affect EDD of coronary arterioles. Keywords endothelium-dependent dilation; N G -nitro-L-arginine methyl esterA healthy vascular endothelium promotes arterial homeostasis; in contrast, an injured endothelium portends arterial dysfunction (28). Although the mechanisms by which endothelial dysfunction exacts vascular damage remain to be fully elucidated, it is thought that reduced nitric oxide (NO) production and/or scavenging play a crucial role (27).Chronically decreased NO production by nitric oxide synthase (NOS) inhibition results in significant hemodynamic alterations. Systemically, NOS inhibition via N G -nitro-L-argi-nine methyl ester (L-NAME) or other NOS inhibitor administration increases blood pressure and peripheral resistance while decreasing heart rate and cardiac output (4,11,18,21,24,29). The fact that chronic NOS inhibition causes increased mean arterial pressure in vivo could be Address for reprint requests and other correspondence: M. H. Laughlin, Department of Biomedical Sciences, W102 Veterinary Medicine, 1600 E. Rollins Rd., Univ. of Missouri, Columbia, MO 65211 (e-mail: laughlinm @missouri.edu). * D. G. Ingram and S. C. Newcomer contributed equally to this work. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript evidence that chronic NOS inh...