Atrial repolarization as observable in the PQ interval

Objective: To study the involvement of atrial repolarization in body surface potentials. Methods: Electrocardiograms of healthy subjects were recorded using a 64-lead system. The data analysis focused on the PQ intervals, while devoting special attention to the low-amplitude signals during the PQ segment: the segment from the end of the P wave till onset QRS. The data were analyzed by inspecting body surface potential maps and the XYZ signals of the vector cardiogram. Results: Standard P wave features exhibited normal values. The local potential extremes were found at positions not sampled by the standard leads. The PQ segment was found to be not iso-electric, the potential distribution being very similar to that at the timing of apex P but for a reversed polarity and a 3-fold lower magnitude. Conclusion: The results demonstrate a significant involvement of atrial repolarization during the PQ interval, with essentially non-concomitant atrial T waves

Jaw thrust versus the use of a boil-and-bite mandibular advancement device as a screening tool during drug-induced sleep endoscopy

STUDY OBJECTIVES: The objectives of this study were to analyze agreement in degree of obstruction and configuration of the upper airway between jaw thrust and an oral device in situ during drug-induced sleep endoscopy and to evaluate clinical decision making using jaw thrust or a boil-and-bite mandibular advancement device (MAD; the MyTAP). METHODS: This was a single-center prospective cohort study in patients with obstructive sleep apnea who underwent drug-induced sleep endoscopy between January and July 2019. RESULTS: Sixty-three patients were included. Agreement among observations in the supine position for degree of obstruction was 60% (n = 36, κ = 0.41) at the level of the velum, 68.3% (n = 41, κ = 0.35) for oropharynx, 58.3% (n = 35, κ = 0.28) for tongue base, and 56.7% (n = 34, κ = 0.14) for epiglottis; agreement among observations in the lateral position were 81.7% (n = 49, κ = 0.32), 71.7% (n = 43, κ = 0.36), 90.0% (n = 54, κ = 0.23), and 96.7% (n = 58, κ = could not be determined), respectively. In the supine position, agreement for configuration of obstruction at the level of the velum was found in 20 of 29 patients (69.0%, κ = 0.41) and in the lateral position was 100%. Thirty patients would have been prescribed a MAD using jaw thrust and 34 using the boil-and-bite MAD as a screening instrument. The main reason for being labeled as nonsuitable was complete residual retropalatal collapse during jaw thrust. Using the boil-and-bite MAD, this was caused by complete retropalatal or hypopharyngeal collapse. CONCLUSIONS: There is only slight to moderate agreement in degree of obstruction for jaw thrust and a new-generation boil-and-bite MAD during drug-induced sleep endoscopy. Greater improvement of upper airway patency at the hypopharyngeal level was observed during jaw thrust, but this maneuver was less effective in improving upper airway obstruction at the retropalatal level. CITATION: Vonk PE, Uniken Venema JAM, Hoekema A, Ravesloot MJL, van de Velde–Muusers JA, de Vries N. Jaw thrust versus the use of a boil-and-bite mandibular advancement device as a screening tool during drug-induced sleep endoscopy. J Clin Sleep Med. 2020;16(7):1021–1027

A comparative study of Tam3 and Ac transposition in transgenic tobacco and petunia plants

Transposition of the Anthirrinum majus Tam3 element and the Zea mays Ac element has been monitored in petunia and tobacco plants. Plant vectors were constructed with the transposable elements cloned into the leader sequence of a marker gene. Agrobacterium tumefaciens-mediated leaf disc transformation was used to introduce the transposable element constructs into plant cells. In transgenic plants, excision of the transposable element restores gene expression and results in a clearly distinguishable phenotype. Based on restored expression of the hygromycin phosphotransferase II (HPTII) gene, we established that Tam3 excises in 30% of the transformed petunia plants and in 60% of the transformed tobacco plants. Ac excises from the HPTII gene with comparable frequencies (30%) in both plant species. When the β-glucuronidase (GUS) gene was used to detect transposition of Tam3, a significantly lower excision frequency (13%) was found in both plant species. It could be shown that deletion of parts of the transposable elements Tam3 and Ac, removing either one of the terminal inverted repeats (TIR) or part of the presumptive transposase coding region, abolished the excision from the marker genes. This demonstrates that excision of the transposable element Tam3 in heterologous plant species, as documented for the autonomous element Ac, also depends on both properties. Southern blot hybridization shows the expected excision pattern and the reintegration of Tam3 and Ac elements into the genome of tobacco plants.