Cephalometric assessment of craniofacial morphology in Chinese patients with obstructive sleep apnoea.

OBJECTIVE: To compare the differences in craniofacial morphology in Chinese patients with and without obstructive sleep apnoea (OSA). METHOD: We performed lateral cephalometric radiographs on 94 consecutive patients (77 males) referred with snoring or other symptoms suggestive of OSA for polysomnography (PSG). Significant OSA was defined as an apneoa-hypopnoea index (AHI) > or = 10/h of sleep on overnight PSG. The cephalometric data were compared between those with and without significant OSA. RESULTS: (mean +/- SD) There were 69 (56 males) with significant OSA with mean age 53 +/- 12 years, body mass index (BMI) 28.6 +/- 5.0 kg/m2, AHI 36.5 +/- 20.6/h, and minimum SaO2 76 +/- 14%. There were 25 controls (21 males) without significant OSA with similar age and BMI. The mandibular plane to hyoid bone distance (MPH) and the perpendicular distance from hyoid bone to the line connecting C3 vertebra and retrognathion (HHI) were significantly longer in the OSA patients. The angle measurement from sella to nasion to point A (SNA) was smaller in the OSA group. MPH distance was the only independent variable for significant OSA with an odds ratio of 3.47 (95% CI 1.39-8.66). Abnormalities of the MPH and SNA were more marked in the OSA patients with BMI > or = 30 kg/m2. CONCLUSIONS: Significant differences in craniofacial morphology are noted between OSA patients and non-apnoeic controls. An inferiorly positioned hyoid bone and a retropositioned maxilla may predispose obese patients to more severe OSA.

Laser surface profiler.

By accurate measurement of the angle of reflection of a laser beam that is incident upon a reflective surface with a position-sensitive detector, changes in the surface-normal direction (the slope or the derivative of the surface) can be determined directly. An instrument has been built that makes repeated measurements over the surface and uses the collected data to produce a gray-scale image of the slope. The resolution of this system for detecting changes in the surface-normal direction is found to be better than 0.01 degrees . By focusing of the laser beam to achieve a lateral resolution of 5 mum , the resolvable surface-height change owing to a variation in slope is estimated to be <1 nm .

An RNA-dependent ATPase from Chlamydomonas reinhardII.

An RNA-dependent ATPase has been isolated from extracts of Chlamydomonas reinhardii. The enzyme catalyzes the hydrolysis of ATP, dATP, CTP and dCTP to the corresponding nucleoside diphosphate and Pi in the presence of Mg2+ or Mn2+ and an RNA cofactor. In 1 mM MgCl2 it displays the greatest activity with poly(A), poly(I) and poly(U); and somewhat lower activity with poly(C) and T7 RNA. Although the enzyme is active with single-stranded DNA, all the single-stranded RNAs tested were significantly more effective cofactors than any of the single or double-stranded DNAs tested. A comparison of this ATPase with other RNA-dependent ATPases indicates that is has more in common with the ATPase isolated from the nuclei of animal cells than with the RNA synthesis termination protein rho, the major RNA-dependent ATPase from Escherichia coli. Although chloroplasts of C. reinhardii are known to contain many bacterial-like gene expression components, the presence of an enzyme with close homology to the E. coli rho protein was not detected.