Three-dimensional CT measurement of adult acetabular dysplasia: technique, preliminary results in normal subjects, and potential applications.

OBJECTIVE: To assess a three-dimensional computed tomography (3DCT) technique for measurement of acetabular coverage in adults. DESIGN: We used 3DCT to define the geometric centre of the femoral head and to measure centre-edge angles (CEAs) at 10 degrees rotational increments around the acetabular rim. The means, ranges, standard deviations and 95% confidence intervals for the CEAs at the various rotational increments were determined. Inter- and intra-observer variability was measured. The normal values are compared with two example cases of acetabular dysplasia. PATIENTS: The normal hips of 15 subjects aged 1949 years (mean 34.2 years) were measured. RESULTS: The 3DCT measurements are reproducible (mean difference interobserver, 1.7 degrees - 7.9 degrees; mean difference intra-observer, 0.6 degrees-6.9 degrees). Mean normal CEA at the lateral rim was 33 degrees with a 95% confidence interval of 23 degrees - 43 degrees. Mean normal CEAs at 10 rotational increments from anterior to posterior rim were determined, and graphed as a 'normal curve'. CONCLUSION: This new 3DCT method of assessing acetabular dysplasia is simple, reproducible, and applicable to diagnosis, quantification and surgical planning for adult acetabular dysplasia patients.

Cardiovascular influences on rat parabrachial nucleus: an electrophysiological study.

The rat pontine parabrachial nucleus is a prominent recipient of autonomic-related information from the more caudal levels of the neuraxis. The present experiments examined the responsiveness of neurons within the parabrachial nucleus to the following three specific cardiovascular stimuli: the activation of peripheral arterial baroreceptors, right atrial stretch receptors, and the administration of systemic angiotensin (ANG) II. Extracellular recordings in urethan-anesthetized animals indicate the presence of cells, mostly within the lateral parabrachial nucleus, that increase (17.5%, 28 of 160 cells) and decrease (48.1%, 77 of 160 cells) their excitability consequent to baroreceptor activation. A similar profile of alteration in cellular firing rates was observed with intravenous ANG II (increase in 15.8%, 16 of 101 cells; decrease in 28.7%, 29 of 101 cells). In contrast, fewer neurons located within the medial parabrachial and the Kölliker-Fuse nuclei were activated by these stimuli. A majority of cells (80%, n = 15) displayed a lack of response to right atrial stretch receptor activation. Of ANG II-sensitive lateral parabrachial cells, 23% (n = 43) revealed an alteration in excitability that could not be explained on the basis of a response to elevation in blood pressure. It is possible that this group of cells may be activated by the actions of systemic ANG II on neurons of the area postrema, a circumventricular structure, whose central projections are directed toward the parabrachial nucleus. These findings also support the notion of a diversity of cardiovascular inputs to topographically segregated regions within the parabrachial nucleus.