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Biomedical subjects

W Y Yu

Publications and source records attributed to W Y Yu.

28 records · Page 2Linked to original sources

Closed reduction of lumbosacral fracture dislocations.

A unique method for closed reduction of lumbosacral fracture dislocations that uses a circle-electric bed is described. Fine radiological description of the injury with computed tomography scanning allows the application of appropriate forces to facilitate the reduction, while having the patient awake during the procedure greatly reduces the chance of introducing further neurological deficit.

Adult

Colonic variceal bleeding in a child.

A 5-year-old girl with biliary atresia is described who developed lower gastrointestinal bleeding from colonic varices. Vasopressin infusions temporarily controlled the bleeding. Following a right hemicolectomy the bleeding has not recurred.

Child, Preschool

Detection of interaural time differences for clicks and tone pips: effects of interaural signal disparity.

The ability to detect small interaural time differences (delta t) was determined in 4 subjects using clicks or long tone pips of various interaural signal disparities which are expressed as the extent of interaural spectral overlaps. The interaural signal disparity was varied by changing (a) the interaural pulse duration difference (delta d) for clicks, or (b) the interaural carrier frequency difference (delta f) for tone pips. In either case, the sensitivity to delta t was maximal under diotic presentations and declined with delta d or delta f. The overall sensitivity to delta t was remarkably higher for clicks than for long tone pips. The results indicate that both (a) the extent of binaural spectral overlaps and (b) the structure of acoustic stimuli are important in detecting small interaural time differences of binaural sounds.

Acoustic Stimulation

Mechanicla properties and mineral content of avascular and revascularizing cortical bone.

The mechanical properties of avascular and revascularizing bone and their mineral content were studied in thirty adult dogs. The strength and mineral content of avascular bone decreased in the early phase of avascular necrosis, and with revascularization the bone-mineral content increased but the mechanical strength decreased further. In the normal bone the mechanical strength increased with an increase in mineral content.

Animals

Comparative effects of the calcium antagonist isradipine and some other dihydropyridine derivatives on regional blood flow in anesthetized open-chest dogs.

The effects of isradipine (PN 200-110), isopropyl 4-(2,1,3-benzoxadiazol-4-yl)-1,4-dihydro-5-methoxycarbonyl-2,6-dim ethyl-3- pyridinecarboxylate, on some cardiovascular parameters and regional blood flow were compared with those of other dihydropyridine derivatives in anesthetized open-chest dogs. Intravenous (i.v.) administrations of isradipine 3 and 10 micrograms/kg, nifedipine 10 micrograms/kg, nicardipine 10 micrograms/kg and nisoldipine 10 micrograms/kg, decreased aortic blood pressure and increased aortic (AoF), vertebral (VBF) and coronary blood flow (CBF), but did not affect heart rate and left ventricular end-diastolic pressure. Renal blood flow was reduced by isradipine 10 micrograms/kg and nifedipine 10 micrograms/kg, but was not influenced by isradipine 3 micrograms/kg, nicardipine 10 micrograms/kg and nisoldipine 10 micrograms/kg. Left ventricular dP/dt was increased by isradipine 3 micrograms/kg, nicardipine 10 micrograms/kg and nisoldipine 10 micrograms/kg, but remained essentially unchanged following isradipine 10 micrograms/kg and nifedipine 10 micrograms/kg. The increase in AoF, VBF and CBF lasted 5-9 min following nifedipine 10 micrograms/kg or nicardipine 10 micrograms/kg, 17-30 min following nifedipine 10 micrograms/kg or nicardipine 10 micrograms/kg, 17-30 min following nisoldipine 10 micrograms/kg, and 16-44 min following isradipine 3 micrograms/kg i.v., but persisted for at least 60 min following isradipine 10 micrograms/kg. Under the experimental conditions and at the doses used in this study, all 4 drugs reduced total peripheral resistance as well as resistance in the vertebral, coronary and renal vascular beds. The results suggest that isradipine exerts cardiovascular effects similar to other calcium antagonists of the dihydropyridine group, but possesses a longer duration of action and shows a greater specificity in reducing coronary vascular resistance than nifedipine, nicardipine and nisoldipine.

Anesthesia