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Biomedical subjects

L Yao

Publications and source records attributed to L Yao.

At least 181 records · Page 10Linked to original sources
PubMed1990

Calcium-calmodulin binding in ischemic rat neurons after calcium channel blocker therapy.

Calcium channel blockers such as nicardipine improve outcome after global cerebral ischemia and may attenuate ischemic neuronal injury by preventing calcium influx and binding to calmodulin. We followed the temporal and regional sequence of neuronal calcium-calmodulin binding in normal rats (n = 6), untreated ischemic rats (n = 15), and ischemic rats treated with 0.05 mg/kg/hr s.c. nicardipine (n = 13). After 30 minutes of four-vessel occlusion, 40-microns brain sections were incubated in an anti-calmodulin antibody specific for calmodulin not bound to calcium and brain protein. Light-microscopic sections were examined immediately after ischemia and after 2 and 24 hours of reperfusion. Extensive staining of unbound calmodulin was seen in all hippocampal regions and in the cortex in normal rats. In untreated ischemic control rats, staining was lost, indicating calcium-calmodulin binding immediately after ischemia in all regions. However, after 24 hours, staining returned to normal in the cortex and dentate, and minimal staining returned in CA1 and CA3. Nicardipine-treated animals had significantly less calcium-calmodulin binding in CA1 and in the dentate after 2 hours of reperfusion. This study demonstrates that in clinically relevant doses nicardipine has a limited effect on calcium-calmodulin binding in selectively vulnerable regions after severe ischemia.

Animals↗
PubMed1989

Isoproterenol induction of vasodepressor-type reaction in vasodepressor-prone persons.

The ability of isoproterenol to induce symptoms and laboratory findings of a vasodepressor reaction was tested in 48 patients, ages 17 to 74, divided into 4 groups according to the reason for their referral. Group 1 comprised 12 patients with vasodepressor syncope, group 2 had 8 patients with syncope of unknown origin, group 3 included 11 patients with syncope due to seizures in 2 and ventricular tachycardia in 9, group 4 had 17 patients with various arrhythmias not associated with syncope. Isoproterenol boluses were administered starting at 2 micrograms and increased in 2-micrograms steps to a maximum of 8 micrograms at 0 degree and +60 degrees. The responses at 0 degrees were all normal. At +60 degrees a vasodepressor reaction consisting of syncope or near syncope, hypotension and bradycardia was produced by isoproterenol (mean dose 6.0 +/- 0.26 micrograms) in 8 patients from group 1 (66.6%), 4 from group 2 (50%), 0 from group 3 and 4 from group 4 (23.5%). Three of the 4 patients in group 4 had a remote history of classic vasodepressor syncope. The overall sensitivity and specificity of the test were 73 and 85%, respectively, while the predictive accuracy of a test with positive or negative outcome were 69 and 89%, respectively. Muscarinic receptor blockade with atropine in 4 patients prevented isoproterenol-induced bradycardia but not hypotension or symptoms of fainting. Beta-adrenergic receptor blockade with propranolol inhibited all aspects of the isoproterenol-induced faint. Thus, the administration of isoproterenol during a passive upright tilt may identify persons who suffer from or are prone to a vasodepressor reaction.

Adult↗
PubMed1989

Palmar dislocation of the trapezoid: case report.

A case of palmar dislocation of the trapezoid, associated with radial subluxation of the trapezium, is presented. This rare injury was treated by internal fixation. A satisfactory clinical result is noted 4 years later.

Adult↗
PubMed1989

Rounded atelectasis associated with end-stage renal disease.

Three cases of end-stage renal disease are presented where plain radiographs of the chest suggested the diagnosis of rounded atelectasis. The clinical setting and follow-up radiographs in each case served to corroborate this diagnosis. The recognition of this benign condition in patients with end-stage renal disease may be important in obviating further invasive procedures in this subset of high risk patients.

Humans↗
PubMed1988

Anterior cruciate ligament tears: MR imaging compared with arthroscopy and clinical tests.

Seventy-nine magnetic resonance (MR) studies of the knee were reviewed in an evaluation of the ability of MR imaging to demonstrate arthroscopically proved anterior cruciate ligament (ACL) tears. MR findings were also compared with the findings of two commonly applied clinical tests of ACL instability: the Lachman test and the anterior drawer test. The sensitivity of MR imaging was 94% (17 of 18), compared with 78% (14 of 18) for the anterior drawer test and 89% (16 of 18) for the Lachman test. The specificity was 100% for all three. Three MR criteria were applied: irregularity or a wavy contour of the anterior margin of the ligament, high-signal-intensity change within the substance of the ligament on T2-weighted images, and discontinuity of that substance. The sagittal T2-weighted image was especially helpful, producing an "arthrographic" effect, in which the anterior margin of the ACL is outlined by high-signal-intensity joint fluid. By demonstrating ACL and other extrameniscal lesions, MR imaging may help clarify the mechanisms of knee injury.

Adolescent↗
PubMed1988

Occult intraosseous fracture: detection with MR imaging.

Magnetic resonance (MR) images were retrospectively evaluated in eight patients who had recent, symptomatic knee injuries and in whom plain radiographs showed no fractures. T2-weighted images revealed irregular, intraosseous areas of high signal intensity; T1-weighted and proton density images revealed speckled or linear regions of low signal intensity in corresponding areas. In the seven patients whose injuries did not result from direct contusion, abnormalities occurred in subchondral locations. Two patients underwent bone scintigraphy, which showed increased activity in locations corresponding to areas of abnormality noted on MR images. Two patients underwent follow-up MR imaging at 6 weeks and 3 months, which showed complete resolution of the abnormalities. The authors speculate that the MR imaging findings represent microscopic compression fracture of trabecular bone and discuss the related entity, stress fracture.

Adolescent↗
PubMed1988

Stress fractures: MR imaging.

Five cases of stress fracture were studied with high-field-strength magnetic resonance (MR) imaging. In all cases, MR images showed bandlike areas of very low signal intensity in the intramedullary space, which were continuous with the cortex. These findings corresponded in location to the sites of fracture or new bone formation noted on radiographs. Surrounding areas of decreased signal intensity in the marrow space were also consistently seen on T1-weighted images. In three cases, prominent intramedullary areas of high signal intensity were noted on T2-weighted images obtained within 3 weeks of the onset of symptoms. Juxtacortical and/or subperiosteal areas of high signal intensity were also seen on T2-weighted images in two cases. Characteristic MR findings may distinguish stress fracture from occult intraosseous fracture.

Aged↗
PubMed1987

MR imaging of solitary osteochondromas: report of eight cases.

MR imaging was performed in eight patients with osteochondromas, and the results were compared with the histologic findings in six of these cases. MR imaging effectively showed the essential anatomic features of lesions and was particularly useful in assessing the presence and thickness of the cartilage cap. The cartilage cap was clearly seen as a region of high signal intensity on T2-weighted images. A superficial zone of low signal intensity was seen covering the cartilage cap, corresponding to an intact perichondrium, in all of the five cases in which histologic examination confirmed the presence of an intact perichondrium. The results of MR in these cases suggest that MR is useful in the preoperative planning of cases in which excision of an osteochondroma is necessary. Optimal surgical resection of the lesion requires complete excision of an intact perichondrium to prevent possible recurrence of the tumor.

Adolescent↗
PubMed1983

Multiple alleles and low variability of glycerol-3-phosphate dehydrogenase in Aedes albopictus (Diptera: Culicidae) from Peninsular Malaysia.

1. A total of 8 samples from three natural populations and a laboratory strain of Aedes albopictus were analysed for glycerol-3-phosphate dehydrogenase phenotypes by means of horizontal starch-gel electrophoresis. 2. The electrophoretic phenotypes were governed by three codominant Gpd alleles. 3. There was low variability, with the heterozygosity in the variable samples ranging from 0.02 to 0.12. 4. The commonest allele in all the population samples was GpdB which encoded an electrophoretic band with intermediate mobility. 5. There was no temporal or spatial variation.

Aedes↗
PubMedDate not supplied

Incidental magnetization transfer contrast in fast spin-echo imaging of cartilage.

In this article, the authors illustrate the contributions of incidental magnetization transfer contrast (MTC) to the signal characteristics of patellar cartilage on routine, multiplanar fast spin-echo (FSE) images. Incidental MTC diminishes the signal of patellar cartilage by 30% on routine FSE scans. Spectral fat saturation does not significantly increase incidental MTC on multislice FSE acquisitions. By increasing the contrast between synovial fluid and patellar cartilage, incidental MTC may account for greater conspicuousness of chondromalacia on FSE as compared to conventional spin-echo images. Incidental MTC may also alter or obscure the normal, laminar appearance of hyaline cartilage on short-TE, FSE images.

Cartilage, Articular↗
PubMedDate not supplied

Ex-vivo MR imaging of the cruciate ligaments.

Eight pairs of cruciate ligaments were obtained at autopsy for ex-vivo MR imaging. Image analysis demonstrated no differences in intrinsic signal characteristics between the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). Histologic examination showed no differences in ligament organization. These findings support the hypothesis that the normal signal intensity difference between the ACL and PCL noted on clinical images is due to a volume-averaging artifact.

Aged↗
PubMedDate not supplied

Epiphyseal growth arrest lines. MR findings.

We present two cases in which MR exams revealed unusual, low signal intensity lines in the marrow space of epiphyses. These epiphyseal lines were smooth and regular, creating a bone-in-bone appearance. These lines were much more conspicuous on MR than on radiographs, partly because of adjacent alterations in trabecular architecture. A history of prolonged immobilization during childhood in both cases suggests that these lines represent growth arrest lines persisting in the epiphyses.

Adult↗