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Biomedical subjects

M Yeung

Publications and source records attributed to M Yeung.

27 records · Page 2Linked to original sources
PubMed1992

Increased contraction and inositol phosphate formation of tracheal smooth muscle from hyperresponsive guinea pigs.

Tracheal smooth muscle from guinea pigs with documented airway hyperresponsiveness in vivo after multiple antigen challenges produced 30% to 50% greater force than tracheas from control guinea pigs, when stimulated with carbachol, histamine, or leukotriene D4. When cultured smooth muscle cells were incubated with myo[2-3H]inositol, basal uptake of [3H]inositol was similar in cells from normal and hyperresponsive guinea pigs, but when these cells were stimulated with contractile agonists, there was increased uptake of inositol in hyperresponsive cells. Analysis of inositol phosphates by column chromatography and high-performance liquid chromatography revealed the presence of inositol-1,4,5-triphosphate, inositol-1,3,4-trisphosphate, inositol-1,4-bisphosphate, and inositol-1-monophosphate. The release of inositol-1,4,5-triphosphate, inositol-1,4-biphosphate, and inositol-1-monophosphate by smooth muscle cells stimulated with carbachol, leukotriene D4, or histamine was 20% to 40% greater in cells derived from hyperresponsive animals than cells from normal animals. These data demonstrate that the increased muscle contraction of hyperresponsive guinea pig tracheas is associated with increased inositol phosphate metabolism in these cells. Delineating the mechanisms of airway smooth muscle contraction should provide new pharmacologic targets for the inhibition of bronchoconstriction in asthma.

Animals↗
PubMed1992

The use of an abdominal compression belt to reduce stone movement during extracorporeal shock wave lithotripsy.

We used an abdominal compression belt in 50 patients undergoing extracorporeal shock wave lithotripsy with the Siemens Lithostar lithotriptor to limit diaphragmatic excursion and, therefore, renal calculus movement. Stone movement was measured on the monitor with and without the compression belt. Abdominal compression was found to decrease the range of stone movement by an average of 32% (-4 to 63%). This technique was less effective in patients with limited chest expansion. Abdominal compression was also found to be useful during treatment of renal and upper ureteral stones in reducing overall patient movement. The decreased stone movement during extracorporeal shock wave lithotripsy with abdominal compression may increase stone fragmentation and may decrease the number of shocks per treatment.

Humans↗
PubMed1987

Detection of prostaglandins by high-performance liquid chromatography after conversion to p-(9-anthroyloxy)phenacyl esters.

p-(9-Anthroyloxy)phenacyl bromide (panacyl bromide) undergoes rapid reaction with the carboxyl group of prostaglandins in the presence of N,N-diisopropylethylamine in acetonitrile-tetrahydrofuran (4:1). The resulting prostaglandin panacyl esters are strongly uv absorbing with a lambda max at 253 nm and an epsilon of 174,280 in acetonitrile. The lower limit of detection of prostaglandins was approximately 200 pg with uv detection (254 nm) and about 30 pg with fluorescent detection (exitation 253 and emission 445 nm) using normal-phase HPLC. The reactivity of panacyl bromide with 23 prostaglandins as well as prostaglandins released by human lung tissues was investigated.

Chemical Phenomena↗
PubMed1985

Determinants of changes in FEV1 over a workshift.

Measurement of workshift change in FEV1 is a useful predictor of respiratory disease among cotton workers and grainhandlers. Certain factors affect this measurement and must be considered in the analysis. Response varies with the time of day at which the measurement is taken. Tobacco smoking, immediate skin reactivity to common allergens, age, and initial level of FEV1 are other factors that must be considered when this measurement is used to study effects of occupational exposure to respiratory hazards.

Adult↗
PubMedDate not supplied

Metabolic bone disease in patients receiving home parenteral nutrition: a Canadian study and review.

BACKGROUND: Metabolic bone disease (MBD) is a significant complication in patients receiving long-term home parenteral nutrition (HPN). Pamidronate has been poorly studied in this population. We examine the prevalence and risk factors for MBD and examine changes in bone mineral density (BMD) after pamidronate administration. METHODS: First, a chart review of patients receiving HPN for >1 year was performed, and Pearson correlations were used to assess associations between MBD (defined as t score<-1) and risk factors. Second, the effect of IV pamidronate on BMD was studied prospectively in 11 HPN patients. Results were compared using a t-test. RESULTS: Charts were reviewed in 25 patients (15 F, 10 M): age, 56.9+/-3.1 years; body mass index (BMI), 21.2+/-0.57 kg/m2; months receiving HPN, 113.2+/-0.09; and days per week receiving HPN, 5.08+/-0.39. MBD was present in 33% of patients for the spine and hip and in 50% for the femoral neck; 24% had previous fractures. There was a significant negative correlation between the duration of HPN and BMD (r=-0.40) for all measurements. From those patients, 11 received IV pamidronate for a mean of 22.2+/-5.4 months. At baseline, their mean HPN treatment duration was 10.6+/-6.3 years. Overall, BMD results showed a trend toward improvement in the mean t score of the spine and hip postpamidronate therapy (pre, -3.1+/-0.75; post, -2.9+/-0.69; p=.07). After excluding 2 patients receiving corticosteroids, the mean t score of the spine showed significant improvement (prepamidronate -3.4+/-0.57 vs post-pamidronate -3.1+/-0.65, p=.036). CONCLUSIONS: In our HPN population, 76% had MBD and 24% had previous fractures. The results suggest that these patients may benefit from pamidronate. More studies are needed to assess the efficacy of pamidronate.

Bone Density↗