Biomedical subjects

Wing-Sze Lee

Publications and source records attributed to Wing-Sze Lee.

4 recordsLinked to original sources

PubMed2006

The application of capillary electrophoresis for enantiomeric separation of N,N-dimethylamphetamine and its related analogs: intelligence study on N,N-dimethylamphetamine samples in crystalline and tablet forms.

This paper reports a new capillary zone electrophoresis method for the simultaneous chiral determination of the enantiomers of N,N-dimethylamphetamine (DMA), methamphetamine (MA), ephedrine (E), pseudoephedrine (PE) and methylephedrine (Me-E). In this study, a number of electophoretic parameters were examined and optimized including the choice of chiral selectors, the use of short-chain tetraalkylammonium cations, the effect of chiral selector concentration, buffer concentration, applied voltage and capillary temperature. Heptakis(2,6-di-O-methyl)-beta-cyclodextrin (DM-beta-CD) and tetrabutylammonium (TBA) being the best chiral selector and buffer cation, respectively, the optimized electrophoretic conditions were found to be: 20 mM DM-beta-CD, 50 mM TBAPO(4) at pH 2.5, applied voltage at 30 kV and temperature at 25 degrees C. Under the optimized conditions, all analytes were well separated with resolution factors between 3.3 and 24.0 achieved. Using phentermine as an internal standard, the intra-day (n=8) precisions for the relative migration times and peak areas of all analytes were below 1.09%, while the inter-day precisions (n=12, 6 days) for the relative migration times and peak areas of all analytes were under 3.77%. This method has been applied to the measurement of the enantiomeric purities of the seized DMA samples. The result of the measurement could provide important clues about the possible synthetic pathways of these samples.

Journal Article↗

PubMed2006

Age-associated decrease of type IIA/B human skeletal muscle fibers.

Elderly individuals often fall because of poor muscle strength and reduced balancing ability related to muscle aging. However, it is unclear whether changes in muscle fiber types contribute to poor strength or imbalance. We studied age- associated changes in human skeletal muscle fibers using muscle biopsy specimens taken from 65 male and female Chinese patients aged 17-96 years. The muscle specimens were cryosectioned with alkaline triphosphatase staining at pH 4.4, followed by image analysis. We analyzed morphologic observations and performed quantitative analyses of the number, size, and area percentage of different types of skeletal muscle fibers and connective tissues. Types IIA and IIB muscle fibers decreased with age in the area percentage, fiber number percentage, and mean fiber area, whereas Type I fibers increased in area and number but not in size. Morphologically, Type II fibers appeared smaller and flatter. Our findings suggest deterioration in muscle quality and balancing coordination in elderly patients. We provide data to help determine treatments for reversing muscle fiber changes and reducing the number of falls and related fractures in patients.

Accidental Falls↗

PubMed2004

Complex tibial fracture outcomes following treatment with low-intensity pulsed ultrasound.

A clinical study was conducted to investigate the effect of low-intensity pulsed ultrasound (US) stimulation (LIPUS) on the healing of complex tibial fractures. Thirty complex tibial fractures were randomly assigned to the treatment with LIPUS (n = 16) or by a dummy machine (sham-exposed: n = 14). The fractures were immobilized by either internal or external fixations according to the clinical indications. LIPUS was given 20 min/day for 90 days. Fracture healing was monitored by clinical, radiological, densitometric and biochemical assessments. The LIPUS-treated group showed statistically significantly better healing, as demonstrated by all assessments. Complications were minimal in the LIPUS group. There were two cases of delayed union, with one in each group. There were two cases of infection in the control group. The delayed-union cases were subsequently treated by LIPUS and the infection cases were treated with standard protocol. Fracture healing in these patients was again treated by LIPUS.

Adult↗

PubMed2004

Lack of efficacy of low-intensity pulsed ultrasound on prevention of postmenopausal bone loss evaluated at the distal radius in older Chinese women.

A within-subject, randomized, and prospective intervention trial was done to evaluate the potential effect of low-intensity pulsed ultrasound on prevention of postmenopausal bone loss. Twenty healthy postmenopausal women between the ages of 51-81 years met the inclusion criteria. The treatment hand was randomly selected, and the contralateral site served as a control. Integral and trabecular bone mineral density were measured using highly precise multilayer peripheral quantitative computed tomography at the bilateral distal radius at baseline, 3 months after daily low-intensity pulsed ultrasound treatment, and 3 months after discontinuing treatment. Results showed that the rate of bone change (trabecular bone mineral density and integral bone mineral density) did not significantly differ between the site treated with low-intensity pulsed ultrasound and the contralateral control at either followup. Also, during the followup, bone mineral density did not change significantly in the contralateral control site. This was the first prospective and randomized study to show that low-intensity pulsed ultrasound at the current regime did not have significant effects on intact bone for prevention of postmenopausal bone loss in the distal radii of older Chinese women.

Aged↗