Biomedical subjects

Albert Leung

Publications and source records attributed to Albert Leung.

4 recordsLinked to original sources

PubMed2005

The effect of Ting point (tendinomuscular meridians) electroacupuncture on thermal pain: a model for studying the neuronal mechanism of acupuncture analgesia.

OBJECTIVE: The aim of this study was to characterize the role of Ting points (TP) in acute pain management and its potential use in functional imaging studies by quantitatively assessing: (1) the change in peripheral thermal thresholds before and after the electroacupuncture (EA); and (2) the corresponding behavioral feedback of thermal pain stimulation and the de qi sensation of EA. DESIGN: The study design was prospective. SETTINGS/LOCATION: Healthy subjects were recruited for the study at the University of California, San Diego Medical Center. SUBJECTS/INTERVENTIONS: Thirteen (13) healthy subjects were studied. Baseline thermal thresholds (cold and warm sensations and cold and hot pain) were measured at premarked testing sites along the medial aspects of bilateral lower extremities. Five (5) seconds of hot pain (HP) was delivered to the testing sites and the corresponding pain visual analog scale (VAS) scores were recorded. Thirty (30) seconds of EA was delivered via the SP1 and LR1 on the left lower extremities at 5 Hz via a 6-V square-wave stimulator. OUTCOME MEASURES: The VAS scores of the HP and de qi sensation (tingling) during the EA were recorded. The thermal thresholds and VAS scores for the HP and de qi were obtained immediately and both 30 and 60 minutes after the EA. Adaptation testing was also carried out to assess the change in thermal thresholds and the VAS scores of HP without EA. RESULTS: The warm thresholds of bilateral medial calves significantly increased (p < 0.01) after 30 seconds of EA stimulation. The HP VAS score reduced significantly at the ipsilateral calf during EA in comparison to preacupuncture and postacupuncture (p < 0.01) measurements. No significant change in thermal thresholds was noted in the adaptation paradigm. CONCLUSIONS: EA at the TP has an inhibitory effect on the C-fiber afferents. The analgesic benefit observed is most likely A-delta afferent mediated. Further correlation studies in functional imaging may provide defining data for the observed analgesic mechanism.

Acupuncture Analgesia↗

PubMed2004

Dynamic integration of gene annotation and its application to microarray analysis.

Comprehensive and structured annotations for all genes on a microarray chip are essential for the interpretation of its expression data. Currently, most chip gene annotations are one-line free text descriptions that are often partial, outdated and unsuitable for large-scale data analysis. Therefore the interpretation of microarray gene expression clusters is often limited. Although researchers can manually navigate a collection of databases for better annotations, it is only practical for limited number of genes. Existing meta-databases fail to provide comprehensive categorized annotations for hundreds of genes simultaneously. We have developed an automatic system to address this issue. GeneView system monitors various data sources, extracts gene information from a source whenever it is updated, comprehensively matches genes, and integrates them into a central database by categories, such as pathway, genetic mapping, phenotype, expression profile, domain structure, protein interaction, disease association, and references. The system consists of four major components: (1) relational database; (2) data processing; (3) user curation; (4) data query. We evaluated it by analyzing genes on cDNA and Affymetrix Oligo chips. In both cases, the system provided more accurate and comprehensive information than those provided by the vendors or the chip users, and helped identify new common functions among genes in the same expression clusters.

Cluster Analysis↗

PubMed2002

The upper GI safety and tolerability of oral alendronate at a dose of 70 milligrams once weekly: a placebo-controlled endoscopy study.

OBJECTIVE: Alendronate (10 mg daily) has been shown in long term clinical trials to be an effective treatment for postmenopausal osteoporosis. A weekly dosing regimen of alendronate is preferred by both patients and physicians, as it has the potential to provide greater convenience and enhance compliance. In a 1-yr clinical trial, alendronate (70 mg once weekly) was equally efficacious and at least as well tolerated as the 10-mg daily dose in the treatment of postmenopausal osteoporosis, despite the higher unit dosage required. We conducted a randomized, double blind, placebo- and active-controlled endoscopy study to confirm the results of this clinical trial. We hypothesized that mean endoscopic gastric erosion scores would be similar in subjects receiving alendronate (70 mg once weekly) and those receiving a placebo. METHODS: Two hundred seventy-seven subjects (90 men and 187 women) were randomized to one of three treatment groups: 1) alendronate (70 mg once weekly) for 10 wk (N = 126), 2) placebo (once weekly) for 10 wk (N = 126), or 3) placebo (once weekly) for 10 wk followed by aspirin (650 mg q.i.d.) for the last week as the positive control (N = 25). Esophagogastroduodenoscopy was performed 5 to 7 days after the last dose of alendronate or matching placebo. RESULTS: The mean gastric erosion scores (Lanza scale) were similar in subjects given alendronate (70 mg once weekly) and those given a placebo (0.32 vs 0.35, respectively; 95% CI for difference = -0.22-0.16, p = 0.75), whereas scores in both groups were significantly lower than in those given aspirin (3.09; p < 0.001). Endoscopic gastroduodenal ulcers occurred in no alendronate (0%), two placebo (1.7%), and five aspirin (23.8%) subjects. The mean erosion scores in the esophagus and duodenum of alendronate and placebo subjects were also similar. The incidences of upper GI symptoms were similar in the alendronate and placebo subjects and did not suggest a relationship with endoscopic lesions. CONCLUSIONS: Alendronate (70 mg once weekly) was not associated with any increase in endoscopic lesions in the upper GI tract relative to a placebo.

Administration, Oral↗

PubMed2002

Concentration-effect relationships for intravenous alfentanil and ketamine infusions in human volunteers: effects on acute thresholds and capsaicin-evoked hyperpathia.

The authors have extended preclinical studies on pain to human volunteers by examining the effects of intravenous alfentanil and ketamine on acute sensory thresholds andfacilitated processing induced by intradermal capsaicin. Eleven healthy subjects received targeted plasma concentrations of alfentanil, ketamine, and placebo followed by neurosensory testing (thermal and von Frey hair thresholds). After completing the tests at the highest plasma level, intradermal capsaicin was injected into the volar aspect of the left forearm, and the flare response and hyperalgesia to von Frey hair, stroking, and heat were assessed. Alfentanil significantly elevated cool and warm thresholds and decreased capsaicin-induced stroking hyperalgesia. Ketamine significantly decreased capsaicin-induced von Frey hair hyperalgesia. Both drugs resulted in a significant elevation of von Frey hair-induced pain thresholds and a decrease in capsaicin-induced pain. These studies suggest that experimental human pain models may be used to study analgesic pharmacology and may serve as important methods for defining the analgesic efficacy of drugs in phase I clinical trials.

Adult↗