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Biomedical subjects

D S Chan

Publications and source records attributed to D S Chan.

At least 19 recordsLinked to original sources
PubMed2006

A multi-centre randomized controlled trial comparing electrothermal arthroscopic capsulorrhaphy versus open inferior capsular shift for patients with shoulder instability: protocol implementation and interim performance: lessons learned from conducting a multi-centre RCT [ISRCTN68224911; NCT00251160].

BACKGROUND: The shoulder is the most frequently dislocated joint in the body. Multiple causes and pathologies account for the various types of shoulder instability. Multi-directional instability (MDI) and multi-directional laxity with antero-inferior instability (MDL-AII) are similar in pathology, less common and more difficult to treat. These instabilities are caused by ligamentous capsular redundancy. When non-operative management fails for these patients, quality of life is significantly impaired and surgical treatment is required to tighten the ligaments and joint capsule. The current reference (gold) standard treatment for MDI/MDL-AII is an open inferior capsular shift (ICS) surgical procedure. An alternative treatment involves arthroscopic thermal shrinkage of redundant capsular tissue to tighten the joint. However, there is a lack of scientific evidence to support the use of this technique called, electrothermal arthroscopic capsulorrhaphy (ETAC). This trial will compare the effectiveness of ETAC to open ICS in patients with MDI and MDL-AII, using patient-based quality of life outcome assessments. METHODS: This study is a multi-centre randomized clinical trial with a calculated sample size of 58 patients (p = 0.05, 80% power). Eligible patients are clinically diagnosed with MDI or MDL-AII and have failed standardized non-operative management. A diagnostic shoulder arthroscopy is performed to confirm eligibility, followed by intra-operative randomization to the ETAC or ICS surgical procedure. The primary outcome is the disease-specific quality of life questionnaire (Western Ontario Shoulder Instability Index), measured at baseline, 3, 6, 12 and 24 months. Secondary outcomes include shoulder-specific measures (American Shoulder and Elbow Surgeons Score and Constant Score). Other outcomes include recurrent instability, complications and operative time. The outcome measurements will be compared on an intention-to-treat basis, using two-sample independent t-tests to assess statistical significance. A Generalized Estimated Equations (GEE) analysis will determine whether there is an effect over time. DISCUSSION: This ongoing trial has encountered unexpected operational and practical issues, including slow patient enrollment due to high intra-operative exclusion rates. However, the authors have a greater understanding of multi-directional laxity in the shoulder and anticipate the results of this trial will provide the medical community with the best scientific clinical evidence on the efficacy of ETAC compared to open ICS.

Journal Article↗
PubMed2001

Multidisciplinary education and management program for children with asthma.

A multidisciplinary program for managing asthma in a pediatric population is discussed. A coordinated, multidisciplinary program for managing asthma in children was initiated in November 1997 at a U.S. Army medical center. The program, designed to improve care and decrease hospitalizations for asthma, was pharmacist managed and pulmonologist directed and was implemented by pediatricians. Patient education was provided by a pediatric clinical pharmacist or a nurse case manager; providers also received intensive education. Follow-up occurred at predetermined intervals and included asthma education, discussion of expectations and goals, analysis of metered-dose-inhaler and spacer technique, and assessment of compliance. Between November 1997 and January 1999, 210 inpatients were screened for asthma. One hundred seven were believed to have asthma and received inpatient asthma counseling and teaching. Of these 107 patients, 79 were enrolled in the program and monitored in the ambulatory care setting. Seventy-one (90%) of the 79 program enrollees were not rehospitalized during the ensuing two years. The number of children admitted to the hospital for asthma decreased from 147 in 1997 (a rate of 3.2 per 1000 population) to 93 in 1998 (2.1 per 1000) and to 87 in 1999 (1.9 per 1000). A multidisciplinary approach to the management of children with asthma may reduce hospitalizations of such patients.

Anti-Asthmatic Agents↗
PubMed2001

Combining qualitative and quantitative methods in assessing hospital learning environments.

Clinical education is a vital component in the curricula of pre-registration nursing courses and provides student nurses with the opportunity to combine cognitive, psychomotor, and affective skills. Clinical practice enables the student to develop competencies in the application of knowledge, skills, and attitudes to clinical field situations. It is, therefore, vital that the valuable clinical time be utilised effectively and productively. Nursing students' perception of the hospital learning environment were assessed by combining quantitative and qualitative approaches. The Clinical Learning Environment Inventory, based on the theoretical framework of learning environment studies, was developed and validated. The quantitative and qualitative findings reinforced each other. It was found that there were significant differences in students' perceptions of the actual clinical learning environment and their preferred learning environment. Generally, students preferred a more positive and favourable clinical environment than they perceived as being actually present.

Attitude of Health Personnel↗
PubMed2001

Trichosanthin interacts with acidic ribosomal proteins P0 and P1 and mitotic checkpoint protein MAD2B.

Trichosanthin is a ribosome-inactivating protein with multiple pharmacological properties. By a yeast two-hybrid system, ribosomal phosphoproteins P0 and P1 and a putative mitotic checkpoint protein, MAD2B, were found to interact with an active-site mutated trichosanthin (TCS). The interactions were verified by an in vitro binding assay of recombinant wild-type TCS and target proteins. The interaction domain of P0 was mapped to amino acids 220-273, which had been previously reported to be involved in the interaction with P1 and P2 in yeast. Consistent with our previous finding that the last seven residues of TCS are not essential for an active conformation, the same deletion did not affect the interaction with P0. Our present study suggests that TCS may disrupt the binding of elongation factors to the P-complex, in addition to the well-known N-glycosidase activity for ribosome inactivation.

Binding Sites↗
PubMed1999

Capped-porphyrin precursors.

In the crystalline state, 2-[3-(tosyloxy)propoxy]benzaldehyde [(I), C17H18O5S] exists in a U-shaped conformation. The benzaldehyde and toluene rings are nearly parallel. Crystals of 2-[2-(tosyloxy)ethoxy]-benzaldehyde occur with two habits. The X-ray structure determinations of these habits reveal an anhydrous form [(II), C16H16O5S] and a hemihydrated form [(III), C16H16O5S.0.5H2O]. In (III), a water molecule bridges two carbonyl functions [O6...O1 2.87 (1) A]. 1,2,4,5-Tetrakis{2-[2-(1,3-dioxolan-2-yl)-phenoxy]ethoxy} benzene [(IV), C50H54O16] was prepared by protecting the aldehyde function of (II) or (III) with ethylene glycol and reacting the resulting compound with 1,2,4,5-tetrahydroxybenzene. Compound (IV) has 1 symmetry.

Crystallization↗
PubMed1998

Prospective randomized double blind placebo-controlled evaluation of azithromycin for treatment of cat-scratch disease.

OBJECTIVE: To determine the efficacy of azithromycin in the treatment of patients with typical cat-scratch disease. DESIGN: Prospective, randomized, double blind, placebo-controlled clinical trial. SETTING: Large military medical center and its referring clinics. PATIENTS: Active duty military members and their dependents with laboratory-confirmed, clinically typical cat-scratch disease. INTERVENTION: Study participants assigned by randomization to treatment with oral azithromycin or placebo for 5 days. OUTCOME MEASURES: Lymph node volume was calculated using three dimensional ultrasonography at entry and at weekly intervals. The ultrasonographer was blinded to the treatment groups. Endpoint evaluations were predetermined as time in days to 80% resolution of the initial total lymph node volume. RESULTS: Demographic and clinical data showed that the azithromycin and placebo treatment groups were comparable at entry although the placebo group tended to be older. Eighty percent decrease of initial lymph node volume was documented in 7 of 14 azithromycin-treated patients compared with 1 of 15 placebo-treated controls during the first 30 days of observation (P = 0.026). After 30 days there was no significant difference in rate or degree of resolution between the two groups. CONCLUSIONS: Treatment of patients with typical cat-scratch disease with oral azithromycin for five days affords significant clinical benefit as measured by total decrease in lymph node volume within the first month of treatment.

Adolescent↗
PubMed1996

Antimicrobial liquid formulations: a blind taste comparison of three brands of penicillin VK and three brands of amoxicillin.

OBJECTIVE: To rate the perception of taste, texture, smell and aftertaste of various brands of penicillin VK and amoxicillin. DESIGN: Oral, liquid formulations of three brands of penicillin VK (PenVee K, V-Cillin-K, VeeTids) and three brands of amoxicillin (Amoxil, Trimox, Wymox) were evaluated for smell, texture, taste, and aftertaste by 30 volunteers in a blind study. Each category was scored on a scale of 1 to 5. The order in which the drugs were sampled was randomized for the first three groups of five participants. The order then was reversed for the remaining three groups of participants. SETTING: A 537-bed US Army teaching hospital. PARTICIPANTS: Participants included 30 healthy adult volunteers from the Departments of Pediatrics, Nursing, and Pharmacy. MAIN OUTCOME MEASURES: Drugs received cumulative scores in each category, as well as an overall total score ranking. The data were analyzed using one-way ANOVA for repeated measures with a post hoc Duncan's multiple range test to determine significant differences between individual means. RESULTS: Overall, Trimox and Amoxil scored significantly higher than the remaining drugs. Although V-Cillin-K scored highest in the smell category, its score was significantly below those of Trimox and Amoxil in the texture, taste, aftertaste, and overall categories. Overall, the three penicillin VK solutions scored lower than the three amoxicillin suspensions, with PenVee K ranking the lowest. Among the penicillin VK solutions, V-Cillin-K scored significantly higher overall than the other two penicillin VK solutions. CONCLUSIONS: Overall, all three amoxicillin oral, liquid suspensions that were studied scored significantly better than the three penicillin VK solutions.

Adult↗
PubMed1994

Antimicrobial drug suspensions: a blinded comparison of taste of twelve common pediatric drugs including cefixime, cefpodoxime, cefprozil and loracarbef.

We conducted a blinded taste test evaluating 12 antimicrobial suspensions by smell, texture, taste, aftertaste and overall acceptance. Drugs received cumulative scores in each category as well as a total score ranking. Overall Lorabid scored highest but not significantly higher than Keflex, Suprax and Ceclor, all of which score higher than the other test drugs. Cefzil and Augmentin scored just below this group of drugs and higher than all other test drugs. Vantin was inferior to these drugs primarily because of its low score in aftertaste. It was ranked along with V-Cillin-K, Veetids, Sulfatrim and Pediazole, the lowest scoring group of drugs other than Dynapen which scored lower than all other test drugs. No difference overall was detected between the two penicillin VK suspensions evaluated, V-Cillin-K and Veetids.

Analysis of Variance↗
PubMed1984

Local anesthetics can interact electrostatically with membrane proteins.

The fluorescent probe 1-anilinonaphthalene 8-sulfonate was used to examine the binding of spin-labeled local anesthetics to lipid model systems, to the membranes of human red blood cells, and rabbit sarcoplasmic reticulum. 1-Anilinonaphthalene 8-sulfonate exhibits two distinct fluorescent lifetimes when bound to these biological membranes. The shorter lifetime represents the probe associated with the purely lipid region while the longer lifetime is associated with the protein region. The spin-labeled local anesthetic quenches the fluorescence of both of these components as indicated by the decrease in the lifetimes. Since nitroxide free radicals are known to quench fluorophores upon 'contract', the results reflect the relative interaction of local anesthetics with membrane lipids and proteins. The evidence is consistent with the concept of multiple binding sites for local anesthetics in membranes. Local anesthetics, once intercalated into the bilayer, may diffuse laterally and interact with membrane components, lipid as well as proteins. In biological membranes, however, positively charged local anesthetics are better able to quench 1-anilinonaphthalene 8-sulfonate in protein regions, suggesting that the interaction between local anesthetics and membrane proteins can be electrostatic in nature.

Anesthetics, Local↗