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Biomedical subjects

E S Chan

Publications and source records attributed to E S Chan.

At least 19 recordsLinked to original sources
PubMed2001

Epinephrine for the out-of-hospital (first-aid) treatment of anaphylaxis in infants: is the ampule/syringe/needle method practical?

BACKGROUND: Little information is available about administration of an accurate epinephrine dose to infants experiencing anaphylaxis outside the hospital setting. OBJECTIVE: Our purpose was to perform a prospective, controlled study of (1) the time needed by parents to draw up an infant epinephrine dose from an ampule and (2) the dose accuracy. METHODS: We gave 18 parents written instructions and asked them to draw up epinephrine 0.09 mL. We timed them by means of a stopwatch and measured the epinephrine content (in micrograms) in each dose by using HPLC-UV. Eighteen resident physicians, 18 general duty nurses, and 18 emergency department nurses served as controls. RESULTS: The parents took significantly longer (P < .05) than the controls to draw up the dose; the mean (+/- SEM) times were 142 +/- 13 seconds (range, 83-248) for the parents, 52 +/- 3 seconds (range, 30-83) for the physicians, 40 +/- 2 seconds (range, 26-71) for the general duty nurses, and 29 +/- 0.09 seconds (range, 27-33) for the emergency department nurses. The control groups did not differ significantly from each other in speed (P > .05). The epinephrine content of the doses drawn up by the parents ranged 40-fold in contrast to the physicians' doses (7- to 8-fold), general duty nurses' doses (3-fold), and emergency department nurses' doses (2-fold). The mean epinephrine content did not differ significantly (P > .05) among the 4 groups. CONCLUSIONS: Most parents were unable to draw up an infant epinephrine dose rapidly or accurately. Most health care professionals drew up the dose rapidly; however, their accuracy was compromised by inherent variations of epinephrine concentrations in the ampules (United States Pharmacopeia compendial limits, 90% to 115%) and the inherent difficulty of measuring low volumes (<0.1 mL) of epinephrine. User-friendly premeasured epinephrine doses suitable for infants should be developed.

Anaphylaxis↗
PubMed2001

Dermal fibroblasts do not enhance the graft take rate of autologous, cultured keratinocyte suspension on full-thickness wounds in rats.

Dermal fibroblasts are known to play an important role in wound healing. In this study, cultured autologous keratinocyte suspension was applied with fibrin glue to the full-thickness wounds in rats (N = 20). Histological analysis on day 14 showed regenerated epithelium in 10 wounds (50%). Keratinocytes were also premixed with allogeneic dermal fibroblasts in a ratio of 3:1 and 5:1 before application to other full-thickness wounds (N = 20) with fibrin glue. Regeneration of epithelium was observed in 10 (50%) and 9 (45%) wounds respectively. Acute inflammatory reaction and mild to moderate proliferation of fibroblasts in the subepithelial layer of the allogeneic fibroblasts were noted. The addition of dermal fibroblasts to keratinocytes/fibrin glue does not enhance the take rate of the cultured keratinocyte suspension.

Animals↗
PubMed2001

A new technique to resurface wounds with composite biocompatible epidermal graft and artificial skin.

BACKGROUND: The incorporation of cultured epidermal autograft on the neodermis of artificial skin (Integra, Integra LifeSciences, Plainsboro, NJ) has been met with some difficulties. A new engraftment technique to resurface the wounds with Integra and composite biocompatible epidermal graft (CBEG) has been successfully applied on three patients for elective reconstructive procedures. METHODS: A small skin biopsy was taken from the normal edge of the lesion for keratinocytes and dermal fibroblast cultures 2 weeks before surgery. When sufficient cells were grown, the patient was admitted for the excision of the lesions or scars. The wounds of the patients, ranging from 125 to 250 cm2, were covered with Integra. When the neodermis of the Integra was fully vascularized, the silicone membrane of the Integra was removed and replaced with the CBEG, which consisted of autologous keratinocytes cultivated on a hyaluronate-derived membrane (Laserskin; Fidia Advanced Biopolymers, Abano Terme, Italy)) using human dermal fibroblasts as a feeder layer. RESULTS: Clinically, there was good initial "take" of the CBEGs in these three patients, ranging from 50% to 100%. Biopsy specimens of the grafted wounds were taken 1 to 3 weeks after the application of the CBEGs. Epithelialization was noted in all patients. CONCLUSION: This engraftment technique has several advantages. The CBEG is much easier to handle than the conventional cultured epidermal autograft. It eliminates the invasive second procedure for skin harvesting, with resulting pain and scarring. The application of the CBEG can be easily performed at the bedside.

Adolescent↗
PubMed2001

Immune complexes and IFN-gamma decrease cholesterol 27-hydroxylase in human arterial endothelium and macrophages.

The enzyme cholesterol 27-hydroxylase, expressed by arterial endothelium and monocytes/macrophages, is one of the first lines of defense against the development of atherosclerosis. By catalyzing the hydroxylation of cholesterol to 27-hydroxycholesterol, which is more soluble in aqueous medium, the enzyme promotes the removal of cholesterol from the arterial wall. Prior studies have suggested that immune reactants play a role in the pathogenesis of atherosclerosis; we report here that immune reactants, IFN-gamma and immune complexes bound to C1q, but not interleukin-1 and tumor necrosis factor, diminish the expression of cholesterol 27-hydroxylase in human aortic endothelial cells, peripheral blood mononuclear cells, monocyte-derived macrophages, and the human monocytoid cell line THP-1. In addition, our studies demonstrate that immune complexes down-regulate cholesterol 27-hydroxylase only after complement fixation via interaction with the 126-kD C1qRp protein on endothelial cells and THP-1 cells. These results are consistent with the prior demonstration that IFN-gamma contributes to the pathogenesis of atherosclerosis and suggest a role for C1q receptors in the atherogenic process. Moreover, these observations suggest that one mechanism by which immune reactants contribute to the development of atherosclerosis is by down-regulating the expression of the enzymes required to maintain cholesterol homeostasis in the arterial wall.

Antigen-Antibody Complex↗
PubMed2001

In vitro inhibition of head and neck cancer-cell growth by human recombinant interferon-alpha and 13-cis retinoic acid.

Three nasopharyngeal carcinoma (NPC) cell lines (CNE-1, CNE-2 and NPC/HK-1), two squamous cell carcinoma (SCC) cell lines (T2/CUHK and PWH-S1) and six head and neck cancer specimens (NPC [n = 4], SCC tongue [n = 1] and a thyroid cancer [n = 1]) were incubated with interferon (IFN)-alpha (5 x 10(4) iu/mL) and/or 13-cis retinoic acid (13RA; 10(-5) mol/L) for two days at 37 degrees C. In vitro chemosensitivity was measured using MTT assay. Mild growth inhibition of the five cell lines by IFN-alpha ranged from 7.1% to 51.8% (mean: 18.5%), whereas with 13RA it was zero to 19.7% (mean: 7%). Greater inhibition (14.8-51.0%, mean: 31.8%) was achieved when the two drugs were used in combination. Growth inhibition of the six surgical specimens ranged from 6.9% to 21% (mean: 13.6%) with IFN-alpha; zero to 10.3% (mean: 6.0%) with 13RA; and 6.6-26.5% (mean: 17.7%) when the two agents were combined. Four of the 11 samples showed synergistic antitumour effect when IFN-alpha and 13RA were combined, and six showed subadditive effect. The results show that IFN-alpha and 13RA have a mild in vitro antitumour effect on head and neck cancer cells, and the drug synergistic effect demonstrated in this study suggests that the two agents should be used in combination in clinical application.

Antineoplastic Agents↗
PubMed2000

Interventions for treating oral lichen planus.

BACKGROUND: Oral lichen planus is a chronic autoimmune disease of unknown aetiology that affects the inner surface of the mouth. The symptomatic forms are painful,tend to worsen with age and with remissions being rare. Current treatment is palliative and not curative, many topical and systemic agents have been tried with little hard evidence for efficacy. OBJECTIVES: To assess the effectiveness and safety of any form of palliative therapy against placebo for the treatment of symptomatic oral lichen planus. SEARCH STRATEGY: Electronic databases, handsearching of conference proceedings and specific journals, researchers in the field, drug manufacturers. SELECTION CRITERIA: Any placebo-controlled trial of palliative therapy for symptomatic oral lichen planus, using a randomised or quasi-randomised design that measured changes in symptoms and/or clinical signs. DATA COLLECTION AND ANALYSIS: Change in symptoms (pain, discomfort) and clinical signs (visual impression, lesion measurements) at the end of therapy. Odds ratio of improvement vs no improvement for each trial outcome and pooling where appropriate. MAIN RESULTS: A total of nine RCTs were identified. The nine interventions were grouped into four separate classes (cyclosporines, retinoids, steroids and phototherapy) for comparison. No therapy was replicated exactly, the closest replication involved two trials using high and low dose cyclosporine mouthwash. Only trials recording the same outcomes in each therapeutic class were pooled. The largest number of pooled trials was three. Large odds ratios with very wide confidence intervals indicating a statistically significant treatment benefit were seen in all trials. However this has to be tempered by considerations of the small study sizes, the lack of replication, the difficulty in measuring outcome changes and the very high likelihood of publication bias. Only systemic agents were associated with treatment toxicities, all other side-effects were mild and mainly limited to local mucosal reactions. REVIEWER'S CONCLUSIONS: The review provides only weak evidence for the superiority of the assessed interventions over placebo for palliation of symptomatic OLP. The results highlight the need for larger placebo-controlled RCTs with more carefully selected and standardised outcome measures before between-treatment comparisons can be properly interpreted.

Cyclosporins↗
PubMed2000

Neoadjuvant and adjuvant therapy for operable hepatocellular carcinoma.

OBJECTIVES: To determine the efficacy and adverse effects of different neoadjuvant and adjuvant therapies compared to surgery alone or surgery and placebo/supportive therapy when given to improve relapse and survival rates for operable hepatocellular carcinoma. SEARCH STRATEGY: Electronic databases, conference proceedings, bibliographies of identified publications. SELECTION CRITERIA: All truly randomised and quasi-randomised clinical trials that compared hepatocellular carcinoma patients who were given and not given neoadjuvant/adjuvant therapy as a supplement to curative liver resection. DATA COLLECTION AND ANALYSIS: Study data was extracted independently by two reviewers and discrepancies were resolved by consensus. A total of eight randomised controlled clinical trials were identified, totaling 548 randomised patients. Seven of the eight trials reported survival and disease-free survival curves and the results of hypothesis testing (log-rank test). The remaining trial reported only the mean survival times. None reported the hazard ratio and only one did a sample size calculation. The survival and disease-free survival curves were compared using their one, two and three-year survival rates, median survival times and the result of the hypothesis tests. MAIN RESULTS: The size of the randomised clinical trials ranged from 40 to 115 subjects. Both preoperative (neoadjuvant) and postoperative (adjuvant), systemic and locoregional (+/- embolization), chemo- and immunotherapy interventions were tested. None were comparable in terms of both treatment regimen and participants selected, so no pooling was done. Only one regimen using preoperative transcatheter arterial chemoembolization with doxorubicin was approximately duplicated. Seven of the eight trials reported no survival benefit from adjuvant therapy. Only one trial reported a statistically significant difference for survival and disease-free survival for the treatment arm, but the results of both its arms were very poor when compared to other studies. Two of the trials that did not report any absolute survival advantage reported statistically significant differences in disease-free survival. Five of the eight trials did not perform intention-to-treat analysis. The highest toxicity rate was in a trial using oral 1-hexylcarbamoyl 5-fluorouracil which resulted in 12 out of 38 subjects stopping because of adverse events. REVIEWER'S CONCLUSIONS: There is no evidence for efficacy of any of the adjuvant protocols reviewed. In order to detect a realistic treatment advantage, larger trials will have to be conducted.

Antineoplastic Agents↗
PubMed2000

The effects of hydrocolloid dressing and gentian violet on radiation-induced moist desquamation wound healing.

The aim of the study was to compare the effect of a gentian violet topical application with that of a moist dressing (hydrocolloid) on the rate and efficacy of radiotherapy-induced moist desquamation wound healing and the patients' satisfaction level with each method. This prospective randomized clinical trial used a stratified sampling design. A sample of 39 patients with 60 wounds had their wounds assessed on alternate days in terms of several wound-healing parameters including wound size, wound pain, incidence of infection, and time required for healing. Patient satisfaction with each treatment was evaluated at the completion of the study. Gentian violet significantly decreased wound size and reduced wound pain. However, this treatment received significantly lower ratings for dressing comfort and dressing aesthetic acceptance. Nevertheless, the time required for healing was not statistically different in the two groups. These findings suggest that the lower score of dressing satisfaction level in the gentian violet group may result from the skin discoloration and drying effects of the treatment, which renders patients unable to move or stretch their skin. Although the aim is to have complete wound healing, this may not be realistic for many lesions such as radiotherapy-induced moist desquamation wounds. The best evidence on which to make decisions about individual care can now be based on patients' own perception of quality.

Analysis of Variance↗
PubMed2000

Failure patterns and factors affecting prognosis of salivary gland carcinoma: retrospective study.

OBJECTIVES: To investigate the failure patterns and the prognostic factors following postoperative radiotherapy for salivary gland carcinoma. DESIGN: Retrospective study. SETTING: University teaching hospital, Hong Kong. PATIENTS: Fifty patients who had non-disseminated salivary gland carcinoma and who received primary treatment from 1984 through 1993. MAIN OUTCOME MEASURES: Demographic data, cancer T- and N-stages, histological type, site of origin, completeness of surgery, whether postoperative radiotherapy was given, and the clinical outcome. RESULTS: Two (4%) patients had been treated with radiotherapy alone, six (12%) had undergone radical resection alone, and 42 (84%) had been radically treated by using both modalities. The 5-year overall survival and relapse-free survival rates were 78.4% and 63.1%, respectively. The free from local failure and free from distant metastasis rates at 5 years were 77.2% and 72.8%, respectively. The N-stage was a significant prognostic factor. The site of the primary tumour, T-stage, completeness of surgery, and use of postoperative radiotherapy were not significant independent prognosticators; however, among the T-stage tumours, the b-substage carcinomas had significantly fewer local failures (P=0.040) and better survival rates (P=0.038) than the a-substage carcinomas. There were seven (14%) locoregional failures without distant metastasis, seven (14%) cases of distant metastasis without locoregional failures, and four (8%) locoregional failures preceding distant metastasis; isolated regional relapse was rare (1/50; 2%). All regional failures (5/50; 10%) occurred ipsilateral to the primary lesion. There were no deaths due to lymphoepithelioma-like carcinoma or acinic cell carcinoma. CONCLUSIONS: The N-stage is the main prognostic factor of overall survival, relapse- and metastasis-free recovery, and success of treatment for salivary gland carcinoma. Optimal locoregional treatment can help reduce distant metastasis, and the maximal use of postoperative radiotherapy may contribute to improved locoregional control. Elective ipsilateral neck radiotherapy is indicated for lymphoepithelioma-like carcinoma.

Carcinoma, Adenoid Cystic↗
PubMed2000

Meta-analyses of clinical drug trials--gold standard reviews or statistical alchemy?

Renewed emphasis on the critical appraisal of published evidence has in turn led to critical appraisal of the way clinical studies have been reviewed. Reviews perform the vital function of summarising a wealth of research information in an efficient and trustworthy manner, but traditional narrative reviews have fallen short in this area, not because they are narrative, but because they have allowed reviewer and publication bias to creep in under the guise of expert authority. Meta-analysis or systematic review emphasises the use of a review protocol based on logical principles to minimise bias, together with qualitative and appropriate quantitative summaries of the data. Like any review, the perceived impact of a meta-analysis is dependent on the quality of the reviewed studies, therefore randomised clinical trials are the favoured substrate for the meta-analysis of drug efficacy because of their potentially high internal validity. The importance of meta-analysis as a tool for clinical drug evaluation has prompted this selective account of its nature, theory, practice and interpretation, with particular emphasis on meta-analysis as a review methodology rather than a statistical methodology, the critical distinction between design and result homogeneity and the need to explore issues of heterogeneity rather than gloss over them by using some statistical shortcut.

Clinical Trials as Topic↗
PubMed1999

In vivo trial comparing patients' tolerance of Q-switched Alexandrite (QS Alex) and Q-switched neodymium:yttrium-aluminum-garnet (QS Nd:YAG) lasers in the treatment of nevus of Ota.

BACKGROUND AND OBJECTIVES: Different types of Q-switched lasers have been found to be effective in the treatment of nevus of Ota. However, a clinical trial involving in vivo comparison of the use of different laser systems has not been performed. The aim of the present study was to compare the patient tolerance of Q-switched Alexandrite (QS Alex) and Q-switched neodymium:yttrium-aluminum-garnet (QS Nd:YAG) lasers in the treatment of nevus of Ota. STUDY DESIGN/MATERIALS AND METHODS: Thirty-three patients (11 male, 22 female) were recruited for this study, and 45 treatment sessions were performed. Half of each lesion was treated with QS Alex and the other half with QS Nd:YAG laser. Patients were interviewed with a visual analog scale questionnaire immediately after treatment and 1 week later. Questions included the degree of pain, swelling, and bleeding. RESULTS: The immediate pain after treatment was more severe for QS Alex than for QS Nd:YAG laser. However, 1 week after laser therapy, most patients found QS Alex to be superior. CONCLUSION: Patients tolerate QS-Alex better than QS Nd:YAG. This finding is important because patients with nevus of Ota are often children, and multiple laser sessions are necessary for complete resolution of the lesion.

Activities of Daily Living↗
PubMed1999

Head and neck cancers associated with Madelung's disease.

BACKGROUND: Madelung's disease is a rare lipodystrophy that presents with multiple fatty masses in the neck, trunk, and upper extremities. The fatty accumulation is considered a benign disease, but compression of the aerodigestive tract may occur in long-standing disease. METHODS: Eight Chinese patients with Madelung's disease were reviewed. All were male, aged 48 to 67 years, with a history of disease ranging from 4 to 20 years. Two of the eight patients developed aerodigestive symptoms and were subsequently found to have head and neck cancers. These two patients are described. RESULTS: The possible mechanism that may account for an increase in malignant tumors of the airway in this group of patients is the synergistic effect of smoking and alcohol abuse as risk factors for both Madelung's disease and malignant tumors of the airway. Currently it is recommended that these patients should have their fatty lesions removed surgically. The removal of fat facilitates examination of the neck for signs of cervical lymphadenopathy in malignant disease. CONCLUSIONS: Patients with Madelung's disease should be followed regularly. The development of aerodigestive symptoms should be fully investigated with endoscopy and imaging. The cause of symptoms should not be attributed to fatty compression until a carcinoma of the upper airway has been excluded.

Alcoholism↗