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Biomedical subjects

C Chan

Publications and source records attributed to C Chan.

At least 37 records · Page 2Linked to original sources
PubMed2004

Use of an electronic barcode system for patient identification during blood transfusion: 3-year experience in a regional hospital.

OBJECTIVE: To evaluate the use of an electronic barcode system for patient identification during blood transfusion. DESIGN: Retrospective study. SETTING: Regional hospital, Hong Kong. PATIENTS: For all patients requiring blood transfusion between May 1999 and April 2002, with the exception of patients in the psychiatric wards and the accident and emergency department, a portable, hand-held scan-and-print electronic device was used to verify and document patients' identity at two critical points of transfusion: blood sampling for the compatibility test and blood administration. MAIN OUTCOME MEASURES: Scope of use of the electronic device, cost, effectiveness, staff compliance, problems and solution for improvement. RESULTS: In the first 3 years of hospital-wide use of the new device, no incidents of blood transfusion to wrong patients, or wrong labelling of blood samples, occurred with 41,00 blood sampling procedures and administration of 27 000 units of blood. Blood sampling took 6 minutes to complete with the use of the electronic device-similar to that taken by the conventional second-checker system. Among hospital staff, the compliance rate of using the new device approached 90%. Battery problems occurred in 12% of episodes of use of the device. CONCLUSIONS: The electronic barcode system was effective in reducing human error related to bedside transfusion procedures. The future goal is to tailor-make a more efficient device with additional functions.

Attitude of Health Personnel↗
PubMed2004

Drug-eluting stents: the end of restenosis?

One of the major advancements in interventional cardiology has been the introduction of drug-eluting stents (DES). By incorporating anti-proliferative agents onto the surface of the stent, neointimal hyperplasia occurring within the stent, which is the main cause of in-stent restenosis (ISR), is markedly reduced. Stents coated with agents, like sirolimus or paclitaxel, when compared to bare metal stents (BMS), had shown remarkable reduction in binary restenosis and target vessel revascularisation (TVR) rates in large randomised clinical trials. The final hurdle of percutaneous coronary intervention (PCI) seems to have been overcome. However, there are still many uncertainties that need to be clarified. The long-term safety of DES remains a major concern; in particular, stent thrombosis and incomplete stent apposition. In the real world, there is a tendency to implant DES in smaller vessels, longer lesions, and complex lesions, as these are high risk for ISR and would yield the greatest benefit. Whether the excellent results of clinical trials of DES can be replicated in these more complex lesions is still unknown and awaits further studies. Although early experience with DES in complex lesions had shown improved results, a higher number of ISR were seen. Finally, the high cost of these devices has precluded their use in all patients undergoing PCI and deliberation among healthcare policy-makers on who should receive DES has centred not only on financial, but also legal and ethical issues. As DES has not completely eliminated ISR and not all patients can afford DES, ISR may survive the initial assault of DES, albeit considerably less in number, for now.

Coronary Restenosis↗
PubMed2003

Acute bile duct injury. The need for a high repair.

BACKGROUND: An immediate repair is considered optimal in acute biliary duct injuries; however, it may prove to be a challenge, because such repairs are usually performed on small ducts whose viability cannot always be determined. METHODS: We performed a retrospective review of the charts of patients with acute bile duct injury who underwent repair at a tertiary care academic university hospital. A total of 204 patients with acute bile duct injury were seen between 1989 and 2002. Of these, 30 were repaired within minutes to hours after the injury. These patients were divided into two groups. Group I patients had a Roux-en-Y hepatojejunostomy below the hepatic junction; Group II patients had a Roux-en-Y hepatojejunostomy at the junction level. We then performed a long-term evaluation of anastomosis function in these patients, using clinical, radiological, and laboratory. RESULTS: Twenty-eight injuries were secondary to a laparoscopy; the other two resulted from open cholecystectomies. All of the patients suffered complex injuries with complete section of the duct and substance loss (Strasberg E). There were 12 patients in group I and 18 in group II. Three cases in group I (25%) and one in group II (5%) developed anastomosis dysfunction. Mean follow-up was 56 months (range, 12-80) in group I and 52 months (range, 10-76) in group II. Two cases in group I (16%) and none in group II (0) required reoperation (p < 0.05). CONCLUSIONS: In the acute setting, complex lesions should be treated with a high bilioenteric anastomosis (at the junction level) in the first attempt at repair. Lower-level anastomoses are associated with a higher dysfunction rate and the need for radiological manipulation and reoperation. Also, stenosis of the anastomosis secondary to undetected duct ischemia in the acute repair is more frequent in low bilioenteric anastomoses.

Acute Disease↗
PubMed2003

Fatal brain stem event complicating acute pancreatitis.

Acute pancreatitis, developing in a patient with chronic renal failure, was complicated by a fatal neurological illness during which MRI showed pontine and extrapontine changes consistent with pontine and extrapontine myelinolysis. At post mortem, acute pancreatitis was confirmed but the neuropathological findings were more in keeping with an unusual presentation of acute haemorrhagic leucoencephalitis, perhaps even representing a form of 'pancreatic encephalopathy'. Although the development of CT and MRI scanning has greatly increased the resolution of neuroimaging and facilitated diagnosis during life, the value of autopsy examination is confirmed in cases such as this. Sometimes the findings may raise more questions than may have been answered - this too is an important function!

Acute Disease↗
PubMed2003

Dental hygiene in Hong Kong: a global perspective.

PURPOSE: This article examines how dental hygiene status in Hong Kong compared to global developments of the profession. The aim is to address access to cost-effective, qualified preventive care. METHODS: Information for this study was obtained using questionnaires and followed up by e-mail correspondence with International Federation of Dental Hygienists (IFDH) delegates and additional experts, supporting studies and reference literature. All experts consulted are involved in the professional and educational organisation of dental hygiene on a national level. RESULTS: Results show that dental hygiene is practised in about 30 countries, generally as a licensed profession, studied at institutions of higher education. Average study duration is 3 years. Globally, low access to qualified dental hygiene care tends to be a result of a lack of social and cultural awareness of the benefits of preventive care and insufficient funding for preventive services as well as supervision requirements, which tie dental hygiene care to private practice dentistry settings. In several countries, a reduction of supervision requirements has opened the door to provide care at alternative settings and public health institutions. CONCLUSION: In Hong Kong, owing to a small number of practising dental hygienists, access to qualified preventive care is scarce. Public awareness of the benefits and cost-effectiveness of preventive measures need to be raised to achieve higher acceptance of the profession. Global and scientific developments mandate an extension of study duration. Access to qualified care could be addressed by public health initiatives, which utilise the expertise of dental hygienists in setting and attaining preventive health goals.

Attitude to Health↗
PubMed2003

The pattern of distribution of selected ATP-sensitive P2 receptor subtypes in normal rat kidney: an immunohistological study.

Using immunohistological techniques and available polyclonal antibodies, we have identified several ATP-sensitive P2 receptor subtypes in specific structures of the normal rat kidney. Of the P2 receptor subtypes examined, P2X1, P2X2 and P2Y1 receptors were found in the smooth muscle layer of intrarenal vessels. The P2Y1 receptor was also found on glomerular mesangial cells, the brush border membrane of the proximal straight tubule and on peritubular fibroblasts. In the cortex, P2Y4 receptors were found on the tubule epithelium of the proximal convoluted tubule, and P2Y2 receptors on glomerular epithelial cells (podocytes). P2X4 and P2X6 receptors were present throughout the renal tubule epithelium from the proximal tubule to the collecting duct. P2X5 receptors were expressed on medullary collecting duct cells and the apical membrane of the S3 segment of the proximal tubule. Possible functions of these receptor subtypes in normal rat kidney are discussed.

Adenosine Triphosphate↗
PubMed2002

Determination of remifentanil in human blood by capillary gas chromatography with nitrogen-selective detection.

A validated method for the determination of remifentanil in human blood, applicable to all therapeutic concentrations, using capillary GC with nitrogen-specific detection and fentanyl as the internal standard has been developed. Citrated whole blood samples were extracted into 1-chlorobutane following precipitation of proteins with methanol. The drugs were back extracted into 10 mM HCl and re-extracted into methanol-1-chlorobutane. The extracts were reconstituted in methanol and injected onto a 25-m BPX-5 column. The lower limit of quantitation was 0.2 ng/ml with within- and between-day coefficients of variation of less than 15%.

Analgesics, Opioid↗
PubMed2002

Bifrontal decompressive craniectomy for acute subdural empyema.

INTRODUCTION: Subdural empyema is an uncommon but serious complication of sinusitis. Despite the use of advanced imaging facilities, modern antibiotic therapy and aggressive neurosurgical protocols, this condition still carries significant morbidity and mortality. CASE REPORT: We report an unusual case of sinusitis-associated acute subdural empyema in a 13-year-old patient, presenting in a catastrophic manner with acutely raised intracranial pressure. Emergency bifrontal decompressive craniectomy was necessary both to reduce the intracranial pressure and to drain the subdural empyema. RESULTS: The full range of intracranial complications subsequently occurred, including brain abscesses, recurrent subdural empyema and ventriculitis. Despite this, the patient's outcome was good, with minimal intellectual deficits. CONCLUSION: In cases of severe intracranial infection, we therefore advocate an aggressive surgical approach coupled with appropriate antibiotics to ensure a good outcome.

Acute Disease↗
PubMed2002

Peptoid inhibition of trypanothione reductase as a potential antitrypanosomal and antileishmanial drug lead.

One route to the design of lead compounds for rational drug design approaches to developing drugs against trypanosomiasis, Chagas' disease and leishmaniasis is to develop novel inhibitors of the parasite-specific enzyme trypanothione reductase. A lead inhibitor based on a peptoid structure was designed in the present study based on the known strong competitive inhibition of trypanothione reductase by N-benzoyl-Leu-Arg-Arg-beta-naphthylamide and N-benzyloxycarbonyl-Ala-Arg-Arg-4-methoxy- beta-naphthylamide. In the target peptoid the arginyl residues were replaced by alkylimidazolium units and the benzyloxycarbonyl group by the benzylaminocarbonyl function. The peptoid was synthesised using t-butoxycarbonyl protection chemistry and couplings were activated by 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate. The resulting peptoid was shown to be a competitive inhibitor of recombinant trypanothione reductase from Trypanosoma cruzi with a K(i) value of 179 microM and with only weak inhibition of human erythrocyte glutathione reductase (the inhibition of glutathione reductase was at least 291-fold weaker than of trypanothione reductase).

Animals↗
PubMed2002

Evaluation of Bioglass/dextran composite as a bone graft substitute.

Allogenic and alloplastic bone graft substitutes serve either as bioinert or bioactive osteoconductors. Bioglass is a bioactive osteoconductor and also shows osteoproductive effects due to its high level of bioactivity. However, the material lacks some cohesiveness when used in augmenting certain bony surfaces, i.e. large or pleomorphic defects. The addition of medium molecular weight dextran modifies the particulate to a putty consistency and improves the handling characteristics. The objective of this study is to evaluate the influence of dextran upon the bioactive properties of Bioglass. Standardized bony defects in the lateral femoral condyles in adult New Zealand white rabbits were filled with one of five material groups: (1) autogenous bone; (2) Bioglass particulate; (3) Bioglass particulate mixed with dextran to a putty-like consistency; (4) a mixture of Bioglass and autogenous bone; (5) a mixture of Bioglass putty with autogenous bone. Postoperative healing was observed after periods of 2 days, 1, 2, 3, 6 and 12 weeks. Results showed no evidence of toxicity in the dextran-containing materials, and defects in all test groups showed 100% bony ingrowth within 6 weeks. The addition of medium molecular weight dextran did not appear to alter the bioactive properties of Bioglass and had no adverse influence upon the ingrowth of bone into the defect sites.

Animals↗
PubMed2002

A comparative study of sevoflurane sedation with nitrous oxide sedation for dental surgery.

This study compares the use of inhalation sedation using sevoflurane (group S) with inhalation sedation using nitrous oxide (group N) in patients undergoing bilateral extraction of third molar teeth under local anaesthesia. The study was designed as a cross-over study. Seventeen ASA I, day surgery patients were studied. Patients were randomly allocated to receive either 8 l/min 50% nitrous oxide in oxygen (group N) or same flow of 1% sevoflurane (group S) for the first procedure. Each patient then had the alternate method of sedation for the second procedure. There were no significant differences between the methods in patient co-operation and surgeon's satisfaction with sedation. Psychomotor tests were comparable in both groups. The patients were significantly more sedated in the group S compared to group N (P=0.004). Significantly more patients complained of an unpleasant odour group S (P<0.01) but none withdrew from the study for this reason. No adverse cardiorespiratory effects resulted from sevoflurane or nitrous oxide sedation. Both methods gave good amnesia during the procedure. There was high acceptance of both methods and the patients rated the technique as equally satisfactory. We conclude that inhalation sedation with sevoflurane is a suitable alternative method to nitrous oxide sedation.

Adult↗
PubMed2002

Clinical outcomes of patients with diabetes mellitus and acute myocardial infarction treated with primary angioplasty or fibrinolysis.

OBJECTIVE: To compare the early and late outcomes of primary percutaneous transluminal coronary angioplasty (PTCA) with fibrinolytic treatment among diabetic patients with acute myocardial infarction (AMI). DESIGN: Retrospective observational study with data obtained from prospective registries. SETTING: Tertiary cardiovascular institution with 24 hour acute interventional facilities. PATIENTS: 202 consecutive diabetic patients with AMI receiving reperfusion treatment within six hours of symptom onset. INTERVENTIONS: Fibrinolytic treatment was administered to 99 patients, and 103 patients underwent primary PTCA. Most patients undergoing PTCA received adjunctive stenting (94.2%) and glycoprotein IIb/IIIa inhibition (63.1%). MAIN OUTCOME MEASURES: Death, non-fatal reinfarction, and target vessel revascularisation at 30 days and one year were assessed. RESULTS: Baseline characteristics were similar in these two treatment groups except that the proportion of patients with Killip class III or IV was considerably higher in those treated with PTCA (15.5% v 6.1%, p = 0.03) and time to treatment was significantly longer (103.7 v 68.0 minutes, p < 0.001). Among those treated with PTCA, the rates for in-hospital recurrent ischaemia (5.8% v 17.2%, p = 0.011) and target vessel revascularisation at one year (19.4% v 36.4%, p = 0.007) were lower. Death or reinfarction at one year was also reduced among those treated with PTCA (17.5% v 31.3%, p = 0.02), with an adjusted relative risk of 0.29 (95% confidence interval 0.15 to 0.57) compared with fibrinolysis. CONCLUSION: Among diabetic patients with AMI, primary PTCA was associated with reduced early and late adverse events compared with fibrinolytic treatment.

Abciximab↗
PubMed2002

Remifentanil concentration during target-controlled infusion of propofol.

After institutional approval and with written informed consent, eight surgical patients were infused intravenously with remifentanil at 250 ngkg lean body mass (LBM)(-1) x min(-1) for 30 min. Cardiovascular and respiratory parameters were recorded and arterial blood samples were taken at regular intervals. In each patient, the same protocol was repeated 40 min later during propofol infused to a target concentration of 3.0 microg x ml(-1). Blood concentrations of remifentanil and propofol were assayed using capillary gas chromatography and high performance liquid chromatography techniques respectively. The number of subjects enrolled was determined by testing the successive areas under the remifentanil time-concentration curve (AUC) for significant difference or non-difference using sequential analysis. The median measured propofol concentration was 3.5 (range: 2.6-4.5) microg x ml(-1) which did not change significantly during the second remifentanil infusion. The median AUC during propofol infusion was greater than control in all subjects, although there was considerable variation of 94.4 (64.3-129.6) versus 64.6 (34.8-126.9) ng x ml(-1) x min; P=0.008, n=8. After 30 min, there was no significant difference in remifentanil concentration during propofol infusion when compared with remifentanil alone of 4.6 (3.2-5.7) versus 3.8 (1.6-4.9) ng x ml(-1); P=0.73, n=8. Co-administration of propofol and remifentanil may result in greater remifentanil concentrations than when remifentanil is infused alone.

Adolescent↗
PubMed2002

Cosmesis in neurosurgery: is the bald head necessary to avoid postoperative infection?

AIM: The aims of this study were to prospectively investigate the incidence of postoperative wound infection following elective cranial surgery, when scalp hair removal was limited to the line of the incision, and to see if there was an increased risk of infection. MATERIALS AND METHODS: This is an observational study of 57 consecutive adult elective cases operated upon without head shave (between July 1998 and December 1998). The method of scalp preparation is described. RESULTS: During the follow-up period, there was 1 case (1.75%) of postoperative wound infection. This was compared with retrospective data, and was not found to be statistically significant. DISCUSSION: In a review of earlier studies and a search into the history of aseptic surgery, no scientific ground for the practice of shaving was found. We suggest that there is no advantage in shaving patients in terms of reducing wound infection rates.

Adult↗
PubMed2002

Factors affecting uptake of cervical and breast cancer screening among perimenopausal women in Hong Kong.

OBJECTIVES: To identify factors affecting cervical and breast cancer screening attendance among women aged 44 to 55 years by comparing self-reported uptake of cervical smear and clinical breast examination between patients and a population sample. DESIGN AND SETTING: Telephone survey and audit of clinic records to confirm patients' self-report. PARTICIPANTS: Two thousand and sixty-seven women identified through random telephone dialling from the residence directory and 319 patients ever-registered at a family practice teaching clinic. MAIN OUTCOME MEASURES: Uptake of cervical smear and clinical breast examination. RESULTS: The proportion of women undergoing cervical smear tests and clinical breast examination in the previous 12 months were 35.4% and 22.6%, respectively, for randomly selected women, while the figures were 47.2% and 50.6%, respectively, for patients. Record audit confirmed high rates of screening for patients according to evidence-based protocols (85.1% had had a cervical smear within 3 years). For women in the random sample (mean age, 48.9 years; standard deviation, 3.3 years), those who were older, postmenopausal, not receiving hormone therapy, educated to primary level, and with no chronic diseases were least likely to have had screening. For clinic patients (mean age, 47.9 years; standard deviation, 2.8 years), lower education level was the only variable associated with no recent smears. CONCLUSIONS: Healthy perimenopausal and postmenopausal women in the community with lower educational level and not receiving hormone therapy were more likely to be underscreened. Attendance of 44- to 55-year-old women at a family medicine clinic that actively promotes preventive medicine was associated with high screening uptake.

Adult↗
PubMed2001

Leg symptoms in peripheral arterial disease: associated clinical characteristics and functional impairment.

CONTEXT: Persons with lower-extremity peripheral arterial disease (PAD) are often asymptomatic or have leg symptoms other than intermittent claudication (IC). OBJECTIVE: To identify clinical characteristics and functional limitations associated with a broad range of leg symptoms identified among patients with PAD. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of 460 men and women with PAD and 130 without PAD, who were identified consecutively, conducted between October 1998 and January 2000 at 3 Chicago-area medical centers. MAIN OUTCOME MEASURES: Ankle-brachial index score of less than 0.90; scores from 6-minute walk, accelerometer-measured physical activity over 7 days, repeated chair raises, standing balance (full tandem stand), 4-m walking velocity, San Diego claudication questionnaire, Geriatric Depression Score Short-Form, and the Walking Impairment Questionnaire. RESULTS: All groups with PAD had poorer functioning than participants without PAD. The following values are for patients without IC vs those with IC. Participants in the group with leg pain on exertion and rest (n = 88) had a higher (poorer) score for neuropathy (5.6 vs 3.5; P<.001), prevalence of diabetes mellitus (48.9% vs 26.7%; P<.001), and spinal stenosis (20.8% vs 7.2%; P =.002). The atypical exertional leg pain/carry on group (exertional leg pain other than IC associated with walking through leg pain [n = 41]) and the atypical exertional leg pain/stop group (exertional leg pain other than IC that causes one to stop walking [n = 90]) had better functioning than the IC group. The group without exertional leg pain/inactive (no exertional leg pain in individual who walks </=6 blocks per week [n = 28]) and the leg pain on exertion and rest group had poorer functioning than those with IC. Adjusting for age, sex, race, and comorbidities and compared with IC, participants with atypical exertional leg pain/carry on achieved a greater distance on the 6-minute walk (404.3 vs 328.5 m; P<.001) and were less likely to stop during the 6-minute walk (6.8% vs 36%; P =.002). The group with pain on exertion and rest had a slower time for completing 5 chair raises (13.5 vs 11.9 seconds; P =.009), completed the tandem stand less frequently (37.5% vs 60.0%; P =.004), and had a slower 4-m walking velocity (0.80 vs 0.90 m/s; P<.001). CONCLUSIONS: There is a wide range of leg symptoms in persons with PAD beyond that of classic IC. Comorbid disease may contribute to these symptoms in PAD. Functional impairments are found in every PAD symptom group, and the degree of functional limitation varies depending on the type of leg symptom.

Aged↗
PubMed2001

A protein interaction map for cell polarity development.

Many genes required for cell polarity development in budding yeast have been identified and arranged into a functional hierarchy. Core elements of the hierarchy are widely conserved, underlying cell polarity development in diverse eukaryotes. To enumerate more fully the protein-protein interactions that mediate cell polarity development, and to uncover novel mechanisms that coordinate the numerous events involved, we carried out a large-scale two-hybrid experiment. 68 Gal4 DNA binding domain fusions of yeast proteins associated with the actin cytoskeleton, septins, the secretory apparatus, and Rho-type GTPases were used to screen an array of yeast transformants that express approximately 90% of the predicted Saccharomyces cerevisiae open reading frames as Gal4 activation domain fusions. 191 protein-protein interactions were detected, of which 128 had not been described previously. 44 interactions implicated 20 previously uncharacterized proteins in cell polarity development. Further insights into possible roles of 13 of these proteins were revealed by their multiple two-hybrid interactions and by subcellular localization. Included in the interaction network were associations of Cdc42 and Rho1 pathways with proteins involved in exocytosis, septin organization, actin assembly, microtubule organization, autophagy, cytokinesis, and cell wall synthesis. Other interactions suggested direct connections between Rho1- and Cdc42-regulated pathways; the secretory apparatus and regulators of polarity establishment; actin assembly and the morphogenesis checkpoint; and the exocytic and endocytic machinery. In total, a network of interactions that provide an integrated response of signaling proteins, the cytoskeleton, and organelles to the spatial cues that direct polarity development was revealed.

Actins↗