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Biomedical subjects

K H Chan

Publications and source records attributed to K H Chan.

At least 109 records · Page 6Linked to original sources
PubMed2000

Effect of oral clonidine premedication on perioperative hemodynamic response and postoperative analgesic requirement for patients undergoing laparoscopic cholecystectomy.

BACKGROUND: To investigate the clinical efficacy of oral clonidine premedication in anesthesia and analgesia in patients undergoing laparoscopic cholecystectomy (LC). METHODS: One hundred and ten patients, scheduled for elective laparoscopic cholecystectomy, were recruited for the prospective, randomized, single-blind, comparative study. They were randomly allotted to either of the placebo or clonidine group. Patients of the placebo group (n = 65) were premedicated with oral antacid (alugel hydroxide 300 mg), while those in the clonidine group (n = 45) were premedicated with oral clonidine 150 micrograms prior to anesthesia. The premedication was given 60 to 90 min before the anticipated time of induction of anesthesia. Normocapnia was maintained throughout the perioperative period. Mass spectrometer was used to assess the inspired and expiratory concentrations of isoflurane, the anesthetic used for maintenance of anesthesia. Postoperative pain intensity, sedation scores, adverse events, time to the first dose of postoperative analgesic and cumulative analgesic requirement in 24 hours were recorded. Data were expressed as mean +/- SD. RESULTS: Patients in the clonidine group displayed greater hemodynamic stability perioperatively and the isoflurane requirement was also reduced (30% less). The postoperative analgesic requirement was less (1.5 +/- 1.3 vs. 2.2 +/- 1.3 dose, P < 0.05) and the time for the first dose of analgesic was prolonged (411 +/- 565 vs. 264 +/- 441 min) in comparison with the placebo group but no statistic difference was found. CONCLUSIONS: Oral clonidine premedication helped to provide perioperative hemodynamic stability, spared the use of isoflurane and reduced the requirement of postoperative analgesia so as to smoother the way to recovery in patients undergoing LC.

Administration, Oral↗
PubMed2000

Twenty-four hour, non-invasive, neonatal chromosome analysis--application in a case of mixed gonadal dysgenesis.

INTRODUCTION: With the advent of interphase molecular fluorescent in-situ hybridisation (FISH), buccal mucosa can be used to provide an highly accurate assessment of those chromosomes most commonly causing abnormality in live-born children. CLINICAL PICTURE: A newborn child presented with ambiguous genitalia. The phallus-looking enlarged "clitoris" had a urethral opening at the ventral surface near the tip and the "labial" folds were completely fused. No definite gonads were palpable. Differential diagnostic possibilities included sex chromosome or a single gene abnormality such as congenital adrenal hyperplasia. Thus, one initial objective was to investigate the sex chromosomes. Buccal mucosa was used in conjunction with fluorescent molecular probes for the X and Y. This methodology enabled a firm diagnosis of a 45,X/46,XY mosiac to be made within 24 hours. Decisions could then be made concerning gender assignment. TREATMENT AND OUTCOME: Intervention by means of reconstructive surgery of the external genitalia would be made available at a later date. CONCLUSIONS: The use of buccal mucosa is non-invasive, easy to obtain and, when combined with molecular techniques, is reliable and accurate. The clinical implication of this methodology is that it will be especially useful in gender assignment or when rapid decisions on live-saving surgery have to be made in cases of possible aneuploidy.

Cytogenetic Analysis↗
PubMed2000

Thoracic epidural analgesia with morphine does not prevent postthoracotomy pain syndrome: a survey of 159 patients.

BACKGROUND: This retrospective study sought to determine the incidence of postthoracotomy pain syndrome (PTPS), and whether epidural morphine for the postoperative analgesia could prevent the development of PTPS. METHODS: We reviewed the charts of 372 patients who had undergone thoracotomy. The majority underwent general anesthesia (GA) combined with thoracic epidural analgesia (TEA). Of the 372 patients, only 159 (42%) were available for interview. Patients were divided into two groups based on the duration of pain, i.e., pain group (pain > 3 months, n = 65) and pain-free group (pain < 3 months, n = 94). RESULTS: Both groups were comparable regarding sex, age, weight, height, smoking, alcohol ingestion, education, marital status, duration of surgery, and the number of patients either receiving GA plus TEA or GA alone. About 41% of the patients experienced PTPS that persisted for 21 +/- 12 mon (follow-up: 28 +/- 12 mon). Most pain was mild or moderate and was usually described as being only a discomfort. Only 6.2% suffered severe pain with shooting, aching, burning or numbness. Patients with PTPS suffered more depression and insomnia. The incidence of PTPS was not different in patients who received GA alone or GA plus TEA (39% vs. 42%). CONCLUSIONS: Epidural morphine for postoperative analgesia that continued for 3 days appeared to have no effect in the prevention of PTPS.

Adult↗
PubMed1999

Human infection with influenza H9N2.

We report the clinical features of two cases of human infection with influenza A virus subtype H9N2 in Hong Kong, and show that serum samples from blood donors in Hong Kong had neutralising antibody suggestive of prior infection with influenza H9N2.

Animals↗
PubMed1999

Fungal mastoiditis in immunocompromised children.

The immunocompromised host is subject to a variety of opportunistic infections. Mycotic infections, including invasive fungal sinusitis, are a dreaded complication in immune deficient children. Fungal mastoiditis has rarely been described in this population. Our experience with 2 cases of fungal mastoiditis in immunocompromised children is reviewed. Case histories describing aggressive medical management with and without surgical intervention and a review of the literature are presented.

Adolescent↗
PubMed1999

Retrograde suction decompression of paraclinoid aneurysm--a revised technique.

BACKGROUND: Aneurysms of the ophthalmic segment of the carotid artery are difficult lesions to handle. Batjer and Samson described the technique of suction decompression of the aneurysm by inserting a needle and aspirating blood from the internal carotid artery in the neck. However, this method carries a risk of arterial dissection and distal embolization. METHOD: We describe a revised technique for suction decompression of paraclinoid aneurysms. The method makes use of the anatomical advantage of the carotid bifurcation. Instead of direct clamping of the internal carotid artery, we isolated the common and external carotid arteries and decompressed the aneurysm via the external carotid artery. We also saved the aspirated blood for autotransfusion. RESULTS: We have used this technique in two elderly patients with good results. CONCLUSION: This technique avoids dissection of the internal carotid artery and minimizes the risk of embolization.

Blood Loss, Surgical↗
PubMed1999

Persistent rhinosinusitis in children after endoscopic sinus surgery.

The efficacy of endoscopic sinus surgery (ESS) in children is insufficiently addressed in the medical literature. We report a cohort of 14 children (mean age 7.7 years, median age 5.1 years) seen at our multidisciplinary clinic for refractory rhinosinusitis during a 30-month period who continued to have rhinosinusitis despite previous ESS. Prior ESS procedures were performed by 11 surgeons in 3 states. The first ESS was performed when the children were a mean age of 4.6 years, and in 10 of 14, it was performed when they were younger than 4.8 years. This cohort required a disproportionately high rate of subsequent surgical intervention, 50%, versus a 9% surgical rate in the remaining clinic population (P = 0.0002). Osteomeatal scarring was the single most difficult surgical complication. Significant morbidity, in the form of persistent disease, is encountered after ESS in young children. Although chronic rhinosinusitis after ESS, to a certain degree, can still be managed by medical therapy, judicial use of ESS, especially in the very young, is recommended.

Adolescent↗
PubMed1999

Clinical practice guidelines for the management of chronic sinusitis in children.

Chronic sinusitis in children is a common and vexing disease for clinicians and the public. There are insufficient data in the literature to develop an evidence-based clinical guideline. Experience in managing pediatric chronic sinusitis has been gained through a multidisciplinary clinic at our institution during the past 3 years. A panel of experts was formed, and with the guidance of a guideline methodologist, the development of a rigorous outcome-based guideline was undertaken. Symptom-improvement and recurrence estimates for a variety of medical and surgical treatments were assessed. Wide probability estimates were made by the panelists in most cases. Although we refrained from making specific recommendations, we developed a ranked series of practical treatment options taking into account side effects and costs.

Anti-Bacterial Agents↗
PubMed1999

Peri-anhepatic phase oxygen kinetics in porcine liver transplantation.

BACKGROUND: We applied a liver transplantation animal model to examine the relationship between oxygen delivery and consumption. The presence of pathologic flow-dependent oxygen consumption was investigated during and after the anhepatic phase. The effect of venous-to-venous bypass on oxygen kinetics was evaluated. METHODS: Twelve pigs were randomly divided into two groups. The non-bypass group consisted of six pigs that were subjected to clamping of the hepatic artery, portal vein, and the superior and inferior vena cava to produce an anhepatic phase. The bypass group consisted of six pigs that underwent vascular clamping and liver transplantation with venous bypass. Hemodynamics, oxygen delivery index (DO2) and oxygen consumption index (VO2) were recorded during the peri-anhepatic phase. Best-fit regression lines were calculated for DO2 vs VO2. RESULTS: In the pigs without venous bypass, the blood pressure, cardiac index and VO2 dropped significantly after vascular clamping and lactic acidosis developed. In pigs with venous bypass, vascular clamping induced a significant decline of cardiac output and DO2 but VO2 was maintained by a compensatory increase in oxygen extraction ratio. DO2 and VO2 after the release of vascular clamping increased significantly higher than that before vascular clamping. The O2 supply-dependent regression line was drawn from the points below critical oxygen delivery with a slope of 0.232 (95% CI = 0.110-0.354, r2 = 0.50, p = 0.010). The pathologic supply-dependent line was drawn from the points with supranormal DO2 and VO2 with a slope of 0.185 (95% CI = 0.050-0.333, r2 = 0.510, p = 0.029). The slope of the supply-independent line was 0.0089 (95% CI = -0.030-0.050, r2 < 0.009, p = 0.12). CONCLUSIONS: Oxygen delivery dropped below the critical level and flow-dependent oxygen consumption developed during the anhepatic phase without venous bypass. Venous-to-venous bypass is necessary to maintain a critical DO2 and stable hemodynamics during porcine liver transplantation. Pathologic flow-dependent oxygen consumption developed after the anhepatic phase.

Animals↗
PubMed1999

Normative data of quantitative thermal and vibratory thresholds in normal subjects in Taiwan: gender and age effect.

BACKGROUND: Quantitative sensory testing has gained popularity as a tool in the diagnosis of peripheral neuropathies. This study aims to establish normative data of quantitative thermal and vibratory thresholds in normal subjects in Taiwan. In addition, we also examined the effect of age and gender differences on these thresholds. METHODS: The study included 100 healthy subjects (50 males and 50 females) who were admitted for regular physical examination. The quantitative testing of thermal, cold and vibratory sensations were performed having recourse to a Thermotest instrument applied on the right hand and foot of these subjects. Measurements included perception thresholds of warm (WT), cold (CT), heat pain, cold pain and vibration as well as a visual analog pain scale. RESULTS: Age was comparable between the sexes, but the male subjects were taller than the female subjects. A higher WT and CT in the hand, but not in the foot, were found in the male subjects in comparison with the female subjects. Heat pain threshold and cold pain threshold of both sites did not significantly differ between genders. Moreover, the groups did not differ in vibration threshold and visual analog pain scale. Young subjects (age < 30 years) showed a higher CT in the foot than the older subjects (age > 50 years). None of the above parameters were different between these two age groups. Overall, the age or height bore no significant relation to the difference between WT and CT (DDWT-CT). CONCLUSIONS: The female subjects were found to be more sensitive to warm and cold stimulation in the hand than their counterparts. These results have provided valuable normative data on sensory perceptive thresholds in Taiwanese, which are useful as a tool in the diagnosis of peripheral neuropathy.

Adult↗
PubMed1999

Asbestosis in Malaysia: report on first two cases.

The first two cases of asbestosis in Malaysia are reported. Both had considerable occupational exposure to asbestos dust in the past, with a long latency period exceeding 30 years. One case presented with distinctive clinical and radiological features, while the other case was only confirmed by histological diagnosis. The usefulness of modern investigation techniques such as CT scan in the diagnosis of asbestosis is also illustrated.

Asbestosis↗
PubMed1998

Simultaneous expression of type 1 and type 2 Lewis blood group antigens by Helicobacter pylori lipopolysaccharides. Molecular mimicry between h. pylori lipopolysaccharides and human gastric epithelial cell surface glycoforms.

Previous structural investigations performed on the lipopolysaccharides (LPSs) from the human gastric pathogen Helicobacter pylori have revealed that these cell surface glycan molecules express type 2 partially fucosylated, glucosylated, or galactosylated N-acetyllactosamine O antigen chains (O-chains) of various lengths, which may or may not be terminated at the nonreducing end by Lewis X (Lex) and/or Ley blood group epitopes in mimicry of human cell surface glycoconjugates and glycolipids. Subsequently, serological experiments with commercially available Lewis-specific monoclonal antibodies also have recognized the presence of Lex and Ley blood group antigens in H. pylori but, in addition, have indicated the presence of type 1 chain Lea, Leb, and Led (H-type 1) blood group epitopes in some H. pylori strains. To confirm their presence, structural studies and additional serological experiments were undertaken on H. pylori strains suspected of carrying type 1 chain epitopes. These investigations revealed that the O-chain region of H. pylori strain UA948 carried both Lea (type 1) and Lex (type 2) blood group determinants. The O-chain from H. pylori UA955 LPS expressed the terminal Lewis disaccharide (type 1 chain) and Lex and Ley antigens (type 2). The O-chain of H. pylori J223 LPS carried the type 1 chain precursor Lec, the H-1 epitope (Led, type 1 chain) and an elongated nonfucosylated type 2 N-acetyllactosamine chain (i antigen). Thus, O-chains from H. pylori LPSs can also express fucosylated type 1 sequences, and the LPS from a single H. pylori strain may carry O-chains with type 1 and 2 Lewis blood groups simultaneously. That monoclonal antibodies putatively specific for the Leb determinant can detect glycan substructures (Le disaccharide, Lec, and Led) of Leb indicates their nonspecificity. The expression of both type 1 and 2 Lewis antigens by H. pylori LPSs mimics the cell surface glycomolecules present in both the gastric superficial (which expresses mainly type 1 determinants) and the superficial and glandular epithelium regions (both of which express predominantly type 2 determinants). Therefore, each H. pylori strain may have a different niche within the gastric mucosa, and each individual LPS blood group antigen may have a dissimilar role in H. pylori adaptation.

Carbohydrate Sequence↗
PubMed1998

Epstein-Barr virus expression within keratinizing nasopharyngeal carcinoma.

Three stages of maturation can be seen in keratinizing nasopharyngeal carcinomas. These stages are similar morphologically to basal cells, intermediate and superficial squamous cells seen in normal squamous epithelium. Taking advantage of such a diverse tumour cell population, 10 keratinizing nasopharyngeal carcinoma (NPC) were examined by in situ hybridization for the presence of latent Epstein-Barr Virus (EBV) using EBV encoded RNAs (EBERs) and by immunohistology for the presence of EBV early antigen-diffuse (EA-D) and the 350/220 kd membrane glycoprotein of the EBV. The basal cell-like tumour cells are mainly infected latently with the virus; viral replication was found in isolated intermediate squamous cells, whilst superficial squamous cells are largely depleted of all the viral markers. We used a control series of nonkeratinizing nasopharyngeal carcinomas composed of undifferentiated and poorly differentiated tumour cells and EBV latency was present in these tumours. Viral replication was detected by RT-PCR, in the undifferentiated tumours but viral replication was not seen by immunohistology. The possible relationship between EBV life cycle in these tumours and tumour cell differentiation is discussed in the light of these findings.

Antibodies, Monoclonal↗
PubMed1998

Emergency medicine in Hong Kong.

Emergency medicine in Hong Kong is a relatively new specialty. Substantial progress toward recognition of emergency medicine in the territory has occurred during the past 2 years, and the Hong Kong College of Emergency Medicine is now formally recognized by the Royal College of Surgeons in the United Kingdom. With the transfer of the territory to chinese rule, the emergency medical system in Hong Kong may serve as a model for the development of emergency medicine in mainland China.

Emergency Medical Services↗
PubMed1998

Development and evaluation of an Epstein-Barr virus (EBV) immunoglobulin M enzyme-linked immunosorbent assay based on the 18-kilodalton matrix protein for diagnosis of primary EBV infection.

A new immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) based on the recombinant Epstein-Barr virus (EBV) matrix protein was developed. Compared to indirect immunofluorescence for the detection of IgM antibody to the EBV capsid antigen on clinical specimens, the sensitivity and specificity of the new IgM ELISA were 96 and 96%, respectively.

Antibodies, Viral↗
PubMed1998

Lack of evidence of active lytic replication of Epstein-Barr and cytomegaloviruses in patients with systemic lupus erythematosus.

OBJECTIVES: Systemic lupus erythematosus (SLE) is a multifactorial disease. Environmental factors such as viral infection(s) have been proposed as pathaetiological factors. There are particular interests in studying lymphotropic viruses such as the Epstein-Barr virus (EBV) and cytomegalovirus (CMV). Although previous case reports and in vitro studies suggested that they may have a role, there is no direct evidence that onset of SLE or disease exacerbation is associated with active infection by these viruses. Using the very sensitive polymerase chain reaction (PCR) technique, we tried to find out evidence of active replication of these viruses in patients with SLE. METHODS: Thirty-four patients with SLE were compared with matched normal controls. Eleven patients were newly diagnosed to have SLE and 18 of the 34 patients had active disease as determined by a SLE Disease Activity Index (SLEDAI) score of > or = 10 at the time of study. RESULTS: Our results showed no evidence of active replication or reactivation of EBV in the leucocytes amongst the newly diagnosed SLE patients, established SLE patients, patients with SLEDAI > or = 10, patients with SLEDAI < 10, and control subjects. There was no evidence of CMV infection in any of the subjects studied. The IgG and IgA responses against EBV early antigen (EA) and viral capsid antigen (VCA) were also studied. The IgG and IgA responses against VCA of EBV were increased in patients with SLE when compared with controls. However, there were no differences in these responses among different subgroups of patients. The mechanism of these responses was not apparent but may represent non-specific hyperimmune responses in these patients. There were no differences in the titre of IgG and IgA against EBV EA between the patient groups and controls. CONCLUSION: There is no direct evidence that either EBV or CMV plays a direct role in the onset and/or exacerbation of SLE.

Antibodies, Viral↗