Biomedical subjects

C H Chan

Publications and source records attributed to C H Chan.

At least 37 records · Page 2Linked to original sources

PubMed2001

Absorption of lidocaine during aspiration anesthesia of the airway.

STUDY OBJECTIVE: To determine the optimal solution to use when anesthetizing the airway by aspiration of lidocaine. DESIGN: Randomized, double-blind clinical study. SETTING: University hospital. PATIENTS: 96 adult ASA physical status 1,II, and III patients, scheduled for diagnostic flexible bronchoscopy. INTERVENTIONS: Patients were randomized to receive one of 5 solutions of lidocaine: Group A (n = 16): 1% lidocaine, 0.2 mL. kg(-1); Group B (n = 16): 1.5% 0.2 mL. kg(-1); Group C (n = 32): 2% 0.2 mL. kg(-1); Group D (n = 16): 1% 0.3 mL. kg(-1), and Group E (n = 16): 2% 0.3 mL. kg(-1). Fiberoptic bronchoscopy was performed after the airway was anesthetized with this aspiration technique, using the assigned lidocaine solution. The scope was manipulated in the trachea to test for anesthesia. MEASUREMENTS AND MAIN RESULTS: Successful airway anesthesia was determined by tolerance to bronchoscopy without sustained coughing, and also by the number of lidocaine supplements, if any, that were given via the bronchoscope. Arterial plasma concentrations of lidocaine were measured in 33 patients from Groups C, D, and E. All solutions provided equally effective anesthesia of the airway. All patients tolerated endoscopy through the vocal cords, and 94 patients required no supplementary anesthesia, or only one dose of lidocaine, during bronchoscopy to the carina. The highest peak plasma concentrations of lidocaine were 5.02 and 6.28 microg. mL. No patient had signs of toxicity. CONCLUSIONS: This technique produced anesthesia of the airway to the carina, safely, suitable for awake intubation, in 94 of 95 patients. The use of 1% lidocaine, 0.2 to 0.3 mL. kg(-1), so that the volume is 10 to 20 mL, is recommended.

Absorption↗

PubMed2001

Proinflammatory cytokines (IL-17, IL-6, IL-18 and IL-12) and Th cytokines (IFN-gamma, IL-4, IL-10 and IL-13) in patients with allergic asthma.

Allergen-reactive T helper type-2 (Th2) cells and proinflammatory cytokines have been suggested to play an important role in the induction and maintenance of the inflammatory cascade in allergic asthma. We compared the plasma concentrations of novel proinflammatory cytokines IL-17 and IL-18, other proinflammatory cytokines IL-6 and IL-12, Th2 cytokines IL-10 and IL-13, and intracellular interferon-gamma (IFN-gamma) and IL-4 in Th cells of 41 allergic asthmatics and 30 sex- and age-matched health control subjects. Plasma cytokines were measured by enzyme-linked immunosorbent assay. Intracellular cytokines were quantified by flow cytometry. Plasma IL-18, IL-12, IL-10, IL-13 concentrations were significantly higher in allergic asthmatic patients than normal control subjects (IL-18: median 228.35 versus 138.72 pg/ml, P < 0.001; IL-12: 0.00 versus 0.00 pg/ml, P = 0.001; IL-10: 2.51 versus 0.05 pg/ml, P < 0.034; IL-13: 119.38 versus 17.89 pg/ml, P < 0.001). Allergic asthmatic patients showed higher plasma IL-17 and IL-6 concentrations than normal controls (22.40 versus 11.86 pg/ml and 3.42 versus 0.61 pg/ml, respectively), although the differences were not statistically significant (P = 0.077 and 0.053, respectively). The percentage of IFN-gamma-producing Th cells was significantly higher in normal control subjects than asthmatic patients (23.46 versus 5.72%, P < 0.001) but the percentage of IL-4 producing Th cells did not differ (0.72 versus 0.79%, P > 0.05). Consequently, the Th1/Th2 cell ratio was significantly higher in normal subjects than asthmatic patients (29.6 versus 8.38%, P < 0.001). We propose that allergic asthma is characterized by an elevation of both proinflammatory and Th2 cytokines. The significantly lower ratio of Th1/Th2 cells confirms a predominance of Th2 cells response in allergic asthma.

Adult↗

PubMed2001

Does intensive rehabilitation improve the functional outcome of patients with traumatic brain injury? Interim result of a randomized controlled trial.

To evaluate the effects of intensive rehabilitation on the functional outcome in patients with traumatic brain injury (TBI), we carried out a randomized controlled assessor-blind trial, comparing two groups of patients receiving different intensities of rehabilitation treatment (2 versus 4 h per day). Patients with moderate and severe TBI, aged from 12 to 65 years, were included. Glasgow Outcome Scale (GOS) and Functional Independent Measurement (FIM) were assessed monthly. The interim results of 36 cases showed that there was a trend of more patients in the study group achieving full FIM scores, and good GOS at 2 and 3 months, but the control group appeared to be catching up towards 6 months. Intensive rehabilitation may improve the early functional outcome of TBI patients. The interim results indicate that the study should be continued.

Adolescent↗

PubMed2001

Emx1 is a marker for pyramidal neurons of the cerebral cortex.

The homeobox-containing gene, Emx1, a mouse homologue of Drosophila empty spiracles, is specifically expressed in the developing telencephalic cortex. It has been reported that Emx1 transcripts and the protein product are localized in most cells of the cerebral cortex during the process of proliferation, migration, differentiation and maturation. We provide evidence here, based on a multitude of experimental approaches in developing rats, in support of the hypothesis that the expression of this gene is restricted to pyramidal neurons. Specifically, we found that, similar to pyramidal neurons, cells expressing Emx1 are distributed in all cortical layers, except layer I. Using in situ hybridization and immunocytochemistry at the light and electron microscope levels, we have shown that the density, distribution, soma shape and ultrastructural features of these cells were identical to those of pyramidal neurons. Double-labelling experiments confirmed that the vast majority of Emx1-expressing cells also contained glutamate, a marker of pyramidal neurons. We also found that this gene is expressed by most glutamate-containing neurons in dissociated cortical cell cultures and the vast majority of cells in radially arranged clones of pyramidal cells in the cortices of chimeric mice. Thus, the homeobox gene Emx1 can be reliably used as a marker of the pyramidal cell lineage.

Age Factors↗

PubMed2001

The adhesion molecule TAG-1 mediates the migration of cortical interneurons from the ganglionic eminence along the corticofugal fiber system.

Cortical nonpyramidal cells, the GABA-containing interneurons, originate mostly in the medial ganglionic eminence of the ventral telencephalon and follow tangential migratory routes to reach the dorsal telencephalon. Although several genes that play a role in this migration have been identified, the underlying cellular and molecular cues are not fully understood. We provide evidence that the neural cell adhesion molecule TAG-1 mediates the migration of cortical interneurons. We show that the migration of these neurons occurs along the TAG-1-expressing axons of the developing corticofugal system. The spatial and temporal pattern of expression of TAG-1 on corticofugal fibers coincides with the order of appearance of GABAergic cells in the developing cortex. Blocking the function of TAG-1, but not of L1, another adhesion molecule and binding partner of TAG-1, results in a marked reduction of GABAergic neurons in the cortex. These observations reveal a mechanism by which the adhesion molecule TAG-1, known to be involved in axonal pathfinding, also takes part in neuronal migration.

Animals↗

PubMed2001

Blood pressure reduction and tolerability of amlodipine versus nifedipine retard in Chinese patients with type 2 diabetes mellitus and hypertension: a randomized 1-year clinical trial.

OBJECTIVE: In this 1-year clinical study, we compared the efficacy and tolerability of amlodipine and nifedipine retard in 64 Chinese Type 2 diabetic patients with hypertension. SUBJECTS AND METHODS: There were 25 (39.1%) men and 39 (60.9%) women with mean age 60.7+/-9.9 years. Thirty-four patients were randomized to receive amlodipine 5 mg daily and 30 to receive nifedipine retard 20 mg twice daily. The daily dose of amlodipine and nifedipine retard was increased from 5 mg to 10 mg daily and 20 mg to 40 mg twice daily, respectively, if sitting BP > 140/90 mmHg. RESULTS: Of the 64 patients, 9 dropped out early because they experienced adverse effects related to the drugs. If all treatment-related adverse effects were taken into account, 6 (19.4%) patients were from the amlodipine group and 14 (53.8%) from the nifedipine group (p = 0.011). After 1 year, 48 patients finished the study, 28 were on amlodipine and 20 were on nifedipine retard. Of the 28 patients from the amlodipine group, 11 (39.3%) required additional antihypertensive agents. Of the 20 patients from the nifedipine group, 5 (25%, p value: NS, comparing the 2 groups) required additional antihypertensive agents. Both groups showed similar and significant reduction in blood pressure from Week 6 to Week 52. CONCLUSION: Both amlodipine and nifedipine retard are relatively safe and useful in the treatment of hypertension in Chinese Type 2 diabetic patients. Nifedipine retard, when compared to amlodipine, showed significantly more adverse effects and these may hamper long-term compliance.

Administration, Oral↗

PubMed2001

Modified arterial switch operation by sharing the common wall between the great arteries.

BACKGROUND: Suprapulmonary stenosis and coronary arterial obstruction still remain as problems after an arterial switch operation (ASO). We used a modified ASO applying the common wall and in situ transfer techniques to improve the current procedure. METHODS: From October 1996 to December 1997, 11 babies aged 6 days to 3 months with transposition of the great arteries underwent a modified ASO which included sharing the common wall between the great arteries until above the anterior neoaortic suture-line for coronary and pulmonary artery reconstruction. Coronary arteries were of usual type in three cases, juxtacommissural origin in five, and a high takeoff in one; all were redirected almost in situ. RESULTS: There was no early death (< 30 d), coronary or bleeding problems. One late death occurred after a repeat surgery for suprapulmonary stenosis. This was caused by upward stretching of the left pulmonary artery, which was placed above the high left-sided neoaortic anastomosis for in situ transfer of the high takeoff coronary arteries. Intraluminal growth of the adventitia also contributed to suprapulmonary stenosis, which decreased significantly when the common wall adventitia was cleaned in the last two cases we operated on. Ten patients were doing well at follow-up (30.9 +/- 5.2 mo). CONCLUSIONS: This modified ASO by common wall and in situ transfer might avoid coronary kinking and lessen the chance of postoperative bleeding. To avoid suprapulmonary stenosis, common wall adventitia inside the pulmonary pathway should be cleaned, and the left and right pulmonary arteries should also be kept in situ as possible as in coronary redirection.

Humans↗

PubMed2001

Uterine artery embolisation for treatment of fibroids: experience in Chinese women.

Twelve women with symptomatic fibroids were treated with transcatheter uterine artery embolisation with the use of polyvinyl alcohol (PVA) particles. For the nine women who were due for follow-up, reduction in uterine volume and dominant fibroid size were observed on magnetic resonance imaging. All the nine women had normal luteinising hormone (LH) and follicle stimulating hormone (FSH) levels before the procedure and during the follow-up. Seven of the nine women reported noticeable symptomatic improvement during the follow-up. Pain experienced was of variable level, but well controlled. Adequate analgesia is essential for the procedure. Longer follow-up and prospective fertility studies are required to evaluate the long-term effects before this procedure could be safely extended to younger age groups.

Adult↗

PubMed2001

Body mass index profile in Hong Kong Chinese adults.

INTRODUCTION: Obesity has now become an epidemic with increasing prevalence in most parts of the world. However, information on the problem of obesity in Asians is limited. SUBJECTS AND METHODS: From April 1996 to August 1997, 17,121 Chinese adult subjects from the community of Hong Kong presented themselves voluntarily at the United Christian Nethersole Community Health Service Centers for primary health care check-up. Demographic data including height and weight were documented. Their body mass indexes (BMI) were measured. The prevalence rates of overweight and obese subjects were calculated according to the 1995 World Health Organization criteria. RESULTS: There were 4781 (27.9%) men and 12,340 (72.1%) women. The mean age (+/- SD) was 51.3 +/- 16.0 years (range 20 to 96 years, median 49.8 years). Of the 17,121 subjects, 4939 (28.85%) were overweight and 656 (3.83%) were obese. Based on the 1997 Hong Kong Census statistics of the overall Hong Kong population data, the age-standardised prevalence rates of overweight and obese subjects were 30.52% and 3.19% in men and 22.14% and 3.35% in women, respectively. Of the 10,937 subjects of working age (20 to 65 years), the prevalence rates of overweight and obese subjects were 28.98% and 3.55%, respectively. Of the 6648 subjects aged > or = 60 years, the prevalence rates of overweight and obese subjects were 36.31% and 4.81%, respectively. CONCLUSIONS: In Hong Kong, the age-standardised prevalence rate of overweight and obese subjects were 30.5% and 3.2% in men and 22.1% and 3.4% in women, respectively. This information provides some useful estimations of the extent of an important public health problem, obesity, in Hong Kong.

Adult↗

PubMed2000

Concomitant management of airway and its adjacent vascular pathology in addition to repair of congenital cardiac defects.

Respiratory symptoms are often present in infants with congenital cardiac anomalies, but the intrinsic pathology of the airway itself or external compression by abnormal vessels is frequently undetected before cardiac repair. We collected 12 patients with airway pathology from July 1996 to October 1998; all had definite diagnosis of lesions of the airway and its adjacent vessels by preoperative ultrafast computed tomography. Four had intrinsic pathology (one retrotracheal diverticulum, three tracheal stenosis) as well as external compression. Among them, six had complete vascular ring, four partial rings and three had bronchial compression by aneurysmal dilatation of branch pulmonary arteries. Simultaneous airway repair (one diverticulectomy, three patch tracheoplasty) and external decompression were performed in ten cases under cardiopulmonary bypass, nine of ten had simultaneous cardiac repair; the other two were done before cardiac repair. All survived except three. We concluded that ultrafast computed tomography is indispensable for definite diagnosis of airway and adjacent cardiovascular pathology. Mere repair of congenital cardiac defects without rectification of the airway and its adjacent structures is incompatible with survival.

Aorta↗

PubMed2000

Area identity shifts in the early cerebral cortex of Emx2-/- mutant mice.

The specification of area identities in the cerebral cortex is a complex process, primed by intrinsic cortical cues and refined after the arrival of afferent fibers from the thalamus. Little is known about the genetic control of the early steps of this process, but the distinctive expression pattern of the homeogene Emx2 in the developing cortex has prompted suggestions that it is critical in this context. We tested this hypothesis using Emx2 -/- mice. We found that the normal spectrum of cortical areal identities was encoded in these mutants, but areas with caudal-medial identities were reduced and those with anterior-lateral identities were relatively expanded in the cortex.

Afferent Pathways↗

PubMed2000

The management of isolated thrombocytopenia in Chinese adults: does bone marrow examination have a role at presentation?

We performed a retrospective analysis of bone marrow examination (BME) in the management of Chinese adult patients less than 60 years of age with isolated thrombocytopenia at presentation. Eighty-three patients with a median age of 39 years presenting with isolated thrombocytopenia (median platelet count: 38 x 10(9)/l) had routinely undergone BME as part of the laboratory investigations during the period from January 1996 to December 1999. All 83 patients had bone marrow findings of active marrow suggesting causes due to peripheral destruction. All of these patients responded to steroid or intravenous immunoglobulin (IVIg) therapy at presentation if their platelet counts were significantly low or if they had mucosal bleeding. Eighty-one of the 83 patients, after a median of 20 months follow-up, were finally diagnosed as having idiopathic thrombocytopenic purpura (ITP). The remaining two patients were finally confirmed as cases of systemic lupus erythematosus (SLE). Our results suggest that BME is not helpful in the diagnosis of isolated thrombocytopenia or suspected ITP in adult patients at presentation, provided that a thorough clinical history and physical examination are undertaken and that the blood count and peripheral blood smear show no abnormalities apart from the thrombocytopenia.

Adolescent↗

PubMed2000

Quantitative volume replacement in the correction of post-traumatic enophthalmos.

We describe a technique to correct enophthalmos that involves measurement of the volume of the injured orbit followed by an accurate replacement of this volume with an autogenous bone graft. Twelve consecutive patients were treated with this technique and all but one showed an improvement in enophthalmos. Four of the seven with diplopia improved after the operation.

Bone Transplantation↗

PubMed2000

Time-kill studies of tea tree oils on clinical isolates.

Tea tree oil has recently emerged as an effective topical antimicrobial agent active against a wide range of organisms. Tea tree oil may have a clinical application in both the hospital and community, especially for clearance of methicillin-resistant Staphylococcus aureus (MRSA) carriage or as a hand disinfectant to prevent cross-infection with Gram-positive and Gramnegative epidemic organisms. Our study, based on the time-kill approach, determined the kill rate of tea tree oil against several multidrug-resistant organisms, including MRSA, glycopeptide-resistant enterococci, aminoglycoside-resistant klebsiellae, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, and also against sensitive microorganisms. The study was performed with two chemically different tea tree oils. One was a standard oil and the other was Clone 88 extracted from a specially bred tree, which has been selected and bred for increased activity and decreased skin irritation. Our results confirm that the cloned oil had increased antimicrobial activity when compared with the standard oil. Most results indicated that the susceptibility pattern and Gram reaction of the organism did not influence the kill rate. A rapid killing time (less than 60 min) was achieved with both tea tree oils with most isolates, but MRSA was killed more slowly than other organisms.

Anti-Infective Agents, Local↗

PubMed2000

Autologous bone marrow transplantation for patients with acute myeloid leukaemia: prospective follow-up study.

OBJECTIVE: To study the use of autologous bone marrow transplantation to treat acute myeloid leukaemia when complete remission had been achieved and when no human leukocyte antigen matched related donor was available. DESIGN: Prospective follow-up study. SETTING: Government hospital, Hong Kong. PATIENTS: Eight patients (median age, 34 years [range, 16-45 years]) with acute myeloid leukaemia in whom complete remission had been achieved. INTERVENTION: Conditioning regimen of carmustine, amsacrine, etoposide VP-16, cytarabine, and infusion of unpurged marrow. MAIN OUTCOME MEASURES: Median time taken to reach neutrophil and platelet counts of > or =0.5 x 10(9) /L and > or = x 10(9) /L, respectively; mortality and relapse rates; and follow-up regimens used. RESULTS: Engraftment was successfully achieved in all patients and there were no early procedure-related mortalities. The median times required to reach a neutrophil count of > or =0.5 x 10(9) /L and a platelet count of > or =20 x 10(9) /L were 30 days (range, 18-36 days) and 38 days (range, 15-53 days), respectively. The median duration of hospital stay was 37 days (range, 25-43 days). Two patients died of a relapse of leukaemia at 6 and 9 months post-transplantation. Two patients experienced relapses: one at 8 months post-transplantation, for which conventional chemotherapy was restarted, and one at 18 months; treatment with all-trans-retinoic acid and conventional chemotherapy achieved a third complete remission in the latter patient, who had acute promyelocytic leukaemia. Continuous remission has been achieved in four of the eight patients after a median follow-up duration of 26 months (range, 6-43 months). CONCLUSION: Autologous bone marrow transplantation is an acceptable treatment for patients with acute myeloid leukaemia who lack a human leukocyte antigen-matched related donor.

Acute Disease↗

PubMed2000

First successful ventricular septation of double inlet left ventricle in Taiwan.

Patients with a double inlet ventricle may undergo surgery using a modified Fontan procedure, in which the pulmonary ventricle is not utilized, or a procedure in which a pulmonary ventricle is created through ventricular septation. Ventricular septation is preferred to the Fontan procedure because there is better cardiorespiratory response to exercise after surgery. A 4-year-old girl with Holmes heart underwent ventricular septation on 12 May 1998. Pulmonary artery banding had been performed at 3 months of age and rebanding 16 days later. She was well and continued to grow. Ultrafast computed tomography and cardiac catheterization prior to surgery showed a double inlet left ventricle (LV) connected to a right posterior aorta with a right-sided rudimentary right ventricle that drained to the left anterior pulmonary trunk. Left ventricular end diastolic volume was 218% of normal and the ejection fraction was 79%. After debanding and enlargement of the bulboventricular foramen, a 3 x 4-cm composite patch of equine pericardium and Dacron velour was used to septate the ventricle, with transmural stitching at the apical portion. The patient survived the operation with complete atrioventricular block, and was extubated 6 days later. A permanent pacemaker was implanted 1 month later. One year after surgery, she was doing well. Echocardiography revealed paradoxical septal motion with good ventricular function. This is the first report of successful ventricular septation of a double inlet left ventricle performed in Taiwan.

Cardiac Surgical Procedures↗

PubMed1999

Genetic characterization of the hemagglutinin of two strains of influenza B virus co-circulated in Taiwan.

Two isolates of influenza B virus were obtained in the spring of 1997. One strain, B/Taiwan/21706/97, was isolated from a patient who had acute tonsillitis. The other, B/Taiwan/3143/97, was isolated from a patient who was diagnosed with meningoencephalitis. This implies that the influenza B viruses not only cause respiratory symptoms but may also cause inflammation of the nervous system. Sequence analysis of the hemagglutinin (HA) gene, HA1 domain, indicated that there were remarkable amino acid changes in the strain B/Taiwan/3143/97 compared to B/Victoria/2/87, B/Yamagata/16/88, and B/Taiwan/7/88. The changes in the positions 116, 200, 238, 242, and 271 were correlated with receptor binding. Furthermore, a potential glycosylation site at position 233 was lost. In total, 30 amino acid changes were noted at positions ranging from 116 to 295. These changes may affect the antigenicity of the virus. Phylogenetic analyses also showed that the B/Taiwan/3143/97 was located in an independent lineage, when compared to the reference strains belonging to B/Victoria/2/87 and B/Yamagata/16/88 lineages. This supports the hypothesis that influenza B viruses with distinct genetic characteristic were co-circulated in Taiwan.

Base Sequence↗

PubMed1999

Improved recovery of Mycobacterium tuberculosis from pleural aspirates: bedside inoculation, heparinized containers and liquid culture media.

The effects of bedside inoculation, heparinized containers and liquid culture media on the recovery of Mycobacterium tuberculosis from pleural aspirates were evaluated in this study. Of 155 patients, 63 were diagnosed to have pleural effusion tuberculous in origin. The overall recovery of M. tuberculosis was 57.1%. Bedside inoculation of the specimens produced a significantly higher yield than laboratory inoculation using non-heparinized specimens. When the pleural aspirates were transported in heparinized containers, the recovery rate was comparable to that from bedside inoculation, but lower when non-heparinized containers were used. No significant difference was found in recovery rate between the two liquid media, but the rate was significantly higher with the use of liquid media than conventional solid media. Thus, bedside inoculation of pleural aspirates, use of heparinized containers for transport for delayed inoculation in the laboratory and use of liquid culture media are recommended.

Anticoagulants↗