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Biomedical subjects

K C Ng

Publications and source records attributed to K C Ng.

At least 19 recordsLinked to original sources
PubMed2006

Analytical model of magnetic nanoparticle transport and capture in the microvasculature.

An analytical model is presented for predicting the transport and capture of therapeutic magnetic nanoparticles in the human microvasculature. The nanoparticles, with surface bound drug molecules, are injected into the vascular system upstream from malignant tissue, and are captured at the tumor site using a local applied magnetic field. The applied field is produced by a rare-earth cylindrical magnet positioned outside the body. An analytical expression is derived for predicting the trajectory of a particle as it flows through the microvasculature in proximity to the magnet. In addition, a scaling relation is developed that enables the prediction of the minimum particle radius required for particle capture. The theory takes into account the dominant magnetic and fluidic forces, which depend on the position and properties of the magnet, the size and magnetic properties of the nanoparticles, the dimensions of the microvessel, the hematocrit level of the blood, and the flow velocity. The model is used to study noninvasive drug targeting, and the analysis indicates that submicron particles can be directed to tumors that are several centimeters from the field source.

Antineoplastic Agents↗
PubMed2005

Otorhinolaryngeal foreign bodies in children presenting to the emergency department.

INTRODUCTION: Accidents with foreign bodies are common in the paediatric population. It is impossible to mandate that all foreign bodies (FB) in the ear, nose and throat (ENT) of children should be removed by the specialty-trained physicians. This study evaluates the management of ENT FB removal in children achieved by emergency physicians not trained in otolaryngology in an urban tertiary care paediatric emergency department. METHODS: A retrospective study was conducted on consecutive paediatric patients presenting with suspected foreign body in the ear, nose or throat to the children's emergency department (ED) of KK Women's and Children's Hospital over a 10-month period. Removal methods, foreign body types, rates of successful removal and associated complications were evaluated. RESULTS: There were 353 patients, most of whom presented after office hours. An attempt at removal of FB by the emergency physician was made in 76.8 percent of the cases. ENT specialist referral in the ED was made in 1.7 percent of the cases. 50.1 percent of cases were discharged after successful removal of FB in the ED. 4.2 percent of cases were admitted for removal of FB and 44.8 percent of cases were referred to the ENT specialist clinic for further assessment. CONCLUSION: The emergency physician managed most cases in the ED and urgent referral to ENT specialists was not required. Complications and morbidity often occur from repeated attempts at removal of the FB. ENT opinion should be sought whenever there is doubt. The ED physician should be skilled in techniques of FB removal, especially throat FB, which had the lowest rate of success in our study.

Age Distribution↗
PubMed2004

Bacterial meningitis in Hong Kong: 10-years' experience.

OBJECTIVE: We studied the etiology, clinical features and outcome of patients with bacterial meningitis from an urban Chinese city over a 10-years period. METHODS: We reviewed the files of all persons aged 15-years old or above diagnosed with community-acquired bacterial meningitis from a regional hospital. The clinical findings, relevant laboratory and imaging results as well as outcome were recorded in cases with microbiological evidence of meningitis. Neurosurgical and pediatric patients were excluded. RESULTS: Sixty-five patients between the ages of 15 and 86 years of age (mean 52 years) were identified of whom 18 (28%) died. The four most common causes were Mycobacteria tuberculosis (46%), Streptococcus pneumoniae (11%), Streptococcus suis (9%) and Klebsiella pneumoniae (8%). Neisseria meningitidis and Haemophilus influenzae were rare pathogens. The annual incidence of community-acquired bacterial meningitis was 1.27/100,000 adults. Delay in treatment was associated with a poorer prognosis (p<0.001, OR=38.84, CI=7.33-205.80). CONCLUSION: The causative organisms found in this region of China differ from that reported from Europe and the US; tuberculous meningitis is the most common cause of bacterial meningitis.

Adolescent↗
PubMed2004

Risk factors and clinical consequences of human herpesvirus 7 infection in paediatric haematopoietic stem cell transplant recipients.

Human herpesvirus 7 (HHV-7) is the least studied beta-herpesvirus in transplant settings. This prospective study examined the activity of HHV-7 during the first 12 weeks post-stem cell transplant in 59 paediatric patients. The presence of HHV-7, human cytomegalovirus (HCMV) and human herpesvirus 6 (HHV-6) in blood was monitored weekly by a multiplex nested polymerase chain reaction. Overall, 33 (55.9%) patients had one or more surveillance blood sample(s) positive for HHV-7. In contrast to HCMV and HHV-6, no obvious peak time of reactivation was observed for HHV-7. The occurrence of HHV-7 DNAaemia showed a significant negative association with HHV-6 (P=0.022), but with no association with HCMV. A significant higher positive rate for HHV-7 was found in autologous versus allogeneic (P=0.002), and in peripheral blood versus umbilical cord/marrow (P<0.001) transplant. Acyclovir had no effect, whereas ganciclovir was associated with a lower rate of HHV-7 reactivation (P=0.009). One patient died of HHV-7 associated brain stem encephalitis. The administration of colony stimulating factor, occurrence of acute graft versus host disease, time to neutrophil and platelet engraftment showed no significant association with the occurrence of HHV-7 DNAaemia.

Acyclovir↗
PubMed2004

Spermine reduces infarction and neurological deficit following a rat model of middle cerebral artery occlusion: a magnetic resonance imaging study.

The role of nitric oxide (NO) in post-ischemic cerebral infarction has been extensively examined, but few studies have investigated its role on the neurological deficit. In the present study, we investigated the effect of spermine on the temporal evolution of infarct volume, NO production and neurological deficit using magnetic resonance imaging in a model of permanent focal cerebral ischemia in rats. Spermine given at 10 mg/kg 2 h after ischemia reduced the infarct volume by 40% and abolished brain NO production and improved the neurological score 24 h, 48 h and 72 h after ischemia. Spermine also reduced the neurological deficit as evaluated by rotamex, grip strength and neurological severity score tests.

Analysis of Variance↗
PubMed2003

Significance of genomic DNA group delineation in comparative studies of antimicrobial susceptibility of Acinetobacter spp.

There were significant differences in antimicrobial susceptibilities in isolates of genomic DNA groups 2 (Acinetobacter baumannii), 3, and 13TU collected from the same sources, e.g., patients in intensive care units and general wards, and in isolates of the same group collected from different sources. The delineation of genomic groups is important in comparative surveillance studies of antimicrobial susceptibilities.

Acinetobacter↗
PubMed2003

Acute bacterial gastroenteritis: a study of adult patients with positive stool cultures treated in the emergency department.

OBJECTIVES: To investigate the presenting clinical features of acute bacterial gastroenteritis in adult patients treated as outpatients in the emergency department (ED), and the pathogens responsible in this setting and population; and to identify the frequency with which positive stool culture result changes management. METHOD: This was a retrospective study of all patients who attended the accident and emergency department of an university affiliated hospital in Hong Kong over a 12 month period, who satisfied the following inclusion criteria: (a) age >/=16, (b) presented with acute gastroenteritis, (c) treated as outpatients with or without observation, and (d) had positive stool cultures. RESULTS: One hundred and thirty patients were included. Pathogens identified were Vibrio parahaemolyticus (42.3%), Samonella spp (34.6%), Plesiomonas spp (9.2%), Campylobacter spp (6.9%), Aeromonas spp (6.9%), and Shigella spp (6.2%). Mean highest body temperature was 37.5 degrees C (95% confidence intervals (CI) 37.3 to 37.6). Bloody diarrhoea was present in 14 patients (10.8%). Mean duration of diarrhoea, from onset to the completion of stay in ED, was 2.2 days (95% CI 1.7 to 2.7). Likewise, mean duration of abdominal pain was 1.8 days (95% CI 1.5 to 2.1). Mean number of unformed stools per day was 9.3 (95% CI 8.3 to 10.3). Change of management, subsequent to the availability of positive stool culture results, was not required in 115 (88.5%) patients. Ciprofloxacin resistance occurred in eight (6.2%) cases, and seven of nine campylobacter isolates. Campylobacter positive patients had a significantly longer duration of abdominal pain (p=0.0236) and were less likely to be dehydrated (p=0.0103). CONCLUSIONS: Most patients with bacterial gastroenteritis do not present with high fever, bloody diarrhoea, or persistent diarrhoea, but generally have quite severe diarrhoea. Stool cultures do not change management for most patients. Vibrio parahaemolyticus is the commonest bacterial pathogen identified.

Acute Disease↗
PubMed2003

Severe acute respiratory syndrome-associated coronavirus infection.

Whether severe acute respiratory syndrome-associated coronavirus (SARS-CoV) infection can be asymptomatic is unclear. We examined the seroprevalence of SARS-CoV among 674 healthcare workers from a hospital in which a SARS outbreak had occurred. A total of 353 (52%) experienced mild self-limiting illnesses, and 321 (48%) were asymptomatic throughout the course of these observations. None of these healthcare workers had antibody to SARS CoV, indicating that subclinical or mild infection attributable to SARS-CoV in adults is rare.

Adult↗
PubMed2003

Paracetamol ingestions at the Children's Emergency Department--a three year series.

This is a three-year retrospective review of 96 cases of paracetamol ingestions seen by KK Children's Emergency Department. Paracetamol is the commonest substance (23%) involved in childhood poisonings. More than 60% occurred in children aged one to three years old with an equal gender distribution. Eighty-six percent were accidental ingestions and the intentional ones had a significant female bias, all occurring in children aged 12 and above. These older children ingested higher doses of paracetamol (average dose of 233 mg/kg) and had potentially serious serum paracetamol levels. There was no significant morbidity and no mortality in this series.

Acetaminophen↗
PubMed2002

Temperature-entropy formulation of thermoelectric thermodynamic cycles.

A temperature-entropy formulation is derived for thermoelectric devices. Thermoelectric chiller and generator cycles can then be cast in the same irreversible thermodynamics framework commonly applied to conventional large-scale cooling and power generation equipment, including a transparent identification of the principal energy flows and performance bottlenecks (dissipation). Distinct differences in chiller versus generator mode are highlighted and illustrated with data from commercial thermoelectric units.

Journal Article↗
PubMed2002

Sedation with ketamine for paediatric procedures in the emergency department--a review of 500 cases.

Ketamine has been used to "consciously" sedate patients for a variety of paediatric procedures in our department since 1998. This is a retrospective review of the first 500 paediatric patients given ketamine for conscious sedation. Ketamine was given, either intramuscularly (3-4 mg/kg) or intravenously (1-2 mg/kg) together with atropine (0.02 mg/kg), with or without intravenous midazolam (0.05 mg/kg). The main indications for giving ketamine were for laceration repair, especially those of the lip, tongue and buccal mucosa (54.4%); manipulation and reduction of upper limb fractures (25.8%); incision and drainage of abscesses (12%), removal of foreign bodies (6.4%) and a potpourri of other conditions. Seventy-five point six percent of our patients were less than six years old and the male to female ratio was 1.9:1. Ninety-six percent of our patients were discharged home well and only one child (0.2%) was admitted for observation possibly as a consequence of ketamine. We find ketamine to be a relatively effective drug for use for conscious sedation in children.

Adolescent↗
PubMed2002

Homocysteine, folate and vitamin B12 as risk factors for acute myocardial infarction in a Southeast Asian population.

INTRODUCTION: Hyperhomocysteinaemia is an emerging risk factor for coronary artery disease (CAD) and most studies done to date are in Caucasian populations. We aimed to determine whether hyperhomocysteinaemia is a risk factor for acute myocardial infarction (AMI) in a Southeast Asian population comprising different ethnic groups and relate it to the traditional risk factors and plasma vitamin B12 and folate levels. MATERIALS AND METHODS: This was a case-control study comprising 168 AMI patients and 141 controls with a median age of 55 years (range, 27 to 77 years), living in Singapore. Homocysteine was measured by fluorescence polarisation immunoassay and vitamin B12 and folate were measured by electrochemiluminescence immunoassay. Logistic regression analysis was use to test the association of homocysteine, vitamin B12 and folate with the occurrence of AMI. The study was approved by the Tan Tock Seng Ethics Committee. RESULTS: We found that the odds of having AMI was higher for subjects with hypertension, smoking habit, lower plasma folate and vitamin B12 levels and non-Chinese ethnic group. On the other hand, plasma homocysteine level was not significantly associated with AMI. The baseline levels of plasma total homocysteine in both AMI patients and controls were higher than other studies (median values between 12 and 14 umol/L). CONCLUSION: In our population, plasma total homocysteine levels were not associated with AMI but low plasma levels of folate and vitamin B12 were independently associated.

Adult↗
PubMed2001

Prevalence and genotype distribution of TT virus in various specimen types from thalassaemic patients.

Peripheral blood mononuclear cells (PBMC), plasma, saliva and urine samples were collected from 50 thalassaemic patients for TT virus (TTV) detection by two sets of PCR. The set B nested PCR was more sensitive than the widely used NG hemi-nested PCR with TTV positive rates approximately PBMC: 98% vs. 70%; plasma: 92% vs. 66%; saliva: 62% vs. 22%; urine: 22% vs. 6%. All 50 patients had TTV detected in one or more specimens, with 16% of patients being positive in all four specimen types: 40% positive in PBMC, plasma and saliva; 30% positive in PBMC and plasma. In 82 NG hemi-nested PCR-positive samples TTV genotype was identified, 68.3% had a single genotype, 25.6% had multiple genotypes and 6.1% were uncharacterized. The positive rates for genotypes by specimen were: G1 (36/82), G2 (49/82), G3 (2/82), G4 (7/82), G5 (1/82) and G6 (3/82). Among the 42 patients for whom the genotype was examined, 42.9% had single-type infection, 45.2% had co-infections and 11.9% had uncharacterized genotypes. Sixteen of them had TTV detected both in PBMC and plasma with seven having identical genotypes in both samples. Eight patients had TTV detected in PBMC, plasma and saliva; two of them harboured identical genotypes in all three samples. The results indicate that, apart from hepatocytes, PBMC is a major cell type for TTV infection occurs. Shedding of TTV in urine and saliva is common and may have a significant role in nonblood-borne transmission among the general population. TTV-infected patients often harbour multiple genotypes suggesting infection with one genotype does not necessarily confer protection against the others. No correlation between TTV infection and liver dysfunction was observed.

DNA Virus Infections↗
PubMed2001

Hyperglycemia and its related factors in Taiwanese middle-aged adults.

Our study used data collected in Chung-Hsing Village to evaluate the relationship between hyperglycemia and its related factors in Taiwanese middle-aged adults in May 1998. All government employees at the Taiwan Provincial Government in Chung-Hsing Village aged 40-64 years were candidates for this study. Only 708 volunteers completed a structured questionnaire and underwent venous blood tests. To study the significant related factors of hyperglycemia, the t-test, chi(2) analysis and multivariate logistic regression were used. Our results showed that 40% of the 708 subjects were men and 60% were women. The mean age was 50.5 plus minus 6.8 years. The mean values of fasting glucose were 4.68 plus minus 1.92 mmol/L in men and 4.70 plus minus 1.70 mmol/L in women (P > 0.05). The proportions of hyperglycemia were 6.4% in men and 5.7% in women (P > 0.05). After controlling for other covariates, the multivariate logistic regression analysis showed that the significant related factors for hyperglycemia were older age (odds ratio=2.86, 95%; confidence interval=1.36-6.05; P < 0.01) and hypertriglyceridemia (odds ratio=3.34, 95%; confidence interval=1.68-6.64; P < 0.001).

Adult↗
PubMed2001

Were there enough physicians in an emergency department in the affected area after a major earthquake? An analysis of the Taiwan Chi-Chi earthquake in 1999.

STUDY OBJECTIVE: The purpose of this study was to evaluate physician manpower and mobilization in an urban emergency department receiving patients after a major earthquake. METHODS: Patient charts were reviewed. The workload of physicians was assessed semiquantitatively before and after a major earthquake. The physicians' mobilization in the postearthquake emergency response was assessed by using a confidential questionnaire. RESULTS: In the 3 days after the earthquake, 566 patients with earthquake-related illnesses or injuries were sent to the urban ED. Three hundred one (53.2%) patients arrived within the initial 10 hours. In the initial hours, there was no significant difference between the number of patients per physician per hour before and after the earthquake. Workloads of wound treatment and advanced life support procedures were significantly higher after the earthquake compared with before the earthquake, during the first to sixth hour and second to fifth hour, respectively. Sixty-five percent of the hospital's physicians did not assist in either the ED or in any other parts of the hospital in the initial 6 hours after the earthquake. CONCLUSION: The number of physicians in the ED was insufficient in the initial hours after the earthquake because of the sudden influx of a large number of patients. Future disaster planning must address the issue of physicians' behavior with regard to their priorities immediately after a major earthquake and include greater provision for efficient mobilization of physicians.

Disasters↗
PubMed2001

Epidemiology and infection control implications of Acinetobacter spp. in Hong Kong.

In a previous study, we showed that Acinetobacter genomic DNA group 3 was the most common species among blood culture isolates and was commonly found on superficial carriage sites of the healthy and the sick, which are different findings from those reported in Europe and North America. We used amplified ribosomal DNA restriction analysis and pulsed-field gel electrophoresis to study further the molecular epidemiology of acinetobacters in our region. Over a study period of 6 weeks with 136 consecutive routine clinical isolates (1.33% of all specimens), genomic DNA groups 2 (Acinetobacter baumannii), 3, and 13TU were obtained from 59 of 69 positive patients. There is a significant difference in the specimen sources of the three genomic DNA groups, with group 13TU being significantly associated with the respiratory tract (chi-square exact test, P = 0.0064). Settle plates showed a significantly heavier environmental load from the intensive care unit (ICU) than from the four surgical wards examined (22 of 70 versus 76 of 120 plates with <5 colonies; chi-square test, P < 0. 0001). Genomic group 3 accounted for 6 of 12 clusters of possibly related strains among patients, between patients and the ICU environment, and in the ICU environment. Genomic groups 2 and 3 accounted for 21% of the 132 genomically identified isolates recovered from 21 of 41 local vegetables, 53 of 74 fish and meat samples, and 22 of 60 soil samples. Group 13TU was present only in patients' immediate surroundings. The role played by the environment and by human carriage should be evaluated in order to devise a cost-effective infection control program pertinent to our situation of acinetobacter endemicity.

Acinetobacter↗
PubMed2001

Neoadjuvant chemotherapy for Chinese women with locally advanced breast cancer.

Locally advanced breast cancer carries a poor prognosis and is still prevalent in developing countries. The current management usually involves administration of neoadjuvant chemotherapy (NCT). From March 1990 through December 1997, 173 Chinese patients with tumor size greater than 4 cm were treated; 38 received NCT and the other 135 postoperative adjuvant chemotherapy. The regimens for NCT were FEC (5-fluorouracil 600 mg/m2, epirubicin 50 mg/m2, and cyclophosphamide 600 mg/m2) for 29 patients and Adriamycin 75 mg/m2 for the rest of the group. Postoperatively the NCT patients received the standard CMF regimen (oral cyclophosphamide 100 mg/m2 for 14 days and intravenous methotrexate 40 mg/m2 and 5-fluorouracil 600 mg/m2 on days one and eight of each cycle). The postoperative adjuvant chemotherapy group received only the CMF regimen. Tumor response after NCT was measured clinically and histologically. The response rate was 75 per cent with 13.2 per cent being complete response. Although there is no difference in response rate the actual reduction in size was greater for patients receiving Adriamycin than FEC (P = 0.001). The only predictive factor of response to NCT was the type of chemotherapy administered. None of the tumor characteristics such as size, nodal status, histological grading, lymphovascular permeation, hormonal receptor status, and c-erb-B2 expression were found to be significant. The overall 5-year probability of survival was 0.44, and there was no difference between groups. The factor important for prognosis was axillary nodal status on histology. The use of NCT did not improve outcome. In summary our results showed that NCT was feasible for Chinese women and good response could be achieved. However, it is the axillary nodal status that determines the final outcome.

Adult↗