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Biomedical subjects

R Sung

Publications and source records attributed to R Sung.

17 recordsLinked to original sources
PubMed2005

The six-minute walk test in healthy children: reliability and validity.

The aim of this study was to assess the reliability and validity of the 6-min walk test (6MWT) in healthy children. Chinese secondary school students were randomly recruited. They attended the current authors' unit on two occasions, separated by 2 weeks. Physical examination and standardised maximum incremental exercise testing on a treadmill were performed on the first visit. Spirometry and 6MWT were carried out on the second visit. A randomly selected subgroup was invited to return for repeat 6MWT at an interval of 2-4 weeks. Seventy-eight subjects were recruited; however, four failed to achieve maximal effort on exercise test. The final group included 43 young females and the mean+/-sd age of the subjects was 14.2+/-1.2 yrs. Physical examination was unremarkable in all cases. The mean+/-sd per cent predicted forced expiratory volume in one second was 91.4+/-10.2%. Concurrent validity was demonstrated by good correlation between the 6-min walking distance and maximum oxygen uptake determined on the exercise treadmill. Test-retest reliability was undertaken in 52 subjects, and the intraclass correlation coefficient (95% confidence interval) was calculated as 0.94 (0.89-0.96). In addition, Bland and Altman plots demonstrated a high degree of repeatability. In healthy children, the 6-min walk test is a reliable and valid functional test for assessing exercise tolerance and endurance.

Adolescent↗
PubMed2002

Gene therapy in transplantation.

Gene transfer and gene therapy represent a relatively new field that has grown and expanded enormously in the last 5-10 years. The application of gene transfer and gene medicines to transplantation is currently in its infancy. Consideration for gene medicines in transplantation requires delivery of vectors, either to the graft or to the immune system. Delivery of vectors to the graft provides a choice of potential immunologic targets including: costimulatory signals; inhibitory cytokines; adhesion molecules; and molecules relating to apoptosis. In addition, non-immunologic targets, that increase graft protective mechanisms by reducing ischemic and immunologic damage, represent significant targets for gene transfer. Delivery of vectors to the immune system includes potential targets to modify the immune system, and results in tolerance. Other considerations for gene therapy include the development of additional technologies, such as gene conversion or transgenesis coupled with xenotransplantation, which may provide genetically modified organs. Another important aspect of gene transfer relates to regulation of the transgene expression. A variety of issues concerning innate immunity, adaptive immunity, response to vector components, response to transgene products, and entry of vectors into the antigen presentation and processing pathway require further investigation and refinement of approaches. Lastly, regulatable promoters and the understanding of their interaction with individual cells, tissues and organs, and their interaction with innate and adaptive immunity, are of paramount importance to improving the efficacy and utility of gene transfer. There is no doubt that there is much exciting basic and translational science to be accomplished in the next decade in order to solve these potential barriers and advance gene medicines into the clinical realm in transplantation.

Abatacept↗
PubMed2001

Lower BMI cut-off value to define obesity in Hong Kong Chinese: an analysis based on body fat assessment by bioelectrical impedance.

There is increasing evidence suggesting that the cut-off values for defining obesity used in the Western countries cannot be readily applied to Asians, who often have smaller body frames than Caucasians. We examined the BMI and body fat (BF) as measured by bioelectrical impedance in 5153 Hong Kong Chinese subjects. We aimed to assess the optimal BMI reflecting obesity as defined by abnormal BF in Hong Kong Chinese. Receiver operating characteristic curve (ROC) analysis was used to assess the optimal BMI predicting BF at different levels. The mean age and SD of the 5153 subjects (3734 women and 1419 men) was 51.5 (SD 16.3) years (range: 18.0-89.5 years, median: 50.7 years). Age-adjusted partial correlation (r) between BMI and BF in women and men were 0.899 (P < 0.001) and 0.818 (P < 0.001) respectively. Using ROC analysis, the BMI corresponding to the conventional upper limit of normal BF was 22.5-23.1 kg/m(2), and the BMI corresponding to the 90 percentiles of BF was 25.4-26.1 kg/m(2). Despite similar body fat contents, the BMI cut-off value used to define obesity in Hong Kong Chinese should be lower as compared to Caucasians. We suggest a BMI of 23 kg/m(2) and 26 kg/m(2) as the cut-off values to define overweight and obesity respectively in Hong Kong Chinese.

Absorptiometry, Photon↗
PubMed2000

Population genetic implications from sequence variation in four Y chromosome genes.

Some insight into human evolution has been gained from the sequencing of four Y chromosome genes. Primary genomic sequencing determined gene SMCY to be composed of 27 exons that comprise 4,620 bp of coding sequence. The unfinished sequencing of the 5' portion of gene UTY1 was completed by primer walking, and a total of 20 exons were found. By using denaturing HPLC, these two genes, as well as DBY and DFFRY, were screened for polymorphic sites in 53-72 representatives of the five continents. A total of 98 variants were found, yielding nucleotide diversity estimates of 2.45 x 10(-5), 5. 07 x 10(-5), and 8.54 x 10(-5) for the coding regions of SMCY, DFFRY, and UTY1, respectively, with no variant having been observed in DBY. In agreement with most autosomal genes, diversity estimates for the noncoding regions were about 2- to 3-fold higher and ranged from 9. 16 x 10(-5) to 14.2 x 10(-5) for the four genes. Analysis of the frequencies of derived alleles for all four genes showed that they more closely fit the expectation of a Luria-Delbrück distribution than a distribution expected under a constant population size model, providing evidence for exponential population growth. Pairwise nucleotide mismatch distributions date the occurrence of population expansion to approximately 28,000 years ago. This estimate is in accord with the spread of Aurignacian technology and the disappearance of the Neanderthals.

Aged↗
PubMed1999

Comparison of healing process in open osteotomy model and closed fracture model.

OBJECTIVE: Comparison of the healing process in open osteotomy and closed fracture models that were used to study fracture healing. DESIGN: Randomized, prospective study in experimental animals, with a recovery duration of two and four weeks. SETTING: Unrestricted cage activity with weight bearing as tolerated. ANIMALS: Thirty-four skeletally mature, female New Zealand White rabbits. INTERVENTIONS: Closed fractures and open osteotomies of the tibial diaphysis were reduced and immobilized with four-pin, double-bar external fixators. MAIN OUTCOME MEASUREMENTS: Callus circumference was measured with a tape measure, bridging callus was assessed on biplane radiographs and evaluated histologically, and torsional stiffness and maximum torque were measured. RESULTS: Periosteum damage was more severe and hematoma formation was smaller in the osteotomy model, resulting in a delay in biological healing and restoration of the biomechanical properties. CONCLUSIONS: Investigators should consider the difference between the closed fracture and open osteotomy models when selecting an animal model to investigate fracture healing.

Animals↗
PubMed1999

Isolation of Helicobacter pylori from vomitus in children and its implication in gastro-oral transmission.

OBJECTIVE: The route of transmission of Helicobacter pylori (H. pylori) is unclear. Gastro-oral transmission via contaminated vomitus has been proposed as an important mode of transmitting H. pylori, especially in children. This pilot study attempted to isolate H. pylori from the vomitus of children. METHODS: Children presenting for evaluation with gastroenteritis-associated vomiting were studied. Fresh vomitus samples were collected for detection of H. pylori by bacteriological culture and polymerase chain reaction, (PCR). A rapid, whole blood test was used to determine the H. pylori status of patients. RESULTS: A total of 18 children with mean age of 6 yr were studied; four had a positive serology test. Among these four children, H. pylori was isolated from vomitus by culture in one child and by PCR in two. An 18-month-old girl with negative serology had H. pylori detected in vomitus by PCR. Six months later, she had seroconversion confirmed, suggesting that she had an acute H. pylori infection on initial presentation. CONCLUSIONS: This is the first study reporting successful isolation of H. pylori from naturally produced vomitus. The result implies that transmission of H. pylori infection by vomitus, especially in children, is possible.

Adolescent↗
PubMed1998

Clinical features and rapid viral diagnosis of human disease associated with avian influenza A H5N1 virus.

BACKGROUND: Human infection with an avian influenza A virus (subtype H5N1) was reported recently in Hong Kong. We describe the clinical presentation of the first 12 patients and options for rapid viral diagnosis. METHODS: Case notes of 12 patients with virus-culture-confirmed influenza A H5N1 infection were analysed. The clinical presentation and risk factors associated with severe disease were defined and the results of methods for rapid virus diagnosis were compared. FINDINGS: Patients ranged from 1 to 60 years of age. Clinical presentation was that of an influenza-like illness with evidence of pneumonia in seven patients. All seven patients older than 13 years had severe disease (four deaths), whereas children 5 years or younger had mild symptoms with the exception of one who died with Reye's syndrome associated with intake of aspirin. Gastrointestinal manifestations, raised liver enzymes, renal failure unrelated to rhabdomyolysis, and pancytopenia were unusually prominent. Factors associated with severe disease included older age, delay in hospitalisation, lower-respiratory-tract involvement, and a low total peripheral white blood cell count or lymphopenia at admission. An H5-specific reverse-transcription PCR assay (RT-PCR) was useful for rapid detection of virus directly in respiratory specimens. A commercially available enzyme immunoassay was more sensitive than direct immunofluorescence for rapid viral diagnosis. Direct immunofluorescence with an H5-specific monoclonal antibody pool was useful for rapid exclusion of H5-subtype infection. INTERPRETATION: Avian Influenza A H5N1 virus causes human influenza-like illness with a high rate of complications in adults admitted to hospital. Rapid H5-subtype-specific laboratory diagnosis can be made by RT-PCR applied directly to clinical specimens.

Adult↗
PubMed1998

Haemophilus influenzae type b infections in Hong Kong.

A 5-year territory-wide retrospective survey of invasive Haemophilus influenzae type b (Hib) diseases in Hong Kong established that the annual incidence for children <5 years old was 2.7 per 100000 [95% confidence interval (CI), 2.0 to 3.5]. However, the corresponding annual incidence in Vietnamese refugees in Hong Kong was 42.7 per 100000 (95% CI 17.2 to 87.9), giving a relative risk of 18.5 (95% CI 8.3 to 41.0). The nasopharyngeal carriage rate of Hib was zero in 621 healthy Chinese children and 1.3% (95% CI 0.04 to 2.63%) in 300 healthy Vietnamese refugees 2 months to 5 years old in Hong Kong. The corresponding carriage rate of nontypable H. influenzae was 5.8% (95% CI 1.4 to 7.6%) in Chinese and 65.4% (95% CI 58.9 to 69.8) in Vietnamese. In a larger study of 1812 healthy Chinese children between 6 months and 5 years of age investigated by throat swabs, again no Hib was isolated but 141 children (7.8%) were found to be carriers of nontype b H. influenzae. In a study of 596 healthy Chinese children and adults, 25% had the protective level of anti-Hib antibody of >0.15 microg/ml by 1 year and 90% had reached >0.15 microg/ml by 6 years of age. There was some evidence that these "natural" antibodies against Hib in Hong Kong Chinese were cross-reacting antibodies against antigens on other encapsulated bacteria.

Antibodies, Bacterial↗
PubMed1997

Low-dose warfarin prophylaxis to prevent symptomatic pulmonary embolism after total knee arthroplasty.

Pulmonary embolism poses a risk to patients undergoing total knee arthroplasty. The selection of an appropriate prophylaxis agent and its implementation have been influenced by decreased duration of hospital stay and the pressures of cost containment. The purpose of this study was to determine the inpatient and outpatient pulmonary embolism rates, the number of days required to attain the target level of anticoagulation, and complications associated with the use of a low-dose warfarin prophylaxis protocol after primary and revision total knee arthroplasty. Between 1984 and 1993, there were 815 primary and revision total knee arthroplasties that received low-dose warfarin prophylaxis at our institution. The average time to attainment of the target level of anticoagulation was 3 days. The average duration of warfarin prophylaxis was 12 days. Overall, there were a total of three symptomatic pulmonary embolisms (0.3%; 95% confidence interval, 0.08%-1.1%). There were eight (1%) symptomatic deep vein thromboses (all distal). There were two deaths (0.3%), but neither one was secondary to a pulmonary embolism. Seventeen knees (2.5%) developed a hematoma after surgery, and two of these patients required drainage of the knee. Low-dose warfarin prophylaxis is safe and effective in preventing symptomatic pulmonary embolism after total knee arthroplasty.

Adult↗
PubMed1997

Calcifying fibrous pseudotumor of mediastinum--a case report.

This report presents a case of calcifying fibrous pseudotumor arising in the posterior mediastinum of a 54-year-old woman. The histopathologic features of this case were identical to that of calcifying fibrous pseudotumor first designated in 1993. It is a distinctive benign fibrous lesion characterized by the presence of characteristics psammomatous or dystrophic calcification, abundant hyalinized collagen and lymphoplasmacytic cell infiltrate. Immunohistochemically most of the scattered fibroblasts were positive for vimentin, but not for CD-34 and cytokeratins, distinguishing it from solitary fibrous tumor of pleura and desmoplastic mesothelioma. The unusual site of the posterior mediastinum and the old age characterize this case.

Age Factors↗
PubMed1984

Phase image evaluation of patients with ventricular pre-excitation syndromes.

To localize bypass pathways, left and right ventricular regions were analyzed at rest by phase image analysis in 18 patients with ventricular pre-excitation syndromes. These were compared with image findings in 18 normal subjects. In each of 17 patients with pre-excitation, the site localized on electrophysiologic study correlated closely with the region of earliest ventricular phase angle. This site could be objectively separated from that in normal subjects in each of eight patients with an active left-sided pathway and in both patients with a right-sided pathway. Those with a septal pathway revealed earliest septal phase angle, but could not be separated from normal subjects. In the eight patients with an active left bypass tract, the onset, upstroke and peak of the left ventricular phase histogram preceded those of the right ventricular histogram. Those with a left-sided pathway demonstrated a mean left ventricular phase angle, a difference between mean left and mean right ventricular phase angle and a difference between earliest left and right ventricular phase angles which was significantly less than that in normal subjects (p less than 0.05). These variables presented characteristic converse changes in those with a right-sided pathway. Sequential phase changes in 10 studies suggested "fusion" of normal septal with lateral bypass fronts. Electrocardiographic and electrophysiologic localization of the bypass pathway agreed in only 8 of 14 patients with a recognized delta wave. The phase image represents a new, noninvasive method of evaluating ventricular pre-excitation. The method may provide useful information complementary to that of electrocardiographic and electrophysiologic analysis.

Adolescent↗
PubMed1978

Functional significance of electrocardiographic changes after left ventricular aneurysmectomy.

Electrocardiographic (ECG) changes after left ventricular aneurysmectomy were analyzed in 20 patients, thirteen of whom had additional aorto coronary saphenous vein bypass surgery. ECG changes were correlated with postoperative clinical and hemodynamic results. Out of 14 patients (Group I) who showed hemodynamic and/or clinical improvement, eight had decrease of chronic ST segment elevation that was associated in five with loss of pathologic Q waves. In the remaining six patients (Group II) who showed no hemodynamic or clinical improvement as well as in six patients in Group I, chronic ST segment elevation persisted or increased and in some, new pathologic Q waves developed after surgery. The study suggests that loss of pathologic Q waves and/or decrease of chronic ST segment elevation in patients who undergo a left ventricular aneurysmectomy with aorto coronary saphenous vein bypass surgery may reflect postoperative clinical, hemodynamic and angiographic improvement. On the other hand, failure of these ECG changes to occur or, conversely, increased ST segment elevation and/or appearance of new Q waves may have no predictive value. The mechanisms for these ECG changes are discussed.

Adult↗