Biomedical subjects

R Y Sung

Publications and source records attributed to R Y Sung.

At least 19 recordsLinked to original sources

PubMed2001

Pathology of fatal human infection associated with avian influenza A H5N1 virus.

Eighteen cases of human influenza A H5N1 infection were identified in Hong Kong from May to December 1997. Two of the six fatal cases had undergone a full post-mortem which showed reactive hemophagocytic syndrome as the most prominent feature. Other findings included organizing diffuse alveolar damage with interstitial fibrosis, extensive hepatic central lobular necrosis, acute renal tubular necrosis and lymphoid depletion. Elevation of soluble interleukin-2 receptor, interleukin-6 and interferon-gamma was demonstrated in both patients, whereas secondary bacterial pneumonia was not observed. Virus detection using isolation, reverse transcription-polymerase chain reaction and immunostaining were all negative. It is postulated that in fatal human infections with this avian subtype, initial virus replication in the respiratory tract triggers hypercytokinemia complicated by the reactive hemophagocytic syndrome. These findings suggest that the pathogenesis of influenza A H5N1 infection might be different from that of the usual human subtypes H1-H3.

Adolescent↗

PubMed2001

A comparison of cytokine responses in respiratory syncytial virus and influenza A infections in infants.

UNLABELLED: Respiratory syncytial virus (RSV) infection is a major cause of bronchiolitis in infants while influenza A infection usually manifests as upper respiratory tract infection. We hypothesised that the immunological responses of infants to RSV infection and influenza A infection are different. This prospective study was undertaken to compare the cytokine responses during RSV and influenza A infection. Sera and nasopharyngeal aspirates (NPA) were collected from infants with a coryzal illness with or without wheeze who were admitted to the paediatric wards during 1998. Cytokines, adhesion molecules, RANTES, IgE and eosinophil cationic protein (ECP) were measured by enzyme linked immunosorbent assay or fluorescence enzyme immunoassay. The diagnosis of RSV and influenza infections was based on direct immunofluorescence and viral culture. Of the 39 infants studied, RSV infection was confirmed in 11 patients and Influenza A in 10 patients. All RSV patients and one influenza A patient had wheeze during the infection. The serum concentrations of interleukin (IL)-4 and IL-5, regulated upon activation normal T cell expressed and secreted (RANTES) and soluble intercellular adhesion molecule 1 (sICAM-1) in infants with RSV infection were significantly higher than those with influenza A infection (all P < 0.02). The concentration of tumour necrosis factor-alpha (TNF-alpha) in NPA was significantly lower in infants with RSV infection (P < 0.01). CONCLUSION: A predominant T helper cell type 2 cytokine and related immunological response was observed in infants with respiratory syncytial virus infection whereas a predominant pro-inflammatory cytokine response was observed in infants with influenza A infection. This may explain the different clinical manifestations of the two viral infections in infants.

Cell Adhesion Molecules↗

PubMed2001

Head-up tilt test without intravascular cannulation in children and adolescents.

Previous studies of head-up tilt test have shown that testing at high degrees lacks specificity in children. We suspected that the high false positive rate might be related to the intravascular catheter and other maneuvers incorporated in the test and therefore studied the sensitivity and specificity of standing and HUT at 80 degrees without any invasive procedure and other maneuvers in children and adolescents. Twenty three patients (11.8+/-2.7 years) with recurrent typical neurally mediated syncope and 35 normal control children (11.6+/-3.0 years) underwent motionless standing for 15 min and tilting to 80 degrees for 30 min. Continuous finger arterial pressure monitoring and ECG were performed during the test. Eight (35%) of the 23 patients developed symptoms of near syncope during motionless standing. Thirteen (57%) of them had positive results at 80 degrees tilting for 30 min. The symptoms of syncope were not always corresponding to excessive haemodynamic changes. None of the controls developed any symptoms or excessive hemodynamic changes. Without intravascular instrumentation and other autonomic maneuvers, active motionless standing or HUT at 80 degrees for 30 min is highly specific but of limited sensitivity for the investigation of vasovagal syncope.

Adolescent↗

PubMed2001

Growth and nutrition of Chinese vegetarian children in Hong Kong.

OBJECTIVE: The study investigated the nutritional status of Chinese lacto-ovo-vegetarian children aged 4-14 years. METHODOLOGY: Dietary intake over 7 days was assessed using a computer program, previously used for a local population-based dietary survey. Anthropometric measurements were made and fasting venous blood was examined for serum lipids, haematological data, iron, vitamin B12 and folate status. Bone mineral density (BMD) of the spine (L2 - L4) was measured as a reflection of calcium status. RESULTS: Fifty-one lacto-ovo-vegetarians aged 4-14 years were investigated. The mean +/- standard deviation (SD) daily energy intake was 1600 +/- 425 kcal. The mean (+/- SD) daily protein intake was 1.6 +/- 0.6 g/kg bodyweight which met the United States recommended dietary allowance. Compared to that of the local omnivore diet, the vegetarian diet was closer to the recommended healthy diet with lower fat (20-23%), more fibre (5.8-8.7 g/day) and better polyunsaturated to saturated fatty acid ratio (1.0-1.1). Growth and BMD of the vegetarian children were comparable to the general omnivore population. Two children had iron deficiency and two children had anaemia. The calcium status, as reflected by the BMD, was not impaired. Serum folate and vitamin B12 were within the normal range. Six (25%) boys and four (15%) girls were obese. Three boys had hyperlipidaemia. CONCLUSIONS: A Hong Kong Chinese vegetarian diet appears healthy, providing adequate iron and vitamin B12 nutrition, but the prevalence of obesity was high.

Adolescent↗

PubMed2001

Measurement of body fat using leg to leg bioimpedance.

AIMS: (1) To validate a leg to leg bioimpedance analysis (BIA) device in the measurement of body composition in children by assessment of its agreement with dual energy x ray absorptiometry (DXA) and its repeatability. (2) To establish a reference range of percentage body fat in Hong Kong Chinese children. METHODS: Sequential BIA and DXA methods were used to determine body composition in 49 children aged 7-18 years; agreement between the two methods was calculated. Repeatability for the BIA method was established from duplicate measurements. Body composition was then determined by BIA in 1139 girls and 1243 boys aged 7-16 years, who were randomly sampled in eight local primary and secondary schools to establish reference ranges. RESULTS: The 95% limits of agreement between BIA and DXA methods were considered acceptable (-3.3 kg to -0.5 kg fat mass and -3.9 to 0.6% body fat). The percentage body fat increased with increasing age. Compared to the 1993 Hong Kong growth survey, these children had higher body mass index. Mean (SD) percentage body fat at 7 years of age was 17.2% (4.4%) and 14.0% (3.4%) respectively for boys and girls, which increased to 19.3% (4.8%) and 27.8% (6.3%) at age 16. CONCLUSION: Leg to leg BIA is a valid alternative method to DXA for the measurement of body fat. Provisional reference ranges for percentage body fat for Hong Kong Chinese children aged 7-16 years are provided.

Absorptiometry, Photon↗

PubMed2000

Cerebral blood flow during vasovagal syncope induced by active standing or head up tilt.

BACKGROUND: Vasovagal syncope is usually associated with a sudden drop of blood pressure and/or heart rate. However, occasionally the symptoms of syncope induced by orthostatic stress testing are not associated with obvious haemodynamic changes. The mechanisms of syncope in these patients are not clear. AIM: To evaluate changes in cerebral blood flow velocities during orthostatic stress testing in children and adolescents with vasovagal syncope. METHODS: Electrocardiogram, instantaneous arterial blood pressure, and right middle cerebral artery blood flow velocity were recorded at rest, during active standing, and 80 degrees head up tilt. 32 children and adolescents aged between 7 and 18 years with a history of repeated vasovagal syncope and 23 healthy control subjects were studied. RESULTS: Presyncope occurred in 10 patients during standing, and 13 patients during head up tilt. None of the controls had symptoms during the test. The transcranial Doppler study showed that the symptoms were associated with significant decreases of diastolic cerebral blood flow velocity and an increase of pulsatility. There was no significant change of the systolic cerebral blood flow velocity. The changes of cerebral blood flow velocities occurred in all episodes of presyncope, including those not associated with severe drop of blood pressure or heart rate. CONCLUSIONS: Diastolic cerebral blood flow velocity decreased significantly during episodes of presyncope induced by orthostatic stress. Impairment of autoregulation of cerebral blood flow might play an important role in the pathophysiology of syncope.

Adolescent↗

PubMed1999

Epidemiology of respiratory syncytial virus infection among paediatric patients in Hong Kong: seasonality and disease impact.

In a 5-year retrospective survey of respiratory syncytial virus (RSV) infections among hospitalized children, 1340 cases were identified of which, 98.4% were children < 5 years old with a male:female ratio of 1.5: 1. Most cases occurred from April to September showing a significant positive correlation with temperature and relative humidity. Community-acquired infections accounted for 92.5% of the cases with a mean hospital stay of 5 days. The estimated annual incidence of RSV infection requiring hospitalization was 2.5/1000 children < 5 years old with a mortality of 0.15% among hospitalized cases. On average, 248 children were admitted each year to the 1400-bed acute regional hospital accounting for an expenditure of HK S1.94 ((approximately US +/-0.25) million for hospitalization costs which equates to an annual cost in excess of HK $6.67 (approximately US $0.86) million for the whole of Hong Kong. An RSV vaccine should be a priority.

Child, Preschool↗

PubMed1998

Effects of blood transfusion on left ventricular output in premature babies.

OBJECTIVE: To investigate the acute effects of red blood cell transfusion on haemodynamics in preterm babies. SETTING: A neonatal unit in a University Hospital. PATIENTS: Preterm babies whose postnatal age was less than four weeks and who required red blood cell transfusion. MEASUREMENT: Cardiac output and left ventricular systolic function was determined using Doppler echocardiography before, one hour and 24 h after red blood cell transfusion. Blood pressure and haematocrit were also recorded at the same time. Mixed-effects regression model was used to analyse the effect of blood transfusion on left ventricular function and cardiac output. RESULTS: 57 preterm babies were recruited. Univariate analysis showed that cardiac index decreased significantly 24 h after transfusion (P<0.05). Systemic red cell transport increased by an average of 11.1% 24 h after transfusion (P<0.05). Multivariate analysis showed that the cardiac index was negatively associated with haematocrit and the index was higher in male babies. CONCLUSION: There was a significant drop in cardiac index and an increase in systemic red cell transport 24 h after transfusion in premature babies.

Analysis of Variance↗

PubMed1997

Echocardiographic evaluation of cardiac function in paediatric oncology patients treated with or without anthracycline.

Using Doppler echocardiography, we studied the left ventricular systolic and diastolic function in 124 healthy control children (group C), 110 oncology patients who had received anthracycline (group A), and 76 oncology patients who had received chemotherapy not including anthracycline (group N), at rest and after supine bicycle exercise. The mean dosage of anthracycline that group A patients received was 219 +/- 95 mg/m2. Impaired systolic function was detected in 29% of the patients in group A and 4% in group N. Figures for impaired diastolic function for group A and N were 27% and 28% respectively. Abnormal diastolic function was detected more frequently in the first two years after chemotherapy in both groups. Four parameters measured at rest appeared to be specifically abnormal in group A but not in group N. These were ejection fraction, fractional shortening, rate-corrected velocity of circumferential fiber shortening (VCFC) and left ventricle peak systolic wall stress (LVWS). After exercise more parameters were abnormal in group N patients when compared to normal children, but abnormalities of VCFC and LVWS remained specific for group A. In conclusion, abnormalities of diastolic function were common among paediatric oncology patients no matter whether they had received anthracycline treatment or not. Abnormalities of systolic function were more specific to anthracycline toxicity. VCFC and LVWS were the most sensitive measurements for differentiating group N patients from group A patients.

Adolescent↗

PubMed1997

Meningitis in Hong Kong children, with special reference to the infrequency of haemophilus and meningococcal infection.

OBJECTIVE: To study the epidemiologic and aetiologic features of meningitis in children in Hong Kong. METHODOLOGY: A retrospective study of 85 children resident in the New Territory East region of Hong Kong admitted to a teaching Hospital because of meningitis during a 9 year period. RESULTS: Mycobacterium tuberculosis was the most common aetiological agent accounting for 13 cases (15.3%). Other bacteria accounted for 41 cases (48%); among these one fifth were caused by Haemophilus influenzae type b. The overall admission rates for tuberculous meningitis in Chinese children were 0.76/100,000 (95% CI 0.25-1.78) and 0.42/100,000 (CI 0.19-0.8) per year, respectively, for under 5 year olds and under 15 year olds. The overall annual incidence rates of bacterial meningitis other than tuberculous were 5.2/100,000 (CI 3.72-7.43) and 1.6/100,000 (CI 1.14-2.29) for Chinese children under 5 years and under 15 years, respectively. The annual incidence of H. influenzae meningitis in Chinese children under 5 years old was low at 1.1/100,000 (0.43-2.2). All five cases of meningococcal meningitis were in Vietnamese children (under 5 years of age incidence: 13.0/100,000 per year, CI 4.2-30.3). There were no cases of meningococcal meningitis in Chinese children during the 9 year period. CONCLUSION: M. tuberculosis was the most common aetiological agent of meningitis in Hong Kong children. The incidence of haemophilus or meningococcal meningitis was very low.

Adolescent↗

PubMed1996

Urinary D-glucaric acid excretion in idiopathic neonatal jaundice.

OBJECTIVE: To determine the extent to which immaturity of hepatic microsomal enzyme activity might contribute to physiological jaundice. METHODS: Urinary excretion of D-glucaric acid, expressed in mumol glucaric acid/ mmol creatinine, was measured in 122 Chinese full-term healthy newborn babies during the first five days of life. Among the 122 babies, 22 were born by normal spontaneous delivery at the British Military Hospital and 100 were born by caesarean section at the Prince of Wales Hospital. RESULTS: In all babies the excretion of D-glucaric acid was highest on the first day of life and gradually decreased over the following 5 days. Five babies born by spontaneous delivery and six babies born by caesarean section developed jaundice during the study period. The excretion of D-glucaric acid in the jaundiced babies was significantly higher on the first two days than in the non-jaundiced babies. CONCLUSIONS: D-glucaric acid excretion was increased in jaundiced newborn babies in the first few days of life. This finding does not indicate less liver microsomal enzyme activity in the jaundiced babies compared to those non-jaundiced. On the contrary, it suggests that in idiopathic neonatal jaundice compensatory mechanism might operate from a very early stage to excrete a higher bilirubin load that might be present through haemolysis.

Creatinine↗

PubMed1995

Carriage of Haemophilus influenzae and Streptococcus pneumoniae in healthy Chinese and Vietnamese children in Hong Kong.

Nasopharyngeal carriage of Haemophilus influenzae and Streptococcus pneumoniae was studied in 621 healthy Chinese children and 300 healthy Vietnamese children aged from 2 months to 5 years in Hong Kong. The carriage rate of H. influenzae type b in Vietnamese children was 1.3% (CI 0.04-2.63); it was zero in Chinese. The carriage rate of non-typable H. influenzae was 5.8% (CI 1.4-7.6%) in Chinese and 65.4% (CI 58.9-69.8%) in Vietnamese. The carriage rates of S. pneumoniae were 10.8% (CI 8.3-13.2%) and 55.7% (CI 50.1-61.3%) in Chinese and Vietnamese children, respectively. Univariate and multivariate logistic regression analyses were performed to search for factors associated with differences in carriage rates of both H. influenzae and S. pneumoniae between Chinese and Vetnamese children. Although older age, smaller living area and parental smoking were associated with higher carriage rates, these could not explain the remarkably low carriage rates of both bacteria in Chinese children.

Adolescent↗

PubMed1993

Cardiovascular effects of i.v. induction in children: comparison between propofol and thiopentone.

We have compared the haemodynamic responses to i.v. propofol 2.5 mg kg-1 with those to thiopentone 5.0 mg kg-1 in 41 healthy Chinese children at induction of anaesthesia. They were allocated to four groups according to their age and induction agent received: group 1 < 2 yr, propofol, n = 9; group II < 2 yr, thiopentone, n = 9; group III 2-12 yr, propofol, n = 12; group IV 2-12 yr, thiopentone, n = 11. Anaesthesia was maintained by spontaneous ventilation with 70% nitrous oxide and 0.5% halothane in oxygen. Arterial pressure and heart rate were monitored by automatic oscillotonometer. Stroke volume was measured by two-dimensional echocardiography and pulse Doppler. Measurements were made before induction and at 1-min intervals for 5 min after induction. The reduction in mean arterial pressure was significantly greater after propofol (28-31%) than after thiopentone (14-21%) (P = 0.001). The reduction in cardiac index (10-15%) after induction was not significantly different between the two agents (P = 0.122). Baroreflex mediated increases in heart rate and systemic vascular resistance were less after propofol than after thiopentone. The baroreceptor reflex was more attenuated in children aged less than 2 yr than in older children.

Anesthesia, Inhalation↗

PubMed1993

Epidemiology and etiology of pneumonia in children in Hong Kong.

The epidemiologic and etiologic features of cases of pneumonia among 1,740 children admitted to a teaching hospital in Hong Kong over a 3-year period were studied. Of the patients, 23% were < 1 year old and 69% were < 5 years old. The incidence of pneumonia requiring admission to the hospital was 6.4 episodes per 1,000 children per year for those < 5 years of age. The overall case fatality rate was 0.15% among patients who did not have severe underlying disease before contracting pneumonia. A bacterial etiology was confirmed by blood culture for only 2% of patients. However, culture of sputum or nasopharyngeal aspirates yielded predominant or pure growth of one bacterial agent in 17% of cases. Haemophilus influenzae was the bacterial agent most frequently isolated from nasopharyngeal aspirates or sputum, followed by Streptococcus pneumoniae and Staphylococcus aureus. Of the H. influenzae isolates, 38% were resistant to ampicillin. A viral etiology was proven in 9.1% of cases, and evidence of mycoplasmal infection was found in 3.8% of cases. Respiratory syncytial virus was the most frequently identified viral agent, followed by adenovirus and influenza A virus.

Adolescent↗

PubMed1993

Treatment of respiratory syncytial virus infection with recombinant interferon alfa-2a.

A prospective randomised, double blind, controlled trial was conducted in 52 infants to determine whether recombinant interferon alfa-2a (INF-alpha-2a) would reduce the morbidity of acute bronchiolitis and the respiratory syncytial virus shedding time. All infants had a positive direct antigen immunofluorescence test for respiratory syncytial virus. INF-alpha-2a (50,000 IU/kg/day) or placebo was administered by daily intramuscular injection for three consecutive days. Sixteen infants received INF-alpha-2a and 36 received placebo treatment. The two groups were similar in demographic characteristics and initial oxygenation. The treatment group, however, had a significantly higher overall score for severity of illness at the start of treatment. More rapid drop of the clinical score was observed in the INF-alpha-2a group after treatment in the first three days and the two groups had similar clinical severity by day 3. There was no significant difference of the duration of viral shedding in the two groups. In conclusion, the overall clinical improvement was greater in the treatment group over the first three days, but the duration of viral shedding was not altered.

Double-Blind Method↗

PubMed1992

Epidemiology and aetiology of acute bronchiolitis in Hong Kong infants.

The epidemiological, clinical and virological features of 1220 children with acute bronchiolitis admitted to the Prince of Wales Hospital, Hong Kong, from 1985 to 1988 are reported. They accounted for 6.6% of total paediatric admissions and provided a case incidence of bronchiolitis requiring admission to hospital of approximately 21 per 1000 children 0-24 months of age. The clinical course and outcome was in general benign. The average hospital stay was 5 days and there were no deaths. Ten per cent of patients were repeatedly admitted to hospital with recurrent wheezing after discharge. Two infants developed bronchiolitis obliterans. Respiratory syncytial virus (RSV) was shown by direct immunofluorescence, virus culture and serology to be the commonest cause of acute bronchiolitis in Hong Kong. Other aetiological agents included parainfluenza and influenza viruses, adenoviruses, and Mycoplasma pneumoniae. In contrast to western countries, a seasonal variation of bronchiolitis was found with a peak incidence in the summer months. The significance of these observations is discussed.

Acute Disease↗

PubMed1992

Preterm infants with patent ductus arteriosus: treatment with an enteral preparation of indomethacin.

Forty-one preterm infants with a mean gestational age and birthweight of 29.7 weeks and 1322 g, respectively, were treated with an enteral preparation of indomethacin for the closure of haemodynamically significant patent ductus arteriosus. The indomethacin was prepared by diluting the content of the commercially available 25-mg indomethacin capsule with lactose by the method of trituration. The mixture was suspended in solution form just prior to administration to the infants. The ductus arteriosus was successfully closed in 29 infants, giving an overall success rate of 71%. The response to treatment was considered satisfactory, except for infants whose birthweights were less than 750 g. Only two infants (5%) developed major complications, both in the form of ileal perforation. As the outcome of treatment with this enteral preparation of indomethacin was comparable with that of the intravenous preparation reported in previous studies, it would be an acceptable alternative to the intravenous preparation in areas where the latter is not available or considered expensive.

Administration, Oral↗

PubMed1991

Echocardiography as a tool for determining the incidence of congenital heart disease in newborn babies: a pilot study in Hong Kong.

We studied, with echocardiography as the main tool, the incidence of congenital heart disease in newborn babies in Hong Kong. The population examined was the 20,928 babies who were born alive in the Prince of Wales Hospital from January 1987 to December 1989. All had a thorough physical examination by a paediatrician after birth, and an estimated 95% of the babies who were discharged from hospital received another routine physical examination at one of the five local Maternal and Child Health Centres within two months of birth. All babies with either suspected congenital heart disease or multiple congenital abnormalities were referred to the paediatric cardiologists in the Prince of Wales Hospital for further cardiovascular assessment that included echocardiographic examination. In all, 492 babies had Doppler and cross-sectional echocardiographic studies. Various abnormalities of the cardiovascular system were diagnosed in 216 babies. Almost all the babies who died within two months of life underwent autopsy. This proved the presence of congenital cardiac malformations in 15 babies, of whom 10 had correct echocardiographic diagnoses during life. One had a patent arterial duct which was missed by the echocardiography. The other four babies did not have echocardiographic examination while alive, either because of early death or absence of clinical suspicion. In total, congenital cardiac malformations were confirmed in 221 babies by echocardiographic examination and autopsy. Excluding 82 premature babies with patency of the arterial duct, and 6 babies with transient tricuspid regurgitation, there were 133 cases of structural cardiac malformation in the studied population, giving an incidence of 6.35 per thousand live births.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗