Biomedical subjects

T F Fok

Publications and source records attributed to T F Fok.

At least 19 recordsLinked to original sources

PubMed2006

Waist circumference and body mass index in Chinese children: cutoff values for predicting cardiovascular risk factors.

BACKGROUND: Body mass index (BMI) and waist circumference (WC) correlate with cardiovascular (CV) risk factors in childhood which track into adulthood. WC provides a measure of central obesity, which has been specifically associated with CV risk factors. Reference standards for WC, and for WC and BMI risk threshold values are not established in Chinese children. OBJECTIVES: To construct reference percentile charts of WC, establish relationships between WC, BMI and other risk factors, and propose WC and BMI threshold values predictive of CV risk factors in Hong Kong ethnic Chinese children. METHODS: Weight, height, waist and hip circumference were measured in 2593 (52% boys, 47% girls) randomly sampled Hong Kong school children aged 6-12 years. In 958 of these and 97 additional overweight children (n=1055), the relationships between WC, BMI, waist/hip and waist/height ratio and six age-adjusted CV risk factors (>85% percentile levels of blood pressure (BP), fasting triglycerides, low-density lipoprotein (LDL) cholesterol, glucose and insulin levels, and <15% percentile levels of high-density lipoprotein (HDL) cholesterol) were studied. Receiver-operating characteristic analysis was employed to derive optimal age-adjusted sex-specific WC and BMI thresholds for predicting these measures of risk. RESULTS: WC percentiles were constructed. WC correlated slightly more than BMI with CV risk factors and most strongly with insulin and systolic BP, but poorly or not with LDL and glucose. Optimal WC and BMI risk thresholds for predicting four of these six CV risk factors were ca. the 85th percentiles (sensitivities approximately 0.8, specificities approximately 0.87) with age-specific cutoff values in girls/boys from approximately 57/58 to approximately 71/76 cm and 17/18 to 22/23 kg/m(2). CONCLUSION: These are the first set of WC reference data for Chinese children. WC risk cutoff values are proposed which, despite a smaller waist in Chinese children, are similar to those reported for American children. WC percentiles may reflect population risk.

Adolescent↗

PubMed2006

Induced sputum inflammatory measures correlate with disease severity in children with obstructive sleep apnoea.

OBJECTIVE: To establish the association between airway inflammation and severity of obstructive sleep apnoea (OSA) in children. METHODS: Consecutive children presenting with symptoms suggestive of OSA were recruited. They completed a sleep apnoea symptom questionnaire, underwent physical examination, spirometry, sputum induction and an overnight polysomnography. Adequate sputum contained <50% squamous epithelial cells, and OSA was diagnosed if the obstructive apnoea index was >1. RESULTS: 73 children with a median (interquartile range (IQR)) age of 11.3 (10.0-13.2) years were recruited. There were 21 girls and the median body mass index of the group was 24.0 (18.0-27.0) kg/m2. The most common presenting symptoms were habitual snoring, mouth breathing and prone sleeping position. Sputum induction was successful in 43 (59%) children, of whom 14 were found to have OSA. Children with OSA had significantly greater percentage sputum neutrophil than those without OSA (18.5 (IQR 8.0-42.0) v 4 (IQR 3.0-11.3), p = 0.006). On multiple regression analysis, percentage sputum neutrophil was significantly associated with OSA (odds ratio = 1.1, p = 0.013). CONCLUSION: Children with OSA had airway inflammation characterised by a marked increase in neutrophils. Further studies are needed to confirm these findings and to better define the downstream cellular interactions and molecular pathogenesis in childhood OSA.

Adolescent↗

PubMed2006

Cough frequency in children with mild asthma correlates with sputum neutrophil count.

BACKGROUND: A study was undertaken to measure cough frequency in children with stable asthma using a validated monitoring device, and to assess the correlation between cough frequency and the degree and type of airway inflammation. METHODS: Thirty six children of median age 11.5 years (interquartile range (IQR) 9-14) with stable asthma were recruited. They underwent spirometric testing, exhaled nitric oxide (eNO) measurement, sputum induction for differential cell count, and ambulatory cough monitoring for 24 hours. Coughing episodes were counted both as individual spikes and as clusters. RESULTS: All children had mild intermittent asthma and their median forced expiratory volume in 1 second and eNO were 83.3% (IQR 81.1-97.6) and 56.1 ppb (IQR 37.4-105), respectively. The median number of cough episodes per day was 25.5 (IQR 16-42.8). Sputum induction was successful in 69% of the subjects and cough frequency was found to have a significant positive correlation with sputum neutrophil count (r = 0.833, p = 0.0001). CONCLUSIONS: Children with stable mild asthma have increased cough frequency that might be driven by a neutrophilic inflammatory pathway.

Asthma↗

PubMed2006

Longer term follow up of aerobic capacity in children affected by severe acute respiratory syndrome (SARS).

BACKGROUND: A study was undertaken to investigate the aerobic capacity and pulmonary function of children 6 and 15 months after the diagnosis of severe acute respiratory syndrome (SARS). METHODS: Thirty four patients of mean age 14.7 years completed both pulmonary function and maximal aerobic capacity tests at 6 months. All had normal clinical examination and were asymptomatic. Their exercise responses were compared with a group of healthy controls. Complete data were collected on 27 of the original 34 cases at 15 months. RESULTS: Compared with normal controls, the patient group had significantly lower absolute and mass related peak oxygen consumption (peak V o(2) (p<0.01)), higher ventilatory equivalent for oxygen (p<0.01), lower oxygen pulse (p<0.01), and a lower oxygen uptake efficiency slope (p<0.01) at 6 months. This impairment was unexpected and out of proportion with the degree of lung function abnormality. Residual high resolution computed tomography of thorax (HRCT) abnormalities were present in 14 patients. Those with abnormal HRCT findings had significantly lower mass related peak V o(2) than subjects with normal radiology (p<0.01). Absolute and mass related peak V o(2) in the patient group remained impaired at 15 months despite normalisation of lung function in all patients. CONCLUSIONS: The mechanism for the reduced aerobic capacity in children following SARS is not fully understood, but it is probably a consequence of impaired perfusion to the lungs at peak exercise and deconditioning.

Adolescent↗

PubMed2006

Exhaled nitric oxide levels are not correlated with eczema severity in Chinese children with atopic dermatitis.

Asthma is a common atopic disease associated with atopic dermatitis (AD) and allergic rhinitis (AR). Exhaled nitric oxide level (eNO) has been found to be an interesting noninvasive marker of disease severity in children with asthma. However, it is uncertain if eNO may be confounded by any coexisting AD or AR. In this study, eNO in Chinese children with moderate-to-severe AD and no asthma symptoms (n = 53) was measured online by a chemiluminescence analyzer. Severity of AD was assessed using the objective SCORing-Atopic-Dermatitis score and coexisting allergic rhinitis with the Allergic-Rhinitis-Score (ARS). Patients with active symptoms of asthma or inhaled/intranasal corticosteroids were excluded. There was no difference in eNO between genders and no correlation between eNO and AD severity regardless of ARS or bronchial reactivity status. ENO appears to be a noninvasive marker whose level is independent of the two atopic diseases of AD and AR in children old enough to perform exhalation maneuver.

Adolescent↗

PubMed2006

Dietary restriction and supplementation in children with atopic eczema.

Issues on empirical dietary restriction or supplementation are important but inadequately studied in children with atopic eczema (AE). The dietary habits of children with AE followed at a paediatric dermatology clinic (n = 179) were compared with those without eczema (n = 78). The mothers of 53% of the patients with or without eczema did not breastfeed their children. Common food items avoided by parents whose children have moderate-to-severe AE included fish or seafood [64% vs. 32% of controls, odds ratio (OR) 3.84, 95% CI 2.12-6.95], beef (42% vs. 17%; OR = 3.57, 95% CI 1.79-7.11), eggs (34% vs. 14%; OR = 3.05, 95% CI 1.46-6.34) and cows' milk (18% vs. 4%; OR = 5.56, 95% CI 1.61-19.12); whereas their avoidance was less frequent in children with noneczematous diseases. The avoidance of these foods were often based on belief, but 66% of all AE patients who had avoided any of the above foods reported previous experience of eczema exacerbation by these items. Patients with moderate-to-severe AE were more likely to have consumed 'bird's nest' soup and traditional Chinese medicines. It is important to evaluate whether the AE patients are genuinely 'allergic' to some of these food items. Management is suboptimal if children with food allergy and severe disease continue to consume the culprit food. Conversely, avoidance of common foods in children without food allergy could result in food faddism or malnutrition.

Adolescent↗

PubMed2006

Lesson from performing SCORADs in children with atopic dermatitis: subjective symptoms do not correlate well with disease extent or intensity.

BACKGROUND: Atopic dermatitis (AD) is a distressing disease associated with pruritus and sleep disturbance. It is not known how well these symptoms correlate with the extent and intensity of eczematous involvement. We evaluated whether: (i) the level of sleep loss correlates with pruritus and (ii) the level of pruritus correlates with the extent or severity of AD in children according to the SCORing Atopic Dermatitis (SCORAD) index. METHOD: Patients with AD younger than 18 years old were recruited from the pediatric dermatology clinic of a university teaching hospital, and AD severity was evaluated by the SCORAD index. RESULTS: One hundred and eighty-two Chinese children with AD (107 boys and 75 girls) [mean (SD) age of 9.6 (4.2) years] were recruited. Their mean (SD) overall SCORAD was 30.1 (19.2). Sleep loss was strongly correlated with pruritus (r = 0.57, P < 0.001). However, the two subjective symptoms were only weakly correlated with the objective signs (extent and intensity) of AD. The correlations between pruritus and extent and intensity were 0.42 (P < 0.001) and 0.38 (P < 0.001), respectively, and the correlations between sleep loss and extent and intensity were 0.38 (P < 0.001) and 0.34 (P < 0.001), respectively. CONCLUSION: We speculate that the lack of a better correlation was either because pruritus and sleep loss as reported by parents were imprecise, or that mechanisms other than disease extent or severity are responsible for the pathogenesis of these subjective symptoms.

Adolescent↗

PubMed2005

Limbs anthropometry of singleton Chinese newborns of 28-42 weeks' gestation.

Abnormalities of limbs are important features of some syndromes recognizable at birth. The purpose of this study was to establish normal standards of limbs including arm length, arm circumference, upper arm length, lower arm length, leg length, thigh circumference, upper leg length, and lower leg length. 10,226 infants (5,422 males, 4,804 females) with gestation 28-42 weeks from 12 hospitals were included. The LMS method using maximum penalized likelihood was used to perform model fitting of the anthropometric centiles for these parameters. This study provided the first set of references for the limbs of the infants by gestation and gender. Racial differences were found when comparing with other populations. The parameters are useful for evaluation of morphologic disorders involving the limbs.

Americas↗

PubMed2005

Clinical and atopic parameters and airway inflammatory markers in childhood asthma: a factor analysis.

BACKGROUND: Recent studies have repeatedly shown weak correlations among lung function parameters, atopy, exhaled nitric oxide level (Feno), and airway inflammatory markers, suggesting that they are non-overlapping characteristics of asthma in adults. A study was undertaken to determine, using factor analysis, whether the above features represent separate dimensions of childhood asthma. METHODS: Clinically stable asthmatic patients aged 7-18 years underwent spirometric testing, methacholine bronchial challenge, blood sampling for atopy markers and chemokine levels (macrophage derived chemokine (MDC), thymus and activation regulated chemokine (TARC), and eotaxin), Feno, and chemokines (MDC and eotaxin) and leukotriene B(4) measurements in exhaled breath condensate (EBC). RESULTS: The mean (SD) forced expiratory volume in 1 second (FEV1) and Feno of 92 patients were 92.1 (15.9)% predicted and 87.3 (65.7) ppb, respectively. 59% of patients received inhaled corticosteroids. Factor analysis selected four different factors, explaining 55.5% of total variance. The Kaiser-Meyer-Olkin measure of sampling adequacy was 0.587. Plasma total and specific IgE levels, peripheral blood eosinophil percentage, and Feno loaded on factor 1; plasma TARC and MDC concentrations on factor 2; MDC, eotaxin and leukotriene B4 concentrations in EBC on factor 3; and plasma eotaxin concentration together with clinical indices including body mass index and disease severity score loaded on factor 4. Post hoc factor analyses revealed similar results when outliers were excluded. CONCLUSIONS: The results suggest that atopy related indices and airway inflammation are separate dimensions in the assessment of childhood asthma, and inflammatory markers in peripheral blood and EBC are non-overlapping factors of asthma.

Administration, Inhalation↗

PubMed2005

Mal-positioned umbilical venous catheter causing liver abscess in a preterm infant.

Neonatal liver abscess is uncommon, carries a high mortality and is difficult to diagnose. We report an unusual case of liver abscess in a preterm infant presenting with abdominal distension and suspected gastrointestinal perforation, rather than the more usual features of fever, hepatomegaly, abdominal tenderness, right-sided pleural effusion, and leukocytosis. We discuss current treatments for neonatal liver abscess and argue that in view of the high mortality and difficulty in diagnosis, prevention should be the primary objective. We believe that mal-positioning the umbilical venous catheter in the liver substantially increases the life-threatening risk of this complication, and advocate extreme care in the placement and use of these catheters.

Catheterization, Peripheral↗

PubMed2005

Fetal growth velocities in Hong Kong Chinese infants.

Few studies have investigated the velocities of fetal growth. The aim of the present study was to determine the pattern of 'fetal' growth velocities in a Chinese population. The gestation-specific measurements of the body weight, body length and head circumference in a representative sample of 5,045 male and 4,484 female newborns delivered between 26 and 42 weeks of gestation at 12 hospitals in Hong Kong were obtained. Peak growth velocity occurred before 30 weeks of gestation for head circumference, at week 30 for length and at week 30 for weight. When compared with data obtained from a French population, a significant difference in the growth velocity for body weight was observed below 32 weeks between French and Chinese infants, suggesting an ethnic difference in fetal growth of this parameter.

Anthropometry↗

PubMed2005

Normative data of penile length for term Chinese newborns.

Careful examination and assessment of penile length in the newborn is important because micropenis is associated with hypothalamic disorders. This prospective cross-sectional study was designed to establish the norm of penile length for term Hong Kong Chinese newborns. 4,628 full-term healthy male newborns were enrolled in the study. Penile length was measured from pubic ramus to the tip of the glans penis by placing the end of a straight edge ruler against the pubic ramus. A gestation-associated graph of 3rd, 10th, 25th, 50th, 75th, 90th and 97th centiles for the penile length was created. The penile length was significantly correlated with gestational age, birth weight and body length. When compared with published data for other populations, Hong Kong newborns have significantly shorter penile length. The norm of the penile length is useful in diagnostic and therapeutics for the ethnic Chinese male newborns.

Asian People↗

PubMed2005

Trunk anthropometry of Hong Kong Chinese infants.

BACKGROUND: Disturbed growth of the trunk may result in abnormal sternocostal relationship and a variety of pectus deformities. AIMS: The purposes of this study were to establish norms of trunk anthropometry for dysmorphology identification in the newborns and to evaluate chest circumference as a predictor for low birth weight for outborn infants where weighing scales were unavailable. STUDY DESIGN AND SUBJECTS: A total of 10,339 Chinese infants (5478 males, 4861 females) with gestation 24-42 weeks from 12 hospitals were included. The anthropometric measurements analyzed included chest circumference, inter-nipple distance, sternal length and abdominal circumference. OUTCOME MEASURES: The LMS method using maximum penalized likelihood was used to perform model fitting of the anthropometric centiles for these physical parameters. RESULTS: References tables of the four physical parameters for newborns were constructed. Chest circumference showed the highest correlation with birth weight (male: r = 0.866, female: r = 0.883). The cut-off points for chest circumference of 295 (male) and 299 mm (female) were the best predictor for low birth weight. There were also racial differences in these parameters. When compared with French infants, Chinese newborns had smaller chest circumference. CONCLUSION: These physical parameters provide useful references and aid dysmorphology diagnosis in newborns of ethnic Chinese origin.

Anthropometry↗

PubMed2005

Multipotent neural precursors express neural and hematopoietic factors, and enhance ex vivo expansion of cord blood CD34+ cells, colony forming units and NOD/SCID-repopulating cells in contact and noncontact cultures.

In view of the possible crosstalks between hematopoiesis and neuropoiesis, we evaluated two microenvironments, murine neonatal neural cell line C17.2 and primary embryonic aorta-gonad-mesonephros (AGM) stromal cells, on the ex vivo expansion of CD34+ cells from human cord blood. In a contact culture system, C17.2 or AGM cells significantly enhanced the expansion of CD34+ cells to a panel of early and committed hematopoietic progenitor cells. In a noncontact transwell system, pre-established C17.2 cells significantly increased the expansion of total nucleated cells, CD34+ cells and multilineage colony forming cells (P<0.01). Expanded cells were infused into nonobese diabetic/severe-combined immunodeficient mice. The engraftment of human (hu)CD45+ cells in the bone marrow of these mice was consistently higher in all the 10 experiments conducted with the support of C17.2 cells when compared with those in respective control groups (11.9 vs 2.43%, P=0.03). Using RT-PCR and Southern blot analysis, we showed that AGM and C17.2 cells expressed a panel of hematopoietic, bone morphogenetic and neurotrophic factors. Our data provided the first evidence on the promoting effects of a neural progenitor cell line on hematopoiesis at a noncontact condition. The mechanism could be mediated by the expression of multilineage regulatory factors.

Animals↗

PubMed2005

Resting energy expenditure, oxygen consumption and carbon dioxide production during sleep in children with atopic dermatitis.

BACKGROUND: Pruritus and scratching are cardinal symptoms of atopic dermatitis (AD). Sleep and growth may also be affected in children with moderate-to-severe AD. We evaluated whether resting energy expenditure (REE), oxygen consumption (VO2) and carbon dioxide production (VCO2) in various stages of sleep were influenced by the disease severity. METHODS: Disease severity was evaluated by the scoring atopic dermatitis (SCORAD) index. All-night polysomnography was performed and REE, VO2 and VCO2 were measured. RESULTS: Twenty children (13 boys and seven girls) with AD and eight controls were recruited. The median overall SCORAD for our AD patients was 36.8. The total sleep efficiency was lower in patients with severe AD than that obtained in the control group (median: 72% versus 88%; p = 0.039). When compared with mild-to-moderate disease (SCORAD40) and controls, REE, VO2 and VCO2 in patients with severe AD (SCORAD > 40) did not differ in sleep stages I and II combined, stages III and IV combined or the rapid eye movement (REM) stage. REE, VO2 and VCO2 in these sleep stages did not show significant correlation with the overall and the three components of the SCORAD scores. CONCLUSIONS: Children with AD do not appear to have significant disturbance in their resting energy consumption, oxygen consumption and carbon dioxide production during sleep. These parameters do not appear to correlate with the symptomatology of pruritus and sleep disturbance. We speculate that deranged metabolism during sleep is unlikely in children with AD.

Adolescent↗

PubMed2005

Brief case series: montelukast, at doses recommended for asthma treatment, reduces disease severity and increases soluble CD14 in children with atopic dermatitis.

BACKGROUND: The choice of oral therapeutic agents for the treatment of atopic dermatitis (AD) in children is limited. Montelukast, a specific cysteinyl leukotriene (LT) receptor antagonist, may be useful in alleviating AD symptoms. OBJECTIVE: To evaluate the clinical and immunological effects of montelukast in children with AD. METHODS: After a 2-week run-in, children with AD were started on oral montelukast 5 mg once-daily for children < 12 years of age and 10 mg for older children. The clinical severity of AD as indicated by the SCORing Atopic Dermatitis (SCORAD) score, and serum soluble CD14 and urinary leukotriene E4 (LTE4) concentrations were evaluated at baseline and the end of a 3-month treatment period. RESULTS: Four boys and three girls, with a median (range) age of 12 (3-16) years, participated in the study. The total SCORAD was reduced in five patients (by 30-84%) and remained similar in two patients. Their median (range) SCORAD scores before and after treatment were 34.7 (16.5-54.8) and 17.0 (6.9-36.9) (p = 0.046). The intensity component of SCORAD also decreased from 5 (2-10) to 3 (1-7) (p = 0.042). Serum sCD14 levels increased significantly from 5533 (4575-6452) ng/ml to 6259 (5617-8988) ng/ml (p = 0.028), whereas urinary LTE4 levels remained the same (p = 0.735). CONCLUSIONS: Montelukast, at doses recommended for asthma treatment, resulted in over 30% reduction in the total SCORAD in some children. Treatment with montelukast may also be associated with deviation of the immune system towards the Th1-specific pathway.

Acetates↗

PubMed2005

Reasons for new referral non-attendance at a pediatric dermatology center: a telephone survey.

BACKGROUND: Non-attendance at pediatric dermatology outpatient clinics is a significant problem. AIM: To determine the reasons and predictors for non-attendance. METHODS: New referral non-attenders to the pediatric dermatology clinic of a university teaching hospital were contacted by telephone and reasons for non-attendance enquired about. RESULTS: Sixty-three patients (20%) did not attend the first appointment over a 15-month study period. The mean+/-SD waiting time between attenders and non-attenders was 99+/-46 days and 113+/-41 days (p=0.029). A total of 49% of attenders and 60% of non-attenders were males. Telephone contact of non-attenders who did not schedule any re-appointment spontaneously (n=54), found that the mother was the informant in 85% of cases. Approximately 80% of informants gave one reason for non-attendance; approximately 20% gave two or more reasons. The most common reasons for non-attendance were 'skin condition already improved' (46%) and 'forgot appointment' (25%). 'Long waiting time' did not appear to be a common reason for non-attendance. There was no significant association between age of patient, urgency of booking and non-attendance. CONCLUSIONS: We confirm that there is a significant non-attendance rate in pediatric dermatology new referrals. Many of the skin conditions reportedly resolve spontaneously. As there is no identifiable predictor for non-attendance apart from a longer waiting time, any maneuvers or interventions to improve attendance rate are unlikely to be significantly fruitful.

Adult↗

PubMed2005

High levels and gender difference of exhaled nitric oxide in Chinese schoolchildren.

BACKGROUND: Exhaled nitric oxide (eNO) may represent a useful noninvasive marker of airway inflammation, but data on the reference population values in schoolchildren are limited. No reference eNO study in Asian children has been published. METHODS: Levels of eNO in a sample of 531 schoolchildren aged 11-18 years recruited from five schools (three international schools) in Hong Kong were measured online by a chemiluminescence analyser according to ERS/ATS standard. Each student also completed an International Study of Asthma and Allergic disease in Childhood questionnaire. RESULTS: Among the children without a physician's diagnosis of asthma or symptoms of wheeze, rhinitis and eczema, there were 258 Chinese and 33 Caucasians. In control Chinese children, the eNO level (median: interquantile range) was significantly higher (P<0.001) in males (17.0 parts per billion (p.p.b.); 10.7-36.6) than in females (10.8 p.p.b.; 7.8-17.6). When compared with Caucasian control males (11.6 p.p.b.; 8.2-19.3) and females (9.1 p.p.b.; 7.5-11.9), the Chinese children had significantly higher eNO levels for both males (P=0.011) and females (P=0.037). For Chinese asthmatic males, the median eNO (interquartile range) was 39.8 p.p.b. (12.5-73.8), and for asthmatic females, 18.0 (9.6-56.3). After controlling for sex in Chinese controls, eNO did not have any significant correlation with height, weight and body mass index or body surface area. CONCLUSIONS: This study demonstrates a gender difference of eNO level in healthy Chinese schoolchildren. When compared with Caucasians, Chinese children have significantly higher eNO levels.

Adolescent↗