Changes in serum leptin concentration after corticosteroid treatment in preterm infants

The aim of this study was to investigate the effect of postnatal systemic dexamethasone on serum leptin, insulin and hormones of the hypothalamic-pituitary-adrenal (HPA) axis in preterm, very low birthweight (VLBW) infants. Nineteen VLBW infants who received a 3 wk dose tapering course of dexamethasone for treatment of bronchopulmonary dysplasia were prospectively enrolled. Blood for hormone assays was collected immediately before the start of the dexamethasone course (T(d-per)), 3 wk after commencement of the drug (T(d-end)) and 2 wk after dexamethasone treatment had been stopped (T(d-post)). In addition, 28 VLBW infants who participated in a concurrent longitudinal leptin study within the same period but did not receive corticosteroid had their serum leptin and insulin concentrations serially monitored. Blood specimens for the latter group of infants were obtained at 2 (T(wk-2)), 5 (T(wk-5)) and 7 (T(wk-7)) wk of postnatal age. Serum leptin and insulin at T(d-end) were significantly increased, whereas plasma ACTH and serum cortisol were significantly suppressed compared with the pretreatment (T(d-pre)) levels in the corticosteroid group (p < 0.0001 for leptin and insulin; p < 0.05 and p < 0.001 for ACTH and cortisol, respectively). In contrast, serum leptin and insulin at weeks 5 (T(wk-5)) and 7 (T(wk-7)) did not differ significantly from their respective levels at week 2 (T(wk-2)) in the non-treatment group.

CONCLUSION

The administration of systemic corticosteroid resulted in significant increases in serum leptin and insulin, but marked suppression of hormones of the HPA axis. The effect of dexamethasone on the "adipoinsular" and HPA axes was transient and reversible. The adipoinsular axis in preterm infants is likely to be functional and active at an early stage of human development, and leptin may regulate energy balance in VLBW infants in the early postnatal period. Corticosteroids may, through the adipoinsular axis or its associated pathways, mediate in the regulation of body weight in preterm neonates.

3-methyglutaconic aciduria in a Chinese patient with glycogen storage disease Ib

We report elevated urinary excretion of 3-methylglutaconic (3MGC) and 3-methylglutaric acids (3MGR) in a patient with glycogen storage disease Ib. Combined excretion was 10-fold elevated in comparison to control during inadequate glucose maintenance, and still elevated following dietary improvement. 3MGC acid excretion correlated with plasma lactate and glucose. We speculate that imbalanced gluconeogenesis and de novo cholesterol synthesis result in secondarily increased 3MGC/3MGR production.

Distribution in allele frequencies of predisposition-to-atopy genotypes in Chinese children

Asthma is one of the most common chronic diseases in childhood; it is caused by a complex interaction between genetic factors and exposure to environmental allergens and irritants. Previous studies using the candidate gene approach showed that asthma was linked to a number of susceptibility genetic loci in Caucasian subjects. There are, however, only a few studies on asthma predisposition genes in the Chinese population. We studied the distribution of allele frequencies of I50V for the interleukin-4 receptor, two polymorphisms in intron 2 and exon 7 for the high-affinity IgE receptor (Fc epsilon RI-beta), R16G and E27Q for the beta(2)-adrenoceptor,and R275Q (824G/A) for CC chemokine receptor 3 in Chinese children.Seventy-six patients, with a mean age of 10.6 years, and 70 age- and sex-matched controls, were studied. Significantly more subjects in the asthma group had specific IgE antibodies against environmental allergens (P < 0.0001; odds ratio, 9.82). Genotyping of the six genetic markers showed that none of the six polymorphisms was associated with asthma in this cohort. The allele frequencies of I50V, R16G, and E27Q in our population were similar to those published for Asian subjects but not Caucasians. The R275Q substitution was a rare finding in our study and in the published reports. Our results demonstrate ethnic differences in polymorphisms of atopy candidate genes. Additional studies involving larger samples are required to investigate the association between asthma or atopy and the genotypes studied to date in Chinese children.

Cobblestone area-forming cells, long-term culture-initiating cells and NOD/SCID repopulating cells in human neonatal blood: a comparison with umbilical cord blood

Our prior study demonstrated that neonatal blood (NB) contained hematopoietic stem and progenitor cells that declined rapidly after birth. To validate that NB is a source of functional stem cells, we characterized this population in terms of cobblestone area-forming cells (CAFC), long-term culture-initiating cells (LTC-IC) and NOD/SCID mouse repopulating cells (SRC) in NB and umbilical cord blood (CB). Our data demonstrated that the frequencies of CAFC (30.2 vs 37.1, P = 0.14) and LTC-IC (28.6 vs 31.0, P = 0.49) in 1 x 10(5) mononuclear cells (MNC) of NB and CB were similar, suggesting that these cells were preserved in the circulation of the neonates shortly after birth. Sublethally irradiated NOD/SCID mice were transplanted with CD34(+) cells enriched from thawed NB and CB. At 6 weeks post transplant, human (hu)CD45(+) cells were detected in the bone marrow (BM), spleen and peripheral blood (PB) of the mice as demonstrated by flow cytometric and DNA analysis. Levels of huCD45(+)cells and colony forming units (CFU) appeared to be dependent on the infusion cell dose and were higher in animals receiving CB cells when compared with those of the NB group. The transplanted cells were capable of differentiation into multi-lineage progenitor cells (CD34(+) cells and differential CFU), as well as mature myeloid (CD14(+), CD33(+)), B lymphoid (CD19(+)) and megakaryocytic (CD61(+)) cells in the recipients. NB cells, subjected to ex vivo culture in an optimized preclinical condition, were significantly expanded to early and committed progenitor cells. Expanded NB contained SRC at a reduced quantity but with high proportions of CD14(+) cells and CD33(+) cells. Our study confirms that NB contains pluripotent hematopoietic stem and progenitor cells capable of homing and engrafting the NOD/SCID mice.

Reference ranges and factors affecting the human corticotropin-releasing hormone test in preterm, very low birth weight infants

This prospective study aims to investigate the factors that influence the human CRH (hCRH) test and to provide reference ranges for plasma corticotropin (ACTH) and serum cortisol concentrations of the stimulation test in preterm, very low birth weight (VLBW) infants. Two hundred twenty-six hCRH tests were performed on 137 VLBW infants at d 7 and 14 of life. Plasma ACTH did not differ significantly between infants whose mothers did not receive antenatal corticosteroids (group 1) and those whose mothers received one or two doses (group 2) or more than two doses (group 3) of the drug. However, plasma ACTH levels at d 7 were found to be significantly higher in infants with severe lung disease who required intermittent positive-pressure ventilation (IPPV) or high-frequency oscillation ventilation (HFOV), compared with those who had milder pulmonary disease and did not require mechanical ventilation or needed only continuous positive airway pressure (CPAP) support (P < 0.011). A significantly higher rate of increase in plasma ACTH concentration at d 7 was also observed in infants whose mothers suffered from antepartum hemorrhage (P < 0.016). In contrast, infants in group 2 had significantly lower serum cortisol, compared with group 1 infants (P < 0.05), whereas group 3 infants did not have serum cortisol levels significantly different from those of patients in group 1 or 2. Significant positive correlation between serum cortisol at d 7 and the time interval between the last dose of antenatal dexamethasone and delivery was also observed in group 3 infants (r > 0.33, P < 0.045). In addition, infants who required IPPV or HFOV had significantly lower serum cortisol at d 7 (P < 0.0001), but this pattern of cortisol response was reversed on d 14, with infants requiring IPPV or HFOV having significantly higher serum cortisol (P < 0.036). The reference ranges for plasma ACTH and serum cortisol concentrations of the hCRH test at d 7 and 14 were also provided for group 1 and group 2 infants. This study demonstrates that even one or two doses of antenatal corticosteroids cause adrenal suppression in VLBW infants. Maternal antepartum hemorrhage also influences the pituitary response of preterm newborns in the first week of life. The change in the pattern of cortisol response in sick ventilated (IPPV or HFOV) infants during the first 2 wk of life suggests that a proportion of preterm infants may have inadequate adrenal response to stress in early postnatal life, but it is likely that rapid adaptation of the hypothalamic-pituitary-adrenal axis results in enhanced and more appropriate cortisol response by d 14. The percentile distribution of plasma ACTH and serum cortisol responses provides useful statistical reference data for interpretation of the hCRH test in VLBW infants and may also assist in facilitating the use of corticosteroids replacement therapy in cases with clinical manifestations suggestive of adrenal insufficiency.

Respiratory function in patients with thalassaemia major: relation with iron overload

AIMS

(1) To determine the pattern of respiratory impairment in children with thalassaemia major (TM); (2) to assess the relation between the degree of respiratory impairment and total body iron content.

METHODS

Twenty nine TM patients were recruited. All underwent physical examination, standardised pulmonary function tests (spirometry, lung volume, and single breath diffusion capacity for carbon monoxide), and magnetic resonance imaging measurements of the liver. Serum ferritin was measured. The signal intensity ratio of liver to that of paraspinal muscle (T1 weighted sequence) and serum ferritin were used as surrogate index of body iron content.

RESULTS

Sixteen boys and 13 girls (median age 14.2 years) were studied. None had clinical evidence of congestive heart failure. Sixteen had normal lung function. Impairment of diffusion capacity (median DL(co) 83.5% predicted) was the most common abnormality, being observed in 34% of patients. Pure restrictive and obstructive ventilatory impairment was found in one and two patients respectively. Five patients had a combination of ventilation and diffusion defects. There was no correlation between the degree of impairment of each respiratory abnormality and body iron content.

CONCLUSION

Diffusion impairment was the commonest abnormality found in our cohort of paediatric TM patients. Our data did not support the notion that respiratory function impairment was correlated with body iron content.

Use of tonsil size in the evaluation of obstructive sleep apnoea

AIMS

(1) To determine the extent to which tonsil size contributes to the severity of obstructive sleep apnoea (OSA) in children; and (2) to assess the use of tonsillar-pharyngeal (TP) ratio in differentiating patients with different severity of OSA.

METHODS

Lateral neck radiograph was performed on 35 children referred consecutively to a university paediatric chest clinic for suspected OSA secondary to tonsillar hypertrophy. The tonsil size was determined by measuring the TP ratio on the radiographs. The severity of OSA was assessed by overnight polysomnography.

RESULTS

A total of 24 boys and 11 girls (median age 6.2 years) were studied. All presented with symptoms of OSA, and tonsillar hypertrophy was detected on clinical examination. The median apnoea-hypopnoea index (AHI) was 16.93 (interquartile range: 8.41 to 28.29). The median TP ratio was 0.76 (interquartile range: 0.65 to 0.80). AHI was positively correlated with the TP ratio. The clinical tonsil size did not correlate with the AHI or the TP ratio. Using a TP ratio of 0.479, the sensitivity and specificity in predicting cases with moderate/severe OSA (AHI >10) were 95.8% and 81.8% respectively, while the positive and negative predictive values were 92.0% and 90.0% respectively.

CONCLUSIONS

Results show that in a population of children with OSA, tonsillar hypertrophy as assessed by lateral neck radiograph correlates positively with the severity of obstructive sleep apnoea. The TP ratio has high sensitivity and specificity in predicting those with moderate/severe disease and this feature may be used as a clinical screening method in prioritising patients with OSA for further assessment.

CTLA-4 gene A-G polymorphism and childhood Graves' disease

OBJECTIVE

Graves' disease is associated with a polymorphism at position 49 in exon 1 of the cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene in Caucasians and Japanese. A high incidence of childhood Graves' disease has been documented in Hong Kong Chinese. The aims of this study were to investigate the CTLA-4 gene A-G polymorphism association in Chinese children with Graves' disease.

PATIENTS AND DESIGN

One hundred and twenty-three Chinese children with Graves' disease (104 girls and 19 boys) and 158 racially matched healthy controls were recruited for the study. Genomic DNA was extracted from venous blood samples. The dimorphism at position 49 A-G was analysed by polymerase chain reaction, single-strand conformation polymorphism and restriction fragment-length polymorphism analysis.

RESULTS

The genotype distribution and allele frequencies of children with Graves' disease differed significantly from those of the controls (P = 0.0023 and P = 0.022, respectively). The presence of at least one G allele (GG or AG) was associated with an increased risk of Graves' disease (OR = 6.8, 95% CI = 2.0-36.1; P = 0.001).

CONCLUSIONS

This study confirms that CTLA-4 49 A-G polymorphism is associated with Graves' disease in Chinese children. The CTLA-4 49 G allele confers an increased risk of childhood Graves' disease.

Individual allergens as risk factors for asthma and bronchial hyperresponsiveness in Chinese children

The role of allergen sensitization in the development of asthma in the Chinese is not clear. This study aims to determine the relationship of sensitization to individual allergens, and the development of asthma and bronchial hyperresponsiveness (BHR) in schoolchildren from three Chinese cities: Hong Kong, Beijing and Guangzhou. Community-based random samples of 10-yr-old schoolchildren from three Chinese cities were recruited for study using the International Study of Asthma and Allergies in Childhood (ISAAC) Phase II protocol. Subjects were studied by parental questionnaires (n=10,902), skin-prick tests (n=3,479), and methacholine challenge tests (n=608). The prevalence rates of wheeze in the past 12 months (Hong Kong, 5.8%; Beijing, 3.8%; Guangzhou, 3.4%) and atopy (Hong Kong, 41.2%; Beijing, 23.9%; Guangzhou, 30.8%) were highest in schoolchildren from Hong Kong. Multivariate logistic regression analyses revealed that sensitization to Dermatophagoides pteronyssinus (odds ratio (OR)=4.48; 95% confidence interval (CI): 3.02-6.66), cat (2.59; 1.67-4.03), Dermatophagoides farinae (2.41; 1.65-3.51) and mixed grass pollen (2.85; 1.24-6.50) were significantly associated with current wheeze. Atopy, defined as having > or = 1 positive skin-prick tests, was not an independent risk factor for current wheeze in children from any of the three cities. Furthermore, atopy (OR=2.53; 95% CI: 1.07-5.97), sensitization to cat (3.01; 1.39-6.52) and D. farinae (3.67; 1.93-6.97) were significantly associated with BHR. The authors confirmed that sensitization to house dust mite and cat was significantly associated with current wheeze and bronchial hyperresponsiveness in Chinese schoolchildren. However, the difference in the prevalence rate of atopic sensitization cannot explain the higher prevalence of childhood asthma in Hong Kong, when compared with those children from Beijing and Guangzhou.

Changes in markers of bone metabolism during dexamethasone treatment for chronic lung disease in preterm infants

AIM

To characterise the change in serum and urinary bone markers in the early postnatal period, and to assess the effect of systemic corticosteroid on bone metabolism in preterm infants.

METHODS

Bone formation was quantified by measurement of serum concentrations of bone specific alkaline phosphatase (BALP) and osteocalcin. Bone resorption was measured by monitoring creatinine adjusted urinary deoxypyridinoline (Dpd) concentration. Blood and urinary samples were collected from corticosteroid treated infants (n = 19) immediately before the start (T(d-pre)), three weeks after the start (T(d-end)), and two (T(d-post2)) and four weeks (T(d-post4)) after the end of the dexamethasone course. Untreated patients (n = 30) had specimens taken at week 3 (T(wk-3)), 6 (T(wk-6)), 8 (T(wk-8)), and 10 (T(wk-10)) of postnatal age.

RESULTS

Serum concentrations of BALP and osteocalcin at T(d-end) were significantly lower than pretreatment levels and the levels at the corresponding time point (T(wk-6)) of the non-treatment group. In contrast, urinary Dpd concentration at T(d-end) was not significantly decreased compared with the pretreatment level. However, it was significantly lower than the urinary Dpd concentration at T(wk-6) of the non-treatment group. The rate of increase in lower leg length was significantly higher in the non-treatment group between weeks 3 and 6 than in the corresponding period during dexamethasone treatment in the corticosteroid group.

CONCLUSION

Systemic corticosteroid causes appreciable suppression of serum BALP and osteocalcin and, to a lesser extent, urinary Dpd. The results suggest that corticosteroid inhibits bone growth mainly by decreasing bone formation.

Preclinical ex vivo expansion of cord blood hematopoietic stem and progenitor cells: duration of culture; the media, serum supplements, and growth factors used; and engraftment in NOD/SCID mice

BACKGROUND

Ex vivo expansion of cord blood (CB) hematopoietic stem and progenitor cells increases cell dose and may reduce the severity and duration of neutropenia and thrombocytopenia after transplantation. This study's purpose was to establish a clinically applicable culture system by investigating the use of cytokines, serum-free media, and autologous plasma for the expansion of CB cells and the engraftment of expanded product in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice.

STUDY DESIGN AND METHODS

Enriched CB CD34+ cells were cultured in four media (Iscove's modified Dulbecco's medium with FCS, Gibco; X-Vivo-10, BioWhittaker; QBSF-60, Quality Biological; and StemSpan SFEM, Stem Cell Technologies) with four cytokine combinations (thrombopoietin [TPO], SCF, Flt-3 ligand [FL] with and without G-CSF, and/or IL-6). The effect of autologous CB plasma was also investigated. The read-out measures were evaluated on Days 8 and 12. After expansion at the optimized condition, cultured cells were transplanted into sublethally irradiated NOD/SCID mice. The engraftment of human CD45+ cells and subsets in the bone marrow, spleen, and peripheral blood was determined.

RESULTS

QBSF-60 or StemSpan SFEM supported high yields of early progenitors (CD34+ cells, <or= 64.8-fold; CD34+CD38- cells, 330-fold; CFU-granulocyte erythroid macrophage megakaryocyte [GEMM], 248-fold) and CFUs of the myeloid (CFU-GM, 407-fold) and erythroid (BFU/CFU-E, 144-fold) lineages. The expansion of the megakaryocytic lineage was consistently higher in X-Vivo-10 (CFU-megakaryocyte, 684-fold). Autologous plasma promoted colony formation but reduced CD34+ cells and CFU-GEMM. The addition of G-CSF or IL-6 improved cell yields; G-CSF was more effective for committed progenitors. Expansion products from cultures in QBSF-60 with the cytokines engrafted and differentiated into the myeloid and lymphoid lineages in NOD/SCID mice.

CONCLUSION

The data supported the strategy of expansion. The optimized condition may be applicable to clinical expansion for the abrogation or reduction of posttransplant cytopenia.

Neonatal jaundice--traditional Chinese medicine approach

Herbal treatment of neonatal jaundice (NNJ) has been practiced in China for a long time. Even to-date, a variety of herbal items, including "Yin-chin" (Artemisia), "Huang-qin" (Scutellaria), "Da-huang" (Rheum officinale), "Gan-cao" (Glycyrrhiza), and "Huang-lin" (Coptis chinesis), are still being prescribed to jaundiced infants, often in combination with modern treatment such as phototherapy and exchange transfusion. Their efficacy has, however, not been tested by properly conducted randomised controlled trial. On the other hand, exposure to herbs either before or after birth has been suspected to be a cause of hemolysis and jaundice in the newborns. It is also widely believed in the Chinese community that a number of herbal items are hemolytic agents in infants deficient in the enzyme glucose-6-phosphate dehydrogenase (G6PD). The belief is so deep rooted that each infant detected to have G6PD deficiency by neonatal cord blood screening is given a G6PD deficiency alert card, which states that the child must avoid these herb items for life. In a cohort of 1008 mother-infant pairs, however, we have previously shown that there was no association between maternal herb consumption during pregnancy and the incidence or severity of neonatal hyperbilirubinemia in their offsprings, including those who were deficient in G6PD. A thorough search of medical literature also fails to detect any evidence that any of the herbs stated in the G6PD deficiency alert card causes hemolysis in G6PD-deficient subjects. Thus, there are many misunderstandings and unsubstantiated beliefs about the relationship between herbal medicine and NNJ. Given the potential usefulness of Chinese traditional medicine, which has been practiced for almost 3000 years and is still gaining momentum in the modern days, extensive scientific studies to determine the therapeutic efficacy and potential harmful effects of the various herbal items are warranted.

Overview of common inherited metabolic diseases in a Southern Chinese population of Hong Kong

BACKGROUND

The Joint metabolic clinic at the Prince of Wales Hospital was established in January 1997 to provide a comprehensive multi-disciplinary care to patients with inherited metabolic diseases (IMDs). Patients are referred from both within and outside our hospital. Until July, 2000, more than 40 patients and families with 20 different biochemical diagnoses attend the clinic for regular follow up. A pattern of more common IMDs among Hong Kong Chinese emerged from our case registry. In order to advance the understanding of Chinese metabolic diseases, we examined the molecular basis of those diseases with unique features in Chinese or were locally prevalent. Mutations were found in patients with primary carnitine deficiency, ornithine transcarbamylase deficiency, X-linked adrenoleukodystrophy, glutaric aciduria type I, and galactosemia. We also analyzed the mutations in multiple carboxylase deficiency and Niemann-pick type C on four families.

CONCLUSIONS

Although IMDs are a significant cause of mortality and morbidity among pediatric patients, with a better understanding of the molecular genetics of these diseases, prenatal diagnosis of these common IMDs will be facilitated, which is currently the most effective way of controlling IMDs.

Asthma, atopy and tuberculin responses in Chinese schoolchildren in Hong Kong

BACKGROUND

The prevalence rates of asthma and other atopic disorders have increased steadily in many developed countries over the past few decades. Recent epidemiological and animal studies have suggested that BCG vaccination might be beneficial in reducing the subsequent development of atopy. This study investigates the relationship between asthma, allergic symptoms, atopy, and tuberculin response in Chinese schoolchildren who received BCG vaccination at birth.

METHODS

A total of 3110 schoolchildren aged 10 years were recruited for the Hong Kong arm of the phase II International Study of Asthma and Allergies in Childhood. Of the 2599 children born in Hong Kong and vaccinated with BCG after birth, 2201 had tuberculin testing performed at a mean (SD) age of 8.4 (1.4) years. A random subsample of 980 children was also recruited for skin prick testing.

RESULTS

The prevalence rates of asthma ever, wheeze ever, current wheeze, current rhinoconjunctivitis, and current flexural eczema were not significantly different between tuberculin positive and negative subjects. The mean (SE) tuberculin response was 3.4 (0.2) mm in atopic subjects and 3.3 (0.2) mm in non-atopic subjects (difference not significant). Logistic regression analyses did not reveal any significant relationship between asthma ever, current wheeze, atopy, and positive tuberculin responses.

CONCLUSIONS

This study did not find any relationship between asthma, allergic symptoms, atopy, and positive tuberculin reactivity in Chinese schoolchildren vaccinated with BCG at birth.

Manganese intake and cholestatic jaundice in neonates receiving parenteral nutrition: a randomized controlled study

Infants requiring parenteral nutrition (n = 244) were randomized to receive either 1 (group 1, n = 121) or 0.0182 micromol/kg/d (group 2, n = 123) of manganese supplementation. The whole-blood manganese and serum direct bilirubin concentrations of the infants were monitored, as was the development of cholestasis (peak serum direct bilirubin concentration >50 micromol/L). Subgroup analysis was carried out on the data of 78 infants in group 1 and 82 in group 2 who had received manganese supplementation and more than three-quarters of their total daily fluid as parenteral nutrition for >14 d. Of all the infants randomized, the high manganese group (group 1) showed a trend towards developing higher peak whole-blood manganese concentration [group 1 versus group 2: median (interquartile range): 606.0 (421.0; 1005.0) vs 566.0 (336.0: 858.0); p=0.061] and higher peak serum direct bilirubin concentration [37.0 (10.5; 122.5) vs 19.0 (8.0; 112.5); p=0.153], but the differences between the 2 groups did not reach statistical significance. The 2 groups did not differ in terms of the occurrence of cholestasis during parenteral nutrition (63/121 vs 57/123; p=0.444). Subgroup analysis of infants who had received more than three-quarters of their total daily fluid as parenteral nutrition showed, however, that the high manganese group developed significantly higher whole-blood manganese concentration [743.5 (498.0; 1211.0) vs 587.0 (438.0; 982.0); p=0.037] and serum direct bilirubin concentration [84.0 (28.0; 170.0) vs 25.5 (9.0; 117.0): p < 0.001]. Although there was no significant difference in the occurrence of cholestasis (58/78 vs 49/82; p = 0.073), more infants in the high manganese group developed a more severe degree of direct hyperbilirubinaemia, with peak serum direct bilirubin >100 micromol/L (32/78 vs 20/82; p = 0.038).

CONCLUSION

We conclude that the pathogenesis of parenteral nutrition-related cholestasis is probably multifactorial, and that high manganese intake is a significant contributory factor.

Oxygen consumption by lungs with acute and chronic injury in a rabbit model

OBJECTIVE

To study the oxygen consumption by lungs with acquired acute and chronic injury in a rabbit model.

DESIGN

A non-randomized controlled animal study.

SUBJECTS AND METHOD

Three groups of White New Zealand rabbits were studied to determine the oxygen consumption of the lungs. Group 1 (n=21, controls) consisted of healthy rabbits with normal lungs. The rabbits in group 2 (n=14) had sustained acute lung damage induced by subcutaneous N-nitroso-N-methylurethane and those in group 3 (n=9) had sustained chronic lung damage inflicted by a single dose of intra-tracheal bleomycin. Pulmonary oxygen consumption was estimated from the difference between the whole body oxygen consumption, measured by indirect calorimetry, and systemic oxygen consumption estimated by the Fick method.

MEASUREMENTS AND RESULTS

Both acute and chronic lung-damaged groups had significantly greater pulmonary oxygen consumption than the control group, both as absolute values [control vs acute vs chronic: 0.25 (0.04) vs 0.76 (0.10) vs 1.77 (0.21) ml/kg per min, p<0.001], and as a percentage of total body oxygen consumption [2.98 (0.47) vs 9.34 (1.39) vs 20.20 (2.11)%, p<0.0001]. Histological evaluation of the severity of lung damage using a lung-injury score revealed significantly higher scores in both lung-injury groups than in the controls.

CONCLUSIONS

These findings suggest that the lung is an important site of energy loss in subjects with acute and chronic lung injury.

Obstructive sleep apnoea in children with adenotonsillar hypertrophy: prospective study

OBJECTIVE

To determine clinical and baseline polysomnographic data on obstructive sleep apnoea secondary to adenotonsillar hypertrophy in Hong Kong Chinese children.

DESIGN

Prospective study.

SETTING

University teaching hospital, Hong Kong.

PARTICIPANTS

Fifty children (35 boys and 15 girls) suspected to have obstructive sleep apnoea were recruited between January 1999 and December 1999.

MAIN OUTCOME MEASURES

Symptoms questionnaire, electrocardiogram, chest radiograph, and full-night polysomnography.

RESULTS

All patients had symptoms suggestive of obstructive sleep apnoea. None were found to have clinical evidence of cor pulmonale. Forty-five (90%) of 50 children had obstructive sleep apnoea with a respiratory disturbance index of greater than five. Central and mixed apnoeas were rare. Tonsil size did not correlate with the severity of obstructive sleep apnoea.

CONCLUSION

Symptoms and signs suggestive of obstructive sleep apnoea can lead to a high detection rate and confirmation of obstructive sleep apnoea by polysomnography.

Temporal relationship between air pollution and hospital admissions for asthmatic children in Hong Kong

BACKGROUND

Many epidemiological studies have shown positive association between respiratory health and current levels of outdoor air pollution in Europe and America.

OBJECTIVE

The aim of this study was to investigate the association between air pollution and the number of childhood admissions for asthma in Hong Kong.

METHODS

Daily counts of childhood admission for asthma to a large teaching Hospital were obtained from the computerized database for the period 1993-1994. A Poisson regression allowing for seasonal patterns and meteorological conditions was used to assess the associations between the number of Hospital admissions and the three pollutants: nitrogen dioxide, sulphur dioxide and inhalable particles (measured as PM10, particles < 10 microm in aerodynamic diameter).

RESULTS

A total of 1217 children under 15 years of age were admitted for asthma during the study period. The calculated annual hospitalization rates were 283 and 178 per 100 000 for boys and girls, respectively. The mean PM10, NO2 and SO2 levels were 44.1 microg/m3, 43.3 microg/m3, and 12.2 microg/m3, respectively. Daily admission for asthma increased significantly with increasing ambient level of nitrogen dioxide (relative risk (RR) = 1.08 per 10 microg/m3 increase), sulphur dioxide (RR = 1.06) and inhalable particles (RR = 1.03). No association was found between hospital admission and humidity, temperature or atmospheric pressure.

CONCLUSION

This is the first daily time series study of childhood admissions for asthma and air pollution in Hong Kong. The results support that current levels of air pollution contribute to the respiratory morbidity in asthmatic children in Hong Kong.

Prevalence of respiratory and atopic disorders in Chinese schoolchildren

BACKGROUND

Epidemiological surveys have shown that the prevalence of asthma in the Asian population is relatively low. Within the Chinese population, schoolchildren from Hong Kong were found to have the highest rate of asthma.

OBJECTIVE

To compare the prevalence of respiratory and atopic disorders, and to assess the role of atopy in the development of asthma, in Chinese schoolchildren from Hong Kong, Beijing and Guangzhou.

METHODS

Community-based random samples of schoolchildren aged 9-11 years from three Chinese cities (Hong Kong, Beijing and Guangzhou) were recruited for study using the International Study of Asthma and Allergies in Childhood (ISAAC) Phase II protocol. Subjects were studied by parental questionnaires (n = 10902), skin-prick tests (n = 3479) and skin examination (n = 3479).

RESULTS

The prevalence rates of current wheeze, speech limiting wheeze, rhinoconjunctivitis and flexural dermatitis were significantly more common in Hong Kong than in Beijing or Guangzhou. The atopy rate was also higher in Hong Kong (41.2%) than in Beijing (23.9%) or Guangzhou (30.8%). Atopy was strongly correlated with current wheeze (OR 7.74; 95% CI = 5.70-10.51). Subgroup analyses of children from Hong Kong revealed that children born in mainland China who had subsequently migrated to Hong Kong had a significantly lower rate of allergic symptoms and atopy than those children born in Hong Kong.

CONCLUSION

Using a standardized written questionnaire along with a skin prick test and skin examination, we confirmed that the prevalence of asthma, allergic diseases and atopy was highest in schoolchildren from Hong Kong. Atopic sensitization is an important factor associated with asthma in Chinese children.

Rhabdomyolysis following status asthmaticus

A 15-year-old Chinese boy developed rhabdomyolysis with myoglobinuria and marked elevation of serum creatine phosphokinase following a prolonged and severe attack of asthma. He recovered after vigorous hydration and supportive treatment. Clinicians should be aware of this potentially fatal, albeit rare, complication of status asthmaticus.

Oxygen consumption and resting energy expenditure during phototherapy in full term and preterm newborn infants

OBJECTIVES

To determine the effect of phototherapy on the oxygen consumption and resting energy expenditure of term and preterm newborn infants.

METHODS

A total of 202 infants (gestation 30-42 weeks; body weight 1270-4100 g) requiring phototherapy for the treatment of neonatal hyperbilirubinaemia were enrolled in a randomised crossover study. In random sequence, the oxygen consumption and resting energy expenditure were measured twice in each infant by indirect calorimetry, once at the end of six hours of continuous phototherapy and once after a control period of at least six hours without phototherapy. Anterior abdominal wall temperature was servocontrolled at 36.5 degrees C throughout the study.

RESULTS

At the end of six hours of continuous phototherapy, oxygen consumption (mean (SD): 6.21 (1.35) v 6.26 (1.51) ml/kg, p = 0.555) and resting energy expenditure (178.11 (37.62) v 180.37 (43.14) kJ/kg/24 h, p = 0.382) did not differ significantly from those measured after the control period. There were also no significant differences in heart rate, respiratory rate, or rectal temperature. Subgroup analysis of those of gestation < 37 weeks or < 34 weeks also showed no effect of phototherapy on either oxygen consumption or resting energy expenditure.

CONCLUSION

Phototherapy has no effect on the metabolic rate of thermally stable term or preterm infants.

Deceptive hyperbilirubinaemia in a newborn with familial lipoprotein lipase deficiency

A rare case of familial lipoprotein lipase (LPL) deficiency in a Chinese newborn who presented with severe hyperbilirubinaemia is described. The falsely high serum bilirubin concentration was subsequently found to be a laboratory analytical error caused by interference of optical measurement of the lipaemic serum. Hypertriglyceridaemia and chylomicronaemia could be safely and effectively controlled by a fat-restricted diet using either modified elementary milk formula fortified with protein, calories and minerals, or the commercially available special milk formula such as Monogen or Portagen. DNA sequence analysis of the patient showed a Leu252Arg mutation in exon 6 of both alleles of the LPL gene. Although the parents were unrelated, both were heterozygous carriers of the same genetic defect. Codon 252 in exon 6 appears to be a common and critical site of mutation in the LPL gene of Chinese, but this important association has not been recognized previously.

Platelet-derived growth factor enhances ex vivo expansion of megakaryocytic progenitors from human cord blood

Infusion of ex vivo expanded megakaryocytic (MK) progenitor cells is a strategy for shortening the duration of thrombocytopenia after haematopoietic stem cell transplantation. The cell dose after expansion has emerged as a critical factor for achieving the desired clinical outcomes. This study aimed to establish efficient conditions for the expansion of the MK lineage from enriched CD34(+) cells of umbilical cord blood and to investigate the effect of platelet-derived growth factor (PDGF) in this system. Our results demonstrated that thrombopoietin (TPO) alone produced a high proportion of CD61(+)CD41(+) cells but a low total cell count and high cell death, resulting in an inferior expansion. The addition of interleukin-1 beta (IL-1 beta), Flt-3 ligand (Flt-3L) and to a lesser extent IL-3 improved the expansion outcome. The treatment groups with three to five cytokines produced efficient expansions of CFU-MK up to 400-fold with the highest yield observed in the presence of TPO, IL-1 beta, IL-3, IL-6 and Flt-3L. CD34(+) cells were expanded by five to 22-fold. PDGF improved the expansion of all cell types with CD61(+)CD41(+) cells, CFU-MK and CD34(+) cells increased by 101%, 134% and 70%, respectively. On day 14, the CD61(+) population consisted of diploid (86.5%), tetraploid (11.8%) and polyploid (8N--32N; 1.69%) cells. Their levels were not affected by PDGF. TPO, IL-1 beta, IL-3, IL-6, Flt-3L and PDGF represented an effective cytokine combination for expanding MK progenitors while maintaining a moderate increase of CD34(+) cells. This study showed, for the first time, that PDGF enhanced the ex vivo expansion of the MK lineage, without promoting their in vitro maturation. PDGF might be a suitable growth factor to improve the ex vivo expansion of MK progenitors for clinical applications.

Changes of leptin and metabolic hormones in preterm infants: a longitudinal study in early postnatal life

OBJECTIVES

Very little is known concerning the physiological role of leptin and growth in the early postnatal period and the association of leptin with other metabolic hormones in preterm infants. This study aims to investigate these relationships, and to explore the longitudinal and dynamic profile of leptin and metabolic hormones including insulin, ACTH, cortisol and FT4 in this category of patient. We also postulate that a rapid increase in body weight and body mass index in the first few weeks of life may be associated with a corresponding increase in serum leptin if the 'adipoinsular axis' is active at this stage.

DESIGN

A longitudinal study in a cohort of preterm infants < 34 weeks gestation for the first five weeks of postnatal life.

PATIENTS AND METHODS

Sixty-one preterm newborns < 34 weeks gestation were prospectively enrolled. Blood samples were collected in the morning when the newborns were 24 h of age (day 1), and on days 5, 14 and 35 of life. Serum leptin, insulin, cortisol, FT4, glucose and plasma ACTH concentrations were analysed using standard biochemical methods. Spearman's correlation coefficient was used to assess the inter-relationship of different metabolic hormones on the first day of life, and the relationship between metabolic hormones on day 1 and anthropometric or clinical parameters. The mixed-effects models were further used for analysing the multiple longitudinal measurements, and also for comparing the hormone concentrations between day 1 (baseline) and their corresponding levels on days 5, 14 and 35.

RESULTS

Serum leptin on day 1 (baseline) was significantly associated with serum insulin (r = 0.30, P < 0.05) and insulin:glucose ratio (r = 0.29, P < 0.05) in infants < 34 weeks gestation. Female preterm infants had significantly higher serum leptin (P < 0.05) and insulin (P < 0.05) levels than male infants. In addition, the duration between the last dose of antenatal dexamethasone and delivery significantly influenced the serum concentrations of leptin (r = - 0.27, P < 0.05), cortisol (r = 0.52, P < 0.001), plasma ACTH (r = 0.28, P < 0.05) and insulin:glucose ratio (r = - 0.27, P < 0.05) on the first day of life. Despite significant increase in body weight (P < 0.00001) and body mass index (P < 0.00001) by day 35 when compared to birth weight, no corresponding significant changes were observed for serum leptin, insulin and FT4. However, there was an increasing though statistically nonsignificant trend in serum leptin after day 14 of life.

CONCLUSION

This study characterized the longitudinal profile of leptin and metabolic hormones in preterm infants < 34 weeks gestation in the first 5 weeks of life. Serum leptin was significantly associated with serum insulin and insulin:glucose ratio supporting the hypothesis that an 'adipoinsular axis' exists and is likely to be functional before 34 weeks of gestation. Although a significant increase in body weight was demonstrated by day 35, no significant corresponding changes occurred with regard to serum leptin. We postulate that the limited quantity of adipose tissue at this stage of development might have contributed to this observation. Moreover, our results also showed that the duration between the last dose of antenatal corticosteroid and delivery could influence the postnatal concentrations of adipoinsular and pituitary-adrenal hormones. Thus, it is possible that antenatal dexamethasone might affect fetal growth and development via these neuroendocrine pathways in early intrauterine life.