P C Ng

The Chinese University of Hong Kong, Hong Kong, Hong Kong

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Publications (228)878.19 Total impact

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    ABSTRACT: Makorin-2 (MKRN2) is a highly conserved protein and yet its functions are largely unknown. We investigated the expression levels of MKRN2 and RAF1 in normal and malignant hematopoietic cells, and leukemia cell lines. We also attempted to delineate the role of MKRN2 in umbilical cord blood CD34+ stem/progenitor cells and K562 cell line by over-expression and inhibition of MKRN2 through lentivirus transduction and shRNA nucleofection, respectively. Our results provided the first evidence on the ubiquitous expression of MKRN2 in normal hematopoietic cells, embryonic stem cell lines, primary leukemia and leukemic cell lines of myeloid, lymphoid, erythroid and megakaryocytic lineages. The expression levels of MKRN2 were generally higher in primary leukemia samples compared with those in age-matched normal BM cells. In all leukemia subtypes, there was no significant correlation between expression levels of MKRN2 and RAF1. sh-MKRN2-silenced CD34+ cells had a significantly lower proliferation capacity and decreased levels of the early stem/progenitor subpopulation (CFU-GEMM) compared with control cultures. Over-expression of MKRN2 in K562 cells increased cell proliferation. Our results indicated possible roles of MKRN2 in normal and malignant hematopoiesis.
    PLoS ONE 03/2014; 9(3):e92706. DOI:10.1371/journal.pone.0092706 · 3.53 Impact Factor
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    ABSTRACT: Background: Infants receiving prolonged parenteral nutrition (PN) are at risk of PN-associated cholestasis (PNAC). This can progress to hepatic failure and death if PN cannot be discontinued. Fish oil-based parenteral lipid preparation (FOLP) has been shown to be beneficial in case studies. Objectives: (1) To evaluate whether FOLP could halt or reverse the progression of PNAC compared with soy-based parenteral lipid preparation (SLP) and (2) to assess the effects of FOLP on liver function and physical growth. Methods: Design: double-blind randomised controlled trial. Setting: level III neonatal intensive care unit. Participants: infants with PNAC (plasma-conjugated bilirubin concentration ≥34 µmol/l or 2 mg/dl) expected to be PN-dependent for >2 weeks. Intervention: to receive either FOLP or SLP at 1.5 g/kg/day. Primary outcome measure: reversal of PNAC within 4 months after commencement of lipid treatment; secondary outcomes: rate of change of weekly liver function tests, infant growth parameters, blood lipid profile and episodes of late-onset sepsis. Results: A total of 9 infants were randomised to the FOLP group and 7 to the SLP group. There was no significant difference in reversal of PNAC at 4 months between groups. Rates of increase of plasma-conjugated bilirubin and alanine aminotransferase in the SLP group were significantly greater than the FOLP group (13.5 vs. 0.6 µmol/l per week and 9.1 vs. 1.1 IU/l per week, respectively, p = 0.03). Increased enteral nutrition was associated with significant improvement of PNAC in infants receiving FOLP compared with SLP (-8.5 vs. -1.6 µmol/l per 10% increase in enteral nutrition, respectively). The study was terminated prematurely. Conclusions: progression of PNAC in PN-dependent infants can be halted by replacing SLP with FOLP and reversed by increasing the proportion of enteral nutrition in infants receiving FOLP. Replacement of SLP with FOLP in PN-dependent infants who develop PNAC may be considered. © 2014 S. Karger AG, Basel.
    Neonatology 02/2014; 105(4):290-296. DOI:10.1159/000358267 · 2.57 Impact Factor
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    ABSTRACT: To provide a comprehensive database of gene regulation and compare differentially regulated molecular networks in human tissues of necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP). Both NEC and SIP are devastating surgical emergencies associated with high morbidity and mortality in preterm infants. Their pathophysiology and molecular mechanisms remain unclear. Differential whole genome microarray analysis was performed on intestinal tissues collected from NEC (n = 15) and SIP (n = 12) infants and compared with tissues collected from surgical-control patients with noninflammatory intestinal conditions (n = 14). Validation of 52 target gene expressions was performed by quantitative polymerase chain reaction. Regulatory networks of significantly affected genes were constructed according to functional pathways. Extensive and significant changes of gene expression were observed in NEC tissues, which comprised multiple pathways of angiogenesis, arginine metabolism, cell adhesion and chemotaxis, extracellular matrix remodeling, hypoxia and oxidative stress, inflammation, and muscle contraction. These dysregulated genes could be networked downstream of key receptors, TLR2, TLR4, and TREM1, and mediated via NF-κB, AP-1, and HIF1A transcription factor pathways, indicating predominant microbial and inflammatory involvement. In contrast, SIP tissues exhibited much milder and less diversified expressional changes, with target genes significantly associated with G-protein-mediated muscle contraction and extracellular matrix remodeling. The molecular evidence suggests that NEC and SIP are likely 2 different diseases caused by distinct etiology and pathophysiology. This first comprehensive database on differential gene expression profiles of human NEC and SIP tissues could lead to development of disease-specific diagnostic and prognostic biomarkers and new therapeutic strategies for improving outcomes.
    Annals of surgery 12/2013; DOI:10.1097/SLA.0000000000000374 · 7.19 Impact Factor
  • Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine 12/2013; 19 Suppl 8:10-1.
  • Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine 12/2013; 19 Suppl 8:12-5.
  • Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine 12/2013; 19 Suppl 9:21-5.
  • Pak Cheung Ng
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    ABSTRACT: Different categories of biomarkers of necrotising enterocolitis (NEC), including (i) non-specific mediators of the inflammatory cascade, e.g. acute phase reactants, chemokines, cytokines, and cell surface antigens, (ii) enhanced non-specific biomarkers, and (iii) specific gut-associated proteins, have distinctive biochemical characteristics and properties. The appropriateness of using these mediators in specific clinical situations, and the pros and cons of their applications as indicators or predictors of intestinal injury and NEC are highlighted. Many potentially new biomarkers such as micro-RNA, volatile organic compounds and gut microbiomes are currently under investigation. A stringent protocol for biomarker discovery is revealed so that investigators can consider this methodology as a reference for future discovery of organ-specific and/or disease-specific biomarkers for preterm infants.
    Seminars in Fetal and Neonatal Medicine 09/2013; DOI:10.1016/j.siny.2013.09.002 · 3.13 Impact Factor
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    ABSTRACT: Early detection and treatment of infected preterm infants could decrease morbidity and mortality. Neutrophil CD64 has been shown to be an excellent early diagnostic biomarker of late-onset sepsis (LOS) and necrotizing enterocolitis (NEC). We aimed to study whether using CD64 as a daily surveillance biomarker could predict LOS/NEC before clinical manifestation.METHODS: We collected 0.1 mL whole blood from very low birth weight (VLBW) infants from day 7 postnatal age until routine daily blood tests were no longer required. Four categories of responses were defined: proven sepsis, clinical sepsis, nonsepsis/non-NEC, and asymptomatic CD64 activation.RESULTS: A total of 146 infants were consecutively recruited and 155 episodes of sepsis evaluation were performed. The biomarker screening utility, sensitivity, specificity, positive predictive value, and negative predictive value for surveillance of LOS/NEC using a cutoff of 5655 antibody-PE (phycoerythrin) molecules bound/cell were 89%, 98%, 41%, and 99.8%, respectively. LOS/NEC was detected a mean of 1.5 days before clinical presentation. However, 63 episodes of CD64 activation occurred in asymptomatic infants who would not otherwise have required sepsis evaluations.CONCLUSIONS: As a surveillance biomarker, neutrophil CD64 detected LOS/NEC 1.5 days before clinical presentation, but at the expense of performing 41% additional sepsis evaluations. This was mainly attributed to an unexpected group of asymptomatic infants with CD64 activation, who recovered spontaneously and did not require antimicrobial treatment. The latter group has not been previously recognized in VLBW infants and could represent subclinical infection secondary to transient bacterial translocation or mild viral infection.
    Clinical Chemistry 09/2013; 59(12). DOI:10.1373/clinchem.2013.209536 · 7.77 Impact Factor
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    ABSTRACT: In newborn infants, the innate cellular system plays a crucial role in the first line of defense against pathogens. Neutrophils are the most abundant leukocytes, and their response to the commonly encountered nosocomial bacterial (Gram positive) infection in newborns remains largely unclear. In this study, a genome-wide expression array analysis was performed on CB neutrophils after challenge by PGN in vitro and compared with neutrophils in CTL cultures without PGN. We investigated responses of neutrophils to PGN and LPS, with respect to cytokine synthesis, chemotaxis, ROS production, cell death, and pathways of HSP response. Our results provide the first comprehensive expressional profile of neonatal neutrophils stimulated by PGN. mRNA levels of 16 up-regulated genes and 6 down-regulated genes were validated by qPCR. Their regulatory networks were identified downstream of TLR-2 and NOD-2, which work in concert toward signals of death, cytoprotection, inflammation, and stress responses. Members of the HSP family were significantly up-regulated in PGN-stimulated neutrophils, compared with those in LPS-stimulated cells. We confirmed protein co-precipitation of HSPA1A and OLR1 in stimulated neutrophils, and their transcription, induced by NF-κB but not by MAPK signals. We found increased CD11b, chemotaxis, TNF-α, and IL-8 in neutrophils stimulated by PGN or LPS. PGN, but not LPS, increased ROS production. We conclude that neonatal neutrophils are capable of vigorous molecular and functional responses to PGN and suggest that HSP plays a critical role in the host defense mechanism, possibly involving proinflammatory OLR1 and CD11b-facilitated chemotaxis.
    Journal of leukocyte biology 08/2013; 95(1). DOI:10.1189/jlb.0413219 · 4.99 Impact Factor
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  • Archives of Disease in Childhood - Fetal and Neonatal Edition 03/2013; DOI:10.1136/archdischild-2013-303717 · 3.86 Impact Factor
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    ABSTRACT: OBJECTIVES:: To evaluate the use of gut barrier proteins, liver-fatty acid binding protein (L-FABP), intestinal-fatty acid binding protein (I-FABP), and trefoil factor 3 (TFF3), as biomarkers for differentiating necrotizing enterocolitis (NEC) from septicemic/control infants and to identify the most severely affected surgical NEC from nonsurgical NEC infants. BACKGROUND:: Clinical features and routine radiologic investigations have low diagnostic utilities in identifying surgical NEC patients. METHODS: : The diagnostic utilities of individual biomarkers and the combination of biomarkers, the LIT score, were assessed among the NEC (n = 20), septicemia (n = 40), and control groups (n = 40) in a case-control study for the identification of proven NEC and surgical NEC infants. RESULTS: : Plasma concentrations of all gut barrier biomarkers and the LIT score were significantly higher in the NEC than in the septicemia or control group (P < 0.01). Using median values of biomarkers and the LIT score in the NEC group as cutoff values for identifying NEC from septicemic/control cases, all had specificities of 95% or more and sensitivities of 50%. Significantly higher levels of biomarkers and the LIT score were found in infants with surgical NEC than in nonsurgical NEC cases (P ≤ 0.02). The median LIT score of 4.5 identified surgical NEC cases with sensitivity and specificity of 83% and 100%%, respectively. A high LIT score of 6 identified nonsurvivors of NEC with sensitivity and specificity of 78% and 91%, respectively. CONCLUSIONS: : The LIT score can effectively differentiate surgical NEC from nonsurgical NEC infants and nonsurvivors of NEC from survivors at the onset of clinical presentation. Frontline neonatologists and surgeons may, therefore, target NEC infants who are most in need of close monitoring and those who may benefit from early surgical intervention.
    Annals of surgery 03/2013; DOI:10.1097/SLA.0b013e318288ea96 · 7.19 Impact Factor
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    ABSTRACT: This article summarizes the commonly used biomarkers currently available for diagnosis of necrotizing enterocolitis. The most exciting advances in diagnostic tests were the use of new nucleic acid sequencing techniques (eg, next-generation sequencing) and molecular screening methods (eg, proteomics and microarray analysis) for the discovery of novel biomarkers. The new technology platform coupled with stringent protocols of biomarker discovery and validation would enable neonatologists to study biologic systems at a level never before possible and discover unique biomarkers for specific organ injury and/or disease entity.
    Clinics in perinatology 03/2013; 40(1):149-59. DOI:10.1016/j.clp.2012.12.005 · 1.54 Impact Factor
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    ABSTRACT: BACKGROUND: International studies suggest that low dose prenatal methylmercury exposure (>29nmol/L) has long-term adverse neurocognitive effects. There is evidence that the majority of children in Hong Kong exceed this level as a result of high fish consumption of mothers during pregnancy. OBJECTIVE: To study whether there are any associations between low-dose prenatal methylmercury exposure and neurocognitive outcomes in Hong Kong children. MATERIALS AND METHODS: All 1057 children from the original birth cohort were eligible for entry into the study, except children with conditions that would affect neurocognitive development, but were unrelated to methylmercury exposure. Subjects were assessed by a wide panel of tests covering a broad range of neurocognitive functions: Hong Kong Wechsler Intelligence Scale for Children (HK-WISC), Hong Kong List Learning Test (HKLLT), Tests of Everyday Attention for Children (TEACH), Boston Naming Test, and Grooved Pegboard Test. RESULTS: 608 subjects were recruited (median age 8.2years, IQR 7.3, 8.8; 53.9% boys). After correction by confounders including child age and sex, multivariate analysis showed that cord blood mercury concentration was significantly associated with three subtests: Picture Arrangement of HK-WISC (coefficient -0.944, P=0.049) and Short and Long Delay Recall Difference of the HKLLT (coefficient -1.087, P=0.007 and coefficient -1.161, P=0.005, respectively), i.e., performance worsened with increasing prenatal methylmercury exposure in these subtests. CONCLUSIONS: Small, but statistically significant adverse associations between prenatal methylmercury exposure and long-term neurocognitive effects (a visual sequencing task and retention ability of verbal memory) were found in our study. These effects are compatible with findings of studies with higher prenatal methylmercury exposure levels and suggest that safe strategies to further reduce exposure levels in Hong Kong are desirable.
    Environment international 02/2013; 54C:59-64. DOI:10.1016/j.envint.2013.01.005 · 6.25 Impact Factor
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    ABSTRACT: Neonates possess a relatively "naive", yet inducible immune system. Our hypothesis is that upon strategic antigen exposure, cytokine priming and sensitization by accessory cells, natural killer (NK) cells could be activated to become a functional phenotype. We investigated the in vitro stimulation of cord blood (CB) and adult NK cells upon challenge with lipoteichoic acid (LTA), interleukin (IL)-15 and LTA-primed autologous macrophage-conditioned medium, using CD107a and CD69 phenotypes as indicators of activation. We also examined response of CB macrophages to LTA, in terms of P44/42 extracellular signal-regulated kinases (ERK1/2) activation and cytokine secretion. LTA significantly induced secretion of inflammatory cytokines tumor necrotic factor (TNF)-α, IL-6, IL-12 and activated the upstream signal of ERK1/2 phosphorylation in neonatal macrophages. The magnitude of responses to stimulation differed between neonatal and adult NK cells. Co-stimulation with IL-15 was critical for expansion of the CD69 and CD107a NK subpopulations in both neonatal and adult cells, upon a LTA challenge. NK cell activation could be enhanced by LTA-primed autologous macrophages through secretory factors. Our results indicated that neonatal macrophages and NK cells can evoke immunologic responses to a Gram-positive bacterial antigen. The combinatory priming strategy is relevant for development of novel protocols, such as IL-15 treatment, to compensate for the immaturity of the innate immune system in newborns against bacterial infections.
    Cytokine 11/2012; DOI:10.1016/j.cyto.2012.10.034 · 2.87 Impact Factor
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    ABSTRACT: BACKGROUND: Selected reaction monitoring (SRM) is a reliable mass spectrometry (MS)-based technique for quantification of small molecules. However, it is not applicable to matrix assisted laser desorption ionization time-of-flight/time-of-flight tandem MS (MALDI-TOF/TOF MS) instruments. This work presents a novel comparable MALDI-TOF/TOF MS technique, "Parallel Fragmentation Monitoring" (PFM), for high-throughput quantification of citrulline. METHOD: Calibrator/sample solutions were spiked with internal standard that was a stable isotopic analog with 1 mass unit heavier than citrulline. Both citrulline and internal standard were isolated and fragmented in parallel by MALDI-TOF/TOF MS in the presence of graphitized carbon nanoparticles as matrix. The ratio of the peak intensities of the selected fragments from citrulline to internal standard was used to calibrate/calculate the concentrations of citrulline in samples. RESULTS: Linear calibration curves were obtained in the range of 10-250μmol/l citrulline with correlation coefficients≥0.997. Stored calibration curve and batch-specific calibration curve produced highly similar measurement values. Within- and between-day CVs were 3.1 - 8.7% and 3.5 - 10.6%, respectively, illustrating the reliability and robustness of PFM. CONCLUSION: Using citrulline for proof-of-concept, we have developed the PFM technique with tremendous potential for high-throughput quantification of amino acids and other small molecules.
    Clinica chimica acta; international journal of clinical chemistry 10/2012; DOI:10.1016/j.cca.2012.10.039 · 2.54 Impact Factor
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    ABSTRACT: BACKGROUND: Thrombopoietin (TPO) protects against heart damages by doxorubicin-induced cardiomyopathy in animal models. We aimed to investigate the therapeutic efficacy of TPO for treatment of myocardial infarction (MI) in a rat model and explored the mechanisms in terms of the genome-wide transcriptional profile, TPO downstream protein signals, and bone marrow endothelial progenitor cells (EPCs). METHODS: Sprague-Dawley rats were divided into 3 groups: Sham-operated, MI (permanent ligation of the left coronary artery) and MI+TPO. Three doses of TPO were administered weekly for 2weeks, and outcomes were assessed at 4 or 8weeks post-injury. RESULTS AND CONCLUSIONS: TPO treatment significantly improved left ventricular function, hemodynamic parameters, myocardium morphology, neovascularization and infarct size. MI damage upregulated a large cohort of gene expressions in the infarct border zone, including those functioned in cytoskeleton organization, vascular and matrix remodeling, muscle development, cell cycling and ion transport. TPO treatment significantly reversed these modulations. While phosphorylation of janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3) and protein kinase B (AKT) was modified in MI animals, TPO treatment regulated phosphorylation of STAT3 and extracellular signal-regulated kinases (ERK), and bone morphogenetic protein 1 (BMP1) protein level. TPO also increased EPC colonies in the bone marrow of MI animals. Our data showed that TPO alleviated damages of heart tissues from MI insults, possibly mediated by multi-factorial mechanisms including suppression of over-reacted ventricular remodeling, regulation of TPO downstream signals and mobilization of endothelial progenitor cells. TPO could be developed for treatment of cardiac damages.
    International journal of cardiology 07/2012; 167(6). DOI:10.1016/j.ijcard.2012.06.038 · 6.18 Impact Factor
  • Pak C Ng, Hugh S Lam
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    ABSTRACT: Over the past two decades, neonatal clinicians have commonly used host response biomarkers to diagnose and assess the severity of systemic infection. Most of these biomarkers, such as acute-phase proteins or cytokines, are non-specific immunomodulating mediators of the inflammatory cascade. With advances in biochemical/genetic research, it is anticipated that future biomarkers will be 'organ and/or disease specific'. There is also the quest for discovery of 'novel' biomarkers to assist diagnosis and prognosis of neonatal diseases using powerful mass-screening techniques, e.g. the next-generation sequencing, proteomics and arrays. This article aims to introduce the concept of the next generation of biomarkers to practising neonatal clinicians, and, hopefully, to integrate basic science research into day-to-day clinical practice in the future.
    Neonatology 06/2012; 102(2):145-51. DOI:10.1159/000338587 · 2.57 Impact Factor
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    ABSTRACT: Neonatal extracorporeal membrane oxygenation (ECMO) is not available in Hong Kong. To document the survival of neonates with symptomatic congenital diaphragmatic hernia at birth, but without access to ECMO. Twenty-two patients diagnosed to have CDH within a ten year period (1999-2009) at Prince of Wales Hospital were systematically reviewed. CDH patients who presented after the neonatal period were excluded. There were 17 neonates with symptomatic CDH at birth and the overall survival, including infants with multiple anomalies, was 14/17 (82%). 6 of 17 (35%) infants met the ECMO criteria and the survival rate for these serious cases was 4/6 (67%). Our results are comparable with centers which provide ECMO and suggest that there may be only marginal benefit for using ECMO to improve survival. A territory-wide registry for documenting risk factors and outcomes would be important, especially in light of improving neonatal intensive care and survival.
    Early human development 04/2012; 88(9):739-41. DOI:10.1016/j.earlhumdev.2012.03.002 · 2.12 Impact Factor

Publication Stats

4k Citations
878.19 Total Impact Points


  • 1995–2013
    • The Chinese University of Hong Kong
      • • Department of Paediatrics
      • • Prince of Wales Hospital
      Hong Kong, Hong Kong
    • University of London
      Londinium, England, United Kingdom
  • 1994–2013
    • Prince of Wales Hospital, Hong Kong
      Chiu-lung, Kowloon City, Hong Kong
  • 2004
    • Christian Hospital
      Сент-Луис, Michigan, United States
  • 2003
    • Princess Margaret Hospital, Hong Kong
      Hong Kong, Hong Kong