Exploring novel aspects of choline phospholipid metabolism in cancer using metabolomics

Abnormal metabolic phenotypes can be a powerful resource for drug and biomarker discoveries. In this thesis, a metabolomic approach was used to examine several aspects of tumour metabolism with potential clinical applications. In the first part, the metabolic consequences of PIK3CA mutation in MCF10A breast cells were assessed. PIK3CA mutation is oncogenic, and is important for disease progression in many breast tumours. Increased glutaminolysis, fatty acid synthesis, pyruvate entry into the TCA cycle, and decreased glycerophosphocholine (GPC) were identified to be the most prominent phenotypes following knock-in PIK3CA mutation in MCF10A cells. GPC has long been reported as a potential marker for disease progression; however, its functional role in cancer remains unclear. Glycerophosphodiester phosphodiesterase is responsible for the hydrolysis of GPC into choline and glycerol-3 phosphate (G3P), and EDI3 is a member of the glycerophosphodiester phosphodiesterase family associated with metastasis in endometrial cancer patients. Through metabolomic analysis of tumour cell models, EDI3 silencing was found to increase GPC levels and the GPC: phosphocholine ratio. Also, it was demonstrated that EDI3 had an impact on a broader spectrum of metabolic phenotypes, and effects on glycolysis and fatty acid synthesis were also observed. Finally, using 1H HR-MAS-NMR, changes in levels of choline phospholipid metabolites following Colony stimulating factor 1 receptor (CSF1R) inhibitor treatment were investigated in a mouse pancreatic tumour model. CSF1R is important for growth signalling of macrophages in tumours. Phosphocholine levels were found to be associated with disease progression and CSF1R inhibitor treatment. Collectively, these findings highlight a number of novel factors in choline phospholipid metabolism that may be important to tumourigenesis and the development of cancer biomarkers, including the role of glycerophosphodiester phosphodiesterase and macrophage-tumour interaction.Open Acces

NMR Spectroscopy of Cell Culture, Tissues, and Other Biofluids

NMR spectroscopy can provide a wealth of information on cellular metabolism and is frequently used in metabolomics application that use cultured cells, tissues, and whole organisms. Central to these analyses are the protocols for sample harvest, which incorporate procedures for quenching metabolic processes to preserve samples in a state that is representative of their source. In this chapter, the main considerations are discussed with reference to literature exemplars. In the latter half of the chapter, less commonly studied biofluids that also have specific sample preparation requirements are discussed, with a focus on cerebrospinal fluid, faeces, bile, seminal fluid, and milk.</jats:p

Syntactic skills in sentence reading comprehension among Chinese elementary school children

The present study examined the role of syntactic skills for reading comprehension in Chinese. Two hundred and seventy-two Chinese children were tested on their phonological processing, orthographic, morphological, syntactic, and literacy skills at Grades 1 and 2. Hierarchical multiple regression results showed that syntactic skills, in terms of word order, connective usage, and knowledge of morphosyntactic structure (measured by an oral cloze task) in Grade 1, significantly predicted sentence reading comprehension in Grade 2 after controlling for the children's age, IQ, and word level reading-related cognitive skills in Grade 1, and word reading in Grade 2. As in alphabetic languages, syntactic skills are essential for reading comprehension in Chinese. The unique roles of individual syntactic skills for understanding sentences in Chinese are discussed. © 2011 Springer Science+Business Media B.V.postprin

Chronic benign neutropenia among Chinese children

Objective. To delineate the clinical behaviour of chronic benign neutropenia in Chinese children in Hong Kong. Design. Retrospective study. Setting. University teaching hospital, Hong Kong. Patients. All infants and children with absolute neutrophil count of 1.5 × 109 /L or lower for more than 3 months. Main outcome measures. Development of significant infection, and achievement of remission. Results. Twenty-four children with chronic benign neutropenia were identified between 1992 and 2001. Their median age of diagnosis was 9 months. The mean (standard deviation) initial absolute neutrophil count was 0.28 × 109 /L (0.24 × 109 /L). Twenty-three patients presented with infection. Of the 19 patients tested, four (21%) were positive for anti-neutrophil antibodies. Bone marrow examination was performed in 17 patients: nine had normal results, but six showed evidence of peripheral consumption, one showed late maturation arrest at band stage, and one showed phagocytosis of myeloid cells by histiocytes. The overall hospitalised infection rate was 51.6 episodes per 1000 patient-months. Ten percent of cases were considered 'significant' infections and required hospital admission with either surgical intervention or intravenous therapy (antibiotics or fluid replacement). In the first year of diagnosis, more than 80% of patients had their lowest absolute neutrophil count (mean, 0.16 × 109 /L; standard deviation, 0.11 × 109 /L). Granulocyte-colony stimulating factor was used to treat three patients and induced transient elevation of absolute neutrophil count in all three. The projected remission rate was 55.4% at 3 years. Even for those with persistent disease, there was significant recovery in absolute neutrophil count to a mean of 0.5 × 109 /L (P<0.01). Conclusions. Patients with chronic benign neutropenia experienced a relatively benign clinical course regardless of their remission status. Only a small proportion of patients developed significant infections. A multi-centre prospective study may help identify predictive factors of remission.published_or_final_versio

Klebsiella infection in patients with thalassemia

Klebsiella infection has previously been reported in a few patients with transfusion-dependent thalassemia. The incidence and clinical spectrum of this infection in our cohort of patients were reviewed retrospectively. Among 160 patients observed for 12 years, there were 15 episodes of Klebsiella infection that occurred in 12 patients (7.5%), resulting in an incidence of 0.78 infections per 100 patient-years. The clinical spectrum included sinusitis (4 cases), intracranial infection (5 cases), septicemia (4 cases), and abscesses of the liver, lung, kidney, and parotid gland (1 case each). Three patients had recurrent infections involving different sites, 2 (16%) died of fulminant septicemia, and 3 (25%) had significant permanent neurological deficits. The antibiotic susceptibility pattern for the isolates was similar to the pattern for isolates recovered in the community. With regard to predisposing factors, iron overload and liver function derangement were found to be significant on univariate analysis (P = .046 and P = .049, respectively) but insignificant on multivariate analysis. Klebsiella infection was a serious and frequently encountered complication in our patients with transfusion-dependent thalassemia, resulting in high mortality and morbidity rates.published_or_final_versio

Prognostic implications of surrogate markers of atherosclerosis in low to intermediate risk patients with type 2 diabetes.

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Prenatal Tobacco Exposure Shortens Telomere Length in Children

Introduction: Preliminary evidence suggests a possible association between prenatal tobacco exposure and telomere length in children. This study was conducted to investigate whether maternal smoking during pregnancy was associated with telomere shortening in their children and whether prenatal and childhood exposure to environmental tobacco had any impact on this association. Methods: This is a population-representative study on the association between prenatal tobacco exposure and telomere length in children. Ninety-eight Hong Kong Chinese children aged under 15 years with prenatal tobacco exposure and 98 age- and gender-matched controls were recruited from a population health study with stratified random sampling. Results: Telomere length in children with prenatal tobacco exposure was significantly shorter than in those with no exposure (mean T/S ratio = 24.9 [SD = 8.58] in exposed vs. 28.97 [14.15] in control groups; P = 0.02). A negative dose-response relationship was observed between the T/S ratio and tobacco exposure duration: the longer the duration of maternal smoking in pregnancy, the shorter the child's telomere length. The association between the child's telomere length and prenatal tobacco exposure remained significant after considering the influence of family socioeconomic status and exposure to environmental tobacco smoke during pregnancy and childhood. Conclusions: Prenatal tobacco exposure was associated with telomere shortening in children. As this may impose significant health impacts through fetal genetic programming, more efforts should be made to reduce fetal tobacco exposure by educating pregnant women to not smoke and motivating smokers to quit in early pregnancy. Implications: As reflected by telomere shortening, prenatal tobacco exposure in children can cause premature aging and increased health risks, which we suggest is entirely preventable. Not smoking during pregnancy or quitting smoking is critical to improving the health outcome of our future generations as prenatal tobacco exposure may affect children's biological programming. © The Author 2016. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved.postprin

Cigarette Smoking Accelerated Brain Aging and Induced Pre-Alzheimer-Like Neuropathology in Rats

Cigarette smoking has been proposed as a major risk factor for aging-related pathological changes and Alzheimer's disease (AD). To date, little is known for how smoking can predispose our brains to dementia or cognitive impairment. This study aimed to investigate the cigarette smoke-induced pathological changes in brains. Male Sprague-Dawley (SD) rats were exposed to either sham air or 4% cigarette smoke 1 hour per day for 8 weeks in a ventilated smoking chamber to mimic the situation of chronic passive smoking. We found that the levels of oxidative stress were significantly increased in the hippocampus of the smoking group. Smoking also affected the synapse through reducing the expression of pre-synaptic proteins including synaptophysin and synapsin-1, while there were no changes in the expression of postsynaptic protein PSD95. Decreased levels of acetylated-tubulin and increased levels of phosphorylated-tau at 231, 205 and 404 epitopes were also observed in the hippocampus of the smoking rats. These results suggested that axonal transport machinery might be impaired, and the stability of cytoskeleton might be affected by smoking. Moreover, smoking affected amyloid precursor protein (APP) processing by increasing the production of sAPPβ and accumulation of β–amyloid peptide in the CA3 and dentate gyrus region. In summary, our data suggested that chronic cigarette smoking could induce synaptic changes and other neuropathological alterations. These changes might serve as evidence of early phases of neurodegeneration and may explain why smoking can predispose brains to AD and dementia