There is a continued interest in the properties of arsenic thiolate compounds for both industrial and biological uses. Recent discoveries in the medicinal properties of such compounds have resulted in a sustained need for the synthesis of new dithiarsolane compounds for research as anti-leukemic compounds. Close analogues of the 2-halo arsenic dithiolates, namely those with an arsenic-carbon bond instead of an arsenic-halide bond, have recently been shown to have some efficacy towards leukemia cells. Based on the hydrolytic character and the active role of glutathione with arsenic in vivo, the compounds reported here may also have such activity. Arsenic compounds have demonstrated biological activity in the literature, thus the hypothesis of this thesis is cyclized arsenic thiolates can be synthesized with the appropriate characteristics as to be potentially useful medicinal agents as well as provide new structural and reaction information. A series of arsenic and antimony di- and trithiolates has been synthesized and characterized. Those compounds include 2-chloro-1,3,2-dithiarsolane, 2-bromo- 1,3,2-dithiarsolane, 2-iodo-1,3,2-dithiarsolane, 2-chloro-1,3,2-dithiarsenane, 2-bromo- 1,3,2-dithiarsenane, 2-iodo-1,3,2-dithiarsenane, 3-chloro-4H,7H-5,6-benz-1,3,2- dithiarsepine, 2-chloro-benzo-1,3,2-dithiarsole, 1,2-bis-dithiarsolan-2-ylmercapto-ethane, tris-(pentafluorophenylthio)-arsen, bis(2-(1,3,2-benzodithiarsol-2ylsulfanyl)- benzenesulfide), 2-chloro-benzo-1,3,2-dithiastibole, and bis(2-(1,3,2-benzodithistibol)- 1,2-benzenedithiol. Elucidation of the pH characteristics of arsenic dithiolates within the human toxicity reaction pathway is an area of interest. It has been shown that the aqueous arsenic dithiolate stability depends on the size of the ring. 2-Chloro-1,3,2-dithiarsolane has been shown to be somewhat stable at both low and high pH as well as neutral pH. 1,2-bis- Dithiarsolan-2-ylmercapto-ethane is completely stable in a neutral aqueous solution. Glutathione does not permanently bind to arsenic even in overwhelming excess. In particular, these fully characterized compounds determine how reactive the AsS and AsCl linkages are under environmental and biological conditions, and provide a source of new reagents to examine in medical applications. Future applications may include the incorporation of the reported compounds in filtration and remediation technologies with further modification.

The occurrence of psychological late effects resulting from the diagnosis and treatment of pediatric acute lymphoblastic leukemia (ALL) been the subject of empirical investigations for approximately 25 years, with an emphasis on those patients treated with radiation therapy. In more recent years, however, research has shown that children and adolescents with ALL treated only with chemotherapy may also be at risk for treatment-related cognitive and academic deficits, although many specific treatment regimens remain to be investigated. Purpose: The present investigation was designed to examine 76 pediatric patients with ALL who were randomized to receive 1g/m² or 2g/m² of intravenous methotrexate (IVMTX) with regard to cognitive, academic, and social-emotional/behavioral functioning over a 3-year period beginning shortly after diagnosis. Method: Scores from a preexisting database were analyzed with particular interest in main effects for methotrexate dose level, time since diagnosis, age at diagnosis, ALL vs non-ALL status and interactions between group and time variables. Participants with ALL and group of non-ALL siblings had participated in cognitive evaluations measuring performance in the following domains: intelligence, language, visual-spatial/visual-motor skills, attention and working memory, processing speed, psychomotor speed and coordination, executive function, academic achievement, and social-emotional/behavioral functioning. Results: A main effect for methotrexate dose level was significant for a measure of adaptive skills. A main effect for age at diagnosis was noted on measures of visual-spatial attention and working memory, and spelling and written expression. No main effect for time was noted on any dependent measure. Additionally, no main effect for ALL versus non-ALL status was noted on any dependent measure. Conclusion: Overall the findings suggest that the treatment of ALL with 1g/m² or 2g/m² IVMTX does not significantly impact the incidence of late effects with regard to cognitive, academic, and social-emotional/behavioral functioning within the first 3 years post-diagnosis. Younger age at diagnosis may, however, contribute to differences in performance on measures of cognitive and academic functioning.

Obesity is a recognized problem for children treated for acute lymphoblastic leukemia (ALL) and is present in roughly one fourth of children by the end of therapy. Obesity may lead to immediate health threats, such as an increased risk for cancer relapse, or may cause future heath issues such as diabetes, metabolic syndrome, hypertension, additional cancers, depression or cardiovascular disease. The purpose of this study was to determine if weight gain during two individual cycles of therapy (Induction or Delayed Intensification Cycle 1) were predictive of obesity (defined as body mass index ≥ 95th percentile for age and gender) at the end of treatment. This study retrospectively examined height and weight data from 1,017 childhood leukemia patients treated on Children's Oncology Group (COG) protocol number 1961. This study included patients that had fully completed therapy on protocol 1961 and who were between the ages of 2-20 years. Percentiles and z-scores for age and gender specific body mass index (BMI) were calculated using the height and weight measurements obtained at the beginning of each cycle of chemotherapy. Univariate and multivariate logistic regression analyses were performed. BMI z-score at the beginning of therapy and difference in BMI z-score during Induction were significant predictors (p<0.0001) of BMI ≥ 95th percentile at the end of maintenance in both males and females. A one unit increase in the difference of BMI z-score during Induction resulted in a 3.03 odds ratio (OR) for obesity at the end of therapy for males (95% CI, 1.90 to 4.84) and a 4.15 OR for females (95% CI, 2.32 to 7.43). The change in BMI z-score during Delayed Intensification I was not found to be significant in relationship to obesity at the end of therapy. Weight gain during Induction consisted of ≥ 20% increase in weight for 3.9% of the study participants. Weight gain during Induction therapy of childhood ALL treatment may be useful in predicting patients at increased risk for obesity development during therapy. Early identification of these at risk patients can assist with interventions aimed at normalizing weight gain during therapy.

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Telomeres are regions of tandem repeats at the ends of chromosomes ensuring chromosome stability or inducing replicative senescence when critically short. Telomerase extends telomeres and its catalytic subunit, telomerase reverse transcriptase is tightly regulated at multiple levels. Cancerous cells prevent telomere-mediated senescence to attain unlimited proliferation, in most cases by enhancing telomerase activity. Chronic myeloid leukaemia is characterised by the translocation, t(9;22), in haematopoietic stem cells. The resulting fusion protein exhibits constitutive tyrosine kinase activity in the cytoplasm, promoting cellular proliferation, inhibiting apoptosis and impeding cell adhesion. Changes in telomere biology have been observed in chronic myeloid leukaemic cells. The current study aimed to investigate telomere biology in 18 chronic myeloid leukaemia patients at various time intervals from date of diagnosis. Although telomeres were significantly shorter in patients compared to controls, results point to complex telomere dynamics in the malignancy. Increased telomerase activity did not necessarily accompany telomere lengthening and increased transcription of the telomerase catalytic subunit was not necessarily indicative of telomerase activity. Ultimately the current study could not detect any trends between telomere length, telomerase activity and telomerase catalytic subunit expression in chronic myeloid leukaemia patients. Together with inherent patient-to-patient variation and the high cost per assay, measurement of telomere biology does not appear to hold prognostic value in chronic myeloid leukaemia and does not warrant inclusion into a routine test repertoire.

INTRODUCTION: Despite best current therapy, acute lymphoblastic leukemia (ALL) still remains the most common cause of cancer-related death in children and young adults. Relapse is the main reason for treatment failure in ALL patients and occurs in 15-20% of these patients. Current risk stratification criteria have not been sufficient to predict relapse in ALL patients. The Philadelphia (Ph) chromosome is a chromosomal abnormality found in a subset of high risk ALL patients and is associated with a poor prognosis. Recent genome-wide studies have identified focal deletions of the Ikaros gene (IKZF1) in 70-80% of B-cell ALL patients that have the Philadelphia (Ph) chromosome. Subsequent studies have also found a strong correlation between IKZF1 deletions and ALL patients (Ph+ and Ph-) that relapse. IKZF1 is required for normal lymphoid development and loss of IKZF1 results in haploidinsufficiency or the overexpression of dominant negative IKZF1 isoforms, in particular Ik6 in high risk ALL patients. Most studies used DNA microarrays to detect IKZF1 deletions. Multiplex ligation probe dependent amplification (MLPA) is a low cost, rapid technique that can detect small DNA copy number changes of up to 50 targets in a single reaction and is not as technically challenging to analyse as arrays. MLPA has also been suggested to be used as an alternative to array based techniques in developing countries. METHODS: There were 31 ALL (paediatric and adult) patients that were tested using MLPA and 24 ALL patients tested using reverse transcriptase PCR (RT-PCR) to detect IKZF1 copy number changes and IKZF1 isoform expression pattern respectively. RT-PCR was validated with DNA sequencing and MLPA was validated with Fluorescent in situ hybridization (FISH). MLPA was also compared to cytogenetics in certain cases. RESULTS: MLPA detected 156 copy number changes (7.1 aberrations per sample) in 22 leukemic patients. IKZF1 deletions accounted for the majority of the aberrations (41%) and were detected in 53% of Ph+ ALL patients (n=15) by MLPA. IKZF1 deletions were detected at presentation and relapse in Ph+ and Ph- ALL patients. IKZF1 isoform Ik6 was detected in 70% of Ph+ and relapsed ALL patients after performing RT-PCR. IKZF1 deletions of exons 4-7 resulted in exclusive expression of Ik6. MLPA results were also correlated with certain aneuploidies detected with cytogenetics. CONCLUSION: This study showed that IKZF1 deletions could have assisted with prognosis in certain ALL cases and thus, newly diagnosed ALL patients should be screened for IKZF1 deletions. MLPA proved to be a reliable, rapid and cost effective technique to detect small copy number changes in multiple genes and should be implemented as a diagnostic test to detect IKZF1 deletions.

by Chan Shuk Chong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 135-142). / Statement --- p.i / Acknowledgment --- p.ii / Abbreviations --- p.iii / Abstract --- p.iv / Chapter Chapter 1: --- General Introduction / Chapter 1.1 --- Haematopoiesis --- p.1 / Chapter 1.1.1 --- Sites of haematopoiesis / Chapter 1.1.1.1 --- Bone marrow stroma / Chapter 1.1.1.2 --- Thymus / Chapter 1.1.1.3 --- Spleen and lymph node / Chapter 1.1.1.3.1 --- Spleen / Chapter 1.1.1.3.2 --- Lymph Nodes / Chapter 1.1.2 --- Blood Cell / Chapter 1.1.2.1 --- Development of T and B cells / Chapter 1.1.2.1.1 --- T cells / Chapter 1.1.2.1.2 --- B cells / Chapter 1.1.2.2 --- Development of Granulocytes and monocytes / Chapter 1.2 --- White Cell Disorder -Leukemia --- p.13 / Chapter 1.2.1 --- Leukemia - general concept / Chapter 1.2.1.1 --- Classification of leukemia / Chapter 1.2.1.2 --- Pathophysiology and Clinical features / Chapter 1.2.1.3 --- Etiology of myeloid leukemia / Chapter 1.2.2 --- Genetic basis of leukemia / Chapter 1.3 --- Acute myeloid leukemia (AML) cell model --- p.19 / Chapter 1.3.1 --- Cell Model for human acute myeloid leukemia / Chapter 1.3.2 --- Murine leukemia cell lines / Chapter 1.4 --- Induction of leukemia cell differentiation --- p.21 / Chapter 1.4.1 --- Overview of different inducers / Chapter 1.4.2 --- Cytokines as Inducers / Chapter 1.5 --- Objectives and Research Strategy --- p.26 / Chapter 1.5.1 --- Objectives / Chapter 1.5.2 --- Research strategy / Chapter Chapter 2 : --- Materials and Methods / Chapter 2.1 --- Materials --- p.29 / Chapter 2.1.1 --- Cell line / Chapter 2.1.2 --- Tissue culture medium / Chapter 2.1.3 --- Tumor necrosis Factor - alpha (TNF-α) / Chapter 2.1.4 --- Interleukin 1- alpha (IL-lα)and Interleukin 1- beta (IL-1β) / Chapter 2.1.5 --- "Monoclonal hamster anti-mouse IL-lα monoclonal hamster anti-mouse IL-1β, and Polyclonal rabbit anti-mouse TNF-α antibodies" / Chapter 2.1.6 --- Lipopolysaccharides (LPS) / Chapter 2.1.7 --- Buffers and solutions / Chapter 2.2 --- Methods : --- p.33 / Chapter 2.2.1 --- Cell culture / Chapter 2.2.2 --- Cytotoxicity assay / Chapter 2.2.3 --- Proliferation assay / Chapter 2.2.4 --- Cell morphology / Chapter 2.2.5 --- Phagocytosis assay / Chapter 2.2.6 --- Preparation of undifferentiated and differentiated murine leukemia WEHI3B (JCS) cells for cell lysate / Chapter 2.2.7 --- Isolation of total cellular RNA / Chapter 2.2.8 --- Extraction of the total RNA / Chapter 2.2.9 --- Spectrophotometry / Chapter 2.2.10 --- Electrophoresis of RNA in agarose gel containing formaldehyde / Chapter 2 2.11 --- First strand cDNA synthesis / Chapter 2.2.12 --- Cytokines phenotyping of the uninduced and induced WEHI 3B (JCS) by The Reverse Trancription Polymerase Chain Reaction method / Chapter 2.2.13 --- Gel electrophoresis of PCR- product / Chapter 2.2.14 --- Southern blot / Chapter 2.2.15 --- Dot blot / Chapter 2.2.16 --- Hybridization with oligonucleotides / Chapter 2.2.17 --- Chemiluminescent detection / Chapter Chapter 3 : --- Growth Inhibitory and Differentiation Effects of Lipopolysaccharides ( LPS ) on WEHI 3B (JCS) cells / Chapter 3.1 --- Introduction --- p.51 / Chapter 3.1.1 --- Chemical structure of LPS / Chapter 3.1.2 --- Biological activity of LPS / Chapter 3.2 --- Results --- p.55 / Chapter 3.2.1 --- Anti-proliferative effects of LPS / Chapter 3.2.2 --- Differentiation inducing effect of LPS on WEHI 3B (JCS) cells / Chapter 3.2.3 --- Phagocytic activity LPS treated WEHI 3B (JCS) cells / Chapter 3.2.4 --- Anti-proliferative effect of TNF-α / Chapter 3.2.5 --- Differentiation inducing effect of TNF-α / Chapter 3.2.6 --- Phagocytic activity of TNF-α treated WEHI3B (JCS) cells / Chapter 3.3 --- Discussion --- p.67 / Chapter 3.4 --- Summary --- p.69 / Chapter Chapter 4 : --- The Cytokine Genes Expression of the TNF-α and LPS Treated WEHI 3B (JCS) cells / Chapter 4.1 --- Introduction --- p.70 / Chapter 4.1.1 --- Differentiation of leukemia cell line / Chapter 4.1.2 --- Study of the cytokine genes expression of WEHI 3B (JCS) cells / Chapter 4.2 --- Results --- p.72 / Chapter 4.2.1 --- Isolation of total RNA from uniduced and induced WEHI 3B (JCS) cells / Chapter 4.2.2 --- The cytokine genes expression during differentiation / Chapter 4.2.2.1 --- "Up-regulation of IL-lα, IL-1β,TNF-α and IFN-γ in both TNF-α induced and LPS induced WEHI 3B (JCS) cells" / Chapter 4.2.2.1.1 --- Southern blot / Chapter 4.2.2.1.2 --- Semi-quantitation of PCR-products by gel electrophoresis and dot-blot hybridization / Chapter 4.2.2.2 --- up-regulation of GM-CSF and G-CSF in LPS induced WEHI 3B (JCS) cells / Chapter 4.3 --- Discussion --- p.92 / Chapter 4.4 --- Summary --- p.95 / Chapter Chapter 5 : --- Growth inhibitory and Differentiation Inducing Effect of IL-l( IL-1α and IL-1β) on WEHI 3B (JCS) cells / Chapter 5.1 --- Introduction --- p.96 / Chapter 5.1.1 --- The interleukin 1 (IL-1) family / Chapter 5.1.1.1 --- Structure of IL-1 / Chapter 5.1.1.2 --- The biological function of IL-1 / Chapter 5.1.2 --- Tumor necrosis factor - alpha ( TNF-α) / Chapter 5.1.2.1 --- Structure of TNF-α / Chapter 5.1.2.2 --- Biological functions of TNF-α / Chapter 5.1.3 --- The similarity between TNF and IL-1 / Chapter 5.2 --- Results --- p.102 / Chapter 5.2.1 --- Anti-proliferative effect of IL-1 / Chapter 5.2.2 --- Differentiation inducing effect of IL-1 / Chapter 5.2.3 --- Phagocytic activity of IL-1 treated JCS cells / Chapter 5.2.4 --- "Role of endogenously produced IL-lα, IL-1β and TNF-α in LPS cytokines differentiation of WEHI 3B (JCS) cells" / Chapter 5.2.4.1. --- "Effect of neutralizing anti- ILl-α,anti - IL-l-β, and anti-TNF-α antibodies on the growth inihbition of the treated WEHI 3B (JCS) cells" / Chapter 5.2.4.2 --- "Effects of neutralizing anti-IL-lα, anti- IL-1β, and anti-TNF-α antibodies on differentiation of the treated WEHI 3B (JCS) cells" / Chapter 5.3 --- Discussion --- p.124 / Chapter 5.4 --- Summary --- p.127 / Chapter Chapter 6 --- : Concluding Discussion --- p.128 / References --- p.135

The replication of Moloney Murine Leukemia Virus (MoMLV or MLV) is restricted in mouse embryonic stem (ES) and embryonic carcinoma (EC) cells, but not in differentiated cells. The restriction is mediated by the primer binding site (PBS) of proviral DNA of MLV. A restriction complex can bind to the PBS of MLV and block the transcription of viral genes. Two major components of the PBS-mediated silencing complex were identified in our lab, ZFP809 and Trim28. ZFP809 contains two conserved domains, a zinc finger domain responsible for DNA binding and a KRAB box recruiting Trim28, and hence other transcription repressors, such as HP1γ and ESET. A protein called L1td1 was identified during the purification of PBS-mediated restriction complex. L1td1 is a stem cell specific protein but little is known about the function of L1td1. In differentiated cells, the replication of MLV is not restricted. Overexpression of ZFP809 in differentiated cells is sufficient to re-establish the PBS mediated restriction. However, data from various expression libraries shows that the mRNA levels of ZFP809 in stem cells and differentiated cells are approximately the same, which indicating that there is some post-transcriptional mechanism negatively regulating the protein levels of ZFP809 in differentiated cells. To study the post-translational regulation of ZFP809 may help us understand how retroviral restriction is regulated in different cell types. Here we found that the down-regulation of ZFP809 proteins is due to the rapid degradation of protein but not on mRNA. The protein of ZFP809 is degraded rapidly in differentiated cells but not in stem cells. The last 50 amino acids, as well as the lysine residue within the peptide, are important for the turnover of ZFP809 protein in differentiated cells. The drug MG132 can stabilize the ZFP809 protein in differentiated and in vivo ubiquitination assay show that ZFP809 is heavily ubiquinated in differentiated cells, suggesting that ZFP809 is degraded through the ubiquitin-dependent proteasomal pathway. Interestingly, the protein Trim28, which is an essential factor for in the silencing complex, can promote the degradation of ZFP809. Mutations with the lysine residue mutated to alanine or abolished the interaction between Trim28 are less ubiquitinated. A small drug, MLN4924, which is the neddylation inhibitor, stabilizes ZFP809 in differentiated cells. Overall, these observations suggest that, during the differentiation of mouse stem cells, ZFP809 protein is eliminated by the proteasomal system, which leads to the loss of restriction of MLV in differentiated cells. In addition, we studied the role of L1td1 in retroviral silencing. Knockdown or knockout of L1td1 partially relieves the restriction of MLV replication. Immunoprecipitation and pulldown assays show that L1td1 might interact with Trim28 and ZFP809 bridging by Trim28. In summary, L1td1 might interact with the essential factors of silencing complex and help the silencing of MLV in stem cells. Proteins of the nucleosome remodeling deacetylase (NuRD) complex were also identified during purification of the restriction. The NuRD complex is shown to be involved in the transcriptional repression. However, depletion of single subunits of the NuRD complex does not affect the PBS-mediated retroviral restriction in mouse EC cells.