Publications by authors named "David Stammers"

Thromboembolism (TE) is associated with reduced survival in pediatric acute lymphoblastic leukemia (ALL). It has been hypothesized that TE might signal leukemic aggressiveness. The objective was to determine risk factors for TE during ALL induction (TE ) therapy and whether TE is associated with treatment refractoriness.

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Vitamin B12 deficiency in childhood presents with a wide variety of symptoms including anemia, failure to thrive and developmental delays. It is a diagnostic consideration in children who are exclusively breastfed or have minimal solid intake, especially if their mother is vegetarian or has underlying vitamin B12 deficiency. Infantile tremor syndrome (ITS) has been associated with vitamin B12 deficiency.

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Background: The COVID-19 pandemic has had a major impact on access to health care resources. Our objective was to estimate the impact of the COVID-19 pandemic on the incidence of childhood cancer in Canada. We also aimed to compare the proportion of patients who enrolled in clinical trials at diagnosis, presented with metastatic disease or had an early death during the first 9 months of the COVID-19 pandemic compared with previous years.

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Background: It is questionable whether enrollment on clinical trials offers any survival advantage at the population level over standard-of-care treatment. The objectives of this study were to describe the impact of trial enrollment on event-free survival and overall survival in pediatric acute myeloid leukemia (AML) using the Cancer in Young People in Canada (CYP-C) database.

Methods: Children were included if they had had AML newly diagnosed between ages birth and 14 years from 2001 to 2012.

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There is conflicting information about the epidemiology of thromboembolism (TE) in paediatric oncology. Objectives were to describe the incidence and risk factors of TE in children with cancer. We included all children with cancer less than 15 years of age diagnosed from 2001 to 2016, treated at one of the 12 Canadian paediatric centres outside of Ontario and entered into the Cancer in Young People-Canada database.

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Background: The objectives of this study were to describe the impact of trial enrollment at diagnosis on event-free and overall survival in paediatric acute lymphoblastic leukaemic (ALL) using a population-based approach.

Methods: We conducted a retrospective cohort study that included children newly diagnosed with ALL between 1 and 14 years of age. The data source was the Cancer in Young People in Canada (CYP-C) national paediatric cancer population-based database.

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Background: Primary objective was to describe the proportion of children newly diagnosed with cancer enrolled on a therapeutic clinical trial. Secondary objectives were to describe reasons for non-enrollment and factors associated with enrollment on trials.

Methods: In this retrospective cohort study, we included children newly diagnosed with cancer between 0 and 14 years of age and diagnosed from 2001 to 2012.

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Background: Venous access device (VAD) occlusion from intraluminal thrombus is a common complication during childhood cancer treatment. Current practice at many institutions is to assess VAD position with a chest X-ray (CXR) prior to intraluminal administration of tissue plasminogen activator (tPA). We aimed to determine the utility of this practice.

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Background: Health disparities between Canadian First Nation (FN) people and the rest of the national population exist. No studies have specifically documented cancer-related health outcomes in Canadian FN children. The purpose of this study was to describe the incidence of pediatric malignancies in Manitoba FN children, and to compare morbidity patterns and survival between FN and non-FN children with cancer in the Canadian province of Manitoba.

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YcbL has been annotated as either a metallo-β-lactamase or glyoxalase II (GLX2), both members of the zinc metallohydrolase superfamily, that contains many enzymes with a diverse range of activities. Here, we report crystallographic and biochemical data for Salmonella enterica serovar Typhimurium YcbL that establishes it as GLX2, which differs in certain structural and functional properties compared with previously known examples. These features include the insertion of an α-helix after residue 87 in YcbL and truncation of the C-terminal domain, which leads to the loss of some recognition determinants for the glutathione substrate.

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Background: Zhx1 to 3 (zinc-fingers and homeoboxes) form a set of paralogous genes encoding multi-domain proteins. ZHX proteins consist of two zinc fingers followed by five homeodomains. ZHXs have biological roles in cell cycle control by acting as co-repressors of the transcriptional regulator Nuclear Factor Y.

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Binding of the nuclear factor-Y complex (NF-Y) to the inverted CCAAT-box interferes with transcription activation through nucleosome reorganization. The three homologous proteins forming the zinc-fingers and homeoboxes (ZHX) family interact with the activation domain of NF-Ya to repress transcription. Each ZHX-protein contains two generic C2H2 zinc-fingers (ZNF1 and ZNF2) followed by five homeodomains.

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The structure of the MarR-family transcription factor NMB1585 from Neisseria meningitidis has been solved using data extending to a resolution of 2.1 A. Overall, the dimeric structure resembles those of other MarR proteins, with each subunit comprising a winged helix-turn-helix (wHtH) domain connected to an alpha-helical dimerization domain.

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Differential binding of dinucleotides to key regulatory proteins can modulate their interactions with other proteins and, in some cases, can signal fluctuations in the cellular redox state, to produce changes in transcription and physiological state. The dinucleotide-binding proteins human HSCARG and yeast transcription repressor Gal80p are examples that offer exciting glimpses into the potential for dinucleotide-sensing proteins to couple fluctuations in dinucleotide ratios to changes in transcription and to act as networking agents linking different classes of signaling molecules.

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Owing to the emergence of resistant virus, next generation non-nucleoside HIV reverse transcriptase inhibitors (NNRTIs) with improved drug resistance profiles have been developed to treat HIV infection. Crystal structures of HIV-1 RT complexed with benzophenones optimized for inhibition of HIV mutants that were resistant to the prototype benzophenone GF128590 indicate factors contributing to the resilience of later compounds in the series (GW4511, GW678248). Meta-substituents on the benzophenone A-ring had the designed effect of inducing better contacts with the conserved W229 while reducing aromatic stacking interactions with the highly mutable Y181 side chain, which unexpectedly adopted a "down" position.

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Amongst the most common protein motifs in eukaryotes are zinc fingers (ZFs), which, although largely known as DNA binding modules, also can have additional important regulatory roles in forming protein:protein interactions. AreA is a transcriptional activator central to nitrogen metabolism in Aspergillus nidulans. AreA contains a GATA-type ZF that has a competing dual recognition function, binding either DNA or the negative regulator NmrA.

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The selection of drug resistant virus is a significant obstacle to the continued successful treatment of HIV infection. Reverse transcriptase is the target for numerous approved anti-HIV drugs including both nucleoside inhibitor (NRTI) and non-nucleosides (NNRTI). The many available crystal structures of RT reveal that, generally, in relation to their binding sites NRTI resistance mutations are generally more distally positioned, whilst for NNRTIs mutations are clustered.

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The S. typhimurium genome encodes proteins, designated EngA and YhbZ, which have a high sequence identity with the GTPases EngA/Der and ObgE/CgtAE of Escherichia coli. The wild-type activity of the E.

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The eradication of smallpox was announced by the WHO in 1980. However, smallpox has not totally disappeared from people's minds because of its potential use as a biological weapon. Further outbreaks of smallpox would, needless to say, be devastating in a population, which has little or no immune defence against the virus.

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Dominant mutations in the ubiquitous enzyme glycyl-tRNA synthetase (GlyRS), including S581L, lead to motor nerve degeneration. We have determined crystal structures of wildtype and S581L-mutant human GlyRS. The S581L mutation is approximately 50A from the active site, and yet gives reduced aminoacylation activity.

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HIV-1 isolates harbouring an insertion in the beta3-beta4 loop of reverse transcriptase (RT) confer high-level resistance to nucleoside analogues. We have identified a novel 5-amino-acid insertion (KGSNR amino acids 66-70) in a patient on prolonged nucleoside combination therapy (didanosine and stavudine) and investigated which factors were responsible for its outgrowth. Remarkably, only small fold increases in drug resistance to nucleoside analogues were observed compared to wild type.

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The selection of drug resistant viruses is a major problem in efforts to combat HIV and AIDS, hence, new compounds are required. We report crystal structures of wild-type and mutant HIV-1 RT with bound non-nucleoside (NNRTI) GW420867X, aimed at investigating the basis for its high potency and improved drug resistance profile compared to the first-generation drug nevirapine. GW420867X occupies a smaller volume than many NNRTIs, yet accesses key regions of the binding pocket.

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