Catalogue Search | MBRL
Search Results Heading
Explore the vast range of titles available.
MBRLSearchResults
-
DisciplineDiscipline
-
Is Peer ReviewedIs Peer Reviewed
-
Item TypeItem Type
-
SubjectSubject
-
YearFrom:-To:
-
More FiltersMore FiltersSourceLanguage
Done
Filters
Reset
13
result(s) for
"Backstrom, Ian"
Sort by:
Genome-wide tandem repeat expansions contribute to schizophrenia risk
by
Yuen, Ryan K. C
,
Scherer, Stephen W
,
Thiruvahindrapuram, Bhooma
in
Disease
,
Exons
,
Genetic diversity
2022
Tandem repeat expansions (TREs) can cause neurological diseases but their impact in schizophrenia is unclear. Here we analyzed genome sequences of adults with schizophrenia and found that they have a higher burden of TREs that are near exons and rare in the general population, compared with non-psychiatric controls. These TREs are disproportionately found at loci known to be associated with schizophrenia from genome-wide association studies, in individuals with clinically-relevant genetic variants at other schizophrenia loci, and in families where multiple individuals have schizophrenia. We showed that rare TREs in schizophrenia may impact synaptic functions by disrupting the splicing process of their associated genes in a loss-of-function manner. Our findings support the involvement of genome-wide rare TREs in the polygenic nature of schizophrenia.
Journal Article
Nanoscale Reaction Vessels Designed for Synthesis of Copper-Drug Complexes Suitable for Preclinical Development
by
Malhotra, Armaan
,
Anantha, Malathi
,
Leung, Ada
in
Alcoholism
,
Alzheimer's disease
,
Alzheimers disease
2016
The development of copper-drug complexes (CDCs) is hindered due to their very poor aqueous solubility. Diethyldithiocarbamate (DDC) is the primary metabolite of disulfiram, an approved drug for alcoholism that is being repurposed for cancer. The anticancer activity of DDC is dependent on complexation with copper to form copper bis-diethyldithiocarbamate (Cu(DDC)2), a highly insoluble complex that has not been possible to develop for indications requiring parenteral administration. We have resolved this issue by synthesizing Cu(DDC)2 inside liposomes. DDC crosses the liposomal lipid bilayer, reacting with the entrapped copper; a reaction that can be observed through a colour change as the solution goes from a light blue to dark brown. This method is successfully applied to other CDCs including the anti-parasitic drug clioquinol, the natural product quercetin and the novel targeted agent CX-5461. Our method provides a simple, transformative solution enabling, for the first time, the development of CDCs as viable candidate anticancer drugs; drugs that would represent a brand new class of therapeutics for cancer patients.
Journal Article
Impact of Commercial Strain Use on Saccharomyces cerevisiae Population Structure and Dynamics in Pinot Noir Vineyards and Spontaneous Fermentations of a Canadian Winery
by
Martiniuk, Jonathan T.
,
Backstrom, Ian
,
Measday, Vivien
in
Baking yeast
,
Bioinformatics
,
Biology and Life Sciences
2016
Wine is produced by one of two methods: inoculated fermentation, where a commercially-produced, single Saccharomyces cerevisiae (S. cerevisiae) yeast strain is used; or the traditional spontaneous fermentation, where yeast present on grape and winery surfaces carry out the fermentative process. Spontaneous fermentations are characterized by a diverse succession of yeast, ending with one or multiple strains of S. cerevisiae dominating the fermentation. In wineries using both fermentation methods, commercial strains may dominate spontaneous fermentations. We elucidate the impact of the winery environment and commercial strain use on S. cerevisiae population structure in spontaneous fermentations over two vintages by comparing S. cerevisiae populations in aseptically fermented grapes from a Canadian Pinot Noir vineyard to S. cerevisiae populations in winery-conducted fermentations of grapes from the same vineyard. We also characterize the vineyard-associated S. cerevisiae populations in two other geographically separate Pinot Noir vineyards farmed by the same winery. Winery fermentations were not dominated by commercial strains, but by a diverse number of strains with genotypes similar to commercial strains, suggesting that a population of S. cerevisiae derived from commercial strains is resident in the winery. Commercial and commercial-related yeast were also identified in the three vineyards examined, although at a lower frequency. There is low genetic differentiation and S. cerevisiae population structure between vineyards and between the vineyard and winery that persisted over both vintages, indicating commercial yeast are a driver of S. cerevisiae population structure. We also have evidence of distinct and persistent populations of winery and vineyard-associated S. cerevisiae populations unrelated to commercial strains. This study is the first to characterize S. cerevisiae populations in Canadian vineyards.
Journal Article
Genome sequencing broadens the range of contributing variants with clinical implications in schizophrenia
2021
The range of genetic variation with potential clinical implications in schizophrenia, beyond rare copy number variants (CNVs), remains uncertain. We therefore analyzed genome sequencing data for 259 unrelated adults with schizophrenia from a well-characterized community-based cohort previously examined with chromosomal microarray for CNVs (none with 22q11.2 deletions). We analyzed these genomes for rare high-impact variants considered causal for neurodevelopmental disorders, including single-nucleotide variants (SNVs) and small insertions/deletions (indels), for potential clinical relevance based on findings for neurodevelopmental disorders. Also, we investigated a novel variant type, tandem repeat expansions (TREs), in 45 loci known to be associated with monogenic neurological diseases. We found several of these variants in this schizophrenia population suggesting that these variants have a wider clinical spectrum than previously thought. In addition to known pathogenic CNVs, we identified 11 (4.3%) individuals with clinically relevant SNVs/indels in genes converging on schizophrenia-relevant pathways. Clinical yield was significantly enriched in females and in those with broadly defined learning/intellectual disabilities. Genome analyses also identified variants with potential clinical implications, including TREs (one in DMPK; two in ATXN8OS) and ultra-rare loss-of-function SNVs in ZMYM2 (a novel candidate gene for schizophrenia). Of the 233 individuals with no pathogenic CNVs, we identified rare high-impact variants (i.e., clinically relevant or with potential clinical implications) for 14 individuals (6.0%); some had multiple rare high-impact variants. Mean schizophrenia polygenic risk score was similar between individuals with and without clinically relevant rare genetic variation; common variants were not sufficient for clinical application. These findings broaden the individual and global picture of clinically relevant genetic risk in schizophrenia, and suggest the potential translational value of genome sequencing as a single genetic technology for schizophrenia.
Journal Article
Combined Use of Gene Expression Modeling and siRNA Screening Identifies Genes and Pathways Which Enhance the Activity of Cisplatin When Added at No Effect Levels to Non-Small Cell Lung Cancer Cells In Vitro
by
Qadir, Mohammed A.
,
Segovia, Romulo
,
Backstrom, Ian
in
Analysis
,
Antineoplastic Agents - chemistry
,
Apoptosis
2016
Platinum-based combination chemotherapy is the standard treatment for advanced non-small cell lung cancer (NSCLC). While cisplatin is effective, its use is not curative and resistance often emerges. As a consequence of microenvironmental heterogeneity, many tumour cells are exposed to sub-lethal doses of cisplatin. Further, genomic heterogeneity and unique tumor cell sub-populations with reduced sensitivities to cisplatin play a role in its effectiveness within a site of tumor growth. Being exposed to sub-lethal doses will induce changes in gene expression that contribute to the tumour cell's ability to survive and eventually contribute to the selective pressures leading to cisplatin resistance. Such changes in gene expression, therefore, may contribute to cytoprotective mechanisms. Here, we report on studies designed to uncover how tumour cells respond to sub-lethal doses of cisplatin. A microarray study revealed changes in gene expressions that occurred when A549 cells were exposed to a no-observed-effect level (NOEL) of cisplatin (e.g. the IC10). These data were integrated with results from a genome-wide siRNA screen looking for novel therapeutic targets that when inhibited transformed a NOEL of cisplatin into one that induced significant increases in lethality. Pathway analyses were performed to identify pathways that could be targeted to enhance cisplatin activity. We found that over 100 genes were differentially expressed when A549 cells were exposed to a NOEL of cisplatin. Pathways associated with apoptosis and DNA repair were activated. The siRNA screen revealed the importance of the hedgehog, cell cycle regulation, and insulin action pathways in A549 cell survival and response to cisplatin treatment. Results from both datasets suggest that RRM2B, CABYR, ALDH3A1, and FHL2 could be further explored as cisplatin-enhancing gene targets. Finally, pathways involved in repairing double-strand DNA breaks and INO80 chromatin remodeling were enriched in both datasets, warranting further research into combinations of cisplatin and therapeutics targeting these pathways.
Journal Article
Genome-wide detection of tandem DNA repeats that are expanded in autism
2020
Tandem DNA repeats vary in the size and sequence of each unit (motif). When expanded, these tandem DNA repeats have been associated with more than 40 monogenic disorders
1
. Their involvement in disorders with complex genetics is largely unknown, as is the extent of their heterogeneity. Here we investigated the genome-wide characteristics of tandem repeats that had motifs with a length of 2–20 base pairs in 17,231 genomes of families containing individuals with autism spectrum disorder (ASD)
2
,
3
and population control individuals
4
. We found extensive polymorphism in the size and sequence of motifs. Many of the tandem repeat loci that we detected correlated with cytogenetic fragile sites. At 2,588 loci, gene-associated expansions of tandem repeats that were rare among population control individuals were significantly more prevalent among individuals with ASD than their siblings without ASD, particularly in exons and near splice junctions, and in genes related to the development of the nervous system and cardiovascular system or muscle. Rare tandem repeat expansions had a prevalence of 23.3% in children with ASD compared with 20.7% in children without ASD, which suggests that tandem repeat expansions make a collective contribution to the risk of ASD of 2.6%. These rare tandem repeat expansions included previously undescribed ASD-linked expansions in
DMPK
and
FXN
, which are associated with neuromuscular conditions, and in previously unknown loci such as
FGF14
and
CACNB1
. Rare tandem repeat expansions were associated with lower IQ and adaptive ability. Our results show that tandem DNA repeat expansions contribute strongly to the genetic aetiology and phenotypic complexity of ASD.
Genome-wide analysis of tandem DNA repeats in the genomes of individuals with autism spectrum disorder and control participants reveals a strong contribution of tandem repeat expansions to the genetic aetiology and phenotypic complexity of autism spectrum disorder.
Journal Article
Rare tandem repeat expansions associate with genes involved in synaptic and neuronal signaling functions in schizophrenia
2023
Tandem repeat expansions (TREs) are associated with over 60 monogenic disorders and have recently been implicated in complex disorders such as cancer and autism spectrum disorder. The role of TREs in schizophrenia is now emerging. In this study, we have performed a genome-wide investigation of TREs in schizophrenia. Using genome sequence data from 1154 Swedish schizophrenia cases and 934 ancestry-matched population controls, we have detected genome-wide rare (<0.1% population frequency) TREs that have motifs with a length of 2–20 base pairs. We find that the proportion of individuals carrying rare TREs is significantly higher in the schizophrenia group. There is a significantly higher burden of rare TREs in schizophrenia cases than in controls in genic regions, particularly in postsynaptic genes, in genes overlapping brain expression quantitative trait loci, and in brain-expressed genes that are differentially expressed between schizophrenia cases and controls. We demonstrate that TRE-associated genes are more constrained and primarily impact synaptic and neuronal signaling functions. These results have been replicated in an independent Canadian sample that consisted of 252 schizophrenia cases of European ancestry and 222 ancestry-matched controls. Our results support the involvement of rare TREs in schizophrenia etiology.
Journal Article
Genome-wide detection of tandem DNA repeats expanded in autism
2020
Tandem DNA repeats vary by the size and sequence of each unit (motif). When expanded, they have been associated with >40 monogenic disorders1. Their involvement in complex disorders is largely unknown, as is the extent of their heterogeneity. Here, we interrogated genome-wide characteristics of tandem repeats with 2-20 bp motifs in 17,231 genomes of families with autism2,3 and population controls4. We found extensive polymorphism in motif size and sequence. Many correlated with cytogenetic fragile sites. At 2,588 loci, gene-associated tandem repeat expansions that were rare among population controls were significantly more prevalent among individuals with autism than their unaffected siblings, particularly in exons and near splice junctions and in genes related to nervous system development and cardiovascular system or muscle. Rare tandem repeat expansions had a prevalence of 23.3% in autism-affected children versus 20.7% in unaffected children, suggesting a collective contribution to autism risk of 2.6%. They included novel autism-linked tandem repeat expansions in DMPK and FXN, known for neuromuscular conditions, and in novel loci such as FGF14 and CACNB1. These were associated with lower IQ and adaptive ability. Our results revealed a strong contribution of tandem DNA repeat expansions to the genetic etiology and phenotypic complexity of autism.
Journal Article
Combined Use of Gene Expression Modeling and siRNA Screening Identifies Genes and Pathways Which Enhance the Activity of Cisplatin When Added at No Effect Levels to Non-Small Cell Lung Cancer Cells In Vitro: e0150675
2016
Platinum-based combination chemotherapy is the standard treatment for advanced non-small cell lung cancer (NSCLC). While cisplatin is effective, its use is not curative and resistance often emerges. As a consequence of microenvironmental heterogeneity, many tumour cells are exposed to sub-lethal doses of cisplatin. Further, genomic heterogeneity and unique tumor cell sub-populations with reduced sensitivities to cisplatin play a role in its effectiveness within a site of tumor growth. Being exposed to sub-lethal doses will induce changes in gene expression that contribute to the tumour cell's ability to survive and eventually contribute to the selective pressures leading to cisplatin resistance. Such changes in gene expression, therefore, may contribute to cytoprotective mechanisms. Here, we report on studies designed to uncover how tumour cells respond to sub-lethal doses of cisplatin. A microarray study revealed changes in gene expressions that occurred when A549 cells were exposed to a no-observed-effect level (NOEL) of cisplatin (e.g. the IC10). These data were integrated with results from a genome-wide siRNA screen looking for novel therapeutic targets that when inhibited transformed a NOEL of cisplatin into one that induced significant increases in lethality. Pathway analyses were performed to identify pathways that could be targeted to enhance cisplatin activity. We found that over 100 genes were differentially expressed when A549 cells were exposed to a NOEL of cisplatin. Pathways associated with apoptosis and DNA repair were activated. The siRNA screen revealed the importance of the hedgehog, cell cycle regulation, and insulin action pathways in A549 cell survival and response to cisplatin treatment. Results from both datasets suggest that RRM2B, CABYR, ALDH3A1, and FHL2 could be further explored as cisplatin-enhancing gene targets. Finally, pathways involved in repairing double-strand DNA breaks and INO80 chromatin remodeling were enriched in both datasets, warranting further research into combinations of cisplatin and therapeutics targeting these pathways.
Journal Article
Pediatric obesity and traumatic lower extremity long bone fracture outcomes
by
Backstrom, Ian C
in
Medicine
2011
Background. Pediatric obesity is associated with lower extremity injuries and poor outcomes after blunt trauma. Our aim was to determine if obese pediatric patients with femur and tibia fractures have more severe injury patterns and worse outcomes compared to non-obese patients. Methods. We performed a retrospective cohort study of obese and non-obese pediatric patients with femur or tibia fractures treated at two Level-1 trauma centers from 2004–2010. Patients weighing ≥ 95th percentile for age and gender were classified as obese. Patients were compared regarding demographics, Injury Severity Score (ISS), intra-abdominal, and orthopedic injuries. Outcomes included fracture treatment, orthopedic complications, ICU and hospital length of stay, ventilator days, and mortality. Results. Of the 356 patients included in the study, 78 (21.9%) were obese and 278 (78.1%) were non-obese. Obese patients were older (9.9±3.7 vs. 8.8±3.9 years; p=0.0162), had a higher ISS (20.8±13.4 vs. 14.5±10.8; p=0.0002), and sustained more intra-abdominal solid organ (24.4% vs.13.5%; p=0.0200) and hollow viscus (3.9% vs. 0.0%; p=0.0105) injuries. They had more pelvic fractures (15.4% vs. 6.9%; p=0.0196), bilateral tibia fractures (8.0% vs. 0.0%; p=0.0332), and operatively-treated femur fractures (89.9% vs. 79.1%; p=0.0484). Adjusting for age, obese patients were more likely to be admitted to the ICU [relative risk (RR), 1.68; 95% confidence interval (CI), 1.10–2.55] and die in the hospital (RR, 3.45; 95% CI, 1.14–10.41). Adjusting for ISS, these associations were non-significant. Conclusions. Obese patients with femur and tibia fractures have more severe injuries which may predispose them to greater inpatient morbidity and mortality than non-obese patients.
Dissertation