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Stewart, A.

Publications and source records attributed to Stewart, A..

At least 19 recordsLinked to original sources

Pangenomics and machine learning reveal genetic variation to optimize carotenoids in sorghum grain

Enhancing grain carotenoid concentration to increase yellowness and provitamin A content in sorghum (Sorghum bicolor [L.] Moench) is a major breeding objective across sub-Saharan Africa. Carotenoid breeding is constrained by costly post-harvest phenotyping and can be accelerated through genetic markers that capture functional variation in key carotenoid biosynthesis genes. Zeaxanthin epoxidase (ZEP) is a major gene controlling sorghum grain carotenoid accumulation, and SNP-based KASP markers facilitate selection of high-carotenoid grain, although quantitative variation remains among lines carrying the favorable allele. We hypothesized that additional functional variation within ZEP and other carotenoid biosynthesis pathway genes contributes to this variation and can be revealed by a pangenome-informed analysis. Using a 33-member pangenome reference, we characterized sequence and structural variation at ZEP and other key carotenoid biosynthesis genes and applied pangenome-derived genotyping to study marker diversity associated with carotenoid accumulation. Evaluation of ZEP in the pangenome reference revealed previously uncharacterized structural variation that is absent from the BTx623 primary reference genome. A pangenome-based association analysis identified genetic markers associated with the accumulation of carotenoids which were specific to particular pangenome reference members, including in RTx430 and SRN39, both yellow endosperm lines. Machine learning identified markers in ZEP, {beta}-OH, ZDS, and Z-ISO as the most predictive for all carotenoid traits, suggesting a multi-locus genetic architecture underlies the accumulation of carotenoids in sorghum grain. By integrating sorghum pangenomic resources with machine learning, this study establishes a framework for pangenome-accelerated trait discovery and identifies new genetic targets for carotenoid biofortification in sorghum.

genomics↗

Visibly Transparent, Near-Infrared Absorbing Nanofluids Enable High-Efficiency and Safe Laser Lithotripsy

Laser lithotripsy (LL) is the gold standard for urinary stone management yet maximizing ablation efficiency while maintaining procedural safety remains clinically challenging. Here, we present a visibly transparent, near-infrared (NIR)-absorbing ITO@SiO2 nanofluid irrigation strategy that significantly enhances LL efficiency without compromising endoscopic visibility. By spectrally matching the absorption profile of ITO@SiO2 with the clinical Holmium:YAG laser wavelength, ablation efficiency improved by >200% in the bench-top spot treatments and >100% in the hydrogel kidney model. Mechanistic investigations revealed that the enhanced optical absorption of the nanofluid modifies bubble dynamics and synergistically amplifies photothermal/microexplosion effects and cavitation damage. Importantly, both in-vitro hydrogel and in-vivo porcine kidney models demonstrated a substantial thermal safety margin (maximum temperatures <35 {degrees}C) and excellent acute biocompatibility, with no evidence of thermal tissue injury. Integrating seamlessly into established clinical workflows without requiring stone pretreatment, this strategy offers a highly translatable, safe, and efficient platform for next-generation endoscopic lithotripsy.

bioengineering↗

Nipoppy: A framework for standardizing neuroimaging studies to facilitate international derived-data sharing

Neuroimaging data management and processing are tedious and error-prone, prompting reproducibility concerns. Globally, studies with heterogeneous infrastructure and governance policies lead to eclectic data processing and sharing, necessitating standardization of data workflows to ensure reusability and comparability of multi-centric datasets. The Nipoppy neuroinformatics framework facilitates such standardization by combining specification, protocol, and software to manage study-level data workflows. With its adoption, researchers can share standardized, derived datasets enabling efficient, reproducible, and inclusive research.

bioinformatics↗

Molecular cloning of a novel, nervous system-specific RGS6 isoform lacking canonical G protein regulatory effects and with dominant negative actions

Regulator of G protein Signaling 6 (RGS6), heavily implicated in neurological and neuropsychiatric disorders, is enriched in mouse and human brain. Our initial cloning effort identified 36 RGS6 mRNAs in human brain. However, we recently identified an additional RGS6 protein isoform that is larger ([~]69kDa) than the ubiquitously expressed [~]56kDa RGS6L(+GGL) isoforms. Notably, this isoform, named "RGS6B" for "brain-specific", is selectively expressed in the nervous system of mice and humans. Here, we report the cloning of a new RGS6-encoding mRNA, which resembles the RGS6L1(+GGL) transcript identified in our initial cloning effort but includes a highly conserved novel exon (Alternative 3, A3) that alters the reading frame of terminal exon resulting in an extension of the protein C-terminus. When expressed in cells, RGS6LA31(+GGL) co-migrates with RGS6B, and, importantly, interfering RNA targeting exon A3 results in selective depletion of RGS6B in isolated primary cortical astrocytes. RGS6B is capable of stabilizing RGS6 binding partners R7BP and G{beta}5 and, in fact, exhibits an increased protein half-life relative to RGS6L. Both RGS6L and RGS6B are downregulated in human gliomas and share the ability to kill U87MG glioblastoma cells when overexpressed indicating conservation of non-canonical cytotoxic activity between RGS6L and RGS6B species. However, RGS6B lacks the ability to counteract Gi/o-dependent suppression of cAMP signaling, indicating a lack of functional GTPase activating protein (GAP) activity. Instead, RGS6B functions in a dominant negative manner to block Gi/o regulation by RGS6L. RGSB is the first identified RGS protein member that functions to promote, rather than inhibit, G protein signaling. The discovery of the molecular identity of RGS6B will now allow for delineation of unique functions for RGS6 protein isoforms in both physiological and pathophysiological brain states.

neuroscience↗

Intestinal challenges shape the polarisation of protective dural memory CD4 T cells

The meninges house several innate and adaptive immune cell populations1-3. These predominantly localise within the dura mater and include gut-derived IgA-secreting plasma cells4. Whether T cell adaptive memory in the dura is similarly linked to the gut is currently unknown. Here we show that dural CD4 T cell polarisation to a T helper (Th) 1, Th2 and Th17 state is determined by the nature of the immunological challenge encountered in the gastrointestinal tract. We find that intestinally polarised CD4 T cells seed to the dura in a CXCR6-CXCL16-dependent manner, express tissue-residency markers and are long-lived. Functionally, these orally-primed dural CD4 T are capable of a rapid antigen-specific recall response that limits pathogen spread into the brain following intravenous re-challenge. Our work reveals how linked intestinal and dural immunity enables the central nervous system to accrue immunological memory of gut microbes, the most likely source of life-threatening bloodborne pathogens.

immunology↗

Testing for a wildlife reservoir of divergent SARS-CoV-2 in white-tailed deer

The 2021 discovery of a divergent lineage (B.1.641) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in white-tailed deer (Odocoileus virginianus) from Ontario raised concerns that deer were a potential reservoir. To assess whether white-tailed deer continued to be infected with B.1.641 and to test for spillover into other species, we established a surveillance program in Ontario by sampling wildlife via existing monitoring programs and through active surveillance of captive and wild animals. Between 2022 to 2024, we tested 2,839 animals, identifying one active SARS-CoV-2 infection (a likely spillover of a recombinant XBB.2.3.11.3 lineage), but no cases of B.1.641. Overall, 93 animals (6.8%) tested positive for SARS-CoV-2 antibodies, including 89 white-tailed deer, two Virginia opossums (Didelphis virginiana), one American mink (Neogale vison), and one river otter (Lontra canadensis). In Southwestern Ontario, where B.1.641 was originally detected, 15.2% of deer samples were seropositive. Generalized Linear Models demonstrated that seropositive deer were more likely to be found in areas with a higher fall deer harvest and human population density, and closer to previous B.1.641 cases. Our data suggest that deer-associated B.1.641 may have caused a relatively localized epizootic without forming a stable reservoir. This study underscores the importance of One Health-focused surveillance.

pathology↗

Genic and phylogenomic discordances reveal conflicting hybridization episodes in temperate Loliinae grasses

The grass subtribe Loliinae has great ecological and economic importance, as it includes community-dominant species of world mountain grasslands and the most extensively cultivated pasture, fodder and lawn grasses (fescues, ryegrasses). Resolving the phylogeny of recently evolved Loliinae lineages has proven challenging due to frequent introgressions and polyploidizations that occurred throughout their history. Evolutionary reconstruction based on genome-wide data sets is useful for large groups of species, enabling recovering phylogenetic trees, contrasting their topologies, unraveling the origins of the discordances, and testing hypotheses on their reticulate history. Here we present the first target-capture phylogeny of Loliinae using 234 single-copy nuclear coding loci for a large sample of 132 representative taxa, covering all its 29 evolutionary lineages. Additionally, we have completed organelle (plastome) sequences to elucidate the hybridogenic speciation history of the Loliinae from complementary genome sources. Concatenated maximum likelihood and multispecies coalescent trees of single-copy genes showed well-supported relationships for major lineages, which were generally consistent across analyses and genomes, and with previous taxonomic and phylogenetic findings. However, they also revealed high levels of both nuclear and cyto-nuclear discordances. The time-calibrated phylogeny of target-capture data supports an early Miocene origin for Loliinae and Mid-Late Miocene splits for its main broad-leaved and fine-leaved lineages, while current species-rich groups radiated in Plio-Pleistocene times. Hybridization and topological incongruence tests between the nuclear single-copy genes and plastome-based trees using multiple approaches and different sampling subsets confirmed the rampant introgression experienced by Loliinae at deep and shallow nodes. However, hybridization rates differed from lineage to lineage within the major clades and were not correlated with time or ploidy but rather depended on the "hybridogenous" nature of particular lineages. Our analyses detected high hybridization rates in four broad-leaved (Subulatae-Hawaiian, Tropical-South African, Mexico-Central-South American and Leucopoa p.p.) and five fine-leaved Loliinae lineages (American II, Aulaxyper, Afroalpine, American-Neozeylandic) containing rogue species that probably originated from trans-clade crosses and are more likely to hybridize greatly. In contrast, they recovered low hybridization rates in four broad-leaved (Schedonorus-Lolium, Subbulbosae, Drymanthele-Pseudoscariosae-Lojaconoa, Leucopoa pp) and six fine-leaved lineages (Festuca, Psilurus-Vulpia, American I, Exaratae-Loretia, American-Vulpia-Pampas, Eskia), with species derived from single ancestors that hybridize only with close congeners. The levels of intragenomic nuclear discordance could have been magnified by the prevalence of allopolyploids in the Loliinae and by methodological bias in the selection of orthologs; however, our nuclear and plastome trees have revealed key hybrid origins in these grasses. [allopolyploidization, lineage-specific hybridization rates, nuclear and cyto-nuclear discordances, Festuca and related genera, phylogenomics, nuclear single-copy genes, plastome].

evolutionary biology↗

ZW sex chromosome structure in Amborella trichopoda

Sex chromosomes have evolved hundreds of times, and their recent origins in flowering plants can shed light on the early consequences of suppressed recombination. Amborella trichopoda, the sole species on a lineage that is sister to all other extant flowering plants, is dioecious with a young ZW sex determination system. Here we present a haplotype-resolved genome assembly, including highly-contiguous assemblies of the Z and W chromosomes. We identify a [~]3-Megabase sex-determination region (SDR) captured in two strata that includes a [~]300-Kilobase inversion that is enriched with repetitive sequence and contains a homolog of the Arabidopsis METHYLTHIOADENOSINE NUCLEOSIDASE (MTN1-2) genes, which are known to be involved in fertility. However, the remainder of the SDR does not show patterns typically found in non-recombining SDRs, like repeat accumulation and gene loss. These findings are consistent with the hypothesis that dioecy is recently derived in Amborella and the sex chromosome pair has not significantly degenerated.

genomics↗

Arc mediates intercellular synaptic plasticity via IRSp53-dependent extracellular vesicle biogenesis.

Current models of learning and memory have focused on cell-autonomous regulation of synaptic strength; however, intercellular signaling between cells in the brain is important for normal cognition. The immediate early gene Arc is a repurposed retrotransposon critical for long-term forms of synaptic plasticity and memory. Arc protein forms virus-like capsids released in extracellular vesicles (EVs) that mediate intercellular signaling of unknown function. Here, we find that long-term potentiation stimuli induce the biogenesis of Arc EVs by recruiting the I-BAR protein IRSp53, which facilitates Arc capsid assembly, trafficking, and release from actin-rich filopodial structures in dendrites. Arc EVs transfer Arc protein and mRNA to neighboring dendrites, where translation of transferred Arc mRNA induces a loss of surface AMPA-type glutamate receptors. These results show that Arc EVs mediate an intercellular form of synaptic plasticity that may be critical for memory consolidation and reveals a new neuronal EV biogenesis pathway.

neuroscience↗

Developing a safe 15-hour preservation protocol of donor kidneys using normothermic machine perfusion

IntroductionO_ST_ABSBackgroundC_ST_ABSNormothermic machine perfusion (NMP) offers a superior alternative to existing hypothermic preservation strategies but is currently limited to 1-3 hours. Extending the time a kidney can be sustained using this technology could electivise transplantation, and enable physiological assessments of renal function. We aimed to develop a protocol that allows the safe preservation of donor kidneys for 12 hours using this technique. MethodsPorcine kidneys (n=20) were retrieved and flushed with 1L preservation solution before being stored on ice. Following a cold ischaemic time of 3.5 hours, kidneys were placed onto a NMP circuit and perfused for 12 hours. Renal haemodynamics, biochemistry and urine output were recorded and analysed. At the end of perfusion, kidneys were scored based on the clinical assessment score and their suitability for transplant determined. Biopsies were collected at the end for histological assessment. ResultsAll kidneys were successfully perfused with immediate recordable renal blood flow (RBF). RBF continually improved over the course of the perfusions, peaking at 12 hours, and negatively correlated with intra-renal resistance. Perfusate sodium concentrations remained stable and within physiological parameters. Sodium bicarbonate increased over time with a corresponding decrease in lactate concentrations, demonstrating active renal gluconeogenesis and Cori cycle processes. Urine production began immediately in all kidneys and was sustained throughout, indicating active renal function. Under the clinical perfusion assessment score, all kidneys received a score of 1 and would be considered suitable for transplantation. Histological assessment revealed kidneys were injury free with REMUZZI scores of 0 in all samples. ConclusionWe have developed an NMP protocol that safely preserves donor kidneys for over 15 hours. Successful perfusion was achieved with stable haemodynamics, blood-perfusate biochemistry, and maintained urine output. Importantly, kidneys remained in optimal health, with no evidence of injury. This protocol may enable the electivisation of transplantation, while reducing ischaemic injury associated with static cold storage.

physiology↗

Kappa Opioid Receptor Antagonism Rescues Genetic Perturbation of Dopamine Homeostasis: Molecular, Physiological and Behavioral Consequences

Aberrant dopamine (DA) signaling is implicated in schizophrenia, bipolar disorder (BPD), autism spectrum disorder (ASD), substance use disorder, and attention-deficit/hyperactivity disorder (ADHD). Treatment of these disorders remains inadequate, as exemplified by the therapeutic use of d-amphetamine and methylphenidate for the treatment of ADHD, agents with high abuse liability. In search for an improved and non-addictive therapeutic approach for the treatment of DA-linked disorders, we utilized a preclinical mouse model expressing the human DA transporter (DAT) coding variant DAT Val559, previously identified in individuals with ADHD, ASD, or BPD. DAT Val559, like several other disease-associated variants of DAT, exhibits anomalous DA efflux (ADE) that can be blocked by d-amphetamine and methylphenidate. Kappa opioid receptors (KORs) are expressed by DA neurons and modulate DA release and clearance, suggesting that targeting KORs might also provide an alternative approach to normalizing DA-signaling disrupted by perturbed DAT function. Here we demonstrate that KOR stimulation leads to enhanced surface trafficking and phosphorylation of Thr53 in wildtype DAT, effects achieved constitutively by the Val559 mutant. Moreover, these effects can be rescued by KOR antagonism of DAT Val559 in ex vivo preparations. Importantly, KOR antagonism also corrected in vivo DA release as well as sex-dependent behavioral abnormalities observed in DAT Val559 mice. Given their low abuse liability, our studies with a construct valid model of human DA associated disorders reinforce considerations of KOR antagonism as a pharmacological strategy to treat DA associated brain disorders.

neuroscience↗

SimpliPyTEM: An open-source Python library and app to simplify Transmission Electron Microscopy and in situ-TEM image analysis.

Introducing SimpliPyTEM, a Python library and accompanying GUI that simplifies the post-acquisition evaluation of transmission electron microscopy (TEM) images, helping streamline the workflow. After an imaging session, a folder of image and/or video files, typically containing low contrast and large file size 32-bit images, can be quickly processed via SimpliPyTEM into high-quality, high-contrast .jpg images with suitably sized scale-bars. The app can also generate HTML or PDF files containing the processed images for easy viewing and sharing. Additionally, SimpliPyTEM has a specific focus on in situ TEM videos, an emerging field of EM, allowing for fast data processing into preview movies, averages, image series, or motion corrected averages using MotionCor2. The accompanying Python library offers many standard image processing methods, all simplified to a single command, plus a module to analyse particle morphology and population. This latter application is particularly useful for life sciences investigations. User-friendly tutorials and clear documentation are included to help guide users through the processing and analysis. We invite the EM community to contribute to and further develop this open-source package.

biophysics↗

sciCSR infers B cell state transition and predicts class-switch recombination dynamics using single-cell transcriptomic data

Class-switch recombination (CSR) is an integral part of B cell maturation. Steady-state analyses of isotype distribution (e.g. B cell receptor [BCR] repertoire analysis of snapshots during an immune response) do not directly measure CSR dynamics, which is crucial in understanding how B cell maturation is regulated across time. We present sciCSR (pronounced scissor, single-cell inference of class switch recombination), a computational pipeline which analyses CSR events and dynamics of B cells from single-cell RNA-sequencing (scRNA-seq) experiments. sciCSR re-analyses transcriptomic sequence alignments to differentiate productive heavy-chain immunoglobulin transcripts from germline "sterile" transcripts. From a snapshot of B cell scRNA-seq data, a Markov state model is built by the pipeline to infer the dynamics and direction of CSR. Applying sciCSR on SARS-CoV-2 vaccination time-course scRNA-seq data, we observe that sciCSR predicts, using data from an earlier timepoint in the collected time-course, the isotype distribution of BCR repertoires of subsequent timepoints with high accuracy (cosine similarity [~] 0.9). sciCSR also recapitulates CSR patterns in mouse models where B cell maturation was perturbed using gene knockouts. sciCSR infers cell state transitions using processes specific to B cells, identifies transitions which are often missed by conventional RNA velocity analyses, and can reveal insights into the regulation of CSR and the dynamics of B cell maturation during an immune response.

bioinformatics↗

Neurodesk: An accessible, flexible, and portable data analysis environment for reproducible neuroimaging

Neuroimaging data analysis often requires purpose-built software, which can be challenging to install and may produce different results across computing environments. Beyond being a roadblock to neuroscientists, these issues of accessibility and portability can hamper the reproducibility of neuroimaging data analysis pipelines. Here, we introduce the Neurodesk platform, which harnesses software containers to support a comprehensive and growing suite of neuroimaging software (https://www.neurodesk.org/). Neurodesk includes a browser-accessible virtual desktop environment and a command line interface, mediating access to containerized neuroimaging software libraries on various computing platforms, including personal and high-performance computers, cloud computing and Jupyter Notebooks. This community-oriented, open-source platform enables a paradigm shift for neuroimaging data analysis, allowing for accessible, flexible, fully reproducible, and portable data analysis pipelines.

neuroscience↗

DAT Val559 Mice Exhibit Compulsive Behavior Under Devalued Reward Conditions Accompanied by Cellular and Pharmacological Changes

Identified across multiple psychiatric disorders, the dopamine (DA) transporter (DAT) Ala559Val substitution triggers non-vesicular, anomalous DA efflux (ADE), perturbing DA neurotransmission and behavior. We have shown that DAT Val559 mice display a waiting impulsivity and changes in cognitive performance associated with enhanced reward motivation. Here, utilizing a within-subject, lever-pressing paradigm designed to bias the formation of goal-directed or habitual behavior, we demonstrate that DAT Val559 mice modulate their nose-poke behavior appropriately to match context, but demonstrate a perseverative checking behavior. Although DAT Val559 mice display no issues with the cognitive flexibility required to acquire and re-learn a visual pairwise discrimination task, devaluation of reward evoked habitual reward seeking in DAT Val559 mutants in operant tasks regardless of reinforcement schedule. The direct DA agonist apomorphine also elicits locomotor stereotypies in DAT Val559, but not WT mice. Our observation that dendritic spine density is increased in the dorsal medial striatum (DMS) of DAT Val559 mice speaks to an imbalance in striatal circuitry that might underlie the propensity of DAT Val559 mutants to exhibit compulsive behaviors when reward is devalued. Thus, DAT Val559 mice represent a model for dissection of how altered DA signaling perturbs circuits that normally balance habitual and goal-directed behaviors.

neuroscience↗

The western redcedar genome reveals low genetic diversity in a self-compatible conifer

We assembled the 9.8 Gbp genome of western redcedar (WRC, Thuja plicata), an ecologically and economically important conifer species of the Cupressaceae. The genome assembly, derived from a uniquely inbred tree produced through five generations of self-fertilization (selfing), was determined to be 86% complete by BUSCO analysis - one of the most complete genome assemblies for a conifer. Population genomic analysis revealed WRC to be one of the most genetically depauperate wild plant species, with an effective population size of approximately 300 and no significant genetic differentiation across its geographic range. Nucleotide diversity, {pi}, is low for a continuous tree species, with many loci exhibiting zero diversity, and the ratio of {pi} at zero-to four-fold degenerate sites is relatively high ([~] 0.33), suggestive of weak purifying selection. Using an array of genetic lines derived from up to five generations of selfing, we explored the relationship between genetic diversity and mating system. While overall heterozygosity was found to decline faster than expected during selfing, heterozygosity persisted at many loci, and nearly 100 loci were found to deviate from expectations of genetic drift, suggestive of associative overdominance. Non-reference alleles at such loci often harbor deleterious mutations and are rare in natural populations, implying that balanced polymorphisms are maintained by linkage to dominant beneficial alleles. This may account for how WRC remains responsive to natural and artificial selection, despite low genetic diversity.

plant biology↗

The PREGCARE study: Personalized recurrence risk assessment following the birth of a child with a pathogenic de novo mutation

Next-generation sequencing has led to a dramatic improvement in molecular diagnoses of serious pediatric disorders caused by apparently de novo mutations (DNMs); by contrast, clinicians ability to counsel the parents about the risk of recurrence in a future child has lagged behind. Owing to the possibility that one of the parents could be mosaic in their germline, a recurrence risk of 1-2% is frequently quoted, but for any specific couple, this figure is usually incorrect. We present a systematic approach to providing individualized recurrence risk stratification, by combining deep-sequencing of multiple tissues in the mother-father-child trio with haplotyping to determine the parental origin of the DNM. In the first 58 couples analysed (total of 59 DNMs in 49 different genes), the risk for 35 (59%) DNMs was decreased below 0.1% but for 6 (10%) couples it was increased owing to parental mosaicism - that could be quantified in semen (recurrence risks of 5.6-12.1%) for the paternal cases. Deep-sequencing of the DNM efficiently identifies couples at greatest risk for recurrence and may qualify them for additional reproductive technologies. Haplotyping can further reassure many other couples that their recurrence risk is very low, but its implementation is more technically challenging and will require better understanding of how couples respond to information that reduces their risks.

genetics↗

Identification of plasma proteins associated with oesophageal cancer chemotherapeutic treatment outcomes using SWATH-MS

Oesophageal adenocarcinoma (OAC) is an aggressive cancer with a five-year survival of <15%. Current chemotherapeutic strategies only benefit a minority (20-30%) of patients and there are no methods available to differentiate between responders and non-responders. We performed quantitative proteomics using Sequential Window Acquisition of all THeoretical fragment-ion spectra-Mass Spectrometry (SWATH-MS) on albumin/IgG-depleted and non-depleted plasma samples from 23 patients with locally advanced OAC prior to treatment. Individuals were grouped based on tumour regression (TRG) score (TRG1/2/3 vs TRG4/5) after chemotherapy, and differentially abundant proteins were compared. Protein depletion of highly abundant proteins led to the identification of around twice as many proteins. SWATH-MS revealed significant quantitative differences in the abundance of several proteins between the two groups. These included complement c1q subunit proteins, C1QA, C1QB and C1QC, which were of higher abundance in the low TRG group. Of those that were found to be of higher abundance in the high TRG group, GSTP1 was found to exhibit the lowest p-value and highest classification accuracy and Cohens kappa value. Concentrations of these proteins were further examined using ELISA-based assays. This study provides quantitative information relating to differences in the plasma proteome that underpin response to chemotherapeutic treatment in oesophageal cancers.

cancer biology↗