Behavior and toxicological impact of spilled diluted bitumen and conventional heavy crude oil in the unsaturated zone.

Demand for unconventional crude oils continues to drive the production of diluted bitumen (dilbit) within Western Canada, promoting increased transport volumes across the extensive 700,000 km pipeline system of Canada and the USA. Despite this vast extent of terrestrial transport, the current understanding of the behavior and fate of spilled dilbit within shallow groundwater systems is limited. To this end, oil spill experiments with a dilbit (Cold Lake Blend) and a physicochemically similar conventional heavy crude oil (Conventional Heavy Blend) were conducted for 104 days in large soil columns (1 m height × 0.6 m diameter) engineered to model contaminant transport in the unsaturated (vadose) zone. Around two-fold greater concentrations and 6-41 % faster rates of vadose zone transport of benzene, toluene, ethylbenzene and xylenes (BTEX) and polycyclic aromatic compounds (PACs) were observed in the dilbit- compared to conventional heavy crude-contaminated columns. As determined by Orbitrap mass spectrometry, the OxSx species abundances in the acid extractable organics (AEOs) fraction of column leachate from both oil types increased over time, ostensibly due to microbial degradation of petroleum. Bioaccumulation of petroleum constituents in fathead minnow (Pimephales promelas) larvae exposed to contaminated leachate was confirmed through the induction of developmental malformations lasting up to 34 days and increased abundance of cyp1a mRNA observed throughout the experiment. Toxicity was comparable between the two oils but could not be fully attributed to metals, BTEX, PACs or AEOs, implying the presence of uncharacterized teratogens capable of being transported within the vadose zone following terrestrial dilbit and conventional heavy crude oil surface spills.

Is Seven Days Enough? Comparing A 7-Day Exposure to the Classical 21-Day OECD TG 229 Fish Short-Term Reproduction Assay in Fathead Minnow.

The OECD (Organisation for Economic Co-operation and Development) test guidelines (TG) 229-fish short-term reproduction assay (FSTRA) is one of the gold standard methods used to identify endocrine disrupting chemicals (EDCs). While informative, the FSTRA's 5-6 week duration makes it difficult to use routinely. Prior studies have shown that EDCs' impact on fecundity, vitellogenin (VTG) and steroid levels can be detected after less than 1 week of exposure suggesting the FSTRA could be shortened. This study compares both 7- and 21-day FSTRAs using fathead minnows (Pimephales promelas) for three known EDCs: 17α-ethinylestradiol (EE2; 40 ng/L), 17ß-trenbolone (TRB; 50 µg/L), and propiconazole (PRP; 500 µg/L). All three compounds led to arrested fertility after 24 h of exposure, except for the 7-day EE2 treatment which still decreased reproduction. Moreover, independently of time of exposure, EE2 induced VTG production in males, and decreased estrogen levels in females and testosterone levels in males. In contrast, TRB-induced VTG production in males, while the levels were not different from controls in females even though testosterone levels increased, and masculinization was observed. Finally, PRP led to a decrease in VTG levels which was only significant during the 21-day exposure, and surprisingly, no effect on steroid levels were observed despite its known effects on steroidogenesis. For two of the three EDCs tested, both times of exposure led to similar outcomes supporting the shortening of the FSTRA to seven days. This proposed 7-day FSTRA could be used to screen EDCs in routine monitoring of environmental samples.

Theta-band neural oscillations reflect cognitive control during language processing.

As we interpret language moment by moment, we often encounter conflicting cues in the input that create incompatible representations of sentence meaning, which must be promptly resolved. Although ample evidence suggests that cognitive control aids in the resolution of such conflict, the methods commonly used to assess cognitive control's involvement in language comprehension provide limited information about the time course of its engagement. Here, we show that neural oscillatory activity in the theta-band (∼3-8 Hz), which is associated with cognitive control in nonlinguistic tasks like Stroop and Flanker, provides a real-time index of cognitive control during language processing. We conducted time-frequency analyses of four electroencephalogram data sets, and consistently observed that increased theta-band power was elicited by various kinds of linguistic conflict. Moreover, increases in the degree of conflict within a sentence produced greater increases in theta activity. These effects emerged as early as 300 ms from the onset of the initiating event, indicating rapid cognitive-control recruitment during sentence processing in response to conflicting representations. Crucially, the effect patterns could not be ascribed to processing difficulty that is not due to conflict (e.g., semantic implausibility was neither necessary nor sufficient to elicit theta activity). We suggest that neural oscillations in the theta-band offer a reliable way to test specific hypotheses about cognitive-control engagement during real-time language comprehension. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Integrating viruses into soil food web biogeochemistry.

The soil microbiome is recognized as an essential component of healthy soils. Viruses are also diverse and abundant in soils, but their roles in soil systems remain unclear. Here we argue for the consideration of viruses in soil microbial food webs and describe the impact of viruses on soil biogeochemistry. The soil food web is an intricate series of trophic levels that span from autotrophic microorganisms to plants and animals. Each soil system encompasses contrasting and dynamic physicochemical conditions, with labyrinthine habitats composed of particles. Conditions are prone to shifts in space and time, and this variability can obstruct or facilitate interactions of microorganisms and viruses. Because viruses can infect all domains of life, they must be considered as key regulators of soil food web dynamics and biogeochemical cycling. We highlight future research avenues that will enable a more robust understanding of the roles of viruses in soil function and health.

Non-invasive biomonitoring of polar bear feces can be used to estimate concentrations of metals of concern in traditional food.

The Arctic faces increasing exposure to environmental chemicals such as metals, posing health risks to humans and wildlife. Biomonitoring of polar bears (Ursus maritimus) can be used to quantify chemicals in the environment and in traditional foods consumed by the Inuit. However, typically, these samples are collected through invasive or terminal methods. The biomonitoring of feces could be a useful alternative to the current metal monitoring method within the Arctic. Here, we aim to 1) quantify the relationship between concentrations of metals in the feces and tissues (muscle, liver, and fat) of polar bears using predictive modeling, 2) develop an easy-to-use conversion tool for use in community-based monitoring programs to non-invasively estimate contaminant concentrations in polar bears tissues and 3) demonstrate the application of these models by examining potential exposure risk for humans from consumption of polar bear muscle. Fecal, muscle, liver, and fat samples were harvested from 49 polar bears through a community-based monitoring program. The samples were analyzed for 32 metals. Exploratory analysis indicated that mean metal concentrations generally did not vary by age or sex, and many of the metals measured in feces were positively correlated with the internal tissue concentration. We developed predictive linear regression models between internal (muscle, liver, fat) and external (feces) metal concentrations and further explored the mercury and methylmercury relationships for utility risk screening. Using the cross-validated regression coefficients, we developed a conversion tool that contributes to the One Health approach by understanding the interrelated health of humans, wildlife, and the environment in the Arctic. The findings support using feces as a biomonitoring tool for assessing contaminants in polar bears. Further research is needed to validate the developed models for other regions in the Arctic and assess the impact of environmental weathering on fecal metal concentrations.

Impact of childhood nephrotic syndrome on obesity and growth: a prospective cohort study.

BACKGROUND: Children with nephrotic syndrome are at risk of obesity and growth impairment from repeated steroid treatment. However, incidence and risk factors for obesity and short stature remain uncertain, which is a barrier to preventative care. Our aim was to determine risk, timing, and predictors of obesity and short stature among children with nephrotic syndrome. METHODS: We evaluated obesity and longitudinal growth among children (1-18 years) enrolled in Insight into Nephrotic Syndrome: Investigating Genes, Health, and Therapeutics. We included children with nephrotic syndrome diagnosed between 1996-2019 from the Greater Toronto Area, Canada, excluding congenital or secondary nephrotic syndrome. Primary outcomes were obesity (body mass index Z-score ≥ + 2) and short stature (height Z-score ≤ -2). We evaluated prevalence of obesity and short stature at enrolment (< 1-year from diagnosis) and incidence during follow-up. Cox proportional hazards models determined the association between nephrotic syndrome classification and new-onset obesity and short stature. RESULTS: We included 531 children with nephrotic syndrome (30% frequently relapsing by 1-year). At enrolment, obesity prevalence was 23.5%, 51.8% were overweight, and 4.9% had short stature. Cumulative incidence of new-onset obesity and short stature over median 4.1-year follow-up was 17.7% and 3.3% respectively. Children with frequently relapsing or steroid dependent nephrotic syndrome within 1-year of diagnosis were at increased risk of new-onset short stature (unadjusted hazard ratio 3.99, 95%CI 1.26-12.62) but not obesity (adjusted hazard ratio 1.56, 95%CI 0.95-2.56). Children with ≥ 7 and ≥ 15 total relapses were more likely to develop obesity and short stature, respectively. CONCLUSIONS: Obesity is common among children with nephrotic syndrome early after diagnosis. Although short stature was uncommon overall, children with frequently relapsing or steroid dependent disease are at increased risk of developing short stature. Effective relapse prevention may reduce steroid toxicity and the risk of developing obesity or short stature.

Investigating the anti-bioadhesion properties of short, medium chain length, and amphiphilic polyhydroxyalkanoate films.

Silicone materials are widely used in fouling release coatings, but developing eco-friendly protection via biosourced coatings, such as polyhydroxyalcanoates (PHA) presents a major challenge. Anti-bioadhesion properties of medium chain length PHA and short chain length PHA films are studied and compared with a reference Polydimethylsiloxane coating. The results highlight the best capability of the soft and low-roughness PHA-mcl films to resist bacteria or diatoms adsorption as compared to neat PDMS and PHBHV coatings. These parameters are insufficient to explain all the results and other properties related to PHA crystallinity are discussed. Moreover, the addition of a low amount of PEG copolymers within the coatings, to create amphiphilic coatings, boosts their anti-adhesive properties. This work reveals the importance of the physical or chemical ambiguity of surfaces in their anti-adhesive effectiveness and highlights the potential of PHA-mcl film to resist the primary adhesion of microorganisms.

Straightforward Way to Provide Antibacterial Properties to Healthcare Textiles through N-2-Hydroxypropyltrimethylammonium Chloride Chitosan Crosslinking.

A straightforward and cost-effective way to coat polypropylene fibers, designed for healthcare textiles, was developed through chitosan crosslinking for antibacterial purposes. As polypropylene is an inert material, the goal was to physically trap the inert fibers through a network of crosslinked chitosan or a quaternized derivative (to enhance the antibacterial action). First, chitosan or its quaternized derivative was physically deposited by impregnation or spraying. Then, chitosan was crosslinked in glutaraldehyde solution followed by its quaternized derivative with a diisocyanate. Coated fabrics were characterized by infrared spectroscopy (IR), weight gain measurements, and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX). This led us to conclude that spraying provides uniform deposition while maintaining the fabric's porosity. Acidic washing allowed us to prove that chitosan and its quaternized derivative were successfully immobilized on the fabric. Biological assays were conducted against two major strains of bacteria responsible for nosocomial infections: Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). Chitosan-crosslinked samples did not show significant antibacterial activity, but the quaternized derivative allowed a significant decrease in S. aureus colonization. This study presents a simple and scalable process to coat inert fabrics with a polymer containing reactive functions potentially available to graft various additional antimicrobial agents.

Green Physical Modification of Polypropylene Fabrics by Cross-Linking Chitosan with Tannic Acid and Postmodification by Quaternary Ammonium Grafting to Improve Antibacterial Activity.

A green cross-linking and straightforward method to physically trap inert fibers in a network of chitosan was implemented. The cross-linking reaction involved a biosourced and biocompatible cross-linker [tannic acid (TA)] and mild conditions in water (pH = 8.5, O2 bubbling, 60 °C, 3 h). The steric hindrance of TA led to a low but effective cross-linking rate leaving parts of primary amines of chitosan available for postmodification such as the grafting of quaternary ammoniums for antibacterial purposes. Fabric's coatings were characterized by scanning electron microscopy coupled with energy-dispersive X-ray, infrared spectroscopy, and weight gain measurements. This allowed the optimization of process conditions. No significant antioxidant activity was observed on fabrics coated with chitosan cross-linked with TA, confirming the low cross-linking rate. This low cross-linking rate allowed grafting of quaternary ammoniums for antibacterial purposes, but it is possible to consider grafting other active molecules. Biological assays were conducted on this coating to assess its antibacterial properties. Reduction of bacterial colonization on both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), two of the major strains responsible for nosocomial infections, confirmed the potential of the coating for antibacterial purposes. This study displays a simple and ecofriendly process to coat inert fabrics with a chitosan network containing reactive functions (primary amines) available for grafting active molecules for various purposes.

The State of Cognitive Control in Language Processing.

Understanding language requires readers and listeners to cull meaning from fast-unfolding messages that often contain conflicting cues pointing to incompatible ways of interpreting the input (e.g., "The cat was chased by the mouse"). This article reviews mounting evidence from multiple methods demonstrating that cognitive control plays an essential role in resolving conflict during language comprehension. How does cognitive control accomplish this task? Psycholinguistic proposals have conspicuously failed to address this question. We introduce an account in which cognitive control aids language processing when cues conflict by sending top-down biasing signals that strengthen the interpretation supported by the most reliable evidence available. We also provide a computationally plausible model that solves the critical problem of how cognitive control "knows" which way to direct its biasing signal by allowing linguistic knowledge itself to issue crucial guidance. Such a mental architecture can explain a range of experimental findings, including how moment-to-moment shifts in cognitive-control state-its level of activity within a person-directly impact how quickly and successfully language comprehension is achieved.

Thyroid axis participates in high-temperature-induced male sex reversal through its activation by the stress response.

Environmental changes alter the sex fate in about 15% of vertebrate orders, mainly in ectotherms such as fish and reptiles. However, the effects of temperature changes on the endocrine and molecular processes controlling gonadal sex determination are not fully understood. Here, we provide evidence that thyroid hormones (THs) act as co-players in heat-induced masculinization through interactions with the stress axis to promote testicular development. We first demonstrated that the thyroid axis (through thyroid-related genes and T3 levels) is highly active in males during the gonadal development in medaka (Oryzias latipes). Similarly, T3 treatments promoted female-to-male sex reversal in XX embryos. Subsequently, embryonic exposure to temperature-induced stress up-regulated the genes related to the thyroid and stress axes with a final increase in T3 levels. In this context, we show that blocking the stress axis response by the loss of function of the corticotropin-releasing hormone receptors suppresses thyroid-stimulating hormone expression, therefore, heat-induced activation of the thyroid axis. Thus, our data showed that early activation of the stress axis and, in consequence, the TH axis, too, leaves us with that both being important endocrine players in inducing female-to-male reversal, which can help predict possible upcoming physiological impacts of global warming on fish populations.

Meeting report: The first soil viral workshop 2022.

Soil viral ecology is a growing research field; however, the state of knowledge still lags behind that of aquatic systems. Therefore, to facilitate progress, the first Soil Viral Workshop was held to encourage international scientific discussion and collaboration, suggest guidelines for future research, and establish soil viral research as a concrete research area. The workshop took place at Søminestationen, Denmark, between 15 and 17th of June 2022. The meeting was primarily held in person, but the sessions were also streamed online. The workshop was attended by 23 researchers from ten different countries and from a wide range of subfields and career stages. Eleven talks were presented, followed by discussions revolving around three major topics: viral genomics, virus-host interactions, and viruses in the soil food web. The main take-home messages and suggestions from the discussions are summarized in this report.

Hydrogel Based on Polyhydroxyalkanoate Sulfonate: Control of the Swelling Rate by the Ionic Group Content.

Hydrogels based on poly(3-hydroxyalkanoate) (PHA) sulfonate and poly(ethylene glycol) diacrylate, PEGDA, are prepared. First, PHA sulfonate is synthesized from unsaturated PHA by a thiol-ene reaction in the presence of sodium-3-mercapto-1-ethanesulfonate. The hydrophilicity of PHAs is considerably increased by adding sulfonate functions, and three amphiphilic PHAs are synthesized, containing 10, 22, or 29% sulfonate functions. Then, hydrogels are formed in the presence of PEGDA having different molar masses, that is, 575 or 2000 g mol-1. The hydrogels show fibrillar and porous structures observed in cryo-MEB with pore sizes that vary according to the content of sulfonated groups (10 to 29 mol %) ranging from 50 to more than 150 nm. Furthermore, depending on the proportions of the two polymers, a variable rigidity is observed from 2 to 40 Pa. In fact, the evaluation of the dynamic mechanical properties of the hydrogel determined by DMA reveals that the less rigid hydrogels hinder the adhesion of Pseudomonas aeruginosa PaO1 bacteria. Finally, these hydrogels swelling up to 5000% are noncytotoxic, allowing the adhesion and amplification of immortalized C2C12 cells, and they are therefore seen as promising materials both for repelling PaO1 bacteria and for amplifying myogenic cells.

Isotopic and microbial evidence for biodegradation of diluted bitumen in the unsaturated zone.

The oil sands region in Western Canada is one of the world's largest proven oil reserves. To facilitate pipeline transport, highly viscous oil sands bitumen is blended with lighter hydrocarbon fractions to produce diluted bitumen (dilbit). Anticipated increases in dilbit production and transport raise the risk of inland spills. To understand the behaviour of dilbit in the unsaturated or vadose zone following a surface spill, we ran parallel dilbit and conventional heavy crude exposures, along with an untreated control, using large soil-filled columns over 104 days. Phospholipid fatty acids (PLFAs), biomarkers for the active microbial population, were extracted from column soil cores. Stable carbon isotope contents (δ13C) of individual PLFAs and radiocarbon contents (Δ14C) of bulk PLFAs were characterized over the course of the experiment. The Δ14CPLFA values in soils impacted by dilbit (-221.1 to -54.7‰) and conventional heavy crude (-259.4 to -97.9‰) indicated similar levels of microbial uptake of fossil carbon. In contrast, Δ14CPLFA values in the control column (-46.1 to +53.7‰) reflected assimilation of more recently fixed organic carbon. Sequencing of 16S ribosomal RNA genes extracted from soil cores revealed a significant increase in the relative abundance of Polaromonas, a known hydrocarbon-degrader, following exposure to both types of oil. This study demonstrates that in the first several months following a surface spill, dilbit has a similar potential for biodegradation by a native shallow subsurface microbial community as conventional heavy crude oil.

A Tale of Two Seasons: Distinct Seasonal Viral Communities in a Thermokarst Lake.

Thermokarst lakes are important features of subarctic landscapes and are a substantial source of greenhouse gases, although the extent of gas produced varies seasonally. Microbial communities are responsible for the production of methane and CO2 but the "top down" forces that influence microbial dynamics (i.e., grazers and viruses) and how they vary temporally within these lakes are still poorly understood. The aim of this study was to examine viral diversity over time to elucidate the seasonal structure of the viral communities in thermokarst lakes. We produced virus-enriched metagenomes from a subarctic peatland thermokarst lake in the summer and winter over three years. The vast majority of vOTUs assigned to viral families belonged to Caudovirales (Caudoviricetes), notably the morphological groups myovirus, siphovirus and podovirus. We identified two distinct communities: a dynamic, seasonal community in the oxygenated surface layer during the summer and a stable community found in the anoxic water layer at the bottom of the lake in summer and throughout much of the water column in winter. Comparison with other permafrost and northern lake metagenomes highlighted the distinct composition of viral communities in this permafrost thaw lake ecosystem.

Early developmental toxicity of Atlantic salmon exposed to conventional and unconventional oils.

Atlantic salmon is an important species for Canadian culture and economy and its importance extends beyond Canada to Scandinavia and Western Europe. However, it is a vulnerable species facing decline due to habitat contamination and destruction. Existing and new Canadian pipeline projects pose a threat to salmonid habitat. The effects of diluted bitumen (dilbit), the main oil circulating in pipelines, are less studied than those of conventional oils, especially during the critical early embryonic developmental stage occurring in freshwater ecosystems. Therefore, this study aimed to compare the effects of water-accommodated fractions (WAF) of the Clearwater McMurray dilbit and the Lloydminster Heavy conventional oil on Atlantic salmon embryos exposed either from fertilization or from eyed stage. The dilbit contained the highest concentrations of low molecular weight (LMW) compounds (including BTEX and C6-C10), while the conventional oil contained the highest concentrations of PAHs. The Clearwater dilbit caused a higher percentage of mortality and malformations than the conventional oil at similar WAF concentrations. In addition, the embryos exposed from fertilization suffered a higher mortality rate, more developmental delays, and malformations than embryos exposed from the eyed stage, suggesting that early development is the most sensitive developmental stage to oil exposure. Gene expression and enzymatic activity of the detoxification phase I and II enzymes (CYP1A and GST) were measured. Data showed increases in both cyp1a expression and GST activity with increasing WAF concentrations, while gst expression was not affected by the exposures. Also, gene expression of proteins involved in the biotransformation of vitamin A and DNA damage repair were modified by the oil exposures. Overall, this study indicates that Atlantic salmon is mostly affected by oil exposure at the beginning of its development, during which embryos accumulate deformities that may impact their survival at later life stages.

Phenology of the transcriptome coincides with the physiology of double-crested cormorant embryonic development.

The rigorous timing of the dynamic transcriptome within the embryo has to be well orchestrated for normal development. Identifying the phenology of the transcriptome along with the physiology of embryonic development in birds may suggest periods of increased sensitivity to contaminant exposure depending on the contaminant's mechanism of action. Double-crested cormorants (Nannopterum auritum, formerly Phalacrocorax auritus) are commonly used in ecotoxicological studies, but relatively little is known about their functional transcriptome profile in early development. In this study, we tracked the phenology of the transcriptome during N. auritum embryogenesis. Fresh eggs were collected from a reference site and artificially incubated from collection until four days prior to hatching. Embryos were periodically sampled throughout incubation for a total of seven time points. A custom microarray was designed for cormorants (over 14,000 probes) and used for transcriptome analysis in whole body (days 5, 8) and liver tissue (days 12, 14, 16, 20, 24). Three main developmental periods (early, mid, and late incubation) were identified with differentially expressed genes, gene sets, and pathways within and between each developmental transition. Overall, the timing of differentially expressed genes and enriched pathways corresponded to previously documented changes in morphology, neurology, or physiology during avian embryonic development. Targeted investigation of a subset of genes involved in endogenous and xenobiotic metabolism (e.g., cytochrome P450 cyp1a, cyp1b1, superoxide dismutase 1 sod1) were expressed in a pattern similar to reported endogenous compound levels. These data can provide insights on normal embryonic development in an ecologically relevant species without any environmental contaminant exposure.

Biocompatible Semi-Interpenetrating Materials Based on Poly(3-hydroxyalkanoate)s and Poly(ethyleneglycol) Diacrylate.

Biocompatible gels based on poly(3-hydroxyalkanoate)s (PHAs) were developed by radical polymerization in the presence of poly(ethylene glycol) diacrylate (PEGDA). In order to elaborate cross-linked networks based on PEGDA and PHAs, several PHAs were tested; saturated PHAs, such as poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) or poly(3-hydroxyoctanoate) (PHO), and an unsaturated PHA, poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) PHOU. The PHAxPEGDA1-x networks obtained in this work were studied by FTIR, Raman spectroscopy, DSC, TGA and NMR. The microscopic structure varied according to the mass proportions between the two polymers. Time Domain 1H DQ NMR measurements demonstrated that in the case of the unsaturated PHA, it was chemically crosslinked with PEGDA, due to the presence of double bonds in the lateral groups. The organogels were able to swell in organic solvents, such as THF, up to 2000% and in water up to 86%. It was observed by rheological analysis that the stiffness of the networks was dependent on the content of PHA and on the degree of cross-linking. The biocompatible characters of PHOU and PEGDA were not affected by the formation of the networks and these networks had the advantage of being non-cytotoxic to immortalized C2C12 myoblast cells.

Longitudinal Changes in Cardiac Structure and Function in Pediatric Kidney Transplant Recipients.

BACKGROUND: Cardiovascular disease results in increased morbidity and mortality in pediatric kidney transplant recipients. Longitudinal changes in cardiac structure and function and the association with blood pressure control over time in pediatric kidney transplant recipients are unknown. METHODS: To determine the influence of blood pressure control on cardiac changes following pediatric kidney transplant, we conducted a retrospective cohort study of children who received their first kidney transplant at the Hospital for Sick Children from 2004 to 2015. Children were followed until transfer to adult care or censoring in July 2018. Cardiac structure and function parameters were collected from clinical echocardiograms and assessed using standardized scores. Blood pressure control was determined by systolic blood pressure Z scores (above or below the 90th percentile) in combination with antihypertensive medications. A segmented mixed-effects model assessed Z scores of interventricular septum thickness, left ventricular end-diastolic dimension, and left ventricular posterior wall dimension. RESULTS: Of 142 children included, 58% were men, mean age at transplant was 11 (±4.5) years, and average follow-up time was 4 (±3) years. All cardiac structural Z scores improved during follow-up. Interventricular septum thickness normalized at 4.0 years post-transplant. Left ventricular end-diastolic dimension normalized at 1.5 years post-transplant. Left ventricular posterior wall dimension normalized at 6.3 years post-transplant. Left ventricular mass index showed sustained improvement up to 12 years post-transplant. Individuals with uncontrolled blood pressure had increased left ventricular mass (ß=2.97 [95% CI, 0.77-5.16]). CONCLUSIONS: Cardiac structural abnormalities improve following kidney transplantation and normalize within 7 years, especially with controlled blood pressure. Strict blood pressure control is critical after pediatric kidney transplantation.