GATE Monte Carlo approach to heterogeneity dose distribution in small fields used in radiation therapy

The Accurate dosage prediction in Radiation Therapy is challenging, prompting a need for precision beyond conventional clinical Treatment Planning Systems (TPS). Monte Carlo-based methods are sought for their superior accuracy. The aim of this study is to compare dose distributions between the ACUROS algorithm and the GATE platform in various tissue densities and field sizes, focusing on smaller fields. This study was initiated with a homogeneous validation of the TrueBeam STX system, using measurements obtained from the Centre Hospitalier Interregional Edith Cavell (CHIREC) in Brussels. The validation compared dosimetric functions (Percentage Depth Dose (PDD), Dose profile (DP) and Collimator scatter fraction (CSF)) employing the GAMMA index with a 2% / 2 mm criterion tolerance. Following this, heterogeneous studies examined dose distributions between the ACUROS algorithm and the GATE platform in various tissue densities and field sizes, with a specific focus on smaller fields. Simulations were conducted using both platforms on chest phantoms with heterogeneous slabs representing bone, lung, and heart, each housing a central tumor. The impact of electronic equilibrium on tumors for different small field sizes was evaluated. Results showed a remarkable 99% agreement between measurements and GATE calculations in the homogeneous validation of the TrueBeam STX system. However, in heterogeneous studies, ACUROS consistently overestimated lung doses by up to 8% compared to GATE simulation, especially evident with a flattening filter and smaller beam sizes at density interfaces. This highlights significant dose estimation discrepancies between ACUROS and GATE, emphasizing the need for precise calculations. The findings support exploring Monte Carlo-based methods for enhanced accuracy in Radiation Therapy treatment planning.

Methyl donor micronutrients, hypothalamic development and programming for metabolic disease

Nutriture in utero is essential for fetal brain development through the regulation of neural stem cell proliferation, differentiation, and apoptosis, and has a long-lasting impact on risk of disease in offspring. This review examines the role of maternal methyl donor micronutrients in neuronal development and programming of physiological functions of the hypothalamus, with a focus on later-life metabolic outcomes. Although evidence is mainly derived from preclinical studies, recent research shows that methyl donor micronutrients (e.g., folic acid and choline) are critical for neuronal development of energy homeostatic pathways and the programming of characteristics of the metabolic syndrome in mothers and their children. Both folic acid and choline are active in one-carbon metabolism with their impact on epigenetic modification of gene expression. We conclude that an imbalance of folic acid and choline intake during gestation disrupts DNA methylation patterns affecting mechanisms of hypothalamic development, and thus elevates metabolic disease risk. Further investigation, including studies to determine translatability to humans, is required.

Central glucagon-like peptide 1 receptor activation inhibits Toll-like receptor agonist-induced inflammation

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) exert anti-inflammatory effects relevant to the chronic complications of type 2 diabetes. Although GLP-1RAs attenuate T cell-mediated gut and systemic inflammation directly through the gut intraepithelial lymphocyte GLP-1R, how GLP-1RAs inhibit systemic inflammation in the absence of widespread immune expression of the GLP-1R remains uncertain. Here, we show that GLP-1R activation attenuates the induction of plasma tumor necrosis factor alpha (TNF-α) by multiple Toll-like receptor agonists. These actions are not mediated by hematopoietic or endothelial GLP-1Rs but require central neuronal GLP-1Rs. In a cecal slurry model of polymicrobial sepsis, GLP-1RAs similarly require neuronal GLP-1Rs to attenuate detrimental responses associated with sepsis, including sickness, hypothermia, systemic inflammation, and lung injury. Mechanistically, GLP-1R activation leads to reduced TNF-α via α1-adrenergic, δ-opioid, and κ-opioid receptor signaling. These data extend emerging concepts of brain-immune networks and posit a new gut-brain GLP-1R axis for suppression of peripheral inflammation.

Methylenetetrahydrofolate reductase deficiency and high-dose FA supplementation disrupt embryonic development of energy balance and metabolic homeostasis in zebrafish

Folic acid (synthetic folate, FA) is consumed in excess in North America and may interact with common pathogenic variants in methylenetetrahydrofolate reductase (MTHFR); the most prevalent inborn error of folate metabolism with wide-ranging obesity-related comorbidities. While preclinical murine models have been valuable to inform on diet-gene interactions, a recent Folate Expert panel has encouraged validation of new animal models. In this study, we characterized a novel zebrafish model of mthfr deficiency and evaluated the effects of genetic loss of mthfr function and FA supplementation during embryonic development on energy homeostasis and metabolism. mthfr-deficient zebrafish were generated using CRISPR mutagenesis and supplemented with no FA (control, 0FA) or 100 μm FA (100FA) throughout embryonic development (0-5 days postfertilization). We show that the genetic loss of mthfr function in zebrafish recapitulates key biochemical hallmarks reported in MTHFR deficiency in humans and leads to greater lipid accumulation and aberrant cholesterol metabolism as reported in the Mthfr murine model. In mthfr-deficient zebrafish, energy homeostasis was also impaired as indicated by altered food intake, reduced metabolic rate and lower expression of central energy-regulatory genes. Microglia abundance, involved in healthy neuronal development, was also reduced. FA supplementation to control zebrafish mimicked many of the adverse effects of mthfr deficiency, some of which were also exacerbated in mthfr-deficient zebrafish. Together, these findings support the translatability of the mthfr-deficient zebrafish as a preclinical model in folate research.

Beyond the pancreas: contrasting cardiometabolic actions of GIP and GLP1

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP1) exhibit incretin activity, meaning that they potentiate glucose-dependent insulin secretion. The emergence of GIP receptor (GIPR)-GLP1 receptor (GLP1R) co-agonists has fostered growing interest in the actions of GIP and GLP1 in metabolically relevant tissues. Here, we update concepts of how these hormones act beyond the pancreas. The actions of GIP and GLP1 on liver, muscle and adipose tissue, in the control of glucose and lipid homeostasis, are discussed in the context of plausible mechanisms of action. Both the GIPR and GLP1R are expressed in the central nervous system, wherein receptor activation produces anorectic effects enabling weight loss. In preclinical studies, GIP and GLP1 reduce atherosclerosis. Furthermore, GIPR and GLP1R are expressed within the heart and immune system, and GLP1R within the kidney, revealing putative mechanisms linking GIP and GLP1R agonism to cardiorenal protection. We interpret the clinical and mechanistic data obtained for different agents that enable weight loss and glucose control for the treatment of obesity and type 2 diabetes mellitus, respectively, by activating or blocking GIPR signalling, including the GIPR-GLP1R co-agonist tirzepatide, as well as the GIPR antagonist-GLP1R agonist AMG-133. Collectively, we update translational concepts of GIP and GLP1 action, while highlighting gaps, areas of uncertainty and controversies meriting ongoing investigation.

Anesthesia Patient Safety: Next Steps to Improve Worldwide Perioperative Safety by 2030

Patient safety is a core principle of anesthesia care worldwide. The specialty of anesthesiology has been a leader in medicine for the past half century in pursuing patient safety research and implementing standards of care and systematic improvements in processes of care. Together, these efforts have dramatically reduced patient harm associated with anesthesia. However, improved anesthesia patient safety has not been uniformly obtained worldwide. There are unique differences in patient safety outcomes between countries and regions in the world. These differences are often related to factors such as availability, support, and use of health care resources, trained personnel, patient safety outcome data collection efforts, standards of care, and cultures of safety and teamwork in health care facilities. This article provides insights from national anesthesia society leaders from 13 countries around the world. The countries they represent are diverse geographically and in health care resources. The authors share their countries' current and future initiatives in anesthesia patient safety. Ten major patient safety issues are common to these countries, with several of these focused on the importance of extending initiatives into the full perioperative as well as intraoperative environments. These issues may be used by anesthesia leaders around the globe to direct collaborative efforts to improve the safety of patients undergoing surgery and anesthesia in the coming decade.

Development of a Zebrafish Model for Studies of the Interaction of Methylenetetrahydrofolate Reductase Deficiency and Dietary Folates on Metabolic Regulation

Objectives

Methylenetetrahydrofolate reductase (MTHFR) is required for 5-methyltetrahydrofolate (5MTHF) synthesis, and common variants reduces its efficiency and associate with metabolic disorders. High folic acid (FA) intakes, commonly consumed by pregnant women in North America, may further inhibit MTHFR enzyme; programming long-term metabolic dysregulation in offspring. The zebrafish (Danio rerio) is a valuable model for study of embryonic development and high-throughput nutrient × gene interactions. The objective of this study was to characterize a zebrafish model of mthfr deficiency and assess the interaction between mthfr and FA intakes on early-life metabolic dysregulation.

Methods

Zebrafish were co-injected with a set of 4 guide RNAs (gRNAs) or cas9 protein alone and F0 embryos were assayed for a high-throughput phenotypic screen. Germline F1 knock-out homozygous mutants (mthfr −/−) were made by co-injecting cas9 mRNA with 2 gRNAs targeting the transcriptional start site of the mthfr gene. Embryos were raised up to 5 days post-fertilization (dpf) and folate and 1-carbon metabolites measured by LC-MS/MS. Lipid accumulation was assessed at 5dpf and after feeding a high cholesterol diet (HDC) with cholesteryl-ester (CE)-BoDipy-C12® from 5–15dpf. A subset of embryos were exposed to no (0µM) or high (100µM) FA from 0–5dpf and whole-body lipids measured.

Results

mthfr disruption in zebrafish reduced (80%) mthfr mRNA and 5MTHF levels (90%) compared to controls (P < 0.0001). They had lower 1-carbon metabolites including betaine, methionine, s-adenosylmethionine, and higher choline, s-adenosylhomocysteine, cystathionine and homocysteine (P < 0.01). As well, neutral lipid accumulation was higher in liver, heart and vasculature at 5 and 15 dpf along with higher CE altered cholesterol transport/metabolism. High FA exposure ameliorated lipid accumulation in mthfr mutants at 5 dpf (P = 0.06), but increased lipids accumulation in controls compared to no exposure (P = 0.03).

Conclusions

The zebrafish mthfr deficient model exhibits a similar alteration to 1-carbon metabolites as in humans with severe MTHFR deficiency. This zebrafish model has potential for understanding the interaction of mthfr deficiency and dietary folates on metabolism.

Funding Sources

CIHR-INMD, EP by NSERC-CGS

High Choline During Pregnancy Reduces Characteristics of the Metabolic Syndrome in Male Wistar Rat Offspring Fed a High Fat Post-Weaning Diet

Objectives

The prenatal period is a critical time for fetal development, programming the offspring's later-life health in response to the postnatal environment. We have shown that a high maternal choline diet programs long-term energy regulation leading to higher food intake and weight-gain in mature rat offspring fed a normal fat diet. However, the offspring's response to an obesogenic post-weaning diet has not been described. We aim to elucidate the interaction between the choline content of the gestational diet (GD) and fat content of the post-weaning diet (PWD) on male Wistar rat offspring's long-term metabolic phenotype.

Methods

Pregnant Wistar rats were fed an AIN-93G diet with either recommended choline (RC, 1g/kg diet choline bitartrate) or high choline (HC, 2.5-fold). Male pups were weaned to either a normal (10%) fat (RC-NF and HC-NF) or a high (45%) fat (RC-HF and HC-HF) diet for 17 weeks. Dependent measures were body weight, food intake, visceral adiposity, plasma glucoregulatory hormones and triglycerides, and plasma and hepatic free fatty acids (FFAs). Data were analyzed with 2-way ANOVA for main effects of GD and PWD and their interaction. Measures with significant interaction effects were followed by a Student's T-test comparing groups stratified by PWD.

Results

HC-HF offspring had lower body weight (7%, P < 0.05), and visceral adiposity (15%, P < 0.05), but no difference in food intake compared to RC-HF. HC-HF offspring had lower insulin (18%, P < 0.05), HOMA-IR (24%, P < 0.01), and plasma triglycerides (30%, P < 0.05) but no difference in leptin. Total hepatic ω-3 FFAs (30%, P < 0.05) were higher and ω-6/ω-3 (P < 0.01) was lower in HC-HF compared to RC-HF, indicating an ameliorated metabolic phenotype in HC-HF offspring. In contrast, HC-NF offspring had higher food intake (8%, P < 0.01) and body weight (6%, P < 0.05) and no difference in adiposity compared to RC-NF. They also had higher plasma leptin adjusted for adiposity (22%, P < 0.05) but not insulin or HOMA-IR compared to RC-NF. Hepatic C16:1n-7/C16:0 ratio was higher in HC-NF compared to RC-NF, suggestive of dysregulated lipid metabolism.

Conclusions

Gestational choline supplementation is associated with improved long-term metabolic regulation in male Wistar rat offspring fed a high fat post-weaning diet.

Funding Sources

CIHR-Institute of Nutrition, Metabolism, and Diabetes.

Methylenetetrahydrofolate Reductase Deficiency Reduces Brain Microglia in Zebrafish During Embryonic Development and Is Not Corrected by Folic Acid

Objectives

Neuronal development and function is dependent on the interaction between the central nervous system and immune system. Microglia are resident macrophages of the brain critical for regulating neuronal activity during embryonic development. 5-methyltetrahydrofolate (5MTHF), the bioactive folate form, is essential for fetal brain development and immune function. Common variants in methylenetetrahydrofolate reductase (MTHFR), required for conversion of folic acid (FA) to 5-MTHF, limits its production. High dose FA supplementation is recommended but high FA may have the converse effect of reducing MTHFR activity. The objective of this study was to determine the effects of mthfr deficiency and its interaction with FA during embryonic development on microglia in a zebrafish model.

Methods

The mthfr gene in zebrafish was disrupted using two CRISPR mutagenesis methods. A set of 4 guide RNAs (gRNAs) + cas9 protein or cas9 alone (control) were injected to assay F0 zebrafish, or 2 gRNAs + cas9 mRNA were used to induce a germline mutation. To visualize macrophages at 4 days post fertilization (dpf) in live zebrafish, the transgenic mpeg1: mcherry line was used. In a subset of embryos, FA was added at 0, 50, 75, or 100- μM from 0–4dpf. At 4dpf, live neutral red staining for microglia was performed and the number in the optic tectum was quantified. 5MTHF, s-adenosylmethionine (SAM) and s-adenosylhomocysteine (SAH) were assayed in whole zebrafish at 5dpf.

Results

In vivo imaging revealed a reduction in macrophage number (∼30%, P < 0.001) in the head region of mthfr disrupted zebrafish, but not in the periphery. mthfr zebrafish also had less microglia compared to controls (15%, P < 0.001). These changes were associated with lower 5MTHF (90%, P < 0.0001) and SAM: SAH (∼50%, P < 0.001) at 5dpf indicative of lower methylation potential. Exposure with FA did not correct the phenotype and at 100µM FA, control zebrafish also showed a decrease in microglia similar to mthfr zebrafish, confirming inhibitory effects of the high FA dose.

Conclusions

mthfr deficiency reduces microglia in zebrafish but supplementation with FA does not prevent and may exacerbate the negative effects. The 5MTHF form of folate may be a better alternative to FA for brain health in patients with underlying genetic conditions.

Funding Sources

Supported by CIHR-INMD.

High 5-Methyletetrahydrofolate and Folic Acid Gestational Diets Differ on Leptin-Dependent Hypothalamic Genes Regulating Food Intake in Female Offspring

Objectives

While the replacement of folic acid (FA) with the bioactive folate form 5-methyltetrahydrofolate (MTHF) is gaining popularity, a comparison of their effects during pregnancy is limited. In a comparison of maternal intakes of FA and MTHF at recommended or high (5X) doses in Wistar rat dams, we found that dams fed 5X MTHF gained > 70% more weight and ate 8% more food to 19-weeks post weaning (PW) than those fed the high FA diet (Nutrients. 2021;13:48). However, both high dose diets resulted in dysregulation of leptin and central energy regulatory systems. The objective of this study was to compare the effect of gestational FA and MTHF diets on metabolic response and leptin-dependent hypothalamic energy-regulatory genes in the brain of their female offspring.

Methods

Pregnant Wistar rats were fed an AIN-93G diet with 1X recommended (2mg/kg diet) or 5X FA or equimolar MTHF. At weaning, female offspring were fed a high-fat diet until 19-weeks PW. Body weight, food intake, adiposity, plasma leptin, and gene expression of leptin signaling and related candidate genes in the hypothalamus were measured.

Results

Similar to the mothers, the 5X-MTHF gestational diet resulted in offspring with higher weight (>15%, P < 0.01) independent of visceral adiposity, and higher food intake (8% P < 0.01) compared to those born to dams fed the 5X-FA, but not from the 1X folate diets. Both 5X diets led to higher plasma leptin at birth (60%, P < 0.05) and at 19-weeks PW (40%, P < 0.01) and up-regulated hypothalamic mRNA of the downstream leptin signalling gene, signal transducer and activator of transcription-3 (Stat3). However, only 5X-MTHF offspring had lower expression of leptin receptor (Ob-rB) and higher expression of suppressor of cytokine signaling-3 (Socs-3), an inhibitor of leptin signalling and indicator of central leptin resistance. In contrast, 5X-FA offspring had higher expression (>1.5-fold, P < 0.01) of dopamine and GABA- receptors which are targets of leptin and associated with feeding inhibition and hyperactivity.

Conclusions

Folate form and dose during pregnancy affects long-term programming of leptin dependent hypothalamic regulatory pathways in female offspring. Unfavorable differences in response to FA and MTHF were seen at the higher doses, thus neither should be consumed at high intakes.

Funding Sources

CIHR-INMD; EP by NSERC-CGS.

Effects of a 'Baby-Friendly Hospital Initiative' on exclusive breastfeeding rates at a private hospital in Lebanon: an interrupted time series analysis

Background

Exclusive breastfeeding (EBF) through six months of age has been scientifically validated as having a wide range of benefits, but remains infrequent in many countries. The WHO/UNICEF Baby-Friendly Hospital Initiative (BFHI) is one approach to improve EBF rates.

Methods

This study documents the implementation of BFHI at Clemenceau Medical Center (CMC), a private hospital in Lebanon, and analyzes data on EBF practices among CMC’s patients before, during, and after the implementation period. The process of launching the BFHI at CMC is discussed from the perspective of key stakeholders using the SQUIRE guidelines for reporting on quality improvement initiatives. As an objective measure of the program’s impact, 2,002 live births from July 2015 to February 2018 were included in an interrupted time series analysis measuring the rates of EBF at discharge prior to, during, and following the bundle of BFHI interventions.

Results

The steps necessary to bring CMC in line with the BFHI standards were implemented during the period between November 2015 and February 2016. These steps can be grouped into three phases: updates to hospital policies and infrastructure (Phase 1); changes to healthcare staff practices (Phase 2); and improvements in patient education (Phase 3). The baseline percentage of EBF was 2.4 % of all live births. Following the BFHI intervention, the observed monthly change in EBF in the “Follow-Up” period (i.e., the 24 months following Phases 1–3) was significantly increased relative to the baseline period (+ 2.0 % points per month, p = 0.006). Overall, the observed rate of EBF at hospital discharge increased from 2.4 to 49.0 % of all live births from the first to the final month of recorded data.

Conclusions

Meeting the BFHI standards is a complex process for a health facility, requiring changes to policies, practices, and infrastructure. Despite many challenges, the results of the interrupted time series analysis indicate that the BFHI reforms were successful in increasing the EBF rate among CMC’s patients and sustaining that rate over time. These results further support the importance of the hospital environment and health provider practices in breastfeeding promotion, ultimately improving the health, growth, and development of newborns.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03816-3.

High Intakes of [6S]-5-Methyltetrahydrofolic Acid Compared with Folic Acid during Pregnancy Programs Central and Peripheral Mechanisms Favouring Increased Food Intake and Body Weight of Mature Female Offspring

Supplementation with [6S]-5-methyltetrahydrofolic acid (MTHF) is recommended as an alternative to folic acid (FA) in prenatal supplements. This study compared equimolar gestational FA and MTHF diets on energy regulation of female offspring. Wistar rats were fed an AIN-93G diet with recommended (2 mg/kg diet) or 5-fold (5X) intakes of MTHF or FA. At weaning, female offspring were fed a 45% fat diet until 19 weeks. The 5X-MTHF offspring had higher body weight (>15%), food intake (8%), light-cycle energy expenditure, and lower activity compared to 5X-FA offspring (p < 0.05). Both the 5X offspring had higher plasma levels of the anorectic hormone leptin at birth (60%) and at 19 weeks (40%), and lower liver weight and total liver lipids compared to the 1X offspring (p < 0.05). Hypothalamic mRNA expression of leptin receptor (ObRb) was lower, and of suppressor of cytokine signaling-3 (Socs3) was higher in the 5X-MTHF offspring (p < 0.05), suggesting central leptin dysregulation. In contrast, the 5X-FA offspring had higher expression of genes encoding for dopamine and GABA- neurotransmitter receptors (p < 0.01), consistent with their phenotype and reduced food intake. When fed folate diets at the requirement level, no differences were found due to form in the offspring. We conclude that MTHF compared to FA consumed at high levels in the gestational diets program central and peripheral mechanisms to favour increased weight gain in the offspring. These pre-clinical findings caution against high gestational intakes of folates of either form and encourage clinical trials examining their long-term health effects when consumed during pregnancy.

High Choline Intake during Pregnancy Reduces Characteristics of the Metabolic Syndrome in Male Wistar Rat Offspring Fed a High Fat But Not a Normal Fat Post-Weaning Diet

Maternal choline intakes are below recommendations, potentially impairing the child’s later-life metabolic health. This study aims to elucidate the interaction between the choline content of the gestational diet (GD) and fat content of the post-weaning diet (PWD) on metabolic phenotype of male Wistar rats. Pregnant Wistar rats were fed a standard rodent diet (AIN-93G) with either recommended choline (RC, 1 g/kg diet choline bitartrate) or high choline (HC, 2.5-fold). Male pups were weaned to either a normal (16%) fat (NF) or a high (45%) fat (HF) diet for 17 weeks. Body weight, visceral adiposity, food intake, energy expenditure, plasma hormones, triglycerides, and hepatic fatty acids were measured. HC-HF offspring had 7% lower body weight but not food intake, and lower adiposity, plasma triglycerides, and insulin resistance compared to RC-HF. They also had increased hepatic n-3 fatty acids and a reduced n-6/n-3 and C 18:1 n-9/C18:0 ratios. In contrast, HC-NF offspring had 6–8% higher cumulative food intake and body weight, as well as increased leptin and elevated hepatic C16:1 n-7/C16:0 ratio compared to RC-NF. Therefore, gestational choline supplementation associated with improved long-term regulation of several biomarkers of the metabolic syndrome in male Wistar rat offspring fed a HF, but not a NF, PWD.

Choline and Folic Acid in Diets Consumed during Pregnancy Interact to Program Food Intake and Metabolic Regulation of Male Wistar Rat Offspring

BACKGROUND

North American women consume high folic acid (FA), but most are not meeting the adequate intakes for choline. High-FA gestational diets induce an obesogenic phenotype in rat offspring. It is unclear if imbalances between FA and other methyl-nutrients (i.e., choline) account for these effects.

OBJECTIVE

This study investigated the interaction of choline and FA in gestational diets on food intake, body weight, one-carbon metabolism, and hypothalamic gene expression in male Wistar rat offspring.

METHODS

Pregnant Wistar rats were fed an AIN-93G diet with recommended choline and FA [RCRF; 1-fold, control] or high (5-fold) FA with choline at 0.5-fold [low choline and high folic acid (LCHF)], 1-fold [recommended choline and high folic acid (RCHF)], or 2.5-fold [high choline and high folic acid (HCHF)]. Male offspring were weaned to an RCRF diet for 20 wk. Food intake, weight gain, plasma energy-regulatory hormones, brain and plasma one-carbon metabolites, and RNA sequencing (RNA-seq) in pup hypothalamuses were assessed.

RESULTS

Adult offspring from LCHF and RCHF, but not HCHF, gestational diets had 10% higher food intake and weight gain than controls (P < 0.01). HCHF newborn pups had lower plasma insulin and leptin compared with LCHF and RCHF pups (P < 0.05), respectively. Pup brain choline (P < 0.05) and betaine (P < 0.01) were 22-33% higher in HCHF pups compared with LCHF pups; methionine was ∼23% lower after all high FA diets compared with RCRF (P < 0.01). LCHF adult offspring had lower brain choline (P < 0.05) than all groups and lower plasma 5-methyltetrahydrofolate (P < 0.05) than RCRF and RCHF groups. HCHF adult offspring had lower plasma cystathionine (P < 0.05) than LCHF adult offspring and lower homocysteine (P < 0.01) than RCHF and RCRF adult offspring. RNA-seq identified 144 differentially expressed genes in the hypothalamus of HCHF newborns compared with controls.

CONCLUSIONS

Increased choline in gestational diets modified the programming effects of high FA on long-term food intake regulation, plasma energy-regulatory hormones, one-carbon metabolism, and hypothalamic gene expression in male Wistar rat offspring, emphasizing a need for more attention to the choline and FA balance in maternal diets.

High 5MTHF, but Not Folic Acid During Pregnancy, Alters Hypothalamic Regulatory Pathways and Associates with Post-Partum Weight-Gain in Wistar Rat Mothers

Objectives

5-methyltetrahydrofolate (5MTHF), the bioactive folate form, has been proposed an alternative supplement to folic acid (FA) due to direct cellular uptake and utilization. In North America, 5MTHF is incorporated into prenatal supplements at the equivalent high dose (1000 µg) as FA and discussion has been raised of its formation into baby formula. Our lab was the first to compare the dose (1X vs high, 5X) and form (FA vs 5MTHF) effects of folate during pregnancy on later-life metabolic health of the Wistar rat mother. Contrary to our hypothesis, 5MTHF diets, independent of dose, led to mothers with 40% greater body weight-gain and higher food intake post-birth compared to FA. The objective of this study was to identify differentially expressed genes and related hypothalamic pathways of mothers fed FA vs 5MTHF diets during pregnancy.

Methods

Pregnant Wistar rats were fed an AIN-93 G diet with recommended (1X, control, 2 mg/kg diet) or high (5X) FA or equimolar levels of 5MTHF. At birth, a subset of dams were terminated and RNA-seq analysis was performed in the arcuate nucleus of the hypothalamus (ARC), a key regulator of body weight and food intake, in dams fed the high FA and MTHF diets.

Results

Over 350 differentially expressed genes were identified in the ARC of dams fed high 5MTHF vs FA diets. Combining differential gene expression patterns with reported GO function terms and Kegg pathway analyses, four candidate genes (prolactin hormone receptor, corticotropin releasing hormone receptor, KISS1 peptide and dopamine receptor) were validated by qPCR thus far as plausible contributors to higher body weight-gain and food intake in 5MTHF dams. These genes correspond to neuroactive ligand-receptor interaction pathway (path: hsa04080), associated with metabolic diseases including leptin deficiency and genetic obesity. Other significantly enriched pathways included the retrograde endocannabinoid signalling and morphine addiction pathway.

Conclusions

High 5MTHF supplementation during pregnancy alters expression of central feeding regulatory pathways in the hypothalamus of the mother, potentially programming post-partum body-weight gain. 5MTHF, at the equivalent dose of FA, may not be the preferred folate form during pregnancy.

Funding Sources

CIHR-INMD; EP supported by NSERC-CGS D.

Choline Supplementation Mitigates the Adverse Effects of a High Folic Acid Maternal Diet on Food Intake Regulation in the Offspring

Objectives

Folic acid (FA) intake by many women in North America is exceeding recommendations. We have shown that high maternal FA induces methylation-dependent programming of energy regulation associated with an obesogenic phenotype in adult rat offspring. However, it is unclear if this is a direct effect of high FA or due to an imbalance between FA and other methyl-nutrients (i.e., choline) in the 1-carbon cycle. Unlike FA, choline intake by women is below recommendations and is absent from most prenatal supplements, potentially affecting fetal development. The objective of this study was to examine the mechanisms and effects of choline content in high FA maternal diets on in-utero programming of energy regulation and later-life offspring phenotype.

Methods

Pregnant Wistar rats were fed an AIN-93 G diet with recommended FA and choline (1X, RFRC, control), or 5X-FA diet with choline at 0.5X-(HFLC), 1X-(HFRC), or 2.5X- (HFHC). In pups at birth, brain and liver 1-carbon metabolites, hypothalamic DNA methyltransferase (DNMT) activity and global DNA methylation (5-mC%) were measured. At weaning, one male pup/dam was fed the control diet and weekly weight-gain and food intake were recorded for 20 weeks.

Results

Offspring born to dams on the HFLC and HFRC, but not HFHC diet, had higher food intake (P &lt; 0.05) and weight-gain (P &lt; 0.01) than controls. In liver at birth, free choline was lower in HFHC than in HFLC pups, but betaine was unaffected. In contrast, in brains, betaine but not free choline concentrations, directly reflected the maternal choline diets. These results suggest that choline may modulate central food intake pathways via the methyl-donor betaine, warranting further investigation. Hypothalamic DNMT activity was highest (P &lt; 0.05) in HFLC pups but global methylation was not affected. Thus, gene expression by RNA sequencing and gene-specific methylation in the hypothalamus is in progress to elucidate the mechanisms underlying the observed phenotype.

Conclusions

Increased maternal choline mitigates the high FA diet induced increase in body weight and food intake in the adult offspring and results in tissue-specific changes in 1-carbon metabolism at birth. These findings have potential application to human health, providing support to optimize choline and FA intakes by women of childbearing age.

Funding Sources

CIHR-INMD.

The Zebrafish (Danio Rerio) as a Novel Model to Study Folate-mthfr Interactions During Embryonic Development and Effect(s) on Long-Term Health

Objectives

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the synthesis of the bioactive folate form, 5-methyltetrahydrofolate (5MTHF). Common polymorphisms in MTHFR limits the availability of 5MTHF and high intakes of folic acid (FA, synthetic form) may exacerbate these effects. 5MTHF is an alternative supplement to FA, but the interaction of folate form and MTHFR genotype and role in programming metabolic health has not been determined. The zebrafish (Danio rerio) is a proven model system in nutrient and drug discovery studies. The objectives of this study were to: 1) develop a mthfr zebrafish mutant model using CRISPR-Cas9 technology; and 2) identify in zebrafish the relationship between folate form (FA vs 5MTHF) and mthfr genotype on early-life development and metabolic regulation.

Methods

To assay the function of mthfr in vivo, we used a rapid transient knock-out approach reported to recapitulate germline zebrafish loss-of-function phenotypes. Embryos were co-injected with Cas9 protein and a set of 4 guide RNAs (4gRNA) or Cas9 protein alone (control). Zero to 5 days post-fertilization (dpf), embryos were raised in standard conditions then fed a high cholesterol diet (HCD) up to 15 dpf with a fluorescent cholesteryl BODIPY-C12. The HCD was used to induce obesity as previously reported. Global DNA methylation (5-mC%) was measured at 5 dpf and whole-body and hepatic lipid accumulation and live imaging analyses performed at 15 dpf.

Results

Compared to control, 4gRNA mthfr zebrafish on an HCD had enlarged liver, greater accumulation of hepatic and whole body lipids and altered lipid transport. They also had 80% lower mthfr mRNA than control zebrafish. Global methylation was ∼15% higher (P = 0.06) in 4gRNA zebrafish suggesting a compensatory dependency on an alternative methyl donor pathway during embryonic development. We are now screening germline mutant carriers and assessing folate and methylation metabolites and the interaction of folate form and genotype.

Conclusions

The zebrafish mthfr mutant will be a valuable model to examine the mechanisms underlining mthfr-related pathologies and provide a high-throughput in vivo system to ascertain the role of different folate forms on embryonic development and long-term health.

Funding Sources

CIHR-INMD; EP supported by NSERC-CGS D.

Maternal Choline Intake Programs Hypothalamic Energy Regulation and Later-Life Phenotype of Male Wistar Rat Offspring

SCOPE

High-folic-acid diets during pregnancy result in obesity in the offspring, associated with altered DNA-methylation of hypothalamic food intake neurons. Like folic acid, the methyl-donor choline modulates foetal brain development, but its long-term programing effects on energy regulation remain undefined. This study aims to describe the effect of choline intake during pregnancy on offspring phenotype and hypothalamic energy-regulatory mechanisms.

METHODS AND RESULTS

Wistar rat dams are fed an AIN-93G diet with recommended choline (RC, 1 g kg^-1 diet), low choline (LC, 0.5-fold), or high choline (HC, 2.5-fold) during pregnancy. Male pups are terminated at birth and 17 weeks post-weaning. Brain 1-carbon metabolites, body weight, food intake, energy expenditure, plasma hormones, and protein expression of hypothalamic neuropeptides are measured. HC pups have higher expression of the orexigenic neuropeptide-Y neurons at birth, consistent with higher cumulative food intake and body weight gain post-weaning compared to RC and LC offspring. LC pups have lower leptin receptor expression at birth and lower energy expenditure and activity during adulthood.

CONCLUSION

Choline content of diets that are consumed by rats during pregnancy affects the later-life phenotype of offspring, associated with altered in utero programing of hypothalamic food intake regulation.

5-Methyltetrahydrofolate in Maternal Diets Alters DNA Methylation Potential and Increases Later Life Weight Gain and Food Intake in Wistar Rat Dams and Female Offspring (P11-022-19)

Objectives

Diet during pregnancy programs the mother and offspring post-weaning (PW). Folic acid (FA, synthetic folate) mediates DNA methylation (DNAm) reactions and high intakes, simulating those consumed by American women, lead to epigenetic dysregulation of energy metabolic pathways. 5-methyltetrahydrofolate (5MTHF), the bioactive folate form, has gained popularity as a supplement due to direct cellular uptake and utilization and does not increase unmetabolized FA (UMFA). However, a comparison of folate forms on in utero programming of offspring or maternal health has not been reported. Our objectives were to compare the effects of folate dose (low vs high) and form (FA vs 5MTHF) during pregnancy on DNAm potential, and the early and later PW phenotype of Wistar rat mothers and female offspring (mothers-to-be).

Methods

Pregnant Wistar rats (n = 22/group) were fed an AIN93G diet with recommended FA (1X, 2mg/kg diet), 5X-FA or equimolar 5MTHF. Dams were fed 1X-FA during lactation and then dams and female pups were fed a high fat diet for 19 weeks. Weight gain (WG), food intake (FI), energy expenditure (EE), insulin resistance (IR), plasma 5MTHF, UMFA, homocysteine (tHcy), and hepatic S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) and DNA methyltransferases (DNMT) activity at birth and PW were measured.

Results

Dams fed 5MTHF diets had lower DNMT activity at birth and female pups had higher SAM: SAH ratios (P < 0.05) indicative of altered DNAm potential compared to FA diets. Plasma 5MTHF at birth was dose dependent with 5X diets leading to higher levels than 1X diets (P < 0.001) in dams and pups. In contrast, UMFA was only higher in 5X-FA dams. 5MTHF dams had higher tHcy at birth and were more IR at 1 week PW than FA fed dams (P < 0.05). In both dams and offspring, high 5MTHF also led to higher WG (> 15%, P < 0.001) and FI (> 5%, P < 0.001) compared to high FA diets up to 19 weeks. EE (P < 0.05) was higher suggesting a compensatory response to WG. 5X-MTHF dams, but not offspring, also had greater hepatic lipids (P < 0.05) than other groups.

Conclusions

Folate dose and form during pregnancy affects DNAm potential at birth and early and later phenotype of dams and female offspring. High 5MTHF increases WG, FI and hepatic lipids PW suggesting it may not be the preferred form for prenatal supplements or additions to the food supply.

Funding Sources

Supported by CIHR-INMD; EP supported by NSERC-CGS D.

Choline and Folic Acid Balance in Diets During Pregnancy Programs Food Intake Regulation in Wistar Rat Offspring (FS08-05-19)

Objectives

High gestational folic acid (FA) induces an obesogenic phenotype in male Wistar rat offspring. Imbalances between FA and other methyl-nutrients (i.e., choline) leading to perturbations in the 1-carbon cycle may account for the effects of high FA diets. Canadian women consume high (2–7-fold) intakes of FA, but most are not meeting recommended adequate intakes for choline. Choline is also absent from Canadian prenatal supplements. The objective of this study is to evaluate the effects of the interaction between choline and FA in maternal diets of rats on the 1-carbon cycle, and the programming of food intake, body weight gain and biomarkers of obesity in the offspring later in life.

Methods

Pregnant Wistar rat dams were fed the AIN-93 G diet with recommended (1X) choline and FA (RCRF, control), or a 5X FA diet with either 0.5X choline (LCHF), 1X choline (RCHF), or 2.5X choline (HCHF). Brain and blood were collected at birth. At weaning one male pup/dam from all groups was maintained on the control diet for 20 weeks then terminated. Dependent measures include weekly body weight-gain and food intake, plasma glucoregulatory hormones and 1-carbon metabolites at birth and post-weaning.

Results

Increasing choline content to 2.5-fold in a high (5-fold) gestational FA diet (HCHF) led to lower plasma insulin and leptin levels at birth compared to the LCHF and RCHF diets, respectively (P < 0.05). It also led to lower (25%, P = 0.03) plasma 5-methyltetrahydrofolate concentrations at birth compared to the RCHF diet, suggesting more efficient utilization of FA. Offspring born to dams maintained on a high folic acid diet with either low or recommended choline had higher weekly food intake (6%, P < 0.05) and body weight-gain (9%, P < 0.01). In contrast, offspring from dams fed the HCHF gestational diet were not different from those born to dams fed the RCRF (control) diet, highlighting the mitigating effects of a balanced choline and FA gestational diet.

Conclusions

Increased intakes of choline mitigate the effects of high FA diets. Maternal dietary choline interacts with FA on the long-term programming of food intake regulation in the offspring; emphasizing a need for more attention to improving choline intakes by women of child-bearing age.

Funding Sources

This research was funded by the Canadian Institute of Health Research, Institute of Nutrition, Metabolism and Diabetes (CIHR-INMD).

Maternal Choline Intake Programs Hypothalamic Energy Regulatory Pathways and Long-Term Phenotype in Male Wistar Rat Offspring (OR35-04-19)

Objectives

The prenatal period is a critical time of brain development. Maternal choline intake is associated with improvement in memory and cognitive function in the offspring. However, the role of choline in the regulation of physiological functions controlled by the hypothalamus has not been reported. The objective of this study is to elucidate the effects of choline intake on the in utero programming of hypothalamic energy regulatory neurons in male Wistar rat offspring.

Methods

Pregnant Wistar rats received an AIN-93G diet containing recommended choline (RC, 1 g/kg diet), low choline (LC, 0.5-fold), or high choline (HC, 2.5-fold). At birth, brain and blood was collected from male pups. Male pups from each dietary treatment were maintained on the control diet for 17-weeks. Dependent measures include post-weaning food intake, energy expenditure, weight-gain, plasma glucoregulatory hormones, brain choline and 1-carbon metabolite levels, and expression of hypothalamic energy regulatory neurons.

Results

At birth, pup brain concentrations of choline proportionally reflected the choline content in the maternal diets. HC pups had higher hypothalamic protein expression of the orexigenic neuropeptide-Y neuron than both groups (P < 0.05), but lower activation than LC pups (P < 0.05). Both HC and LC pups had lower plasma leptin concentrations than RC pups (P < 0.01), but LC pups had lower hypothalamic leptin receptor expression compared to both groups at birth (P < 0.05). During adulthood, offspring of HC dams had higher weekly food intake compared to RC (11%, P < 0.01), and higher weight-gain than both RC and LC groups (12%, P < 0.05). LC offspring had lower 24hr energy expenditure and locomotor activity than HC and RC groups (6%, P < 0.05).

Conclusions

Choline content of diets consumed by rats during pregnancy impacts in utero development of hypothalamic energy regulatory systems; long-term body weight-gain, food intake and energy expenditure in mature rat offspring.

Funding Sources

This research was supported by the Canadian Institute of Health Research, Institute of Nutrition, Metabolism and Diabetes (CIHR-INMD).

Dietary Intakes of Folic Acid During Pregnancy Determines Maternal Re-Set of Metabolism Post-Birth in Wistar Rat Dams (FS08-06-19)

Objectives

Nutrition during pregnancy alters the “re-set” of maternal metabolism and in turn the mother's metabolic phenotype later in life. Folic acid (FA, synthetic folate) consumed at intakes above requirements during pregnancy by rats leads to increased weight gain and altered DNA methylation in central and peripheral pathways regulating food intake. The objectives of this study were to examine the effects of intakes below and above FA dietary requirements on the re-set of energy metabolic pathways in Wistar rat mothers early post-birth.

Methods

Pregnant Wistar rats (n = 12/group) were fed an AIN93G diet with 5 levels of FA: 0X, 1X (control, 2 mg FA/kg), 2.5X, 5X or 10X. Dams were fed 1X-FA during lactation up to 1-week post-weaning (PW) when maternal metabolism is thought to re-set to homeostasis and then terminated. Weekly body weight, food intake, expression of hypothalamic food-intake neurons, mRNA and protein expression of folate-related and energy metabolic genes, and glucoregulatory hormones were measured. The homeostatic model assessment of insulin resistance (HOMA-IR) was used as a surrogate index of insulin resistance.

Results

Below (0X) and above (5X and 10X) FA requirements during pregnancy suppressed expression of hepatic folate metabolism (methyltetrahydrofolate (MTHF) reductase, and methionine synthase; P < 0.05) genes and led to higher 5-MTHF (P < 0.005) in blood compared to control suggesting dysregulation of 1-carbon pathways. Dams fed 0X- and 5X-FA also had higher plasma insulin and HOMA-IR than controls and changes in glucose and lipid metabolism-regulating genes in muscle (Glucose transporter-4, and Peroxisome-proliferator activated receptors; P < 0.05) but not liver or adipose at 1-week PW. The diets did not affect expression of hypothalamic food intake neurons nor body weight or food intake of the dams from birth to 1-week PW.

Conclusions

FA below (0X) or above (5X, 10X) requirements during pregnancy induce dysregulation of 1-carbon pathways and delay re-set of energy metabolic pathways in Wistar rat dams by 4-weeks after birth, potentially programming long-term negative metabolic effects.

Funding Sources

This research was supported by: Canadian Institute of Health Research, Institute of Nutrition, Metabolism and Diabetes (CIHR-INMD); EP supported by NSERC Alexander Graham Bell Canada Graduate Scholarships-Doctoral Program (CGS D).

Gestational folic acid content alters the development and function of hypothalamic food intake regulating neurons in Wistar rat offspring post-weaning

Background: Folic acid plays an important role in early brain development of offspring, including proliferation and differentiation of neural stem cells known to impact the function of food intake regulatory pathways. Excess (10-fold) intakes of folic acid in the gestational diet have been linked to increased food intake and obesity in male rat offspring post-weaning.Objective: The present study examined the effects of folic acid content in gestational diets on the development and function of two hypothalamic neuronal populations, neuropeptide Y (NPY) and pro-opiomelanocortin (POMC), within food intake regulatory pathways of male Wistar rat offspring at birth and post-weaning.Results: Folic acid fed at 5.0-fold above recommended levels (5RF) to Wistar dams during pregnancy increased the number of mature NPY-positive neurons in the hypothalamus of male offspring, compared to control (RF), 0RF, 2.5RF, and 10RF at birth. Folic acid content had no effect on expression and maturation of POMC-positive neurons. Body weight and food intake were higher in all treatment groups (2.5-, 5.0-, and 10.0-fold folic acid) from birth to 9 weeks post-weaning compared to control. Increased body weight and food intake at 9-weeks post-weaning were accompanied by a reduced activation of POMC neurons in the arcuate nucleus (ARC).Conclusion: Gestational folic acid content modulates expression of mature hypothalamic NPY-positive neurons at birth and activation of POMC-positive neurons at 9-weeks post-weaning in the ARC of male Wistar rat offspring which may contribute to higher body weight and food intake later in life.

Obstruction of a non-resterilized reinforced endotracheal tube during craniotomy under general anesthesia

Many cases of reinforced endotracheal tube (ETT) obstruction were reported in the literature. In most of these cases, the obstruction was related to the use of a resterilized tube with or without the use of nitrous oxide (N₂O). Resterilization and autoclaving of the tube may result in dissection or formation of a bleb between the two layers of the tube that may expand after the use of N₂O. We describe a case of acute non-resterilized reinforced ETT obstruction, by bleb formation, during occipital craniotomy under general anesthesia.

SU-E-T-649: Evaluation of RapidArc- Based Stereotactic Cranial Radiotherapy Plans with MU Objective Using Multiple Non Coplanar Arcs in Comparison with Conventional Dynamic Conformal Arc Technique

PURPOSE

Previous researches reported that RapidArc plans for stereotactic cranial radiotherapy have two to three times more MUs as compared to Conventional Dynamic Conformal Arc (DCA) Technique. This study aims to evaluate RapidArc plans using multiple non- coplanar arcs, developed with MU objective constraint in the optimization stage.

METHODS

Five single brain metastasis and three multiple metastases cases previously planned using DCA techniques in BrainLab iPlan Version 4.1 were investigated in this study. For each case, the target was defined on CT-MR fused images in iPlan. The CT images and contours of these patients were exported from iPlan to Varian Eclipse TPS Version 8.6. For each case, a DCA plan and a RapidArc plan with multiple non-coplanar arcs with and without using MU objective in the optimization stage were generated using Varian Trilogy machine with Millennium 120 MLC keeping the same prescription and critical structure dose limits. All plans were evaluated according to Conformity Index (CI-modified Paddick) Homogeneity Index (HI), and the normal tissue volume receiving various dose levels (V80%, V50%, V25% and V10%).

RESULTS

In all the plans, the target objectives were met and dose to OARs was within tolerance dose constraints. RapidArc plans with and without MU objective showed better CI and HI as supposed to DCA plans. V80%, V50%, V25% and V10% of normal tissue for RapidArc plans are equal or lesser than DCA plans. Single isocentre RapidArc plan for closely spaced multiple metastases cases showed better dose fall off between the lesions as supposed to DCA plans. RapidArc plans with MU objective resulted in comparable MUs as that of DCA plans.

CONCLUSIONS

Our study showed RapidArc plans done with and without MU objective have no significant dosimetric difference in plan objectives. Therefore, multiple non-coplanar RapidArc plans with MU objective is clinically feasible and can provide better treatment plans than conventional DCA plans, especially for complicated cases.