Delta like 4 regulates cerebrovascular development and endothelial integrity via DLL4-NOTCH-CLDN5 pathway and is vulnerable to neonatal hyperoxia.

The mechanisms governing brain vascularization during development remain poorly understood. A key regulator of developmental vascularization is delta like 4 (DLL4), a Notch ligand prominently expressed in endothelial cells (EC). Exposure to hyperoxia in premature infants can disrupt the development and functions of cerebral blood vessels and lead to long-term cognitive impairment. However, its role in cerebral vascular development and the impact of postnatal hyperoxia on DLL4 expression in mouse brain EC have not been explored. We determined the DLL4 expression pattern and its downstream signalling gene expression in brain EC using Dll4+/+ and Dll4+/LacZ mice. We also performed in vitro studies using human brain microvascular endothelial cells. Finally, we determined Dll4 and Cldn5 expression in mouse brain EC exposed to postnatal hyperoxia. DLL4 is expressed in various cell types, with EC being the predominant one in immature brains. Moreover, DLL4 deficiency leads to persistent abnormalities in brain microvasculature and increased vascular permeability both in vivo and in vitro. We have identified that DLL4 insufficiency compromises endothelial integrity through the NOTCH-NICD-RBPJ-CLDN5 pathway, resulting in the downregulation of the tight junction protein claudin 5 (CLDN5). Finally, exposure to neonatal hyperoxia reduces DLL4 and CLDN5 expression in developing mouse brain EC. We reveal that DLL4 is indispensable for brain vascular development and maintaining the blood-brain barrier's function and is repressed by neonatal hyperoxia. We speculate that reduced DLL4 signalling in brain EC may contribute to the impaired brain development observed in neonates exposed to hyperoxia. KEY POINTS: The role of delta like 4 (DLL4), a Notch ligand in vascular endothelial cells, in brain vascular development and functions remains unknown. We demonstrate that DLL4 is expressed at a high level during postnatal brain development in immature brains and DLL4 insufficiency leads to abnormal cerebral vasculature and increases vascular permeability both in vivo and in vitro. We identify that DLL4  regulates endothelial integrity through NOTCH-NICD-RBPJ-CLDN5 signalling. Dll4 and Cldn5 expression are decreased in mouse brain endothelial cells exposed to postnatal hyperoxia.

Early-life stress perturbs the epigenetics of Cd36 concurrent with adult onset of NAFLD in mice.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in the U.S. and worldwide. The roles of early postnatal life stress (EPLS) and the fatty acid translocase (CD36) on the pathogenesis of adult-onset NAFLD remain unknown. We hypothesized that EPLS, in the form of neonatal maternal separation (NMS), would predispose mice towards developing adult NAFLD, increase hepatic CD36 expression, and differentially methylate Cd36 promoter concurrently. METHODS: NMS was performed on mice from postnatal day 1 to 21 and a high-fat/high-sucrose (HFS) diet was started at 4 weeks of age to generate four experimental groups: Naive-control diet (CD), Naive-HFS, NMS-CD, and NMS-HFS. RESULTS: NMS alone caused NAFLD in adult male mice at 25 weeks of age. The effects of NMS and HFS were generally additive in terms of NAFLD, hepatic Cd36 mRNA levels, and hepatic Cd36 promoter DNA hypomethylation. Cd36 promoter methylation negatively correlated with Cd36 mRNA levels. Two differentially methylated regions (DMRs) within Cd36 promoter regions appeared to be vulnerable to NMS in the mouse. CONCLUSIONS: Our findings suggest that NMS increases the risk of an individual, particularly male, towards NAFLD when faced with a HFS diet later in life. IMPACT: The key message of this article is that neonatal maternal separation and a postweaning high-fat/high-sucrose diet increased the risk of an individual, particularly male, towards NAFLD in adult life. What this study adds to the existing literature includes the identification of two vulnerable differentially methylated regions in hepatic Cd36 promoters whose methylation levels very strongly negatively correlated with Cd36 mRNA. The impact of this article is that it provides an early-life environment-responsive gene/promoter methylation model and an animal model for furthering the mechanistic study on how the insults in early-life environment are "transmitted" into adulthood and caused NAFLD.

Adverse maternal environment affects hippocampal HTR2c variant expression and epigenetic characteristics in mouse offspring.

BACKGROUND: An adverse maternal environment (AME) predisposes progeny towards cognitive impairment in humans and mice. Cognitive impairment associates with hippocampal dysfunction. An important regulator of hippocampal function is the hippocampal serotonergic system. Dysregulation of hippocampal serotonin receptor 2c (HTR2c) expression is linked with cognitive impairment. HTR2c contains multiple mRNA variants and isoforms that are epigenetically regulated including DNA methylation, histone modifications, and small nucleolar RNA MBII-52. We tested the hypotheses that AME increases HTR2c variant expression and alters epigenetic modifications along the HTR2c gene locus. METHODS: We create an AME through maternal Western diet and prenatal environmental stress in the mouse. We analyzed hippocampal HTR2c and variants' expression, DNA methylation and histone modifications along the gene locus, and MBII-52 levels in postnatal day 21 offspring. RESULTS: AME significantly increased the expressions of total HTR2c and full-length variants (V201 and V202) concurrently with an altered epigenetic profile along the HTR2c gene locus in male offspring hippocampi. Moreover, increased full-length variants' expression in AME males was in line with increased MBII-52 levels. CONCLUSIONS: AME affects male offspring hippocampal expression of HTR2c and full-length variants via epigenetic mechanisms. Altered hippocampal HTR2c expression may contribute to cognitive impairment seen in adult males in this model. IMPACT: The key message of our article is that an adverse maternal environment increases expression of total HTR2c mRNA and protein, alters proportions of HTR2c mRNA variants, and impacts HTR2c epigenetic modifications in male offspring hippocampi relative to controls. Our findings add to the literature by providing the first report of altered HTR2c mRNA variant expression in association with altered epigenetic modifications in the hippocampus of offspring mice exposed to an adverse maternal environment. Our findings suggest that an adverse maternal environment affects the expression of genes previously determined to regulate cognitive function through an epigenetic mechanism in a sex-specific manner.

DUSP5-mediated inhibition of smooth muscle cell proliferation suppresses pulmonary hypertension and right ventricular hypertrophy.

Pulmonary hypertension (PH) is associated with structural remodeling of pulmonary arteries (PAs) because of excessive proliferation of fibroblasts, endothelial cells, and smooth muscle cells (SMCs). The peptide hormone angiotensin II (ANG II) contributes to pulmonary vascular remodeling, in part, through its ability to trigger extracellular signal-regulated kinase (ERK1/2) activation. Here, we demonstrate that the ERK1/2 phosphatase, dual-specificity phosphatase 5 (DUSP5), functions as a negative regulator of ANG II-mediated SMC proliferation and PH. In contrast to wild-type controls, Dusp5 null mice infused with ANG II developed PH and right ventricular (RV) hypertrophy. PH in Dusp5 null mice was associated with thickening of the medial layer of small PAs, suggesting an in vivo role for DUSP5 as a negative regulator of ANG II-dependent SMC proliferation. Consistent with this, overexpression of DUSP5 blocked ANG II-mediated proliferation of cultured human pulmonary artery SMCs (hPASMCs) derived from patients with idiopathic PH or from failed donor controls. Collectively, the data support a role for DUSP5 as a feedback inhibitor of ANG II-mediated ERK signaling and PASMC proliferation and suggest that disruption of this circuit leads to adverse cardiopulmonary remodeling.NEW & NOTEWORTHY Dual-specificity phosphatases (DUSPs) serve critical roles in the regulation of mitogen-activated protein kinases, but their functions in the cardiovascular system remain poorly defined. Here, we provide evidence that DUSP5, which resides in the nucleus and specifically dephosphorylates extracellular signal-regulated kinase (ERK1/2), blocks pulmonary vascular smooth muscle cell proliferation. In response to angiotensin II infusion, mice lacking DUSP5 develop pulmonary hypertension and right ventricular cardiac hypertrophy. These findings illustrate DUSP5-mediated suppression of ERK signaling in the lungs as a protective mechanism.

Adverse Maternal Environment Alters MicroRNA-10b-5p Expression and Its Epigenetic Profile Concurrently with Impaired Hippocampal Neurogenesis in Male Mouse Hippocampus.

An adverse maternal environment (AME) predisposes adult offspring toward cognitive impairment in humans and mice. However, the underlying mechanisms remain poorly understood. Epigenetic changes in response to environmental exposure may be critical drivers of this change. Epigenetic regulators, including microRNAs, have been shown to affect cognitive function by altering hippocampal neurogenesis which is regulated in part by brain-derived neurotropic factor (BDNF). We sought to investigate the effects of AME on miR profile and their epigenetic characteristics, as well as neurogenesis and BDNF expression in mouse hippocampus. Using our mouse model of AME which is composed of maternal Western diet and prenatal environmental stress, we found that AME significantly increased hippocampal miR-10b-5p levels. We also found that AME significantly decreased DNA methylation and increased accumulations of active histone marks H3 lysine (K) 4me3, H3K14ac, and -H3K36me3 at miR-10b promoter. Furthermore, AME significantly decreased hippocampal neurogenesis by decreasing cell numbers of Ki67+ (proliferation marker), NeuroD1+ (neuronal differentiation marker), and NeuN+ (mature neuronal marker) in the dentate gyrus (DG) region concurrently with decreased hippocampal BDNF protein levels. We speculate that the changes in epigenetic profile at miR-10b promoter may contribute to upregulation of miR-10b-5p and subsequently lead to decreased BDNF levels in a model of impaired offspring hippocampal neurogenesis and cognition in mice.

Adverse Maternal Environment and Postweaning Western Diet Alter Hepatic CD36 Expression and Methylation Concurrently with Nonalcoholic Fatty Liver Disease in Mouse Offspring.

BACKGROUND: The role of an adverse maternal environment (AME) in conjunction with a postweaning Western diet (WD) in the development of nonalcoholic fatty liver disease (NAFLD) in adult offspring has not been explored. Likewise, the molecular mechanisms associated with AME-induced NAFLD have not been studied. The fatty acid translocase or cluster of differentiation 36 (CD36) has been implicated to play a causal role in the pathogenesis of WD-induced steatosis. However, it is unknown if CD36 plays a role in AME-induced NAFLD. OBJECTIVE: This study was designed to evaluate the isolated and additive impact of AME and postweaning WD on the expression and DNA methylation of hepatic Cd36 in association with the development of NAFLD in a novel mouse model. METHODS: AME constituted maternal WD and maternal stress, whereas the control (Con) group had neither. Female C57BL/6J mice were fed a WD [40% fat energy, 29.1% sucrose energy, and 0.15% cholesterol (wt/wt)] 5 wk prior to pregnancy and throughout lactation. Non invasive variable stressors (random frequent cage changing, limited bedding, novel object, etc.) were applied to WD dams during the last third of pregnancy to produce an AME. Con dams consumed the control diet (CD) (10% fat energy, no sucrose or cholesterol) and were not exposed to stress. Male offspring were weaned onto either CD or WD, creating 4 experimental groups: Con-CD, Con-WD, AME-CD, and AME-WD, and evaluated for metabolic and molecular parameters at 120 d of age. RESULTS: AME and postweaning WD independently and additively increased the development of hepatic steatosis in adult male offspring. AME and WD independently and additively upregulated hepatic CD36 protein and mRNA expression and hypomethylated promoters 2 and 3 of the Cd36 gene. CONCLUSIONS: Using a mouse AME model together with postweaning WD, this study demonstrates a role for CD36 in AME-induced NAFLD in offspring and reveals 2 regions of environmentally induced epigenetic heterogeneity within Cd36.

Hippocampal epigenetic and insulin-like growth factor alterations in noninvasive versus invasive mechanical ventilation in preterm lambs.

BACKGROUND: The brain of chronically ventilated preterm human infants is vulnerable to collateral damage during invasive mechanical ventilation (IMV). Damage is manifest, in part, by learning and memory impairments, which are hippocampal functions. A molecular regulator of hippocampal development is insulin-like growth factor 1 (IGF1). A gentler ventilation strategy is noninvasive respiratory support (NRS). We tested the hypotheses that NRS leads to greater levels of IGF1 messenger RNA (mRNA) variants and distinct epigenetic profile along the IGF1 gene locus in the hippocampus compared to IMV. METHODS: Preterm lambs were managed by NRS or IMV for 3 or 21 days. Isolated hippocampi were analyzed for IGF1 mRNA levels and splice variants for promoter 1 (P1), P2, and IGF1A and 1B, DNA methylation in P1 region, and histone covalent modifications along the gene locus. RESULTS: NRS had significantly greater levels of IGF1 P1 (predominant transcript), and 1A and 1B mRNA variants compared to IMV at 3 or 21 days. NRS also led to more DNA methylation and greater occupancy of activating mark H3K4 trimethylation (H3K4me3), repressive mark H3K27me3, and elongation mark H3K36me3 compared to IMV. CONCLUSIONS: NRS leads to distinct IGF1 mRNA variant levels and epigenetic profile in the hippocampus compared to IMV. IMPACT: Our study shows that 3 or 21 days of NRS of preterm lambs leads to distinct IGF1 mRNA variant levels and epigenetic profile in the hippocampus compared to IMV. Preterm infant studies suggest that NRS leads to better neurodevelopmental outcomes later in life versus IMV. Also, duration of IMV is directly related to hippocampal damage; however, molecular players remain unknown. NRS, as a gentler mode of respiratory management of preterm neonates, may reduce damage to the immature hippocampus through an epigenetic mechanism.

Adverse early-life environment impairs postnatal lung development in mice.

BACKGROUND: Fetal growth restriction (FGR) is a major risk factor for bronchopulmonary dysplasia (BPD). Maternal stress and poor diet are linked to FGR. Effect of perinatal stress on lung development remains unknown. OBJECTIVE: Using a murine model of adverse early life environment (AELE), we hypothesized that maternal exposure to perinatal environmental stress and high-fat diet (Western diet) lead to impaired lung development in the offspring. METHODS: Female mice were placed on either control diet or Western diet before conception. Those exposed to Western diet were also exposed to perinatal environmental stress, the combination referred to as AELE. Pups were either euthanized at postnatal day 21 (P21) or weaned to control diet and environment until adulthood (8-14 wk old). Lungs were harvested for histology, gene expression by quantitative RT-PCR, microRNA profiling, and immunoblotting. RESULTS: AELE increased the mean linear intercept and decreased the radial alveolar count and secondary septation in P21 and adult mice. Capillary count was also decreased in P21 and adult mice. AELE lungs had decreased vascular endothelial growth factor A (VEGFA), VEGF receptor 2, endothelial nitric oxide synthase, and hypoxia inducible factor-1α protein levels and increased expression of genes that regulate DNA methylation and upregulation of microRNAs that target genes involved in lung development at P21. CONCLUSION: AELE leads to impaired lung alveolar and vascular growth, which persists into adult age despite normalizing the diet and environment at P21. AELE also alters the expression of genes involved in lung remodeling.

Persistent pulmonary hypertension alters the epigenetic characteristics of endothelial nitric oxide synthase gene in pulmonary artery endothelial cells in a fetal lamb model.

Decreased expression of endothelial nitric oxide synthase (eNOS), a key mediator of perinatal transition, characterizes persistent pulmonary hypertension of the newborn (PPHN) in neonates and a fetal lamb model; the mechanisms are unclear. We investigated whether increased DNA CpG methylation at the eNOS promoter in estrogen response elements (EREs) and altered histone code together contribute to decreased eNOS expression in PPHN. We isolated pulmonary artery endothelial cells (PAEC) from fetal lambs with PPHN induced by prenatal ductus arteriosus constriction from 128 to 136 days gestation or gestation-matched twin controls. We measured right ventricular systolic pressure (RVSP) and Fulton index and determined eNOS expression in PAEC in control and PPHN lambs. We determined DNA CpG methylation by pyrosequencing and activity of ten eleven translocase demethylases (TET) by colorimetric assay. We quantified the occupancy of transcription factors, specificity protein 1 (Sp1), and estrogen receptors and density of four histone marks around Sp1 binding sites by chromatin immunoprecipitation (ChIP) assays. Fetal lambs with PPHN developed increased RVSP and Fulton index. Levels of eNOS mRNA and protein were decreased in PAEC from PPHN lambs. PPHN significantly increased the DNA CpG methylation in eNOS promoter and decreased TET activity in PAEC. PPHN decreased Sp1 occupancy and density of the active mark, lysine 12 acetylation of histone 4, and increased density of the repression mark, lysine 9 trimethylation of histone 3 around Sp1 binding sites in eNOS promoter. These results suggest that epigenetic modifications are primed to decrease Sp1 binding at the eNOS gene promoter in PPHN.

Intrauterine growth restriction disrupts developmental epigenetics around distal growth hormone response elements on the rat hepatic IGF-1 gene.

Intrauterine growth restriction (IUGR) decreases serum IGF-1 levels. Postnatal IGF-1 expression is transcriptionally regulated by growth hormone (GH) through growth hormone response elements (GHREs). We hypothesized that IUGR disrupts the normal developmental maturation of hepatic IGF-1 intron 2 growth hormone response element (IN2GHRE) histone methylation of key lysines and DNA methylation. We also evaluated a 5' distal weak enhancer (IGF-1 5'-upstream region growth hormone response element; 5URGHRE) as a GHRE specificity control. IUGR was induced through a well-characterized model of bilateral uterine artery ligation of the pregnant rat. Offspring livers were tested at d 0 and 21. Chromatin immunoprecipitation and bisulfite sequencing quantified epigenetic characteristics. We found that distinct age-related developmental patterns of histone and DNA methylation characterize each GHRE. Development increased H3K4 trimethylation (me3) in both GHREs. However, H3K9me3 decreased with age at IN2GHRE and increased with age at 5URGHRE. IUGR altered the developmental pattern of H3K4me3 and K9me3 around the GHREs in a sex-specific manner at d 21. Developmental and IUGR-induced DNA methylation occurred in a GHRE-, CpG site-, and sex-specific manner. We conclude that IUGR disrupts developmental epigenetics around distal GHREs on the rat hepatic IGF-1 gene.

Essential nutrient supplementation prevents heritable metabolic disease in multigenerational intrauterine growth-restricted rats.

Intrauterine growth restriction (IUGR) confers heritable alterations in DNA methylation, rendering risk of adult metabolic syndrome (MetS). Because CpG methylation is coupled to intake of essential nutrients along the one-carbon pathway, we reasoned that essential nutrient supplementation (ENS) may abrogate IUGR-conferred multigenerational MetS. Pregnant Sprague-Dawley rats underwent bilateral uterine artery ligation causing IUGR in F1. Among the F2 generation, IUGR lineage rats were underweight at birth (6.7 vs. 8.0 g, P < 0.0001) and obese by adulthood (p160: 613 vs. 510 g; P < 0.0001). Dual energy X-ray absorptiometry studies revealed increased central fat mass (Δ+40 g), accompanied by dyslipidemic (>30% elevated, P < 0.05) serum triglycerides (139 mg/dl), very-LDLs (27.8 mg/dl), and fatty acids (632 µM). Hyperglycemic-euglycemic clamp studies and glucose tolerance testing revealed insulin resistance. Conversely, IUGR lineage ENS-fed rats did not manifest MetS, with significantly lower body weight (p160: 410 g), >5-fold less central fat mass, normal hepatic glucose efflux, and >70% reduced circulating triglycerides and very-LDLs compared with IUGR control-fed F2 offspring (P < 0.01). Moreover, increased methylation of the IGF-1 P2 transcriptional start site among IUGR lineage F2 offspring was reversed in ENS (P < 0.04). This is an initial demonstration that supplementation along the one-carbon pathway abrogates adult morbidity and associated epigenomic modifications of IGF-1 in a rodent model of multigenerational MetS.

Intrauterine growth restriction perturbs nucleosome depletion at a growth hormone-responsive element in the mouse IGF-1 gene.

Intrauterine growth restriction (IUGR) is a common human pregnancy complication. IUGR offspring carry significant postnatal risk for early-onset metabolic syndrome, which is associated with persistent reduction in IGF-1 protein expression. We have previously shown that preadolescent IUGR male mice have decreased hepatic IGF-1 mRNA and circulating IGF-1 protein at postnatal day 21, the age when growth hormone (GH) normally upregulates hepatic IGF-1 expression. Here we studied nucleosome occupancy and CpG methylation at a putative growth hormone-responsive element in intron 2 (in2GHRE) of the hepatic IGF-1 gene in normal, sham-operated, and IUGR mice. Nucleosome occupancy and CpG methylation were determined in embryonic stem cells (ESCs) and in liver at postnatal days 14, 21, and 42. For CpG methylation, additional time points out to 2 yr were analyzed. We confirmed the putative mouse in2GHRE was GH-responsive, and in normal mice, a single nucleosome was displaced from the hepatic in2GHRE by postnatal day 21, which exposed two STAT5b DNA binding sites. Nucleosome displacement correlated with developmentally programmed CpG demethylation. Finally, IUGR significantly altered the nucleosome-depleted region (NDR) at the in2GHRE of IGF-1 on postnatal day 21, with either complete absence of the NDR or with a shifted NDR exposing only one of two STAT5b DNA binding sites. An NDR shift was also seen in offspring of sham-operated mothers. We conclude that prenatal insult such as IUGR or anesthesia/surgery could perturb the proper formation of a well-positioned NDR at the mouse hepatic IGF-1 in2GHRE necessary for transitioning to an open chromatin state.

Epigenetic contributions to the developmental origins of adult lung disease.

Perinatal insults, including intrauterine growth restriction, preterm birth, maternal exposure to toxins, or dietary deficiencies produce deviations in the epigenome of lung cells. Occurrence of perinatal insults often coincides with the final stages of lung development. The result of epigenome disruptions in response to perinatal insults during lung development may be long-term structural and functional impairment of the lung and development of lung disease. Understanding the contribution of epigenetic mechanisms to life-long lung disease following perinatal insults is the focus of the developmental origins of adult lung disease field. DNA methylation, histone modifications, and microRNA changes are all observed in various forms of lung disease. However, the perinatal contribution to such epigenetic mechanisms is poorly understood. Here we discuss the developmental origins of adult lung disease, the interplay between perinatal events, lung development and disease, and the role that epigenetic mechanisms play in connecting these events.

IUGR increases chromatin-remodeling factor Brg1 expression and binding to GR exon 1.7 promoter in newborn male rat hippocampus.

Intrauterine growth restriction (IUGR) increases the risk for neurodevelopment delay and neuroendocrine reprogramming in both humans and rats. Neuroendocrine reprogramming involves the glucocorticoid receptor (GR) gene that is epigenetically regulated in the hippocampus. Using a well-characterized rodent model, we have previously shown that IUGR increases GR exon 1.7 mRNA variant and total GR expressions in male rat pup hippocampus. Epigenetic regulation of GR transcription may involve chromatin remodeling of the GR gene. A key chromatin remodeler is Brahma-related gene-1(Brg1), a member of the ATP-dependent SWItch/Sucrose NonFermentable (SWI/SNF) chromatin remodeling complex. Brg1 regulates gene expression by affecting nucleosome repositioning and recruiting transcriptional components to target promoters. We hypothesized that IUGR would increase hippocampal Brg1 expression and binding to GR exon 1.7 promoter, as well as alter nucleosome positioning over GR promoters in newborn male pups. Further, we hypothesized that IUGR would lead to accumulation of specificity protein 1 (Sp1) and RNA pol II at GR exon 1.7 promoter. Indeed, we found that IUGR increased Brg1 expression and binding to GR exon 1.7 promoter. We also found that increased Brg1 binding to GR exon 1.7 promoter was associated with accumulation of Sp1 and RNA pol II carboxy terminal domain pSer-5 (a marker of active transcription). Furthermore, the transcription start site of GR exon 1.7 was located within a nucleosome-depleted region. We speculate that changes in hippocampal Brg1 expression mediate GR expression and subsequently trigger neuroendocrine reprogramming in male IUGR rats.

Resistance strength training exercise in children with spinal muscular atrophy.

INTRODUCTION: Preliminary evidence in adults with spinal muscular atrophy (SMA) and in SMA animal models suggests exercise has potential benefits in improving or stabilizing muscle strength and motor function. METHODS: We evaluated feasibility, safety, and effects on strength and motor function of a home-based, supervised progressive resistance strength training exercise program in children with SMA types II and III. Up to 14 bilateral proximal muscles were exercised 3 times weekly for 12 weeks. RESULTS: Nine children with SMA, aged 10.4 ± 3.8 years, completed the resistance training exercise program. Ninety percent of visits occurred per protocol. Training sessions were pain-free (99.8%), and no study-related adverse events occurred. Trends in improved strength and motor function were observed. CONCLUSIONS: A 12-week supervised, home-based, 3-day/week progressive resistance training exercise program is feasible, safe, and well tolerated in children with SMA. These findings can inform future studies of exercise in SMA.

IUGR prevents IGF-1 upregulation in juvenile male mice by perturbing postnatal IGF-1 chromatin remodeling.

BACKGROUND: Intrauterine growth restriction (IUGR) offspring with rapid catch-up growth are at increased risk for early obesity especially in males. Persistent insulin-like growth factor-1 (IGF-1) reduction is an important risk factor. Using a mouse model of maternal hypertension-induced IUGR, we examined IGF-1 levels, promoter DNA methylation, and histone H3 covalent modifications at birth (D1). We additionally investigated whether prenatal perturbations could reset at preadolescence (D21). METHODS: IUGR was induced via maternal thromboxane A2-analog infusion in mice. RESULTS: IUGR uniformly decreased D1 IGF-1 mRNA and protein levels with reduced promoter 1 (P1) transcription and increased P1 DNA methylation. IUGR males also had increased H3K4ac at exon 5 and 3' distal UTR. At D21, IUGR males continued to have decreased IGF-1 levels, originating from both P1 and P2 with reduced 1A variant. IUGR males also had decreased activation mark of H3K4me3 at P1 compared with sham males. In contrast, D21 IUGR females normalized their IGF-1 levels, in association with an increased activation mark of H3K4me3 at P1 compared with sham females. CONCLUSION: IUGR uniformly affected D1 hepatic IGF-1 epigenetic modifications in both sexes. However, at preadolescence, IUGR males are unable to correct for the prenatal reduction possibly due to a more perturbed IGF-1 chromatin structure.

In utero nicotine exposure epigenetically alters fetal chromatin structure and differentially regulates transcription of the glucocorticoid receptor in a rat model.

BACKGROUND: Fetal exposure to nicotine is not limited to maternal tobacco smoke, as electronic cigarettes have an increased prevalence of use among reproductive aged women. Animal models have shown that nicotine exposure in utero is associated with increased risk of asthma and cognitive deficits, as well as increased expression of the hippocampal glucocorticoid receptor. We hypothesized that in utero nicotine exposure is associated with epigenetic changes in the offspring lung and brain which may contribute to a memory of this exposure METHODS: Sprague-Dawley rat dams received either saline or 2 mg/kg of nicotine by intraperitoneal injection once daily from embryonic day 6 (e6) to e22. Pups were killed on day 1 of life, and brain and lung tissues were harvested (N = 3/ group). RESULTS: We found that nicotine exposed offspring have altered histone modifications in the brain. Dimethylation of lysine 9 of histone H3 is decreased (0.43-fold; p = 0.03) while acetylation is increased (1.79-fold; p = 0.031). Histone deacetylase activity is significantly decreased with nicotine exposure in brain and lung (0.11-fold; p < 0.001; 0.12-fold; p < 0.001, respectively). Expression of splice variant 1.7 of the glucocorticoid receptor is reduced in the nicotine exposed offspring lung (0.25-fold; p = 0.038). CONCLUSION: We conclude that nicotine exposure is associated with epigenetic alterations in the offspring and may lead to susceptibility to adult disease,. Our finding that in utero exposure to nicotine is associated with inhibition of histone deacetylase activity in the brain of offspring is of importance as a similar inhibition has been suggested as a mechanism for the potentiation of addiction.

Essential surgery: the way forward.

INTRODUCTION: Very little surgical care is performed in low- and middle-income countries (LMICs). An estimated two billion people in the world have no access to essential surgical care, and non-surgeons perform much of the surgery in remote and rural areas. Surgical care is as yet not recognized as an integral aspect of primary health care despite its self-demonstrated cost-effectiveness. We aimed to define the parameters of a public health approach to provide surgical care to areas in most need. METHODS: Consensus meetings were held, field experience was collected via targeted interviews, and a literature review on the current state of essential surgical care provision in Sub-Saharan Africa (SSA) was conducted. Comparisons were made across international recommendations for essential surgical interventions and a consensus-driven list was drawn up according to their relative simplicity, resource requirement, and capacity to provide the highest impact in terms of averted mortality or disability. RESULTS: Essential Surgery consists of basic, low-cost surgical interventions, which save lives and prevent life-long disability or life-threatening complications and may be offered in any district hospital. Fifteen essential surgical interventions were deduced from various recommendations from international surgical bodies. Training in the realm of Essential Surgery is narrow and strict enough to be possible for non-physician clinicians (NPCs). This cadre is already active in many SSA countries in providing the bulk of surgical care. CONCLUSION: A basic package of essential surgical care interventions is imperative to provide structure for scaling up training and building essential health services in remote and rural areas of LMICs. NPCs, a health cadre predominant in SSA, require training, mentoring, and monitoring. The cost of such training is vastly more efficient than the expensive training of a few polyvalent or specialist surgeons, who will not be sufficient in numbers within the next few generations. Moreover, these practitioners are used to working in the districts and are much less prone to gravitate elsewhere. The use of these NPCs performing "Essential Surgery" is a feasible route to deal with the almost total lack of primary surgical care in LMICs.

Maternal obesity and high-fat diet program offspring metabolic syndrome.

OBJECTIVE: We determined the potential programming effects of maternal obesity and high-fat (HF) diet during pregnancy and/or lactation on offspring metabolic syndrome. STUDY DESIGN: A rat model of maternal obesity was created using an HF diet prior to and throughout pregnancy and lactation. At birth, pups were cross-fostered, thereby generating 4 paradigms of maternal diets during pregnancy/lactation: (1) control (Con) diet during pregnancy and lactation (Con/Con), (2) HF during pregnancy and lactation (HF/HF), (3) HF during pregnancy alone (HF/Con), and (4) HF during lactation alone (Con/HF). RESULTS: Maternal phenotype during pregnancy and the end of lactation evidenced markedly elevated body fat and plasma corticosterone levels in HF dams. In the offspring, the maternal HF diet during pregnancy alone programmed increased offspring adiposity, although with normal body weight, whereas the maternal HF diet during lactation increased both body weight and adiposity. Metabolic disturbances, particularly that of hyperglycemia, were apparent in all groups exposed to the maternal HF diet (during pregnancy and/or lactation), although differences were apparent in the manifestation of insulin resistant vs insulin-deficient phenotypes. Elevated systolic blood pressure was manifest in all groups, implying that exposure to an obese/HF environment is disadvantageous for offspring health, regardless of pregnancy or lactation periods. Nonetheless, the underlying mechanism may differ because offspring that experienced in utero HF exposure had increased corticosterone levels. CONCLUSION: Maternal obesity/HF diet has a marked impact on offspring body composition and the risk of metabolic syndrome was dependent on the period of exposure during pregnancy and/or lactation.

High-frequency nasal ventilation for 21 d maintains gas exchange with lower respiratory pressures and promotes alveolarization in preterm lambs.

BACKGROUND: Short-term high-frequency nasal ventilation (HFNV) of preterm neonates provides acceptable gas exchange compared to endotracheal intubation and intermittent mandatory ventilation (IMV). Whether long-term HFNV will provide acceptable gas exchange is unknown. We hypothesized that HFNV for up to 21 d would lead to acceptable gas exchange at lower inspired oxygen (O2) levels and airway pressures compared to intubation and IMV. METHODS: Preterm lambs were exposed to antenatal steroids and treated with perinatal surfactant and postnatal caffeine. Lambs were intubated and resuscitated by IMV. At ~3 h of age, half of the lambs were switched to noninvasive HFNV. Support was for 3 or 21 d. By design, Pao2 and Paco2 were not different between groups. RESULTS: At 3 d (n = 5) and 21 d (n = 4) of HFNV, fractional inspired O2 (FiO2), peak inspiratory pressure (PIP), mean airway, intratracheal, and positive end-expiratory pressures, oxygenation index, and alveolar-arterial gradient were significantly lower than matched periods of intubation and IMV. Pao2/FiO2 ratio was significantly higher at 3 and 21 d of HFNV compared to matched intubation and IMV. HFNV led to better alveolarization at 3 and 21 d. CONCLUSION: Long-term HFNV provides acceptable gas exchange at lower inspired O2 levels and respiratory pressures compared to intubation and IMV.