Prematurity disrupts glomeruli development, whereas prematurity and hyperglycemia lead to altered nephron maturation and increased oxidative stress in newborn baboons.

BackgroundPremature birth occurs when nephrogenesis is incomplete and has been linked to increased renal pathologies in the adult. Metabolic factors complicating preterm birth may have additional consequences for kidney development. Here, we evaluated the effects of prematurity and hyperglycemia on nephrogenesis in premature baboons when compared with those in term animals.MethodsBaboons were delivered prematurely (67% gestation; n=9) or at term (n=7) and survived for 2-4 weeks. Preterm animals were classified by glucose control during the first 5 days of life: normoglycemic (PtN; serum glucose 50-100 mg/dl, n=6) and hyperglycemic (PtH; serum glucose 150-250 mg/dl, n=3). Kidneys were assessed histologically for glomeruli relative area, maturity, size, and overall morphology. Kidney lysates were evaluated for oxidative damage with 4-hydroxynonenal (4-HNE) antibody.ResultsHistological examination revealed decreased glomeruli relative area (P<0.05), fewer glomerular generations (P<0.01), and increased renal corpuscle area (P<0.001) in preterm compared with those in term animals. Numbers of apoptotic glomeruli were similar between groups. PtH kidneys exhibited reduced nephrogenic zone width (P<0.0001), increased numbers of mature glomeruli (P<0.05), and increased 4-HNE staining compared with those in PtN kidneys.ConclusionPrematurity interrupts normal kidney development, independent of glomerular cell apoptosis. When prematurity is complicated by hyperglycemia; kidney development shifts toward accelerated maturation and increased oxidative stress.

Cardiovascular and Musculoskeletal Assessment of Elite US Volleyball Players.

OBJECTIVE: The aim of this study was to characterize the cardiovascular and musculoskeletal systems of elite volleyball players, including aortic dimensions. Previous studies have shown that the upper limit of normal aortic sinus diameter for male and female athletes is 4 and 3.4 cm, respectively. DESIGN: Cross-sectional analysis. SETTING: United States Olympic Volleyball Training Facility and Rady Children's Hospital San Diego. PARTICIPANTS: Seventy (37 male) members of the US national volleyball team. MAIN OUTCOME MEASURES: Athletes underwent evaluation that included medical and family histories, targeted physical examinations specifically focusing on abnormalities present in Marfan syndrome (MFS), and transthoracic echocardiograms. Cardiac chamber and great artery size, valve function, and coronary artery origins were assessed. RESULTS: Three male athletes (8%) had an aortic sinus diameter ≥4 cm, one of whom also had an ascending aorta >4 cm. Two female athletes (6%) had aortic sinus diameter ≥3.4 cm, and another had an ascending aorta of 3.4 cm. There were no other intracardiac or arterial abnormalities. Individual musculoskeletal characteristics of MFS were common among the athletes but not more frequent or numerous in those with aortic dilation. CONCLUSIONS: The prevalence of aortic root dilation in this population of athletes was higher than what has previously been reported in other similar populations. Further study is needed to determine whether these represent pathological changes or normal variations in tall athletes. CLINICAL RELEVANCE: This study adds to the existing knowledge base of athlete's heart, with specific attention to aortic dimensions in elite volleyball players. The data are relevant to similar athletes' medical care and to preparticipation cardiac screening in general.

Smad7 inhibits autocrine expression of TGF-ß2 in intestinal epithelial cells in baboon necrotizing enterocolitis.

Preterm infants may be at risk of necrotizing enterocolitis (NEC) due to deficiency of transforming growth factor-ß 2 (TGF-ß(2)) in the developing intestine. We hypothesized that low epithelial TGF-ß(2) expression in preterm intestine and during NEC results from diminished autocrine induction of TGF-ß(2) in these cells. Premature baboons delivered at 67% gestation were treated per current norms for human preterm infants. NEC was diagnosed by clinical and radiological findings. Inflammatory cytokines, TGF-ß(2), Smad7, Ski, and strawberry notch N (SnoN)/Ski-like oncoprotein (SKIL) was measured using quantitative reverse transcriptase-polymerase chain reaction, immunoblots, and immunohistochemistry. Smad7 effects were examined in transfected IEC6 intestinal epithelial cells in vitro. Findings were validated in archived human tissue samples of NEC. NEC was recorded in seven premature baboons. Consistent with existing human data, premature baboon intestine expressed less TGF-ß(2) than term intestine. TGF-ß(2) expression was regulated in epithelial cells in an autocrine fashion, which was interrupted in the premature intestine and during NEC due to increased expression of Smad7. LPS increased Smad7 binding to the TGF-ß(2) promoter and was associated with dimethylation of the lysine H3K9, a marker of transcriptional silencing, on the nucleosome of TGF-ß(2). Increased Smad7 expression in preterm intestine was correlated with the deficiency of SnoN/SKIL, a repressor of the Smad7 promoter. Smad7 inhibits autocrine expression of TGF-ß(2) in intestinal epithelial cells in the normal premature intestine and during NEC. Increased Smad7 expression in the developing intestine may be due to a developmental deficiency of the SnoN/SKIL oncoprotein.

Hyperglycemia increases the risk of death in extremely preterm baboons.

BACKGROUND: Transient neonatal hyperglycemia (HG) has been reported in up to 80% of extremely preterm human infants. We hypothesize that severe HG is associated with increased morbidity and mortality in preterm baboons. METHODS: Sixty-six baboons born at 67% of gestation were studied. HG was defined as serum glucose level ≥150 mg/dl during the first week of life. Animals were stratified into two groups: severe HG (≥8 events) and nonsevere HG (<8 events). RESULTS: HG developed in 65 of the 66 (98%) baboons that were included. A total of 3,386 glucose measurements were obtained. The mean serum glucose level was 159 ± 69 mg/dl for the severe HG group and 130 ± 48 mg/dl for the nonsevere HG group during the first week of life. No differences were found in gender, birth weight, sepsis, patent ductus arteriosus, or oxygenation/ventilation indexes between groups. Severe HG was associated with early death even after controlling for sepsis, postnatal steroid exposure, and catecholamine utilization. CONCLUSION: HG is common in preterm baboons and is not associated with short-term morbidity. Severe HG occurring in the first week of life is associated with early death in preterm baboons.

Isolated Absent Aortic Valves: A Unique Fetal Case With Echocardiographic, Pathologic, and Genetic Correlation.

We present a 22-week fetus with isolated absent aortic valve and inverse circular shunt. The pregnancy was interrupted. Here, echocardiography and pathology images demonstrate this rare entity. Whole genome sequencing revealed a potentially disease-causing variant in the APC gene. Whole genome sequencing should be considered in severe and rare fetal diseases. (Level of Difficulty: Advanced.).

Clostridium perfringens phospholipase C, an archetypal bacterial virulence factor, induces the formation of extracellular traps by human neutrophils.

Neutrophil extracellular traps (NETs) are networks of DNA and various microbicidal proteins released to kill invading microorganisms and prevent their dissemination. However, a NETs excess is detrimental to the host and involved in the pathogenesis of various inflammatory and immunothrombotic diseases. Clostridium perfringens is a widely distributed pathogen associated with several animal and human diseases, that produces many exotoxins, including the phospholipase C (CpPLC), the main virulence factor in gas gangrene. During this disease, CpPLC generates the formation of neutrophil/platelet aggregates within the vasculature, favoring an anaerobic environment for C. perfringens growth. This work demonstrates that CpPLC induces NETosis in human neutrophils. Antibodies against CpPLC completely abrogate the NETosis-inducing activity of recombinant CpPLC and C. perfringens secretome. CpPLC induces suicidal NETosis through a mechanism that requires calcium release from inositol trisphosphate receptor (IP3) sensitive stores, activation of protein kinase C (PKC), and the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK) pathways, as well as the production of reactive oxygen species (ROS) by the metabolism of arachidonic acid. Proteomic analysis of the C. perfringens secretome identified 40 proteins, including a DNAse and two 5´-nucleotidases homologous to virulence factors that could be relevant in evading NETs. We suggested that in gas gangrene this pathogen benefits from having access to the metabolic resources of the tissue injured by a dysregulated intravascular NETosis and then escapes and spreads to deeper tissues. Understanding the role of NETs in gas gangrene could help develop novel therapeutic strategies to reduce mortality, improve muscle regeneration, and prevent deleterious patient outcomes.

Hemoglobin A1c above threshold level is associated with decreased ß-cell function in overweight Latino youth.

OBJECTIVE: To examine whether a hemoglobin A1c (HbA1c)-identified prediabetic state (HbA1c ≥ 6.0%-6.4%) is associated with decreased insulin sensitivity (SI) and ß-cell dysfunction, known factors in the pathogenesis of type 2 diabetes, in an overweight pediatric population. STUDY DESIGN: A total of 206 healthy overweight Latino adolescents (124 males and 82 females; mean age, 13.1 ± 2.0 years) were divided into 2 groups: lower risk (n=179), with HbA1c <6.0%, and higher risk (n=27), with HbA1c 6.0%-6.4%. Measurements included HbA1c, oral glucose tolerance testing, fasting and 2-hour glucose and insulin, SI, acute insulin response, and disposition index (an index of ß-cell function) by the frequently sampled intravenous glucose tolerance test with minimal modeling. Body fat was determined by dual-energy X-ray absorptiometry. RESULTS: Compared with the lower risk group, the higher risk group had 21% lower SI (1.21 ± 0.06 vs 1.54 ± 0.13; P<.05), 30% lower acute insulin response (928 ± 102 vs 1342 ± 56; P<.01), and a 31% lower disposition index (1390 ± 146 vs 2023 ± 83; P=.001) after adjusting for age and total percent body fat. CONCLUSION: These data provide clear evidence of greater impairment of ß-cell function in overweight Latino children with HbA1c 6.0%-6.4%, and thereby support the adoption of the International Expert Committee's HbA1c-determined definition of high-risk state for overweight children at risk for type 2 diabetes.

High Branched-Chain Amino Acid Concentrations Are Found in Preterm Baboons Receiving Intravenous Amino Acid Solutions and Mimic Alterations Found in Preterm Infants.

BACKGROUND: Parenteral amino acid (AA) nutrition administration after premature birth is necessary to ensure adequate growth and neurodevelopment. However, optimizing safety and efficacy remains a major challenge. This study investigated the effects of intravenous AA administration on plasma AA profiles in premature baboons and infants. METHODS: Premature baboons were delivered by cesarean section at 125 days (67% gestation) and chronically ventilated. At 24 hours of life, a parenteral AA protocol comparable to the early and high AA regimens used in premature infants was initiated. Serial plasma AA concentrations were obtained on days of life (DOLs) 1, 3, and 7 and compared with concentrations at similar DOLs from preterm infants. Fetal baboon (165 ± 2 days; 89% gestation) and term baboon plasma AA concentrations were obtained for comparison. RESULTS: Premature baboons receiving early and high parenteral AA supplementation exhibited significant differences in plasma AA concentrations compared with fetuses. In particular, concentrations of leucine, isoleucine, valine, and ornithine were elevated (fold increase: 2.14, 2.03, 1.95, and 16.5, respectively; P < 0.001) on DOL 3 vs fetuses. These alterations mimicked those found in preterm infants. CONCLUSION: Early and high AA supplementation in extremely premature baboons significantly disrupted plasma AA concentrations. Elevated concentrations of branched-chain AAs and ornithine raise concerns for adverse neurodevelopmental outcomes. These results are consistent with those found in premature human infants and emphasize the need to optimize parenteral AA solutions for the unique metabolic requirements of premature infants. Improved technologies for rapid monitoring of AA concentrations during treatment are essential.

Utility of Genetic Testing in Elite Volleyball Players with Aortic Root Dilation.

Basketball and volleyball attract individuals with a characteristic biophysical profile, mimicking features of Marfan syndrome. Consequently, identification of these abnormalities can be lifesaving. PURPOSE: To determine how physical examination, echocardiography, and genetic screening can identify elite volleyball players with a previously undiagnosed aortopathy. METHODS: We have performed cardiac screening on 90 US Volleyball National Team members and identified four individuals with dilated sinuses of Valsalva. This case series reports on three individuals who underwent a comprehensive genetics evaluation, including gene sequencing. RESULTS: Cardiac screening combined with genetic testing can identify previously undiagnosed tall athletes with an aortopathy, in the absence of noncardiac findings of a connective tissue disorder. Subject 1 had a revised Ghent systems (RGS) score of 2 and a normal aortopathy gene panel. Subject 2 had a RGS score of 1 and genetic testing revealed a de novo disease causing mutation in the gene encoding fibrillin-1 (FBN1). Subject 3 had an RGS score of 4.0 and had a normal aortopathy gene panel. CONCLUSIONS: Despite variable clinical features of Marfan syndrome, dilated sinuses of Valsalva were found in 4.9% of the athletes. A disease-causing mutation in the FBN1 gene was identified in subject 2, who had the lowest RGS but the largest aortic root measurement. Subjects 1 and 3, with the highest RGS, had a normal aortopathy gene panel. Our findings provide further evidence suggesting that a cardiac evaluation, including a screening echocardiogram, should be performed on all elite tall adult athletes independent of other physical findings. Genetic testing should be considered for athletes with dilated sinuses of Valsalva (male, >4.2 cm; female, >3.4 cm), regardless of other extracardiac findings.

Hepatic Insulin Resistance and Altered Gluconeogenic Pathway in Premature Baboons.

Premature infants have altered glucose regulation early in life and increased risk for diabetes in adulthood. Although prematurity leads to an increased risk of diabetes and metabolic syndrome in adult life, the role of hepatic glucose regulation and adaptation to an early extrauterine environment in preterm infants remain unknown. The purpose of this study was to investigate developmental differences in glucose metabolism, hepatic protein content, and gene expression of key insulin-signaling/gluconeogenic molecules. Fetal baboons were delivered at 67%, 75%, and term gestational age and euthanized at birth. Neonatal baboons were delivered prematurely (67% gestation), survived for two weeks, and compared with similar postnatal term animals and underwent serial hyperinsulinemic-euglycemic clamp studies. Premature baboons had decreased endogenous glucose production (EGP) compared with term animals. Consistent with these results, the gluconeogenic molecule, phosphoenolpyruvate carboxykinase messenger RNA, was decreased in preterm baboons compared with terms. Hepatic insulin signaling was altered by preterm birth as evidenced by decreased insulin receptor-ß, p85 subunit of phosphoinositide 3-kinase, phosphorylated insulin receptor substrate 1, and Akt-1 under insulin-stimulated conditions. Furthermore, preterm baboons failed to have the normal increase in glycogen synthase kinase-α from fetal to postnatal life. The blunted responses in hepatic insulin signaling may contribute to the hyperglycemia of prematurity, while impaired EGP leads to hypoglycemia of prematurity.

Double trouble: fetal diagnosis of a pulmonary artery sling and vascular ring.

Left pulmonary artery slings and vascular rings are rare congenital anomalies definable by fetal echocardiography. Left pulmonary artery slings are associated with high respiratory morbidity and mortality. Prenatal diagnosis of a left pulmonary artery sling should prompt delivery planning for postnatal management at a pediatric tertiary care center.

Peripheral insulin resistance and impaired insulin signaling contribute to abnormal glucose metabolism in preterm baboons.

Premature infants develop hyperglycemia shortly after birth, increasing their morbidity and death. Surviving infants have increased incidence of diabetes as young adults. Our understanding of the biological basis for the insulin resistance of prematurity and developmental regulation of glucose production remains fragmentary. The objective of this study was to examine maturational differences in insulin sensitivity and the insulin-signaling pathway in skeletal muscle and adipose tissue of 30 neonatal baboons using the euglycemic hyperinsulinemic clamp. Preterm baboons (67% gestation) had reduced peripheral insulin sensitivity shortly after birth (M value 12.5 ± 1.5 vs 21.8 ± 4.4 mg/kg · min in term baboons) and at 2 weeks of age (M value 12.8 ± 2.6 vs 16.3 ± 4.2, respectively). Insulin increased Akt phosphorylation, but these responses were significantly lower in preterm baboons during the first week of life (3.2-fold vs 9.8-fold). Preterm baboons had lower glucose transporter-1 protein content throughout the first 2 weeks of life (8%-12% of term). In preterm baboons, serum free fatty acids (FFAs) did not decrease in response to insulin, whereas FFAs decreased by greater than 80% in term baboons; the impaired suppression of FFAs in the preterm animals was paired with a decreased glucose transporter-4 protein content in adipose tissue. In conclusion, peripheral insulin resistance and impaired non-insulin-dependent glucose uptake play an important role in hyperglycemia of prematurity. Impaired insulin signaling (reduced Akt) contributes to the defect in insulin-stimulated glucose disposal. Counterregulatory hormones are not major contributors.

Developmental regulation of key gluconeogenic molecules in nonhuman primates.

Aberrant glucose regulation is common in preterm and full-term neonates leading to short and long-term morbidity/mortality; however, glucose metabolism in this population is understudied. The aim of this study was to investigate developmental differences in hepatic gluconeogenic pathways in fetal/newborn baboons. Fifteen fetal baboons were delivered at 125 day (d) gestational age (GA), 140d GA, and 175d GA (term = 185d GA) via cesarean section and sacrificed at birth. Term and healthy adult baboons were used as controls. Protein content and gene expression of key hepatic gluconeogenic molecules were measured: cytosolic and mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-C and PEPCK-M), glucose-6-phosphatase-alpha (G6Pase-α), G6Pase-ß, fructose-1,6-bisphosphatase (FBPase), and forkhead box-O1 (FOXO1). Protein content of PEPCK-M increased with advancing gestation in fetal baboons (9.6 fold increase from 125d GA to 175d GA, P < 0.001). PEPCK-C gene expression was consistent with these developmental differences. Phosphorylation of FOXO1 was significantly lower in preterm fetal baboons compared to adults, and gene expression of FOXO1 was lower in all neonates when compared to adults (10% and 62% of adults respectively, P < 0.05). The FOXO1 target gene G6Pase expression was higher in preterm animals compared to term animals. No significant differences were found in G6Pase-α, G6Pase-ß, FOXO1, and FBPase during fetal development. In conclusion, significant developmental differences are found in hepatic gluconeogenic molecules in fetal and neonatal baboons, which may impact the responses to insulin during the neonatal period. Further studies under insulin-stimulated conditions are required to understand the physiologic impact of these maturational differences.

Antenatal corticosteroids alter insulin signaling pathways in fetal baboon skeletal muscle.

We hypothesize that prenatal exposure to glucocorticoids (GCs) negatively alters the insulin signal transduction pathway and has differing effects on the fetus according to gestational age (GA) at exposure. Twenty-three fetal baboons were delivered from 23 healthy, nondiabetic mothers. Twelve preterm (0.67 GA) and 11 near-term (0.95 GA) baboons were killed immediately after delivery. Half of the pregnant baboons at each gestation received two doses of i.m. betamethasone 24 h apart (170 µg/kg) before delivery, while the other half received no intervention. Vastus lateralis muscle was obtained from postnatal animals to measure the protein content and gene expression of insulin receptor ß (IRß; INSR), IRß Tyr 1361 phosphorylation (pIRß), IR substrate 1 (IRS1), IRS1 tyrosine phosphorylation (pIRS1), p85 subunit of PI3-kinase, AKT (protein kinase B), phospho-AKT Ser473 (pAKT), AKT1, AKT2, and glucose transporters (GLUT1 and GLUT4). Skeletal muscle from preterm baboons exposed to GCs had markedly reduced protein content of AKT and AKT1 (respectively, 73 and 72% from 0.67 GA control, P<0.001); IRß and pIRß were also decreased (respectively, 94 and 85%, P<0.01) in the muscle of premature GC-exposed fetuses but not in term fetuses. GLUT1 and GLUT4 tended to increase with GC exposure in preterm animals (P=0.09), while GLUT4 increased sixfold in term animals after exposure to GC (P<0.05). In conclusion, exposure to a single course of antenatal GCs during fetal life alters the insulin signaling pathway in fetal muscle in a manner dependent on the stage of gestation.

Birth weight and body composition in overweight Latino youth: a longitudinal analysis.

To examine the associations between birth weight and BMI, and total body composition, in overweight Latino adolescents. Two hundred and forty-two overweight Latino children (baseline age = 11.1 +/- 1.7 years; BMI >or= 85th percentile) were measured annually for up to 6 years (2.6 +/- 1.4 observations/child, total 848 visits). Birth weight and history of gestational diabetes were obtained by parental interview. Visceral fat and subcutaneous abdominal fat were assessed by magnetic resonance imaging, while total body fat, total lean tissue mass (LTM), trunk fat, and lean tissue trunk mass were measured by dual-energy X-ray absorptiometry. BMI and BMI percentile were calculated using the Centers for Disease Control and Prevention age appropriate cutoffs. Longitudinal linear mixed effects (LME) modeling was used to evaluate the influence of birth weight on subsequent changes in body composition and distribution of fat across puberty. Birth weight significantly predicted BMI (P < 0.001), total trunk fat (P < 0.001), total trunk LTM (P < 0.001), total fat mass (FM) (P < 0.001), and total LTM (P < 0.001), but not subcutaneous (P = 0.534) or visceral fat (P = 0.593) at age 11 years. Longitudinally, as participants transitioned into puberty, birth weight did not significantly predict any of the body composition or fat distribution measures (P > 0.05). Birth weight is significantly associated with increased adiposity and LTM and negatively associated with trunk fat mass and trunk lean mass at baseline; however these relationships did not predict rate of change of any of the variables as the children progress through adolescence.