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1.  Maternal Haemoglobin and Short-Term Neonatal Outcome in Preterm Neonates 
PLoS ONE  2014;9(2):e89530.
To determine whether there is a significant association between maternal haemoglobin measured before delivery and short-term neonatal outcome in very preterm neonates.
Study design
We included prospectively all live births occurring from 25 to 32+6 weeks of gestation in a tertiary care centre between January 1st 2009 and December 31st 2011. Outborn infants and infants presenting with lethal malformations were excluded. Three hundred and thirty-nine mothers and 409 infants met the inclusion criteria. For each mother-infant pair a prospective record of epidemiologic data was performed and maternal haemoglobin concentration recorded within 24 hours before delivery was retrospectively researched. Maternal haemoglobin was divided into quartiles with the second and the third one regarded as reference as they were composed of normal haemoglobin values. Short-term outcome was defined as poor in case of death during hospital stay and/or grades III/IV intraventricular haemorrhage and/or periventricular leukomalacia and/or necessity of ventriculoperitoneal shunt.
The global rate of poor short-term neonatal outcome was 11.4% and was significantly associated with low maternal haemoglobin values. This association remained significant after adjustment for antenatal corticosteroids therapy, gestational age, parity, mechanism of preterm birth, mode of delivery and birth weight (aOR = 2.97 CI 95% [1.36–6.47]). There was no relation between short-term neonatal outcome and high maternal haemoglobin concentration values.
We show that low maternal haemoglobin concentration at delivery is an independent risk factor for poor short-term neonatal outcome in very preterm neonates. This study is one of the first to show such an association within the preterm population.
PMCID: PMC3934893  PMID: 24586850
2.  Progress on the Maternal Mortality Ratio Reduction in Wuhan, China in 2001–2012 
PLoS ONE  2014;9(2):e89510.
Most maternal deaths occur in developing countries and most maternal deaths are avoidable. China has made a great effort to reduce MMR by three quarters to meet the fifth Millennium Development Goal (MDG5).
This retrospective study reviewed and analyzed maternal death data in Wuhan from 2001 to 2012. Joinpoint regression and multivariate Poisson regression was conducted using the log-linear model to measure the association of the number of maternal deaths with time, cause of death, where the death occurred, and cognitive factors including knowledge, attitude, resource, and management stratified.
The MMR declined from 33.41 per 100,000 live births in 2001 to 10.63 per 100,000 live births in 2012, with a total decline of 68.18% and an average annual decline of 9.89%. From 2001–2012, the four major causes of maternal death were obstetric hemorrhage (35.16%), pregnancy complications (28.57%), amniotic fluid embolism (16.48%) and gestational hypertension (8.79%). Multivariate Poisson regression showed on average the MMR decreased by.17% each year from 2001–2006 and stayed stagnant since 2007–2012.
With the reduction in MMR in obstetric death (e.g. obstetric hemorrhage), there had been a remarkable reduction in MMR in Wuhan in 2001–2012, which may be due to (1) the improvement in the obstetric quality of perinatal care service on prevention and treatment of obstetric hemorrhage and emergency care skills, and (2) the improvement in the maternal health management and quality of prenatal care. Interventions to further reduce the MMR include several efforts such as the following: (1) designing community-based interventions, (2) providing subsidies to rural women and/hospitals for hospital delivery, (3) screening for pregnancy complications, and (4) establishing an emergency rescue system for critically ill pregnant women.
PMCID: PMC3931783  PMID: 24586836
3.  In-Utero Exposure to Bereavement and Offspring IQ: A Danish National Cohort Study 
PLoS ONE  2014;9(2):e88477.
Intelligence is a life-long trait that has strong influences on lifestyle, adult morbidity and life expectancy. Hence, lower cognitive abilities are therefore of public health interest. Our primary aim was to examine if prenatal bereavement measured as exposure to death of a close family member is associated with the intelligence quotient (IQ) scores at 18-years of age of adult Danish males completing a military cognitive screening examination.
We extracted records for the Danish military screening test and found kinship links with biological parents, siblings, and maternal grandparents using the Danish Civil Registration System (N = 167,900). The prenatal exposure period was defined as 12 months before conception until birth of the child. We categorized children as exposed in utero to severe stress (bereavement) during prenatal life if their mothers lost an elder child, husband, parent or sibling during the prenatal period; the remaining children were included in the unexposed cohort. Mean score estimates were adjusted for maternal and paternal age at birth, residence, income, maternal education, gestational age at birth and birth weight.
When exposure was due to death of a father the offsprings' mean IQ scores were lower among men completing the military recruitment exam compared to their unexposed counterparts, adjusted difference of 6.5 standard IQ points (p-value = 0.01). We did not observe a clinically significant association between exposure to prenatal maternal bereavement caused by death of a sibling, maternal uncle/aunt or maternal grandparent even after stratifying deaths only due to traumatic events.
We found maternal bereavement to be adversely associated with IQ in male offspring, which could be related to prenatal stress exposure though more likely is due to changes in family conditions after death of the father. This finding supports other literature on maternal adversity during fetal life and cognitive development in the offspring.
PMCID: PMC3928249  PMID: 24558394
4.  Preeclampsia Is Associated with Alterations in the p53-Pathway in Villous Trophoblast 
PLoS ONE  2014;9(1):e87621.
Preeclampsia (PE) is characterized by exaggerated apoptosis of the villous trophoblast of placental villi. Since p53 is a critical regulator of apoptosis we hypothesized that excessive apoptosis in PE is mediated by abnormal expression of proteins participating in the p53 pathway and that modulation of the p53 pathway alters trophoblast apoptosis in vitro.
Fresh placental villous tissue was collected from normal pregnancies and pregnancies complicated by PE; Western blotting and real-time PCR were performed on tissue lysate for protein and mRNA expression of p53 and downstream effector proteins, p21, Bax and caspases 3 and 8. To further assess the ability of p53 to modulate apoptosis within trophoblast, BeWo cells and placental villous tissue were exposed to the p53-activator, Nutlin-3, alone or in combination with the p53-inhibitor, Pifithrin-α (PFT- α). Equally, Mdm2 was knocked-down with siRNA.
Protein expression of p53, p21 and Bax was significantly increased in pregnancies complicated by PE. Conversely, Mdm2 protein levels were significantly depleted in PE; immunohistochemistry showed these changes to be confined to trophoblast. Reduction in the negative feedback of p53 by Mdm2, using siRNA and Nutlin-3, caused an imbalance between p53 and Mdm2 that triggered apoptosis in term villous explants. In the case of Nutlin, this was attenuated by Pifithrin-α.
These data illustrate the potential for an imbalance in p53 and Mdm2 expression to promote excessive apoptosis in villous trophoblast. The upstream regulation of p53 and Mdm2, with regard to exaggerated apoptosis and autophagy in PE, merits further investigation.
PMCID: PMC3907567  PMID: 24498154
5.  Reduced Fetal Telomere Length in Gestational Diabetes 
PLoS ONE  2014;9(1):e86161.
Gestational diabetes mellitus (GDM) is an important complication of pregnancy that poses significant threats to women and their offspring. Telomere length shortens as cellular damage increases and is associated with metabolic diseases. Telomere length in fetal leucocytes was determined in 82 infants of women with GDM (N = 82) and 65 normal pregnant women (N = 65). Women with preeclampsia (N = 45) and gestational hypertension (N = 23) were also studied. In the GDM group, telomere length was significantly shorter than normal pregnancy (P = 0.028), but there were no significant differences in fetal telomere length between preeclampsia and normal pregnancy (P = 0.841) and between gestational hypertension and normal pregnancy (P = 0.561). Regression analysis revealed that fetal telomere length was significantly associated with intrauterine exposure to GDM (P = 0.027 after adjustment for maternal age, gestational age at delivery, birth weight and fetal gender). Shortened telomere length may increase the risk of metabolic diseases in adulthood of GDM offspring.
PMCID: PMC3899117  PMID: 24465936
6.  Preterm Birth Has Sex-Specific Effects on Autonomic Modulation of Heart Rate Variability in Adult Sheep 
PLoS ONE  2013;8(12):e85468.
Globally, 11% of infants are born preterm. In adulthood, individuals born preterm are at increased risk of cardiovascular morbidity and mortality, but the mechanistic basis of this remains unknown. Clinically overt cardiovascular disease may be preceded by altered cardiac autonomic activity characterised by increased sympathetic activity and/or reduced parasympathetic activity. Thus, altered cardiac autonomic activity in survivors of preterm birth may underlie later cardiovascular risk.
To investigate the impact of gestational age on cardiac autonomic activity in juvenile and adult sheep.
Methods and Results
Singleton-bearing ewes were randomised antenatally to spontaneous term birth (TC; n=73) or corticosteroid induced preterm birth (PT; n=60). Cardiac autonomic modulation was assessed using heart rate variability analysis in juvenile and adult offspring. Preterm birth in adult males was associated with altered sympatho-vagal modulation (LFnu: PT 64±4 vs. TC 49±4, p<0.05; LogLF/HF: PT 1.8±0.1 vs. TC 1.5±0.1, p<0.05) and reduced parasympathetic modulation (LogRMSSD: PT 2.9±0.2 vs. TC 3.4±0.1, p<0.05; LogNN50: PT 0.3±0.4 vs. TC 1.6±0.4, p<0.05). Within the range of term birth, each one-day increment in gestational age was associated with a decrement in LFnu in juvenile females and with a decrement in LFnu and LF/HF ratio, but an increment in RMSSD and NN50 in adult females.
Cardiac autonomic function in adult sheep is affected in a sex-specific manner by gestational age at birth, even within the term range. Altered cardiac autonomic function may contribute to increased later cardiovascular morbidity in those born preterm.
PMCID: PMC3873460  PMID: 24386475
7.  Antenatal Maternal Long-Term Hypoxia: Acclimatization Responses with Altered Gene Expression in Ovine Fetal Carotid Arteries 
PLoS ONE  2013;8(12):e82200.
In humans and other species, long-term hypoxia (LTH) during pregnancy can lead to intrauterine growth restriction with reduced body/brain weight, dysregulation of cerebral blood flow (CBF), and other problems. To identify the signal transduction pathways and critical molecules, which may be involved in acclimatization to high altitude LTH, we conducted microarray with advanced bioinformatic analysis on carotid arteries (CA) from the normoxic near-term ovine fetus at sea-level and those acclimatized to high altitude for 110+ days during gestation. In response to LTH acclimatization, in fetal CA we identified mRNA from 38 genes upregulated >2 fold (P<0.05) and 9 genes downregulated >2-fold (P<0.05). The major genes with upregulated mRNA were SLC1A3, Insulin-like growth factor (IGF) binding protein 3, IGF type 2 receptor, transforming growth factor (TGF) Beta-3, and genes involved in the AKT and BCL2 signal transduction networks. Most genes with upregulated mRNA have a common motif for Pbx/Knotted homeobox in the promoter region, and Sox family binding sites in the 3′ un translated region (UTR). Genes with downregulated mRNA included those involved in the P53 pathway and 5-lipoxygenase activating proteins. The promoter region of all genes with downregulated mRNA, had a common 49 bp region with a binding site for DOT6 and TOD6, components of the RPD3 histone deacetylase complex RPD3C(L). We also identified miRNA complementary to a number of the altered genes. Thus, the present study identified molecules in the ovine fetus, which may play a role in the acclimatization response to high-altitude associated LTH.
PMCID: PMC3867347  PMID: 24367503
8.  Apnea-Induced Cortical BOLD-fMRI and Peripheral Sympathoneural Firing Response Patterns of Awake Healthy Humans 
PLoS ONE  2013;8(12):e82525.
End-expiratory breath-holds (BH) and Mueller manoeuvres (MM) elicit large increases in muscle sympathetic nerve activity (MSNA). In 16 healthy humans (9♀, 35±4 years) we used functional magnetic resonance imaging with blood oxygen level-dependent (BOLD) contrast to determine the cortical network associated with such sympathoexcitation. We hypothesized that increases in MSNA evoked by these simulated apneas are accompanied by BOLD contrast changes in the insular cortex, thalamus and limbic cortex. A series of 150 whole-brain images were collected during 3 randomly performed 16-second end-expiratory BHs and MMs (-30 mmHg). The identical protocol was repeated separately with MSNA recorded from the fibular nerve. The time course of the sympathoexcitatory response to both breathing tasks were correlated with whole-brain BOLD signal changes. Brain sites demonstrating both positive (activation) and negative (deactivation) correlations with the MSNA time course were identified. Sympathetic burst incidence increased (p<0.001) from 29±6 (rest) to 49±6 (BH) and 47±6 bursts/100 heartbeats (MM). Increased neural activity (Z-scores) was identified in the right posterior and anterior insular cortices (3.74, 3.64), dorsal anterior cingulate (3.42), fastigial and dentate cerebellar nuclei (3.02, 3.34). Signal intensity decreased in the left posterior insula (3.28) and ventral anterior cingulate (3.01). Apnea both activates and inhibits elements of a cortical network involved in the generation of sympathetic outflow. These findings identify a neuroanatomical substrate to guide future investigations into central mechanisms contributing to disorders characterized by elevated basal MSNA and exaggerated sympathetic responses to simulated apneas such as sleep apnea and heart failure.
PMCID: PMC3865029  PMID: 24358198
9.  Residential Exposure to 50 Hz Magnetic Fields and the Association with Miscarriage Risk: A 2-Year Prospective Cohort Study 
PLoS ONE  2013;8(12):e82113.
The hypothesis of whether exposure to extremely low-frequency magnetic fields (ELF-MF) may increase miscarriage risk is controversial. A 2-year prospective cohort study was designed to study the association between exposure to 50 Hz magnetic fields (MF) and the miscarriage risk for women residing in the area of the Pearl-River Delta of China.
Two towns with densely distributed power supply constructions were selected as the study sites. From 2010 to 2012, 552 women in the region who were at approximately 8 weeks of gestation or who planned to have a baby within 1 year were selected as candidate subjects. Exposure to MF was estimated by measurements at their front doors and in the alley in front of the subjects’ houses. The average exposure level was used as a cutoff point to define the exposed group. Clinical miscarriage was diagnosed by local obstetricians. Staffs from the local population and family planning service stations were responsible for the follow-up interviews every 2 months.
Four hundred and thirteen pregnant women were selected for the cohort study. The average residential exposure to MF was 0.099 µT. No significantly increased risk of miscarriage was found to be associated with the average front-door exposure (p>0.05). However, miscarriage risk was found to be significantly associated with maximum alley exposure (p=0.001). The relative risk (RR) of miscarriage from maximum alley exposure was 2.35 (95% C.I.: 1.18-4.71). In addition, Cox regression analysis showed that the adjusted hazard ratio of maximum alley exposure for miscarriage was 1.72 (95% C.I.:1.10-2.69).
Although the miscarriage incidence was shown to be positively associated with the maximum alley MF exposure, the association between miscarriage risk and the exposure to MF was not confirmed in the study. The results of this study are of interest concerning MF exposure assessment and pregnancy outcomes.
PMCID: PMC3849403  PMID: 24312633
10.  Congenital Cerebral Palsy, Child Sex and Parent Cardiovascular Risk 
PLoS ONE  2013;8(11):e79071.
Genes associated with cardiovascular disease may also be risk factors for congenital cerebral palsy (CP) and these associations may be modified by sex, since there is an increased risk of CP in male children. We investigated the association between CP of the child with cardiovascular disease in parents, taking sex of the child into consideration.
All parents of non-adopted singletons born in Denmark between 1973 and 2003 were included. Parents of a child with CP, confirmed by the Danish National CP registry, were considered exposed. Cox proportional hazards regressions were used to model risk of cardiovascular outcomes for exposed parents compared to all other parents beginning at the child’s 10th birthday.
We identified 733,730 mothers and 666,652 fathers among whom 1,592 and 1,484, respectively, had a child with CP. The mean age for mothers at end of follow up was 50±8 years. After adjustment for maternal age, parental education, child’s sex, child’s residence, child being small for gestational age and maternal hypertensive disorder during pregnancy, mothers of CP male children had an excess risk of cardiovascular disease (HR: 1.52, 95% CI: 1.16-2.00), attributable mostly to an increased incidence of hypertension and cerebrovascular disease. After additional adjustment for preterm birth, the association was markedly attenuated for cardiovascular disease (1.34, 95%CI: 1.02 - 1.76), became nonsignificant for hypertension, but remained significant for cerebrovascular disease (HR: 2.73, 95% CI: 1.45- 5.12). There was no increased risk of cardiovascular events in mothers of female CP children, or fathers of CP children of any sex.
Women that have a male child with CP are at increased risk for premature cardiovascular disease. Part of this association may be related to risk factors for preterm births.
PMCID: PMC3815096  PMID: 24223882
11.  Partial Sleep Restriction Activates Immune Response-Related Gene Expression Pathways: Experimental and Epidemiological Studies in Humans 
PLoS ONE  2013;8(10):e77184.
Epidemiological studies have shown that short or insufficient sleep is associated with increased risk for metabolic diseases and mortality. To elucidate mechanisms behind this connection, we aimed to identify genes and pathways affected by experimentally induced, partial sleep restriction and to verify their connection to insufficient sleep at population level. The experimental design simulated sleep restriction during a working week: sleep of healthy men (N = 9) was restricted to 4 h/night for five nights. The control subjects (N = 4) spent 8 h/night in bed. Leukocyte RNA expression was analyzed at baseline, after sleep restriction, and after recovery using whole genome microarrays complemented with pathway and transcription factor analysis. Expression levels of the ten most up-regulated and ten most down-regulated transcripts were correlated with subjective assessment of insufficient sleep in a population cohort (N = 472). Experimental sleep restriction altered the expression of 117 genes. Eight of the 25 most up-regulated transcripts were related to immune function. Accordingly, fifteen of the 25 most up-regulated Gene Ontology pathways were also related to immune function, including those for B cell activation, interleukin 8 production, and NF-κB signaling (P<0.005). Of the ten most up-regulated genes, expression of STX16 correlated negatively with self-reported insufficient sleep in a population sample, while three other genes showed tendency for positive correlation. Of the ten most down-regulated genes, TBX21 and LGR6 correlated negatively and TGFBR3 positively with insufficient sleep. Partial sleep restriction affects the regulation of signaling pathways related to the immune system. Some of these changes appear to be long-lasting and may at least partly explain how prolonged sleep restriction can contribute to inflammation-associated pathological states, such as cardiometabolic diseases.
PMCID: PMC3806729  PMID: 24194869
12.  Long-Term Functional Outcomes and Correlation with Regional Brain Connectivity by MRI Diffusion Tractography Metrics in a Near-Term Rabbit Model of Intrauterine Growth Restriction 
PLoS ONE  2013;8(10):e76453.
Intrauterine growth restriction (IUGR) affects 5–10% of all newborns and is associated with increased risk of memory, attention and anxiety problems in late childhood and adolescence. The neurostructural correlates of long-term abnormal neurodevelopment associated with IUGR are unknown. Thus, the aim of this study was to provide a comprehensive description of the long-term functional and neurostructural correlates of abnormal neurodevelopment associated with IUGR in a near-term rabbit model (delivered at 30 days of gestation) and evaluate the development of quantitative imaging biomarkers of abnormal neurodevelopment based on diffusion magnetic resonance imaging (MRI) parameters and connectivity.
At +70 postnatal days, 10 cases and 11 controls were functionally evaluated with the Open Field Behavioral Test which evaluates anxiety and attention and the Object Recognition Task that evaluates short-term memory and attention. Subsequently, brains were collected, fixed and a high resolution MRI was performed. Differences in diffusion parameters were analyzed by means of voxel-based and connectivity analysis measuring the number of fibers reconstructed within anxiety, attention and short-term memory networks over the total fibers.
Principal Findings
The results of the neurobehavioral and cognitive assessment showed a significant higher degree of anxiety, attention and memory problems in cases compared to controls in most of the variables explored. Voxel-based analysis (VBA) revealed significant differences between groups in multiple brain regions mainly in grey matter structures, whereas connectivity analysis demonstrated lower ratios of fibers within the networks in cases, reaching the statistical significance only in the left hemisphere for both networks. Finally, VBA and connectivity results were also correlated with functional outcome.
The rabbit model used reproduced long-term functional impairments and their neurostructural correlates of abnormal neurodevelopment associated with IUGR. The description of the pattern of microstructural changes underlying functional defects may help to develop biomarkers based in diffusion MRI and connectivity analysis.
PMCID: PMC3797044  PMID: 24143189
13.  Impaired Mouse Mammary Gland Growth and Development is Mediated by Melatonin and its MT1 G Protein-Coupled Receptor via Repression of ERα, Akt1, and Stat5 
Journal of pineal research  2012;53(3):307-318.
To determine if melatonin, via its MT1 G protein-coupled receptor (GPCR), impacts mouse mammary gland development, we generated a mouse mammary tumor virus (MMTV)-MT1-Flag-mammary gland over-expressing (MT1-mOE) transgenic mouse. Increased expression of the MT1-Flag transgene was observed in the mammary glands of pubescent MT1-mOE transgenic female mice, with further significant increases during pregnancy and lactation. Mammary gland whole mounts from MT1-mOE mice showed significant reductions in ductal growth, ductal branching, and terminal end bud (TEB) formation. Elevated MT1 receptor expression in pregnant and lactating female MT1-mOE mice was associated with reduced lobulo-alveolar development, inhibition of mammary epithelial cell proliferation, and significant reductions in body weights of suckling pups. Elevated MT1 expression in pregnant and lactating MT1-mOE mice correlated with reduced mammary gland expression of Akt1, phospho-Stat5, Wnt4, estrogen receptor alpha (ERα), progesterone receptors (PR) A and B, and milk proteins β-casein and whey acidic protein (WAP). Estrogen and progesterone stimulated mammary gland development was repressed by elevated MT1 receptor expression and exogenous melatonin administration. These studies demonstrate that the MT1 melatonin receptor and its ligand melatonin play an important regulatory role in mammary gland development and lactation in mice through both growth suppression and alteration of developmental paradigms.
PMCID: PMC3422609  PMID: 22582905
Melatonin; MT1 Receptor; AKT; Stat5; Mammary Gland Development
14.  Improved bioavailability of inhibitors of Trypanosoma cruzi trans-sialidase: PEGylation of lactose analogs with multiarm polyethyleneglycol 
Glycobiology  2012;22(10):1363-1373.
The trans-sialidase of Trypanosoma cruzi (TcTS) catalyzes the transfer of sialic acid from host glycoconjugates to terminal β-galactopyranosides in the mucins of the parasite. During infection, the enzyme is actively shed by the parasite to the bloodstream inducing hematological alterations. Lactitol prevents cell apoptosis caused by the TcTS, although it is rapidly eliminated from the circulatory system. Linear polyethyleneglycol (PEG) conjugates of lactose analogs were prepared but their clearance from blood was still quite fast. With the aim of improving their circulating half-lives in vivo, we now synthesized covalent conjugates of eight-arm PEG. The star-shape of these conjugates allows an increase in the molecular weight together with the loading of the active sugar. Two approaches were used for PEGylation of disaccharide derivatives containing β-d-Galp as the non-reducing unit. (1) Amide formation between benzyl β-d-galactopyranosyl-(1→6)-2-amino-2-deoxy-α-d-glucopyranoside and a succinimide-activated PEG. (2) Conjugation of lactobionolactone with amino end-functionalized PEG. Two 8-arm PEG derivatives (20 and 40 kDa) were used for each sugar. Substitution of all arms was proved by 1H nuclear magnetic resonance (NMR) spectroscopy. The bioavailability of the conjugates in mice plasma was considerably improved with respect to the 5 kDa linear PEG conjugates retaining their inhibitory properties.
PMCID: PMC3425324  PMID: 22653661
inhibitors; multiarm conjugates; PEGylation; trans-sialidase; Trypanosoma cruzi
15.  A Population Model of Integrative Cardiovascular Physiology 
PLoS ONE  2013;8(9):e74329.
We present a small integrative model of human cardiovascular physiology. The model is population-based; rather than using best fit parameter values, we used a variant of the Metropolis algorithm to produce distributions for the parameters most associated with model sensitivity. The population is built by sampling from these distributions to create the model coefficients. The resulting models were then subjected to a hemorrhage. The population was separated into those that lost less than 15 mmHg arterial pressure (compensators), and those that lost more (decompensators). The populations were parametrically analyzed to determine baseline conditions correlating with compensation and decompensation. Analysis included single variable correlation, graphical time series analysis, and support vector machine (SVM) classification. Most variables were seen to correlate with propensity for circulatory collapse, but not sufficiently to effect reasonable classification by any single variable. Time series analysis indicated a single significant measure, the stressed blood volume, as predicting collapse in situ, but measurement of this quantity is clinically impossible. SVM uncovered a collection of variables and parameters that, when taken together, provided useful rubrics for classification. Due to the probabilistic origins of the method, multiple classifications were attempted, resulting in an average of 3.5 variables necessary to construct classification. The most common variables used were systemic compliance, baseline baroreceptor signal strength and total peripheral resistance, providing predictive ability exceeding 90%. The methods presented are suitable for use in any deterministic mathematical model.
PMCID: PMC3772858  PMID: 24058546
16.  Quantifying Memory in Complex Physiological Time-Series 
PLoS ONE  2013;8(9):e72854.
In a time-series, memory is a statistical feature that lasts for a period of time and distinguishes the time-series from a random, or memory-less, process. In the present study, the concept of “memory length” was used to define the time period, or scale over which rare events within a physiological time-series do not appear randomly. The method is based on inverse statistical analysis and provides empiric evidence that rare fluctuations in cardio-respiratory time-series are ‘forgotten’ quickly in healthy subjects while the memory for such events is significantly prolonged in pathological conditions such as asthma (respiratory time-series) and liver cirrhosis (heart-beat time-series). The memory length was significantly higher in patients with uncontrolled asthma compared to healthy volunteers. Likewise, it was significantly higher in patients with decompensated cirrhosis compared to those with compensated cirrhosis and healthy volunteers. We also observed that the cardio-respiratory system has simple low order dynamics and short memory around its average, and high order dynamics around rare fluctuations.
PMCID: PMC3764113  PMID: 24039811
17.  Imbalanced Frequencies of Th17 and Treg Cells in Acute Coronary Syndromes Are Mediated by IL-6-STAT3 Signaling 
PLoS ONE  2013;8(8):e72804.
Extensive evidence suggests inflammatory components participate in the pathogenic processes of acute coronary syndromes (ACS). In this study, we aimed to elucidate the role and mechanism underlying the imbalance of Th17 and Treg cell peripheral populations in the pathogenesis of ACS.
Methods and Results
Using a flow cytometric analysis, we observed a significantly increased frequency of Th17 cells and a concurrently decreased CD4+CD25+Foxp3+ Treg cells in patients with ACS. To elucidate the mechanism of Th17/Treg imbalance in ACS, 22 inflammatory cytokines were measured using multiplexed immunobead-based assays. Of six elevated cytokines in ACS patients, only IL-6 was positively correlated with a higher Th17 cell level (r = 0.39, P<0.01). Relying on IL-6 stimulating and neutralizing studies, we demonstrated a direct role for IL-6 in sera from ACS patients with an increased frequency of Th17 cells. IL-6 induces the differentiation of Th17 cells from naïve CD4+ T cells through STAT3 activation and RORγt induction. However, we observed that high levels of TGF-β1 inhibited IL-6-dependent Th17 cell differentiation, indicating a complex interplay between the two cytokines in the control of Th17 and Treg cell populations.
Our results demonstrate the role of IL-6-STAT3 signaling in ACS through increased Th17 cell differentiation. These findings indicate that IL-6 neutralizing strategies could present novel therapeutic avenues in the treatment of ACS.
PMCID: PMC3753235  PMID: 23991153
18.  Pre-Existing Hypoxia Is Associated with Greater EEG Suppression and Early Onset of Evolving Seizure Activity during Brief Repeated Asphyxia in Near-Term Fetal Sheep 
PLoS ONE  2013;8(8):e73895.
Spontaneous antenatal hypoxia is associated with high risk of adverse outcomes, however, there is little information on neural adaptation to labor-like insults. Chronically instrumented near-term sheep fetuses (125 ± 3 days, mean ± SEM) with baseline PaO2 < 17 mmHg (hypoxic group: n = 8) or > 17 mmHg (normoxic group: n = 8) received 1-minute umbilical cord occlusions repeated every 5 minutes for a total of 4 hours, or until mean arterial blood pressure (MAP) fell below 20 mmHg for two successive occlusions. 5/8 fetuses with pre-existing hypoxia were unable to complete the full series of occlusions (vs. 0/8 normoxic fetuses). Pre-existing hypoxia was associated with progressive metabolic acidosis (nadir: pH 7.08 ± 0.04 vs. 7.33 ± 0.02, p<0.01), hypotension during occlusions (nadir: 24.7 ± 1.8 vs. 51.4 ± 3.2 mmHg, p<0.01), lower carotid blood flow during occlusions (23.6 ± 6.1 vs. 63.0 ± 4.8 mL/min, p<0.01), greater suppression of EEG activity during, between, and after occlusions (p<0.01) and slower resolution of cortical impedance, an index of cytotoxic edema. No normoxic fetuses, but 4/8 hypoxic fetuses developed seizures 148 ± 45 minutes after the start of occlusions, with a seizure burden of 26 ± 6 sec during the inter-occlusion period, and 15.1 ± 3.4 min/h in the first 6 hours of recovery. In conclusion, in fetuses with pre-existing hypoxia, repeated brief asphyxia at a rate consistent with early labor is associated with hypotension, cephalic hypoperfusion, greater EEG suppression, inter-occlusion seizures, and more sustained cytotoxic edema, consistent with early onset of neural injury.
PMCID: PMC3749175  PMID: 23991209
19.  Induction of TGF-β1 Synthesis by Macrophages in Response to Apoptotic Cells Requires Activation of the Scavenger Receptor CD36 
PLoS ONE  2013;8(8):e72772.
Phosphatidylserine (PS) exposed on apoptotic cells has been shown to stimulate production of transforming growth factor-β (TGF-β) and promote anti-inflammatory responses. However, the PS receptor(s) responsible for this induction has not been clearly determined.
Methodology/Principal Findings
In the present study, using RAWTβRII cells in which a truncated dominant negative TGF-β receptor II was stably transfected in order to avoid auto-feedback induction of TGF-β, we show that TGF-β1 synthesis is initiated via activation of the scavenger receptor, CD36. The response requires exposure of PS on the apoptotic cell surface and was absent in macrophages lacking CD36. Direct activation of CD36 with an anti-CD36 antibody initiated TGF-β1 production, and signaling pathways involving both Lyn kinase and ERK1/2 were shown to participate in CD36-driven TGF-β1 expression.
Since CD36 has been previously implicated in activation of secreted latent TGF-β, the present study indicates its role in the multiple steps to generation of this important biological mediator.
PMCID: PMC3732218  PMID: 23936544
20.  Characterization of the M32 metallocarboxypeptidase of Trypanosoma brucei: differences and similarities with its orthologue in Trypanosoma cruzi 
Metallocarboxypeptidases (MCP) of the M32 family of peptidases have been identified in a number of prokaryotic organisms but they are absent from eukaryotic genomes with the remarkable exception of those of trypanosomatids. The genome of Trypanosoma brucei, the causative agent of Sleeping Sickness, encodes one such MCP which displays 72% identity to the characterized TcMCP-1 from Trypanosoma cruzi. As its orthologue, TcMCP-1, Trypanosoma brucei MCP is a cytosolic enzyme expressed in both major stages of the parasite. Purified recombinant TbMCP-1 exhibits a significant hydrolytic activity against the carboxypeptidase B substrate FA (furylacryloil)-Ala-Lys at pH 7.0–7.8 resembling the T. cruzi enzyme. S everal divalent cations had little effect on TbMCP-1 activity but increasing amounts of Co2+ inhibited the enzyme. Despite having similar tertiary structure, both protozoan MCPs display different substrate specificity with respect to P1 position. Thus, TcMCP-1 enzyme cleaved Abz-FVK-(Dnp)-OH substrate (where Abz: o-aminobenzoic acid and Dnp: 2,4-dinitrophenyl) whereas TbMCP-1 had no activity on this substrate. Comparative homology models and sequence alignments using TcMCP-1 as a template led us to map several residues that could explain this difference. To verify this hypothesis, site-directed mutagenesis was undertaken replacing the TbMCP-1 residues by those present in TcMCP-1. We found that the substitution A414M led TbMCP-1 to gain activity on Abz-FVK-(Dnp)-OH, thus showing that this residue is involved in specificity determination, probably being part of the S1 sub-site. Moreover, the activity of both protozoan MCPs was explored on two vasoactive compounds such as bradykinin and angiotensin I resulting in two different hydrolysis patterns.
PMCID: PMC3383389  PMID: 22575602
Trypanosoma brucei; carboxypeptidase; M32 family; FRET peptides; Trypanosoma cruzi; peptidase
21.  The FGF8-related signals Pyramus and Thisbe promote pathfinding, substrate adhesion, and survival of migrating longitudinal gut muscle founder cells 
Developmental biology  2012;368(1):28-43.
Fibroblast growth factors (FGFs) frequently fulfill prominent roles in the regulation of cell migration in various contexts. In Drosophila, the FGF8-like ligands Pyramus (Pyr) and Thisbe (Ths), which signal through their receptor Heartless (Htl), are known to regulate early mesodermal cell migration after gastrulation as well as glial cell migration during eye development. Herein, we show that Pyr and Ths also exert key roles during the long-distance migration of a specific sub-population of mesodermal cells that migrate from the caudal visceral mesoderm within stereotypic bilateral paths along the trunk visceral mesoderm toward the anterior. These cells constitute the founder myoblasts of the longitudinal midgut muscles. In a forward genetic screen for regulators of this morphogenetic process we identified loss of function alleles for pyr. We show that pyr and ths are expressed along the paths of migration in the trunk visceral mesoderm and endoderm and act largely redundantly to help guide the founder myoblasts reliably onto and along their substrate of migration. Ectopically-provided Pyr and Ths signals can efficiently re-rout the migrating cells, both in the presence and absence of endogenous signals. Our data indicate that the guidance functions of these FGFs must act in concert with other important attractive or adhesive activities of the trunk visceral mesoderm. Apart from their guidance functions, the Pyr and Ths signals play an obligatory role for the survival of the migrating cells. Without these signals, essentially all of these cells enter cell death and detach from the migration substrate during early migration. We present experiments that allowed us to dissect the roles of these FGFs as guidance cues versus trophic activities during the migration of the longitudinal visceral muscle founders.
PMCID: PMC3589571  PMID: 22609944
Cell migration; Cell survival; Fibroblast growth factor; Visceral mesoderm; Gut muscle development
22.  Genome-wide analysis of 3′-untranslated regions supports the existence of post-transcriptional regulons controlling gene expression in trypanosomes 
PeerJ  2013;1:e118.
In eukaryotic cells, a group of messenger ribonucleic acids (mRNAs) encoding functionally interrelated proteins together with the trans-acting factors that coordinately modulate their expression is termed a post-transcriptional regulon, due to their partial analogy to a prokaryotic polycistron. This mRNA clustering is organized by sequence-specific RNA-binding proteins (RBPs) that bind cis-regulatory elements in the noncoding regions of genes, and mediates the synchronized control of their fate. These recognition motifs are often characterized by conserved sequences and/or RNA structures, and it is likely that various classes of cis-elements remain undiscovered. Current evidence suggests that RNA regulons govern gene expression in trypanosomes, unicellular parasites which mainly use post-transcriptional mechanisms to control protein synthesis. In this study, we used motif discovery tools to test whether groups of functionally related trypanosomatid genes contain a common cis-regulatory element. We obtained conserved structured RNA motifs statistically enriched in the noncoding region of 38 out of 53 groups of metabolically related transcripts in comparison with a random control. These motifs have a hairpin loop structure, a preferred sense orientation and are located in close proximity to the open reading frames. We found that 15 out of these 38 groups represent unique motifs in which most 3′-UTR signature elements were group-specific. Two extensively studied Trypanosoma cruzi RBPs, TcUBP1 and TcRBP3 were found associated with a few candidate RNA regulons. Interestingly, 13 motifs showed a strong correlation with clusters of developmentally co-expressed genes and six RNA elements were enriched in gene clusters affected after hyperosmotic stress. Here we report a systematic genome-wide in silico screen to search for novel RNA-binding sites in transcripts, and describe an organized network of several coordinately regulated cohorts of mRNAs in T. cruzi. Moreover, we found that structured RNA elements are also conserved in other human pathogens. These results support a model of regulation of gene expression by multiple post-transcriptional regulons in trypanosomes.
PMCID: PMC3728762  PMID: 23904995
RNA-binding protein; Trypanosomes; Cis-element; Post-transcriptional control; RNA regulon
23.  Effects of Maternal Obstructive Sleep Apnoea on Fetal Growth: A Prospective Cohort Study 
PLoS ONE  2013;8(7):e68057.
The objective of this study is to determine whether obstructive sleep apnea (OSA) is associated with reduced fetal growth, and whether nocturnal oxygen desaturation precipitates acute fetal heart rate changes.
Study Design
We performed a prospective observational study, screening 371 women in the second trimester for OSA symptoms. 41 subsequently underwent overnight sleep studies to diagnose OSA. Third trimester fetal growth was assessed using ultrasound. Fetal heart rate monitoring accompanied the sleep study. Cord blood was taken at delivery, to measure key regulators of fetal growth.
Of 371 women screened, 108 (29%) were high risk for OSA. 26 high risk and 15 low risk women completed the longitudinal study; 14 had confirmed OSA (cases), and 27 were controls. The median (interquartile range) respiratory disturbance index (number of apnoeas, hypopnoeas or respiratory related arousals/hour of sleep) was 7.9 (6.1–13.8) for cases and 2.2 (1.3–3.5) for controls (p<0.001). Impaired fetal growth was observed in 43% (6/14) of cases, vs 11% (3/27) of controls (RR 2.67; 1.25–5.7; p = 0.04). Using logistic regression, only OSA (OR 6; 1.2–29.7, p = 0.03) and body mass index (OR 2.52; 1.09–5.80, p = 0.03) were significantly associated with impaired fetal growth. After adjusting for body mass index on multivariate analysis, the association between OSA and impaired fetal growth was not appreciably altered (OR 5.3; 0.93–30.34, p = 0.06), although just failed to achieve statistical significance. Prolonged fetal heart rate decelerations accompanied nocturnal oxygen desaturation in one fetus, subsequently found to be severely growth restricted. Fetal growth regulators showed changes in the expected direction- with IGF-1 lower, and IGFBP-1 and IGFBP-2 higher- in the cord blood of infants of cases vs controls, although were not significantly different.
OSA may be associated with reduced fetal growth in late pregnancy. Further evaluation is warranted to establish whether OSA may be an important contributor to adverse perinatal outcome, including stillbirth.
PMCID: PMC3722214  PMID: 23894293
24.  A Pig Model of the Preterm Neonate: Anthropometric and Physiological Characteristics 
PLoS ONE  2013;8(7):e68763.
Large animal models are an essential tool in the development of rationally-based new clinical therapies for preterm infants. We provide a description of the newborn pig as a model of the preterm neonate in terms of growth parameters, physiology and the requirement for intensive care over a range of gestational ages.
Twenty-nine litters of piglets (n = 298) were delivered by caesarean section at six timepoints during gestation from 91d to 113d (term = 115d). Two groups, at 91 and 97d gestation, also received maternal glucocorticoid treatment. At four of these timepoints, piglets (n = 79) were ventilated, sedated and monitored using standard neonatal intensive care techniques for up to 8 h in various experimental protocols.
Body weight increased from mean 697 g (SD 193) at 91d gestation to 1331 g (SD 368) at 113d gestation. Piglets delivered at 97d gestation were able to be resuscitated and kept alive for at least 8 h on respiratory support after surfactant administration. Maternal glucocorticoid treatment 48 h and 24 h hours prior to delivery reduced the requirement for ventilator support and improved cardiovascular stability.
The pig provides a relevant model for the study of human preterm physiology and for investigation of novel therapies to improve outcomes.
PMCID: PMC3706365  PMID: 23874755
25.  Emerging roles for lysophosphatidylserine in resolution of inflammation 
Progress in Lipid Research  2012;51(3):199-207.
Despite overlapping structural aspects with other phospholipids, lysophosphatidylserine (lysoPS), the monoacyl derivative of phosphatidylserine (diacylPS), appears to exert unique signaling characteristics important in both the early stages of initiating acute inflammation and in the orchestration of its resolution. LysoPS has long been known as a signaling phospholipid in mast cell biology, markedly enhancing stimulated histamine release and eicosanoid production. More recently, there has been a resurgence of interest in lysoPS as new roles in the promotion of phagocytosis of apoptotic cells, so-called efferocytosis, and resolution of inflammation have been identified. With regard to the latter, lysoPS generated in/on activated or aged apoptotic neutrophils enhances their clearance by macrophages via signaling through the macrophage G-protein coupled receptor G2A. In macrophages, this early acting pathway results in PKA-dependent augmentation of Rac1 activity via increased production of PGE2 and cAMP. As such, macrophages stimulated with lysoPS demonstrate significantly increased efferocytic capacity necessary to clear large numbers of recruited neutrophils typical of acute inflammation. Given that clearance of these cells is critical for restoration of tissue function, lysoPS, as a pro-resolving lipid mediator, is hypothesized to play a key role in promoting timely resolution of inflammation. This article will review our current knowledge of lysoPS biology including receptor signaling and mechanisms of generation as well as summarize the more recent evidence of its expanding roles in inflammation.
PMCID: PMC3365616  PMID: 22465125

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