Epigenetics and cardiovascular risk in childhood

Differentially methylated regions interrogated for metastable epialleles associate with offspring adiposity

Aim: Assess if cord blood differentially methylated regions (DMRs) representing human metastable epialleles (MEs) associate with offspring adiposity in 588 maternal-infant dyads from the Colorado Health Start Study.Materials & methods: DNA methylation was assessed via the Illumina 450K array (~439,500 CpG sites). Offspring adiposity was obtained via air displacement plethysmography. Linear regression modeled the association of DMRs potentially representing MEs with adiposity.Results & conclusion: We identified two potential MEs, ZFP57, which associated with infant adiposity change and B4GALNT4, which associated with infancy and childhood adiposity change. Nine DMRs annotating to genes that annotated to MEs associated with change in offspring adiposity (false discovery rate <0.05). Methylation of approximately 80% of DMRs identified associated with decreased change in adiposity.

Cardiovascular prevention in childhood: a consensus document of the Italian Society of Cardiology Working Group on Congenital Heart Disease and Cardiovascular Prevention in Paediatric Age

Cardiovascular diseases (CVD) may be manifested from a very early age. Genetic and environmental (epigenetic) factors interact to affect development and give rise to an abnormal phenotypical expression of genetic information, although not eliciting changes in the nucleotide sequence of DNA. It has been scientifically proven that increased oxidative stress (OS) caused by disease (overweight, obesity, diabetes), nutritional imbalances, unhealthy lifestyles (smoking, alcohol, substance abuse) in the mother during pregnancy may induce placental dysfunction, intrauterine growth restriction, prematurity, low birth weight, postnatal adiposity rebound, metabolic alterations and consequent onset of traditional cardiovascular risk factors. OS represents the cornerstone in the onset of atherosclerosis and manifestation of CVD following an extended asymptomatic period. OS activates platelets and monocytes eliciting the release of pro-inflammatory, pro-atherogenic and pro-oxidising substances resulting in endothelial dysfunction, decrease in flow-mediated arterial dilatation and increase in carotid intima-media thickness. The prevention of CVD is defined as primordial (aimed at preventing risk factors development), primary (aimed at early identification and treatment of risk factors), secondary (aimed at reducing risk of future events in patients who have already manifested a cardiovascular event), and tertiary (aimed at limiting the complex outcome of disease). Atherosclerosis prevention should be implemented as early as possible. Appropriate screening should be carried out to identify children at high risk who are apparently healthy and implement measures including dietary and lifestyle changes, addition of nutritional supplements and, lastly, pharmacological treatment if risk profiles fail to normalise. Reinstating endothelial function during the reversible stage of atherosclerosis is crucial.

The interplay between DNA methylation and cardiac autonomic system functioning: a systematic review

Epigenetic marks, particularly DNA methylation (DNAm), are emerging as an important biological marker of susceptibility to cardiac autonomic dysfunction. This review summarizes recent discoveries about the association between DNAm and cardiac autonomic activity. A systematic literature search was performed through the Embase, Web of Science, Cochrane Library, Pubmed, PsycINFO, and Pilots databases. Twenty-two studies met inclusion criteria, of which 18 were human studies including a total of 2,686 participants. DNAm differences in multiple genes, such as NR3C1, TLR2, GPR133, EPO, PHGDH, OXTR, and SLC7A11, linked environmental stressors to physiological responses. For instance, exposure to psychosocial stressors increased NR3C1 methylation, which was associated with both decreased blood pressure and increased parasympathetic activity. Additionally, GPR133 played a potential role in cardiac autonomic dysfunction in an occupational setting, affecting the heart rate's deceleration capacity in welders. This review's findings suggest that DNAm is involved in cardiac autonomic regulation under different stress-mediated responses.

Prenatal caffeine exposure induced renal developmental toxicity and transgenerational effect in rat offspring

Epidemiological studies revealed that prenatal caffeine exposure (PCE) is associated with adverse gestational outcomes and susceptibility to chronic diseases in offspring, yet the effects of PCE on glomerulosclerosis susceptibility in adult female offspring and its intergenerational transmission remain to be further investigated. Here, we found that PCE caused fetal kidney dysplasia and glomerulosclerosis of the female offspring. Besides, the kidney of F1 offspring in PCE group exhibited the "low expressional programming of AT2R" and "GC-IGF1 programming" alteration. Intergenerational genetic studies revealed that the renal defect and GC-IGF1 programming alteration was inherited to F2 adult female offspring derived from the female germ line, but Low expression of AT2R did not extend to the F2 female offspring. Taken together, PCE caused renal dysplasia and adult glomerulosclerosis in the F1 female offspring, which might be mediated by renal AT2R low expressional programming and GC-IGF1 axis alteration. Furthermore, PCE induced transgenerational toxicity on kidney, and GC-IGF1 programming alteration might be the potential molecular mechanism. This study provided experimental evidence for the mechanism study of the intergenerational inheritance of kidney developmental toxicity caused by PCE.

Epigenetic Age Acceleration Reflects Long-Term Cardiovascular Health

[Figure: see text].

Cardiovascular Risk Factors in Children with Obesity, Preventive Diagnostics and Possible Interventions

The increasing burden of obesity plays an essential role in increased cardiovascular morbidity and mortality. The effects of obesity on the cardiovascular system have also been demonstrated in childhood, where prevention is even more important. Obesity is associated with hormonal changes and vascular dysfunction, which eventually lead to hypertension, hyperinsulinemia, chronic kidney disease, dyslipidemia and cardiac dysfunction—all associated with increased cardiovascular risk, leading to potential cardiovascular events in early adulthood. Several preventive strategies are being implemented to reduce the cardiovascular burden in children. This paper presents a comprehensive review of obesity-associated cardiovascular morbidity with the preventive diagnostic workup at our hospital and possible interventions in children.

Renal NKCC2 Is Dual Regulated by the Synergy of 20-HETE and High-Fat Diet in CYP4F2 Transgenic Mice

INTRODUCTION

20-Hydroxyeicosatetraenoic acid (20-HETE) is the metabolite of cytochrome P450, which modulates blood pressure by inhibiting renal sodium transport. However, the molecular mechanisms underlying the role of 20-HETE in the development of obesity-related hypertension remain unclear, necessitating this study.

METHODS

Cytochrome P450 4F2 (CYP4F2) transgenic mice fed high-fat diet (HFD) were used as research animal models. The expression of renal ion transport molecules targeted by 20-HETE was evaluated by real-time PCR and Western blot (WB). The regulatory effect of 20-HETE and HFD on renal Na+-K+-2Cl- cotransporter, isoform 2 (NKCC2) was explored by immunoprecipitation, WB, and luciferase assay.

RESULTS

A 2-week HFD feeding dramatically decreased protein abundance but increased renal NKCC2 mRNA expression in CYP4F2 transgenic mice. The decrease in NKCC2 protein was demonstrated to be due to ubiquitination induced by the synergy between 20-HETE and HFD. The increased PPAR-γ protein in CYP4F2 transgenic mice fed HFD and the activation of rosiglitazone on the luciferase reporter construct of the NKCC2 promoter demonstrated that the increase in NKCC2 mRNA in CYP4F2 transgenic mice fed HFD was a consequence of elevated PPAR-γ protein induced by the synergy between 20-HETE and HFD.

CONCLUSIONS

Our data demonstrated that the synergy between 20-HETE and HFD could decrease NKCC2 protein via posttranslational ubiquitination, which was thought to be the main mechanism underlying the short-term effect in response to HFD and might be responsible for the adaptive modulation of renal NKCC2 to resist sodium retention. Moreover, the increased NKCC2 mRNA expression via PPAR-γ-induced transcriptional regulation was thought to be the main mechanism underlying the long-term effect in response to HFD and plays a pivotal role in the development of obesity-related hypertension.

Paternal inheritance predicts earlier cardiovascular event onset in patients with familial hypercholesterolemia

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is a genetic disease, with an autosomal codominant inheritance, predisposing to premature atherosclerotic cardiovascular disease (ASCVD). Paternal or maternal inheritance of the FH-causing mutation may affect the FH phenotype in offspring, but the effect of the genetic transmission on cardiovascular disease risk remains to be established. The aim of the present study is to compare the incidence of cardiovascular events between patients with maternal vs paternal inheritance of familial hypercholesterolemia.

METHODS

We prospectively studied 725 genetically-confirmed FH patients (33,805 person-years), including 268 with maternal inheritance and 321 with paternal inheritance of the mutation. ASCVD was defined as angina, myocardial infarction, coronary angioplasty, coronary bypass surgery, claudication, peripheral angioplasty, peripheral arterial surgery, transient ischemic attack, stroke, carotid endarterectomy and CV death. Cox-proportional hazard models and Kaplan-Meier analysis were used to compare the two groups.

RESULTS

Before 50 years of age, paternal inheritance of FH was associated with a 1.5-fold increased risk for ASCVD, as compared to maternal inheritance (HR 1.59, 95% CI 1.11-2.28, p = 0.01). This association remained significant after adjusting for confounding factors (HR 1.49, 95% CI 1.00-2.23, p = 0.05). The age of first ASCVD event was also significantly lower in the paternal inheritance group (42 years) than in the maternal inheritance group (46 years), p = 0.02.

CONCLUSIONS

This study suggests that paternal inheritance of the FH-causing mutation was associated with an earlier cardiovascular event onset compared to maternal inheritance. The mechanisms behind these findings remain to be established.

Extremely Low Birth Weight and Accelerated Biological Aging

BACKGROUND AND OBJECTIVES

Extremely low birth weight (ELBW) (<1000 g) survivors are exposed to elevated levels of physiologic stress during their lives and may be susceptible to accelerated aging. Using the oldest known longitudinally followed cohort of ELBW survivors, we compared biological aging in this group using an epigenetic clock to a sample of matched normal birth weight (NBW) (>2500 g) control participants.

METHODS

Buccal cells were collected from 45 ELBW survivors and 49 NBW control participants at 30 to 35 years of age. Epigenetic age was calculated from the weighted average of DNA methylation at 353 cytosine-phosphate-guanine sequence within DNA sites, by using the Illumina Infinium Human Methylation EPIC 850k BeadChip array.

RESULTS

Before and after statistically adjusting for neurosensory impairment and the presence of chronic health conditions, a significant sex by birth weight group interaction was observed in the 353-site epigenetic-clock assay (P = .03), whereby ELBW men had a significantly older epigenetic age than NBW men (4.6 years; P = .01). Women born at ELBW were not found to be epigenetically older than their NBW peers.

CONCLUSIONS

The results of this study suggest that prenatal exposures may play an important role in aging, and that men born preterm may experience accelerated aging relative to their peers. We further highlight the need to monitor and promote the health of preterm survivors, with a particular focus on healthy aging across the life span.

Prenatal dexamethasone exposure induces nonalcoholic fatty liver disease in male rat offspring via the miR-122/YY1/ACE2-MAS1 pathway

Epidemiological studies have shown that nonalcoholic fatty liver disease (NAFLD) has an intrauterine developmental origin. We aimed to demonstrate that NAFLD is caused by prenatal dexamethasone exposure (PDE) in adult male rat offspring and to investigate the intrauterine programming mechanism. Liver samples were obtained on gestational day (GD) 21 and postnatal week (PW) 28. The effects and epigenetic mechanism of dexamethasone were studied with bone marrow mesenchymal stem cells (BMSCs) hepatoid differentiated cells and other cell models. In the PDE group, lipid accumulation increased, triglyceride synthesis-related gene expression increased, and oxidation-related gene expression decreased in livers of adult male rat offspring. In utero, hepatic triglyceride synthesis increased and oxidative function decreased in PDE fetal male rats. Moreover, low hepatic miR-122 expression, high Yin Yang-1 (YY1) expression and angiotensin-converting enzyme 2 (ACE2)-Mas receptor (MAS1) signaling pathway inhibition were observed before and after birth. At the cellular level, dexamethasone (100-2500 nM) elevated the intracellular triglyceride content, increased triglyceride synthesis-related gene expression and decreased oxidation-related gene expression. Dexamethasone treatment also decreased miR-122 expression, increased YY1 expression and inhibited the ACE2-MAS1 signaling pathway. Interference or overexpression of glucocorticoid receptor (GR), miR-122, YY1 and ACE2 could reverse the changes in downstream gene expression. In summary, PDE could induce NAFLD in adult male rat offspring. The programming mechanism included inhibition of miR-122 expression after GR activation, and dexamethasone increased hepatocyte YY1 expression; these effects resulted in ACE2-MAS1 signaling pathway inhibition, which led to increased hepatic triglyceride synthesis and decreased oxidative function. The increased triglyceride synthesis and decreased oxidative function of hepatocytes caused by low miR-122 expression due to dexamethasone could continue postnatally, eventually leading to NAFLD in adult rat offspring.

miR-148a/LDLR mediates hypercholesterolemia induced by prenatal dexamethasone exposure in male offspring rats

Epidemiology suggests that adverse environmental exposure during pregnancy may predispose children to hypercholesterolemia in adulthood. This study aimed to demonstrate hypercholesterolemia induced by prenatal dexamethasone exposure (PDE) in adult male offspring rats and explore the intrauterine programming mechanisms. Pregnant Wistar rats were injected subcutaneously with dexamethasone (0, 0.1, 0.2, and 0.4 mg/kg∙d) from gestational days (GD) 9 to 21, and the serum and liver of the male offsprings were collected at GD21, postnatal week (PW) 12 and 28. Furthermore, the effects of dexamethasone on the expression of low-density lipoprotein receptor (LDLR) and its epigenetic mechanism was confirmed in the bone marrow mesenchymal stem cells (BMSCs) hepatoid differentiated cells and continuous hepatocyte line. PDE could reduce the birth weight of male offsprings, increase the serum total cholesterol (TCH) level in adult rats, and decrease the liver low-density lipoprotein receptor (LDLR) expression. Serum TCH level and liver LDLR expression were decreased in PDE male fetuses in utero (GD21). Moreover, PDE increased the translocation of the glucocorticoid receptor (GR) in the fetal liver, the expression of DiGeorge syndrome critical region 8 gene (DGCR8), the pre- and post-natal expression of miR-148a. The results of PDE offspring in vivo and in vitro exhibited similar changes. These changes could be reversed by overexpressing LDLR, inhibiting miR-148a or GR. PDE caused hypercholesterolemia in male adult offspring rats, which was mediated via dexamethasone activated intrauterine hepatic GR, enhanced the expression of DGCR8 and miR-148a, thereby reducing the expression of LDLR, leading to impaired liver cholesterol reverse transport function, and finally causing hypercholesterolemia in adult rats.

The role and mechanism of asymmetric dimethylarginine in fetal growth restriction via interference with endothelial function and angiogenesis

PURPOSE

Fetal growth restriction (FGR) is a high-risk pregnancy, and placental dysfunction is the main cause of FGR. The upregulation of asymmetric dimethylarginine (ADMA) is linked to FGR pathology, but the mechanism needs to be investigated.

METHODS

The levels of ADMA and other related molecules were measured in human biological samples. We further used human umbilical vein endothelial cells (HUVECs) to reveal the mechanism of ADMA-induced FGR in vitro.

RESULTS

Compared with the control group, FGR patients had higher placental resistance, and ADMA levels were increased in the maternal blood, cord blood, and placenta; additionally, nitric oxide (NO) production decreased, accompanied by a decreased expression of endogenous NO synthase (eNOS). The expression of vascular growth factor (VEGF) and placental growth factor (PLGF) in the maternal blood during the third trimester and umbilical cord of the FGR group was lower than the control group. The PLGF levels in the placentas of the FGR group were also reduced, while the expression of soluble fms-like tyrosine kinase-1 (sFlt-1) increased. In in vitro cell experiments, NO production was obviously lower when the cells were exposed to 100 μM of ADMA, with no difference in eNOS expression. There was a dose-dependent decrease in PLGF expression with increasing doses of ADMA, and the levels of sFlt-1 increased. Moreover, we confirmed that tube formation in HUVECs was lower after ADMA treatment compared with the control group.

CONCLUSION

The accumulation of ADMA during pregnancy has an adverse effect on fetal development via interference with placental endothelial function and angiogenesis.

Glucocorticoid programming mechanism for hypercholesterolemia in prenatal ethanol-exposed adult offspring rats

Our previous studies showed that prenatal ethanol exposure (PEE) elevated blood total cholesterol (TCH) level in adult offspring rats. This study was aimed at elucidating the intrauterine programming mechanism of hypercholesterolemia in adult rats induced by PEE. Pregnant Wistar rats were intragastrically administered ethanol (4 mg/kg∙d) from gestational day (GD) 9 to 20. The offspring rats were euthanized at GD20 and postnatal week 24. Results showed that PEE decreased serum TCH and HDL-C levels (female and male) as well as LDL-C level (female only) in fetal rats but increased serum TCH level and the TCH/HDL-C and LDL-C/HDL-C ratios in adult rats. Furthermore, PEE elevated serum corticosterone levels but inhibited hepatic insulin-like growth factor 1 (IGF1) signaling pathway, cholesterol synthesis and output in fetal rats. The conversed changes were observed in adult rats. Moreover, histone acetylation (H3K9ac and H3K14ac) and expression of hepatic reverse cholesterol transport (RCT) related genes, scavenger receptor BI and low-density lipoprotein receptor were decreased before and after birth by PEE. In HepG2 cells, cortisol negatively regulated the IGF1 signaling pathway and cholesterol metabolic genes, but this inhibition of the cholesterol metabolic genes could be reversed by glucocorticoid receptor antagonist RU486, whereas exogenous IGF1 treatment only reversed the downregulation of RCT genes by cortisol. We confirmed a "two programming" mechanism for PEE-induced hypercholesterolemia in adult rats. The "first programming" was a glucocorticoid (GC)-induced persistent reduction of RCT genes by epigenetic modifications, and the "second programming" was the negative regulation of cholesterol synthesis and output by the GC-IGF1 axis.

Retinal vascular function in asymptomatic individuals with a positive family history of cardiovascular disease

PURPOSE

To compare retinal microvascular function in healthy individuals with and without a positive family history (FH) of cardiovascular disease (CVD).

METHODS

Retinal vessel reactivity was assessed by means of dynamic retinal vessel analysis in 38 healthy subjects aged between 30 and 66 years with a positive FH of CVD and 37 age- and gender-matched control subjects. Other assessments included blood pressure (BP) profiles, blood glucose and lipid metabolism markers, Framingham risk scores (FRS), carotid intima-media thickness (c-IMT) and brachial flow-mediated dilation (FMD).

RESULTS

Family history-positive subjects showed decreased retinal arterial baseline diameter fluctuation, dilation amplitude, percent dilation, and overall constriction response slope (p = 0.001; p = 0.015; p = 0.001; and p < 0.001, respectively) and increased percent constriction (p = 0.008). On the venous side, baseline-corrected flicker response and dilation response slope were decreased in the FH-positive group (p = 0.009 and p = 0.010, respectively). There were no significant differences between groups in c-IMT scores or FMD parameters (all p > 0.05). The arterial MC% correlated negatively with decreased high-density lipoprotein cholesterol (r = -0.52, p = 0.002) in only FH-positive group.

CONCLUSION

Although macrovascular function is preserved in individuals with FH positive for CVD but with low FRS, there are, however, functional impairments at the retinal microvascular level that correlate with established plasma markers for cardiovascular risk.

Markers of Atherosclerosis: Part 2 - Genetic and Imaging Markers

This is Part 2 of a two-part review summarising current knowledge on biomarkers of atherosclerosis. Part 1 addressed serological biomarkers. Here, in part 2 we address genetic and imaging markers, and other developments in predicting risk. Further improvements in risk stratification are expected with the addition of genetic risk scores. In addition to single nucleotide polymorphisms (SNPs), recent advances in epigenetics offer DNA methylation profiles, histone chemical modifications, and micro-RNAs as other promising indicators of atherosclerosis. Imaging biomarkers are better studied and already have a higher degree of clinical applicability in cardiovascular (CV) event prediction and detection of preclinical atherosclerosis. With new methodologies, such as proteomics and metabolomics, discoveries of new clinically applicable biomarkers are expected.

The combined association of adherence to Mediterranean diet, muscular and cardiorespiratory fitness on low-grade inflammation in adolescents: a pooled analysis

PURPOSE

Low-grade inflammation leads to several metabolic disorders, and adherence to a Mediterranean diet (MedDiet), cardiorespiratory fitness (CRF), and muscular fitness (MF) has been considered important markers of metabolic healthy in youth. We investigated the combined association of adherence to Mediterranean diet, and muscular and cardiorespiratory fitness on high-sensitivity C-reactive protein (hs-CRP) in adolescents.

METHODS

This is a cross-sectional analysis with 1462 adolescents (625 girls) aged 9-18 years from Colombia and Portugal. MedDiet was assessed by Kidmed questionnaire. Shuttle run test was used to assess CRF. MF was assessed by the standing long-jump and handgrip tests. High-sensitivity assays were used to obtain the hs-CRP level.

RESULTS

Logistic regression shows that subjects with a low adherence to MedDiet and LowMF/LowCRF had a similar odds (OR = 2.3; 95% CI 1.2-4.0) as those with an optimal adherence to MedDiet and LowMF/LowCRF (OR = 2.3; 95% CI 1.2-5.0) of expressing high inflammatory profile when compared to those with an optimal adherence to MedDiet and HighMF/HighCRF. In addition, ANCOVA showed that subjects classified as high adherence to MedDiet and HighMF/HighCRF had, on average, the lowest levels of hs-CRP (F_(7,1454) = 2.051 p = 0.04).

CONCLUSION

The combination of optimal levels of CRF and MF and adherence to MedDiet is associated with lower hs-CRP. However, high MF and CRF seems to counteract the deleterious effect of having a low adherence to the MedDiet on hs-CRP levels.

Two intrauterine programming mechanisms of adult hypercholesterolemia induced by prenatal nicotine exposure in male offspring rats

Epidemiologic studies showed that low birth weight is associated with high cholesterol and an increased risk of cardiovascular diseases in adulthood. This study aimed to elucidate the intrauterine programming mechanisms of adult hypercholesterolemia. The results showed that prenatal nicotine exposure (PNE) caused intrauterine growth retardation and hypercholesterolemia in male adult offspring rats. Hepatic cholesterol synthesis and output were deceased in utero but increased in adults; hepatic reverse cholesterol transport (RCT) persistently deceased before and after birth. Meanwhile, PNE elevated serum corticosterone level and decreased hepatic IGF1 pathway activity in male fetuses, whereas converse changes were observed in male adults. The chronic stress model and cortisol-treated HepG2 cells verified that excessive glucocorticoid (GC)-induced GC-IGF1 axis programming enhanced hepatic cholesterol synthesis and output. In addition, PNE decreased the expression of specific protein 1 and P300 enrichment and H3K27 acetylation at the promoter region of genes responsible for RCT both in fetal and adult, male livers and reduced expression of those genes, similar alterations were also confirmed in cortisol-treated HepG2 cells, suggesting that excessive GC-related programming induced continuous RCT reduction by epigenetic modification. Taken together, the "2-programming" approach discussed above may ultimately contribute to the development of hypercholesterolemia in male adult offspring.-Zhou, J., Zhu, C., Luo, H., Shen, L., Gong, J., Wu, Y., Magdalou, J., Chen, L., Guo, Y., Wang, H. Two intrauterine programming mechanisms of adult hypercholesterolemia induced by prenatal nicotine exposure in male offspring rats.

Evaluation of epigenetic alterations (mir-126 and mir-155 expression levels) in Mexican children exposed to inorganic arsenic via drinking water

Recently, a great number of epidemiological studies have shown evidence that exposure to inorganic arsenic could have harmful effects on the cardiovascular system of humans. However, the underlying mechanisms through which arsenic induces cardiovascular toxic effects remain unclear. In this regard, epigenetic mechanisms have emerged as a probable connection between environment and disease phenotypes, including cardiovascular diseases. Therefore, this study aimed to evaluate epigenetic changes related to cardiotoxicity (miR-126 and miR-155 expression levels) in children from San Luis Potosi, Mexico exposed to inorganic arsenic. From 2014 to 2015, in a cross-sectional study, children (aged 6-12 years; n = 73) attending public schools at the studied sites were enrolled to take part in this study. Urinary arsenic was used as an exposure biomarker and analyzed by an atomic absorption spectrophotometry technique. On the other hand, miR-126 and miR-155 expression levels were evaluated by qRT-PCR. A mean urinary arsenic level of 30.5 ± 25.5 μg/g of creatinine was found. Moreover, the data showed a significant negative association (p < 0.05) between urinary arsenic concentrations and plasma miR-126 levels. However, an association between urinary arsenic concentrations and plasma miR-155 levels was not found (p > 0.05). In this regard, some investigations have shown an association between diminished plasma miR-126 levels and cardiovascular illnesses. The results found in this study are of concern. However, more similar studies including a larger sample size are necessary in order to clarify the real significance of the data.