Associations of carotid intima media thickness with gene expression in whole blood and genetically predicted gene expression across 48 tissues

Carotid intima media thickness (cIMT) is a biomarker of subclinical atherosclerosis and a predictor of future cardiovascular events. Identifying associations between gene expression levels and cIMT may provide insight to atherosclerosis etiology. Here, we use two approaches to identify associations between mRNA levels and cIMT: differential gene expression analysis in whole blood and S-PrediXcan. We used microarrays to measure genome-wide whole blood mRNA levels of 5647 European individuals from four studies. We examined the association of mRNA levels with cIMT adjusted for various potential confounders. Significant associations were tested for replication in three studies totaling 3943 participants. Next, we applied S-PrediXcan to summary statistics from a cIMT genome-wide association study (GWAS) of 71 128 individuals to estimate the association between genetically determined mRNA levels and cIMT and replicated these analyses using S-PrediXcan on an independent GWAS on cIMT that included 22 179 individuals from the UK Biobank. mRNA levels of TNFAIP3, CEBPD and METRNL were inversely associated with cIMT, but these associations were not significant in the replication analysis. S-PrediXcan identified associations between cIMT and genetically determined mRNA levels for 36 genes, of which six were significant in the replication analysis, including TLN2, which had not been previously reported for cIMT. There was weak correlation between our results using differential gene expression analysis and S-PrediXcan. Differential expression analysis and S-PrediXcan represent complementary approaches for the discovery of associations between phenotypes and gene expression. Using these approaches, we prioritize TNFAIP3, CEBPD, METRNL and TLN2 as new candidate genes whose differential expression might modulate cIMT.

An integrative cross-omics analysis of DNA methylation sites of glucose and insulin homeostasis

Despite existing reports on differential DNA methylation in type 2 diabetes (T2D) and obesity, our understanding of its functional relevance remains limited. Here we show the effect of differential methylation in the early phases of T2D pathology by a blood-based epigenome-wide association study of 4808 non-diabetic Europeans in the discovery phase and 11,750 individuals in the replication. We identify CpGs in LETM1, RBM20, IRS2, MAN2A2 and the 1q25.3 region associated with fasting insulin, and in FCRL6, SLAMF1, APOBEC3H and the 15q26.1 region with fasting glucose. In silico cross-omics analyses highlight the role of differential methylation in the crosstalk between the adaptive immune system and glucose homeostasis. The differential methylation explains at least 16.9% of the association between obesity and insulin. Our study sheds light on the biological interactions between genetic variants driving differential methylation and gene expression in the early pathogenesis of T2D.

The effects of golimumab treatment on systolic and diastolic left ventricular function in ankylosing spondylitis

Background

Diastolic left ventricular (LV) dysfunction appears more prevalent in ankylosing spondylitis (AS). The effects of tumor necrosis factor alpha (TNF-α) blocking therapy, a strong and effective anti-inflammatory drug, on diastolic LV function in AS are unknown. The objective of the study was to find the effects of 1-year treatment with golimumab 50 mg subcutaneously once per month on systolic and diastolic LV dysfunction in AS patients.

Methods

Forty consecutive AS patients were treated with TNF-α blocking therapy for 1 year. Transthoracic echocardiography was performed in all patients at baseline and after 1 year of treatment.

Results

Diastolic LV function improved after treatment in four out of six (67%) AS patients who completed follow-up (P=0.125), and did not develop or worsen in any of the other patients. Treatment with TNF-α blocking therapy had no effect on systolic LV function.

Conclusion

These findings give support to the hypothesis that diastolic LV dysfunction improves during treatment with TNF-α blocking therapy.

A whole-blood transcriptome meta-analysis identifies gene expression signatures of cigarette smoking

Cigarette smoking is a leading modifiable cause of death worldwide. We hypothesized that cigarette smoking induces extensive transcriptomic changes that lead to target-organ damage and smoking-related diseases. We performed a meta-analysis of transcriptome-wide gene expression using whole blood-derived RNA from 10,233 participants of European ancestry in six cohorts (including 1421 current and 3955 former smokers) to identify associations between smoking and altered gene expression levels. At a false discovery rate (FDR) <0.1, we identified 1270 differentially expressed genes in current vs. never smokers, and 39 genes in former vs. never smokers. Expression levels of 12 genes remained elevated up to 30 years after smoking cessation, suggesting that the molecular consequence of smoking may persist for decades. Gene ontology analysis revealed enrichment of smoking-related genes for activation of platelets and lymphocytes, immune response, and apoptosis. Many of the top smoking-related differentially expressed genes, including LRRN3 and GPR15, have DNA methylation loci in promoter regions that were recently reported to be hypomethylated among smokers. By linking differential gene expression with smoking-related disease phenotypes, we demonstrated that stroke and pulmonary function show enrichment for smoking-related gene expression signatures. Mediation analysis revealed the expression of several genes (e.g. ALAS2) to be putative mediators of the associations between smoking and inflammatory biomarkers (IL6 and C-reactive protein levels). Our transcriptomic study provides potential insights into the effects of cigarette smoking on gene expression in whole blood and their relations to smoking-related diseases. The results of such analyses may highlight attractive targets for treating or preventing smoking-related health effects.

Caenorhabditis elegans orthologs of human genes differentially expressed with age are enriched for determinants of longevity

We report a systematic RNAi longevity screen of 82 Caenorhabditis elegans genes selected based on orthology to human genes differentially expressed with age. We find substantial enrichment in genes for which knockdown increased lifespan. This enrichment is markedly higher than published genomewide longevity screens in C. elegans and similar to screens that preselected candidates based on longevity‐correlated metrics (e.g., stress resistance). Of the 50 genes that affected lifespan, 46 were previously unreported. The five genes with the greatest impact on lifespan (>20% extension) encode the enzyme kynureninase (kynu‐1), a neuronal leucine‐rich repeat protein (iglr‐1), a tetraspanin (tsp‐3), a regulator of calcineurin (rcan‐1), and a voltage‐gated calcium channel subunit (unc‐36). Knockdown of each gene extended healthspan without impairing reproduction. kynu‐1(RNAi) alone delayed pathology in C. elegans models of Alzheimer's disease and Huntington's disease. Each gene displayed a distinct pattern of interaction with known aging pathways. In the context of published work, kynu‐1, tsp‐3, and rcan‐1 are of particular interest for immediate follow‐up. kynu‐1 is an understudied member of the kynurenine metabolic pathway with a mechanistically distinct impact on lifespan. Our data suggest that tsp‐3 is a novel modulator of hypoxic signaling and rcan‐1 is a context‐specific calcineurin regulator. Our results validate C. elegans as a comparative tool for prioritizing human candidate aging genes, confirm age‐associated gene expression data as valuable source of novel longevity determinants, and prioritize select genes for mechanistic follow‐up.

DNA methylation signatures of chronic low-grade inflammation are associated with complex diseases

BACKGROUND

Chronic low-grade inflammation reflects a subclinical immune response implicated in the pathogenesis of complex diseases. Identifying genetic loci where DNA methylation is associated with chronic low-grade inflammation may reveal novel pathways or therapeutic targets for inflammation.

RESULTS

We performed a meta-analysis of epigenome-wide association studies (EWAS) of serum C-reactive protein (CRP), which is a sensitive marker of low-grade inflammation, in a large European population (n = 8863) and trans-ethnic replication in African Americans (n = 4111). We found differential methylation at 218 CpG sites to be associated with CRP (P < 1.15 × 10^-7) in the discovery panel of European ancestry and replicated (P < 2.29 × 10^-4) 58 CpG sites (45 unique loci) among African Americans. To further characterize the molecular and clinical relevance of the findings, we examined the association with gene expression, genetic sequence variants, and clinical outcomes. DNA methylation at nine (16%) CpG sites was associated with whole blood gene expression in cis (P < 8.47 × 10^-5), ten (17%) CpG sites were associated with a nearby genetic variant (P < 2.50 × 10^-3), and 51 (88%) were also associated with at least one related cardiometabolic entity (P < 9.58 × 10^-5). An additive weighted score of replicated CpG sites accounted for up to 6% inter-individual variation (R2) of age-adjusted and sex-adjusted CRP, independent of known CRP-related genetic variants.

CONCLUSION

We have completed an EWAS of chronic low-grade inflammation and identified many novel genetic loci underlying inflammation that may serve as targets for the development of novel therapeutic interventions for inflammation.

Peripheral Blood Transcriptomic Signatures of Fasting Glucose and Insulin Concentrations

Genome-wide association studies (GWAS) have successfully identified genetic loci associated with glycemic traits. However, characterizing the functional significance of these loci has proven challenging. We sought to gain insights into the regulation of fasting insulin and fasting glucose through the use of gene expression microarray data from peripheral blood samples of participants without diabetes in the Framingham Heart Study (FHS) (n = 5,056), the Rotterdam Study (RS) (n = 723), and the InCHIANTI Study (Invecchiare in Chianti) (n = 595). Using a false discovery rate q <0.05, we identified three transcripts associated with fasting glucose and 433 transcripts associated with fasting insulin levels after adjusting for age, sex, technical covariates, and complete blood cell counts. Among the findings, circulating IGF2BP2 transcript levels were positively associated with fasting insulin in both the FHS and RS. Using 1000 Genomes-imputed genotype data, we identified 47,587 cis-expression quantitative trait loci (eQTL) and 6,695 trans-eQTL associated with the 433 significant insulin-associated transcripts. Of note, we identified a trans-eQTL (rs592423), where the A allele was associated with higher IGF2BP2 levels and with fasting insulin in an independent genetic meta-analysis comprised of 50,823 individuals. We conclude that integration of genomic and transcriptomic data implicate circulating IGF2BP2 mRNA levels associated with glucose and insulin homeostasis.

Tobacco smoking is associated with DNA methylation of diabetes susceptibility genes

AIMS/HYPOTHESIS

Tobacco smoking, a risk factor for diabetes, is an established modifier of DNA methylation. We hypothesised that tobacco smoking modifies DNA methylation of genes previously identified for diabetes.

METHODS

We annotated CpG sites available on the Illumina Human Methylation 450K array to diabetes genes previously identified by genome-wide association studies (GWAS), and investigated them for an association with smoking by comparing current to never smokers. The discovery study consisted of 630 individuals (Bonferroni-corrected p = 1.4 × 10(-5)), and we sought replication in an independent sample of 674 individuals. The replicated sites were tested for association with nearby genetic variants and gene expression and fasting glucose and insulin levels.

RESULTS

We annotated 3,620 CpG sites to the genes identified in the GWAS on type 2 diabetes. Comparing current smokers to never smokers, we found 12 differentially methylated CpG sites, of which five replicated: cg23161492 within ANPEP (p = 1.3 × 10(-12)); cg26963277 (p = 1.2 × 10(-9)), cg01744331 (p = 8.0 × 10(-6)) and cg16556677 (p = 1.2 × 10(-5)) within KCNQ1 and cg03450842 (p = 3.1 × 10(-8)) within ZMIZ1. The effect of smoking on DNA methylation at the replicated CpG sites attenuated after smoking cessation. Increased DNA methylation at cg23161492 was associated with decreased gene expression levels of ANPEP (p = 8.9 × 10(-5)). rs231356-T, which was associated with hypomethylation of cg26963277 (KCNQ1), was associated with a higher odds of diabetes (OR 1.06, p = 1.3 × 10(-5)). Additionally, hypomethylation of cg26963277 was associated with lower fasting insulin levels (p = 0.04).

CONCLUSIONS/INTERPRETATION

Tobacco smoking is associated with differential DNA methylation of the diabetes risk genes ANPEP, KCNQ1 and ZMIZ1. Our study highlights potential biological mechanisms connecting tobacco smoking to excess risk of type 2 diabetes.

DNA Methylation in Newborns and Maternal Smoking in Pregnancy: Genome-wide Consortium Meta-analysis

Epigenetic modifications, including DNA methylation, represent a potential mechanism for environmental impacts on human disease. Maternal smoking in pregnancy remains an important public health problem that impacts child health in a myriad of ways and has potential lifelong consequences. The mechanisms are largely unknown, but epigenetics most likely plays a role. We formed the Pregnancy And Childhood Epigenetics (PACE) consortium and meta-analyzed, across 13 cohorts (n = 6,685), the association between maternal smoking in pregnancy and newborn blood DNA methylation at over 450,000 CpG sites (CpGs) by using the Illumina 450K BeadChip. Over 6,000 CpGs were differentially methylated in relation to maternal smoking at genome-wide statistical significance (false discovery rate, 5%), including 2,965 CpGs corresponding to 2,017 genes not previously related to smoking and methylation in either newborns or adults. Several genes are relevant to diseases that can be caused by maternal smoking (e.g., orofacial clefts and asthma) or adult smoking (e.g., certain cancers). A number of differentially methylated CpGs were associated with gene expression. We observed enrichment in pathways and processes critical to development. In older children (5 cohorts, n = 3,187), 100% of CpGs gave at least nominal levels of significance, far more than expected by chance (p value < 2.2 × 10(-16)). Results were robust to different normalization methods used across studies and cell type adjustment. In this large scale meta-analysis of methylation data, we identified numerous loci involved in response to maternal smoking in pregnancy with persistence into later childhood and provide insights into mechanisms underlying effects of this important exposure.

Maternal plasma folate impacts differential DNA methylation in an epigenome-wide meta-analysis of newborns

Folate is vital for fetal development. Periconceptional folic acid supplementation and food fortification are recommended to prevent neural tube defects. Mechanisms whereby periconceptional folate influences normal development and disease are poorly understood: epigenetics may be involved. We examine the association between maternal plasma folate during pregnancy and epigenome-wide DNA methylation using Illumina's HumanMethyl450 Beadchip in 1,988 newborns from two European cohorts. Here we report the combined covariate-adjusted results using meta-analysis and employ pathway and gene expression analyses. Four-hundred forty-three CpGs (320 genes) are significantly associated with maternal plasma folate levels during pregnancy (false discovery rate 5%); 48 are significant after Bonferroni correction. Most genes are not known for folate biology, including APC2, GRM8, SLC16A12, OPCML, PRPH, LHX1, KLK4 and PRSS21. Some relate to birth defects other than neural tube defects, neurological functions or varied aspects of embryonic development. These findings may inform how maternal folate impacts the developing epigenome and health outcomes in offspring.

Associations between joint effusion in the knee and gene expression levels in the circulation: a meta-analysis

Objective: To identify molecular biomarkers for early knee osteoarthritis (OA), we examined whether joint effusion in the knee associated with different gene expression levels in the circulation.

Materials and Methods: Joint effusion grades measured with magnetic resonance (MR) imaging and gene expression levels in blood were determined in women of the Rotterdam Study (N=135) and GARP (N=98). Associations were examined using linear regression analyses, adjusted for age, fasting status, RNA quality, technical batch effects, blood cell counts, and BMI. To investigate enriched pathways and protein-protein interactions, we used the DAVID and STRING webtools.

Results: In a meta-analysis, we identified 257 probes mapping to 189 unique genes in blood that were nominally significantly associated with joint effusion grades in the knee. Several compelling genes were identified such as C1orf38 and NFATC1. Significantly enriched biological pathways were: response to stress, gene expression, negative regulation of intracellular signal transduction, and antigen processing and presentation of exogenous pathways.

Conclusion: Meta-analyses and subsequent enriched biological pathways resulted in interesting candidate genes associated with joint effusion that require further characterization. Associations were not transcriptome-wide significant most likely due to limited power. Additional studies are required to replicate our findings in more samples, which will greatly help in understanding the pathophysiology of OA and its relation to inflammation, and may result in biomarkers urgently needed to diagnose OA at an early stage.

The transcriptional landscape of age in human peripheral blood

Disease incidences increase with age, but the molecular characteristics of ageing that lead to increased disease susceptibility remain inadequately understood. Here we perform a whole-blood gene expression meta-analysis in 14,983 individuals of European ancestry (including replication) and identify 1,497 genes that are differentially expressed with chronological age. The age-associated genes do not harbor more age-associated CpG-methylation sites than other genes, but are instead enriched for the presence of potentially functional CpG-methylation sites in enhancer and insulator regions that associate with both chronological age and gene expression levels. We further used the gene expression profiles to calculate the ‘transcriptomic age' of an individual, and show that differences between transcriptomic age and chronological age are associated with biological features linked to ageing, such as blood pressure, cholesterol levels, fasting glucose, and body mass index. The transcriptomic prediction model adds biological relevance and complements existing epigenetic prediction models, and can be used by others to calculate transcriptomic age in external cohorts.

Ageing increases the risk of many diseases. Here the authors compare blood cell transcriptomes of over 14,000 individuals and identify a set of about 1,500 genes that are differently expressed with age, shedding light on transcriptional programs linked to the ageing process and age-associated diseases.

A genetic variant in the seed region of miR-4513 shows pleiotropic effects on lipid and glucose homeostasis, blood pressure, and coronary artery disease

MicroRNAs (miRNA) play a crucial role in the regulation of diverse biological processes by post-transcriptional modulation of gene expression. Genetic polymorphisms in miRNA-related genes can potentially contribute to a wide range of phenotypes. The effect of such variants on cardiometabolic diseases has not yet been defined. We systematically investigated the association of genetic variants in the seed region of miRNAs with cardiometabolic phenotypes, using the thus far largest genome-wide association studies on 17 cardiometabolic traits/diseases. We found that rs2168518:G>A, a seed region variant of miR-4513, associates with fasting glucose, low-density lipoprotein-cholesterol, total cholesterol, systolic and diastolic blood pressure, and risk of coronary artery disease. We experimentally showed that miR-4513 expression is significantly reduced in the presence of the rs2168518 mutant allele. We sought to identify miR-4513 target genes that may mediate these associations and revealed five genes (PCSK1, BNC2, MTMR3, ANK3, and GOSR2) through which these effects might be taking place. Using luciferase reporter assays, we validated GOSR2 as a target of miR-4513 and further demonstrated that the miRNA-mediated regulation of this gene is changed by rs2168518. Our findings indicate a pleiotropic effect of miR-4513 on cardiometabolic phenotypes and may improve our understanding of the pathophysiology of cardiometabolic diseases.

Tobacco smoking is associated with methylation of genes related to coronary artery disease

Background

Tobacco smoking, a risk factor for coronary artery disease (CAD), is known to modify DNA methylation. We hypothesized that tobacco smoking modifies methylation of the genes identified for CAD by genome-wide association study (GWAS).

Results

We selected genomic regions based on 150 single-nucleotide polymorphisms (SNPs) identified in the largest GWAS on CAD. We investigated the association between current smoking and the CpG sites within and near these CAD-related genes. Methylation was measured with the Illumina Human Methylation 450K array in whole blood of 724 Caucasian subjects from the Rotterdam Study, a Dutch population based cohort study.

A total of 3669 CpG sites within 169 CAD-related genes were studied for association with current compared to never smoking. Fifteen CpG sites were significantly associated after correction for multiple testing (Bonferroni-corrected p value <1.4 × 10⁻⁵). These sites were located in the genes TERT, SARS, GNGT2, SMG6, SKI, TOM1L2, SIPA1, MRAS, CDKN1A, LRRC2, FES and RPH3A. In 12 sites, current smoking was associated with a 1.2 to 2.4 % lower methylation compared to never smoking; and in three sites, it was associated with a 1.2 to 1.8 % higher methylation. The effect estimates were lower in 10 of the 15 CpG sites when comparing current to former smoking. One CpG site, cg05603985 (SKI), was found to be associated with expression of nearby CAD-related gene PRKCZ.

Conclusions

Our study suggests an effect of tobacco smoking on DNA methylation of CAD-related genes and thus provides novel insights in the pathways that link tobacco smoking to risk of CAD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0088-y) contains supplementary material, which is available to authorized users.

Full blood count parameters for the detection of asthma inflammatory phenotypes

BACKGROUND

In asthma, the airway inflammatory phenotype influences clinical characteristics and treatment response. Although induced sputum is the gold standard test for phenotyping asthma, a more accessible method is needed for clinical practice.

OBJECTIVE

To investigate whether white blood cell counts and/or their derived ratios can predict sputum eosinophils or neutrophils in uncontrolled asthma.

METHODS

This cross-sectional study evaluated 164 treated but uncontrolled asthmatic patients with sputum induction and blood collection. Receiver-operating characteristic (ROC) curves were used to assess the relationship between blood and sputum parameters.

RESULTS

There was a significant positive relationship between blood eosinophil parameters and the percentage of sputum eosinophil count. A weak but significant correlation was found between sputum neutrophil percentage and blood neutrophil percentage (r = 0.219, P = 0.005). ROC curve analysis identified that blood eosinophil percentage count was the best predictor for eosinophilic asthma, with an area under the curve (AUC) of 0.907 (P < 0.001). The optimum cut-point for blood eosinophil percentage was 2.7%, and this yielded a sensitivity of 92.2% and a specificity of 75.8%. The absolute blood eosinophil count was also highly predictive with an AUC of 0.898 (P < 0.0001) at a blood eosinophil cut-off of 0.26 × 10(9) /L. The blood eosinophil/lymphocyte ratio (ELR) and eosinophil/neutrophil ratio (ENR) were increased in eosinophilic asthma, and the neutrophil/lymphocyte ratio (NLR) was increased in neutrophilic asthma. Neutrophilic asthma could also be detected by blood neutrophil percentages and NLR, but with less accuracy.

CONCLUSIONS AND CLINICAL RELEVANCE

Blood eosinophil counts and derived ratios (ELR and ENR) can accurately predict eosinophilic asthma in patients with persistent uncontrolled asthma despite treatment. Blood neutrophil parameters are poor surrogates for the proportion of sputum neutrophils. Blood counts may be a useful aid in the monitoring of uncontrolled asthma.

A meta-analysis of gene expression signatures of blood pressure and hypertension

Genome-wide association studies (GWAS) have uncovered numerous genetic variants (SNPs) that are associated with blood pressure (BP). Genetic variants may lead to BP changes by acting on intermediate molecular phenotypes such as coded protein sequence or gene expression, which in turn affect BP variability. Therefore, characterizing genes whose expression is associated with BP may reveal cellular processes involved in BP regulation and uncover how transcripts mediate genetic and environmental effects on BP variability. A meta-analysis of results from six studies of global gene expression profiles of BP and hypertension in whole blood was performed in 7017 individuals who were not receiving antihypertensive drug treatment. We identified 34 genes that were differentially expressed in relation to BP (Bonferroni-corrected p<0.05). Among these genes, FOS and PTGS2 have been previously reported to be involved in BP-related processes; the others are novel. The top BP signature genes in aggregate explain 5%–9% of inter-individual variance in BP. Of note, rs3184504 in SH2B3, which was also reported in GWAS to be associated with BP, was found to be a trans regulator of the expression of 6 of the transcripts we found to be associated with BP (FOS, MYADM, PP1R15A, TAGAP, S100A10, and FGBP2). Gene set enrichment analysis suggested that the BP-related global gene expression changes include genes involved in inflammatory response and apoptosis pathways. Our study provides new insights into molecular mechanisms underlying BP regulation, and suggests novel transcriptomic markers for the treatment and prevention of hypertension.

The focus of blood pressure (BP) GWAS has been the identification of common DNA sequence variants associated with the phenotype; this approach provides only one dimension of molecular information about BP. While it is a critical dimension, analyzing DNA variation alone is not sufficient for achieving an understanding of the multidimensional complexity of BP physiology. The top loci identified by GWAS explain only about 1 percent of inter-individual BP variability. In this study, we performed a meta-analysis of gene expression profiles in relation to BP and hypertension in 7017 individuals from six studies. We identified 34 differentially expressed genes for BP, and discovered that the top BP signature genes explain 5%–9% of BP variability. We further linked BP gene expression signature genes with BP GWAS results by integrating expression associated SNPs (eSNPs) and discovered that one of the top BP loci from GWAS, rs3184504 in SH2B3, is a trans regulator of expression of 6 of the top 34 BP signature genes. Our study, in conjunction with prior GWAS, provides a deeper understanding of the molecular and genetic basis of BP regulation, and identifies several potential targets and pathways for the treatment and prevention of hypertension and its sequelae.

New genetic loci link adipose and insulin biology to body fat distribution

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, we conducted genome-wide association meta-analyses of waist and hip circumference-related traits in up to 224,459 individuals. We identified 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (WHRadjBMI) and an additional 19 loci newly associated with related waist and hip circumference measures (P<5×10⁻⁸). Twenty of the 49 WHRadjBMI loci showed significant sexual dimorphism, 19 of which displayed a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation, and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms.

Low-frequency and rare exome chip variants associate with fasting glucose and type 2 diabetes susceptibility

Fasting glucose and insulin are intermediate traits for type 2 diabetes. Here we explore the role of coding variation on these traits by analysis of variants on the HumanExome BeadChip in 60,564 non-diabetic individuals and in 16,491 T2D cases and 81,877 controls. We identify a novel association of a low-frequency nonsynonymous SNV in GLP1R (A316T; rs10305492; MAF=1.4%) with lower FG (β=-0.09±0.01 mmol l(-1), P=3.4 × 10(-12)), T2D risk (OR[95%CI]=0.86[0.76-0.96], P=0.010), early insulin secretion (β=-0.07±0.035 pmolinsulin mmolglucose(-1), P=0.048), but higher 2-h glucose (β=0.16±0.05 mmol l(-1), P=4.3 × 10(-4)). We identify a gene-based association with FG at G6PC2 (pSKAT=6.8 × 10(-6)) driven by four rare protein-coding SNVs (H177Y, Y207S, R283X and S324P). We identify rs651007 (MAF=20%) in the first intron of ABO at the putative promoter of an antisense lncRNA, associating with higher FG (β=0.02±0.004 mmol l(-1), P=1.3 × 10(-8)). Our approach identifies novel coding variant associations and extends the allelic spectrum of variation underlying diabetes-related quantitative traits and T2D susceptibility.

Finger length pattern as a biomarker for osteoarthritis and chronic joint pain: a population-based study and meta-analysis after systematic review

OBJECTIVE

Type 3 finger length pattern (longer fourth digit than second digit) is influenced by prenatal androgens and has been studied previously as a biomarker for sexually dimorphic traits. Because osteoarthritis (OA) and chronic pain are known to be sexually dimorphic traits, we evaluated the association between finger length pattern and OA and chronic joint pain.

METHODS

This study was part of the Rotterdam Study, a prospective population-based cohort study. We examined 4,784 participants. Associations between type 3 finger length and radiologic knee, hip, and hand OA and chronic joint pain were analyzed using a logistic regression model. Our results for OA were combined with previously published data in a meta-analysis.

RESULTS

Participants with type 3 finger length pattern had an odds ratio of 1.64 for hand OA (P = 1.06 × 10(-7)). No associations with radiologic knee or hip OA were observed in the Rotterdam Study. The meta-analysis of previously published data and our novel data showed a significant association between type 3 finger length pattern and clinical symptomatic knee OA, but no association was found with radiologic knee OA. In addition, within the Rotterdam Study, we observed an odds ratio of 1.41 for individuals having joint pain at multiple sites (P = 1.4 × 10(-3)).

CONCLUSION

Type 3 finger length pattern, as an indicator of prenatal androgen exposure, was associated with having symptomatic knee OA, chronic pain, and hand OA. Therefore, it may be applicable as an easy measurable biomarker to identify susceptible subjects for these traits.

A genome-wide copy number association study of osteoporotic fractures points to the 6p25.1 locus

BACKGROUND

Osteoporosis is a systemic skeletal disease characterised by reduced bone mineral density and increased susceptibility to fracture; these traits are highly heritable. Both common and rare copy number variants (CNVs) potentially affect the function of genes and may influence disease risk.

AIM

To identify CNVs associated with osteoporotic bone fracture risk.

METHOD

We performed a genome-wide CNV association study in 5178 individuals from a prospective cohort in the Netherlands, including 809 osteoporotic fracture cases, and performed in silico lookups and de novo genotyping to replicate in several independent studies.

RESULTS

A rare (population prevalence 0.14%, 95% CI 0.03% to 0.24%) 210 kb deletion located on chromosome 6p25.1 was associated with the risk of fracture (OR 32.58, 95% CI 3.95 to 1488.89; p = 8.69 × 10(-5)). We performed an in silico meta-analysis in four studies with CNV microarray data and the association with fracture risk was replicated (OR 3.11, 95% CI 1.01 to 8.22; p = 0.02). The prevalence of this deletion showed geographic diversity, being absent in additional samples from Australia, Canada, Poland, Iceland, Denmark, and Sweden, but present in the Netherlands (0.34%), Spain (0.33%), USA (0.23%), England (0.15%), Scotland (0.10%), and Ireland (0.06%), with insufficient evidence for association with fracture risk.

CONCLUSIONS

These results suggest that deletions in the 6p25.1 locus may predispose to higher risk of fracture in a subset of populations of European origin; larger and geographically restricted studies will be needed to confirm this regional association. This is a first step towards the evaluation of the role of rare CNVs in osteoporosis.

Identification of genetic loci associated with Helicobacter pylori serologic status

IMPORTANCE

Helicobacter pylori is a major cause of gastritis and gastroduodenal ulcer disease and can cause cancer. H. pylori prevalence is as high as 90% in some developing countries but 10% of a given population is never colonized, regardless of exposure. Genetic factors are hypothesized to confer H. pylori susceptibility.

OBJECTIVE

To identify genetic loci associated with H. pylori seroprevalence in 2 independent population-based cohorts and to determine their putative pathophysiological role by whole-blood RNA gene expression profiling.

DESIGN, SETTING, AND PARTICIPANTS

Two independent genome-wide association studies (GWASs) and a subsequent meta-analysis were conducted for anti-H. pylori IgG serology in the Study of Health in Pomerania (SHIP) (recruitment, 1997-2001 [n = 3830]) as well as the Rotterdam Study (RS-I) (recruitment, 1990-1993) and RS-II (recruitment, 2000-2001 [n = 7108]) populations. Whole-blood RNA gene expression profiles were analyzed in RS-III (recruitment, 2006-2008 [n = 762]) and SHIP-TREND (recruitment, 2008-2012 [n = 991]), and fecal H. pylori antigen in SHIP-TREND (n = 961).

MAIN OUTCOMES AND MEASURES

H. pylori seroprevalence.

RESULTS

Of 10,938 participants, 6160 (56.3%) were seropositive for H. pylori. GWASs identified the toll-like receptor (TLR) locus (4p14; top-ranked single-nucleotide polymorphism (SNP), rs10004195; P = 1.4 × 10(-18); odds ratio, 0.70 [95% CI, 0.65 to 0.76]) and the FCGR2A locus (1q23.3; top-ranked SNP, rs368433; P = 2.1 × 10(-8); odds ratio, 0.73 [95% CI, 0.65 to 0.81]) as associated with H. pylori seroprevalence. Among the 3 TLR genes at 4p14, only TLR1 was differentially expressed per copy number of the minor rs10004195-A allele (β = -0.23 [95% CI, -0.34 to -0.11]; P = 2.1 × 10(-4)). Individuals with high fecal H. pylori antigen titers (optical density >1) also exhibited the highest 25% of TLR1 expression levels (P = .01 by χ2 test). Furthermore, TLR1 exhibited an Asn248Ser substitution in the extracellular domain strongly linked to the rs10004195 SNP.

CONCLUSIONS AND RELEVANCE

GWAS meta-analysis identified an association between TLR1 and H. pylori seroprevalence, a finding that requires replication in nonwhite populations. If confirmed, genetic variations in TLR1 may help explain some of the observed variation in individual risk for H. pylori infection.

Genome-wide meta-analysis identifies 11 new loci for anthropometric traits and provides insights into genetic architecture

Approaches exploiting trait distribution extremes may be used to identify loci associated with common traits, but it is unknown whether these loci are generalizable to the broader population. In a genome-wide search for loci associated with the upper versus the lower 5th percentiles of body mass index, height and waist-to-hip ratio, as well as clinical classes of obesity, including up to 263,407 individuals of European ancestry, we identified 4 new loci (IGFBP4, H6PD, RSRC1 and PPP2R2A) influencing height detected in the distribution tails and 7 new loci (HNF4G, RPTOR, GNAT2, MRPS33P4, ADCY9, HS6ST3 and ZZZ3) for clinical classes of obesity. Further, we find a large overlap in genetic structure and the distribution of variants between traits based on extremes and the general population and little etiological heterogeneity between obesity subgroups.

Genome-wide association study meta-analysis of chronic widespread pain: evidence for involvement of the 5p15.2 region

BACKGROUND AND OBJECTIVES

Chronic widespread pain (CWP) is a common disorder affecting ∼10% of the general population and has an estimated heritability of 48-52%. In the first large-scale genome-wide association study (GWAS) meta-analysis, we aimed to identify common genetic variants associated with CWP.

METHODS

We conducted a GWAS meta-analysis in 1308 female CWP cases and 5791 controls of European descent, and replicated the effects of the genetic variants with suggestive evidence for association in 1480 CWP cases and 7989 controls. Subsequently, we studied gene expression levels of the nearest genes in two chronic inflammatory pain mouse models, and examined 92 genetic variants previously described associated with pain.

RESULTS

The minor C-allele of rs13361160 on chromosome 5p15.2, located upstream of chaperonin-containing-TCP1-complex-5 gene (CCT5) and downstream of FAM173B, was found to be associated with a 30% higher risk of CWP (minor allele frequency=43%; OR=1.30, 95% CI 1.19 to 1.42, p=1.2×10(-8)). Combined with the replication, we observed a slightly attenuated OR of 1.17 (95% CI 1.10 to 1.24, p=4.7×10(-7)) with moderate heterogeneity (I2=28.4%). However, in a sensitivity analysis that only allowed studies with joint-specific pain, the combined association was genome-wide significant (OR=1.23, 95% CI 1.14 to 1.32, p=3.4×10(-8), I2=0%). Expression levels of Cct5 and Fam173b in mice with inflammatory pain were higher in the lumbar spinal cord, not in the lumbar dorsal root ganglions, compared to mice without pain. None of the 92 genetic variants previously described were significantly associated with pain (p>7.7×10(-4)).

CONCLUSIONS

We identified a common genetic variant on chromosome 5p15.2 associated with joint-specific CWP in humans. This work suggests that CCT5 and FAM173B are promising targets in the regulation of pain.

Lung perfusion and chest wall configuration is altered by glossopharyngeal breathing

Glossopharyngeal insufflation is used by competitive breath-hold divers to increase lung gas content above baseline total lung capacity (TLC) in order improve performance. Whilst glossopharyngeal insufflation is known to induce hypotension and tachycardia, little is known about the effects on the pulmonary circulation and structural integrity of the thorax. Six male breath-hold divers were studied. Exhaled lung volumes were measured before and after glossopharyngeal insufflation. On two study days, subjects were studied in the supine position at baseline TLC and after maximal glossopharyngeal insufflation above TLC. Tc 99(m) labelled macro-aggregated albumin was injected and a computed tomography (CT) scan of the thorax was performed during breath-hold. Single photon emission CT images determined flow and regional deposition. Registered CT images determined change in the volume of the thorax. CT and perfusion comparisons were possible in four subjects. Lung perfusion was markedly diminished in areas of expanded lung. 69% of the increase in expired lung volume was via thoracic expansion with a caudal displacement of the diaphragm. One subject who was not proficient at glossopharyngeal insufflation had no change in CT appearance or lung perfusion. We have demonstrated areas of hyperexpanded, under perfused lung created by glossopharyngeal insufflation above TLC.

Emergency management of children with severe sepsis in the United Kingdom: the results of the Paediatric Intensive Care Society sepsis audit

OBJECTIVE

To audit current UK practice of the management of severe sepsis in children against the 2002 American College of Critical Care Medicine/Pediatric Advanced Life Support (ACCM-PALS) guideline.

DESIGN

Prospective observational study.

SETTING

17 UK paediatric intensive care units (PICUs) and two UK PICU transport services.

PARTICIPANTS

200 children accepted for PICU admission within 12 h of arrival in hospital, whether or not successfully transported to a PICU, with a discharge diagnosis of sepsis or suspected sepsis.

MAIN OUTCOME MEASURES

Medical interventions, physiological and laboratory data to determine the presence or absence of shock, inter-hospital transfer times, predicted mortality (using the Paediatric Index of Mortality, version 2 (PIM2) scoring system) and observed mortality.

RESULTS

34/200 (17%) children died following referral. Although children defined as being in shock received significantly more fluid (p<0.001) than those who were not in shock, overall fluid and inotrope management suggested by the 2002 ACCM-PALS guideline was not followed in 62% of shocked children. Binary logistic regression analysis demonstrated that the odds ratio for death, if shock was present at PICU admission, was 3.8 (95% CI 1.4 to 10.2, p = 0.008).

CONCLUSIONS

The presence of shock at PICU admission is associated with an increased risk of death. Despite clear consensus guidelines for the emergency management of children with severe sepsis and septic shock, most children received inadequate fluid resuscitation and inotropic support in the crucial few hours following presentation.

Effect of budesonide/formoterol maintenance and reliever therapy on asthma exacerbations

This randomised, double-blind, 6-month study compared budesonide/formoterol for maintenance and relief with salmeterol/fluticasone and a fixed maintenance dose of budesonide/formoterol, both with terbutaline for relief. Following a 2-week run-in, 3335 symptomatic adults and adolescents (mean FEV1 73% predicted, mean inhaled corticosteroid dose 745 microg/day) received budesonide/formoterol 160/4.5 microg one inhalation bid plus additional inhalations as needed, salmeterol/fluticasone 25/125 microg two inhalations bid plus as-needed terbutaline or budesonide/formoterol 320/9 microg one inhalation bid plus as-needed terbutaline. Budesonide/formoterol for maintenance and relief prolonged the time to first severe exacerbation requiring hospitalisation, emergency room treatment or oral steroids (primary variable) vs. fixed-dose salmeterol/fluticasone and budesonide/formoterol (p=0.0034 and p=0.023 respectively; log-rank test). Exacerbation rates were 19, 16 and 12 events/100 patients/6 months for salmeterol/fluticasone, fixed-dose budesonide/formoterol and budesonide/formoterol for maintenance and relief, respectively, [rate reduction vs. fixed-dose salmeterol/fluticasone (0.61; 95% CI 0.49-0.76, p<0.001) and vs. fixed-dose budesonide/formoterol (0.72; 95% CI 0.57-0.90, p=0.0048)]. Budesonide/formoterol maintenance and relief patients used less inhaled corticosteroid vs. salmeterol/fluticasone and fixed-dose budesonide/formoterol patients. All treatments provided similar marked improvements in lung function, asthma control days and asthma-related quality of life. Budesonide/formoterol for maintenance and relief reduces asthma exacerbations and maintains similar daily asthma control at a lower overall drug load compared with fixed-dose salmeterol/fluticasone and budesonide/formoterol.

Relapsing Splenic Vein Thrombosis Associated With Antiphospholipid Antibodies in a Patient With Wegener Granulomatosis

Relapsing splenic vein thrombosis, a very rare complication of Wegener granulomatosis (WG), is described in a female patient. Positive antiphospholipid antibodies found in this case are a rare occurrence in primary vasculitis, especially in WG. This probably caused or accentuated an effect of the WG on the splenic vein. Treatment of such patients with antiphospholipid syndrome and WG must include anticoagulation and immunosuppression and, as noted in this patient, the splenic vein thrombosis and other antiphospholipid syndrome and WG can resolve quickly.

Endotoxin immunity and the development of the systemic inflammatory response syndrome in critically ill children

BACKGROUND

The systemic inflammatory response syndrome (SIRS) may be triggered by endotoxin. Humans have antibodies directed against the core of endotoxin (endotoxin core antibodies, EndoCAb) that appear to be protective following surgery and in sepsis. We hypothesised that children with elevated antibodies to endotoxin core would be less likely to develop SIRS in their initial period on intensive care. Because of the existing literature we defined two sub-groups according to the primary reason for ICU admission: infection and non-infection.

METHODS

We recruited 139 consecutive patients admitted to a paediatric intensive care unit (PICU) with more than one organ failure for longer than 12 h as part of another study. Patients were classified on admission to PICU as having an infectious or a non-infections diagnosis. The occurrence of SIRS within 48 h of admission was recorded along with detailed clinical and demographic data, EndoCAb concentration and the potential confounding variables C-reactive protein and mannose-binding lectin.

RESULTS

In the 71 patients admitted without infection (primarily post-operative and head injured) IgG EndoCAb was significantly lower in patients who developed SIRS than those who did not (72 vs. 131 MU/ml), independent of potential confounding variables. In patients with infection there was no significant difference in IgG EndoCAb between children developing SIRS and those who did not (111 vs. 80 MU/ml).

CONCLUSION

Head injured and post-operative patients admitted to PICU who develop early SIRS have significantly lower serum IgG EndoCAb levels than those who do not.

Effect of simulated commercial flight on oxygenation in patients with interstitial lung disease and chronic obstructive pulmonary disease

BACKGROUND

Commercial aircraft cabins provide a hostile environment for patients with underlying respiratory disease. Although there are algorithms and guidelines for predicting in-flight hypoxaemia, these relate to chronic obstructive pulmonary disease (COPD) and data for interstitial lung disease (ILD) are lacking. The purpose of this study was to evaluate the effect of simulated cabin altitude on subjects with ILD at rest and during a limited walking task.

METHODS

Fifteen subjects with ILD and 10 subjects with COPD were recruited. All subjects had resting arterial oxygen pressure (PaO2) of >9.3 kPa. Subjects breathed a hypoxic gas mixture containing 15% oxygen with balance nitrogen for 20 minutes at rest followed by a 50 metre walking task. Pulse oximetry (SpO2) was monitored continuously with testing terminated if levels fell below 80%. Arterial blood gas tensions were taken on room air at rest and after the resting and exercise phases of breathing the gas mixture.

RESULTS

In both groups there was a statistically significant decrease in arterial oxygen saturation (SaO2) and PaO2 from room air to 15% oxygen at rest and from 15% oxygen at rest to the completion of the walking task. The ILD group differed significantly from the COPD group in resting 15% oxygen SaO2, PaO2, and room air pH. Means for both groups fell below recommended levels at both resting and when walking on 15% oxygen.

CONCLUSION

Even in the presence of acceptable arterial blood gas tensions at sea level, subjects with both ILD and COPD fall below recommended levels of oxygenation when cabin altitude is simulated. This is exacerbated by minimal exercise. Resting sea level arterial blood gas tensions are similarly poor in both COPD and ILD for predicting the response to simulated cabin altitude.

Inappropriate emergency management of status epilepticus in children contributes to need for intensive care

OBJECTIVES

To characterise the clinical features, emergency pre-paediatric intensive care (PIC) treatment, and course of status epilepticus (SE) in children admitted to PIC. This may provide insight into reasons for admission to PIC and provide a framework for the development of strategies that decrease the requirement for intensive care.

DESIGN

Cross sectional, retrospective study.

SETTING

A tertiary paediatric institution's intensive care unit.

PARTICIPANTS

The admission database and all discharge summaries of each admission to a tertiary paediatric institution's PIC over a three year period were searched for children aged between 29 days and 15 years with a diagnosis of SE or related diagnoses. The case notes of potential cases of SE were systematically reviewed, and clinical and demographic data extracted using a standard data collection form.

RESULTS

Most children with SE admitted to PIC are aged less than 5 years, male to female ratio 1:1, and most (77%) will have had no previous episodes of SE. Prolonged febrile convulsions, SE related to central nervous system infection, and SE associated with epilepsy occur in similar proportions. Contrary to the Advanced Paediatric Life Support guidelines many children admitted to PIC for SE receive over two doses, or inadequate doses, of benzodiazepine. There is a risk of respiratory depression following administration of over two doses of benzodiazepine (chi2 = 3.4, p = 0.066). Children with SE admitted to PIC who had prehospital emergency treatment are more likely to receive over two doses of benzodiazepines (chi2 = 11.5, p = 0.001), and to subsequently develop respiratory insufficiency (chi2 = 6.2, p = 0.01). Mortality is low. Further study is required to determine the morbidity associated with SE in childhood requiring intensive care.

CONCLUSIONS

As the risk of respiratory depression is greater with more than two doses of benzodiazepines, clinicians should not disregard prehospital treatment of SE. As pre-PIC treatment of SE is inadequate in many cases, appropriate audit and modifications of standard guidelines are required.

KATP channel activation induces ischemic preconditioning of the endothelium in humans in vivo

BACKGROUND

Endothelial dysfunction contributes to ischemia-reperfusion injury (IRI) and is reduced by ischemic preconditioning (IPC). IPC may involve activation of ATP-sensitive potassium channels (K(ATP)). We determined whether modulation of K(ATP) channels occurs in endothelial IPC in humans.

METHODS AND RESULTS

IRI of the forearm was induced by inflating a blood pressure cuff to 200 mm Hg for 20 minutes in healthy volunteers. K(ATP) activation was modulated by intra-arterial glibenclamide (blocker) and diazoxide (opener). Endothelial function (response to intra-arterial acetylcholine) was assessed with forearm plethysmography before and after (1) 15-minute reperfusion, (2) IRI preceded by IPC (3 five-minute periods of ischemia), (3) IRI preceded by IPC with glibenclamide, (4) IPC followed by glibenclamide before IRI, (5) IRI preceded by diazoxide, and (6) IRI preceded by coinfusion of glibenclamide with diazoxide. IRI caused endothelial dysfunction (P=0.002), which IPC prevented (P=0.40). Glibenclamide abolished IPC when given contemporaneously with (P=0.003) or during IRI (P=0.0005). Diazoxide prevented endothelial dysfunction after IRI (P=0.68) but not when coinfused with glibenclamide.

CONCLUSIONS

Glibenclamide abolishes and diazoxide mimics endothelial IPC in humans. The time course of the effect of glibenclamide suggests involvement of K(ATP) channels as effectors of endothelial IPC in vivo. These data may have implications for understanding the therapeutic role of agents that modulate K(ATP) channel function.

Non-invasive diagnosis of tracheobronchomalacia using a modified ventilation radioisotope lung scan

The use of radionuclide ventilation lung scan to characterise the physiological effects of tracheobronchomalacia is a novel application of this non-invasive technique. In the reported case the right upper lobe was found to be not ventilated below a pressure of 20 cm H2O despite evidence from a dynamic tracheobronchogram of the right upper lobe bronchus opening at the lower pressure of 15 cm H2O.

Severe meningococcal disease is characterized by early neutrophil but not platelet activation and increased formation and consumption of platelet-neutrophil complexes

Approximately 25% of polymorphonuclear leukocytes (PMNL) circulate in heterotypic complexes with one or more activated platelets. These platelet-neutrophil complexes (PNC) require platelet CD62P expression for their formation and represent activated subpopulations of both cell types. In this study, we have investigated the presence, time course, and mechanisms of PNC formation in 32 cases of severe pediatric meningococcal disease (MD) requiring intensive care. There were marked early increases in PMNL CD11b/CD18 expression and activation, and reduced CD62L expression compared with intensive care unit control cases. Minimal platelet expression of the active form of alphaIIbbeta3 (GpIIb/IIIa) was seen. PNC were reduced on presentation and fell to very low levels after 24 h. Immunostaining of skin biopsies demonstrated that PNC appear outside the circulation in MD. In vitro studies of anticoagulated whole blood inoculated with Neisseria meningitidis supported these clinical findings with marked increases in PMNL CD11b/CD18 expression and activation but no detectable changes in platelet-activated alphaIIbbeta3 or CD62P expression. In vitro PMNL activation with N. meningitidis (or other agonists) potentiated the formation of PNC in response to platelet activation with adenine diphosphate. Therefore, in severe MD, PMNL activation is likely to promote PNC formation, and we suggest that the reduced levels of PNC seen in established MD reflect rapid loss of PNC from the circulation rather than reduced formation.

Multicentre study of fetal cardiac time intervals using magnetocardiography

OBJECTIVE

A database with reference values of the durations of the various waveforms in a magnetocardiogram of fetuses in uncomplicated pregnancies is assessed. This database will be of help to discriminate between pathologic and healthy fetuses. A fetal magnetocardiogram is a recording of the magnetic field in a location near the maternal abdomen and reflects the electric activity within the fetal heart. It is a non-invasive method, which can be used with nearly 100% reliability from the 20th week of gestation onward.

DESIGN

Durations of the waveforms were assembled from averaged magnetocardiograms and statistically processed.

SETTING

Fetal magnetocardiograms were measured with different magnetocardiographs. All measurements were carried out in magnetically shielded rooms.

SAMPLE

Fetal magnetocardiograms were obtained for 582 healthy patients.

METHOD

The durations of the waveforms were extracted from fetal magnetocardiograms measured at the cooperating centres. The variables collected included the duration of the P-wave, the PR interval, the PQ interval, the QRS complex, the QT interval and the T-wave and QTc value. The results were compared with values extracted from electrocardiograms of fetuses measured via electrodes attached to the maternal abdomen, from electrocardiograms measured during labour using a scalp electrode, and from electrocardiograms recorded in newborns, that were found in the literature.

MAIN OUTCOME MEASURES

Values of the durations are given as a function of gestational age including the regression line as well as the bounds marking the 90%, 95% and 98% prediction interval.

RESULTS

The durations of the P-wave, the PR interval, the QRS complex, the QT interval and QTc value increase linearly with gestational age. The durations of the PQ interval and the T-wave are independent of fetal age.

CONCLUSION

The values found agree with those found in the literature. The scatter of the data is wide due to the variation in normal physiology, the measuring system and signal processing and the subjectivity of the researcher. However, the system can define normal ranges and may be used in diagnosis.

Clinical implications of fetal magnetocardiography

OBJECTIVES

To test the usefulness and reliability of fetal magnetocardiography as a diagnostic or screening tool, both for fetuses with arrhythmias as well as for fetuses with a congenital heart defect.

METHODS

We describe 21 women with either a fetal arrhythmia or a congenital heart defect discovered during prenatal evaluation by sonography. Four fetuses showed a complete atrioventricular block, two an atrial flutter, nine ventricular extrasystole, and one a complete irregular heart rate. Five fetuses were suspected to have a congenital heart defect. In all cases magnetocardiograms were recorded.

RESULTS

Nine fetuses with extrasystole showed a range of premature atrial contractions, premature junctional beats or premature ventricular contractions. Two fetuses with atrial flutter showed typical flutter waves and four fetuses with complete atrioventricular block showed an uncoupling of P-wave and QRS complex. One fetus showed a pattern suggestive of a bundle branch block. In three of four fetuses with confirmed congenital heart defects the magnetocardiogram showed abnormalities.

CONCLUSION

Fetal magnetocardiography allows an insight into the electrophysiological aspects of the fetal heart, is accurate in the classification of fetal arrhythmias, and shows potential as a tool in defining a population at risk for congenital heart defects.

The influence of fetoabdominal tissues on fetal ECGs and MCGs

Both fetal electrocardiography and fetal magnetocardiography are influenced by the volume conduction within the abdomen of the pregnant woman. In this paper, various models are used to simulate this influence. Such models are helpful to determine where to attach electrodes at the maternal abdomen in case fetal ECGs are measured and where to position the magnetocardiograph in case fetal MCGs are measured. Another goal is to assess the influence of individual differences, such as the amount of amniotic fluid. Seven models based on MR-images have been created, four for the third trimester of gestation, with the fetus in left occiput position, and three for the second trimester. The models consist of four compartments; the fetus, the vernix caseosa, the amniotic fluid, and the remainder of the maternal abdomen. It turns out that individual differences have a large impact on the fetal MCG and that the best measurement positions are expected over the centre of the abdomen near the fetal heart. The fetal ECG is dependent on the vernix caseosa and when this layer is present, the fetal ECG is best measured by two electrodes, one over the fetal mouth and the other over the bottom of the fetus.

The passive DC conductivity of human tissues described by cells in solution

The electrical conductivity of human tissue at low frequencies is discussed when a uniform electric field is applied to some tissue containing many cells. Human tissue is described as a suspension of particles in a conducting solution. Relations are derived for the apparent conductivity of a cell surrounded by a membrane. These relations can be used to estimate the accuracy of a model that considers the cell as a non-conducting particle. Usually, a tissue is composed of several types of particles. A relationship that expresses the effective conductivity of a suspension of one type of ellipsoidal particles could be found in the literature. The orientation of the particles could be uniform or they could be randomly distributed. For non-conducting particles, this expression is known as Archie's law. The expression is extended such that also the effective conductivity of a suspension of various types of particles can be calculated. The result is evaluated for the cortex of the brain using experimental data given in the literature.

Platelet and leucocyte activation in childhood sickle cell disease: association with nocturnal hypoxaemia

We hypothesized that vaso-occlusive events in childhood sickle cell disease (SCD) may relate to inflammatory cell activation as well as interactions between sickle erythrocytes and vascular endothelium. Peripheral blood was examined from 24 children with SCD, of whom 12 had neurological sequelae and seven had frequent painful crises, and 10 control subjects. Platelet (CD62P and CD40L expression) and granulocyte (CD11b expression) activation and levels of platelet-erythrocyte and platelet-granulocyte complexes were determined by flow cytometry. Platelets (P = 0.019), neutrophils (P = 0.02) and monocytes (P = 0.001) were more activated and there were increased platelet-erythrocyte complexes (P = 0.026) in SCD patients compared with controls. Platelet-granulocyte complexes were not raised. There were no differences between the different groups of SCD. As hypoxia activates monocytes, platelets and endothelial cells and causes sickling of SCD erythrocytes, we also investigated 20 SCD patients with overnight pulse oximetry. Minimum overnight saturation correlated with the level of platelet-erythrocyte complexes (Spearman's rho -0.668, P < 0.02), neutrophil CD11b (Spearman's rho -0.466, P = 0.038) and monocyte CD11b (Spearman's rho -0.652, P = 0. 002). These findings provide important clues about the mechanism by which SCD patients may become predisposed to vaso-occlusive events.

Biological function of CD40 on human endothelial cells: costimulation with CD40 ligand and interleukin-4 selectively induces expression of vascular cell adhesion molecule-1 and P-selectin resulting in preferential adhesion of lymphocytes

The expression of adhesion molecules on vascular endothelial cells determines the pattern of migration and extravasation of leucocytes in inflammation and immunity. Here we show that costimulation with CD40 ligand (CD40L) and interleukin (IL)-4 (or IL-13) gives rise to a unique pattern of adhesion molecule expression by human umbilical vein endothelial cells (HUVEC). CD40 ligation alone enhanced expression of vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1) and E-selectin whereas IL-4 and IL-13 increased expression of VCAM-1 and P-selectin but not ICAM-1 or E-selectin. When IL-4 and CD40L were combined there was an additional increase of both VCAM-1 and P-selectin, but ICAM-1 and E-selectin were both inhibited. The combined effects of IL-4 and CD40L signalling were not the result of altered response kinetics, enhanced sensitivity of the endothelium, or increased expression of CD40 or the IL-4 receptor. The rise in VCAM-1 expression induced by combined IL-4 and CD40L stimulation was slower and more sustained than with tumour necrosis factor-alpha (TNF-alpha) and occurred only on a subset (75-80%) of the endothelial cell population compared to 100% with TNF-alpha. Costimulation with IL-4 and CD40L increased adhesion of T cells and B cells above levels obtained with either signal alone, but decreased adhesion of neutrophils. Furthermore, CD40 and IL-4 synergistically increased IL-6 but decreased IL-8 production by HUVEC. These results show that interactions between IL-4 and CD40 on endothelial cells give rise to specific patterns of adhesion molecule expression and cytokine production that may have important implications for lymphocyte and neutrophil migration and function at sites of inflammation.

Estimation of the electric conductivity from scalp measurements: feasibility and application to source localization

OBJECTIVES

The accuracy of electrical impedance tomography was investigated.

METHODS

The conductivities of the different compartments of the volume conductor were estimated by utilizing the boundary element method. The approach was tested for realistic head models with either 3 or 4 compartments. The impact of a geometrical error in the head model was investigated and the estimated conductivities were assigned to the compartments of the volume conductor used for the source imaging. The localization errors were quantified.

RESULTS

The method used allowed the estimation of the conductivity of the compartments. The poor conductivity of the skull decreased the precision with which the conductivity of deeper structures could be estimated. A geometrical error in the head model was compensated by the estimated conductivities. However, the estimated conductivities did not cancel the geometrical error in the head model as localization errors of the order of 10-20 mm were obtained.

CONCLUSIONS

In principle, the conductivity estimation of the distinct regions in the head is possible. The application of conductivity estimation to increase the accuracy of source localization remains questionable.

Lung cancer in New South Wales: current trends and the influence of age and sex

OBJECTIVE

To examine the effects of time, sex and age at diagnosis on lung cancer incidence rates and the distribution of the histological types of lung cancer in New South Wales.

DESIGN AND SETTING

Retrospective analysis of data from the NSW Cancer Registry and Australian Bureau of Statistics population data for NSW for 1985-1995.

MAIN OUTCOME MEASURES

Trends in lung cancer incidence rates between 1985 and 1995 for men and women aged over 30 years; changes in incidence rates within age groups; and incidence rates of histological subtypes relative to sex and age.

RESULTS

The incidence of lung cancer in men aged 40-80 years fell, while that in women aged over 65 rose. Rates were stable in younger women and older men. Incidence rates in men aged 40-60 years fell by 40%-60%. Were it not for the reduction in incidence rates in men between 1985 and 1995, the number of male lung cancer cases in 1995 would have been greater by 389 (95% CI, 362-415). In women, increasing incidence rates were responsible for an extra 242 cases (95% CI, 232-253) in 1995. Adenocarcinoma comprised a greater percentage of lung cancer cases in younger people, while squamous-cell carcinoma increases steadily with age in both men and women. Women with lung cancer are less likely to have squamous-cell carcinoma (25% for women v. 40% for men) and therefore more likely than men to have adenocarcinoma (35% of new female cases v. 26% for men) or small-cell lung cancer (24% v. 19%).

CONCLUSIONS

Increased smoking cessation has seen a halving of lung cancer rates in middle-aged men. Whether this represents delayed or prevented cases is uncertain. The distribution of histological subtypes of lung cancer in women is different from that in men, and it is not clear whether this difference is hormone-dependent or related to historical patterns of smoking.