Genetic analysis of blood molecular phenotypes reveals common properties in the regulatory networks affecting complex traits

We evaluate the shared genetic regulation of mRNA molecules, proteins and metabolites derived from whole blood from 3029 human donors. We find abundant allelic heterogeneity, where multiple variants regulate a particular molecular phenotype, and pleiotropy, where a single variant associates with multiple molecular phenotypes over multiple genomic regions. The highest proportion of share genetic regulation is detected between gene expression and proteins (66.6%), with a further median shared genetic associations across 49 different tissues of 78.3% and 62.4% between plasma proteins and gene expression. We represent the genetic and molecular associations in networks including 2828 known GWAS variants, showing that GWAS variants are more often connected to gene expression in trans than other molecular phenotypes in the network. Our work provides a roadmap to understanding molecular networks and deriving the underlying mechanism of action of GWAS variants using different molecular phenotypes in an accessible tissue.

Multiallelic Copy Number Variation in ORM1 is Associated with Plasma Cell-Free DNA Levels as an Intermediate Phenotype for Venous Thromboembolism

Venous thromboembolism (VTE) is a common disease with high heritability. However, only a small portion of the genetic variance of VTE can be explained by known genetic risk factors. Neutrophil extracellular traps (NETs) have been associated with prothrombotic activity. Therefore, the genetic basis of NETs could reveal novel risk factors for VTE. A recent genome-wide association study of plasma cell-free DNA (cfDNA) levels in the Genetic Analysis of Idiopathic Thrombophilia 2 (GAIT-2) Project showed a significant associated locus near ORM1. We aimed to further explore this candidate region by next-generation sequencing, copy number variation (CNV) quantification, and expression analysis using an extreme phenotype sampling design involving 80 individuals from the GAIT-2 Project. The RETROVE study with 400 VTE cases and 400 controls was used to replicate the results. A total of 105 genetic variants and a multiallelic CNV (mCNV) spanning ORM1 were identified in GAIT-2. Of these, 17 independent common variants, a region of 22 rare variants, and the mCNV were significantly associated with cfDNA levels. In addition, eight of these common variants and the mCNV influenced ORM1 expression. The association of the mCNV and cfDNA levels was replicated in RETROVE (p-value = 1.19 × 10-6). Additional associations between the mCNV and thrombin generation parameters were identified. Our results reveal that increased mCNV dosages in ORM1 decreased gene expression and upregulated cfDNA levels. Therefore, the mCNV in ORM1 appears to be a novel marker for cfDNA levels, which could contribute to VTE risk.

Integrated GWAS and Gene Expression Suggest ORM1 as a Potential Regulator of Plasma Levels of Cell-Free DNA and Thrombosis Risk

Plasma cell-free DNA (cfDNA) is a surrogate marker of neutrophil extracellular traps (NETs) that contribute to immunothrombosis. There is growing interest about the mechanisms underlying NET formation and elevated cfDNA, but little is known about the factors involved. We aimed to identify genes involved in the regulation of cfDNA levels using data from the Genetic Analysis of Idiopathic Thrombophilia (GAIT-2) Project.

Imputed genotypes, whole blood RNA-Seq data, and plasma cfDNA quantification were available for 935 of the GAIT-2 participants from 35 families with idiopathic thrombophilia. We performed heritability and GWAS analysis for cfDNA. The heritability of cfDNA was 0.26 ( p  = 3.7 × 10 ⁻⁶ ), while the GWAS identified a significant association (rs1687391, p  = 3.55 × 10 ⁻¹⁰ ) near the ORM1 gene, on chromosome 9. An eQTL (expression quantitative trait loci) analysis revealed a significant association between the lead GWAS variant and the expression of ORM1 in whole blood ( p  = 6.14 × 10 ⁻⁹ ). Additionally, ORM1 expression correlated with levels of cfDNA ( p  = 4.38 × 10 ⁻⁴ ). Finally, genetic correlation analysis between cfDNA and thrombosis identified a suggestive association ( ρ_g  = 0.43, p  = 0.089).

All in all, we show evidence of the role of ORM1 in regulating cfDNA levels in plasma, which might contribute to the susceptibility to thrombosis through mechanisms of immunothrombosis.

Genetic variant effects on gene expression in human pancreatic islets and their implications for T2D

Most signals detected by genome-wide association studies map to non-coding sequence and their tissue-specific effects influence transcriptional regulation. However, key tissues and cell-types required for functional inference are absent from large-scale resources. Here we explore the relationship between genetic variants influencing predisposition to type 2 diabetes (T2D) and related glycemic traits, and human pancreatic islet transcription using data from 420 donors. We find: (a) 7741 cis-eQTLs in islets with a replication rate across 44 GTEx tissues between 40% and 73%; (b) marked overlap between islet cis-eQTL signals and active regulatory sequences in islets, with reduced eQTL effect size observed in the stretch enhancers most strongly implicated in GWAS signal location; (c) enrichment of islet cis-eQTL signals with T2D risk variants identified in genome-wide association studies; and (d) colocalization between 47 islet cis-eQTLs and variants influencing T2D or glycemic traits, including DGKB and TCF7L2. Our findings illustrate the advantages of performing functional and regulatory studies in disease relevant tissues.

Sequence-Defined Macrocycles for Understanding and Controlling the Build-up of Hierarchical Order in Self-Assembled 2D Arrays

Anfinsen's dogma that sequence dictates structure is fundamental to understanding the activity and assembly of proteins. This idea has been applied to all manner of oligomers but not to the behavior of cyclic oligomers, aka macrocycles. We do this here by providing the first proofs that sequence controls the hierarchical assembly of nonbiological macrocycles, in this case, at graphite surfaces. To design macrocycles with one (AAA), two (AAB), or three (ABC) different carbazole units, we needed to subvert the synthetic preferences for one-pot macrocyclizations. We developed a new stepwise synthesis with sequence-defined targets made in 11, 17, and 22 steps with 25, 10, and 5% yields, respectively. The linear build up of primary sequence (1°) also enabled a thermal Huisgen cycloaddition to proceed regioselectively for the first time using geometric control. The resulting macrocycles are planar (2° structure) and form H-bonded dimers (3°) at surfaces. Primary sequences encoded into the suite of tricarb macrocycles were shown by scanning-tunneling microscopy (STM) to impact the next levels of supramolecular ordering (4°) and 2D crystalline polymorphs (5°) at solution-graphite interfaces. STM imaging of an AAB macrocycle revealed the formation of a new gap phase that was inaccessible using only C3-symmetric macrocycles. STM imaging of two additional sequence-controlled macrocycles (AAD, ABE) allowed us to identify the factors driving the formation of this new polymorph. This demonstration of how sequence controls the hierarchical patterning of macrocycles raises the importance of stepwise syntheses relative to one-pot macrocyclizations to offer new approaches for greater understanding and control of hierarchical assembly.

Cross-tissue eQTL enrichment of associations in schizophrenia

The genome-wide association study of the Psychiatric Genomics Consortium identified over one hundred schizophrenia susceptibility loci. The number of non-coding variants discovered suggests that gene regulation could mediate the effect of these variants on disease. Expression quantitative trait loci (eQTLs) contribute to variation in levels of mRNA. Given the co-occurrence of schizophrenia and several traits not involving the central nervous system (CNS), we investigated the enrichment of schizophrenia associations among eQTLs for four non-CNS tissues: adipose tissue, epidermal tissue, lymphoblastoid cells and blood. Significant enrichment was seen in eQTLs of all tissues: adipose (β = 0.18, p = 8.8 × 10-06), epidermal (β = 0.12, p = 3.1 × 10-04), lymphoblastoid (β = 0.19, p = 6.2 × 10-08) and blood (β = 0.19, p = 6.4 × 10-06). For comparison, we looked for enrichment of association with traits of known relevance to one or more of these tissues (body mass index, height, rheumatoid arthritis, systolic blood pressure and type-II diabetes) and found that schizophrenia enrichment was of similar scale to that observed when studying diseases in the context of a more likely causal tissue. To further investigate tissue specificity, we looked for differential enrichment of eQTLs with relevant Roadmap affiliation (enhancers and promoters) and varying distance from the transcription start site. Neither factor significantly contributed to the enrichment, suggesting that this is equally distributed in tissue-specific and cross-tissue regulatory elements. Our analyses suggest that functional correlates of schizophrenia risk are prevalent in non-CNS tissues. This could be because of pleiotropy or the effectiveness of variants affecting expression in different contexts. This suggests the utility of large, single-tissue eQTL experiments to increase eQTL discovery power in the study of schizophrenia, in addition to smaller, multiple-tissue approaches. Our results conform to the notion that schizophrenia is a systemic disorder involving many tissues.

Age-dependent changes in mean and variance of gene expression across tissues in a twin cohort

Changes in the mean and variance of gene expression with age have consequences for healthy aging and disease development. Age-dependent changes in phenotypic variance have been associated with a decline in regulatory functions leading to increase in disease risk. Here, we investigate age-related mean and variance changes in gene expression measured by RNA-seq of fat, skin, whole blood and derived lymphoblastoid cell lines (LCLs) expression from 855 adult female twins. We see evidence of up to 60% of age effects on transcription levels shared across tissues, and 47% of those on splicing. Using gene expression variance and discordance between genetically identical MZ twin pairs, we identify 137 genes with age-related changes in variance and 42 genes with age-related discordance between co-twins; implying the latter are driven by environmental effects. We identify four eQTLs whose effect on expression is age-dependent (FDR 5%). Combined, these results show a complicated mix of environmental and genetically driven changes in expression with age. Using the twin structure in our data, we show that additive genetic effects explain considerably more of the variance in gene expression than aging, but less that other environmental factors, potentially explaining why reliable expression-derived biomarkers for healthy-aging have proved elusive compared with those derived from methylation.

A Low-Frequency Inactivating AKT2 Variant Enriched in the Finnish Population Is Associated With Fasting Insulin Levels and Type 2 Diabetes Risk

To identify novel coding association signals and facilitate characterization of mechanisms influencing glycemic traits and type 2 diabetes risk, we analyzed 109,215 variants derived from exome array genotyping together with an additional 390,225 variants from exome sequence in up to 39,339 normoglycemic individuals from five ancestry groups. We identified a novel association between the coding variant (p.Pro50Thr) in AKT2 and fasting plasma insulin (FI), a gene in which rare fully penetrant mutations are causal for monogenic glycemic disorders. The low-frequency allele is associated with a 12% increase in FI levels. This variant is present at 1.1% frequency in Finns but virtually absent in individuals from other ancestries. Carriers of the FI-increasing allele had increased 2-h insulin values, decreased insulin sensitivity, and increased risk of type 2 diabetes (odds ratio 1.05). In cellular studies, the AKT2-Thr50 protein exhibited a partial loss of function. We extend the allelic spectrum for coding variants in AKT2 associated with disorders of glucose homeostasis and demonstrate bidirectional effects of variants within the pleckstrin homology domain of AKT2.

A complete tool set for molecular QTL discovery and analysis

Population scale studies combining genetic information with molecular phenotypes (for example, gene expression) have become a standard to dissect the effects of genetic variants onto organismal phenotypes. These kinds of data sets require powerful, fast and versatile methods able to discover molecular Quantitative Trait Loci (molQTL). Here we propose such a solution, QTLtools, a modular framework that contains multiple new and well-established methods to prepare the data, to discover proximal and distal molQTLs and, finally, to integrate them with GWAS variants and functional annotations of the genome. We demonstrate its utility by performing a complete expression QTL study in a few easy-to-perform steps. QTLtools is open source and available at https://qtltools.github.io/qtltools/.

Analysis of molecular quantitative trait loci (molQTL) can help interpret genome-wide association studies and requires efficient approaches to correct for multiple testing. This study describes a bioinformatics toolkit called QTLtool that can handle large data sets and quickly perform multiple types of molQTL analyses.

Genome-wide association analysis identifies TXNRD2, ATXN2 and FOXC1 as susceptibility loci for primary open-angle glaucoma

Primary open angle glaucoma (POAG) is a leading cause of blindness world-wide. To identify new susceptibility loci, we meta-analyzed GWAS results from 8 independent studies from the United States (3,853 cases and 33,480 controls) and investigated the most significant SNPs in two Australian studies (1,252 cases and 2,592 controls), 3 European studies (875 cases and 4,107 controls) and a Singaporean Chinese study (1,037 cases and 2,543 controls). A meta-analysis of top SNPs identified three novel loci: rs35934224[T] within TXNRD2 (odds ratio (OR) = 0.78, P = 4.05×10⁻¹¹ encoding a mitochondrial protein required for redox homeostasis; rs7137828[T] within ATXN2 (OR = 1.17, P = 8.73×10⁻¹⁰), and rs2745572[A] upstream of FOXC1 (OR = 1.17, P = 1.76×10⁻¹⁰). Using RT-PCR and immunohistochemistry, we show TXNRD2 and ATXN2 expression in retinal ganglion cells and the optic nerve head. These results identify new pathways underlying POAG susceptibility and suggest novel targets for preventative therapies.

The First New Zealanders? An Alternative Interpretation of Stable Isotope Data from Wairau Bar, New Zealand

PLOS ONE Volume 8 includes an article “The First New Zealanders: Patterns of Diet and Mobility Revealed through Isotope Analysis”. The paper proposes that burial groups within the settlement phase site of Wairau Bar differ in terms of dietary stable isotopes and ⁸⁷Sr/⁸⁶Sr. The authors argue this difference is probably due to one group being a founding population while the other burials are later. Here we review the work of Kinaston et al. and present an alternative analysis and interpretation of the isotopic data. Treating the isotope data independently from cultural and biological factors we find that sex best explains dietary variation. Our reassessment of ⁸⁷Sr/⁸⁶Sr confirms the authors original finding of high mobility of early New Zealanders but suggests a larger range of individuals should be considered ‘non-local’ on current evidence.

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same region.

Common genetic variants influence human subcortical brain structures

The highly complex structure of the human brain is strongly shaped by genetic influences. Subcortical brain regions form circuits with cortical areas to coordinate movement, learning, memory and motivation, and altered circuits can lead to abnormal behaviour and disease. To investigate how common genetic variants affect the structure of these brain regions, here we conduct genome-wide association studies of the volumes of seven subcortical regions and the intracranial volume derived from magnetic resonance images of 30,717 individuals from 50 cohorts. We identify five novel genetic variants influencing the volumes of the putamen and caudate nucleus. We also find stronger evidence for three loci with previously established influences on hippocampal volume and intracranial volume. These variants show specific volumetric effects on brain structures rather than global effects across structures. The strongest effects were found for the putamen, where a novel intergenic locus with replicable influence on volume (rs945270; P = 1.08 × 10(-33); 0.52% variance explained) showed evidence of altering the expression of the KTN1 gene in both brain and blood tissue. Variants influencing putamen volume clustered near developmental genes that regulate apoptosis, axon guidance and vesicle transport. Identification of these genetic variants provides insight into the causes of variability in human brain development, and may help to determine mechanisms of neuropsychiatric dysfunction.

Gene expression changes with age in skin, adipose tissue, blood and brain

BACKGROUND

Previous studies have demonstrated that gene expression levels change with age. These changes are hypothesized to influence the aging rate of an individual. We analyzed gene expression changes with age in abdominal skin, subcutaneous adipose tissue and lymphoblastoid cell lines in 856 female twins in the age range of 39-85 years. Additionally, we investigated genotypic variants involved in genotype-by-age interactions to understand how the genomic regulation of gene expression alters with age.

RESULTS

Using a linear mixed model, differential expression with age was identified in 1,672 genes in skin and 188 genes in adipose tissue. Only two genes expressed in lymphoblastoid cell lines showed significant changes with age. Genes significantly regulated by age were compared with expression profiles in 10 brain regions from 100 postmortem brains aged 16 to 83 years. We identified only one age-related gene common to the three tissues. There were 12 genes that showed differential expression with age in both skin and brain tissue and three common to adipose and brain tissues.

CONCLUSIONS

Skin showed the most age-related gene expression changes of all the tissues investigated, with many of the genes being previously implicated in fatty acid metabolism, mitochondrial activity, cancer and splicing. A significant proportion of age-related changes in gene expression appear to be tissue-specific with only a few genes sharing an age effect in expression across tissues. More research is needed to improve our understanding of the genetic influences on aging and the relationship with age-related diseases.

ZNF804A and cortical thickness in schizophrenia and bipolar disorder

ZNF804A SNP rs1344706 confers genome-wide risk for schizophrenia and bipolar disorder. Both disorders affect cortical thickness. To determine if single nucleotide polymorphisms (SNPs) across ZNF804A are associated with cortical thinning, we investigated 63 SNPs (including rs1344706) in 365 psychosis patients and healthy controls. Results show no significant associations.

Genome-wide association study identifies genetic loci associated with body mass index and high density lipoprotein-cholesterol levels during psychopharmacological treatment - a cross-sectional naturalistic study

Metabolic and cardiovascular side effects are serious clinical problems related to psychopharmacological treatment, but the underlying mechanisms are mostly unknown. We performed a genome-wide association study of metabolic and cardiovascular risk factors during pharmacological therapy. Twelve indicators of metabolic side effects as well as cardiovascular risk factors were analyzed in a naturalistic sample of 594 patients of Norwegian ancestry. We analyzed interactions between gene variants and three categories of psychopharmacological agents based on their reported potential for side effects. For body mass index (BMI), two significantly associated loci were identified on 8q21.3. There were seven markers in one 30-kb region, and the strongest signal was rs7838490. In another locus 140kb away, six markers were significant, and rs6989402 obtained the strongest signal. Both of these loci are located upstream of the gene matrix metalloproteinase 16 (MMP16). For high density lipoprotein cholesterol (HDL-C), marker rs11615274 on 12q21 was significant. The results highlight three genomic regions potentially harboring susceptibility genes for drug-induced metabolic side effects, identifying MMP16 as a candidate gene. This deserves to be replicated in additional populations to provide more evidence for molecular genetic mechanisms of side effects during psychopharmacological treatment.

TCF4 sequence variants and mRNA levels are associated with neurodevelopmental characteristics in psychotic disorders

TCF4 is involved in neurodevelopment, and intergenic and intronic variants in or close to the TCF4 gene have been associated with susceptibility to schizophrenia. However, the functional role of TCF4 at the level of gene expression and relationship to severity of core psychotic phenotypes are not known. TCF4 mRNA expression level in peripheral blood was determined in a large sample of patients with psychosis spectrum disorders (n = 596) and healthy controls (n = 385). The previously identified TCF4 risk variants (rs12966547 (G), rs9960767 (C), rs4309482 (A), rs2958182 (T) and rs17512836 (C)) were tested for association with characteristic psychosis phenotypes, including neurocognitive traits, psychotic symptoms and structural magnetic resonance imaging brain morphometric measures, using a linear regression model. Further, we explored the association of additional 59 single nucleotide polymorphisms (SNPs) covering the TCF4 gene to these phenotypes. The rs12966547 and rs4309482 risk variants were associated with poorer verbal fluency in the total sample. There were significant associations of other TCF4 SNPs with negative symptoms, verbal learning, executive functioning and age at onset in psychotic patients and brain abnormalities in total sample. The TCF4 mRNA expression level was significantly increased in psychosis patients compared with controls and positively correlated with positive- and negative-symptom levels. The increase in TCF4 mRNA expression level in psychosis patients and the association of TCF4 SNPs with core psychotic phenotypes across clinical, cognitive and brain morphological domains support that common TCF4 variants are involved in psychosis pathology, probably related to abnormal neurodevelopment.

Photoresponsive polymer brushes for hydrophilic patterning

The use of photolabile protecting groups (PGs) as a means to create latent hydrophilic surfaces is presented. Naturally hydrophobic PGs, based on o-nitrobenzyl chemistry, are used on polymer side chains, poised for cleavage upon exposure to UV light. Removal of the PGs liberates the hydrophilic polymer, thereby switching the surface wettability from hydrophobic to hydrophilic. This switch can be augmented by increasing the surface roughness. Additionally, this system is also shown to be spatially addressable, a highly desirable property for applications which require specific regions of a surface to switch their wettability.

Haematological splenectomy. Changing indications and complications

Review of splenectomies carried out for haematological disease over a ten-year period, at a district hospital, shows that the indications for splenectomy have changed substantially over this time. Fewer patients with idiopathic thrombocytopenic purpura now require splenectomy, however its role in the management of lymphoproliferative disorders has expanded. Splenectomy remains an important therapeutic option for a range of haematological disorders: this series shows it to be a safe and effective operation in selected patients, although it is not without both short and long-term sequelae.

Circumcision in 'buried penis'--a cautionary tale

BACKGROUND

The aim of a circumcision is to remove sufficient foreskin from the penile shaft and preputial epithelium to uncover the glans. Removal of too much preputial skin may lead to an unsatisfactory cosmetic and functional result. Patients with a congenital anomaly known as 'buried penis' are particularly susceptible to this. In this condition, abnormal dartos fascial bands or muscle fibres tether the penile shaft and as a result conceal its true length.

CASE REPORT

A 5-year-old boy underwent circumcision but his 'buried penis' was not recognised by the surgeon pre-operatively. Unfortunately, his penile shaft was left almost entirely denuded of skin as a result. The wound required a full thickness graft. Follow-up at 1 year has so far been satisfactory.

CONCLUSIONS

This case highlights the importance of early recognition of a buried penis when considering circumcision. It demonstrates the abnormal anatomy of a buried penis and its management. It also provides a potential reconstructive option in cases of excess skin removal.

Protective effects of recombinant human antithrombin III in pig-to-primate renal xenotransplantation

Delayed rejection of pig kidney xenografts by primates is associated with vascular injury that may be accompanied by a form of consumptive coagulopathy in recipients. Using a life-supporting pig-to-baboon renal xenotransplantation model, we have tested the hypothesis that treatment with recombinant human antithrombin III would prevent or at least delay the onset of rejection and coagulopathy. Non-immunosuppressed baboons were transplanted with transgenic pig kidneys expressing the human complement regulators CD55 and CD59. Recipients were treated with an intravenous infusion of antithrombin III eight hourly (250 units per kg body weight), with or without low molecular weight heparin. Antithrombin-treated recipients had preservation of normal renal function for 4-5 days, which was twice as long as untreated animals, and developed neither thrombocytopenia nor significant coagulopathy during this period. Thus, recombinant antithrombin III may be a useful therapeutic agent to ameliorate both early graft damage and the development of systemic coagulation disorders in pig-to-human xenotransplantation.

Molecular organization of the nodal region is not altered in spontaneously diabetic BB-Wistar rats

We examined the organization of the molecular components of the nodal region in spontaneously diabetic BB-Wistar rats. Frozen sections and teased fibers from the sciatic nerves were immunostained for nodal (voltage-gated Na(+) channels, ankyrin(G), and ezrin), paranodal (contactin, Caspr, and neurofascin 155 kDa), and juxtaparanodal (Caspr2, the Shaker-type K(+) channels Kv1.1 and Kv1.2, and their associated subunit Kvbeta2) proteins. All of these proteins were properly localized in myelinated fibers from rats that had been diabetic for 15-44 days, compared to age-matched, nondiabetic animals. These results demonstrate that the axonal membrane is not reorganized, so nodal reorganization is not likely to be the cause of nerve conduction slowing in this animal model of acute diabetes.

Acute facial-nerve paralysis with parotid adenolymphoma

An 82-year-old woman presented with acute facial paralysis in association with parotid swelling following fine-needle aspiration cytology of a parotid adenolymphoma. Evacuation of a tense haematoma decompressed the nerve and led to complete recovery within 6 months. Additionally, the tumour is no longer evident, either clinically or radiologically, and fine-needle aspiration cytology appears to have been both diagnostic and, inadvertently, therapeutic in this case.

Dietary modulation of endothelial function: implications for cardiovascular disease

The vascular endothelium is the primary site of dysfunction in many diseases, particularly cardiovascular disease. A variety of risk factors, including smoking, hypercholesterolemia, hyperhomocysteinemia, hypertension, and diabetes mellitus, adversely affect endothelial function. Emerging evidence suggests an important role of dietary factors in modulating endothelial function. In particular, n-3 fatty acids, antioxidant vitamins (especially vitamins E and C), folic acid, and L-arginine appear to have beneficial effects on vascular endothelial function, either by decreasing endothelial activation or by improving endothelium-dependent vasodilation in patients at high risk of cardiovascular disease as well as in healthy subjects. These effects may serve as one potential mechanism through which these nutrients reduce the risk of cardiovascular disease, as observed in epidemiologic studies and several clinical trials. This article reviews clinical and experimental evidence regarding the role of these nutrients in modulating endothelial function and their potential to prevent cardiovascular disease.

Renal xenografts from triple-transgenic pigs are not hyperacutely rejected but cause coagulopathy in non-immunosuppressed baboons

BACKGROUND

The genetic modification of pigs is a powerful strategy that may ultimately enable successful xenotransplantation of porcine organs into humans.

METHODS

Transgenic pigs were produced by microinjection of gene constructs for human complement regulatory proteins CD55 and CD59 and the enzyme alpha1,2-fucosyltransferase (H-transferase, HT), which reduces expression of the major xenoepitope galactose-alpha1,3-galactose (alphaGal). Kidneys from CD55/HT and CD55/CD59/HT transgenic pigs were transplanted into nephrectomised, nonimmunosuppressed adult baboons.

RESULTS

In several lines of transgenic pigs, CD55 and CD59 were expressed strongly in all tissues examined, whereas HT expression was relatively weak and did not significantly reduce alphaGal. Control nontransgenic kidneys (n=4) grafted into baboons were hyperacutely rejected within 1 hr. In contrast, kidneys from CD55/HT pigs (n=2) were rejected after 30 hr, although kidneys from CD55/CD59/HT pigs (n=6) maintained function for up to 5 days. In the latter grafts, infiltration by macrophages, T cells, and B cells was observed at days 3 and 5 posttransplantation. The recipients developed thrombocytopenia and abnormalities in coagulation, manifested in increased clotting times and an elevation in the plasma level of the fibrin degradation product D-dimer, within 2 days of transplantation. Treatment with low molecular weight heparin prevented profound thrombocytopenia but not the other aspects of coagulopathy.

CONCLUSIONS

Strong expression of CD55 and CD59 completely protected porcine kidneys from hyperacute rejection and allowed a detailed analysis of xenograft rejection in the absence of immunosuppression. Coagulopathy appears to be a common feature of pig-to-baboon renal transplantation and represents yet another major barrier to its clinical application.

Prominent role of P-selectin in the development of advanced atherosclerosis in ApoE-deficient mice

BACKGROUND

Adhesive interactions between leukocytes and endothelial cells are characteristic of the development of atherosclerotic lesions, but the receptors involved remain to be defined. P-selectin is an adhesion receptor expressed on activated endothelial cells or platelets and was shown to be involved in fatty streak formation in LDL receptor-deficient mice on an atherogenic diet. The main purpose of this study is to examine the role of P-selectin in the spontaneous development of advanced atherosclerosis in apoE-deficient mice. METHODDS AND RESULTS: We intercrossed P-selectin-deficient mice with mice lacking apoE and compared lesion development in apoE-deficient mice with P-selectin (apoE(-/-) P(+/+)) and without P-selectin (apoE(-/-) P(-/-)) that were fed normal mouse chow. At 4 months of age, apoE(-/-) P(-/-) mice had 3. 5-fold smaller aortic sinus lesions than apoE(-/-) P(+/+) mice. These were limited to fatty streaks in the apoE(-/-) P(-/-) mice, whereas 70% of apoE(-/-) P(+/+) lesions contained smooth muscle cells. Significantly more of the aortic sinus circumference was covered by lesions in the apoE(-/-) P(+/+) animals. The P-selectin genotype affected macrophage recruitment, because twice as many mononuclear cells were present in the P-selectin-positive lesions. At 15 months, the lesions progressed to the fibrous plaque stage in both genotypes and spread throughout the aorta, but this process was delayed in apoE(-/-) P(-/-) mice. In the aortic sinus, the lesions of the apoE(-/-) P(-/-) mice were 2.6-fold smaller and less calcified.

CONCLUSIONS

P-selectin appears to be a key adhesion receptor mediating leukocyte recruitment into lesions and promoting advanced atherosclerosis in apoE-deficient mice.

The combined role of P- and E-selectins in atherosclerosis

P- and E-selectins are adhesion molecules mediating the first step in leukocyte extravasation. Because their function in leukocyte adhesion is overlapping, we hypothesized that there might be a combined effect of these selectins on the development of atherosclerotic lesions. We bred P- and E-selectin-double-deficient mice onto the low-density lipoprotein receptor (LDLR)-deficient background (LDLR-/- P/E-/-) and compared lesion development in these mice to that in mice wild type for both selectins (LDLR-/- P/E+/+). After 8 wk on atherogenic diet, the LDLR-/- P/E-/- mice developed fatty streaks in the aortic sinus that were five times smaller than those in LDLR-/- P/E+/+ mice. The density of macrophages in the fatty streaks was comparable between LDLR-/- P/E+/+ and LDLR-/- P/E-/- mice. After 22 wk on the diet, the lesions spread throughout the aorta but this process was delayed in LDLR-/- P/E-/- mice. At 37 wk on diet, the lesions progressed to the fibrous plaque stage in both genotypes. However, the lesions in the aortic sinus in LDLR-/- P/E-/- mice were 40% smaller and less calcified than those of LDLR-/- P/E +/+ mice. Our results suggest that P- and E-selectins together play an important role in both early and advanced stages of atherosclerotic lesion development.

Soft tissue gliomatosis--heterotopic glial tissue in the subcutis: a case report

A subcutaneous nodule composed of heterotopic glial tissue is reported. The lesion was present in the subcutaneous tissue of the chest wall in a 2-year-old female. Histologically it was composed of loosely textured fibrillary neuroglial tissue in a densely hyalinized collagenous stroma. Immunohistochemical staining for glial fibrillary acidic protein was positive. The possible origin of this soft tissue glial heterotopia is discussed and the subject of heterotopic glial tissue is reviewed.

Experience with the EEA stapler in carcinoma of the lower rectum

The lower rectum is defined and the overall management of carcinoma in this area is considered with regard to operations available, whether these operations are equally radical, and the problem of continence. The various types of low anterior resection are mentioned and the use of EEA stapling device is described. Personal experience with this instrument is reviewed, with special regard to the 'learning curve', the avoidance of colostomies, the technique, and the complications.

Colonoscopy in lower gastro-intestinal haemorrhage

The value of colonoscopy in the diagnosis and management of lower gastro-intestinal haemorrhage was assessed in 107 patients who were examined during a 2-year period. The main indications were to define uncertain radiological findings, to further investigate the cause of bleeding in patients with normal barium studies and to carry out polypectomy. Radiological lesions were confirmed in 27, defined in 12, and refuted in 14 patients. Twenty-eight lesions were demonstrated on colonoscopy which were not diagnosed by barium enema or sigmoidoscopy. A diagnosis was made by colonoscopy in more than two-thirds of the patients with frank blood loss and normal radiographs. In cases of occult bleeding it was farless helpful. Colonoscopy significantly improved diagnosis and management of gastro-intestinal bleeding when the cause was in doubt after standard investigations. In addition, 37 polyps were removed through the colonoscope from 30 patients.

Crush syndrome: a report of 2 cases and a review of the literature

The crush syndrome was first defined as a clinical entity in 1941. This paper reports 2 patients suffering from the syndrome as a result of being trapped for several hours during the Moorgate tube train disaster. An account of the initial course, management and complications is presented and discussed with reference to the available literature on the subject.