Evaluation of Large-Scale Proteomics for Prediction of Cardiovascular Events.

Importance: Whether protein risk scores derived from a single plasma sample could be useful for risk assessment for atherosclerotic cardiovascular disease (ASCVD), in conjunction with clinical risk factors and polygenic risk scores, is uncertain. Objective: To develop protein risk scores for ASCVD risk prediction and compare them to clinical risk factors and polygenic risk scores in primary and secondary event populations. Design, Setting, and Participants: The primary analysis was a retrospective study of primary events among 13 540 individuals in Iceland (aged 40-75 years) with proteomics data and no history of major ASCVD events at recruitment (study duration, August 23, 2000 until October 26, 2006; follow-up through 2018). We also analyzed a secondary event population from a randomized, double-blind lipid-lowering clinical trial (2013-2016), consisting of individuals with stable ASCVD receiving statin therapy and for whom proteomic data were available for 6791 individuals. Exposures: Protein risk scores (based on 4963 plasma protein levels and developed in a training set in the primary event population); polygenic risk scores for coronary artery disease and stroke; and clinical risk factors that included age, sex, statin use, hypertension treatment, type 2 diabetes, body mass index, and smoking status at the time of plasma sampling. Main Outcomes and Measures: Outcomes were composites of myocardial infarction, stroke, and coronary heart disease death or cardiovascular death. Performance was evaluated using Cox survival models and measures of discrimination and reclassification that accounted for the competing risk of non-ASCVD death. Results: In the primary event population test set (4018 individuals [59.0% women]; 465 events; median follow-up, 15.8 years), the protein risk score had a hazard ratio (HR) of 1.93 per SD (95% CI, 1.75 to 2.13). Addition of protein risk score and polygenic risk scores significantly increased the C index when added to a clinical risk factor model (C index change, 0.022 [95% CI, 0.007 to 0.038]). Addition of the protein risk score alone to a clinical risk factor model also led to a significantly increased C index (difference, 0.014 [95% CI, 0.002 to 0.028]). Among White individuals in the secondary event population (6307 participants; 432 events; median follow-up, 2.2 years), the protein risk score had an HR of 1.62 per SD (95% CI, 1.48 to 1.79) and significantly increased C index when added to a clinical risk factor model (C index change, 0.026 [95% CI, 0.011 to 0.042]). The protein risk score was significantly associated with major adverse cardiovascular events among individuals of African and Asian ancestries in the secondary event population. Conclusions and Relevance: A protein risk score was significantly associated with ASCVD events in primary and secondary event populations. When added to clinical risk factors, the protein risk score and polygenic risk score both provided statistically significant but modest improvement in discrimination.

Genome-wide meta-analysis identifies 93 risk loci and enables risk prediction equivalent to monogenic forms of venous thromboembolism.

We report a genome-wide association study of venous thromboembolism (VTE) incorporating 81,190 cases and 1,419,671 controls sampled from six cohorts. We identify 93 risk loci, of which 62 are previously unreported. Many of the identified risk loci are at genes encoding proteins with functions converging on the coagulation cascade or platelet function. A VTE polygenic risk score (PRS) enabled effective identification of both high- and low-risk individuals. Individuals within the top 0.1% of PRS distribution had a VTE risk similar to homozygous or compound heterozygous carriers of the variants G20210A (c.*97 G > A) in F2 and p.R534Q in F5. We also document that F2 and F5 mutation carriers in the bottom 10% of the PRS distribution had a risk similar to that of the general population. We further show that PRS improved individual risk prediction beyond that of genetic and clinical risk factors. We investigated the extent to which venous and arterial thrombosis share clinical risk factors using Mendelian randomization, finding that some risk factors for arterial thrombosis were directionally concordant with VTE risk (for example, body mass index and smoking) whereas others were discordant (for example, systolic blood pressure and triglyceride levels).

Multiomics study of nonalcoholic fatty liver disease.

Nonalcoholic fatty liver (NAFL) and its sequelae are growing health problems. We performed a genome-wide association study of NAFL, cirrhosis and hepatocellular carcinoma, and integrated the findings with expression and proteomic data. For NAFL, we utilized 9,491 clinical cases and proton density fat fraction extracted from 36,116 liver magnetic resonance images. We identified 18 sequence variants associated with NAFL and 4 with cirrhosis, and found rare, protective, predicted loss-of-function variants in MTARC1 and GPAM, underscoring them as potential drug targets. We leveraged messenger RNA expression, splicing and predicted coding effects to identify 16 putative causal genes, of which many are implicated in lipid metabolism. We analyzed levels of 4,907 plasma proteins in 35,559 Icelanders and 1,459 proteins in 47,151 UK Biobank participants, identifying multiple proteins involved in disease pathogenesis. We show that proteomics can discriminate between NAFL and cirrhosis. The present study provides insights into the development of noninvasive evaluation of NAFL and new therapeutic options.

Genetic variants associated with platelet count are predictive of human disease and physiological markers.

Platelets play an important role in hemostasis and other aspects of vascular biology. We conducted a meta-analysis of platelet count GWAS using data on 536,974 Europeans and identified 577 independent associations. To search for mechanisms through which these variants affect platelets, we applied cis-expression quantitative trait locus, DEPICT and IPA analyses and assessed genetic sharing between platelet count and various traits using polygenic risk scoring. We found genetic sharing between platelet count and counts of other blood cells (except red blood cells), in addition to several other quantitative traits, including markers of cardiovascular, liver and kidney functions, height, and weight. Platelet count polygenic risk score was predictive of myeloproliferative neoplasms, rheumatoid arthritis, ankylosing spondylitis, hypertension, and benign prostate hyperplasia. Taken together, these results advance understanding of diverse aspects of platelet biology and how they affect biological processes in health and disease.

Large-Scale Screening for Monogenic and Clinically Defined Familial Hypercholesterolemia in Iceland.

Objective: Familial hypercholesterolemia (FH) is traditionally defined as a monogenic disease characterized by severely elevated LDL-C (low-density lipoprotein cholesterol) levels. In practice, FH is commonly a clinical diagnosis without confirmation of a causative mutation. In this study, we sought to characterize and compare monogenic and clinically defined FH in a large sample of Icelanders. Approach and Results: We whole-genome sequenced 49 962 Icelanders and imputed the identified variants into an overall sample of 166 281 chip-genotyped Icelanders. We identified 20 FH mutations in LDLR, APOB, and PCSK9 with combined prevalence of 1 in 836. Monogenic FH was associated with severely elevated LDL-C levels and increased risk of premature coronary disease, aortic valve stenosis, and high burden of coronary atherosclerosis. We used a modified version of the Dutch Lipid Clinic Network criteria to screen for the clinical FH phenotype among living adult participants (N=79 058). Clinical FH was found in 2.2% of participants, of whom only 5.2% had monogenic FH. Mutation-negative clinical FH has a strong polygenic basis. Both individuals with monogenic FH and individuals with mutation-negative clinical FH were markedly undertreated with cholesterol-lowering medications and only a minority attained an LDL-C target of <2.6 mmol/L (<100 mg/dL; 11.0% and 24.9%, respectively) or <1.8 mmol/L (<70 mg/dL; 0.0% and 5.2%, respectively), as recommended for primary prevention by European Society of Cardiology/European Atherosclerosis Society cholesterol guidelines. Conclusions: Clinically defined FH is a relatively common phenotype that is explained by monogenic FH in only a minority of cases. Both monogenic and clinical FH confer high cardiovascular risk but are markedly undertreated.

Lifelong Reduction in LDL (Low-Density Lipoprotein) Cholesterol due to a Gain-of-Function Mutation in LDLR.

BACKGROUND: Loss-of-function mutations in the LDL (low-density lipoprotein) receptor gene (LDLR) cause elevated levels of LDL cholesterol and premature cardiovascular disease. To date, a gain-of-function mutation in LDLR with a large effect on LDL cholesterol levels has not been described. Here, we searched for sequence variants in LDLR that have a large effect on LDL cholesterol levels. METHODS: We analyzed whole-genome sequencing data from 43 202 Icelanders. Single-nucleotide polymorphisms and structural variants including deletions, insertions, and duplications were genotyped using whole-genome sequencing-based data. LDL cholesterol associations were carried out in a sample of >100 000 Icelanders with genetic information (imputed or whole-genome sequencing). Molecular analyses were performed using RNA sequencing and protein expression assays in Epstein-Barr virus-transformed lymphocytes. RESULTS: We discovered a 2.5-kb deletion (del2.5) overlapping the 3' untranslated region of LDLR in 7 heterozygous carriers from a single family. Mean level of LDL cholesterol was 74% lower in del2.5 carriers than in 101 851 noncarriers, a difference of 2.48 mmol/L (96 mg/dL; P=8.4×10-8). Del2.5 results in production of an alternative mRNA isoform with a truncated 3' untranslated region. The truncation leads to a loss of target sites for microRNAs known to repress translation of LDLR. In Epstein-Barr virus-transformed lymphocytes derived from del2.5 carriers, expression of alternative mRNA isoform was 1.84-fold higher than the wild-type isoform (P=0.0013), and there was 1.79-fold higher surface expression of the LDL receptor than in noncarriers (P=0.0086). We did not find a highly penetrant detrimental impact of lifelong very low levels of LDL cholesterol due to del2.5 on health of the carriers. CONCLUSIONS: Del2.5 is the first reported gain-of-function mutation in LDLR causing a large reduction in LDL cholesterol. These data point to a role for alternative polyadenylation of LDLR mRNA as a potent regulator of LDL receptor expression in humans.

Fibrosis as measured by the biomarker, tissue inhibitor metalloproteinase-1, predicts mortality in Age Gene Environment Susceptibility-Reykjavik (AGES-Reykjavik) Study.

BACKGROUND: Fibrosis is a key pathological process in many chronic inflammatory disease states. AIMS: We hypothesized that tissue inhibitor metalloproteinase-1 and matrix metalloproteinase-9 (TIMP-1 and MMP-9), biomarkers of fibrosis, would predict all-cause mortality and we assessed the incremental value of these biomarkers when adjusting for clinical and other biomarkers. METHODS: The cohort included 5511 community-dwelling participants in the AGES-Reykjavik Study. The baseline Cox proportional hazards regression model was based on the Framingham Risk Score variables; we added TIMP-1, MMP-9, serum high-sensitivity C-reactive protein (hsCRP), and estimated glomerular filtration rate (eGFR). The primary outcome was all-cause 10-year mortality. Cause of death was categorized as cardiovascular death (CVD), cancer death, and other causes. RESULTS: Participants averaged 76 years and 43% were male. Ten-year mortality was 41% (2263 deaths). Of these, 915 (16.6%) died of cardiovascular disease (CVD), 543 (9.9%) with cancer, and 805 (14.6%) from other causes. For 10-year mortality, age was the strongest predictor (log likelihood χ2 = 798.7, P < 0.0001), followed by TIMP-1 (χ2 = 125.2, P < 0.0001), female gender, current smoker, diabetes mellitus, total cholesterol, eGFR (χ2 16.7, P < 0.0001), body mass index, and hsCRP (χ2 11.3, P = 0.0008) in that order. TIMP-1 and hsCRP had the highest continuous net reclassification improvement over the baseline model for 5-year survival [net reclassification index (NRI) 0.28 and 0.19, respectively, both P < 0.0001] and for 10-year survival (NRI 0.19 and 0.11, respectively, both statistically significant). CONCLUSION: TIMP-1 is the strongest predictor of all-cause mortality after age. The metabolic pathways regulating extracellular matrix homeostasis and fibrogenic processes appear pathologically relevant and are prognostically important.

Favourable long-term outcome after coronary artery bypass grafting in a nationwide cohort.

OBJECTIVES: In a nationwide cohort, we analyzed long-term outcome following coronary artery bypass grafting, using the combined strategy of left internal mammary artery to the left anterior descending artery and saphenous vein as secondary graft to other coronary targets. METHODS: 1,507 consecutive patients that underwent myocardial revascularization during 2001-2012 in Iceland. Mean follow-up was 6.8 years. Major adverse cardiac and cerebrovascular events were depicted using the Kaplan-Meier method. Cox-regression was used to define risk factors. Relative survival was estimated by comparing overall survival to the survival of Icelanders of the same age and gender. RESULTS: Mean age was 66 years, 83% were males, mean EuroSCOREst was 4.5, and 23% of the procedures were performed off-pump. At 5 years, 19.7% had suffered a major adverse cardiac or cerebrovascular event, 4.5% a stroke, 2.2% myocardial infarction, and 6.2% needed repeat revascularization. Overall 5-year survival was 89.9%, with a relative survival of 0.990. Independent predictors of major adverse cardiac and cerebrovascular events were left ventricular ejection fraction ≤30%, a previous history of percutaneous coronary intervention, chronic obstructive lung disease, chronic kidney disease, diabetes, and old age. The same variables and an earlier year of operation were predictors of long-term mortality. CONCLUSIONS: The long-term outcome following myocardial revascularization, using the left internal mammary artery and the great saphenous vein as conduits, is favourable and improving. This is reflected by the 5-year survival of 89.9%, deviating minimally from the survival rate of the general Icelandic population, together with a freedom from major adverse cardiac and cerebrovascular events of 80.3%.

Sequence variant at 4q25 near PITX2 associates with appendicitis.

Appendicitis is one of the most common conditions requiring acute surgery and can pose a threat to the lives of affected individuals. We performed a genome-wide association study of appendicitis in 7,276 Icelandic and 1,139 Dutch cases and large groups of controls. In a combined analysis of the Icelandic and Dutch data, we detected a single signal represented by an intergenic variant rs2129979 [G] close to the gene PITX2 associating with increased risk of appendicitis (OR = 1.15, P = 1.8 × 10-11). We only observe the association in patients diagnosed in adulthood. The marker is close to, but distinct from, a set of markers reported to associate with atrial fibrillation, which have been linked to PITX2. PITX2 has been implicated in determination of right-left symmetry during development. Anomalies in organ arrangement have been linked to increased prevalence of gastrointestinal and intra-abdominal complications, which may explain the effect of rs2129979 on appendicitis risk.

[Acute myocardial infarction among Icelanders forty years old and younger 2005-2009. Comparison with a study carried out 1980-1984].

INTRODUCTION: While acute myocardial infarction  (AMI) mostly is a disease of the elderly it also affects younger individuals, often with serious consequenses. In 1980-1984 a study was carried out on the incidence, risk factors, infarct location and distribution of atherosclerosis among Icelanders forty years and younger with AMI. Here we present the results of a similar study carried out for the five year period 2005-2009. MATERIALS AND METHODS: Medical and autopsy records of all individuals, forty years and younger, diagnosed with AMI (I21 in ICD-10) at Landspitali, National University Hospital 2005-2009, or suffering sudden cardiac death in Iceland during the same period were reviewed. Blood tests, electrocardiograms, echocardiograms, coronary angiograms and autopsy results were reviewed with respect to AMI-criteria. Statistical comparisons of ratios and means were carried out using Chi-square test and T-test, respectively. RESULTS: 38 individuals 40 years and younger, 32 males and 6 females, fulfilled the diagnostic criteria of AMI. Calculated incidence for the population at risk was 10/100.000/year (14/100.000/year in 1980-1984) and the mean age ±S.D. was 36.7±3.9. Three (7.9%) died suddenly before reaching hospital but of the 35 hospitalised patients 30 day mortality was zero, compared to nine (23.7%) pre-hospital deaths and two (6.9%) hospital deaths in 1980-1984. Thus, combined pre-hospital and in-hospital (30 day) mortality was 28.9% and 7.9% in the previous and recent time periods, respectively (p=0.02). In 2005-2009, 77.1% had a smoking history and 31.4% were hypertensive compared to 97% and 6.9% in 1980-85 (p=0.026 and p=0.015, respectively). Body mass index (BMI) was higher in the later period, 28.6±4,8 kg/m2 compared to 26.1±3.6 (mean±S.D.; p=0.04) but s-cholesterol was lower, 5.1±1.4 mmol/L compared to 6.3±1.16 ( mean±S.D.; p<0.01). In both studies single coronary artery disease was the most common angiographic pattern and the left anterior descending artery most often involved. CONCLUSION: Our results show that in two surveys 25 years apart AMI patients 40 years and younger are most often men. Smoking and family history were the most prominent risk factors during both periods but hypertension and high BMI were more common in 2005-2009 than in 1980-1984. Prognosis, as indicated by combined pre-hospital and in-hospital (30 day) mortality has improved. Key words: Myocardial infarction, forty and younger, incidence, risk factors, mortality, time trend Correspondence: Gudmundur Thorgeirsson gudmth@landspitali.is.

Thrombin or Ca(++)-ionophore-mediated fall in endothelial ATP levels independent of poly(ADP-Ribose) polymerase activity and NAD levels--comparison with the effects of hydrogen peroxide.

To test the hypothesis that a fall in cellular ATP following stimulation of endothelial cells with thrombin is secondary to a decrease in NAD levels caused by poly(ADP-Ribose)polymerase (PARP), we measured the levels of NAD and ATP in endothelial cells after treatment with thrombin, the Ca(++)-ionophore A23187, or hydrogen peroxide (H2O2), and compared the effects of inhibitors of PARP, NAD synthesis, and ADP-ribose breakdown on these responses. Neither thrombin nor A23187 caused a reduction in endothelial NAD levels and A23187 affected ATP levels independently of NAD levels or PARP activity. H2O2 induced lowering of NAD caused modest lowering of ATP but marked additional ATP-lowering, independent of PARP and NAD, was also demonstrated. We conclude that in endothelial cells ATP levels are largely independent of NAD and PARP, which do not play a role in thrombin or Ca(++)-ionophore-mediated lowering of ATP. H2O2 caused ATP lowering through a similar mechanism as thrombin and A23187 but, additionally, caused a further ATP lowering through its intense stimulation of PARP and marked lowering of NAD.

[Review on coronary artery disease--Part II: medical treatment, percutaneous interventions and myocardial revascularization]. / Yfirlitsgrein um kransæðasjúkdóm--síðari hluti: Lyfjameðferð, kransæðavíkkun og kransæðahjáveituaðgerð.

This article is the second of two review articles on coronary artery disease. The focus is on treatment with coverage of medical treatment, intravascular interventions and surgical therapy. The review is aimed at a wide readership of physicians and other health care providers but also at students of various health sciences. Current literature is reviewed with special focus on recent Icelandic studies.

Lower mortality following coronary arterial revascularization in patients taking statins.

OBJECTIVES: Numerous studies have suggested that statins have beneficial non-lipid-lowering effects, including reduction of systemic inflammatory response following surgery. We wanted to evaluate the effect of preoperative statin treatment on complications and operative mortality after coronary arterial revascularization. DESIGN: We performed a retrospective study of 720 consecutive patients who underwent on-pump coronary artery bypass grafting (CABG) (n = 513) or off-pump (OPCAB) (n = 207) in Iceland from 2002-2006. Patients taking statins preoperatively (n = 529) were compared with those not taking statins (n = 191). Predictors of complications and operative mortality were evaluated by univariate and multivariate analysis. RESULTS: Cardiovascular risk profiles were similar. However, hypertension was more common in the statin group but EuroSCORE was slightly lower. Operative mortality was significantly lower in patients taking statins (1.7% vs. 5.8%, p < 0.001). There were no significant differences in the incidence of major complications. Multivariate analysis showed that preoperative statin treatment was an independent predictor of lower operative mortality (OR = 0.33, p = 0.043), even after adjusting for EuroSCORE, acute operations, advanced age, or other medications. CONCLUSIONS: In this non- randomized study, patients taking statins had lower operative mortality than the controls after adjusting for multiple confounders. The reason for this might be linked to pleiotropic effects of statins.

eNOS activation mediated by AMPK after stimulation of endothelial cells with histamine or thrombin is dependent on LKB1.

Reports on the role of AMP-activated protein kinase (AMPK) in thrombin-mediated activation of endothelial nitric-oxide synthase (eNOS) in endothelial cells have been conflicting. Previously, we have shown that under culture conditions that allow reduction of ATP-levels after stimulation, activation of AMPK contributes to eNOS phosphorylation and activation in endothelial cells after treatment with thrombin. In this paper we examined the signaling pathways mediating phosphorylation and activation of eNOS after stimulation of cultured human umbilical vein endothelial cells (HUVEC) with histamine and the role of LKB1-AMPK in the signaling. In Morgan's medium 199 intracellular ATP was lowered by treatment with histamine or the ionophore A23187 while in medium RMPI 1640 ATP was unchanged after identical treatment. In medium 199 inhibition of Ca(+2)/CaM kinase kinase (CaMKK) by STO-609 only partially inhibited AMPK phosphorylation but after gene silencing of LKB1 with siRNA there was a total inhibition of AMPK phosphorylation by STO-609 after treatment with either histamine or thrombin, demonstrating phosphorylation of AMPK by both upstream kinases, LKB1 and CaMKK. Downregulation of AMPK with siRNA partially inhibited eNOS phosphorylation caused by histamine in cells maintained in medium 199. Downregulation of LKB1 by siRNA inhibited both phosphorylation and activity of eNOS and addition of the AMPK inhibitor Compound C had no further effect on eNOS phosphorylation. When experiments were carried out in medium 1640, STO-609 totally prevented the phosphorylation of AMPK without affecting eNOS phosphorylation. AMPKα2 downregulation resulted in a loss of the integrity of the endothelial monolayer and increased expression of GRP78, indicative of endoplasmic reticular (ER) stress. Downregulation of AMPKα1 had no such effect. The results show that culture conditions affect endothelial signal transduction pathways after histamine stimulation. Under conditions where intracellular ATP is lowered by histamine, AMPK is activated by both LKB1 and CaMKK and, in turn, mediates eNOS phosphorylation in an LKB1 dependent manner. Both AMPKα1 and -α2 are involved in the signaling. Under conditions where intracellular ATP is unchanged after histamine treatment, CaMKK alone activates AMPK and eNOS is phosphorylated and activated independent of AMPK.

Coronary artery calcium, brain function and structure: the AGES-Reykjavik Study.

BACKGROUND AND PURPOSE: Several cardiovascular risk factors are associated with cognitive disorders in older persons. Little is known about the association of the burden of coronary atherosclerosis with brain structure and function. METHODS: This is a cross-sectional analysis of data from the Age, Gene, Environment Susceptibility (AGES)-Reykjavik Study cohort of men and women born 1907 to 1935. Coronary artery calcification (CAC), a marker of atherosclerotic burden, was measured with CT. Memory, speed of processing, and executive function composites were calculated from a cognitive test battery. Dementia was assessed in a multistep procedure and diagnosed according to international guidelines. Quantitative data on total intracranial and tissue volumes (total, gray matter volume, white matter volume, and white matter lesion volume), cerebral infarcts, and cerebral microbleeds were obtained with brain MRI. The association of CAC with dementia (n=165 cases) and cognitive function in nondemented subjects (n=4085), and separately with MRI outcomes, was examined in multivariate models adjusting for demographic and vascular risk factors. Analyses tested whether brain structure mediated the associations of CAC to cognitive function. RESULTS: Subjects with higher CAC were more likely to have dementia and lower cognitive scores, more likely to have lower white matter volume, gray matter volume, and total brain tissue, and to have more cerebral infarcts, cerebral microbleeds, and white matter lesions. The relations of cognitive performance and dementia to CAC were significantly attenuated when the models were adjusted for brain lesions and volumes. CONCLUSIONS: In a population-based sample, increasing atherosclerotic load assessed by CAC is associated with poorer cognitive performance and dementia, and these relations are mediated by evidence of brain pathology.

Abnormal T-wave axis is associated with coronary artery calcification in older adults.

OBJECTIVE: To determine whether T-wave axis on the resting electrocardiogram (ECG) is associated with coronary artery calcification (CAC) score, a measurement of coronary atherosclerosis, in older adults. METHODS: The sample consisted of 2004 adults aged 66 and over participating in the prospective, population-based Age-Gene/Environment Susceptibility-Reykjavik Study. The cohort was divided into gender-stratified quartiles based upon Agatston CAC score derived from computerized tomography. Frontal T-axis deviation from 45 degrees was assessed using surface ECG. Statistical analysis was performed with Tobit regression models adjusted for demographic and cardiovascular risk factors. RESULTS: In the entire study population, T-axis deviation from 45 degrees was significantly associated with increasing CAC score in men (p<0.001) and women (p=0.03). In men without clinically recognized coronary heart disease (CHD), the association with CAC score remained statistically significant (p=0.02). This association was significant among women without CHD once male CAC cut points were used (p=0.05). CONCLUSION: An abnormal T-wave axis is associated with an increasing CAC score in this population of Icelandic older adults. This association remains in the subgroup of subjects without clinical CHD.

Mechanism of thrombin mediated eNOS phosphorylation in endothelial cells is dependent on ATP levels after stimulation.

Conflicting results have been reported concerning the role of AMP-activated protein kinase (AMPK) in mediating thrombin stimulation of endothelial NO-synthase (eNOS). We examined the involvement of two upstream kinases in AMPK activation in cultured human umbilical endothelial cells, LKB1 stimulated by a rise in intracellular AMP/ATP ratio, and Ca(+2)/CaM kinase kinase (CaMKK) responding to elevation of intracellular Ca(+2). We also studied the effects of AMPK activation on the downstream target eNOS. In culture medium 1640 the level of intracellular ATP was unchanged after thrombin stimulation and the CaMKK inhibitor STO-609 totally inhibited phosphorylation of AMPK and acetyl coenzyme A carboxylase (ACC) but not eNOS. In Morgan's medium 199 thrombin caused a significant lowering of intracellular ATP and STO-609 only partially inhibited the phosphorylation of AMPK, ACC and eNOS. Inhibition of AMPK by Compound C or AMPK downregulation using siRNA partially inhibited the phosphorylation of eNOS in medium 199 but not in 1640, underscoring a clear difference in the pathways mediating thrombin-stimulated eNOS phosphorylation in different culture media. Thus, conditions subjecting endothelial cells to a fall in ATP after thrombin stimulation facilitate activation of pathways partly dependent on AMPK causing downstream phosphorylation of eNOS. In contrast, under culture conditions that do not facilitate a fall in ATP after stimulation, AMPK activation is exclusively mediated by CaMKK and does not contribute to the phosphorylation of eNOS.

[Primary percutaneous coronary interventions in Iceland]. / Brádar kransaedathraedingar á Islandi.

INTRODUCTION: Acute coronary angiography with primary percutaneous coronary intervention (PCI), if executed with sufficient expertise and without undue delay, is the best therapy for patients with ST-elevation myocardial infarction (STEMI). At Landspitali-University Hospital 24 hour on-call service has been provided since December the 1st 2003. This hospital is the single center for all coronary catherizations in Iceland. This report is a review of this service during the first year. PATIENTS AND METHODS: Retrospective review was carried out of all hospital records and PCI worksheets of those who had an acute coronary angiography from December 1st 2003 until November 30th 2004. RESULTS: A total of 124 patients were investigated with acute coronary angiography, 94 men (76%) and 30 women (24%). The average age of men was 61 years (range 19 to 85 years) and women 67 years (range 38 to 84 years). The primary indication for acute coronary angiograpy was STEMI (83%), 8% non ST-elevation myocardial infarction (NSTEMI) and for the remaining 9% the procedure was performed for other reasons. Eleven patients (9%) suffered cardiac arrest prior to angiography and ten (8%) were in cardiogenic shock upon arrival to the hospital. The mean door-to-needle time was 47 minutes for all STEMI patients. In 76% of the cases the procedure started within 60 minutes and in 91% within the recommended 90 minutes. Mean hospital stay was 5 (1/2) days. Total mortality was 7% (9 patients). Of those 9 patients 5 were in cardiogenic shock at the arrival to the hospital and 4 had suffered cardiac arrest. The mortality rate among those who were neither in cardiogenic shock upon admission nor having suffered cardiac arrest was 1,7% (2 patients). During follow up for 15-27 months nine of the patients needed CABG and nine needed a repeat PCI. CONCLUSION: The experience of a 24 hour on-call service at Landspitali-University Hospital to carry out primary PCI for all patients in Iceland with STEMI proved excellent during its first year, with a short door-to-needle time, short hospital stay and low mortality.

Low complement C4B gene copy number predicts short-term mortality after acute myocardial infarction.

BACKGROUND AND OBJECTIVES: Some recent data indicate that risk of death after acute coronary syndrome is under genetic control. Previously, we found that the C4B*Q0 genotype (low copy number of the C4B gene that encodes the fourth component of complement) is strongly associated with morbidity and mortality of cardiovascular diseases (CVD). The +252 G allele of the lymphotoxin-alpha (LTA) gene encoded close to the C4B gene was also reported to be related to CVD-related mortality in an Oriental population. METHODS: The relationship between the copy number of the genes encoding the fourth component of complement (C4A and C4B) and LTA 252 single-nucleotide polymorphism (SNP) on the one hand and mortality after acute myocardial infarction (AMI) was studied in 142 Icelandic patients. The number of the C4A and C4B genes was determined in genomic DNA samples by a newly developed real-time PCR-based method; lymphotoxin-alpha (LTA) +252 A>G polymorphism was determined by PCR-restriction fragment length polymorphism analysis. RESULTS: The C4B*Q0 genotype was found to be strongly associated with 1-year mortality, with a hazard ratio of 3.50 (1.38-8.87) (P = 0.008) (adjusted Cox regression analysis). This association was, however, restricted to ever-smoking patients. By contrast, neither C4A gene copy numbers nor LTA 252 SNP did confer increased risk of mortality after AMI. CONCLUSIONS: This observation indicates that low C4B copy number is a strong risk factor for short-term mortality after AMI in smoking Icelandic patients, whereas LTA 252 G allele is not a risk factor in Caucasian population.