Antiviral signalling by a cyclic nucleotide activated CRISPR protease.

CRISPR defence systems such as the well-known DNA-targeting Cas9 and the RNA-targeting type III systems are widespread in prokaryotes1,2. The latter orchestrates a complex antiviral response that is initiated through the synthesis of cyclic oligoadenylates after recognition of foreign RNA3-5. Among the large set of proteins that are linked to type III systems and predicted to bind cyclic oligoadenylates6,7, a CRISPR-associated Lon protease (CalpL) stood out to us. CalpL contains a sensor domain of the SAVED family7 fused to a Lon protease effector domain. However, the mode of action of this effector is unknown. Here we report the structure and function of CalpL and show that this soluble protein forms a stable tripartite complex with two other proteins, CalpT and CalpS, that are encoded on the same operon. After activation by cyclic tetra-adenylate (cA4), CalpL oligomerizes and specifically cleaves the MazF homologue CalpT, which releases the extracytoplasmic function σ factor CalpS from the complex. Our data provide a direct connection between CRISPR-based detection of foreign nucleic acids and transcriptional regulation. Furthermore, the presence of a SAVED domain that binds cyclic tetra-adenylate in a CRISPR effector reveals a link to the cyclic-oligonucleotide-based antiphage signalling system.

The impact of aortic valve replacement on survival in patients with normal flow low gradient severe aortic stenosis: a propensity-matched comparison.

AIMS: To assess the survival benefit of aortic valve replacement (AVR) in patients with normal flow low gradient severe aortic stenosis (AS). METHODS AND RESULTS: A retrospective study of prospectively collected data of 276 patients (mean age 75 ± 15 years, 51% male) with normal transaortic flow [flow rate (FR) ≥200 mL/s or stroke volume index (SVi) ≥35 mL/m2] and severe AS (aortic valve area <1.0 cm2). The outcome measure was all-cause mortality. Of the 276 patients, 151 (55%) were medically treated, while 125 (45%) underwent an AVR. Over a mean follow-up of 3.2 ± 1.8 years (range 0-6.9 years), a total of 96 (34.8%) deaths occurred: 17 (13.6%) in AVR group vs. 79 (52.3%) in those medically treated, when transaortic flow was defined by FR (P < 0.001). When transaortic flow was defined by SVi, a total of 79 (31.3%) deaths occurred: 18 (15.1%) in AVR group vs. 61 (45.9%) in medically treated (P < 0.001). In a propensity-matched multivariable Cox regression analysis adjusting for age, gender, body surface area, smoking, hypertension, diabetes mellitus, atrial fibrillation, peripheral vascular disease, chronic kidney disease, left ventricular ejection fraction, left ventricular mass, and mean aortic gradient, not having AVR was associated with a 6.3-fold higher hazard ratio (HR) of all-cause mortality [HR 6.28, 95% confidence interval (CI) 3.34-13.16; P < 0.001] when flow was defined by FR. In the SVi-guided model, it was 3.83-fold (HR 3.83, 95% CI 2.30-6.37; P < 0.001). CONCLUSION: In patients with normal flow low gradient severe AS, AVR was associated with a significantly improved survival compared with those who received standard medical treatment.

Increased plasma trimethylamine-N-oxide is associated with incident atrial fibrillation.

BACKGROUND: Plasma trimethylamine-N-oxide (TMAO) is associated with cardiovascular disease; however specific relationships with cardiac arrhythmias are unknown. We evaluated the association between plasma TMAO and incident atrial fibrillation (AF). METHODS: Risk associations were explored among 3797 patients with suspected stable angina in the Western Norway Coronary Angiography Cohort (WECAC) and verified in 3143 elderly participants in the community-based Hordaland Health Study (HUSK). Information on endpoints was obtained from nationwide registries. RESULTS: Median follow-up was 7.3 and 10.8 years in the WECAC and HUSK cohorts, respectively, and 412 (10.9%) and 484 (15.4%) subjects were registered with incident AF. The age and gender adjusted HRs were 1.16, 95% CI 1.05-1.28 and 1.10, 95% CI 1.004-1.19 per 1 SD increase in log-transformed plasma TMAO. Adjusting for hypertension, BMI, smoking, diabetes, or intake of total choline, a TMAO precursor, did not materially influence the risk associations. Among patients in WECAC, further extensive adjustment for other AF risk factors yielded similar results. Adding TMAO to traditional AF risk factors (age, gender, hypertension, BMI, smoking and diabetes) yielded a continuous net reclassification improvement of 0.108, 95% CI 0.015-0.202 and 0.139, 95% CI 0.042-0.235. CONCLUSIONS: Plasma TMAO was associated with and improved reclassification of incident AF in two independent Norwegian cohorts with long-term follow-up. The relationship was independent of traditional AF risk factors, as well as of dietary choline intake. Our findings motivate further studies to explore endogenous metabolic factors influencing the relationship between TMAO and cardiovascular disease.

Fibrinogen and Neopterin Is Associated with Future Myocardial Infarction and Total Mortality in Patients with Stable Coronary Artery Disease.

Systemic fibrinogen and neopterin are related to inflammation. We investigated the prognostic utility and possible interactions of these biomarkers in stable coronary artery disease (SCAD) patients undergoing coronary angiography. We included 3,545 patients with suspected stable angina with a median follow-up of 7.3 and 10.2 years for incident acute myocardial infarction (AMI) and all-cause mortality, respectively. Prospective associations were explored by Cox regression. Potential effect modifications were investigated according to strata of fibrinogen, neopterin or high-sensitivity troponin T (hsTnT) below and above the median, as well as gender and smoking habits. During follow-up, 543 patients experienced an AMI and 769 patients died. In a multivariable model, the hazard ratios (HRs; 95% confidence interval [CI]) per 1 SD increase for fibrinogen in relation to these endpoints were 1.30 (1.20, 1.42; p < 0.001) and 1.22 (1.13, 1.31; p < 0.001), respectively. For neopterin, the HRs (95% CI) were 1.31 (1.23, 1.40; p < 0.001) and 1.24 (1.15, 1.34; p < 0.001), respectively. No significant interaction between fibrinogen and neopterin was observed. The prognostic utility of neopterin for incident AMI was improved in patients with an hsTnT above the median, for total mortality in non-smokers, and for both total mortality and AMI in females. In conclusion, both fibrinogen and neopterin were associated with future AMI and total mortality, but had low discriminatory impact. No interaction was observed between these two biomarkers. The prognostic utility of neopterin was improved in patients with hsTnT levels above the median, and in females and non-smokers.

A Quantitative Model for cAMP Binding to the Binding Domain of MloK1.

Ligand-protein binding processes are essential in biological systems. A well-studied system is the binding of cyclic adenosine monophosphate to the cyclic nucleotide binding domain of the bacterial potassium channel MloK1. Strikingly, the measured on-rate for cyclic adenosine monophosphate binding is two orders of magnitude slower than a simple Smoluchowski diffusion model would suggest. To resolve this discrepancy and to characterize the ligand-binding path in structural and energetic terms, we calculated 1100 ligand-binding molecular dynamics trajectories and tested two scenarios: In the first scenario, the ligand transiently binds to the protein surface and then diffuses along the surface into the binding site. In the second scenario, only ligands that reach the protein surface in the vicinity of the binding site proceed into the binding site. Here, a binding funnel, which increasingly confines the translational as well as the rotational degrees of freedom, determines the binding pathways and limits the on-rate. From the simulations, we identified five surface binding states and calculated the rates between these surface binding states, the binding site, and the bulk. We find that the transient binding of the ligands to the surface binding states does not affect the on-rate, such that this effect alone cannot explain the observed low on-rate. Rather, by quantifying the translational and rotational degrees of freedom and by calculating the binding committor, our simulations confirmed the existence of a binding funnel as the main bottleneck. Direct binding via the binding funnel dominates the binding kinetics, and only ∼10% of all ligands proceed via the surface into the binding site. The simulations further predict an on-rate between 15 and 40µs-1(mol/l)-1, which agrees with the measured on-rate.

A novel biosensor to study cAMP dynamics in cilia and flagella.

The cellular messenger cAMP regulates multiple cellular functions, including signaling in cilia and flagella. The cAMP dynamics in these subcellular compartments are ill-defined. We introduce a novel FRET-based cAMP biosensor with nanomolar sensitivity that is out of reach for other sensors. To measure cAMP dynamics in the sperm flagellum, we generated transgenic mice and reveal that the hitherto methods determining total cAMP levels do not reflect changes in free cAMP levels. Moreover, cAMP dynamics in the midpiece and principal piece of the flagellum are distinctively different. The sole cAMP source in the flagellum is the soluble adenylate cyclase (SACY). Although bicarbonate-dependent SACY activity requires Ca(2+), basal SACY activity is suppressed by Ca(2+). Finally, we also applied the sensor to primary cilia. Our new cAMP biosensor features unique characteristics that allow gaining new insights into cAMP signaling and unravel the molecular mechanisms underlying ciliary function in vitro and in vivo.

A Fluorometric Activity Assay for Light-Regulated Cyclic-Nucleotide-Monophosphate Actuators.

As a transformative approach in neuroscience and cell biology, optogenetics grants control over manifold cellular events with unprecedented spatiotemporal definition, reversibility, and noninvasiveness. Sensory photoreceptors serve as genetically encoded, light-regulated actuators and hence embody the cornerstone of optogenetics. To expand the scope of optogenetics, ever more naturally occurring photoreceptors are being characterized, and synthetic photoreceptors with customized, light-regulated function are being engineered. Perturbational control over intracellular cyclic-nucleotide-monophosphate (cNMP) levels is achieved via sensory photoreceptors that catalyze the making and breaking of these second messengers in response to light. To facilitate discovery, engineering and quantitative characterization of such light-regulated cNMP actuators, we have developed an efficient fluorometric assay. Both the formation and the hydrolysis of cNMPs are accompanied by proton release which can be quantified with the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). This assay equally applies to nucleotide cyclases, e.g., blue-light-activated bPAC, and to cNMP phosphodiesterases, e.g., red-light-activated LAPD. Key benefits include potential for parallelization and automation, as well as suitability for both purified enzymes and crude cell lysates. The BCECF assay hence stands to accelerate discovery and characterization of light-regulated actuators of cNMP metabolism.

Circulating B-vitamins and smoking habits are associated with serum polyunsaturated Fatty acids in patients with suspected coronary heart disease: a cross-sectional study.

The long-chain polyunsaturated fatty acids are considered to be of major health importance, and recent studies indicate that their endogenous metabolism is influenced by B-vitamin status and smoking habits. We investigated the associations of circulating B-vitamins and smoking habits with serum polyunsaturated fatty acids among 1,366 patients who underwent coronary angiography due to suspected coronary heart disease at Haukeland University Hospital, Norway. Of these, 52% provided information on dietary habits by a food frequency questionnaire. Associations were assessed using partial correlation (Spearman's rho). In the total population, the concentrations of most circulating B-vitamins were positively associated with serum n-3 polyunsaturated fatty acids, but negatively with serum n-6 polyunsaturated fatty acids. However, the associations between B-vitamins and polyunsaturated fatty acids tended to be weaker in smokers. This could not be solely explained by differences in dietary intake. Furthermore, plasma cotinine, a marker of recent nicotine exposure, showed a negative relationship with serum n-3 polyunsaturated fatty acids, but a positive relationship with serum n-6 polyunsaturated fatty acids. In conclusion, circulating B-vitamins are, in contrast to plasma cotinine, generally positively associated with serum n-3 polyunsaturated fatty acids and negatively with serum n-6 polyunsaturated fatty acids in patients with suspected coronary heart disease. Further studies should investigate whether B-vitamin status and smoking habits may modify the clinical effects of polyunsaturated fatty acid intake.

Plasma choline, smoking, and long-term prognosis in patients with stable angina pectoris.

BACKGROUND: Plasma choline has been associated with cardiovascular disease and nonalcoholic steatohepatitis. DESIGN: We sought to study relations of plasma choline and its metabolite betaine to long-term risk of acute myocardial infarction (AMI) and all-cause mortality according to smoking status, in patients undergoing coronary angiography for stable angina pectoris. METHODS: Samples were obtained before angiography from 2568 patients who were subsequently randomized in the Western Norway B-Vitamin Intervention Trial (WENBIT). Hazard ratios (HR) were calculated using multivariate Cox-regression and p-values were reported for trends over quartiles. RESULTS: Plasma concentrations of choline, but not betaine, were lower in smokers, and choline was positively associated with C-reactive protein and troponin T in nonsmokers, but not in smokers (p for interaction <0.03). During a follow up of 4.8 ± 1.4 (mean ± SD) years, 8.3% suffered from AMI and 6.1% died. In the total population, choline was not associated with AMI or all-cause mortality. However, comparing the highest vs. the lowest quartiles, plasma choline was associated with increased risk of AMI in nonsmokers (HR 2.63, 95% CI 1.56 to 5.51; p for trend = 0.013) and no risk in smokers (p for interaction < 0.001). Plasma choline significantly improved discrimination and reclassification when added to established cardiovascular risk factors. Plasma betaine was not associated with either endpoint. CONCLUSIONS: In patients with stable angina pectoris, elevated plasma choline is associated with elevated troponin levels and increased risk of AMI in nonsmokers. These results motivate further research into the relation between choline metabolism, smoking, and atherothrombosis.

Regulation of Son of sevenless by the membrane-actin linker protein ezrin.

Receptor tyrosine kinases participate in several signaling pathways through small G proteins such as Ras (rat sarcoma). An important component in the activation of these G proteins is Son of sevenless (SOS), which catalyzes the nucleotide exchange on Ras. For optimal activity, a second Ras molecule acts as an allosteric activator by binding to a second Ras-binding site within SOS. This allosteric Ras-binding site is blocked by autoinhibitory domains of SOS. We have reported recently that Ras activation also requires the actin-binding proteins ezrin, radixin, and moesin. Here we report the mechanism by which ezrin modulates SOS activity and thereby Ras activation. Active ezrin enhances Ras/MAPK signaling and interacts with both SOS and Ras in vivo and in vitro. Moreover, in vitro kinetic assays with recombinant proteins show that ezrin also is important for the activity of SOS itself. Ezrin interacts with GDP-Ras and with the Dbl homology (DH)/pleckstrin homology (PH) domains of SOS, bringing GDP-Ras to the proximity of the allosteric site of SOS. These actions of ezrin are antagonized by the neurofibromatosis type 2 tumor-suppressor protein merlin. We propose an additional essential step in SOS/Ras control that is relevant for human cancer as well as all physiological processes involving Ras.

CRIS-a novel cAMP-binding protein controlling spermiogenesis and the development of flagellar bending.

The second messengers cAMP and cGMP activate their target proteins by binding to a conserved cyclic nucleotide-binding domain (CNBD). Here, we identify and characterize an entirely novel CNBD-containing protein called CRIS (cyclic nucleotide receptor involved in sperm function) that is unrelated to any of the other members of this protein family. CRIS is exclusively expressed in sperm precursor cells. Cris-deficient male mice are either infertile due to a lack of sperm resulting from spermatogenic arrest, or subfertile due to impaired sperm motility. The motility defect is caused by altered Ca(2+) regulation of flagellar beat asymmetry, leading to a beating pattern that is reminiscent of sperm hyperactivation. Our results suggest that CRIS interacts during spermiogenesis with Ca(2+)-regulated proteins that--in mature sperm--are involved in flagellar bending.

Influence of feeding and intracoronary dose on insulin-mediated relative akt phosphorylation in the porcine myocardium.

AIMS: Insulin promotes Akt-dependent prosurvival signaling and reduces experimental ischemia reperfusion injury, but its clinical impact has been limited. Further understanding of the interplay between insulin and Akt in the myocardium of relevant large animal models is needed. We aimed to investigate (1) Akt phosphorylation, (2) influence of feeding state, and (3) impact of dose on the Akt response following intracoronary insulin administration in the nonischemic porcine heart. METHODS: Pigs fed 2 h preprocedure received 0.1 U (unit) or 1.0 U of insulin in the left coronary artery and fasting pigs 0.1 U. Left and right ventricle tissues harvested 15 min postinsulin administration were analyzed for Akt phosphorylation by densitometric analyses of total Akt and phosphorylated Akt immunoblots expressed as a ratio and normalized against left auricle biopsies at baseline. RESULTS: Median relative Akt phosphorylation across all biopsy locations increased significantly from baseline in both fasting and fed animals after insulin infusion: 371.4% (P < 0.001) in the fasting-0.1 U insulin group, 202.7% (P = 0.003) in the fed-1.0 U group and 131.5% (P < 0.001) in the fed-0.1 U group. The increase was significantly higher for the fasting-0.1 U and the fed-1.0 U groups as compared with the fed-0.1 U group. Baseline serum glucose in fed and fasting pigs was 6.3 ± 0.3 versus 5.2 ± 0.4 mm (P = 0.050), respectively. CONCLUSIONS: Preexperimental feeding attenuates the median relative rise in Akt phosphorylation mediated by exogenous insulin in the porcine heart, and higher insulin doses are therefore required in fed compared with fasting animals.

Assessment of urinary betaine as a marker of diabetes mellitus in cardiovascular patients.

Abnormal urinary excretion of betaine has been demonstrated in patients with diabetes or metabolic syndrome. We aimed to identify the main predictors of excretion in cardiovascular patients and to make initial assessment of its feasibility as a risk marker of future diabetes development. We used data from 2396 patients participating in the Western Norway B-vitamin Intervention Trial, who delivered urine and blood samples at baseline, and in the majority at two visits during follow-up of median 39 months. Betaine in urine and plasma were measured by liquid-chromatography-tandem mass spectrometry. The strongest determinants of urinary betaine excretion by multiple regression were diabetes mellitus, age and estimated glomerular filtration rate; all p<0.001. Patients with diabetes mellitus (n = 264) had a median excretion more than three times higher than those without. We found a distinct non-linear association between urinary betaine excretion and glycated hemoglobin, with a break-point at 6.5%, and glycated hemoglobin was the strongest determinant of betaine excretion in patients with diabetes mellitus. The discriminatory power for diabetes mellitus corresponded to an area under the curve by receiver-operating characteristics of 0.82, and betaine excretion had a coefficient of reliability of 0.73. We also found a significant, independent log-linear relation between baseline betaine excretion and the risk of developing new diabetes during follow-up. The good discriminatory power for diabetes, high test-retest stability and independent association with future risk of new diabetes should motivate further investigation on the role of betaine excretion in risk assessment and long-term follow-up of diabetes mellitus.

Plasma dimethylglycine and risk of incident acute myocardial infarction in patients with stable angina pectoris.

OBJECTIVE: Dimethylglycine is linked to lipid metabolism, and increased plasma levels may be associated with adverse prognosis in patients with coronary artery disease. We evaluated the relationship between plasma dimethylglycine and risk of incident acute myocardial infarction in a large prospective cohort of patients with stable angina pectoris, of whom approximately two thirds were participants in a B-vitamin intervention trial. Model discrimination and reclassification when adding plasma dimethylglycine to established risk factors were obtained. We also explored temporal changes and the test-retest reliability of plasma dimethylglycine. APPROACH AND RESULTS: Four thousand one hundred fifty patients (72% men; median age 62 years) were included. Plasma dimethylglycine was associated with several traditional coronary artery disease risk factors. During a median follow-up of 4.6 years, 343 (8.3%) patients experienced an acute myocardial infarction. The hazard ratio (95% confidence interval) for acute myocardial infarction was 1.95 (1.42-2.68; P<0.001) when comparing plasma dimethylglycine quartile 4 to 1 in a Cox regression model adjusted for age, sex, and fasting status. Adjusting for traditional coronary artery disease risk factors only slightly modified the estimates, which were particularly strong among nonsmokers and among patients with serum triglyceride or apolipoprotein B100 levels ≤ median (P for interaction=0.004, 0.004, and 0.03, respectively). Plasma dimethylglycine improved discrimination and reclassification and had high test-retest reliability. CONCLUSIONS: Plasma dimethylglycine is independently related to incident acute myocardial infarction and enhances risk prediction in patients with stable angina pectoris. Our results motivate further studies on the relationship between 1-carbon metabolism and atherothrombosis. A potential interplay with lipid and energy metabolism merits particular attention.

Free carnitine and acylcarnitines in obese patients with polycystic ovary syndrome and effects of pioglitazone treatment.

OBJECTIVE: To determine fasting and insulin-stimulated levels of carnitine precursors, total and free carnitine, and acylcarnitines, and evaluate the impact of pioglitazone treatment in obese patients with polycystic ovary syndrome (PCOS). DESIGN: The present study is a secondary analysis of a previously published case-control study, followed by a double-blind randomized clinical trial. SETTING: Academic tertiary care medical center. PATIENT(S): Thirty obese premenopausal patients with PCOS and 14 healthy women. INTERVENTION(S): Sixteen weeks of blinded treatment with pioglitazone (30 mg/d) or placebo. MAIN OUTCOME MEASURE(S): Total and free carnitine and acylcarnitines. RESULT(S): Contrary to controls, patients with PCOS were characterized with slightly lower levels of fasting total and free carnitine, its precursors, and derivatives. Total and free carnitine correlated inversely to sex hormone-binding globulin (SHBG) in patients with PCOS, whereas no associations were found between acylcarnitines and androgenes. Insulin stimulation-induced changes in the levels of total and free carnitine, carnitine precursors, and acylcarnitines in the PCOS group followed the same trends as in the control group. Pioglitazone treatment significantly increased fasting levels of serum-free carnitine, propionyl carnitine, and total carnitine. The analysis of between group differences revealed significant changes in the isovaleryl carnitine levels and lipid oxidation rates after pioglitazone treatment compared with placebo. CONCLUSION(S): Acute insulin stimulation was associated with increased serum levels of free carnitine in both patients and healthy controls. Treatment with pioglitazone is able to redistribute free fatty acids from insulin-sensitive tissues, diminish demand for carnitine, and influence the overall carnitine turnover. CLINICAL TRIAL REGISTRATION NUMBER: NCT00145340.

Differential regulation by cyclic nucleotides of the CNGA4 and CNGB1b subunits in olfactory cyclic nucleotide-gated channels.

Olfactory cyclic nucleotide-gated (CNG) ion channels are essential contributors to signal transduction of olfactory sensory neurons. The activity of the channels is controlled by the cyclic nucleotides guanosine 3',5'-monophosphate (cGMP) and adenosine 3',5'-monophosphate (cAMP). The olfactory CNG channels are composed of two CNGA2 subunits, one CNGA4 and one CNGB1b subunit, each containing a cyclic nucleotide-binding domain. Using patch-clamp fluorometry, we measured ligand binding and channel activation simultaneously and showed that cGMP activated olfactory CNG channels not only by binding to the two CNGA2 subunits but also by binding to the CNGA4 subunit. In a channel in which the CNGA2 subunits were compromised for ligand binding, cGMP binding to CNGA4 was sufficient to partly activate the channel. In contrast, in heterotetrameric channels, the CNGB1b subunit did not bind cGMP, but channels with this subunit showed activation by cAMP. Thus, the modulatory subunits participate actively in translating ligand binding to activation of heterotetrameric olfactory CNG channels and enable the channels to differentiate between cyclic nucleotides.

How subunits cooperate in cAMP-induced activation of homotetrameric HCN2 channels.

Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels are tetrameric membrane proteins that generate electrical rhythmicity in specialized neurons and cardiomyocytes. The channels are primarily activated by voltage but are receptors as well, binding the intracellular ligand cyclic AMP. The molecular mechanism of channel activation is still unknown. Here we analyze the complex activation mechanism of homotetrameric HCN2 channels by confocal patch-clamp fluorometry and kinetically quantify all ligand binding steps and closed-open isomerizations of the intermediate states. For the binding affinity of the second, third and fourth ligand, our results suggest pronounced cooperativity in the sequence positive, negative and positive, respectively. This complex interaction of the subunits leads to a preferential stabilization of states with zero, two or four ligands and suggests a dimeric organization of the activation process: within the dimers the cooperativity is positive, whereas it is negative between the dimers.

The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm.

In the oviduct, cumulus cells that surround the oocyte release progesterone. In human sperm, progesterone stimulates a Ca(2+) increase by a non-genomic mechanism. The Ca(2+) signal has been proposed to control chemotaxis, hyperactivation and acrosomal exocytosis of sperm. However, the underlying signalling mechanism has remained mysterious. Here we show that progesterone activates the sperm-specific, pH-sensitive CatSper Ca(2+) channel. We found that both progesterone and alkaline pH stimulate a rapid Ca(2+) influx with almost no latency, incompatible with a signalling pathway involving metabotropic receptors and second messengers. The Ca(2+) signals evoked by alkaline pH and progesterone are inhibited by the Ca(v) channel blockers NNC 55-0396 and mibefradil. Patch-clamp recordings from sperm reveal an alkaline-activated current carried by mono- and divalent ions that exhibits all the hallmarks of sperm-specific CatSper Ca(2+) channels. Progesterone substantially enhances the CatSper current. The alkaline- and progesterone-activated CatSper current is inhibited by both drugs. Our results resolve a long-standing controversy over the non-genomic progesterone signalling. In human sperm, either the CatSper channel itself or an associated protein serves as the non-genomic progesterone receptor. The identification of CatSper channel blockers will greatly facilitate the study of Ca(2+) signalling in sperm and help to define further the physiological role of progesterone and CatSper.

Systemic markers of interferon-γ-mediated immune activation and long-term prognosis in patients with stable coronary artery disease.

OBJECTIVE: Interferon γ (IFN-γ) is centrally involved in atherosclerosis-related inflammation, but its activity cannot be reliably assessed by systemic measurements. In activated macrophages, IFN-γ stimulates production of neopterin and conversion of tryptophan to kynurenine. We evaluated the relationships of plasma neopterin and plasma kynurenine:tryptophan ratio (KTR) to long-term prognosis in patients with stable angina pectoris and angiographically verified significant coronary artery disease. METHODS AND RESULTS: Samples were obtained from 2380 patients with a mean age of 63.7 years; 77.3% were men. During a median follow-up of 56 months, 10.8% of patients experienced a major coronary event (MCE), and 9.5% died. For MCE, each SD increment of neopterin and KTR (logarithmically transformed) was associated with multivariable adjusted hazard ratios and 95% CIs of 1.28 (1.10 to 1.48) and 1.28 (1.12 to 1.48), respectively. The corresponding hazard ratios (95% CIs) for all-cause mortality were 1.40 (1.21 to 1.62) (neopterin) and 1.23 (1.06 to 1.43) (KTR). CONCLUSIONS: In patients with stable angina pectoris, systemic markers of IFN-γ activity, plasma neopterin, and plasma KTR provide similar risk estimates for MCE and mortality. Our results support experimental data linking IFN-γ to acute atherosclerotic complications.

Serum osteoprotegerin levels and long-term prognosis in patients with stable angina pectoris.

OBJECTIVES: Osteoprotegerin (OPG) is a member of the tumor necrosis factor superfamily with pleiotropic effects on bone metabolism, endocrine function and the immune system. Circulating OPG levels are elevated in cardiovascular disease (CVD). We assessed serum OPG as predictor of long-term prognosis in patients with suspected stable angina pectoris (SAP) undergoing elective coronary angiography. METHODS: Samples were obtained from 1025 patients (median [25th, 75th percentile] age 62 [54, 70] years, 71.9% men). At inclusion, 43.2% of patients had single or double vessel disease, whereas 34.3% had triple vessel disease. RESULTS: During a median follow-up of 73 months, 11.0% of patients died, 5.9% died from CVD and 10.0% experienced an acute myocardial infarction (MI). In univariable analyses, strong associations were observed between OPG concentrations and all-cause mortality, CVD mortality and the incidence of MI (fatal or nonfatal). However, adjustment for conventional risk factors attenuated the risk estimates which were no longer significant, except for the subgroup with levels above the 90th percentile. For decile 10 versus deciles 1-9 of serum OPG, the following multivariable hazard ratios (95% confidence intervals) were observed: All-cause mortality: 1.94 (1.18, 3.18), p=0.01; CVD mortality: 2.29 (1.16, 4.49), p=0.02; and MI: 1.76 (1.02, 3.06), p=0.04. CONCLUSION: In patients with SAP, elevated serum OPG is associated with increased risk of all-cause mortality, CVD mortality and MI, but independent effects are mainly confined to levels above the 90th percentile.