Exenatide decreases liver fat content and epicardial adipose tissue in patients with obesity and type 2 diabetes: a prospective randomized clinical trial using magnetic resonance imaging and spectroscopy.

AIM: To conduct a prospective randomized trial to investigate the effect of glucagon-like peptide-1 (GLP-1) analogues on ectopic fat stores. METHODS: A total of 44 obese subjects with type 2 diabetes uncontrolled on oral antidiabetic drugs were randomly assigned to receive exenatide or reference treatment according to French guidelines. Epicardial adipose tissue (EAT), myocardial triglyceride content (MTGC), hepatic triglyceride content (HTGC) and pancreatic triglyceride content (PTGC) were assessed 45 min after a standardized meal with 3T magnetic resonance imaging and proton magnetic resonance spectroscopy before and after 26 weeks of treatment. RESULTS: The study population had a mean glycated haemoglobin (HbA1c) level of 7.5 ± 0.2% and a mean body mass index of 36.1 ± 1.1 kg/m(2) . Ninety five percent had hepatic steatosis at baseline (HTGC ≥ 5.6%). Exenatide and reference treatment led to a similar improvement in HbA1c (-0.7 ± 0.3% vs. -0.7 ± 0.4%; p = 0.29), whereas significant weight loss was observed only in the exenatide group (-5.5 ± 1.2 kg vs. -0.2 ± 0.8 kg; p = 0.001 for the difference between groups). Exenatide induced a significant reduction in EAT (-8.8 ± 2.1%) and HTGC (-23.8 ± 9.5%), compared with the reference treatment (EAT: -1.2 ± 1.6%, p = 0.003; HTGC: +12.5 ± 9.6%, p = 0.007). No significant difference was observed in other ectopic fat stores, PTGC or MTGC. In the group treated with exenatide, reductions in liver fat and EAT were not associated with homeostatic model assessment of insulin resistance index, adiponectin, HbA1c or fructosamin change, but were significantly related to weight loss (r = 0.47, p = 0.03, and r = 0.50, p = 0.018, respectively). CONCLUSION: Our data indicate that exenatide is an effective treatment to reduce liver fat content and epicardial fat in obese patients with type 2 diabetes, and these effects are mainly weight loss dependent.

Ectopic fat storage in the pancreas using 1H-MRS: importance of diabetic status and modulation with bariatric surgery-induced weight loss.

OBJECTIVES: Recent literature suggests that ectopic fat deposition in the pancreas may contribute to endocrine and exocrine organ dysfunction, such as type 2 diabetes (T2D), pancreatitis or pancreatic cancer. The aim of this study was to determine factors associated with pancreatic triglyceride content (PTGC), and to investigate the impact of bariatric surgery on ectopic fat pads, pancreatic fat (PTGC) and hepatic fat (HTGC). SUBJECTS: In all, 45 subjects (13 lean, 13 obese nondiabetics and 19 T2D, matched for age and gender) underwent 1H-magnetic resonance spectroscopy, computed tomography of the visceral abdominal fat, metabolic and lipidomic analysis, including insulin-resistance homeostasis model assessment (HOMA-IR), insulin-secretion homeostasis model assessment (HOMA-B) and plasma fatty-acid composition. Twenty obese subjects were reassessed 6 months after the bariatric surgery. RESULTS: PTGC was significantly higher in type 2 diabetic subjects (23.8±3.2%) compared with obese (14.0±3.3; P=0.03) and lean subjects (7.5±0.9%; P=0.0002). PTGC remained significantly associated with T2D after adjusting for age and sex (ß=0.47; P=0.004) or even after adjusting for waist circumference, triglycerides and HOMA-IR (ß=0.32; P=0.04). T2D, C18:1n-9 (oleic acid), uric acid, triglycerides and plasminogen activator inhibitor-1 were the five more important parameters involved in PTGC prediction (explained 80% of PTGC variance). Bariatric surgery induced a huge reduction of both HTGC (-51.2±7.9%) and PTGC (-43.8±7.0%) reaching lean levels, whereas body mass index remained greatly elevated. An improvement of insulin resistance HOMA-IR and no change in HOMA-B were observed after bariatric surgery. The PTGC or HTGC losses were not correlated, suggesting tissue-specific mobilization of these ectopic fat stores. CONCLUSION: Pancreatic fat increased with T2D and drastically decreased after the bariatric surgery. This suggests that decreased PTGC may contribute to improved beta cell function seen after the bariatric surgery. Further, long-term interventional studies are warranted to examine this hypothesis and to determine the degree to which ectopic fat mobilization may mediate the improvement in endocrine and exocrine pancreatic functions.

Assessment of epicardial fat volume and myocardial triglyceride content in severely obese subjects: relationship to metabolic profile, cardiac function and visceral fat.

OBJECTIVE: To assess epicardial fat volume (EFV), myocardial TG content (MTGC) and metabolic profile in severely obese patients, and to determine whether ectopic fat depots are linked to metabolic disorders or myocardial function. RESEARCH DESIGN AND METHODS: Sixty-three subjects with normal LV function and no coronary artery disease, including 33 lean (BMI: 21.4 ± 2.0 kg m(-2)) and 30 obese (BMI: 41.8 ± 6 kg m(-2)) patients, underwent 3-T cardiovascular MRI, and anthropometric, biological and visceral abdominal fat (VAT) assessments. EFV was measured by short-axis slice imaging and myocardial (intra-myocellular) TG content was measured by proton magnetic resonance spectroscopy. RESULTS: EFV and MTGC were positively correlated (r=0.52, P<0.0001), and were both strongly correlated with age, BMI, waist circumference and VAT, but not with severity of obesity. EFV and MTGC were significantly higher in obese patients than in lean controls (141 ± 18 versus 79 ± 7 ml, P=0.0001; 1.0 ± 0.1 versus 0.6 ± 0.1%, P=0.01, respectively), but some differences were found between the two cardiac depots: EFV was higher in diabetic obese subjects as compared with that in non-diabetic obese subjects (213 ± 34 versus 141 ± 18 ml, P=0.03), and was correlated with parameters of glucose tolerance (fasting plasma glucose, insulin and HOMA-IR), whereas MTGC was not. EFV and MTGC were both associated with parameters of lipid profile or inflammation (TGs, CRP). Remarkably, this was VAT-dependent, as only VAT remained independently associated with metabolic parameters (P<0.01). Concerning myocardial function, MTGC was the only parameter independently associated with stroke volume (ß=-0.38, P=0.01), suggesting an impact of cardiac steatosis in cardiac function. CONCLUSIONS: These data show that VAT dominates the relationship between EFV, MTGC and metabolic measures, and uncover specific partitioning of cardiac ectopic lipid deposition.

Endovascular therapies for hepatic artery stenosis post liver transplantation.

PURPOSE: To evaluate primary patency at 12 months after endovascular therapies in hepatic artery stenosis. METHODS: A retrospective review of all endovascular interventions for hepatic artery stenosis (HAS) after liver transplantation that occurred between June 2013 and November 2020 was performed at a single institution in France. Follow up occurred from 1 month to 4 years (median 15 months). The treatment consisted of dilation with a balloon or stent. We analyzed short-term (technical success and complications) and long-term outcomes (liver function, arterial patency, graft survival at 12 months (GS), and reintervention). We also compared percutaneous balloon angioplasty (PBA) with stent placement. PBA alone was used if < 30% residual stenosis of the hepatic artery was achieved. Stenting was performed if there was greater than 30% residual stenosis and in the case of complications (dissection or rupture). RESULTS: A total of 18 stenoses were suspected on the basis of routine surveillance duplex ultrasound imaging (peak systolic velocity > 200 cm/s, systolic accelerating time > 10 ms and resistive index < 0.5), all of which were confirmed by angio CT, but only 17 were confirmed by angiography. Seventeen patients were included (14 males, mean age 57 years; and three females, mean age 58 years). Interventions were performed in 17 cases (95%) with PBA only (5/17), stent only (5/17) or both (4/17). Immediate technical success was 100%. Major complications occurred in 1 of 17 cases (5.8%), consisting of target vessel dissection. The analysis of the three (groups PBA only, stent only or both) showed the same procedural success (100%), GS (100%) and normal liver function after the procedures but different rates of complications (20% vs. 0% vs. 0%), arterial patency at 12 months (60% vs. 80% vs. 85%) (p = 0.4), early stenosis (40% vs. 80% vs. 0%) or late stenosis (60% vs. 20% vs. 100%) and requirement for reintervention (40% vs. 20% vs. 14%) (p = 0.56). CONCLUSION: This study suggests that PBA, stent, or both procedures show the same primary patency at 12 months. It is probably not a definitive answer, but these treatments are safe and effective for extending graft survival in the context of graft shortages.

Astrocytic protection of spinal motor neurons but not cortical neurons against loss of Als2/alsin function.

Three neurodegenerative diseases affecting upper and/or lower motor neurons have been associated with loss of ALS2/Alsin function: juvenile amyotrophic lateral sclerosis, primary lateral sclerosis and infantile-onset ascending hereditary spastic paralysis. The distinct neuronal vulnerability and the role of glia in these diseases remains, however, unclear. We here demonstrate that alsin-depleted spinal motor neurons can be rescued from defective survival and axon growth by co-cultured astrocytes. The astrocytic rescue is mediated by a soluble protective factor rather than by cellular contact. Cortical neurons are intrinsically as vulnerable to alsin depletion as spinal motor neurons but cannot be rescued by co-cultured astrocytes. To our knowledge, these data provide the first example of non-cell-autonomous glial effects in a recessive form of motor neuron disease and a potential rationale for the higher vulnerability of upper versus lower motor neurons in ALS2/Alsin-linked disorders.

Quantification of diffuse myocardial fibrosis using CMR extracellular volume fraction and serum biomarkers of collagen turnover with histologic quantification as standard of reference.

PURPOSE: To compare the assessment of diffuse interstitial myocardial fibrosis in valvular diseases using cardiac magnetic resonance (CMR) extracellular volume fraction (ECV) quantification and serum biomarkers of collagen turnover using results of myocardial biopsy as standard of reference. MATERIALS AND METHODS: This prospective monocentric study included consecutive patients before aortic valvular replacement. All patients underwent: i), 1.5T CMR with pre and post contrast T1 mapping sequence and ECV computation; ii), serum quantification of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) and iii), myocardial biopsies were collected during surgery to assess collagen volume fraction (CVF). Patients with coronary artery disease were excluded. Correlation between native T1, ECV, CVF and serum biomarkers were assessed using Pearson correlation test. Agreement between basal anteroseptal ECV with global ECV was assessed using Bland-Altman test. RESULTS: Twenty-one patients, 16 with aortic stenosis and 5 with aortic regurgitation were included. There were 12 men and 9 women with a mean age of 74.1±6.8 (SD) years (range: 32-84 years). Mean global ECV value was 26.7±2.7 (SD) % (range: 23.4-32.5%) and mean CVF value was 12.4±9.7% (range: 3.2-25.7%). ECV assessed at the basal anteroseptal segment correlated moderately with CVF (r=0.6; P=0.0026). There was a strong correlation and agreement between basal anteroseptal ECV and global ECV, (r=0.8; P<0.0001; bias 5.4±6.1%) but no correlation between global ECV and CVF (r=0.5; P=0.10). Global ECV poorly correlated with serum TIMP-1 (r=0.4; P=0.037) and MMP-2 (r=0.4; P=0.047). No correlation was found between serum biomarkers and basal anteroseptal- ECV or native T1. CONCLUSION: In patients with severe aortic valvulopathy, diffuse myocardial fibrosis assessed by anterosepto-basal ECV correlates with histological myocardial fibrosis. Anteroseptobasal ECV strongly correlates with global ECV, which poorly correlates with TIMP-1 and MMP-2, serum biomarkers involved in the progression of heart failure.

[Mechanisms of delayed myocardial enhancement and value of MR and CT contrast materials in the evaluation of myocardial viability]. / Mécanismes du rehaussement tardif myocardique et apport des produits de contraste en IRM et scanner dans le diagnostic de viabilité myocardique.

The purpose of this article is to present a brief theoretical review of the models characterizing delayed myocardial enhancement applicable to both MR and CT imaging, review the different characteristics of commercially available gadolinium-based and iodinated contrast materials, and summarize the literature on the potential value of dedicated MR imaging contrast currently in development for the diagnosis of myocardial viability. The intensity of myocardial enhancement following infarction is related to two factors: expansion of the interstitial volume (15+/-2% in normal myocardium and 80+/-3% within necrosis) secondary to cell necrosis and perfusion abnormalities due to the absence of revascularization or lesions to the microcirculation. A kinetic model of contrast material properties within myocardium could be constructed from Kety's equation with regards to enhancement within the different myocardial tissues (viable myocardium, necrotic myocardium, fibrosis, no-reflow zones, stunned or hibernating myocardium). This model can be applied to both CT and MR since clinically available contrast agents are extracellular, inert and kinetically comparable. The development of dedicated contrast agents for viability and necrosis or molecular contrast agents open new horizons for preclinical research.

[Delayed myocardial enhancement: Optimizing the MR imaging protocol]. / Comment j'optimise la technique d'IRM à la recherche d'un rehaussement tardif?

The purpose of this article is to 1) review the basic models characterizing myocardial enhancement on MR and CT, 2) review the main characteristics of available iodinated and Gadolinium-based contrast agents and, 3) review the literature on emerging MR contrast agents to assess myocardial viability. The intensity of enhancement following infarction is the result of two processes: 1) the increased interstitial space (15 + or - 2% in normal myocardium and 80 + or - 3% in necrotic tissue) secondary to cell necrosis and 2) perfusion abnormalities secondary to absent revascularization or impaired microvascularization. The equation described by Kety was used to create models of contrast material kinetics within myocardium or enhancement of the different components of the myocardium (viable myocardium, necrosed myocardium, fibrosis, with no-reflow zone, hibernating or stunned myocardium).

[Urokinase in the management of occluded PICC lines]. / Utilisation de l'urokinase dans le traitement des occlusions de PICC-lines.

PURPOSE: To determine the efficacy and safety of urokinase in the management of occluded PICC lines. MATERIALS AND METHODS: A total of 587 PICC lines were placed over an 11 month period. During this period, 28 PICC lines (4.8%) became occluded: 12 occluded PICC lines were successfully managed by simple flushing with normal saline while 16 PICC lines were thrombolyzed with urokinase. RESULTS: After urokinase, 93.8% (15/16) of occluded PICC lines were completely patent. A single infusion of urokinase, 20,000 IU over 30 minutes, was used in all cases. No secondary occlusion or complication was noted after urokinase. CONCLUSION: Urokinase is effective and safe to restore patency to occluded PICC lines. The procedure is simple, and could be performed at the bedside by nursing staff after medical prescription. It is an alternative to over the wire PICC line exchange, that could reduce the risk of complication related to manipulations, patient discomfort and cost.

Cytometry-based analysis of HLA-G functions according to ILT2 expression.

HLA-G was described as a molecule inhibiting NK and T cells functions through its receptor, ILT2. However, most functional studies of HLA-G were so far performed on heterogeneous immune populations and regardless of ILT2 expression. This may lead to an underestimation of the effect of HLA-G. Thus, considering the immune subpopulations sensitive to HLA-G remained an important issue in the field. Here we present a new cytometry assay to evaluate HLA-G effects on both NK and CD8+ T cell cytotoxic functions. Using flow cytometry allows for the comparison of HLA-G function on multiple subsets and multiple functions in the same time. In particular, we sharpen the analysis by specifically studying the immune subpopulations expressing HLA-G receptor ILT2. We focused our work on: IFN-gamma production and cytotoxicity (CD107a expression) by CD8+ T cells and NK cells expressing or not ILT2. We compared the expression of these markers in presence of target cells, expressing or not HLA-G1, and added a blocking antibody to reverse HLA-G inhibition. This new method allows for the discrimination of cell subsets responding and non-responding to HLA-G1 in one tube. We confirm that HLA-G-specifically inhibits the ILT2+ CD8+ T cell and ILT2+ NK cell subsets but not ILT2-negative ones. By blocking HLA-G/ILT2 interaction using an anti-ILT2 antibody we restored the cytotoxicity level, corroborating the specific inhibition of HLA-G1. We believe that our methodology enables to investigate HLA-G immune functions easily and finely towards other immune cell lineages or expressing other receptors, and might be applied in several pathological contexts, such as cancer and transplantation.

Pediatric cardiac computed tomography angiography: Expert consensus from the Filiale de Cardiologie Pédiatrique et Congénitale (FCPC) and the Société Française d'Imagerie Cardiaque et Vasculaire diagnostique et interventionnelle (SFICV).

This article was designed to provide a pediatric cardiac computed tomography angiography (CCTA) expert panel consensus based on opinions of experts of the Société Française d'Imagerie Cardiaque et Vasculaire diagnostique et interventionnelle (SFICV) and of the Filiale de Cardiologie Pédiatrique Congénitale (FCPC). This expert panel consensus includes recommendations for indications, patient preparation, CTA radiation dose reduction techniques, and post-processing techniques. The consensus was based on data from available literature (original papers, reviews and guidelines) and on opinions of a group of specialists with extensive experience in the use of CT imaging in congenital heart disease. In order to reach high potential and avoid pitfalls, CCTA in children with congenital heart disease requires training and experience. Moreover, pediatric cardiac CCTA protocols should be standardized to acquire optimal images in this population with the lowest radiation dose possible to prevent unnecessary radiation exposure. We also provided a suggested structured report and a list of acquisition protocols and technical parameters in relation to specific vendors.

Prostatic artery embolization using three-dimensional cone-beam computed tomography.

PURPOSE: The purpose of this study was to report the use of three-dimensional (3D) cone-beam computed tomography (CBCT) for prostatic artery embolization (PAE) in patients with benign prostatic hypertrophy (BPH). MATERIALS AND METHODS: Twenty-three consecutive men who underwent PAE using 3D CBCT from June 2016 to September 2018, were retrospectively included in this observational single-center study. There were 23 men with a mean age of 73±12 (SD) years (range: 52-94years) with moderate to severe lower urinary tract symptoms (mean international prostate symptom score, 21±5.7 [SD]; range: 9-30) due to BPH (mean prostate weight, 100g±63 [SD]; range: 30-250g). PAEs were analyzed with respect to procedure time, fluoroscopy time, technical success, complications and dosimetric indices. RESULTS: The mean catheterization time of the prostatic artery from the internal iliac artery was 17.3±12.5 (SD) min (range: 8-57min) on the right side and 23.6±14.9 (SD) min (range: 6-54min) on the left side. A technical success was achieved in 21 patients (21/23; 91%). PAE was bilateral in 14 patients (14/21; 66%) and unilateral in 7 patients (7/21; 33%). No occurrence of non-target embolization was reported. The mean dose area product was 146.7±47.9 (SD) Gy.cm2 (range: 54-254Gy.cm2) and mean cumulative air kerma was 771.4±333.3 (SD) mGy; range: 280-1560 mGy. The mean fluoroscopy time was 42.3±23.1 (SD) min (range: 19.4-118.2min). CONCLUSION: 3D CBCT is a useful tool to identify the prostatic arteries and facilitates catheterization of prostatic arteries with an acceptable level of radiation exposure.

Cardiac magnetic resonance assessment of left ventricular dilatation in chronic severe left-sided regurgitations: comparison with standard echocardiography.

PURPOSE: The purpose of this study was to investigate the potential additional value of cardiac magnetic resonance (CMR) in the assessment of left ventricular (LV) dilatation and dysfunction by comparison to standard echocardiography in patients with chronic left-sided valvular regurgitation. MATERIALS AND METHODS: We prospectively enrolled patients with chronic severe mitral regurgitation (MR) or aortic regurgitation (AR). They underwent standard echocardiography and CMR using aortic flow and LV-function sequences. LV dilatation or dysfunction was assessed with each technique, based on thresholds used for surgery indication. Reference regurgitation severity was defined following previously reported CMR-based regurgitant volume thresholds. RESULTS: A total of 71 patients with chronic severe MR (n=44) or severe AR (n=27) were prospectively included. There were 60 men and 11 women with a mean age of 61±14 (SD) years (range: 18-83 years). CMR-based regurgitation severity was significantly greater in the LV dysfunction group when assessed with CMR (MR, P=0.011; AR, P=0.006) whereas it was not different when LV dysfunction was assessed using standard echocardiography. Among standard echocardiography and CMR volumetric indices, CMR-derived end-diastolic volume showed the best ability to predict regurgitation severity (area under the curve [AUC]=0.78 for MR; AUC=0.91 for AR). Diagnostic thresholds identified on receiver operating characteristics-curve analysis were lower than those of current European recommendations and closer to North-American guidelines. CONCLUSION: CMR assessment of LV end-diastolic volume in chronic severe left-sided regurgitations is more reliably associated with CMR-based regurgitant volume by comparison with standard echocardiography diameter. CMR may provide useful evaluation before surgery decision for severe asymptomatic regurgitations.

Quantification of right ventricular extracellular volume in pulmonary hypertension using cardiac magnetic resonance imaging.

PURPOSE: The purpose of this prospective study was to assess the value of biventricular extracellular volume (ECV) in pre-capillary pulmonary hypertension (PH) obtained using cardiac magnetic resonance imaging (CMR) and to correlate ECV with markers of prognosis such as strain echocardiography and blood biomarkers of fibrosis. MATERIALS AND METHODS: Twelve patients with PH (6 men, 6 women; mean age=50±16 [SD] years; age range: 22-73 years) underwent the same day: (i), transthoracic echocardiography including measurement of right ventricular (RV) fractional shortening (RVfs), tricuspid annular plane systolic excursion (TAPSE), maximal tricuspid annular velocity, RV global and segmental deformation; (ii), right heart catheterization measuring pulmonary arterial pressures (inmmHg) and cardiac output (inL/min); (iii), CMR at 1.5-T measuring RV volumes and ejection fraction; (iv), native and 15min post-contrast T1 mapping using modified look-locker inversion-recovery sequence; and (v), serum quantification of two biomarkers of collagen turnover and hematocrit. Non-parametric Mann-Whitney tests were used to search for differences between categorical variables. Spearman correlation test was used for search for correlation between quantitative values. RESULTS: Global RV ECV was 34%±4.2 (SD) for our entire population. A significant correlation was found between RV ECV and RVfs (r=0.6; P=0.026), S wave velocity (r=0.7; P=0.009), TAPSE (r=0.6; P=0.040) and RV systolic ejection fraction on CMR (r=0.6; P=0.04). There were no correlations between the ECV values in the lateral wall of the RV and in the septum (r=0.4; P=0.206). A significant correlation was found between septal ECV and 2D septal strain (r=0.7; P=0.013). CONCLUSION: ECV in PH as obtained using CMR appears to correlate with known echocardiographic prognostic markers and more specifically with the markers, which assess RV systolic function.

Joint Position Paper of the Working Group of Pacing and Electrophysiology of the French Society of Cardiology (SFC) and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) on magnetic resonance imaging in patients with cardiac electronic implantable devices.

Magnetic resonance imaging (MRI) has become the reference imaging for the management of a large number of diseases. The number of MR examinations increases every year, simultaneously with the number of patients receiving a cardiac electronic implantable device (CEID). A CEID was considered an absolute contraindication for MRI for years. The progressive replacement of conventional pacemakers and defibrillators by MR-conditional CEIDs and recent data on the safety of MRI in patients with "MR-nonconditional" CEIDs have progressively increased the demand for MRI in patients with a CEID. However, some risks are associated with MRI in CEID carriers, even with "MR-conditional" devices because these devices are not "MR-safe". A specific programing of the device in "MR-mode" and monitoring patients during MRI remain mandatory for all patients with a CEID. A standardized patient workflow based on an institutional protocol should be established in each institution performing such examinations. This joint position paper of the Working Group of Pacing and Electrophysiology of the French Society of Cardiology and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) describes the effect and risks associated with MRI in CEID carriers. We propose recommendations for patient workflow and monitoring and CEID programming in MR-conditional, "MR-conditional nonguaranteed" and MR-nonconditional devices.

Catalytic site components common to both splicing steps of a group II intron.

The splicing of group II introns occurs in two steps involving substrates with different chemical configurations. The question of whether these two steps are catalyzed by a single or two separate active sites is a matter of debate. Here, certain bases and phosphate oxygen atoms at conserved positions in domain V of a group II self-splicing intron are shown to be required for catalysis of both splicing steps. These results show that the active sites catalyzing the two steps must, at least, share common components, ruling out the existence of two completely distinct active sites in group II introns.

Efficient trans-splicing of a yeast mitochondrial RNA group II intron implicates a strong 5' exon-intron interaction.

The reaction mechanism for self-splicing introns requires the existence of a 5' exon binding site on the intron. Experimental evidence is now presented consistent with the existence of such a binding site by demonstrating efficient and accurate trans-self-splicing of a yeast mitochondrial group II intron. Partial and complete trans-splicing reactions take place in the absence of branch formation, part of the usual pathway of nuclear splicing and group II self-splicing. In addition to indicating the existence of a 5' exon binding site on the intron, the results have mechanistic implications for group II self-splicing and perhaps for nuclear splicing as well.

[Comparison of 64 MDCT coronary CTA and coronary angiography in the detection of coronary artery stenosis in low risk patients with stable angina and acute coronary syndrome]. / Comparaison du scanner 64-détecteurs et de la coronarographie dans la détection des sténoses coronariennes chez des patients porteurs d'angor stable et de syndrome coronaire aigu à bas risques.

PURPOSE: To determine the accuracy of 64 MDCT coronary CTA (CCTA) compared to coronary angiography in low risk patients with stable angina and acute coronary syndrome and determine the number of significant coronary artery stenoses ( 50%) in these patients. Materials and methods. Fifty-five patients underwent CCTA using a 32 MDCT unit with z flying focus allowing the acquisition of 64 slices of 0.6 mm thickness as well as coronary angiography (gold standard). Nine patients were excluded due to prior coronary artery bypass surgery (n=4), insufficient breath hold (n=3), calcium scoring>1000 (n=1) and delay between both examinations over 4 months (n=1). Forty-six patients: 27 males and 19 females were included. CCTA results were compared to coronary angiography per segment and artery with threshold detection of stenoses 50%. The degree of correlation between both examinations was performed using a regression analysis with a Pearson correlation coefficient<0.05 considered significant. RESULTS: The overall accuracy of CCTA was 90%; limitations related to the presence of calcifications, motion artifacts or insufficient vessel opacification. The correlation for all analyzed segments was 96.4%. Thirty-eight of 50 significant stenoses seen on coronary angiography were correctly detected on CCTA. Sensitivity, specificity, PPVC and NPV for detection of stenoses 50% were 76%, 98.3%, 80.3% and 97.7% respectively. Evaluation per segment had a NPV of 96.8% (interventricular and diagonal segments) to 100% (main trunk). CONCLUSION: Our results for specificity and NPV are similar to reports from the literature. This suggests that CCTA in this clinical setting may replace coronary angiography.

[Technological advances in cardiac CT]. / Evolutions technologiques en tomodensitométrie cardiaque.

The SFR-SFC presents guidelines dedicated to cardiac and coronary imaging using CT in the area of indications, technological requirement including both hardware and software, patient conditioning, CT protocols and related results concerning radiation dose, image quality and diagnostic value. These guidelines are based either on up-dated medical literature proofs and/or on expert consensus.

Self-splicing group II and nuclear pre-mRNA introns: how similar are they?

The splicing pathway of pre-mRNA introns bears similarities to that of the group II introns, some members of which undergo self-splicing. The snRNAs may provide the pre-mRNA introns with RNA structures in trans comparable to those available in cis in group II introns. This article examines the available evidence for the hypothesis that the catalysis of these two splicing pathways is fundamentally equivalent.